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Models for the spatial distribution of protein, lipid and water in gap junction structures have been constructed from the results of the analysis of X-ray diffraction data described here and the electron microscope and chemical data presented in the preceding paper (Caspar, D. L. D., D. A. Goodenough, L. Makowski, and W.C. Phillips. 1977. 74:605-628). The continuous intensity distribution on the meridian of the X-ray diffraction pattern was measured, and corrected for the effects of the partially ordered stacking and partial orientation of the junctions in the X-ray specimens. The electron density distribution in the direction perpendicular to the plane of the junction was calculated from the meridional intensity data. Determination of the interference function for the stacking of the junctions improved the accuracy of the electron density profile. The pair-correlation function, which provides information about the packing of junctions in the specimen, was calculated from the interference function. The intensities of the hexagonal lattice reflections on the equator of the X-ray pattern were used in coordination with the electron microscope data to calculate to the two-dimensional electron density projection onto the plane of the membrane. Differences in the structure of the connexons as seen in the meridional profile and equatorial projections were shown to be correlated to changes in lattice constant. The parts of the junction structure which are variable have been distinguished from the invariant parts by comparison of the X-ray data from different specimens. The combination of these results with electron microscope and chemical data provides low resolution three- dimensional representations of the structures of gap junctions. 相似文献
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Jesudason EP Masilamoni JG Ashok BS Baben B Arul V Jesudoss KS Jebaraj WC Dhandayuthapani S Vignesh S Jayakumar R 《Molecular and cellular biochemistry》2008,311(1-2):145-156
Aβ amyloid peptide is believed to induce oxidative stress leading to inflammation, which is postulated to play a significant
role in the toxicity of Alzheimer’s disease (AD). This study was designed to investigate the inhibitory effects of dl-α lipoic acid (LA), a potential free radical scavenger, on oxidative vulnerability induced by intraperitoneal injection of
Aβ25–35 amyloid fibrils in mice. Mice were divided into three groups: control, Aβ amyloid toxicity induced (AT), and LA treated (ATL).
Blood Plasma was separated, liver, spleen and brain were dissected and analysis of oxidants, antioxidants, ATPases, glial
fibrillary acidic protein (GFAP) and nuclear factor kappa-B (NFκB) were carried out. Results show biochemical parameters such
as reactive oxygen species (ROS) and lipid peroxidation (LPO) were significantly lowered (P < 0.05) and levels of antioxidants and ATPase (P < 0.05) were significantly increased (P < 0.05) in hepatocytes, splenocytes and astrocytes of the ATL group. Moreover, our histological results revealed a decreased
GFAP immunoreactivity in the neocortical region and NFκB immunoreactivity in neocortex, liver and spleen. This study reiterates
LA as a potent free radical scavenger to combat oxidative vulnerability in the treatment for Aβ amyloid toxicity. 相似文献
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The role of nitric oxide in cancer 总被引:4,自引:0,他引:4
WEIMING XU Li ZHI LIU MARILENA LOIZIDOU MOHAMED AHMED IAN G CHARLES Wolfson Institute for Biomedical Research Cruciform Building Gower Street UCL London WC E AUUK Department of Surgery Charles Bell House - Riding House Street UCL London WW EJ UK 《Cell research》2002,(Z2)
Nitric oxide (NO) is a pleiotropic regulator, critical to numerous biological processes, including va-sodilatation, neurotransmission and macrophage-mediated immunity. The family of nitric oxide synthases (NOS) comprises inducible NOS (iNOS), endothelial NOS (eNOS), and neuronal NOS (nNOS). Interestingly, various studies have shown that all three isoforms can be involved in promoting or inhibiting the etiology of cancer. NOS activity has been detected in tumour cells of various histogenetic origins and has been associated with tumour grade, proliferation rate and expression of important signaling components associated with cancer development such as the oestrogen receptor. It appears that high levels of NOS expression (for example, generated by activated macrophages) may be cytostatic or cytotoxic for tumor cells, whereas low level activity can have the opposite effect and promote tumour growth. Paradoxically therefore, NO (and related reactive nitrogen species) may have both genotoxic and angiogenic pro 相似文献
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Paired sequence difference in ribosomal RNAs: evolutionary and phylogenetic implications 总被引:12,自引:1,他引:11
Ribosomal RNAs have secondary structures that are maintained by internal
Watson-Crick pairing. Through analysis of chordate, arthropod, and plant 5S
ribosomal RNA sequences, we show that Darwinian selection operates on these
nucleotide sequences to maintain functionally important secondary
structure. Insect phylogenies based on nucleotide positions involved in
pairing and the production of secondary structure are incongruent with
those constructed on the basis of positions that are not. Furthermore,
phylogeny reconstruction using these nonpairing bases is concordant with
other, morphological data.
