Observations on the biology of Leuciscus ‘svallize’ in the Kremasta reservoir (Greece)

The age, growth, feeding habits and reproductive biology of Leuciscus svallize in artificial lake Kremasta (Greece), are described. There is a considerable similarity in the feeding and reproductive characteristics between L. svallize and L. cephalus and also a similarity in the life span, growth patterns and age of maturation between L. svallize and some southern L. cephalus populations, which may suggest similar responses of closely related taxa to similar conditions.     

利用秆维管束进行中国散生竹类的聚类分析

本文是应用模糊聚类分析方法研究中国散生竹类分类的一次尝试。分类特征采用了竹秆上、中、下三段各类型维管束数,方法上使用了模糊(Fuzzy)直接聚类分析进行综合分析。经电子计算机运算后,不仅取得了与传统分类基本一致的分类结果,同时也表明这种方法较之其它一些植物数量分类方法简便易行,此外还讨论了一些中国散生竹类分类上的问题。     

不同来源的肾综合征出血热病毒对Vero细胞的致病变作用

前文报道,肾综合征出血热病毒76-118株能使Vero细胞产生病变。本文报道76-118株和另11株不同来源的肾综合征出血热病毒(H537、A9、H5、R178、HB55、R22、Z10,沟3、L99、A16和J10)对Vero细胞的致病变作用(CPE )。其中除沟3株外,大部分毒株在感染Vero细胞后的第一代即可见明显的CPE。CPE的特点与76-118株相似,主要是感染细胞粘聚、融合,形成网状结构。CPE能被特异性抗HFRS病毒血清和型特异性单克隆抗体所中和抑制,但不能被特异性抗呼肠孤病毒Ⅲ型免疫血清所中和抑制。HFRS病毒对Vero细胞的致病变作用,对进一步研究HFRS病毒的某些生物学特性及实验方法等均有重要意义。     

肾综合征出血热病毒糖蛋白的提纯和鉴定

以感染肾综合征出血热病毒(HFRSV)的Vero E6细胞为材料,用免疫亲和层析结合制备聚丙烯酰胺凝胶电泳(PAGE)从感染细胞中提纯了HFRSV两种糖蛋白。先用免疫亲和层析从感染细胞的粗制抗原中获得含有四种蛋白的混合液,用[~3H]-氨基葡萄糖在感染细胞中标记病毒糖蛋白,观察到[~3H]-氨基葡萄糖只结合入78K和57K的病毒蛋白。再用制备SDS-PAGE从HFRSV混合液中提纯78K和57K两种蛋白。实验证明这两种糖蛋白均具中和抗原决定簇,57K的糖蛋白尚具血凝活性,初步鉴定表明这两种糖蛋白相当于文献报道的HFRSV G_1和G_2。     

Kinetics of lipase-catalyzed esterification in supercritical CO(2)

This study compares two solvents for enzymatic reactions: supercritical carbon dioxide (SCCO(2)) and organic solvent (n-hexane). The model reaction that was chosen was the esterification of oleic acid by ethanol catalyzed by an immobilized lipase from Mucor miehei (Lypozyme). The stability of the enzyme appeared to be quite good and similar in both media but was affected by the water content. Partition of water between solvents and immobilized enzyme has been calculated from experimental adsorption isotherms. The water content of the solid phase has a dramatic influence on the activity of the enzyme and its optimum value for activity was about 10% (w/w) in both media. A kinetic study enabled a Ping-Pong Bi-Bi reaction mechanism with inhibition by ethanol to be suggested. Despite some differences in kinetic constants, activity was in the same range in both media. Hypotheses for explaining the kinetic constant variations have been proposed and particular attention has been paid to the pH effects.     

Second-harmonic generation in monolayers of hemicyanine dyes at the air/water interface: Observation of chemical degradation

In situ studies of second-harmonic generation (SHG) in monolayers of pure hemicyanine dyes and their mixtures with arachidic acid at the air/water interface were performed. The studies revealed an unexpected chemical instability of the hemicyanine dyes involving a cleavage of the stilbene double bond when deposited onto the water surface. This reaction occurred especially rapidly in the presence of the arachidic acid. Dilution with arachidic acid did not lead to a significant enhancement of the harmonic intensity.     

Time-correlated flights of juvenile and mature locusts: A comparison between free and tethered animals

The flights of free and tethered Locusta migratoria were followed from initiation with a high-speed film camera. A longer sequence of wing-beat cycles can thus be correlated unequivocally with the animals's movement in time and space. In both flight situations the locusts start with approximately the same instantaneous wing-beat frequency. During the early flight phase free-flying animals increase their wing-beat frequency, whereas for tethered locusts this parameter remains constant or even decreases. The general flight pattern is similar in juvenile and mature locusts; the juveniles however, fly with alower wing-beat frequency and flight speed. The differences in the wing-beat frequencies for both flight performances are discussed with respect to differences in the sensory inputs to the flight motor centre.     

Naltrexone partially inhibits the estrogen-induced increase in prolactin secretion and anterior pituitary weight

The effects of naltrexone, a specific opiate antagonist, on stimulation by estradiol benzoate (EB) of prolactin (PRL) release and anterior pituitary (AP) weight, were studied in gonadectomized female and male Sprague-Dawley rats. One week after castration, rats were injected for 10 days once daily with 2 μg EB alone, or together with twice daily injections of 2 mg naltrexone/kg body weight (BW). Blood was collected for radioimmunoassay of PRL by orbital sinus puncture on days 0 and 6, and by decapitation on day 11, at which time the AP was quickly removed, weighed and assayed for PRL.Serum PRL concentrations and AP weights were significantly increased by EB administration. These effects of EB were partially but significantly inhibited by naltrexone. These results suggest that endegenous opiates may be involved in the estrogen-induced rise in serum PRL and increase in pituatary weight.     

Influx of γ-Aminobutyric Acid and α-Aminoisobutyric Acid into Mouse Cerebrum Slices Incubated in a Pyruvate Medium with or without Added Glucose or Glucose Analogues Compared with Influx from a Glucose Medium

Concentrative influx of γ-aminobutyric acid (GABA) and α-aminoisobutyric acid (AIB) into incubated mouse cerebrum slices is decreased when pyruvate is substituted for glucose. Influx of GABA from pyruvate medium is not increased by presence of glucose, 2-deoxy-d -glucose (2-DOG), or 3-O-methyl-d -glucose (3-O-MeG). Influx of AIB is restored to the rate from glucose medium if 2-DOG is present initially, but is not restored if 2-DOG is added with AIB. Influx is not restored if 3-O-MeG is present initially, but is restored if 3-O-MeG is added with AIB. Influx is restored if glucose is present initially or is added with AIB.     

A comparison of the inhibitory effects of melatonin and indomethacin on platelet aggregation and thromboxane release

Collagen-induced platelet aggregation and thromboxane release is inhibited, in a concentration response relationship, by preincubation of gel-filtered platelets with melatonin in the concentration range 430 nM – 4.3 mM. Inhibition of platelet aggregation and thromboxane release also occurs in the presence of indomethacin (4.3 nM – 4.3 mM), a known potent inhibitor of prostaglandin synthesis. Arachidonic acid-induced platelet aggregation and thromboxane release was inhibited in the presence of 4.0 mM melatonin. We therefore propose that inhibition of prostaglandin synthesis maybe the mechanism by which melatonin expresses its activity. Its antigonadotropic activity may result from inhibition of PGE₂ synthesis in the hypothalamus and median eminence.