不同改良措施的研究综述

由于自然因素及人为因素的共同作用,使得我国植被退化日趋严重.综合前人不同的研究成果,探讨了不同改良措施对退化植被的影响。     

无菌动物技术管理—无菌小鼠繁殖管理与监测

从日本中央实验动物研究所购买的２对ＩＱＩ无菌小鼠饲养在无菌隔离器中,饲养温度为２２～２４℃,相对湿度为５８～６０％,并成功地繁殖了２１４只无菌小鼠。无菌检验每２月进行一次,共检验４次,结果均为无菌生长。对鼠肝炎病毒和仙台病毒进行监测,结果为阴性。无菌小鼠剖解肉眼观察其盲肠巨大。     

Current status of genetic transformation technology developed in cucumber (Cucumis sativus L.)

Genetic transformation is an important technique for functional genomics study and genetic improvement of plants. Until now, Agrobacterium-mediated transformation methods using cotyledon as explants has been the major approach for cucumber, and its frequency has been up to 23%. For example, significantly enhancement of the transformation efficiency of this plant species was achieved from the cotyledon explants of the cultivar Poinsett 76 infected by Agrobacterium strains EHA105 with efficient positive selection system in lots of experiments. This review is to summarize some key factors influencing cucumber regeneration and genetic transformation, including target genes, selection systems and the ways of transgene introduction, and then to put forward some strategies for the increasing of cucumber transformation efficiency. In the future, it is high possible for cucumber to be potential bioreactor to produce vaccine and biomaterials for human beings.     

铬对肉仔鸡生长性能、血清生化特性、免疫功能和胴体品质的影响

用294只3周龄Arbor Acres(AA)商品代肉公鸡进行试验,研究玉米-豆粕型基础日粮中添中两种铬源（三氯化铬和酵母铬）及4个铬添加水平（0、0.4、2.0和10.0mg/kg）对肉仔鸡生长性能、血清生化特性、免疫功能和胴体品质的影响。试鸡共分7组（两铬源共用零添加组）,试验期3周。结果表明,三氯化铬在提高肉仔鸡饲料转化效率及法氏囊相对重量上比酵母铬更有效（P < 0.10）,其余多数性能指标在两铬源间无显著差异(P > 0.10);日粮中添加2.0和10.0mg/kg水平铬可显著提高肉仔鸡的血清新城疫抗体效价和胸肌率(P < 0.05),铬水平对其余多数指标无影响(P > 0.10);除胸肌率(P < 0.03)外,其余指标均未观测到铬源与铬水平的互作(P > 0.10)。     

饲粮中锰(Mn)的缺乏与过量对肉仔鸡性能的长期影响

用1日龄AA肉用雏鸡120只(公母各半),分成3组,分别喂以含Mn 16ppm(缺Mn组)的玉米-豆饼型基础饲粮和含Mn 120ppm(对照组)及2840 ppm(Mn过量组)的补Mn饲粮8周。结果表明,与对照组比较,实用饲粮Mn缺乏降低鸡的体增重(P>0.05)和跖骨灰、肝、胰、心、脾、胆汁(P<0.01)及肌肉(P>0.05)中的Mn含量与心组织含Mn超氧化歧化酶(MnSOD)活性(P<0.01),显著提高腿病发生率和心含CuZn超氧化歧化酶(CuZnSOD)活性(P<0.01),单位增重的耗料量(F/G)有增加趋势(P>0.05);Mn过量降低鸡采食量和体增重(P<0.01),提高上述组织和胆汁中的Mn含量(P<0.01),单位增重的耗料量(F/G)也有增加趋势(P>0.05),而对腿病发生率与心MnSOD及CuZnSOD活性无进一步影响(P>0.05)。     

Effect of dietary copper on intestinal mucosa enzyme activity, morphology, and turnover rates in weanling pigs.

Twenty-four pigs from four litters weaned at 21 d of age (6.6 kg of BW) were used to evaluate the influence of 250 ppm of dietary Cu on intestinal mucosa glucose-6-phosphatase (GP), alkaline phosphatase (AP), and adenosine triphosphatase (ATPase) activity; mucosal morphology; and the turnover rate of the intestinal mucosa throughout the gastrointestinal tract. Pigs were allotted into four pens of six pigs each based on sex, litter, and weight. Pens were then assigned to one of two treatments: 1) corn-soybean meal-whey diet with no antimicrobials (CO), or 2) CO + 250 ppm of Cu. Pigs were fed twice daily an amount approximately equal to ad libitum intake for 14 d. On d 14, pigs were injected i.p. with [3H]thymidine (50 microCi/kg of BW) 10 h after the morning meal. One pig from each pen was euthanatized at 1, 6, 12, 20, 32, and 44 h postinjection, and intestinal tissue was collected from the duodenum, two jejunum sites (upper and lower), ileum, cecum, and colon. The activity of GP and AP in the lower jejunum tended to decrease in pigs fed Cu (P less than .11, P less than .08, respectively). The ATPase activity was not affected by treatment (P greater than .10). Crypt death, villus height, or epithelial cell size (P greater than .10) were not affected by feeding Cu. Migration rate of epithelial cells up the villus was also not affected by treatment (P greater than .10).(ABSTRACT TRUNCATED AT 250 WORDS)     

