PAETE.ORG FORUMS
Paetenians Home on the Net

HOME | ABOUT PAETE | USAP PAETE MUNISIPYO  | MEMBERS ONLY  | PICTORIAL PAETE | SINING PAETE  | LINKS  |

FORUM GUIDELINES
please read before posting

USAP PAETE Forum Index USAP PAETE
Discussion Forums for the people of Paete, Laguna, Philippines
 
 FAQFAQ   SearchSearch    UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

(Bio) Fish Evolve A Longer Lifespan

 
Post new topic   Reply to topic   printer-friendly view    USAP PAETE Forum Index -> Science Lessons Forum
View previous topic :: View next topic  
Author Message
adedios
SuperPoster


Joined: 06 Jul 2005
Posts: 5060
Location: Angel C. de Dios

PostPosted: Tue Dec 27, 2005 3:29 pm    Post subject: (Bio) Fish Evolve A Longer Lifespan Reply with quote






Fish Evolve A Longer Lifespan By Evolving A Longer Reproductive Period, Researchers Find
Source: University of California - Riverside
Date: 2005-12-27

A UC Riverside-led research team has found that as some populations of an organism evolve a longer lifespan, they do so by increasing only that segment of the lifespan that contributes to "fitness" – the relative ability of an individual to contribute offspring to the next generation.

Focusing on guppies, small fresh-water fish biologists have studied for long, the researchers found that guppies living in environments with a large number of predators have adapted to reproduce earlier in life than guppies from low-predation localities. Moreover, when reproduction ceases, guppies from high-predation localities are far older, on average, than guppies from low-predation localities, indicating that high-predation guppies enjoy a long "reproductive period" – the time between first and last reproduction.

"In earlier work, we showed that guppies from high predation environments have longer lifespans," said David Reznick, professor of biology. "Our new study explores how and why this happens. We found that fish from populations enjoying longer lifespans live longer because there is a selective increase in their reproductive lifespan. Indeed, theory predicts this result because only reproductive lifespan determines fitness."

Study results appear Dec. 27 in the online edition of the Public Library of Science – Biology.

The study supports the controversial hypothesis that natural selection – the process in nature by which only organisms best adapted to their environment tend to survive and pass on their genetic characters in increasing numbers to succeeding generations – introduces changes in only a specific segment of an organism's lifespan.

The researchers conducted their experiments by comparing life-history traits in 240 guppies they retrieved from high- and low-predation streams in mountains in Trinidad. In their analysis, they divided the life history into three non-overlapping segments: the age at maturity (birth to first reproduction), the reproductive lifespan (first to last reproduction) and the post-reproductive lifespan (last reproduction to death). They also devised a statistical criterion for evaluating whether or not guppies had a post-reproductive lifespan, that is, did guppies live significantly past the end of their capacity to reproduce?

"We were exploring whether or not fish have the equivalent of mammalian menopause," Reznick said. "We found that 60 percent of the fish had a significant post-reproductive lifespan, indicating that, yes, fish do have menopause. Indeed, their patterns of growing old are similar to those of mammals."

The researchers' statistical analysis also showed that regardless of which environments the guppies lived in, there were no differences among their populations in the probability of having a post-reproductive lifespan or in its duration.

"This is just what one might predict because these fish provide no care for their young," explained Reznick. "The older fish, after they stop reproducing, do not contribute to the fitness of young fish. As a result, the post-reproductive period is not influenced by natural selection. This result could be of interest to those who study menopause in humans and who have argued that post-reproductive humans can increase their own fitness by contributing to the fitness of their grandchildren and that the prolonged post-reproductive lifespan of humans is, therefore, the product of natural selection.

"But such arguments are difficult to prove by working on a single population or species. Nevertheless, our results show how it would be possible to evaluate whether or not menopause in humans has been shaped by natural selection. Appropriate comparisons, such as those between humans and apes, would help."

###

Reznick was assisted in the study by Michael Bryant of the California Institute of the Arts and Donna Holmes of the University of Idaho. The Population Biology Division of the National Research Foundation provided support.

*************************************************************
Questions to explore further this topic:

What is a fish?

http://en.wikipedia.org/wiki/Fish

Here are some of the species you will find in the Shedd Aquarium:

http://www.sheddaquarium.org/S.....m?cat_id=1

Here are some fish videos:

http://www.aquariumfish.net/pages/videos.htm

What are the different types of fish?

http://www.flmnh.ufl.edu/fish/.....Groups.htm

How do fish swim?

http://www.flmnh.ufl.edu/fish/.....wSwim.html

How do fish use adaptations?

http://www.flmnh.ufl.edu/fish/...../Adapt.htm

Here is the anatomy of bony fish and sharks:

http://www.flmnh.ufl.edu/fish/.....agrams.htm

How can we tell if a fish is a male or female?

http://www.reef.crc.org.au/res.....ishsex.htm

How do fish reproduce?

http://www.bim.ie/templates/fi.....ode_id=426
http://www.ux1.eiu.edu/~cfruf/.....system.htm

A bouillabaisse (a Mediterranean soup) of fascinating facts about marine life:

http://www.nefsc.noaa.gov/faq/
http://oceanlink.island.net/ask/fishy.html

Conservation: Apo Island in the Philippines:

http://www.sheddaquarium.org/S.....cfm?id=111

GAMES

http://www.sheddaquarium.org/S.....e.cfm?id=7
http://www.sheddaquarium.org/S.....e.cfm?id=8
http://www.sheddaquarium.org/S.....e.cfm?id=9
http://www.sheddaquarium.org/S......cfm?id=11
http://www.sheddaquarium.org/S......cfm?id=20


Last edited by adedios on Sat Jan 27, 2007 3:45 pm; edited 5 times in total
Back to top
View user's profile Send private message Visit poster's website
adedios
SuperPoster


Joined: 06 Jul 2005
Posts: 5060
Location: Angel C. de Dios

PostPosted: Wed Dec 28, 2005 11:53 am    Post subject: Fish Mating Preferences Change with Age Reply with quote

Fish Mating Preferences Change with Age
By Sara Goudarzi
Special to LiveScience
posted: 28 December 2005
07:22 am ET

A new study shows that imperfect male swordtail fish are all the rage of the mating scene among older females of their species.

