Extraembryonic motor activity during the embryogenesis of higher vertebrates

Extraembryonic rhythmic motor activity in higher vertebrates, along with the intrinsic motor activity of the embryo, is important for the normal development of the embryo. This can have different natures in different classes of amniotes (i.e., motor activities of the amnion, yolk sac, and uterus), but these have similar functional importance. This activity changes reproducibly during the process of embryogenesis, providing the optimum conditions for normal embryo development. During embryogenesis, a system for controlling extraembryonic rhythmic motor activity is also formed. There is a trend for the regulation of this activity to become more complex in mammals as compared with birds. Reptiles have received little study from this point of view. In addition to regular changes in extraembryonic rhythmic motor activity during embryogenesis which depend on the developmental stage of the embryo, motor activity can also change in response to changes in a number of environmental factors (for example, temperature and the gas composition of the air). This demonstrates the possible involvement of embryo-associated extraembryonic motor activity in adapting the embryo to changing environmental conditions and maintaining homeostasis for the development of the embryo itself. Translated from Rossiiskii Fiziologicheskii Zhurnal imeni I. M. Sechenova, Vol. 84, No. 10, pp. 961–968, October, 1998.     

Plastid genomes of the Rhodophyta and Chromophyta constitute a distinct lineage which differs from that of the Chlorophyta and have a composite phylogenetic origin,perhaps like that of the Euglenophyta

Summary A phylogenetic tree has been constructed from comparisons of entire 16S rRNA gene sequences from different prokaryotes and from several algal plastids. According to this study, and to previous work on the ribulose-1,5-bisphosphate carboxylase oxygenase (Rubisco) large and small subunit genes, we postulate that: (1) rhodophyte and chromophyte plastid genomes have a common, composite phylogenetic origin which implies at least two different ancestors, a cyanobacterial and a -proteobacterial ancestor; (2) chlorophyte (green algae and land plants) plastids have a cyanobacterial ancestor which probably differs from that of rhodophyte and chromophyte plastids, and in any case constitute a different lineage; (3) euglenophyte plastid genomes also seem to have a composite phylogenetic origin which involves two different lineages.     

鞭毛抗原与细菌的群集运动

群集运动是指在培养基表面某些运动细菌依赖鞭毛的群体迁移行为,涉及繁殖体细胞分化成群集细胞,发生形态、代谢以及蛋白表达等显著变化。菌细胞密度、表面接触和生理学信号均可成为群集运动的刺激因素。群集运动的关键是鞭毛的生物合成,flhDC鞭毛操纵子是支配分化和迁移的细菌调控网络的焦点。     

Inhibition of HIV-1 expression by HIV-2

HIV-1 and HIV-2 are co-endemic in certain geographic areas. HIV-2 is more weakly pathogenic than HIV-1, and progression to AIDS occurs less frequently and over a longer period of time. Recent epidemiologic studies suggest that individuals infected with HIV-2 have a lower risk of HIV-1 infection. Both immune mechanisms and various modes of viral interference have been proposed to account for these results. Our findings, described in this paper, suggest that HIV-2 inhibits HIV-1 replication. To study the molecular interactions between HIV-1 and HIV-2, proviral clones were transfected alone or in combination into the human T cell line CEM. LTR-CAT indicator constructs were included for the purpose of monitoring viral promoter activity. Viral replication in transfected cells was monitored by p24 antigen capture assay of cell culture supernatants and Western blot analysis of cell extracts. HIV-2 inhibited HIV-1 replication as determined by intracellular and extracellular p24 antigen levels. Similar results were obtained with simultaneous virus infection using HIV-1 and HIV-2, rather than transfections of proviral DNA. Using cotransfection of HIV-1 and HIV-2 LTR indicator gene constructs, the mechanism of inhibition was found to be suppression of the HIV-1 LTR by HIV-2. The inhibitory effect of HIV-2 is not due to Tat-2, but appears to discriminate between the HIV-1 and HIV-2 LTRs based on differences in the Tat activation response element, TAR. These results suggest both a molecular mechanism for HIV-2 interference with HIV-1 replication and a potential molecular approach to therapy.     

