共查询到20条相似文献,搜索用时 15 毫秒
1.
L.K. Nakamura 《Current microbiology》1997,34(4):233-237
Organisms formerly identified as strains of
Paenibacillus pulvifaciens group II were reclassified as members of
the species Brevibacillus agri. The reclassification was based on
phylogenetic analysis of 16S rRNA gene sequences from selected
Bacillaceae. The analysis strongly supported placement of group II
strains in the genus Brevibacillus. High DNA relatedness of
87–100% and close phenotypic similarity demonstrated that group II
strains were members of the species Brevibacillus agri.
Received: 10 September 1996 / Accepted: 2 October 1996 相似文献
2.
Genomic in situ hybridization (GISH) was used to study somatic chromosomes of parental and progeny plants (all 2n=2x=14) of the bigeneric hybrid between Gasteria lutzii and Aloe aristata (Aloaceae), which is partially fertile, a rare occurrence in plants. GISH successfully distinguished between the two parental
genomes in the F1 hybrid and revealed numerous genomic recombinations in chromosomes transmitted by the F1 to the back-cross
progeny. The results indicate high levels of meiotic compatibility between the parental genomes, even though they differ in
size by 20%. Recombination occurred at a frequency that was higher than that expected from the analysis of orcein-stained
meiosis in the F1. The discrepancy suggests that terminalization may occur prior to or during metaphase I, reducing the apparent
chiasma frequency, or possibly reveals an under-estimation caused by difficulties in resolving closely grouped chiasmata by
eye.
Received: 9 September 1996; in revised form: 21 October 1996 / Accepted: 21 October 1996 相似文献
3.
B.P. Latham 《Microbial ecology》1998,36(1):60-65
Abstract
Community persistence was investigated in the yeast assemblage inhabiting patches of necrotic stem tissue of the columnar
cactus Stenocereus gummosus (pitaya agria). Two surveys, conducted in 1981 and 1996, were compared. The variation in species occurrence in a spatial
hierarchy within neuroses, among plants within a location, and among locations, was persistent across the 15-yr time span.
The core species had a community similarity coefficient of 0.75, and the rank of their variability was significantly correlated
for the two surveys. The physiological potential of the yeasts was distributed in the same manner in 1996 and 1981. Likewise,
the rank order of physiological potentials both within plant and between plants was significantly correlated. These results
indicate a microbial community that persists regionally, even though individual necroses routinely experience extinction and
colonization. The role of an insect vector, Drosophila mojavensis, in community persistence is discussed.
Received: 7 July 1997; Accepted: 27 October 1997 相似文献
4.
Interspecific hybridisation in the genus Helianthus via somatic cell fusion is thought to play an important role in future sunflower breeding programs. The establishment of
this technique requires, however, the development of single-cell-regeneration protocols. For this purpose, we applied a regeneration
protocol recently developed for Helianthus annuus L. to mesophyll protoplasts of two wild sunflowers (H. nuttallii T&G, H. giganteus L). Protoplasts of both species were embedded in agarose droplets and covered by liquid mKM medium. After 4–5 weeks, callus
was transferred onto solid differentiation medium yielding plating efficencies of 1.5% (H. nuttallii) and 2.5% (H. giganteus). Emerging shoots were elongated on hormone-free medium, and root formation was induced by an NAA treatment. Regenerated
plants were transferred to the greenhouse where they grew up to a height of 2 m and flowered after 3 months. Seeds were harvested
from regenerated plants of both species.
Received: 22 October 1996 / Revision received: 30 December 1996 / Accepted: 30 January 1997 相似文献
5.
We analyzed the functional relationship between the Escherichia coli RNase E and the CafA protein, which show extensive sequence similarity. The temperature-sensitive growth of the RNase E mutant
strain ams1 was partially suppressed by multicopy plasmids bearing the cafA gene. Introduction of a cafA::cat mutation enhanced the temperature sensitivity of the ams1 mutant. These results suggest that there is a functional homology between these two proteins.
Received: 17 May 1996 / Accepted: 1 October 1996 相似文献
6.
