温度休克法诱导草履虫的同步分裂

运用细胞周期原理,采用温度休克法,对尾草履虫进行分裂周期同步化的研究,实验中草履虫经过3－5h的处理后,就能观察到大量不同阶段的无性生殖横分裂状态,并获得了大量处于分裂阶段的草履虫。运用这种技术取材容易,获取率稳定,可达61％,可为细胞生理学等领域的研究提供大量的同步分裂个体。     

激光对尾草履虫分裂繁殖影响的研究

采用Ｈｅ－Ｎｅ激光辐照经单克隆培养的尾草履虫（Ｐａｒａｍｅｃｉｕｍｃａｕａｔｕｍ）无性繁殖系,观察并分析激光对尾草履虫分裂繁殖产生的影响,结果表明,在本实验条件下,当辐照的能量密度处于５０．９－１０１．９（Ｊ／ｃｍ＾２）范围内,激光对尾草履虫的分裂繁殖产生促进作用,当辐照的能量密度为１０１．９Ｊ／ｃｍ＾２时,草履虫分裂繁殖的个体平均数达最大值。草履虫对激光辐照有很大的耐受范围和很强的耐受能力。本实     

金黄滴虫细胞同步分裂的诱导

无菌培养的金黄滴虫在25℃及连续通气的条件下,经12小时光照(2500Lux)和12小时黑暗的相间处理,可连续出现三次同步分裂,同步分裂率最高可达92％,即细胞数在一小时内可陡增92％。 细胞核动态的观察表明,在黑暗处理期中细胞被阻止于细胞分裂的前期。当黑暗处理11小时后,前期细胞突破阻拦,实现了同步分裂。     

培养温度和保存时间对草履虫密度的影响

草履虫是原生动物门纤毛纲的代表动物。在培养与保存草履虫的过程中,培养液中草履虫密度高低,直接影响学生的实验效果。实验证明,草履虫的生长、繁殖受温度影响比较大。草履虫培养液在不同温度条件下、保存时间长短不同,草履虫的密度不同。围绕着这一问题,进行了温度和时间对草履虫密度影响的研究。     

草履虫的冬季培养

草履虫作为原生动物纤毛纲的代表 ,在动物学教学和实验中是必不可少的 ,在遗传学、细胞生物学、生物化学以及生理学等领域内也被广泛采用 ,且需要量大 ,纯度要求高。关于草履虫的培养方法 ,已有诸多报道 ,这里介绍一种冬季在人工控温条件下用熟鸡蛋黄培养草履虫的方法。1　 草履虫的简易纯化与培养取普通多孔水浴锅一只 ,在锅内安装一只暖棒 (恒温加热器 ,温度范围 16 - 32℃ ) ,加水、通电、调温至 2 5℃ ;同时安放 5 0ｍｌ、 10 0 0ｍｌ烧杯各一只 ,内盛自来水 2 / 3左右。将野外采集的草履虫液在水浴锅中放置一周左右 ,取上层含有草履虫…     

草履虫的运动与摄食

描述了草履虫的形态结构及不同细胞器的主要功能,进而结合示意图详细叙述了草履虫是如何进行运动和摄食的.     

几种常见的限制草履虫运动的方法及改进

草履虫在分类上属原生动物门纤毛纲动物。由于它易采集和培养,常被用做中学生物课以及高校生物专业学生学习原生动物的实验材料。但是,草履虫的运动速度较快,这影响了实验者尤其是初学者对草履虫外部形态及内部结构的详细观察,而且草履虫的观察实验一般安排在课程的第一次,因此     

中国对虾三倍体的诱发研究 1.温度休克

温度休克中国对虾(Penaeus orientalis)的受精卵,结果表明,用0、6和9℃的低温休克,温度越低或休克时间越长,对细胞分裂的抑制作用也越强,孵化率也越低,用30和33℃的高温休克,温度越高或休克时间越长,对细胞的伤害也越大,孵化率明显降低。低温和高温休克都能诱发三倍体,三倍体的最高诱发率,低温(9℃)为43.8％,高温(30℃)为32％,并获得三倍体蚤状幼体,对虾三倍体的诱发成功,为对虾的多倍体育种提供了可能。     

温度对草履虫横分裂影响的实验

草履虫是原生动物实验的常用材料。无性生殖中的分裂生殖实验可用草履虫进行。器材和实验材料实验仪器:体视显微镜、温箱、微吸管、凹玻片、盖玻片、烧杯、蒸馏水、稻草培养液温箱制作:取一带盖的小木箱,内装一支60W电灯泡,放一温度计,用箱盖开的大小来控制温度,在实验前反复实验几次以便掌握。微吸管制作:取细玻璃管,手持两端将管的中央部位在酒精灯上烧数分钟,使玻璃管软化,随供随向左右轻拉,逐渐拉断玻璃管,使管的端部成细针状。折去管尖端一小段,使管口孔径极小即可。配上橡皮管头,便可使用。吸取草履虫时,不要按橡皮管头,只将管口一     

Biophoton Emission Induced by Heat Shock

Ultraweak biophoton emission originates from the generation of reactive oxygen species (ROS) that are produced in mitochondria as by-products of cellular respiration. In healthy cells, the concentration of ROS is minimized by a system of biological antioxidants. However, heat shock changes the equilibrium between oxidative stress and antioxidant activity, that is, a rapid rise in temperature induces biophoton emission from ROS. Although the rate and intensity of biophoton emission was observed to increase in response to elevated temperatures, pretreatment at lower high temperatures inhibited photon emission at higher temperatures. Biophoton measurements are useful for observing and evaluating heat shock.     

