Effects of high sodium intake diet on the vascular reactivity to phenylephrine on rat isolated caudal and renal vascular beds: Endothelial modulation

High salt intake is involved in the genesis of hypertension and vascular changes in salt-sensitive patients. Although many mechanisms have been proposed, the underlying mechanisms of these alterations in healthy rats are not completely elucidated. The aim of this study was to investigate if male Wistar rats fed a high salt diet, NaCl 1.8% in drinking water for 4 weeks, develop changes in the pressor reactivity of isolated tail and renal vascular beds. Salt treatment increased mean arterial pressure (SALT = 124 +/- 2.2 vs. CT = 111 +/- 3.9 mmHg; p < 0.01) and urinary sodium excretion in the absence of changes in sodium plasma levels. Pressor reactivity was generated in isolated tail and kidney vascular beds as dose-response curves to phenylephrine (PHE = 0.01 to 300 microg). SALT increased the reactivity (E(max): SALT = 378 +/- 15.8 vs. CT = 282 +/- 10 mmHg; p < 0.01) without changing the sensitivity (pD(2)) to PHE in the tail vascular bed. However, these parameters did not change in the renal bed. In subsequent studies on the isolated caudal vascular bed, we found that endothelial damage, but not L-NAME (100 microM) or indomethacin (10 microM), abolished the increment in E(max) to PHE induced by SALT. On the other hand, losartan (100 microM) reduced E(max) in SALT to CT values. Additionally, local angiotensin-converting enzyme activity in segments from tail artery increased by 95%. In conclusion, 4 weeks of high salt diet increases blood pressure and induces specific territorial vascular changes in response to PHE. Results also suggest that the increment in E(max) in the tail vascular bed from SALT rats was endothelium-dependent and was mediated by the activation of the local renin-angiotensin system.     

Chronic CO levels have [corrected] a beneficial effect on vascular relaxation in diabetes

Heme oxygenase (HO) has been shown to provide cytoprotection to the vascular system in diabetes. Isolated femoral arteries from diabetic rats treated with cobalt protoporphyrin (CoPP) exhibited increased relaxation to acetylcholine (ACh), which was markedly decreased in control diabetic rats. In control rats treated with either CoPP or with CO releasing molecules-3 (CORM-3), but not in rats treated with biliverdin, we observed an increased dilatory response to ACh. The inhibition of guanylyl-cyclase (GC) with 1H-[1,2,4]Oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) caused a contractile response to ACh in control rats and in biliverdin-treated rats, while in rats treated with CoPP and CORM-3, the ACh dilatory effect was only decreased. Moreover, the inhibition of HO with chromium mesoporphyrin did not change the response to ACh in rats treated with CoPP, suggesting that the improving effect of overproduction of CO on vascular reactivity is due to a decrease in iNOS and the beneficial effect on vascular function.     

Rapid synthesis of partially O-methylated alditol acetate standards for GC-MS: some relative activities of hydroxyl groups of methyl glycopyranosides on Purdie methylation

Mixtures containing the majority of partially O-methylated alditol acetates (PMAAs), necessary for the GC-MS based identification of glycosidic linkages in oligo- and polymeric structures were prepared. Rha, Fuc, Rib, Ara, Xyl, Man, Gal, and Glc were converted to their Me glycosides, and the products were progressively O-methylated using the Purdie reagent at 25 degrees C. Resulting PMGs were assayed by TLC and at times that were optimum for formation of mono-O-methyl derivatives and later for higher degrees of methylation; they were converted to PMAAs, in a process incorporating NaB(2)H(4) reduction. The majority of these can be used as standards for simultaneous identification of pyranosides and some furanosyl units particularly in heteropolysaccharides. The relative reactivities of OH-groups were determined by GC-MS as: Me alpha- and beta-Glcp, HO-2>HO-4>HO-3>HO-6, Me alpha- and beta-Galp, HO-3>HO-2>HO-4>HO-6, Me alpha-Manp, HO-3>HO-2>HO-4>HO-6, Me beta-Manp, HO-3>HO-4HO-6>HO-2, Me alpha-Rhap, OH-3>OH-2>OH-4; Me alphabeta-Fucp, OH-2>OH-3>OH-4, and Me alphabeta-Xylp, OH-2>OH-4>OH-3. The results differ from those obtained with Haworth, Hakomori, and Ciucanu methylation techniques, although some similarities occurred with the more rapid Kuhn method.     

Cross-species amplification of bovid microsatellites in central African duikers (genus Cephalophus) and other sympatric artiodactyls

The present study set out to evaluate cross-species amplification of 34 bovid microsatellites in six central African duikers: Cephalophus callipygus, C. monticola, C. silvicultor, C. nigrifrons, C. dorsalis and C. leucogaster. Of these loci, 16 amplified across all species and appeared polymorphic when initially tested in polyacrylamide gel electrophoresis. Twelve of these loci were subsequently assembled into three multiplex panels of four loci each. These multiplexes successfully amplified across all six duiker species in the present study and the sympatric artiodactyls Tragelaphus spekei and Hyemoschus aquaticus. The only exception was the locus BM848 that did not amplify from C. leucogaster. For species with sufficient sample sizes (C. callipygus and C. monticola), the number of alleles ranged from three to ten and four to fifteen, respectively. Three loci deviated from Hardy–Weinberg equilibrium in C. callipygus and five in C. monticola. We attribute the latter result to possibilities of local population substructuring or to an excess of homozygotes because of null alleles. These multiplex assemblies will greatly facilitate studies of individual identification, parentage analysis, population size estimation and fine-scale analyses of population genetic structure in central African artiodactyls.     

