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1.
Human λ light chain locus: Organization and DNA sequences of three genomicJ regions 总被引:14,自引:0,他引:14
Evidence for the genomic organization of human lambda light chain joining (J) region gene segments is presented. A mouse J probe was used in Southern hybridizations to localize joining region sequences in a cosmid clone containing the genomic cluster of six human lambda constant (C) region gene segments. The results of these hybridizations suggest the presence of at least one J gene segment upstream from each constant region gene segment. The DNA sequences indicate that the human JI, J2, and J3 gene segments have consensus nonamer and heptamer sequences, proposed to be involved in V-J joining, are capable of encoding the known amino acid sequences for the respective J peptides, and have a sequence which could give functional RNA splice site at the end of their coding regions. Our data show that a single functional J is located 1.3 or 1.6 kb upstream of each of the C gene segments known to encode the Mcg, Kern– Oz–, and Kern–Oz+ isotypes. Therefore, the gene organization of this region of the human lambda locus is J1 CI -J2C2-J3C3. The DNA sequences ofJ
1,J
2, andJ
3 presented in this paper establish that a singleJ
gene segment precedes each expressed C gene segment, and support a model for the evolution of the human JC clusters where JICI andJ2C2-J3C3. arose from different ancestral JC units. 相似文献
2.
Summary The activity of the P gene product at various multiplicities of infection (m.o.i.) was examined in C
1
-
conditions using an assay which measures the disappearance of the rapidly-sedimenting closed-circular (c.c) form of phage DNA. When cells were infected with C1857 at multiplicities of 5 phage/cell or less, between 65%–75% c.c. DNA was lost during incubation. If the multiplicity of infection was increased to 10 phage/cell or greater, a marked inhibition in the cleavage of c.c. DNA was observed.When bacteria were infected with either CI857CII2002 or CI857cro27 at low m.o.i., the usual 65%–75% decrease in the percentage of c.c. phage DNA occurred during incubation. In contrast, no losses in c.c. DNA were noted after infection with CI857cro27susP3. At high m.o.i., the cleavage of c.c. DNA was inhibited after infection with CI857CII2002, but not after infection with CI857cro27. It is concluded that at high m.o.i. in C
1
-
infections, the expression of gene P is unaffected by the CII gene product, but is inhibited by the increased intracellular levels of cro protein. 相似文献
3.
Summary Lambda virC mutant, presumably an operator mutant for the operon including x, y, CII and O genes (Fig. 1), produce clearish plaque on a sensitive bacteria.Four revertants producing turbid plaques were isolated from virC and the mutational sites of which were studied. One (tw
1) is located very close to and on the left side of virC34, and another (tw
32) is at the almost same site of virC34. The others (tx
6 and tx
53) are located on the right side of virC34. tx recombinants have been isolated and characterized. These recombinants produce very turbid plaques and the rate of the repressor formation in the presence of CIts repressor is somewhat higher than that of wild type. tx develops very poorly after infection to sensitive cells but CItx develops normally. tx lysogens synthesize two to three times more exonuclease than the wild type lysogen. On a function of x region for the repressor formation and on a presence of a possible anti-repressor were discussed. The mutant tw
1 might be a promotor mutation of the CI-rex operon.This material has been published as an abstract in Jap. J. Genetics 45, 474 (1970). 相似文献
4.
Two oxidases were found to be present in membranes from the facultative thermophile Bacillus coagulans grown at 55°C, compared to one in cells grown at 37°C. Cytochrome spectra and inhibitors of the respiratory chain identified them as cytochrome oxidases aa
3 and d. Both were present in membranes from 55°C grown cells, but only cytochrome oxidase aa
3 was found in membranes from 37°C grown cells. The presence of cytochrome d in 55°C grown cultures was found to be due to decreased oxygen tension and not to the high growth temperature. This was confirmed by (a) induction of cytochrome d at 37°C under conditions of oxygen limitation and (b) its repression at 55°C under conditions of high aeration and its subsequent induction on lowering the dissolved oxygen concentration in chemostat cultures. Two cytochromes b (max 558 and max 562) were present in both 37°C and 55°C grown cells. Results from the inhibition of substrate oxidation by membranes suggested different pathways of electron transport by the respiratory chain. 相似文献
5.
