Nutritional restriction in utero programs postnatal muscle development in lambs

The effect of nutritional programming during late gestation on evoked compound muscle action potentials (CMAP) during early postnatal life was examined. Lambs were born to ewes that were fed either an adequate or low nutrient supply during the last trimester of gestation. Lambs were born to either a ram with a high genetic potential for daily live weight gain, or a ram with a high genetic potential for both daily gain and lean content. CMAP signals were evoked by electrical stimulation and recordings were analyzed in terms of area, amplitude, width at 50% maximal height and both leading and trailing slopes. Significant effects of nutrient restriction during late gestation were measured for lamb birthweight, bodyweight at day 21 and growth rate (P < 0.001), as well as CMAP area, corrected peak and slope for Musculus longissimus dorsi at day 21 and as early as day 10 for Musculus biceps femoris. In conclusion, nutrient restriction during the last trimester of gestation influences evoked CMAP signal parameters postnatally in a muscle‐specific fashion, and muscle development may be related to paternal genetic background.     

两种噁二唑类化合物对蔬菜害虫的生物活性研究

对两种新型     

牛磺酸营养研究进展

牛磺酸是一种游离氨基酸,因其具有广泛的生物学效应而受到营养学家的极大关注。本文综述了牛磺酸的性质、分布、代谢、生理功能及其在动物营养中的应用。     

十三星瓢虫和多异瓢虫对苜蓿斑蚜的捕食作用研究

研究了十三星瓢虫和多异瓢虫个体间的干扰作用对捕食作用的影响,以及2种瓢虫在苜蓿斑蚜不同密度下的功能反应。结果表明,2种瓢虫对苜蓿斑蚜的捕食率随着捕食者个体间的相互干扰作用的增加而下降,苜蓿斑蚜之间的关系随着瓢虫数量的增加呈幂函数下降曲线,2种瓢虫个体间存在明显的相互干扰效应,且捕食作用随着猎物密度的增加而增大,还与虫态、温度、饥饿程度等有关。干扰作用和功能反应的数学模拟理论值与观察值很接近,经X2检验后,误差不显著(P>0.05)。     

桔梗的"引经"作用对左旋氧氟沙星在鸡体内药物分布的影响

72只25日龄健康黄杂鸡随机均分为2组，Ⅰ组单剂量内服左氧氟沙星（10mg／kg），Ⅱ组左氧氟沙星（10mg／kg）与桔梗煎液（2g／kg）联合内服。采用高效液相色谱法测定鸡体内不同组织中药物的浓度。结果表明，桔梗与左氧氟沙星联用，明显影响了左氧氟沙星在健康鸡体内的分布，其中，肺、心、肾组织最高药物浓度较单用左氧氟沙星组显著增高，而肝脏的药物浓度较单用左氧氟沙星有所降低。     

抗植物病毒剂作用机制研究进展

根据植物病毒侵染寄主、体内复制和症状表达的过程,综述了目前所开发的抗病毒剂的作用机制,以及药剂、病毒(TMV)对寄主(烟草)基因表达差异的研究情况,分析了抗病毒剂研究中存在的问题,并进行了展望。     

Microscopic, Biochemical and Physiological Assessment of the Effect of Methylene Bisthiocyanate on the Sapstain Fungus Ophiostoma floccosum

In vitro effects of methylene bisthiocyanate (MBT) on hyphal morphology and ultra-structure of Ophiostoma floccosum were examined using differential interference contrast, epifluorescence and transmission electron microscopy (TEM). To understand the mode of action of MBT, experiments were undertaken to measure potassium ion (K⁺) leakage from cells, oxygen consumption, glucose and ATP levels. Differential interference contrast microscopy indicated that MBT caused rapid changes in O. floccosum hyphae resulting in extensive vaculoation and accumulation of granular materials within the cytoplasm. Epifluorescence microscopy provided evidence that MBT treatment causes a loss in the permeability properties of the plasma membrane. TEM showed retraction of the plasma membrane from the cell wall, aggregation of cytoplasmic contents, vesiculation of membranous components, a dramatic increase in vacuolation, and eventually a complete loss in the integrity of organelles. There was a rapid efflux of intracellular K⁺ ions from cells, a substantial loss in K⁺ ions occurring within the first 5 min of MBT treatment. The rate of K⁺ leakage was MBT concentration treatment-time dependent. The study also showed that the effect of lower concentrations of MBT (0.01 and 0.1 mM) on respiratory activity was negligible. However, at the same concentrations, glucose consumption and ATP production were affected. Taken together, these observations suggest that the target site of MBT in O. floccosum alters membrane properties and uncouples oxidative phosphorylation from the respiratory chain.     

