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21.
We describe the characterization of tandemly repeated DNA sequences, which resemble the satellite DNA sequences of multicellular eucaryotes, in the unicellular green alga Chlamydomonas reinhardtii. Restriction enzymes that cleave C. reinhardtii DNA relatively frequently produce a number of high molecular weight DNA fragments in addition to the bulk of low molecular weight DNA fragments. pTANC 1.5 contains a 1.5 kb Sau3A fragment cloned from one of these large bands. pTANC 1.5 hybridized to at least three large arrays (200 to 700 kb) of tandemly repeated DNA sequences in the cell-wall-deficient strain cw1.5. These arrays are composed of repeat units that are each cleaved once by BamHl into bands of 1.5, 1.9, 2.0 and 2.5 kb in size. The copy numbers of the 1.5, 1.9, 2.0 and 2.5 kb Bamhl bands vary between different C. reinhardtii strains. Chlamydomonas smithii and a number of C. reinhardtii strains are deficient in all four BamHl bands. Genetic analysis of wild-type strain 137c, which is deficient in the 2.0 kb BamHl band, indicates that the 1.5, 1.9 and 2.5 kb BamHl bands derive from at least five loci. The 1.5, 1.9 and 2.5 kb repeat units are not extensively interspersed with each other in strain 137c. Pulsed-field gel electrophoresis of intact C. reinhardtii chromosomes indicates that TANC arrays are present on more than one chromosome. 相似文献
22.
Suman Mishra Nidhi Kundu Ishika Pramanick Anil Kumar Kausik Chattopadhyay Somnath Dutta 《Proteins》2023,91(2):137-146
Thermostable direct hemolysin (TDH) is a ~19 kDa, hemolytic pore-forming toxin from the gram-negative marine bacterium Vibrio parahaemolyticus, one of the causative agents of seafood-borne acute gastroenteritis and septicemia. Previous studies have established that TDH exists as a tetrameric assembly in physiological state; however, there is limited knowledge regarding the molecular arrangement of its disordered N-terminal region (NTR)—the absence of which has been shown to compromise TDH's hemolytic and cytotoxic abilities. In our current study, we have employed single-particle cryo-electron microscopy to resolve the solution-state structures of wild-type TDH and a TDH construct with deletion of the NTR (NTD), in order to investigate structural aspects of NTR on the overall tetrameric architecture. We observed that both TDH and NTD electron density maps, resolved at global resolutions of 4.5 and 4.2 Å, respectively, showed good correlation in their respective oligomeric architecture. Additionally, we were able to locate extra densities near the pore opening of TDH which might correspond to the disordered NTR. Surprisingly, under cryogenic conditions, we were also able to observe novel supramolecular assemblies of TDH tetramers, which we were able to resolve to 4.3 Å. We further investigated the tetrameric and inter-tetrameric interaction interfaces to elaborate upon the key residues involved in both TDH tetramers and TDH super assemblies. Our current structural study will aid in understanding the mechanistic aspects of this pore-forming toxin and the role of its disordered NTR in membrane interaction. 相似文献
23.
Anil Amaratunga †Susan E. Leeman ‡Kenneth S. Kosik § Richard E. Fine 《Journal of neurochemistry》1995,64(5):2374-2376
Abstract: We have previously demonstrated that the in vivo vitreal injection of an antisense oligonucleotide directed to the kinesin heavy chain inhibits retinal kinesin synthesis by 82% and concomitantly inhibits rapid transport of total protein into the optic nerve by 70%. These results establish a major role for kinesin in rapid axonal transport in vivo. Recently, the cloning of a family of kinesin-like molecules from the mammalian brain has been reported, and some of these proteins are also expressed in neurons. To assign a specific function to the kinesin heavy chain we inhibited the kinesin synthesis with an antisense kinesin oligonucleotide and assessed the axonal transport into the optic nerve of representative proteins from each of three vesicle classes that contain rapidly transported proteins. Marker proteins used were substance P for peptide-containing synaptic vesicles, the amyloid precursor protein for plasma membrane precursor vesicles, and several integral synaptic vesicle proteins. Our results indicate that the major anterograde motor protein for all three vesicle classes utilizes kinesin heavy chain, although we discuss alternative explanations. 相似文献
24.
Rice seedlings accumulate stainable amounts of the 104 and 90 kDa polypeptides in response to high temperature stress. We have purified and raised highly specific polyclonal antisera against both of these polypeptides. In western blotting experiments, we find that these proteins are accumulated to different extents in rice seedlings subjected to salinity (NaCl), water stress, low-temperature stress and exogenous abscisic acid application. These proteins also accumulated when rice seedlings grown in pots under natural conditions were subjected to water stress by withholding watering. Seedlings of Triticum aestivum, Sorghum bicolor, Pisum sativum, Zea mays, Brassica juncea and mycelium of Neurospora crassa showed accumulation of the immunological homologues of both the 104 and the 90 kDa polypeptides, in response to high-temperature stress. We have earlier shown that shoots of rice seedlings exposed to heat shock accumulate a 110 kDa polypeptide which is an immunological homologue of the yeast HSP 104 (Singla and Grover, Plant Mol Biol 22: 1177–1180, 1993). Employing anti-rice HSP 104 antibodies and anti-yeast HSP 104 antibodies together, we provide evidence that rice HSP 104 is different from the earlier characterized rice HSP 110. 相似文献
25.
