线粒体DNA在家猪遗传多样性研究中的应用

笔者介绍了mtDNA基因组结构的研究进展以及线粒体DNA在家猪遗传多样性研究中的应用,并对基于线粒体DNA研究家猪多样性的意义和前景进行展望。     

猪线粒体DNA D-loop环研究进展

D-loop环作为线粒体DNA重要的一个区域,已被广泛用于物种起源分化、系统进化等方面的研究。本文简要介绍了线粒体DNA D-loop环的结构特征及其研究方法,并综述了近年来猪线粒体DNA D-loop环的研究进展。     

猪线粒体DNA(mtDNA)及其在遗传育种中的应用

线粒体DNA是真核细胞内较为简单的DNA分子，具有极少发生重组、进化、速度快等特点，作为动物进化研究的一类重要标记，为动物的起源、迁移和进化提供了大量的证据。本文介绍了线粒体DNA的基本特征及其多态性，概述了猪线粒体DNA的研究概况和取得的成果。线粒体DNA的独特特性必将在猪遗传育种中发挥其重要的作用。     

线粒体DNA及蜜蜂线粒体DNA的研究现状与展望

线粒体DNA是真核细胞中核外唯一的遗传物质,是目前研究起源进化及群体遗传分析的理想研究对象。综述了线粒体DNA(mtDNA)基本特征、多态性及其分析方法的同时,介绍了蜜蜂线粒体DNA的组成结构和多态性,阐述了蜜蜂线粒体DNA研究的现状并对其未来的发展前景予以展望。     

线粒体DNA在先天性免疫中的作用

线粒体是细胞内重要的细胞器,具有多种功能,是细胞的能量工厂。线粒体含有自己的遗传物质线粒体DNA,线粒体DNA因其在氧化磷酸化中的作用而广为人知。近年来,越来越多的研究表明线粒体DNA可作为先天性免疫系统的激动剂,并在病原体感染和炎性疾病的病理发展中起重要作用。线粒体DNA在进入细胞质或细胞外环境后,可以激活多种先天性免疫系统的模式识别受体,从而触发促炎细胞因子分泌和Ⅰ型干扰素反应。因此,本文就线粒体DNA激活先天性免疫的机制以及其在病原体感染和相关疾病发生发展中的作用进行讨论、总结,以期为进一步深入开展线粒体DNA在病原体感染及相关疾病中的作用及其机制研究提供理论依据。     

猪核线粒体假基因的分布特征研究

核线粒体假基因(NUMT)是线粒体DNA插入到核基因组中的DNA片段。目前,已经发现越来越多的真核生物基因组存在线粒体假基因现象。猪线粒体假基因在核基因组中的分布尚未见报道。研究通过猪线粒体基因组全序列与核基因组全序列进行比对,由BLAST程序鉴别出132个NUMT。结果表明:这些NUMT的大小在37～4 453bp,其中90%的NUMT长度处于40～1 000 bp的范围内,NUMT与相应的线粒体DNA片段之间的同源性数值范围为66%～100%。此外,鉴定出的NUMT序列几乎涵盖了包括线粒体DNA控制区在内的全部线粒体基因组,包括30个完整的线粒体基因,分布于猪的1、4、5、7、11、13、14、15、17号染色体上,近50%的NUMT定位在14号染色体上。     

猪卵母细胞线粒体分布及线粒体DNA拷贝数变化

本研究旨在观察猪卵母细胞线粒体分布及线粒体DNA拷贝数变化,以期作为判定哺乳动物卵母细胞胞质成熟的指标,同时也为今后克隆技术的发展和相关基因表达调控的研究提供基础.运用线粒体分子探针标记技术检测体外成熟不同时期卵母细胞中线粒体的分布变化,运用实时荧光定量PCR技术检测其线粒体DNA拷贝数的变化趋势,揭示线粒体分布、线粒体DNA拷贝数变化与卵母细胞发育潜能的关系.结果表明,猪卵母细胞成熟前后,线粒体分布由未成熟的周边分布变为成熟后的均匀分布,并且线粒体簇变大,着色变深.卵母细胞成熟0、11、22 h的mtDNA拷贝数分别为(2 519.52士940.39)、(3 421.47士345.71)和(9 747.58士1 928.24),他们之间无显著性差异(P＞0.05).卵母细胞成熟33 h的mtDNA拷贝数为(39 913.61±1 180.26),显著高于成熟0、11和22 h的mtDNA拷贝数(P＜0.05).卵母细胞成熟44 h的mtDNA拷贝数为(130 074.30±78 119.45),显著高于成熟33 h的mtDNA拷贝数(P＜0.05).由此可见,随着卵母细胞成熟进程的推进,线粒体活性增强,线粒体DNA拷贝数明显增加.     

