Whole Genome Sequence Analysis of Lactiplantibacillus Plantarum Bacteriophage P2

Phage P2 was isolated from failed fermentation broth carried out by Lactiplantibacillus plantarum IMAU10120. A previous study in our laboratory showed that this phage belonged to the Siphoviridae family. In this study, this phage’s genomic characteristics were analyzed using whole-genome sequencing. It was revealed that phage P2 was 77.9 kb in length and had 39.28% G + C content. Its genome included 96 coding sequences (CDS) and two tRNA genes involved in the function of the structure, DNA replication, packaging, and regulation. Phage P2 had higher host specificity; many tested strains were not infected. Cell wall adsorption experiments showed that the adsorption receptor component of phage P2 might be a part of the cell wall peptidoglycan. This research might enrich the knowledge about genomic information of lactobacillus phages and provide some primary data to establish phage control measures.     

Effect of AMPA on Cerebral Cortical Oxygen Balance of Ischemic Rat Brain

We tested the hypothesis that the excitatory neurotransmitter receptor agonist, alpha amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA), would worsen cerebral cortical oxygen supply/consumption balance during focal ischemia. In this study, we compared regional cerebral blood flow, arterial and venous O₂ saturation, O₂ extraction and oxygen consumption of ischemic and AMPA treated ischemic and control regions of rat brain. Ischemia was induced by middle cerebral artery (MCA) occlusion in isoflurane (1.4%) anesthetized Wistar rats. Twenty minutes after MCA occlusion, 10^–5 M AMPA was applied to the ischemic cortex (IC) for a period of 40 min; the fluid was changed every 10 min. After 1 hr of ischemia, animals were sacrificed and regional cerebral blood flow (rCBF) was determined using the C¹⁴-iodoantipyrine autoradiographic technique. Regional arterial and venous oxygen saturation were determined microspectrophotometrically. In control, the cerebral blood flow and oxygen consumption of the IC were significantly lower than the contralateral cortex (rCBF: 46 ± 20 vs. 81 ± 39 ml/min/100g, O₂ consumption: 2.8 ± 1.4 vs. 3.6 ± 1.4 ml O₂/min/100g). 10^–5 M AMPA did not significantly alter regional cerebral blood flow and oxygen consumption of the IC, but did decrease the average venous O₂ saturation of the IC from 50.2 ± 3.9% to 46.7 ± 1.6%. AMPA also significantly increased the frequency of small veins with less than 45% O₂ saturation in the IC (8 out of 56 veins in IC vs. 18 out of 56 veins in AMPA treated IC). Thus, topical application of 10^–5 M AMPA to the ischemic area worsens cerebral O₂ balance and suggests that excitatory amino acids contribute to the degree of cerebral ischemia.     

A New Species of Holboellia from Gansu

One new species of Holboellia (Lardizabalaceae) is described from Gansu Province, China. It is Holboellia apetala Q. Xia, J. Z. Suen et Z. X. Peng.     

Newcastle disease virus-vectored rabies vaccine is safe, highly immunogenic, and provides long-lasting protection in dogs and cats

Effective, safe, and affordable rabies vaccines are still being sought. Newcastle disease virus (NDV), an avian paramyxovirus, has shown promise as a vaccine vector for mammals. Here, we generated a recombinant avirulent NDV La Sota strain expressing the rabies virus glycoprotein (RVG) and evaluated its potential to serve as a vaccine against rabies. The recombinant virus, rL-RVG, retained its high-growth property in chicken eggs, with titers of up to 10^9.8 50% egg infective doses (EID₅₀)/ml of allantoic fluid. RVG expression enabled rL-RVG to spread from cell to cell in a rabies virus-like manner, and RVG was incorporated on the surface of the rL-RVG viral particle. RVG incorporation did not alter the trypsin-dependent infectivity of the NDV vector in mammalian cells. rL-RVG and La Sota NDV showed similar levels of sensitivity to a neutralization antibody against NDV and similar levels of resistance to a neutralization antibody against rabies virus. Animal studies demonstrated that rL-RVG is safe in several species, including cats and dogs, when administered as multiple high doses of recombinant vaccine. Intramuscular vaccination with rL-RVG induced a substantial rabies virus neutralization antibody response and provided complete protection from challenge with circulating rabies virus strains. Most importantly, rL-RVG induced strong and long-lasting protective neutralization antibody responses to rabies virus in dogs and cats. A low vaccine dose of 10^8.3 EID₅₀ completely protected dogs from challenge with a circulating strain of rabies virus for more than a year. This is the first study to demonstrate that immunization with an NDV-vectored vaccine can induce long-lasting, systemic protective immunity against rabies.     

The cytosolic loop of the gamma-secretase component presenilin enhancer 2 protects zebrafish embryos from apoptosis

The gamma-secretase complex, composed of presenilin, presenilin enhancer 2 (Pen-2), nicastrin, and Aph-1, catalyzes the final cleavage of amyloid precursor protein to generate the toxic amyloid beta protein, the major component of plaques in the brains of Alzheimer disease patients. To understand the in vivo function of Pen-2, we used morphant technology available in zebrafish and transiently knocked down the expression of endogenous Pen-2 by injecting the morpholino (MO) against Pen-2. Two truncated Pen-2 proteins lacking either the cytosolic or the C-terminal domain were expressed in MO-injected embryos. This deletion analysis demonstrated that the Pen-2 cytosolic loop is essential for protecting developing embryos from caspase-dependent apoptosis caused by the reduction of Pen-2. Twelve amino acids in the C terminus of Pen-2 were dispensable and could not rescue the Pen-2 knockdown-induced apoptotic phenotype. Surprisingly, double knockdown of Pen-2 and nuclear factor kappaB component p65 abrogated the single Pen-2 MO-induced caspase activation, indicating that a previously reported pro-apoptotic role of NF-kappaB in some cell types could be manifested in a whole animal and that knockdown of Pen-2 may trigger pro-apoptotic activation of NF-kappaB.     

Synthetic Biology Toolkits for Metabolic Engineering of Cyanobacteria

Cyanobacteria are of great importance to Earth's ecology. Due to their capability in photosynthesis and C1 metabolism, they are ideal microbial chassis that can be engineered for direct conversion of carbon dioxide and solar energy into biofuels and biochemicals. Facilitated by the elucidation of the basic biology of the photoautotrophic microbes and rapid advances in synthetic biology, genetic toolkits have been developed to enable implementation of nonnatural functionalities in engineered cyanobacteria. Hence, cyanobacteria are fast becoming an emerging platform in synthetic biology and metabolic engineering. Herein, the progress made in the synthetic biology toolkits for cyanobacteria and their utilization for transforming cyanobacteria into microbial cell factories for sustainable production of biofuels and biochemicals is outlined. Current techniques in heterologous gene expression, strategies in genome editing, and development of programmable regulatory parts and modules for engineering cyanobacteria towards biochemical production are discussed and prospected. As cyanobacteria synthetic biology is still in its infancy, apart from the achievements made, the difficulties and challenges in applying and developing genetic toolkits in cyanobacteria for biochemical production are also evaluated.