Nicotinic acid and DP1 blockade: studies in mouse models of atherosclerosis

The use of nicotinic acid to treat dyslipidemia is limited by induction of a “flushing” response, mediated in part by the interaction of prostaglandin D₂ (PGD₂) with its G-protein coupled receptor, DP1 (Ptgdr). The impact of DP1 blockade (genetic or pharmacologic) was assessed in experimental murine models of atherosclerosis. In Ptgdr^−/−ApoE^−/− mice versus ApoE^−/− mice, both fed a high-fat diet, aortic cholesterol content was modestly higher (1.3- to 1.5-fold, P < 0.05) in Ptgdr^−/−ApoE^−/− mice at 16 and 24 weeks of age, but not at 32 weeks. In multiple ApoE^−/− mouse studies, a DP1-specific antagonist, L-655, generally had a neutral to beneficial effect on aortic lipids in the presence or absence of nicotinic acid treatment. In a separate study, a modest increase in some atherosclerotic measures was observed with L-655 treatment in Ldlr^−/− mice fed a high-fat diet for 8 weeks; however, this effect was not sustained for 16 or 24 weeks. In the same study, treatment with nicotinic acid alone generally decreased plasma and/or aortic lipids, and addition of L-655 did not negate those beneficial effects. These studies demonstrate that inhibition of DP1, with or without nicotinic acid treatment, does not lead to consistent or sustained effects on plaque burden in mouse atherosclerotic models.     

Cytomegalovirus Vaccine Strain Towne-Derived Dense Bodies Induce Broad Cellular Immune Responses and Neutralizing Antibodies That Prevent Infection of Fibroblasts and Epithelial Cells

Human cytomegalovirus (HCMV), a betaherpesvirus, can cause severe disease in immunosuppressed patients and following congenital infection. A vaccine that induces both humoral and cellular immunity may be required to prevent congenital infection. Dense bodies (DBs) are complex, noninfectious particles produced by HCMV-infected cells and may represent a vaccine option. As knowledge of the antigenicity and immunogenicity of DB is incomplete, we explored characterization methods and defined DB production methods, followed by systematic evaluation of neutralization and cell-mediated immune responses to the DB material in BALB/c mice. DBs purified from Towne-infected cultures treated with the viral terminase inhibitor 2-bromo-5,6-dichloro-1-beta-d-ribofuranosyl benzimidazole riboside (BDCRB) were characterized by nanoparticle tracking analysis (NTA), two-dimensional fluorescence difference gel electrophoresis (2D-DIGE), immunoblotting, quantitative enzyme-linked immunosorbent assay, and other methods. The humoral and cellular immune responses to DBs were compared to the immunogenicity of glycoprotein B (gB) administered with the adjuvant AddaVax (gB/AddaVax). DBs induced neutralizing antibodies that prevented viral infection of cultured fibroblasts and epithelial cells and robust cell-mediated immune responses to multiple viral proteins, including pp65, gB, and UL48. In contrast, gB/AddaVax failed to induce neutralizing antibodies that prevented infection of epithelial cells, highlighting a critical difference in the humoral responses induced by these vaccine candidates. Our data advance the potential for the DB vaccine approach, demonstrate important immunogenicity properties, and strongly support the further evaluation of DBs as a CMV vaccine candidate.     

Cytogenetic Studies on Workers of the Neotropical Ant Wasmannia auropunctata (Roger 1863) (Hymenoptera: Formicidae: Myrmicinae)

Wasmannia auropunctata is known as one of the worst invasive ants in the World. A cytogenetic study was conducted on two native populations from southeastern Bahia, Brazil. The analysis of the chromosomes observed in mitotic metaphases was made by a combination of methods: Giemsa conventional staining, chromomycin A3 (CMA3) and 4-6-diamidino-2-phenylindole (DAPI) fluorochrome staining, and acridine orange banding. The workers have all the karyotype 2n=32, with ten pairs of metacentric and six pairs of acrocentric chromosomes. One chromosome arm of the pair ten was positive for CMA3 and acridine orange, suggesting the occurrence of a nucleolar organizing region. This region is an interesting marker because is very conservative and seems to constitute an interesting specific taxonomic character. The pericentromeric region of many chromosomes was stained with DAPI, evidencing the occurrence of AT bases rich heterochromatin.     

