黄杜鹃毒素和川楝素在果蝇幼虫神经肌肉传递的毒理效应初步观察(英)

黄杜鹃毒素Ⅱ,Ⅲ,Ⅴ和川楝素分别是从杀虫植物黄杜鹃Rhododendron molle和川楝Melia toosendan中提取、纯化的有效成分。本文利用胞内微电极记录技术,测定了它们对果蝇(Drosophila melangaster Meigen)3龄幼虫腹侧纵肌细胞内神经肌肉兴奋性接点电位的毒理效应。各化合物均可抑制并最终阻断该电位,阻断所需时间随处理浓度提高而缩短。3种黄杜鹃毒素的抑制活性顺序为Ⅲ>Ⅱ>Ⅴ.初步观察提示,上述植物杀虫物质对神经肌肉传递的破坏作用可能与其致死效应有关。     

川棟素在小鼠神经肌肉标本上的抗肉毒作用

本文用小白鼠离体膈神经膈肌标本,研究了川棟素的抗肉素作用。在我们所用的试验条件下,川棟素均显著地延长肉毒中毒标本对间接刺激收缩反应的麻痹时间,表明川楝素能在神经肌肉接头处对抗肉毒的阻遏作用。文中对川棟素的抗毒机理进行了讨论。     

秋水仙素对大鼠神经肌肉接头传递的作用

在不均匀牵拉法固定的离体大鼠膈神经膈肌标本上,用秋水仙素探讨了突触后膜的微管在神经肌肉接头乙酰胆碱受体兴奋中的作用。秋水仙素使小终板电位的幅度下降;使串刺激(10Hz,50Hz)诱发的平均终板电位幅度和平均量子含量减少;并使有神经支配的膈肌终板区乙酰胆碱电位幅度降低;但不影响膜电位、小终板电位的频率及终板电位和乙酰胆碱电位的时程。结果表明该药对神经肌肉接头乙酰胆碱受体的兴奋有抑制作用。而其同分异构体光化秋水仙素则无此作用。据此本文提出突触后膜下的微管可能参与神经肌肉接头乙酰胆碱受体的反应过程。     

南湖霉素对神经肌肉传递的影响和机理探讨

南湖霉素是我国学者筛选的一个新的多醚类抗生素，具有抑制枯草杆菌生长和抗鸡球虫病的作用。本工作利用电生理胞内记录方法，在小鼠膈神经膈肌标本上观察了它的作用。结果为（１）ＮＨＭ不可逆地阻遏神经肌肉传递，２０μｇ／ｍｌ时１．５－２ｈ完全阻遏。（２）２－２０μｇ／ｍｌ浓度的ＮＨＭ引起小终板电位发放频率显著地和阵发性地升高，持续４０－６０ｍｉｎ；其间，终板电位的平均量子含量也相应升高，并随传递阻遏的发生，终     

EVOLUTIONARY EFFECTS OF SELECTION ON AGE AT REPRODUCTION IN LARVAL AND ADULT: DROSOPHILA MELANOGASTER

Two sets of three replicate lines of Drosophila melanogaster were artificially selected by reproduction at either a ‘young’ or an ‘old’ age. The pure lines, the hybrids between the lines within a selection regimen and the base stock from which the lines were derived were compared for longevity, early and late fertility, development time, larval viability and adult thorax length. Comparison of hybrid with pure lines showed some evidence for inbreeding depression in the lines from both selection regimes. Comparison of hybrid lines with the base stock did not provide evidence for any trade-off in either males or females between early fertility on the one hand and late life fertility and longevity on the other. Nor was there any clear evidence of a trade-off between pre-adult and adult fitness components. There was evidence of inadvertent selection for rapid development in both selection regimens, especially in the females of the ‘young’ lines, and this complicated the interpretation of the responses and correlated responses to selection. An improvement in adult performance in the ‘old’ line males relative to the base stock appeared to be attributable to reversal of mutation accumulation. Comparison of the hybrid ‘young’ and ‘old’ lines with the base stock did not support the idea that the superior longevity and late life fertility of the ‘old’ lines relative to the ‘young’ lines could be accounted for by the effects of mutation accumulation in the ‘young’ lines. The results point to the need to compare selected lines with their base stock when deducing responses and correlated responses to selection and to avoid unintentional selection. In this type of experiment, larval density should be standardized during selection, and adults should not be under pressure for rapid maturation.     

