Genetics & Molecular Biology

Our genes may not be the basis for human individuality, according to new studies in Science and Nature. The key may actually lie in the sequences that surround and control our genes.

The interaction of those sequences with a class of proteins, called transcription factors, can vary significantly between two people and are likely to affect our appearance, our development and even our predisposition to certain diseases.

The discovery suggests that researchers focusing exclusively on genes to learn what makes people different from one another have been looking in the wrong place.

Information processing and entropy management - that's what organisms are about, right? Information and entropy are terms that get people excited, and yet it's extremely difficult to integrate formal ideas about information, free energy, entropy, etc. (much of this from modern statistical mechanics) into a meaningful biological framework. People (including myself) love to toss around terms like entropy and information, but in most cases I have encountered, efforts to apply these concepts to molecular/cellular biology are hopelessly vague and unhelpful. Once you get beyond the level of individual proteins in biology, it's difficult to apply some of the traditional concepts of physical chemistry.
Sean Carroll at Cosmic Variance on Entropy and the Meaning of Life:

We know that entropy increases as the universe evolves. But why, on the road from the simple and low-entropy early universe to the simple and high-entropy late universe, do we pass through our present era of marvelous complexity and organization, culminating in the intricate chemical reactions we know as life?...
In a report published in the Proceedings of the National Academy of Sciences, researchers from The Wistar Institute suggest that mice that lack the p21 gene gain the ability to regenerate lost or damaged tissue.

The team says their findings provide solid evidence to link tissue regeneration to the control of cell division.

Unlike typical mammals, which heal wounds by forming a scar, these mice begin by forming a blastema, a structure associated with rapid cell growth and de-differentiation as seen in amphibians. The loss of p21 causes the cells of these mice to behave more like embryonic stem cells than adult mammalian cells
Researchers at the University of Minnesota have created a molecular image of a system that moves electrons between proteins in cells. The achievement is a breakthrough for biology and could provide insights to minimize energy loss in other systems, from nanoscale devices to moving electricity around the country. The research was published this week in Science.
Physicians have long recognized that pinpointing specific causes of disease in individual patients enables therapies that are the most likely to confer benefit with the fewest adverse effects. We also recognize the potential for disease prevention through identification of specific risk factors and mitigation of their effects. For a century, we have known that many of these risk factors are genetic. In the past 20 years, the genomic revolution has translated this knowledge into a new understanding of disease: mutations that cause more than 2000 mendelian diseases have been identified, which has led to the rewriting of textbooks of pathophysiology of every organ system and the identification of rational targets for therapeutic intervention.
Some chickens appear to be male on one side of the body and female on the other, and researchers writing in Nature this week say they know why.

It was previously thought that sex chromosomes in birds control whether a testis or ovary forms, with sexual traits then being determined by hormones.

The authors of the new study, however, identified differences between male and female cells that control the development of sexual traits. The scientists have named the phenomenon, cell autonomous sex identity (CASI).

The findings may also be relevant to why males and females differ in behavior and in susceptibility to disease.
Sonic hedgehog, a gene that plays a crucial rule in the positioning and growth of limbs, fingers and toes, has been found in the ectoderm - the cell layer that gives rise to the skin - in the embryos of developing mice. The gene was previously thought to be exclusively present in the cell layer that builds bone and muscle, called the mesoderm.

The discovery, detailed in PNAS, suggests that Sonic hedgehog's role in the growth of appendages is far more complex than originally thought. Developmental biologists may have to rethink established theories about how limbs are patterned in vertebrates — an effort that could provide insight into human birth defects.
A team of Georgia Institute of Technology scientists are reporting that molecules they term "unselfish" may have midwifed the birth of life's original (sometimes called "selfish") genes. The Georgia Tech scientists are investigating the possibility that intercalator molecules such as ethidium could have assisted life's non-living building blocks in forming complex organic chains and might have entered into the selection of DNA double helix base pairs.
This is the second in a present series, highlighting a particular incidence of  discrimination here and now, and those new to this may consider my intent to do some wider campaigning around this issue so here is a summary of what has happened since the first in this series was originally blogged.