毛竹林地土壤团聚体稳定性及其对碳贮量影响研究

通过对集约经营毛竹林地土壤团聚体的测定,结果表明毛竹林地3个土壤层次各粒径团聚体分布特征为>5 mm的含量在土壤团粒结构中占主导地位,占总团聚体的比例为26.39%~42.38%;其次为1~5 mm含量,占14%~18%;<0.25 mm的含量最小,占2.31%~6.73%。毛竹林土壤团聚体平均重量直径平均值为0.90 mm,并且随着土壤层次的增加有逐渐增加的趋势。毛竹林地土壤总有机碳的积累与0.25~3.15 mm土壤团聚体中有机碳含量呈显著相关,与>3.15 mm和<0.25 mm团聚体有机碳含量相关不显著。毛竹林地0~20 cm土壤层中,分布在>5 mm和3.15~5 mm粒径土壤团聚体中的有机碳比例分别为14.86%和11.26%,低于20~40 cm和40~60 cm土壤。这也说明,长期集约经营毛竹林后,林地土壤有机碳含量下降的主要原因可能是>5 mm粒径土壤团聚体有机碳含量下降。     

华西雨屏区人工竹林凋落物及表层土壤的水源涵养功能研究

以华西雨屏区退耕还林后形成的人工竹林(慈竹林、苦竹林、撑绿杂交竹林、苦竹 光皮桦混交林)为对象,对其凋落物及表层土壤的水源涵养功能进行了初步研究。结果表明:几种竹林凋落物蓄积量的大小顺序是:撑绿杂交竹林>混交林>苦竹林>慈竹林,且都大于光皮桦林。叶凋落物持水量的大小关系为:慈竹林>混交林>苦竹林>杂交竹林,光皮桦林的持水量介于慈竹林和混交林之间。几种叶凋落物持水量与浸泡时间的关系符合指数函数的模型、持水速率与浸泡时间的关系符合幂函数的模型。不同林地的表层土壤容重在1.27~1.34 g/cm3之间,总孔隙度48.08%~55.96%,不同林地表层土壤的水分物理性质差异不大。     

雷竹引种与丰产培育试验初报

通过引种雷竹,进行笋用竹林丰产栽培试验,探讨营林技术对其速生丰产的影响,结果表明:采用林地表土层以下深度30cm深翻耕作、深层施肥等措施后其优质经济竹(眉围≥9.60cm)可达65.0%以上,比对照提高18.6%~31.7%,新栽竹林套种农作物有利于促进雷竹笋用竹林速繁成林。     

毛竹切削力的研究

为合理制定竹材切削工艺,节约切削动力,该文利用传感器技术及信号分析技术,经切削实验研究了毛竹不同切面、密度、含水率等物理性质及刀具前角、切削量与切削速度等切削参数对切削力的影响.结果表明,由于竹黄部位维管束分布较疏,所需主切削力较小;竹青部位维管束分布密集,主切削力较大.端面切削主切削力最大,纵向切削力次之,横向切削力最小;竹材密度对切削力有明显影响,且呈正相关关系.随着含水率的增大,竹材韧性增加,所需主切削力增加;当含水率超过30%之后,主切削力随含水率的进一步增加而缓慢降低.刀具前角对主切削力的影响较为显著,随刀具前角的增大,所需主切削力明显减小.主切削力与切削量呈正相关关系.切削速度对切削力的影响不大.      

气调包装复合保鲜技术在水产品保鲜中的应用现状

水产品营养价值高,含有多种氨基酸、不饱和脂肪酸、矿物质等营养素而脂肪含量相对较低,深受人们喜爱,也是中国居民膳食指南中的重要组成部分。水产品中由于水分、蛋白质等成分含量丰富,极易在微生物和内源酶的作用下发生蛋白质、脂肪等的降解或氧化而腐败变质,从而缩短了货架期,降低了商业价值。气调包装保鲜技术是指通过使用高阻隔性能的复合包装材料,并调整食品贮藏环境中的气体组成来改善食品贮藏品质并延长货架期的技术,因其安全性高、保鲜效果好而被广泛应用于水产品保鲜领域中,本文总结了近几年气调包装复合其他保鲜技术(低温、紫外杀菌、臭氧处理、超高压处理、化学保鲜剂、生物保鲜剂)在水产品保鲜领域中的应用,旨在为气调包装在水产品保鲜中的进一步应用提供理论依据。已有的研究表明该复合技术能有效地降低水产品贮藏末期微生物总数、挥发性盐基氮、三甲胺、生物胺等指标,并维持较高的感官评分、水分含量、鲜度值,可有效延长水产品的货架期,未来可以从气调包装复合保鲜技术的抑菌机理、理化指标变化机理、包装材料及模式等方面展开深入研究。     

