The control of protein synthesis during heat shock in Drosophila cells involves altered polypeptide elongation rates

When Drosophila tissue culture cells are shifted from 25 to 36°C (heat shocked) the pre-existing mRNAs (25°C mRNAs) remain in the cytoplasm but their translation products are underrepresented relative to the induced heat shock proteins. Many of these undertranslated 25°C mRNAs are found in association with polysomes of similar size in heat-shocked and control cells. Furthermore, the messages encoding α-tubulin, β-tubulin, and actin are found associated with one-third to one-half as many total ribosomes in heat-shocked cells as in cells incubated at 25°C. Increased temperature should lead to increased output of protein per ribosome. However, the 25°C proteins are actually synthesized at less than 10% of 25°C levels in heat-shocked cells. Thus, the rates of both elongation and initiation of translation are significantly (15- to 30-fold) slower on 25°C mRNAs than they are on heat shock mRNAs in heat-shocked cells.     

The effect of anisotonic media upon cellular ultra-structure in fresh and fixed rat brain

Summary When tissue slices or small blocks of unfixed rat cerebrum are incubated in various anisotonic physiological media, distinctive morphological changes are induced in glial cells, neurons, and endothelial cells. The variation in observed cellular swelling and shrinkage may be related to differences in ionic content of the cytoplasm of these cells. When HAA, glutal, and osmium tetroxide fixed tissue is incubated in this manner, only the cerebrum fixed in HAA responds to osmotic inequilibrium in a manner similar to unfixed tissue. Although HAA does not fix tissues very well, the permeability of plasma membranes in the brain appears to be less altered by HAA than by glutal or osmium tetroxide. The relationship of these findings to a demonstration of the extracellular space in HAA fixed tissues is discussed.This work was supported by grants (U-1293) from the Health Research Council of the City of New York and (NB 04161-02) from the National Institute of Neurological Disease and Blindness of the National Institutes of Health.     

糙叶败酱挥发油镇静作用的研究

本文观察了败酱科植物糙叶败酱(Patrinia scabra Bunge)根和根茎中制得的挥发油的镇静作用,井与黄花败酱挥发油做了比较。结果表明,此油灌胃给予数组小鼠,剂量0.45ml/kg,显示如下的作用:[1]能显著延长由于腹腔注射戊巴比妥钠(50mg/kg)引起的小鼠睡眠时间,但其作用强度弱于黄花败酱挥发油。(2)一次灌胃给予小鼠大剂量10.46g/kg的糙叶败酱挥发油,连续观察10天,动物外观正常,无一死亡,体重增加与对照组相似。     

The inhibition of catalase by glutathione

Reduced glutathione (GSH) inhibited catalase activity in a dose-dependent manner. DL-dithiothreitol (DL-DTT) and dithioerythritol (DTE) also inhibited catalase activity. The inhibition of catalase by GSH and DL-DTT could be reduced by NADPH. Polyacrilamide gel electrophoresis demonstrated the inhibition was partially reversible. The inhibition of catalase by GSH appeared to be partly due to superoxide radicals, since it was inhibited by active manganese superoxide dismutase, but not by heat-inactivated enzyme. Other chemical species also appear to take part in the inhibition, but they could not be identified.     

Detection of IgG and IgM antibodies with ELISA technique in human trichomoniasis

The direct wet mount examination of vaginal secretion, widely applied for the diagnosis of Trichomonas vaginalis infection in woman patients, is rapid and economical, however, the sensitivity of this technique is not so high. In this study enzyme-linked immunosorbent assay (ELISA) was employed for the detection of serum anti-T. vaginalis IgG and IgM antibodies from 30 vaginal trichomoniasis patients and 30 non-infected healthy persons. The results were as follows: 1. Serum ELISA-IgG value was 0.37 +/- 0.134 (Mean +/- S.D.) in vaginal trichomoniasis patients and 0.21 +/- 0.054 in healthy controls (p less than 0.005), and the sensitivity and specificity of ELISA for serum IgG antibody were 70.0% and 96.7%, respectively. 2. Serum ELISA-IgM value was 0.33 +/- 0.177 (Mean +/- S.D.) in vaginal trichomoniasis patients and 0.11 +/- 0.051 in healthy controls (p less than 0.005), and the sensitivity and specificity of ELISA for serum IgM antibody were 70.0% and 96.7%, respectively. 3. The ELISA-IgG values showed a significant correlation with ELISA-IgM values (r = 0.77, p less than 0.005). With above results, it is assumed that ELISA is a reliable method for the diagnosis of T. vaginalis infection and simultaneous measurement of serum IgG and IgM with this technique is recommended.     

