乙草胺对蟾蜍心电活动的影响

采用生物机能实验系统,对乙草胺胁迫条件下蟾蜍Bufo gargarizans的心率和心电活动的相关指标进行了测定和分析.试验结果表明,随着乙草胺处理浓度的增大,蟾蜍的心率减慢,心电图中P波、R波和T波的电压峰值降低,而P-R间期、QRS期和Q-T间期的时值延长.乙草胺胁迫条件下,蟾蜍心率与心电图的各项指标有显著相关性.由此可见,乙草胺的喷施对蟾蜍心电活动周期和机械活动周期均造成了一定影响.     

化肥磷酸二铵对花背蟾蜍蝌蚪发育的影响

目的为了探究化肥磷酸二铵对两栖类幼体发育的影响。方法以花背蟾蜍(Bufo raddei)蝌蚪为研究对象,用化肥磷酸二铵(DAP)进行染毒培育,并依据Gosner(1960)分期标准,将蝌蚪分为G0实验组和G20实验组,分别暴露于浓度为0.045g/L、0.135g/L、0.225g/L的DAP水溶液中,直至蝌蚪完成变态发育,并对孵化率、死亡率、畸形率以及发育时程等参数进行统计分析。结果随着化肥DAP浓度的升高,孵化率逐渐下降,但对照组与各侵染组之间均无显著性差异;侵染组蝌蚪死亡率均高于对照组,均呈极显著性差异(P0.01),且G20侵染组明显高于G0侵染组;蝌蚪畸形可分为四大类,侵染组蝌蚪畸形率均高于对照组,且均呈极显著性差异(P0.01),畸形率随着DAP浓度的升高而增加;完成变态发育所用时程,侵染组明显长于对照组。结论化肥磷酸二铵对蝌蚪发育具有显著影响及损伤。     

不同温度对中华蟾蜍早期胚胎发育的影响

本文探讨了温度与中华蟾蜍早期胚胎的发育速度、器官分化、畸形率、死亡率、增长速度之间的相互关系,并同相近温度下几种蛙卵的发育速度进行了比较。证实:中华蟾蜍早期胚胎在6—29℃范围内均能发育,最适发育温度为17—23℃,最高限温32℃,1℃时不能发育,完成早期发育的蝌蚪也不能持续耐受34℃的高温和1℃的低温;变温对胚胎发育有益;原肠胚期和神经胚期是胚胎发育中对温度最敏感的时期。     

长波紫外线照射对花背蟾蜍肾脏结构损伤

为研究长波紫外线对花背蟾蜍(Buforaddei)肾脏的损伤,用波长为365nm的长波紫外线(UVA)以352μW.cm-2的辐射量对花背蟾蜍亚成体进行150、300和450min的连续照射,分别在照射后立即、3、6、9、12和15d取材,常规石蜡切片。结果表明:UVA照射后,3组不同照射时间的花背蟾蜍肾脏整体结构基本完整,但均出现肾小管管壁破裂,管径显著缩小,肾小囊消失,而300min照射组的损伤则极为明显,其后依次为450min照射组与150min照射组,300与450min照射组的肾小体塌陷程度较150min照射组更为严重;经15d的恢复,虽出现明显好转,但大多指标仍与对照组间存在极显著性差异;UVA对花背蟾蜍肾脏有着不可忽视的损伤,虽然具有一定的自我修复的能力,但在野外,紫外辐射的增强和植被的减少可导致两栖类遭受过度的紫外辐射,进而引起两栖类种群的衰减。     

温度和湿度对蟾蜍生理功能的影响

蟾蜍随机分为室温干燥、室温保湿、低温保湿和低温冬眠组,观察禁食蟾蜍在不同温度和湿度条件下的生存时间、体重变化、心脏活动、腓肠肌收缩功能和坐骨神经干动作电位,探寻能够延长禁食蟾蜍生存时间和机体生理功能维持时间的途径。结果显示,室温干燥组蟾蜍体重自实验第1 d起显著性下降(P<0.01),其它组无显著性变化。室温干燥、室温保湿、低温保湿和低温冬眠组蟾蜍的累计死亡率分别为100%(第6 d)、45.83%(第26 d)、16.67%(第36 d)、0%。除室温保湿组蟾蜍的心脏舒缩幅度自实验第20 d起下降之外(P<0.05),其它组的心肌舒缩幅度和心率无显著性变化。室温干燥组蟾蜍的腓肠肌收缩幅度自实验第1 d开始下降,第4 d起有显著性差异(P<0.05),低温保湿组在第27 d也显著性下降(P<0.05),其他组未发生显著性变化。各组蟾蜍坐骨神经干动作电位未发生显著性改变。充足的湿度和适当降温,尤其保持冬眠,能够延长禁食蟾蜍的生存时间和机体生理功能维持时间。     

