Rapid improvement of rice eating and cooking quality through gene editing toward glutelin as target

Rice eating and cooking quality (ECQ) is a major concern of breeders and consumers, determining market competitiveness worldwide. Rice grain protein content (GPC) is negatively related to ECQ, making it possible to improve ECQ by manipulating GPC. However, GPC is genetically complex and sensitive to environmental conditions; therefore, little progress has been made in traditional breeding for ECQ. Here, we report that CRISPR/Cas9-mediated knockout of genes encoding the grain storage protein glutelin rapidly produced lines with downregulated GPC and improved ECQ. Our finding provides a new strategy for improving rice ECQ.     

Structure of the tetragonal surface virulence array protein and gene of Aeromonas salmonicida

The paracrystalline surface protein array of the pathogenic bacterium Aeromonas salmonicida is a primary virulence factor with novel binding capabilities. The species-specific structural gene (vapA) for this array protein (A-protein) was cloned into lambda gt11 but was unstable when expressed in Escherichia coli, undergoing an 816-base pair deletion due to a 21-base pair direct repeat within the gene. However, the gene was stable in cosmid pLA2917 as long as expression was poor. A-protein was located in the cytoplasmic, inner membrane and periplasmic fractions in E. coli. The DNA sequence revealed a 1,506-base pair open reading frame encoding a protein consisting of a 21-amino acid signal peptide, and a 481-residue 50,778 molecular weight protein containing considerable secondary structure. When assembled into a paracrystalline protein array on Aeromonas the cell surface A-protein was totally refractile to cleavage by trypsin, but became trypsin sensitive when disassembled. Trypsin cleavage of the isolated protein provided evidence that both the NH2- and COOH-terminal regions form distinct structural domains, consistent with three-dimensional ultrastructural evidence. The NH2-terminal 274-residue domain remained refractile to trypsin activity. This segment connects by a trypsin and CNBr-sensitive 78-residue linker region to a COOH-terminal 129-residue fragment which could apparently refold into a partially trypsin-resistant structure after cleavage at residue 323.     

Suppressor T cell growth and differentiation: production of suppressor T cell differentiation factor by the murine thymoma BW5147

Previous studies have identified a lymphokine, termed Ts differentiation factor (TsDF), in primary MLR supernatants that induces effector function of alloantigen-primed MLR-Ts. The present report describes constitutive production of TsDF by the murine thymoma BW5147, and its use to analyze alloantigen and TsDF requirements for MLR-Ts activation to TsF production. Serum-free supernatants of BW5147 restored the capacity of MLR-TsF production to alloantigen-primed MLR-Ts cultured with glutaraldehyde-fixed allogeneic stimulator cells, and were not themselves directly suppressive in the MLR assay. BW5147 supernatant induced MLR-TsF production from primed L3T4-Ly2+ MLR-Ts in the absence of concomitant proliferation, suggesting that the function of BW5147 supernatant, like that of MLR-derived TsDF, is a differentiative rather than a proliferative one, and is required for the synthesis or release of TsF. The differentiative activity of BW5147 supernatant was associated with a molecular species of approximately 14,500 m.w. by HPLC fractionation and was expressed independently of detectable IL 2, IL 3, IFN-gamma, and IL 1. The functional activity of BW5147 supernatant has therefore been provisionally designated BW5147-derived Ts differentiative factor, or BW-TsDF. By using BW-TsDF, it was demonstrated that MLR-Ts fail to respond to TsDF in the absence of, or preceding, reexposure to priming alloantigen. Instead, alloantigen binding by primed MLR-Ts appears to create a transient state of TsDF responsiveness. Primed MLR-Ts were fully sensitive to delayed addition of TsDF for approximately 12 hr after reexposure to alloantigen, but became TsDF-unresponsive within 24 to 36 hr. MLR-Ts cultured alone for 36 hr were fully responsive to the combined addition of TsDF and alloantigen. Thus, MLR-Ts activation to TsF release requires the sequential events of specific alloantigen binding, which induces a TsDF-responsive state, followed by interaction with TsDF. The transience of induced TsDF responsiveness suggests a precise mechanism for control of antigen-initiated Ts activation to effector function.     

Brain Metabolism and Intracellular pH During Ischaemia and Hypoxia: An In Vivo 31P and 1H Nuclear Magnetic Resonance Study in the Lamb

Brain metabolism and intracellular pH were studied during and after episodes of ischaemia and hypoxia-ischaemia in lambs anaesthetised with sodium pentobarbitone. 31P and 1H magnetic resonance spectroscopy methods were used to monitor brain pHi and brain concentrations of Pi, phosphocreatine (PCr), beta--nucleoside triphosphate (beta NTP), and lactate. Simultaneous measurements were made of cerebral blood flow and cerebral oxygen and glucose consumption. Cerebral ischaemia sufficient to reduce oxygen delivery to 75% of control values was associated with a fall in brain pHi and increase in brain Pi. Progressively severe hypoxia-ischaemia was associated with a progressive fall in brain pHi, PCr, and beta NTP and increase in brain Pi. In two animals the increase in brain lactate during hypoxia-ischaemia measured by 1H nuclear magnetic resonance (NMR) could be quantitatively accounted for by the increased net uptake of glucose by the brain in relation to oxygen, but was insufficient to account for the concomitant acidosis according to previous estimates of brain buffering capacity. In four animals brain pHi, PCr, Pi, and beta NTP had returned to normal 1 h after the hypoxic-ischaemic episode. In one animal brain pHi had reverted to normal at a time when 1H NMR indicated persistent elevation of brain lactate.     

Effect of hyperthermia on intracellular pH in Chinese hamster ovary cells

Chinese hamster ovary cells were heated at 45.5 or 43.0 degrees C at acidic pH (6.7) or normal physiological pH (7.4) to have a survival of 10(-3). The weak acid, 5,5-dimethyl-2,4-oxazolidinedione-2-14C), was used to measure the intracellular pH (pHi) both during and following hyperthermia. Tritiated water and a Particle Data machine were used to measure cellular volume as well. With 99.9% of the cell population destined to die clonogenically, the physiologically alive cells, as determined by the exclusion of trypan blue dye, maintained their pH differential between pHe and pHi as well as unheated cells. Furthermore, the cell's ability to regulate its pHi in response to changes in pHe was not affected by the same hyperthermic treatment. However, cellular volume decreased by 15-30% by 5 h after the onset of heat treatment. We conclude that heat does not perturb the cellular regulation of intracellular H+ concentration. Therefore, there is no thermal damage to the pHi-regulatory mechanism that could be responsible for either heat-induced reproductive cell death or low pH sensitization of heat killing.