Enhanced immune response with foot and mouth disease virus VP1 and interleukin-1 fusion genes

The capsid of the foot and mouth disease (FMD) virus carries the epitopes that are critical for inducing the immune response. In an attempt to enhance the specific immune response, plasmid DNA was constructed to express VP1/interleukin-1α (IL-1α) and precursor capsid (P1) in combination with 2A (P1-2A)/IL-1α under the control of the human cytomegalovirus (HCMV) immediateearly promoter and intron. After DNA transfection into MA104 (monkey kidney) cells, Western blotting and an immunofluorescence assay were used to confirm the expression of VP1 or P1-2A and IL-1α. Mice were inoculated with the encoding plasmids via the intradermal route, and the IgG1 and IgG2a levels were used to determine the immune responses. These results show that although the immunized groups did not carry a high level of neutralizing antibodies, the plasmids encoding the VP1/IL-1α, and P1-2A/IL-1α fused genes were effective in inducing an enhanced immune response.     

宁夏南部黄土丘陵区天然退化草地改良效果的研究

以位于宁夏南部黄土丘陵区的彭阳县为研究对象,通过采取“88542”整地+播种、施肥、封育等不同的调控措施,旨在寻求一种适合该区天然退化草地改良的最佳途径。结果表明:施肥和封育都可以明显地提高植被的地上生物量和盖度值、群落多样性指数,且施肥效果较明显,而在坡度大于15°的天然退化草地上,“88542”整地+播种效果尤为明显。     

Effects of zeolite a or clinoptilolite in diets of growing swine

Growth, nutrient balance, plasma ammonia levels and urinary p-cresol excretion were evaluated in growing pigs fed diets containing various levels of zeolite A or clinoptilolite. In one growth trial, crossbred pigs averaging 25 kg initial body weight were assigned to diets containing no zeolite, .3% zeolite A or .5% clinoptilolite for a 6-wk growing phase trial. Average daily gain (ADG), average daily feed intake (ADF) and feed/gain (F/G) were unaffected by supplementation of either zeolite in the diet, but metabolizable energy (ME) utilization was improved by feeding diets containing either zeolite. A second growth trial utilized the same crossbred pigs, which averaged 65 kg initial body weight, and were assigned to diets containing no zeolite, 1% zeolite A or 5% clinoptilolite for an 8-wk finishing phase trial. Average daily gain, ADF, and ME utilization were unaffected by feeding either zeolite diet, while F/G was increased in pigs fed the diet containing 5% clinoptilolite. In two nutrient balance trials, 16 crossbred pigs averaging 7.5 kg in initial body weight were fed diets containing 0, 1, 2 or 3% zeolite A in one trial and 16 crossbred pigs averaging 7.0 kg initial body weight were fed diets containing 0, 2.5, 5.0 or 7.5% clinoptilolite in a second trial. In both trials, digestible energy, ME, N-corrected ME and ME corrected for N balance and zeolite levels were linearly reduced as increasing amounts of either zeolite were fed. Daily fecal N increased and apparent digestibility of N was linearly reduced by feeding increasing amounts of zeolite A or clinoptilolite. Biological value of protein was improved linearly as higher levels of zeolite A were fed, indicating that there may be some ammonia binding to zeolite A in the gastrointestinal tract. Net protein utilization was reduced by feeding increasing levels of clinoptilolite in the diet. Calcium, P, Mg, Na, K and Fe retentions were linearly reduced by feeding increasing amounts of zeolite A in the diet, while increasing levels of clinoptilolite caused only P retention to be linearly reduced. Both free and conjugated forms of urinary p-cresol were linearly reduced by feeding increasing levels of clinoptilolite. Plasma ammonia levels were reduced at subsequent bleedings after a meal and by increasing levels of clinoptilolite.     

Effect of liver enzyme induction on paraoxon metabolism in the rat

Orally administered [1-¹⁴C]ethyl paraoxon, O,O-diethyl-O-p-nitrophenyl phosphate, is readily absorbed from the gastrointestinal tract of male albino rats. Radioactivity is essentially eliminated in 72 hr by excretion into urine and feces and by expiration as ¹⁴CO₂. Compounds with radioactivity in the urine are tentatively identified as diethyl phosphoric acid, desethyl paraoxon, ethanol, metabolites conjugated with amino acids, and paraoxon; the first compound is the predominant radioactive metabolite. Intraperitoneally injected phenobarbital, DDT, dieldrin, and endrin are inducers of microsomal enzymes that degrade paraoxon. The aryl phosphate-cleaving activity in vitro is not dependent on the addition of NADPH. O-Dealkylation of paraoxon is catalyzed by microsomal enzymes that require NADPH and oxygen and are inhibited by carbon monoxide. Microsomal enzymes from rats pretreated with enzyme inducers give an increased rate of O-dealkylation of paraoxon. Reduced glutathione has little or no effect on paraoxon degradation by either microsomal or soluble enzymes. Actinomycin D inhibits O-dealkylation of paraoxon in vivo, as indicated by reduction of ¹⁴CO₂ formation, and in vitro, as indicated by decreased activity of microsomal O-dealkylase. The role of microsomal mixed-function oxidases and NADPH-dependent O-dealkylase in the metabolism of organophosphorus insecticides is discussed.