Infectious prions in the saliva and blood of deer with chronic wasting disease

A critical concern in the transmission of prion diseases, including chronic wasting disease (CWD) of cervids, is the potential presence of prions in body fluids. To address this issue directly, we exposed cohorts of CWD-na?ve deer to saliva, blood, or urine and feces from CWD-positive deer. We found infectious prions capable of transmitting CWD in saliva (by the oral route) and in blood (by transfusion). The results help to explain the facile transmission of CWD among cervids and prompt caution concerning contact with body fluids in prion infections.     

鹿慢性消耗性疾病免疫组织化学检测方法的建立与优化

【目的】在自主研制的抗鹿朊蛋白单克隆抗体基础上,建立和优化了鹿慢性消耗性疾病(chronic wasting disease, CWD)的免疫组织化学（immunohistochemistry, IHC）诊断方法。【方法】按照常规石蜡病理切片制作方法制备阴性和阳性切片,应用ABC法对获得的5株单抗进行免疫组织化学检测。【结果】试验结果表明,5株单抗（编号分别为5A5、3B2、6D12、5E3、1F5）中只有5E3和3B2可以与CWD的阳性鹿延髓切片发生特异性免疫反应,而且5E3的反应较强烈,3B2的反应较弱,其它3株单抗则在试验的浓度范围内无特异性免疫反应。此外,5E3的稀释比例为1：10 000时,免疫反应效果达到最佳状态。【结论】实验结果表明,单抗5E3可以用于我国CWD的监测。     

Balancing selection at the prion protein gene consistent with prehistoric kurulike epidemics

Kuru is an acquired prion disease largely restricted to the Fore linguistic group of the Papua New Guinea Highlands, which was transmitted during endocannibalistic feasts. Heterozygosity for a common polymorphism in the human prion protein gene (PRNP) confers relative resistance to prion diseases. Elderly survivors of the kuru epidemic, who had multiple exposures at mortuary feasts, are, in marked contrast to younger unexposed Fore, predominantly PRNP 129 heterozygotes. Kuru imposed strong balancing selection on the Fore, essentially eliminating PRNP 129 homozygotes. Worldwide PRNP haplotype diversity and coding allele frequencies suggest that strong balancing selection at this locus occurred during the evolution of modern humans.     

季节变化对长白山马鹿肉质品质的影响研究

[目的]研究季节变化对马鹿肉质品质的影响。[方法]测定分别在秋前和秋后屠宰的9头性成熟马鹿的肉色、大理石纹状结构、pH值、系水力、熟肉率、剪切力和营养成分。[结果]结果表明,秋后肉质色泽变深(P<0.01)、大理石纹状结构明显减少(P<0.01)、系水力(53.16%)和熟肉率(62.43%)均极显著下降(P<0.01),剪切力值达6.05 kg/cm2,极显著高于秋前(P<0.01)。秋后肉质脂肪含量下降极显著(P<0.01),水分和蛋白质也呈下降趋势(P<0.05),而干物质含量和灰分则有所增加(P<0.05)。脂肪含量与肉质指标的相关性分析显示,与肉色呈极显著的负相关(r=-0.946,P<0.01),而与大理石纹状结构呈极显著的正相关(r=0.912,P<0.01)。脂肪含量影响肉质的系水力和熟肉率,且呈显著的正相关(r=0.726、0.689,P<0.05);脂肪含量越小,肌肉剪切力值越大(r=-0.672,P<0.05)。[结论]秋后屠宰,鹿肉色泽鲜红,可接受性增加。     

Prevention of scrapie pathogenesis by transgenic expression of anti-prion protein antibodies

Variant Creutzfeldt-Jakob disease and bovine spongiform encephalopathy are initiated by extracerebral exposure to prions. Although prion transmission from extracerebral sites to the brain represents a potential target for prophylaxis, attempts at vaccination have been limited by the poor immunogenicity of prion proteins. To circumvent this, we expressed an anti-prion protein (anti-PrP) mu chain in Prnp(o/o) mice. Transgenic mice developed sustained anti-PrP titers, which were not suppressed by introduction of Prnp+ alleles. Transgene expression prevented pathogenesis of prions introduced by intraperitoneal injection in the spleen and brain. Expression of endogenous PrP (PrP(C)) in the spleen and brain was unaffected, suggesting that immunity was responsible for protection. This indicates the feasibility of immunological inhibition of prion disease in vivo.     

