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Hilary S. Callahan Massimo Pigliucci Carl D. Schlichting 《BioEssays : news and reviews in molecular, cellular and developmental biology》1997,19(6):519-525
The plastic response of phenotypic traits to environmental change is a common research focus in several disciplines - from ecology and evolutionary biology to physiology and molecular genetics. The use of model systems such as the flowering plant Arabidopsis thaliana has facilitated a dialogue between developmental biologists asking how plasticity is controlled (proximate causes) and organismal biologists asking why plasticity exists (ultimate causes). Researchers studying ultimate causes and consequences are increasingly compelled to reject simplistic, ‘black box’ models, while those studying proximate causes and mechanisms are increasingly obliged to subject their interpretations to ecological ‘reality checks.’ We review the successful multidisciplinary efforts to understand the phytochrome-mediated shade-avoidance and light-seeking responses of flowering plants as a pertinent example of convergence between evolutionary and molecular biology. In this example, the two-way exchange between reductionist and holist camps has been essential to rapid and sustained progress. This should serve as a model for future collaborative efforts towards understanding the responses of organisms to their constantly changing environments. 相似文献
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Alberto Buson Alessandro Negro Luigi Grassato Massimo Tagliaro Marina Basaglia Claudio Grandi Angelo Fontana Marco P. Nuti 《FEMS microbiology letters》1996,145(1):55-62
Abstract A clone positive for d-carbamoylase activity (2.7 kb Hin dIII- Bam H1 DNA fragment) was obtained by screening a genomic library of Agrobacterium radiobacter in Escherichia coli . This DNA fragment contains an open reading frame of 912 bp which is predicted to encode a peptide of 304 amino acids with a calculated molecular mass of 34247 Da. The d-carbamoylase gene. named cauA , was placed under the control of T7 RNA-dependent promoter and expressed in E. coli BL21 (DE3). After induction with isopropyl-thio-β-d-galactopyranoside, the synthesis of d-carbamoylase in E. coli reached about 40% of the total protein. The expressed protein was shown to possess a molecular mass, on SDS-PAGE, of 36 kDa and showed an enhanced allowed us to establish that a Pro14 →Leu14 exchange leads to an inactive enzyme species, while a Cys279 →Ser279 exchange did not impair the functional properties of the enxyme. 相似文献
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Human gastric adenocarcinoma MKN-45 cells were found to synthesize actively carcinoembryonic antigen (CEA). The biosynthesis and carbohydrate processing of CEA were studied in these cells by means of metabolic labelling followed by immunoadsorption with a specific polyclonal-antibody preparation and gel electrophoresis. Pulse-chase studies with [14C]leucine and [3H]mannose (shortest pulse 3 min) showed that N-linked oligosaccharide side chains are added to the protein co-translationally, producing a high-mannose immature CEA; the average molecular mass of this form is 145 kDa. The protein is later translocated to the Golgi apparatus and here undergoes additional processing; these modifications are visible in our system as a broadening of the CEA band and require about 4 h. The upper limit of mature CEA band reaches 200 kDa, but radioactivity is maximally incorporated at 168 kDa. The extent of co-translational glycosylation was measured by treating the cells with tunicamycin; in the presence of this inhibitor, a 74 kDa aglyco-CEA was produced and was still recognized by the antibody. Monensin, an ionophore which interferes with glycoprotein maturation and terminal sugar addition, blocked broadening of the CEA band, producing a sharp 141 kDa peak. In conclusion, CEA appears to be synthesized as a 145 kDa high-mannose immature form, the protein core accounting for about half of its molecular mass. Full maturation results in a broad band at 168 kDa. 相似文献
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M T Parodi M Baffico G P Tonini G Dini G Ferrea L Massimo P Cornaglia-Ferraris 《International journal of cell cloning》1986,4(4):263-273
A long-term culture of bone marrow lymphoblasts in a case of unclassified acute lymphoblastic leukemia is described. Cells lacking any lymphocytic marker in the early phase of the culture were gradually substituted by B cells showing a pattern of polyclonality. The culture supernatant contained high levels of immunoglobulins also showing interleukin 2 activity. Search for antigens related to the Epstein-Barr virus was negative. A clonal expansion of B cells versus spontaneous differentiation of unclassified leukemic cells is discussed; the long-term culture technique as a tool for a better evaluation of leukemic cells is suggested and discussed. 相似文献
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The isomerization of poly-L -proline in different solvents has been studied by NMR spectroscopy. Different resonance signals for the CHα protons have been obtained for the two different helical conformations of thus compound, namely form I and form II. 相似文献