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121.
Simona Rosu Karl A. Zawadzki Ericca L. Stamper Diana E. Libuda Angela L. Reese Abby F. Dernburg Anne M. Villeneuve 《PLoS genetics》2013,9(8)
For most organisms, chromosome segregation during meiosis relies on deliberate induction of DNA double-strand breaks (DSBs) and repair of a subset of these DSBs as inter-homolog crossovers (COs). However, timing and levels of DSB formation must be tightly controlled to avoid jeopardizing genome integrity. Here we identify the DSB-2 protein, which is required for efficient DSB formation during C. elegans meiosis but is dispensable for later steps of meiotic recombination. DSB-2 localizes to chromatin during the time of DSB formation, and its disappearance coincides with a decline in RAD-51 foci marking early recombination intermediates and precedes appearance of COSA-1 foci marking CO-designated sites. These and other data suggest that DSB-2 and its paralog DSB-1 promote competence for DSB formation. Further, immunofluorescence analyses of wild-type gonads and various meiotic mutants reveal that association of DSB-2 with chromatin is coordinated with multiple distinct aspects of the meiotic program, including the phosphorylation state of nuclear envelope protein SUN-1 and dependence on RAD-50 to load the RAD-51 recombinase at DSB sites. Moreover, association of DSB-2 with chromatin is prolonged in mutants impaired for either DSB formation or formation of downstream CO intermediates. These and other data suggest that association of DSB-2 with chromatin is an indicator of competence for DSB formation, and that cells respond to a deficit of CO-competent recombination intermediates by prolonging the DSB-competent state. In the context of this model, we propose that formation of sufficient CO-competent intermediates engages a negative feedback response that leads to cessation of DSB formation as part of a major coordinated transition in meiotic prophase progression. The proposed negative feedback regulation of DSB formation simultaneously (1) ensures that sufficient DSBs are made to guarantee CO formation and (2) prevents excessive DSB levels that could have deleterious effects. 相似文献
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Huntington’s disease (HD) is a devastating dominantly inherited neurodegenerative disorder caused by an abnormal polyglutamine expansion in the N-terminal part of the huntingtin (HTT) protein. HTT is a large scaffold protein that interacts with more than a hundred proteins and is probably involved in several cellular functions. The mutation is dominant, and is thought to confer new and toxic functions to the protein. However, there is emerging evidence that the mutation also alters HTT’s normal functions. Therefore, HD models need to recapitulate this duality if they are to be relevant. Drosophila melanogaster is a useful in vivo model, widely used to study HD through the overexpression of full-length or N-terminal fragments of mutant human HTT. However, it is unclear whether Drosophila huntingtin (DmHTT) shares functions similar to the mammalian HTT. Here, we used various complementary approaches to analyze the function of DmHTT in fast axonal transport. We show that DmHTT interacts with the molecular motor dynein, associates with vesicles and co-sediments with microtubules. DmHTT co-localizes with Brain-derived neurotrophic factor (BDNF)-containing vesicles in rat cortical neurons and partially replaces mammalian HTT in a fast axonal transport assay. DmHTT-KO flies show a reduced fast axonal transport of synaptotagmin vesicles in motoneurons in vivo. These results suggest that the function of HTT in axonal transport is conserved between flies and mammals. Our study therefore validates Drosophila melanogaster as a model to study HTT function, and its dysfunction associated with HD. 相似文献
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Kelsey J. R. P. Byers Kathy Darragh Jamie Musgrove Diana Abondano Almeida Sylvia Fernanda Garza Ian A. Warren Pasi M. Rastas Marek Kučka Yingguang Frank Chan Richard M. Merrill Stefan Schulz W. Owen McMillan Chris D. Jiggins 《Evolution; international journal of organic evolution》2020,74(2):349-364
Understanding the production, response, and genetics of signals used in mate choice can inform our understanding of the evolution of both intraspecific mate choice and reproductive isolation. Sex pheromones are important for courtship and mate choice in many insects, but we know relatively little of their role in butterflies. The butterfly Heliconius melpomene uses a complex blend of wing androconial compounds during courtship. Electroantennography in H. melpomene and its close relative Heliconius cydno showed that responses to androconial extracts were not species specific. Females of both species responded equally strongly to extracts of both species, suggesting conservation of peripheral nervous system elements across the two species. Individual blend components provoked little to no response, with the exception of octadecanal, a major component of the H. melpomene blend. Supplementing octadecanal on the wings of octadecanal-rich H. melpomene males led to an increase in the time until mating, demonstrating the bioactivity of octadecanal in Heliconius. Using quantitative trait locus (QTL) mapping, we identified a single locus on chromosome 20 responsible for 41% of the parental species’ difference in octadecanal production. This QTL does not overlap with any of the major wing color or mate choice loci, nor does it overlap with known regions of elevated or reduced FST. A set of 16 candidate fatty acid biosynthesis genes lies underneath the QTL. Pheromones in Heliconius carry information relevant for mate choice and are under simple genetic control, suggesting they could be important during speciation. 相似文献
128.
Culver Mvumi Elizabeth Ngadze Diana Marais Elsa S. duToit Jameson Kugara 《Archives Of Phytopathology And Plant Protection》2013,46(7-8):432-444
AbstractThe study investigates the presence and quantity of antimicrobial sinigrin glucosinolates in tomato leaves after spraying them with moringa (Moringa oleifera) leaf extract (MLAE). Moringa concentrates (0.5, 0.75, 1.00 and 1.5?kg?L?1 (w v?1)) were prepared. Distilled water was the control. Sampled tomato leaves were air-dried, freeze-dried and extracted firstly using pure methanol in a hot water bath and then pellet re-extracted using 5?mL of hot aqueous methanol (70% v v?1). An ion exchange column, and sulphatase was used to achieve glucosiodesulphonation. High performance liquid chromatography (HPLC) was employed in the identification and quantitative analysis of the sinigrin glucosinolates. Tomato (Solanum lycopersicum) leaves treated with MLAE revealed highly significant (p?<?.001) content of sinigrin glucosinolates. The sinigrin standard and the desulphated sinigrin glucosinolates had a 7?s retention time difference; 5?kg?L?1 (w v?1) resulted in a superior amount of sinigrin in tomato leaves as compared to all the other MLAE concentrations. The study reveals that spraying MLAE on putatively diseased tomato leaves donates specific quantifiable glucosinolates like sinigrin, which may be involved in defense against tomato diseases and, hence, recommends use of 5?kg?L?1 (w v?1) for the highest sinigrin defense tag. 相似文献
129.
Anna Maria Di Giacomo Luana Calabrò Riccardo Danielli Ester Fonsatti Erica Bertocci Isabella Pesce Carolina Fazio Ornella Cutaia Diana Giannarelli Clelia Miracco Maurizio Biagioli Maresa Altomonte Michele Maio 《Cancer immunology, immunotherapy : CII》2013,62(6):1021-1028