BioUpdates for October, 2001

Making Stem Cells Less Divisive

Going Beyond the Fossil Record

The Promise of Everlasting Life

Cloning News

Breathtaking Announcement

Making Stem Cells Less Divisive

A research team from the Montreal Neurological Institute’s Centers for Neuronal Survival and Brain Tumor Research has identified stem cells, known as SKPs, from the skin of juvenile and adult rodents. Subsequent human studies suggest similar stem cells are also present in humans. These SKPs are believed to be less biased than other adult stem cells, possessing the ability to develop into neurons, glia, smooth muscle cells and fat cells.

The research team is excited about their discovery for other reasons. First, the source of these cells is free of the controversy surrounding embryonic stem cells. Second, in terms of medical applications the SKPs could potentially be derived from the individual requiring treatment. Such an autologous source of stem cells would probably eliminate the medical complications that so often occur when cells and organs are donated from another individual. In particular, the research team believes their discoveries may advance the treatment of Parkinson’s disease and other neuronal disorders.

Visit:

Nature Cell Biology

http://www.nature.com/ncb/future_issues/

This research has just been published in the online edition of Nature Cell Biology.

back to the top

Going Beyond the Fossil Record

A recent study just published in Science by researchers from Pennsylvania State University suggests that mosses and fungi began colonizing the Earth’s land surfaces considerably earlier than the fossil record can demonstrate. While the oldest known fossils date back to approximately 480 million years ago, analysis of the genes of modern mosses by the PSU team indicates that mosses first appeared on land about 700 million years ago and lichens about 1.3 billion years ago.

The team was able to develop these estimates by examining 119 genes common to existing species of fungi, plants and animals that met the criteria for use as “molecular clocks.” By comparing various amino acids, the team established a sequence of mutations that occur at a constant rate relative to each other. The team solidified their findings by calibrating their “gene clocks” to known evolutionary evidence clearly established in the fossil record. Armed with this knowledge the researchers were able to extrapolate backwards to determine how long it has taken for particular species to evolve.

From their findings the researchers believe that an aquatic fungi developed a terrestrial form of lichen about 1.3 billion years ago, bridging the gap between sea and land using a symbiotic relationship with a primitive aquatic plant. The chance that paleobotanists will be able to confirm the team’s projections using the fossil record is unlikely, as these types of organisms do not lend themselves to preservation. However, these techniques lead the way for examining the history of life when a fossil record is absent. Without a fossil record this type of study will be susceptible to criticism. Nonetheless, if sufficient genetic studies are conducted that can be calibrated with fossil evidence confidence in the ability to extrapolate beyond the fossil record will grow.

References:

Heckman, Daniel S. et al (2001). Molecular Evidence for the Early Colonization of the Land by Fungi and Plants. Science 293 (Aug10): 1129

Visit:

Science Magazine

http://www.sciencemag.org/content/vol293/issue5532/index.shtml#researcharticles

Abstract of above reference.

Paleobotany

http://members.aol.com/fostrak/palebota.htm

Paleobotany Links

http://www.uni-wuerzburg.de/mineralogie/palbot1.html

Paleobotany Research Group

http://www.uni-muenster.de/GepPalaeontologie/Palaeo/Palbot/seite3.html

Botanical Society of America – Paleobotany

http://www.dartmouth.edu/~daghlian/paleo/

back to the top

The Promise of Everlasting Life

It is a fact of life that our ability to grow new tissue and heal is compromised as we age. However, researchers from the University of Illinois in Chicago appear to have made considerable progress in understanding how to combat the aging process and counter the various health problems associated with the elderly.

The team designed an experiment to examine the role of the FoxM1B gene that previous studies indicated was associated with age-related defects in cell proliferation. The researchers introduced an agent that promote the expression of the FoxM1B gene to one group of aging mice, while leaving another group untreated. Subsequently, all the mice had a part of their liver removed. Examination showed that the mice with increased expression of the Fox M1B gene experienced the regeneration of liver cells comparable to that found in younger mice, while the second untreated group exhibited much slower recovery. Additionally the treated mice showed an overall increase in the activity of other genes connected to cell division.