东北民猪线粒体DNA D-loop遗传多样性与母系起源研究

为了保护东北民猪的遗传资源,对东北地区民猪群体进行线粒体DNA D-loop遗传多样性进行了调查,本研究对30头东北民猪的线粒体D-loop区部分序列(697 bp)进行扩增和测序,共检测到7个变异位点,界定了8种单倍型,核苷酸多样度(Pi)及单倍型多样度(H)分别为:0.217和0.789。结合已收录的30个亚欧猪种的线粒体D-loop序列,采用最大似然法构建的分子进化树明显分为欧洲与亚洲2个主要类群,民猪的8个单倍型都聚在亚洲分支上,并与莱芜黑猪及沂蒙黑猪较为接近,表明民猪是多母系起源群体,主要来自山东地区的华北型黑猪种群。     

一种食品中猪源性成分的快速检测技术

建立一种基于PCR技术的食品中猪源性成分快速检测技术。根据猪线粒体cytb基因设计引物,进行PCR扩增。该方法对猪DNA检测的灵敏度达到100pg;该方法仅对猪DNA检测呈阳性,与其他物种DNA无交叉反应;同时可用于商业样本及复杂食物样本的检测。本研究的猪源性成分特异PCR检测技术具有快速、准确的特点,且具有较高的特异性和敏感性,可作为肉制品中猪源性成分快速检测的手段。     

线粒体DNA损伤及其碱基切除修复的研究进展

DNA对于细胞有氧代谢和外源性化合物产生的活性氧(reactive oxygen species,ROS)极其敏感。大量研究表明,ROS可引起多种类型的DNA氧化损伤,形成种类繁多的具有致突变作用的碱基氧化产物。线粒体DNA接近线粒体自由基的合成区域,因此氧化应激是诱导线粒体DNA突变的主要因素之一。线粒体DNA突变或损伤与机体衰老及肿瘤等生理及病理过程有关,其修复机制尤其是碱基切除修复是保证线粒体DNA完整性的重要途径。本文就其功能及在线粒体功能障碍相关疾病中的研究热点作一综述。     

Phase I evaluation of CCNU (lomustine) in tumor-bearing cats

1-(2-Chloroethyl)3-cyclohexyl-1-nitrosourea (CCNU) is an alkylating agent in the nitrosourea subclass. A prospective evaluation of CCNU was done to determine the maximally tolerated dosage of CCNU in tumor-bearing cats. Response data were obtained when available. Twenty-five cats were treated with CCNU at a dosage of 50-60 mg/m3 body surface area. Complete hematologic data were available for 13 cats. Neutropenia was the acute dose-limiting toxicity. The median neutrophil count at the nadir was 1,000 cells/microL (mean, 2,433 cells/microL; range, 0-9,694 cells/microL). The time of neutrophil nadir was variable, occurring 7-28 days after treatment, and counts sometimes did not return to normal for up to 14 days after the nadir. Based on these findings, a 6-week dosing interval and weekly hematologic monitoring after the 1st treatment with CCNU are recommended. The nadir of the platelet count may occur 14-21 days after treatment. The median platelet count at the nadir was 43,500 cells/microL. No gastrointestinal, renal, or hepatic toxicities were observed after a single CCNU treatment, and additional studies to evaluate the potential for cumulative toxicity should be performed. Five cats with lymphoma and 1 cat with mast cell tumor had measurable responses to CCNU. Phase II studies to evaluate antitumor activity should be completed with a dosing regimen of 50-60 mg/m3 every 6 weeks.     

Prevalence of gastric lesions in racing Alaskan sled dogs

Human and equine athletes are reported to have a high prevalence of gastric disease, and anecdotal evidence suggests a similar phenomenon applies to racing sled dogs. To investigate the prevalence of gastric disease in racing sled dogs, we conducted 2 gastroscopy studies on dogs competing in the annual Iditarod Sled Dog Race. A pilot study of dogs that were either dropped from the 2000 Iditarod Sled Dog Race because of illness or that finished the race indicated that, approximately 5 days after competing, 10 of 28 dogs (35%) had endoscopic evidence of gastric ulceration, erosion, or hemorrhage. The next year, an endoscopic study of 73 dogs participating in the 2001 Iditarod race was performed in order to evaluate a larger population of dogs. Data from 70 of these dogs could be used; 34 (48.5%) had ulceration, erosion, gastric hemorrhage, or some combination of these findings. When this group of 70 dogs was compared retrospectively to a control group of 87 dogs presented to the Texas A&M University (TAMU) Veterinary Medical Teaching Hospital, the Iditarod sled dogs had a significantly higher prevalence (P = .049) of gastric lesions. These findings suggest that, similar to athletes of other species, elite canine athletes have an increased prevalence of gastric disease compared to the canine population at large.     

