Antifungal properties of selected lactic acid bacteria and application in the biological control of ochratoxin A producing fungi during cocoa fermentation

Thirteen Lactic acid bacteria strains isolated from fermenting cocoa and seven reference strains were used in order to assess their antifungal properties towards three ochratoxin A (OTA) producing fungi (Aspergillus carbonarius, Aspergillus niger and Aspergillus ochraceus). Furthermore, two of the isolates strains (A19 and A21) identified as belonging to the genus of Pediococcus as well as Lactobacillus plantarum B4496, Lactobacillus brevis 207 and Lactobacillus sanfranciscensis BB12 showed interesting in vitro broad antifungal activities towards the three ochratoxin-producing fungi with inhibition percentages ranging from 15% to 66.7%. Treatment of cell-free supernatant at 100°C affected antifungal activity suggesting that the main compounds responsible for this activity were of proteic nature, and hence could be bacteriocins. Application of isolate A19 in cocoa fermentation as starter inhibited the growth of each of the OTA-producing species. At the end of fermentation in boxes inoculated with A19, A. niger was not detectable while A. carbonarius concentration was found to be 2 Log CFU/g of wet beans. The assessment of the ochratoxin produced during fermentation of cocoa inoculated with A. carbonarius indicated that the use of isolate A19 as starter could reduce their level of growth so as to have only a toxin production of 0.0012 ± 0.0005 μg/kg after 40 days of storage, while this was 2.45 ± 0.35 μg/kg of fermented and dried cocoa beans in the absence of A19. This work is a contribution for the application of biological control of OTA-producing fungi during cocoa production.     

网络成瘾者奖赏系统和认知控制系统的神经机制

网络成瘾作为一种行为成瘾,已成为严重影响人们心理健康的全球性问题.根据大脑发育的神经生物模型,揭示网络成瘾者奖赏和认知控制系统的神经机制是解决网络成瘾问题的关键,也是心理学研究的重大问题.行为研究探讨了网络成瘾具有高奖赏寻求和低认知控制特征;神经机制研究揭示了奖赏和认知控制系统的缺陷是网络成瘾行为的高风险因素;与药物成瘾的比较研究发现,网络成瘾有着独特的奖赏机制.这些研究深化了对网络成瘾心理和神经机制的理解,但仍存在网络成瘾筛查和入组标准不科学、分型笼统、因果研究匮乏、干预和治疗效果具有争议、研究范式存在漏洞等一些急需解决的问题.     

医院疾病资源库标准化建设探讨

疾病资源库在转化医学发展中发挥着重要作用,收集人类遗传资源和疾病相关资源信息,建设疾病资源库越来越受到重视。首都医科大学附属北京佑安医院在建设乙型肝炎和艾滋病疾病资源库的过程中,总结疾病资源库建设经验,为中国疾病资源库建设的标准化提供参考。     

Effect of phorid fly density on the foraging of Atta vollenweideri leafcutter ants in the field

Leafcutter ants in the genus Atta (Hymenoptera: Formicidae: Attini) are considered major pests of agriculture and forestry in the Neotropics. Phorid flies (Diptera: Phoridae) have been proposed as viable candidates for biological control of ants because of the importance of their trait‐mediated effects on their hosts. However, the impact of different densities of phorid flies has never been assessed in the field. Experiments were conducted by isolating 3‐m sections of Atta vollenweideri Forel foraging trails with tunnels, and sampling ants in trails with 0, 1, or 4 Eibesfeldtphora trilobata Disney female parasitoid flies. Samples were collected every 30 min from these trails. We also collected a sample before introducing the parasitoids and another one 30 min after removing them from the trail. We measured traffic of ants on the trails, weight and type of plant material transported, and the proportion and size of the workers collected. The presence of phorids on the trails reduced the ant traffic and amount of plant material transported into the nests and decreased the proportion of workers on the trails in the size range preferred as hosts by the flies. The effect on worker size, as well as the lag effect recorded after phorids were removed from the tunnels, was more pronounced with four phorids. The presence of phorids also affected the weight of monocotyledon and dicotyledon material transported. Even at the minimum density possible, phorids significantly influenced a key aspect of the colony life, the food intake through foraging. From an applied point of view, our results show that releases of these phorids into the field should not necessarily involve many individuals to reduce foraging by A. vollenweideri, making them potentially useful candidates for biological control of these ants.     

