HIV risk among MSM in Senegal: a qualitative rapid assessment of the impact of enforcing laws that criminalize same sex practices

Men who have sex with men (MSM) are at high risk for HIV in Senegal, with a prevalence of 21.5%. In December 2008, nine male HIV prevention workers were imprisoned for "acts against nature" prohibited by Senegalese law. This qualitative study assessed the impact of these arrests on HIV prevention efforts. A purposive sample of MSM in six regions of Senegal was recruited by network referral. 26 in-depth interviews (IDIs) and 6 focus group discussions (FGDs) were conducted in July-August 2009. 14 key informants were also interviewed. All participants reported pervasive fear and hiding among MSM as a result of the December 2008 arrests and publicity. Service providers suspended HIV prevention work with MSM out of fear for their own safety. Those who continued to provide services noticed a sharp decline in MSM participation. An effective response to the HIV epidemic in Senegal should include active work to decrease enforcement of this law.     

Genome-Wide Analysis of the Phosphoinositide Kinome from Two Ciliates Reveals Novel Evolutionary Links for Phosphoinositide Kinases in Eukaryotic Cells

Background

The complexity of phosphoinositide signaling in higher eukaryotes is partly due to expansion of specific families and types of phosphoinositide kinases (PIKs) that can generate all phosphoinositides via multiple routes. This is particularly evident in the PI3Ks and PIPKs, and it is considered an evolutionary trait associated with metazoan diversification. Yet, there are limited comprehensive studies on the PIK repertoire of free living unicellular organisms.

Methodology/Principal Findings

We undertook a genome-wide analysis of putative PIK genes in two free living ciliated cells, Tetrahymena and Paramecium. The Tetrahymena thermophila and Paramecium tetraurelia genomes were probed with representative kinases from all families and types. Putative homologs were verified by EST, microarray and deep RNA sequencing database searches and further characterized for domain structure, catalytic efficiency, expression patterns and phylogenetic relationships. In total, we identified and characterized 22 genes in the Tetrahymena thermophila genome and 62 highly homologues genes in Paramecium tetraurelia suggesting a tight evolutionary conservation in the ciliate lineage. Comparison to the kinome of fungi reveals a significant expansion of PIK genes in ciliates.

Conclusions/Significance

Our study highlights four important aspects concerning ciliate and other unicellular PIKs. First, ciliate-specific expansion of PI4KIII-like genes. Second, presence of class I PI3Ks which, at least in Tetrahymena, are associated with a metazoan-type machinery for PIP₃ signaling. Third, expansion of divergent PIPK enzymes such as the recently described type IV transmembrane PIPKs. Fourth, presence of possible type II PIPKs and presumably inactive PIKs (hence, pseudo-PIKs) not previously described. Taken together, our results provide a solid framework for future investigation of the roles of PIKs in ciliates and indicate that novel functions and novel regulatory pathways of phosphoinositides may be more widespread than previously thought in unicellular organisms.     

Molecular characterization of Fasciola gigantica from Mauritania based on mitochondrial and nuclear ribosomal DNA sequences

Fasciolosis caused by Fasciola hepatica and Fasciola gigantica (Platyhelminthes: Trematoda: Digenea) is considered the most important helminth infection of ruminants in tropical countries, causing considerable socioeconomic problems. From Africa, F. gigantica has been previously characterized from Burkina Faso, Senegal, Kenya, Zambia and Mali, while F. hepatica has been reported from Morocco and Tunisia, and both species have been observed from Ethiopia and Egypt on the basis of morphometric differences, while the use of molecular markers is necessary to distinguish exactly between species. Samples identified morphologically as F. gigantica (n = 60) from sheep and cattle from different geographical localities of Mauritania were genetically characterized by sequences of the first (ITS-1), the 5.8S, and second (ITS-2) Internal Transcribed Spacers (ITS) of nuclear ribosomal DNA (rDNA) genes and the mitochondrial Cytochrome c Oxidase I (COI) gene.Comparison of the sequences of the Mauritanian samples with sequences of Fasciola spp. from GenBank confirmed that all samples belong to the species F. gigantica. The nucleotide sequencing of ITS rDNA of F. gigantica showed no nucleotide variation in the ITS-1, 5.8S, and ITS-2 rDNA sequences among all samples examined and those from Burkina Faso, Kenya, Egypt and Iran. The phylogenetic trees based on the ITS-1 and ITS-2 sequences showed a close relationship of the Mauritanian samples with isolates of F. gigantica from different localities of Africa and Asia. The COI genotypes of the Mauritanian specimens of F. gigantica had a high level of diversity, and they belonged to the F. gigantica phylogenically distinguishable clade. The present study is the first molecular characterization of F. gigantica in sheep and cattle from Mauritania, allowing a reliable approach for the genetic differentiation of Fasciola spp. and providing basis for further studies on liver flukes in the African countries.     