Over their lifetimes, female fish switch from preferring males with symmetrical patterns to those with asymmetrical designs, a new study finds. Scientists now wonder if human mating preferences might shift with age, too.

"What this tells us is that females are most likely weighing several different factors when they choose a mate," said Molly Morris, an associate professor of biological sciences at Ohio University.

Previous studies showed females preferred mates that were symmetrical, an indicator of good genes. However, Morris’ study and several others have found that as female fish get older, their mating preferences completely reverse.

"We are hypothesizing that some other factor, like predation, could outweigh the benefit of the good genes for older, larger females," Morris told LiveScience.

Morris and her colleagues looked at two species of swordtail fish and compared the mating preferences of the young with the old. The smaller, younger females showed a significant preference for males with the same number of dark bars on both sides of their body. While larger, older, females preferred males with different numbers of markings on each side of their body.

The results show that preferences for symmetry are not necessarily driven by visual systems and cues. The study also provides more evidence that mate preferences for female fish can change over their lifetimes. Finally, females are likely optimizing several factors when they make mate choices, rather than basing their decision on whether a male has good genes to pass on to their offspring, Morris explained.

The reason for the "switch" is not yet understood. The researchers are planning experiments to determine if it’s simply part of a female’s development over the course of her lifetime, or if it is in some way due to the experiences females have. "Older, larger females will have had more mating experience," Morris said.

The results raise questions about whether the same is true of other species. Studies that have examined what male and female human's consider attractive show that both sexes find symmetrical faces more appealing. However, these studies have primarily examined young people. In one recent study, the average age of the participants was around 20.

"It will be interesting to see if the preferences of 30- and 40-year-olds are different than the 20-year-olds," Morris said. "What we look for in a mate could shift as we get older."

The study was detailed online recently by the journal Biology Letters.
Back to top
View user's profile Send private message Visit poster's website
adedios
SuperPoster


Joined: 06 Jul 2005
Posts: 5060
Location: Angel C. de Dios

PostPosted: Mon Feb 06, 2006 7:11 pm    Post subject: Sperm Cells Turned into Eggs Reply with quote

Sperm Cells Turned into Eggs
By Ker Than
LiveScience Staff Writer
posted: 06 February 2006
05:00 pm ET

Scientists have tricked male fish cells that were destined to become sperm into switching sex and becoming eggs instead.

The technique could one day be used to quickly produce animals with desired traits, speed up breeding programs and help repopulate dwindling populations of endangered species or creating sushi on demand, the researchers said.

The finding is detailed in the Feb. 7 issue of the journal for the Proceedings of the National Academy of Sciences.

Sexually indifferent cells

Scientists have long known that some fish are able to switch their sex, either spontaneously or when exposed to steroids. This led them to suspect that a subset of the population of cells in male fish that normally become sperm, called spermatogonia, might be stem cells that have the potential to become either sperm or eggs.

To test their hypothesis, the researchers isolated spermatogonia from the testes of adult rainbow trout and transplanted them into newly hatched trout of both sexes. In male hatchlings, the transplanted cells developed into sperm, while in females they developed into eggs.

The scientists are currently looking into whether eggs could be transformed into sperm. Other researchers have successfully produced sperm from mice stem cells.

Sushi on demand

The technique could be used to rapidly breed inbred strains of domestic or research animals with desired genetic traits, the researchers write.

Tokyo University's Goro Yoshizaki, the study's principal investigator, told LiveScience the technique could be used to establish surrogate breeding programs for animals such as the blue fin tuna, a fish popular for sushi and sashimi in Japan and elsewhere. Populations of the fish are declining worldwide and adult blue fin tunas are expensive and difficult to keep in captivity.

One solution, Yoshizaki said, is to isolate the spermatogonia from adult male tunas and transplant them into both male and female hatchlings of a smaller fish species, such as mackerel. Once transplanted, the germ cells would differentiate into sperm and eggs. The mackerel would then be allowed to reproduce normally, but they would produce tuna instead of mackerel.

The technique could also be used to help save endangered fish species, Goro added. A single male endangered fish could be used to repopulate an entire species.

"Even if the species is extinct, we can restore them by transplanting them into closely related species," Goro said.
Back to top
View user's profile Send private message Visit poster's website
adedios
SuperPoster


Joined: 06 Jul 2005
Posts: 5060
Location: Angel C. de Dios

PostPosted: Fri Apr 07, 2006 11:03 am    Post subject: Don't hold your breath-Carp can manage without O2 for months Reply with quote

Society for Experimental Biology
7 April 2006

Don't hold your breath: Carp can manage without oxygen for months

How long can you hold your breath? Scientists at the University of Oslo have recently discovered how the Crucian Carp, a close relative of the goldfish, is able to live for months without oxygen. The researchers hope that understanding how some animals cope with a lack of oxygen might give clues as to how to solve this problem in humans.
"Anoxia related diseases are the major causes of death in the industrialized world. We have here a situation where evolution has solved the problem of anoxic survival millions of years ago, something that medical science has struggled with for decades with limited success", says Professor Göran Nilsson who will be presenting his latest results at the Annual Meeting for the Society for Experimental Biology on Friday 7th April [session A9].

