肌肉生长抑制素的研究进展及应用现状

肌肉生长抑制素基因是限制肌肉超常发育的负调控基因,缺失或突变会导致双肌现象的产生。本文重点探讨了肌肉生长抑制素的分子作用机理,论述了该基因的发现、遗传效应、同源性、组织特异性、定位和结构等方面的研究现状及临床应用。     

肌肉生长抑制素研究进展

肌肉生长抑制素是一种分泌型的多肽。小鼠中该基因的缺失可导致骨骼肌的明显增大,而且在双肌牛中该基因的缺失产生了突变,这表明肌肉生长抑制素可能是骨骼肌生长的负调控因子。本文综述了肌肉生长抑制素的基因结构及其分子作用机制,并就它对动物体成分的影响、应用及尚存在的问题作了概述。     

肌肉生长抑制素研究进展及其在家禽育种中的应用前景

肌肉生长抑制素(Myostatin,MSTN)是抑制肌细胞增殖与分化的关键基因,对骨骼肌生长发育起着负调控作用,还参与到机体脂肪沉积等其他生命过程中.在家禽生产中,产肉量和肉质是影响经济效益的重要指标,前者的主要影响因素是肌肉发育,后者的主要影响因素则是肌内脂肪分布.MSTN不仅能够调控肌肉生长,也能调控脂肪的发育,而...     

肌肉生长抑制素(MSTN)对肌肉调控的分子作用机制

肌肉生长抑制素(Myostatin,MSTN)是肌肉生长的负调控因子,抑制成肌细胞的增殖和分化.MSTN作为胞外信号分子可与成肌细胞膜上的受体结合引起受体自身的磷酸化,启动细胞内一系列信号传导过程,作用于生肌决定因子(MyoD)靶基因的调控区,调节肌肉组成蛋白和蛋白基因的表达.     

猪完整的生长抑制素基因的特性及在不同猪种中的表达

生长抑制素(MSTN)是生长因子β超家族成员,是肌肉生长发育的重要影响因子,是肌肉生长的负调控因子,并与所谓的牛的双肌表型有关。比利时的皮特兰猪是双肌表型的代表猪种,与双肌牛有着共同的肌肉表型,表明生长抑制素基因可能是猪肌肉过度增长的候选基因。本研究对5个品种45头猪的生长抑制素基因的完整序列进行了测定和分析,包括具有特别发达肌肉的皮特兰猪和肌肉欠发达的梅山猪和野猪。经测序,得到了7626 bp的猪生长抑制素基因,包括5′和3′非翻译序列,并且发现了15个多态位点,其中3个位于启动子区,5个位于内含子1内,7个位于内含子2内。大部分的突变位点是在对本试验获得的MSTN基因序列和已发表的猪生长抑制素基因进行比对时发现的。然而,定位于猪生长抑制素基因启动子区447位点处的突变位点在皮特兰猪中有很高的等位基因频率,而不是公认的肌细胞增强因子3结合位点。Sybr Green实时定量PCR检测结果显示,这个突变位点在4周龄猪的背最长肌中表达。     

品种和体重对猪肌肉生长抑制素表达的影响

本文旨在研究猪的体重和品种对其背最长肌的肌肉生长抑制素基因表达的影响,并对猪100kg时的胴体性状与肌肉肌肉生长抑制素基因表达量的相关性进行分析。试验采用荧光定量PCR方法,以β-actin基因为内标,研究不同体重(20、50和100kg)和品种(汉普夏猪和长白×撒坝猪)对猪背最长肌的肌肉生长抑制素基因表达的影响,同时考察试验猪在100kg时的胴体肉质指标。结果表明:①猪背最长肌中肌肉生长抑制素的表达随体重的增加呈上升的趋势(P>0.05);②相同体重条件下长撒猪背最长肌中肌肉生长抑制素表达均显著高于汉普夏猪(P<0.05),其中20kg时达到极显著水平(P<0.01);③肌肉生长抑制素的表达与瘦肉率呈极显著的负相关(P<0.01),与背膘厚则呈极显著的正相关(P<0.01),与滴水损失和肌内脂肪的相关性不显著(P>0.05)。本研究结果表明猪背最长肌的肌肉生长抑制素基因的表达量随体重增加而提高,品种间差异显著,并且肌肉生长抑制素基因的表达与瘦肉率、背膘厚存在显著的相关性。     

肌抑素基因的结构、功能及应用

肌抑素(myostatin)属于TGF-β超家族成员,是动物骨骼肌生长的主要负调控因子。对肌抑素基因及其功能的研究,有助于提高畜禽的产肉性能和肉品质,也有利于治疗人类肌萎缩症等肌肉疾病。另外,肌抑素还具有降低脂肪含量,修复骨组织等功能。本文对肌抑素基因的结构、功能及应用进行了简要概述。     

双肌性状形成的分子机理及其研究进展

肌肉生成是一个复杂的正负调控过程,双肌品种以其特有的饲料报酬高、瘦肉率高’、生长快在近几年来逐步受到育种专家的重视。研究表明,肌肉生长抑制素(mysatatin,MSTN)缺失或突变会导致肌肉过度生长或肥大,即双肌现象;双肌性状受常染色体上一对等位基因控制,存在主基因效应。现从肌肉生长机理入手,分别从不同家畜双肌现象阐明该性状的分子机理及其应用前景。     

肌肉生长抑制素对动物肌肉、脂肪和骨骼的影响

肌肉生长抑制素是转化生长因子 β超家族成员之一,具有众多的生理功能。近来的研究表明,肌肉生长抑制素除对肌肉生长有负调控作用外,还对脂肪的沉积和骨骼的生长发育具有调节作用,甚至还能影响肌腱和韧带的强硬度。本文主要从肌肉生长抑制素的结构、基因表达及其对动物肌肉、脂肪和骨骼的作用等方面进行综述。     

抑制素、活化素和卵泡抑素研究进展

抑制素、卵泡抑素和活化素是3种参与垂体促卵泡素调控过程的糖蛋白激素,随着对促卵泡素调控过程的深入了解,发现这3种蛋白在动物生殖周期中发挥着重要的作用。文章主要就抑制素、卵泡抑素和活化素的结构特征、生理功能以及抑制素和卵泡抑素对活化素生物学活性的抑制机理进行了综述。     

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.     

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.     

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.     

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     

Internal Parasites and Haematological Values in Cattle Slaughtered in Buea Subdivision of Cameroon

Tropical Animal Health and Production -