Gene conversion limits divergence of mammalian TLR1 and TLR6

<p>Abstract</p> <p>Background</p> <p>Toll-like receptors (TLR) recognize pathogen-associated molecular patterns and are important mediators of the innate immune system. TLR1 and TLR6 are paralogs and located in tandem on the same chromosome in mammals. They form heterodimers with TLR2 and bind lipopeptide components of gram-positive and gram-negative bacterial cell walls. To identify conserved stretches in TLR1 and TLR6, that may be important for their function, we compared their protein sequences in nine mammalian species(<it>Homo sapiens</it>, <it>Pan troglodytes</it>, <it>Macaca mulatta</it>, <it>Mus musculus</it>, <it>Rattus norvegicus</it>; <it>Erinaceus europaeus</it>, <it>Bos Taurus</it>, <it>Sus scrofa </it>and <it>Canis familiaris</it>).</p> <p>Results</p> <p>The N-terminal sequences of the orthologous proteins showed greater similarity than corresponding paralog sequences. However, we identified a region of 300 amino acids towards the C-terminus of TLR1 and TLR6, where paralogs had a greater degree of sequence identity than orthologs. Preservation of DNA sequence identity of paralogs in this region was observed in all nine mammalian species investigated, and is due to independent gene conversion events. The regions having undergone gene conversion in each species are almost identical and encode the leucine-rich repeat motifs 16 to 19, the C-terminal cap motif, the transmembrane domain and most of the intracellular Toll/interleukin-1 receptor (TIR) domain.</p> <p>Conclusion</p> <p>Our results show that, for a specific conserved region, divergence of TLR1 and TLR6 is limited by gene conversion, most likely because of the need for co-evolution with multiple intracellular and extracellular binding partners. Thus, gene conversion provides a mechanism for limiting the divergence of functional regions of protein paralogs, while allowing other domains to evolve diversified functions.</p

The protein kinase TOUSLED facilitates RNAi in Arabidopsis

RNA silencing is an evolutionarily conserved mechanism triggered by double-stranded RNA that is processed into 21- to 24-nt small interfering (si)RNA or micro (mi)RNA by RNaseIII-like enzymes called Dicers. Gene regulations by RNA silencing have fundamental implications in a large number of biological processes that include antiviral defense, maintenance of genome integrity and the orchestration of cell fates. Although most generic or core components of the various plant small RNA pathways have been likely identified over the past 15 years, factors involved in RNAi regulation through post-translational modifications are just starting to emerge, mostly through forward genetic studies. A genetic screen designed to identify factors required for RNAi in Arabidopsis identified the serine/threonine protein kinase, TOUSLED (TSL). Mutations in TSL affect exogenous and virus-derived siRNA activity in a manner dependent upon its kinase activity. By contrast, despite their pleiotropic developmental phenotype, tsl mutants show no defect in biogenesis or activity of miRNA or endogenous trans-acting siRNA. These data suggest a possible role for TSL phosphorylation in the specific regulation of exogenous and antiviral RNA silencing in Arabidopsis and identify TSL as an intrinsic regulator of RNA interferenc

Females tend to prefer genetically similar mates in an island population of house sparrows

BACKGROUND: It is often proposed that females should select genetically dissimilar mates to maximize offspring genetic diversity and avoid inbreeding. Several recent studies have provided mixed evidence, however, and in some instances females seem to prefer genetically similar males. A preference for genetically similar mates can be adaptive if outbreeding depression is more harmful than inbreeding depression or if females gain inclusive fitness benefits by mating with close kin. Here, we investigated genetic compatibility and mating patterns in an insular population of house sparrow (Passer domesticus), over a three-year period, using 12 microsatellite markers and one major histocompability complex (MHC) class I gene. Given the small population size and the distance from the mainland, we expected a reduced gene flow in this insular population and we predicted that females would show mating preferences for genetically dissimilar mates. RESULTS: Contrary to our expectation, we found that offspring were less genetically diverse (multi-locus heterozygosity) than expected under a random mating, suggesting that females tended to mate with genetically similar males. We found high levels of extra-pair paternity, and offspring sired by extra-pair males had a better fledging success than those sired by the social male. Again, unexpectedly, females tended to be more closely related to extra-pair mates than to their social mates. Our results did not depend on the type of genetic marker used, since microsatellites and MHC genes provided similar results, and we found only little evidence for MHC-dependent mating patterns. CONCLUSIONS: These results are in agreement with the idea that mating with genetically similar mates can either avoid the disruption of co-adapted genes or confer a benefit in terms of kin selection

