The influence of caging conditions and hormone treatments on fighting in male and female hamsters

After gonadectomy, more individually caged female hamsters fought prior to the initiation of hormone treatments than did group-caged females. Daily injections of testosterone propionate (TP), estradiol benzoate (EB), or progesterone (Prog) had no influence on the number of individually caged females that fought. However, TP and EB were effective in increasing the number of group-caged females that fought. In contrast to females, both individually and group-caged males fought infrequently after castration. Daily injections of TP, EB, or Prog were effective in increasing the number of individually caged males that fought, while only TP and EB were effective in group caged males. Prog failed to increase the number of group-caged hamsters of either sex that fought.     

The influence of retinal on complement-dependent immune damage to liposomes

Retinal was incorporated into liposomes containing dipalmitoyllecithin, cholesterol, dicetyl phosphate and galactocerebroside; the latter substance served as antigen. They were compared to control liposomes, lacking retinal, with regard to glucose release due to complement-dependent immune damage in the presence of anticerebroside serum. The liposomes were indistinguishable from each other in the amount of total glucose trapped, light scattering characteristics and phosphate content. The rate and extent of glucose release in 30 min was inhibited by the incorporation of retinal. In addition, inhibition was directyl related to retinal concentration and was also observed in the presence of a wide range of concentrations of antigen and complement. Damage to liposomes in the presence of either guinea pig or human complement was inhibited by retinal; this was in contrast to the erythrocyte system in which the hemolytic activity of guinea pig complement was inhibited while that of human complement was enhanced by retinal. Addition of retinal to performed liposomes did not influence complement-dependent damage. Inhibition occurred only when retinal was present during the initial formation of the model membranes. Inhibition persisted even after washing the liposomes free of any unincorporated retinal. The data indicate that liposomes may be an excellent model for studying the influences of retinal on complement mechanism in membranes.     

Postpartum aggression in mice: The influence of suckling stimulation

The influence of suckling stimulation upon postpartum aggression was studied by removing the nipples (thelectomy) of female mice at various times during pregnancy and lactation. Prepartum thelectomy, regardless of whether it was performed prior to mating or shortly before parturition, in combination with the fostering of young, prevented the exhibition of aggression. The aggressive behavior of females thelectomized following either 2 or 5 days of suckling experience was similar to that of normal lactating females. However, only 25% of animals thelectomized following 24 hr of suckling experience exhibited aggressive behavior. The results demonstrate that suckling stimulation is important for the initiation of postpartum aggression but is not essential in animals that have had at least 48 hr of suckling experience.     

The exchange hypothesis for the formation of chromatid aberrations: an experimental test using bleomycin

The association between bleomycin-induced chromatid aberrations and BUdR-label exchange between sister chromatids was investigated in order to evaluate Revell's exchange hypothesis for the formation of chromatid aberrations. The results of this study indicate that a larger than expected proportion of chromatid breaks can be accounted for by the exchange hypothesis though not all breaks are the result of incomplete exchange.     

Q-mode regression analysis applied to predict the antidotal action of bispyridinium oximes in intoxications with organophosphorus poisons

There are some serious pitfalls if the usual multiple and multivariate regression analysis are applied to correlate the biological activity of compounds against parameters describing the chemical molecule structure if the observations consist of an inhomogeneous data set. By contrast to the more known methods of cluster analysis, it must be required that a partition into homogeneous groups is possible and, in addition, that the members inside any group are normally distributed. The principle of the Q-mode regression analysis dealing with that problem is exemplified on the antidotal action of bispyridinium oximes in intoxication with organophosphorus poisons (soman, tabun, sarin, VX).     

