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21.
I. S. Voroshilova V. S. Artamonova A. A. Makhrov Yu. V. Slyn’ko 《Biology Bulletin》2010,37(5):542-547
Dreissenids display a high diversity of shell morphology, and it is frequently difficult to ascribe some individuals from
mixed populations to one of the two species, Dreissena polymorpha (Pallas, 1771) or D. bugensis (Andrusov, 1897). Presumably, such individuals may be interspecific hybrids. We have analyzed species-specific allozyme loci
of the typical representatives of these two mussel species and putative interspecific hybrids. A natural interspecific hybrid
between D. polymorpha and D. bugensis was discovered for the first time by genetic methods. It has been demonstrated that D. bugensis was a maternal parent. 相似文献
22.
Concerted transpositions of mobile genetic elements coupled with fitness changes in Drosophila melanogaster 总被引:3,自引:0,他引:3
Pasyukova EG; Belyaeva ES; Kogan GL; Kaidanov LZ; Gvozdev VA 《Molecular biology and evolution》1986,3(4):299-312
In an inbred low-activity (LA) strain of Drosophila melanogaster with a low
level of fitness and a complex of inadaptive characters, in situ
hybridization reveals an invariant pattern of distribution of three
copia-like elements (mdg-1, mdg-3, and copia). Rare, spontaneous, multiple
transpositions of mobile elements in the LA strain were shown to be coupled
with a drastic increase of fitness. A changed pattern of various types of
mobile elements was also observed on selecting the LA strain for higher
fitness. High-fitness strains show transpositions of mobile elements to
definite chromosomal sites ("hot spots"). Concerted changes in the location
of three different mobile elements were found to be coupled with an
increase of fitness. The mdg-1 distribution patterns were also examined in
two low-fitness strains independently selected from the high-fitness ones.
Fitness decrease was accompanied by mdg-1 excision from the hot spots of
their location usually detected in the high-fitness strains. The results
suggest the existence of a system of adaptive transpositions of mobile
elements that takes part in fitness control.
相似文献
23.
A L Okorokov N O Bukanov O Iu Beskrovnaia E B Voroshilova M M Gusiatiner V G Gritsenko N K Iankovski? V G Debabov 《Genetika》1990,26(4):648-656
Novel cloning vectors for glutamic acid producing bacteria have been constructed. The cryptic plasmid pBO1 (4.4 kb) from Brevibacterium sp. recombined with the plasmid pACYC184 (4.0 kb) from Escherichia coli was used to produce composite plasmid named pKA1. The plasmid could propagate and express the Cm-r phenotype in E. coli and coryneform glutamic acid producing bacteria Br. flavum, C. glutamicum, Br. lactofermentum. The pKA1 plasmid and its variants deleted within non-essential plasmid regions with unique restriction sites HindIII, SalGI, SphI were used in cloning experiments. The genes coding for threonine biosynthesis of C. glutamicum and Br. flavum were subcloned into shuttle vectors in C. glutamicum cells. Recombinant plasmids were introduced into protoplasts by polyethylenglycol-mediated transformation of plasmid DNAs. It was shown that the presence of plasmids containing the Br. flavum thrA2 gene in C. glutamicum (thrB) caused 10-fold increase in homoserine dehydrogenase activity, as compared to that of wild type strain, and in homoserine production. 相似文献
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Strong coupling of plant and fungal community structure across western Amazonian rainforests 总被引:1,自引:0,他引:1
The Amazon basin harbors a diverse ecological community that has a critical role in the maintenance of the biosphere. Although plant and animal communities have received much attention, basic information is lacking for fungal or prokaryotic communities. This is despite the fact that recent ecological studies have suggested a prominent role for interactions with soil fungi in structuring the diversity and abundance of tropical rainforest trees. In this study, we characterize soil fungal communities across three major tropical forest types in the western Amazon basin (terra firme, seasonally flooded and white sand) using 454 pyrosequencing. Using these data, we examine the relationship between fungal diversity and tree species richness, and between fungal community composition and tree species composition, soil environment and spatial proximity. We find that the fungal community in these ecosystems is diverse, with high degrees of spatial variability related to forest type. We also find strong correlations between α- and β-diversity of soil fungi and trees. Both fungal and plant community β-diversity were also correlated with differences in environmental conditions. The correlation between plant and fungal richness was stronger in fungal lineages known for biotrophic strategies (for example, pathogens, mycorrhizas) compared with a lineage known primarily for saprotrophy (yeasts), suggesting that this coupling is, at least in part, due to direct plant–fungal interactions. These data provide a much-needed look at an understudied dimension of the biota in an important ecosystem and supports the hypothesis that fungal communities are involved in the regulation of tropical tree diversity. 相似文献
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Tsyganov VE Voroshilova VA Priefer UB Borisov AY Tikhonovich IA 《Annals of botany》2002,89(4):357-366
Twelve non-nodulating pea (Pisum sativum L.) mutants were studied to identify the blocks in nodule tissue development. In nine, the reason for the lack of infection thread (IT) development was studied; this had been characterized previously in the other three mutants. With respect to IT development, mutants in gene sym7 are interrupted at the stage of colonization of the pocket in the curled root hair (Crh- phenotype), mutants in genes sym37 and sym38 are blocked at the stage of IT growth in the root hair cell (Ith- phenotype) and mutants in gene sym34 at the stage of IT growth inside root cortex cells (Itr- phenotype). With respect to nodule tissue development, mutants in genes sym7, sym14 and sym35 were shown to be blocked at the stage of cortical cell divisions (Ccd- phenotype), mutants in gene sym34 are halted at the stage of nodule primordium (NP) development (Npd- phenotype) and mutants in genes sym37 and sym38 are arrested at the stage of nodule meristem development (Nmd- phenotype). Thus, the sequential functioning of the genes Sym37, Sym38 and the gene Sym34 apparently differs in the infection process and during nodule tissue development. Based on these data, a scheme is suggested for the sequential functioning of early pea symbiotic genes in the two developmental processes: infection and nodule tissue formation. 相似文献