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1.
Agonist-stimulated oscillations and cycling of intracellular free calcium in individual cultured muscle cells 总被引:7,自引:0,他引:7
Receptor regulation of [Ca2+]i was monitored in individual BC3H-1 muscle cells with intracellularly trapped fura-2 using digital imaging analysis techniques. Activation of alpha 1-adrenergic or H1-histaminergic receptors resulted in multiple bursts, or oscillations, of elevated [Ca2+]i with an average interval frequency of approximately 1.8 min-1. The duration of oscillatory behavior was generally more prolonged in response to phenylephrine than in response to histamine. Additionally, a larger fraction of the cells responded with [Ca2+]i oscillations to phenylephrine (approximately 90%) than to histamine (approximately 60%), although the majority of cells produced oscillations in response to both agonists. In most cells, the receptor-mediated [Ca2+]i oscillations continued for several minutes in the absence of extracellular Ca2+, although the amplitude of the individual peaks gradually decreased. The activation of [Ca2+]i oscillations by H1-receptors was more dependent upon extracellular Ca2+ than those elicited by alpha 1-receptors, reflecting the greater dependency of the histaminergic response on Ca2+ influx. Readdition of Ca2+ to the incubation buffer resulted in the resumption of the [Ca2+]i oscillations. These results indicate that considerable cycling of Ca2+ between the cytoplasm and the endoplasmic reticulum must occur. Receptor-mediated [Ca2+]i oscillations were much more prevalent in subconfluent cells than in confluent cells, possibly due to increased coupling of the cells at higher densities. The cells were capable of responding independently of one another, since sister cells displayed unique temporal responses immediately following cell division. Thus, the linkage of receptor occupancy to [Ca2+]i elevation is a functionally unique property for each individual cell and can be influenced by epigenetic factors. 相似文献
2.
Hardies SC; Martin SL; Voliva CF; Hutchison CA d; Edgell MH 《Molecular biology and evolution》1986,3(2):109-125
3.
4.
A major difference between the divergence patterns within the lines-1 families in mice and voles 总被引:3,自引:0,他引:3
Vanlerberghe F; Bonhomme F; Hutchison CA d; Edgell MH 《Molecular biology and evolution》1993,10(4):719-731
L1 retroposons are represented in mice by subfamilies of interspersed
sequences of varied abundance. Previous analyses have indicated that
subfamilies are generated by duplicative transposition of a small number of
members of the L1 family, the progeny of which then become a major
component of the murine L1 population, and are not due to any active
processes generating homology within preexisting groups of elements in a
particular species. In mice, more than a third of the L1 elements belong to
a clade that became active approximately 5 Mya and whose elements are >
or = 95% identical. We have collected sequence information from 13 L1
elements isolated from two species of voles (Rodentia: Microtinae: Microtus
and Arvicola) and have found that divergence within the vole L1 population
is quite different from that in mice, in that there is no abundant
subfamily of homologous elements. Individual L1 elements from voles are
very divergent from one another and belong to a clade that began a period
of elevated duplicative transposition approximately 13 Mya. Sequence
analyses of portions of these divergent L1 elements (approximately 250 bp
each) gave no evidence for concerted evolution having acted on the vole L1
elements since the split of the two vole lineages approximately 3.5 Mya;
that is, the observed interspecific divergence (6.7%-24.7%) is not larger
than the intraspecific divergence (7.9%-27.2%), and phylogenetic analyses
showed no clustering into Arvicola and Microtus clades.
相似文献
5.
Molecular phylogeny and divergence times of drosophilid species 总被引:32,自引:15,他引:17
The phylogenetic relationships and divergence times of 39 drosophilid
species were studied by using the coding region of the Adh gene. Four
genera--Scaptodrosophila, Zaprionus, Drosophila, and Scaptomyza (from
Hawaii)--and three Drosophila subgenera--Drosophila, Engiscaptomyza, and
Sophophora--were included. After conducting statistical analyses of the
nucleotide sequences of the Adh, Adhr (Adh-related gene), and nuclear rRNA
genes and a 905-bp segment of mitochondrial DNA, we used Scaptodrosophila
as the outgroup. The phylogenetic tree obtained showed that the first major
division of drosophilid species occurs between subgenus Sophophora (genus
Drosophila) and the group including subgenera Drosophila and Engiscaptomyza
plus the genera Zaprionus and Scaptomyza. Subgenus Sophophora is then
divided into D. willistoni and the clade of D. obscura and D. melanogaster
species groups. In the other major drosophilid group, Zaprionus first
separates from the other species, and then D. immigrans leaves the
remaining group of species. This remaining group then splits into the D.