Furosemide continuous rate infusion in the horse: evaluation of enhanced efficacy and reduced side effects

Continuous rate infusion (CRI) of furosemide in humans is considered superior to intermittent administration (IA). This study examined whether furosemide CRI, compared with IA, would increase diuretic efficacy with decreased fluid and electrolyte fluctuations and activation of the renin-angiotensin-aldosterone system (RAAS) in the horse. Five mares were used in a crossover-design study. During a 24-hour period, each horse received a total of 3 mg/kg furosemide by either CRI (0.12 mg/kg/h preceded by a loading dose of 0.12 mg/kg IV) or IA (1 mg/kg IV q8h). There was not a statistically significant difference in urine volume over 24 hours between methods; however, urine volume was significantly greater after CRI compared with IA during the first 8 hours ([median 25th percentile, 75th percentile]: 9.6 L [8.9, 14.4] for CRI versus 5.9 L [5.3, 6.0] for IA). CRI produced a more uniform urine flow, decreased fluctuations in plasma volume, and suppressed renal concentrating ability throughout the infusion period. Potassium, Ca, and Cl excretion was greater during CRI than IA (1,133 mmol [1.110, 1,229] versus 764 mmol [709, 904], 102.7 mmol [96.0, 117.2] versus 73.3 mmol [65.0, 73.5], and 1,776 mmol [1,657, 2.378] versus 1,596 mmol [1,457, 1,767], respectively). Elimination half-lives of furosemide were 1.35 and 0.47 hours for CRI and IA, respectively. The area under the excretion rate curve was 1,285.7 and 184.2 mL x mg/mL for CRI and IA, respectively. Furosemide CRI (0.12 mg/kg/h) for 8 hours, preceded by a loading dose (0.12 mg/kg), is recommended when profound diuresis is needed acutely in horses.     

The Epidemiology of Gastrointestinal Nematodes of Dairy Cattle in Central Kenya

The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round.     

Diversity of Ectoparasites in Sheep Flocks in Sa~o Paulo,Brazil

The occurrence of ectoparasites in sheep flocks is frequently reported but seldom quantified. Sheep production used to be a predominantly family activity in the state of Sa~o Paulo (Brazil), but it began to become a commercial activity in the past decade. Thus, information about the ectoparasites existing in sheep flocks has become necessary. The present data were obtained by means of questionnaires sent to all sheep breeders belonging to the `Associaça~o Paulista de Criadores de Ovinos' (ASPACO; Sa~o Paulo State Association of Sheep Breeders). Response reliability was tested by means of random visits paid to 10.6% of the respondents. Most of the properties (89.5%) reported the presence of one or more ectoparasites. Screw-worm (Cochliomyia hominivorax) was the most frequent ectoparasite (72.5%), followed by bot fly larvae (Dermatobia hominis, 45.0%), ticks (Amblyomma cajennense) and Boophilus microplus, 31.3%) and finally lice (Damalinia ovis, 13.8%). Combined infestations also occurred, the most common one being screw-worm with bot fly larvae (36.0%) followed by bot fly larvae with ticks (13.9%), screw-worm with ticks (9.3%), bot fly larvae with lice (6.9%), and ticks with lice (5.0%). The most common triple combination was screw-worm, bot fly larvae and ticks (12.8%). Breeds raised for meat or wool were attacked by bot fly larvae and ticks more often than other breeds. Lice were only absent from animals of indigenous breeds. The relationships among these ectoparasites are discussed in terms of sheep breeds, flock size, seasonality and the ectoparasitic combinations on the host.     

Evaluation of biohydrogenation rate of canola vs. soya bean seeds as unsaturated fatty acids sources for ruminants in situ

An experiment was conducted to study disappearance of C14 to C18 fatty acids, lag times and biohydrogenation (BH) rates of C18 fatty acids of ground soya bean and canola seeds in situ. Three ruminally fistulated Dallagh sheep were used to determine ruminal BH of unsaturated fatty acids (UFAs). Differences in the disappearance of fatty acids through the bags and lag times were observed between the oilseeds. We saw that the longer the incubation time of the oilseeds in the rumen, the lower the content of C18:2 and C18:3. Significantly higher lag times for both C18:2 and C18:3 were observed in ground canola compared to ground soya bean. BH rates of C18:2 and C18:3 fatty acids in soya bean were three times higher than those of canola. These results suggest that the fatty acid profile of fat source can affect the BH of UFAs by rumen micro‐organisms. So that UFAs of canola had higher ability to escape from ruminal BH. It seems that fatty acid profile of ruminant products is more affected by canola seed compared to soya bean seed.     

Serum biochemical values and mineral element contents of tissues in yaks

Serum biochemical values and the wet weight to dry weight ratios of tissues were determined in yaks in Shandan county of Gansu province. The liver, kidney, heart and muscle contents of seven elements in yaks were also analysed. Most serum biochemical values were similar to those of cattle, camels and sheep, but the calcium concentration was considerably above the normal range for other ruminants. The liver contained the highest concentrations of copper, manganese and cobalt and the kidney of selenium, iron and calcium.Abbreviations Alb albumin - ALT alanine aminotransferase - AST aspartate aminotransferase - BUN blood urea nitrogen - Chol cholesterol - Glob globulin - -GT -glutamyl transpeptidase - IP inorganic phosphorus - TP total protein     

Avian brood parasitism — a growing research area in behavioral ecology (part Ⅱ)

正We are pleased to publish the second special issue on avian brood parasitism and to be responsible guest editors for the two special issues of Chinese Birds (Vol. 3, No. 4, 2012 and Vol. 4, No. 1, 2013), entitled "Avian Brood Parasitism - A Growing Research Area in Behavioral Ecology". The first issue was published in December 2012. The goal of the two special issues is to publish accumulated knowledge and some of the recent developments in