Voltage-independent barium-permeable channel activated inLymnaea neurons by internal perfusion or patch excision

Summary Isolated nerve cells fromLymnaea stagnalis were studied using the internal-perfusion and patch-clamp techniques. Patch excision frequently activated a voltage-independent Ba²⁺-permeable channel with a slope conductance of 27 pS at negative potentials (50mm Ba²⁺). This channel is not seen in patches on healthy cells and, unlike the voltage-dependent Ca channel, is not labile in isolated patches. The activity of the channel in inside-out patches is unaffected by intracellular ATP, Ca²⁺ below 1mm or the catalytic subunit of cAMP-dependent protein kinase but is reversibly blocked by millimolar intracellular Ca²⁺ or Ba²⁺. The channel can be activated in on-cell patches by either internal perfusion with high Ca²⁺ or the long-term internal perfusion of low Ca²⁺ solutions not containing ATP. These channels may carry the inward Ca²⁺ current which causes a regenerative increase in intracellular Ca⁺ when snail neurons are perfused with high Ca²⁺ solutions. High internal Ca²⁺, or long periods of internal perfusion with ATP-free solutions, induces an increase in a resting (–50 mV) whole-cell Ba²⁺ conductance. This conductance can be turned off by returning the intracellular perfusate to a low Ca²⁺ solution containing ATP and Mg²⁺. The activity of this channel appears to have an opposite dependence on intracellular conditions to that of the voltage-dependent Ca channel.     

长江中游鱼类寄生棘头虫区系的研究

经过3年10次调查,剖检湖北省宜都、黄冈两处江段所产72种鱼类,共计766尾。收集棘头虫10种,其中包括2新种和1新组合,即蛇鮈新棘吻虫(新种)Neoechinorhynchus saurogobi sp.nov.,长江丽棘虫(新种)Brentisentis yangtzensis sp.nov.(Illiosontidae),鲤丽棘虫(新组合)B.cyprini comb.nov.。对长江中游鱼类寄生棘头虫区系的特点进行了分析和探讨。     

Electroporation of Bradyrhizobium japonicum

Summary Electroporation offers a fast, efficient and reproducible way to introduce DNA into bacteria. We have successfully used this technique to transform two commercially important strains of Bradyrhizobium japonicum, the nitrogen-fixing soybean symbiont. Initially, electroporation conditions were optimized using plasmid DNA which had been prepared from the same B. japonicum strain into which the{imDNA was to b}e transformed. Efficiencies of 10⁵-10⁶ transformants/g DNA were obtained for strains USDA 110 and 61A152 with ready-to-use frozen cells. Successful electroporation of B. japonicum with plasmid DNA prepared from Escherichia coli varied with the E. coli strain from which the plasmid was purified. The highest transformation efficiencies (10⁴ transformants/g DNA) were obtained using DNA prepared from a dcm ^– dam ^– strain of E. coli. This suggests that routine isolation of DNA from an E. coli strain incapable of DNA modification should help in increasing transformation efficiencies for other strains of bacteria where DNA restriction appears to be a significant obstacle to successful transformation. We have also monitored the rate of spontaneous mutation in electroporated cells and saw no significant difference in the frequency of streptomycin resistance for electroporated cells compared to control cells.     

Multiple origins for phenylketonuria in Europe

Phenylketonuria (PKU), a disorder of amino acid metabolism prevalent among Caucasians and other ethnic groups, is caused primarily by a deficiency of the hepatic enzyme phenylalanine hydroxylase (PAH). PKU is a highly heterogeneous disorder, with more than 60 molecular lesions identified in the PAH gene. The haplotype associations, relative frequencies, and distributions of five prevalent PAH mutations (R158Q, R261Q, IVS10nt546, R408W, and IVS12n1) were established in a comprehensive European sample population and subsequently were examined to determine the potential roles of several genetic mechanisms in explaining the present distribution of the major PKU alleles. Each of these five mutations was strongly associated with only one of the more than 70 chromosomal haplotypes defined by eight RFLPs in or near the PAH gene. These findings suggest that each of these mutations arose through a single founding event that occurred within time periods ranging from several hundred to several thousand years ago. From the significant differences observed in the relative frequencies and distributions of these five alleles throughout Europe, four of these putative founding events could be localized to specific ethnic subgroups. Together, these data suggest that there were multiple, geographically and ethnically distinct origins for PKU within the European population.