Cloning and characterization of a tandemly repeated DNA sequence in the crane family (Gruidae)

A tandemly repeated DNA sequence possessing a unique PstI site has been characterized in several species of the crane family. The "Pst family" comprises at least 8800 monomer units 187 base pairs (bp) in length and constitutes 0.14% of the genome of the sarus crane (Grus antigone). The array is located in the centromeric heterochromatin of chromosome 2 in the two species where in situ hybridizations of a cloned monomer to metaphase chromosome spreads were carried out. DNA sequence comparisons between five monomer units from G. antigone revealed a high degree of homology between four of the individual repeats, while the fifth was somewhat divergent. The G + C content deduced from the DNA sequence makes it likely that the Pst family constitutes part of a density satellite seen in profiles of crane DNA centrifuged to equilibrium in CsCl. The common occurrence of tandem arrays such as the Pst family, with repeat lengths close to 200 bp, leads us to an hypothesis implicating nucleosomes in the evolution of such families.     

The viral envelope gene is involved in macrophage tropism of a human immunodeficiency virus type 1 strain isolated from brain tissue.

Human immunodeficiency virus type 1 (HIV-1) strains isolated from the central nervous system (CNS) may represent a subgroup that displays a host cell tropism different from those isolated from peripheral blood and lymph nodes. One CNS-derived isolate, HIV-1SF128A, which can be propagated efficiently in primary macrophage culture but not in any T-cell lines, was molecularly cloned and characterized. Recombinant viruses between HIV-1SF128A and the peripheral blood isolate HIV-1SF2 were generated in order to map the viral gene(s) responsible for the macrophage tropism. The env gene sequences of the two isolates are about 91.1% homologous, with variations scattered mainly in the hypervariable regions of gp120. Recombinant viruses that have acquired the HIV-1SF128A env gene display HIV-1SF128A tropism for macrophages. Furthermore, the gp120 variable domains, V1, V2, V4, and V5, the CD4-binding domain, and the gp41 fusion domain are not directly involved in determining macrophage tropism.     

Otolith microstructure indicating growth and mortality among plaice, Pleuronectes platessa L., post-larval sub-cohorts

Growth and mortality of post-metamorphosed plaice were studied by means of daily increments in the sagittal otoliths. The Gompertz model was the best fit to length-at-age data and there were no significant differences between length-at-age and back-calculated lengths. The microstructure pattern of the otoliths at metamorphosis was also used to estimate hatching and settlement distributions. Differential growth and mortality occurred among sub-cohorts; growth rates and mortality were higher in fish that settled earlier. In 1986, the best survival was for a sub-cohort settling in late May to early June. In contrast, in the warmer season of 1987, survival was highest for the second and third sub-cohorts settling in late April and mid May.     

The Epstein-Barr virus (EBV) BZLF1 immediate-early gene product differentially affects latent versus productive EBV promoters.

The Epstein-Barr virus (EBV) BZLF1 gene product is thought to mediate the disruption of latent EBV infection. We have examined the regulatory effects of BZLF1 by studying its transactivating effects on seven different EBV promoters. We find that whereas the BZLF1 gene product increases the activity of the two early promoters, BMLF1 and BMRF1, it decreases the activity of three latent promoters (the BamHI-C and BamHI-W Epstein-Barr nuclear antigen promoters and the latent membrane protein promoter). The BZLF1-induced changes in promoter-directed chloramphenicol acetyltransferase activity occur in EBV-negative as well as EBV-positive cell lines and are accompanied by a similar change in chloramphenicol acetyltransferase mRNA. Deletion analysis of the BamHI Z fragment indicates that in a portion of the amino-terminal half of the BZLF1 gene product (amino acids 24 to 86) is not essential for positive transactivating effects but is required for down-regulating effects. Thus, different domains of the same EBV immediate-early gene product can either increase the function of EBV promoters active in productive infection or decrease the function of key promoters active in latent infection.     

On the sensitivity of intact cells to perturbation by ethanol

A comparison was made of ethanol's effects on the order of plasma membranes in intact cells and some isolated membrane preparations. Order was assessed by steady-state fluorescence polarization techniques using the non-permeant probe, TMA-DPH. The data show that two cultured cells, rat neonatal astroglial and N2A neuroblastoma, were sensitive to significant ethanol-induced disordering within the anesthetically relevant range (100 - 200 mM). Human erythrocytes, cultured fibroblasts and homogenized astroglial cells required higher ethanol concentrations (greater than 250 mM) to produce a similar effect. Intact erythrocytes were approximately twice as sensitive as erythrocyte ghost membranes to ethanol-induced perturbation. The neonatal glial and N2A cells were approximately five times more sensitive than synaptic membranes to ethanol effects. DMPC and DMPC + cholesterol liposomes and myelin membranes were insensitive to ethanol's effects. The incorporation of 10 mole % ganglioside GM1 sensitized the liposomes to ethanol-induced perturbation.     

Nucleotide sequence of cDNA for Acacia confusa trypsin inhibitor and implication of post-translation processing.

Synthetic oligonucleotides corresponding to all possible sequences of N-terminal and C-terminal region of Acacia confusa trypsin inhibitor were used to generate ACTI-related sequences using the polymerase chain reaction on the cDNAs encoding ACTI of the seeds of legume, A. confusa. The deduced amino acid sequence agreed with that determined by the peptide analysis except an extra amino acid residue, serine, was found at the junction of A and B chain, which was removed by post-translation processing with specific protease(s). The substrate specificity of the protease(s) was found to cleave at the C-terminal sites of asparagine and serine, which was also shown to be the same case for another plant protein, abrin, isolated from legume, Abrus precatorius.     

Deletion of C-terminal 12 amino acids of GLUT1 protein does not abolish the transport activity.

We engineered the GLUT1 cDNA to delete C-terminal 12 amino acids of encoded GLUT1 protein. This mutated GLUT1 protein expressed in CHO cells by transfection of its cDNA was demonstrated to reside on the plasma membrane by cell surface labeling technique, and retain the transport activity, similar to that of the wild-type GLUT1. In addition, metabolic labeling of the intact cells with 35S indicated that the half-life of the mutated GLUT1 was not significantly different from that of the wild-type GLUT1. These results suggest that C-terminal 12 amino acids of GLUT1 are not important for the transport activity and the stability of the protein. Taken together with our previous results on the mutant without C-terminal 37 amino acids, the amino acids between the 37th and the 13th from the C-terminus appear to be essential for the transport activity.     

黑龙江桔梗科叶表皮研究

本文对分布在黑龙江省的桔梗料(Campanulaceae)植物叶表皮进行了光学显微镜和扫描电镜方面的观察。发现桔梗科植物的气孔复合体是不规则型的;毛状体是单细胞的,其表面的角质纹饰因类群而异;表皮角质纹饰可用于某些种间的鉴别。