黄河上游环境污染对花背蟾蜍抗氧化酶活性及丙二醛含量的影响

选择黄河上游污染程度较严重的兰州地区和相对无污染的刘家峡地区作为研究样点,比较分析了两地花背蟾蜍（Bufo raddei）肝脏和肾脏中抗氧化酶SOD、CAT和GPx活性及丙二醛（MDA）含量。与刘家峡地区相比,兰州地区花背蟾蜍肝脏的SOD活性升高,CAT和GPx活性极显著降低,肾脏GPx活性显著增高,肝脏和肾脏MDA含量明显高于刘家峡。结果表明,黄河上游环境污染使得花背蟾蜍体内氧化胁迫加重,导致其组织脂质过氧化程度升高。     

复合肥对花背蟾蜍蝌蚪红细胞微核及核异常的影响

以花背蟾蜍蝌蚪外周血红细胞微核及核异常作为毒理监测指标,对Gosner 31、42和46期蝌蚪进行观察,研究了复合肥对水生生物的毒性效应.结果表明:用复合肥溶液浓度为1、1.5、2、2.5和3g·L-1进行染毒时,红细胞出现了大、小2种类型的微核,在核异常类型中出现了严重的核分叶和双核类型;在3个被观察的蝌蚪发育期中,42期蝌蚪红细胞微核细胞率和核异常细胞率数值明显低于其他两个发育期;在5个浓度的染毒中,2.5g·L-1浓度组在微核、双核和核分叶与对照组间无显著性差异;花背蟾蜍不同发育时期的蝌蚪,对生境中不良因素的抵抗能力存在着明显的差别,且微核和核异常与复合肥浓度之间没有明显的剂量-效应关系.     

UVA对花背蟾蜍微核及核异常的诱导

为了研究紫外线A对花背蟾蜍的毒性作用,选择微核及核异常为毒理监测指标,对花背蟾蜍红细胞进行观察.结果表明,紫外线A对花背蟾蜍成熟红细胞和非成熟红细胞核异常均有诱导作用并随照射强度的增加而不断增加.在150 min的紫外线A短时间照射内,紫外线对核异常能够产生一定的抑制作用.同时在一定范围内紫外线A能够刺激造血器官释放新的红细胞至外周血中以补充损伤的成熟红细胞.紫外线诱导的核异形主要是核畸形和核膨大.     

不周浓度乙醇对蟾蜍血压和心率的影响

本实验采用静脉内注入乙醇的方法,观察了不同浓度乙醇对蟾蜍血压和心率的影响。结果表明：尽管乙醇浓度不同,但大多数注入乙醇后血压降低,少数升高;心率大多数变慢,少数加快或不变。随着乙醇浓度升高,这种现象仍然存在。提示动物种类和个体差异,对乙醇反应也是不同的。     

肾上腺素、乙酰胆碱对蟾蜍心电图的影响

本实验用肾上腺素和乙酰胆碱分别对蟾蜍的心电图变化进行了分析。实验同结果表明,注入肾上腺素和乙酰胆碱后出现明显的心电图各波段的变化,有的变化是相同的,提示这两种药物对蟾蜍心脏的电活动变化有一定的影响。     

Studies on the differentiation of the retina receptor cell of toad (Bufo raddei Strauch)

