小篷竹群落邻体干扰指数的研究

运用邻体干扰指数模型,分析小蓬竹群落种内、种间竞争强度,确立小蓬竹群落的竞争干扰因子。结果表明,在小蓬竹群落中,对小蓬竹干扰指数最大是猴樟,其次是小蓬竹本身。在自然情况下的群落演替过程中,猴樟种群将占优势,最终小蓬竹将在小蓬竹群落彻底消失。     

Synchronization of Ovulation and Fixed Time Intrauterine Insemination in Ewes

A novel method for oestrus-ovulation synchronization in sheep followed by fixed time insemination is presented herewith. Mature dry ewes (n = 28) of Karagouniko breed being at an unknown stage of the oestrous cycle, were used during the middle of breeding season. The treatment protocol consisted of an initial administration of a GnRH analogue followed 5 days later by a prostaglandin F2alpha injection. Thirty-six hours later a second GnRH injection was administered to synchronize ovulation, and laparoscopic intrauterine insemination was performed 12-14 h later. Three days after insemination, fertile rams were introduced into the flock twice daily and oestrus-mating detection was carried out. For progesterone (P(4)) determination, blood samples were collected on alternate days, starting 2 days before the first GnRH injection and continuing for 17 days after insemination. An additional sample was taken on the day of insemination. Pregnancy diagnosis was carried out by trans-abdominal ultrasonography. Fourteen ewes (50%) conceived at insemination and maintained pregnancy; from the remainder 14 ewes 10 became pregnant at natural service, while four, although they mated at least two to three times, failed to conceive. In response to the first GnRH, P(4) concentration increased at higher levels in ewes that conceived at AI compared with those that failed to conceive (47.54 and 22.44%, respectively; p < 0.05). Significant differences (p < 0.05) in mean P(4) concentration between pregnant and non-pregnant animals were detected 1 day before AI (0.17 +/- 0.06 and 0.26 +/- 0.14 ng/ml, respectively) on the day of AI (0.15 +/- 0.04 and 0.24 +/- 0.08 ng/ml, respectively) as well as 9 and 11 days thereafter (0.48 +/- 0.12 and 0.38 +/- 0.12 ng/ml; 0.68 +/- 0.14 and 0.50 +/- 0.18 ng/ml, respectively). These results indicate that using the proposed protocol, an acceptable conception rate can be achieved which could be further improved by modifying the time intervals between interventions.     

Identification of equine herpesvirus 3 (equine coital exanthema virus), equine gammaherpesviruses 2 and 5, equine adenoviruses 1 and 2, equine arteritis virus and equine rhinitis A virus by polymerase chain reaction

OBJECTIVE: To develop rapid (< 8 hour) tests using polymerase chain reaction (PCR) for the diagnosis of equine herpesvirus 3 (EHV3; equine coital exanthema virus), equine gammaherpesviruses 2 (EHV2) and EHV5, equine adenovirus 1 (EAdV1), EAdV2, equine arteritis virus (EAV), equine rhinitis A virus (ERAV; formerly equine rhinovirus 1) DESIGN: Either single round or second round (seminested) PCRs were developed and validated. METHODS: Oligonucleotide primers were designed that were specific for each virus, PCR conditions were defined and the specificity and sensitivity of the assays were determined. The application of the tests was validated using a number of independent virus isolates for most of the viruses studied. The PCRs were applied directly to clinical samples where samples were available. RESULTS: We developed a single round PCR for the diagnosis of EHV3, a seminested PCR for EHV2 and single round PCRs for EHV5, EAdV1, EAdV2 and RT-PCRs for EAV and ERAV. The PCR primer sets for each virus were designed and shown to be highly specific (did not amplify any recognised non-target template) and sensitive (detection of minimal amounts of virus) and, where multiple virus isolates were available all isolates were detected. CONCLUSION: The development and validation of a comprehensive panel of PCR diagnostic tests, predominantly for viruses causing equine respiratory disease, that can be completed within 8 hours from receipt of clinical samples, provides a major advance in the rapid diagnosis or exclusion diagnosis of these endemic equine virus diseases in Australia.     

Relationships among Puberty,Muscle and Fat,and Liveweight Gain during Mating in Young Female Sheep