Somatic hybrids between Solanum tuberosum cv 'Brodick' and S. sanctae-rosae were selected for having elevated chromosome numbers, intermediate morphology and potato cyst nematode resistance (derived
from S. sanctae-rosae). DNA was extracted from this material and subjected to inter-SSR PCR directed by oligonucleotide primers comprising 5′-anchored
di- and tri-nucleotide repeat motifs. PCR products were separated by polyacrylamide gel electrophoresis and visualised by
silver staining. An average of 30.31 bands per primer were generated in each parent and, on average, 8.19 of these bands were
polymorphic. S. sanctae-rosae-specific bands were observed in the hybrid material as was evidence of deletions, substitutions and rearrangements. The relative
merits of this technique for the analysis of somatic hybrid material are discussed.
Received: 23 July 1996 / Revision received: 22 October 1996 / Accepted: 22 March 1999 相似文献
7.
Regeneration in caraway was obtained via two different routes. Hypocotyls showed delayed shoot formation after a callus phase
and at relatively low frequencies. In contrast, high-frequency, direct regeneration occurred when cotyledonary node explants
were used. Transient expression of β-glucuronidase was monitored after inoculation of both explant types with Agrobacterium tumefaciens AGL0(pMOG410). Gene transfer was more efficient when using cotyledonary node explants. This explant type also proved to be
the best for stable transformation resulting in transgenic plants. Several parameters determining regeneration and transformation
efficiency were tested. The percentage of explants giving one to numerous transgenic plants could be as high as 13%. This
system for the rapid production of many transgenic caraway plants opens up possibilities for studying metabolic engineering
with this crop.
Received: 8 October 1996 / Revision received: 2 January 1997 / Accepted: 2 February 1997 相似文献
8.
In a culture method for enhanced axillary branching functional plants of Eucalyptus tereticornis and E. camaldulensis are efficiently regenerated. To assess the genetic integrity among the regenerants, we employed multiple analytical tools
including cytochemical and molecular assays. The 2C DNA amounts were estimated in the meristematic zones of root and shoot
tips of 250 micropropagated plants, collected at various cycles of tissue culture from multiplication to field transfer, and
compared to the corresponding mother plants. The culture conditions did not induce amplification or deletion of DNA sequences,
nor were there drastic change(s) in chromosome number, since all the micropropagated plants of E. tereticornis (1.2 pg) and E. camaldulensis (1.4 pg) maintained the same DNA amounts as the mother plant. Total DNA of 46 micropropagated and mother plants digested
with eight restriction enzymes and hybridized to 13 nuclear, mitochondrial, and synthetic oligonucleotide DNA probes yielded
82 bands. Hybridization patterns indicated that the variation observed was minor. To further confirm the genetic fidelity,
12 arbitrary 10-base primers and six synthetic oligonucleotide sequences, successfully used to amplify genomic DNA from in
vivo and in vitro materials, produced 133 fragments that were monomorphic across the plants tested. The present results demonstrate
that enhanced-axillary-branching culture of mature trees could be utilized commercially for mass clonal propagation of these
two important Eucalyptus species that have been recalcitrant to vegetative propagation. The results also provide novel insights into the genetic differences
between E. tereticornis and E. camaldulensis.
Received: 8 October 1996 / Revision received: 22 July 1997 / Accepted: 30 July 1997 相似文献
9.
While a large number of studies have examined the effects of increased ultraviolet-B radiation (UV-B) on growth and physiological
function of plants, UV-B effects on pollination success and fitness are poorly understood. To examine this question, we measured
growth, timing of flowering, pollination success, production of pollen, ovules, flowers, fruits, and seeds, and quality of
offspring produced by Brassica nigra and B. rapa in a garden experiment. A total of 313 plants of the two species were randomly divided into two treatment groups. One group
received only natural ambient levels of UV-B, while the other received an artificially enhanced UV-B dose. Fitness of B. nigra declined at the higher UV-B dose while B. rapa fitness did not change. One possible cause of this result was a shift in the relative attractiveness of the two species to
pollinators: visitation to B. nigra declined at the high UV-B dose while B. rapa visitation increased.
