Molecular Biology
pharyngula | July 31, 2008
Ontogenetic allometry in the fang in the front-fanged Causus rhombeatus (Viperidae) displaces the fang along the upper jaw. Scale bars, 1 mm. We note the change in relative size of the upper jaw subregions: i, anterior; ii, fang; iii, posterior. d.a.o., days after oviposition.
I keep saying this to everyone: if you want to understand the origin of novel morphological features in multicellular organisms, you have to look at their development. "Everything is the way it is because of how it got that way," as D'Arcy Thompson said, so comprehending the ontogeny of form is absolutely critical to…
neurophilosophy | July 16, 2008
This three-dimensional reconstruction of an amyloid fibril (found at Discover) was created by Nikolaus Grigorieff and his colleagues at Brandeis University, by computer processing of a transmission electron cryomicroscopy image. It is the most detailed image yet of the abnormally folded protein which accumulates to form the senile plaques that are a pathological hallmark of Alzheimer's Disease.
The fibrils consist of a protein fragment called amyloid-beta 1-40, an insoluble forty amino acid polypeptide generated by the sequential actions of a number of enzymes on the amyloid precursor…
edyong | July 4, 2008
There can be few events more devastating for a parent than cot death - the sudden and unexpected death of a baby. Cot death is more formally known as Sudden Infant Death Syndrome (SIDS) and it is an apt title, for affected babies often seem outwardly healthy and show no signs of suffering. Studies have suggested that things like passive smoke and breastfeeding can affect the risk of SIDS but the underlying biology behind the syndrome is a mystery, as is the cause of death in most cases.
But it's a mystery that's slowly being solved. The latest and most intriguing clue comes from Enrica…
pharyngula | June 30, 2008
We've heard the arguments about the relative importance of mutations in cis regulatory regions vs. coding sequences in evolution before — it's the idea that major transitions in evolution were accomplished more by changes in the timing and pattern of gene expression than by significant changes in the genes themselves. We developmental biologists tend to side with the cis-sies, because timing and pattern are what we're most interested in. But I have to admit that there are plenty of accounts of functional adaptation in populations that are well-founded in molecular evidence, and the cis…
pharyngula | June 26, 2008
This is an amphioxus, a cephalochordate or lancelet. It's been stained to increase contrast; in life, they are pale, almost transparent.
It looks rather fish-like, or rather, much like a larval fish, with it's repeated blocks of muscle arranged along a stream-lined form, and a notochord, or elastic rod that forms a central axis for efficient lateral motion of the tail…and it has a true tail that extends beyond the anus. Look closely at the front end, though: this is no vertebrate.
It's not much of a head. The notochord extends all the way to the front of the animal (in us vertebrates, it…
edyong | June 21, 2008
The world's nations are stockpiling two drugs, Tamiflu and Relenza, to counter the threat of a bird flu pandemic. These drugs work by blocking a key protein that allows the virus to spread. But two years ago, a study revealed the structure of this protein and in doing so, shown that both Tamiflu and Relenza only work through a fortunate fluke.
The threat of bird flu is looming large in the minds of the public, scientists and politicians alike. So far, 241 people have died of the disease across 12 countries. But the real worry is that that the virus could mutate into a form that…
neurophilosophy | June 11, 2008When it comes to human brain evolution, it is often said that size matters. The human cerebral cortex is much larger than that of other primates, and therefore its expansion must have been a vital feature of human evolution. Researchers have therefore emphasized the importance of encephalization, the process by which brain mass increased dramatically in relation to total body mass that occurred in the human lineage.
However, a new study which used bioinformatics to compare the synapses of distantly related species suggests that size may not be the most important factor in human brain…
neurophilosophy | June 8, 2008
Logo by Ricardo at My Biotech Life
Welcome to the 33rd edition of Gene Genie, the blog carnival devoted to genes and genetic diseases.
In this edition, there is a strong emphasis on cancer. There's also a focus on leukodystrophy, and a special section on personalized genetics.
Spotlight on Leukodystrophy
The term leukodystrophy refers to a group of diseases characterized by progressive degeneration of the white matter in the brain. The conditions are normally inherited, and are associated with mutations in the genes encoding components of the myelin sheath.
Leukodystrophy came under the…
neurophilosophy | May 17, 2008The brain is an organ of staggering complexity, consisting of hundreds of billions of cells (and tens of thousands of different cell types) which form millions of specialized circuits that are organized into thousands of discrete areas. Neuroscientists have a number of methods for investigating brain circuitry and the connectivity of neurons within circuits. One of these involves exploiting the abilities of certain viruses, such as the herpes viruses, to target nerve cells; genetically manipulated viruses can be used to trace the synaptic connections between cells. This method has its…
grrlscientist | May 2, 2008tags: Elizabeth Blackburn, Joan Steitz, Albany Medical Center Prize
I learned this afternoon that America's highest prize in medicine, the Albany Medical Prize in Medicine and Biomedical Research, was awarded to two women for the first time in its history. The recipients, Elizabeth Blackburn of the University of California, San Francisco, and Joan Steitz of Yale University will share the $500,000 prize, which is second only to the $1.4 million Nobel Prize. The two medical scientists, who work independently of each other, study proteins associated with DNA and RNA, and their work will likely…
grrlscientist | April 25, 2008tags: researchblogging.org, evolution, dinosaurs, birds, Tyrannosaurus rex, ornithology, paleontology
The Tyrannosaurus rex femur from which researcher Mary Higby Schweitzer of North Carolina State University recovered soft tissue.
