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21.
本文测定了温度对香菇胞外纤维素酶和半纤维素酶活性的影响。木屑基质培养90天的香菇胞外游纸纤维素酶(C_1酶)、羧甲基纤维素酶(C_X酶)和半纤维素酶(H_C酶)的最适作用温度分别是55℃、55~60℃和50℃。在50~55℃条件下保温1小时后,C_1酶和H_C酶活性大幅度下降,而C_x酶活性下降较为缓慢,具有较高的热稳定性。本文提出相对活力系数(Relative activity coefficient,RAC)作为表示香菇菌丝生长温度与酶最适作用温度之间关系的一个参数。 相似文献
22.
野生稻与栽培稻的杂种后代对褐稻虱的抗性机制初探 总被引:7,自引:0,他引:7
为了开拓抗虫基因源,培育抗性稳定的水稻抗虫品种,采用感虫的栽培稻雄性不育株为母本,以高抗褐稻虱的野生稻为父本进行有性杂交。通过用改良的苗期群体筛选法,对其后代进行抗性鉴定,证实其抗性可以遗传,已成功地获得了抗褐稻虱的杂种后代。并根据飞虱在抗虫植株上的生存率、群体建立、蜜露量和稻株的受害级别等指标与感虫对照种TN1上的差异显著性作比较,综合评定杂种后代对褐稻虱的抗性机制。结果表明,测试的N482(A)/101392组合的F_5、F_6、F_7和H_4等几个后代对褐稻虱的抗性机制均为抗生性。 相似文献
23.
Seeds of Johnsongrass [Sorghum halepense (L.) Pers.] germinated to higher percentages (20–30% higher) when incubated at 28 and 35° C than at 10 or 22° C. After-ripening was accelerated by dry storage of these seeds at 50°C. Seeds pre-chilled at 6°C for 2–4 weeks followed by incubation at 28°C germinated 40–60%. Light effects on germination were related to incubation temperatures; inhibitory at 22°C; no response at 28°C; and stimulatory at 35°C. Effects of gibberellin A3 (GA3) also varied depending on incubation temperature, sodium hypochlorite (NaOCl) immersion and light conditions. Immersion of dry seeds in either 700 mM NaOCl, 900 mM H2O2 or concentrated H2SO4 before incubation in water was effective in breaking dormancy. This result suggests the modes of action of H2SO4 in the termination of dormancy may be similar to those of NaOCl and H2SO4 as previously suggested by Hsiao & Quick (1984), that is by modification or scarification of the hull or seed coat membranes, and also by the supply of additional oxygen to the seed. 相似文献
24.
为明确大豆-玉米带状间作种植模式对点蜂缘蝽Riptortus pedestris发生规律的影响,2023年在山东省大豆单作田中进行诱捕效果试验,筛选诱捕效果最好的诱捕器对黄淮海地区山东、河南和安徽3个省6个市不同种植模式下点蜂缘蝽的发生动态进行监测。结果显示,风叶型诱捕器对点蜂缘蝽的诱捕效果最佳。在大豆单作田内点蜂缘蝽的发生高峰期为7月中旬—8月中旬,此时大豆正值盛花-始荚期。在大豆-玉米带状间作田内点蜂缘蝽的发生动态与大豆单作田的无明显差异,但点蜂缘蝽发生数量及高峰期发生时间可能与杀虫剂的施用时间和次数密切相关。 相似文献
25.
云南苹果产区苹果茎沟病毒(ASGV)的发现及其分子变异 总被引:1,自引:0,他引:1
【目的】为了查明云南省苹果产区的苹果茎沟病毒病毒(Apple stem grooving virus,ASGV)的侵染情况和不同来源分离物间的分子变异情况,【方法】以云南昭通、丽江、昆明、曲靖等地采集的325份苹果病毒样品为试材,采用RT-PCR技术对其是否携带ASGV进行检测,运用DNAMAN6.0、MEGA5.0对实验获得的6个分离物和GenBank上已登录的34个分离物进行序列比对分析。【结果】ASGV在云南各大苹果产区的发病率高达48%。序列比对结果显示,这些分离物的核苷酸序列相似性为87.3%~93.8%,氨基酸序列相似性为90.7%~98.7%。系统发育树显示,云南的6个分离物聚为一簇,而陕西省苹果分离物YL06与云南省分离物ZT1、TJX1亲缘关系比较近,聚为一支;ASGV苹果分离物要明显区别于ASGV梨分离物和CTLV柑橘分离物。【结论】云南省苹果产区苹果树的ASGV带毒率高达48%,推测可能是一种发生率比较普遍的病毒病,这是云南省发现的首次报道。系统发育树显示:本研究获得的6个苹果分离物明显区别于其他寄主分离物,并且与其他地区的分离物具有一定差异,推测在我国,ASGV的分子变异与寄主/地域来源存在着一定的相关性。 相似文献
26.