Received: 25 October 1996 / Accepted: 27 March 1997 相似文献
10.
A. Pellegrineschi C. A. Fatokun G. Thottappilly A. A. Adepoju 《Plant cell reports》1997,17(2):133-138
Factors responsible for successful rescue of immature embryos of cowpea [Vigna unguiculata (L.) Walp.] and V. vexillata (L.) and for in vitro embryo development were studied. A new basal medium for embryo development in vitro was formulated
on the basis of the mineral composition of embryos. Sucrose, fructose and glucose were compared as carbohydrate sources. The
highest frequency of embryos developing into plants was obtained with sucrose. Adding casein hydrolysate to the medium increased
plant recovery by 30%. Among the plant growth factors used, cytokinins, zeatin, 6-benzylaminopurine and kinetin were the most
effective in promoting embryo maturation and development. A method that can routinely ensure high plant recovery from cultured
immature cowpea embryos is proposed.
Received: 4 June 1996 / Revision received: 28 October 1996 / Accepted: 22 November 1996 相似文献
11.
Expression of the yeast trehalose-6-phosphate synthase gene in transgenic tobacco plants: pleiotropic phenotypes include drought tolerance 总被引:2,自引:1,他引:1
Carlos Romero José M. Bellés José L. Vayá Ramón Serrano Francisco A. Culiáñez-Macià 《Planta》1997,201(3):293-297
The yeast trehalose-6-phosphate synthase gene (TPS1) was engineered under the control of the cauliflower mosaic virus regulatory sequences (CaMV35S) for expression in plants.
Using Agrobacterium-mediated transfer, the gene was incorporated into the genomic DNA and constitutively expressed in Nicotiana tabacum␣L. plants. Trehalose was determined in the transformants, by anion-exchange chromatography coupled to pulsed amperometric
detection. The non-reducing disaccharide accumulated up to 0.17 mg per g fresh weight in leaf extracts of transgenic plants.
Trehalose-accumulating plants exhibited multiple phenotypic alterations, including stunted growth, lancet-shaped leaves, reduced
sucrose content and improved drought tolerance. These pleiotropic effects, and the fact that water loss from detached leaves
was not significantly affected by trehalose accumulation, suggest that synthesis of this sugar, rather than leading to an
osmoprotectant effect, had altered sugar metabolism and regulatory pathways affecting plant development and stress tolerance.
Received: 8 July 1996 / Accepted: 10 October 1996 相似文献
12.
An antigen in the outer membrane protein (OMP) fraction of
Campylobacter jejuni was identified and characterized. Western blot
analysis demonstrated antigenic differences in this protein between two
congenic C. jejuni strains. Strain A74/C, which colonizes chickens,
expressed the antigen at 34 kDa, while strain A74/O, which poorly colonizes
chickens, expressed the antigen at 32 and 34 kDa. A genomic library was
constructed in λgt11 with DNA from A74/O and screened with antibody raised
against C. jejuni OMPs. A clone that possessed a 1.3-kb insert and
expressed an immunoreactive protein fused to β-galactosidase was isolated
and purified. DNA sequence analysis revealed the insert contained one open
reading frame 864 bases long. The deduced amino acid sequence demonstrated
56.3% similarity with Bacillus steorothermophilus glnH, a
glutamine-binding protein, and 54.0% similarity with C. jejuni
PEB1, a putative colonization adhesin. Southern hybridization, Northern
hybridization, and DNA sequence analyses of the congenic colonizing and
noncolonizing strains of C. jejuni failed to distinguish the two
strains and revealed only one copy of the gene. Post-translational
modification may be an alternate explanation for the antigenic differences
seen between the two strains.
Received: 15 October 1996 / Accepted: 3 December 1996 相似文献
13.
The presence of IS240 was investigated in 69
Bacillus thuringiensis (Bt) strains including strains from
serotype H1 to H45 and additional strains with known Dipteran larvae
toxicity. Restriction digests of total DNA and PCR products obtained with a
single 16-bases primer corresponding to the IS240 inverted repeated
sequence were hybridized with the IS240A element. The results
indicate that 67% of the Bt strains tested, including all
known mosquitocidal strains, possess at least one IS240-related
element. PCR experiments indicate that IS240 represents a family of
insertion sequences with several variants.