The researchers have found that this extraordinary fish can change the structure of its gills to avoid becoming anoxic. In addition its blood has a much higher affinity for oxygen than any other vertebrate, and it makes tranquilizers and produces alcohol when oxygen supplies are limited. These mechanisms allow the fish to survive for days or even months without oxygen depending on the temperature, whilst still maintaining physical activity.
Back to top
View user's profile Send private message Visit poster's website
adedios
SuperPoster


Joined: 06 Jul 2005
Posts: 5060
Location: Angel C. de Dios

PostPosted: Tue Apr 11, 2006 10:16 am    Post subject: Uncovering Sex-Change Secrets Of The Black Sea Bass Reply with quote

Uncovering Sex-Change Secrets Of The Black Sea Bass
Contact: Kirsten Weir
603-749-1565
NH Sea Grant
April 11, 2006

--------------------------------------------------------------------------------

DURHAM, N.H. -- In a former cowshed on the edge of the University of New Hampshire campus, David Berlinsky, assistant professor of zoology, peers into a big blue plastic tub. Inside, black sea bass circle slowly in the dim light. The converted barn is now an aquaculture research facility for the College of Life Sciences and Agriculture, and home to Berlinsky’s latest research.

Black sea bass feature prominently on many menus, but wild populations of the fish are in decline and their availability is limited. Because of the high demand, they’re a good candidate for aquaculture on the east coast. Except, that is, for one problem: they have a tendency to change sex unpredictably in captivity.

“In the wild, black sea bass are born as females and turn into males at around two to five years old,” Berlinsky explains. “When you bring them into captivity, they change into males more quickly.” Some captive-born fish emerge as males even before reaching adulthood, devoting energy toward reproductive development and away from growth. Such problems make breeding and growing the fish in captivity a tricky proposition.

“Black sea bass is a wonderful fish to culture and to eat,” says George Nardi, vice president and director of GreatBay Aquaculture, a commercial fish farm in Newington, NH. But the sex change problem must be tackled if fish farmers are to bring a high-quality fish to market. “We invest in our brood stocks, the parents of the young fish, much as a thoroughbred horse farm invests in mares and stallions,” he says. “It doesn’t do us much good if we always have to go out and get new females.”

With funding from NH Sea Grant, Berlinsky has teamed with Nardi and GreatBay Aquaculture to study what triggers sex reversal in black sea bass – and how to prevent it. Berlinsky and his colleagues have discovered that fish are more likely to become males if raised at constant temperatures. But temperature is hardly the only factor involved. Sex ratios and density also come into play. Berlinsky’s team found that females were more likely to change sex when no males were present in the tank. Additionally, the fish were more likely to turn into males when kept in crowded tanks.

Berlinsky is continuing his experiments to clarify the role that water temperature plays and to further understand what factors determine the initial sex of captive-born fish. He’s also collaborating with Canadian researchers to study the underlying biochemical mechanisms that cause the fish to change sex. In female fish, estrogen plays the major role, he said. In males, a steroid hormone called 11-ketotestosterone is involved. The scientists are now studying those hormones as well as the enzymes that control them.

By turning off estrogen production, Berlinsky says, he can turn a female fish into a male within a week. Giving 11-ketotestosterone to a female converts it into a male. “We’re studying the ways to control the enzymes that control sex reversal,” he explains. “We’re coming at the problem both behaviorally and biochemically.”

Though he still has details to sort out, Berlinsky believes he has already made important steps. “We have already made progress, determining optimal sex ratios and delaying sex reversal by controlling density,” he notes. “We’ve already made strides toward making black sea bass aquaculture possible.”
Back to top
View user's profile Send private message Visit poster's website
adedios
SuperPoster


Joined: 06 Jul 2005
Posts: 5060
Location: Angel C. de Dios

PostPosted: Sat Sep 30, 2006 8:13 am    Post subject: Tiny Fish Learn to Sniff Out Predators Reply with quote

Tiny Fish Learn to Sniff Out Predators

By Ker Than
LiveScience Staff Writer
posted: 29 September 2006
11:29 am ET

When threatened, minnows bunch together, swim slower and make quick darting movements to fake out their predators. How close they group together and how often they dart depends on the level of the threat. Is it just one pike fish or many? Are they far away or dangerously near?

But sometimes vision isn't enough to tell the minnows these things, so the small fish rely on another tactic: They sniff the water for scents of their predators.


For the full article:

http://www.livescience.com/ani....._nose.html
Back to top
View user's profile Send private message Visit poster's website
adedios
SuperPoster


Joined: 06 Jul 2005
Posts: 5060
Location: Angel C. de Dios

PostPosted: Thu Oct 26, 2006 6:50 am    Post subject: Odd Fish Jawless for 360 Million Years Reply with quote

Odd Fish Jawless for 360 Million Years

By Jeanna Bryner
LiveScience Staff Writer
posted: 25 October 2006
01:02 pm ET

They lack jaws, eyes and bones, but lampreys and their "primitive" anatomy have survived 360 million years and four major extinctions relatively unaltered, suggests a new study.

Scientists unearthed and analyzed the oldest lamprey fossil ever discovered, finding that it had a mouth nearly identical to today’s lamprey.

"This fossil changes how we look at lampreys today," said study team member Michael Coates of the University of Chicago. "They're very ancient, very primitive animals, yet with highly specialized feeding habits."

