Parelaphostrongylus odocoilei: Life cycle in experimentally infected cervids including the mule deer, Odocoileus h. hemionus

The life cycle of a metastrongyloid nematode, Parelaphostrongylus odocoilei, was successfully completed in three members of the Cervidae: mule deer (Odocoileus h. hemionus), black-tailed deer (O. h. columbianus), and moose (Alces alces andersoni). The terrestrial gastropod, Triodopsis multilineata, was the experimental intermediate host. White-tailed deer (O. virginianus dacotensis) were refractory to infection. The prepatent period of P. odocoilei was significantly shorter in mule deer (X = 53 days) than in the black-tailed deer or moose. There was an inverse relationship between the size of the infective inoculum and the duration of the prepatent period of P. odocoilei in mule deer, but not in black-tailed deer. The duration and intensity of larval production of P. odocoilei were higher in mule deer than in the other hosts. Peak larval production in the feces (approximately 14,000 larvae/g) of mule deer was in excess of previous reports for elaphostrongyline nematodes, regardless of the size of the infective inoculum. Daily larval production, estimated at 3 to 4 × 10⁶ larvae/day, was six times higher than estimates for other elaphostrongylines. The duration of patency was not clearly established, but three mule deer and one black-tailed deer passed larvae for 12, 18, 24, and 18 months, respectively. On the basis of the reduced prepatent period and increased length and intensity of larval production, O. h. hemionus is considered the primary host of P. odocoilei.     

Definition of a juvenile hormone-sensitive period in Rhodnius prolixus

This paper is an attempt to establish the times of onset and termination of the juvenile hormone-sensitive period for metamorphosis in fifth-instar larvae of Rhodnius. Small regions of the abdominal integument were exposed to discrete pulses of the juvenile hormone analogue ZR-515 (methoprene) by applying small drops of a mixture in paraffin to the dorsum at various times after a bloodmeal and removing these drops after different time intervals. The diffusion coefficient of the analogue in the integument was estimated and used together with estimates of its metabolism to determine the lag times between application of the analogue and its rise to above threshold concentration in the epidermis, and between removal of the analogue source and its fall to below threshold concentration in the epidermis. These lag times were estimated to be 1.5 and 24h, respectively. Knowledge of the lag times makes it possible to establish the limits of the juvenile hormone-sensitive period or metamorphosis from the responses of larvae to variously-timed pulses of the analogue. The juvenile hormone-sensitive period has the following properties. For the population as a whole it lasts from about day 3 to about day 9 after a bloodmeal. Any individual in that population, however, only requires the presence of juvenile hormone during a 2 to 4-day period. The exact duration of an individual's sensitive period within these limits is a stochastic event. Surprisingly, for any individual, a pulse of juvenile hormone is equally effective when experienced early as when experienced late during its juvenile hormone-sensitive period.     

青桃利用单、复花芽结果对盛果期生长结实的影响

青桃盛果期,特别中庸偏旺的植株,单、复花芽果枝数大体均等,复花芽果枝以其复芽个体较大,枝条较粗而往往表现为优势。然而笔者于1974—1979年观察了青桃树以单、复花芽结果对盛果初期的影响,结果表明:利用单花芽结果,控制了强旺枝和结果部位,使果枝分布均匀,树势稳定,尤其果枝数、花芽数、单株产量等的变动趋势与年度增加无关,r为:-0.2899、0.0620(单、复花芽果枝数分别占总果枝数的35.1％和16.7％),-0.3830、-0.1804(单、复花芽朵数分别占总花芽朵数的44.5％和13.4％),0.4093(单株年产量为179.4公斤,从而延长了盛果期;利用复花芽结果却相反,促进树势极性生长,旺枝增强,果枝外移,内膛空虚,尤其果枝数、花芽数、单株产量等的变动趋势随年度增加而呈显著与极显著负相关,r为:-0.8938~(**)、-0.9818~(**)(单、复花芽果枝数分别占总果枝数的27.1％和21.1％),-0.953~(**)、-0.8908~(**)(单、复花芽朵数占总花芽朵数的35.3％和6.8％).-0.8853~(**)(单株产量较单花芽结果减产19.4％),从而明显缩短盛果期。     

α和β受体阻断剂对早期缺血心肌多发早搏阈的影响

本实验在35只兔心脏上观察了α和β受体阻断剂对心肌缺血早期MET变化的影响,并初步分析了α受体阻断剂抗心律失常效应的作用机理。实验结果表明,β与α受体阻断剂对MET 的影响明显不同。β受体阻断剂心得安可使正常心脏与缺血心脏的MET同等程度的升高,而对阻断冠脉后 MET的降低无改善作用。与此相反,α受体阻断剂哌唑嗪对正常心脏的MET 无明显影响,但可使阻断冠脉血流后 MET降低的百分率明显减轻,此效应与血压变化和扩血管作用无直接关系。上述结果提示,β受体阻断剂可通过提高正常和缺血心脏MET 的绝对值发挥抗心律失常效应,而α受体阻断剂则有特异性的提高缺血心肌MET 的作用。     

Correlation between larval weights,endocrine gland activities and competence period during differentiation of workers and soldiers in Macrotermes michaelseni (Isoptera:Termitidae)

Correlations were established between corpora allata and prothoracic gland activities, changes in fresh weights and competence period for soldier formation in a higher termite species, Macrotermes michaelseni. There was a time-course differential increase in fresh weights observed in pairs of female third (final)-instar larvae of the same age previously adopted by a pair of female reproductives from incipient colonies. A bimodal distribution of these larvae according to weights was evident from the first day of the instar. Heavier larvae were associated with higher corpora allata and prothoracic gland volumes (activities), and differentiation into presoldiers, while lighter larvae had considerably less-active corpora allata and prothoracic glands and developed into workers. The peak in the activities of these glands in both cases marked the end of the competence period.The chain of events that may precede caste differentiation is discussed briefly and the significance of the findings outlined.     

