Sigma E Regulators Control Hemolytic Activity and Virulence in a Shrimp Pathogenic Vibrio harveyi

Members of the genus Vibrio are important marine and aquaculture pathogens. Hemolytic activity has been identified as a virulence factor in many pathogenic vibrios including V. cholerae, V. parahaemolyticus, V. alginolyticus, V. harveyi and V. vulnificus. We have used transposon mutagenesis to identify genes involved in the hemolytic activity of shrimp-pathogenic V. harveyi strain PSU3316. Out of 1,764 mutants screened, five mutants showed reduced hemolytic activity on sheep blood agar and exhibited virulence attenuation in shrimp (Litopenaeus vannamei). Mutants were identified by comparing transposon junction sequences to a draft of assembly of the PSU3316 genome. Surprisingly none of the disrupted open reading frames or gene neighborhoods contained genes annotated as hemolysins. The gene encoding RseB, a negative regulator of the sigma factor (σE), was interrupted in 2 out of 5 transposon mutants, in addition, the transcription factor CytR, a threonine synthetase, and an efflux-associated cytoplasmic protein were also identified. Knockout mutations introduced into the rpoE operon at the rseB gene exhibited low hemolytic activity in sheep blood agar, and were 3-to 7-fold attenuated for colonization in shrimp. Comparison of whole cell extracted proteins in the rseB mutant (PSU4030) to the wild-type by 2-D gel electrophoresis revealed 6 differentially expressed proteins, including two down-regulated porins (OmpC-like and OmpN) and an upregulated protease (DegQ) which have been associated with σE in other organisms. Our study is the first report linking hemolytic activity to the σE regulators in pathogenic Vibrio species and suggests expression of this virulence-linked phenotype is governed by multiple regulatory pathways within the V. harveyi

Manganese Superoxide Dismutase: Guardian of the Powerhouse

The mitochondrion is vital for many metabolic pathways in the cell, contributing all or important constituent enzymes for diverse functions such as β-oxidation of fatty acids, the urea cycle, the citric acid cycle, and ATP synthesis. The mitochondrion is also a major site of reactive oxygen species (ROS) production in the cell. Aberrant production of mitochondrial ROS can have dramatic effects on cellular function, in part, due to oxidative modification of key metabolic proteins localized in the mitochondrion. The cell is equipped with myriad antioxidant enzyme systems to combat deleterious ROS production in mitochondria, with the mitochondrial antioxidant enzyme manganese superoxide dismutase (MnSOD) acting as the chief ROS scavenging enzyme in the cell. Factors that affect the expression and/or the activity of MnSOD, resulting in diminished antioxidant capacity of the cell, can have extraordinary consequences on the overall health of the cell by altering mitochondrial metabolic function, leading to the development and progression of numerous diseases. A better understanding of the mechanisms by which MnSOD protects cells from the harmful effects of overproduction of ROS, in particular, the effects of ROS on mitochondrial metabolic enzymes, may contribute to the development of novel treatments for various diseases in which ROS are an important component

Environmental effects of ozone depletion, UV radiation and interactions with climate change : UNEP Environmental Effects Assessment Panel, update 2017

Peer reviewe

Genetic Management of Virus Diseases in Peanut

Peanut, also known as groundnut (Arachis hypogaea L.) is a major oilseed crop in the world. About 31 viruses representing 14 genera are reported to naturally infe.ct peanut in different parts of the world, although only a few of these are of economic importance. These include groundnutrosette disease in Africa, tomato spotted wilt-disease in the United States, peanut bud necrosis disease in south Asia, and peanut stripe virus disease in east and southeast Asia. Cucumber mosaic virus disease in China and Argentina and peanut stem necrosis disease in certain -pockets in southern India are also economically important. Host plant resistance provides the most effective and economic option to manage virus diseases. However, for many virus diseases, effective resistance gene(s) in cultivated peanut have not been identified. With a few exceptions, the virus resistance breeding work has received little attention in peanut improvement programs. Transgenic resistance offers another option in virus resistance breeding. This review focuses on the status of genetic resistance to various economically important groundnut viruses and'use of transgenic-technology for the improvement of virus resistance

"Matching with Myopic and Farsighted Players"

We study stable sets for marriage problems under the assumption that players can be both myopic and farsighted. We introduce the new notion of the myopic-farsighted stable set. For the special cases where all players are myopic and where all players are farsighted, our concept predicts the set of matchings in the core. When all men are myopic and the top choice of each man is a farsighted woman, we show that the singleton consisting of the woman-optimal stable matching is a myopic-farsighted stable set. The same result holds when all women are farsighted