共查询到20条相似文献,搜索用时 15 毫秒
1.
Batchelor AK Boutilier K Miller SS Labbé H Bowman L Hu M Johnson DA Gijzen M Miki BL 《Planta》2000,211(4):484-492
A seed coat-specific gene, SCS1 (Seed Coat Subtilisin 1), from soybean, Glycine max [L.] Merill, has been identified and studied. The gene belongs to a small family of genes with sequence similarity to the
subtilisins, which are serine proteases. Northern blot analysis showed that SCS1 RNA accumulates to maximal levels in seed coats at 12 days post anthesis, preceding the final stages of seed coat differentiation.
The SCS1 RNA was not found in other tissues including embryos, seed pods, flowers, stems, roots or leaves. In-situ hybridization studies
confirmed the temporal pattern of expression observed by Northern blot analysis and further revealed a restricted pattern
of RNA accumulation in thick-walled parenchyma cells of the seed coats. These cells are important in the apoplastic translocation
of nutrients en route to the embryo from the vascular tissues. The tissue-specific subtilisin-like gene may be required for
regulating the differentiation of the thick-walled parenchyma cells.
Received: 10 January 2000 / Accepted: 22 February 2000 相似文献
2.
Pavel Merkulov Sofya Gvaramiya Maxim Dudnikov Roman Komakhin Murad Omarov Alina Kocheshkova Zakhar Konstantinov Alexander Soloviev Gennady Karlov Mikhail Divashuk Ilya Kirov 《植物学报(英文版)》2023,65(10):2242-2261
Transposable element insertions (TEIs) are an important source of genomic innovation by contributing to plant adaptation, speciation, and the production of new varieties. The often large, complex plant genomes make identifying TEIs from short reads difficult and expensive. Moreover, rare somatic insertions that reflect mobilome dynamics are difficult to track using short reads. To address these challenges, we combined Cas9-targeted Nanopore sequencing (CANS) with the novel pipeline NanoCasTE to trace both genetically inherited and somatic TEIs in plants. We performed CANS of the EVADÉ (EVD) retrotransposon in wild-type Arabidopsis thaliana and rapidly obtained up to 40× sequence coverage. Analysis of hemizygous T-DNA insertion sites and genetically inherited insertions of the EVD transposon in the ddm1 (decrease in DNA methylation 1) genome uncovered the crucial role of DNA methylation in shaping EVD insertion preference. We also investigated somatic transposition events of the ONSEN transposon family, finding that genes that are downregulated during heat stress are preferentially targeted by ONSENs. Finally, we detected hypomethylation of novel somatic insertions for two ONSENs. CANS and NanoCasTE are effective tools for detecting TEIs and exploring mobilome organization in plants in response to stress and in different genetic backgrounds, as well as screening T-DNA insertion mutants and transgenic plants. 相似文献
3.
S. Seah H. Bariana J. Jahier K. Sivasithamparam E. S. Lagudah 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2001,102(4):600-605
A cloned gene sequence (Vrga1D), with features of the nucleotide-binding-site leucine-rich repeat class of disease resistance
(R) gene sequence super family, was previously shown to belong to a family of five gene members derived from a Triticum ventricosum Ces. (syn. Aegilops ventricosa Tausch) segment in wheat (Triticum aestivum L.). This gene family was introgressed, together with the linked rust resistance genes Yr17, Lr37 and Sr38 from T. ventricosum, to wheat chromosome 2AS. An independently derived T. ventricosum segment carrying a leaf rust resistance gene in a French wheat cultivar, was shown to exhibit a rust resistance response equivalent
to Lr37 as well as Yr17 and Sr38. DNA probes from different regions of the Vrga1D clone consistently detected the presence of RFLPs associated with the introgressed
segment carrying the resistance genes Yr17, Lr37 and Sr38 present in diverse wheat genotypes from Australia, Canada, France and the UK. Our results showed that the transfer of the
T. ventricosum- derived Vrga1 gene members and the rust resistance genes were always accompanied by the loss of a corresponding set of Vrga1-related
gene members in recipient wheat cultivars presumed to be of homoeoallelic origin. A PCR assay, based on sequences from the
3"-untranslated region of a Vrga1 gene member isolated from the T. ventricosum donor line of the introgressed segment, was developed. The PCR assay detected the presence of the introgressed rust resistance
genes across the diverse wheat backgrounds and should be useful in marker- assisted selection in wheat breeding.