repleta group and the Hawaiian drosophilid cluster (Hawaiian Drosophila,
Engiscaptomyza, and Scaptomyza). Engiscaptomyza and Scaptomyza are tightly
clustered. Each of the D. repleta, D. obscura, and D. melanogaster groups
is monophyletic. The splitting of subgenera Drosophila and Sophophora
apparently occurred about 40 Mya, whereas the D. repleta group and the
Hawaiian drosophilid cluster separated about 32 Mya. By contrast, the
splitting of Engiscaptomyza and Scaptomyza occurred only about 11 Mya,
suggesting that Scaptomyza experienced a rapid morphological evolution. The
D. obscura and D. melanogaster groups apparently diverged about 25 Mya.
Many of the D. repleta group species studied here have two functional Adh
genes (Adh-1 and Adh-2), and these duplicated genes can be explained by two
duplication events.
相似文献
6.
P. H. Clarke R. E. Drew C. Turberville W. J. Brammar R. P. Ambler A. D. Auffret 《Bioscience reports》1981,1(4):299-307
A restriction enzyme map was constructed for 5.1-kb fragment of Pseudomonas aeruginosa DNA inserted into plasmid pBR322. Restriction enzyme sites were matched to the N-terminal amino acid sequence of amidase to obtain alignment of the amiE gene within the cloned fragment. 相似文献
7.
Sulfate reduction and S-oxidation in a moorland pool sediment 总被引:3,自引:2,他引:1
In an oligotrophic moorland pool in The Netherlands, S cycling near the sediment/water boundary was investigated by measuring (1) SO4
2– reduction rates in the sediment, (2) depletion of SO4
2– in the overlying water column and (3) release of35S from the sediment into the water column. Two locations differing in sediment type (highly organic and sandy) were compared, with respect to reduction rates and depletion of SO4
2– in the overlying water.Sulfate reduction rates in sediments of an oligotrophic moorland pool were estimated by diagenetic modelling and whole core35SO4
2– injection. Rates of SO4
2– consumption in the overlying water were estimated by changes in SO4
2– concentration over time in in situ enclosures. Reduction rates ranged from 0.27–11.2 mmol m–2 d–1. Rates of SO4
2– uptake from the enclosed water column varied from –0.5, –0.3 mmol m–2 d–1 (November) to 0.43–1.81 mmol m–2 d–1 (July, August and April). Maximum rates of oxidation to SO4
2– in July 1990 estimated by combination of SO4
2– reduction rates and rates of in situ SO4
2– uptake in the enclosed water column were 10.3 and 10.5 mmol m–2 d–1 at an organic rich and at a sandy site respectively.Experiments with35S2– and35SO4
2– tracer suggested (1) a rapid formation of organically bound S from dissimilatory reduced SO4
2– and (2) the presence of mainly non SO4
2–-S derived from reduced S transported from the sediment into the overlying water. A35S2– tracer experiment showed that about 7% of35S2– injected at 1 cm depth in a sediment core was recovered in the overlying water column.Sulfate reduction rates in sediments with higher volumetric mass fraction of organic matter did not significantly differ from those in sediments with a lower mass fraction of organic matter.Corresponding author 相似文献
8.
L. Sawyer C.L. Jones A.M. Damas M.M. Harding R.O. Gould R.P. Ambler 《Journal of molecular biology》1981,153(3):831-835
The dihaem cytochrome c4 from Pseudomonas aeruginosa has been crystallized in space group P6522 with cell dimensions , and one molecule per asymmetric unit. Two heavy-atom derivatives, UO2(NO3)2 and K2Pt(NO2)4, which substitute at one and three sites, respectively, have allowed a low-resolution electron density map to be obtained. This shows clearly the two domains of the molecule. 相似文献
9.
The use of thermolysin in amino acid sequence determination. 总被引:13,自引:10,他引:3
10.
Boron-deficient soybean roots have a rosette appearance at the terminals caused by the death of the root primordium and the initiation of new root primordia. The root tips show some darkening, swelling, and then a collapse of the tissue. The petiole s of B-deficient plants are very brittle. Physiologically, B-deficiency in HA-soybeans does not appear to involve an interference in the transport of photosynthate (C14 distribution) or precursors required for citrate synthesis in the roots. More Ca 45 was found in the tops of B-sufficient than B-deficient plants, but the opposite trend existed in the root sap. Boron deficiency symptoms were accentuated by maintaining a relatively low pH of the prenutrient solution by the addition of K salts. 相似文献