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11.
After c. 30 years without sighting or capture, Anthias salmopunctatus was rediscovered at the type locality, St Peter and St Paul's Rocks, Mid-Atlantic Ridge. To date, the known distribution is restricted to depths varying from 35 to 55 m in vertical drop offs around the perimeter of the islands ( c. 400 m). This may be the smallest geographic range known for a marine fish species. 相似文献
12.
Competition from native soil rhizobia is likely to be an important factor limiting Phaseolus vulgaris L. inoculant response in Latin America. We used UMR 1116, a nod
+ fix– natural mutant of Rhizobium leguminosarum bv phaseoli strain CC511, as a reference strain to study competition for nodulation sites in this species. When P. vulgaris cv Carioca was planted in soils containing different proportions of UMR 1116 and the effective and competitive strain UMR 1899, UMR 1116 occupied more than 50% of the nodules at all inoculant ratios tested, though increasing the proportion of UMR 1899 in the inoculant did enhance the number and percentage of effective nodules and plant dry weight. Sixty two strains of bean rhizobia were tested in competition with UMR 1116. An inoculant ratio of 1:1 was used, with all strains applied to the soil rather than to seeds. Strains varied in the number and percentage of effective nodules produced in competition with UMR 1116, and in plant dry weight, and there was a strong correlation between variation in each of these traits and plant N accumulation. Seven of the strains (UMR 1073, 1084, 1102, 1125, 1165, 1378 and 1384) were identified as both superior in competitive ability and active in N2 fixation. Site of placement of the inoculant and ambient temperature influenced strain response.Journal paper 16736, Agricultural Experiment Station, University of Minnesota, St. Paul, MN 55108, USA 相似文献
13.
14.
Synthesis of the nuclear protein cyclin (PCNA) and its relationship with DNA replication 总被引:38,自引:0,他引:38
Rodrigo Bravo 《Experimental cell research》1986,163(2):287-293
Synthesis of the nuclear protein cyclin (MW 36 000) and DNA in quiescent mouse fibroblasts is coordinately induced by serum and purified growth factors. Inhibition of DNA synthesis by hydroxyurea or aphidicolin in serum-stimulated quiescent cells does not affect the induction of cyclin. The levels of cyclin synthesis decrease rapidly at the end of the S phase. Immunofluorescence studies reveal that there are dramatic changes in the nuclear distribution of cyclin during S phase and that these depend on DNA synthesis or events during S phase. These observations strengthen the notion that cyclin is an important component of the events leading to DNA replication. 相似文献
15.
16.
Begoña Granadino Luiz O. F. Penalva Lucas Sánchez 《Molecular & general genetics : MGG》1996,250(1):89-96
Crosses betweenDrosophila melanogaster females andD. simulans males produce viable hybrid females, while males are lethal. These males are rescued if they carry theD. simulans Lhr gene. This paper reports that females of the wild-typeD. melanogaster population Staket do not produce viable hybrid males when crossed withD. simulans Lhr males, a phenomenon which we designate as the Staket phenotype. The agent responsible for this phenomenon was found to be the StaketX chromosome (X
mel
,Stk). Analysis of the Staket phenotype showed that it is suppressed by extra copies ofD. melanogaster rDNA genes and that theX
mel
,Stk chromosome manifests a weak bobbed phenotype inD. melanogaster X
mel
,Stk/0 males. The numbers of functional rDNA genes inX
mel
,Stk andX
mel
,y w (control) chromosomes were found not to differ significantly. Thus a reduction in rDNA gene number cannot account for the weak bobbedX
mel
,Stk phenotype let alone the Staket phenotype. The rRNA precursor molecules transcribed from theX
mel
,Stk rDNA genes seem to be correctly processed in both intraspecific (melanogaster) and interspecific (melanogaster-simulans) conditions. It is therefore suggested that theX
mel
,Stk rDNA genes are inefficiently transcribed in themelanogaster-simulans hybrids. 相似文献
17.
Stimulation of in vitro shoot proliferation from nodal explants of cassava by thidiazuron, benzyladenine and gibberellic acid 总被引:2,自引:0,他引:2
Basdeo Bhagwat Luiz G. F. Vieiral Larry R. Erickson 《Plant Cell, Tissue and Organ Culture》1996,46(1):1-7
Multiple shoots were produced from nodal explants of cassava (Manihot esculenta Crantz) by a two-step procedure: a 6- to 8-day exposure to 0.11–0.22 µM thidiazuron (TDZ) in liquid Murashige and Skoog (MS) medium followed by culture on agar-solidified MS medium supplemented with 2.2 µM 6-benzyladenine (BA) and 1.6 M gibberellic acid (GA3). TDZ caused the nodal explants to expand and this expansion (growth) continued during culture with BA and GA3. From this expanded explant, clusters of buds and fasciated stems developed continuously and these gave rise to shoots. The shoot proliferation process was open-ended, yielding an average of 31.5 shoots per nodal explant after 10 weeks of culture with genotype CG 1–56. A positive response was also obtained from seven other genotypes evaluated with this protocol.Abbreviations BA
6-benzyladenine
- BM
basal medium
- DPU
1,3-diphenylurea
- GA3
gibberellie acid
- 2iP
isopentenyladenine
- MSM
multiple shoot medium
- NAA
1-naphthaleneacetic acid
- PGR
plant growth regulator
- TDZ
thidiazuron
- Z
zeatin 相似文献
18.
