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Tag: "variation" at biology news

Gene expression becomes heterogeneous with age in humans and rats

...ng on gene expression, researchers have found that variation in gene expression among individuals tends to incr...ore, they found that the tendency toward increased variation is not restricted to a specific set of genes, implying that increased heterogeneity is the outcome o...

Internal body clock dictates timing of different types of stroke

... for all the different types, but there was little variation between the sexes in respect of the timing of the various types of stroke. All three stroke types registered two peaks during the day, one between 6 and 8 in the morning and the other between 6 and 8 in the evening, with a significant dip in the nu...

Completed genome set to transform the cow

...e bovine genome as a template to highlight genetic variation within and between cattle breeds, and between cattle and other mammal species. The head of bioinformatics research at CSIRO Livestock Industries, Dr Brian Dalrymple, says the new data is very valuable because it provides researchers with a more co...

Chimpanzee study reveals genome variation hotspots

...nvolved in and what they mean from a morphological variation and disease standpoint." Specifically, the study ...ely, we can use information about within-a-species variation to identify unusual patterns between species," he says. "This may highlight copy number differences ...

HIV-1's high virulence might be an accident of evolution

...key hosts. The group will also examine whether Nef variation among HIV-2 strains might explain differences in the rate of progression to disease in infected humans. ...

Non-coding RNAs help silence the mammalian transcription

...mechanism utilizes some form of RNA silencing. The variation in silencing mechanisms lends further support to the argument that imprinting arose gradually over a long period in mammals, not all at once," explains Dr. Tilghman. ...

Snakes' virtual glasses, leopard spots and all-optical transistors

...at such patterns may evolve over time. A two-stage variation of Turing's model, recently developed by physicists at Taiwan's National Chung-Hsing University and Oxford's Mathematical Institute, duplicates the changes in the patterns on leopards and jaguars as the animals age. Both felines sport simple spots wh...

Researcher gives hard thoughts on soft inheritance

...ies acquiring inherited characteristics that drive variation and evolution. Lamarck, for instance, believed th...tion that is beneficial. This is the more extreme variation of soft inheritance that raises the hackles." Packing DNA Epigenetic mechanisms l...

DNA to the defense

...s were quite variable in size. "The range of size variation we observe in African trypanosomes far exceeds any... non-variable parasite proteins, such capacity for variation further dims hopes for an effective vaccine for affected populations in rural Africa. ...

Choosy females make colourful males

...peciation in the East African Lakes. Environmental variation subsequently leads to differences in preference and eventually to speciation. Evolutionary theory predicts that species can diverge if different females choose different characteristics in males. Yet females often pay attention to traits that revea...

The higher the hierarchy, the greater the aggression

Individual variation in social behavior is one of the most striking fea...els," write the authors. Cant et al. conclude that variation in future fitness due to inheritance rank is the hidden factor accounting for much of the variation ...

Wasps queue for top job

...e. Previous scientific thinking indicated that the variation in help given might be proportional to genetic relatedness. Those less closely related to the queen would help out less. This new study, however, shows that more distantly related wasps aren't in fact lazier. Instead, the team led by Dr Field, foun...

A new view on Lyme disease: Rodents hold the key to annual risk

...r simulations, they analyzed trends in interannual variation and found two powerful predictors of entomological...rprising, the researchers found that even a 3-fold variation in deer numbers had no impact on subsequent nymph abundance. Density of infected nymphs--the prin...

A new kind of mutation could explain numerous phenotypic variations in various species

..., could contribute significantly to the phenotypic variation observed in many species ?among which humans ?including the hereditary predisposition to various diseases. Researchers at ULg have thus produced a database available online that compiles all these mutations (the Patrocles database: http://www.patroc...

Evolution reveals an independent route for diversity in animal form

...efining characteristic of animals, and much of the variation seen in animal morphology has been attributed to evolutionary variations on how the Hox system is implemented during development in different species. In the new work, the researchers investigated the Hox status of cnidarians--a group of primitive ...

Electric fish in Africa could be example of evolution in action

...rances, so we were surprised to find no detectable variation in the genetic markers we studied," Arnegard said. Because all of the 20 or so species of mormyrid have distinct electric signals, Arnegard believes the different impulses of the fish he studies might be their first step in diverging into different ...

Solved: The mystery of flesh-eating bacteria's relentless attack

...yme called ScpC. The team then created a mutant variation of the M14 strain of Streptococcus that could not produce ScpC. As expected, this strain was much less virulent than the original M14. Only three of 28 mice receiving the mutant strain succumbed to infection, a death rate much lower than that of mice...

AIDS study challenges conventional treatment guidelines for HIV patients

... that the viral load explains only about 5% of the variation from person to person in the rate of CD4 cell loss...ought to estimate how much of the person-to-person variation in the rate of CD4 cell loss could be accounted for on the basis of each patient's initial viral loa...

Viral marker of human migration suspect

...rchers note that while previous studies of genetic variation have observed some differences between the distribution of JCV and human populations, the extent of the differences in their evolutionary histories has never been fully tested. Shackelton and her colleagues analyzed 333 genetic sequences of the vi...

Second opinion yields treatment changes for half of patients

...o another biopsy. Previous studies have documented variation in how radiologists interpret mammograms. Those who specialize in breast imaging tend to detect more abnormalities. In addition, a dedicated breast pathologist can make a difference in how the cancer is staged, which in turn can affect treatment r...

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