A sensitivity analysis of process design parameters,commodity prices and robustness on the economics of odour abatement technologies

The sensitivity of the economics of the five most commonly applied odour abatement technologies (biofiltration, biotrickling filtration, activated carbon adsorption, chemical scrubbing and a hybrid technology consisting of a biotrickling filter coupled with carbon adsorption) towards design parameters and commodity prices was evaluated. Besides, the influence of the geographical location on the Net Present Value calculated for a 20 years lifespan (NPV20) of each technology and its robustness towards typical process fluctuations and operational upsets were also assessed. This comparative analysis showed that biological techniques present lower operating costs (up to 6 times) and lower sensitivity than their physical/chemical counterparts, with the packing material being the key parameter affecting their operating costs (40–50% of the total operating costs). The use of recycled or partially treated water (e.g. secondary effluent in wastewater treatment plants) offers an opportunity to significantly reduce costs in biological techniques. Physical/chemical technologies present a high sensitivity towards H₂S concentration, which is an important drawback due to the fluctuating nature of malodorous emissions. The geographical analysis evidenced high NPV20 variations around the world for all the technologies evaluated, but despite the differences in wage and price levels, biofiltration and biotrickling filtration are always the most cost-efficient alternatives (NPV20). When, in an economical evaluation, the robustness is as relevant as the overall costs (NPV20), the hybrid technology would move up next to BTF as the most preferred technologies.     

The inhibitory actions of progesterone: effects on male and female sexual behavior of the hamster

A series of three experiments compared the inhibitory effects of progesterone on estrogen- or androgen-induced sexual behavior in male and female hamsters. In the first experiment chronic progesterone treatment was found to have no effect on male copulatory behavior maintained after castration with testosterone propionate or estradiol benzoate. However, testosterone propionate was more effective at maintaining male behavior than estradiol benzoate. In the second experiment progesterone was found to have a slight inhibitory effect on the rate of the restoration of the intromission response after androgen treatment in males which had been castrated for 8 weeks. In the final experiment, chronic progesterone treatment markedly inhibited sexual receptivity in male and female hamsters which had been given 4 weeks of androgen or estrogen treatment and a single pretest injection of progesterone. Thus, progesterone was shown to be a potent inhibitor of androgen- or estrogen-induced estrus in both male and female hamsters. Due to the large difference in effectiveness on these two behavioral systems, we suggest that progesterone affects steroid-induced male copulatory behavior and female receptivity by different mechanisms of action.     

The influence of food presentation on the behavior of small cats in confined environments

Captive small felids frequently pace repetitively and/or spend large amounts of time inactive. Presenting a fishing cat with live-fish resulted in more activity (60% less sleeping), increased behavioral diversity, including previously unobserved hunting behaviors, and greater enclosure utilization. Effects persisted for at least 48 h after presentation of live fish, and up to 8 days. In a second study, four leopard cats were fed: (1) once per day, (2) four times per day and, (3) four times per day with food hidden in small piles of brush. Multiple feedings of hidden food increased daily exploratory behavior from 5.5% to over 14%, and increased the diversity of behaviors observed. It also reduced the total duration, and bout length of stereotyped pacing. These studies suggest that providing food to small cats in a way that minimizes predictability of food availability, while maximizing the functional consequences of foraging behavior, can be an effective enrichment technique. These results are discussed in relation to two models of behavioral motivation, one that focuses on the issue of behavioral needs, and the other that emphasizes the importance of information acquisition. © 1993 Wiley-Liss, Inc.     

Inhibitory effect on limb morphogenesis by cells of the polarizing zone coaggregated with pre- or postaxial wing bud mesoderm.

The influence of cells of the polarizing zone mesoderm on the morphogenesis of recombinant chick limbs was studied. The recombinant buds were composed of leg bud ectoderm and different regions of the wing bud mesoderm, which had been dissociated and reaggregated. In any case where the polarizing zone mesoderm was coaggregated with the wing mesoderm the morphogenetic capabilities of the recombinant were reduced. This was the case with postaxial mesoderm, preaxial mesoderm plus polarizing tissue, and postaxial mesoderm from which a piece of the nonpolarizing mesoderm (comparable in size to the polarizing zone) had been removed. All of these gave outgrowths with digits in only a very low percentage of cases. In contrast, those recombinants without polarizing mesoderm developed outgrowths with digits in a high percentage of cases, indicating good morphogenesis. Finally, if the polarizing zone were removed prior to dissociation, the recombinant limb, composed of the total remaining wing bud mesoderm plus leg bud ectoderm, exhibited a higher percentage of complete morphogenesis than if the polarizing zone had been part of the recombinant.It is clear that cells of the polarizing zone, when dissociated, and coaggregated with wing mesoderm, are inhibitory to the morphogenetic performance of that mesoderm in the recombinant limb situation.     

