水胁迫条件下引物处理对巴西盾柱木种子萌发的影响

实验所用巴西盾柱木种子由圣保罗州Anhembi公司提供,种子经由98%的浓硫酸预处理15 min, 以打破物理休眠。分别在0.2%克菌丹溶液10 oC和27 oC下,-1.0 MPa聚乙二醇6000 10 oC和27 oC下,以及, 0.5 mol,0.75 mol,1.0 mol 硝酸钾溶液进行引物处理. 包括对照组种子,共8个实验处理,每一个处理5个重复,每一个处理实验用100粒种子,置于滤纸浸透引物聚乙二醇6000溶液的15厘米培养皿中,置于冰箱保持27oC恒温。实验引物渗透势为0.0, -0.2, -0.4, -0.6, -0.8, -1.0-MPa, -1.4 MPa. 实验同时将种子置于浸有引物聚乙二醇的卷纸中,观察水胁迫下的萌发情况。实验结果证明,随着聚乙二醇6000浓度的升高,巴西盾柱木种子萌发率降低,对照组萌发率比实验引物处理组高。聚乙二醇达到PEG -1.4 MPa,种子不能萌发。图2表3参10。     

甜叶菊葡糖基转移酶基因UGT76G2的克隆及生物信息学分析

本研究利用RT—PCR方法从甜叶菊（Stevia rebaudian）叶片中分离了与甜叶菊UGT76G1高度同源的UGT76G2基因，该基因编码一条分子量为52．029kD的由458个氨基酸残基组成的多肽，含有C-端所特有的高度保守的信号序列PSPG基序和N-端膜结合序列，属于植物中特有PSPG基序的UGT家族成员。半定量RT—PCR分析表明：UGT76G2在甜叶菊根、茎、叶、花不同组织中具有组织表达特异性，在叶组织中的表达丰度略高，在根中不表达而在茎中表达较低。推断的UGT76G2编码产物与其它参与植物次级代谢产物的糖基转移相关酶同源比对和系统发生分析表明该蛋白与康乃馨（Dianthus caryophyllus）DicGT4、棉花（Gossypium hirsutum）GhUGT1、甜叶菊（Stevia rebaudian）UGT76H1及玉米（Zea mays）BX8的一致性较高，分别为41％、35％、35％和32％。对UGT76G2和UGT76G1的次级结构和立体结构分析发现，苜蓿（Medicagosativ曲UGT71G1与二者的一致性皆为23％，它们有类似的次级结构。在C-端的PSPG信号区内具有10个相同的基质结合位点。但在UGT76G2和UGT76G1之间也有个别位置氨基酸存在差异。它们的N-端含有保守的组氨酸H25和天冬氨酸D124残基，可能与受体的结合有关。     

THE APPLICATION OF TECHNETIUM-99m HEXAMETHYLPROPYLENEAMINE OXIME (99mTc-HMPAO) LABELED WHITE BLOOD CELLS FOR THE DIAGNOSIS OF RIGHT DORSAL ULCERATIVE COLITIS IN TWO HORSES

The application of 99mTc-HMPAO labeled white blood cells to support the diagnosis of right dorsal ulcerative colitis was studied in two horses with a history and clinical signs consistent with phenylbutazone toxicity. These images were compared to a reference horse unaffected by right dorsal ulcerative colitis. Blood was collected aseptically in heparinized syringes from the patients for in vitro white blood cell (WBC) radiolabeling. The buffy coat was separated out and radiolabeled with 99mTc-HMPAO. The radiolabeled blood was re-injected i.v. and four images of the right and left side of the patient's abdomen were acquired at 4 hours and 20 hours post-injection. Results of the nuclear study revealed no abnormal findings in the abdomen at the four-hour post-injection images in any horse. Images obtained 20 hours post-injection revealed a linear uptake of radiolabeled WBCs in the right cranioventral abdomen in the region of the right dorsal colon in both horses with right dorsal ulcerative colitis. The reference horse had no radiopharmaceutical uptake in this region. This nuclear imaging study was a rapid, non-invasive method to identify right dorsal colon inflammation. These findings not only supported the diagnosis of right dorsal ulcerative colitis, but also facilitated appropriate medical management of each horse.     

