Changes in the electric resistance of the vaginal mucus in oestrous sows     

O Szenci  Z Sima  C Hartmann  J Keresztes 《Acta veterinaria Hungarica》1990,38(1-2):19-24

Changes in the electric resistance of the vaginal mucus were monitored in a large pig herd at 4-h intervals with a heat detector (Hauptner, Federal Republic of Germany) in multiparous sows (n = 16; litter size = 11.4 +/- 2.9) that showed a positive standing test and conceived. The initial value of resistance was 74.4 +/- 7.4 ohms. In 36 h this value gradually increased to 93.6 +/- 7.6 ohms. One to 2 h after the artificial inseminations (AI) lower resistance values were obtained, though the difference was not statistically significant. In the second part of the experiment 73.9% and 82.7% of the gilts (n = 92) and multiparous sows (n = 98) conceived, respectively, with an average litter size of 9.6 +/- 2.2 and 11.0 +/- 2.7, respectively. The conception rate of animals that immediately before AI had vaginal mucus resistance values between 75 and 90 ohms was about 20% higher. The only exception were 8 multiparous sows which had an average vaginal mucus resistance of 70 +/- 4.6 ohms after the first insemination. Litter size was also the biggest in sows with vaginal mucus resistance between 75 and 90 ohms. This difference was statistically significant for the multiparous sows. The heat detector is considered to be a useful complement to conventional methods of oestrus detection.  相似文献   

家蚕遗腹卵率的遗传参数分析   总被引：1，自引：0，他引：1  

林健荣  农朝志 《华南农业大学学报》1995,16(4):87-90

用６个原种按完全双列杂交法安排试验，对组配的３６个杂交组合的试验结果，用数量遗传学及统计学的方法进行了分析。家蚕遗腹卵的发生，在原种间、杂种间均有一定的差异性。以日系杂交原种有偏高的倾向。造卵数与遗腹卵率的相关分析表明，蚕的遗腹卵率并不依造卵数的增多而增加。家蚕亲本的遗腹卵率多时，其杂交后代的遗腹卵率也高，遗腹卵的遗传表现为超显性，显性效应大于加性效应，亲本以显性基因频率大于隐性基因的频率，推测其基因数目至少有３对。  相似文献   

濒危植物景东翅子树种群的分布、年龄结构及其动态特征   总被引：1，自引：0，他引：1  

袁春明  司马永康  耿云芬  郝佳波  毛云玲  魏大坤  何琪金 《东北林业大学学报》2011,39(5):15-16,33

调查研究了景东翅子树种群的分布、年龄结构及其动态特征,并讨论了濒危的原因.野外调查的4个种群中,3个分布于季风常绿阔叶林,1个分布于次生灌丛.在4个种群中共调查到景东翅子树99株(含幼树).结果表明,景东翅子树属于衰退型种群,其中缺乏幼树和胸径≥20 cm的大树.景东翅子树种群的存活曲线为DeevryⅢ型,生活史中存在...  相似文献   

Egyptian broomrape (Phelipanche aegyptiaca) response to silicon nutrition in tomato (Solanum lycopersicum L.)     

Hassan Karimmojeni  Mohammad Hossein Ehtemam  Sima Javadimoghadam  Amir Hossein Bazrafshan 《Archives of Agronomy and Soil Science》2017,63(5):612-618

Egyptian broomrape is a root holoparasitic plant that causes severe damage to tomato in Iran. Experiments were conducted in 2013 to investigate the effect of silicon (Si) nutrition on broomrape response in tomato. Si concentration significantly delayed first appearance of broomrape and decreased number of tubercles in both cultivars, although the magnitude of reduction varied with cultivar and Si concentration. Broomrape infection significantly decreased root and shoot dry weights of tomato cultivars. However, Si nutrition at high concentration considerably reduced damage severity of broomrape compared to the treatment that received no Si. Infection of tomato with broomrape resulted in significant increase in peroxidase and catalase activity in the roots of resistant cultivar which led to enhanced crop resistance to oxidative stress and improved growth in this cultivar.  相似文献   