Rapid Divergent Evolution of Male Genitalia Among Populations of Drosophila buzzatii

Increasing evidence from multiple animal systems suggests that genital evolution and diversification are driven by rapid and strong evolutionary forces. Particularly, the morphology of male genital structures is considered to be among the fastest evolving traits in animal groups with internal fertilization. In this study, we investigated patterns of male genital variation within and between natural populations of the cactophilic fly Drosophila buzzatii in its original geographic distribution range in the Neotropics. We detected significant morphological differences among populations and distinguished five differentiated groups. Moreover, among population differentiation in genital morphology was associated with the degree of geographic isolation among populations and clearly contrasted with the general homogeneity detected for the putatively neutral mitochondrial gene COI. Integrating our present data with previous molecular population genetic surveys, our results suggest that male genital morphology has rapidly diverged after the recent demographic expansion that D. buzzatii has undergone in the arid zones of South America. Because the “lock and key” hypothesis failed to explain the present pattern, we explored alternative explanations for the observed pattern of genital diversification including drift-facilitated sexual selection.     

Latitudinal Variation in Starvation Resistance is Explained by Lipid Content in Natural Populations of Drosophila melanogaster

One of the most common environmental stressors is a shortage or suboptimal quality of food, thus all animals deal with periods of starvation. In the present study we examine variation in starvation resistance, longevity and body lipid content and the correlations between traits along an environmental gradient using isofemale lines recently derived from natural populations of Drosophila melanogaster from South America. The use of isofemale lines and controlled rearing laboratory conditions allows us to investigate within and among population components of genetic variation and the potential associations among starvation resistance, longevity and body lipid content. All these traits were analyzed separately in females and males, improving our understanding of sexual dimorphism. Our results revealed significant differences among populations in starvation resistance and longevity. Actually, the opposing latitudinal cline detected for starvation resistance suggests that natural selection played an essential role in shaping the pattern of geographic variation in this trait. Moreover, we also detected a positive relationship between starvation resistance and body lipid content in both sexes, providing evidence for a physiological and/or evolutionary association between these traits. Conversely, starvation resistance was not correlated with longevity indicating that these traits might be enabled to evolve independently. Finally, our study reveals that there is abundant within population genetic variation for all traits that may be maintained by sex-specific effects.     

Different nest predator guild associated with egg size in the Patagonian temperate forest

Capsule: Studies of nest predation using artificial nests need to consider the effect of egg size on the types of predator that are detected.

Aims: To estimate the nest predation rate in the Patagonian temperate forest and evaluate the influence of egg size on predator guild.

Methods: On different plant species, we placed 108 nests each containing eggs of either Atlantic Canary Serinus canaria or Common Quail Coturnix coturnix, and a model clay egg of equal size to the real egg. Nest predators were identified from the marks left on the clay eggs or by videos recorded using camera traps.

Results: 86% of the nests were predated. Birds, mainly Chimango Caracara Milvago chimango, were the main nest predators. A marsupial, the Monito del Monte Dromiciops gliroides, and rodents also contributed to nest predation. Nest predation rates were similar for both egg sizes but the nest predator guild was different. Birds and rodents preyed on both eggs but the Monito del Monte consumed mainly small eggs.

Conclusion: Egg size did not influence the rate of nest predation but, instead, affected the nest predator guild. Consequently, in order to avoid underestimating the impacts of small predators, egg size should be considered in studies of nest predation.     

