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排序方式: 共有620条查询结果,搜索用时 15 毫秒
611.
M T Cornelissen T Bots M A Bri?t M F Jebbink A P Struyk J G van den Tweel C E Greer H L Smits J ter Schegget 《Virchows Archiv. B, Cell pathology including molecular pathology》1992,62(3):167-171
By means of a consensus polymerase chain reaction (PCR) method, the prevalence of HPV types was determined in cervical biopsies from 137 women referred to the gynecological outpatient clinic for colposcopy because of an abnormal cervical smear. The prevalence of HPV was 80.3%. There was a statistically highly significant rise in the prevalence of the oncogenic HPV types (16, 18, 31, 33) with increasing severity of cervical intraepithelial neoplasia (CIN I to III), indicating a role for these HPV types in the pathogenesis of cervical cancer. The prevalence of other HPV types decreased significantly with the severity of the lesion, suggesting that these HPV types play a less significant role in this process. These data indicate that HPV typing with PCR may be a valuable tool for distinguishing between high-risk and low-risk cervical lesions. Furthermore, our results suggest that the detection of HPV types by consensus PCR in the cervix of patients with an abnormal smear but without histologically detectable CIN is a useful tool for predicting which of these patients will eventually develop CIN. Finally, a relatively low percentage (3%) of HPV double infections is reported in this study. 相似文献
612.
613.
Summary Two strains of Pelodictyon clathratiforme have been successfully maintained in culture in a partly purified state. Their maintenance under laboratory conditions requires low light intensity and low sulfide concentrations.The formation of the characteristic three-dimensional nets appears to be the consequence of occasional branching at the contiguous poles of two cells in a chain, to form a ring which expands by subsequent normal cell growth and division. Both strains contain the chlorobium vesicles typical of other green bacteria, and their absorption spectra indicate the presence of the chlorophyllous pigments characteristic of this group. Unlike other green bacteria so far studied, P. clathratiforme produces gas vacuoles, homologous in structure to those of blue-green algae.Dedicated to Prof. C. B. van Niel on the occasion of his 70th birthday. 相似文献
614.
J. H. C. Cornelissen 《Oecologia》1999,118(2):248-255
A hypothesized relationship between seed weight and leaf size was investigated for 58 diverse British (semi-)woody species.
Interspecific variation in leaf size of adult plants corresponded allometrically with interspecific variation in the weight
of an infructescence (seed-bearing inflorescence). The relationship between seed size and leaf size of adult plants was triangular.
The corners of the triangle were interpreted in terms of ecological strategy. Medium-sized infructescences, small seeds and
large leaves were seen among medium-sized, fast-growing, earlier-successional, mostly deciduous shrubs and trees; small infructescences,
small seeds and small leaves mostly among low, slow-growing evergreens from stress-prone, proclimax habitats; and large infructescences,
large seeds and large leaves among slow-growing, later-successional trees of potential competitive vigour. The hypothesis
that the combination of large seeds and small leaves is allometrically unlikely was supported by the data. The roles of ontogeny
and taxonomic relatedness in the seed size-leaf size relationship were examined by correlative and taxonomic analyses of seed,
plant and leaf size during the unfolding of the life history from seed through two seedling phases to adulthood. Deciduous
versus evergreen leaf habit was a source of deviation from the otherwise linear allometric relationships during ontogenetic
development, none of which were, individually, confounded significantly with taxonomy.
Received: 2 March 1998 / Accepted: 15 October 1998 相似文献
615.
cDNA to an mRNA that is strongly induced in Samsun NN tobacco after tobacco mosaic virus (TMV) infection or salicylic acid treatment was used to probe a genomic blot and to screen a genomic library. The mRNA corresponds to a family of approximately eight genes, four of which were cloned. The sequence of the genes and flanking DNA in two clones was determined. One gene was found to contain an intron of 555 bp; S1-nuclease mapping studies indicated that this gene is expressed. The other gene is interrupted by an intron of 1,954 bp and is probably not expressed after TMV infection. The genes encode a protein of 109 amino acids with a putative N-terminal signal peptide of 26 amino acids. The protein contains a high proportion of glycine (25%) and charged amino acids (29%), suggesting that it may be a cell wall component. A comparison of the upstream sequences of the genes encoding the glycine-rich protein and the pathogenesis-related protein 1a showed only limited homology, although both genes are TMV- and salicylic acid-inducible. However, the upstream sequence of the glycine-rich protein gene contains a 64-bp inverted repeat that occurs in a similar position in the tobacco ribulose bisphosphate carboxylase small subunit gene. 相似文献
616.
617.
Complete sequence of the gene encoding the largest subunit of RNA polymerase I of Trypanosoma brucei 总被引:5,自引:0,他引:5
We have set out to clone the trypanosomal gene encoding the largest subunit of RNA polymerase I. We screened a genomic library with a synthetic oligonucleotide probe encoding an eleven amino acid sequence motif, YNADFDGDEMN, which has been found in all eukaryotic RNA polymerase largest subunit genes analyzed so far. We isolated the Trp11 locus and determined the complete sequence of the gene encoded within this locus. The deduced amino acid sequence contains the highly conserved RNA polymerase domains as well as the previously identified RNA polymerase I-specific hydrophilic insertions. Therefore, the gene most closely resembles the largest subunit of RNA polymerase I. 相似文献
618.
Chromosome rearrangements in Trypanosoma brucei 总被引:39,自引:0,他引:39
619.
Transcription analysis in Trypanosoma brucei 总被引:2,自引:0,他引:2
A W Cornelissen S Backes R Evers E J Grondal W Jess J K?ck 《Biochemical Society transactions》1990,18(5):710-714
620.