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Phylogenetic distribution in the genus Mus of t-complex-specific DNA and protein markers: inferences on the origin of t-haplotypes 总被引:8,自引:0,他引:8
Delarbre C; Kashi Y; Boursot P; Beckmann JS; Kourilsky P; Bonhomme F; Gachelin G 《Molecular biology and evolution》1988,5(2):120-133
We have examined the phylogenetic distribution of two t-specific markers
among representatives of various taxa belonging to the genus Mus. The
centromeric TCP-1a marker (a testicular protein variant specific for all
t-haplotypes so far studied) has also been apparently detected in several
non-t representatives of the Mus IVA, Mus IVB, and probably M. cervicolor
species. By contrast, a t-specific restriction- fragment-length
polymorphism allele (RFLP) of the telomeric alpha- globin pseudogene DNA
marker alpha-psi-4 was found only in animals belonging to the M.
musculus-complex species either bearing genuine t- haplotypes or, like the
M. m. bactrianus specimen studied here, likely to do so. This t-specific
alpha-psi-4 RFLP allele was found to be as divergent from the RFLP alleles
of the latter, non-t, taxonomical groups as it is from Mus 4A, Mus 4B, or
M. spretus ones. These results suggest the presence of t-haplotypes and of
t-specific markers in populations other than those belonging to the M. m.
domesticus and M. m. musculus subspecies, implying a possible origin for
t-haplotypes prior to the radiation of the most recent offshoot of the Mus
genus (i.e., the spretus/domesticus divergence), some 1-3 Myr ago.
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Steady-state current flow through gap junctions. Effects on intracellular ion concentrations and fluid movement. 总被引:1,自引:1,他引:0 下载免费PDF全文
Double voltage clamp studies were performed on gap junctions contained in septal membranes of the earthworm median giant axon. The gap junctions exhibited no conductance changes in response to voltages imposed across either the septal membrane or the plasma membrane. However, the trans-septal current displayed a slow (10 s) relaxation in response to transjunctional voltage steps. The experimental evidence suggests that this relaxation is a polarization of the septum due to local accumulation/depletion of permeant ions. A theoretical analysis of this observation suggests that the applied electric field causes accumulation of impermeant anions on one side of the junction and depletion on the other, which leads to a change in concentration of permeant ions to maintain macroscopic electroneutrality. The change in concentration of permeant ions generates a transjunctional equilibrium potential that opposes junctional current flow. These results indicate that currents flowing through gap junctions can have an influence on the distribution of intracellular ions. Moreover, the theoretical analysis suggests that such currents will be accompanied by significant intracellular and intercellular water flow. 相似文献
4.
Summary The seasonal occurrence ofAtyaephyra desmaresti in The Netherlands has been studied by sampling the cooling-water filtering screens of power stations situated along the rivers Rhine and Meuse. The shrimps were only found in large numbers at the two power stations with vegetation in the cooling-water intake areas. Fluctuations in the seasonal occurrence showed great similarity for these two localities. Highest numbers of shrimps were impinged in November. High numbers also occurred in September, while a lower peak in numbers was found in May.Changes in the numbers of records during the last 30 years in The Netherlands were compared with climatological fluctuations (severe or mild winters), indicating that this mainly southern-European species is living here at the limits of its ecological and geographical range.The distribution in The Netherlands reveals thatAtyaephyra desmaresti mainly occurs in freshwater habitats, although it tolerates higher chlorinities. 相似文献
5.
In this report the karyotypes of 54 species of the tribe Milesiini and of four species of the tribe Myoleptini are described in detail with illustrations and idiograms. These species belong in the genera Lejota, Myolepta, Blera, Calliprobola, Criorhina, Hadromyia, Milesia, Somula, Sphecomyia, Spilomyia, Syritta, Temnostoma, Tropidia and Xylota. Six species have 2n = 8 chromosomes, 35 have 2n = 10 (including Xylota nemorum which has about 20 extra microchromosomes in some specimens), 15 have 2n = 12, one has 2n = 14, and Somula decora has 2n = 10 large chromosomes plus about eight microchromosomes. The mean total complement length (TCL) for 347 complements analysed in these tribes was 53.7 but there is great variation between TCL's of complements analysed even from a single fly. Karyotypes of species of Myolepta in the Myoleptini resemble in certain respects those of species of Tropidia in the Milesiini. Our observations support Currran's transfer of Lejota cyanea to the Milesiini. The 2n = 12 karyotypes of species of Blera, Criorhina, Lejota, Milesia, and to a lesser extent Sphecomyia, have some features in common. Spilomyia species have rather distinct 2n = 10 karyotypes. Certain species in Calliprobola, Syritta and Hadromyia are karyologically similar to some species of the genus Xylota in which species studied fall into fairly distinct karyological groups. These observations provide clear evidence of the accumulation of karyotypic variations in the origin of species in these two tribes. 相似文献
6.
The chromosome number in the damselflyEnallagma cyathigerum (Charp.) is 2n =27, 2n =28, n =14 (13). The sex determining mechanism is XX-XO, the X segregates postreductionally in the male. 相似文献
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In this paper we describe the identification of pristanoyl-CoA oxidase activity in rat liver peroxisomes. This activity was not stimulated by clofibrate feeding. Furthermore, the activity was found in multiple tissues. These results show that pristanoyl-CoA oxidase is different from any of the known oxidases which include a clofibrate-inducible acyl-CoA oxidase and the recently identified cholestanoyl-CoA oxidase. Gelfiltration and chromatofocusing experiments provide conclusive evidence that we are dealing with a novel acyl-CoA oxidase with a unique function in peroxisomal beta-oxidation. 相似文献