Opioid-binding protein (OBCAM) is rich in β-sheets

Based on circular dichroism (CD) and the sequence-predictive method, the opioid-binding cell adhesion molecule (OBCAM) consisted of one half -sheets and one fourth -helices. This is consistent with significant sequence homology of the protein to several members of the immunoglobulin (Ig) superfamily, particularly cell adhesion molecules, which are rich in -sheets. Hydropathy analysis suggests that hydrophobic and hydrophilic regions were evenly distributed along the sequence, but the NH₂- and COOH-termini were hydrophobic. Hydrophobic moments and Fourier-transform amphipathic analyses further suggest that residues 23–30 and 83–93 were amphiphathie -sheets. The overall conformation of OBCAM was unaltered by adding linoleic acid, which is required for opioid ligand binding.     

左旋四氢巴马汀加强电针对兔大脑皮层牙髓诱发电位的...

Cortical potentials evoked by stimulation of the contralateral tooth-pulp were recorded epidurally from the SI cortex of rabbits anesthetized with urethane and chloralose. It was found that nociceptive components of the evoked potential consisted of P1 and P2 wavelets with a relative stable peak latency of 22.5 +/- 1.2 ms and 66.1 +/- 1.9 ms respectively. Higher intensity of tooth pulp stimulation was required for appearance of P2 than P1. Diazepam, a non-analgesic sedative, reduced P1 but not P2 amplitude. On the contrary, dolantin, an analgesic, suppressed P2 but showed no significant influence on P1. The results suggest that P2, but not P1 might be related to pain. The effects of l-tetrahydropalmatine (1-THP) and electroacupuncture on P2 were observed on 12 animals. The results showed that both iv l-THP 8mg/kg and electroacupuncture brought forth a decrease in P2 amplitude by 40.3 +/- 14% and 59.3 +/- 10% respectively, while electroacupuncture combined with l-THP produce a further decrease in P2 amplitude by 92.8 +/- 7%. Furthermore, the inhibitory periods of P2 amplitude were significantly prolonged after electroacupuncture combined with l-THP. The results indicated that l-THP enhanced the suppression of P2 by electroacupuncture.     

烟青虫人工饲料的研究

本文报道烟青虫Heliothis assulta的一种人工饲料,其主要成分是麦胚、酵母粉、番茄酱和辣椒粉.与自然食料相比,用这种人工饲料饲养的烟青虫生长快、发育整齐、存活率高,得到的蛹大,成虫繁殖力强.饲料中含0.1—0.2%的NaCI对幼虫的生长发育有促进作用.6龄幼虫对该饲料中干物质、能量和氮的同化效率分别是38.5%、43.9%和48.5%.在连续12代饲养期间,幼虫期存活率在57—92%之间,平均76%.     

A refined linkage map for DNA markers around the pericentromeric region of chromosome 10

A refined genetic linkage map for the pericentromeric region of human chromosome 10 has been constructed from data on 12 distinct polymorphic DNA loci as well as the locus for multiple endocrine neoplasia type 2A (MEN 2A), a dominantly inherited cancer syndrome. The map extends from D10S24 (at 10p13-p12.2) to D10S3 (at 10q21-q23) and is about 70 cM long. Overall, higher female than male recombination frequencies were observed for this region, with the most remarkable female excess in the immediate vicinity of the centromere, as previously reported. Most of the DNA markers in this map are highly informative for linkage and the majority of the interlocus intervals are no more than 6 cM apart. Thus this map should provide a fine framework for future efforts in more detailed mapping studies around the centromeric area. A set of ordered cross-overs identified in this work is a valuable resource for rapidly and accurately localizing new DNA clones isolated from the pericentromeric region.     

Hormonal regulation of gonadotropin-releasing hormone receptors and messenger RNA activity in ovine pituitary culture

Previous studies demonstrate that gonadotroph responsiveness to GnRH, GnRH binding, and the apparent number of GnRH receptors are all increased by 17 beta-estradiol (E) or inhibin (IN) in ovine pituitary cultures. Progesterone (P) attenuates these effects. To explore differences between the effects of IN and E on GnRH binding, a detailed time-course study was performed. The results indicate that after 48 h, IN had a greater effect on binding of a GnRH agonist (5-fold increase) than E (3-fold increase), but was slower to act initially. A combined treatment of IN and E gave a partially additive effect at 48 h (6.5-fold increase). The mechanism of receptor regulation in this system is not known, but could involve synthesis, recycling, or modification of GnRH receptors. To investigate the contribution of altered receptor biosynthesis to the regulation of receptor levels, a functional Xenopus oocyte-based assay for GnRH receptor mRNA activity was employed. After 48 h of treatment, IN or E each led to a 7- to 8-fold increase in GnRH receptor mRNA activity. Treatment with both hormones led to a 19-fold increase. The increase in mRNA activity induced by either hormone was greatly attenuated by P. Modulation of GnRH receptor mRNA levels suggests that IN, E, and P regulate responsiveness to GnRH in the ovine pituitary at least in part by altering de novo synthesis of GnRH receptors. The differing time courses of action, as assayed by GnRH binding, and the additivity of effects at the mRNA level suggest that IN and E alter mRNA levels via different mechanisms.