Genetics of reovirus: the relationship of interference to complementation and reassortment of temperature-sensitive mutants at nonpermissive temperature.

Temperature-sensitive mutants of reovirus type 3 are capable of interfering with the replication of wild-type reovirus type 3. The interfering activity correlated with the ability of pairs of mutants to complement at 39°: Pairs of noninterfering mutants (tsD × tsE) yielded efficient complementation (indexes of 10–50); pairs of interfering mutants (including members of groups ts A, B, G) did not produce significant complementation (indexes ～ 1). The ability of pairs of mutants to reassort at 39° generally followed a similar pattern. Thus interference is an important property of ts mutants of reovirus and needs to be considered when genetic interactions are being studied at 39°.     

Soluble and membrane-bound forms of brain acetylcholinesterase in Alzheimer''s disease

In order to determine the effect of Alzheimer's disease on the relative distribution of soluble and membrane-bound molecular forms of acetylcholinesterase (AChE) in the brain, postmortem samples (delay interval less than 12 h) were obtained from parietal cortex (Brodmann area 40) and hippocampus as well as the areas containing their respective projection nuclei, i.e., substantia innominata and septal nucleus, in 9 patients with Alzheimer's disease (AD) and 4 normal controls. The monomer (G₁), dimer (G₂), and tetramer (G₄) forms of AChE were examined. In AD compared to controls, significant changes occurred in area 40 and hippocampus but not in the areas containing projection nuclei, and included loss of mean total AChE activity, decrease in the relative percentage of membrane-bound G₄, and increase in the relative percentage of soluble G₁---G₂. Percent of soluble G₄ was unaffected in AD brain. In area 40 but not hippocampus a large increase in percent membrane-bound G₁-G₂ occurred. Thus, these results emphasize that the selective decrease in membrane-bound G₄ accounts for the decrease in total G₄ activity in AD brain.     

Quantitative changes in gene expression of glutamate receptor subunits/subtypes in the vestibular nucleus, inferior olive and flocculus before and following unilateral labyrinthectomy in the rat: real-time quantitative PCR method

Spontaneous recovery from the oculomotor and postural symptoms of unilateral labyrinthectomy (UL) is known as vestibular compensation, which is a useful model for investigation of the mechanisms of lesion-induced CNS plasticity. In the present study, to elucidate the molecular biological basis of vestibular compensation, we investigated changes in the mRNA expression of glutamate receptor subunit/subtypes in the rat central vestibular system, including the vestibular nucleus complex (VNC), inferior olive (IO), and cerebellar flocculus following UL, using a real-time quantitative polymerase chain reaction (PCR) method. In normal control animals, regional differences in the expression of several glutamate receptor subunit/subtypes, e.g., NR1 and NR2A subunits of the N-methyl-D-aspartic acid (NMDA) receptor, GluR2 and KA2 subtypes of non-NMDA receptors, and mGluR1 and mGluR7 metabotropic glutamate receptors, were consistent with previous results from studies using in situ hybridization histochemistry, suggesting that the real-time quantitative PCR method was a reliable procedure for evaluation of changes in mRNA expression. In the vestibular nucleus complex, NR2A, GluR2 and mGluR7 mRNA were ipsilaterally downregulated by 6 h following UL (P<0.05, P<0.05 and P<0.01, respectively). In the inferior olive, no changes in gene expression were observed. In the ipsilateral flocculus, KA2 mRNA expression was increased by 50 h post-UL (P<0.05). However, in the contralateral flocculus, mGluR1 mRNA was downregulated by 6 h post-UL (P<0.005). Both the increase in KA2 mRNA expression in the ipsilateral flocculus and the decrease in mGluR1 mRNA expression in the contralateral flocculus may have had the effect of reducing Purkinje cell inhibition of ipsilateral VNC neurons, thereby contributing to the rebalancing of spontaneous resting activity between the ipsilateral and contralateral VNCs. It is suggested that such changes in the activities of the floccular-VNC pathways may be important to the vestibular compensation process. Electronic Publication     