The development of the retinal receptor cell in the young tadpoles (Bufo raddei Strauch), from the stage 20 to the stage 25, was studied by TEM and immunohistochemical method. The morphological differentiation of the photoreceptor cell may be described as follows. The time and the degree of differentiation of the cells in the tadpole retina is asynchronous between central (posterior pole) and peripheral parts of the tadpole retina, namely, they are earlier and higher in the central than in the peripheral. The cells of the outer nuclear layer are undifferentiated at the stage 20. The cells in the posterior part of the retina elongate at the beginning of the stage 21 (Plate I, Fig. 1). This is the first sign of differentiation in the photoreceptor cell. A small hillock-like process forms the inner segment at the scleral pole of the receptor cell. The inner segment is rich in mitochondria, rough-surfaced cytomembrane, free ribosomes, and vesicles. One or two large lipid droplets are also found in the inner segment (Plate I Fig. 2-3). Later on, the connecting structure develops at the tip of the inner segment. The newly formed filaments and the plasma membrane form the outer segment. Its membrane forms some evaginations oriented perpendicularly to the longitudinal axis of the receptor cell. In this way, disks of the outer segment are formed (Plate I Fig. 4-5). The length of the outer segment gradually increases with the number of disks increasing at the base. At the same time, an axon process of receptor cell, extending vitreal, develops synapses with dendrites of the bipolar cell in the outer plexiform layer. At the beginning (the stage 22), the synaptic structure is an immature form that lacks synaptic ribbons and vesicles (Plate II Fig. 8). Later on, ribbons and vesicles are observed in the further developed synaptic structure (Plate II Fig. 9). The toad rhodopsin was prepared by a method of Dewey et al. (1969) and Papermaster & Dreyer (1974) with slight modification. A specific immune serum against the toad rhodopsin was produced in rabbits. Using the indirect Coon's antibody technique, the localization of the rhodopsin antibody and the time when the antibody was seen in the retina of the early developing tadpoles was traced.(ABSTRACT TRUNCATED AT 400 WORDS)     

Diurnal rhythm, temperature and water relations of the African toad, bufo regularis

B. regularis Reuss is nocturnally active, having an endogenous rhythm that is not accelerated in darkness or retarded by constant light. The rate of water-loss is correlated with the saturation deficiency of the air and there is no control of transpiration. Pulmonary ventilation, however, plays a significant part in evaporative cooling. The lethal temperature for one hour's exposure in moist air is 39°C: in dry air a body temperature of 42°C has been recorded from a living toad. There is no correlation between rate of water-loss and the point at which dehydration becomes lethal. The maximum water-loss survived is 50% of normal body weight. The rate of water-uptake is not influenced by ambient air temperature-it is greatest in toads desiccated below 10 to 15% of original weight and declines as rehydration proceeds.     

The morphology of the juxtaglomerular apparatus in the toad,Bufo bufo

Summary In a light microscopic study the course of the tubule in the kidney of the toadBufo bufo was studied. The distal tubule returning to the glomerulus of its origin appears to enclose the afferent arteriole. In that area, from which a three dimensional graphic reconstruction is made, there is an intimate contact between tubular and vascular wall. The latter contains granulated media cells. In the part of the tubule adjacent to the afferent arteriole an accumulation of nuclei is present. It is suggested that this structure is similar to the macula densa of the mammalian juxtaglomerular apparatus. The functional significance of a stricture in the tubule distally from the macula densa-like structure is discussed.The authors wish to thank Mrs. Ineke van de Mee-Wienen and Miss Ans Rouwenhorst for their technical assistance and Mr. J. J. M. de Bekker for the realization of the graphic reconstruction.     

Membrane acclimation by unicellular organisms in response to temperature change

Unicellular organisms possess a wide variety of molecular mechanisms for altering the lipid composition (and thereby the physical properties) of their membranes in response to changes in environmental temperature. These are discussed with a view to establish which of the mechanisms are of more importance to bacteria, algae, and protozoa in coping with extremes of temperature.     

Histochemistry of the juxtaglomerular apparatus in the toad Bufo bufo

Summary An investigation regarding the question of whether there exists a macula densa as part of the juxtaglomerular apparatus in the kidney of amphibians has been carried out. With the aid of a histochemical reaction for glucose-6-phosphate dehydrogenase activity, the presence of a macula densa zone as a specialized part of the distal tubule in the toad Bufo bufo was demonstrated. The functional significance of the high glucose-6-phosphate dehydrogenase activity in the macula densa cells is discussed.     

Egg production in the Common toad, Bufo bufo

The number and size of eggs produced by the Common toad (Bufo bufo) was investigated at a site in southern England. There was a trend within the population as a whole for egg weight, egg number and ovary weight to increase with female size, as defined by body length and body weight. However, with use of partial correlation analysis to remove the effects of female size from the data, some of these trends changed. Thus, for females of the same size, although egg number increased with ovary weight, no significant correlation was found between egg weight and ovary weight whilst egg weight became negatively correlated with egg number. The possible significance of variation in egg weight on tadpole survival and female reproductive success is discussed.     

