A Novel Gelatinase from Marine Flocculibacter collagenilyticus SM1988: Characterization and Potential Application in Collagen Oligopeptide-Rich Hydrolysate Preparation

Although the S8 family in the MEROPS database contains many peptidases, only a few S8 peptidases have been applied in the preparation of bioactive oligopeptides. Bovine bone collagen is a good source for preparing collagen oligopeptides, but has been so far rarely applied in collagen peptide preparation. Here, we characterized a novel S8 gelatinase, Aa2_1884, from marine bacterium Flocculibacter collagenilyticus SM1988^T, and evaluated its potential application in the preparation of collagen oligopeptides from bovine bone collagen. Aa2_1884 is a multimodular S8 peptidase with a distinct domain architecture from other reported peptidases. The recombinant Aa2_1884 over-expressed in Escherichia coli showed high activity toward gelatin and denatured collagens, but no activity toward natural collagens, indicating that Aa2_1884 is a gelatinase. To evaluate the potential of Aa2_1884 in the preparation of collagen oligopeptides from bovine bone collagen, three enzymatic hydrolysis parameters, hydrolysis temperature, hydrolysis time and enzyme-substrate ratio (E/S), were optimized by single factor experiments, and the optimal hydrolysis conditions were determined to be reaction at 60 ℃ for 3 h with an E/S of 400 U/g. Under these conditions, the hydrolysis efficiency of bovine bone collagen by Aa2_1884 reached 95.3%. The resultant hydrolysate contained 97.8% peptides, in which peptides with a molecular weight lower than 1000 Da and 500 Da accounted for 55.1% and 39.5%, respectively, indicating that the hydrolysate was rich in oligopeptides. These results indicate that Aa2_1884 likely has a promising potential application in the preparation of collagen oligopeptide-rich hydrolysate from bovine bone collagen, which may provide a feasible way for the high-value utilization of bovine bone collagen.     

不同植物生长促进剂对香蕉假植大苗培育的调控作用

采用盆栽试验,在香蕉假植大苗培育过程中分别喷施浓度均为20 mg/L的赤霉素、复硝酚钠、胺鲜酯、α-萘乙酸钠等植物生长促进剂,以喷施清水为对照,通过不同处理假植大苗生长、物质累积及生理指标的分析,明确不同植物生长促进剂在香蕉假植大苗调控的作用。结果表明,本试验采用的4种植物生长促进剂对香蕉假植大苗培育的调控作用不同。与对照相比,叶面分别喷施20mg/L赤霉素、复硝酚钠均能有利于香蕉假植大苗假茎高及叶面积增加,提高叶绿素含量及叶绿素a、b含量,且以上两种植物生长促进剂平均提高叶绿素含量26.46%;喷施20mg/Lα-萘乙酸钠能提高假植苗假茎粗,提高干物质累积量16.11%积及吸氮量9.95%,促进氮磷钾养分吸收。叶面喷施赤霉素、复硝酚钠、α-萘乙酸钠和胺鲜酯均能显著提高香蕉假植大苗抗性,平均降低丙二醛含量14.64%、提高脯氨酸含量64.36%和SOD含量16.74%,且赤霉素还能显著提高POD含量82.13%。     

Cloning,Expression and Bioinformatics Analysis of Enterococcus faecalis from Northeast Black Bear

In order to detect Enterococcus faecalis endocarditis antigen (EfaA) of bear that was used to disclose the infected Northeast Black bear immediately, a pair of PCR primers was synthesized by EfaA gene of Enterococcus faecalis that was recorded in GenBank (accession number:U03756.1) and the target fragment was 689 bp. The PCR product was cloned by pMD19-T vector, then was transferred to Escherichia coli DH5α competent cells and the positive clones were filtered. Recombinant plasmid (pMD19-T-EfaA) was extracted. Identification of PCR and digestion, sequencing, the structure prediction of proteins were operated. The results showed that EfaA gene was cloned successfully, and the gene homology with ATCC 29212 was 100.0%. pMD19-T-EfaA was constructed successfully, structure of proteins was predicted. This study provided theoretical basis for diagnostic methods of Enterococcus faecalis and laid basis for prevention and control of Northeast Black bear disease.     

浙南山区杨梅大棚促早栽培技术研究

本研究选择‘东魁’杨梅为试验材料,以露地栽培为对照,研究大棚设施促早栽培对‘东魁’杨梅的物候期、产量、品质、效益的影响效应。经过3年的试验,通过对‘东魁’杨梅物候期的记载,产量、效益的统计,单果质量、可溶性固形物、总糖、总酸、钾含量、Vc含量等质量指标的检测,综合分析结果表明,东魁杨梅大棚栽培促早、提质、增效效果显著。本研究对优化和推广杨梅大棚促早栽培技术具有重要意义,对山区农民增收提供示范案例。     

