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1.
Levans produced by four Zymomonas mobilis strains showed antitumour activity against sarcoma 180 and Ehrlich carcinoma in Swiss albino mice. Levans from two strains (ZAP and CP4) had the highest effects. NMR analysis showed that the polymers were composed only of fructose units. The results suggested that the antineoplasic effect is associated to the polysaccharide molecular weight and that a particular molecular weight range may be responsible for this effect. 相似文献
2.
A. P. Read R. V. Thakker K. E. Davies R. C. Mountford D. P. Brenton M. Davies F. Glorieux R. Harris G. N. Hendy A. King S. McGlade C. J. Peacock R. Smith J. L. H. O'Riordan 《Human genetics》1986,73(3):267-270
Summary Eleven families with X-linked dominant hypophosphataemic rickets (HPDR) have been typed for a series of X chromosome markers. Linkage with probe 99.6 (DXS41) was demonstrated with a peak lod score of 4.82 at 10% recombination. Multilocus linkage analysis showed that HPDR maps distal to 99.6; this probe has previously been located at Xp22.31-p21.3 by in situ hybridisation. In the mouse hypophosphataemia (Hyp) maps to the distal part of the X chromosome; our location in man is consistent with a scheme which relates the mouse and human X chromosomes by two rearrangements. No marker has yet been found which shows no recombination with HPDR. 相似文献
3.
Poliovirus type 3: molecular cloning of the genome and nucleotide sequence of the region encoding the protease and polymerase proteins. 总被引:8,自引:3,他引:5 下载免费PDF全文
A J Cann G Stanway R Hauptmann P D Minor G C Schild L D Clarke R C Mountford J W Almond 《Nucleic acids research》1983,11(5):1267-1281
Overlapping cDNA clones representing the entire genome of poliovirus type 3 have been prepared in E. coli by two separate methods. Cloning of RNA . cDNA hybrids produced a more comprehensive set of clones with generally larger cDNA inserts than cloning of double - stranded cDNA. A restriction map of the entire genome and the nucleotide sequence of 2003 bases from the 3' terminus, comprising the region encoding the protease and polymerase proteins, are presented. 相似文献
4.
Variation in the ribosomal internal transcribed spacers (ITS1 and ITS2) among eight taxa of the Mimulus guttatus species complex 总被引:1,自引:0,他引:1
The internal transcribed spacer region (ITS1 and ITS2) of the 18S-25S
nuclear ribosomal DNA sequence and the intervening 5.8S region were
sequenced from three individuals in each of eight taxa of the Mimulus
guttatus species complex. Three discrete variants, or "types," of ITS
sequences were found, among which 30%-40% of sites differed, compared with
1%-2% within types. Dot plots indicate that these types were not related by
conspicuous rearrangements or inversions. More than one ITS type was often
found in the same taxon, and two of three ITS types span species
boundaries, indicating their presence prior to speciation. These ITS
sequences showed essentially no positional homology with the nearest
sequenced relative, tomato. In contrast, the 5.8S region was relatively
unvaried, with 8 of 162 sites varied in the sample among all eight taxa.
The phylogeny inferred by the most common ITS sequence type, rooted by the
two other ITS types, agreed with isozymes in showing the distinctness of M.
nudatus, M. laciniatus, and M. tilingii from the other five taxa.
相似文献
5.
Variation in heat shock proteins within tropical and desert species of poeciliid fishes 总被引:8,自引:0,他引:8
Norris CE; diIorio PJ; Schultz RJ; Hightower LE 《Molecular biology and evolution》1995,12(6):1048-1062
The 70-kilodalton heat shock protein (hsp70) family of molecular
chaperones, which contains both stress-inducible and normally abundant
constitutive members, is highly conserved across distantly related taxa.
Analysis of this protein family in individuals from an outbred population
of tropical topminnows, Poeciliopsis gracilis, showed that while
constitutive hsp70 family members showed no variation in protein isoforms,
inducibly synthesized hsp70 was polymorphic. Several species of
Poeciliopsis adapted to desert environments exhibited lower levels of
inducible hsp70 polymorphism than the tropical species, but constitutive
forms were identical to those in P. gracilis, as they were in the
confamilial species Gambusia affinis. These differences suggest that
inducible and constitutive members of this family are under different
evolutionary constraints and may indicate differences in their function
within the cell. Also, northern desert species of Poeciliopsis synthesize a
subset of the inducible hsp70 isoforms seen in tropical species. This
distribution supports the theory that ancestral tropical fish migrated
northward and colonized desert streams; the subsequent decrease in
variation of inducible hsp70 may have been due to genetic drift or a
consequence of adaptation to the desert environment. Higher levels of
variability were found when the 30- kilodalton heat shock protein (hsp30)
family was analyzed within different strains of two desert species of
Poeciliopsis and also in wild-caught individuals of Gambusia affinis. In
both cases the distribution of hsp30 isoform diversity was similar to that
seen previously with allozyme polymorphisms.
相似文献
6.
