genetics
gregladen | January 18, 2008They always told you to eat your carrots, to improve your eyesight. Well, a deficiency of vitamin A (found in carrots, and lots of other foods) causes eye disease in a lot of children. In areas where Maize (corn) is a significant staple, there can be a problem because maize varies a great deal in how much vitamin A it can provide via precursor molecules. A new study in Science explores this relationship.
Maize is the dominant subsistence crop in much of sub-Saharan Africa and the Americas, where between 17 and 30% of children under age of 5 are vitamin A-deficient. This results in…
gregladen | January 18, 2008There is a discussion on the internet about Junk DNA, that includes a discussion at Sandwalk (Larry Moran's blog) ... I made a comment there about genome size that was responded to by T.R. Gregory. I started to write my response in Larry's Little Box, but realized that it would not fit. So it is here:
Imagine a gene family distributed among all the species in a given taxon. There are several alleles per gene. The gene codes for an enzyme that plays a role in determining cell size. Different combinations of genes/alleles exist to cause cell size to vary such that each species has a…
razib | January 17, 2008I've been blogging a fair bit on the relationship between history & genetics (see here, here and here), both as a parameter in shaping the course of events (e.g., immunological profiles, or through gene-culture coevolution), and as a tool in tracing out phylogenetic relationships between peoples and fleshing out demographic details. It so happens that an excellent paper which focuses upon the latter came out this week, The Genetic Structure of Pacific Islanders, in PLoS Genetics. It is so good and I'm so busy that I'll simply encourage you to read the paper in the original, and then read…
razib | January 16, 2008Why men and women find longer legs more attractive:
While all of the people were the same height, the length of their legs was altered to make them equal to the Polish average or longer by 5%, 10% or 15%.
The team found that regardless of the volunteers' own body shape and leg length, people whose legs were 5% longer than average were rated as the most attractive. The next most appealing was an average leg length, or those that were 10% longer than normal.
There's plenty of research on leg-length and its correlates to attractiveness. But the more important insight here is the rank order, and…
gregladen | January 16, 2008Well, it is a good thing that I have a thick skin and a good sense of humor, or I would be very put off by Larry Moran and probably T. Ryan Gregory as well.
Apparently, I stepped into an ongoing partially ad hominem debate over "Junk DNA" centering on the work of John Mattick and his research group. In this post, I'd like to provide a clarification of my "position" on Junk DNA, and I'll spend a moment admonishing my colleagues for being dorks.
My offending post is here. This is a report on a recent paper by Mattick and others in which they provide evidence that non coding RNA does…
mikethemadbiologist | January 16, 2008By way of ScienceBlogling Razib, I came across this Reason article by Ronald Bailey summarizing the presidential candidates views' on evolution. Bailey highlights two reasons what lack of support for evolution says about a candidate:
The candidate probably is weak on the separation of church and state.
The candidate is unable to rationally assess evidence.
But I think this misses the point entirely: evolution matters because evolutionary biology matters.
Granted this sounds like something Yogi Berra would say, but I'm tired of the Coalition of the Sane, regardless of where individual…
grrlscientist | January 15, 2008tags: researchblogging.org, blind cave fish, Astyanax mexicanus, evolution, fish, genetics
Blind cave fish, Astyanax mexicanus.
Image: Orphaned. Please contact me for proper credit and linkage.
Do you keep tropical freshwater fishes? I have kept tropical fishes for most of my life and was always intrigued by the so-called "blind cave fish", Astyanax mexicanus, that were sometimes offered for sale to the public. These fish evolved from a sighted species that live in surface streams, but since the blind cave fishes lived in caves since the mid-Pleistocene or earlier, they were not exposed…
gregladen | January 15, 2008You know that organisms develop, grow, and function in part because genes code for proteins that form the building blocks of life or that function as working bioactive molecules (like enzymes). You also know that most DNA is junk, only a couple percent actually coding for anything useful. Most importantly, however, you know that everything you know is wrong. Right?
The "Junk DNA" story is largely a myth, as you probably already know. DNA does not have to code for one of the few tens of thousands of proteins or enzymes known for any given animal, for example, to have a function. We know…
gregladen | January 14, 2008Syphilis is first clearly seen in Europe in 1495, when it appeared as a plague (though it was not "the blague" ... Yersinia pestis) among Charles VIII's troops. When these troops went home shortly after the fall of Naples, they brought this disease with them, staring an epidemic. The level of mortality in Europe was truly devastating. Is it the case that syphilis was brought to Europe by Columbus and his men just prior to the plague-like outbreak of 1495?
The origin of syphilis has been debated for years, really since the actual 1495 event itself. Some researchers have asserted that…
mikethemadbiologist | January 14, 2008While reading this unclear AP story about the genetics of autism (here's a clearer version), it struck me that the word allele needs to enter alongside the word gene.
