Population genetic studies of the tsetse fly, Glossina pallidipes (Diptera: Glossinidae)

Tsetse flies transmit trypanosome species that cause sleeping sickness in humans and nagana in livestock. In the absence of a vaccine against trypanosome parasites and given the high cost of treatment, vector control remains the most effective method for reducing the incidence of trypanosomiasis. In anticipation of area-wide control of G. pallidipes by using genetic methods, a thorough understanding of its breeding structure is required.;Capture release-recapture data show that G. pallidipes has a high capacity for dispersal, but genetic data indicate surprisingly high differentiation among populations. Studying local patterns of genetic variation and examining how such variation changes temporally can provide insight into the apparent contradiction between ecological and genetic data. The overall objective of my research was to determine microgeographic (200 m--≤10 km) genetic structure of G. pallidipes and compare with population structure at the macrogeographic (tens to hundreds of kilometers) scale. In addition, I wanted to assess temporal changes in gene diversity and differentiation.;Microsatellite DNA loci were characterized and used to study genetic variation within and among natural G. pallidipes populations. The loci were highly polymorphic (mean number of alleles = 20.5 +/- 10.1) and unlinked hence useful for population studies. Mating was random within but not among populations at the macrogeographic scale (F ST = 0.18). Differentiation among microgeographic populations was minimal (FST = 0.017) indicating a high rate of gene flow at microgeographic scale. Allele frequencies were homogeneous among sampling sites. Analysis of molecular variance (AMOVA) showed that most of the variation (\u3e90%) lay within sites while only 2% of the total variance was attributed to variation among blocks.;Allele frequencies were homogenous between seasons. Genetic differentiation was higher in the dry season than in the wet season. However, differentiation between pooled wet and pooled dry season samples did not differ significantly from zero (FST = 0.008, G ST = 0.004). AMOVA showed that less than 2% of the variance could be attributed to difference between temporal samples. It is concluded that tsetse populations show little temporal variation probably due to drift. These results provide a better understanding of levels of genetic subdivision and gene flow at the local scale

The Toxoplasma gondii active serine hydrolase 4 regulates parasite division and intravacuolar parasite architecture

ABSTRACT Hydrolase are enzymes that regulate diverse biological processes, including posttranslational protein modifications. Recent work identified four active serine hydrolases (ASHs) in Toxoplasma gondii as candidate depalmitoylases. However, only TgPPT1 (ASH1) has been confirmed to remove palmitate from proteins. ASH4 (TgME49_264290) was reported to be refractory to genetic disruption. We demonstrate that recombinant ASH4 is an esterase that processes short acyl esters but not palmitoyl thioesters. Genetic disruption of ASH4 causes defects in cell division and premature scission of parasites from residual bodies. These defects lead to the presence of vacuoles with a disordered intravacuolar architecture, with parasites arranged in pairs around multiple residual bodies. Importantly, we found that the deletion of ASH4 correlates with a defect in radial dispersion from host cells after egress. This defect in dispersion of parasites is a general phenomenon that is observed for disordered vacuoles that occur at low frequency in wild-type parasites, suggesting a possible general link between intravacuolar organization and dispersion after egress. IMPORTANCE This work defines the function of an enzyme in the obligate intracellular parasite Toxoplasma gondii. We show that this previously uncharacterized enzyme is critical for aspects of cellular division by the parasite and that loss of this enzyme leads to parasites with cell division defects and which also are disorganized inside their vacuoles. This leads to defects in the ability of the parasite to disseminate from the site of an infection and may have a significant impact on the parasite's overall infectivity of a host organism

Recent Outbreaks of Rift Valley Fever in East Africa and the Middle East

Rift Valley fever (RVF) is an important neglected, emerging, mosquito-borne disease with severe negative impact on human and animal health. Mosquitoes in the Aedes genus have been considered as the reservoir, as well as vectors, since their transovarially infected eggs withstand desiccation and larvae hatch when in contact with water. However, different mosquito species serve as epizootic/epidemic vectors of RVF, creating a complex epidemiologic pattern in East Africa. The recent RVF outbreaks in Somalia (2006–2007), Kenya (2006–2007), Tanzania (2007), and Sudan (2007–2008) showed extension to districts, which were not involved before. These outbreaks also demonstrated the changing epidemiology of the disease from being originally associated with livestock, to a seemingly highly virulent form infecting humans and causing considerably high-fatality rates. The amount of rainfall is considered to be the main factor initiating RVF outbreaks. The interaction between rainfall and local environment, i.e., type of soil, livestock, and human determine the space-time clustering of RVF outbreaks. Contact with animals or their products was the most dominant risk factor to transfer the infection to humans. Uncontrolled movement of livestock during an outbreak is responsible for introducing RVF to new areas. For example, the virus that caused the Saudi Arabia outbreak in 2000 was found to be the same strain that caused the 1997–98 outbreaks in East Africa. A strategy that involves active surveillance with effective case management and diagnosis for humans and identifying target areas for animal vaccination, restriction on animal movements outside the affected areas, identifying breeding sites, and targeted intensive mosquito control programs has been shown to succeed in limiting the effect of RVF outbreak and curb the spread of the disease from the onset