黄土高原沟壑区退耕还林典型优化模式机理分析

以退耕还林工程重点地区的黄土高原沟壑区为研究对象,引入系统动力学理论和技术。采取试验站点观测与广泛调研集成等5个结合的技术路线,横跨自然、经济、社会科学三大领域,共获取原始数据10000多个,对黄河中游黄土高原沟壑区山西省乡宁县试验点退耕还林生态一经济一社会效益最优结合、可持续发展的油松X侧柏X花椒X刺槐优化模式的作用机理,从生态、经济、社会效益及其相互作用等方面进行了分析研究．结果表明,该模式的生态、经济和社会效益各主要指标均处于最佳或较好状态;三大效益综合比较,该模式是最佳模式;经F检验,该模式与其它模式均呈极显著性差异．     

基于物质流分析方法的唐山市经济与环境关系的协整检验和分解

利用物质流分析方法(MFA)建立物质流账户,分析唐山市在经济 环境系统运行中物质投入量与产出量的阶段特征及物质投入和产出强度对经济发展的影响程度;使用计量经济学模型,分别对国内生产总值(GDP)、直接物质投入(DMI)和直接废弃物排放(DPO)进行单位根检验、Johansen协整检验、向量误差修正分析、脉冲响应和方差分解分析,探索了各指标之间的双向作用机制和长期关系.结果表明: 1992—2011年,唐山市DMI和DPO 均呈增长趋势,DMI的增幅高于DPO.DMI投入强度呈增长趋势,DPO产出强度呈波动下降趋势.GDP与DMI、DPO之间存在着长期稳定协整关系,指标间的作用关系经历了由波动到逐步平稳的过程.DMI与DPO在短期内会对经济发展起到较强的正向冲击作用,但是经济-环境系统会逐步消化这些影响,并对系统内外指标进行短期的动态调整,最终使系统表现出一种长期的均衡关系;经济发展受到经济规模效应的影响逐步增加.将各指标对GDP的贡献度予以分解,其中,DMI的贡献度上升,GDP的贡献度下降,DPO的贡献度变化不大.总体上,唐山市的经济发展遵循了资源型城市的传统生产轨迹,较大程度上依赖于物质投入,高能源消耗又加剧了环境污染.     

Inability of progestogen pretreatment to prevent premature luteolysis of induced corpora lutea in the anestrous bitch

Fourteen mature anestrous bitches were used to determine the effectiveness of pretreatment with an orally active progestogen to prevent premature luteolysis of induced corpora lutea (CL) in the anestrous bitch. In Group 1, seven bitches were treated orally with megestrol acetate (Ovaban((R))) at the rate of 2.2 mg/kg body weight for eight days. Three days later, the bitches were treated daily with pregnant mare's serum gonadotropin (PMSG) (44 IU/kg body weight) administered intramuscularly for nine consecutive days, and each bitch was given 500 IU human chorionic gonadotropin (HCG) on day 10, or on the first day of induced estrus if the bitches exhibited estrus while being treated with PMSG. A control group (Group 2) of seven bitches was not treated with Ovaban((R)) but was similarly given PMSG and HCG. Estrus was detected twice daily using a vasectomized male dog and verified by vaginal cytology. Blood samples were obtained on the first day of induced estrus (day 0) and every other day until day 90 post-estrus. Plasma progesterone (P(4)) concentrations were determined by a non-extraction solid phase radioimmunoassay (RIA), and data were analyzed by Student's t-test. There was no significant difference between the progesterone profiles of both groups of bitches. In addition, P(4) values were less than 1 ng/ml by day 50 post-estrus. Results of this study suggested that pretreatment with an orally active progestogen was not effective in preventing premature luteolysis of induced CL in the anestrous bitch.     

