新疆扁桃花粉萌发及花柱离体培养试验研究

对‘纸皮'、‘双果'、‘克西'、‘麻壳'、‘267'共5个扁桃品种进行花粉萌发试验,结果表明‘纸皮'花粉萌发率最高,为84.83%。‘克西'的萌发率最低,为0.65%。通过对5个品种自交和杂交授粉后的花柱进行离体培养可以看出,自交时,‘双果'ב双果'的自交组合优势最为明显;杂交时,‘双果'ב纸皮'的授粉组合优势最为明显。     

广西青贮玉米生产的优势、问题及建议

发展青贮玉米对畜牧业发展具有积极的作用。通过实地调研和查阅有关资料发现,广西青贮玉米生产具有政策层面、生态环境、市场需求、优质饲料缺口大、效率高、品质好等方面的优势,但广西青贮玉米生产也存在缺乏优质专用型青贮玉米品种、技术落后、生产及收获加工机械化程度低和效率低等问题。广西要立足资源优势,用好用足各类支持和鼓励政策,制定适宜本地青贮玉米发展的具体措施,积极开展青贮玉米优质专用型新品种的选育和审定等科研联合攻关,推广应用青贮玉米新品种,强化青贮玉米种植生产的技术培训和展示观摩,提高青贮玉米生产的规模化和机械化水平,大力发展青贮玉米,促进畜牧业健康发展。     

不同品系西方蜜蜂基因组DNA多态性图谱构建及杂交分析

本研究应用随机引物K（5'-CGGCCCCTGT-3'）对不同品系西蜂的基因组DNA扩增，获得了能区分不同品系西蜂的多态性DNA图谱，从多态性图谱中选取一个共同片段K1680bp，标记成探针，探针K1680bp与不同品系西蜂的基因组DNA匀有杂交，从而证明片段K1680bp是西蜂蜂种的共性，为西蜂的鉴定提供了直接依据。     

稻虱净对家蚕毒性和安全性评估

在稻桑混栽区，施用浓度约１０００ｐｐｍ稻虱净时，将被污染的桑叶饲蚕，或在实验室用约１０００ｐｐｍ稻虱净从一龄蚕连续添毒，均能对家蚕造成慢性中毒，发生迟眠蚕，多营下茧和烂茧，全茧量、茧层量显著下降。     

伪狂犬病病毒在NF-κB家族p65基因敲除细胞系的复制规律研究

试验旨在研究伪狂犬病病毒（PRV）在NF-κB家族p65基因敲除细胞系中的复制规律。利用慢病毒介导的CRISPR/Cas9基因定点修饰技术构建猪肺泡巨噬细胞（3D4/21）p65基因稳定敲除细胞系。通过构建p65-sgRNA重组质粒,转染至HEK293T/17细胞,收取慢病毒,感染3D4/21细胞后利用嘌呤霉素筛选获得多克隆细胞系,T7核酸酶检测敲除效率,再通过有限稀释法获得3D4/21-p65^-/-的稳定细胞系。CCK-8试剂盒检测3D4/21细胞中敲除p65基因后对细胞增殖的影响;流式细胞术检测PRV-GFP感染3D4/21及3D4/21-p65^-/-细胞后病毒增殖的差异;实时定量PCR检测PRV感染3D4/21及3D4/21-p65^-/-细胞后PRV gB、TK基因mRNA表达水平及PRV感染细胞诱导的IL-1β和IL-6基因mRNA水平表达的变化;Western blotting检测PRV-QXX感染3D4/21及3D4/21-p65^-/-细胞后PRV gB、gE蛋白的表达;滴度测定检测PRV-QXX感染3D4/21及3D4/21-p65^-/-细胞后子代病毒滴度。结果表明,sgRNA2和sgRNA3的基因编辑效率较高,对其进行克隆化培养进而获得敲除p65基因的稳定表达细胞系;CCK-8试剂盒检测细胞活力表明,p65基因敲除对细胞活力无影响;流式细胞仪检测表明,同一时间点PRV-GFP在3D4/21-p65^-/-中的增殖显著高于对照细胞;实时荧光定量PCR表明在3D4/21细胞中敲除p65基因促进了PRV gB、TK基因的mRNA表达水平,而抑制了IL-1β、IL-6基因的mRNA表达;Western blotting结果表明,在3D4/21细胞中敲除p65基因促进了PRV gB、gE蛋白的表达;滴度测定结果表明,同一时间点PRV-QXX在3D4/21-p65^-/-细胞中子代病毒的复制显著高于对照细胞。以上结果均表明,p65基因敲除可促进PRV在3D4/21细胞中复制。     