Marcello Franco Eduardo Bagagli Marino Cunha Luiz Gastão Chamma Denise Fecchio 《Mycopathologia》1996,135(1):13-19
We investigated the occurrence of antigenic and biochemical variability among Paracoccidioides brasiliensis antigen batches prepared according to the same protocol. Initially (experiment #1), we analyzed two antigen lots of two human isolates (Bt1 & Bt2), cultured in two media (PYG: bactopeptone, yeast extract, glucose; MMM: McVeigh & Morton medium) in SDS-PAGE and in two immunological tests (imunodiffusion-ID and footpad swelling test-FPT). Afterwards (experiment #2), we compared the antigenic profile of three antigen batches from three human isolates (Bt1, Bt2 & Bt3) by two-dimensional immunoelectrophoresis (2 D-IEP) against a reference system for P. brasiliensis antigens. In experiment #1, there were important intra- and inter-strain antigenic differences between batches of the fungal isolates cultured on both media. The block titration of the antigen batches for the immunological tests revealed correlation between protein concentration and biological activity in ID and no correlation in FPT. In experiment #2, the reference system for P. brasiliensis showed 26 antigen peaks. There were important differences between batches prepared from the same isolate and between batches from different isolates. Our data suggested the occurrence of instability in the synthesis of antigenic components by a same P. brasiliensis isolate, under controlled incubation conditions. 相似文献
19.
Large scale patterns and trophic structure of southern African rocky shores: the roles of geographic variation and wave exposure 总被引:2,自引:0,他引:2
In this study we revise the biogeographic delimitation, and large-scale patterns of community structure of the intertidal rocky shores of southern Africa. We use binary (presence/absence) and per-species biomass data collected at fifteen localities and thirty-seven different rocky sites, encompassing the shores of southern Namibia, South Africa and southern Mozambique. Multivariate analyses revealed that the shores of southern Africa (south of 25°) can be divided into three main biogeographic provinces: the west coast or Namaqua province, the south coast or Agulhas province and the east coast or Natal province. The biomass structure of the intertidal rocky shores communities of southern Africa varied at a large scale, corresponding to biogeographic differences, while local-scale variation accorded with the intensity of local wave action. The average biomass of west coast communities was on average significantly greater than that of the south and east provinces. At a local scale, the community biomass on exposed shores was an order of magnitude greater than on sheltered shores, within all biogeographic provinces. Semi-exposed shores exhibited intermediate average biomass. The trophic structure of these communities varied significantly with wave action: autotrophs, filter-feeders and invertebrate predators were more prevalent on wave exposed than sheltered shores, whereas grazers were more abundant on sheltered and semi-exposed shores. Exposed shores were consistently dominated by far fewer species than semi-exposed and sheltered shores, independently of biogeographic differences. Within all biogeographic provinces semi-exposed and sheltered shores were more diverse than exposed shores. West coast intertidal communities therefore had high levels of biomass, but were consistently species-poor. Several working hypotheses that could explain these large and small-scale patterns are presented. 相似文献
20.
Leda Guzman Rodrigo Bustos Ricardo B. Maccioni 《Molecular and cellular biochemistry》1994,131(2):105-113
The changes in the levels of microtubule-associated proteins (MAPs) during advanced embryonic stages, neonatal and adult organisms reflect the importance of these cytoskeletal proteins in relation to the morphogenesis of the central nervous system. MAP-1B is found in prenatal brains and it appears to have the highests levels in neonatal rat brains, being a developmentally-regulated protein. In this research, a fast procedure to isolate MAP-1B, as well as MAP-2 and MAP-3 from neonatal rat brains was designed, based on the differential capacity of poly L-aspartic acid to release MAPs during temperature-dependent cycles of microtubule assembly in the absence of taxol. The high molecular weight MAP-1B was recovered in the warm supernatants after microtubular protein polymerization in the presence of low concentrations of polyaspartic acid. Instead, MAP-2 and a 180 kDa protein with characteristics of MAP-3 remained associated to the polymer after the assembly. Further purification of MAP-1B was attained after phosphocellulose chromatography. Isolation of MAP-2 isoforms together with MAP-3 was achieved on the basis of their selective interactions with calmodulin-agarose affinity columns. In addition, MAP-2 and MAP-3 were also purified on the basis of their capacities to interact with the tubulin peptide -II (422–434) derivatized on an Affigel matrix. However, MAP-1B did not interact with the -II tubulin fragment, but it showed interaction with the Affigel-conjugated -I (431–444) tubulin peptide. The different MAPs componentes were characterized by western blots using specific monoclonal antibodies. A salient feature of neonatal rat brain MAP-3 was its interactions with site-directed antibodies that recognize binding epitopes on the repetitive sequences of tau and MAP-2. However, these site-specific antibodies did not interact with MAP-1B from the neonatal rat brain tissue.Abbreviations PAA
poly (L-aspartic acid)
- HMW-MAPs
high molecular weight microtubule associated proteins 相似文献