温带臭虫生活史中各龄若虫及成虫形态的进一步描述

本通过对温带臭虫生活史中各龄若虫及成虫形态的进一步描述,首次提出臭虫度量的长度随虫龄的成熟而逐步增大。身长与体宽之比基本保持在1：1.8左右,前胸宽及前胸长之比在3：1左右;除一龄若虫外,其基本基缘毛丛的数量。每增加一龄,其毛从根数也增加一根,即n 1,这在臭虫形态分类及对臭虫的进一步研究和防治有着重要的意义。     

OBSERVATIONS ON THE RESPIRATION OF TRYPANOSOMA CRUZI IN CULTURE

1. The oxygen consumption of cultural forms of Trypanosoma cruzi decreases in intensity with increasing age of the cultures; no correlation with any other factor studied could be established. 2. The respiratory quotient was high for the first 10 days, i.e. as long as the population increased; with the onset of a decline in numbers, the R.Q. began to drop. It is believed that the flagellates consume in the beginning predominantly sugar and later predominantly protein. Observations on the pH of the cultures bear out this view. 3. The oxygen consumption was independent of the oxygen tension over a wide range of tensions. 4. The oxygen consumption increased in the temperature range 13° to 40°C., while a temperature of 44°C. proved to be lethal. Upon application of Arrhenius'' equation, two straight lines, intersecting at about 28°C., resulted. The µ values were 23,980 and 5275 for the lower and higher temperature range respectively. 5. Of the oxidase inhibitors tested, strong inhibition of the oxygen consumption was achieved with azide, cyanide, and hydrogen sulfide. Pyrophosphate had no influence at all. There is some probability that cytochrome oxidase is the chief oxidase present. 6. The strongest inhibitory influence due to dehydrogenase inhibitors was observed with propyl carbamate and high concentrations of ethyl carbamate. 7. A small fraction of the oxygen consumption, about 10 per cent, may be due to substances with sulfhydryl groups, as indicated by a slight but distinct inhibition due to dilute iodoacetate and to arsenite.     

淤泥湖近太湖新银鱼的生物学及其增殖途径的研究

近太湖新银鱼的生殖期为春夏季的３月底至６月上旬,产卵盛期为４月上旬和５月上旬。性成熟年龄为１年,属分批产卵类型。终生以浮游动物为食。生长１年平均全长为６８．７ｍｍ,平均体重为０．７０ｇ。产卵后不久死亡,寿命只有１年。捕捞近太湖新银鱼的合理时期为冬季,捕捞期内划定禁渔区和向禁渔区放流部分亲本。产卵盛期人工放流受精卵或银鱼苗。     

THE EFFECTS OF KINETIN AND NAPHTHALENEACETIC ACID ON IN VITRO SHOOT MULTIPLICATION AND ROOTING IN THE FISHTAIL FERN

This study is concerned with the determination of the shoot and root inducing effects of kinetin (K) and naphthaleneacetic acid (NAA) on shoots ofthe fishtail fern (Nephrolepisfalcata formafurcans) in sterile tissue culture. The data shows that K is the major factor involved in maximal shoot production. The NAA is not essential. Specific concentrations ofNAA must be present with specific concentrations of K for maximal root production. At the same time, the data also demonstrate that shoots on media containing no NAA but with K concentrations of 5 × 10⁻⁷ and 10⁻⁶ M produced as many roots as with any other NAA concentration. The data can be used as a guide to rapid commercial propagation of fishtail fern, and demonstrate that media available commercially for Boston fern multiplication will induce maximal shoot production in fishtail fern.     

THE INFLUENCE OF RENNET ON BACTERIOPHAGE MULTIPLICATION IN MILK

SUMMARY: Milk inoculated with 1% starter culture and immediately infected with small numbers of phage particles was afforded protection from phage attack for several hours if rennetted within 30 min of infection. The degree of protection was largely dependent upon the multiplication rate of the phage under test. When rennetting was delayed for 90 min after infection, protection was greatly reduced. The effect of early rennetting was to stimulate cell multiplication and retard the increase of phage. This retardation prolonged the period before equality between cell and phage numbers was reached. Even after equality was reached, acid production continued for some hours in milk that had received early addition of rennet.     

