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1.
A cell line of Taxus cuspidata has been transformed with wild-type Agrobacterium rhizogenes ATCC strain 15834 containing binary vector pCAMBIA1301 and, separately, with A. tumefaciens strain EHA105 containing binary vector pCAMBIA1305.2. Additionally, a cell line of T. chinensis has been transformed with wild-type A. rhizogenes ATCC strain 25818 containing binary vector pCAMBIA1301. The two transgenic T. cuspidata cell lines have been maintained in culture for more than 20 months, and the transgenic T. chinensis cell line for more than 9 months, with no loss of reporter gene expression or antibiotic resistance. The introduced genes had no discernable effect on growth or Taxol production in the transgenic cell lines when compared to the parent control. The methods for transforming non-embryogenic Taxus suspension cultures are described.  相似文献   

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In 2004, the first report of TRIM5α as a cellular antiretroviral factor triggered intense interest among virologists, particularly because some primate orthologs of TRIM5α have activity against HIV. Since that time, a complex and eventful evolutionary history of the TRIM5 locus has emerged. A review of the TRIM5 literature constitutes a veritable compendium of evolutionary phenomena, including elevated rates of nonsynonymous substitution, divergence in subdomains due to short insertions and deletions, expansions and contractions in gene copy number, pseudogenization, balanced polymorphism, trans-species polymorphism, convergent evolution, and the acquisition of new domains by exon capture. Unlike most genes, whose history is dominated by long periods of purifying selection interspersed with rare instances of genetic innovation, analysis of restriction factor loci is likely to be complicated by the unpredictable and more-or-less constant influence of positive selection. In this regard, the molecular evolution and population genetics of restriction factor loci most closely resemble patterns that have been documented for immunity genes, such as class I and II MHC genes, whose products interact directly with microbial targets. While the antiretroviral activity encoded by TRIM5 provides plausible mechanistic hypotheses for these unusual evolutionary observations, evolutionary analyses have reciprocated by providing significant insights into the structure and function of the TRIM5α protein. Many of the lessons learned from TRIM5 should be applicable to the study of other restriction factor loci, and molecular evolutionary analysis could facilitate the discovery of new antiviral factors, particularly among the many TRIM genes whose functions remain as yet unidentified.  相似文献   

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Rhizoctonia solani and Phytophthora capsici are two of the most destructive phytopathogens occurring worldwide and are only partly being managed by traditional control strategies. Fluorescent Pseudomonas isolates PGC1 and PGC2 were checked for the antifungal potential against R. solani and P. capsici. Both the isolates were screened for the ability to produce a range of antifungal compounds. The results of this study indicated the role of chitinase and β-1,3-glucanase in the inhibition of R. solani, however, antifungal metabolites of a non-enzymatic nature were responsible for inhibition of P. capsici. The study confirmed that multiple and diverse mechanisms are adopted by the same antagonist to suppress different phytopathogens, as evidenced in case of R. solani and P. capsici.  相似文献   

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Molecular evolution of the second largest subunit of low copy nuclear RNA polymerase II (RPB2) in allotetrploid StH genomic species of Elymus is characterized here. Our study first reported a 39-bp MITE stowaway element insertion in the genic region of RPB2 gene for all tetraploid Elymus St genome and diploid Pseudoroegneria spicata and P. stipifolia St genome. The sequences on 3′-end are highly conserved, with AGTA in all sequences but H10339 (E. fibrosis), in which the AGTA was replaced with AGAA. All 12 Stowaway-containing sequences encompassed a 9 bp conserved TIRs (GAGGGAGTA). Interestingly, the 5′-end sequence of GGTA which was changed to AGTA or deleted resulted in Stowaway excision in the H genome of Elymus sepcies, in which Stowaway excision did not leave footprint. Another two large insertions in all St genome sequences are also transposable-like elements detected in the genic region of RPB2 gene. Our results indicated that these three transposable element indels have occurred prior to polyploidization, and shaped the homoeologous RPB2 loci in St and H genome of Eymus species. Nucleotide diversity analysis suggested that the RPB2 sequence may evolve faster in the polyploid species than in the diploids. Higher level of polymorphism and genome-specific amplicons generated by this gene indicated that RPB2 is an excellent tool for investigating the phylogeny and evolutionary dynamics of speciation, and the mode of polyploidy formation in Elymus species.  相似文献   