Potential of anaerobic co-digestion in improving the environmental quality of agro-textile wastewater sludge

This research article published by IWA publishingSludge from textile effluent treatment plants (ETP) remains a challenge for many industries due to inefficient and limited waste management strategies. This study explores the potential of using anaerobic digestion (AD) to improve the environmental quality of textile ETP sludge. The AD of ETP sludge is affected by the low C/N ratio (3.7), heavy metal content, and toxicity. To improve the process, co-digestion of ETP sludge with different substrates (sewage sludge, cow dung, and sawdust) under mesophilic conditions (37 °C), followed by a thermochemical pretreatment was assessed. The results showed that anaerobic co-digestion of the textile sludge with the co-substrates is effective in reducing pollution load. It was found that organic matters degraded during the 30-day AD process. The chemical oxygen demand and biological oxygen demand reduction was in the range of 33.1–88.5% and 48.1–67.1%, respectively. Also, heavy metal (cadmium, lead, iron, and, mercury) concentration was slightly reduced after digestion. Maximal biogas yield was achieved from co-digestion of textile sludge and sewage sludge at a mixing ratio of 3:1, 1:1, and 1:3, and methane content was respectively 87.9%, 68.9%, and 69.5% of the gas composition. The results from this study show that co-digestion will not only reduce the environmental pollution and health risks from the textile industry but also recover useful energy

Understanding factors influencing distribution and density of a micro-Lepidoptera moth, Tuta absoluta (Gelechiidae) and its impact in tomato agroecological zones of Tanzania

This research article published by Bioscience Research, 2020Field survey was conducted from August to November 2016 and repeated from January to April 2017 to study population, distribution and damage by tomato leaf miner (TLM) (Tuta absoluta Meyrick 1977) in 156 farms in agroecological zones of Tanzania. A pheromone trap/farm was deployed in tomato or other Solanaceae’s crops for examining moth of T. absoluta stuck in each trap and to determine damage by TLM. Results indicated that TLM is present in 13 regions with the highest population in Southern zone (Iringa), Northern zone (Arusha) and East-Central (Morogoro) with catches averaging 357.8±25.5, 279.9±12.1, 298.7±11.4 and 173.1±10.1 moths/trap in dry season respectively whereas lowest count amounting 13.3±1.0moths/trap was observed in western zone (Mwanza) during rainy season. Tomato was the most damaged crop with high mines averaging 90.0 ± 0.0% damage in Iringa and the low of 30.0±5.7 % realized in Mwanza. Tuta absoluta was found attacking 10 more plant species besides tomato with damage incidence averaging 83.3 ± 3.7% in Solanum lycopersicum, 60.0±0.0% in Solanum tuberosum, 30.0±0.0% damage in weed (Solanum incanum) and the lowest damage averaging 0.0±0.0% was observed in capsicum annuum. Based on these findings, it is evident that, T. absoluta is expanding its geographical range and hosts resulting into high damage and yield loss affecting farmers’ livelihood in Tanzania. This study informs farmers on the proper use of pheromone traps for early detection, scouting, weeding, crop rotation, use of biological control agents for effective management of the pest to reduce losses and environmental impact due to extensive use of synthetic pesticides

Genetic diversity and population structure of Glossina pallidipes in Uganda and western Kenya

<p>Abstract</p> <p>Background</p> <p><it>Glossina pallidipes </it>has been implicated in the spread of sleeping sickness from southeastern Uganda into Kenya. Recent studies indicated resurgence of <it>G. pallidipes </it>in Lambwe Valley and southeastern Uganda after what were deemed to be effective control efforts. It is unknown whether the <it>G. pallidipes </it>belt in southeastern Uganda extends into western Kenya. We investigated the genetic diversity and population structure of <it>G. pallidipes </it>in Uganda and western Kenya.</p> <p>Results</p> <p>AMOVA indicated that differences among sampling sites explained a significant proportion of the genetic variation. Principal component analysis and Bayesian assignment of microsatellite genotypes identified three distinct clusters: western Uganda, southeastern Uganda/Lambwe Valley, and Nguruman in central-southern Kenya. Analyses of mtDNA confirmed the results of microsatellite analysis, except in western Uganda, where Kabunkanga and Murchison Falls populations exhibited haplotypes that differed despite homogeneous microsatellite signatures. To better understand possible causes of the contrast between mitochondrial and nuclear markers we tested for sex-biased dispersal. Mean pairwise relatedness was significantly higher in females than in males within populations, while mean genetic distance was lower and relatedness higher in males than females in between-population comparisons. Two populations sampled on the Kenya/Uganda border, exhibited the lowest levels of genetic diversity. Microsatellite alleles and mtDNA haplotypes in these two populations were a subset of those found in neighboring Lambwe Valley, suggesting that Lambwe was the source population for flies in southeastern Uganda. The relatively high genetic diversity of <it>G. pallidipes </it>in Lambwe Valley suggest large relict populations remained even after repeated control efforts.</p> <p>Conclusion</p> <p>Our research demonstrated that <it>G. pallidipes </it>populations in Kenya and Uganda do not form a contiguous tsetse belt. While Lambwe Valley appears to be a source population for flies colonizing southeastern Uganda, this dispersal does not extend to western Uganda. The complicated phylogeography of <it>G. pallidipes </it>warrants further efforts to distinguish the role of historical and modern gene flow and possible sex-biased dispersal in structuring populations.</p