Hairpin-based virus resistance depends on the sequence similarity between challenge virus and discrete,highly accumulating siRNA species     

Victor Gaba  Arie Rosner  Ludmilla Maslenin  Diana Leibman  Sima Singer  Emre Kukurt  Yoel M. Shiboleth  Amit Gal-On 《European journal of plant pathology / European Foundation for Plant Pathology》2010,128(2):153-164

Virus resistance can be effectively generated in transgenic plants by using the plant’s silencing machinery. To study the specificity of gene-silencing-based resistance, homozygous tobacco (Nicotiana tabacum L.) plants containing a 597-nt hairpin RNA construct of the Potato Virus Y (PVY) replicase sequence were challenged with a variety of PVY strains. The transgene-carrying tobacco line was immune to five potato PVY strains with high sequence similarity (88.3–99.5%) to the transgene. Infection with more distant tomato and pepper PVY field strains (86–86.8% sequence similarity) caused delayed symptom appearance in the transgenic tobacco. Transgene production of small interfering (si) RNA was detected by northern blot and measured using a custom-designed microarray for the detection of small RNAs. siRNA accumulation peaks were observed throughout the inverted-repeat transgene. In the resistance-breaking tomato and pepper strains there were nucleotide differences in the sequences correlated to siRNA transgene accumulation, indicating the role of siRNA specificity in resistance breaking. The log of transgene siRNA signal intensity increased with probe GC content, indicating that the accumulating siRNA molecules were GC-rich. Sequence similarity of highly accumulating siRNAs with the target virus strain appears to be important for both resistance and resistance-breaking characteristics.  相似文献   

夏秋蚕新品种吴花×浒星的育成     

何毅  司马杨虎  郑必平 《蚕业科学》2002,28(1):56-60

采用杂交、回交、系统分离育种方法 ,育成了适应长江流域夏秋期饲养的品种吴花×浒星。该品种体质强 ,孵化、眠起、老熟齐一 ,产茧量和产丝量高 ,茧层率达 2 2 6 % ,与对照种 75新× 75 32比较 ,万蚕产茧量、万蚕茧层量、出丝率分别提高 8 4 %、8 5 %、9 8%。茧丝品质优良 ,纤度 2 886dtex、茧丝长 10 5 0m ,并且繁育容易。  相似文献   

濒危植物景东翅子树的萌生特征   总被引：1，自引：0，他引：1  

袁春明  司马永康  耿云芬  郝佳波  毛云玲  罗忠华  鲁成荣  袁德财 《东北林业大学学报》2012,40(3):113-114,122

调查研究了濒危植物景东翅子树种群的起源与萌生特征。结果表明:所调查的4个种群中共记录到景东翅子树99株,其中萌生形成的植株35株,占总株数的35.4%;萌生个体主要处于幼树(D<2 cm)和小树(2 cm≤D<5 cm)阶段,二者占全部萌生个体的85.7%。景东翅子树萌生更新的方式主要是根部萌生和干基萌生2种。4个种群平均的萌生百分比为59.2%,萌生个体萌生的平均茎数为2.8个。景东翅子树萌生的方式和萌生能力的大小与人为干扰的状况与关。萌生在干扰条件下景东翅子树种群的恢复和维持中起到了重要的作用。  相似文献   

Comparison of floral ontogeny in wild-type and double-flowered phenotypes of Syringa vulgaris L. (Oleaceae)     

Mohammad Reza Dadpour  Somayeh Naghiloo  Seyed Hadi Peighambardoust  Sima Panahirad  Maryam Aliakbari  Ali Movafeghi 《Scientia Horticulturae》2011

