Intracytoplasmic Glutathione Levels in Heifer Oocytes Cultured in different Maturation Media and its Effect on Embryo Development     

MJ Mertens  M López-Bejar  M-T Paramio 《Reproduction in domestic animals》2005,40(2):126-130

The present study was carried out to study the effect of different maturation media on embryo development of heifer oocytes and on their glutathione (GSH) synthesis during in vitro maturation (IVM). Immature heifer oocytes were matured in parallel in one of four maturation media: (i) Tissue Culture Medium (TCM)-199 supplemented with 10 ng/ml of epidermal growth factor (EGF); (i) TCM-199 supplemented with 10 ng/ml of EGF plus 1 microg/ml of FSH; (iii) TCM-199 supplemented with 10% of foetal bovine serum (FBS) and (iv) TCM-199 supplemented with 10% of FBS plus 1 microg/ml of FSH. Cow oocytes were used as control and were matured in TCM-199 supplemented with 10 ng/ml of EGF. No differences were observed in blastocyst rate among the different heifer oocyte groups (8.8, 7.5. 8.4 and 6.8%, respectively) however, the percentage of blastocysts obtained from cow oocytes was significantly higher (30%; p < 0.01) than those obtained from heifer oocytes. De novo GSH synthesis during oocyte maturation of heifer and cow oocytes was detected. No significant differences in intracytoplasmic GSH levels were observed among the experimental heifer oocyte groups or between heifer and cow oocytes both before and after IVM. In conclusion, the blastocyst yield obtained from heifer oocytes was lower than that from cow oocytes and this fact could not be explained by significant differences in intracytoplasmic GSH contents of oocytes before or after IVM.  相似文献   

恩拉霉素的研究进展   总被引：4，自引：0，他引：4  

周岷江  严玉宝  胡娟  余华  叶建强  谢晶  汤华钊 《中国兽药杂志》2007,41(12):42-44

概述了恩拉霉素的理化特性、药效学、毒理学和临床应用研究进展,展望了今后恩拉霉素的研究方向.  相似文献   

Temperature and surface-ocean water balance of the mid-holocene tropical western pacific     

MK Gagan  LK Ayliffe  D Hopley  JA Cali  GE Mortimer  J Chappell  MT McCulloch  MJ Head 《Science (New York, N.Y.)》1998,279(5353):1014-1018

Skeletal Sr/Ca and 18O/16O ratios in corals from the Great Barrier Reef, Australia, indicate that the tropical ocean surface approximately 5350 years ago was 1 degrees C warmer and enriched in 18O by 0.5 per mil relative to modern seawater. The results suggest that the temperature increase enhanced the evaporative enrichment of 18O in seawater. Transport of part of the additional atmospheric water vapor to extratropical latitudes may have sustained the 18O/16O anomaly. The reduced glacial-Holocene shift in seawater 18O/16O ratio produced by the mid-Holocene 18O enrichment may help to reconcile the different temperature histories for the last deglaciation given by coral Sr/Ca thermometry and foraminiferal oxygen-isotope records.  相似文献   

Formation of molecular chlorine from the photolysis of ozone and aqueous sea-salt particles     

KW Oum  MJ Lakin  DO DeHaan  T Brauers  BJ Finlayson-Pitts 《Science (New York, N.Y.)》1998,279(5347):74-77

Halogen atoms from the reactions of sea-salt particles may play a significant role in the marine boundary layer. Reactions of sodium chloride, the major component of sea-salt particles, with nitrogen oxides generate chlorine atom precursors. However, recent studies suggest there is an additional source of chlorine in the marine troposphere. This study shows that molecular chlorine is generated from the photolysis of ozone in the presence of sea-salt particles above their deliquescence point; this process may also occur in the ocean surface layer. Given the global distribution of ozone, this process may provide a global source of chlorine.  相似文献   

光和磷对苔草属植物胡萝卜状根形成及分布格局的影响     

古文丽  李卫忠  Martin J Lechowicz 《西北农林科技大学学报(自然科学版)》2007,35(12):210-216

为了了解光照和土壤中磷对苔草属植物胡萝卜状根形成及分布格局的影响，2006年夏季在加拿大麦吉尔人工气候室内，对北美苔草属植物进行了不同光照强度和磷浓度组合的处理，以诱导苔草属植物胡萝卜状根的形成。结果发现：（1）苔草属植物的胡萝卜状根主要在低磷条件下形成，其中54％的植株在低磷条件下形成胡萝b状根，而高磷条件下只有4％的植株形成；（2）在相同的光照和磷处理条件下，处理时间对苔草属植物胡萝b状根的形成无显著影响；（3）遮荫影响苔草属植物胡萝b状根的形成，其中在“低磷＋全光照”条件下形成胡萝b状根的植株占处理植株总数的52％，而在“低磷＋遮荫”条件下形成胡萝卜状根的植株只占22％；（4）在苔草属植物中，胡萝卜状根只发生在苔草亚属（Subgen．CaYex）植物中，其中23组81种苔草亚属中78％的种类形成胡萝卜状根，而在二柱苔草亚属（Subgen．Vignea）植物中，5组9种苔草植物均无胡萝卜状根形成。可见，胡萝卜状根的形成不仅受环境因素（养分、光照）的影响，而且还与其系统发育有关。  相似文献   

