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.     

Environmental,geographical and time-related impacts on avian malaria infections in native and introduced populations of house sparrows (Passer domesticus), a globally invasive species

Aim

The increasing spread of vector-borne diseases has resulted in severe health concerns for humans, domestic animals and wildlife, with changes in land use and the introduction of invasive species being among the main possible causes for this increase. We explored several ecological drivers potentially affecting the local prevalence and richness of avian malaria parasite lineages in native and introduced house sparrows (Passer domesticus) populations.

Location

Global.

Time period

2002–2019.

Major taxa studied

Avian Plasmodium parasites in house sparrows.

Methods

We analysed data from 2,220 samples from 69 localities across all continents, except Antarctica. The influence of environment (urbanization index and human density), geography (altitude, latitude, hemisphere) and time (bird breeding season and years since introduction) were analysed using generalized additive mixed models (GAMMs) and random forests.

Results

Overall, 670 sparrows (30.2%) were infected with 22 Plasmodium lineages. In native populations, parasite prevalence was positively related to urbanization index, with the highest prevalence values in areas with intermediate urbanization levels. Likewise, in introduced populations, prevalence was positively associated with urbanization index; however, higher infection occurred in areas with either extreme high or low levels of urbanization. In introduced populations, the number of parasite lineages increased with altitude and with the years elapsed since the establishment of sparrows in a new locality. Here, after a decline in the number of parasite lineages in the first 30 years, an increase from 40 years onwards was detected.

Main conclusions

Urbanization was related to parasite prevalence in both native and introduced bird populations. In invaded areas, altitude and time since bird introduction were related to the number of Plasmodium lineages found to be infecting sparrows.     

Potassium channel activators based on the benzopyran substructure: synthesis and activity of the C-8 substituent

The synthesis of a series of methoxy bearing 2,2-dimethyl-2H-1-benzopyrans have been achieved for testing as potassium channel activators. The synthesis involves formation of 6-cyano-8-methoxy-2,2-dimethyl-2H-1-benzopyran from vanillin, epoxidation, then ring opening of the epoxide with nitrogen nucleophiles to produce the new benzopyrans. Biological testing showed a dramatic decrease in activity thus revealing an important site of activity in this class of compounds.     

Phenotypic instability in a tif-1 mutant of Escherichia coli

Summary A recent study showed that in E. coli T44 () carrying the tif-1 mutation, elevated temperature and adenine can interfere with the translation process. The present study shows that the expression of tif phenotypes (thermoinduction and filamentation) is suppressed by factors which affect ribosomal function. Ethanol suppresses thermoinduction and, in some spc ^r mutants, both thermoinduction and filamentation are suppressed. An unknown factor(s) in yeast extract suppresses both thermoinduction and filamentation. In thermoresistant revertant (ts⁺), the expression of the ts⁺ phenotype is suppressed by yeast extract, ethanol, guanosine+cytidine and by the addition of a spc ^r mutation. This indicates that this phenotype could be due to suppressor mutations, and the interaction between factors affecting ribosomal function and the ts⁺ phenotype suggests that the suppression of tif in the ts⁺ strains could operate on the ribosomal level. In vitro studies show that in extracts from either spc ^r or ts⁺ strains, or in the presence of ethanol, translational restriction is relieved, suggesting that the suppression of tif phenotypes could involve the translation process.     

Clonal Analysis of Cell Division in the Bacillus subtilis div IV-B1 Minicell-Producing Mutant

Spores of the Bacillus subtilis minicell-producing mutant div IV-B1 were germinated and grown to microcolonies in chambers which facilitate continuous observation of the developing clones with a phase-contrast microscope. Time lapse photographs were taken of 46 clones, covering the period from the beginning of outgrowth until at least two rounds of cell division had been completed. Cell lineages were constructed from contour length measurements of the photographs. These data include cell lengths, division site locations, and cell numbers in clones of various ages. From these data we have determined that the probability of a minicell being produced at any division by the div IV-B1 mutant is 0.31. The location of the abnormal division site which generates the first minicell produced in the outgrowing clone appears to be random with respect to the existing cell poles. In contrast, the location of the second abnormal division site, and hence the second minicell, is not random but rather occurs preferentially in proximity to the first minicell. This clustering of abnormal events suggests that division site location is related to pole age (generations), although other influences on minicell clustering cannot be ruled out at present.     

