Effects of Body Condition and Protein Supplementation on LH Secretion and Luteal Function in Sheep   总被引：1，自引：0，他引：1  

CA Meza-Herrera  T Ross  D Hallford  D Hawkins  A Gonzalez-Bulnes 《Reproduction in domestic animals》2007,42(5):461-465

In ruminants, nutrition is one of the exogenous inputs affecting reproductive function at different levels of the hypothalamic-hypophyseal-gonadal axis. However, the exact mechanisms or even the identification of the signalling metabolic compounds by which nutrition affects reproductive function still need further clarification. The role of static body condition (BC) and its interaction with a short-term protein supplementation (PL), on secretion of metabolic hormones [growth hormone (GH), insulin and insulin-like growth factor-1 (IGF-1)], as well as on secretion of LH and progesterone (P4) was evaluated in sheep. Twenty-four Rambouillet ewes divided into two groups, with lower (LBC) and higher body condition (HBC), were randomly assigned within BC to one of two PL levels: low (LPL, 24% of crude protein; 14 g/animal/day), and high (HPL, 44% of crude protein; 30 g/animal/day). The secretion of GH, insulin, IGF-1 and LH was evaluated on day 10 of the oestrous cycle; appearance and timing of oestrous behaviour were previously detected using rams. Progesterone secretion was evaluated on day 13 of the same cycle. No differences were found (p > 0.05) between PL groups on serum GH concentrations during the sampling period (overall mean of 4.0 +/- 0.3 ng/ml), but a trend for lower values in HBC sheep was found (3.6 +/- 0.4 vs 4.4 +/- 0.4 ng/ml, p = 0.06). A BC effect was observed (p < 0.05) on serum IGF-1 level, with higher values in HBC sheep (p < 0.05). Neither BC nor PL affected (p > 0.05) secretion of LH and the number of corpora lutea, nor serum P4 and insulin concentrations. Results indicate a predominance of the static component of nutrition on sheep metabolic hormone responses, GH and IGF-1, with no effect of short-term PL on secretion of pituitary and ovarian hormones as well as luteal number and activity.  相似文献   

Granulosa Cell Tumors of the Equine Ovary     

Patrick M. McCue  Janet F. Roser  Coralie J. Munro  Irwin K.M. Liu  Bill L. Lasley 《Veterinary Clinics of North America: Equine Practice》2006

  相似文献   

Cytochrome P-based resistance mechanism and pyrethroid resistance in the field Anopheles albimanus resistance management trial     

R. Patricia Penilla  Janet Hemingway  Alma D. López 《Pesticide biochemistry and physiology》2007,89(2):111-117

The relative rates of cytochrome P⁴⁵⁰ selection in southern Mexican Anopheles albimanus populations were investigated during a 3 years indoor residual house spraying intervention with a pyrethroid (PYR) or DDT, a mosaic of organophosphate (OP)-PYR, and the annual rotation of OP-PYR-carbamate (CARB). This insecticide resistance mechanism, initially evenly spread in the mosquito population, correlated with PYR resistance during the second treated year, when cytochrome P⁴⁵⁰ contents increased in most villages of the PYR, rotation and mosaic schemes. However, by the third year, mean cytochrome P⁴⁵⁰ contents declined to susceptible levels in mosquitoes of the rotation and one mosaic group but not in the PYR-treated villages. In DDT-treated villages, a continuous decrement of cytochrome P⁴⁵⁰ levels occurred since the first treatment year, and susceptible levels were observed at the end of the intervention. Most correlations of cytochrome P⁴⁵⁰ levels and PYR resistance were lost during the third year, indicating that another mechanism evolved in resistant mosquito populations.  相似文献   

‘Candidatus Phytoplasma australiense’ is the phytoplasma associated with Australian grapevine yellows, papaya dieback and Phormium yellow leaf diseases     