Received: 24 December 1999 / Accepted: 13 June 2000 相似文献
4.
It has been hypothesized that a large fraction of 24% noncoding DNA in R. prowazekii consists of degraded genes. This hypothesis has been based on the relatively high G+C content of noncoding DNA. However,
a comparison with other genomes also having a low overall G+C content shows that this argument would also apply to other bacteria.
To test this hypothesis, we study the coding potential in sets of genes, pseudogenes, and intergenic regions. We find that
the correlation function and the χ2-measure are clearly indicative of the coding function of genes and pseudogenes. However, both coding potentials make almost
no indication of a preexisting reading frame in the remaining 23% of noncoding DNA. We simulate the degradation of genes due
to single-nucleotide substitutions and insertions/deletions and quantify the number of mutations required to remove indications
of the reading frame. We discuss a reduced selection pressure as another possible origin of this comparatively large fraction
of noncoding sequences.
Received: 27 December 1999 / Accepted: 5 July 2000 相似文献
5.
A group of frequent cDNA clones from a young-leaf cDNA library was found to code for a homologue of S-ribonucleases (S-RNases)
involved in gametophytic incompatibility and the so-called S-like RNases active in flowers and in vegetative tissues. The
derived amino acid sequence starts with a signal peptide and has a 27-amino-acid C-terminal extension of unknown function.
The barley (Hordeum vulgare L.) gene, rsh1 (for RNase S-like homologue) corresponding to the cDNA clones was isolated. The gene has three introns and the position of
one intron corresponds to the site of the single, small intron in the S-RNase genes. The deduced amino acid sequence of mature
RSH1 shares 35% identical and 58% similar amino acid residues with an S-like RNase from tomato, RNase LE. However, two active-site
histidine residues, conserved between all S and S-like RNases are replaced by serine residues in RSH1. The new barley RNase
S-like homologue is clearly related to the family of active RNases but is probably not active as an RNase. Sequences from
the same class of presumably inactive RNases have been recorded in maize, rice and sorghum. The barley gene is exclusively
expressed in young leaf tissue and is substantially induced by light.
Received: 26 July 1999 / Accepted: 26 October 1999 相似文献
6.
Bekman EP Saibo NJ Di Cataldo A Regalado AP Ricardo CP Rodrigues-Pousada C 《Planta》2000,211(5):663-672
1-Aminocyclopropane-1-carboxylate (ACC) synthase (ACS; EC 4.4.1.14) is the key regulatory enzyme of the ethylene biosynthetic
pathway and is encoded by a multigene family in Arabidopsis thaliana, tomato, mung bean and other plants. Southern blot analysis revealed the existence of at least five ACS genes in white lupin
(Lupinus albus L.) genome. Four complete and one partial sequences representing different ACS genes were cloned from the lupin genomic library.
The levels of expression of two of the genes, LA-ACS1 and LA-ACS3, were found to increase after hypocotyl wounding. Apparently, these two genes were up-regulated by exogenous IAA treatment
of seedlings. The LA-ACS3 mRNA levels were also elevated in the apical part of hypocotyl, which is reported to contain a high endogenous auxin concentration.
This gene may be involved in the auxin- and ethylene-controlled apical hook formation. The expression of the LA-ACS4 gene was found to be almost undetectable. This gene may represent a “silent” twin of LA-ACS5 as these two genes share a considerable level of homology in coding and non-coding regions. The LA-ACS5 mRNA is strongly up-regulated in the embryonic axis of germinating seeds at the time of radicle emergence, and was also found
in roots and hypocotyls of lupin seedlings.
Received: 19 July 1999 / Accepted: 3 March 2000 相似文献
7.
Whereas the genomes of many organisms contain several nonallelic types of linker histone genes, one single histone H1 type
is known in Drosophila melanogaster that occurs in about 100 copies per genome. Amplification of H1 gene sequences from genomic DNA of wild type strains of D. melanogaster from Oregon, Australia, and central Africa yielded numerous clones that all exhibited restriction patterns identical to each
other and to those of the known H1 gene sequence. Nucleotide sequences encoding the evolutionarily variable domains of H1
were determined in two gene copies of strain Niamey from central Africa and were found to be identical to the known H1 sequence.
Most likely therefore, the translated sequences of D. melanogaster H1 genes do not exhibit intragenomic or intergenomic variations.