Experimentally induced ovine border disease: extensive hypomyelination with minimal viral antigen in neonatal spinal cord

Border disease (BD) was experimentally induced in 9 lambs by inoculation of their dams with the BD-31 strain of border disease virus (BDV) at 50 days of gestation. These ewes developed serum-neutralizing antibody titers to BDV. The diagnosis of BD in their lambs was confirmed by hairy birthcoats, intrauterine growth retardation, tremors, and hypomyelination. Three clinically healthy age-matched control lambs, whose dams had been given an inoculum containing only BDV-free cell culture supernatant, were studied in parallel. There were significant differences in birth weights and in the lengths of the right tibiae and radii between the affected and the control lambs. There was a gradient in severity of clinical neurologic signs among the affected lambs, which directly correlated with the severity of hypomyelination in their spinal cords. However, the difference in severity of the neurologic deficits did not correlate with differences either in the precolostral serum-neutralizing antibody titers to BDV in these lambs or in the number of BDV antigen-containing cells in their spinal cords. Only approximately 0.01% to 0.3% of spinal cord cells, both in gray matter and white matter, were BDV antigen positive in the affected lambs. These results indicate that extensive infection of CNS cells with their subsequent destruction or functional alteration may not be a critical part of the pathogenesis of the hypomyelination in BD.     

Caprine encephalomyelomalacia

Six cases of encephalomyelomalacia in dairy goats 3 1/2 to four months of age are described. Neurologic signs had an abrupt onset and passed rapidly from ataxia to paralysis. All goats were killed after six to ten days and had spinal cord and brain stem lesions--always more extensive and severe in the cord. The bilaterally symmetrical necrotic lesions were restricted to the ventral and intermediate gray substance in the cord and to certain brain stem nuclei. The spinal cord enlargements were affected especially.     

Effects of sodium monensin on reproductive performance of dairy cattle. I. Effects on conception rates, calving-to-conception intervals, calving-to-heat and milk production in dairy cows

SUMMARY A total of 1061 lactating dairy cows in six different herds were randomly allocated to treatment and control groups. One herd was lot-fed on total mixed rations; three herds were fed on pasture with significant amounts of supplementary concentrates, and two herds were primarily pasture fed. Treated cows received a slow-release, intraruminal capsule containing 32 g sodium monensin within 7 days of calving. Conception rates at first service, days to first oestrus and calving-to-conception interval did not differ significantly between untreated and monensin-treated cows in the 5 herds, 3 herds and 4 herds, respectively, in which these outcomes were examined. Treatment of lactating cows immediately after calving may not be the optimal method to achieve fertility responses with capsules containing sodium monensin. Monensin treatment significantly increased milk yield in one of the six herds. Milk fat or milk protein production was not significantly affected by treatment.     

Plasma beta-endorphin and adrenocorticotrophin in young horses in training

A controlled period of submaximal exercise on a treadmill was used as a standardised stress test in 6 young horses to monitor the effects of training. Circulating plasma concentrations of immunoreactive beta-endorphin (IR beta-EP) were measured before, during and after the exercise period. The stress test was conducted on 3 occasions during an intensive training program lasting 14 weeks. In week 3 a marked increase in plasma IR beta-EP (P = 0.003) was demonstrated as a result of training, but by the last exercise test performed in week 9 no significant increase in plasma IR beta-EP concentrations could be detected. During the training period the basal concentrations of plasma IR beta-EP significantly decreased (P = 0.0059). Plasma adrenocorticotrophin (ACTH) did not increase during exercise, although there was a trend of decreasing basal plasma ACTH by the end of the training period. It was concluded that a standardised work test acted as a mild stress to unfit horses, but as the horses' fitness increased the hormonal response to exercise diminished. Basal plasma beta-EP concentrations were decreased with increasing fitness.     

