Neighbours' breeding success and the sex ratio of their offspring affect the mate preferences of female zebra finches

Several hypotheses on divorce predict that monogamous pairs should split up more frequently after a breeding failure. Yet, deviations from the expected pattern "success-stay, failure-leave" have been reported in several species. One possible explanation for these deviations would be that individuals do not use only their own breeding performance (i.e., private information) but also that of others (i.e., public information) to decide whether or not to divorce. To test this hypothesis, we investigated the relative importance of private and public information for mate choice decisions in female zebra finches (Taeniopygia guttata).We manipulated the reproductive performance of breeding pairs and measured females' preferences for their mate and the neighbouring male first following pair formation and then seven weeks later when all females had laid eggs and the young were independent. Although all females reduced their preference for their mate after a breeding failure, the decrease was significant only when the neighbouring pair had reproduced successfully. Furthermore, there was no evidence that females biased the sex ratio of their offspring according to their mate's attractiveness. On the other hand, after reproduction, both successful and unsuccessful females increased their preferences for males who had produced a larger proportion of sons. Despite the fact that other mechanisms may have also contributed to our findings, we suggest that females changed their mate preferences based on the proportion of sons produced by successful males, because offspring sex ratio reflects the male's testosterone level at the moment of fertilization and hence is an indicator of his immune condition.     

Differential expression of two somatostatin genes during zebrafish embryonic development

We have identified the cDNAs of two new zebrafish preprosomatostatins, PPSS1 and PPSS3, in addition to the previously cloned PPSS2 (Argenton et al., 1999). PPSS1 is the orthologue of mammalian PPSSs, with a conserved C-terminal SS-14 sequence, PPSS2 is a divergent SS precursor and PPSS3 is a cortistatin-like prohormone. Using whole-mount in situ hybridisation, we have analysed the expression of PPSS1 and PPSS2 in zebrafish embryos up to 5 days post fertilisation. PPSS1 was expressed in the developing pancreas and central nervous system (CNS), whereas PPSS2 expression was exclusively pancreatic. In the CNS, PPSS1 was detected in several areas, in particular in the vagal motor nucleus and in cells that pioneer the tract of the postoptic commissure. PPSS1 was also expressed transiently in the telencephalon and spinal motor neurons. In all areas but the telencephalon PPSS1 was coexpressed with islet-1.     

Macrozoobenthos of two Antarctic glacial coves: a comparison with non-disturbed bottom areas

There are only few studies on shallow Antarctic benthic communities associated with habitats affected by intense mineral sedimentation inflow. The analysis of macrofaunal communities associated with two shallow, isolated glacial coves was performed in Admiralty Bay (King George Island) and compared with non-disturbed sites. Multivariate analyses (hierarchical classification, nMDS) clearly separated glacial cove communities (two assemblages) from the sites situated outside both basins (two assemblages). The community influenced by the streamflow of glacial discharge of meltwater situated in the area with sandy–clay–silt sediments had a very low species richness, diversity and abundance. It was dominated by eurytopic, motile deposit feeding polychaetes such as Mesospio moorei, Tharyx cincinnatus and Leitoscoloplos kerguelensis as well as the bivalve Yoldia eightsi. The second glacial community of the area located at a grater distance from the outlet of the stream was characterized by sandy–clay–silt and clay–silt deposits and showed also a low diversity and species richness. The most abundant here were peracarid crustaceans, with the dominant opportunistic feeder Cheirimedon femoratus. Community from the non-disturbed area with silty–clay–sand, and silty–sand sediments had higher species richness and diversity. The assemblage of fauna from the sandy bottom has values of those two indexes similar to those found in the disturbed areas.     

Between- and within-host species selection on cytoplasmic incompatibility-inducing Wolbachia in haplodiploids

Abstract The most common effect of the endosymbiont Wolbachia is cytoplasmic incompatibility (CI), a form of postzygotic reproductive isolation that occurs in crosses where the male is infected by at least one Wolbachia strain that the female lacks. We revisited two puzzling features of Wolbachia biology: how Wolbachia can invade a new species and spread among populations, and how the association, once established in a host species, can evolve, with emphasis on the possible process of infection loss. These questions are particularly relevant in haplodiploid species, where males develop from unfertilized eggs, and females from fertilized eggs. When CI occurs in such species, fertilized eggs either die (female mortality type: FM), or develop into males (male development type: MD), raising one more question: how transition among CI types is possible. We reached the following conclusions: (1) the FM type is a better invader and should be retained preferentially after a new host is captured; (2) given the assumptions of the models, FM and MD types are selected on neither the bacterial side nor the host side; (3) selective pressures acting on both partners are more or less congruent in the FM type, but divergent in the MD type; (4) host and symbiont evolution can drive infection to extinction for all CI types, but the MD type is more susceptible to the phenomenon; and (5) under realistic conditions, transition from MD to FM type is possible. Finally, all these results suggest that the FM type should be more frequent than the MD type, which is consistent with the results obtained so far in haplodiploids.     