STUDIES ON THE EFFECT OF TEMPERATURE ON VIRUS MULTIPLICATION IN INOCULATED LEAVES

The rate at which the Rothamsted tobacco necrosis virus (RTNV) accumulates in inoculated French bean leaves increases with rising temperature to 22°C. and then decreases. Three days after inoculation, leaves at 22°C. contain 4000 times as much virus as at 10°C. and 1000 times as much as at 30°C. At all temperatures the rate of accumulation may depend on the balance between synthesis and inactivation of RTNV, but inactivation becomes increasingly important with rise of temperature above 22° C. and as the virus content of the leaves increases. Above 22°C. the rate of multiplication may increase but less rapidly than the rate of inactivation, and exposing inoculated leaves to ultra-violet radiation at various intervals after inoculation suggests that at 30°C. RTNV multiplies in and moves from the initially infected epidermal cells in slightly less than the 6 hr. needed at 22°C. Thirty hr. are needed at 10°C. Newly formed virus is rapidly inactivated at 30°C. Raising the ambient temperature also decreases the numbers of local lesions produced by RTNV, possibly by increasing the chances that the introduced virus particles will become inactivated. Increasing the virus content of the inoculum above the level giving one lesion per sq.cm. does not increase the subsequent virus content of inoculated leaves.
At temperatures of 30°C. and below, tomato aucuba mosaic virus produces necrotic lesions in leaves of tobacco and Nicotiana glutinosa whereas above 30°C. the lesions are chlorotic. In both hosts this virus multiplies more rapidly when the infected cells are killed.     

THE INFLUENCE OF ACIDITY ON THE MULTIPLICATION OF LACTIC STREPTOCOCCAL BACTERIOPHAGE IN LIQUID MEDIA

SUMMARY: Mass lysis of lactic streptococci infected with baeteriophage at 30° was prevented at pH 5·10. At lower pH values no multiplication of phage followed infection, and prolonged incubation at 30° resulted in loss of phage particles from unlysed samples. Adsorption of phage particles on host cells was unaffected by acidity, but no phage penetration of host cells took place. Host cell properties were apparently unchanged by adsorption of phage particles in acid whey.     

冬季水淹对洲滩钉螺生存繁殖影响的观察

在我国长江下游江边，采用现实验性水淹的方法，观察冬季水淹对钉螺生存影响及水淹后尚存活螺繁殖力变化。结果水淹３０、６０、９０、１２０天１５０天后其亡率依次为１．２５％、９．３０％、１９．２３％、３６．０５％和３６．７０％。经水淹６０－９０天，螺的产卵量减少１／２以上，所产卵的孵化率下降约１／３。观察提示，冬季持续一定时间水淹一定时间水淹对湖沼地区钉螺生存和繁殖均为不利。     

pH AND POPULATION DENSITY IN THE REGULATION OF ANIMAL CELL MULTIPLICATION

Sparse and dense cultures of chick embryo cells were affected differently by pH. The rates of cell multiplication and of thymidine-³H incorporation into DNA of dense cultures were increased as the pH was increased from 6.6 to 7.6. At pH higher than 7.6 the rate of multiplication decreased slightly in the dense cultures, but the rate of thymidine-³H incorporation continued to increase. The discrepancy was due in part to cell death and detachment at very high pH, and in part to a more rapid uptake of thymidine-³H at very high pH. Sparse cultures were much less sensitive to pH reduction and, when a suitably conditioned medium was used to minimize cell damage, very sparse cultures grew almost as well at pH 6.7 as at higher pH. The rates of cell multiplication and thymidine-³H incorporation at low pH decreased in the initially sparse cultures before they reached confluent cell densities. There was no microscope evidence of direct contact between plasma membranes of cells at these densities although the parallel orientation indicated that the cells were influencing locally each other's behavior. Even at much higher cell densities, electron microscopy revealed large intercellular gaps partly filled with a fragmentary electron-opaque material suspected to be glycoprotein. Wounding experiments showed that pH affected cell migration in a manner similar to its effects on cell multiplication. Low pH inhibited cell migration, but those cells which migrated into the denuded region multiplied as rapidly at low pH as at high pH. The effects of pH on growth were correlated with effects on the uptake of 2-deoxyglucose-³H. Dense populations of cells inhibited by low pH were stimulated to incorporate thymidine-³H by the addition of small amounts of diethylaminoethyl-dextran. Rous sarcoma cells at high cell density were less sensitive to pH than were normal cells at the same density, but were more sensitive than sparse normal cultures. The results suggest that cell growth is inhibited through the combined effects of both lowered pH and high cell density on cell surface permeability.