浅谈海洋无脊椎动物的生物钟

一般动物(含人类)的生理活动和行为都有不同程度的周期性(periodicity)或节奏性(rhythemicity),而这些现象的表现并不一致:有的较明显,很易发觉(如昼夜垂直移动、体色变化等),而有的较隐蔽,不易发现(如视网膜色素移动等)。生物钟(biological clock)是受时间机制(timing mechanism)调节或控制的一种节奏性或周期性的生理活动(较为隐蔽)     

Myocardial infarct death and temperature in Auckland,New Zealand

Daily myocardial infarct deaths for Auckland (36° 51S, 20 m above sea-level) show an increase in mortality rate with decreasing temperatures over the entire thermal range. Parallel studies in Brisbane and Montreal predicted a minimum death temperature between 21 and 24° C, but no such point was apparent. Lack of temperatures above 21° C, together with the small overall thermal range, is thought responsible.     

龙眼果实防腐保鲜技术研究

近几年来,我们探讨了不同的贮藏温度、化学防腐剂、气体组分、包装容器及包装方法对不同品种龙眼果实的防腐保鲜效果。结果表明:龙眼品种间的耐贮性有很大差异,按耐贮性排列:泉州本>乌龙岭>普明庵>福眼>赤壳>水涨;最佳的保鲜贮藏温度为3～4℃;仲丁胺、仲丁胺+赤霉素、多菌灵、甲基托布津、苯甲酸、特克多、FISB-1和FISB-2等不同化学防腐剂对泉州本的防腐效果,以FISB-1和FISB-2防腐效果最佳,贮藏40天,好果率分别为95.0％和95.2％,其他防腐剂处理的好果率为80.7％～86.5％;气调贮藏,CO_2为4％～6％,O_2为6％～8％的气体组分可延长贮藏寿命,降低龙眼果实自身损耗;包装容器以塑料周转箱套薄膜袋气调贮藏效果最佳。     

Changes in gill morphology of Oreochromis mossambicus subjected to heat stress

Synopsis The cichlid fish, Oreochromis mossambicus, was acclimated to 25°C for a 14 day period and then subjected to elevated temperatures of 30, 35, 40 and 45° C. Gill epithelia was progressively damaged from 30–40° C; gills from fish tested at 45°C showed less damage than those tested at 40°C. This is presumably due to the shorter exposure (survival) time at 45°C. Shrinkage of the secondary lamellae and the collapse of pillar cells supports the hypothesis that hypoxia at elevated temperatures is partially a function of changes in gill morphology.     

Effect of temperature on early development of white and lake sturgeon,Acipenser transmontanus and A. fulvescens

Synopsis The effect of constant incubation temperatures (between 10°C and 26°C) on the developmental rates was found to fit a similar exponential relationship in both the lake and white sturgeon embryos and larvae. Although the lake sturgeon had an overall slower rate of development than the white sturgeon, no statistically significant difference was detected in the slopes of the exponential equations describing the effect of temperature on developmental rate. The effect of these incubation temperatures on embryonic survival also did not differ between these two species. Both species exhibited optimal survival between 14–17° C and incipient mortalities occurred at 20°C. Temperatures above 20°C were lethal for white sturgeon embryos. No effect of low incubation temperature on survival was evident from this study. A comparison of these North American species with Eurasian acipenserids suggests that all the sturgeon that have been examined exhibit a similar influence of incubation temperature on developmental rate.     

Circadian Rhythm and Seasonal Variations in Basal cAMP Content of Rat Heart Ventricles

The cAMP content in rat heart ventricles was studied at 3-hr intervals during 24hr at different times of the year. A significant circadian rhythm in cAMP content was found. Time of the year reproducibly influenced the 24-hr mean, the amplitude as well as the peak value in cAMP in relation to circadian time.     

Circadian Activity Rhythm of the House Fly Continues after Optic Tract Severance and Lobectomy

Under constant conditions, locomotor activity in about 50% of 63 adult Musca domestica continued to be rhythmic after bilateral severance of optic tracts or bilateral lobectomy. Apparently, the optic lobes of Musca do not contain the oscillator for rhythmic control of locomotor activity as has been proposed for other insects. In 20% of the individuals, several circadian components of activity rhythms were found after operation indicating a role of the optic lobes in the coupling of oscillators. The remaining 30% of the flies with severed optic tracts appeared to be arrhythmic. Most of these flies had vacuolized tissue in the central brain. However, disruption of rhythmicity did not correlate with a common pattern of degeneration. Therefore no conclusions can be drawn as to the localization of the circadian control of locomotor activity in the brain. Flies showing an arrhythmic activity pattern could still be synchronized by LD cycles. Activity did not occur solely during the light period as is the case in controls; but was phase delayed by about 6 hr towards the dark period. Since all flies with severed optic tracts could be synchronized by LD cycles, Musca domestica must possess extraocular photoreceptors.     

