Crystalline form of native celluloses     

Hebert JJ 《Science (New York, N.Y.)》1985,227(4682):79

  相似文献   

Effects of Growth Hormone on In Situ Culture of Bovine Preantral Follicles are Dose Dependent          下载免费PDF全文

CR Jimenez  JL de Azevedo  RG Silveira  J Penitente‐Filho  EL Carrascal‐Triana  AM Zolini  VR Araújo  CAA Torres 《Reproduction in domestic animals》2016,51(4):575-584

The objective of this study was to evaluate different concentrations of growth hormone (GH) on the development of bovine preantral follicles cultured included in the ovarian tissue (in situ) on the rates of morphologically normal, viable, primordial and developing follicles, as well as the oocyte and follicle diameter and ultrastructural analysis. Ovarian fragments collected from cows with no cross‐breeds defined were cultured in situ for 1 and 7 days in minimal essential medium (α‐MEM+) supplemented with different concentrations of recombinant human GH (0, 10, 25, 50 ng/ml). The ovarian fragments non‐cultured (control) and cultured were processed for classic histology, mechanical isolation and electron transmission microscopy (MET). The parameters underwent anova (Tukey′s and Dunnett′s tests) and chi‐square test (χ²). After 7 days of culture, the treatment with 50 ng/ml GH showed no differences with fresh control (p > 0.05) and had greater effectiveness than in the 0, 10 and 25 ng/ml GH concentrations of the morphologically normal follicles. Regarding the primordial follicles, a reduction was observed in the 50 ng/ml GH concentration concomitant with the significant increase in developing follicles, differing from both the fresh control and the other GH concentrations tested. In addition, 50 ng/ml GH showed a larger follicle and oocyte diameter when compared to the other treatments cultured. Similar structures were ultrastructurally observed in the control group, 50 ng/ml GH. Follicles cultured in 10 ng/ml GH showed nuclear invagination, vacuoles and lesioned basal membrane. Hence, it is concluded that 50 ng/ml GH is the most effective concentration for the development of preantral follicles cultured in situ.  相似文献   

Fusion of Boar Sperm with Nanoliposomes Prepared from Synthetic Phospholipids          下载免费PDF全文

VR Kasimanickam  MM Buhr 《Reproduction in domestic animals》2016,51(4):461-466

Liposomes are artificial membrane vesicles that can be used to test and model the functions and interactions of various biological membranes, or as a carrier system to deliver biologically active substances into the cells, or to incorporate lipids into the plasma membrane of target cells to modify membrane structure–function relationships. Sperm plasma membrane undergoes lipid modification during maturation in epididymis and during capacitation in the female reproductive tract to facilitate fertilization. Natural variation in the amounts and composition of lipids in the sperm plasma membrane may also contribute to the species‐specific sperm sensitivities to handling and storage conditions. Boar sperm are notoriously susceptible to membrane damage and are resistant to compositional alteration by artificial liposomes. This study used flow cytometry to demonstrate stable incorporation of nanoliposomes prepared from a complex mixture of various phospholipids (phosphatidylcholine : phosphatidylethanolamine : sphingomyelin : phosphatidylserine : phosphatidylinositol) with high fusion efficiency. Over 90% of sperm rapidly took up fluorescently labelled liposomes and retained the lipids for at least 60 min, in a significant time‐ and concentration‐dependent manner. This unique fusion efficacy could be used to alter sperm plasma membrane composition and hence membrane‐based functional responses.  相似文献   

不同铵离子浓度与pH人工海水对栉江瑶精子激活效果的比较          下载免费PDF全文

邱达观  兰帅勤  陈煜  毛晶  臧战  VASQUEZ Hebert Ely  於锋  王爱民  郑兴  顾志峰 《渔业科学进展》2024,45(3):214-223

栉江瑶(Atrina pectinata)为我国重要的海洋经济双壳贝类,近年来,其养殖生产活动备受养殖企业关注,为发展和优化其人工繁殖技术,本研究探究了人工海水中铵离子浓度和pH的变化对栉江瑶新鲜精子游泳运动的激活作用,定量描述了高度活化状态下精子曲线运动速率(VCL)、直线运动速率(VSL)、平均路径运动速率(VAP)和鞭毛摆动频率(BCF)的运动学特征,并对精子ATP含量、ATP酶与超氧化物歧化酶(SOD)活性进行了记录。结果显示,简单提高海水pH可略微提高栉江瑶精子运动率,但无法使精子进入高度活化状态;含有铵离子的碱化海水可有效激发精子游泳运动,3 mmol/L氨海水激活效果最佳。经3 mmol/L氨海水激活后,精子活力等级(MI)在21 min内一直保持在≥4的状态,在激活的前3 min内精子运动率都在80%以上,VCL>56 μm/s,VSL>17 μm/s,VAP>30 μm/s,BCF>6 Hz。精子ATP含量在激活5 min后降低至初始含量的30.29% [(128.80± 66.92) μmol/g prot],随后,无显著变化(P>0.05)。精子Na+-K+-ATP酶和Ca2+-Mg2+-ATP酶活性在运动过程中较为稳定,其中,Na+-K+-ATP酶活性较低[(0.62±0.03) U/mg prot],Ca2+-Mg2+-ATP酶活性较高[(6.08± 0.04) U/mg prot]。精子SOD活性在15 min内逐步降低至[(1.23±0.73) U/mg prot],随后维持稳定。本研究可为栉江瑶精子激活机制深入研究提供基础,助力发展栉江瑶人工繁育技术。  相似文献   

