水稻突变群体的构建及功能基因组学

随着水稻基因组全序列的测定完成，功能基因组学已成为重点研究内容。功能基因组学主要研究生物有机体内各基因的生物学功能进而了解所有基因如何协调发挥作用完成一系列的生长发育过程。目前已经发展了多种分析鉴定基因功能的方法，其中最直接最有效的方法是构建饱和的基因突变群体，通过突变体分析鉴定基因功能。本文主要阐述了各种构建方法及其优缺点以及在功能基因分离鉴定上的应用。自发突变的频率极低，且自发突变基因的分离难度比较大，只能作为突变群体构建的辅助方法。利用EMS等化学诱变剂可以在短时间内构建大量点突变群体，并可用TILLING进行突变检测，但多位点的点突变使突变表型难以鉴定。由快中子等物理诱变也可以在短时间内构建大量缺失突变体，且可用Ddeteagene系统进行检测；但多基因缺失、多位点缺失和内含子缺失等使突变表型的分析可能无法进行。利用T—DNA、转座子和反转录转座子等构建插入突变体已经成为突变库构建的主要方法。T—DNA插入已成功应用于水稻大规模突变体的构建，但只限于转基因效率较高的品种；T—DNA在基因组中整合的复杂性以及转基因过程中由组织培养等引发的突变等，增加了突变体表型和分子分析的难度。Tos17是目前应用最为成功的反转录转座子，但多拷贝的插入使突变体的表型鉴定和分子鉴定较为困难，因为只有10％左右的突变性状是由Tos17插入引起的。理论上，Ac／Ds双因子系统是目前最理想的水稻插入突变库构建体系，Ds的单拷贝插入，大大方便了突变体的表型分析和分子鉴定；Ds的回复突变，可以验证突变表型是否由Ds插入引起；但在血转座酶驱动下Ds可能发生的多次跳动所形成的痕迹(footprint)也可能影响突变表型的分析。RNAi可以有效地使目标基因沉默，但并不是所有基因均可被RNAi沉默；对多因一效基因或同源性较高的基因家族，RNAi会同时作用这些基因，沉默表型很难鉴定。可见，每一种方法都有各自的优缺点，但不同的方法是可以互补的，通过各种方法是能够构建成理想的水稻突变库的。     

Primary hypoparathyroidism in two horses

Two Thoroughbred horses were presented with various clinical signs which included sweating, agitation, muscle twitching and synchronous diaphragmatic flutter. These signs were associated with profound hypocalcaemia. A diagnosis of primary hypoparathyroidism was made on the basis of low serum ionised calcium concentration, hyperphosphataemia and markedly reduced serum immunoreactive parathyroid hormone concentrations in the presence of normal renal function. Treatment with a combination of intravenous calcium and subsequently oral calcium, magnesium and a vitamin D analogue (dihydrotachysterol) for up to 65 days resulted in complete remission of clinical signs. Horse 1 was euthanased 12 months after the initial recognition of signs. Results of necropsy were unremarkable apart from an absence of detectable parathyroid tissue. Horse 2 returned to athletic activities while receiving only maintenance doses of oral calcium carbonate.     

Nonsurgical management of type II fractures of the distal phalanx in 48 Standardbred horses

OBJECTIVE: To evaluate nonsurgical management of type II fractures of the distal phalanx in Standardbred horses. DESIGN: Retrospective study of 48 affected horses. RESULTS: Most fractures occurred on the lateral palmar process of the left forelimb or the medial palmar process of the right forelimb; 81% of horses were considered sound enough to return to training and 63% raced. Of those returning to racing, 41% competed in > 10 races, 37% in 2 to 10 races and 22% in only 1 race. There was no difference in performance before and after fracture. Twenty-four of 25 horses had a bar shoe fitted for > 50% of the treatment phase. Of those horses returning to training without a bar shoe, 89% refractured at the same site. Sixty percent of horses returning to training with a bar shoe raced successfully. The total convalescent time, the time rested in a box and the time spelled in a paddock were similar for horses returning to racing and those that did not. The age of the horse had no effect on the ability to return to racing. CONCLUSION: The prognosis for type II fractures of the distal phalanx is guarded. It is advisable to fit a bar shoe on the horse during convalescence. Horses returning to training and racing with a bar shoe appear less likely to refracture the distal phalanx. Those horses that return to racing can perform at a level similar to that prior to fracture.     

Prosthetic Coxofemoral Joint Repiacement in the Goose (Anser Sp.): I. Preliminary Results

In order to study failure modes of fixation of artificial hip joints in man, an animal model was needed that had similar loading conditions concerning the hip joint and a life expectancy long enough to allow for fixation failures to occur. Femoral components of a hip joint were implanted into domestic geese ( Anser sp.) to evaluate their suitability for long-term in vivo studies of femoral implants. A prosthesis was developed. It was implanted into mature geese under general anesthesia using a lateral surgical approach. The animals were sacrificed 5 to 11 months after implantation. The results indicate that prosthetic hip joints could be implanted and that joint function was restored in all cases. There was no postoperative morbidity or mortality. Prosthetic loosening was observed in three out of the nine implants.     