森林生态系统粗木质残体研究进展

粗木质残体（coarse woody debris,CWD）是森林生态系统中重要的结构性和功能性组成要素,是联系森林生态系统养分循环、碳库储存、群落更新以及为其他有机体提供生境等主要功能的载体和纽带,对森林生态系统的能量流动及物质循环以及在维护森林生态系统的完整性和稳定性方面具有重要作用,科学有效地对其进行定量化研究,对了解粗木质残体在生物地球化学循环过程中和全球碳循环与碳平衡中的地位与作用具有重要意义。从4个方面阐述森林生态系统粗木质残体的研究进展:①粗木质残体的来源及分类;②粗木质残体的研究内容;③粗木质残体的研究方法;④粗木质残体的生态功能。最后提出了提高粗木质残体定量化研究以及结构与功能研究的4种路径选择:①改进研究方法,提高粗木质残体基础数据的定量化研究,加强本底数据的积累,并构建丰富翔实的粗木质残体数据库;②重视粗木质残体结构与功能的研究,强化人类活动对粗木质残体的影响及其对森林生态系统结构和功能影响的研究;③发展粗木质残体生态功能定量化与模型化研究,定量研究粗木质残体的分解速率及其在生物地球化学循环和全球碳循环与碳平衡中的作用;④研究粗木质残体的动态特征与森林演替的交互关系,优化粗木质残体可持续经营管理方式及管理策略。参64     

肉品的嫩化机制、方法及其影响因素

肉品嫩度是肉的主要食用品质之一,它是消费者评判肉质优劣的最常用指标.由肌肉转变为可食性肉,到最后的嫩化成熟是一个复杂过程.宰后肉类的后期成熟和嫩化处理,是改善肉品嫩度的关键环节.该文主要阐述了影响肉嫩度的因素(宰前和宰后因素)、嫩化方法以及嫩化机制(如:电刺激、盐类、酶法、有机酸、超声波、高压和吊挂拉伸等),为肉制品加工企业品质改良提供理论支持.     

A mutation in PRKAG3 associated with excess glycogen content in pig skeletal muscle

A high proportion of purebred Hampshire pigs carries the dominant RN- mutation, which causes high glycogen content in skeletal muscle. The mutation has beneficial effects on meat content but detrimental effects on processing yield. Here, it is shown that the mutation is a nonconservative substitution (R200Q) in the PRKAG3 gene, which encodes a muscle-specific isoform of the regulatory gamma subunit of adenosine monophosphate-activated protein kinase (AMPK). Loss-of-function mutations in the homologous gene in yeast (SNF4) cause defects in glucose metabolism, including glycogen storage. Further analysis of the PRKAG3 signaling pathway may provide insights into muscle physiology as well as the pathogenesis of noninsulin-dependent diabetes mellitus in humans, a metabolic disorder associated with impaired glycogen synthesis.     

Facilitated cross-species transmission of prions in extraneural tissue

Prions are infectious pathogens essentially composed of PrP(Sc), an abnormally folded form of the host-encoded prion protein PrP(C). Constrained steric interactions between PrP(Sc) and PrP(C) are thought to provide prions with species specificity and to control cross-species transmission into other host populations, including humans. We compared the ability of brain and lymphoid tissues from ovine and human PrP transgenic mice to replicate foreign, inefficiently transmitted prions. Lymphoid tissue was consistently more permissive than the brain to prions such as those causing chronic wasting disease and bovine spongiform encephalopathy. Furthermore, when the transmission barrier was overcome through strain shifting in the brain, a distinct agent propagated in the spleen, which retained the ability to infect the original host. Thus, prion cross-species transmission efficacy can exhibit a marked tissue dependence.     

Human prion protein cDNA: molecular cloning, chromosomal mapping, and biological implications

A human complementary DNA whose protein product is considered to be the major component of scrapie-associated fibrils in Creutzfeldt-Jakob disease, kuru, and Gerstmann-Straussler syndrome has been identified and characterized. The extensive homology of this gene sequence to the hamster PrP 27- to 30-kilodalton prion protein complementary DNA clone, and its existence as a single copy in the human genome, leads to the conclusion that this is the human prion gene. This human prion gene has been mapped to human chromosome 20, negating a direct link between the prion protein and Down's syndrome or the amyloid of Alzheimer's disease.     