Bovine mycotic abortion: some epidemiological aspects     

B M Williams  B J Shreeve  C N Hebert  P W Swire 《The Veterinary record》1977,100(18):382-385

Records from 898 cases of bovine mycotic abortion occurring over the five years 1969 to 1974 in South Wales were examined with particular reference to incidence and climate. Mean incidence was lowest in September and highest in January and February. Annual incidence of Aspergillus-type infection decreased but that of Mucortype did not alter significantly. Most abortions occurred during the last trimester of pregnancy. The abortion rate for cattle fed hay in cowsheds was extremely high compared with that for other management systems. No correlation could be detected between total rainfall or number of raindays in June and September and mycotic abortions occurring over the succeeding 12 months. Fungal abortion was followed by pregnancy in most cases where subsequent breeding performance was known.  相似文献   

Erythrocyte and leukocyte parameters in fetal and neonatal piglets     

D H Upcott  C N Hebert  M Robins 《Research in veterinary science》1973,15(1):8-12

  相似文献   

Evaluation of pheromone release from commercial mating disruption dispensers     

Tomaszewska E  Hebert VR  Brunner JF  Jones VP  Doerr M  Hilton R 《Journal of agricultural and food chemistry》2005,53(7):2399-2405

Pome fruit growers and crop consultants have expressed concerns about the seasonal release performance of commercial codling moth mating disruption dispenser products. Because of these concerns, we developed a laboratory flow-through volatile collection system (VCS) for measuring the volatile release of the codling moth sex pheromone, codlemone, from commercially available hand-applied dispensers. Under controlled air-flow and temperature conditions, the released vapor was trapped onto a polyurethane foam adsorbent followed by solvent extraction, solvent reduction, and GC/MS determination. Method recovery and breakthrough validations were performed to demonstrate system reliability before determining codlemone release from commercial dispensers field-aged over 140 days. The volatile collection was carried out in a consistent manner among five dispenser types most commonly used by growers, so that direct comparison of performance could be made. The comparison showed differences in the amount of pheromone released and in the patterns of release throughout the season between dispenser types. The variation in release performance demonstrates the need for routine evaluation of commercially marketed mating disruption dispensers. We believe that the simple and cost-effective volatile collection system can assist pheromone dispenser manufacturers in determining seasonal dispenser performance before new products are introduced into the commercial market and in rapidly verifying dispenser release when field-aged dispenser efficacy is in question.  相似文献   

Effects of a Cassia occidentalis extract in the domestic chicken (Gallus domesticus)     

M J Graziano  W Flory  C L Seger  C D Hebert 《American journal of veterinary research》1983,44(7):1238-1244

The effects of an orally administered Cassia occidentalis extract were studied in chickens. A 25 mM sodium bicarbonate solution effectively extracted the toxic principle. Toxic activity was reduced, but not eliminated, when the heated extract (90 C, 40 minutes) was administered. The toxic principle was in the pellet after centrifuging the extract at 38,000 X g. Daily administration of the extract produced weight loss and muscular weakness. Microscopic examination revealed skeletal and cardiac muscle degeneration and hepatocyte vacuolation. Electron microscopic examination revealed mitochondrial disruption. Respiratory studies on liver mitochondria isolated from treated chickens demonstrated lower phosphorylation ratios, lower respiratory control ratios, and lower rates of oxygen use.  相似文献   

Blood Mineral Levels of Cattle in Kenya     

Gitter  M.  Boarer  C.  Howard  D. A.  Hebert  C. Nancy 《Tropical animal health and production》1975,7(2):95-104

Tropical Animal Health and Production - In a survey carried out in cattle on six farms over a period of one year 11•2 per cent of samples had a serum calcium concentration of less than...  相似文献   

Role of silicon in developing cotton fibers     

E. K. Boylston  J. J. Hebert  T. P. Hensarling  J.M. Bradow  D. P. Thibodeaux 《Journal of plant nutrition》2013,36(1):131-148

The concentration of silicon is high during the elongation phase (approximately day 1 through day 21 post‐anthesis) of cotton fiber development. The ratio of the amount of silicon per mass of fiber peaks at the time when secondary wall initiation occurs. This suggests that silicon has one or more functions during a specific phase of cotton fiber development.  相似文献