Robust crossover assurance and regulated interhomolog access maintain meiotic crossover number

Most organisms rely on interhomolog crossovers (COs) to ensure proper meiotic chromosome segregation but make few COs per chromosome pair. By monitoring repair events at a defined double-strand break (DSB) site during Caenorhabditis elegans meiosis, we reveal mechanisms that ensure formation of the obligate CO while limiting CO number. We find that CO is the preferred DSB repair outcome in the absence of inhibitory effects of other (nascent) recombination events. Thus, a single DSB per chromosome pair is largely sufficient to ensure CO formation. Further, we show that access to the homolog as a repair template is regulated, shutting down simultaneously for both CO and noncrossover (NCO) pathways. We propose that regulation of interhomolog access limits CO number and contributes to CO interference.     

罗马尼亚不同沙棘品种叶中甘树脂的提取

沙棘（Hippophae rhamnoides）是一种可广泛生长于欧亚地区,包括罗马尼亚的小果实灌木。沙棘具有药用及营养价值,同时可以改善区域的微气候环境。人们已经研究了罗马尼亚沙棘的生物化学组分及相关数据,所以我们分析了不同沙棘叶的甘树脂,一个重要的生化参数可以为植株的一项基本新陈代谢——光合作用提供信息。结果表明根据品种及特定环境因素的不同,产生了多样性。     

Antigenic profiles of recombinant proteins from Mycobacterium avium subsp. paratuberculosis in sheep with Johne's disease

Methods to improve the ELISA test to detect Mycobacterium avium subsp. paratuberculosis have been explored over several years. Previously, selected recombinant proteins of M. avium subspecies paratuberculosis were found to be immunogenic in cattle with Johne's disease. In the present study, antibody responses of infected and healthy sheep were evaluated using 18 purified recombinant proteins in an ELISA-based format for the serodiagnosis of ovine paratuberculosis. These selected recombinant proteins represent heat shock proteins, hypothetical proteins and cell surface proteins of M. avium subsp. paratuberculosis. Whereas, Map0862 (a gene uniquely present in M. avium subspecies paratuberculosis) and Map3786 encoded protein solicited the strongest antibody response in infected sheep. The protein encoded by Map2116c showed the weakest antibody response among the animals tested. Although none of the recombinant proteins detected all 11 infected sheep singly, antibodies to Map0862 were detected in 9 of 11 (81%) infected sheep. Furthermore, ovine responses to these selected antigens were assessed temporally over the course of 1 year during which we found a spiking effect rather than an incremental increase of antibody reactivity. This study evaluated multiple M. avium subsp. paratuberculosis recombinant proteins in an ELISA-based format for sheep.     

Biodegradation and Detoxification Efficiency of Azo-Dye Reactive Orange 16 by <Emphasis Type="Italic">Pichia kudriavzevii</Emphasis> CR-Y103

In consideration of the hazards associated with the presence of the textile azo-dye and their biotransformation products in the environment, the goal of this work was to study bioremediation process by the yeast strain Pichia kudriavzevii CR-Y103 related to the ability to degrade and detoxify the sulfonated Reactive Orange 16 azo-dye. In experimental conditions, the optimal inoculum/dye concentration ratio required for complete decolorization (100%) of culture medium and biomass within 24 h has been 1 g L^?1 yeast cell (dry weight)/50 mg L^?1 Reactive Orange 16. In the presence of 400 mg L^?1 of Reactive Orange 16 (RO16), 95% of the dye was removed after 72 h of incubation. Also, the yeast strain could decolorize other eight textile dyes (56.48–99.98% decolorization within 24 h). NADH-DCIP reductase and azo reductase activities were significantly increased (ca. 5.4 times and ca. 37 times, respectively) during the decolorization process. UV-VIS spectra, high-performance liquid chromatography (HPLC), and Fourier transform infrared spectroscopy (FTIR) analysis confirmed the presence of new biotransformation products in extracted metabolites, highlighting the partial biodegradation of the dye by the new yeast isolate. The phytotoxicity evaluation strongly supported the decreased toxicity of biodegraded products as minor inhibition on germination (%), root and shoots elongation of T. pratense L. and T. aestivum L. seedlings. Increasing of mitotic index value and decreasing the frequency of chromosomal aberrations in tested plant meristem cells treated with biodegraded products, compared with RO16 treatment (500 ppm), confirmed their slightly toxic nature. A cell viability assay also confirmed the reduced toxicity of biodegraded products on healthy monkey kidney cells (Vero cells).