Biology subjects

Gu, B.

Publications and source records attributed to Gu, B..

3 recordsLinked to original sources

bioRxiv2018

YggG is a Novel SPI-1 Effector Essential for Salmonella Virulence

Salmonella is a leading cause of food borne illness and poses a major public health problem worldwide. Two type III secretion systems (TTSSs) are responsible for the delivery of a series of bacterial effectors into the infected cells to reprogram host cell functions to promote bacterial invasion and intracellular survival/replication. Nearly half of Salmonella genes encode proteins that are annotated as \"hypothetical\". We hypothesize that some of these hypothetical proteins might be TTSS effectors and participate in Salmonella virulence. In this study, we employed an in silico screen to identify putative TTSS effector proteins and performed a large scale screening of Salmonella effectors using a {beta}-lactamase protein translocation reporter assay. We identified 22 novel effectors that have not been previously reported. One of the effector - YggG, is found to be cytotoxic to mammalian cells when overexpressed suggesting interference with mammalian cell functions and survival. Importantly, Salmonella strains lacking YggG has reduced virulence in the mouse infection model. Our study demonstrated that YggG and its protease activity are required for Salmonella virulence in the mouse infection model. Surprisingly, no detectable roles in invasion into epithelial cells and no effect on the survival and replication inside cultured macrophages. We speculate that YggG may be involved in altering some aspects of the host immune system to promote infection. Our finding significantly expands the number of known Salmonella effectors, and laid a solid foundation in further understanding Salmonella pathogenesis.\n\nAbstract ImportanceSalmonellosis continues to be public health concern in the USA and the world. Salmonella delivers a set of bacterial proteins (effectors) into the host cells to invade non-phagocytic cells and to replicate inside the infected cells. Identification and characterization of these effectors are pivotal to the understanding of how Salmonella causes diseases. In addition, Nearly half of Salmonella genes encode proteins that are annotated as \"hypothetical\". We have identified 22 novel effectors that have not been previously reported. Our finding significantly expands the number of known Salmonella effectors, and laid a solid foundation in further understanding Salmonella pathogenesis.

microbiology↗

bioRxiv2017

Efficient generation of targeted large insertions in mouse embryos using 2C-HR-CRISPR

Rapid and efficient generation of large fragment targeted knock-in mouse models is still a major hurdle in mouse genetics. Here we developed 2C-HR-CRISPR, a highly efficient gene editing method based on introducing CRISPR reagents into mouse embryos at the 2-cell stage, taking advantage of the likely increase in HR efficiency during the long G2 phase and open chromatin structure of the 2-cell embryo. With 2C-HR-CRISPR and a modified biotin-streptavidin approach to localize repair templates to target sites, we rapidly targeted 20 endogenous genes that are expressed in mouse blastocysts with fluorescent reporters and generated reporter mouse lines. We showcase the first live triple-color blastocyst with all three lineages differentially reported. Additionally, we demonstrated efficient double targeting, enabling rapid assessment of the auxin-inducible degradation system for probing protein function in mouse embryos. These methods open up exciting avenues for exploring cell fate decisions in the blastocyst and later stages of development. We also suggest that 2C-HR-CRISPR can be a better alternative to random transgenesis by ensuring transgene insertions at defined safe harbor sites.

genetics↗

bioRxiv2017

Carbon pool trends and dynamics within a subtropical peatland during long-term restoration

BackgroundThe Florida Everglades has undergone significant ecological change spanning the continuum of disturbance to restoration. While the restoration effort is not complete and the ecosystem continues to experience short duration perturbations, a better understanding of long-term C dynamics of the Everglades is needed to facilitate new restoration efforts. This study evaluated temporal trends of different aquatic carbon (C) pools of the northern Everglades Protection Area over a 20-year period to gauge historic C cycling patterns. Dissolved inorganic C (DIC), dissolved organic C (DOC), particulate organic C (POC), and surface water carbon dioxide (pCO2(aq)) were investigated between May 1, 1994 and April 30, 2015.\n\nResultsAnnual mean concentrations of DIC, DOC, POC, and pCO2(aq) significantly decreased through time or remained constant across the Water Conservation Areas (WCAs). Overall, the magnitude of the different C pools in the water column significantly differed between regions. Outgassing of CO2 was dynamic across the Everglades ranging from 420 to 2001 kg CO2 yr-1. Overall the historic trend in CO2 flux from the marsh declined across our study area while pCO2(aq) largely remained somewhat constant with the exception of Water Conservation Area 2 which experienced significant declines in pCO2(aq). Particulate OC concentrations were consistent between WCAs, but a significantly decreasing trend in annual POC concentrations were observed.\n\nConclusionsHydrologic condition and nutrient inputs significantly influenced the balance, speciation, and flux of C pools across WCAs suggesting a subsidy-stress response in C dynamics relative to landscape scale responses in nutrient availability. The interplay between nutrient inputs and hydrologic condition exert a driving force on the balance between DIC and DOC production via the metabolism of organic matter which forms the base of the aquatic foodweb. Along the restoration trajectory as water quality and hydrology continues to improve it is expected that C pools will respond accordingly.

ecology↗