应用重离子束苏制核微孔滤膜除菌除支原体的研究

本文采用苏制核微孔滤膜进行了除菌、除支原体实验研究,核孔膜孔径分别为０．０７、０．１、０．５、０．７及１．５微米,采用的菌种为白色葡萄球菌、链球菌和大肠杆菌,支原体为解脲脲原体,实验结果表明：０．０７及０．１微米的核孔膜可完全滤除细菌及支原体,０．５微米的核孔膜可滤除绝大部分细菌,不能滤除支原体,１．５微米的核孔膜只能滤除少量细菌。     

岩豆凝集素的圆二色性与生物学活性关系的研究

岩豆凝集素（ＭＤＬ）的远紫外圆二色性谱（ＣＤ谱）显示２１６－２１７ｎｍ处的单一负峰。此时ＭＤＬ分子含有１６．２％的α螺旋,４６．３％的β折叠和３７．５％的无规卷曲。ｐＨ９．０时负峰红移至２２０ｎｍ,且在２１７－２２２ｎｍ处的峰值几乎相同;在２０－４０℃范围内,ＣＤ谱的变化甚微;６０℃时谱峰蓝移;在８０℃或１００℃时,２１２ｎｍ处出现一大负峰。１ｍｏｌ／Ｌ或２ｍｏｌ／Ｌ脲时,ＭＤＬ的ＣＤ谱已发生明显变化,二级结构单元也有变化,凝集兔红细胞的活性也随之减弱;随脲浓度的增加,ＭＤＬ的谱峰蓝移,最终在２１２ｎｍ处出现大负峰。当胍浓度为０．７５ｍｏｌ／Ｌ时,ＭＤＬ的ＣＤ谱即有明显变化和活性丧失;胍浓度继续增加,ＣＤ谱逐渐成为特征的无规卷曲的谱形。在ｐＨ９．０、温度超过８０℃、脲或胍浓度分别高于２ｍｏｌ／Ｌ和０．７５ｍｏｌ／Ｌ时,ＭＤＬ的ＣＤ谱发生显著变化的同时,其凝集兔红细胞的生物学活性全部丧失,分子的二级结构单元也发生很大改变。     

Identification of two human sperm populations using flow and image cytometry

Flow cytometric studies of human sperm from fertile men display a constant and characteristic bimodal nonartifactual DNA pattern confirming the existence of two distinct populations. The main population is represented by a peak followed by a shoulder (“marginal population”). The appearance of this marginal population fluctuates with either freezing and thawing or with Percoll gradient centrifugation. We have analyzed both the main and marginal sperm populations by flow cytometry after cell sorting, laser scanning cytometry, light microscopic evaluation, and their sensitivity to DNase digestion. We have observed that the marginal population detected in fertile men represents a sperm group altered in the nuclear condensation, yielding unstable chromatin which appears more stainable with propidium iodide. © 1994 Wiley-Liss, Inc.     

The Biotransformation of Propylene to Propylene Oxide by Methylococcus capsulatus (Bath): 3. Reactivation of Inactivated Whole Cells to Give a High Productivity System

Methylococcus capsulatus (Bath) possesses methane monooxygenases (soluble - (sMMO) and particulate - (pMMO)) which are able to catalyse the epoxidation of propylene to propylene oxide. In a previous paper we have shown that the production of the epoxide caused a rapid inactivation of the bioconversion process (Stanley et al, 1992). This paper shows that cultures containing pMMO, inactivated by propylene oxide production, could be completely reactivated in the presence of growth substrates within 5 h after the removal of propylene oxide so long as the propylene oxide production rate was below 150 nmol min^-1 [mg dry weight cells]^-1. Reactivation under these conditions was detectable within 30 min of propylene oxide removal. On the other hand, cells inactivated by propylene oxide production rates in excess of 150 nmol min^-1 [mg dry weight]^-1 did not begin to recover activity within the 30 min period. Furthermore a lag period was observed before reactivation began which was dependent upon the initial production rate. Cultures possessing sMMO took twice as long to recover their activity compared with cells containing pMMO.

Reactivation of propylene oxide production could occur without growth, but the process required the presence of a carbon and energy source (methane or methanol), sulphur, nitrogen and oxygen, although copper (which is normally involved in pMMO activity) was not required. It was shown that de novo protein synthesis was required for reactivation of activity.