Defining patch contribution in source-sink metapopulations: the importance of including dispersal and its relevance to marine systems 总被引:1,自引:1,他引:0
In metapopulations, individual patch contribution (source or sink) is typically calculated as a patch growth rate (the intrinsic lambda, I) dependent only upon local demographics. We demonstrate that when dispersal is explicitly included in the model, the growth rates for all patches calculated in an analogous manner (the observed lambda, O) equilibrate to the overall metapopulation growth rate and thus no longer serve as a useful reflection of the demographic and dispersive characteristics of a given patch. In these situations we suggest an alternative method of estimating patch contribution (the contribution lambda, C) in which a patch is decremented for losses that occur within it and credited for gains that occur anywhere in the metapopulation because of it. We compare values of I, O, and C for individual patches in discrete-time density-independent metapopulation models of two organisms with very different life histories, mayflies with adult dispersal, and reef fish with larval dispersal. Results confirm that when dispersal is included only C clearly indicates the contribution of a particular patch. I–C comparisons indicate that inclusion of dispersal in the mayfly model was only important if connectivity patterns were random or directional. In the reef fish model, however, results were very different when dispersal was included and there were many cases of patches being misidentified (e.g., as a source when it was really a sink) depending upon the metric used (I or C). Our results demonstrate the importance of including dispersal in metapopulation models when considering the contribution of individual patches. 相似文献
6.
Summary The isolation of recombinant carrying virC mutation from newly isolated virulent carrying virL virC virR, (Horiuchi et al., 1969) was succeeded and the genetic character of virC mutation producing clear plaque was studied. virL virC shows weak-virulent character and produces clear plaque on CIts lysogen but not on wild type lysogen. virC shows avirulent character and no plaque is produced on these lysogen. The virC mutation is located very closely to and on the left side of the virR region (Fig. 1) which is presumed to be the operator of the right-side operon including O and P cistrons. The genetic characters of virL, virR and virC, were compared with v
1, v
2, v
3 mutations of classical vir (Jacob and Wollman, 1954) and c
17 mutation of another type of virulent (Da Silva and Jacob, 1968). The results indicate that virL, virC or virR mutation is similar to v
2, v
1 or v
3 mutation, respectively, and an effect of virC mutation on producing virulent character was somewhat similar to that of c
17 mutation and was stronger than that of virR mutation. The length of virR regions was suggested to be smaller than one tenth of that of the CI cistron. 相似文献
7.
Alain Lévine Huguette J. Lévine et Bention Nisman 《Molecular & general genetics : MGG》1973,121(1):83-98
Summary We have previously shown that a membranous cell-free system derived from uninfected penicillin spheroplasts of E. coli transcribes early and late messenger RNA's from DNA.This in vitro system will also transcribe and translate the endolysin gene R of DNA. The enzyme activity that results from in vitro synthesis corresponds to endolysin (a typical late protein) by several criteria.DNA from CI857 sus R5 ts 9B and CI857 sus S7 pgal, mutants carrying nonsense mutations in genes involved in the host lysis, are inactive in the synthesis of endolysin with an extract of non permissive cells, although they are fully active with an extract of permissive cells. Furthermore, suppression of these mutations is entirely dependent on addition of supernatant from suppressor strains.The endolysin synthesis from a thermosensitive CI mutant is observed at 40°C and not at 30°C. This suggests that the product of CI gene is formed and acts in the in vitro system at 30°C.Enzymatic activity is detected after a 15 min lag period.Membranes and double stranded DNA are absolutely required for the enzyme synthesis. Ribosomes and supernatant highly stimulate the in vitro system.Inhibitors of RNA, DNA and protein synthesis (actinomycine D; cytosine arabinoside; DNA-ase; and chloramphenicol respectively) will prevent endolysin production when added at zero time. If DNA-ase or actinomycine D are added after 20 min of incubation, only partial inhibition of endolysin synthesis occurs. It is therefore concluded, according to our previous observations, that messengers are stable enough to allow enzyme synthesis after delayed addition of the inhibitors in the in vitro system.It appears that there is a complete regulation in the membranous system like in vivo and which starts with the early and late messenger formation and leads to active late protein synthesis. 相似文献
8.