For the full article:

http://www.livescience.com/ani.....mouth.html
Back to top
View user's profile Send private message Visit poster's website
adedios
SuperPoster


Joined: 06 Jul 2005
Posts: 5060
Location: Angel C. de Dios

PostPosted: Tue Nov 14, 2006 10:44 am    Post subject: Fish Balance Courtship With Threats Reply with quote

Fish Balance Courtship With Threats

By Charles Q. Choi
Special to LiveScience
posted: 14 November 2006
08:27 am ET

New research on swordtail fish suggests male courtships displays aren't always just for appealing to the ladies, but for showing off and scaring away other males too.

Behavioral ecologist Heidi Fisher was investigating northern swordtails she collected in Mexico. Male swordtails [image] court by swimming close alongside females, raising their typically large sail-like dorsal fins and quivering briefly [video].

To see what female swordtails found attractive, Fisher tested them against video animations of males, which they varied by body size, coloration, the movement of the male, "and of course dorsal fin size," Fisher told LiveScience. "I assumed they would prefer the large dorsal fin, and was surprised when they didn't."

For the full article:

http://www.livescience.com/ani.....idate.html
Back to top
View user's profile Send private message Visit poster's website
adedios
SuperPoster


Joined: 06 Jul 2005
Posts: 5060
Location: Angel C. de Dios

PostPosted: Wed Jan 10, 2007 3:58 pm    Post subject: In a Vast Sea, How Fish Find Home Reply with quote

In a Vast Sea, How Fish Find Home

By Jeanna Bryner
LiveScience Staff Writer
posted: 10 January 2007
12:11 am ET

Ocean currents can whisk tiny larval fish a long way from home. Turns out, the little ones follow their noses back to their native reefs.

Jelle Atema, a sensory biologist at Boston University, and Gabriele Gerlach of the Marine Biological Laboratory in Woods Hole, Mass., analyzed small gene units called microsatellite markers in three species of reef fish, including the cardinal fish, spiny damsel fish and the neon damsel fish, living on five reefs within Australia’s Great Barrier Reef.

The markers indicated that more returned to their home reef than random chance would predict. The most obvious was the cardinal fish [image], which showed clear genetic differences from one reef to another.

For the full article:

http://www.livescience.com/ani.....trail.html
Back to top
View user's profile Send private message Visit poster's website
adedios
SuperPoster


Joined: 06 Jul 2005
Posts: 5060
Location: Angel C. de Dios

PostPosted: Tue Apr 17, 2007 7:43 am    Post subject: Ability to Bite Evolved in Fishy Ancestors Reply with quote

Ability to Bite Evolved in Fishy Ancestors

By Jeanna Bryner
LiveScience Staff Writer
posted: 16 April 2007
05:01 pm ET


The ability of ferocious land animals to bite prey evolved in ancient fish, a new study finds.

Fish predominantly capture prey with suction, which can be seen by watching a goldfish constantly puckering its mouth. But land animals can’t use this technique and instead use jaws that clamp together to catch and grasp a meal.

This feeding adaptation is another piece of evidence scientists use to illuminate the evolutionary transition from fish to land vertebrates.

For the full article:

http://www.livescience.com/ani....._bite.html
Back to top
View user's profile Send private message Visit poster's website
adedios
SuperPoster


Joined: 06 Jul 2005
Posts: 5060
Location: Angel C. de Dios

PostPosted: Fri Apr 27, 2007 9:02 am    Post subject: Fish growth enhanced by climate change Reply with quote

Fish growth enhanced by climate change

27 April 2007
CSIRO
Reference: 07/72

Changes in growth rates in some coastal and long-lived deep-ocean fish species in the south west Pacific are consistent with shifts in wind systems and water temperatures, according to new Australian research published in the United States this week.

“We have drawn correlations between the growth of fish species related to their environmental conditions – faster growth in waters above a depth of 250 metres and slower rates of growth below 1,000 metres,” says lead author, Dr Ron Thresher.

“These observations suggest that global climate change has enhanced some elements of productivity of shallow-water stocks but at the same time reduced the productivity and possibly the resilience of deep water stocks,” he says.

For the full article:

http://www.csiro.au/news/FishGrowthEnhanced.html
Back to top
View user's profile Send private message Visit poster's website
adedios
SuperPoster


Joined: 06 Jul 2005
Posts: 5060
Location: Angel C. de Dios

PostPosted: Mon Apr 30, 2007 8:20 am    Post subject: Hearts of male and female rainbow trout are different Reply with quote

American Physiological Society
30 April 2007

Hearts of male and female rainbow trout are different

Female rainbow trout prefer carbohydrates and tolerate lower oxygen levels better than males
WASHINGTON -- The heart is one of the most energy demanding organs of the human body. Its failure to function properly accounts for 600,000 deaths each year. Similarly, the rainbow trout, native to the Pacific Northwest and beloved as a sport- and food fish, requires dynamic and sustained cardiac function to maintain its health and swimming activity.

Previous studies of trout cardiac performance and energy metabolism have been conducted under hypoxic (oxygen shortage) conditions, but gender was not specifically examined. Nor were comparisons made between male and female fish (the largest group of vertebrates) made. There is a growing appreciation of significant sex differences in cardiac characteristics and function in adult humans. A new research study begins to close the gender gap in fishes, and finds that sex differences in cardiac performance and metabolism exist in rainbow trout. These differences occur at a young age and are only realized when the trout heart is contracting and not under resting conditions.

The study is entitled Sex Differences in Cardiac Glucose Metabolism and Function in Immature Rainbow Trout (Oncorhynchus mykiss). It was conducted by Pavan K. Battiprolu, Adam C. Goddard and Kenneth J. Rodnick, all of the Department of Biological Sciences, Idaho State University, Pocatello, Idaho. Dr. Rodnick's laboratory is presenting the team's findings at the 120th American Physiological Society (APS; www.the-APS.org) annual meeting, which is being held as part of the Experimental Biology (EB '07) conference. More than 12,000 scientific researchers will attend the gathering being held April 28-May 2, 2007 at the Washington, DC Convention Center.

