Development of microsatellite markers for southern catfish (Silurus meriaionalis) and cross‐species amplification in northern sheatfish (Silurus soldatovi)

Forty microsatellite markers were developed from a (CA)_n enrichment library created from the DNA of southern catfish (Silurus meriaionalis). Also, the population structure of northern sheatfish (Silurus soldatovi) was examined by 24 microsatellite loci. They are polymorphic in at least one of the two geographically distant populations sampled from the Heilongjiang River and the Songhuajiang River in North China, respectively. Unbiased expected heterozygosity levels varied from 0.435 to 0.946 and number of alleles per locus varied from three to 20. Results indicated that these microsatellite loci were highly polymorphic and could be used as genetic markers.     

Covalent attachment of proteins to solid supports and surfaces via Sortase-mediated ligation

Background

There is growing interest in the attachment of proteins to solid supports for the development of supported catalysts, affinity matrices, and micro devices as well as for the development of planar and bead based protein arrays for multiplexed assays of protein concentration, interactions, and activity. A critical requirement for these applications is the generation of a stable linkage between the solid support and the immobilized, but still functional, protein.

Methodology

Solid supports including crosslinked polymer beads, beaded agarose, and planar glass surfaces, were modified to present an oligoglycine motif to solution. A range of proteins were ligated to the various surfaces using the Sortase A enzyme of S. aureus. Reactions were carried out in aqueous buffer conditions at room temperature for times between one and twelve hours.

Conclusions

The Sortase A transpeptidase of S. aureus provides a general, robust, and gentle approach to the selective covalent immobilization of proteins on three very different solid supports. The proteins remain functional and accessible to solution. Sortase mediated ligation is therefore a straightforward methodology for the preparation of solid supported enzymes and bead based assays, as well as the modification of planar surfaces for microanalytical devices and protein arrays.     

Which Obesity Index Best Explains Prevalence Differences in Type 2 Diabetes Mellitus?

Objective: Obesity drives the diabetes epidemic. However, it is not known which obesity index best explains variations in type 2 diabetes mellitus prevalence across populations. Research Methods and Procedures: We analyzed three cross‐sectional studies from San Antonio, TX, (Mexican‐Americans and non‐Hispanic whites, n = 2839), Mexico City (n = 2233), and Spain (n = 2161) (age range, 35 to 64 years). We used the area under the receiver operating characteristic curve (AUC) to assess performance for identifying diabetic subjects and logistic regression analysis to examine differences in diabetes prevalence. Results: AUCs for waist circumference and BMI were similar in white subjects, but the AUC for waist circumference was greater in Mexican‐origin subjects (Mexican men, 0.594 vs. 0.549, p = 0.008; and women, 0.605 vs. 0.557, p = 0.002; Mexican‐American men, 0.648 vs. 0.600, p < 0.001; and women, 0.744 vs. 0.693, p < 0.001). The AUC for waist‐to‐height ratio tended to be greater than that for waist circumference, but statistical significance was demonstrated only in Mexican women (0.628 vs. 0.613, p = 0.044), Mexican‐American women (0.774 vs. 0.758, p < 0.001), and Spanish women (0.734 vs. 0.715, p = 0.039). No obesity index was consistently superior to the others for explaining differences in diabetes prevalence among populations. Conclusions: In white and Mexican‐origin men, waist circumference may be the preferred marker for identifying diabetic subjects on account of its simplicity; in women, waist‐to‐height ratio may be better. Differences in diabetes prevalence among these populations cannot be attributed to a single measure of obesity.     

Efficient identification of critical residues based only on protein structure by network analysis

Despite the increasing number of published protein structures, and the fact that each protein's function relies on its three-dimensional structure, there is limited access to automatic programs used for the identification of critical residues from the protein structure, compared with those based on protein sequence. Here we present a new algorithm based on network analysis applied exclusively on protein structures to identify critical residues. Our results show that this method identifies critical residues for protein function with high reliability and improves automatic sequence-based approaches and previous network-based approaches. The reliability of the method depends on the conformational diversity screened for the protein of interest. We have designed a web site to give access to this software at http://bis.ifc.unam.mx/jamming/. In summary, a new method is presented that relates critical residues for protein function with the most traversed residues in networks derived from protein structures. A unique feature of the method is the inclusion of the conformational diversity of proteins in the prediction, thus reproducing a basic feature of the structure/function relationship of proteins.     