Tadao Horichi Hideo Koga Hachiro Inokuchi Jun-ichi Tomizawa 《Molecular & general genetics : MGG》1969,104(1):51-58
Summary Weak-virulent mutants of temperate coli-phage were isolated which can grow on the CIts lysogen producing a temperature-sensitive repressor but which cannot grow on the wild type lysogen producing a normal repressor.Genetic analysis on the mutants shows that their weak-virulence is attributable to two mutations, one (virL) in the region between sus N213 and c
47 and the other (virR) in the region between c
1 and sus O8. Both mutations are located within the region of non-homology between and imm
434 phages.True virulent mutants which can grow on the wild type lysogen can be obtained easily from the weak-virulent mutant by an additional mutation, virC in a region very close to virR. The virulent mutants obtained are similar to the classical vir mutant (Jacob and Wollman, 1954). The virL and virR mutations are probably operator mutations which render the genome insensitive to the repressor.This work was reported at the XII th International Congress of Genetics, held in Tokyo, on August 23, 1968. 相似文献
9.
Summary The left operator mutant v2s develops poorly during infection as a result of constitutive expression of the left operon. A revertant of v2s, designated iri, was found to contain an inversion of the cI region with the inversion endpoints to be within the lambda operators o
L and o
R. Formation of the inversion is facilitated by a translocation of right operator o
R
c
mutant sequence to the left operator in v2s. The inversion in iri positions wild-type o
R sequence at o
L returning control of the left operon to repression by the lambda cro repressor. 相似文献
10.
A simple one variable caricature for oscillating and excitable reaction-diffusion systems is introduced. It is shown that as a parameter, , varies the system dynamics change from oscillatory ( >
0) to excitable ( <
0) and the frequency of the oscillation vanishes as
for 0. When such dynamics are coupled by continuous diffusion in a ring geometry (1-space dimension), propagating wave trains may be found. On an infinite ring excitable devices lead to unique solitary waves which are analogous to pulse waves. A solvable example is presented, illustrating properties of dispersion, excitability, and waves. Finally it is shown that the caricature arises in a natural way from more general excitable/oscillatory systems. 相似文献
11.
Intact erythrocytes incubated in the presence of low density lipoproteins (LDL) undergo a time-dependent morphologic transformation from biconcave discs to spherocytes within 4 h. No shape change is observed when erythrocytes are incubated with high density lipoproteins (HDL). The LDL-induced change in erythrocyte morphology occurs without concomitant leakage of hemoglobin from the cell or depletion of intracellular ATP; no change in the distribution of the major lipids of the erythrocyte membranes was detected. The alteration of morphology does require attachment of LDL to the erythrocyte surface. The LDL-induced morphologic alteration is inhibited by HDL, but not by serum albumin. HDL prevent the attachment of LDL to the cell membrane; however, the HDL subfractions, HDL2 and HDL3, are only partially effective. These data suggest that normal erythrocyte morphology and cell function may depend on the concentration and composition of the circulating lipoproteins. 相似文献
12.
Summary The radioactively labeled proteins synthesised in Escherichia coli minicells infected by bacteriophage R and R
+ were compared by polyacrylamide gel electrophoresis. R mutants, which have lost the ability to lyse host cells, lack a polypeptide of molecular weight 17.5 kD corresponding to the molecular weight of murein transglycosylase — a bacteriolytic enzyme from lysates which we have described previously. It has been shown by direct comparison using radio-labeled enzyme that transglycosylase comigrates with the R gene product. The enzyme was endetectable in induced cultures of E. coli W3350 su
o (cI857 Ram5) and C600 (cI857 acR301), while it was present in a R
–
+
mutant lysate. We conclude that the transglycosylase is the R gene product.Abbreviations Muropeptide CA
GlcNac-1-4-1,6-anhydro-MurNac-L-Ala-D-Glu-msA2pm-D-Ala
- muropeptide CB
GlcNac-MurNac-GlcNac-1,6-anhydro-MurNac in which the carboxyl groups of MurNac and 1,6-anhydro-MurNac are substituted by the tetrapeptide L-Ala-D-Glu-msA2pm-D-Ala
- muropeptide C3
dimer of the two units GlcNac-MurNac-L-Ala-D-Glu-msA2pm-D-Ala which are connected by D-D peptide bond between D-Ala and msA2pm
- GlcNac
N-acetyl-D-glucosamine
- MurNac
N-acetylmuramic acid
- msA2pm
meso-diaminopimelic acid
- rivanol
6,9-diamino-2-ethoxyacridine lactate
- SDS
sodium dodecyl sulfate 相似文献
13.