The Study

The researchers examined if two regulatory molecules found in the fish heart -- citrate (an acid which inhibits the glycolytic metabolic pathway) and pyruvate dehydrogenase (PDH), the enzyme allowing carbohydrates to be oxidized -- differ between the sexes. The researchers hypothesized that male hearts would have higher citrate levels and females would benefit more from the stimulation of PDH than males.

The study also sought to determine if sodium cyanide (NaCN) -- an inhibitor of oxidative metabolism ¡V decreases activity of the glycolytic pathway and cardiac performance in both sexes, and if males possess a larger outermost (epicardial) layer of the ventricle vs. the inner endocardium layer. The trout heart is a composite organ and layer distinction is important because the epicardium, much like the human heart, receives oxygenated blood via the coronary circulation. Conversely, the endocardium is supplied by only deoxygenated blood returning from the rest of the body. Not surprisingly, the authors expect there to be corresponding layer differences in energy production and function.

Methodology

Uniform ventricle strips or transverse rings were cut from 10-12 month old, hatchery raised, sexually-immature male and female rainbow trout. Each strip was prepared in one of two ways: (1) incubated without stimulation (i.e., ventricle strips were incubated in a respiration cell containing an oxygenated buffer solution with glucose as the energy substrate). Oxygen consumption was measured using a calibrated oxygen electrode and data acquisition system; or (2) electrically-paced (i.e., ventricle strips were electrically-stimulated at physiological rates and temperature in tissue baths containing buffer, with (a) glucose and (b) glucose + DCA (dichloroacetate, an activator of PDH and a therapeutic drug used to treat human heart disease and cancer), or (c) glucose + NaCN under oxygenated and hypoxic conditions.

The researchers measured several indices of contractile performance (resting tension, twitch force, post-rest potentiation and other variables. Frozen samples of ventricle tissue were homogenized and assayed for citrate concentration. Ventricle rings were processed, sectioned and stained. Light microscopy was used to capture images of ventricle layers and analyzed for layer cross-sectional areas. Lactate concentration and net lactate release from cardiac tissue was also examined.

Results

The researchers found:


ventricle strips from males and females had similar rates of oxygen consumption and lactate release under resting conditions;


the inhibition of oxidative metabolism with NaCN lowered cardiac performance dramatically, and elevated resting tension and lactate release in both males and females;


under stimulated conditions with DCA vs. controls, female ventricle strips selectively demonstrated better performance and reduced lactate release;


force production during reoxygenation -- after a hypoxic insult -- significantly improved in males receiving DCA, but not females;


male ventricle tissue had 2.5-fold higher citrate concentrations than females; and;


males had a proportionately larger epicardium to endocardium ratio compared with females with similar size hearts.

Summary and Conclusions

This study expands upon previous findings that sex differences in cardiac performance and metabolism exist in fish in general, and have now been found to occur in rainbow trout in particular. Moreover, the differences are only realized during working conditions and involve stimulation or inhibition of the glycolytic pathway and carbohydrate oxidation. Ultimately, sex differences in cardiac energy metabolism and function may help define habitat suitability, swimming capabilities and health status of wild and hatchery-reared rainbow trout, and human heart disease, sex-specific treatment.

###
The research was funded by the NIH (grant # P20 RR16454 from the BRIN-INBRE Program of the National Center for Research Resources) and NSF (award # IOB-517669).

The American Physiological Society (APS) has been an integral part of the scientific discovery process since it was established in 1887. Physiology is the study of how molecules, cells, tissues and organs function to create health or disease.

NOTE TO EDITORS: The APS annual meeting is part of the Experimental Biology 2007 (EB '07) gathering and will be held April 28-May 2, 2007 at the Washington, DC Convention Center. To schedule an interview with Dr. Rodnick, please contact Donna Krupa.
Back to top
View user's profile Send private message Visit poster's website
adedios
SuperPoster


Joined: 06 Jul 2005
Posts: 5060
Location: Angel C. de Dios

PostPosted: Fri Jun 01, 2007 9:08 am    Post subject: Sharks Use Strange Trick to Hunt Prey Reply with quote

Sharks Use Strange Trick to Hunt Prey
By LiveScience Staff

posted: 01 June 2007 09:11 am ET

Like dogs, sharks rely on a keen sense of smell to track down food. But new research shows noses aren’t the only way that sharks detect smells: Their entire bodies, in fact, function as giant noses capable of even picking up the “shape” of a smell.

Running down the sides of every shark are nerve-packed strips called lateral lines. Researchers know these sensitive structures can detect the faint vibrations emitted by living things in water, but their ability to pick up scent was previously unknown. Even more surprising, researchers said, is that lateral lines can detect the 3-D “plumes” of scents—structures resembling the turbulence left behind after waving a hand through thick fog or steam.

"Odor plumes are complex, dynamic, three-dimensional structures used by many animal species to locate food, mates and home sites," said Jelle Atema, a Boston University biologist and co-author of the study detailed in an upcoming issue of the Journal of Experimental Biology. When deprived of the “odor plume” information, the study shows, sharks are unable to find the source of an odor.