Anil Chatterji Z. A. Ansari J. K. Mishra Parveen Rattan A. H. Parulekar 《Hydrobiologia》1995,310(2):157-161
The occurrence of Diaphanosoma excisum (Sars), a freshwater cladoceran, in benthic samples of an intertidal sandy beach is reported. Population density was seasonal. A relatively high density was recorded from June to September (south-west monsoon season) with a maximum (46 ind 10 cm–2) in September at a depth of 10–15 cm of sediment. A sudden decline occurred during north-east monsoon (October to January), and in the fair season (February to May), the cladocerans disappeared. Mean density varied (P<0.001) with sediment depth and season and showed a contagious dispersion. Abundance was negatively correlated with salinity (r = –0.76) but positively with POC (r =0.79) and mean grain size of the sediment (r = 0.93). The density of D. excisum was highest in fine sand. 相似文献
26.
Mycelium of Fusarium oxysporum grown on a glucose-containing medium lacked fructosyl transferase and invertase activities. Synthesis of fructosyl t 相似文献
27.
Wayne K. Hoffman Peter Lalley Jean Deb Butler Sheldon Orloff Joseph D. Schulman Anil B. Mukherjee 《In vitro cellular & developmental biology. Plant》1981,17(8):735-740
Summary Using lipochromosomes (phospholipid-entrapped chromosomes) we have transferred the human HGPRT gene into HGPRT deficient mouse
cells (A9) with a frequency of approximately 1×10−5 (Mukherjee et al., Proc. Natl. Acad. Sci. USA 75: 1361–1365; 1978). Two other genes located on the long arm of the human
X-chromosome were also expressed in two independently derived populations of transferents (A9/GT3 and A9/GT4). We report here
the chromosomal and enzymatic composition of human HGPRT-positive clones from each subpopulation analyzed in detail with alkaline
Giemsa-11 staining.
All the clones expressed human PGK and HGPRT, but one (A9/GT4C6) lacked human G6PD. In each of four clones examined microscopically,
a small piece of presumptive human chromatin was visible in the karyotypes of most cells. The chromatin fragment was free
or attached in each cell of an individual clone. When integrated, the human chromosomal fragment in each clone appeared associated
with the centromere of the same telocentric A9 chromosome (No. 6 by Q-banding).
These data suggest that: (a) substantial human chromosomal fragments can be transferred into recipient cells using the lipochromosome
technique; (b) clones from human HGPRT positive A9 transferent subpopulations may or may not possess other human X-linked
markers; (c) the stability of lipochromosomally transferred genes varied from clone to clone and stability is generally poor
in the absence of continuous selection pressure (e.g., HAT); (d) when multiple X-linked human genes were transferred to mouse
cells a cytologically detectable human chromosomal fragment was identified free or attached to a host chromosome; and (e)
integration of transferred human chromosomal material into mouse chromosomes may occur at preferential site(s) in the recipient
genome.
This research was sponsored in part by the Office of Health and Environmental Research U.S. Department of Energy under Contract
W-7405-eng-26 with the Union Carbide Corporation. 相似文献
28.
K Anil R Abraham G S Kumar P R Sudhakaran P A Kurup 《Indian journal of experimental biology》1992,30(6):518-522
The effect of feeding fish oil on the metabolism of lipoproteins was studied in rats. Rats were fed diet containing 10% sardine or groundnut oil for 6 weeks. There was a significant decrease in the total cholesterol, phospholipids and triglycerides as well as the amount of the lipids associated with VLDL and LDL in serum in fish oil-fed rats. The synthesis and secretion of lipoproteins particularly apoB containing lipoproteins by primary cultures of hepatocytes from these rats were studied by 14(C)-acetate or 3(H)-leucine labelling. Primary cultures of hepatocytes derived from sardine oil-fed rats showed reduced incorporation of 3(H)-leucine into apoB containing lipoproteins secreted into the medium when compared to those fed groundnut oil, indicating a decreased synthesis and secretion of apoB. This was further confirmed by significantly lower incorporation of 14(C)-radioactivity into total and individual lipids of VLDL secreted into the medium, as well as that associated with different lipids in cell layer. The activity of lipoprotein lipase in adipose tissue and aorta was significantly higher in rats fed sardine oil which may cause an increased clearance of triglyceride-rich lipoproteins from circulation. These results indicate that the fish oil exerts hypolipidemic effect particularly by decreasing the synthesis and secretion of VLDL by liver and possibly by an increased clearance of triglyceride-rich lipoproteins from circulation. 相似文献
29.
Cystinotic and normal fibroblasts: Differential susceptibility to cysteine toxicity in vitro 总被引:2,自引:0,他引:2
Sheldon Orloff Anil B. Mukherjee Jean DeB Butler Barbara Foley Joseph D. Schulman 《In vitro cellular & developmental biology. Plant》1980,16(8):655-660
Summary Extracellular cysteine concentrations between 0.5 and 2.5 mM resulted in death of normal but not cystinotic cells grown in Eagle's minimal essential medium containing supplemental fetal
bovine serum and antibiotics. Differential cell survival was determined by viable cell counting using Trypan Blue dye exclusion.
In cocultivation experiments of [3H]thymidine-labelled cystinotic fibroblasts with nonradioactive normal fibroblasts, autoradiography confirmed the selective
survival of cystinotic cells in medium containing 1 mM cysteine. At this concentration of 1 mM cysteine, intracellular cystine content increased slightly in surviving normal cells but not in cystinotic cells, which normally
contain a high level of intracellular cystine. This comparative resistance of cystinotic fibroblasts to elevated extracellular
cysteine concentrations forms the basis for an in vitro selective system for these mutant human cells. Further exploration
of this resistance phenomenon may well expand the understanding of the molecular defect in cystinotic cells. 相似文献
30.