Sex differences and the development of the rabbit brain: effects of vinclozolin

The preoptic/anterior hypothalamic area (POA/AH) is one of the most sexually dimorphic areas of the vertebrate brain and plays a pivotal role in regulating male sexual behavior. Vinclozolin is a fungicide thought to be an environmental antiandrogen, which disrupts masculine sexual behavior when administered to rabbits during development. In this study, we examined several characteristics of the rabbit POA/AH for sexual dimorphism and endocrine disruption by vinclozolin. Pregnant rabbits were dosed orally with vinclozolin (10 mg/kg body weight) or carrot paste vehicle once daily for 6 wk beginning at midgestation and continuing through nursing until Postpartum Week 4. At 6 wk, offspring were perfused with 4% paraformaldehyde and brains processed for immunocytochemical localization of tyrosine hydroxylase, calbindin, gonadotropin-releasing hormone (GnRH), or Nissl stain. There were significant sex differences in the distribution of calbindin in the POA/AH and the size of cells in the dorsal POA/AH (values greater in females than in males), but not in the number or distribution of tyrosine hydroxylase or GnRH neurons. In both sexes, exposure to vinclozolin significantly increased calbindin expression in the ventral POA/AH and significantly decreased number of GnRH neurons selectively in the region of the organum vasculosum of the lamina terminalis (OVLT) but not more caudally in the POA/AH. This is the first documentation of a sexually dimorphic region in the rabbit brain, and further supports the use of this species as a model for studying the influence of vinclozolin on reproductive development with potential application to human systems.     

Tono Reservoir fishery contribution to poverty reduction among fishers in northern Ghana

Fishery characteristics and livelihood status of fishers at Tono Reservoir, Ghana, were investigated between January 2015 and June 2016. Data on fisher demography, fishing gears, fishing methods, perceptions of the state of fish stocks, management practices, income and consumption of fishers were obtained through structured interviews. Censuses of fishers and fishing gears were conducted through direct observation and counts. The population of fishers was 950 and the majority (74%) of the sampled respondents fell within the ages of 24–41 years. Gillnet, cast net, trap and hook and line were the four main gears utilised. Illegal methods of fishing observed included the use of mosquito nets (nets with mesh <1.0 cm) and the use of brewer’s waste (pito mash) as bait. Brycinus nurse, Synodontis spp., Parailia spiniserrata and Chrysichthys spp. were perceived to have disappeared from the reservoir. The fishers were unaware of the existence of any fisheries regulations, hence there was no adherence to management practices. Their daily income was derived mainly from fishing. The incidence of poverty among fishers was low (8%). The Tono Reservoir has a great potential for supporting livelihood if it is properly managed.     

Molecular modeling and analysis of human and plant endo-β-N-acetyl- glucosaminidases for mutations effects on function

Endo- β-N-acetylgucosaminidases (ENGases) are the enzymes that catalyze both hydrolysis and transglycosylation reactions. It is of interest to study ENGases because of their ability to synthesize glycopeptides. Homology models of Human, Arabidopsis thaliana and Sorghum ENGases were developed and their active sites marked based on information available from Arthrobacter protophormiae (PDB ID: 3FHQ) ENGase. Further, these models were docked with the natural substrate GlcNAc-Asn and the inhibitor Man₃GlcNAc-thiazoline. The catalytic triad of Asn, Glu and Tyr (N171, E173 and Y205 of bacteria) were found to be conserved across the phyla. The crucial Y299F mutation showing 3 times higher transglycosylation activity than in wild type Endo-A is known. The hydrolytic activity remained unchanged in bacteria, while the transglycosylation activity increased. This Y to F change is found to be naturally evolved and should be attributing higher transglycosylation rates in human and Arabidopsis thaliana ENGases. Ligand interactions Ligplots revealed the interaction of amino acids with hydrophobic side chains and polar uncharged side chain amino acids. Thus, structure based molecular model-ligand interactions provide insights into the catalytic mechanism of ENGases and assist in the rational engineering of ENGases.     

The Maloti minnow Pseudobarbus quathlambae (Barnard, 1938) is not extinct in South Africa

Despite concerted surveys, the Maloti minnow Pseudobarbus quathlambae (Barnard 1938) had not been recorded in South African waters for almost eighty years since the original collections were made at the type locality in the upper uMkhomazana River in 1938. The species was therefore declared extinct in South Africa, whereas extant populations were considered confined to various rivers in the Lesotho highlands. In April 2017, however, this species was rediscovered in the Mzimkhulu River system in KwaZulu-Natal. The rediscovery of a species that was considered locally extinct supports the need for extensive surveys to determine its distribution range, estimate population sizes, assess conservation status and implement effective strategies to ensure its continued existence in KwaZulu-Natal.