Wagner M Melzner D Bagò Z Winter P Egerbacher M Schilcher F Zangana A Schoder D 《Journal of veterinary medicine. B, Infectious diseases and veterinary public health》2005,52(6):278-283
We report the results of clinical and microbiological investigations on Listeria monocytogenes infections in a flock of 55 sheep and describe the implications for the safety of the raw milk and raw-milk cheeses produced in the on-farm dairy. The outbreak was caused by feeding grass silage, which was contaminated with 5 log10 CFU L. monocytogenes/g. Clinically, although having been fed from the same batch of silage, abortive (nine ewes), encephalitic (one ewe) and septicaemic (four ewes) forms of listeriosis were observed during the outbreak phase. As the starting point of feeding the contaminated silage was known we could calculate an incubation period of 18+/-2 and 26 days for the abortive and the encephalitic form of listeriosis, respectively. Pathologically, the septicaemic cases suffered from Listeria accumulation at comparable numbers in visceral organs but not in the brain. Only a single ewe developed central nervous symptoms and a rhomb-encephalitis was immunohistologically confirmed. In this case the infection proceeded from the nasal mucosa into the brain, with no infections of the liver, spleen and other visceral organs. Sampling of the cheese production chain, the farm environment and the persons living at the farm revealed the exposure of a farm-worker to an isolate genetically indistinguishable from the outbreak clone, obviously through the consumption of faecally contaminated bovine raw milk. The cheese under processing was free of Listeria because, as a result of intensive consultations, the farmer ensured a proper acidification of the cheese. The epidemiological findings suggest that food safety matters should be assessed in any case where infection of food-producing animals with potential human pathogens is observed. 相似文献
27.
选择覆盖肾综合征出血热病毒(HFRSV)膜蛋白(MP)基因的保守区核苷酸序列合成2对引物,采用异硫氰酸胍一步抽提RNA,建立了RT-PCR检测鼠体恙螨及游离恙螨体内HFRSV-RNA的方法,扩增产物经凝胶电泳及斑点印迹杂交证实具有特异性。结果显示,HFRSV抗原阳性鼠体恙螨50只组、10只组、游离螨50只组,HFRSV抗原阳性鼠肺1000mg、500mg组经RT-PCR检测为阳性;HFRSV抗原阳性鼠体恙螨5只组,HFRSV抗原阴性鼠体恙螨50只和10只组,游离螨10只和5只组,鼠肺HFRSV抗原阳性100mg组均未见有明显扩增带。进一步用套式反转录-聚合酶链反应(NestedRT-PCR)检测,在RT-PCR未测出HFRSV-RNA的各组中均检测有HFRSV-RNA。结果表明NestedRT-PCR具有高特异、高敏感的特点,可用于检测恙螨体内微量HFRSV-RNA,为确认恙螨作为HFRSV的传播媒介提供了分子生物学证据。 相似文献
28.
29.
新西兰实验兔体重及体尺增长模式 总被引:3,自引:1,他引:3
对自繁培育的普通级新西兰兔不同时期体重、体长、胸围、耳长及尾长的增长模式进行观察,结果表明:哺乳期(0~6周龄)体重及体尺增长比较缓慢,断奶后迅速增长;其中体重日均增长,0~2周龄最低,为9.21g,12~16周龄最高,为37.24g;体长与耳长的日均增长,2~4周龄最高,12~16周龄最低;胸围及尾长的日均增长则是4~8周龄最高,12~16周龄最低。 相似文献
30.
Effect of a 1800 MHz electromagnetic field emitted during embryogenesis on chick development and hatchability 下载免费PDF全文
K. Pawlak Z. Nieckarz A. Sechman D. Wojtysiak B. Bojarski B. Tombarkiewicz 《Anatomia, histologia, embryologia》2018,47(3):222-230
The level of artificial electromagnetic field (EMF) has steadily increased with the development of human civilization. The developing chicken embryo has been considered a good model to study the effects of EMF on living organisms. The aim of the study was to determine the effect of a 1800 MHz electromagnetic field during embryogenesis on the frequency of chick embryo malformations, morphometric parameters of the heart and liver and concentration of corticosterone in blood plasma, lipid and glycogen content in the liver of newly hatched chicks. A 1800 MHz EMF was found to shorten the duration of embryogenesis (earlier pipping and hatching of chicks) while having no effect on the quantity and quality of chicks and on increasing the incidence of embryo malformations. Exposure of chick embryos to EMF caused decreases in relative heart weight and right ventricle wall thickness. The pipping and hatching of chicks can be accelerated by stressful impact of EMF, which is confirmed by a significant increase in plasma corticosterone concentrations and decrease in fat and glycogen in the liver of chicks exposed during embryogenesis on the electromagnetic field with a frequency of 1800 MHz. 相似文献