Cross-species amplification of 92 microsatellites of Medicago truncatula

Medicago species are important genetic sources for forage crops and nitrogen sources for various ecosystems. The ongoing genome sequencing of the model legume, Medicago truncatula, provides a wealth of genetic markers potentially useful for characterizing the population genetic structure and evolutionary history, and the potential of the wild Medicago species. Here we tested the PCR amplification of 92 microsatellites developed from M. truncatula in six other Medicago species, and found that the cross-species transferability, ranging from 53.26% to 61.96%, is comparable with those reported in other angiosperm genera. This article thus reports a number of microsatellites that are potentially useful for large-scale ecological and evolutionary genetic studies of wild Medicago species.     

Influence of an Interpersonal Laboratory Stressor on Youths’ Choice to Be Physically Active

Objective: To determine whether interpersonal stress reduces youths’ motivation to exercise in a laboratory setting. Research Methods and Procedures: Physical activity and sedentary behavior were measured in boys and girls across a control day, after reading children's magazines, and on a stress day, after giving a videotaped speech. For one analysis, children were divided into low (n = 12) and high (n = 13) heart‐rate reactivity groups based on changes in heart rate to stress. In a second analysis, children were divided into low and high perceived level of stress based on changes in perceived stress. To determine differences in choice of exercise or sedentary behavior across the control and stress conditions, subjects chose either to exercise for progressively longer periods to earn a monetary reinforcer or to engage in a high‐rated sedentary behavior. Results: The choice to exercise was influenced by stress reactivity differently in the stress and control conditions. Low heart‐rate reactive children participated in similar (p > 0.50) amounts of exercise on the stress and control days, but high heart‐rate reactive children participated in less (p < 0.01) exercise (22.0 ± 2.5 vs. 26.3 ± 2.2 minutes) on the stress than control days. When grouped by change in perceived stress, there were no group differences, but subjects exercised longer (p < 0.01) on the control day than the stress day. Discussion: Interpersonal stress decreased exercise in children susceptible to interpersonal stress. Stress‐induced alterations in health behaviors may lead to weight gain in children.     

Monoclonal antibodies to choline acetyltransferase of rat brain

Monoclonal antibodies to rat brain choline acetyltransferase were produced by the hybridoma technique. Two stable cell lines, Ab-57 and Ab-60, secreted immunoglobulin of subclass IgG1. The monoclonal antibodies bound to choline acetyltransferase without blocking catalytic activity. Affinity of Ab-57 was 100-times higher than that of Ab-60. Both antibodies bound to the rat enzyme in a mutually exclusive fashion. The antibodies showed cross-species reactivity with choline acetyltransferase from several mammalian brains.     

Independent fusions and recent origins of sex chromosomes in the evolution and diversification of glass knife fishes (Eigenmannia)

The genus Eigenmannia comprises several species groups that display a surprising variety of diploid chromosome numbers and sex-determining systems. In this study, hypotheses regarding phylogenetic relationships and karyotype evolution were investigated using a combination of molecular and cytogenetic methods. Phylogenetic relationships were analyzed for 11 cytotypes based on sequences from five mitochondrial DNA regions. Parsimony-based character mapping of sex chromosomes confirms previous suggestions of multiple origins of sex chromosomes. Molecular cytogenetic analyses involved chromosome painting using probes derived from whole sex chromosomes from two taxa that were hybridized to metaphases of their respective sister cytotypes. These analyses showed that a multiple XY system evolved recently (<7 mya) by fusion. Furthermore, one of the chromosomes that fused to form the neo-Y chromosome is fused independently to another chromosome in the sister cytotype. This may constitute an efficient post-mating barrier and might imply a direct function of sex chromosomes in the speciation processes in Eigenmannia. The other chromosomal sex-determination system investigated is shown to have differentiated by an accumulation of heterochromatin on the X chromosome. This has occurred in the past 0.6 my, and is the most recent chromosomal sex-determining system described to date. These results show that the evolution of sex-determining systems can proceed very rapidly.     

Reactivity of ferritin and the structure of ferritin-derived ferrihydrite

Background

In nature or in the laboratory, the roughly spherical interior of the ferritin protein is well suited for the formation and storage of a variety of nanosized metal oxy-hydroxide compounds which hold promise for a range of applications. However, the linkages between ferritin reactivity and the structure and physicochemical properties of the nanoparticle core, either native or reconstituted, remain only partly understood.

Scope of review

Here we review studies, including those from our laboratory, which have investigated the structure of ferritin-derived ferrihydrite and reactivity of ferritin, both native and reconstituted. Selected proposed structure models for ferrihydrite are discussed along with the structural and genetic relationships that exist among several different forms of ferrihydrite. With regard to reactivity, the review will emphasize studies that have investigated the (photo)reactivity of ferritin and ferritin-derived materials with environmentally relevant gaseous and aqueous species.

Major conclusions

The inorganic core formed from apoferritin reconstituted with varied amounts of Fe has the same structural topology as the inorganically derived ferrihydrite that is an important component of many environmental and soil systems. Reactivity of ferritin toward aqueous species resulting from the photoexcitation of the inorganic core of the protein shows promise for driving redox reactions relevant to environmental chemistry.

General significance

Ferritin-derived ferrihydrite is effectively maintained in a relatively unaggregated state, which improves reactivity and opens the possibility of future applications in environmental remediation. Advances in our understanding of the structure, composition, and disorder in synthetic, inorganically derived ferrihydrite are shedding new light on the reactivity and stability of ferrihydrite derived artificially from ferritin.