Novel missense mutations in the human lysosomal sialidase gene in sialidosis patients and prediction of structural alterations of mutant enzymes

Three novel missense mutations in the human lysosomal sialidase gene causing amino acid substitutions (P80L, W240R, and P316S) in the coding region were identified in two Japanese sialidosis patients. One patient with a severe, congenital form of type 2 sialidosis was a compound heterozygote for 239C-to-T (P80L) and 718T-to-C (W240R). The other patient with a mild juvenile-onset phenotype (type 1) was a homozygote for the base substitution of 946C-to-T (P316S). None of these mutant cDNA products showed enzymatic activity toward an artificial substrate when coexpressed in galactosialidosis fibroblastic cells together with protective protein/cathepsin A (PPCA). All mutants showed a reticular immunofluorescence distribution when coexpressed with the PPCA gene in COS-1 cells, suggesting that the gene products were retained in the endoplasmic reticulum/Golgi area or rapidly degraded in the lysosomes. Homology modeling of the structural changes introduced by the mutations predicted that the P80L and P316S transversions cause large conformational changes including the active site residues responsible for binding the sialic acid carboxylate group. The W240R substitution was deduced to influence the molecular surface structure of a limited region of the constructed models, which was also influenced by previously identified V217M and G243R transversions. Received: Stptember 21, 2001 / Accepted: November 2, 2001     

Novel mutations, including the second most common in Japan, in the β-hexosaminidase α subunit gene, and a simple screening of Japanese patients with Tay-Sachs disease

Two novel mutations of the β-hexosaminidase α subunit gene were identified in Japanese patients with the infantile form of Tay-Sachs disease. One mutation was a one-base deletion at nt613C, which generated a stop codon at two codons downstream, in three unrelated patients. The other mutation was a one-base substitution of G-to-A at IVS 5, +1, which caused a splicing abnormality, in one patient. A missense mutation of R170W, which has already been reported in other ethnic groups, was also newly identified in one patient. In 1993, the most common mutation (IVS 5, −1G → T) in Japanese patients with Tay-Sachs disease was reported as the major mutation in Japan accounting for 80% of 56 mutant alleles from 28 unrelated patients. The deletion of nt613C was the second most common mutation, accounting for 5% of the mutant alleles. The previously reported mutation IVS 5, −1G → T and the nt613C deletion found in this study together accounted for 85% of the mutations causing Tay-Sachs disease among Japanese. Since these two mutations were located in or close to exon 6 and since they abolish Fok I (IVS 5, −1G → T) and Sfa NI (nt613C deletion) restriction sites, respectively, they were screened rapidly by single polymerase chain reaction followed by digestion with these enzymes. Received: November 10, 1998 / Accepted November 14, 1998     

膀胱抗菌机制—粘膜抗菌蛋白初步研究

本文报道以１％乙酸冲洗雌性Ｗｉｓｔａｒ大鼠膀胱和雌性新西兰白兔膀胱，分别获得其膀胱酸溶性提取物。ＡＵ－ＰＡＧＥ分析表明，两种膀胱粘膜酸溶性提取物都有十余条主蛋白带，而不含常见的杀菌物质溶菌酶和防御素样分子。琼脂糖弥散法杀菌试验显示，两种膀胱粘膜酸溶性提取物对致病性大肠杆菌ＭＬ－３５ｐ耐药株都有杀菌活性。进一步采用电泳凝胶琼脂糖弥散法杀菌试验分析，结果表明大鼠膀胱粘膜酸溶性提取物中有两条蛋白带具明显的杀菌活性，我们称这两条蛋白带为ＲａｔＢＰ－１和ＲａｔＢＰ－２。而兔膀胱粘膜酸溶性提取物的杀菌活性亦与两条被称为ＲａｂＢＰ－１和ＲａｂＢＰ－２的蛋白带相关。本文首次提示，在膀胱粘膜内存在抗菌蛋白，可能是膀胱粘膜杀菌作用的分子基础。