Prevalence of trypanosomes,salivary gland hypertrophy virus and <Emphasis Type="Italic">Wolbachia</Emphasis> in wild populations of tsetse flies from West Africa

Background

Tsetse flies are vectors of African trypanosomes, protozoan parasites that cause sleeping sickness (or human African trypanosomosis) in humans and nagana (or animal African trypanosomosis) in livestock. In addition to trypanosomes, four symbiotic bacteria Wigglesworthia glossinidia, Sodalis glossinidius, Wolbachia, Spiroplasma and one pathogen, the salivary gland hypertrophy virus (SGHV), have been reported in different tsetse species. We evaluated the prevalence and coinfection dynamics between Wolbachia, trypanosomes, and SGHV in four tsetse species (Glossina palpalis gambiensis, G. tachinoides, G. morsitans submorsitans, and G. medicorum) that were collected between 2008 and 2015 from 46 geographical locations in West Africa, i.e. Burkina Faso, Mali, Ghana, Guinea, and Senegal.

Results

The results indicated an overall low prevalence of SGHV and Wolbachia and a high prevalence of trypanosomes in the sampled wild tsetse populations. The prevalence of all three infections varied among tsetse species and sample origin. The highest trypanosome prevalence was found in Glossina tachinoides (61.1%) from Ghana and in Glossina palpalis gambiensis (43.7%) from Senegal. The trypanosome prevalence in the four species from Burkina Faso was lower, i.e. 39.6% in Glossina medicorum, 18.08%; in Glossina morsitans submorsitans, 16.8%; in Glossina tachinoides and 10.5% in Glossina palpalis gambiensis. The trypanosome prevalence in Glossina palpalis gambiensis was lowest in Mali (6.9%) and Guinea (2.2%). The prevalence of SGHV and Wolbachia was very low irrespective of location or tsetse species with an average of 1.7% for SGHV and 1.0% for Wolbachia. In some cases, mixed infections with different trypanosome species were detected. The highest prevalence of coinfection was Trypanosoma vivax and other Trypanosoma species (9.5%) followed by coinfection of T. congolense with other trypanosomes (7.5%). The prevalence of coinfection of T. vivax and T. congolense was (1.0%) and no mixed infection of trypanosomes, SGHV and Wolbachia was detected.

Conclusion

The results indicated a high rate of trypanosome infection in tsetse wild populations in West African countries but lower infection rate of both Wolbachia and SGHV. Double or triple mixed trypanosome infections were found. In addition, mixed trypanosome and SGHV infections existed however no mixed infections of trypanosome and/or SGHV with Wolbachia were found.

     

A Distinct Class of Genome Rearrangements Driven by Heterologous Recombination

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Molecular genetics of the transcription factor GLIS3 identifies its dual function in beta cells and neurons

The GLIS family zinc finger 3 isoform (GLIS3) is a risk gene for Type 1 and Type 2 diabetes, glaucoma and Alzheimer's disease endophenotype. We identified GLIS3 binding sites in insulin secreting cells (INS1) (FDR q < 0.05; enrichment range 1.40–9.11 fold) sharing the motif wrGTTCCCArTAGs, which were enriched in genes involved in neuronal function and autophagy and in risk genes for metabolic and neuro-behavioural diseases. We confirmed experimentally Glis3-mediated regulation of the expression of genes involved in autophagy and neuron function in INS1 and neuronal PC12 cells. Naturally-occurring coding polymorphisms in Glis3 in the Goto-Kakizaki rat model of type 2 diabetes were associated with increased insulin production in vitro and in vivo, suggestive alteration of autophagy in PC12 and INS1 and abnormal neurogenesis in hippocampus neurons. Our results support biological pleiotropy of GLIS3 in pathologies affecting β-cells and neurons and underline the existence of trans?nosology pathways in diabetes and its co-morbidities.     