In contrast, three different histone H1 genes were isolated from D. virilis and found to encode proteins that differ remarkably from each other and from the H1 of D. melanogaster and D. hydei. About 40 copies of H1 genes are organized in the D. virilis genome with copies of core histone genes in gene quintets that were found to be located in band 25F of chromosome 2. Another
type of histone gene cluster is present in about 15 copies per genome and contains a variable intergenic sequence instead
of an H1 gene. The H1 heterogeneity in D. virilis may have arisen from higher recombination rates than occur near the H1 locus in D. melanogaster and might provide a basis for formation of different chromatin subtypes.
Received: 2 March 2000 / Accepted: 1 June 2000 相似文献
8.
Transgenic Arabidopsis plants can accumulate polyhydroxybutyrate to up to 4% of their fresh weight 总被引:7,自引:0,他引:7
Bohmert K Balbo I Kopka J Mittendorf V Nawrath C Poirier Y Tischendorf G Trethewey RN Willmitzer L 《Planta》2000,211(6):841-845
Transgenic Arabidopsis thaliana (L.) Heynh. plants expressing the three enzymes encoding the biosynthetic route to polyhydroxybutyrate (PHB) are described.
These plants accumulated more than 4% of their fresh weight (≈40% of their dry weight) in the form of PHB in leaf chloroplasts.
These very high producers were obtained and identified following a novel strategy consisting of a rapid GC-MS analysis of
a large number of transgenic Arabidopsis plants generated using a triple construct, thus allowing the parallel transfer of all three genes necessary for PHB synthesis
in a single transformation event. The level of PHB produced was 4-fold greater than previously published values, thus demonstrating
the large potential of plants to produce this renewable resource. However, the high levels of the polymer produced had severe
effects on both plant development and metabolism. Stunted growth and a loss of fertility were observed in the high-producing
lines. Analysis of the metabolite composition of these lines using a GC-MS method that we have newly developed showed that
the accumulation of high levels of PHB was not accompanied by an appreciable change in either the composition or the amount
of fatty acids. Substantial changes were, however, observed in the levels of various organic acids, amino acids, sugars and
sugar alcohols.
Received: 2 February 2000 / Accepted: 31 March 2000 相似文献
9.
Francki MG Berzonsky WA Ohm HW Anderson JM 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2002,104(2-3):184-191
Cereal centromeres consist of a complex organization of repetitive DNA sequences. Several repetitive DNA sequences are common
amongst members of the Triticeae family, and others are unique to particular species. The organization of these repetitive elements and the abundance of other
types of DNA sequences in cereal centromeres are largely unknown. In this study, we have used wheat-rye translocation lines
to physically map 1BL.1RS centromeric breakpoints and molecular probes to obtain further information on the nature of other
types of centromeric DNA sequences. Our results, using the rye-specific centromeric sequence, pAWRC.1, indicate that 1BL.1RS
contains a small portion of the centromere from 1R of rye. Further studies used molecular markers to identify centromeric
segments on wheat group-1 chromosomes. Selected RFLP markers, clustered around the centromere of wheat homoeologous group-1S
chromosomes, were chosen as probes during Southern hybridization. One marker, PSR161, identified a small 1BS segment in all
1BL.1RS lines. This segment maps proximal to pAWRC.1 in 1BL.1RS and on the centromere of 1B. Sequence analysis of PSR161 showed
high homology to HSP70 genes and Northern hybridization showed that this gene is constitutively expressed in leaf tissue and induced by heat shock
and light stimuli. The significance of this work with respect to centromere organization and the possible significance of
this HSP70 gene homologue are discussed.
Received: 12 March 2001 / Accepted: 14 June 2001 相似文献
10.
Sucrose synthase (SS), a key enzyme in plant carbohydrate metabolism, has recently been isolated from Anabaena sp. strain PCC 7119, and biochemically characterized; two forms (SS-I and SS-II) were detected (Porchia et al. 1999, Planta
210: 34–40). The present study describes the first isolation and characterization of a prokaryotic SS gene, susA, encoding SS-II from that strain of Anabaena. A 7 kbp DNA fragment containing an open reading frame (EMBL accession number AJ010639) with about 30–40% amino acid identity
with plant SSs was isolated from an Anabaena subgenomic library. The putative SS gene was demonstrated to encode an SS protein by expression in Escherichia coli. The biochemical properties of the recombinant enzyme were identical to those of the enzyme purified from the cyanobacterial
cells. The deduced amino acid sequence of the Anabaena SS diverged from every plant SS reported. The occurrence of SS in cyanobacteria of different taxonomic groups was investigated.