重庆市奉节县中部土壤硒富集特征及来源分析

近年来,人们对富硒(Se)资源的需求不断提高,土壤作为农作物生长的基础物质,富 Se 土地开发利用将是提高 Se 资源合理利用的首要切入点。选取奉节县中部青龙镇和五马镇一带土壤为研究对象,采集 247 个土壤样品,对研究区 Se 元素含量、来源、分布和影响因素特征进行分析。结果表明,研究区土壤 Se 平均含量为 0.462 mg/kg,变异程度属于高度变异。根据《天然富硒土地划定与标识》(DZ/T 0380—2021)中规定的富 Se 土地划分标准,研究区内一般富 Se 点位占比为 17.89%,空间位置上具有连续分布的特点。对 Se 等元素源解析及影响因素分析结果显示,Se 元素与 Cd 等重金属元素具有较强的伴生关系并且来源相对一致。同时,土壤有机质、硫化物、铁氧化物及磷灰石对 Se 含量影响显著,并指示受到外源迁入的影响。据正定矩阵因子分析模型定量源解析分析,研究区 土壤中 Se 来源影响顺序为外源迁入 > 地质背景 > 人为活动,贡献率分别为 70.1%、15.2% 和 14.7%,主要受河流上游地质背景影响,同时伴随着 Cd 的迁入。综合分析表明,研究区土壤环境有利于 Se 元素富集并降低重金属安全风险,具有划定天然富 Se 土地的条件,建议在后续工作中开展专项农作物调查,进一步评估农产品开发利用潜力。     

山西谷子品种主要农艺性状的相关和主成分分析

为了明确山西谷子品种主要农艺性状间的关系,采用相关分析和主成分分析方法对11个山西谷子品种的10个农艺性状进行分析。结果表明：农艺性状的变异范围为1.94%~13.39%,各农艺性状的变异程度由大到小依次为单穗重、穗粒重、产量、穗长、株高、千粒重、出苗期—抽穗期天数、抽穗期—成熟期天数、出谷率、生育期。抽穗期—成熟期天数、单穗重、穗粒重、千粒重、出谷率等5个性状指标与产量呈正相关,其中,抽穗期—成熟期天数与产量呈显著正相关(P<0.05),出苗期—抽穗期天数与抽穗期—成熟期天数呈极显著负相关(P<0.01),出苗期—抽穗期天数与生育期呈极显著正相关(P<0.01)。在所有的主成分分析中,主要集中在前3个主成分,其累积贡献率达75.20%。在对高产品种综合性状评价和选育过程中,穗粒重是提高产量的关键,但同时也应注重对其他性状的综合考虑,注重选择单穗重偏高、株高偏低、生育期、穗长和出谷率适中的材料。     

棉花“保险+期货”模式助力南疆主产棉区脱贫攻坚

通过解析棉花“保险+期货”模式的运行机制、优势及存在的不足,并提出了发展优质棉“订单生产+保险+期货”模式和引入银行、基金等信贷机构的建议,期望对南疆主产棉区贫困棉农增收致富、助力脱贫攻坚提供有益探索。     

Identifying and Characterizing a Novel Peritrophic Matrix Protein (MdPM-17) Associated With Antibacterial Response From the Housefly,Musca domestica (Diptera: Muscidae)

Peritrophic matrix/membrane (PM) critically prevents the midgut of insects from external invasion by microbes. The proteins in the peritrophic membrane are its major structural components. Additionally, they determine the formation and function of this membrane. However, the role of PM proteins in immune regulation is unclear. Herein, we isolated a novel PM protein (MdPM-17) from Musca domestica larvae. Further, the function of MdPM-17 in regulating host innate immunity was identified. Results showed that the cDNA of MdPM-17 full is 635 bp in length. Moreover, it consists of a 477-bp open reading frame encoding 158 amino acid residues. These amino acid residues are composed of two Chitin-binding type-2 domain (ChtBD2) and 19 amino acids as a signal peptide. Moreover, tissue distribution analysis indicates that MdPM-17 was enriched expressed in midgut, and moderate levels in the fat body, foregut, and malpighian tubule. Notably, MdPM-17 recombinant protein showed high chitin-binding capacity, thus belongs to the Class III PM protein group. MdPM-17 protein silencing via RNA interference resulted in the expression of antimicrobial peptide (defensin, cecropins, and diptericin) genes, and this occurred after oral inoculation with exogenous microbes Escherichia coli (Enterobacteriales:Enterobacteriaceae), Staphylococcus aureus (Bacillales:Staphylococcaceae), and Candida albicans (Endomycetales:Saccharomycetaceae)). Therefore, all the antimicrobial peptide (AMP) gene expression levels are high in MdPM-17-depleted larvae during microbial infection compared to controls. Consequently, these findings indicate that MdPM-17 protein is associated with the antibacterial response from the housefly.     

丽草蛉滞育预蛹的重要生化物质变化分析

丽草蛉是多种农林害虫的重要捕食性天敌昆虫,能以预蛹进行兼性滞育越冬,该属性对延长丽草蛉的产品货架期、增加产品储备量及促进产品运输具有重要意义。本研究分别测定了丽草蛉非滞育预蛹（1日龄）和滞育预蛹（1日龄、7日龄）体内的总蛋白质、脂类、糖类及醇类等主要生化物质的含量,以及脂肪酶、海藻糖酶、抗氧化酶（超氧化物歧化酶、过氧化物酶、过氧化氢酶）等关键酶的活性变化,比较了非滞育和滞育丽草蛉预蛹体内重要生化物质的差异。结果表明：滞育和非滞育丽草蛉的生理生化特征显著不同,滞育预蛹显著积累蛋白质、脂类、甘油三酯、糖原等能源物质以及甘油、海藻糖等低温保护物质,并且滞育个体的抗氧化防御能力显著增强,这些生理生化变化有助于提高丽草蛉的抗逆性,满足滞育维持期及滞育解除后恢复发育的能量需求,保证滞育个体的发育和存活。结果为解析丽草蛉滞育的生理机制奠定了基础。