Effects of three endophytic entomopathogens on sweet sorghum and on the larvae of the stalk borer Sesamia nonagrioides

Various endophytic fungi of native plants and crops are important entomopathogens. The objective of this study was to investigate the entomopathogenic action of Beauveria bassiana (Balsamo) Vuillemin, Metarhizium robertsii (Metchnikoff) Sorokin, and Isaria fumosorosea (Wize) Brown & Smith (all Ascomycota: Hypocreales) against larvae of Sesamia nonagrioides (Lefebvre) (Lepidoptera: Noctuidae) artificially introduced into Sorghum bicolor L. (Moench) (Poaceae) plants under natural environmental conditions. Sorghum bicolor is an economically important crop cultivated for grain, fiber, forage, and lately for biofuel, and S. nonagrioides is its main pest in Mediterranean areas. Young sorghum plants were inoculated with the entomopathogens by spraying in the field. Plant water status, chlorophyll concentration, photosynthesis, and transpiration were not affected. Thirty days after endophyte establishment, plants were infested with fourth instars of S. nonagrioides. The endophytes prevented 50–70% of larvae from entering stalks. Larval mortality was 70–100% and tunnel lengths were reduced by 60–87%. Larval infestation resulted in reduced electron transport capacity and net photosynthetic rate, which was ameliorated in the presence of I. fumosorosea and reversed by B. bassiana and M. robertsii. The growth of sorghum was unaffected in all treatments during the experimental period. Beauveria bassiana and M. robertsii can protect sweet sorghum from damage induced by S. nonagrioides under natural environmental conditions without affecting plant physiology and growth.     

Intramolecular Binding of the Rad9 C Terminus in the Checkpoint Clamp Rad9-Hus1-Rad1 Is Closely Linked with Its DNA Binding

The human checkpoint clamp Rad9-Hus1-Rad1 (9-1-1) is loaded onto chromatin by its loader complex, Rad17-RFC, following DNA damage. The 120-amino acid (aa) stretch of the Rad9 C terminus (C-tail) is unstructured and projects from the core ring structure (CRS). Recent studies showed that 9-1-1 and CRS bind DNA independently of Rad17-RFC. The DNA-binding affinity of mutant 9^ΔC-1-1, which lacked the Rad9 C-tail, was much higher than that of wild-type 9-1-1, suggesting that 9-1-1 has intrinsic DNA binding activity that manifests in the absence of the C-tail. C-tail added in trans interacted with CRS and prevented it from binding to DNA. We narrowed down the amino acid sequence in the C-tail necessary for CRS binding to a 15-aa stretch harboring two conserved consecutive phenylalanine residues. We prepared 9-1-1 mutants containing the variant C-tail deficient for CRS binding, and we demonstrated that the mutant form restored DNA binding as efficiently as 9^ΔC-1-1. Furthermore, we mapped the sequence necessary for TopBP1 binding within the same 15-aa stretch, demonstrating that TopBP1 and CRS share the same binding region in the C-tail. Indeed, we observed their competitive binding to the C-tail with purified proteins. The importance of interaction between 9-1-1 and TopBP1 for DNA damage signaling suggests that the competitive interactions of TopBP1 and CRS with the C-tail will be crucial for the activation mechanism.     

Comparative pattern of genetic structure in two Mediterranean killifishes Aphanius fasciatus and Aphanius iberus inferred from both mitochondrial and nuclear data

In this study, genetic variation was assessed in Aphanius fasciatus and Aphanius iberus characterized by similar ecological traits but with very different distribution ranges in the Mediterranean area. Five populations of A. iberus and five of A. fasciatus were analysed using five polymorphic microsatellite loci and partial mitochondrial control region (D‐loop) sequences. Congruent results were found with both nuclear and mitochondrial molecular markers. The results showed that similar levels of genetic divergence, based on mitochondrial control region sequences, are present among populations of A. iberus and among populations of A. fasciatus despite the very different geographic distance existing among the examined populations of the two species (low geographic distance in A. iberus and high in A. fasciatus). A possible explanation could be that the populations of A. iberus were isolated for a longer time than the populations of A. fasciatus supporting the hypothesis that the split in the lineage leading to A. iberus is older than the split in the lineage leading to A. fasciatus. The possibility that the wide circum‐Mediterranean distribution of A. fasciatus ensures the high connectivity of its populations, preventing, in some cases, local differentiation, however, cannot be ruled out.