The enzyme occurs in several filamentous nitrogen-fixing cyanobacteria but not in two species of unicellular, non-diazotrophic
cyanobacteria.
Received: 5 January 2000 / Accepted: 7 March 2000 相似文献
11.
In this paper we have analyzed 49 vertebrate gene families that were generated in the early stage of vertebrates and/or shortly
before the origin of vertebrates, each of which consists of three or four member genes. We have dated the first (T1) and second (T2) gene duplications of 26 gene families with 3 member genes. The means of T1 (594 mya) and T2 (488 mya) are largely consistent to a well-cited version of two-round (2R) genome duplication theory. Moreover, in most cases,
the time interval between two successive gene duplications is large enough that the fate of duplicate genes generated by the
first gene duplication was likely to be determined before the second one took place. However, the phylogenetic pattern of
23 gene families with 4 members is complicated; only 5 of them are predicted by 2R model, but 11 families require an additional
gene (or genome) duplication. For the rest (7 families), at least one gene duplication event had occurred before the divergence
between vertebrate and Drosophila, indicating a possible misleading of the 4:1 rule (member gene ratio between vertebrates and invertebrates). Our results show
that Ohno's 2R conjecture is valid as a working hypothesis for providing a most parsimonious explanation. Although for some
gene families, additional gene duplication is needed, the credibility of the third genome duplication (3R) remains to be investigated.
Received: 13 December 1999 / Accepted: 7 April 2000 相似文献
12.
Summary. Phosphate transport in bacteria occurs via a phosphate specific transporter system (PSTS) that belongs to the ABC family of
transporters, a multisubunit system, containing an alkaline phosphatase. DING proteins were characterized due to the N-terminal
amino acid sequence DINGG GATL, which is highly conserved in animal and plant isolates, but more variable in microbes. Most
prokaryotic homologues of the DING proteins often have some structural homology to phosphatases or periplasmic phosphate-binding
proteins. In E. coli, the product of the inducible gene DinG, possesses ATP hydrolyzing helicase enzymic activity. An alkaline phosphorolytic enzyme of the PSTS system was purified
to homogeneity from the thermophilic bacterium Thermus thermophilus. N-terminal sequence analysis of this protein revealed the same high degree of similarity to DING proteins especially to
the human synovial stimulatory protein P205, the steroidogenesis-inducing protein and to the phosphate ABC transporter, periplasmic
phosphate-binding protein, putative (P. fluorescens Pf-5). The enzyme had a molecular mass of 40 kDa on SDS/PAGE, exhibiting optimal phosphatase activity at pH 12.3 and 70 °C.
The enzyme possessed characteristics of a DING protein, such as ATPase, ds endonuclease and 3′ phosphodiesterase (3′-exonuclease)
activities and binding to linear dsDNA, displaying helicase activity on supercoiled DNA. Purification and biochemical characterization
of a T. thermophilus DING protein was achieved. The biochemical properties, N-terminal sequence similarities of this protein implied that the
enzyme belongs to the PSTS family and might be involved in the DNA repair mechanism of this microorganism.
Authors’ address: Assist. Prof. A. A. Pantazaki, Laboratory of Biochemistry, Department of Chemistry, Aristotle University
of Thessaloniki, Thessaloniki 54124, Greece 相似文献
13.
Ronald W. DeBry 《Journal of molecular evolution》1998,46(3):355-360
Sequences were obtained from five species of rodents that are orthologous to an H2a histone pseudogene from Mus musculus. The pseudogene is part of the cluster of replication-dependent histone genes found on Mus musculus chromosome 13. Comparative analysis of these five sequences together with the previously published sequence from M. musculus shows that this gene has likely been a pseudogene throughout the evolution of the genus Mus, while the gene from Rattus norvegicus is likely functional. Three large (>20 bp) deletions were found among the Mus pseudogenes, a feature that is very unusual compared to surveys of processed pseudogenes. In addition, there are two single-base
deletions and one 4-bp insertion among the Mus pseudogenes. The species distributions of one of the large deletions and the 4-bp insertion require either independent insertions
of an identical sequence, independent deletions with identical boundaries, or a deletion followed by precise reintegration
of the original sequence. The evidence favors the hypothesis of multiple deletions with identical boundaries. The ``coding'
regions of the Mus pseudogenes show a much reduced level of among-species variability in the 3′ half of the pseudogene, compared both to the
5′ half and to flanking sequences. This supports a hypothesis that the 3′ end of the pseudogene is the target of frequent
gene conversion by functional H2a genes.