Macronuclear Regeneration and Cell Division in Paramecium caudatum

SYNOPSIS. In Paramecium caudatum , occurrence of macronuclear regeneration is closely related to the time of feeding after conjugation. Macronuclear regeneration is induced with a high frequency when conjugating pairs are transferred into fresh culture medium. Feeding immediately after conjugation induces early cell division and 3 or more fissions occur without macronuclear division because of the inability of the macronuclear anlagen to divide. In the cells lacking normal macronuclear anlagen, old macronuclear fragments undergo regeneration and form vegetative macronuclei.     

Responses of Paramecium to Temperature Change

SYNOPSIS. The effect of temperature on the swimming velocity of Paramecium was investigated. When paramecia cultured at 25 C were transferred to various temperatures, their swimming velocity was increased immediately and then decreased exponentially with time to a new steady velocity. The relaxation time was about 1 min, independent of the new temperature. At a constant temperature the steady velocity was inversely proportional to viscosity. The velocity acceleration was observed when the sudden temperature change was larger than ± 1 C. Its magnitude became constant when the temperature change was greater than several degrees. The steady velocity as a function of temperature had a sharp maximum at the culture temperature and decreased on both sides of this temperature. Incubation of paramecia at 30 C for several hr after cultivation at 25 C shifted the maximum temperature of the steady velocity to 30 C. The temperature at which paramecia gathered in a temperature gradient cell correlated closely with the temperature of the maximum steady velocity.     

Induction of Temperature Sensitivity in Paramecium aurelia by Nitrosoguanidine*

Paramecium aurelia cells were exposed to N-methyl-N-nitroso-N′-nitroguanidine for periods of 15–30 min. The lethality in homozygous clones derived from treated cells depends on the time of treatment within the cell cycle. Exposures at interfission ages 0.04, 0.40, and 0.80 were tested yielding lethalities of 12.5, 44 and 2%, respectively. These results correlate with the period of DNA synthesis in the micronuclei. A temperature sensitive mutant has been found which cannot live at 31 C but divides at ～1 fission per day at 19 and 25 C. The rise in temperature from 19–25 C does not significantly change the fission rate whereas in normal cells it would be doubled. Genetic analysis shows that this mutation is caused by a single recessive gene.     

Ultraviolet Light-Induced Division Delay in Synchronized Chinese Hamster Cells

The age-dependent, ultraviolet light (UVL) (254 nm)-induced division delay of surviving and nonsurviving Chinese hamster cells was studied. The response was examined after UVL exposures adjusted to yield approximately the same survival levels at different stages of the cell cycle, 60% or 30% survival. Cells irradiated in the middle of S suffered the longest division delay, and cells exposed in mitosis or in G₁ had about the same smaller delay in division. Cells irradiated in G₂, however, were not delayed at either survival level. It was further established, after exposures that yielded about 30% survivors at various stages of the cycle, that surviving cells had shorter delays than nonsurvivors. This difference was not observed for cells in G₂ at the time of exposure; i.e., neither surviving nor nonsurviving G₂ cells were delayed in division. The examination of mitotic index vs. time revealed that most cells reach mitosis, but all of the increase in the number of cells in the population can be accounted for by the increase of the viable cell fraction. These observations suggest strongly that nonsurviving cells, although present during most of the experiment, are stopped at mitosis and do not divide. Cells in mitosis at the time of irradiation complete their division, and in the same length of time as unirradiated controls. Division and mitotic delays after UVL are relatively much larger than after X-ray doses that reduce survival to about the same level.     

Sensitivity of Paramecium Thermotaxis to Temperature Change

SYNOPSIS. The relationship to swimming velocity of the critical temperature gradient necessary for inducing thermotaxis in Paramecium caudatum was analyzed at various temperatures and viscosities. Since the critical temperature gradient was linearly proportional to the inverse of the swimming velocity, it is concluded that P. caudatum detects temperature changes by locomotion through space and thus exhibits thermotaxis, provided the rate of change is > 0.055 C/sec. The swimming velocity jump was observed when the ciliates were subjected to a stepwise temperature change toward an optimum with a rate > 0.05 C/sec; the jump was not observed, however, when they were subjected to a change toward an unpreferred temperature with the same rate. Hence, thermotaxis can be explained partly by the swimming velocity jump brought about when the cells are swimming toward an optimum temperature in a spatial gradient. It is suggested that thermotaxis might be a direct manifestation of the dynamic properties of membrane as a receptor.