January 25, 2010, 0:04 AM CT

Risky business for toads under threat from fungus

Midwife toads that live in the mountains are highly likely to die from a serious fungal infection, called chytridiomycosis, whereas their infected relatives in the lowlands are not, as per new research published recently in Ecology Letters

The authors of the study, from Imperial College London, the Zoological Society of London and the BiodivERsA project RACE, say their findings suggest conservationists appears to be able to limit the impact of the disease in the mountains by ensuring tourists do not transfer it between lakes.

During the five year study, the scientists observed that no midwife toads at low altitudes died as a result of fungal infection, whereas up to 100 per cent of those at high altitudes died. The mortality rate of toads at high altitudes fluctuated over the five years.

The fungus Batrachochytrium dendrobatidis (Bd), also known as chytrid fungus, grows in the skin of amphibians, causing a disease called chytridiomycosis. The fungus has caused a number of species of frog and toad to become extinct and human activity has spread the fungus across the world, affecting an estimated 50 per cent of amphibian species.

Eventhough infection commonly is invisible to the naked eye, it can cause skin discolouration and ulceration and lead to convulsions. Prior research shows that infection kills amphibians by causing heart failure. The fungus is especially prevalent in Australia and the Americas, where its spread is well studied. However, little was known about Bd in Europe before today's study......... Posted by: Kelly      Read more         Source

Mon, 25 Jan 2010 05:35:42 GMT

Parasite of the Day

My colleague at the American Museum of Natural History, Susan Perkins, has started an ambitious new blog. She will be introducing a new parasite to the world each day in Parasite of the Day. Unfortunately, perhaps, for the hosts of the world, Susan has plenty of subject matter and should be busy for quite some time. A recent paper in PNAS (Dobson et al. 2008) states that although they "estimate that there are between 75,000 and 300,000 helminth species parasitizing the vertebrates. [They] have no credible way of estimating how many parasitic protozoa, fungi, bacteria, and viruses exist. At least the helminths parasites of vertebrates will keep Susan busy for the next 821 years or so.
The photo above is of Neoechinorhynchus emyditoides a species of acanthocephalan, or thorny-headed worm, by Mike Barger. Posted by: Dennehy      Read more     Source

Mon, 25 Jan 2010 05:05:52 GMT

Andrew Zuckerman's Bird

Turning his camera to the world of birds, Andrew Zuckerman has created a new body of work showcasing more than 200 stunning photographs of nearly 75 different species.



(via Neatorama) Posted by: Gerard      Read more     Source

January 22, 2010, 8:05 AM CT

Sexual reproduction versus asexual reproduction

Living organisms have good reason for engaging in sexual, rather than asexual, reproduction as per Maurine Neiman, assistant professor of biology in the UI College of Liberal Arts and Sciences and researcher in the Roy J. Carver Center for Genomics.

In an article published in a recent issue of the journal Molecular Biology and Evolution, she and her colleagues, including John M. Logsdon Jr., associate professor of biology, examined the theory that sexual reproduction, while requiring more time and energy than asexual reproduction, is also much more common among living organisms and, therefore, must be very beneficial.

The study looked at sexual, as well as asexual, varieties of a New Zealand freshwater snail (left), Potamopyrgus antipodarum, by sequencing mitochondrial genomes and observed that the sexually reproducing snails had accumulated harmful DNA mutations at about half the rate of the asexual snails.

"This is the first study to compare mutation accumulation in a species where sexual individuals and asexual individuals regularly coexist, and thus provides the most direct evidence to date that sex helps to counter the accumulation of harmful mutations," said Neiman.

Neiman plans to continue her evolutionary biology research such that a clearer understanding of the advantages of sex will offer a better understanding of the value of preserving genetic diversity within and among populations, species, and ecological communities......... Posted by: Kelly      Read more         Source

January 22, 2010, 8:03 AM CT

Zebrafish helps drug development

By combining the tools of medicinal chemistry and zebrafish biology, a team of Vanderbilt researchers has identified compounds that may offer therapeutic leads for bone-related diseases and cancer.

The findings, reported in ACS Chemical Biology, support using zebrafish as a novel platform for drug development.

In 2007, Charles Hong, M.D., Ph.D., and his colleagues described using fish embryos to screen for compounds that interfere with signaling pathways involved in early development pathways known to play roles in a variety of disease processes. They discovered the compound "dorsomorphin" and demonstrated that it blocked BMP (bone morphogenetic protein) signaling, which has been implicated in anemia, inflammatory responses and bone-related disorders.

But in examining dorsomorphin further, the researchers observed that it had other "off-target" effects it also blocked the VEGF (vascular endothelial growth factor) receptor and disrupted zebrafish blood vessel development, a process called angiogenesis.

"Off-target effects contribute to side effects and limit the therapeutic potential of small molecule signaling inhibitors," said Hong, assistant professor of Medicine and Pharmacology.

To find compounds that were more selective BMP inhibitors (didn't have the off-target effects), Hong and his colleagues opted to use their zebrafish drug discovery screen as a drug development/optimization tool......... Posted by: Kelly      Read more         Source

Mon, 18 Jan 2010 05:43:20 GMT

Green Sea Slug Is Part Animal, Part Plant

It"s easy being green for a sea slug that has stolen enough genes to become the first animal shown to make chlorophyll like a plant. Shaped like a leaf itself, the slug Elysia chlorotica already has a reputation for kidnapping the photosynthesizing organelles and some genes from algae.