Image: Science.
It wasn't too long ago that paleontologists thought that fossilization was a process where all biological material was replaced with inert stone. However, in 2005, Mary Higby Schweitzer of North Carolina State University rocked the paleontological world when she recovered a still-elastic blood vessel from inside a fractured thigh bone fossil of…
edyong | April 25, 2008
If it looks like a dead cell and it feels like a dead cell, be careful - it could be a virus. Viruses are experts at infiltrating and exploiting cells but some are so big that they need to use special tricks. The Vaccinia virus is one of these. It belongs to the same family as the more infamous variola virus that causes smallpox. This group are among the largest of viruses, dwarfing many other types by a factor of ten. But despite its size, Vaccinia relies on stealth rather than brute force.
It's a mimic and it disguises itself as cellular flotsam. Vaccinia carries a molecular tag on its…
pharyngula | April 14, 2008Jay Hosler has a new book out, Optical Allusions(amzn/b&n/abe/pwll). If you're familiar with his other books, Clan Apis(amzn/b&n/abe/pwll) and The Sandwalk Adventures(amzn/b&n/abe/pwll), you know what to expect: a comic book that takes its science seriously. Hosler has a fabulous knack for building serious content into a light and humorous medium, just the kind of approach we need to get wider distribution of science into the culture.
This one has a strange premise. Wrinkles the Wonder Brain is an animated, naked brain working for the Graeae Sisters, and he loses the one eye they…
edyong | April 11, 2008For comic book characters, big doses of radiation are a surefire way of acquiring awesome superpowers, but in real life, the results aren't quite as glamorous. A victim of acute radiation poisoning can look forward to hair loss, bleeding, the destruction of their white blood cells and bone marrow, and severe damage to their spleen, stomach and intestines.
Radiation doesn't kill cells directly, but it can cause so much damage that they commit suicide, by enacting a failsafe program called apoptosis. Now, Lyudmila Burdelya and colleagues from Roswell Park Cancer Institute have found a way to…
evolgen | April 8, 2008Us dudes are always accused of thinking with our dicks. Perhaps it's because the genes expressed in our brains are similar to those expressed in our 'nads:
Among the 17 tissues, the highest similarity in gene expression patterns was between human brain and testis, based on DDD and clustering analysis. Genes contributing to the similarity include ribosomal protein (RP) genes as well as genes involved in transcription, translation and cell division.
The authors of the paper allege that their result has something to do with speciation. They even claim, "Brain is the most important tissue in…
neurophilosophy | April 6, 2008What with the current debate about the use of "smart" drugs by academics, I thought it pertinent to republish this old piece from January of last year, about a bacterial toxin which has been shown to enhance fear conditioning and spatial memory in mice.
In the late nineteenth century, the great Spanish neuroanatomist Santiago Ramon y Cajal suggested that memories might be formed by the strengthening of connections between nerve cells:
Cerebral gymnastics are not capable of improving the organization of the brain by increasing the number of cells, because it is known that the nerve cells…
edyong | March 25, 2008We've all seen the images of receding glaciers and stranded polar bears that accompany talks of climate change. But rising carbon dioxide levels also have subtler and less familiar effects, and may prove to be a boon for many animal groups. Plant-eating insects, for example, have much to gain in a high -CO2 future as rising concentrations of the gas can compromise the defences of the plants they feed on.
Plants and herbivorous insects are engaged in a silent war that we are rarely privy too, where chemicals act as both weapons and messengers. Munching mandibles trigger the production of…
pharyngula | March 20, 2008
The Harvard multimedia team that put together that pretty video of the Inner Life of the Cell has a whole collection of videos online (including Inner Life with a good narration.) Go watch the one titled F1-F0 ATPase; it's a beautiful example of a highly efficient molecular motor, and it's the kind of thing the creationists go ga-ga over. It's complex, and it does the same rotary motion that the bacterial flagellum does; it has a little turbine in the membrane, a stream of protons drives rotation of an axle, and the movement of that axle drives conformation changes in the surrounding protein…
pharyngula | March 19, 2008
Fossils are cool, but some of us are interested in processes and structures that don't fossilize well. For instance, if you want to know more about the evolution of mammalian reproduction, you'd best not pin your hopes on the discovery of a series of fossilized placentas, or fossilized mammary glands … and although a few fossilized invertebrate embryos have been discovered, their preservation relied on conditions not found inside the rotting gut cavity of dead pregnant mammals.
You'd think this would mean we're right out of luck, but as it turns out, we have a place to turn to, a different…
grrlscientist | March 15, 2008tags: genetics, Bill Nye the Science Guy, education, streaming video
Those of you who do not know who Bill Nye the Science Guy! is will especially enjoy this video. In this streaming episode, Bill Nye the Science Guy explores the science behind genes (part 3). Basically, you can thank your parents for all those nice pairs of genes. Chromosomes are made up of sequences of genes, which are themselves made up of strands of DNA. The mutations in DNA during replication cause resulting changes within genes, which is the basis of evolution. [8:54].