Bacterial blight (BB), which is caused by Xanthomonas oryzae pv. oryzae (Xoo), is one of the most important rice diseases in Asian countries. Developing resistant rice hybrids and cultivars is the most effective and economical strategy for controlling bacterial disease. In this study, a novel dominant gene Xa39, which confers broad-spectrum resistance for BB, was introgressed into two rice restorer lines H6X6 and H6X11 by a marker-assisted introgression breeding approach, combined with artificial inoculation with five Xoo and rigorous phenotypic selections. Finally, the two restorer lines H6X6-Xa39 and H6X11-Xa39 carrying a broader spectrum of BB resistance were developed. H6X6-Xa39, H6X11-Xa39, and their hybrid combinations with three sterile lines exhibited the same level of resistance as that of resistant donor FF329. The newly developed BB-resistant restorers and their derived hybrids with sterile lines were mostly identical to their respective original versions for agronomic traits, suggesting considerable value of the Xa39 gene in breeding BB resistance for genetic improvement of hybrid rice. Our results provide important reference information for the utilization of the Xa39 gene in rice breeding program.

为明确热处理对胶原蛋白三螺旋结构域的影响,采用红外光谱分析了胶原蛋白在脱水和水溶液两种加热环境下的结构变化规律.结果 表明,脱水和水溶液两种加热环境下,胶原蛋白二级结构含量变化规律相同,溶液状态下胶原蛋白对温度更加敏感;随温度的升高,其主要吸收峰发生迁移,三螺旋结构解旋,α-螺旋含量降低,无规则卷曲含量增加,分子结构逐渐舒展,无序性增大.二维红外相关光谱结果表明,脱水和水溶液两种加热环境下,胶原蛋白基团对温度的响应顺序不同,脱水加热时,脯氨酸CH3基团摇摆振动先作出响应,而水溶液加热时,N-H弯曲振动先作出响应.

胶原蛋白是动物体内含量最丰富的蛋白质,独特的三螺旋结构和氨基酸组成使其具备独特的理化特性和生物学特性,被广泛应用于食品、皮革、制药和组织工程等领域.然而,由于胶原蛋白对热敏感,加热时易发生热变性,三螺旋结构被破坏,其特性随之改变,因此,了解胶原蛋白的热稳定性机理及调控措施对胶原蛋白的开发与应用极其重要.本文介绍了胶原蛋白的结构特征,归纳了近年来胶原蛋白热稳定性的研究进展和研究手段,重点综述影响胶原蛋白热稳定性的因素,探讨未来胶原蛋白热稳定性研究的重点和方向,以期为胶原蛋白热稳定性研究与应用提供参考和指导.