Mechanism of the Zonal Displacements of the Pacific Warm Pool: Implications for ENSO   总被引：7，自引：0，他引：7  

J Picaut  M Ioualalen  C Menkes  T Delcroix  MJ McPhaden 《Science (New York, N.Y.)》1996,274(5292):1486-1489

The western equatorial Pacific warm pool is subject to strong east-west migrations on interannual time scales in phase with the Southern Oscillation Index. The dominance of surface zonal advection in this migration is demonstrated with four different current data sets and three ocean models. The eastward advection of warm and less saline water from the western Pacific together with the westward advection of cold and more saline water from the central-eastern Pacific induces a convergence of water masses at the eastern edge of the warm pool and a well-defined salinity front. The location of this convergence is zonally displaced in association with El Nino-La Nina wind-driven surface current variations. These advective processes and water-mass convergences have significant implications for understanding and simulating coupled ocean-atmosphere interactions associated with El Nino-Southern Oscillation (ENSO).  相似文献   

Differential Rotation and Dynamics of the Solar Interior     

MJ Thompson  J Toomre  ER Anderson  HM Antia  G Berthomieu  D Burtonclay  SM Chitre  J Christensen-Dalsgaard  T Corbard  M DeRosa  CR Genovese  DO Gough  DA Haber  JW Harvey  F Hill  R Howe  SG Korzennik  AG Kosovichev  JW Leibacher  FP Pijpers  J Provost  EJ Rhodes  J Schou  T Sekii  PB Stark  PR Wilson 《Science (New York, N.Y.)》1996,272(5266):1300-1305

Splitting of the sun's global oscillation frequencies by large-scale flows can be used to investigate how rotation varies with radius and latitude within the solar interior. The nearly uninterrupted observations by the Global Oscillation Network Group (GONG) yield oscillation power spectra with high duty cycles and high signal-to-noise ratios. Frequency splittings derived from GONG observations confirm that the variation of rotation rate with latitude seen at the surface carries through much of the convection zone, at the base of which is an adjustment layer leading to latitudinally independent rotation at greater depths. A distinctive shear layer just below the surface is discernible at low to mid-latitudes.  相似文献   

14 EVALUATION OF BACTERIAL CONTAMINATION AFTER UNCOMPLICATED EQUINE CASTRATIONS.     

MJ  Schoonover  HD Moll  CL Crowson  HW Jann 《Veterinary surgery : VS》2003,32(6):601-602

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Physiological, morphological and allocational plasticity in understory deciduous trees: importance of plant size and light availability     

Delagrange S  Messier C  Lechowicz MJ  Dizengremel P 《Tree physiology》2004,24(7):775-784

In a 4-year study, we investigated changes in leaf physiology, crown morphology and whole-tree biomass allocation in seedlings and saplings of shade-tolerant sugar maple (Acer saccharum Marsh.) and intermediate shade-tolerant yellow birch (Betula alleghaniensis Britt.) growing in natural understory light (0.5 to 35% of full sunlight) or in understory light reduced by 50% with shade nets to simulate the effect of gap closure. Leaf physiological parameters were mainly influenced by the light gradient, whereas crown morphological and whole-tree allocational parameters were mainly influenced by tree size. No single physiological, morphological or allocational trait was identified that could explain the difference in shade tolerance between the species. Yellow birch had higher growth rates, biomass allocation to branches and leaf physiological plasticity and lower crown morphological plasticity in unmodified understory light than sugar maple. Sugar maple did not display significant physiological plasticity, but showed variation with tree size in both crown morphology and whole-tree biomass allocation. When sugar maple was small, a greater proportion of whole-tree biomass was allocated to roots. However, physiological differences between the species decreased with decreasing light and most morphological and allocational differences tended to disappear with increasing tree size, suggesting that many species differences in shade-tolerance are expressed mainly during the seedling stage. Understory trees of both species survived for 4 years under shade nets, possibly because of higher plasticity when small and the use of stored reserves when taller.  相似文献   

Interacting effects of nutrients,pH - Al and elevated CO2 on the growth of red spruce (Picea rubens Sarg.) seedlings     

B. Shipley  M. Lechowicz  S. Dumont  W. H. Hendershot 《Water, air, and soil pollution》1992,64(3-4):585-600

A 4 mo growth chamber experiment was conducted to evaluate the presence and importance of interactions between nutrient supply, atmospheric CO₂ concentration, and four different combinations of pH — Al concentration on the growth, vitality, and tissue element concentrations of 1-yr-old red spruce seedlings. Solution chemistry was chosen to simulate soil conditions at a red spruce die-back site at Roundtop Mountain (Quebec) that has high acid loadings. CO₂ levels were chosen to simulate ambient levels and those expected in the next century. All three experimental factors affected growth and all factors except CO₂ affected the visual symptoms of die-back. There was an important interaction between nutrient levels and the different pH — Al combinations, indicating that the response of red spruce to various pH and Al concentrations changes with soil fertility. The positive growth response to enriched CO₂ was not sufficient to offset the negative effects of the acid rain induced stresses. A principal component analysis showed that multivariate functions of foliar element concentrations could clearly distinguish plants from different experimental regimes.  相似文献