Polymorphism analysis and supertype definition of swine leukocyte antigen class I molecules in three-way crossbred (Landrace,Duroc, and Yorkshire) pigs: implications for the vaccine development of African swine fever virus

正Dear Editor,Swine major histocompatibility complex (MHC) is a highly polymorphic gene in pigs and is also called swine leukocyte antigen (SLA)(Fan et al., 2018). SLA is divided into three major categories, SLA Ⅰ (SLA-1,-2,-3), SLA Ⅱ, and SLA Ⅲ(Smith et al., 2005). SLA Ⅰ plays an important role in cellular immunity which can eliminate viruses and other foreign     

水稻根系遗传育种研究进展

根系作为水稻(Oryza sativa)植株的重要组成部分, 在水稻生长发育过程中发挥多种作用, 包括植物的固定、水分和营养物质的获取以及氨基酸和激素的生物合成等, 其形态结构和生理功能与水稻产量和稻米品质以及抗性等密切相关。目前, 通过遗传及生化等诸多手段, 已挖掘到较多水稻根系QTLs与控制基因。该文综述了水稻根系QTL和基因的研究进展, 并对未来根系研究进行展望, 以期为进一步克隆水稻根系基因和完善水稻理想株型模型提供参考。     

Elevated intracellular cyclic-di-GMP level in Shewanella oneidensis increases expression of c-type cytochromes

Electrochemically active biofilms are capable of exchanging electrons with solid electron acceptors and have many energy and environmental applications such as bioelectricity generation and environmental remediation. The performance of electrochemically active biofilms is usually dependent on c-type cytochromes, while biofilm development is controlled by a signal cascade mediated by the intracellular secondary messenger bis-(3ʹ-5ʹ) cyclic dimeric guanosine monophosphate (c-di-GMP). However, it is unclear whether there are any links between the c-di-GMP regulatory system and the expression of c-type cytochromes. In this study, we constructed a S. oneidensis MR-1 strain with a higher cytoplasmic c-di-GMP level by constitutively expressing a c-di-GMP synthase and it exhibited expected c-di-GMP-influenced traits, such as lowered motility and increased biofilm formation. Compared to MR-1 wild-type strain, the high c-di-GMP strain had a higher Fe(III) reduction rate (21.58 vs 11.88 pM of Fe(III)/h cell) and greater expression of genes that code for the proteins involved in the Mtr pathway, including CymA, MtrA, MtrB, MtrC and OmcA. Furthermore, single-cell Raman microspectroscopy (SCRM) revealed a great increase of c-type cytochromes in the high c-di-GMP strain as compared to MR-1 wild-type strain. Our results reveal for the first time that the c-di-GMP regulation system indirectly or directly positively regulates the expression of cytochromes involved in the extracellular electron transport (EET) in S. oneidensis, which would help to understand the regulatory mechanism of c-di-GMP on electricity production in bacteria.     

Quorum sensing regulation confronts the development of a viable but non-culturable state in Vibrio cholerae

Vibrio cholerae can enter a viable but non-culturable (VBNC) state when it encounters unfavourable environments; VBNC cells serve as important reservoirs and still pose threats to public health. The genetic regulation of V. cholerae entering its VBNC state is not well understood. Here, we show a confrontation strategy adapted by V. cholerae O1 in which it utilizes a quorum sensing (QS) system to prevent transition into a VBNC state under low nutrition and temperature conditions. The upregulation of hapR resulted in a prolonged culturable state of V. cholerae in artificial sea water at 4°C, whereas the mutation of hapR led to fast entry into the VBNC state. We also observed that different V. cholerae O1 natural isolates with distinct QS functions present a variety of abilities to maintain culturability during the transition to a VBNC state. The strain groups with higher or constitutive expression of QS genes exhibit a greater tendency to maintain the culturable state during VBNC induction than those lacking QS functional groups. In summary, HapR-mediated QS regulation is associated with the transition to the VBNC state in V. cholerae. HapR expression causes V. cholerae to resist VBNC induction and become dominant over competitors in changing environments.