转基因和基因编辑猪的研究进展

猪是重要的农业经济动物,其在遗传背景、解剖学、生理病理学、营养代谢和疾病特征等方面与人类高度相似,是农业生产性状改良、人类疾病动物模型和异种器官移植研究的重要对象。随着ZFN、TALEN和CRISPR等基因编辑技术的出现,转基因或基因编辑猪的研究取得快速发展。本文将结合当前我国转基因及基因编辑猪的研究现状,对基因编辑技术在农业生产性状改良如提高产肉量、改善肉质、提高抗病能力和建立人类疾病模型、动物生物反应器、异种器官移植等方面进行综述,以期为猪遗传改良和医学研究提供参考。     

骨骼肌肌纤维形成机制的研究进展

骨骼肌是动物躯体最重要的组成部分,占到产肉动物躯体的40%,肌纤维作为骨骼肌组织的主要成分,其类型的差异是影响产肉动物肌肉品质的重要因素之一。因此,骨骼肌的生长发育与产肉动物肉的产量有着密切的联系,而其生理生化特性的差异也将会直接影响到产肉动物屠宰之后肉品的质量。一般而言,动物骨骼肌肌纤维数目在胚胎发育期间基本上就已固定,出生之后,由于肌纤维的肥大,动物躯体肌肉块才表现出增大增粗。另外,动物肌肉块在生长发育过程中,其肌纤维组成类型并不是完全固定的,它们会随着骨骼肌对代谢与功能需求的改变而发生转变。骨骼肌的生长发育,以及骨骼肌肌纤维类型的发生与发展是一个非常复杂的生物学过程,受到许多信号通路与因子的调控。随着分子生物学技术的飞速发展,各种先进技术相继被应用于生物学现象的研究中,利用这些分子生物学技术很好的阐明了许多复杂生物学现象形成的分子机制。目前,骨骼肌生长发育的分子遗传调控机制取得了长足的进展,许多与骨骼肌形成发育相关的关键因子已被鉴定出来。然而,在早期研究中,人们对于骨骼肌肌纤维的研究主要集中在类型的鉴定,以及不同肌纤维类型生理生化特性的分析,对于骨骼肌肌纤维形成的具体分子遗传调控机制的研究相对较少。近年来,随着研究的不断深入,骨骼肌肌纤维形成的分子遗传调控机制也取得了突破性的进展。因此,有必要进一步对骨骼肌肌纤维类型的特性,骨骼肌肌纤维类型形成的分子机制,以及肌纤维类型与肌肉品质的关系进行全面的综述。本文首先对肌纤维的类型、特性进行了综述;进一步分别对慢型肌纤维与快型肌纤维形成的分子调控机制的研究进展进行了回顾;最后对肌纤维类型与肉品质的关系进行了讨论。总之,本综述的撰写将有助于对骨骼肌肌纤维类型形成的遗传机制的进一步了解,为将来进一步的深入研究肌纤维形成的分子机制提供参考;同时也将有助于揭示肌肉品质形成的分子遗传调控机制,为利用分子生物学技术培育高品质新品种或新品系产肉动物提供分子理论依据。     

畜禽硒—维生素E缺乏综合征流行病学调查研究——Ⅲ.黑龙江省畜禽硒—维E缺乏综合征流行病学调查初报

本文初步综合报导了黑龙江省畜禽硒—维生素 E 缺乏综合征的流行病学调查研究结果。通过调查研究,确认在我省大部分地区均有本病的发生,侵害猪、羊、牛、马、鹿、兔、水貂及鸡,北京鸭等多种畜禽,且以幼龄畜禽病情严重。综合征的流行具有地区性的待点,即受特定的环境条件所制约。初步查明,低硒环境(土壤)是致病的根本条件。因此,疾病的实质是一种生物地球化学性流行病。调查结果表明,从流行病学现象及病区的分布来看,本综合征与人的克山病有一定的相关性。     

中国森林粗木质残体储量及其影响因素

 粗木质残体（CWD）是森林生态系统的重要组成部分,在森林生态系统结构组成和功能发挥中扮演重要角色。在收集整理文献资料数据的基础上对长白山、小兴安岭、秦岭、武夷山、鼎湖山、哀牢山等地不同森林生态系统粗木质残体储量的研究结果进行了初步统计和分析。初步结果认为：中国南、北方森林生态系统的粗木质残体储量存在差异,北方的粗木质残体储量是针叶林＞针阔混交林;南方的粗木质残体储量是阔叶林＞针阔混交林＞针叶林。海拔、林分结构、年平均降水量、自然灾害、人为干扰均是影响粗木质残体储量的因子,枯立木和倒木是中国原始林粗木质残体储量的主要贡献者。研究结果可为中国森林生态系统粗木质残体的进一步深入研究及相应的合理保护和利用提供依据。图2表2参47     