Soybean lecithin-based extender as an alternative for goat sperm cryopreservation

The aim of this study was to evaluate the effect of different concentrations of soybean lecithin (SL) in extenders for sperm goat cryopreservation. Sexually mature male Saanen goats (n = 4) were used, and the ejaculates were obtained using an artificial vagina method. The semen samples were pooled and diluted in a skim milk-based extender (control group; CG) or Tris extender supplemented with SL at different concentrations (G1 = 0.04%, SL G2 = 0.08% SL and G3 = 0.16%) for a final concentration of 240 × 10⁶ spermatozoa/mL. The semen samples were packed in straws (0.25 mL), frozen using an automated system and stored in liquid nitrogen (?196 °C). After thawing (37 °C/30 s), the samples were evaluated for sperm quality parameters, including sperm motility, membrane integrity, acrosome integrity and mitochondrial activity. No significant difference was observed among the experimental and control groups for all of the parameters (P > 0.05). However, even though the control group presented a significantly lower mitochondrial membrane potential compared to fresh semen (P < 0.05), the same did not occur for the extender supplemented with soybean lecithin, that is, it did not differ from fresh sperm (P > 0.05). The extender containing soybean lecithin at different concentrations preserved the sperm quality parameters in a manner similar to the conventional skim milk-based extender. Thus, it is concluded that an extender containing soybean lecithin as the lipoprotein source can be used for freezing goat semen.     

Population genetics structure of glyphosate‐resistant Johnsongrass (Sorghum halepense L. Pers) does not support a single origin of the resistance

Single sequence repeats (SSR) developed for Sorghum bicolor were used to characterize the genetic distance of 46 different Sorghum halepense (Johnsongrass) accessions from Argentina some of which have evolved toward glyphosate resistance. Since Johnsongrass is an allotetraploid and only one subgenome is homologous to cultivated sorghum, some SSR loci amplified up to two alleles while others (presumably more conserved loci) amplified up to four alleles. Twelve SSR providing information of 24 loci representative of Johnsongrass genome were selected for genetic distance characterization. All of them were highly polymorphic, which was evidenced by the number of different alleles found in the samples studied, in some of them up to 20. UPGMA and Mantel analysis showed that Johnsongrass glyphosate‐resistant accessions that belong to different geographic regions do not share similar genetic backgrounds. In contrast, they show closer similarity to their neighboring susceptible counterparts. Discriminant Analysis of Principal Components using the clusters identified by K‐means support the lack of a clear pattern of association among samples and resistance status or province of origin. Consequently, these results do not support a single genetic origin of glyphosate resistance. Nucleotide sequencing of the 5‐enolpyruvylshikimate‐3‐phosphate synthase (EPSPS) encoding gene from glyphosate‐resistant and susceptible accessions collected from different geographic origins showed that none presented expected mutations in aminoacid positions 101 and 106 which are diagnostic of target‐site resistance mechanism.     

Extinction of Hepatitis C Virus by Ribavirin in Hepatoma Cells Involves Lethal Mutagenesis

Lethal mutagenesis, or virus extinction produced by enhanced mutation rates, is under investigation as an antiviral strategy that aims at counteracting the adaptive capacity of viral quasispecies, and avoiding selection of antiviral-escape mutants. To explore lethal mutagenesis of hepatitis C virus (HCV), it is important to establish whether ribavirin, the purine nucleoside analogue used in anti-HCV therapy, acts as a mutagenic agent during virus replication in cell culture. Here we report the effect of ribavirin during serial passages of HCV in human hepatoma Huh-7.5 cells, regarding viral progeny production and complexity of mutant spectra. Ribavirin produced an increase of mutant spectrum complexity and of the transition types associated with ribavirin mutagenesis, resulting in HCV extinction. Ribavirin-mediated depletion of intracellular GTP was not the major contributory factor to mutagenesis since mycophenolic acid evoked a similar decrease in GTP without an increase in mutant spectrum complexity. The intracellular concentration of the other nucleoside-triphosphates was elevated as a result of ribavirin treatment. Mycophenolic acid extinguished HCV without an intervening mutagenic activity. Ribavirin-mediated, but not mycophenolic acid-mediated, extinction of HCV occurred via a decrease of specific infectivity, a feature typical of lethal mutagenesis. We discuss some possibilities to explain disparate results on ribavirin mutagenesis of HCV.