重金属对饲料污染的分析及防制措施

文章综述了我国饲料重金属污染的种类、污染物的主要来源、污染物的特性及危害机理,并简要阐述了预防饲料重金属污染的措施。     

VH1-44 gene usage defines a subset of canine B-cell lymphomas associated with better patient survival

The use of specific immunoglobulin heavy chain variable region (VH) genes has been associated with increased patient survival in human B-cell lymphomas (hBCL). Given the similarity of human and canine BCL (cBCL) in morphology and clinical treatment, we examined the choice of VH in cBCL and determined whether VH gene selection was a distinct feature associated with survival time in dogs. VH gene selection and mutational status in 52 cBCL, including 29 diffuse large B-cell lymphomas (cDLBCL, the most common subtype of cBCL), were analyzed by comparison with the 80 published canine germline VH gene sequences. We further examined the prognostic impact of the subgroups defined by these features on canine survival. We found that VH1-44 was preferentially expressed in the majority of the 52 cBCLs (60%) as well as in the majority of the cDLBCL subset (59%). VH1-44 gene expression was associated with a statistically better overall survival (p = 0.039) in cBCL patients, as well as in the cDLBCL subset of patients (p = 0.038). These findings suggest that VH gene selection in cBCL is not random and may therefore have functional implications for cBCL lymphomagenesis, in addition to being a useful prognostic biomarker.     

Changes in muscle fiber type and expression of mRNA of myosin heavy chain isoforms in porcine muscle during pre‐ and postnatal development

The purpose of this study is to elucidate developmental changes in muscle fiber type in the pig during pre‐ and postnatal development. For this purpose, we performed a histochemical analysis for myosin adenosine triphosphatase activity to assess muscle fiber type and determined abundances of messenger RNA (mRNA) of myosin heavy chain (MHC) isoforms. Samples of Longissimus dorsi (LD) muscle were taken from fetuses on day 90 of the fetal stage. Further, samples of LD, Rhomboideus and Biceps femoris (B. femoris) muscles were taken from pigs when they were 1, 12, 26, 45 or 75 days old. Expression of MHC 2b mRNA in the LD and the B. femoris muscles rapidly and considerably increased from the late fetal stage to the early postnatal stage and this increase was associated with the development of type 2b fibers at least in the LD muscle. As shown by the rapid and considerable changes in expression of MHC 2b mRNA, it seems that a certain plasticity of muscle fiber type still remains in this developmental stage.     

乳糖酶的固定化及其应用研究进展

乳糖酶在乳制品加工领域应用广泛,有很重要的研究利用价值.本文概述了乳糖酶的特性、固定化,重点分析了乳糖酶在乳品工业的应用研究进展,并展望了乳糖酶的发展前景.旨在为乳糖酶的固定化研究提供参考.     

模拟酸雨与Cd对紫萼膜脂过氧化及形态特征的影响

为了解酸雨与Cd复合污染对紫萼膜脂过氧化及形态特征的影响,本试验采用土培的方式,人工模拟pH分别为6.5,5.5,4.5,3.5,2.5梯度酸雨与不同浓度(0,10,30,50,100 mg/kg)Cd复合胁迫紫萼,从植物形态特征,质膜过氧化,抗氧化方面的响应研究复合污染对植物的生理生态影响特点。结果表明,复合污染比单一污染对植物伤害更大,二者间存在明显的交互作用,并非简单的加和作用,更多地表现为协同作用,高强度复合污染对紫萼的影响更大。紫萼对低强度酸雨和低浓度Cd污染有一定耐受性。Cd对植物的影响比酸雨更显著,是复合污染下造成植物伤害的主要因素。CAT活性对Cd污染比SOD敏感;Cd浓度为30 mg/kg和酸雨pH=3.5是植物可见伤害的临界值。综合各指标对复合污染的响应,紫萼可作为酸雨区土壤Cd污染背景下修复植物的选择。     