These findings also suggest that the FoxM1B gene influences cell division. This is important because when cell division continues at an abnormal pace, health problems can arise, such as cancer. Because the FoxM1B gene is found throughout the human body, the researchers believes their work could lead to therapies being developed to combat age-related health problems such as organ failure, Alzheimer’s disease, cancer and more.

References:

Costa, Robert H. et al (2001). Increased levels of forkhead box M1B transcription factor in transgenic mouse hepatocytes prevent age-related proliferation defects in regenerating liver. Proceedings of the National Academy of Sciences 98 (Sept 25): 11468-11473

Visit:

Proceedings of the National Academy of Sciences

http://www.pnas.org/cgi/content/abstract/98/20/11468

back to the top

Cloning News

Ever since the cloned sheep “Dolly” was introduced to the world, the prospect of human cloning has raised many scientific and ethical questions. Among the objections is the fact that the cloning of animals has proved to be more problematic than most realize. Animals cloned so far have developed major problems: they are prone to fetal overgrowth, are more susceptible to cancer and have weaker immune systems. These complications provide a strong ethical argument against pursuing human cloning.

However, researchers from Duke University Medical Center have identified a key genetic difference between primates (including humans) and other mammals that suggest cloning humans would probably result in far fewer complications than other mammals. The geneticists discovered that primates receive two activated copies of a gene called insulin-like growth factor II receptor (IGF2R) while other mammals receive only one functional copy because of a phenomenon known as genomic imprinting. This subtle genetic difference means primates are considerably less likely to succumb to the complications that can occur when cloning other animals. The latest gene mapping technology allowed the researchers to use varieties of single nucleotide polymorphisms to test for the presence of imprinting. The results provide definitive evidence that human IGF2R is not imprinted. The prospects of “safer” human cloning weakens one argument against its pursuit and will likely cause cloning opponents to find other ethical and social objections.

References

Jirtle. Randy L. et al (2001). Divergent evolution in M6P/IGF2R imprinting from the Jurassic to the Quaternary. Human Molecular Genetics 10 (Aug 15): 1721-1728.

Visit:

Human Molecular Genetics

http://hmg.oupjournals.org/cgi/content/abstract/10/17/1721

Abstract of above reference.

Science Daily Press Releases

http://www.sciencedaily.com/releases/2001/08/010815080314.htm

Press release about the discovery.

Genomic Imprint Website

http://www.geneimprint.com

Genomic Imprinting

http://www.ucalgary.ca/~browder/imprint.html

Breathtaking Announcement

We have all seen those textbook diagrams matching the different regions of the brain to specific functions, but in reality those maps are imprecise. Although recent research has fine-tuned these maps, knowledge of which exact part of the brain controls breathing has been sparse. However, discoveries by neurobiologists at UCLA are changing that picture.

Recently, the research team had identified the “preBotzinger Complex” as the brain’s command post for breathing in mammals, and now follow-up research using rats has pinpointed the exact neurons that generate breathing. Focusing on only 600 neurons in a group of rats, they stained a marker on these cells and then administered a toxin that targeted the stained cells. In the rats where over 80% of these neurons were killed, the animals displayed noticeable breathing problems. Breathing became highly irregular and the rat’s lost their ability to control oxygen and carbon dioxide levels in the bloodstream. Because the layout of brains is very similar in all mammals, the research team now hopes to find the same neurons in the human brain. Once located, comparative studies between healthy individuals and those suffering breathing disorders could be very revealing and lead the way to the development of various diagnostic tests and treatments to combat conditions ranging from sleep apnea to sudden infant death syndrome (SIDS).

Reference:

Feldman, Jack L. et al (2001). Normal breathing requires preBotzinger complex neurokinin-1 receptor-expressing neurons. Nature Neuroscience 4 (Sept): 927-930

Visit:

Nature Neuroscience

http://www.nature.com/cgi-taf/DynaPage.taf?file=/neuro/journal/v4/n9/abs/nn0901-927.html

Abstract of above reference.