Factors controlling the loss of immunoreactive somatic histone H1 from blastomere nuclei in oocyte cytoplasm: a potential marker of nuclear reprogramming

Nuclei of differentiated cells can acquire totipotency following transfer into the cytoplasm of oocytes. While the molecular basis of this nuclear reprogramming remains unknown, the developmental potential of nuclear-transfer embryos is influenced by the cell-cycle stage of both donor and recipient. As somatic H1 becomes immunologically undetectable on bovine embryonic nuclei following transfer into ooplasm and reappears during development of the reconstructed embryo, suggesting that it may act as a marker of nuclear reprogramming, we investigated the link between cell-cycle state and depletion of immunoreactive H1 following nuclear transplantation. Blastomere nuclei at M-, G1-, or G2-phase were introduced into ooplasts at metaphase II, telophase II, or interphase, and the reconstructed embryos were processed for immunofluorescent detection of somatic histone H1. Immunoreactivity was lost more quickly from donor nuclei at metaphase than at G1 or G2. Regardless of the stage of the donor nucleus, immunoreactivity was lost most rapidly when the recipient cytoplast was at metaphase and most slowly when the recipient was at interphase. When the recipient oocyte was not enucleated, however, immunoreactive H1 remained in the donor nucleus. The phosphorylation inhibitors 6-DMAP, roscovitine, and H89 inhibited the depletion of immunoreactive H1 from G2, but not G1, donor nuclei. In addition, immunoreactive H1 was depleted from mouse blastomere nuclei following transfer into bovine oocytes. Finally, expression of the developmentally regulated gene, eIF-1A, but not of Gapdh, was extinguished in metaphase recipients but not in interphase recipients. These results indicate that evolutionarily conserved cell-cycle-regulated activities, nuclear elements, and phosphorylation-linked events participate in the depletion of immunoreactive histone H1 from blastomere nuclei transferred in oocyte cytoplasm and that this is linked to changes in gene expression in the transferred nucleus.     

Evidence for triacylglycerol synthesis in the lumen of microsomes via a lipolysis-esterification pathway involving carnitine acyltransferases

In this study a pathway for the synthesis of triacylglycerol (TAG) within the lumen of the endoplasmic reticulum has been identified, using microsomes that had been preconditioned by depleting their endogenous substrates and then fusing them with biotinylated phosphatidylserine liposomes containing CoASH and Mg(2+). Incubating these fused microsomes with tri[(3)H] oleoylglycerol and [(14)C]oleoyl-CoA yielded microsome-associated triacylglycerol, which resisted extensive washing and had a [(3)H]:[(14)C] ratio close to 2:1. The data suggest that the precursor tri[(3)H]oleoylglycerol was hydrolyzed by microsomal lipase to membrane-bound di[(3)H]oleoylglycerol and subsequently re-esterified with luminal [(14)C]oleoyl-CoA. The accumulation of TAG within the microsomes, even when overt diacylglycerol acyltransferase (DGAT I) was inactive, is consistent with the existence of a latent diacylglycerol acyltransferase (DGAT II) within the microsomal lumen. Moreover, because luminal synthesis of TAG was carnitine-dependent and markedly reduced by glybenclamide, a potent carnitine acyltransferase inhibitor, microsomal carnitine acyltransferase appears to be essential for trafficking the [(14)C]oleoyl-CoA into the microsomal lumen for subsequent incorporation into newly synthesized TAG. This study thus provides the first direct demonstration of an enzymatic process leading to the synthesis of luminal triacylglycerol, which is a major component of very low density lipoproteins.     

Cannabinoid receptor agonists are mitochondrial inhibitors: a unified hypothesis of how cannabinoids modulate mitochondrial function and induce cell death

Time-lapse microscopy of human lung cancer (H460) cells showed that the endogenous cannabinoid anandamide (AEA), the phyto-cannabinoid Δ-9-tetrahydrocannabinol (THC) and a synthetic cannabinoid HU 210 all caused morphological changes characteristic of apoptosis. Janus green assays of H460 cell viability showed that AEA and THC caused significant increases in OD 595 nm at lower concentrations (10-50 μM) and significant decreases at 100 μM, whilst HU 210 caused significant decreases at all concentrations. In rat heart mitochondria, all three ligands caused significant decreases in oxygen consumption and mitochondrial membrane potential. THC and HU 210 caused significant increases in mitochondrial hydrogen peroxide production, whereas AEA was without significant effect. All three ligands induced biphasic changes in either mitochondrial complex I activity and/or mitochondrial complex II-III activity. These data demonstrate that AEA, THC, and HU 210 are all able to cause changes in integrated mitochondrial function, directly, in the absence of cannabinoid receptors.