Effect of Beta-Adrenergic Stimulation on the Circulatory Lymphocyte Count: Studies in Normals and in Patients with Chronic Airflow Obstruction

In eight non-allergic patients with chronic airflow obstruction (CAO) and eight age and sex matched, healthy control subjects the circadian variation in circulatory lymphocyte count was studied in relation to serum Cortisol and urinary epinephrine levels. In addition, we investigated the effect of the beta-adrenergic agent terbutaline on the lymphocyte count in two ways: as a long-term effect after 8 days of oral slow-release terbutaline with constant diurnal and nocturnal serum levels in patients, and as a short-term effect by a constant rate infusion of 0.2μg/min over 4hr in normals. Both patients and controls showed similar circadian patterns of urinary epinephrine excretion and lymphocyte counts. Patients with CAO, however, had significantly lower epinephrine levels and significantly higher lymphocyte counts at all hours of observation (every 4 hr from 0800 to 0800 hr the next day), as compared with normal controls. After 8 days of slow-release terbutaline the lymphocyte count in the patient group decreased to levels not significantly different from that of normals. The circadian rhythm of the lymphocytes, however, persisted under terbutaline therapy. No correlation existed between the lymphocyte count modulating factor, serum Cortisol and the lymphocyte count over 24 hr. On placebo infusion in the control persons an increase of lymphocytes over 4hr occurred, as a consequence of circadian rhythmicity. On terbutaline infusion a significant increase of lymphocytes after 1hr was follwed by a decrease to levels significantly below those on the placebo day. The same pattern was found in the leucocyte count. From this study it is concluded that beta-adrenergic stimulation corrects the relative lymphocytosis to counts comparable with normals. Other coinciding factors must regulate, however, the circadian rhythmicity.     

Daily Changes in the Gonadotropin Levels and Response of Carp Oocytes to Hypophysial Homogenate

Daily changes in carp gonadotropin levels in adult female carp and daily changes in carp oocyte sensitivity to carp hypophysial homogenate, in vitro and in vivo, were investigated.

A total of three series of experiments were carried out. Gonadotropin levels were radioimmtmologically determined.

The results of series 1 and 2 experiments were subjected to statistical analysis with the use of cosinors circle and elipse of errors. It has been found that in the mature female carp in the pre-spawning period with the light periods being long (L:D = 16:8) the apogee for gonadotropin occurs 10 hr after the onset of the light period.

The sensitivity of the oocytes, in terms of the percentage of mature oocytes (after GVBD) following a 24-hr incubation of ovarian fragments with the hypophysial homogenate, reached the highest value at 1300, i.e. 9 hr after the onset of the light period.

It was also found that the injections of carp hypophysial homogenate made at 0900 were much more efficient in inducing ovulation than those at 2100.     

Migration and division of cleavage nuclei in the gall midge,Wachtliella persicariae

Summary The control of nuclear division and migration was studied in time-lapse films of the multinucleate egg cell of a gall midge by experimental alterations of the mitotic pattern. During each cleavage cycle, a wave of randomly oriented saltations of yolk particles (WROS) is seen to travel through the ooplasm. This wave proved to be an indispensable prerequisite for the accompanying anaphase wave and for the activation of the nuclear migration cytasters: WROS cycles can occur autonomously without cleavage nuclei being present, but there is no anaphase without a WROS passing the dividing nucleus. WROSs and mitotic waves can be inverted, and the WROS cycles and the cleavage cycles can be desynchronized by temperature grandients or by locally impaired gas exchange. If a nucleus is not ready for anaphase when met by a WROS, it will only divide in the course of the next WROS. WROSs thus indicate autonomous anaphase-triggering waves governing the cleavage divisions. Rhythmic ooplasmic movements continue even if the WROSs as well as the nuclear divisions are inhibited by colchinine. The characteristics of the WROSs support the hypothesis that each of them is the visible effect of a wave of calcium release (similar to that established in vertebrate eggs) which acts locally on the microtubular system and may continue even if the WROSs are suppressed. The correlations between a possible calcium release, WROS activity, microtubule disassembly and nuclear cycle are discussed.