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The major histocompatibility complex genes coding for antigen binding and presenting molecules are the most polymorphic genes in the vertebrate genome. We studied the DRA and DQA gene polymorphism of the family Equidae. In addition to 11 previously reported DRA and 24 DQA alleles, six new DRA sequences and 13 new DQA alleles were identified in the genus Equus. Phylogenetic analysis of both DRA and DQA sequences provided evidence for trans-species polymorphism in the family Equidae. The phylogenetic trees differed from species relationships defined by standard taxonomy of Equidae and from trees based on mitochondrial or neutral gene sequence data. Analysis of selection showed differences between the less variable DRA and more variable DQA genes. DRA alleles were more often shared by more species. The DQA sequences analysed showed strong amongst-species positive selection; the selected amino acid positions mostly corresponded to selected positions in rodent and human DQA genes.  相似文献   

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The maT clade of transposons is a group of transposable elements intermediate in sequence and predicted protein structure to mariner and Tc transposons, with a distribution thus far limited to a few invertebrate species. We present evidence, based on searches of publicly available databases, that the nematode Caenorhabditis briggsae has several maT-like transposons, which we have designated as CbmaT elements, dispersed throughout its genome. We also describe two additional transposon sequences that probably share their evolutionary history with the CbmaT transposons. One resembles a fold back variant of a CbmaT element, with long (380-bp) inverted terminal repeats (ITRs) that show a high degree (71%) of identity to CbmaT1. The other, which shares only the 26-bp ITR sequences with one of the CbmaT variants, is present in eight nearly identical copies, but does not have a transposase gene and may therefore be cross mobilised by a CbmaT transposase. Using PCR-based mobility assays, we show that CbmaT1 transposons are capable of excising from the C. briggsae genome. CbmaT1 excised approximately 500 times less frequently than Tcb1 in the reference strain AF16, but both CbmaT1 and Tcb1 excised at extremely high frequencies in the HK105 strain. The HK105 strain also exhibited a high frequency of spontaneous induction of unc-22 mutants, suggesting that it may be a mutator strain of C. briggsae.  相似文献   

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Methyl oleate was used as a primary carbon source and as an alternative inducer for the production of an extracellular lipase, Lip2, in Y. lipolytica strain LgX64.81 grown in a 20-l bioreactor. The lipase-encoding gene, LIP2, was investigated during culture on methyl oleate using a pLIP2LacZ reporter fusion and we provide evidence for the involvement of methyl oleate in its regulation. Revisions requested 7 July 2005; Revisions received 30 August 2005  相似文献   

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Dioscorea zingiberensis Wright has been cultivated as a pharmaceutical crop for production of diosgenin, a precursor for synthesis of various important steroid drugs. Because breeding of D. zingiberensis through sexual hybridization is difficult due to its unstable sexuality and differences in timing of flowering in male and female plants, gene transfer approaches may play a vital role in its genetic improvement. In this study, the Agrobacterium tumefaciens-mediated transformation of D. zingiberensis was investigated with leaves and calli as explants. The results showed that both leaf segments and callus pieces were sensitive to 30 mg/l hygromycin and 50–60 mg/l kanamycin, and using calli as explants and addition of acetosyringone (AS) in cocultivation medium were crucial for successful transformation. We first immersed callus explants in A. tumefaciens cells for 30 min and then transferred the explants onto a co-cultivation medium supplemented with 200 μM AS for 3 days. Three days after, we cultured the infected explants on a selective medium containing 50 mg/l kanamycin and 100 mg/l timentin for formation of kanamycin-resistant calli. After the kanamycin-resistant calli were produced, we transferred them onto fresh selective medium for shoot induction. Finally, the kanamycin resistant shoots were rooted and the stable incorporation of the transgene into the genome of D. zingiberensis plants was confirmed by GUS histochemical assay, PCR and Southern blot analyses. The method reported here can be used to produce transgenic D. zingiberensis plants in 5 months and the transformation frequency is 24.8% based on the numbers of independent transgenic plants regenerated from initial infected callus explants.  相似文献   