Received: 15 October 1996 / Accepted: 20 November 1996 相似文献
14.
Leaf, rhizome, and stem explants of Helianthus smithii, a wild relative of the cultivated sunflower, have been tested for their morphogenic potential on media containing a range
of hormonal combinations including α-naphthaleneacetic acid and 6-benzylaminopurine (0–2 mg/l). Somatic embryos appeared on
the majority of the tested media incorporating auxins, while shoots were observed on media containing exclusively 6-benzylaminopurine.
Fertile plants were recovered from all explant types under a wide range of conditions, albeit with different efficiencies.
The induction mechanism of the observed shoots is discussed.
Received: 12 July 1996 / Revision received: 13 September 1996 / Accepted: 5 October 1996 相似文献
15.
Identification of a Cold Shock Gene in Lactic Acid Bacteria and the Effect of Cold Shock on Cryotolerance 总被引:6,自引:0,他引:6
When Lactic Acid Bacterial cultures were frozen at −20°C for 24 h, the cell viability decreased drastically, but when they
were cold shocked at 10°C for 2 h prior to freezing, viability improved significantly for the Lactococcus lactis subsp. lactis strains (25–37%) and Pediococcus pentosaceus PO2 (18%), but not for the Lactococcus lactis subsp. cremoris strains tested or for one strain of Lactobacillus helveticus LB1 and Streptococcus thermophilus TS2. When the period for cold shock was extended to 5 h, the viability increased even further for those strains that displayed
cold shock cryotolerance. Use of degenerate PCR primers based on the major cold shock protein (csp) of both Escherichia coli and Bacillus subtilis resulted in PCR products from all strains tested. The PCR product from Lactococcus lactis ssp. lactis M474 was cloned and sequenced, and the deduced amino acid sequence displayed a high sequence similarity to other csp's. Use
of PCR primers based on the M474 sequence resulted in PCR products being produced only from the lactococcal strains studied
and not from the Lactobacillus helveticus, Streptococcus thermophilus, or Pediococcus pentosaceus strains tested.
Received: 18 October 1996 / Accepted: 28 January 1997 相似文献
16.
Alessandra Bonci Alessandra Chiesurin Patrizia Muscas Gian Maria Rossolini 《Journal of molecular evolution》1997,44(3):299-309
The structure of a Salmonella enterica serovar typhi gene located within the fim gene cluster and encoding a putative periplasmic chaperone-like protein involved in the assembly of type 1 pili was determined.
This gene, named fimC, has the ability to encode a 26-kDa polypeptide which is similar, at the sequence level, to the PapD periplasmic chaperonin
mediating the assembly of P pili of Escherichia coli, as well as to other periplasmic chaperone-like proteins involved in the biogenesis of pili or capsule-like structures of
various Gram-negative bacteria. A comprehensive search through the literature and sequence databases identified 31 (putative)
bacterial proteins that can be included in this protein family on the basis of sequence similarity. Results of a multiple
sequence comparison analysis showed that several residues, including most of those known to be critical in maintaining the
three-dimensional structure of PapD, are either conserved or conservatively substituted in all these proteins, suggesting
an overall similar folding for all of them. It was also evident that members of this family are clustered into different subfamilies
according to structural and phyletic data.
Received: 15 February 1996 / Accepted: 3 October 1996 相似文献
17.
Transfer of a grapevine stilbene synthase gene to rice (Oryza sativa L.) 总被引:17,自引:0,他引:17
P. Stark-Lorenzen B. Nelke G. Hänßler H. P. Mühlbach J. E. Thomzik 《Plant cell reports》1997,16(10):668-673
A gene derived from grapevine (Vitis vinifera) coding for stilbene synthase has been transferred into protoplasts of the commercially important japonica rice cultivar
Nipponbare using PEG-mediated direct gene transfer. Transgenic plants were regenerated from calli selected on kanamycin. Southern
blot analysis of genomic DNA isolated from regenerants and progeny plants demonstrated that the stilbene synthase gene is
stably integrated in the genome of transgenic rice plants and inherited in the offspring. The transient formation of stilbene-synthase-specific
mRNA shortly after inoculation with the fungus of the rice blast Pyricularia oryzae has demonstrated that the grapevine stilbene synthase promoter is also active in monocotyledonous plants. Preliminary results
indicate an enhanced resistance of transgenic rice to P. oryzae.
