Photoperiod-dependent changes in exocytotic activity in the hypophyseal pars tuberalis of the Djungarian hamster,Phodopus sungorus

The pars tuberalis of the hypophysis of the Djungarian hamster, Phodopus sungorus, was investigated with regard to secretory activity by applying the tannic acid-Ringer perfusion technique. Two groups were maintained under long photoperiods (16 h light: 8 h dark) or short photoperiods (8 h light: 16 h dark), respectively. Perfusion with tannic acid showed that specific pars tuberalis cells release some of their secretory granules as indicated by typical exocytotic figures. The percentage of cells displaying exocytotic activity was significantly higher in the pars tuberalis of hamsters kept under long photoperiods. The number of exocytotic figures per single cell was not increased. These results provide further evidence for a secretory activity of the pars tuberalis and support the hypothesis of its involvement as a mediator between photoperiodic stimuli and the endocrine system.     

Finding the best antibody dilution by repeated immunostaining of the same tissue section

One can find the optimal antibody dilution for immunostaining by repeated staining on the same tissue section by using a less dilute antibody for each attempt. Using secondary antibody and horseradish peroxidase conjugated to a dextran polymer, a section stained repeatedly with several dilutions of antibody appears as good as a section stained with only the last dilution.     

吗啡对大鼠海马神经元突触传递的作用及机制探讨

目的 :从离子通道角度研究吗啡对中枢神经系统兴奋性及抑制性突触传递的作用并探讨其机制。方法 :　原代培养新生Wistar大鼠的海马神经元。采用膜片钳技术研究吗啡对其兴奋性及抑制性突触后电流及谷氨酸诱发电流的影响。结果 :①吗啡可明显增强海马神经元兴奋性突触传递 ,加吗啡后自发兴奋性突触后电流 (sEPSC)的发放频率增加了 ( 2 0 7.8± 2 0 .9) %。此作用可被阿片受体阻断剂纳洛酮阻断 (P <0 .0 1) ;②吗啡对微小兴奋性突触后电流 (mEPSC)的发放频率及谷氨酸诱发电流的幅度没有明显影响 (P >0 .0 5 ) ;③吗啡可明显抑制神经元自发抑制性突触后电流 (sIPSC) ,纳洛酮可拮抗吗啡作用 (n =13 ,P <0 .0 1)。结论 :实验结果提示吗啡对海马神经元的兴奋作用不是由于吗啡直接作用于兴奋性氨基酸—谷氨酸突触传递过程 ,而是可能由于抑制了抑制性中间神经元 ,间接产生的兴奋作用。     

Morphological evidence for the existence of a more complex cytoskeleton in Amoeba proteus

Summary Various stabilization and extraction procedures were tested to demonstrate the ultrastructural organization of the cytoskeleton in normal, locomoting Amoeba proteus. Most reliable results were obtained after careful fixation in glutaraldehyde/lysine followed by prolonged extraction in a polyethylene glycol/Triton X-100 solution. Before dehydration in a graded series of ethanol and critical-point drying, the amoebae were split by the sandwich-technique, i.e., by mechanical cleavage of cells mounted between two poly-L-lysine-coated glass slides. Platinum-carbon replicas as well as thin sections prepared from such cell fragments revealed a cytoskeleton composed of at least four different types of filaments: (1) 5–7-nm filaments organized as a more or less ordered cortical network at the internal face of the plasma membrane and probably representing F-actin; (2) 10–12-nm filaments running separately or slightly aggregated through the cytoplasm and probably representing intermediate filaments; (3) 24–26-nm filaments forming a loose network and probably representing microtubules; and (4) 2–4-nm filaments as connecting elements between the other cytoskeleton constituents. Whereas microfilaments are responsible for protoplasmic streaming and other motile phenomena, the function of intermediate filaments and cytoplasmic microtubules in amoebae is still obscure.     

Amphiphilic effects of local anesthetics on rotational mobility in neuronal and model membranes

To provide a basis for studying the molecular mechanism of pharmacological action of local anesthetics, we carried out a study of the membrane actions of tetracaine, bupivacaine, lidocaine, prilocaine and procaine. Fluorescence polarization of 12-(9-anthroyloxy)stearic acid (12-AS) and 2-(9-anthroyloxy)stearic acid (2-AS) were used to examine the effects of local anesthetics on differential rotational mobility between polar region and hydrocarbon interior of synaptosomal plasma membrane vesicles (SPMV) isolated from bovine cerebral cortex, and liposomes of total lipids (SPMVTL) and phospholipids (SPMVPL) extracted from the SPMV. The two membrane components differed with respect to 2 and 12 anthroyloxy stearate (2-AS, 12-AS) probes, indicating that a difference in the membrane fluidity may be present. In a dose-dependent manner, tetracaine, bupivacaine, lidocaine, prilocaine and procaine decreased anisotropy of 12-AS in the hydrocarbon interior of the SPMV, SPMVTL and SPMVPL, but tetracaine, bupivacaine, lidocaine and prilocaine increased anisotropy of 2-AS in the membrane interface. These results indicate that local anesthetics have significant disordering effects on hydrocarbon interior of the SPMV, SPMVTL and SPMVPL, but have significant ordering effects on the membrane interface, and thus they could affect the transport of Na⁺ and K⁺ in nerve membranes, leading to anesthetic action.     