The influence of distance to burrow on flight initiation distance in the woodchuck, Marmota monax

We used woodchucks (Marmota monax) to test predictions of acost-benefit model of antipredator behavior that flight initiationdistance would increase with distance to refuge and with predatorapproach velocity. We also examined the effects of distanceto refuge and predator approach velocity on escape velocityand on both temporal and spatial margin of safety (expectedtime and distance between predator and burrow at the time ofthe woodchuck's arrival). The observer, assumed to be perceivedas a potential predator, approached juvenile woodchucks fromthe direction opposite to the burrow at a slow (1.24 m/s) orfast (1.79 m/s) walking pace. When the woodchuck started toflee, the observer recorded the woodchuck's distance from theobserver and from its burrow, the time spent running, and whetherthe woodchuck stopped before reaching its burrow. Flight initiationdistance increased consistendy with distance to the burrow overthe entire observed range (0–25 m) but was not significantlyaffected by observer approach velocity. Escape velocity wasnot significantly influenced by the observer approach velocityand was approximately constant over the range of 2–25m, but was slower for woodchucks less than 2 m from their burrows.Both temporal and spatial margins of safety increased with distancefrom the burrow. The temporal margin of safety increased withdistance from the burrow more rapidly for slow than for fastobserver approach velocity. Woodchucks fleeing from greaterthan 2 m usually stopped near the burrow before entering, butthose from closer distances usually entered directly. Theseresults support the assumption that antipredator behavior issensitive to the costs and benefits of alternative escape decisions.     

高考遗传学试题的分析和对策

遗传学相关内容是高中生物学的重点和难点知识;遗传学又在历年高考中占有相当大的比重,因此,分析了近几年高考遗传学相关试题的类型及解题方法,并对中学教学和学生的学习方法提出了建议。     

薇甘菊对内伶仃岛植被危害的相关分析

对广东内伶仃岛群落受薇甘菊危害的植物种类分析表明,58种乔木、小乔木和灌木种不同程度地受薇甘菊的影响,约占样地中木本种类的67%;其中受薇甘菊影响最大的主要是小乔木和阳生性灌木.薇甘菊危害与群落类型的关系表现为,由5、6个优势种组成的结构复杂的具有较大郁蔽度的群落受薇甘菊的危害轻微,而仅由2个优势种组成结构简单且郁蔽度很小的群落受薇甘菊的危害较严重.薇甘菊危害与群落结构的相关分析表明,群落垂直高度越大、片层越丰富,群落中薇甘菊的盖度越小;群落物种越丰富,群落密度越大,个体受害比例越小;群落中其他藤本盖度越大,个体受薇甘菊危害的程度越高.     

The influence of aging on androgen dynamics in the male rat

Androgen assimilation was investigated in a variety of accessory sex organs (seminal vesicles and anterior, dorsal, lateral, and ventral prostates) and in several nonaccessory sex organs in male Wistar rats. After administration of a pulse dose of [³H]testosterone in vivo to intact young (3–4 months old) rats, [³H]testosterone was the primary radioactive steroid recovered from most organs examined, except for the secondary sex glands where the reduced metabolites, [³H]5α-dihydrotestosterone (DHT) and [³H]5α-androstanediol(s), predominated. At longer postinjection times, [³H]DHT was preferentially retained in the accessory sex glands, presumably reflecting intracellular metabolism of [³H]testosterone to this compound and subsequent specific binding of [³H]DHT to receptor proteins. At the longest postinjection interval investigated, the ventral prostate retained greater concentrations of [³H]DHT than the lateral prostate which in turn had a higher [³H]DHT concentration than the seminal vesicles or anterior or dorsal prostates. The latter three glands retained approximately equal concentrations of [³H]DHT. Scatchard plot analyses of cytosol binding in 24-h castrates indicated that with one exception, the level of high affinity DHT binding sites was generally correlated with the retention of [³H]DHT in vivo in intact rats. Specifically, while the affinity for DHT binding in all accessory sex organs was the same, the number of high affinity binding sites per mg wet tissue weight was on the order of ventral prostate > anterior prostate ≥ seminal vesicles ≥ dorsal prostate > lateral prostate. Studies of the influence of aging to 22–26 months revealed no apparent differences in the affinity of the DHT receptor for its ligand in any of the accessory sex glands from 24-h castrates when the receptors were present in levels sufficiently high to quantify. The concentration of available DHT receptors with advancing age remained constant in the anterior and dorsal prostates, increased in the seminal vesicles, and declined in the ventral and lateral prostates. The decreases observed in the ventral prostate were only partial, but the receptors of the lateral prostate declined to nondetectable levels.