Plasmodium strain determines dendritic cell function essential for survival from malaria

The severity of malaria can range from asymptomatic to lethal infections involving severe anaemia and cerebral disease. However, the molecular and cellular factors responsible for these differences in disease severity are poorly understood. Identifying the factors that mediate virulence will contribute to developing antiparasitic immune responses. Since immunity is initiated by dendritic cells (DCs), we compared their phenotype and function following infection with either a nonlethal or lethal strain of the rodent parasite, Plasmodium yoelii, to identify their contribution to disease severity. DCs from nonlethal infections were fully functional and capable of secreting cytokines and stimulating T cells. In contrast, DCs from lethal infections were not functional. We then transferred DCs from mice with nonlethal infections to mice given lethal infections and showed that these DCs mediated control of parasitemia and survival. IL-12 was necessary for survival. To our knowledge, our studies have shown for the first time that during a malaria infection, DC function is essential for survival. More importantly, the functions of these DCs are determined by the strain of parasite. Our studies may explain, in part, why natural malaria infections may have different outcomes.     

Homology of ciliary bands in Spiralian Trochophores

A number of hypotheses have been presented regarding the originsof the metazoans and, more specifically, the Bilateria. Usingvarious phylogenetic analyses, characteristics have been mappedon phylogenetic trees to infer ancestral body plans and lifehistory strategies of those ancestors. Many arguments on theevolution of the Bilateria are based on the presumed homologyof certain characteristics of extant larva and adults, includingvarious ciliated bands involved in feeding and locomotion. Thisarticle considers a recent study indicating that the second,downstream-collecting, ciliated band in the veliger larva ofthe gastropod mollusc, Crepidula fornicata, is actually derivedfrom secondary trochoblasts (derived from second quartet micromeres),that normally form part of the prototrochal band found in otherspiralian phyla (Hejnol et al. 2007). Despite previous arguments,these new findings suggest that the second ciliated band inthe veliger larva is not homologous to the metatroch found inthe trochophore larva of some other spiralians, such as theannelid, Polygordius lacteus. In the latter case, the metatrochwas reported to be formed by a different set of lineage precursors(derived from third quartet micromeres) (Woltereck 1904). Thesefindings have important implications for the interpretationof various hypotheses related to the evolution of metazoan phyla.     

Discovery of a natural thiamine adenine nucleotide

Several important cofactors are adenine nucleotides with a vitamin as the catalytic moiety. Here, we report the discovery of the first adenine nucleotide containing vitamin B1: adenosine thiamine triphosphate (AThTP, 1), or thiaminylated ATP. We discovered AThTP in Escherichia coli and found that it accumulates specifically in response to carbon starvation, thereby acting as a signal rather than a cofactor. We detected smaller amounts in yeast and in plant and animal tissues.     

Effect of exercise duration on postprandial hypertriglyceridemia in men with metabolic syndrome.

We examined the effect of exercise on postprandial hypertriglyceridemia (PHTG) and insulin resistance in individuals with metabolic syndrome. Subjects were 10 hypertriglyceridemic men with insulin resistance [age = 35.0 +/- 1.8 yr, body weight = 90.7 +/- 3.3 kg, fasting triglyceride (TG) = 2.6 +/- 0.4 mmol/l, peak oxygen consumption ((.)Vo(2peak)) = 36.0 +/- 1.3 ml(-1).kg(-1).min(-1), and homeostatic model assessment of insulin resistance (HOMA-IR)= 3.1 +/- 0.3]. Each participant performed a control trial (Ctr; no exercise) and three exercise trials at 60% of their (.)Vo(2peak) for 30 min (30 min-Ex), 45 min (45 min-Ex) and 60 min (60 min-Ex). All subjects had a fat meal in each trial. In the exercise trials, the subject jogged on a treadmill for a designated duration of 12 h before ingestion of a fat meal. Blood samples were taken at 0 h (before the meal) and at 2, 4, 6, and 8 h after the meal. The plasma TG, area score under TG concentration curve over an 8-h period (TG AUC) after the meal, and HOMA-IR were analyzed. The TG AUC scores in both the 45 min-Ex and 60 min-Ex were 31 and 33% lower, respectively, than Ctr (P < 0.02). There were no significant differences in TG AUC scores between the 30 min-Ex and the Ctr (P > 0.05). There were no trial differences in the fasting plasma glucose concentration (P > 0.05). HOMA-IR values in the 30 min-Ex, 45 min-Ex, and 60 min-Ex trials were lower than the Ctr (P < 0.03), but no significant differences were found in HOMA-IR among the exercise trials. The results suggest that for physically inactive individuals with metabolic syndrome, exercising at moderate intensity for 45 min effectively attenuates PHTG while exercise for 30 min is sufficient to improve insulin action.