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1.
Kinetics of the change of photosystem (PS) composition in cyanobacteriainduced by chromatic light were studied in relation to cellproliferation. The study was made for two unicellular strains,Synechococcus NIBB 1059 and Synechocystis (Aphanocapsa) PCC6714. We found that (1) the change to a higher or lower PS I/IIratio was due to acceleration or suppression of apparent PSI formation, and (2) it progressed on a similar time scale tothat of the cell proliferation. The apparent rate constant ofthe change in the PS I/II ratio was proportional to that ofcell proliferation, µ, when this was low, but at highvalues of µ the increase in the rate constant of the changein the PS I/II ratio became smaller, causing a deviation fromthe linear relationship. Results indicate that under autotrophicconditions, the photoregulated composition change occurs asa result of thylakoid development, which accompanies cell proliferation. (Received June 23, 1986; Accepted December 5, 1986) 相似文献
2.
The physical properties of the pretransition (P beta'----L beta') of dipalmitoylphosphatidylcholine liposomes were investigated using freeze-fracture electron microscopy. The kinetics of pretransition examined in the previous paper using TEMPO spin probe (Tsuchida, K., et al. (1985) Biochim. Biophys. Acta 812, 249-254) was extensively studied by observing the ripple structures in the freeze-fractured surfaces at different time intervals. When the temperature is decreased from 38 degrees C to 30 degrees C, the ripple structure disappears in the following steps. The intervals between ripples begin to expand with the decrease of ripple density upon the temperature shift, and this process continues for several tens minutes. Then, each ripple disappears gradually and changes into a completely smooth surface at 3 h after the temperature shift. The comparison of relaxation times between the previous ESR measurement and the present experiment suggests that the fast relaxation observed in the previous study corresponds to the expansion of the intervals between ripples. On the other hand, the ripple structure of regular intervals appears rapidly in some places and then spreads over the whole area of fractured surface when the temperature is increased from 23 degrees C to 35 degrees C. The results obtained in this work and the previous ESR work strongly suggest that the formation and disappearance of ripple structure is closely related to the relaxation processes near the pretransition temperature. 相似文献
3.
Southern hydridization analyses of genomic DNAs from various dnaJ mutants of Escherichia coli showed that mutant K7052, which has well characterized dnaK706 and dnaJ705 double mutantions, is a deletion mutant. The deletion is about 8.0 kb long and encompasses the whole of the dnaKdnaJ operon. 相似文献
4.
K Ohki 《Biochemical and biophysical research communications》1989,164(2):850-856
Interaction of melittin with phosphatidylcholine molecules in pure vesicles, binary mixtures and a ternary mixture of dimyristoylphosphatidylcholine IDMPC), dipalmitoylphosphatidylcholine (DPPC) and distearoylphosphatidylcholine (DSPC) was investigated by differential scanning calorimetry. Melittin binds preferentially with DMPC, and results in segregation of DMPC in binary mixtures of DMPC/DPPC and DMPC/DSPC and in a ternary mixture of DMPC/DPPC/DSPC. The results indicate that the hydrophobic part of peptide interacts preferentially with the phospholipid which has the same size of hydrophobic region or fatty acyl chains. 相似文献
5.
Summary Information is limited on soil contamination of leaves from field-grown row crops, especially with respect to aluminum (Al) analyses. The objective of this study was to determine the influence of washing leaf samples with either deionized water or detergent solution on elemental analyses for several agronomic crop plants. The crop plants sampled were corn (Zea mays L.), soybean (Glycine max L. Merr.), grain sorghum (Sorghum bicolor L. Moench), and wheat (Triticum aestivum L.). The crops were grown on a range of soil types, soil pH values, and tillage practices. Samples of upper leaves and lower leaves were collected separately. The samples were either not washed, washed with deionized water, or washed with detergent solution. After drying, grinding, and digesting, the samples were analyzed for Al, nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu). For all crop plants and conditions studied, there was no effect on measured N, P, K, Ca, Mg, Mn, Zn, or Cu concentrations, but measured Al and Fe concentrations were influenced by washing. In general, washing had a greater effect on Al analyses than on Fe analyses. Soybean samples were most affected by washing, while wheat samples seemed to be least affected. The results reflected greater contamination of lower leaves than upper leaves. Decontamination procedures appear necessary prior to Al and Fe analyses of field-grown crop plants. 相似文献
6.