Oxalate-degrading capacities of lactic acid bacteria in canine feces

In this study, lactic acid bacteria in canine feces were isolated and identified, and their oxalate-degrading capacities were evaluated. The oxalate-degrading capacities were determined for 24 of 47 (51.06%) lactic acid bacteria isolates. Of these, 8 isolates [Leuconostoc mesenteroides (RL75), Lactococcus garvieae (CD2), Lactococcus subsp. lactis (CS21), Enterococcus faecium (CL71 and CL72), and Enterococcus faecalis (CD14, CS62, and CD12)] degraded more than 5% of the oxalate present, while the others degraded less than 5% of the oxalate in vitro. Isolates that degraded more than 5% of the oxalate present were selected for further examination. The oxalate-degrading capacities of individual isolates, a mixture of Enterococcus, a mixture of Lactococcus, and a mixture of the eight isolates were evaluated in media containing different concentrations of glucose (sufficient, insufficient, or no glucose). In comparison with the control medium, all of the individual isolates and mixtures of isolates could degrade oxalate in all three groups (P<0.05). In most cases, the isolates growing in medium with 20 g/L of glucose had higher oxalate-degrading capacities than those growing in medium with 2.5 g/L of glucose or no glucose. The mixture of all isolates showed higher oxalate-degrading capacity than the individual isolates and other mixtures. The oxalate-degrading capacities of the isolates were isolate dependent.     

我国丝绸面临的困境及成因浅析

丝绸业是以茧丝绸为纽带 ,以出口创汇为主的跨越农工贸的外向型行业 ,现在我国的蚕茧和生丝产量分别约占世界总产量的78%和 72 % ,丝类、绸缎和丝绸服饰的出口量分别约占世界贸易的 90 %、50 %和 45% ,1 950～ 1 998年间丝绸出口创汇达 42 2 .1 2亿美元 ,在世界丝绸业和国民经济中占有重要的地位。1　我国丝绸业面临的困境80年代后期 ,我国丝绸行业高速发展 ,产量大幅攀升 ,出口量迅猛增加 ,但至 90年代中期 ,全行业发生前所未有的亏损 ,近来 ,以加入ＷＴＯ为契机 ,行业情况有所好转 ,但也仍在困境中艰难跋涉 ,发展前景不容盲目乐观。自 1 9…     

Dietary supplementation with sodium bicarbonate improves calcium absorption and eggshell quality of laying hens during peak production

1. The advantage of supplemental sodium bicarbonate (NaHCO₃) on eggshell quality in laying hens changes with age. Besides increasing calcium (Ca) secretion in the eggshell gland, it may improve Ca absorption in the intestine or kidney.

2. Hy-Line Brown layers (n = 384), 25 weeks of age, were allocated to two treatment groups in two experiments, each of which included 4 replicates of 24 hens. Hens were fed a basal diet (control) or the basal diet containing 3 g NaHCO₃ g/kg for 50 or 20 weeks in Experiment 1 or 2, respectively. A 24-h continuous lighting regimen was used to allow hens to consume the dietary supplements during the period of active eggshell formation.

3. In Experiment 1, particularly from 25 to 50 weeks of age, and in Experiment 2, NaHCO₃ supplementation favoured hen-d egg production at the expense of lower egg weight. The increased eggshell thickness should have nothing to do with the additional eggshell formation, because of the unchanged egg mass and daily eggshell calcification.

