Germination ecology of seeds of the annual weeds Capsella bursa-pastoris and Descurainia sophia originating from high northern latitudes     

C C Baskin  †  P Milberg‡  L Andersson§  & J M Baskin 《Weed Research》2004,44(1):60-68

Low temperatures may inhibit dormancy break in seeds of winter annuals, therefore it was hypothesized that seeds of Capsella bursa‐pastoris and Descurainia sophia that mature at high latitudes in late summer–early autumn would not germinate until they had been exposed to high summer temperatures. Consequently, germination would be delayed until the second autumn. Most freshly matured seeds of both species collected in August and September in southern Sweden were dormant. After 3 weeks of burial at simulated August (20/10°C) and September (15/6°C) temperatures, 28 and 27%, respectively, of the C. bursa‐pastoris and 56 and 59%, respectively, of the D. sophia seeds germinated in light at 15/6°C. In contrast, in germination phenology studies conducted in Sweden, only a few seeds of either species germinated during the first autumn following dispersal. However, there was a peak of germination of both species the following spring, demonstrating that dormancy was lost during exposure to the low habitat temperatures between late summer and early autumn and spring. Nearly 100% of the seeds of both species subjected to simulated annual seasonal temperature changes were viable after 30.5 months of burial. In the burial study, exhumed seeds of C. bursa‐pastoris were capable of germinating to 98–100% in light at the simulated spring–autumn temperature regime (15/6°C) in both spring and autumn, while those of D. sophia did so only in autumn. In early spring, however, seeds of D. sophia germinated to 17–50% at 15/6°C. Thus, most seeds of these two annual weeds that mature in late summer do not germinate in the first autumn, but they may do so the following spring or in some subsequent autumn or spring.  相似文献   

Ontogeny and function of the pituitary-gonadal axis during fetal development in sheep     

AN Brooks  GB Thomas 《Reproduction in domestic animals》1995,30(4):158-162

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Endometrial hyperplasia,polyps, and adenomyosis associated with unopposed estrogen in rhesus monkeys (Macaca mulatta)     

Baskin GB  Smith SM  Marx PA 《Veterinary pathology》2002,39(5):572-575

The purpose of this study was to evaluate the effects of estrogen and progesterone on the vaginal mucosa and their role in vaginal transmission of simian immunodeficiency virus. Incidentally, endometrial hyperplasia was observed in estrogen-treated monkeys at necropsy. Six adult female rhesus monkeys (Macaca mulatta) were ovariectomized and 120 days later received two subcutaneous implants, each containing 200 mg estradiol. The animals were sacrificed 17-27 months later and the uterus examined at necropsy. All the monkeys had simple endometrial hyperplasia, some with polyps or adenomyosis, at the time of necropsy. The severity of the changes correlated with the time between implantation and necropsy. The lesions were similar to endometrial hyperplasia caused by unopposed estrogen in women, but occurred over a time period that is suitable for experimental manipulation. Rhesus monkeys could be used as a model to test the safety of various combinations of sex steroids for the prevention of postmenopausal symptoms in women.  相似文献   

Factors influencing first remission and survival in 145 dogs with lymphoma: a retrospective study     

Baskin CR  Couto CG  Wittum TE 《Journal of the American Animal Hospital Association》2000,36(5):404-409

Records of 145 dogs diagnosed with lymphoma were reviewed to evaluate for factors influencing duration of remission and survival. Dogs with histories of certain chronic inflammatory diseases were 3.23 times more likely to relapse (relative risk, 3.23) than the overall population. Dogs with World Health Organization (WHO) stage IV lymphoma or those treated with a protocol containing cyclophosphamide, doxorubicin, vincristine, prednisone, and sulfatrimethoprim (CHOP) had lower relative risks of relapse (0.32 and 0.085, respectively). Progressive disease after induction, gastrointestinal toxicity from induction, and clinical signs (i.e., substage b lymphoma) were associated with higher relative risks of death (3.5, 2.64, and 2.02, respectively).  相似文献   