Now it turns out that the slug has acquired enough stolen goods to make an entire plant chemical-making pathway work inside an animal body. The slugs can manufacture the most common form of chlorophyll, the green pigment in plants that captures energy from sunlight. Posted by: Gerard      Read more     Source

January 15, 2010, 8:09 AM CT

Plant-pollinator relationship

Figs and the wasps that pollinate them present one of biologists' favorite examples of a beneficial relationship between two different species. In exchange for the pollination service provided by the wasp, the fig fruit provides room and board for the wasp's developing young. However, wasps do not always pollinate the fig. Fig trees "punish" these "cheaters" by dropping unpollinated fruit, killing the wasp's offspring inside, report scientists working at the Smithsonian Tropical Research Institute.

Their results, reported in the Proceedings of the Royal Society, show that sanctions against cheaters appears to be critical to maintain the relationship.

"Relationships require give and take. We want to know what forces maintain this 80-million-year-old arrangement between figs and their wasp pollinators." said main author, Charlotte Jandr, graduate student in Cornell University's Department of Neurobiology and Behavior, who conducted the study as a Smithsonian pre-doctoral fellow. "What prevents the wasps from reaping the benefits of the relationship without paying the costs?".

Some wasp species passively carry pollen that sticks to their bodies. Others actively collect pollen in special pouches. Jandr reviewed the ability of six different fig tree-fig wasp species pairs to regulate cheating. She introduced either a single pollen-free wasp, or a wasp carrying pollen, into a mesh bag containing an unpollinated fig. The wasps entered the figs to lay their eggs. Jandr observed that trees often dropped unpollinated figs before young wasps could mature......... Posted by: Kelly      Read more         Source

January 14, 2010, 8:11 AM CT

Why leopards can't change their spots

The leopard cannot change its spots, nor can the tiger change its stripes, but a new research report reported in the January 2009 issue of the journal GENETICS tells us something about how cats end up with their spots and stripes. It demonstrates for the first time that at least three different genes are involved in the emergence of stripes, spots, and other markings on domestic cats. Scientists have also determined the genomic location of two of these genes, which will allow for further studies that could shine scientific light on various human skin disorders.

"We hope that the study opens up the possibility of directly investigating the genes involved in pattern formation (i.e., the establishment of stripes, spots, and other markings) on the skin of mammals, including their structure, function, and regulation," said Eduardo Eizirik, a researcher involved in the work from the Pontifical Catholic University of Rio Grande do Sul, Brazil. "From these studies, we hope to understand how the different coat patterns have evolved in different mammalian groups, and to be able to investigate their roles in adaptation to different environments, such as their importance for camouflage in wild cat species."

Researchers crossed domestic cats with different coat patterns, such as stripes and blotches, and tracked the inheritance of these patterns among their offspring. Genetic samples were collected and used to type various molecular markers. Results showed that specific markers were inherited by a kitten every time a given coat pattern appeared, suggesting that the marker and the gene causing the coat pattern were located in the same region of the genome. Using statistical procedures called linkage mapping, researchers determined the genomic location of two genes involved in these traits. By clarifying the inheritance of markings in one mammalian species, scientists hope to identify and characterize the implicated genes and then determine if they apply to other mammals, such as humans. The hope is that this discovery will shed new light on human skin diseases that appear to follow standardized patterns......... Posted by: Kelly      Read more         Source

January 14, 2010, 8:10 AM CT

Tracking paw prints of selective breeding

From the Dachshund's stubby legs to the Shar-Pei's wrinkly skin, breeding for certain characteristics has left its mark on the dog genome. Scientists have identified 155 regions on the canine genome that appear to have been influenced by selective breeding.

With more than 400 distinct breeds, dogs come in a wide range of shapes, sizes, fur-styles, and temperaments. The curly-haired toy poodle, small enough to sit in a teacup, barely looks or acts like the smooth-coated Great Dane tall enough to peer like a periscope out of a car's sunroof. Not so apparent are breed differences in how the dogs' bodies function and their susceptibility to various diseases.

Eventhough domestication of dogs began over 14,000 years ago, as per Dr. Joshua Akey, University of Washington (UW) assistant professor of genome sciences, the spectacular diversity among breeds is thought to have originated during the past few centuries through intense artificial selection of and strict breeding for desired characteristics. Akey is the main author of the effort to map canine genome regions that show signs of recent selection and that contain genes that are prime candidates for further investigation. Those genes are being examined for their possible roles in the most conspicuous variations among dog breeds: size, coat color and texture, behavior, physiology, and skeleton structure......... Posted by: Kelly      Read more         Source

January 13, 2010, 8:16 AM CT

Tilapia feed on Fiji's native fish

The poster child for sustainable fish farmingthe tilapiais actually a problematic invasive species for the native fish of the islands of Fiji, as per a newly released study by the Wildlife Conservation Society and other groups.

Researchers suspect that tilapia introduced to the waterways of the Fiji Islands appears to be gobbling up the larvae and juvenile fish of several native species of goby, fish that live in both fresh and salt water and begin their lives in island streams.

The recently published paper appears in Aquatic Conservation: Marine and Freshwater Ecosystems The authors include: Stacy Jupiter and Ingrid Qauqau of the Wildlife Conservation Society; Aaron P. Jenkins of Wetlands International-Oceania; and James Atherton of Conservation International.

"A number of of the unique freshwater fishes of the Fiji Islands are being threatened by introduced tilapia and other forms of development in key water catchment basins," said Dr. Jupiter, a co-author of the study and one of the researchers examining the effects of human activities on the native fauna. "Conserving the native fishes of the islands will require a multi-faceted collaboration that protects not only the waterways of the islands, but the ecosystems that contain them." .

The most surprising finding of the study centers on the tilapia, a member of the cichlid family of fishes from Africa that has become one of the most important kinds of fish for aquaculture, due in large part to its rapid rate of growth and palatability. Aside from its value as a source of protein, the tilapia is sometimes problematic to native fish species in tropical locations......... Posted by: Kelly      Read more         Source