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排序方式: 共有76条查询结果,搜索用时 15 毫秒
51.
P Gilch F Pollinger-Dammer C Musewald ME Michel-Beyerle UE Steiner 《Science (New York, N.Y.)》1998,281(5379):982-984
The recombination dynamics of a transition metal redox system monitored by femtosecond pump-probe spectroscopy are shown to be sensitive to high magnetic fields at times shorter than 10 picoseconds. The effect, based on coherent population beats of different spin states, is quantitatively accounted for and allows direct access to spin relaxation rates far beyond the time resolution of the fastest electron paramagnetic resonance technique. The presence of this ultrafast magnetic field effect helps in understanding complex reaction schemes in transition metal chemistry, which occur in a wide range of fields, such as bioinorganic chemistry and catalysis. 相似文献
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53.
PE Fernández ME Diessler A Pachame HH Ortega EJ Gimeno EL Portiansky CG Barbeito 《Reproduction in domestic animals》2014,49(2):263-269
The aim of this study was to characterize cytoskeletal intermediate filament proteins and glycoconjugates of syncytiotrophoblast, cytotrophoblast and decidual cells of feline endotheliochorial placenta. Samples from 12 normal pregnant female cats, after 45 ± 5 days of gestation, were obtained removing the uterine horns by hysterectomy. Sections were processed for routine observation and for immunohistochemistry using anticytokeratin, antivimentin and antidesmin antibodies. In addition, lectin histochemistry was performed using a panel of several biotinylated lectins to characterize glycosides expression profile. Cytotrophoblast and syncytiotrophoblast showed immunoreactivity only with acidic and basic cytokeratins. Decidual cells were only positive to vimentin, consistent with their origin from endometrial fibroblasts. Trophoblast expressed a broad population of glycans, highly exposing terminal N‐acetyl glucosamine residues and non‐sialylated galactose and N‐acetyl galactosamine oligomers. Oligosaccharides bound by Phaseolus vulgaris erythroagglutinin were the only highly branched N‐linked residues evidenced in cats, and they were restricted to the syncytium. Unlike results reported on humans, mice and rats on lectin affinity of decidual cells, sialid acids and complex N‐linked oligosaccharides were not demonstrated in cats. Glycosylation of proteins determines many of their final properties, thus becoming essential for the embryo‐maternal dialogue during implantation and placentation. Changes in glycosylation pattern have been related to pathological pregnancies in other species. Hence, the knowledge about glycosylation profile of the normal cat placenta may lead to a better understanding of both normal and pathological reproductive events. 相似文献
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Bovine thyroglobulin gene polymorphisms and their association with sexual precocity in Guzerat bulls 下载免费PDF全文
ME Fernández AM Loaiza Echeverri M Henry M Drummond DA Andrade de Oliveira S Demyda Peyrás D Cunha Cardoso G Giovambattista JP Liron 《Reproduction in domestic animals》2017,52(5):911-913
Puberty is a stage of sexual development determined by the interaction of environmental factors and genetic mechanisms. Among them, thyroid function plays a key role in sexual development and spermatogenic function and is under the control of several genes, including the well‐described thyroglobulin gene (TG). Previous reports have shown genetic association between thyroid function and selected single nucleotide polymorphisms (SNPs) in taurine cattle. Therefore, the identification of genetic mechanisms involved in the regulation of this trait can assist with the selection for early pubertal bulls, thus improving genetic progress in livestock breeding. The aim of this study was to validate the association between TG SNPs and age at puberty in zebuine bulls. Three SNPs (rs110406764, rs109662686, rs109057985) were genotyped in 159 Guzerat animals using SEQUENOM technology. Results showed a significant association (p < .05) between the studied SNPs and puberty age, in agreement with our previous reports in a taurine breed. Interestingly, allele frequencies were different from those already reported, being GAT the most favourable allele for age at puberty in Guzerat (94.4 days lower). Overall, our findings corroborate previous reports and reinforce the importance of genetic influence in the regulation of sexual development and puberty through a thyroid pathway in zebuine cattle. 相似文献
56.