Exogenous induction of cerebral beta-amyloidogenesis is governed by agent and host

Protein aggregation is an established pathogenic mechanism in Alzheimer's disease, but little is known about the initiation of this process in vivo. Intracerebral injection of dilute, amyloid-beta (Abeta)-containing brain extracts from humans with Alzheimer's disease or beta-amyloid precursor protein (APP) transgenic mice induced cerebral beta-amyloidosis and associated pathology in APP transgenic mice in a time- and concentration-dependent manner. The seeding activity of brain extracts was reduced or abolished by Abeta immunodepletion, protein denaturation, or by Abeta immunization of the host. The phenotype of the exogenously induced amyloidosis depended on both the host and the source of the agent, suggesting the existence of polymorphic Abeta strains with varying biological activities reminiscent of prion strains.     

Human prion protein with valine 129 prevents expression of variant CJD phenotype

Variant Creutzfeldt-Jakob disease (vCJD) is a unique and highly distinctive clinicopathological and molecular phenotype of human prion disease associated with infection with bovine spongiform encephalopathy (BSE)-like prions. Here, we found that generation of this phenotype in transgenic mice required expression of human prion protein (PrP) with methionine 129. Expression of human PrP with valine 129 resulted in a distinct phenotype and, remarkably, persistence of a barrier to transmission of BSE-derived prions on subpassage. Polymorphic residue 129 of human PrP dictated propagation of distinct prion strains after BSE prion infection. Thus, primary and secondary human infection with BSE-derived prions may result in sporadic CJD-like or novel phenotypes in addition to vCJD, depending on the genotype of the prion source and the recipient.     

梅花鹿巴氏杆菌病的防治

鹿巴氏杆菌病是由多杀性巴氏杆菌引起的一种败血性传染病,发病率、死亡率较高不易早期发现,是影响鹿业发展较大的一种传染病。就梅花鹿巴氏杆菌病的发病情况与防治进行探讨。     

Depleting neuronal PrP in prion infection prevents disease and reverses spongiosis

The mechanisms involved in prion neurotoxicity are unclear, and therapies preventing accumulation of PrPSc, the disease-associated form of prion protein (PrP), do not significantly prolong survival in mice with central nervous system prion infection. We found that depleting endogenous neuronal PrPc in mice with established neuroinvasive prion infection reversed early spongiform change and prevented neuronal loss and progression to clinical disease. This occurred despite the accumulation of extraneuronal PrPSc to levels seen in terminally ill wild-type animals. Thus, the propagation of nonneuronal PrPSc is not pathogenic, but arresting the continued conversion of PrPc to PrPSc within neurons during scrapie infection prevents prion neurotoxicity.     

天宝岩典型森林群落粗死木质残体现存量研究

对天宝岩国家级自然保护区长苞铁杉林、猴头杜鹃林和柳杉林典型森林群落粗死木质残体（CWD）现存量进行研究。结果表明:1）天宝岩3种典型森林群落CWD现存量分别为33.6、45.3、31.8 t/hm2,处于我国热带和亚热带地区森林的中间水平;2）3种森林群落中,CWD的不同形态组成较不同腐烂等级对现存量差异的贡献度更大;3）猴头杜鹃林和长苞铁杉林内各种类型CWD现存量表现为倒木枯立木树桩,柳杉林内CWD现存量则为树桩枯立木倒木;4）中高腐烂等级CWD现存量为猴头杜鹃林长苞铁杉林柳杉林,而在低腐烂等级中呈现长苞铁杉林猴头杜鹃林;5）在柳杉林内,未受人为干扰地段枯立木和树桩所占比例明显高于受干扰地段,而倒木的比例则很低。      

鹿结核病流行概况

鹿结核病是由牛型结核分支杆菌(Mycobacterium bovis)引发的一种恶性传染病。目前,世界上大多数鹿场都可以检测到其病原体,该病对养鹿业的危害是巨大的。现就鹿结核病在世界范围内的流行情况、流行特点以及某些国家对鹿结核病的控制政策等作一综述。