Production rates of 12 g 1^-1 d^-1 could be maintained for longer than three weeks in a single phase production process and rates up to 30 g 1^-1 d^-1 were achieved in a two stage process. Using Methylocystis parvus (OBBP) rates of up to 90 g 1^-1 d^-1 were attained over a one week period.     

Sexual isolation in Drosophila. II. Intraspecific variation in mate recognition systems

A simple behavioral model is used to investigate whether differences in the specific-mate-recognition system (SMRS), occur within species of the Drosophila genus. This model takes into account, and overcomes, the distorting effect of vigor differences on experimental results. Analysis shows significant deviations from the expected values under the assumption of identical SMRSs in around one fifth of the multiple-choice experiments performed with natural strains of twelve different Drosophila species. Different selection procedures raise the number of significant assortative mating results between strains of D. melanogaster and D. pseudoobscura from 3.0% to 32.8%. Finally, sub- or semispecific taxa show variations in their SMRS even more frequently (74.5%). Differences in male vigor and female receptivity are also found. These results show that a classification of Drosophila species based on SMRS stability, as proposed by the “Recognition concept of species”, is virtually impossible.     

Effects of Host Cell Density on Cell Infection Level in Antheraea eucalypti (Lepidoptera: Saturniidae) Cell Cultures Persistently Infected with Nosema bombycis (Microsporida: Nosematidae)

ABSTRACT. Spores of Nosema bombycis Y9101, isolated from the beet armyworm, Spodoptera exigua , were primed with an alkaline solution and inoculated into Antheraea eucalypti cell cultures. Infected cells were subcultured every five days at three cell densities (2.5 × 10³, 5.0 × 10³, and 1.0 × 10⁴ cells/cm²). A difference was observed in the spread of N. bombycis Y9101 infection between low-density and higher-density cultures of host cells. The host cell density did not affect the productivity of secondary infective forms of the parasite. The principal factor determining the rate of microsporidian infection in vitro was the number of host cells existing within the reach of extruded short-coiled polar tubes from spores germinated intracellularly.     

Mother-infant bonding

A study of the research on postpartum mother-infant bonding shows that results from poorly constructed research programs were published in major journals and became a part of hospital policy because the bonding concept was politically useful in the struggle between advocates of natural childbirth and managers of the medical model of birth. The concept was also uncritically accepted because it was consistent with a longstanding ideology of motherhood that sees women as the prime architects of their children’s personalities. Diane Eyer earned her Ph.D. in developmental psychology from the University of Pennsylvania. She is currently writing a book on the ways in which the concepts of bonding and attachment have affected our understanding of appropriate early childcare.     

Slow cortical potential biofeedback and the startle reflex

The negativity of slow cortical potentials (SCP) of the surface EEG is a measure of brain excitability, correlating with motor and cognitive preparation. Selfcontrol of SCP positivity has been shown to reduce seizure activity. Following SCP biofeedback from a central EEG electrode position, subjects gained bidirectional control over their SCP. The current study used a modified feedback methodology, and found a positive relationship between negativity and magnitude of EMG startle response (a measure of cortical and subcortical arousal, particularly aversive response disposition). Greater success in SCP differentiation was associated with self-report of less relaxation during negativity training.This research was supported by the Deutsche Forschungsgemeinschaft under grant No. SFB 307.     

Ontogenetic patterns of volatiles identified in Dufour's gland extracts from queens and workers of the primitively eusocial halictine bee,Lasioglossum malachmum (Hymenoptera: Halictidae)

Summary Ontogenetic patterns of volatile compounds identified in Dufour's gland extracts from queens and workers of the primitively eusocial sweat beeLasioglossum malachurum (K.) were compared. Only young unmated queens showed high proportions of isopentenyl esters, while macrocyclic lactones were dominant in old breeding queens, spring queens, and workers. In young queens the relative and absolute amounts of volatiles changed one day after mating. A discriminant analysis revealed significant differences in odor patterns of unmated and mated young queens. The fat body was the largest in young females, while eggs could be recorded only in breeding queens. Possible functions of different odor components in the investigated female groups are discussed.