For the full article:

http://www.livescience.com/ani.....ation.html
Back to top
View user's profile Send private message Visit poster's website
adedios
SuperPoster


Joined: 06 Jul 2005
Posts: 5060
Location: Angel C. de Dios

PostPosted: Sat Jul 07, 2007 7:30 am    Post subject: Dedicated Exclusively to Florida's Smalltooth Sawfish Reply with quote

Dedicated Exclusively to Florida's Smalltooth Sawfish
Pristis pectinata Latham, 1794
Floridasawfish.com

Many thanks for the hundreds of people who have reported their sawfish sightings and captures since we began this project a number of years ago. Without you, we would not have been able to begin to understand Florida's smalltooth sawfish, and we have been able to publish three scientific articles using your contributed data. Our project would not have been possible without your help!

http://www.floridasawfish.com/
Back to top
View user's profile Send private message Visit poster's website
adedios
SuperPoster


Joined: 06 Jul 2005
Posts: 5060
Location: Angel C. de Dios

PostPosted: Tue Jul 24, 2007 5:12 pm    Post subject: Eat fish -- especially if you drink high levels of alcohol Reply with quote

Alcoholism: Clinical & Experimental Research
24 July 2007

Eat fish -- especially if you drink high levels of alcohol

Essential fatty acids (EFAs) are a necessary part of an individual's healthy diet.
New findings indicate that binge-drinking men have lower intakes of n-3 fats, one type of EFA.
This low intake exacerbates the already very low EFA levels.
Essential fatty acids (EFAs) are just that; an "essential" part of the total fat intake necessary for a healthy human diet. Most EFAs come from plants, but some are animal-sourced. A new study has found that men who binge drink have substandard intake of n-3 fats, one of two types of EFAs, indicating poor dietary choices with negative long-term health consequences.

Results are published in the August issue of Alcoholism: Clinical & Experimental Research.

"Essential fatty acids are important building blocks of living cells, making up a substantial part of cell walls," explained Norman Salem, Jr., chief of the Laboratory of Membrane Biochemistry & Biophysics at the National Institute on Alcohol Abuse and Alcoholism "EFAs also have many biological functions, and a lack of them leads to loss of growth and development, infertility, and a host of physiological and biochemical abnormalities." Salem is also the study's corresponding author.

The most important EFAs are polyunsaturated fatty acids (PUFA), said J. Thomas Brenna, professor of human nutrition and of chemistry & chemical biology at Cornell University. Particularly two types, Brenna noted: the omega-6 PUFA linoleic acid (LA), also called n-6 fats, and the omega-3 PUFA linolenic acid (ALA), also called n-3 fats. "Most Americans consume adequate amounts of LA in their diets through the use of vegetable oils, but tend to have low intakes of ALA," said Brenna.

This imbalance, added Salem, has become pronounced only in the last century and many believe it is a source of the increase of many common diseases in Western society. Salem and his co-authors wanted to investigate what influence alcohol consumption might have on EFA imbalance in the Western diet.

Researchers used data from 4,168 adults who self-reported their alcohol consumption as part of the 2001-2002 National Health and Nutrition Examination Survey. Participants were also interviewed about their EFA intake during a single previous 24-hour period.

Results indicate that EFA intake drops as alcohol consumption increases, particularly among men.

"Our most important finding is the decrease in n-3 EFA intake in binge-drinking men," said Salem. "We really couldn’t evaluate women who binge drink two or more times per week due to the low numbers in this population, although it is quite possible that we would obtain similar findings. The changes we found indicate that those who drink alcohol make food selections in such a way as to decrease foods with this important nutrient. The binge-drinking men have decreases in the longer chain n-3 fatty acids, the ones that we typically get from eating fish, and so this suggests that they eat less fish."

"Previous studies by Dr. Salem and colleagues have shown that requirements for these nutrients actually increase with greater alcohol consumption," noted Brenna. "Considering that the ALA levels are already low compared to the LA levels, these results are further reason for concern over the ALA intake of alcoholics."

"This helps to explain why alcohol abuse leads to losses in polyunsaturated fats in the circulation and organs," said Salem. "However, dietary influence does not explain all of the changes observed in past studies of fatty-acid changes in organs of alcohol abusers. Alcohol also has an effect on fatty acid metabolism, mainly through increasing fat break down."

Furthermore, said Brenna, alcohol has strong, lasting, and deleterious effects on the brain. "The brain depends on a supply of omega-3 PUFA," he said. The brains of men consuming high levels of alcohol, particularly those who regularly binge drink, are further compromised by a low intake of EFA."

"In summary," said Salem, "for those who drink, especially binge drinkers or those who drink more than one drink per day on average: make sure that you obtain your sources of n-3 fatty acids in the diet, that is, eat more fish."

###
EMBARGOED FOR RELEASE UNTIL 24 JULY 2007 @ 16:00:00 ET

Alcoholism: Clinical & Experimental Research (ACER) is the official journal of the Research Society on Alcoholism and the International Society for Biomedical Research on Alcoholism. Co-authors of the ACER paper, “Alcohol Consumption and Fatty Acid Intakes in the 2001-2002 National Health and Nutrition Examination Survey,” were: Soo Yeon Kim (first author) of the Laboratory of Membrane Biochemistry and Biophysics at the National Institute on Alcohol Abuse and Alcoholism (NIAAA), Rosalind A. Breslow of the Division of Epidemiology and Prevention Research at NIAAA; and Jiyoung Ahn of the Nutritional Epidemiology Branch in the Division of Cancer Epidemiology and Genetics at the National Cancer Institute.
Back to top
View user's profile Send private message Visit poster's website
adedios
SuperPoster


Joined: 06 Jul 2005
Posts: 5060
Location: Angel C. de Dios

PostPosted: Mon Jul 30, 2007 2:28 pm    Post subject: Fishing for an answer: Wild or farmed? Reply with quote

Fishing for an answer: Wild or farmed?
30 July 2007

Journal of Agricultural and Food Chemistry

You pass up the farm-raised sea bass in the supermarket fish department, and pay a premium for its wild cousin. Are you getting your money’s worth, or was that “wild” fish actually raised on a fish farm and accidentally or intentionally mislabeled" Scientists in the United Kingdom are reporting development of a method to answer that question.