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Vo MT  Lee KW  Kim TK  Lee YH 《Biotechnology letters》2007,29(12):1915-1920
The fadBA operon in the fatty acid β-oxidation pathway of P. putida KCTC1639 was blocked to induce a metabolic flux of the intermediates to the biosynthesis of medium chain-length PHA (mcl-PHA). Succinate at 150 mg l−1 stimulated cell growth and also the biosynthesis of medium chain-length-polyhydroxyalkanoate. pH-stat fed-batch cultivation of the fadA knockout mutant P. putida KCTC1639 was carried out for 60 h, in which mcl-PHA reached 8 g l−1 with a cell dry weight of 10.3 g l−1.  相似文献   

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Summary   Funastrum rupicola Goyder, a new species of Apocynaceae: Asclepiadoideae from Bolivia, is described and illustrated. The conservation status of this species is assessed.  相似文献   

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Pisum sativum L., the garden pea crop plant, is serving as the unique model for genetic analyses of morphogenetic development of stipule, the lateral organ formed on either side of the junction of leafblade petiole and stem at nodes. The stipule reduced (st) and cochleata (coch) stipule mutations and afila (af), tendril-less (tl), multifoliate-pinna (mfp) and unifoliata-tendrilled acacia (uni-tac) leafblade mutations were variously combined and the recombinant genotypes were quantitatively phenotyped for stipule morphology at both vegetative and reproductive nodes. The observations suggest a role of master regulator to COCH in stipule development. COCH is essential for initiation, growth and development of stipule, represses the UNI-TAC, AF, TL and MFP led leafblade-like morphogenetic pathway for compound stipule and together with ST mediates the developmental pathway for peltate-shaped simple wild-type stipule. It is also shown that stipule is an autonomous lateral organ, like a leafblade and secondary inflorescence.  相似文献   

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We developed molecular diagnostic assays for the detection of Streptococcus pyogenes (GAS) and Streptococcus dysgalactiae subsp. equisimilis (SDSE), two streptococcal pathogens known to cause both pharyngitis and more invasive forms of disease in humans. Two real-time PCR assays coupled with an internal control were designed to be performed in parallel. One assay utilizes a gene target specific to GAS, and the other utilizes a gene target common to the two species. Both assays showed 2–3 orders of magnitude improved analytical sensitivity when compared to a commercially available rapid antigen test. In addition, when compared to standard culture in an analysis of 96 throat swabs, the real-time PCR assays resulted in clinical sensitivity and specificity of 91.7 and 100%, respectively. As capital equipment costs for real-time PCR can be prohibitive in smaller laboratories, the real-time PCR assays were converted to a low-density microarray format designed to function with an inexpensive photopolymerization-based non-enzymatic signal amplification (NESA™) method. S. pyogenes was successfully detected on the low-density microarray in less than 4 h from sample extraction through detection.  相似文献   

20.
We have investigated the floral ontogeny of Arillastrum, Allosyncarpia, Stockwellia and Eucalyptopsis (of the eucalypt group, Myrtaceae) using scanning electron microscopy and light microscopy. Several critical characters for establishing relationships between these genera and to the eucalypts have been determined. The absence of compound petaline primordia in Arillastrum, Allosyncarpia, Stockwellia and Eucalyptopsis excludes these taxa from the eucalypt clade. Post-anthesis circumscissile abscission of the hypanthium above the ovary in Stockwellia, Eucalyptopsis and Allosyncarpia is evidence that these three taxa form a monophyletic group; undifferentiated perianth parts and elongated fusiform buds are characters that unite Stockwellia and Eucalyptopsis as sister taxa. No floral characters clearly associate Arillastrum with either the eucalypt clade or the clade of Stockwellia, Eucalyptopsis and Allosyncarpia.We gratefully acknowledge Clyde Dunlop and Bob Harwood (Northern Territory Herbarium) for collecting specimens of Allosyncarpia, and Bruce Gray (Atherton) for collecting specimens of Stockwellia. The Australian National Herbarium (CANB) kindly lent herbarium specimens of Eucalyptopsis for examination. This research was supported by a University of Melbourne Research Development Grant to Andrew Drinnan.  相似文献   

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