Effects of sodium monensin on reproductive performance of dairy cattle. II. Effects on metabolites in plasma, resumption of ovarian cyclicity and oestrus in lactating cows

SUMMARY A randomised trial was conducted to determine the effects of sodium monensin on plasma metabolite concentrations, resumption of cyclicity and oestrus and milk production and milk composition of postparturient dairy cows. Cows treated with sodium monensin in a controlled-release capsule had significantly lower plasma β-hydroxybutyrate (BHB) concentrations (P = 0.006) and tended (P = 0.07) to have significantly higher plasma glucose concentrations than untreated cows. Treatment did not significantly influence plasma free fatty acid, urea nitrogen or cholesterol concentrations. Despite higher plasma glucose concentrations and lower plasma BHB concentrations, periods from calving to first ovulation and oestrus were not reduced by treatment. This observation, with limited numbers of cows, is not consistent with a hypothesis that glucose or ketones are important metabolic regulators of pulsatile release of luteinising hormone and consequent resumption of cyclicity. While milk production and milk protein concentration did not significantly differ between groups, milk fat concentration was significantly lower for treated cows. Treated cows probably had lower dry matter intake than untreated cows as they produced 67 litres less milk per head and lost more weight than untreated cows during the study period, although weight and body condition score were not significantly affected by treatment. The lack of significance of these latter observations probably reflects the low statistical power of the study.     

Administration of Thyroxine Affects the Morphometric Parameters and VEGF Expression in the Uterus and Placenta and the Uterine Vascularization but does Not Affect Reproductive Parameters in Gilts During Early Gestation

The aim of this study was to evaluate the effects of thyroxine administration on morphometric parameters, expression of vascular endothelial growth factor (VEGF) and vascularization in the uterus and placenta and reproductive parameters in gilts at 70 days of gestation. At 150 days of age, i.e., before first heat, 20 gilts were randomly divided into two experimental groups: treated (n = 10) and control (n = 10). The treated group received a daily dose of 400 μg of l ‐thyroxine (T₄) in their diet until slaughter and the control group received only typical meals. Before artificial insemination, blood was collected to determine plasma total T₄. The gilts were inseminated in the second oestrus and slaughtered at 70 days of gestation. The foetal thyroid follicular epithelium height, number, size and weight of foetuses; foetal myogenesis, corpora lutea number, embryonic mortality rate, uterine weight, placental weight and placental fluid volume were measured. Histomorphometric and immunohistochemical analysis of uterus and placenta were determined. The averages of all variables were compared by the Student’s t‐test. The gilts treated with thyroxine showed significant increase of plasma total T₄. At 70 days of gestation, the heights of the trophoblastic epithelium, endometrial epithelium and endometrial gland epithelium were significantly higher in the group treated with T₄. The expression of cytoplasmatic and nuclear VEGF in trophoblastic cells and the number of blood vessels per field in endometrial stroma were significantly higher in the gilts treated with T₄. No other significant differences between groups were obtained with respect to other parameters (p > 0.05). We conclude that oral administration of T₄ up to 70 days of pregnancy in gilts affects the morphometric parameters, the expression of placental VEGF and the uterine vascularization but does not affect reproductive parameters in gilts during early gestation.     

Livestock disease threats associated with intensification of pastoral dairy farming

This paper provides an overview of the changes in the pasture-based dairy systems of New Zealand and Australia that may influence the health of cattle.

There are relatively few available data that can be used to quantify the effects of increased intensification of milk production on the health of cattle. There is evidence that increased production increases the risk of mastitis and culling for udder health. Increased risks of mastitis with treatment with somatotropin support these findings; however, the risk of mastitis may decrease with increased milking frequency. Larger herds with greater stocking density should increase the risk for infectious disease, but evidence to support this contention is sparse.

Very intensive grazing patterns associated with higher grass yields achieved using better cultivars and greater use of fertilisers favour nematode parasites. There is some evidence of anthelmintic resistance in both nematodes and liver fluke. Veterinarians will need to be aware of the potential for these to reduce the productivity of cattle.

There have been benefits of improved nutrition on the efficiency of energy use for dairy production. Diseases such as bloat and ketosis appear to be of lower prevalence. It also appears that mineral nutrition of pasture-fed cattle is being better addressed, with gains in the control of milk fever, hypomagnesaemia and trace-element deficiencies. However, acidosis is a condition with a high point prevalence in pasture-based dairy systems where cows are fed supplements; one study in Australia found a point prevalence of approximately 11% of cows with acidosis. There is evidence from this study that the neutral detergent fibre (NDF) in pasture-based diets may need to be higher than 30% of the diet to maintain rumen stability. Laminitis and acidosis are different conditions with a similar pathogenesis, specifically highly fermentable diets. The prevalence of lameness was 28% in herds in Australia, suggesting that this condition must be a focus for preventive medical approaches, including the design of laneways, feedpads and dairies.