体细胞克隆猪的研究与展望

用体细胞核移植的方法生产的克隆猪诞生至今已近5年，虽然同胚胎细胞核移植相比，体细胞核移植技术难度大，成功率低，但近年来用体细胞核移植技术克隆猪有了更深入的研究，在体细胞核移植基本机理和关键技术上取得了一定的进展。综述了用核移植的方法生产体细胞克隆猪的技术关键和难点及应用情况，并对提高猪体细胞核移植效率的策略进行了分析。     

培养液添加物与去核方法对猪体细胞核移植效率的影响

综述了在卵母细胞的成熟、去核和后期发育过程中添加化学成分对体细胞核移植效率的影响,以期对改进体细胞核移植效率提供参考.     

分子育种手段之微卫星技术的应用与前景

在国内，1995年，西北农业大学窦忠英等用胚胎细胞核移植产生了6头猪。1996年，湖北农科院魏庆信等得到了胚胎细胞核移植猪。1997年赵浩斌等和2000年Li等分别获得猪胚细胞核移植后代1998年，东北农业大学的李光鹏等把猪胚胎的细胞核通过电融合移植到去核的体内和体外成熟卵母细胞中，出生了2头克隆猪。2003年，西北农林科技大学冯秀亮等得到了人体细胞和猪卵母细胞异种核移植囊胚。     

哺乳动物细胞核移植目前存在的问题

简要概括哺乳动物细胞核移植技术的应用前景，详细综述其目前存在的问题，认为对待细胞核移植技术的发展，应该理性分析。     

哺乳动物克隆技术研究进展及前景

本文简要回顾了动物克隆技术研究的历史，重点介绍了当代哺乳动物细胞核移植方法和进展情况、体细胞核移植的应用前景。     

哺乳动物胚胎细胞核移植克隆技术的研究进展

对哺乳动物胚胎细胞核移植克隆技术的基本环节，以及细胞周期阶段对细胞核移植克隆胚胎效率影响的研究进行系统综述     

哺乳动物胚胎细胞核移植克隆技术的研究进展

对哺乳动物胚胎细胞核移植克隆技术的基本环节，以及细胞周期阶段对细胞核移植克隆胚胎效率影响的研究进行系统综述。     

影响猪体细胞核移植效果的因素

克隆技术的研究已经取得了丰硕的成果,但猪体细胞核移植还受到众多因素的制约,克隆效率仍然较低,文章针对猪体细胞核移植的各项技术环节及影响因素进行探讨与分析,以期加快猪体细胞核移植技术的研究,提高猪体细胞核移植效率,进一步促进猪体细胞核移植技术的发展和运用。     

提高猪核移植效率的研究进展

哺乳动物体细胞核移植(克隆)经过多年的发展，获得了多种后代。猪的核移植研究意义重大，应用价值颇高，是当今生物技术的热点研究之一。尽管猪核移植已取得了很大进展，但移植效率依然很低。本文就目前已有的资料，综述了提高猪体细胞核移植效率的各项技术环节的研究进展。     

表观遗传修饰影响哺乳动物体细胞核移植效率的研究进展

表观遗传修饰是一种不依赖于DNA序列变化的可逆、可遗传修饰，在哺乳动物胚胎发育的整个阶段均可发生，是影响哺乳动物体细胞核移植效率的主要因素之一。其中，DNA甲基化、组蛋白的动态修饰、X染色体失活、端粒与端粒酶活性变化作为常见的表观遗传修饰类型，任一修饰形式的异常都会影响基因的表达，引发体细胞重编程错误导致核移植效率降低。近年来，随着体细胞核移植技术研究的不断深入，表观遗传修饰影响体细胞核移植效率的关键作用机制日益明确。本文通过综述不同类型的表观遗传修饰影响哺乳动物体细胞核移植效率的研究进展，以期在表观遗传修饰层面为提高哺乳动物体细胞核移植效率提供新思路。     

Evidence for the non-involvement of the uterus in the lifespan of the corpus luteum in the cyclic dog

Progesterone levels in peripheral blood of dogs were analysed during the cycle in which hysterectomy (n = 5) or sham surgery (n = 3) was performed as well as during the cycle of dogs (n = 5) hysterectomized at least one year prior to this study; the data were compared with the findings in control dogs (n = 3). The averages of the duration of the luteal period observed in the three experimental groups were not significantly different from those of control dogs. Immediately after surgery, the progesterone level decreased from 25 to 50% of the presurgical level, but returned to presurgical level in about four days. Prolactin levels were elevated for about 30 h after surgery. Nevertheless, the averages of the mean prolactin levels for each animal during the luteal period of the experimental groups were not significantly different from those of control dogs. It is concluded that in the dog, the uterus is not involved in the lifespan of the cyclic corpus luteum.     