离体大鼠不均匀牵张膈肌标本上的神经肌肉传递

在离体大鼠不均匀牵张膈肌标木（ＩＮＳＭＰ）上选择合适终板,可用同一微电极记录同一终板的小终板电住（ＭＥＰＰ）和终板电位（ＥＰＰ）。膜电位为－６２±２ｍＶ,ＭＥＰＰ频率和幅度在正常值范围,ＥＰＰ幅度高于２０ｍＶ,用直接法计算的量子含量对细胞外Ｃａ２＋浓度双对数作图呈直线,斜率为４．０６。２、５０和１００Ｈ２串刺激诱发量子释放的统计学性质为二项分布。表明ＩＮＳＭＰ上合适终板可作为电生理学上接近正常生理状态的神经肌接头模型,并提示生理状态下神经肌接头突触前诱发量子释放的机率较高（５０Ｈｚ时ｐ＝０．９）,遵循二项分布规律,递质动员较快（５０ＨＺ时为２０５０ｓ－１）,以保证正常的神经肌肉传递。     

WITHIN- AND BETWEEN-GENERATION EFFECTS OF TEMPERATURE ON THE MORPHOLOGY AND PHYSIOLOGY OF DROSOPHILA MELANOGASTER

We investigated the effects of developmental and parental temperatures on several physiological and morphological traits of adult Drosophila melanogaster. Flies for the parental generation were raised at either low or moderate temperature (18°C or 25°C) and then mated in the four possible sex-by-parental temperature crosses. Their offspring were raised at either 18°C or 25°C and then scored as adults for morphological (dry body mass, wing size, and abdominal melanization [females only]), physiological (knock-down temperature, and thermal dependence of walking speed), and life history (egg size) traits. The experiment was replicated, and the factorial design allows us to determine whether and how paternal, maternal, and developmental temperatures (as well as offspring sex) influence the various traits. Sex and developmental temperature had major effects on all traits. Females had larger bodies and wings, higher knock-down temperatures, and slower speeds (but similar shaped performance curves) than males. Development at 25°C (versus at 18°C) increased knock-down temperature, increased maximal speed and thermal performance breadth, decreased the optimal temperature for walking, decreased body mass and wing size, reduced abdominal melanization, and reduced egg size. Parental temperatures influenced a few traits, but the effects were generally small relative to those of sex or developmental temperature. Flies whose mother had been raised at 25°C (versus at 18°C) had slightly higher knock-down temperature and smaller body mass. Flies whose father had been raised at 25°C had relatively longer wings. The effects of paternal, maternal, and developmental temperatures sometimes differed in direction. The existence of significant within- and between-generation effects suggests that comparative studies need to standardize thermal environments for at least two generations, that attempts to estimate “field” heritabilities may be unreliable for some traits, and that predictions of short-term evolutionary responses to selection will be difficult.     

冲击波负压对大鼠肺致伤效应的初步观察

观察了不同的冲击波负压峰值对大鼠肺的影响。各种条件下的冲击波负压值可由负压发生装置来模拟调节,这种装置可满足化爆、核爆和爆炸性减压下负压参数的一般要求,参数稳定,重复性好。冲击波负压峰值范围为-13～-90kPa,下降时间为1～90ms,持续时间为14～2 000ms。6组Wistar系大鼠,分别暴露在-47.2～-84.0kPa的冲击波负压环境中,伤后立即解剖动物,重点观察肺伤情。实验结果显示,在上述冲击波负压环境中,肺可出现从无伤至极重度伤;出血、充血以及肺表面压痕酷似肺冲击伤的病理表现。随着冲击波负压峰值的变化,各组肺伤情亦随着变化,冲击波负压峰值(△P)和减压倍数(P_i/P_a)分别与肺出血面积和动物死亡率相关显著或非常显著。本实验提示,一定条件下的冲击波负压具有明显的致伤作用,且伤情变化范围与超压所致肺伤情变化范围相同,超压和冲击波负压在一定条件下可通过伤情指标等效。     

“C-751”激素在植物组织培养中的生物学效应初步观察

植物激素,按作用性质分为二大类:一为生长素类(如吲哚乙酸,奈乙酸,2,4—D等),一为激动素类(kinetin)(如6—苄基嘌呤,甲氨基嘌呤等)。从石油废渣中提取的长春产C—751激素是相当于哪一类激素呢?通过胡萝卜,菊芋,蓖麻胚乳的诱导愈伤组织实验和通过对小麦,向日葵,绿豆的发芽、生根实验,我们做了同6—苄基嘌呤,6—(?)基嘌呤,吲哚乙酸,萘乙酸,2,4—D药剂的作用对比,实验初步结果:C—751激素在诱导愈伤组织形成和生长以及种子发芽和幼苗生根中,其性质多接近生长素类。     

THE RESPONSES OF DROSOPHILA MELANOGASTER TO ARTIFICIAL SELECTION ON BODY WEIGHT AND ITS PHENOTYPIC PLASTICITY IN TWO LARVAL FOOD ENVIRONMENTS

To investigate the potential response to natural selection of reaction norms for age and size at maturity, fresh body weight at eclosion was mass selected under rich and poor larval food conditions in Drosophila melanogaster. The sensitivity of dry weight at eclosion to the difference between rich and poor larval food was selected using differences in sensitivities among families. For both experiments, the correlated response to selection of age at eclosion was examined. The flies were derived from wild populations and had been mass cultured in the lab for more than six months before the experiments started. These flies responded to selection on body weight upwards and downwards on both rich and poor larval food. Selection on increased or decreased sensitivity of body weight was also successful in at least one direction. Sensitivity was reduced by selection upwards in a poor environment and downwards in a rich environment.     