Reproduction and growth of the black shore skink,Leiolopisma suteri (Lacertilia: Scincidae), in north‐eastern New Zealand

Reproduction and growth of a boulder beach population of the nocturnal skink Leiolopisma suteri on Motutapu Island were studied for 19 months. Epididymes contain sperm from April to November, and copulation probably occurs in October or November (spring). Ovulation occurs in late October or early November, and three or four (mean, 3.7) eggs are laid in late December. Incubation takes 3 months. Total development time from ovulation to hatching is 5 months, one of the longest development periods recorded for Scincidae. Growth to sexual maturity is slow, most females depositing their first clutch 33 months after hatching; males mature at 29 months.     

The adequacy of collecting techniques for estimating species richness of grassland invertebrates

1.  There is still considerable debate about the most effective methods of sampling invertebrates in monitoring and assessment programmes.
2.  The above-ground invertebrates of a limestone grassland in north-east England were compared between samples from pitfall traps and from a D-vac suction trap combined with a lightweight swish net (SW/DV).
3.  Over 14 000 individuals were captured, with similar numbers in the pitfall and SW/DV samples. A total of 480 species of Hemiptera, Coleoptera, Diptera and Araneae was identified and placed into 14 taxa for further analysis.
4.  The pitfall sample produced species/specimen curves from which it was possible to estimate species richness for all the Coleoptera and Araneae taxa and the calypterate Schizophora. The SW/DV sample was adequate to estimate the species richness of Hemiptera, most Diptera taxa, herbivorous Coleoptera and Linyphiidae.
5.  The proportion of Coleoptera and Araneae taxa that were method-unique was higher in the pitfall sample than the SW/DV sample and vice versa for the Hemiptera and Diptera taxa. Nevertheless, a relatively high proportion of method-unique species of most taxa was found in both sample types, indicating that they can each contribute to assessing species assemblages in grasslands.
6.  Both pitfall traps and SW/DV samples are needed to estimate species richness in grasslands for all taxa except Heteroptera, Homoptera and Lycosidae. Herbivorous Coleoptera and Linyphiidae were collected in numbers adequate for assessing richness in both sample types, but more specimens were required in one or other sample for the remaining taxa.     

应用脂质体介导技术改变重组杆状病毒感染方法

昆虫重组杆状病毒表达系统是有效的真核表达系统之一,广泛应用于重组蛋白的生产。目前常采用将重组病毒直接注射入家蚕体内的方法进行感染表达,在实际操作过程中很容易造成病毒对环境的污染,具有潜在的危险性。为了严格控制作业环境重组病毒的扩散和潜在污染,开发安全、有效的感染方法显得非常必要。本研究直接将病毒基因组DNA导入家蚕体内取得同样的感染效果,探讨了利用阳离子脂质体介导下的避免病毒污染和提高感染效果的感染方法。     

Cloning and characterization of BS-cadherin, a novel cadherin from the colonial urochordate Botryllus schlosseri

The genomic DNA for a novel member of the cadherin family (BS-cadherin) was cloned and characterized from the colonial marine invertebrate, Botryllus schlosseri. Using a differential display of mRNA by means of PCR, a small cDNA fragment of 380 nucleotides was found to be specifically expressed in a colony undergoing allogeneic rejection processes, as compared with naïve parts of the same genotype. This cDNA fragment was used as a probe to screen a genomic library of Botryllus schlosseri. A genomic fragment containing an ORF of 2718 nucleotides, with no introns, was isolated. The encoded protein exhibits a typical structure of cadherins; an extracellular domain with conserved repeated sequences (cadherin signatures), a single transmembrane domain and a conserved cytoplasmic tail region. The BS-cadherin amino-acid sequence shows 32–35% identity to mature classical cadherins type I, e.g., N-, P- and E-cadherin as well as mature classical cadherins type II, e.g., human cadherin-6, -8 and OB-cadherin. This cadherin represents a new cadherin gene family, evolutionarily distant to all other known classical cadherins.     

激光微束在两种鱼受精卵上打孔技术研究

在埃及胡子鲶和苏氏芒鲶两种鱼受精卵上,用脉冲ＹＡＧ激光微束打孔技术,成功地导入了外源指示剂和用激光微束打过孔的受精卵孵化出了仔鱼,为今后激光微束打孔植入外源基因和针类转基因研究做了一些有意义的探索工作。