Too often, in popular accounts, we hear people say things like "she was diagnosed with having the breast cancer gene." This is, of course, ridiculous. There is no breast cancer gene. Instead, some alleles of a gene make you more likely to get breast cancer (an allele is an alternative form of a DNA sequence that is located at a specific position on a specific chromosome).
This isn't just semantics; I think if the word allele…
razib | January 13, 2008The internet is a great thing. I've posted this link before, but if you haven't checked it out you really should poke through The Collected Papers of R.A. Fisher. There is so much archived genius on the internet; sometimes I wonder what a Ramanujan would have done with all the access to great thought.... (let's hope he wouldn't have spent his time on YouTube!). The Correlation Between Relatives on the Supposition of Mendelian Inheritance is probably one of the most important little known papers in the scientific firmament; it definitively fused Mendelianism with a Darwinian view of…
gregladen | January 12, 2008
Hat tips:
Evolgen
Biorad
Biosingularity
..And, pretty much everybody else on the Internet.
Can you identify the singers that are being parodies? (or at least, imitated?)
gregladen | January 11, 2008MIT scientists have found a new way that DNA can carry out its work that is about as surprising as discovering that a mold used to cast a metal tool can also serve as a tool itself, with two complementary shapes each showing distinct functional roles.
Professor Manolis Kellis and postdoctoral research fellow Alexander Stark report in the Jan. 1 issue of the journal Genes & Development that in certain DNA sequences, both strands of a DNA segment can perform useful functions, each encoding a distinct molecule that helps control cell functions.
There is a full press report here.
razib | January 11, 2008There have been a spate of articles about E. O. Wilson'sdrive to put group selection back into mainstream conversation among evolutionary biologists over the past year. Wilson has kept the torch alive for this particular paradigm since the 1970s, when it was prominently featured in his famous book Sociobiology. At the same time as Wilson was making waves in the United States Richard Dawkins debuted with The Selfish Gene, a book where he explored the new ideas of theoretical biologists W. D. Hamilton and J. M. Smith. Hamilton's model of kin selection, which he debuted in the mid-1960s,…
razib | January 10, 2008Turns out that Jamie Lynn Spears' baby daddy is expressing paternity skepticism. He might check out the paper How Well Does Paternity Confidence Match Actual Paternity? Evidence from Worldwide Nonpaternity Rates:
This survey of published estimates of nonpaternity suggests that for men with high paternity confidence, nonpaternity rates are typically 1.7% (if we exclude studies of unknown methodology) to 3.3% (if we include such studies). These figures are substantially lower than the "typical" nonpaternity rate of 10% or higher cited by many researchers, often without substantiation...or the…
gregladen | January 9, 2008A glow in the dark pig has given birth to more glow in the dark pigs.
Fluorescent Chinese pig passes on trait to offspring from PhysOrg.com
A pig genetically modified in China to make it glow has given birth to fluorescent piglets, proving such changes can be inherited, state media said Wednesday.
[...]
The pigs were originally modified (to glow) using somatic cell nuclear transfer.It is not entirely clear to me how the gene got into the gametes. It also appears that the distribution of the gene in the offspring is not exactly the same as in the parent, suggesting something interesting…
gregladen | January 7, 2008A group of scientists ... has uncovered a new biological mechanism that could provide a clearer window into a cell's inner workings.....What's more, this mechanism could represent an "epigenetic" pathway -- a route that bypasses an organism's normal DNA genetic program -- for so-called Lamarckian evolution, enabling an organism to pass on to its offspring characteristics acquired during its lifetime to improve their chances for survival.
Giardia surfaces are known to adapt to a host's immune response, and pass this on to daughter cells during cell division. That would be a system of…
clock | January 7, 2008
I had no time to read this in detail and write a really decent overview here, perhaps I will do it later, but for now, here are the links and key excerpts from a pair of exciting new papers in PLoS Biology and PLoS ONE, which describe the patterns of expression of a second type of cryptochrome gene in Monarch butterflies.
This cryptochrome (Cry) is more similar to the vertebrate Cry than the insect Cry, also present in this butterfly. The temporal and spatial patterns of expression of the two types of Cry suggest that they may be involved in the transfer of time-information from the…
gregladen | January 6, 2008From a Massachusetts Institute of Technology press release:
researchers have uncovered a critical difference between flu viruses that infect birds and humans, a discovery that could help scientists monitor the evolution of avian flu strains and aid in the development of vaccines against a deadly flu pandemic.
A quick word about viruses and receptor sites. I have always found the terminology to be a bit counter-intuitive and possibly misleading. The word "receptor site" almost sounds like a feature that a cell has in order to receive, allow in, provide a reception for a virus, as though…