BioUpdates for August, 2001

Let There Be No Light

Looks Can Be Deceiving

Heartening News

Researchers Go Forth and Multiply

Plugging the Leaks



Let There Be No Light

When we think of algae, we may be inclined to think of the algal blooms associated with fish kills. Few of us are aware that algae have practical applications. For example, they may be used as pigments in scientific labeling, ingredients in human dietary supplements, or feed for the aquaculture industry. Because researchers from Martek Biosciences Corporation and the Carnegie Institute of Washington do think of algae's practical uses, they have been investigating how to cultivate the microalga, Phaeodactylum tricornutum, in a controlled and protected indoor environment that facilitates high rates of growth and protection from contamination. The team finally achieved their goal with the introduction of glucose transporter genes obtained from human red blood cells and other types of algae. These genes provided the alga with an alternative to photosynthesis for energy production, thus eliminating its inherent need for sunlight and allowing it to grow in enclosed fermentation tanks. So far the experiments have shown growth rates as much as 15 times greater than in sunlight-grown algae, promising improved production and a final product free of microbial contamination, ready for use in many applications. Although the team believes their work demonstrates that basic metabolic changes can be achieved by introduction of a single gene, they see P.tricornutum as an isolated example. They predict that most metabolic engineering projects are likely to demand more complex solutions.

References:

Zaslaskaia, L.A. et al (2001) Trophic conversion of an obligate photoautotrophic organism through metabolic engineering. Science 292 (June 15^th): 2073-2075

Visit:

Martek Biosciences

http://www.martekbio.com/Corporate/Research_MB.asp

http://www.martekbio.com/Corporate/trophicconv.pdf

back to the top


Looks Can Be Deceiving
Two recent studies in genetic analysis, just reported in the Proceedings of the Royal Society, are going to challenge traditional classifications of aquatic birds and, by implication, perhaps the very structure of classification throughout the animal kingdom. Traditionally, aquatic birds have been classified according to the nature of various outward physical traits such as length of legs, beaks, and feet, but now two broad-ranging, independent genetic studies of aquatic birds are questioning the validity of such classifications. One research team from Penn State University targeted genes of 28 species of birds using DNA sequencing techniques for analysis, while a team from the University of Wisconsin compared the entire genomes of 21 species using a technique known as DNA-DNA hybridization.

Skeptics will want plenty of evidence to convince them that the closest living relative to the elegant, long-legged wading flamingo is the squat, short-legged diving grebe! In fact, the Penn State workers were doubtful enough of their own initial results that they examined other genetic data available for the two birds to confirm their conclusions. Each study, though, has generated an immense amount of persuasive data, and each study supports the other's conclusions. Further weight is added to their validity by the fact that two different analytical techniques were used. The study results also suggest that the development of such characteristics as long legs or webbed feet have evolved independently in a number of circumstances and that evolution, at least in aquatic birds, has proceeded at a much faster pace than previously believed.

References:

Van Tuinen, Marcel et al (2001) Convergence and divergence in the evolution of aquatic birds. Proceedings of the Royal Society (Biological Sciences) 268 (July 7^th): 1345

Visit:

Proceedings of Royal Society

http://www.pubs.royalsoc.ac.uk/proc_bio/pro_bio.html

Search for July 7^th, 2001 issue for abstract of above reference.

back to the top


Heartening News
No doubt because it remains the biggest killer in the U.S., heart disease continues to attract a lot of attention from the medical research community. While recent news of the implantation of a completely artificial heart has dominated the heart disease headlines, avenues of research concerning the repair and replacement of damaged heart tissue give reason for greater hope. Researchers from the University of Illinois at Chicago and Loyola University Medical Center are developing methods to more effectively study heart cell behavior in a laboratory setting. They have created a tiny artificial silicone polymer "scaffolding" to which actual heart cells can be attached, creating a more realistic simulation of heart cell behavior than can be accomplished by simply placing cells in a petri dish. Meanwhile, a research team from New York Medical College has discovered solid evidence suggesting, contrary to conventional wisdom, that heart cells regenerate after a heart attack. The researchers compared myocytes (heart muscle cells) from heart attack victims with myocytes from people free of heart problems. They observed elevated levels of Ki67, a protein associated with myocyte cell division, in those recently suffering heart attack. In short, they discovered up to 70 times as many replicating myocytes in the diseased hearts as in the healthy hearts, implying the heart was undergoing repair. The team leader, Piero Anversa, wonders whether some form of heart stem cell is present in the heart and could be manipulated to facilitate the heart's self-repair abilities.