Received: 1 July 1996 / Revision received: 5 November 1996 / Accepted: 30 November 1996 相似文献
18.
J. M. H. Kijas M. R. Thomas J. C. S. Fowler M. L. Roose 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,94(5):701-706
We report the successful assignment of the first seven microsatellite markers to the Citrus RFLP and isozyme map. A total of 14 microsatellite primer pairs were developed and tested for amplification and product-length
polymorphism within a population of plants previously used for linkage-map construction. In each case, the successfully assigned
microsatellite mapped to the termini of a different linkage group indicating a widespread distribution throughout the genome.
Analysis of allele segregation revealed that two of nine microsatellites displayed a significant deviation from expected ratios
(P>0.5). This was compared with other marker types within Citrus and a similar proportion of skewed loci was also found to be present. The analysis of two markers was complicated by the
non-amplification of an inherited null allele within the mapping population. The successful integration of microsatellites
into the genetic map of Citrus demonstrates the utility of this marker type for genetic analysis within wide intergeneric plant crosses.
Received: 16 September 1996 / Accepted: 18 October 1996 相似文献
19.
Gene structure of a chlorophyll a/c-binding protein from a brown alga: Presence of an intron and phylogenetic implications 总被引:5,自引:0,他引:5
Lise Caron Dominique Douady Michelle Quinet-Szely Susan de Goër Claire Berkaloff 《Journal of molecular evolution》1996,43(3):270-280
A Laminaria saccharina genomic library in the phage EMBL 4 was used to isolate and sequence a full-length gene encoding a fucoxanthin-chlorophyll
a/c-binding protein. Contrary to diatom homologues, the coding sequence is interrupted by an intron of about 900 bp which
is located in the middle of the transit peptide. The deduced amino acid sequence of the mature protein is very similar to
those of related proteins from Macrocystis pyrifera (Laminariales) and, to a lesser extent, to those from diatoms and Chrysophyceae. Seven of the eight putative chlorophyll-binding
amino acids determined in green plants are also present. Alignments of different sequences related to the light-harvesting
proteins (LHC) demonstrate a structural similarity among the three transmembrane helices and suggest a unique ancestral helix
preceded by two β-turns. The β-turns are conserved in front of the second helices of the chlorophyll a/c proteins more so
than in chlorophyll a/b proteins. Phylogenetic trees generated from sequence data indicate that fucoxanthin-chlorophyll-binding
proteins diverged prior to the separation of photosystem I and photosystem II LHC genes of green plants. Among the fucoxanthin-containing
algae, LHC I or II families could not be distinguished at this time.
Received: 14 February 1996 / Accepted: 4 April 1996 相似文献
20.
Detection of somaclonal variation in garlic (Allium sativum L.) using RAPD and cytological analysis 总被引:12,自引:0,他引:12
Plants were regenerated by somatic embryogenesis from long-term callus cultures derived from five garlic (Allium sativum L.) cultivars. Thirty-five of these plants were subjected to RAPD analysis. The frequency of variation was found to be cultivar
dependent: approximately 1% in the two clones Solent White and California Late and around 0.35% in another three clones, Chinese,
Long Keeper and Madena. Certain band changes were found in regenerants of different cultivars, suggesting the existence of
a mutation-sensitive part of the garlic genome. The karyotypes of another 75 regenerants derived from the same callus cultures
of three parental garlic clones were examined. Of these plants, 9.3% were found to be tetraploids, 4% aneuploid and 2.6% showed
a change in the position of the secondary constriction. No association could be shown between the rate of variation for molecular
and cytological characters either by comparing cultivars or examining individual regenerants.
Received: 30 July 1996 / Revision received: 28 October 1996 / Accepted: 12 November 1996 相似文献