Studies on the Appearance of the Centres of Ossification of the Axial Skeleton in the Feline Foetus

ossification of the vertebral column, ribs, sternum and skull of the foetuses of cats was studied radiographicaly. All individuals from 90 litters were radiographed both fresh and after impregnation with silver nitrate. Other were subjected to histologically examination and alizarin red straining. The ages of the litters were estimated using crown-rump length. Thje range of ages was from day 24 after mating to day 63. The times of observation of the first appearance of the centers of ossification were notedc using various techniques and both these times and all the centers for the axial skeleton appearing during foetal life were tabulated. A survey of the relevant literature is also given.     

A study of the radiographic anatomy of the cervical spine in the dog

Cervical radiographs, with the neck in varying positions, were made of a series of dogs belonging to different breeds, all with conditions unrelated to the spine. Post-mortem myelograms were carried out on a small number, and the cervical vertebrae macerated. Measurement of cervical angles, and sagittal diameters of the neural canal were obtained from the plain radiographs. The relative positions of adjacent vertebrae were noted. The sagittal diameter values were compared with those calculated from the myelograms and isolated vertebrae.
The vertebral angles showed a wide variation, the vertebrae moved relatively to one another as the position of the neck was varied, and the sagittal diameters showed good correlation between plain radiographs, myelograms and isolated vertebrae.     

Quantitation of the pharyngoesophageal sphincter in the dog

The pressure and length of the pharyngoesophageal sphincter were studied in 5 healthy dogs that were awake and then immobilized with xylazine. During successive tests, a single side-hole catheter was mechanically withdrawn and rotated 90 degrees. Similar pressures were measured, regardless of the orientation of the catheter side hole. The mean pressure and length of the pharyngoesophageal sphincter of the awake dogs were 18 mm of Hg and 1.8 cm, respectively. After the dogs were immobilized with xylazine, the mean pressure and length were 8 mm of Hg and 1.7 cm, respectively. In 2 dogs immobilized with xylazine, there was no change in the maximum resting pharyngoesophageal sphincter pressure or length of the pressure zone after IV administration of edrophonium chloride, succinylcholine chloride, or thiamylal sodium. Seemingly, xylazine was not a suitable agent for immobilization of clinical patients for pharyngoesophageal manometry.     

Normal Postpartum Involution of the Uterus in the Dog

Ninety-eight reproductive tracts from dogs at different postpartum time periods were used to investigate stages of normal involution. Seventy-eight reproductive tracts were obtained from the field, and 20 obtained surgically for gross and microscopic examination. Plasma progesterone was measured in 22 dogs at various times postpartum.

The uterine horns during the first week postpartum were dilated and edematous. The placental sites were 1.5-3 cm in width, rough, granular and covered with mucus and a few blood clots. By the fourth week the placental sites were thick, grayish-tan and nodular with a few blood clots within nodules. The uterine horns during the seventh week were greatly contracted and the placental sites were narrow and light in color. A few nodules were still present on the surface. By the ninth week the uterine horns were uniform in shape and contracted with a narrow lumen. The placental sites appeared as a narrow brown band.

Histologically the placental sites during the first week postpartum were covered by an eosinophilic staining necrotic mass and a few intact epithelial cells scattered on the surface as an interrupted single layer. Under the necrotic mass, large eosinophilic staining cells in moderate number were scattered throughout the lamina propria of the placental site. These cells were considered to be decidual cells. By the fourth week the placental sites were covered by a large lobulated mass of collagen fibers. The uterine glands were greatly dilated and degenerate, and mononuclear cell infiltration in the lamina propria was pronounced. By the seventh week, large masses of collagen fibers were detached from the surface, and endometrial glands were normal in size and shape. By the ninth week surface sloughing was completed. However, regeneration and replacement of the endometrial lining from the mouth of the uterine glands continued until the end of the twelfth week when the involution process was completed.

The progesterone levels were very low for eight weeks postpartum.

     

The influence of the width of the saddle tree on the forces and the pressure distribution under the saddle

As there is no statistical evidence that saddle fit influences the load exerted on a horse's back, this study was performed to assess the hypothesis that the width of the tree significantly alters the pressure distribution on the back beneath the saddle. Nineteen sound horses were ridden at walk and trot on a treadmill with three saddles differing only in tree width. Kinetic data were recorded by a sensor mat. A minimum of 14 motion cycles were used in each trial. The saddles were classified into four groups depending on fit. For each horse, the saddle with the lowest overall force (LOF) was determined. Saddles were classified as "too-narrow" if they were one size (2 cm) narrower than the LOF saddle, and "too-wide" if they were one size (2 cm) wider than the LOF saddle. Saddles two sizes wider than LOF saddles were classified as "very-wide". In the group of narrow saddles, the pressure in the caudal third (walk 0.63 N/cm(2)+/-0.10; trot 1.08 N/cm(2)+/-0.26) was significantly higher compared to the LOF saddles (walk 0.50 N/cm(2)+/-0.09; trot 0.86 N/cm(2)+/-0.28). In the middle transversal third, the pressure of the wide saddles (walk 0.73 N/cm(2)+/-0.06; trot 1.52 N/cm(2)+/-0.19) and very-wide saddles (walk 0.77 N/cm(2)+/-0.06; trot 1.57 N/cm(2)+/-0.19) was significantly higher compared to LOF saddles (walk 0.65 N/cm(2)+/-0.10/ 0.63 N/cm(2)+/-0.11; trot 1.33 N/cm(2)+/-0.22/1.27 N/cm(2)+/-0.20). This study demonstrates that the load under poorly fitting saddles is distributed over a smaller area than under properly fitting saddles, leading to potentially harmful pressures peaks.     