Angiotensin II elicits water seeking behavior and the water absorption response in the toad Bufo bufo

Fully hydrated toads, Bufo bufo were acclimated to a simulated terrestrial habitat, with access to shelters and water. To get from the shelters to the water, the toads had to walk across the pan of an Ohaus balance and the body weights were recorded on a computer. Toads were placed inside shelters immediately following injection of human angiotensin II (A II), Thr(8)-saralasin, or Ringer's in the dorsal lymph sac, and their behavior was recorded continuously by video surveillance. The injection doses were 1-100 microg/100 g body weight A II and 100 microg/100 g body weight saralasin dissolved in 0.1 ml Ringer's; control animals received the same volume of Ringer's. The latency from injection to the initiation of water absorption behavior (WR) was significantly shorter in both A-II- and saralasin-injected toads, compared to controls. A-II- and saralasin-injected toads also spent significantly more time in the water than controls. The bladder depots when WR was terminated were significantly larger in A-II- or saralasin-injected toads than in controls. The stimulatory action of Thr(8)-saralasin, an antagonist of A II in mammals, on WR behavior in B. bufo suggests differences in receptor structure and/or receptor distribution between amphibians and mammals.     

斑马鱼热耐受性对温度驯化的响应及其性别差异

为了探究斑马鱼(Danio rerio)热耐受性对温度驯化的响应及其性别差异,将性成熟斑马鱼分别于适温(28℃)、低温(20℃)和高温(34℃)下驯化14 d,之后测定不同温度驯化下雌鱼和雄鱼的临界高温(critical thermal maxima,CTmax)、致死高温(lethal thermal maxima,LTmax)、临界低温(critical thermal minima,CTmin)、致死低温(lethal thermal minima,LTmin)等热耐受性参数.结果表明:驯化温度对雄鱼和雌鱼的所有热忍耐参数(CTmax、LTmax、CTmin和LTmin)均影响显著(P<0.05),并且驯化温度和性别对热耐受性参数的影响具有交互作用(P<0.05).适温(28℃)驯化下,雌鱼与雄鱼各个热忍耐参数相比无显著差异(P> 0.05);低温(20℃)驯化下雌鱼的耐高温能力强于雄鱼,而高温(34℃)驯化下雌鱼的耐低温能力弱于雄鱼.结果提示:繁殖适温下雌雄斑马鱼的热耐受性趋于一致,而非繁殖适温下二者的热耐受性出现分化.     

Breeding pond fidelity in the common toad, Bufo bufo

Two independent studies of adult common toad, Bufo bufo , movements between different spawning ponds/populations both within and between years were made in England and Sweden during the spring breeding periods of1987–1990. The results of the two studies were subsequently combined since they were found to be complementary. In addition, in England during 1984 and 1985, large numbers of 'toadlets' were marked so that they could be identified if recaptured as breeding adults.
The degree of relocation between ponds was negatively correlated to the distance between ponds. The proportion of both males and females that moved between ponds within a particular year was significantly less than the proportion relocating between years. In any year, between 79% and 96% of adults that survived to breed the following year, returned to the original pond. Similarly, of the toadlets marked during1984–85, 81% of the males that subsequently returned as breeding adults were captured in their pond of origin.
Isolation, in relation to both population dynamics and population genetics, is defined and its implications for the management of common toad populatins discussed.     

The response of trout red cells to adrenaline during seasonal acclimation and changes in temperature

Adult rainbow trout were acclimated to three different temperature and photoperiod regimes: 17°C, 14 h light: 10 h dark (summer); 7° C, 14 h light: 10 h dark; and 5° C, 8 h light: 16 h dark (winter). Blood was collected from these fish after 40 days acclimation, and the response of red blood cells to in vitro adrenergic stimulation was assessed. To examine potential seasonal variations in endogenous levels of circulating catecholamines, plasma levels of adrenaline (Ad) and noradrenaline (NAd) were measured at rest and after exercise. At rest, there were no differences between groups in plasma levels of either Ad or NAd, but, after exercise, the pattern of catecholamine elevation differed. In fish acclimated to 17 and 7° C in summer, Ad and NAd increased by about the same amount (10–15 times). In fish acclimated to 5° C in winter, NAd increased about three-fold, compared to the near 50-fold increase in Ad levels. Whether this difference between groups can be attributed to seasonal influences is unclear. At both low (0·5%) and high (2%) PCO ₂, adrenergic stimulation (2 × 10^-7 M Ad) of trout red cells in vitro led to a significant reduction in MCHC (mean cell [haemoglobin]), compared to non-stimulated cells. However, only at the high PCO ₂ were pHe and red cell pHi significantly different from those in the non-stimulated cells: the latter was higher and the former lower in the stimulated cells. There were no differences in the response of red cells to adrenergic stimulation between groups of fish. Under the conditions of the present study no influence of season and/or temperature on the in vitro response of trout red cells to adrenergic stimulation was shown.