Involvement of RDR6 in short-range intercellular RNA silencing in Nicotiana benthamiana

In plants, non-cell autonomous RNA silencing spreads between cells and over long distances. Recent work has revealed insight on the genetic and molecular components essential for cell-to-cell movement of RNA silencing in Arabidopsis. Using a local RNA silencing assay, we report on a distinct mechanism that may govern the short-range (6–10 cell) trafficking of virus-induced RNA silencing from epidermal to neighbouring palisade and spongy parenchyma cells in Nicotiana benthamiana. This process involves a previously unrecognised function of the RNA-dependent RNA polymerase 6 (RDR6) gene. Our data suggest that plants may have evolved distinct genetic controls in intercellular RNA silencing among different types of cells

Influence of viral genes on the cell-to-cell spread of RNA silencing

The turnip crinkle virus-based vector TCV–GFPΔCP had been devised previously to study cell-to-cell and long-distance spread of virus-induced RNA silencing. TCV–GFPΔCP, which had been constructed by replacing the coat protein (CP) gene with a green fluorescent protein (GFP) coding sequence, was able to induce RNA silencing in single epidermal cells, from which RNA silencing spread from cell-to-cell. Using this unique local silencing assay together with mutagenesis analysis, two TCV genes, p8 and p9, which were involved in the intercellular spread of virus-induced RNA silencing, were identified. TCV–GFPΔCP and its p8- or p9-mutated derivatives, TCVmp8–GFPΔCP and TCVmp9–GFPΔCP, replicated efficiently but were restricted to single Nicotiana benthamiana epidermal cells. TCV–GFPΔCP, TCVmp8–GFPΔCP, or TCVmp9–GFPΔCP was able to initiate RNA silencing that targeted and degraded recombinant viral RNAs in inoculated leaves of the GFP-expressing N. benthamiana line 16c. However, cell-to-cell spread of silencing to form silencing foci was triggered only by TCV–GFPΔCP. Non-replicating TCVmp88–GFPΔCP and TCVmp28mp88–GFPΔCP with dysfunctional replicase genes, and single-stranded gfp RNA did not induce RNA silencing. Transient expression of the TCV p9 protein could effectively complement TCVmp9–GFPΔCP to facilitate intercellular spread of silencing. These data suggest that the plant cellular trafficking machinery could hijack functional viral proteins to permit cell-to-cell movement of RNA silencing

Animal board invited review: Risks of zoonotic disease emergence at the interface of wildlife and livestock systems.

The ongoing coronavirus disease 19s pandemic has yet again demonstrated the importance of the human-animal interface in the emergence of zoonotic diseases, and in particular the role of wildlife and livestock species as potential hosts and virus reservoirs. As most diseases emerge out of the human-animal interface, a better understanding of the specific drivers and mechanisms involved is crucial to prepare for future disease outbreaks. Interactions between wildlife and livestock systems contribute to the emergence of zoonotic diseases, especially in the face of globalization, habitat fragmentation and destruction and climate change. As several groups of viruses and bacteria are more likely to emerge, we focus on pathogenic viruses of the Bunyavirales, Coronaviridae, Flaviviridae, Orthomyxoviridae, and Paramyxoviridae, as well as bacterial species including Mycobacterium sp., Brucella sp., Bacillus anthracis and Coxiella burnetii. Noteworthy, it was difficult to predict the drivers of disease emergence in the past, even for well-known pathogens. Thus, an improved surveillance in hotspot areas and the availability of fast, effective, and adaptable control measures would definitely contribute to preparedness. We here propose strategies to mitigate the risk of emergence and/or re-emergence of prioritized pathogens to prevent future epidemics

Adherencia, satisfacción al tratamiento y calidad de vida de pacientes con cáncer de mama en el Hospital Universitario del Caribe.(Cartagena, Colombia)