Contributions of the glossopharyngeal nerve and the pharyngeal branch of the vagus nerve to the swallowing process in dogs

The separate contributions of the glossopharyngeal nerve and the pharyngeal branch of the vagus nerve to the innervation of the pharyngeal muscles were studied first in 10 canine cadavers by dissection of the pharyngeal plexus and the pharyngeal muscles. In 10 other dogs, the parent trunks and 1st division of the glossopharyngeal nerve and the pharyngeal branch of the vagus nerve were electrically stimulated. The evoked stimulation potentials were recorded from the stylopharyngeal, hyopharyngeal, thyropharyngeal, and cricopharyngeal muscles. One of the parent trunks was then transected, and the effects on the swallowing process were observed clinically and by contrast videofluorography. Denervation potentials resulting from nerve transection were recorded in the soft palate, the hyopharyngeal, thyropharyngeal, and cricopharyngeal muscles. The pharyngeal plexus was composed of branches originating from the glossopharyngeal nerve and the pharyngeal branch of the vagus nerve. In most dogs, the pharyngeal muscles and the soft palate were innervated ipsilaterally by both nerves. The swallowing process was more severely disturbed after bilateral transection of the pharyngeal branch of the vagus nerve than after bilateral transection of the glossopharyngeal nerve.     

Morphometric studies of the proximal tubules of the rat kidney considering the effect of the method of killing]

120 male rats belonging to two different strains (Han: WIST, Han: SPRD) and two different weight groups (group I: lighter body weight, group II heavier body weight) were killed on three different methods (decapitation, Nembutal -overdose greater than 250 mg/kg b.w. i.p. less than, exsanguination in Nembutal -anaesthesia greater than 100 mg/kg b.w. i.p.). Subsequently, changes in tubuli contorti I of the left kidneys were examined morphometrically. The mean total area, luminal area and epithelial area were evaluated as well as the mean diameter of the tubular nuclei. Concerning the areas of the proximal tubules only the luminal areas show differences between the Wistar and the Sprague-Dawley strain. The total, luminal and epithelial area in the rats belonging to the weight group II were significantly larger than in the rats belonging to weight group I. With one exception this could be noticed within both strains and all three modes of killing. In both strains and weight groups the rats were killed by Nembutal -overdose or exsanguination showed significantly smaller total, luminal and epithelial areas than the rats that were decapitated. Possible cause heretofore are discussed. Differences between the tubular areas of the rats that were killed by Nembutal -overdose and those that were killed by exsanguination after Nembutal -anaesthesia could not be established. The measurements of nuclei diameters in the proximal tubules did not lead to clearly different results between both strains, weight groups and the various modes of killing.     

陕北白绒山羊繁育中心羊场绒山羊日粮的评价

试验选择陕北白绒山羊繁育中心羊场的成年健康母羊（怀孕前期）16只,育成母羊13只,育成公羊13只,空腹称重。测定每只羊1d的采食量,计算其摄入的营养成分含量,并与原苏联绒用山羊饲养标准比较,进行饲养水平评价。结果显示,与饲养标准比较,陕北白绒山羊繁育中心羊场的育成母羊代谢能高2．68MJ,粗蛋白低59．29g,钙低3．00g,磷低1．52g;育成公羊代谢能高3．47MJ,粗蛋白低81．92g,钙低4．42g,磷低2．62g;成年母羊代谢能高2．51MJ,粗蛋白低91．33g,钙低3．09g,磷低1．93g。结合羊的体况综合评价饲养水平基本合理,但尚需要按饲养标准增加粗蛋白、钙、磷等营养物质的供给量。     

On the parafollicular cells in the thyroid gland of the bovine foetus

The thyroids of 117 bovine foetuses were studied by some histochemical and selective staining methods with respect to the occurrence of parafollicular cells. Furthermore, 7 foetuses were studied by electron microscopy. The length of the foetuses varied from 6 to 72 cm corresponding to an estimated age of about 2 to 9 months. Parafollicular cells were observed in the thyroids of all foetuses examined. The ultrastructure of the parafollicular cells in the foetuses differed very little from that described in adult animals. Histochemically, Luxol fast blue positive phospholipids and α-glycerophosphate dehydrogenase activity could be observed in the cells. The Solcia-Sampietro method gave positive results in most of the foetuses examined. The reactions observed at light microscopic level were rather faint in the youngest foetuses. The functional aspects of the results are discussed.