Prominent intraspecific genetic divergence within Anopheles gambiae sibling species triggered by habitat discontinuities across a riverine landscape

The Anopheles gambiae complex of mosquitoes includes malaria vectors at different stages of speciation, whose study enables a better understanding of how adaptation to divergent environmental conditions leads to evolution of reproductive isolation. We investigated the population genetic structure of closely related sympatric taxa that have recently been proposed as separate species (An. coluzzii and An. gambiae), sampled from diverse habitats along the Gambia river in West Africa. We characterized putatively neutral microsatellite loci as well as chromosomal inversion polymorphisms known to be associated with ecological adaptation. The results revealed strong ecologically associated population subdivisions within both species. Microsatellite loci on chromosome‐3L revealed clear differentiation between coastal and inland populations, which in An. coluzzii is reinforced by a unusual inversion polymorphism pattern, supporting the hypothesis of genetic divergence driven by adaptation to the coastal habitat. A strong reduction of gene flow was observed between An. gambiae populations west and east of an extensively rice‐cultivated region apparently colonized exclusively by An. coluzzii. Notably, this ‘intraspecific’ differentiation is higher than that observed between the two species and involves also the centromeric region of chromosome‐X which has previously been considered a marker of speciation within this complex, possibly suggesting that the two populations may be at an advanced stage of differentiation triggered by human‐made habitat fragmentation. These results confirm ongoing ecological speciation within these most important Afro‐tropical malaria vectors and raise new questions on the possible effect of this process in malaria transmission.     

Spatiotemporal changes in the genetic diversity of harmful algal blooms caused by the toxic dinoflagellate Alexandrium minutum

Organisms with sexual and asexual reproductive systems benefit from both types of reproduction. Sexual recombination generates new combinations of alleles, whereas clonality favours the spread of the fittest genotype through the entire population. Therefore, the rate of sexual vs. clonal reproduction has a major influence on the demography and genetic structure of natural populations. We addressed the effect of reproductive system on populations of the dinoflagellate Alexandrium minutum. More specifically, we monitored the spatiotemporal genetic diversity during and between bloom events in two estuaries separated by 150 km for two consecutive years. An analysis of population genetic patterns using microsatellite markers revealed surprisingly high genotypic and genetic diversity. Moreover, there was significant spatial and temporal genetic differentiation during and between bloom events. Our results demonstrate that (i) interannual genetic differentiation can be very high, (ii) estuaries are partially isolated during bloom events and (iii) genetic diversity can change rapidly during a bloom event. This rapid genetic change may reflect selective effects that are nevertheless not strong enough to reduce allelic diversity. Thus, sexual reproduction and/or migration may regularly erase any genetic structure produced within estuaries during a bloom event.     

Population Genetic Structure and Isolation by Distance of Helicobacter pylori in Senegal and Madagascar

Helicobacter pylori has probably infected the human stomach since our origins and subsequently diversified in parallel with their human hosts. The genetic population history of H. pylori can therefore be used as a marker for human migration. We analysed seven housekeeping gene sequences of H. pylori strains isolated from 78 Senegalese and 24 Malagasy patients and compared them with the sequences of strains from other geographical locations. H. pylori from Senegal and Madagascar can be placed in the previously described HpAfrica1 genetic population, subpopulations hspWAfrica and hspSAfrica, respectively. These 2 subpopulations correspond to the distribution of Niger-Congo speakers in West and most of subequatorial Africa (due to Bantu migrations), respectively. H. pylori appears as a single population in Senegal, indicating a long common history between ethnicities as well as frequent local admixtures. The lack of differentiation between these isolates and an increasing genetic differentiation with geographical distance between sampling locations in Africa was evidence for genetic isolation by distance. The Austronesian expansion that started from Taiwan 5000 years ago dispersed one of the 10 subgroups of the Austronesian language family via insular Southeast Asia into the Pacific and Madagascar, and hspMaori is a marker for the entire Austronesian expansion. Strain competition and replacement of hspMaori by hpAfrica1 strains from Bantu migrants are the probable reasons for the presence of hspSAfrica strains in Malagasy of Southeast Asian descent. hpAfrica1 strains appear to be generalist strains that have the necessary genetic diversity to efficiently colonise a wide host spectrum.     

Trypanosoma vivax: mechanical transmission in cattle by one of the most common African tabanids,Atylotus agrestis

The role of mechanical vectors in the transmission of African livestock trypanosomes has always been controversial relative to tsetse flies, their cyclical vectors. An experiment was carried out in Burkina Faso to demonstrate mechanical transmission of Trypanosoma vivax by one of the most common tabanids in Africa: Atylotus agrestis. Eight heifers (crossbred zebuxBaoulé), free of trypanosome infection, were kept in a corral covered by a mosquito net, together with two heifers infected experimentally with a local stock of T. vivax. On average, 324 A. agrestis, freshly captured with Nzi traps, were introduced daily over 20 days. Parasitological, PCR and serological examinations were carried out regularly to assess infections and levels of parasitaemia. Microscopic examination of buffy-coats indicated that five of the eight receiver-heifers were infected on days 8, 13, 32, 41, and 48. PCR results indicated that these five heifers were already infected by day 13. Mechanical transmission of T. vivax by A. agrestis was demonstrated unequivocally, at a high rate (63% in 13-20 days). Conditions of transmission in this experiment are discussed in terms of natural rates of challenge. The importance of tabanids as mechanical vectors of T. vivax should be re-considered, in light of these results. Creation of tsetse free zones in Africa will generally lead to the disappearance of T. congolense, T. brucei, and most often T. vivax as well; however, in areas where T. vivax can be mechanically transmitted, clearance of tsetse may not be sufficient to eradicate livestock trypanosomosis.