Objetivos: Determinar la adherencia, satisfacción al tratamiento y calidad de vida de pacientes con cáncer de mama. Materiales y métodos: Estudio descriptivo, prospectivo, trasversal,  desarrollado en el Hospital Universitario del Caribe, entre agosto de 2014 y  abril de 2015. La muestra fueron 23 pacientes, diagnosticadas de cáncer de mama. La adherencia, satisfacción al tratamiento y calidad de vida se determinaron con los instrumentos siguientes: Cuestionario simplified medication adherence questionnaire (SMAQ), registro de dispensación del hospital (RD), test de satisfacción ESTAR del Estudio ARPAS adaptado y el cuestionario WHOQOL BREF respectivamente. El cuestionario ESTAR fue  validado por expertos y mediante alfa de Cronbach.   Resultados: El 54,78% de las pacientes (según SMAQ), fueron no  adherentes a quimioterápicos, la satisfacción fue de 3,94 (rango 0-6). La calidad de vida estuvo en un promedio de 3.2 (rango 1-5), con valores de 14,5% y 7,14% en el nivel 5 del rango. La mayoría de dimensiones del cuestionario de calidad de vida guardan una correlación directamente  proporcional con el nivel total de satisfacción al tratamiento; arrojando un dato negativo (-0,3207) únicamente en la dimensión de satisfacción con la eficacia al tratamiento   Conclusiones: La calidad de vida fue media y baja, la adherencia y  satisfacción al tratamiento fueron bajas y se presentó una correlación inversa entre calidad de vida y la satisfacción al tratamiento, probablemente a causa de reacciones adversas indeseables que se constituyen en disminución de la calidad de vida

Adherencia, satisfacción al tratamiento y calidad de vida de pacientes con cáncer de mama en el Hospital Universitario del Caribe.(Cartagena, Colombia)

Objetivos: Determinar la adherencia, satisfacción al tratamiento y calidad de vida de pacientes con cáncer de mama. Materiales y métodos: Estudio descriptivo, prospectivo, trasversal,  desarrollado en el Hospital Universitario del Caribe, entre agosto de 2014 y  abril de 2015. La muestra fueron 23 pacientes, diagnosticadas de cáncer de mama. La adherencia, satisfacción al tratamiento y calidad de vida se determinaron con los instrumentos siguientes: Cuestionario simplified medication adherence questionnaire (SMAQ), registro de dispensación del hospital (RD), test de satisfacción ESTAR del Estudio ARPAS adaptado y el cuestionario WHOQOL BREF respectivamente. El cuestionario ESTAR fue  validado por expertos y mediante alfa de Cronbach.   Resultados: El 54,78% de las pacientes (según SMAQ), fueron no  adherentes a quimioterápicos, la satisfacción fue de 3,94 (rango 0-6). La calidad de vida estuvo en un promedio de 3.2 (rango 1-5), con valores de 14,5% y 7,14% en el nivel 5 del rango. La mayoría de dimensiones del cuestionario de calidad de vida guardan una correlación directamente  proporcional con el nivel total de satisfacción al tratamiento; arrojando un dato negativo (-0,3207) únicamente en la dimensión de satisfacción con la eficacia al tratamiento   Conclusiones: La calidad de vida fue media y baja, la adherencia y  satisfacción al tratamiento fueron bajas y se presentó una correlación inversa entre calidad de vida y la satisfacción al tratamiento, probablemente a causa de reacciones adversas indeseables que se constituyen en disminución de la calidad de vida

Transgene Silencing and Transgene-Derived siRNA Production in Tobacco Plants Homozygous for an Introduced AtMYB90 Construct

Transgenic tobacco (Nicotiana tabacum) lines were engineered to ectopically over-express AtMYB90 (PAP2), an R2–R3 Myb gene associated with regulation of anthocyanin production in Arabidopsis thaliana. Independently transformed transgenic lines, Myb27 and Myb237, accumulated large quantities of anthocyanin, generating a dark purple phenotype in nearly all tissues. After self-fertilization, some progeny of the Myb27 line displayed an unexpected pigmentation pattern, with most leaves displaying large sectors of dramatically reduced anthocyanin production. The green-sectored 27Hmo plants were all found to be homozygous for the transgene and, despite a doubled transgene dosage, to have reduced levels of AtMYB90 mRNA. The observed reduction in anthocyanin pigmentation and AtMYB90 mRNA was phenotypically identical to the patterns seen in leaves systemically silenced for the AtMYB90 transgene, and was associated with the presence of AtMYB90-derived siRNA homologous to both strands of a portion of the AtMYB90 transcribed region. Activation of transgene silencing in the Myb27 line was triggered when the 35S::AtMYB90 transgene dosage was doubled, in both Myb27 homozygotes, and in plants containing one copy of each of the independently segregating Myb27 and Myb237 transgene loci. Mapping of sequenced siRNA molecules to the Myb27 TDNA (including flanking tobacco sequences) indicated that the 3′ half of the AtMYB90 transcript is the primary target for siRNA associated silencing in both homozygous Myb27 plants and in systemically silenced tissues. The transgene within the Myb27 line was found to consist of a single, fully intact, copy of the AtMYB90 construct. Silencing appears to initiate in response to elevated levels of transgene mRNA (or an aberrant product thereof) present within a subset of leaf cells, followed by spread of the resulting small RNA to adjacent leaf tissues and subsequent amplification of siRNA production