Received: 1 April 1997 / Accepted: 12 June 1997 相似文献
14.
Bouzat JL McNeil LK Robertson HM Solter LF Nixon JE Beever JE Gaskins HR Olsen G Subramaniam S Sogin ML Lewin HA 《Journal of molecular evolution》2000,51(6):532-543
We employed a phylogenomic approach to study the evolution of α subunits of the proteasome gene family from early diverging
eukaryotes. BLAST similarity searches of the Giardia lamblia genome identified all seven α proteasome genes characteristic of eukaryotes from the crown group. In addition, a PCR strategy
for the amplification of multiple α subunit sequences generated single α proteasome products for representatives of the Kinetoplastida
(Leishmania major), the Parabasalia (Trichomonas vaginalis), and the Microsporidia (Vairimorpha sp., Nosema sp., Endoreticulata sp., and Spraguea lophii). The kinetoplastid Trypanosoma cruzi and the eukaryote crown group Acanthamoeba castellanii yielded two distinct α proteasome genes each. The presence of seven distinct α proteasome genes in G. lamblia, one of the earliest-diverging eukaryotes, indicates that the α proteasome gene family evolved rapidly from a minimum of one
gene in Archaea to seven or more in Eukarya. Results from the phylogenomic analysis are consistent with the idea that the
Diplomonida (as represented by G. lamblia), the Kinetoplastida, the Parabasalia, and the Microsporidia diverged after the duplication events that originated the α
proteasome gene family. A model for the early origin and evolution of the proteasome gene family is presented.
Received: 14 February 2000 / Accepted: 14 August 2000 相似文献
15.
Detailed nucleotide diversity studies revealed that the fil1 gene of Antirrhinum, which has been reported to be single copy, is a member of a gene family composed of at least five genes. In four Antirrhinum majus populations with different mating systems and one A. graniticum population, diversity within populations is very low. Divergence among Antirrhinum species and between Antirrhinum and Digitalis is also low. For three of these genes we also obtained sequences from a more divergent member of the Scrophulariaceae, Verbascum nigrum. Compared with Antirrhinum, little divergence is again observed. These results, together with similar data obtained previously for five cycloidea genes,
suggest either that these gene families (or the Antirrhinum genome) are unusually constrained or that there is a low rate of substitution in these lineages. Using a sample of 52 genes,
based on two measures of codon usage (ENC and GC3 content), we show that cyc and fil1 are among the least biased Antirrhinum genes, so that their low diversity is not due to extreme codon bias.
Received: 20 June 2000 / Accepted: 25 October 2000 相似文献
16.
In arbuscular mycorrhizas, H+-ATPase is active in the plant membrane around arbuscules but absent from plant mutants defective in arbuscule development
(Gianinazzi-Pearson et al. 1995, Can J Bot 73: S526–S532). The proton-pumping H+-ATPase is encoded by a family of genes in plants. Immunocytochemical studies and promoter-gusA fusion assays were performed in transgenic tobacco (Nicotiana tabacum L.) to determine whether the periarbuscular enzyme activity results from de-novo activation of plant genes by an arbuscular
mycorrhizal fungus. The H+-ATPase protein was localized in the plant membrane around arbuscule hyphae. The enzyme was absent from non-colonized cortical
cells. Regulation of seven H+-ATPase genes (pma) was compared in non-mycorrhizal and mycorrhizal roots by histochemical detection of β-glucuronidase (GUS) activity. Two
genes (pma2, pma4) were induced in arbuscule-containing cells of mycorrhizal roots but not in non-mycorrhizal cortical tissues or senescent
mycorrhiza. It is concluded that de-novo H+-ATPase activity in the periarbuscular membrane results from selective induction of two H+-ATPase genes, which can have diverse roles in plant-fungal interactions at the symbiotic interface.
Received: 23 October 1999 / Accepted: 7 February 2000 相似文献
17.
An arabinogalactan-protein (AGP) was purified from differentiating xylem of loblolly pine (Pinus taeda L.) and the N-terminal sequence used to identify a cDNA clone. The protein, PtaAGP3, was not coded for by any previously identified AGP-like genes. Moreover, PtaAGP3 was abundantly and preferentially expressed in differentiating xylem. The encoded protein contains four domains, a signal
peptide, a cleaved hydrophilic region, a region rich in serine, alanine, and proline/hydroxyproline, and a hydrophobic C-terminus.
