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(Bio) Amoeba: Single Cell Amoeba Increases MRSA Numbers

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PostPosted: Sun Apr 02, 2006 7:41 am    Post subject: (Bio) Amoeba: Single Cell Amoeba Increases MRSA Numbers Reply with quote

Blackwell Publishing Ltd.
31 March 2006

Single cell amoeba increases MRSA numbers 1000- fold

Scientists in the UK have found that a type of amoeba acts as an incubator for MRSA bacteria. As amoebae are often found in healthcare environments this discovery has implications for the infection control strategies adopted by hospitals.
The single cell amoeba, Acanthamoeba polyphagam commonly eats and digests environmental bacteria. It also engulfs pathogens such as MRSA. However, instead of being digested by the amoeba, MRSA survives and replicates whilst inside the amoeba. Prof Michael Brown and colleagues at the University of Bath, found that MRSA in association with amoebae increased in numbers 1000- fold.

The pathogenic bacteria, Legionella, also replicate inside amoebae and are then released into the environment. The released bacteria are less susceptible to biocides and antimicrobials, and are more invasive than the same bacteria which have grown freely. Replication within amoebae may have the same effect on MRSA.

Amoebae, as cysts, are often dispersed by air currents, providing another means of spreading any trapped bacteria.

"We need more research into the role of amoeba in the spread of MRSA – hospitals should aim to eradicate amoebae as well as the bacteria themselves" said Prof Brown of the Department of Pharmacy and Pharmacology, University of Bath.


Questions to explore further this topic:

What are amoeba?

Where are amoeba found?

How to collect microscopic pond life?

Images of amoeba

Videos of amoeba

Structure of amoeba

How do amoeba fit in the tree of life?


Amoeba and Human Health

What is Pfiesteria?

Mouth amoeba parasites

What is amebiasis?

Deadly amoeba

What kills amoeba?

What is MRSA?

What are social amoeba?


Last edited by adedios on Sat Jan 27, 2007 3:40 pm; edited 2 times in total
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PostPosted: Fri Oct 27, 2006 6:48 pm    Post subject: Scientists' cell discovery unearths evolutionary clues Reply with quote

Scientists' cell discovery unearths evolutionary clues
University of York
27 October 2006

The full family tree of the species known as social amoebas has been plotted for the first time – a breakthrough which will provide important clues to the evolution of life on earth.

Researchers, headed by evolutionary biologist Professor Sandie Baldauf, of the University of York, and biochemist Professor Pauline Schaap, of the University of Dundee, have produced the first molecular ‘dictionary’ of the 100 or so known species of social amoeba.

Using this family tree, they have devised a model system to establish how single cell organisms communicate and interact to create multi-cellular structures in response to changing environmental conditions. Previously, there was almost no molecular data for social amoeba – Dictyostelia – which are a hugely diverse and ancient group.

Social amoebas are a group of organisms with a genetic diversity that is greater than that of fungi and similar to that of all animals. They offer an excellent experimental system for studying aspects of evolution and communication that are not easy to study in more complex multi-cellular organisms.

The York and Dundee teams have worked with field biologists in Germany, the US and Japan, and their research is published today (Friday 27 October 2006) in the prestigious international journal Science.

The published paper shows for the first time the family tree of all known social amoeba species and the evolution of their multicellular life style.

"This provides a starting point in allowing us to examine what happens at the molecular level as species evolve and mutate," said Professor Schaap, of the Division of Cell and Developmental Biology in the College of Life Sciences at Dundee.

"The availability of a family tree allows us to reconstruct the evolution of the signalling mechanisms that generate multicellularity. It also provides a powerful tool to identify core ancestral processes that regulate the most basic aspects of development."

Professor Baldauf, of the Department of Biology at York, said: "We have investigated the evolution of plants and animals for a very long time but our whole eco-system depends on single cell organisms. If we want to look at the fundamentals of life we have to look at single cell organisms.