DISENTANGLING THE EFFECTS OF MATING PROPENSITY AND MATING CHOICE IN DROSOPHILA

Incipient sexual isolation between genotypes, lines, or populations of the same species is commonly measured in Drosophila by choice tests. Results of these tests are known to be influenced, in an undetermined manner, by the mating propensity of competitors and by discriminatory factors during courtship. We have approached the problem by measuring male and female propensities in separate, independent tests, and by examining whether these estimates could explain the results of the choice tests. First, male and female choice tests were used to measure sexual isolation between populations of Drosophila melanogaster and between populations of D. simulans. Significant deviations from random mating occurred in 31 out of 48 tests, in agreement with the propensity values of the tested genotypes. We conclude that mating propensity instead of discrimination is directly involved in the estimation of sexual isolation in our populations, and advise against the application of male and female choice tests to assess intraspecific isolation without a proper knowledge of the mating propensities of competing individuals. Second, multiple choice tests were used to assess isolation between D. melanogaster populations. In examining the dynamics of matings throughout the test, we show that if competing individuals differ in mating propensities and tests are long enough to allow most matings to happen, a spurious sexual isolation can appear. We recommend that multiple choice tests be terminated once 50 percent of matings had been observed.     

EXPERIMENTAL EVOLUTION OF ACCELERATED DEVELOPMENT IN DROSOPHILA. 1. DEVELOPMENTAL SPEED AND LARVAL SURVIVAL

Developmental time is a trait of great relevance to fitness in all organisms. In holometabolous species that occupy ephemeral habitat, like Drosophila melanogaster, the impact of developmental time upon fitness is further exaggerated. We explored the trade-offs surrounding developmental time by selecting 10 independent populations from two distantly related selection treatments (CB_1-5 and CO_1-5) for faster development. After 125 generations, the resulting accelerated populations (ACB_1-5 and ACO_1-5) displayed net selection responses for development time of -33.4 hours (or 15%) for ACB and -38.6 hours (or 17%) for ACO. Since most of the change in egg-to-adult developmental time was accounted for by changes in larval duration, the “accelerated” larvae were estimated to develop 25-30% faster than their control/ancestor populations. The responses of ACB and ACO lines were remarkably parallel, despite being founded from populations evolved independently for more than 300 generations. On average, these “A” populations developed from egg to adult in less than eight days and produced fertile eggs less than 24 hours after emerging. Accelerated populations showed no change in larval feeding rate, but a reduction in pupation height, the latter being a trait relating to larval energetic expenditure in wandering prior to pupation. This experiment demonstrates the existence of a negative evolutionary correlation between preadult developmental time and viability, as accelerated populations experienced a severe cost in preadult survivorship. In the final assay generation, viability of accelerated treatments had declined by more than 10%, on average. A diallel cross demonstrated that the loss of viability in the ACO lines was not due to inbreeding depression. These results suggest the existence of a rapid development syndrome, in which the fitness benefits of fast development are balanced by fitness costs resulting from reduced preadult survivorship, marginal larval storage of metabolites, and reduced adult size.     

EFFECTS ON FITNESS COMPONENTS OF P-ELEMENT INSERTS IN DROSOPHILA MELANOGASTER: ANALYSIS OF TRADE-OFFS

We analyzed the trade-offs between fitness components detected in four experiments in which traits were manipulated by inserting small (control) and large (treatment) P-elements into the Drosophila melanogaster genome. Treatment effects and the interactions of treatment with temperature, experiment, and line were caused by the greater length and different positions of the treatment insert. In inbred flies, the treatment decreased early and total fecundity. Whether it increased the lifespan of mated females depended upon adult density. Analysis of line-by-treatment-by-temperature interactions revealed hidden trade-offs that would have been missed by other methods. They included a significant trade-off between lifespan and early fecundity. At 25°C high early fecundity was associated with decreased reproductive rates and increased mortality rates 10–15 days later and persisting throughout life, but not at 29.5°C. Correlations with Gompertz coefficients suggested that flies that were heavier at eclosion also aged more slowly and that flies that aged more slowly had higher fecundity late in life at 25°C. The results support the view that lifespan trades off with fecundity and that late fecundity trades off with rate of aging in fruitflies. Genetic engineering is an independent method for the analysis of trade-offs that complements selection experiments.     