Lia W. Liefting  Anna C. Padovan  Karen S. Gibb  Ross E. Beever  Mark T. Andersen  Richard D. Newcomb  David L. Beck  Richard L.S. Forster 《European journal of plant pathology / European Foundation for Plant Pathology》1998,104(6):619-623

Sequence comparisons and phylogenetic analysis of the 16S rRNA genes and the 16S/23S spacer regions of the phytoplasmas associated with Australian grapevine yellows, papaya dieback and Phormium yellow leaf diseases revealed minimal nucleotide differences between them resulting in the formation of a monophyletic group. Therefore, along with Australian grapevine yellows, the phytoplasmas associated with Phormium yellow leaf and papaya dieback should also be considered as Candidatus Phytoplasma australiense.  相似文献   

猕猴桃成熟果实中脂氧合酶基因的克隆   总被引：11，自引：0，他引：11  

陈昆松 Ross.  GS 《园艺学报》1998,25(3):230-235

采用ＰＣＲ扩增方法,从成熟猕猴桃果实组织中克隆到一个８２４ｂｐ的脂氧合酶（ＬＯＸ）基因片段（ｐＫＬＣ１）,该片段含有２７５个氨基酸组成的开放阅读框架,它与拟南芥菜、黄瓜、豌豆、土豆、水稻、大豆、烟草和番茄的核苷酸同源性为５９．０％～７４．６％,氨基酸同源性为６３．１％～７６．３％。Ｓｏｕｔｈｅｒｎ杂交表明,ｐＫＬＣ１片段为一低拷贝数基因家族所编码。  相似文献   

Cell-mediated and humoral immune response to Mycoplasma hyopneumoniae in pigs enhanced by dextran sulfate     

M Kishima  R F Ross  C Kuniyasu 《American journal of veterinary research》1985,46(2):456-462

The effect of dextran sulfate (DS), known to be cytotoxic to macrophages, on the cell-mediated and humoral immune response to nonviable Mycoplasma hyopneumoniae in pigs was investigated. The cell-mediated immune response was determined by means of lymphocyte transformation a test, using uptake of [3H]thymidine in a microculture system and the humoral immune response by means of a microplate complement-fixation test. Peripheral blood lymphocytes from pigs vaccinated with nonviable M hyopneumoniae and DS incorporated substantially more [3H]thymidine than did those from pigs given Mycoplasma or DS alone. The transformation of lymphocytes from M hyopneumoniae-DS vaccinated pigs was enhanced when M hyopneumoniae cells used in the assay system were heated at 60 C for 30 minutes. Similarly prepared M flocculare and M hyorhinis cells also stimulated lymphocytes from M hyopneumoniae-DS vaccinated pigs, but not nearly as great as when M hyopneumoniae cells were used. The humoral antibody response and the cell-mediated immune response to nonviable M hyopneumoniae was markedly enhanced by DS. Pigs were vaccinated with nonviable M hyopneumoniae and/or DS 4 times and challenge exposed intratracheally with viable M hyopneumoniae. Pigs vaccinated with M hyopneumoniae and DS had less severe pneumonia than did nonvaccinated pigs.  相似文献   

Suppressive effect of nonviable Mycoplasma hyopneumoniae on phytohemagglutinin-induced transformation of swine lymphocytes     

M Kishima  R F Ross 《American journal of veterinary research》1985,46(11):2366-2368

The effect of nonviable Mycoplasma hyopneumoniae on transformation of swine peripheral blood lymphocytes by mitogen was investigated. Lymphocyte transformation was evaluated as incorporation of [3H]-thymidine, using a microculture system. Mycoplasma hyopneumoniae was grown in Friis medium, inactivated with sodium azide, and washed with phosphate-buffered saline solution. Four strains of M hyopneumoniae, strain J, strain 11, and 2 low-passage isolates (1361A, 1375C), were found to suppress phytohemagglutinin-induced lymphocyte transformation. Mycoplasma hyopneumoniae strains J, 11, and 1361A reduced lymphocyte transformation by about 50%, whereas strain 1375C reduced lymphocyte transformation by 98.7%. The suppressive effect was abrogated by heating M hyopneumoniae at 60 C or at higher temperatures for 30 minutes. Sonication of the heated M hyopneumoniae cells partially restored the suppressive effect.  相似文献   