"Amoebas are some of the closest single cell relatives of animals so understanding how they work and evolve is important because it helps us to understand how animals evolve. We have developed a new model system for the study of the evolution of forms.

"Amoebas are some of the closest single cell relatives of animals so understanding how they work and evolve is important because it helps us to understand how animals evolve"
Professor Sandie Baldauf"We have written the dictionary. Now we know what the words are - but we still have to construct the sentences."

The research teams were able to build the family tree by amplifying and comparing highly conserved genes from all known species of social amoeba.

The existing family tree of the social amoeba was based on how the multicellular structures of each species look on the outside. However, this tree was completely uprooted by the molecular data gathered by the researchers in Dundee and York.

By plotting all existing information of the amoebas’ cellular and multi-cellular shapes and behaviour to the molecular tree, it appeared that increased cell specialization and organism size is a major trend in the evolution of social amoeba.

Professor Schaap and her team are now working to establish how the regulation and function of genes with important roles in development was altered and elaborated during the course of evolution to generate novel cell-types and morphological features.

The next step for Professor Baldauf and her team will be to investigate the origin of these amoebas, and also to search for new species and to establish their position on the family tree. Meanwhile, a number of research projects, including teams in the USA and Germany, have won sponsorship to sequence the genomes of social amoeba species identified by the work in York and Dundee.

The Dundee-York project was funded under the Biotechnology and Biological Sciences Research Council (BBSRC) CODE (COmparative DEvelopment) initiative and took four years to complete.


Notes to Editors:
Professor Baldauf’s team included Michaela Nelson and Barrie Elgie.
Professor Schaap's team included Elisa Alvarez-Curto, Daniel Rozen and Alicia Milano-Curto
The College of Life Sciences at the University of Dundee has an international reputation as a centre of excellence for research into such key areas as cancer, diabetes and tropical diseases. Dundee has been Europe’s top-rated institution two years running in The Scientist magazine’s Best Places to Work in Academia survey, also finishing in the top four in the world outside the United States both years.
The University of York’s Department of Biology is one of the leading centres for biological teaching and research in the UK. The Department, with more than 400 scientific and support staff and 400 undergraduates currently has one of the highest research ratings in the UK.
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PostPosted: Thu Aug 02, 2007 3:13 pm    Post subject: Immunity in social amoeba suggests ancient beginnings Reply with quote

Baylor College of Medicine
2 August 2007

Immunity in social amoeba suggests ancient beginnings

Finding an immune system in the social amoeba (Dictyostelium discoideum) is not only surprising but it also may prove a clue as to what is necessary for an organism to become multicellular, said the Baylor College of Medicine researcher who led the research that appears today in the journal Science.

Dictyostelium discoideum usually exists as a single-celled organism. However, when stressed by starvation, the single cells band together to form a slug that can move. Eventually the slug changes to produce cells that perform specific functions – spores and stalks. In this new report, Dr. Adam Kuspa, chair of biochemistry and molecular biology at BCM, and his colleagues describe a new kind of cell they dubbed a “sentinel” cell.

Sentinel cells circulate within the slug, engulfing invading bacteria and sequestering poisons or toxins, eventually eliminating these from the slug. These cells often operate through a particular mechanism in the cells controlled by a Toll/Interleukin-1 Receptor domain protein (TirA), Kuspa and his team found.

This signaling pathway or a very similar one is present in plants and animals, he said. Now it has been identified in amoeba. It has not been found in fungi.

“Amoeba have, in the last 10 years, become appreciated as one of the four main forms of life in the crown group of eukaryotic (multicellular) organisms – plants, animals, fungi and amoeba,” said Kuspa. “What allowed them to become multicellular"”

One way to estimate the characteristics of the organism that went before those that were multicellular is to look for characteristics that are present in two, three or all four of these main groups, he said.