Implementing evidence‐based science to improve women’s health globally

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135335/1/ijgo91.pd

High HIV Prevalence Among Men Who have Sex with Men in Soweto, South Africa: Results from the Soweto Men’s Study

The Soweto Men’s Study assessed HIV prevalence and associated risk factors among MSM in Soweto, South Africa. Using respondent driven sampling (RDS) recruitment methods, we recruited 378 MSM (including 15 seeds) over 30 weeks in 2008. All results were adjusted for RDS sampling design. Overall HIV prevalence was estimated at 13.2% (95% confidence interval 12.4–13.9%), with 33.9% among gay-identified men, 6.4% among bisexual-identified men, and 10.1% among straight-identified MSM. In multivariable analysis, HIV infection was associated with being older than 25 (adjusted odds ratio (AOR) 3.8, 95% CI 3.2–4.6), gay self-identification (AOR 2.3, 95% CI 1.8–3.0), monthly income less than ZAR500 (AOR 1.4, 95% CI 1.2–1.7), purchasing alcohol or drugs in exchange for sex with another man (AOR 3.9, 95% CI 3.2–4.7), reporting any URAI (AOR 4.4, 95% CI 3.5–5.7), reporting between six and nine partners in the prior 6 months (AOR 5.7, 95% CI 4.0–8.2), circumcision, (AOR 0.2, 95% CI 0.1–0.2), a regular female partner (AOR 0.2, 95% CI 0.2–0.3), smoking marijuana in the last 6 months (AOR 0.6, 95% CI 0.5–0.8), unprotected vaginal intercourse in the last 6 months (AOR 0.5, 95% CI 0.4–0.6), and STI symptoms in the last year (AOR 0.7, 95% CI 0.5–0.8). The results of the Soweto Men’s Study confirm that MSM are at high risk for HIV infection, with gay men at highest risk. HIV prevention and treatment for MSM are urgently needed

Tracking the Feeding Patterns of Tsetse Flies (Glossina Genus) by Analysis of Bloodmeals Using Mitochondrial Cytochromes Genes

Tsetse flies are notoriously difficult to observe in nature, particularly when populations densities are low. It is therefore difficult to observe them on their hosts in nature; hence their vertebrate species can very often only be determined indirectly by analysis of their gut contents. This knowledge is a critical component of the information on which control tactics can be developed. The objective of this study was to determine the sources of tsetse bloodmeals, hence investigate their feeding preferences. We used mitochondrial cytochrome c oxidase 1 (COI) and cytochrome b (cytb) gene sequences for identification of tsetse fly blood meals, in order to provide a foundation for rational decisions to guide control of trypanosomiasis, and their vectors. Glossina swynnertoni were sampled from Serengeti (Tanzania) and G. pallidipes from Kenya (Nguruman and Busia), and Uganda. Sequences were used to query public databases, and the percentage identities obtained used to identify hosts. An initial assay showed that the feeds were from single sources. Hosts identified from blood fed flies collected in Serengeti ecosystem, included buffaloes (25/40), giraffes (8/40), warthogs (3/40), elephants (3/40) and one spotted hyena. In Nguruman, where G. pallidipes flies were analyzed, the feeds were from elephants (6/13) and warthogs (5/13), while buffaloes and baboons accounted for one bloodmeal each. Only cattle blood was detected in flies caught in Busia and Uganda. Out of four flies tested in Mbita Point, Suba District in western Kenya, one had fed on cattle, the other three on the Nile monitor lizard. These results demonstrate that cattle will form an integral part of a control strategy for trypanosomiasis in Busia and Uganda, while different approaches are required for Serengeti and Nguruman ecosystems, where wildlife abound and are the major component of the tsetse fly food source

Phylogeography and Population Structure of Glossina fuscipes fuscipes in Uganda: Implications for Control of Tsetse

Glossina fuscipes fuscipes is the most common species of tsetse in Uganda, where it transmits human sleeping sickness and nagana, a related disease of cattle. A consortium of African countries dedicated to controlling these diseases is poised to begin area wide control of tsetse, but a critical question remains: What is the most appropriate geographical scale for these activities? To address this question, we used population genetics to determine the extent of linkage between populations of tsetse confined to discrete patches of riverine habitat. Our results suggest that Uganda was colonized by two distinct lineages of G. f. fuscipes, which now co-occur only in a narrow band across central Uganda. Evidence for interbreeding at the zone of contact and movement of genes from the south to the north suggest that this historical genetic structure may dissolve in the future. At smaller scales, we have demonstrated that exchange of genes among neighboring populations via dispersal is at equilibrium with the differentiating force of genetic drift. Our results highlight the need for investment in vector control programs that account for the linkage observed among tsetse populations. Given its genetic isolation and its location at the far edge of G. fuscipes' range, the Lake Victoria region appears to be an appropriate target for area wide control