Summary We have demonstrated previously by DNA-DNA hybridization that induction of phage with wild type O and P genes results in an increase of bacterial DNA in the chromosomal region adjacent to the left of the prophage, that is a segment between gal and att
(gal DNA) (Imae and Fukasawa, 1970). Evidence is presented in this report that such an increase of bacterial DNA is also seen in the region to the right of the prophage; a segment between bio and att
(bio DNA). We postulate therefore that the bidirectional replication of DNA extends beyond the prophage and copies the neighboring host DNA until the prophage is excised. The model is verified by making use of excision-defective phages. The synthesis of gal DNA (or bio DNA) slows down to a halt within 40 min after the induction in the normal lysogens. The results are attributed to the prophage excision: (1) In lysogens for int, synthesis of the bacterial DNA continues for longer times. (2) The synthesis of the bacterial DNA slows down to a halt in lysogens for xis or b2 as in the control. However DNA synthesis also slows down in parallel so that the amount of the bacterial DNA relative to that of DNA synthesized by a given time stays constant from 20 min to 80 min. During that time the relative amount of the bacterial DNA rapidly decreases in the normal lysogen.The first article of this series is in J. molec. Biol. 54, 585 (1970). 相似文献
14.
Intact erythrocytes incubated in the presence of low density lipoproteins (LDL) undergo a time-dependent morphologic transformation from biconcave discs to spherocytes within 4 h. No shape change is observed when erythrocytes are incubated with high density lipoproteins (HDL). The LDL-induced change in erythrocyte morphology occurs without concomitant leakage of hemoglobin from the cell or depletion of intracellular ATP; no change in the distribution of the major lipids of the erythrocyte membranes was detected. The alteration of morphology does require attachment of LDL to the erythrocyte surface. The LDL-induced morphologic alteration is inhibited by HDL, but not by serum albumin. HDL prevent the attachment of LDL to the cell membrane; however, the HDL subfractions, HDL2 and HDL3, are only partially effective. These data suggest that normal erythrocyte morphology and cell function may depend on the concentration and composition of the circulating lipoproteins. 相似文献
15.
P. Quillardet P. L. Moreau H. Ginsburg D. W. Mount R. Devoret 《Molecular & general genetics : MGG》1982,188(1):37-43
Summary The effect of the cellular level of RecA protein on the ability of E. coli K12 bacteria to (i) survive UV-irradiation (ii) promote UV-reactivation of UV-damaged phage (iii) induce prophage was determined in bacterial mutants with discrete increasing levels of RecA protein. The various levels of RecA protein were obtained by combining lexA and recA alleles. Except for the double mutant lexA3 recAo98, whose repair ability was 25% less than that observed in wild type bacteria, bacterial survival was proportional to the level of RecA protein measured after 90 min of incubation. In lexA3 recAo98 bacteria, RecA protein, at a constitutive high basal level, failed to compensate totally for the lack of LexA repressor cleavage; UV-reactivation of UV-damaged phage was not restored; yet, prophage was induced with 35% efficiency. Efficient UV-induction of prophage is linked to the induction of lexA-controlled host processes that repair the UV-damaged prophage. 相似文献
16.
P. H. Heinermann M. A. Ali 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1989,164(5):707-716
Summary Scotopic visual pigments measured in the creek chub and the white sucker are porphyropsins with mean max values located at 538.3 and 536.5 nm, respectively. There is a shift of the max towards shorter wavelengths during the winter in both of these species coinciding with similar changes in the quality of downwelling light. max is significantly correlated to the P50 and spectrum width of the downwelling light and dissolved oxygen. An analysis of variance shows that there are significant differences between the max values of: fish in the two lakes, fish at different times, the two species at different times and fish in different lakes at different seasons. The offset visual pigments of both species appear to be well adapted to their photic environment in terms of the contrast hypothesis. This improvement of contrast detection is discussed in relation to their feeding habits.Abbreviations max
wavelength at which absorbance is maximum
- P50
wavelength which halves the total number of photons between 400 and 700 nm, a measure of spectral quality
-
PAR
photosynthetically active radiation
-
MSP
microspectrophotometric
-
SE
standard error 相似文献
17.
