Posts Tagged ‘Biology’

Zebra’s Stripes, Butterfly’s Wings: How Do Biological Patterns Emerge?

June 23, 2008

A zebra’s stripes, a seashell’s spirals, a butterfly’s wings: these are all examples of patterns in nature. The formation of patterns is a puzzle for mathematicians and biologists alike. How does the delicate design of a butterfly’s wings come from a single fertilized egg? How does pattern emerge out of no pattern?

Using computer models and live cells, researchers at Johns Hopkins have discovered a specific pattern that can direct cell movement and may help us understand how metastatic cancer cells move.

“Pattern formation is a classic problem in embryology,” says Denise Montell, Ph.D., a professor of biological chemistry at Hopkins. “At some point, cells in an embryo must separate into those that will become heart cells, liver cells, blood cells and so on. Although this has been studied for years, there is still a lot we don’t understand.”

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Altruism In Social Insects Is A Family Affair

June 16, 2008

The contentious debate about why insects evolved to put the interests of the colony over the individual has been reignited by new research from the University of Leeds, showing that they do so to increase the chances that their genes will be passed on.

A team led by Dr Bill Hughes of the University’s Faculty of Biological Sciences studied ‘kin selection’ — the theory that an animal may pass on its genes by helping relatives to reproduce, because they share common genes, rather than by reproducing itself.

The concept of ‘kin selection’ was developed in 1964 by the evolutionary biologist Bill Hamilton, first proposed by Charles Darwin to explain, for example, why sterile workers evolved in social insect groups and why a honeybee would sacrifice its life to defend the colony. Charles Darwin recognized that such altruistic behaviour in highly social insect groups was at odds with his theory of natural selection, and Bill Hamilton’s theory of kin selection showed that this behaviour can evolve because it still fulfills the drive to pass on genes – but through relatives instead.

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Flies Found To Have Internal Thermosensors To Monitor Environmental Temperatures

June 13, 2008

Flies, unlike humans, can’t manipulate the temperature of their surroundings so they need to pick the best spot for flourishing. New Brandeis University research in this week’s Nature reveals that they have internal thermosensors to help them.

Biologist Paul Garrity and his colleagues have discovered that the fruitfly Drosophila has four large heat-responsive neurons located in its brain. These are activated at temperatures just above the fly’s preferred temperature by an ion channel in the cell membrane known as dTrpA1, which itself acts as a molecular sensor of warmth.

This internal warmth-sensing pathway helps the fly to avoid slightly raised temperatures and acts together with a cold-avoidance pathway in the antennae to set the fly’s preferred temperature–enabling the fly to pick its optimal ambient temperature range for survival.

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Mammalian Neurogenesis Breaks Into The Most Static Brain Region

June 9, 2008

Fifteen years ago, the discovery of adult neurogenesis (the production of new neurons) in the highly static, non-renewable mammalian brain was a breakthrough in neuroscience. Most emphasis was put on the possibility to figure out new strategies for brain repair against the threath of neurodegenerative diseases. Yet, unlike lower vetebrates, which are characterized by widespread postnatal neurogenesis, neurogenic sites in mammals are highly restricted within two very small regions. Hence, the fact that protracted neurogenesis in mammals is an exception rather than the rule slowes down hopes for generalized brain repair.

Work carried out in the recent past at the University of Turin, involving Federico Luzzati and Paolo Peretto at the Department of Animal Biology, and Giovanna Ponti and Luca Bonfanti at the Department of Veterinary Morphophysiology, revealed striking examples of structural plasticity and neurogenesis in the nervous system of rabbits. These Lagomorphs show remarkable differences under the profile of neurogenesis with respect to their close relatives Rodents (mice and rats).

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Mice Mothers Devote Energies To Offspring When Life Is Threatened

May 30, 2008

An Iowa State University researcher has found that sick female deer mice devote their energy to producing healthier offspring.

Lisa Schwanz, a researcher in the department of ecology, evolution and organismal biology, studied the size of offspring for both infected and healthy mice and found that females that had been infected with a parasite produced larger offspring than healthy females.

This finding was unexpected because most mammals tend to focus on their own survival when they are threatened with sickness or infection.

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New Threat To Spotted Owl Exposed

May 30, 2008

A new study provides a baseline distribution of blood parasites and strains in Spotted Owls, suggesting a more fragile immune health than previously understood for the already threatened Northern and California Spotted Owls.

The study, co-authored by San Francisco State University biologists, is the first to show a Spotted Owl infected with an avian malaria (Plasmodium) parasite.

“While Plasmodium parasites have been found in thriving owl species, the detection in a Spotted Owl could further challenge the threatened species’ survival,” said Heather Ishak, an SF State graduate biology student who performed the research with Assistant Professor of Biology Ravinder Sehgal and others.

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Multiple New Species Of Fruit Flies With Overlapping Niches Discovered

May 20, 2008

Evidence of physically similar species hidden within plant tissues suggest that diversity of neotropical herbivorous insects may not simply be a function of plant architecture, but may also reflect the great age and area of the neotropics.

In an article published in Science, Cornell College biology professor Marty Condon and coauthors turn current thought on plant-feeding insect diversity on its head. The study used an examination of fruit fly diversity in Latin America to conclude that typical niche diversity tracking can lead to undercounting of species. DNA analysis resulted in the discovery of multiple new species of fruit flies with overlapping niches.

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