Growth of Fagus sylvatica saplings in an old-growth forest as affected by soil and light conditions

Abstract. Studies were conducted on 41 five yr-old common beech (Fagus sylvatica) saplings collected in an old-growth beech wood (Fontainebleau forest, biological reserve of La Tillaie, France), under varying humus and light conditions, following gypsy moth (Lymantria dispar) caterpillar injuries. Aerial and subterranean parts of each sapling were described by means of 34 parameters and environmental conditions at the microsite, where each sapling was excavated, were characterized by 23 parameters. The development of beech saplings is strongly affected by microsite conditions. An increase in sapling size was associated with darkness of the A-horizon, typical of zones with poor mineralization of organic matter. Light conditions were more important in influencing the development of the root system than that of the aerial parts. Rooting depth was shallower and rate of mycorrhiza development by the black ascomycete Cenococcum geophilum was lower in microsites receiving incident light during the morning than in those never receiving incident light during this period. Results are discussed in the frame of survival of young beech individuals in varying environmental conditions, when submitted to competition by other vegetation and adverse climate conditions.     

Evidence for the dimerization of human regulator of G-protein signalling 5 (RGS5).

RGS5 is a R4 type RGS that regulates GPCR signalling. Using western blot, we detected RGS5 as a specific 23 kDa protein in cells overexpressing RGS5. A 42 kDa band representing a possible RGS5 dimer was also detected. Given that GPCRs and their associated proteins form complexes involving multiple protein-protein interactions, we investigated the possibility that the 42 kDa band represents an RGS5-RGS5 dimer. RGS5 dimerization was confirmed by the analysis of a GFP tagged RGS5 fusion in yeast and with two-hybrid assays. Analysis of RGS5 in HEK293A cells suggests that the dimer may serve a regulatory function since it is longer lived than the monomer.     

Angiotensin II stimulates the production of NO and peroxynitrite in endothelial cells

Angiotensin II(ANG II) produces vasoconstriction by a direct action on smooth musclecells via AT₁ receptors. Thesereceptors are also present in the endothelium, but their function ispoorly understood. This study was therefore undertaken to determinewhether ANG II elicits the release of nitric oxide (NO) from cultured rat aortic endothelial cells. NO production, measured by theaccumulation of nitrite and nitrate, was enhanced by10⁷ M ANG II. Thebiological activity of the NO released by ANG II action was evaluatedby measuring its guanylate cyclase-stimulating activity in smoothmuscle cells. The guanosine 3',5'-cyclic monophosphate (cGMP) content of smooth muscle cells was significantly increased byexposure of supernatant from ANG II-stimulated endothelial cells. Theseeffects resulted from the activation of NO synthase, as they wereinhibited by the L-arginineanalogs. These ANG II actions were mediated by theAT₁ receptor, as shown by theirinhibition by the AT₁ antagonistlosartan. The cGMP production by reporter cells was inhibited by thecalmodulin antagonist W-7, suggesting that ANG II activates endothelialcalmodulin-dependent NO synthase. This hypothesis is also supported bythe increase of intracellular free calcium induced by ANG II inendothelial cells. ANG II also stimulated luminol-enhancedchemiluminescence in endothelial cells. This effect was inhibited byN-monomethyl-L-arginine andsuperoxide dismutase, suggesting that this luminol-enhancedchemiluminescence reflected an increase in peroxynitrite production.Thus ANG II stimulates NO release from macrovascular endothelium, whichmay modulate the direct vasoconstrictor effect of ANG II on smoothmuscle cells. However, this beneficial effect may be counteracted bythe simultaneous production of peroxynitrite, which could contribute toseveral pathological processes in the vascular wall.

     

Intergroup variation in robbing and bartering by long-tailed macaques at Uluwatu Temple (Bali,Indonesia)

