Scientists reverse brain birth defects in animal models

Prof Joseph Yanai and his associates at the Hebrew University were able to overcome neural and behavioral birth defects in mice by using mouse embryonic neural stem cells. These cells migrate in the brain, search for the deficiency that caused the defect, and then differentiate into becoming the cells needed to repair the damage.

Neural and behavioral birth defects, such as learning disabilities, are said to be particularly difficult to treat, compared to defects with known cause factors such as Parkinson’s or Alzheimer’s disease, because the prenatal teratogen — the substances that cause the abnormalities — act diffusely in the fetal brain, resulting in multiple defects.

In the animal model, researchers were able to reverse learning deficits in the offspring of pregnant mice who were exposed to organophosphate (a pesticide) and heroin. This was done by direct neural stem cell transplantation into the brains of the offspring. According to the scientists, the recovery was almost 100 percent, as proved in behavioral tests in which the treated animals improved to normal behavior and learning scores after the transplantation. On the molecular level, brain chemistry of the treated animals was also restored to normal.

However, the researchers have also discovered that the neural stem cells succeed before they die in inducing the host brain itself to produce large number of stem cells, which repair the damage. This discovery was published earlier this year in one of the leading journals in the field, Molecular Psychiatry.

The scientists are now in the midst of developing procedures for the least invasive method for administering the neural stem cells, which is probably via blood vessels, thus making the therapy practical and clinically feasible.

The research on the project was supported by the US National Institutes of Health, the US-Israel Bi-national Science Foundation and the Israel anti-drug authorities.

Bacteria thrive deep under sea floor

Analysis of sediments taken from hundreds of metres beneath the ocean floor has shown them to contain living microbes. According to a study produced by a team of researchers supported by the International Ocean Drilling Program, this is the first time that microbes have been found in abundance at such depths.

Scientists have long speculated about how much of the bacterial content of the sediments is biologically active. Techniques used to stain the bacteria and identify them could not previously discriminate between live and dead cells. For this study a new technique that could distinguish between alive and dead cells was used.

The results were surprising. The sediments, some of which had been collected from up to 800 metres from beneath the sea floor and are said to be up to 16 million years old, contained between 10-30% living bacteria. Scientists estimate that between 60-70% of all bacteria are living deep beneath the surface, far from any sunlight.

"We didn't have clear evidence that bacteria there were alive until now," said ecologist and team member Lev Neretin of the Max Planck Institute for Marine Biology in Bremen, Germany. According to calculations, the populations of bacteria multiply at the same rate as their surface cousins and contribute significantly to the balance of greenhouse gases, consuming and producing CO2. They also contribute methane via a metabolic process that does not require oxygen.

"Because they play such a major role in the biochemical processes in the subsurface, clearly they are driving lots of reactions that produce the chemical steady state on Earth," said Dr John Parkes, one of the original co-authors of the paper which appeared in Nature magazine, "possibly we might not have oil and gas formations without them."

How could these bacteria get so deep beneath the ocean floor? "The only reasonable way is for them to be buried there," says Bo Thamdrup, a microbiologist from the University of Southern Denmark, Odense. The extremes of temperature and pressures tolerated by these bacteria add weight to the assertion that microbes may flourish in the extreme conditions of other planets.
"It is well known that bacteria living in deep oceans have special adaptations to help them survive," says Thamdrup. "I'm sure these bacteria have special adaptations too." A full genetic analysis may soon reveal them

Study claims to show the difference between male and female brains

Michael Gurian, psychologist and author of "What Could He Be Thinking?", has claimed to identify approximately one hundred structural differences between male and female brains in a recent study.

Gurian comments:
"Men, because we tend to compartmentalize our communication into a smaller part of the brain, we tend to be better at getting right to the issue, the more female brain (will) gather a lot of material, gather a lot of information, feel a lot, hear a lot, sense a lot."One major structural difference that Gurian has made clear is that males generally have more activity in the mechanical centers of the brain, while women have more activity in centers of the brain dedicated to verbal communication and emotion. A clear example of this is the hypothetical situation of giving a child a toy.

He explains it as such:
"That doll becomes life-like to that girl, but you give it to a two-year-old boy and you are more likely, not all the time, but you are more likely than not to see that boy try to take the head off the doll. He thinks spatial-mechanical. He's using the doll as an object."Another expert, Dr. Marianne Legato, says it all boils down to genetics, noting that the Y chromosome (which only males carry) has "at least 21 unique genes unique to males which control many of the body's operations down to the level of the cells."

Gurian agrees that culture is significant in brain development, but argues that biology plays an equally important role. He makes a point of how the MRI scans show that the female corpus callosum, the center of the brain which regulates communication between the brain's hemispheres, is larger than the male's. On the other hand, the scans also show that information flows more freely between the hemispheres of the male brain.

The exact role that brain structure plays in behavior, however, has been an area of considerable contention in science for literally hundreds of years. Early studies in craniometry conducted by Paul Pierre Broca were used to attempt to distinguish differences between human races, though have now been dismissed as scientific racism. The nature-nurture debate has raged for centuries in a variety of forms, without yet any clear resolution as to the role in which innate biological tendencies interact with environmental conditions or willed behavior. As such, studies relating to brain structure and claims to innate behavior often generate substantial controversy.

MIT anthropologist of science Joseph Dumit's study of brain imaging in his book Picturing Personhood: Brain Scans and Biomedical Identity, noted that the apparent "transparency" of such pictures (the appearance that they can be easily interpreted by laymen, when they are often the source of ambiguity and dispute by even highly-trained neurosurgeons) has led to their proliferation as indicators of objective truth in media and in courts of law, and that such conclusions are often knowingly exaggerated by the specialists creating the images for better visual effect.

The timing of Gurian's book comes on the heels of another controversy over gender differences sparked by comments made by Harvard president Lawrence Summers, who blamed low numbers of women in the sciences on genetic differences. Summers has been criticized by a large number of academics and scientists, as well as by many news publications, in the wake of what he was reported as saying during a conference on January 14.