相似文献
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Mitochondrial gene order is not conserved in arthropods: prostriate and metastriate tick mitochondrial genomes 总被引:25,自引:15,他引:10
The entire mitochondrial genome was sequenced in a prostriate tick, Ixodes
hexagonus, and a metastriate tick, Rhipicephalus sanguineus. Both genomes
encode 22 tRNAs, 13 proteins, and two ribosomal RNAs. Prostriate ticks are
basal members of Ixodidae and have the same gene order as Limulus
polyphemus. In contrast, in R. sanguineus, a block of genes encoding NADH
dehydrogenase subunit 1 (ND1), tRNA(Leu)(UUR), tRNA(Leu)(CUN), 16S rDNA,
tRNA(Val), 12S rDNA, the control region, and the tRNA(Ile) and tRNA(Gln)
have translocated to a position between the tRNA(Glu) and tRNA(Phe) genes.
The tRNA(Cys) gene has translocated between the control region and the
tRNA(Met) gene, and the tRNA(Leu)(CUN) gene has translocated between the
tRNA(Ser)(UCN) gene and the control region. Furthermore, the control region
is duplicated, and both copies undergo concerted evolution. Primers that
flank these rearrangements confirm that this gene order is conserved in all
metastriate ticks examined. Correspondence analysis of amino acid and codon
use in the two ticks and in nine other arthropod mitochondrial genomes
indicate a strong bias in R. sanguineus towards amino acids encoded by
AT-rich codons.
相似文献
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R. G. Hemalatha S. Jebaraj J. A. J. Raja T. Raguchander A. Ramanathan R. Samiyappan P. Balasubramanian 《Journal of plant biochemistry and biotechnology.》1999,8(2):75-80
This study was undertaken to explore the possibilities of using in vitro techniques for selection of sheath rot-resistant soma clones of rice cv Co43. Oryza nivara and O. longistaminata possessing sheath rot-resistance were included in the study, with a view to comparing the reaction of the susceptible somaclones of O. Sativa cv Co43 to a crude toxin preparation from culture filtrate of the pathogenic fungus, Sarocladium oryzae. A few somaclones of Co43, selecfed on the crude toxin preparation, regenerated into plantlets and their reaction to the toxin was reconfirmed up to R1 generation. 相似文献
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J. Gunasingh Masilamoni E. Philip Jesudason S. Dhandayuthapani Ben S. Ashok S. Vignesh W. Charles E. Jebaraj 《Free radical research》2013,47(7):661-673
Widespread cerebral deposition of a 40–42 amino acid peptide called amyloid β peptide (Aβ) in the form of amyloid fibrils is one of the most prominent neuropathologic features of Alzheimer's disease (AD). The clinical study provides evidence that accumulation of protofibrils due to the Arctic mutation (E22G) causes early AD onset. Melatonin showed beneficial effects in an AD mouse model. Mice were divided into four different groups (n=8 per group): (i) control group, (ii) scrambled Aβ-injected group, (iii) Aβ protofibril-injected group and (iv) melatonin-treated group. A single dose of (5 µg) Aβ protofibril was administered to the Aβ protofibril-injected and melatonin-treated groups via intracerebroventricular injections. The results demonstrate that melatonin treatment significantly reduces Aβ protofibril-induced reactive oxygen species (ROS) production, intracellular calcium levels and acetylcholinesterase activity in the neocortex and hippocampus regions. Based on these findings it is suggested that melatonin therapy might be a useful treatment for AD patients. 相似文献
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Jesudason EP Masilamoni JG Jebaraj CE Paul SF Jayakumar R 《Molecular and cellular biochemistry》2008,313(1-2):113-123
Inflammation can activate macrophages or monocytes and sequentially release several inflammatory cytokines and reactive oxygen species (ROS). Oxidative stress-induced acute inflammatory response plays an important role in several diseases. This study was designed to investigate the prophylactic effect of the antioxidant lipoic acid (LA) during inflammation-induced mice. Mice were divided in to three groups (n = 8 in each): control, systemic inflammation, and LA treated mice with systemic inflammation. Results show that ROS was significantly higher in lymphocytes, hepatocytes, and astrocytes (P < 0.05) of inflammation induced mice when compared with control but no significant changes were observed in the LA treated group. Increased levels of lipid peroxidation (LPO) and decreased activities of oxidants such as superoxide dismutase (SOD), catalase, glutathione peroxidase, glutathione, and ATPase were observed in the inflammation-induced mice, which returned to near normalcy following LA therapy. In vitro study has shown that LA treatment not only suppresses the increased LPO levels but also inhibits the lipid break down resulting from autoxidation. In addition, increased immunoreactivity of the astrocyte marker glial fibrillary acidic protein (GFAP) was observed in the neocortex region of inflammation-induced mice, whereas nuclear factor kappa B p65 (NFkappaB) immunoreactivity was observed in both the neocortex and liver of the same group which were effectively controlled by LA therapy suggesting that LA can efficiently manage systemic inflammation. 相似文献