Robbing and bartering (RB) is a behavioral practice anecdotally reported in free-ranging commensal macaques. It usually occurs in two steps: after taking inedible objects (e.g., glasses) from humans, the macaques appear to use them as tokens, returning them to humans in exchange for food. While extensively studied in captivity, our research is the first to investigate the object/food exchange between humans and primates in a natural setting. During a 4-month study in 2010, we used both focal and event sampling to record 201 RB events in a population of long-tailed macaques (Macaca fascicularis), including four neighboring groups ranging freely around Uluwatu Temple, Bali (Indonesia). In each group, we documented the RB frequency, prevalence and outcome, and tested the underpinning anthropogenic and demographic determinants. In line with the environmental opportunity hypothesis, we found a positive qualitative relation at the group level between time spent in tourist zones and RB frequency or prevalence. For two of the four groups, RB events were significantly more frequent when humans were more present in the environment. We also found qualitative partial support for the male-biased sex ratio hypothesis [i.e., RB was more frequent and prevalent in groups with higher ratios of (sub)adult males], whereas the group density hypothesis was not supported. This preliminary study showed that RB is a spontaneous, customary (in some groups), and enduring population-specific practice characterized by intergroup variation in Balinese macaques. As such, RB is a candidate for a new behavioral tradition in this species.     

A multi-trait systems approach reveals a response cascade to bleaching in corals

Background

Climate change causes the breakdown of the symbiotic relationships between reef-building corals and their photosynthetic symbionts (genus Symbiodinium), with thermal anomalies in 2015–2016 triggering the most widespread mass coral bleaching on record and unprecedented mortality on the Great Barrier Reef. Targeted studies using specific coral stress indicators have highlighted the complexity of the physiological processes occurring during thermal stress, but have been unable to provide a clear mechanistic understanding of coral bleaching.

Results

Here, we present an extensive multi-trait-based study in which we compare the thermal stress responses of two phylogenetically distinct and widely distributed coral species, Acropora millepora and Stylophora pistillata, integrating 14 individual stress indicators over time across a simulated thermal anomaly. We found that key stress responses were conserved across both taxa, with the loss of symbionts and the activation of antioxidant mechanisms occurring well before collapse of the physiological parameters, including gross oxygen production and chlorophyll a. Our study also revealed species-specific traits, including differences in the timing of antioxidant regulation, as well as drastic differences in the production of the sulfur compound dimethylsulfoniopropionate during bleaching. Indeed, the concentration of this antioxidant increased two-fold in A. millepora after the corals started to bleach, while it decreased 70% in S. pistillata.

Conclusions

We identify a well-defined cascading response to thermal stress, demarking clear pathophysiological reactions conserved across the two species, which might be central to fully understanding the mechanisms triggering thermally induced coral bleaching. These results highlight that bleaching is a conserved mechanism, but specific adaptations linked to the coral’s antioxidant capacity drive differences in the sensitivity and thus tolerance of each coral species to thermal stress.

     

Three-dimensional electron microscopy analysis of ndc10-1 mutant reveals an aberrant organization of the mitotic spindle and spindle pole body defects in Saccharomyces cerevisiae

Kinetochore components play a major role in regulating the transmission of genetic information during cell division. Ndc10p, a kinetochore component of the essential CBF3 complex in budding yeast is required for chromosome attachment to the mitotic spindle. ndc10-1 mutant was shown to display chromosome mis-segregation as well as an aberrant mitotic spindle (Goh and Kilmartin, 1993). In addition, Ndc10p localizes along the spindle microtubules (Muller-Reichert et al., 2003). To further understand the role of Ndc10p in the mitotic apparatus, we performed a three-dimensional electron microscopy (EM) reconstruction of mitotic spindles from serial sections of cryo-immobilized ndc10-1 mutant cells. This analysis reveals a dramatic reduction in the number of microtubules present in the half-spindle, which is connected to the newly formed spindle pole body (SPB) in ndc10-1 cells. Moreover, in contrast to wild-type (WT) cells, ndc10-1 cells showed a significantly lower signal intensity of the SPB components Spc42p and Spc110p fused with GFP, in mother cell bodies compared with buds. A subsequent EM analysis also showed clear defects in the newly formed SPB, which remains in the mother cell during anaphase. These results suggest that Ndc10p is required for maturation of the newly formed SPB. Intriguingly, mutations in other kinetochore components, ndc80-1 and spc24-1, showed kinetochore detachment from the spindle, similar to ndc10-1, but did not display defects in SPBs. This suggests that unattached kinetochores are not sufficient to cause SPB defects in ndc10-1 cells. We propose that Ndc10p, alongside its role in kinetochore–microtubule interaction, is also essential for SPB maturation and mitotic spindle integrity.