Thylakoid membranes were isolated from Gymnodinium sp. and spinach, whereas the phycobilisomes were isolated and purified from red alga Porphyridium cruentum. The absorption spectra of the purified phycobilisomes (PBS) showed three peaks at 548, 564, and 624 nm, respectively, and the ratio of the fluorescence intensity at the
680
em
to that at
580
em
was about 7.3. All these results demonstrated that the purified PBS remained intact. The thylakoid membranes were incubated with the purified phycobilisomes, and the thylakoid membranes, which harbored the phycobilisomes, were purified by sucrose density gradient centrifugation. Meantime, the conjugates of phycobilisome-thylakoid membranes were constructed using glutaraldehyde and further purified. Their characteristics were studied by measuring the absorption spectra and fluorescence emission spectra. The results showed that the phycobilisomes from Porphyridium cruentum can attach to the thylakoid membranes from Gymnodinium sp. and spinach without covalent cross-linking, but the excited energy transfer did not occur. The conjugate of phycobilisome-thylakoid membranes with covalent cross-linking exhibits the excited energy transfer between the phycobilisomes and the thylakoid membranes.__________From Fiziologiya Rastenii, Vol. 52, No. 3, 2005, pp. 331–337.Original English Text Copyright © 2005 by Zhu, Wang, Tseng.This article was submitted by the authors in English. 相似文献
18.
G. H. Jacobs J. F. Deegan II J. Neitz B. P. Murphy K. V. Miller R. L. Marchinton 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1994,174(5):551-557
Electroretinogram (ERG) flicker photometry was used to study the spectral mechanisms in the retinas of white-tailed deer (Odocoileus virginianus) and fallow deer (Dama dama). In addition to having a rod pigment with maximum sensitivity (max) of about 497 nm, both species appear to have two classes of photopic receptors. They share in common a short-wavelength-sensitive cone mechanism having max in the region of 450–460 nm. Each also has a cone having peak sensitivity in the middle wavelengths, but these differ slightly for the two species. In white-tailed deer the max of this cone is about 537 nm; for the fallow deer the average max value for this mechanism was 542 nm. Deer resemble other ungulates and many other types of mammal in having two classes of cone pigment and, thus, the requisite retinal basis for dichromatic color vision.Abbreviations ERG
electroretinogram
- LWS
long wavelength sensitive
- MWS
middle wavelength sensitive
- SWS
short wavelength sensitive 相似文献
19.
Summary The clearish plaque mutants virC which were isolated from true-virulent, virLvirCvirR (virLCR), do not complement CI mutants but CII, CIII and mutant (c
42) for lysogenization. No complementation for lysogenization was observed between virCR and any CI, CII, CIII or y mutants. No lysogen was obtained when virC or virC carrying susN, susO or susP was infected to -sensitive sup
- host. This was also true for virCR. Infection of ind
- lysogen with virCRsusNO(P) or virCsusNO(P) results in marked prophage induction. Effect of virCRsusNO(P) on prophage induction is stronger than that of virCsusNO(P). These results suggest the existence of gene(s) for anti-repressor. When virCsusNO(P) or virCRsusNO(P) was infected to W3350 sup
- at high m.o.i., lysogen in anti-immune state and that in weak-immune state was obtained, respetively. Wild type phage forms clear plaque on virCsusNO(P) lysogen with e.o.p. of one and no plaque on virCRsusNO(P) lysogen. T4rII can plate on both lysogens. This weak-immunity caused by virCRsusNO(P) prophage is different from CI immunity and not abolished by irradiation of ultraviolet light (hereafter this is referred to as the vir-immunity). Action of anti-immunity and vir-immunity are almost specific. Possible functional sites for anti-and vir-immunity substances are suggested to be virL and virR regions. A hypothesis was presented that the vir-immunity may caused by the overproduced anti-immunity substance coded from x region.This material has been published as an abstract in Jap. J. Genetics 45, 479 (1970). 相似文献
20.
Summary infected minicells synthesize a polypeptide (M
r=20,500) which is incorporated almost exclusively into the outer membrane of the minicell envelope. The gene (lom=lambda outer membrane) encoding this polypeptide has been mapped in the nonessential region of the genome between coordinates 39.4% and 40.7% of . 相似文献