4. At 35 weeks of age in both experiments, NaHCO₃ supplementation increased duodenal expression of calbindin-d28k (CaBP-D28k) protein, contributing to higher Ca retention and balance.

5. From 50 to 75 weeks of age in Experiment 1, the hens had little response to NaHCO₃ supplementation and showed a negative trend on eggshell thickness and strength.

6. It is concluded that dietary supplementation with 3 g NaHCO₃ g/kg improves Ca absorption and eggshell quality of laying hens during the peak but not late production period, with the introduction of continuous lighting.

     

Protection of pigs against post-weaning multisystemic wasting syndrome by a recombinant adenovirus expressing the capsid protein of porcine circovirus type 2

Post-weaning multisystemic wating syndrome (PMWS) associated with PCV2 was one of the most costly diseases currently faced by the swine industry. In order to develop a vaccine to control this disease, we previously constructed a recombinant adenovirus expressing the capsid of PCV2. Here, we examined the protection of swine against PMWS by the recombinant adenovirus. Eighteen 32-day-old pigs were assigned to three groups each with six. Group 1 was vaccinated subcutaneously with rAd-Cap and boosted 2 weeks later. Thirty-seven days after first vaccination, Groups 1 and 2 were oronasally challenged with virulent PCV2 isolate, 4 and 7 days later, intramuscularly exposed to keyhole limpet hemocyanin (KLH). Group 3 remained unchallenged but with KLH. The results showed that high level of PCV2-specific ELISA antibody and neutralizing antibody could be induced at 37 days after first vaccination. After challenge, pigs in vaccinated group had no clearly clinical signs, although some of them had increased rectal temperatures (>/=40 degrees C) for short time. The pyrexic phase in vaccinated group was significantly lighter than that in challenge-control group (P<0.05). The relative daily weight gain in vaccinated-challenged group was similar to that in empty control group. But it was significantly high compared to the challenge-control group (P<0.05). Mean while the pathological lesions and virema presented in vaccinated group were milder than those in control group. It indicated that the recombinant adenovirus was able to confer significant protection against clinical disease and reduce pathogenic lesions induced by PCV2 challenge, even though it could not provide complete virological protection. The recombinant adenovirus might be an attractive candidate vaccine for preventing the disease associated with PCV2 infection.     

青海东部农业干旱区不同播种方式对紫花苜蓿农艺性状和生产性能的影响

为筛选紫花苜蓿(Medicago sativa)在青海东部农业干旱区适宜的播种方法,选用陇东苜蓿、WL343和金皇后3个品种,采用撒播、条播和精量穴播进行二因素随机区组试验.结果表明:1)3个品种间越冬率差异极显著(P＜0.01),WL343越冬率达到78.74％,比陇东苜蓿和金皇后分别高7.86％和13.16％;但3种播种方式间越冬率差异不显著(P＞005).2)2龄WL343的株高、生长速度和茎叶比与金皇后和陇东苜蓿相比较差异均显著(P ＜ 0.05),其单株分枝数与金皇后间差异不显著(P＞0.05),但与陇东苜蓿间差异显著(P＜0.05);精量穴播处理下苜蓿株高极显著高于条播和撒播处理,单株分枝数与条播无明显差异,与撒播差异明显,茎叶比极显著低于撒播和条播.3)2龄WL343鲜草产量与金皇后相比差异不显著,较陇东苜蓿显著提高了10.57％;精量穴播平均鲜草产量与撒播间差异显著;WL343 ×精量穴播平均鲜草产量达到39.86 t·hm-2,高于其他品种×播种方式的饲草产量.4)WL343粗蛋白含量(19.20％)较金皇后和陇东苜蓿分别高出2.65％和6.12％,粗纤维含量分别低20.41％和7.83％,无氮浸出物比金皇后高出17.23％.综合以上农艺性状和生产性能分析,在青海东部农业干旱区,采用精量穴播种植方式,选取WL343紫花苜蓿品种,其在第2年表现出高的生产性能和饲草品质.