Evolutionary Physiology of Closely Related Taxa: Analyses of Enzyme Expression

Comparative biochemistry and physiology offer the advantageof specifically defining the functional parameters or traitsthat affect an organism's performance (e.g., amino acids thataffect K_m, enzymes that affect metabolism). By combining thesefunctional determinations with both intraspecific and phylogeneticallyappropriate analyses, comparative biologists can indicate thata trait is biologically important by demonstrating that it isevolving by natural selection. An evolutionary approach maybenefit from the analysis of variation within and among closelyrelated species. The advantages of analyzing closely relatedspecies are that they allow one to identify more definitivelythe derived conditions and suggest why differences arose. Importantly,there is substantial variation in physiological and biochemicaltraits within and among closely related species. For example,among species within a single genus of teleost, Fundulus, thevariation in enzyme expression is similar to the variation seenamong most superorders of teleost. However, most of the variationwithin the genus Fundulus is most readily explained by evolutionarydistance, and thus there is no compelling reason for furtheradaptive hypotheses. Extending this observation, the greaterthe phylogenetic distance between taxa in a comparative study,the more likely there will be a statistically significant differencethat may only represent evolutionary time. The molecular mechanismsaffecting adaptive variation in enzyme expression appear tobe readily altered and may vary within a species or betweenacclimation conditions. Thus, studies among closely relatedorganisms are more likely to identify the specific molecularor biochemical changes responsible for adaptive variation.     

The capsule polysaccharide structure and biogenesis for non-O1 Vibrio cholerae NRT36S: genes are embedded in the LPS region

Background  

In V. cholerae, the biogenesis of capsule polysaccharide is poorly understood. The elucidation of capsule structure and biogenesis is critical to understanding the evolution of surface polysaccharide and the internal relationship between the capsule and LPS in this species. V. cholerae serogroup O31 NRT36S, a human pathogen that produces a heat-stable enterotoxin (NAG-ST), is encapsulated. Here, we report the covalent structure and studies of the biogenesis of the capsule in V. cholerae NRT36S.     

Genomics and the renaissance of generalism

A meeting report of the sessions on human, eukaryotic and bacterial genome sequencing at the American Society for Microbiology and Institut Pasteur joint conference: Genomes 2000 International Conference on Microbial and Model Genomes, Paris, April 11-15, 2000     

Use of Volatile Organic Components in Scat to Identify Canid Species

Abstract: Identification of wildlife species from indirect evidence can be an important part of wildlife management, and conventional methods can be expensive or have high error rates. We used chemical characterization of the volatile organic constituents (VOCs) in scat as a method to identify 5 species of North American canids from multiple individuals. We sampled vapors of scats in the headspace over a sample using solid-phase microextraction and determined VOC content using gas chromatography with a flame ionization detector. We used linear discriminant analysis to develop models for differentiating species with bootstrapping to estimate accuracy. Our method correctly classified 82.4% (bootstrapped 95% CI = 68.8–93.8%) of scat samples. Red fox (Vulpes vulpes) scat was most frequently misclassified (25.0% of scats misclassified); red fox was also the most common destination for misclassified samples. Our findings are the first reported identification of animal species using VOCs in vapor emissions from scat and suggest that identification of wildlife species may be plausible through chemical characterization of vapor emissions of scat. (JOURNAL OF WILDLIFE MANAGEMENT 72(3):792–797; 2008)     

Design and baseline characteristics of the ParkFit study,a randomized controlled trial evaluating the effectiveness of a multifaceted behavioral program to increase physical activity in Parkinson patients

Background  

Many patients with Parkinson's disease (PD) lead a sedentary lifestyle. Promotion of physical activities may beneficially affect the clinical presentation of PD, and perhaps even modify the course of PD. However, because of physical and cognitive impairments, patients with PD require specific support to increase their level of physical activity.     

Fairy, tadpole, and clam shrimps (Branchiopoda) in seasonally inundated clay pans in the western Mojave Desert and effect on primary producers

Background

Fairy shrimps (Anostraca), tadpole shrimps (Notostraca), clam shrimps (Spinicaudata), algae (primarily filamentous blue-green algae [cyanobacteria]), and suspended organic particulates are dominant food web components of the seasonally inundated pans and playas of the western Mojave Desert in California. We examined the extent to which these branchiopods controlled algal abundance and species composition in clay pans between Rosamond and Rogers Dry Lakes. We surveyed branchiopods during the wet season to estimate abundances and then conducted a laboratory microcosm experiment, in which dried sediment containing cysts and the overlying algal crust were inundated and cultured. Microcosm trials were run with and without shrimps; each type of trial was run for two lengths of time: 30 and 60 days. We estimated the effect of shrimps on algae by measuring chlorophyll content and the relative abundance of algal species.

Results

We found two species of fairy shrimps (Branchinecta mackini and B. gigas), one tadpole shrimp (Lepidurus lemmoni), and a clam shrimp (Cyzicus setosa) in our wet-season field survey. We collected Branchinecta lindahli in a pilot study, but not subsequently. The dominant taxa were C. setosa and B. mackini, but abundances and species composition varied greatly among playas. The same species found in field surveys also occurred in the microcosm experiment. There were no significant differences as a function of experimental treatments for either chlorophyll content or algal species composition (Microcoleus vaginatus dominated all treatments).

Conclusions

The results suggest that there was no direct effect of shrimps on algae. Although the pans harbored an apparently high abundance of branchiopods, these animals had little role in regulating primary producers in this environment.     

Carcinoma is to Embryology as Mutation is to Genetics

Experiments are reviewed that indicate embryonic fields arecapable of regulating the neoplastic attributes of their closelyrelated carcinomas. In the case of blastocyst regulation ofembryonal carcinoma cells the reaction is mediated by contactof the cancer cells with trophectodermal cells in the presenceof blastocele fluid. In the case of regulation of melanoma,the reaction is mediated in the embryonic skin at the time normalmelanocytes migrate into it. A diffusible factor that inhibitscell division and seems to affect differentiation is involved.In the case of neuroblastoma, a degree of regulation is demonstrablein the neural crest migratory pathway, but the maximal effectis found in the adrenal, renal, and testicular primordia. Afactor inhibitory of mitosis for adenocarcinoma of the breastcan be demonstrated in the breast primordium. It is concludedthat there must be an embryonic field capable of regulatingevery kind of carcinoma: understanding of the phenomena maylead to a noncytotoxic cure for carcinoma, and through the useof cancer cells as probes of embryonic development to an understandingof embryonic induction.