Free gossypol supplementation frequency and reproductive toxicity in young bulls

The aim of the present study was to analyze seminal quality of young bulls subjected to different frequencies of gossypol supplementation. Forty-eight Nellore bulls, with 19 months of age and weighing 357.8 ± 7.2 kg, were used in this study. Animals were fed with 10.5 kg of standard supplement containing free-gossypol from whole cottonseed (WCS) at the following frequency: 3x/week (G3x), 5x/week (G5x) or 7x/week (G7x - Control). Additionally, a negative control was provided, and the treated animals received only mineral supplement (MM) ad libtum. The experiment lasted for 84 days and semen was collected at the beginning and at the end for analysis and cryopreservation. Fresh semen was used for initial analysis and plasma membrane integrity and sperm morphology were also determined. General motility using computer assisted sperm analysis (CASA), plasma and acrosomal membranes integrity, mitochondrial activity, and induced oxidative stress were assessed in post-thawed semen. The study design was completely randomized. Parametric data were analyzed by ANOVA and non-parametric data by the Wilcoxon test, using the statistical program SAS. Level of significance was set at 5%. Supplementation with WCS, regardless the frequency, increased total (P = .009) and head (P = .005) defects in comparison to animals receiving only forage and mineral supplement. Infrequent supplementation, particularly 5 times in the week (G5X), increased head (P = .026) and midpiece (P = .014) abnormalities. Sperm motility in fresh semen was lower in animals that received daily supplementation than those supplemented on alternate days (P = .021). Additionally, animals supplemented daily showed lower percentage of spermatozoa with intact acrosome compared to those supplemented on alternate days (P = .005). Thus, regardless the frequency of supplementation, free-gossypol supplementation affects sperm quality. Although the amount of free gossypol supplied weekly was the same among treatments, daily supplementation compromised sperm kinetics, differently from infrequent supplementation that led to sperm defects developed during spermatogenesis.

Antimicrobial activity of apitoxin, melittin and phospholipase A₂ of honey bee (Apis mellifera) venom against oral pathogens

In this work, we used the Minimum Inhibitory Concentration (MIC) technique to evaluate the antibacterial potential of the apitoxin produced by Apis mellifera bees against the causative agents of tooth decay. Apitoxin was assayed in natura and in the commercially available form. The antibacterial actions of the main components of this apitoxin, phospholipase A2, and melittin were also assessed, alone and in combination. The following bacteria were tested: Streptococcus salivarius, S. sobrinus, S. mutans, S. mitis, S. sanguinis, Lactobacillus casei, and Enterococcus faecalis. The MIC results obtained for the commercially available apitoxin and for the apitoxin in natura were close and lay between 20 and 40 µg / mL, which indicated good antibacterial activity. Melittin was the most active component in apitoxin; it displayed very promising MIC values, from 4 to 40 µg / mL. Phospholipase A2 presented MIC values higher than 400 µg / mL. Association of mellitin with phospholipase A2 yielded MIC values ranging between 6 and 80 µg / mL. Considering that tooth decay affects people's health, apitoxin and its component melittin have potential application against oral pathogens.

Neuroprotection by BDNF against glutamate-induced apoptotic cell death is mediated by ERK and PI3-kinase pathways

Neurotrophins protect neurons against glutamate excitotoxicity, but the signaling mechanisms have not been fully elucidated. We studied the role of the phosphatidylinositol 3-kinase (PI3-K) and Ras/mitogen-activated protein kinase (MAPK) pathways in the protection of cultured hippocampal neurons from glutamate induced apoptotic cell death, characterized by nuclear condensation and activation of caspase-3-like enzymes. Pre-incubation with the neurotrophin brain-derived neurotrophic factor (BDNF), for 24 h, reduced glutamate-evoked apoptotic morphology and caspase-3-like activity, and transiently increased the activity of the PI3-K and of the Ras/MAPK pathways. Inhibition of the PI3-K and of the Ras/MAPK signaling pathways abrogated the protective effect of BDNF against glutamate-induced neuronal death and similar effects were observed upon inhibition of protein synthesis. Moreover, incubation of hippocampal neurons with BDNF, for 24 h, increased Bcl-2 protein levels. The results indicate that the protective effect of BDNF in hippocampal neurons against glutamate toxicity is mediated by the PI3-K and the Ras/MAPK signaling pathways, and involves a long-term change in protein synthesis.

Drug resistance in Chromobacterium violaceum

Chromobacterium violaceum is a free-living bacterium commonly found in aquatic habitats of tropical and subtropical regions of the world. This bacterium is able to produce a large variety of products of biotechnological and pharmacological use. Although C. violaceum is considered to be non-pathogenic, some cases of severe infections in humans and other animals have been reported. Genomic data on the type strain ATCC 12472(T) has provided a comprehensive basis for detailed studies of pathogenicity, virulence and drug resistance genes. A large number of open reading frames associated with various mechanisms of drug resistance were found, comprising a remarkable feature of this organism. Amongst these, beta-lactam (penicillin and cephalosporin) and multidrug resistance genes (drug efflux pumps) were the most numerous. In addition, genes associated with bacitracin, bicyclomycin, chloramphenicol, kasugamycin, and methylenomycin were also found. It is postulated that these genes contribute to the ability of C. violaceum to compete with other bacteria in the environment, and also may help to explain the common drug resistance phenotypes observed in infections caused by this bacterium.

Bacteriophages and insertion sequences of Chromobacterium violaceum ATCC 12472

A fluid genome is a great advantage to prokaryotes, enabling quick adaptation to various types of ecological niches and to diverse environmental selective pressures. A substantial portion of these sudden changes is mediated by lateral gene transfer (LGT), through genetic recombination mechanisms, such as transformation, conjugation and transduction. The recent sequencing of several organisms has offered a new approach to the study of LGT, using comparison and analysis of nucleotide sequences dispersed throughout the genome of these species. This analysis in Choromobacterium violaceum has revealed four prophage and 12 insertion sequences, suggesting genetic exchange with several other bacterial species, including Salmonella enterica, Ralstonia and Xanthomonas. An Rhs (recombination hot spot) element (containing a vgr-like gene) was also observed, the function of which remains unknown, but it has a sequence related to species of Acinetobacter and Sphingomonas. These results support the role of LGT in the acquisition of new traits by C. violaceum.