J. Gordon Bell and colleagues point out that European Union legislation requires that retailers and consumers have information on the geographical origin and production method for seafood. “Due to the global nature of production, similar fish products can be sourced from variable points of origin, and this can lead to instances of mislabeling, both intentional and fraudulent,” their report states. It is scheduled for the current (July 25) issue of ACS’ Journal of Agricultural and Food Chemistry, a biweekly publication. Other considerations, aside from price, make it important to distinguish between wild and farmed fish, the report notes.

The new test is based on differences in composition of the fatty components found in farmed and wild fish. The differences originate because farmed fish usually get a diet containing lower levels of marine-derived ingredients. With tests done on 10 wild and 10 farmed sea bass, the researchers cite the need to verify the findings on larger samples of different fish.

ARTICLE #4 FOR IMMEDIATE RELEASE
“Discrimination of Wild and Cultured European Sea Bass (Dicentarchus labrax) Using Chemical and Isotopic Analyses”

DOWNLOAD PDF
http://pubs.acs.org/cgi-bin/sa.....704561.pdf

DOWNLOAD HTML
http://pubs.acs.org/cgi-bin/sa.....04561.html
Back to top
View user's profile Send private message Visit poster's website
adedios
SuperPoster


Joined: 06 Jul 2005
Posts: 5060
Location: Angel C. de Dios

PostPosted: Wed Dec 12, 2007 3:35 pm    Post subject: Piddling fish face off threat of competition Reply with quote

BioMed Central
12 December 2007

Piddling fish face off threat of competition

Aggressive territorial male Mozambique tilapia fish (Oreochromis mossambicus) send chemical messages to rival males via their urine. They increase urination, have smellier urine and store more in their bladders than less aggressive males, according to research published in the open access journal BMC Biology. Animal behaviourists have known for some time that the urine of freshwater fish is a vehicle for reproductive hormones that act in the water as pheromones, affecting the behaviour and physiology of members of the opposite sex. Now, this research sheds light on the role of urine in influencing members of the same sex.

“Few studies have looked at the roles of pheromones in urine during competition between individuals of the same sex. We’ve found that tilapia dominant males store more urine in their bladders than subordinates, actively urinate during times of confrontation and the urine’s olfactory potency or smell strength is even greater,” explained Eduardo Barata, who led the Portuguese research.

As a lekking species – where males group together in the same area to breed, never leaving their nest, not even to feed – social hierarchy is important for the cichlid fish from Africa. Males actively advertise their dominant status through urinary odorants, which are thought to control aggression in rival males and so maintain social stability within the area, or lek. By measuring male urination frequency during competition, Barata et al. found that dominant or ‘resident’ males increased urination frequency in the presence of ‘intruder’ males from once every ten minutes to once every minute. Dominant males stopped urination when their opponent gave up, indicating a close link between aggression and urination rate. By also collecting urine and measuring the volume over five days and evaluating olfactory potency using an electro-olfactogram, it was seen that subordinate males also stored less urine and the urine was less smelly than that of dominant males.

“We know pheromones are involved in reproductive and non-reproductive behaviours of fish, for example during migration, mating and schooling,” explained Barata. “While we do not yet know what these chemicals are, it is clear they play a major role in many aspects of tilapia social behaviour by providing information about the fish’s aggressive capabilities for instance. This is also probably not unique to tilapia, so we’re touching the tip of the urinary pheromone iceberg!” concluded Barata.


###
Notes to Editors:

1. Pheromones are chemicals that trigger adaptive physiological and behavioural responses, and fish release them into the water via urine, skin and faeces.

2. Mozambique tilapia are endemic to the lakes and rivers of the east African coast. Males turn black during the breeding season and defend small territories centred on pit-like nests they dig in the sand. Females visit and spawn in these territories but brood eggs and rear young in a separate area.

3. Images available upon request.

4. Male urine signals social rank in the Mozambique tilapia (Oreochromis mossambicus, Peters 1852)
Eduardo N Barata, Peter C Hubbard, Olinda G Almeida, Antonio Miranda and Adelino V M Canario BMC Biology (12 December 2007)

To view the published article, please visit the journal website: http://www.biomedcentral.com/bmcbiol/

Please name the journal in any story you write. If you are writing for the web, please link to the article. All articles are available free of charge, according to BioMed Central’s open access policy.

5. BMC Biology - the flagship biology journal of the BMC series - publishes research and methodology articles of special importance and broad interest in any area of biology and biomedical sciences. BMC Biology (ISSN 1741-7007) is covered by PubMed, Scopus, CAS, BIOSIS, Zoological Record and Google Scholar. The journal is tracked by Thomson Scientific (ISI) and will receive its first Impact Factor in 2008.

6. BioMed Central is an independent online publishing house committed to providing immediate access without charge to the peer-reviewed biological and medical research it publishes. This commitment is based on the view that open access to research is essential to the rapid and efficient communication of science.
Back to top
View user's profile Send private message Visit poster's website
adedios
SuperPoster


Joined: 06 Jul 2005
Posts: 5060
Location: Angel C. de Dios

PostPosted: Mon Dec 17, 2007 2:49 pm    Post subject: Fish Swim North as Seas Warm Reply with quote

Fish Swim North as Seas Warm
By Jeanna Bryner, LiveScience Staff Writer

posted: 17 December 2007 08:02 am ET

As their ocean homes overheat, some fish species are swimming North again for the first time in hundreds of years to seek out cooler waters.

