Implications of flower developmental stage, plant isolation and microclimatic condition on a hemiparasitic plant–avian pollinator interaction

The pollination success of bird pollinated plants is determined by avian visits and duration of foraging which in turn have been shown to be regulated by several plant features. However, very few of these factors have been demonstrated on hemiparasitic plants under tropical African climate. This study, determined how three flower developmental stages (ripe, unripe and open flowers), plant isolation and microclimatic conditions (temperature and wind speed) influenced frequency of visits and duration of foraging by avian pollinators on the Loranthaceae mistletoe T. sessilifolius in a tropical savanna habitat in Nigeria, West Africa. One hour focal observations across 40 individuals of the study plant species was used to collect information on avian visits and duration of foraging. While numbers of flowers for the three flower developmental stages were obtained through direct counts. Results showed that increased number of closed ripe flowers on the study plant significantly attracted avian pollinators. This relationship between avian visitors and ripe flowers may be connected with the high nectar content of such flowers as reported in previous studies. Increased intensity of microclimatic factors; temperature (°C) and wind speed (m/s) however, negatively affected avian pollinators. This could be linked to their established effects of increasing avian thermoregulatory costs and mechanical inhibition of flight. These observations could potentially limit pollen deposition at stigma with consequences on plant fitness as shown in previous studies. The observations also give a picture of the potential effects of increasing temperatures in the face of global warming. Keywords: flower, avian, plant-isolation, microclimate, hemiparasitic-plant, interactio

Large Mammals and Wetland utilization: a case study in Yankari Game Reserve Nigeria

The African plain harbours high abundance and diversity of mammals, most of which are confined to protected areas (PAs) due to anthro‐ pogenic threats (Craigie et al., 2010; Dirzo et al., 2014; Estes, 1999; Kingdon, 1997). Also, PAs face problems of hunting, logging and live‐ stock grazing, conflict of interest and poor management (Caro, 2001; Dharmaratne, Sang, &Walling, 2000; Gardner et al., 2009; Geldmann et al., 2015; Geldmann et al., 2015; Hall, Harris, Medjibe, & Ashton, 2003; Pressey, 1994; Salum, Eustace, Malata, & Mbangwa, 2017; Thuiller, 2007), consequently disrupting conservation goals, effective monitor‐ ing and understanding of habitat utilisation dynamics of mammals. Although wetlands are important habitats for sustaining animal populations, there is a widespread trend of increasing degradation of these habitats (Fynn, Chase, & Rӧder, 2014) and dearth of infor‐ mation pertaining to wetland utilisation in most PAs. While this is integral for effective conservation practice, few studies focus on this area in Africa (Arzamendia, Cassini, & Vila, 2006; Kumar, Mudappa, & Raman, 2010; Rahman et al., 2017). Here, we investigated the wet‐ land utilisation dynamics of large mammals in Yankari Game Reserve (YGR). The objective was to determine abundance, density and di‐ versity of large mammals and whether these variables were associ‐ ated with wetland size and time of da

Redox modifications of cysteine residues regulate the cytokine activity of HMGB1.

BACKGROUND: High mobility group box 1 (HMGB1) is a nuclear protein with extracellular inflammatory cytokine activity. It is passively released during cell death and secreted by activated cells of many lineages. HMGB1 contains three conserved redox-sensitive cysteine residues: cysteines in position 23 and 45 (C23 and C45) can form an intramolecular disulfide bond, whereas C106 is unpaired and is essential for the interaction with Toll-Like Receptor (TLR) 4. However, a comprehensive characterization of the dynamic redox states of each cysteine residue and of their impacts on innate immune responses is lacking. METHODS: Primary human macrophages or murine macrophage-like RAW 264.7 cells were activated in cell cultures by redox-modified or point-mutated (C45A) recombinant HMGB1 preparations or by lipopolysaccharide (E. coli.0111: B4). Cellular phosphorylated NF-κB p65 subunit and subsequent TNF-α release were quantified by commercial enzyme-linked immunosorbent assays. RESULTS: Cell cultures with primary human macrophages and RAW 264.7 cells demonstrated that fully reduced HMGB1 with all three cysteines expressing thiol side chains failed to generate phosphorylated NF-КB p65 subunit or TNF-α. Mild oxidation forming a C23-C45 disulfide bond, while leaving C106 with a thiol group, was required for HMGB1 to induce phosphorylated NF-КB p65 subunit and TNF-α production. The importance of a C23-C45 disulfide bond was confirmed by mutation of C45 to C45A HMGB1, which abolished the ability for cytokine induction. Further oxidation of the disulfide isoform also inactivated HMGB1. CONCLUSIONS: These results reveal critical post-translational redox mechanisms that control the proinflammatory activity of HMGB1 and its inactivation during inflammation

Evidence of Infection by H5N2 Highly Pathogenic Avian Influenza Viruses in Healthy Wild Waterfowl

The potential existence of a wild bird reservoir for highly pathogenic avian influenza (HPAI) has been recently questioned by the spread and the persisting circulation of H5N1 HPAI viruses, responsible for concurrent outbreaks in migratory and domestic birds over Asia, Europe, and Africa. During a large-scale surveillance programme over Eastern Europe, the Middle East, and Africa, we detected avian influenza viruses of H5N2 subtype with a highly pathogenic (HP) viral genotype in healthy birds of two wild waterfowl species sampled in Nigeria. We monitored the survival and regional movements of one of the infected birds through satellite telemetry, providing a rare evidence of a non-lethal natural infection by an HP viral genotype in wild birds. Phylogenetic analysis of the H5N2 viruses revealed close genetic relationships with H5 viruses of low pathogenicity circulating in Eurasian wild and domestic ducks. In addition, genetic analysis did not reveal known gallinaceous poultry adaptive mutations, suggesting that the emergence of HP strains could have taken place in either wild or domestic ducks or in non-gallinaceous species. The presence of coexisting but genetically distinguishable avian influenza viruses with an HP viral genotype in two cohabiting species of wild waterfowl, with evidence of non-lethal infection at least in one species and without evidence of prior extensive circulation of the virus in domestic poultry, suggest that some strains with a potential high pathogenicity for poultry could be maintained in a community of wild waterfowl