Effect of sperm pretreatment with glutathione and membrane destabilizing agents lysolecithin and Triton X‐100, on the efficiency of bovine intracytoplasmic sperm injection 下载免费PDF全文
F Zambrano L Aguila ME Arias R Sanchez R Felmer 《Reproduction in domestic animals》2017,52(2):305-311
Intracytoplasmic sperm injection (ICSI) is an assisted reproduction tool with several applications. Its effectiveness in bovines is lower than that in other species, mainly because of difficulties in the decondensation of the sperm nucleus after injection, and the presence of the acrosome and the plasma membrane which remain intact in this procedure. In this study, we assessed the effect of lysolecithin (LL) and Triton X‐100 (TX), in combination with glutathione (GSH) as sperm pretreatments prior to ICSI. The GSH‐LL and GSH‐TX groups showed 0% of spermatozoa with intact membrane (SYBR 14+/PI), in comparison with the control (63.3%) and GSH (65.7%) groups. The proportions of spermatozoa with damaged acrosome membrane in the GSH‐LL, GSH‐TX, GSH and control groups were 46%, 35.9%, 10.5% and 7.5%, respectively. Sperm chromatin decondensation analysis showed that the groups incubated for 3 hr with GSH presented greater decondensation (p < .05). Although fertilization was improved in all treatment groups evaluated, no differences were observed in the cleavage rate 72 hr after activation in the GSH (73.7%), GSH‐LL (80.2%) and GSH‐TX (77.8%) groups compared to the control (66.3%), neither in the blastocyst rate on day 8 (24.0%, 26.2%, 27.1% and 28.4% for the control, GSH, GSH‐LL and GSH‐TX groups, respectively). No differences were also observed in the total number of cells in all groups. In conclusion, although these sperm treatments promoted nuclear decondensation and induced plasma membrane disruption, these effects were not sufficient to improve bovine embryonic development after ICSI. 相似文献
57.
RD Gama WL Vianna ME Pinese A de Campos Rosseto A de Sant''Anna Moretti 《Reproduction in domestic animals》2005,40(5):433-435
The use of hormonal protocols in puberty induction and synchronization of oestrus has lead to an increase in the efficiency of replacement gilts. The aim of this study was to evaluate different doses of porcine LH in precocious puberty induction and oestrus synchronization in a homogeneous group of gilts. Sixty-seven homogeneous prepubertal gilts (Camborough 22) at 137 +/- 4 days of age and 87 +/- 7 kg were treated with three different hormonal protocols: T1--600 UI of equine chorionic gonadotrophin (eCG; Novormon) and after a 72-h period 5 mg of LH (Lutropin); T2--600 UI of eCG and a 72-h period 2.5 mg of LH; T3--600 UI of eCG and a 72-h period 1.25 mg of LH. The ovaries were examined at slaughter, on day 6 after the hormonal treatment. There were no statistical differences (p > 0.05) between the different LH doses in the percentage of the detected oestrus (T1 = 42.85%; T2 = 60.87%, T3 = 52.18%), oestrus duration (T1 = 41.44 +/- 16.30 h; T2 = 48.57 +/- 16.29 h, T3 = 39.33 +/- 11.42 h), number of corpora lutea (T1 = 9.61 +/- 5.43; T2 = 9.86 +/- 3.32, T3 = 8.13 +/- 5.52) and percentage of animals presenting ovarian cystic degeneration (T1 = 33.33%; T2 = 39.13%, T3 = 39.13%). The T2 (2.5 mg of LH) presented the lowest dispersion (p < 0.05) of the LH-ovulation interval (T1 = 37.17 +/- 4.07 h; T2 = 38.26 +/- 2.84 h; T3 = 36.25 +/- 5.69 h). The LH dose reduction to 2.50 and 1.25 mg presented equal results with the recommended dose of 5.0 mg, and could be used in the precocious induction of oestrus in gilts. The 2.5-mg LH dose showed the lowest dispersion of ovulation and it can be used in fixed-time artificial insemination programmes. 相似文献
58.