Sequences of junction fragments in the deletion-prone region of the dystrophin gene 总被引:15,自引:0,他引:15
D R Love S B England A Speer R F Marsden J F Bloomfield A L Roche G S Cross R C Mountford T J Smith K E Davies 《Genomics》1991,10(1):57-67
The Duchenne muscular dystrophy locus is remarkable in that it shows a high mutation rate and the majority of mutations found are deletions. These deletions are generated as meiotic as well as mitotic events and occur preferentially in the central region of the gene. Nothing is known so far about the mechanisms involved. This paper reports the first sequencing of deletion junctions in the dystrophin gene. The data from a study of two patients with deletions in the central region of dystrophin show the breakpoints to lie in regions of introns in which stretches of dA-dT are seen. The relationship between these observations and possible mechanisms for the mutations is discussed. 相似文献
7.
Schistosoma mansoni: the effect of regional lymphadenectomy on the level of protection induced in mice by radiation-attenuated cercariae 总被引:4,自引:0,他引:4
The lymph nodes which drain the sites of percutaneous vaccination with optimally irradiated cercariae of Schistosoma mansoni were surgically excised in studies to determine their role in the induction of protective immunity. Lymphadenectomy of the axillary and inguinal nodes which drain the abdominal exposure site, or of the cervical node which drains the aural site of exposure, five days prior to vaccination reduced the levels of resistance by two-thirds. Excision of these nodes on Days 5, 10, 15, or 20 postvaccination also significantly reduced the levels of immunity induced, though ablation was less effective at later times. Removal of lymph nodes not draining the site of vaccination had no effect on the induction of resistance. We interpret the results as indicating that successful vaccination of mice against S. mansoni requires the presentation of antigen to lymphocytes in local lymph nodes draining the vaccination site, rather than distant lymphoid organs such as the spleen. 相似文献
8.
Long-term change in an unmanaged population of wych elm subjected to Dutch elm disease 总被引:1,自引:0,他引:1
1 Changes in a population of Ulmus glabra in Lady Park Wood (UK), a mixed deciduous native woodland, were studied by means of permanent transects. All individuals reaching 1.3 m height were recorded at irregular intervals from 1945 to 1993.
2 Dutch elm disease struck this population in about 1972. Most of the canopy and subcanopy stems were killed, but a few, slow-growing, subcanopy individuals survived unscathed.
3 Subsequent seedling regeneration and growth of sprouts from rootstocks of infected trees was substantial and vigorous. Twenty-three years after the outbreak of disease the number of elm individuals had increased by about 40%. Disease has, however, continued to afflict vigorous, exposed individuals.
4 The large-scale distribution of elm has been unaffected, but the small-scale pattern has changed due to the concentration of seedling regeneration in gaps.
5 The elm population appears to be differentiating into (i) a large high-turnover subpopulation of fast-growing, but repeatedly diseased maiden individuals and sprouts, and (ii) a small, low-turnover subpopulation of slow-growing individuals rooted in suboptimally dry, secluded sites. 相似文献
2 Dutch elm disease struck this population in about 1972. Most of the canopy and subcanopy stems were killed, but a few, slow-growing, subcanopy individuals survived unscathed.
3 Subsequent seedling regeneration and growth of sprouts from rootstocks of infected trees was substantial and vigorous. Twenty-three years after the outbreak of disease the number of elm individuals had increased by about 40%. Disease has, however, continued to afflict vigorous, exposed individuals.
4 The large-scale distribution of elm has been unaffected, but the small-scale pattern has changed due to the concentration of seedling regeneration in gaps.
5 The elm population appears to be differentiating into (i) a large high-turnover subpopulation of fast-growing, but repeatedly diseased maiden individuals and sprouts, and (ii) a small, low-turnover subpopulation of slow-growing individuals rooted in suboptimally dry, secluded sites. 相似文献
9.
David E. Sanin Catriona T. Prendergast Claire D. Bourke Adrian P. Mountford 《PLoS pathogens》2015,11(5)
The skin provides an important first line of defence and immunological barrier to invasive pathogens, but immune responses must also be regulated to maintain barrier function and ensure tolerance of skin surface commensal organisms. In schistosomiasis-endemic regions, populations can experience repeated percutaneous exposure to schistosome larvae, however little is known about how repeated exposure to pathogens affects immune regulation in the skin. Here, using a murine model of repeated infection with Schistosoma mansoni larvae, we show that the skin infection site becomes rich in regulatory IL-10, whilst in its absence, inflammation, neutrophil recruitment, and local lymphocyte proliferation is increased. Whilst CD4+ T cells are the primary cellular source of regulatory IL-10, they expressed none of the markers conventionally associated with T regulatory (Treg) cells (i.e. FoxP3, Helios, Nrp1, CD223, or CD49b). Nevertheless, these IL-10+ CD4+ T cells in the skin from repeatedly infected mice are functionally suppressive as they reduced proliferation of responsive CD4+ T cells from the skin draining lymph node. Moreover, the skin of infected Rag-/- mice had impaired IL-10 production and increased neutrophil recruitment. Finally, we show that the mechanism behind IL-10 production by CD4+ T cells in the skin is due to a combination of an initial (day 1) response specific to skin commensal bacteria, and then over the following days schistosome-specific CD4+ T cell responses, which together contribute towards limiting inflammation and tissue damage following schistosome infection. We propose CD4+ T cells in the skin that do not express markers of conventional T regulatory cell populations have a significant role in immune regulation after repeated pathogen exposure and speculate that these cells may also help to maintain skin barrier function in the context of repeated percutaneous insult by other skin pathogens. 相似文献