A comparative study of floral ontogeny in normal and double-flowered phenotype of Syringa vulgaris was conducted using the epi-illumination light microscopy. In the wild phenotype, floral differentiation starts with calyx inception and the formation of four sepals in orthogonal positions (two median and two lateral). The corolla emerges as a continuous ring-like structure leading to the appearance of four petal lobes alternating with the sepals. Androecium was formed by initiation of two stamen primordia in transverse plane and finally the bicarpellate gynoecium emerges in median position. In the case of the double-flowered lilac, there are supernumerary petals in an additional whorl. In double-flowered phenotype, a ring meristem is formed acropetally after the first petal whorl initiates. Stamens and carpels initiated similarly in double-flowered as well as in wild-type plants. However, position of stamens deviates from the typical transverse situation. It seems that the appearing of an extra petal whorl did not exhibit any adverse effect on the initiation of other whorls, in terms of organ identity. Therefore, it would be suggested that the double-flowered phenotype of Syringa represents a case of neoheterotopy, with formation of an extra petal whorl, rather than a case of homoheterotopy with transformation of an ancestral androecium whorl into petals.  相似文献   

昆虫生物钟基因及其分子作用机制研究进展   总被引：3，自引：0，他引：3  

王英  司马杨虎  宋艳  朱晓苏  徐世清 《江苏蚕业》2008,30(1):9-14

昆虫经过长期的演化,在其生命活动和行为中,有着明显的昼夜和季节的节律性周期变化,通常将这种节律性活动现象称为生物钟。蟑螂是变温动物,体温会随外界环境的变化而变化,生物钟周期是"温度补偿"的。果蝇昼夜生物钟节律是一种"转录-翻译-抑转录"机制构成的反馈环,主钟由位于脑部的两簇神经元组成,其中已确认的主要钟基因有per、tim、clk、cyc、dbt、vri和cry等。家蚕的滞育是一种世代节律现象,但与近日节律密切相关,且无法单纯用近日节律调控方式来解释。家蚕滞育卵内的酯酶A4(EA4)是一种时间间隔测定酶,能够感知低温和盐酸等刺激信息,EA4的测时功能与其自身的结构有关,受蚕卵内的多肽抑制因子(PIN)的调控。聚类分析结果表明,家蚕EA4虽然在SOD蛋白家族,但EA4与其他物种Cu/Zn-SOD进化距离较远。生物钟的进化关系研究表明,生物钟的关键分子构成在果蝇等昆虫和哺乳动物之间是高度保守的。  相似文献   

Salt Tolerance of Canola in Relation to Accumulation and Xylem Transportation of Cations     

H. Rezaei  N. A. Khosh Kholgh Sima  M. J. Malakouti  M. Pessarakli 《Journal of plant nutrition》2013,36(11):1903-1917

ABSTRACT

This study was conducted in a greenhouse to evaluate the root and shoot response of canola (Brassica napus L.) to salt-stress conditions and the remobilization, deposition, and input rate of sodium (Na), potassium (K), and magnesium (Mg) at different salinity levels using two canola cultivars. A salt-tolerant (‘Kristina’) cultivar and a salt-sensitive (‘Hyola 308’) cultivar were grown in nutrient solutions with 0, 50, 100, 150, and 200 mol m^?3 NaCl for 7 d. The plants were harvested after 6, 12, 18, and 24 h and 3 and 7 d after salt treatment. The results indicated that increasing salinity significantly decreased shoot and root weights 7 d after treatment. Also, K content and K-Na selectivity decreased in both cultivars, but the changes in ‘Hyola 308’ were greater than in ‘Kristina.’ Electrolyte leakage was increased significantly by salinity, and cell-membrane stability of ‘Hyola 308’ was damaged more than that of ‘Kristina’. Sodium import, transport, and deposition was increased by salinity concentration but remobilization was decreased. The K and Mg import, deposition, and remobilization were also decreased. From this experiment we can conclude that greater K and Mg remobilization in ‘Kristina’ could be a mechanism of salt tolerance in canola.  相似文献