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。     

Specific interactions of histone H1 and a 45 kilodalton nuclear protein with a putative matrix attachment site in the distal promoter region of a cell cycle-regulated human histone gene

Protein-DNA interactions within the promoter of a cell cycle-regulated human H4 histone gene were examined by binding of 5'-end-labeled DNA segments to Western blots of nuclear protein fractions. Specific protein interactions were observed with DNA segments located between -500 bp and -1,070 bp upstream of the ATG initiation codon and included a histone H1 binding segment flanked on both sides by binding sites for a 45 kD nuclear protein. This region of the gene contains a DNase I-sensitive site in the center (-720 to -820 bp), and sequence analysis revealed the presence of scaffold attachment sequences in the two flanking segments. Topoisomerase II consensus sequences and in vitro topoisomerase II cleavage sites were also detected in the two flanking segments. Our results suggest that the 45 kd nuclear protein may preferentially interact with these two segments of the H4 histone gene to mediate association with the nuclear matrix. The presence of negative regulatory elements in this putative matrix attachment region provides a basis for the speculation that such nuclear proteins are associated with alterations in gene-matrix interaction that are functionally related to gene expression.     

Tolerance to diazepam and methyl-beta-carboline-3-carboxylate measured in substantia nigra of benzodiazepine tolerant rats

The spontaneous activity of neurons in the pars reticulata of substantia nigra (SNpr) was studied in chloral hydrate anesthetized rats. As a function of dose, intravenous diazepam decreased, and methyl-beta-carboline-3-carboxylate (beta CCM) increased discharge frequency. Two days after terminating a one week treatment with flurazepam (FZP), both diazepam and beta CCM showed decreased ability to alter SNpr neuronal activity. Neither residual FZP nor down-regulation of benzodiazepine receptors can account for these results. In contrast, behavioral testing revealed no change in the ability of i.v. beta CCM to cause convulsions, suggesting that sites other than the SNpr are of prime importance in expressing the convulsant actions of systemically injected beta CCM.     

Photoaffinity labeling of [3H]flunitrazepam- and [3H]Ro15-4513-bound pellets in rat cerebral cortex and cerebellum

Irreversible incorporation of [3H]flunitrazepam and [3H]Ro15-4513 into GABA/benzodiazepine receptor subunits was studied by UV irradiation using ligand-bound membrane pellets from rat cerebral cortical and cerebellar synaptic membranes. Specific incorporation for [3H]flunitrazepam was greater in the pellet than in the suspension. The incorporation was identical for [3H]Ro15-4513 in both pellet and suspension. With the ligand-bound pellets, 50% of the available binding sites were photolabeled by both ligands in cortex and cerebellum. SDS polyacrylamide gel electrophoresis and fluorography of [3H]flunitrazepam photo-labeled receptor revealed the same number of major sites in both brain regions. In contrast, [3H]Ro15-4513 appears to label fewer sites in cortex and cerebellum. Photoaffinity labeling with [3H]flunitrazepam in ligand-bound membrane pellet provides a more selective and reliable method for studying the subunit structure of GABA/benzodiazepine receptor complex.     

睾丸间质细胞—研究自体吞噬的一种正常细胞模型

In the present study, we tried to estimate, in a semiquantitative way, the relative frequency of the autophagic activity in various cell types under physiological condition. The results indicated that the highest activity appeared to be in the Leydig cells of rat testes. Autophagosomes were frequently observed in electron microscope photographs of Leydig cells, which provide a good model to study the autophagocytosis in normal cells. The autophagic process in Leydig cells was observed with the electron microscope in preparations treated to show CMPase activity. The mode of formation of autophagosomes in Leydig cells can be divided into three steps. Step 1, flattened membranous elements expand to enclose a small cytoplasmic territory to form pre-autophagosome. Step 2, The double membrane profile of the pre-autophagosome then completely encloses the cytoplasmic territory to form early autophagosome in which structurally normal organelles are contained. Step 3, the transformation of an early autophagosome into a late one is accompanied by the loss of one of the two delimiting membranes, the partial disintegration of the enclosed content and simultaneous acquisition of acid phosphatase activity. The enzymatic reactivity is acquired following a close association with the lysosomes. The late autophagosome then reaches the cell surface and appear to exocytose their residual content.     

β-II conformation of all-β proteins can be distinguished from unordered form by circular dichroism

The CD spectrum of certain all-β globular proteins resembles that of unfolded proteins with a characteristic negative band around 200 nm. The conformation of this class is tentatively termed β-II, which had two features that were absent for unfolded proteins. First, β-II proteins usually had CD bands due to aromatic side groups in the near-ultraviolet region. Second, the CD intensities both in the far- and in the near-uv region of these compact and rigid proteins usually showed a sharp transition upon thermal denaturation, whereas those of an unordered form changed linearly with rising temperature.     

A procedure for the construction of linear restriction fragment maps of a 50- to 100-kb DNA.

A simple and effective procedure for the construction of linear restriction fragment maps was developed. Using a two-enzyme digestion, two-dimensional (2-D) electrophoresis procedure, all the restriction fragments in a 50- to 100-kb DNA can be individually resolved and displayed on a 2-D plane. This 2-D gel pattern, with appropriate markers, provides a fixed set of x, y coordinates for each fragment obtained from the single and double digestion as well as the relationship between the two steps. A matrix is constructed from the 2-D pattern. The vertical column shows all the singly digested individual fragments and their sizes obtained from each restriction enzyme treatment, and the dividing horizontal row shows all the doubly digested DNA fragments and their sizes after treatment with two enzymes. The order of arrangement is always from the smallest to the largest fragments. Using this matrix, two linear DNA restriction maps for these two enzymes can be simultaneously constructed in a self-reconfirming manner. As examples for this procedure, we describe the construction of two linear restriction fragment maps, a combination of EcoRI and BamHI digestion as well as a combination of EcoRI and HindIII digestion of lambda-phage DNA.     

Hepatitis B virus DNA integration and expression of an erb B-like gene in human hepatocellular carcinoma.

Southern blot studies on Hepatitis B Virus (HBV) DNA integration in 13 human hepatocellular carcinomas (HCCs) patients revealed the presence of several distinct HBV integration sites in different human liver disease patients. In one HCC patient the DNA fragment containing the HBV integration also hybridized to an erb B probe. The erb B/HBV co-migrating DNA fragment was cloned and sequenced, and showed that HBV DNA is integrated next to a cellular DNA fragment which is homologous to the tyrosine protein kinase domain of the human epidermal growth factor receptor gene and other cell surface receptor genes. The virus-integrated cellular DNA sequence is expressed in this HCC patient, suggesting a possible role for this gene in hepatocarcinogenesis.