Collagen, as the most abundant structural protein in living bodies, constitutes approximately 30% of the total proteins. Collagen exhibits excellent film-forming property, and can be used be as an outstanding carrier of bioactive compounds (antioxidant and antimicrobial) for food packaging. However, the rough surface and defects in mechanical properties limit application of collagen film for food packaging. Chitosan, industrially produced by partial deacetylation of chitin, is also one kind of excellent natural film-forming material. The incorporation of chitosan can increase the antimicrobial ability of packaging film. Chitosan-gelatin blend films show better material properties when compared to pure single-component polymer films. The previous studies inferred hydrogen bonds and electrostatic interactions were formed between collagen and chitosan molecules during the process of film formation using one-dimensional infrared spectroscopy. Two-dimensional infrared correlation spectroscopy is a method to study the intermolecular interactions between functional groups under the interference of exogenous factors. The two-dimensional infrared correlation spectroscopy can also obtain the sensitivity and response order of the functional groups to external disturbance. At present, the interaction between bone collagen and chitosan has not been reported by two-dimensional infrared correlation spectroscopy. The paper aimed to infer the interaction by analyzing the characteristics of two-dimensional infrared correlation spectroscopy of bone collagen-chitosan blend film with different mixing ratios. Collagen, extracted from sheep bone by pepsin, and chitosan were mixed evenly according to 100:0, 60:40, 50:50, 40:60 and 0:100, respectively, and then 25% glycerol was added as plasticizer. The mixed film-forming solution was dried at 50 oC for 18 h, and then placed at room temperature for 6 h and uncovered. Fourier transform infrared spectroscopy (FTIR) of blending film was obtained and analyzed by the peak fitting and two-dimensional correlation analysis to infer the interaction between collagen and chitosan molecules. Infrared spectroscopy showed that the intensity and shape of infrared absorption peaks changed obviously with the addition of chitosan. The results showed that conformation of C=O bond of bone collagen varied first with the addition of chitosan. The peak fitting results showed that the secondary structure of collagen in the blend film was mainly β sheet. The content of α helix decreased, and the content of β sheet and β turn increased after adding chitosan. The change of secondary structure of collagen in the blend film may be caused by the film forming process, such as the blending temperature and drying temperature. The secondary structure of collagen extended gradually, and further characteristic group was exposed. FTIR results proved the higher deacetylation degree of chitosan. The existence of two-dimensional infrared correlation peak involved in C-O-C bond of glycosyl skeleton confirmed the spatial conformation of chitosan varied. The infrared spectrum of N-H bond vibration varied significantly after adding chitosan. The hydroxyl, amine, and carboxyl groups of collagen were capable of forming hydrogen bonds with hydroxyl and amine groups of chitosan. The electrostatic interaction was formed between collagen and chitosan whose –NH2groups were easily protonated in acidic solutions and converted to –NH3+. Two-dimensional infrared correlation spectroscopy indicated the response order of groups to mixture ratio was: 1633 cm–1> 1448 cm–1>1236 cm–1> 1068 cm–1> 997 cm–1> 896 cm–1. The intensity and maximum wavenumbers of absorption peaks confirmed that the intermolecular hydrogen bonds appeared between collagen and chitosan in blend films, which were dependent on the ratio of collagen/gelatin to chitosan. In conclusion, the present study shows that hydrogen bonding and electrostatic interaction are formed between collagen and chitosan molecules in blending film, and the strength of intermolecular interaction is related to mixture ratio of collagen and chitosan.

Improving the salt tolerance of direct-seeding rice at the seed germination stage is a major breeding goal in many Asian rice-growing countries, where seedlings must often establish in soils with a high salt content. Thus, it is important to understand the genetic mechanisms of salt tolerance in rice and to screen for germplasm with salt tolerance at the seed germination stage. Here, we investigated seven seed germination-related traits under control and salt-stress conditions and conducted a genome-wide association study based on the re-sequencing of 478 diverse rice accessions.

Mutton slices from forelegs,hindquarters and flank of male and female adult Oula Tibetan sheep were examined for sensory quality,physicochemical properties and protein degradation characteristics after instant boiling.The results showed that ewe meat were more suitable for instant boiling due to higher sensory scores compared to ram meat.Flank had the best sensory quality,followed by hindquarters.Aldehydes were the most important volatile flavor compounds for instantboiled Oula Tibetan sheep meat.Ram meat had higher aldehydes contents compared to ewe meat,and hindquarters had higher aldehydes contents compared to the other meat cuts.The degradation degree of myofibrillar proteins of ewe meat was larger than that of ram meat.Instant boiling loss of forelegs was the largest,and flank showed the least instant boiling loss.

A phosphoproteomic profile of myofibrillar and sarcoplasmic proteins of muscle in response to salting was investigated. Myofibrillar and sarcoplasmic proteins extracted from salted meat with 0, 1, 2, 3, 4, and 5% salt for 0, 2, 4, 6, 8, and 16 h were analyzed by SDS-PAGE electrophoresis and fluorescence staining. The global phosphorylation of myofibrillar proteins in salted meat was lower than that in control muscle at 16 h of salting (p<0.05), and the global phosphorylation of myofibrillar proteins in 3% salt-treated group at 16 h was the lowest. However, salting showed no significant effect on phosphorylation of sarcoplasmic proteins. Four categories of phosphorylated protein were identified by LC-MS/MS, involved in stress response (heat shock protein), glycometabolism (glycogen phosphorylase, glyceraldehyde-3-phosphate dehydrogenase), oxidation or reduction (superoxide dismutase), and others (myoglobin), the phosphorylation of which was affected by salting. Thus, salting may influence meat quality through protein phosphorylation, which regulates protein degradation and glycolysis.