Eclipse period of baculovirus infection in larvae of the armyworm, Pseudaletia unipuncta

Two strains of a nuclear polyhedrosis virus (baculovirus) infect larvae of the armyworm, Pseudaletia unipuncta. The hypertrophy strain (HNPV) produces a gradient of infected epithelial cells along the tracheae indicating the movement of infectious material to adjacent cells. Cytopathology of the eclipse period up to the appearance of the virogenic stroma has been separated into three phases during which the chromatin disappears and is replaced by dense interconnected strands of fibrils and dense punctate bodies. Cellular hypertrophy occurs in phase 1 and the virogenic stroma appears in phase 3. The typical strain (TNPV) does not produce structures comparable to those of HNPV infection.     

在体兔心急性心肌缺血时的复极后不应性

本实验观察了开胸麻醉家兔急性心肌缺血时的不应期改变。用吸引电极记录的单相动作电位(MAP)确定机能不应期(FRP)及 FRP 超过 MAP 复极90%时程(MAPD_(90))的复极后不应性(PRR)。阻断冠脉左室支以后,缺血区不应期表现出两种完全不同的变化:缺血中心区不应期延长并超过 MAPD_(90),出现 PRR;缺血周边区不应期则通常较对照缩短。利用自体颈总动脉的动脉血进行灌流的兔心实验表明,当100%阻断灌流血液时,缺血中心区出现PRR,但是当50%阻断时,同一部位心肌的不应期却表现为缩短。上述结果提示:PRR 是在严重心肌缺血情况下出现的。同一时刻测定缺血中心区、周边区和非缺血区的功能不应期,结果表明,冠脉阻断后不应期离散程度的明显增大是与当时 PRR 的出现密切相关的。因此,PRR 的存在可以认为是造成急性心肌缺血时不应期离散的重要原因,而后者一般认为是异致折返性心律失常的重要因素。     

Extent of excision repair before DNA synthesis determines the mutagenic but not the lethal effect of UV radiation

Excision repair-proficient diploid fibroblasts from normal persons (NF) and repair-deficient cells from a xeroderma pigmentosum patient (XP12BE, group A) were grown to confluence and allowed to enter the G₀ state. Autoradiography studies of cells released from G₀ after 72 h and replated at lower densities (3?9 × 10³ cells/cm²) in fresh medium containing 15% fetal bovine serum showed that semiconservative DNA synthesis (S phase) began ～24 h after the replating. To determine whether the time available for DNA excision repair between ultraviolet irradiation (254 nm) and the onset of DNA synthesis was critical in determining the cytotoxic and/or mutagenic effect of UV in human fibroblasts, we released cultures of NF or XP12BE cells from G₀, allowed them to reattach at lower densities, irradiated them in early G₁ (～18 h prior to the onset of S) or just prior to S phase, and assayed the frequency of mutations to 6-thioguanine resistance and the survival of colony-forming ability. The XP12BE cells, which are virtually incapable of excising UV-induced DNA lesions, showed approximately the same frequency of mutations and survival regardless of the time of UV irradiation. In NF cells, the slope of the dose response for mutations induced in cells irradiated just prior to S was about 7-fold steeper than that of cells irradiated 18 h earlier. However, the two sets of NF cells showed no significant difference in survival. Neither were there significant differences in the survival of NF cells released from G₀, plated at cloning densities and irradiated as soon as they had attached and flattened out (～20 h prior to S) or 4, 8, 12, 16, 20 or 24 h later. We conclude that the frequency of mutations induced by UV is dependent upon the number of unexcised lesions remaining at the time of semi-conservative DNA replication. However, the amount of time available for excision of potentially cytotoxic lesions is not determined primarily by the period between irradiation and the onset of S phase.     

扎龙湿地野生与散养白枕鹤繁殖前期觅食生境选择对比分析

为了探讨野生与散养白枕鹤（Grus vipio）觅食生境选择的异同,2004年春季,通过定点观察法、样方法、因子测定法对扎龙湿地二者繁殖前期的觅食生境选择作了对比研究。结果表明,繁殖前期,野生白枕鹤繁殖对觅食生境选择具有严格要求,倾向于选择人为活动较少（1．67km）、靠近明水面（21．0m）、剩余苇丛隐蔽度较高的苔草沼泽生境中觅食;散养白枕鹤对生境类型的要求不高,倾向于选择距人为活动区域较近（0．32km）的生境觅食。     

哺乳期棕色田鼠对配偶的识别记忆

观察了分娩后哺乳雌性棕色田鼠（Microtus mandarinus）与配偶分离7d、14d、21d后对配偶与陌生雄鼠的行为反应。结果发现,在频次和持续时间上,与配偶分离7d、14d、21d的雌鼠对配偶的攻击行为显著低于陌生雄鼠（P〈0．05）;对配偶的嗅闻及友善行为显著高于陌生雄鼠（P〈0．05）。处于哺乳前、中、后期不同阶段的雌鼠对陌生雄鼠攻击水平没有显著性差异（P〉0．05）。这些结果说明,在整个哺乳期,雌鼠能够识别配偶,对配偶的记忆不因分离时间的增加而减弱,而且对陌生鼠的攻击水平不会因哺乳阶段的变化而变化,维持高水平的攻击可能与其较强的母性行为有关。