锰胁迫下鸡眼草的富集特征及生理响应

为探明植物对锰胁迫的耐受性机制,以采自重金属污染区与非污染区的鸡眼草为试验材料,在不同锰浓度胁迫下［0 （对照）、1000、5000、10000、15000、20000 μmol·L^-1］ 开展盆栽试验,比较研究锰胁迫对两种来源鸡眼草表型、生理生化特性及锰积累特征的影响。结果表明：随着锰浓度的升高,1） 两种来源鸡眼草的根干重、芽干重、根冠比均呈降低的趋势;当锰浓度达5000~20000 μmol·L^-1时,与对照相比,污染区、非污染区鸡眼草的芽干重分别下降4.34%~27.71%与16.33%~49.77%,根干重分别下降19.00%~66.06%与27.90%~77.54%,污染区下降幅度均较非污染区的小;2） 两种来源鸡眼草的叶绿素、可溶性糖、脯氨酸含量及超氧化物歧化酶（SOD）、过氧化物酶（POD）活性均呈先升后降的趋势,可溶性蛋白含量逐渐下降,丙二醛（MDA）含量则逐渐升高;3） 两种来源鸡眼草根、茎、叶的锰含量均增加;锰浓度为20000 μmol·L^-1时,污染区和非污染区鸡眼草的叶锰含量分别为对照的16.53和13.41倍。因此,污染区鸡眼草锰耐受能力及富集能力均较非污染区鸡眼草高,较高的抗氧化酶活性是其耐受高锰胁迫的重要生理机制。     

铜、镉、铅对高羊茅种子萌发及幼苗生长的影响

以高羊茅火凤凰2号(PhoenixⅡ)为试验材料,研究铜(Cu)、镉(Cd)、铅(Pb)对高羊茅(Festuca arundinacea)种子萌发和幼苗生长的影响。分别用CuSO4·5H2O,3CdSO4·8H2O和Pb(NO3)2溶液模拟重金属胁迫处理高羊茅种子,设置低浓度、中浓度、较高浓度、高浓度4个浓度梯度,分别为Cu^2+(200、300、400、500mg/L);Cd^2+(1、50、100、150mg/L);Pb^2+(500、1000、1500、2000mg/L)。通过测定火凤凰2号的相对发芽率、相对发芽势、发芽指数、活力指数、叶表面积、根冠比等13个生长指标,研究高羊茅在3种重金属胁迫下的发芽及幼苗生长状况。结果表明:高羊茅对镉胁迫的耐受性最好,中、低浓度铜胁迫下幼苗耐受性较差,较高浓度及高浓度下对铅胁迫的耐受性最差。铜胁迫下随着胁迫程度的加剧,各项指标均呈下降趋势且幼苗生长受到抑制;低浓度镉、铅胁迫对种子萌发及幼苗生长有促进作用,随着胁迫程度的增高,种子萌发和幼苗生长会受到明显的抑制。当Pb^2+≥1500mg/L时,高羊茅幼苗根系生长受到完全抑制,生长量为0,出现“无根苗”。     

Comparative sequence analysis of four myosin heavy chain isoforms expressed in porcine skeletal muscles: Sequencing and characterization of the porcine myosin heavy chain slow isoform

A nucleotide sequence including the full coding region for the myosin heavy chain (MyHC) slow isoform was determined from the longissimus skeletal muscle. The deduced amino acid sequence was 1935 residues, which was the same length as the human and rat MyHC-slow isoforms. The porcine MyHC-slow isoform showed 97.6% and 97.4% amino acid identities to the human and rat isoforms on their entire regions, respectively. The functional regions were also highly conserved among mammalian MyHC-slow isoforms. Amino acid substitutions between the porcine MyHC-slow and MyHC-fast isoforms were concentrated on the functional regions. Loop 1, the controlling region of nucleotide binding and release, was conserved among the fast isoforms, but not between the slow and fast isoforms. Loop 2, a part of the actin binding region, was not conserved among any of the isoform types, and the most substitutions in this region were found in the slow isoform. The myosin essential light chain binding region was conserved among the fast isoforms, except for some substitutions in the 2b isoform, but was clearly different in the slow isoform. The myosin regulatory light chain binding region was conserved among the fast isoforms, but not between the slow and fast isoforms. These results indicate that the functional difference between the porcine MyHC-slow and -fast isoforms are controlled by the sequence diversity at the four functional regions compared.