Constant Phycobilisome Size in Chromatically Adapted Cells of the Cyanobacterium Tolypothrix tenuis, and Variation in Nostoc sp 下载免费PDF全文
Phycobilisomes of Tolypothrix tenuis, a cyanobacterium capable of complete chromatic adaptation, were studied from cells grown in red and green light, and in darkness. The phycobilisome size remained constant irrespective of the light quality. The hemidiscoidal phycobilisomes had an average diameter of about 52 nanometers and height of about 33 nanometers, by negative staining. The thickness was equivalent to a phycocyanin molecule (about 10 nanometers). The molar ratio of allophycocyanin, relative to other phycobiliproteins always remained at about 1:3. Phycobilisomes from red light grown cells and cells grown heterotrophically in darkness were indistinguishable in their pigment composition, polypeptide pattern, and size. Eight polypeptides were resolved in the phycobilin region (17.5 to 23.5 kilodaltons) by isoelectric focusing followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Half of these were invariable, while others were variable in green and red light. It is inferred that phycoerythrin synthesis in green light resulted in a one for one substitution of phycocyanin, thus retaining a constant phycobilisome size. Tolypothrix appears to be one of the best examples of phycobiliprotein regulation with wavelength. By contrast, in Nostoc sp., the decrease in phycoerythrin in red light cells was accompanied by a decrease in phycobilisome size but not a regulated substitution. 相似文献
7.
Tracking bacterial DNA replication forks in vivo by pulsed field gel electrophoresis. 总被引:5,自引:1,他引:4 下载免费PDF全文
The location of chromosomal DNA replication forks was identified in synchronously replicating E. coli cultures by pulse labeling DNA at specific times with 14C-thymidine and following incorporation of radionucleotide into genomic Not I restriction fragments. This technique could be used to characterize chromosomal DNA replication, to characterize mutations which affect this process, to identify the location of DNA replication origins and termini as well as aid in the construction of macrorestriction maps. Here, we further characterize the DNA replication mutations divE and dnaK and preliminary characterize the genomic organization of E. coli isolate 15. 相似文献
8.
Strains of Shigella species were studied for their ability to adhere and agglutinate mammalian erythrocytes. Shigella dysenteriae and Sh. flexneri exhibited haemagglutinating (HA) properties when cultured in Casamino Acids-Yeast Extract (CYE) broth in the presence of 1 mmol 1-1 calcium chloride, but other shigellae did not show this property under the same culture conditions. Repeated subcultivation of Sh. boydii, Sh. sonnei and HA negative strains of Sh. dysenteriae and Sh. flexneri in CYE broth medium induced adhesive and haemagglutinating properties that were inhibited by sodium periodate. HA activities of Shigella spp. were also inhibited by N -acetylneuraminic acid, α1 -glycoprotein and fetuin, but not by protease. Electron microscopy of Sh. dysenteriae 1, Sh. flexneri 2a, Sh. boydii 12 and Sh. sonnei 1 grown in CYE broth showed the presence of an extracellular slime layer that promoted agglutination of erythrocytes. The slime layer extracted from the cell surface of Shigella spp. showed HA properties, whereas lipopolysaccharide (LPS) obtained from the same strains, except Sh. dysenteriae 1, did not agglutinate erythrocytes. This evidence suggests that the cell surface haemagglutinin is a loosely bound slime layer which is expressed in CYE broth medium. 相似文献
9.
A third multidrug transporter gene named bmr3 was cloned from Bacillus subtilis. Although Bmr3 shows relatively low homology to Bmr and Blt, the substrate specificities of these three transporters overlap. Northern hybridization analysis showed that expression of the bmr3 gene was dependent on the growth phase. 相似文献
10.
Alternative splicing and genomic structure of the AML1 gene involved in acute myeloid leukemia. 总被引:17,自引:0,他引:17 下载免费PDF全文
H Miyoshi M Ohira K Shimizu K Mitani H Hirai T Imai K Yokoyama E Soeda M Ohki 《Nucleic acids research》1995,23(14):2762-2769