THE RATE AND EFFECTS DISTRIBUTION OF VIABILITY MUTATION IN DROSOPHILA: MINIMUM DISTANCE ESTIMATION

The empirical distribution of the mean viability of mutation accumulation lines, obtained from three published experiments, was analyzed using minimum-distance estimation. In two cases (Mukai et al. 1972; Ohnishi 1977), mutations were allowed to accumulate in copies of chromosome II protected from natural selection and recombination. In the other one (Fernández and López-Fanjul 1996), they accumulated in inbred lines derived from an isogenic stock. In contrast with currently accepted hypotheses, we consistently estimated low (about 0.01) genomic viability mutation rates, λ, and a small kurtosis of the distribution of mutational effects on viability (a) in the three datasets. Minimum-distance estimates of the per-generation mean viability change due to mutation (λE[a]) were also obtained. These were very similar for both chromosomal datasets, their absolute values being about five times smaller than estimates obtained from the observed change in mean viability during the mutation process. It must be noted that, in both experiments, viability was measured relative to the Cy chromosome of a Cy/Pm stock. Thus, an unnoticed viability increase in this Cy chromosome may have resulted in overestimation of the mean viability reduction in the lines. In parallel, minimum-distance estimation of λE(a) from inbred lines data (where the selective pressure during the accumulation process was larger) was even somewhat smaller, in absolute value, and very close to the estimate obtained by comparing the mean viability of the lines with that of the control isogenic line. The evolutionary importance of these results, as well as their relevance to the solution of the mutational load paradox, is discussed.     

营养和幼期密度对棉铃虫飞翔能力的影响

采自棉花、玉米、花生、绿豆和芝麻5种作物上的棉铃虫Helicoverpa armigera(Hubner),其飞翔能力依次为：棉花和玉米>花生>绿豆和芝麻。对室内利用人工饲料、棉铃、棉蕾和棉叶饲养的棉铃虫吊飞表明,取食人工饲料和棉铃的个体的飞翔能力数倍于取食棉叶者。成虫体重越大,飞翔能力越强。获得补充营养个体的飞翔距离是无补充营养者的2倍左右。本试验还研究了食物质量对棉铃虫卵巢发育的影响,结果显示成虫期的补充营养明显影响幼期营养较差个体的卵巢发育进程。对不同幼虫密度下发育个体的吊飞则表明成虫的飞翔能力和幼期密度关系不大。鉴于较差的营养条件和较高的幼期密度并不导致成虫飞翔能力的增加,本文认为,棉铃虫的远距离运动是成虫对羽化阶段不良环境的行为反应。     

PLASTICITY, CANALIZATION, AND DEVELOPMENTAL STABILITY OF THE DROSOPHILA WING: JOINT EFFECTS OF MUTATIONS AND DEVELOPMENTAL TEMPERATURE

The phenotypic effects of genetic and environmental manipulations have been rarely investigated simultaneously. In addition to phenotypic plasticity, their effect on the amount and directions of genetic and phenotypic variation is of particular evolutionary importance because these constitute the material for natural selection. Here, we used heterozygous insertional mutations of 16 genes involved in the formation of the Drosophila wing. The flies were raised at two developmental temperatures (18°C and 28°C). Landmark-based geometric morphometrics was used to analyze the variation of the wing size and shape at different hierarchical levels: among genotypes and temperatures; among individuals within group; and fluctuating asymmetry (FA). Our results show that (1) the phenotypic effects of the mutations depend on temperature; (2) reciprocally, most mutations affect wing plasticity; (3) both temperature and mutations modify the levels of FA and of among individuals variation within lines. Remarkably, the patterns of shape FA seem unaffected by temperature whereas those associated with individual variation are systematically altered. By modifying the direction of available phenotypic variation, temperature might thus directly affect the potential for further evolution. It suggests as well that the developmental processes responsible for developmental stability and environmental canalization might be partially distinct.     

大鼠初级感觉神经外周末梢间信息传递的观察

实验切断麻醉大鼠一侧Ｔ５－Ｌ１脊神经背部皮支的中枢端,用５０Ｈｚ,０．２ｍｓ,总时间为２ｓ的方波逆行刺激其中一皮支的外周端,记录其相邻皮支的电活动。结果发现刺激停止后２５ｓ内被记录皮支的放电迅速增加,继而逐渐恢复到刺激前的水平;４１４个序列实验结果的累积时程分析表明：被记录皮支的放电频率在刺激停止后的第２秒达最大值,并持续３ｓ,从第５秒开始逐渐下降,第２５秒及以后恢复到刺激前的水平;放电频率的增加