林木遗传工程及木质素的生物合成调节(英文)   总被引：1，自引：0，他引：1  

唐巍  Janet Ogbon  Aquilla McCoy 《林业研究》2001,12(2):75-83

林木遗传工程有利于保存林木遗传资源，改善全球气候，减轻自然林的过度采伐和满足人类日益增长的林木产品需求。控制林木真菌、病毒病、虫害和杂草的遗传工程方法正被广泛地研究和应用。尽管转基因林木的历史不长，种类不多，但它有广泛的应用前景。目前，抗除草剂基因、抗虫基因以及和木材质量相关的基因已被分离并应用于林木遗传工程。植物分子生物学和基因组学中的新技术使得高效林木遗传改良成为可能并将促进这些技术的商业化应用。木质素的应用已有一百年的历史，但木质素生物合成的全过程并不完全清楚。有关松树自然突变体和转基因林木的最新研究结果表明，木质素的生物合成是一个可以调节的过程。这些发现对完善木质素的生物合成途径、加深对木质素前体生物合成途径的理解和通过遗传工程改善木材质量有促进作用。本文综述了林木遗传工程在这些领域中取得的一些进展。  相似文献   

A thermogravimetric study of the pyrolysis of the bark and chemically-modified bark of jack pine,pinus banksiana lamb     

C. Faibridge  R. A. Ross  P. Spooner 《Wood Science and Technology》1975,9(4):257-274

The pyrolysis of native jack pine bark has been studied from 200 to 340°C by thermogravimetric (TG), and isothermal weight-loss methods. The effects of particle size, solvent extraction and additions of zinc (II) and iron (III) chlorides on the pyrolysis behaviour have also been examined. The bark was characterized by infrared spectroscopy and low-temperature gas adsorption. Residues were analysed for CHN contents and structural changes which occurred on heating were examined by optical and scanning electron microscopy. The TG characteristics were not affected by solvent extraction or particle size variation while the metal chloride additions inhibited the loss of volatile materials from the bark probably by stabilizing chemical bonding in the bark components. Isothermal decomposition data were found to fit established kinetic expressions associated with inorganic decompositions. The physical mechanics of pyrolysis have been interpreted on the assumption that pyrolysis is initiated through the formation of planes of lateral strain which are sites for decomposition and which decrease in number inversely with time. It is suggested that these sites are produced by an oxidation mechanism which may be rate-controlling in the pyrolysis. This hypothesis is supported by the observation that the data fit a reaction rate compensation curve, often associated with oxidation processes but more generally with heterogeneous catalytic reactions. The compensation curve also relates the kinetic parameters found by other workers for a large variety of wood-derived materials.  相似文献   

杉木幼龄林叶片营养元素含量与林木生长的相关性   总被引：3，自引：0，他引：3  

杨承栋  Janet Dutch  焦如珍  夏良放  孙启武 《林业科学》2002,38(6):24-29

本文重点论述丘陵立地条件下 ,1、2代杉木幼龄林高生长、当年高生长、胸径生长与叶片中营养元素N、P、K、Ca、Mg、Cu、Mn、Zn、Fe含量的相关关系 ,进而从林木营养这个角度 ,为提高林木产量、防治地力衰退提供可靠的科学依据。研究结果表明 :2代杉木幼龄林生长与N、P、Mg、Cu、Mn、Fe含量呈密切的正相关。 1代杉木幼龄林生长虽与P、Mg、Cu、Mn、Fe含量呈正相关 ,但复相关系数数值偏低。也就是说土壤养分含量尚没有明显影响 1代杉木幼龄林正常生长  相似文献