It is postulated to contain a GPI (glycosylphosphatidylinositol) anchor site. If the protein is cleaved at the putative GPI
anchor site, as has been observed in other classical AGPs, all but the Ser-Ala-Pro/Hyp-rich domain may be missing from the
mature protein. Xylem-specific AGPs are hypothesized to be involved in xylem development.
Received: 29 July 1999 / Accepted: 19 August 1999 相似文献
18.
Ballard JW 《Journal of molecular evolution》2000,51(1):48-63
In this study, a comparative genomics approach is employed to investigate the forces that shape evolutionary change in the
mitochondrial DNA (mtDNA) of members of the Drosophila melanogaster subgroup. This approach facilitates differentiation of the patterns of variation resulting from processes acting at a higher
level from those acting on a single gene. The mitochondrial genomes of three isofemale lines of D. simulans (siI, -II, and -III), two of D. melanogaster (Oregon R and a line from Zimbabwe), and D. mauritiana (maI and -II), and one of D. sechellia were sequenced and compared with that derived from D. yakuba. Data presented here indicate that at least three broad mechanisms shape the evolutionary dynamics of mtDNA in these taxa.
The first set of mechanisms is intrinsic to the molecule. Dominant processes may be interpreted as selection for an increased
rate of replication of the mtDNA molecule, biases in DNA repair, and differences in the pattern of nucleotide substitution
among strands. In the genes encoded on the major strand (62% of the coding DNA) changes to or from C predominate, whereas
on the minor changes to or from G predominate. The second set of mechanisms affects distinct lineages. There are evolutionary
rate differences among lineages, possibly owing to population demographic changes or changes in mutational biases. This is
supported by the heterogeneity found in synonymous, nonsynonymous, and silent substitutions. The third set of mechanisms differentially
affects distinct genes. A maximum-likelihood sliding-window analysis detected four disjunct regions that have a significantly
different nucleotide substitution process from that derived from the complete sequence. These data show the potential for
comparative genomics to tease apart subtle forces that shape the evolution of DNA.
Received: 30 July 1999 / Accepted: 16 March 2000 相似文献
19.
The pairs of nitrogen fixation genes nifDK and nifEN encode for the α and β subunits of nitrogenase and for the two subunits of the NifNE protein complex, involved in the biosynthesis
of the FeMo cofactor, respectively. Comparative analysis of the amino acid sequences of the four NifD, NifK, NifE, and NifN
in several archaeal and bacterial diazotrophs showed extensive sequence similarity between them, suggesting that their encoding
genes constitute a novel paralogous gene family. We propose a two-step model to reconstruct the possible evolutionary history
of the four genes. Accordingly, an ancestor gene gave rise, by an in-tandem paralogous duplication event followed by divergence,
to an ancestral bicistronic operon; the latter, in turn, underwent a paralogous operon duplication event followed by evolutionary
divergence leading to the ancestors of the present-day nifDK and nifEN operons. Both these paralogous duplication events very likely predated the appearance of the last universal common ancestor.
The possible role of the ancestral gene and operon in nitrogen fixation is also discussed.
Received: 21 June 1999 / Accepted: 1 March 2000 相似文献
20.
Short interspersed DNA elements (SINEs) amplify by retroposition either by (i) successive waves of amplification from one
or a few evolving master genes or by (ii) the generation of new master genes that coexist with their progenitors. Individual,
highly conserved, elements of the B1 SINE family were identified from the GenBank nucleotide database using various B1 subfamily
consensus query sequences to determine their integration times into the mouse genome. A comparison of orthologous loci in
various species of the genus Mus demonstrated that four subfamilies of B1 elements have been amplifying within the last 1–3 million years. Therefore, B1 sequences
are generated by coexisting source genes. Additionally, three B1 subfamilies have been concurrently propagated during subspecies
divergence and strain formation in Mus, indicating very recent activity of this retroposon family. The patterns of intra- and interspecies variations of orthologous
loci demonstrate the usefulness of B1 integrations as a phylogenetic tool. A single inconsistency in the phylogenetic trends
was depicted by the presence of a B1 insert in an orthologous locus exclusively in M. musculus and M. pahari. However, DNA sequence analysis revealed that these were independent integrations at the same genomic site. One highly conserved
B1 element that integrated at least 4–6 million years ago suggests the possibility of occasional function for B1 integrations.
Received: 25 February 2000 / Accepted: 5 June 2000 相似文献