That's according to several studies of archaeological material, tax accounts, church registers and account books of monasteries, which juxtapose marine life as it looked in the distant past with fish data from today's warming world. The results, detailed in 14 papers in a special issue of the journal Fisheries Research, shed light on how global warming is impacting fisheries.

For the full article:

http://www.livescience.com/env.....rming.html
Back to top
View user's profile Send private message Visit poster's website
adedios
SuperPoster


Joined: 06 Jul 2005
Posts: 5060
Location: Angel C. de Dios

PostPosted: Fri Jan 11, 2008 6:39 pm    Post subject: Philippine science as world science: The case of milkfish re Reply with quote

Philippine science as world science: The case of milkfish reproduction
STAR SCIENCE By Raul Kamantigue Suarez, Ph.D.
Thursday, January 10, 2008

The milkfish sold in many Asian stores all over North America is bought mainly by Filipinos. Most Caucasians have never heard of it, while other ethnic groups do not seem to consume it with the same enthusiasm as do Filipinos. The low international demand for milkfish was one factor that led the International Development Research Center (IDRC) of Canada to fund milkfish research in the Philippines. As they put it, bangus is “protein for the masses.”

In the 1970s, I worked as a research assistant while studying for my master’s degree at UP Diliman. My master’s supervisor, Flor Lacanilao, had just returned after earning his Ph.D. in comparative endocrinology from the University of California at Berkeley. Our project to study milkfish reproductive physiology was funded by the National Science Development Board (NSDB) and the UP Natural Sciences Research Center (UPNSRC). Some of Dr. Lacanilao’s lectures were about how environmental factors provide sensory inputs that are processed by the nervous system, which, in turn, regulates the production of hormones by the pituitary gland. Among several hormones produced by the pituitary are those involved in reproduction. It is known that changes in the environment, via this pathway, affect the production and secretion of hormones that regulate the maturation of testes and ovaries. These “gonads” produce steroid hormones that are also involved in reproduction. This cocktail of pituitary and steroid hormones, under the right environmental conditions, stimulates sexual maturation and spawning, i.e., the release of sperm and eggs into the water, allowing external fertilization. A problem the Philippines faces is that the entire milkfish aquaculture industry relies on a seasonal, unreliable supply of wild-caught baby fish (fry) for stocking ponds. Although earlier studies had shown that large, meter-long milkfish could be caught and induced to spawn by hormone injections, this procedure is traumatic and usually fatal, and cannot be relied upon to supply fry to the entire aquaculture industry. So an important question was how milkfish could be grown, induced to mature and spawn in captivity.

What was required was the application of the scientific method — the formulation and testing of hypotheses. The resulting increase in understanding of milkfish reproductive physiology would lead to successful captive breeding. This may sound reasonable, but imagine applying for a P250 cash advance, waiting more than a week for the money, spending it all in one afternoon to buy supplies, submitting receipts, then applying for the next cash advance. This involved spending more time and energy satisfying the demands of bureaucrats than doing research. We often ran out of fish food, so I bought sliced bread to feed our fish. Then, an auditor called me to his office to accuse me of eating the bread myself. The interrogation lasted half an hour but I never confessed. This was the 1970s when theft of more than sliced bread was happening in high places. To make a long story short, our project failed.

By the early 1980s, Clarissa Marte (also a UP faculty member) and Flor Lacanilao had both moved to the Aquaculture Department of the Southeast Asian Fisheries Development Center (SEAFDEC) in Iloilo where they tried a different approach: they kept milkfish in floating cages in their natural, marine environment and let nature take its course. Subjected to natural, seasonal changes in environmental factors, the milkfish spontaneously matured and spawned; external fertilization followed and baby fry were produced. Flor Lacanilao’s dream had finally come true! In subsequent years, they showed that the results were reproducible and studied the underlying hormonal mechanisms. This was a truly Filipino success story: the first case of spontaneous sexual maturation and spawning of milkfish in captivity, followed by research to decipher the causal mechanisms responsible. One might be led to think that research concerning milkfish would be of interest only to Filipinos and publishable only in local, Philippine journals. However, the breakthrough article authored by Marte and Lacanilao was published in the international, peer-reviewed journal Aquaculture in 1986. This shows that when the scientific method is applied to address worthwhile questions, research concerning this “fish that no one cares about” (except us) becomes worthy of publication in international scientific journals. Indeed, my quick search for titles bearing “milkfish” using the ISI Web of Science yielded 227 articles published over the past 31 years, authored by a wide range of nationalities.

Scientists publish papers to report discoveries, describe phenomena, and explain new knowledge and understanding to the world. So, it must have been with great pride that Drs. Marte and Lacanilao announced to the world their truly Filipino achievement. When they did, their peers were other scientists in the international community — specialists in aquaculture, fish physiology, and fish reproductive biology. The publication of their paper in 1986 meant that it was judged to be of sufficient quality to merit publication by the journal’s reviewers and editors. The visibility gained and access to the article provided by the journal allows, even today, the evaluation of the quality and significance of their work by the international community. It was not my intention to write a complete history of Philippine research concerning milkfish reproduction. Rather, I call attention to this breakthrough article, as well as others published in international journals concerning milkfish, as examples of how Philippine science and world science are one.

* * *

Raul Kamantigue Suarez is a professor in the Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, California and an editor of the Journal of Experimental Biology, Cambridge, UK.
Back to top
View user's profile Send private message Visit poster's website
Display posts from previous:   
Post new topic   Reply to topic   printer-friendly view    USAP PAETE Forum Index -> Science Lessons Forum All times are GMT - 5 Hours
Page 1 of 1

 
Jump to:  
You can post new topics in this forum
You can reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group