Dust and ammonia in horse stalls with different ventilation rates and bedding

Airborne particles and ammonia were monitored in horse stalls managed under four conditions. Two ventilation rates, high (27 air changes per h) and low (5 air changes per h) and two bedding types, paper and straw, were employed. At both ventilation rates, the number of airborne particles generated while the stalls were mucked out was higher with straw than with paper. Particles were more efficiently cleared at the higher ventilation rate in both the straw and paper stalls. Ammonia measurements reflected an accumulation over time. In the stalls with low ventilation, ammonia levels were significantly higher than in those stalls with high ventilation regardless of bedding type. Management decisions and their relationships to respiratory disorders are discussed.     

Force Generation via β-Cardiac Myosin,Titin, and α-Actinin Drives Cardiac Sarcomere Assembly from Cell-Matrix Adhesions

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Mn2+ reduces Yz + in manganese-depleted Photosystem II preparations

Manganese in the oxygen-evolving complex is a physiological electron donor to Photosystem II. PS II depleted of manganese may oxidize exogenous reductants including benzidine and Mn²⁺. Using flash photolysis with electron spin resonance detection, we examined the room-temperature reaction kinetics of these reductants with Y_z ⁺, the tyrosine radical formed in PS II membranes under illumination. Kinetics were measured with membranes that did or did not contain the 33 kDa extrinsic polypeptide of PS II, whose presence had no effect on the reaction kinetics with either reductant. The rate of Y_z ⁺ reduction by benzidine was a linear function of benzidine concentration. The rate of Y_z ⁺ reduction by Mn²⁺ at pH 6 increased linearly at low Mn²⁺ concentrations and reached a maximum at the Mn²⁺ concentrations equal to several times the reaction center concentration. The rate was inhibited by K⁺, Ca²⁺ and Mg²⁺. These data are described by a model in which negative charge on the membrane causes a local increase in the cation concentration. The rate of Y_z ⁺ reduction at pH 7.5 was biphasic with a fast 400 s phase that suggests binding of Mn²⁺ near Y_z ⁺ at a site that may be one of the native manganese binding sites.Abbreviations PS II Photosystem II - Y_D tyrosine residue in Photosystem II that gives rise to the stable Signal II EPR spectrum - Y_z tyrosine residue in Photosystem II that mediates electron transfer between the reaction center chlorophyll and the site of water oxidation - ESR electron spin resonance - DPC diphenylcarbazide - DCIP dichlorophenolindophenol     

Temporal mechanisms influencing gender expression and pollen flow within a self-incompatible perennial,Amianthium muscaetoxicum (Liliaceae)

Summary Temporal mechanisms that influence the synchrony of gender expression and the patterns of withinplant pollen flow were examined in Amianthium muscatoxicum. In this species self-incompatible pollinations can clog stigmas, interfere with the growth of outcrossed pollen tubes, and reduce fecundity. The majority of flowers have partial dichogamy: a two-day period of pollen dehiscence and a four-day period of pollen viability are nested in a six-day period of pistil viability. An indeterminate flowering sequence among flowers on the same plant and partial dichogamy within flowers help reduce pollen flow within the whole plant. The combined effects at both of these levels should reduce pollen wastage and lower the incidence of stigma clogging by incompatible self pollen.     

Parasites, sex, and clonal diversity in natural snail populations

Under the Red Queen hypothesis, host-parasite coevolution selects against common host genotypes. Although this mechanism might underlie the persistence of sexual reproduction, it might also maintain high clonal diversity. Alternatively, clonal diversity might be maintained by multiple origins of parthenogens from conspecific sexuals, a feature in many animal groups. Herein, we addressed the maintenance of overall genetic diversity by coevolving parasites, as predicted by the Red Queen hypothesis. We specifically examined the contribution of parasites to host clonal diversity and the frequency of sexually reproducing individuals in natural stream populations of Potamopyrgus antipodarum snails. We also tested the alternative hypothesis that clonal diversity is maintained by the input of clones by mutation from sympatric sexuals. Clonal diversity and the frequency of sexual individuals were both positively related to infection frequency. Surprisingly, although clones are derived by mutation from sexual snails, parasites explained more of the genotypic variation among parthenogenetic subpopulations. Our findings thus highlight the importance of parasites as drivers of clonal diversity, as well as sex.     

The primary role of the P1 residue (ser359) of alpha-1-proteinase inhibitor

The replacement of ser359 with ala359 at the P1 position in human alpha-1-proteinase inhibitor results in the production of a variant protein containing 15% of the inhibitory activity of the normal inhibitor. Separation of active from inactive inhibitor on anhydrochymotrypsin-sepharose yields a form which has a second order association rate with neutrophil elastase which is approximately one half that for the native protein. These data indicate that the P1 residue is not of primary importance during the interaction of proteinases with alpha-1-proteinase inhibitor. Since substitution of alanine for serine causes the formation, primarily, of inactive inhibitor the major function of ser359 probably involves proper folding to give a functionally active inhibitory conformation.     

Nucleotide sequence of mouse 5-aminolevulinic acid synthase cDNA and expression of its gene in hepatic and erythroid tissues

The cDNA coding for 5-aminolevulinic acid (ALA) synthase (EC 2.3.1.37) in both liver and anemic spleen of the mouse has been cloned. The liver clone was selected by complementation of an Escherichia coli hemA mutant. Erythroid clones were obtained by screening a cDNA library made from mouse anemic spleen RNA, using the liver cDNA as a probe. The sequences of the spleen-derived and liver-derived cDNAs are identical. The nucleotide sequence and predicted amino acid (aa) sequence of a 1.85-kb spleen-derived cDNA is presented. The mouse ALA synthase as sequence displays extensive homology to ALA synthase of chick embryonic liver. The ALA synthase mRNA, detected by Northern blot analysis, was the same size, approx. 2.3 kb, in mouse liver, anemic spleen, and mouse erythroleukemia cells. It is therefore unlikely that different isozymic forms of ALA synthase are present in mouse erythroid and hepatic tissue and this is not the basis for the different effects of heme and porphyrinogenic compounds on the expression of liver and erythroid ALA synthase.     

Tricyclic aminopyrimidine histamine H4 receptor antagonists

This report discloses the development of a series of tricyclic histamine H(4) receptor antagonists. Starting with a low nanomolar benzofuranopyrimidine HTS hit devoid of pharmaceutically acceptable properties, we navigated issues with metabolism and solubility to furnish a potent, stable and water soluble tricyclic histamine H(4) receptor antagonist with desirable physiochemical parameters which demonstrated efficacy a mouse ova model.     

Microbial fuel cells meet with external resistance

The influence of external load on the composition of the anodic biofilm microbial community and biomass yield was investigated in a microbial fuel cell fed with glucose and domestic wastewater was used as source of electrogens. Denaturing gradient gel electrophoresis (DGGE) of polymerase chain reaction (PCR) amplified 16S rRNA gene fragments revealed distinct differences in anodic bacterial communities formed at the anode of each MFC operated under a different external load. These results implied that in an MFC, electrogenic bacteria were enriched under higher current densities, i.e., low external load, and were able to sustain better current and effluent quality. The influence of the external resistance applied to the MFCs during formation of the bacterial communities from sewage wastewater was shown to have no significant effect on power performance of the MFCs nor to have a significant influence on their anodic activity with both glucose and brewery wastewater as fuel. As expected, current generation, COD removal and the biomass yield were all directly influenced by the external load. Significantly, when operated under lower external load, the biomass yield in the MFC was less than that in conventional anaerobic digestion (i.e., control).