Variable Effects of Nitrous Oxide at Multiple Levels of the Central Nervous System in Goats

The direct and indirect effects of nitrous oxide (N₂O) on the nociceptive responses of lumbar dorsal horn neurons, and the indirect effects on midbrain reticular formation (MRF) neurons and thalamic neurons were determined in goats anaesthetized with isoflurane. The technique used enabled the differential delivery of N₂O to either the torso or the cerebral circulation, thus allowing assessment of the direct spinal and indirect brain effects of N₂O. Systemic delivery of N₂O appeared to have divergent effects, facilitating (4/11) or depressing (7/11) the responses of dorsal horn neurons. Such divergent effects were also observed when N₂O was differentially delivered to the circulation in the torso (i.e. the spinal cord). Likewise, MRF and thalamic responses to noxious stimulation were variably affected by administration of N₂O to the torso, with some cells facilitated (7/13 MRF neurons, 3/8 thalamic neurons) and others depressed (6/13 MRF neurons, 5/8 thalamic neurons). It appears that N₂O has variable effects on the caprine CNS. The facilitatory action of N₂O might partially explain why it is a relatively weak anaesthetic.     

Beetle-specific Bacillus thuringiensis Cry3Aa toxin reduces larval growth and curbs reproduction in Spodoptera littoralis (Boisd.)

Application of Bacillus thuringiensis tenebrionis (Bt) and expression of the Bt protein Cry3Aa in genetically modified crops are used for targeted control of the Colorado potato beetle Leptinotarsa decemlineata (Say). The Cry3A proteins are selectively toxic for the beetles but the present study describes effects of Cry3Aa on the Egyptian armyworm, Spodoptera littoralis (Boisduval). Cry3Aa expressed in potatoes or added to an agar-base wheat-germ diet reduced the growth of S. littoralis caterpillars and the fertility of adults. The effect of 1.4 mg kg(-1) Cry3Aa in potato leaves was comparable with that of 3.3 mg kg(-1) in the diet. This difference in activity was correlated with better digestibility and higher conversion efficiency of the diet that also supported higher reproduction rate: S. littoralis grown on the potatoes reached a similar size to those on the diet but laid only 702 instead of 1077 eggs per female. Cry3Aa consumption reduced body growth as a consequence of lower food intake without significantly affecting food digestibility and the conversion efficiency of nutrients. The 11% and 5% body weight reductions caused by 1.4 mg kg(-1) Cry3Aa in potatoes and 3.3 mg kg(-1) in the diet, respectively, were associated with 74% and 65% reduction in the number of progeny; S littoralis grown on a diet with 9.1 mg kg(-1) Cry3Aa were 10% smaller and produced no viable progeny. These data suggest that the curtailment of reproduction was not caused by a general shortage of nutrient reserves but by a more direct Cry3Aa effect on the reproduction process.     

In vivo effects of the fungicide ethaboxam on microtubule integrity in Phytophthora infestans

The effects of ethaboxam (LGC-30473), a novel thiazole carboxamide, on microtubule organization was investigated in Phytophthora infestans (Mont) de Bary (Oomycota) at the light microscope level using standard immunofluorescence and laser scanning confocal microscopy. Hyphal cells were exposed to various concentrations ranging from 0.01 to 1.0 microg ml(-1) of ethaboxam at incubation times of 30, 60 and 120 min. Microtubules were disrupted after exposure to ethaboxam for 30 min at 0.01 microg ml(-1). Similar experimental conditions were used to document the effects of ethaboxam on microtubule integrity in the model fungus Aspergillus nidulans (Eidam) Winter (Ascomycota) and in mammalian mouse 17 clone 1 cells. Under these conditions, there was no evidence to suggest that microtubules in A. nidulans and mouse culture cells were affected by the ethaboxam. These results indicate that ethaboxam is specific for the targeting of microtubule disruption in P. infestans.