SHORT CONTRIBUTION: The latest endangered species in Australia: A tobacco-smoking veterinarian

The results of a tobacco smoking survey conducted among veterinarians in Queensland, Australia, during 2007 are presented. Of the 567 participants only 3% reported being current smokers, 24% were ex-smokers and 73% had never smoked. The prevalence of smoking was similar among males and females, and the highest smoking rate was reported among veterinarians aged 31–40 years. However, the rate of never-smokers was strongly and negatively correlated with age, and the proportion of ex-smokers increased with age. Encouragingly, the results from this study suggest that tobacco use has all but disappeared from the Australian veterinary profession in recent years.     

Plasma cortisol concentrations in normal dogs given hydrocortisone sodium succinate

OBJECTIVE: To evaluate the effects on plasma cortisol concentration of a continuous infusion of a readily available steroid with equipotent glucocorticoid and mineralocorticoid effects. PROCEDURE: Plasma cortisol concentrations were measured before and regularly after hydrocortisone sodium succinate was administered as a continuous intravenous infusion over 6 h at 0.32 and 0.65 mg kg-1 h-1 to 12 healthy dogs weighing 12 to 22 kg. RESULTS: The infusion at both does rates produced significant and stable increases in plasma cortisol concentrations. The plateau concentrations produced by the large and small doeses were respectively above and below plasma cortisol concentrations likely to provide adequate glucocorticoid and mineralocorticoid activity in stressed dogs with significantly decreased adrenal function. CONCLUSION: This paper presents information regarding the changes in plasma cortisol concentrations in 12 normal dogs given an hydrocortisone sodium succinate infusion at two dose rates. The marked and continuous increase in plasma cortisol concentrations suggests a continuous HSS infusion may be a possible alternative to desoxycorticosterone acetate and dexamethasone in the treatment of acute adrenal dysfunction.     

OTOLITHIASIS IN THREE DOGS

Mineral opacities within the tympanic bullae, termed otoliths, were detected in three dogs by means of radiography and computed tomography. Radiographic signs of otitis externa were present in two dogs. One dog had clinical signs of vestibular disease, whereas the other two dogs had no clinical evidence of ear disease. Otolithiasis may represent mineralized necrotic material of a current or previous case of otitis media.     

DDGS和酵母培养物对奶牛生产性能和乳成分的影响

选择16头泌乳天数为127±52d经产荷斯坦泌乳牛用于评价酵母培养物(达农威益康XP)和玉米酒糟及其可溶物(DDGS)在试验日粮中含有限草料纤维数量(草料中的中性洗涤纤维含量为19.3%,干物质基础)之情况下对产奶量和乳成分的影响及其它们之间的互作效应。本次试验采用4重复4×4拉丁方设计,试验时间为4个星期。处理组均按照2×2因子排列而设定,其中:1)日粮中不含酵母培养物和DDGS(对照组);2)日粮中含有20%DDGS,无酵母培养物(DDGS组);3)日粮中含有60g/d的酵母培养物益康XP(XP组);4)日粮中含有20%DDGS和60g/d的益康XP(XP+DDGS组)。本次试验结果表明:各处理组之间对奶牛体重和体况评分无显著的影响。日粮的处理并不影响干物质采食量(DMI),在使用草料纤维含量较低且添加20%DDGS的日粮情况下乳脂率会降低。添加益康XP的确能够提高产奶量及乳蛋白产量,但却不能够完全阻止因DDGS所造成的乳脂率下降的趋势。无论日粮中是否含有DDGS,益康XP都能够提高奶牛的生产性能。     

RADIOGRAPHIC DIAGNOSIS OF LAMENESS IN AFRICAN ELEPHANTS (LOXODONTA AFRICANA)

Lameness in captive elephants is most commonly caused by pododermatitis or degenerative joint disease. Hard surfaces such as concrete, which produce a damp and cold environment, wet and muddy conditions, as well as restricted movement are the major causes of these problems. Radiography was performed in two African elephants at the Schoenbrunn Zoo in Vienna to determine the cause and extent of lameness. Various radiographic techniques are described for use in trained elephants. Low time settings were used to avoid loss of detail through movement and to minimize exposure while observing radiation safety. A 37-year-old elephant had front limb lameness due to an interdigital abscess. In radiographs of the foot an inhomogenous soft-tissue swelling without involvement of the phalanges was seen. Ultrasonography was helpful in visualizing the fluid-filled abscess. In additional joint radiographs severe degenerative joint disease was identified. A 13-year-old elephant had lameness of the hind limb. Radiographs of the hind limb from the foot to the stifle were made. Open physes and early signs of degenerative joint disease were identified on the radiographs.