Characterization of a novel Obg-like ATPase in the protozoan Trypanosoma cruzi

We characterized a gene encoding an YchF-related protein, TcYchF, potentially associated with the protein translation machinery of Trypanosoma cruzi. YchF belongs to the translation factor-related (TRAFAC) class of P-loop NTPases. The coding region of the gene is 1185 bp long and encodes a 44.3 kDa protein. BlastX searches showed TcYchF to be very similar (45-86%) to putative GTP-binding proteins from eukaryotes, including some species of trypanosomatids (Leishmania major and Trypanosoma brucei). A lower but significant level of similarity (38-43%) was also found between the predicted sequences of TcYchF and bacterial YyaF/YchF GTPases of the Spo0B-associated GTP-binding protein (Obg) family. Some of the most important features of the G domain of this family of GTPases are conserved in TcYchF. However, we found that TcYchF preferentially hydrolyzed ATP rather than GTP. The function of YyaF/YchF is unknown, but other members of the Obg family are known to be associated with ribosomal subunits. Immunoblots of the polysome fraction from sucrose gradients showed that TcYchF was associated with ribosomal subunits and polysomes. Immunoprecipitation assays showed that TcYchF was also associated with the proteasome of T. cruzi. Furthermore, inactivation of the T. brucei homolog of TcYchF by RNA interference inhibited the growth of procyclic forms of the parasite. These data suggest that this protein plays an important role in the translation machinery of trypanosomes.     

The inhibitory effect of boric acid on hypoxia-regulated tumour-associated carbonic anhydrase IX

Carbonic anhydrases (EC 4.2.1.1) catalyse the reversible hydration of CO₂ into bicarbonate and protons. As a hypoxia-sensitive and tumour-associated isoform, isoform CA IX, is significantly overexpressed in various malignancies, being a validated target for new anticancer/antimetastatic drugs. A multitude of studies has shown that CA IX inhibition decreases cancer cell proliferation and metastasis through pHe/pHi modulation and enhancement of ferroptosis among others. Numerous studies demonstrated increased efficacy of cytotoxic drugs combined with CA inhibitors (CAIs) in various cancer types. We tested the inhibitory effect of boric acid (BA), an inorganic Lewis acid, on CA IX as well as other isoforms (CA I, II, and XII). BA acted as a millimolar in vitro CAI, decreased proliferation of two cancer cell lines, although not strong correlations between the in vitro inhibition and in vivo effects were observed. The mechanism of antiproliferative action of BA should be investigated in more detail.     

Cytomegalovirus Infection in Inflammatory Bowel Disease Is Not Associated with Worsening of Intestinal Inflammatory Activity

Background

Cytomegalovirus is highly prevalent virus and usually occurs in immunocompromised patients. The pathophysiology and treatment of inflammatory bowel disease often induce a state of immunosuppression. Because this, there are still doubts and controversies about the relationship between inflammatory bowel disease and cytomegalovirus.

Aim

Evaluate the frequency of cytomegalovirus in patients with inflammatory bowel disease and identify correlations.

Methods

Patients with inflammatory bowel disease underwent an interview, review of records and collection of blood and fecal samples. The search for cytomegalovirus was performed by IgG and IgM blood serology, by real-time PCR in the blood and by qualitative PCR in feces. Results were correlated with red blood cell levels, C-reactive protein levels, erythrocyte sedimentation rates and fecal calprotectin levels for each patient.

Results

Among the 400 eligible patients, 249 had Crohn''s disease, and 151 had ulcerative colitis. In the group of Crohn''s disease, 67 of the patients had moderate or severe disease, but 126 patients presented with active disease, based on the evaluation of the fecal calprotectin. In patients with ulcerative colitis, only 21 patients had moderate disease, but 76 patients presented with active disease, based on the evaluation of the fecal calprotectin. A large majority of patients had positive CMV IgG. Overall, 10 patients had positive CMV IgM, and 9 patients had a positive qualitative detection of CMV DNA by PCR in the feces. All 400 patients returned negative results after the quantitative detection of CMV DNA in blood by real-time PCR. Analyzing the 19 patients with active infections, we only found that such an association occurred with the use of combined therapy (anti-TNF-alpha + azathioprine)

Conclusion

The findings show that latent cytomegalovirus infections are frequent and active cytomegalovirus infection is rare. We did not find any association between an active infection of CMV and inflammatory bowel disease activity.     

Synaptophysin I selectively specifies the exocytic pathway of synaptobrevin 2/VAMP2

Biogenesis and recycling of synaptic vesicles are accompanied by sorting processes that preserve the molecular composition of the compartments involved. In the present study, we have addressed the targeting of synaptobrevin 2/VAMP2 (vesicle-associated membrane protein 2), a critical component of the synaptic vesicle--fusion machinery, in a heterotypic context where its sorting is not confounded by the presence of other neuron-specific molecules. Ectopically expressed synaptophysin I interacts with VAMP2 and alters its default surface targeting to a prominent vesicular distribution, with no effect on the targeting of other membrane proteins. Protein-protein interaction is not sufficient for the control of VAMP2 sorting, which is mediated by the C-terminal domain of synaptophysin I. Synaptophysin I directs the sorting of VAMP2 to vesicles before surface delivery, without influencing VAMP2 endocytosis. Consistent with this, dynamin and alpha-SNAP (soluble N-ethylmaleimide-sensitive fusion protein-attachment protein) mutants which block trafficking at the plasma membrane do not abrogate the effect of synaptophysin I on VAMP2 sorting. These results indicate that the sorting determinants of synaptic vesicle proteins can operate independently of a neuronal context and implicate the association of VAMP2 with synaptophysin I in the specification of the pathway of synaptic vesicle biogenesis.     

Asymptotic properties of infinite Leslie matrices

The stable population theory is classically applicable to populations in which there is a maximum age after which individuals die. Demetrius [1972. On an infinite population matrix. Math. Biosci. 13, 133-137] extended this theory to infinite Leslie matrices, in which the longevity of individuals is potentially infinite. However, Demetrius had to assume that the survival probability per time step tends to 0 with age. We generalise here the conditions of application of the stable population theory to infinite Leslie matrix models and apply these results to two examples, including or not senescence.