“Those were likely present in the progenitor organism,” said Kuspa. Because three of the four major groups of organisms have this pathway, “I argue that means that the progenitor of all multicellular organisms had this pathway. Since that organism was not likely multicellular, it must have used it as some kind of signaling to respond to bacteria in the environment.”

Looking at it from another point of view, “it’s possible that one of the properties of those (crown) organisms that allowed them to become multicellular was the ability to distinguish self from non-self – the hallmark of an immune system,” said Kuspa. “The speculation is that a requirement of multicellularity is that you develop systems to recognize pathogens and other non-self cells from yourself.”

Kuspa sees two paths for future research in the area. One is to look for evidence of the same immune mechanism and protein in other kinds of amoeba. The other is to look at unicellular organisms to determine if they have this same kind of immune signaling pathway.

“If none of the early diverging organisms that never became multicellular developed this kind of signaling system, it would subtly strengthen our argument,” he said.

Others who took part in this work include Drs. Guokai Chen and Olga Zhuchenko, both of BCM.

Funding for this work came from the National Institutes of Health.

After the embargo lifts, the article can be found at
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PostPosted: Tue Nov 25, 2008 9:13 am    Post subject: In Tough Times, Even Amoebas Turn to Family Reply with quote

In Tough Times, Even Amoebas Turn to Family

Jeanna Bryner
Senior Writer
25 November 2008

When times are tough, many of us turn to family and develop closer ties. So too with amoebas.

Some of these single-celled organisms tighten family bonds and cooperate when food is in short supply, new research shows.

The research, published this week in the journal PLoS Biology, shows how one amoeba species can distinguish genetically similar individuals, and how an incredibly simple life-form can display some sophisticated, social behaviors. (Not only is an amoeba a single cell, it reproduces asexually. So one parent cell divides into two daughter cells, which can continue to divide and produce more amoebas.)

"These single cells aggregate based on genetic similarity, not true kinship," said researcher Gad Shaulsky, professor of molecular and human genetics at Baylor College of Medicine in Houston. Shaulsky added that this demonstrates a discrimination between "self" and "non-self" that is similar to that seen in the immune systems of higher organisms.

Amoeba community

Called Dictyostelium discoideum, this amoeba species generally keeps to itself when living in a healthy environment with enough grub.

But when food supplies run low, the free-living organisms clump together into a community of individuals. The result is a multi-cellular organism. Each amoeba takes on one of two roles in this organism: They either become spores, which can survive and reproduce, or they die and the dead cells forms stalks that lift the spores above the ground to increase the chances the spores will disperse to more favorable environments.

Only cells that form spores can pass on their genetic information to future amoebas. So the preferred position is spore. About 20 percent of the cells, however, do turn into stalks.

Previous research has shown that Dictyostelium cells sometimes cheat and ditch stalk duty. Instead, they turn into spores while reaping the benefits (passing on genes) provided by other stalks.

Chummy cells

Perhaps there's a way to avoid being cheated, the researchers wondered. If being a stalk means one amoeba could ensure the survival and success of genetically similar individuals, evolutionarily, it makes sense to take one for the family.

To find out, the researchers mixed cells from genetically distinct strains of the amoebas. They found that the amoebas segregated into clusters of genetically similar individuals once they congregated into a multi-cellular formation.

In this way, the researchers determined that Dictyostelium reduces the likelihood that it will become a stalk cell that will die to assist in the survival of a genetically distant individual.

"The big thing we found is that Dictyostelium discoideum have social behavior," said researcher Mariko Katoh of Baylor College of Medicine. "We didn't really know if they could discriminate when the genetic differences were small. That was the surprising part."

Amoebas, along with plants, animals, protists and fungi, are considered eukaryotes by biologists. Sociality has also been detected among the other major group of organisms, prokaryotes (bacteria and archaea), which are generally single-celled organisms.

The amoeba research was funded by the National Science Foundation and the Keck Center for Interdisciplinary Bioscience Training of the Gulf Coast Consortia.
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