Rapid screening of genetically modified ingredients in soybean and cotton processing by-product and waste using direct qPCR

To develop a simple and fast method for screening genetically modified ingredients from processing by-product and waste, direct quantitative PCR (qPCR) kit-Taqman which omitting multi genomic DNA preparing steps was developed in this study. A total of 18 oil crop processing by-products and wastes including 10 soybean and 8 cotton materials were collected from food processing factories. Compared with 2 commercial direct qPCR kits, conditions of DNA releasing procedure and PCR amplification were optimized. Element screening was performed at the initial step of genetically modified (GM) ingredient testing procedure via direct qPCR. GM event identification was carried out in positive samples by initial screening. Totally 5 screening elements (P–35S, T-NOS, Cp4-epsps, bar and pat) for soybean materials and 6 screening elements (P–35S, T-NOS, NPTII, Cry1Ac, bar and pat) for cotton samples were detected. In GM event identification, MON531 and MON1445 were found in cotton materials. Results were further confirmed by real-time PCR with DNA extraction and purification. The direct qPCR system proposed by this research was convenient for rapid screening and identification of GM ingredients in oil crop primary by-product and waste.     

Minimally modified low-density lipoprotein up-regulates endothelin receptors in mouse mesenteric artery through p38 MAPK pathway

AIMTo investigate whether minimally modified low-density lipoprotein (mmLDL) affects the quantity and activity of endothelin （ET） type A (ET_A) and type B (ET_B) receptors in mouse mesenteric artery by activating p38 mitogen-activated protein kinase (MAPK) inflammatory pathway. METHODSThe KM mice were divided into normal saline (NS) group (injection of NS via caudal vein), mmLDL group (injection of mmLDL via caudal vein), LDL group (injection of LDL via caudal vein), mmLDL+SB 203580 group (injection of mmLDL via caudal vein and intraperitoneal injection of p38 MAPK pathway specific inhibitor SB 203580) and mmLDL+DMSO group (injection of mmLDL via caudal vein and intraperitoneal injection of DMSO). Mesenteric artery ring segment vasoconstriction dose-response curves affected by sarafotoxin 6c (S6c) and ET-1 were recorded by the myography system. The mRNA levels of ET_B receptor, ET_A receptor and interleukin-6 (IL-6) were detected by RT-qPCR. The protein levels of ET_B receptor, ET_A receptor, IL-6, p38 MAPK, p-p38 MAPK, NF-κB and p-NF-κB were determined by Western blot. The serum concentration of IL-6 was measured by ELISA. RESULTSThe contractile responses of the blood vessel segments to S6c and ET-1 were significantly increased by mmLDL (P<0.01). The mRNA and protein expression levels of ET_A receptor, ET_B receptor, and IL-6 significantly increased (P<0.01). The protein levels of p-p38 MAPK and p-NF-κB were significantly increased (P<0.01). The serum level of IL-6 was significantly increased (P<0.01). These effects of mmLDL were inhibited by p38 MAPK inhibitor SB 203580. CONCLUSION mmLDL increses the serum concentration of IL-6, up-regulates the expression of IL-6, ET_A receptor and ET_B receptor in mouse mesenteric artery, and enhances the vasoconstriction function medi?ated by ET_A and ET_B receptors, which is related to the activation of p38 MAPK inflammatory pathway and downstream NF-κB pathway.     

竹花叶病毒浙江麻竹分离物全基因组序列及siRNA分析

正已知有3种病毒可在自然条件下侵染竹类植物,即竹花叶病毒(bamboo mosaic virus,BaMV)~[1]、樱桃坏死锈斑驳病毒(cherry necrotic rusty mottle virus,CNRMV)和苹果茎沟病毒(apple stem grooving virus,ASGV)~[2,3]。其中,BaMV是最早在巴西的金竹(Bambusa vulgaris Cv.)和孝顺竹     

中国农业转基因生物环境安全检测标准体系现状与展望

农业转基因生物环境安全检测标准是农业转基因生物安全管理必不可少的技术保障.截至2021年1月,农业部/农业农村部共发布了农业转基因生物环境安全检测标准47项.本文对我国农业转基因生物环境安全检测标准体系现状进行初步总结,对国内外农业转基因生物环境安全检测标准的发展现状进行比较,探讨了今后一段时间内农业转基因生物环境安全...