In a similar vein, researchers from Baylor College of Medicine in Houston have observed that bone marrow stem cells in mice can develop into heart tissue. The natural rate of production appears inadequate to combat a catastrophic incident such as a heart attack, but the team is looking at ways to enhance the process. They believe that ultimately a targeted therapy might be developed to facilitate the repair and replacement of damaged cardiac tissue. The team is also suggesting that the treatment could be administered through the bloodstream, thus bypassing the need for risky heart surgery. All this work is still in early experimental stages, but discoveries and techniques are now occurring at an accelerated pace, and treatment of heart disease seems on the verge of even greater revolutions. Artificial hearts may become redundant within a heartbeat.

References:

Anversa, Piero et al (2001) Evidence That Human Cardiac Myocytes Divide After Myocardial Infarction. New England Journal of Medicine 344 (June 7^th): 1750-1757

Jackson, Kathyjo A. et al (2001) Regeneration of ischemic cardiac muscle and vascular endothelium by adult stem cells. Journal of Clinical Investigation 107 (June 1^st): 1395-1402

Visit:

Science Daily News Releases

http://www.sciencedaily.com/releases/2001/06/010614063805.htm

http://www.sciencedaily.com/releases/2001/06/010607075716.htm

http://www.sciencedaily.com/releases/2001/06/010601082914.htm

New England Journal of Medicine

http://www.nejm.org/cgi/content/abstract/344/23/1750

Abstract of above reference

Journal of Clinical Investigation

http://www.jci.org/cgi/content/abstract/107/11/1395

Abstract of above reference

back to the top


Researchers Go Forth and Multiply
Historically, species primarily have been defined by appearance and morphological characteristics. But in recent years DNA analysis has provided more sophisticated tools with which to identify and define species. The results have been revolutionary (as already seen in another of this month's BioUpdates), indicating that biodiversity is even greater than previously realized. Essentially, researchers are discovering that animals appearing to the naked eye to be the same species are in fact different species, genetically distinct and incapable of breeding with each other. David Wake and colleagues at the University of California, Berkeley, are leaders in this field of study and have revealed many new species with their work, identifying this expanding diversity as "cryptic biodiversity". The species list is growing; for example, the number of salamander species is currently increasing by 2% per year. Naturally, the number of species going extinct each year is also increasing. The implications of these discoveries pose challenging questions for those enforcing the Endangered Species Act.

Most recently, Wake and his colleagues have published a report concerning a particular genus of salamander, Lineatriton. This salamander possesses the ability to rapidly burrow into the soil to escape predators. One species in the genus, Lineatriton lineolus, lives in the Veracruz region of the Mexican coast. DNA analysis was performed on animals from other regions thought to be individuals of the same species. It was discovered that they were a different species that had coincidentally developed similar features to solve the same evolutionary problem. Previous work by Wake has also revealed that California's Batrachoseps altennatus salamander is in fact over 20 different species and lives in coastal habitats from Oregon to Mexico .

Visit:

UC Berkeley Press Releases

http://www.berkeley.edu/news/media/releases/2001/06/28_sldna.html

Press release concerning above research.

Plugging the Leaks
In examining the mouse-ear cress (Arabidopsis thaliana), researchers from Penn State and the University of North Carolina are unlocking secrets, about plants' ability to retain water, that could ultimately benefit both farmers and the environment. Normally, according to environmental conditions, guard cells around stomatal pores regulate the release of water and oxygen and the intake of carbon dioxide for photosynthesis by plants' leaves. While observing how the hormone abscisic acid signals the guard cells in A.thaliana to promote water conservation during droughts, the researchers observed the role of the G-protein alpha subunit. In cases where this protein had been eliminated, the plant had lost its response to abscisic acid, increasing the degree of water loss. So in A.thaliana, at least, it would appear that this protein is the key to moisture retention and that its manipulation would lead to greater drought resistance. It is by no means certain that the same mechanisms operate similarly in other plants, but this discovery certainly provides strong clues for future research. The engineering of plants with greater ability to retain water could significantly reduce irrigation needs and cut costs for farmers. The demand on increasingly precious water resources, as well as the negative impact of excessive irrigation on the land, could also be reduced.

References:

Xi-ing Wang et al (2001) G Protein Regulation of Ion Channels and Abscisic Acid Signaling in Arabidopsis Guard Cells. Science 292 (June 15th): 2070-2072.

Visit:

Science

http://www.sciencemag.org/cgi/content/abstract/292/5524/2070
Abstract of above reference.