A Ortega-Pacheco ME Bolio-González RF Colin-Flores CH Sauri-Arceo E Gutiérrez-Blanco M Jiménez-Coello C Linde Forsberg 《Reproduction in domestic animals》2006,41(3):227-232
A Burdizzo castrator was evaluated for the neutering of dogs. Histological and morphological changes of spermatic cells and peripheral serum testosterone after challenge with a GnRH-analogue (gonadorelin) were assessed. There was a control group (G1), a surgically castrated group (G2) and a Burdizzo group (G3) divided in two, G3a receiving two crunches in each spermatic cord and G3b receiving one crunch in each spermatic cord. Sixteen days after application of the Burdizzo blood samples were taken from the dogs at 30 min interval during 2 h; after the second sample the dogs were treated with 1 mug/kg body weight of gonadorelin i.v. The same protocol of gonadorelin challenge was performed in G1 and G2 dogs. The G2 dogs were surgically castrated after the second blood sample, before the gonadorelin treatment, and the G1 dogs after the last blood sample. The excised gonads were examined histologically, and sperm smears were prepared from the caudae epididymidis. The testes and plexus pampiniformis of the G1 and G2 dogs had a normal histological appearance, and they had morphologically normal epididymal sperm cells. In all G3 dogs, there was an acute fibrosis with an inflammatory reaction in the plexus pampiniformis. The testes from the G3a dogs showed diffuse areas of infarction and degeneration of the parenchyma. Similar but less diffuse lesions were seen in group 3b dogs. The deferent ducts from all G3 dogs showed vasitis and/or sperm granulomas. Azoospermia or sperm malformations were observed in the epididymal smears from the G3 dogs. Testosterone concentration in the G1 dogs increased after gonadorelin application (p < 0.0001). The G2 dogs had basal testosterone levels after castration (p < 0.001) and did not respond to gonadorelin. Groups 3a and b showed a slight but non-significant increase in testosterone concentration after gonadorelin challenge, supposedly due to the reduction of testicular blood flow and loss of testicular interstitial tissue. 相似文献
59.
L. J. FREEMAN DVM MS G. A. HEGREBERG DVM PhD J. D. ROBINETTE DVM MS DiplomateACVs J. T. KIMBRELL MS ME 《Veterinary surgery : VS》1989,18(2):97-102
The biomechanical properties of wounded and nonwounded skin were studied in three dogs and three cats affected with type I Ehlers-Danlos syndrome. Three nonaffected dogs and one nonaffected cat served as controls. Samples of wounded skin and adjacent normal skin were harvested at days 75, 138, 141, 144, 147, and 150. Samples were subjected to uniaxial tensile strength testing. Tensile strength, energy absorbed, and site of failure were recorded. In the dogs with Ehlers-Danlos syndrome, there was an increase in tensile strength in samples containing a scar over adjacent intact skin. In nonaffected dogs, affected cats and the nonaffected cat, the nonwounded skin samples had greater tensile strength. The energy absorbed by the skin samples during testing was highly correlated with tensile strength. 相似文献
60.
Haematological and biochemical reference values were established from 45 clinically healthy koalas. Statistical analysis revealed no significant differences for sex and season of sampling. Immature koalas had significantly higher alkaline phosphatase and inorganic phosphate values, and significantly lower total protein concentrations due to low globulins values. Enzyme reference values tended to be wide and could limit their usefulness in detecting disease. In the reference values for leukocytes, neutrophils and lymphocytes, the inclusion of low values which were not actually seen may interfere with the detection of reduced levels due to disease. 相似文献