Greater depths of muscle are associated with better reproductive performance in ewe lambs, but, in adult ewes, reproductive performance also seems to vary with liveweight gain during the mating period. Therefore, in a large field study with Merino ewe lambs, we tested whether the relationships among eye muscle depth (EMD), fat depth (FAT) and reproductive performance depend on liveweight gain during the mating period. We selected lambs with a wide range in phenotypic values for depths of eye muscle (EMD) and fat (FAT) and assigned them to dietary treatments designed to achieve low (LOW, n = 244) or high (HIGH, n = 237) rates of liveweight gain during a 28‐day mating period. The LOW treatment maintained live weight, whereas the HIGH treatment gained 179 ± 3.8 g/day (p < 0.001). From those ewe lambs that attained puberty, first oestrus was detected at live weight 37.8 ± 0.2 kg and age 232 days. The proportion of ewes that attained puberty increased with EMD (p < 0.01). Ewes from the HIGH treatment were more fertile (pregnant ewes per 100 ewes exposed to rams) and had a higher reproductive rate (foetuses in utero per 100 ewes exposed to rams; p < 0.001) than those from the LOW treatment. Fertility and reproductive rate were positively correlated with weight gain during mating as well as live weight at the start of mating, FAT and EMD (p < 0.05 to <0.001). We conclude that faster growth, due to either extra nutrition during mating or higher phenotypic potential for fat and muscle, will increase reproductive performance in ewe lambs mated at 8 months of age.     

Low glyphosate rates do not affect Citrus limonia (L.) Osbeck seedlings

BACKGROUND: Glyphosate is used to control weeds in citrus orchards, and accidental spraying or wind drift onto the seedlings may cause growth arrest owing to metabolism disturbance. Two experiments were carried out to investigate the effect of non‐lethal rates (0, 180, 360 and 720 g AI ha^?1) of glyphosate on four‐month‐old ‘Cravo’ lime, Citrus limonia (L.) Osbeck, seedlings. Photosynthesis and the concentrations of shikimic acid, total free amino acids and phenolic acids were evaluated. RESULTS: Only transitory effects were observed in the contents of shikimate and total free amino acids. No visual effects were observed. CONCLUSION: The present study showed that glyphosate at non‐lethal rates, which is very usual when accidental spraying or wind drift occurs in citrus orchard, did not cause severe metabolic damage in ‘Cravo’ lime seedlings. Copyright © 2009 Society of Chemical Industry     

Heat shock is lethal to fibroblasts microinjected with antibodies against hsp70

Synthesis of a small group of highly conserved proteins in response to elevated temperature and other agents that induce stress is a universal feature of prokaryotic and eukaryotic cells. Although correlative evidence suggests that these proteins play a role in enhancing survival during and after stress, there is no direct evidence to support this in mammalian cells. To assess the role of the most highly conserved heat shock protein (hsp) family during heat shock, affinity-purified monoclonal antibodies to hsp70 were introduced into fibroblasts by needle microinjection. In addition to impairing the heat-induced translocation of hsp70 proteins into the nucleus after mild heat shock treatment, injected cells were unable to survive a brief incubation at 45 degrees C. Cells injected with control antibodies survived a similar heat shock. These results indicate that functional hsp70 is required for survival of these cells during and after thermal stress.     

低O 2和高CO 2对草莓采后酯类生物合成的作用模式

草莓(Fragria ananassa Duck.cv.Chandler)果实于采收当天分别放在:①空气;②0.25%O_2;③21%O_2+50%CO_2;④0.25%O_2+50%CO_2(用 N_2平衡)四种流动气体条件(5℃)下1～7d,以研究气调贮藏对草莓的挥发性物质和发酵性酶活性的影响。在三种气调贮藏条件下,果肉中乙醛、乙醇、乙酸乙酯、丁酸乙酯的浓度较空气处理明显增加而乙酸异丙酯和乙酸丁酯的含量下降。气调贮藏处理增加了丙酮酸脱羧酶(PDC)和乙醇脱氢酶(ADH)的活性但略微减少了醇酰基转移酶(即酯化酶,AAT)的活性。低 O_2、高 CO_2条件下草莓中乙醇的大量累积加速了乙酸乙酯的生物合成。由于 AAT 活性的降低及过量的乙醇与其他醇类化合物对相同羧基化合物的竞争作用导致其他乙酸酯类产物的减少。     

Elevation change of the southern greenland ice sheet

Seasat and Geosat satellite altimeter measurements for the Greenland ice sheet (south of 72 degreesN latitude) show that surface elevations above 2000 meters increased at an average rate of only 1. 5 +/- 0.5 centimeters per year from 1978 to 1988. In contrast, elevation changes varied regionally from -15 to +18 centimeters per year, seasonally by +/-15 centimeters, and interannually by +/-8 centimeters. The average growth rate is too small to determine if the Greenland ice sheet is undergoing a long-term change due to a warmer polar climate.     

Pressure-induced amorphization and negative thermal expansion in ZrW2O8

It has recently been shown that zirconium tungstate (ZrW2O8) exhibits isotropic negative thermal expansion over its entire temperature range of stability. This rather unusual behavior makes this compound particularly suitable for testing model predictions of a connection between negative thermal expansion and pressure-induced amorphization. High-pressure x-ray diffraction and Raman scattering experiments showed that ZrW2O8 becomes progressively amorphous from 1.5 to 3.5 gigapascals. The amorphous phase was retained after pressure release, but the original crystalline phase returned after annealing at 923 kelvin. The results indicate a general trend between negative thermal expansion and pressure-induced amorphization in highly flexible framework structures.