Intracerebroventricular Infusion of Leptin into Mature Merino Rams of Different Metabolic Status: Effects on Blood Concentrations of Glucose and Reproductive and Metabolic Hormones     

P Celi  D Blache  MA Blackberry  GB Martin 《Reproduction in domestic animals》2006,41(1):79-90

In mature Merino rams, nutrition is one of the external cues that most strongly affects the reproductive centres of the preoptic-hypothalamic continuum. The signalling pathways that link dietary status and the activity of the neurones that produce gonadotrophin-releasing hormone signals are thought to be partly hormonal in nature to reflect the amount of body reserves. Among the hormones thought to be involved are insulin and leptin. This study tested whether recombinant bovine leptin infused (0.4 microg/h) into the third cerebral ventricle would stimulate pulsatile luteinizing hormone (LH) secretion in mature Merino rams when their energy status was low or decreasing, during both chronic (fasting) and acute reductions of energy balance. Leptin may interact with other hormones that depend on energy availability, so we also monitored changes in circulating concentrations of insulin, thyroid hormones, growth hormone, prolactin and adrenocorticotrophin. Overall, our data do not support this hypothesis. The dietary regimes induced clear responses in the metabolic profiles of the animals but there was no clear effect of central leptin administration on LH pulse frequency. The relationships between the hormonal systems measured in the present study add weight to the contention that leptin plays only a permissive role in the nutritional control of the reproductive axis and that other hormonal signals (particularly insulin) or pathways are acting in concert with leptin to stimulate the reproductive axis.  相似文献   

Lethal short-limbed dwarfism in a rhesus monkey     

D H Zeman  G B Baskin 《Veterinary pathology》1986,23(2):198-200

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Spatial and temporal evaluation of veterinarians and veterinary employers relative to human and domesticated animal populations in Australia 2002–2012          下载免费PDF全文

GB Smyth  IJ East  RM Wicks 《Australian veterinary journal》2015,93(5):137-144

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Rhino Biology: Keeping Tabs on an Endangered Species: Isotopic IDs for Rhino Horn     

Baskin Y 《Science (New York, N.Y.)》1991,252(5010):1257

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Electrons in finite-sized water cavities: hydration dynamics observed in real time     

Paik DH  Lee IR  Yang DS  Baskin JS  Zewail AH 《Science (New York, N.Y.)》2004,306(5696):672-675

We directly observed the hydration dynamics of an excess electron in the finite-sized water clusters of (H2O)n- with n = 15, 20, 25, 30, and 35. We initiated the solvent motion by exciting the hydrated electron in the cluster. By resolving the binding energy of the excess electron in real time with femtosecond resolution, we captured the ultrafast dynamics of the electron in the presolvated ("wet") and hydrated states and obtained, as a function of cluster size, the subsequent relaxation times. The solvation time (300 femtoseconds) after the internal conversion [140 femtoseconds for (H2O)35-] was similar to that of bulk water, indicating the dominant role of the local water structure in the dynamics of hydration. In contrast, the relaxation in other nuclear coordinates was on a much longer time scale (2 to 10 picoseconds) and depended critically on cluster size.  相似文献   

Ventricular septal defect repair in a small dog using cross-circulation     

GB HUNT  MRB PEARSON †  CR BELLENGER †  R. MALIK † 《Australian veterinary journal》1995,72(10):379-382

SUMMARY A haemodynamically significant ventricular septal defect was diagnosed in a 3-month-old male Cavalier King Charles Spaniel. A median sternotomy was performed and the 6.5 kg dog placed on cardiopulmonary bypass using pump-assisted cross-circulation. A 10 mm diameter peri-membranous ventricular septal defect was closed using a continuous suture of 4–0 polypropylene, via a 2.5 cm incision in the right ventricular outflow tract. The duration of cardiopulmonary bypass was 90 minutes. Complications in the immediate postoperative period were mild and easily managed.  相似文献