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61.
Marc Pauly Isabelle Kayser Martine Schmitz Fernand Ries François Hentges Mario Dicato 《Journal of molecular evolution》1995,41(6):974-978
The mdr1 gene, first member of the human multidrug-resistance gene family, is a major gene involved in cellular resistance to several drugs used in anticancer chemotherapy. Its product, the drug-excreting P-glycoprotein, shows a bipartite structure formed by two similar adjacent halves. According to one hypothesis, the fusion of two related ancestral genes during evolution could have resulted in this structure. The DNA sequence analysis of the introns located in the region connecting the two halves of the human mdr1 gene revealed a highly conserved poly(CA) · poly (TG) sequence in intron 15 and repeated sequences of the Alu family in introns 14 and 17. These repeated sequences most likely represent molecular fossils of ancient DNA elements which were involved in such a recombination event.
Correspondence to: M. Pauly 相似文献
62.
Christine Heberden Thierry Mercier Isabelle Gaillard-Sanchez Brigitte Huet Paule Martel 《Experimental cell research》1995,218(2)
We assessed the presence and the role of membrane TGF-α in two rat liver epithelial cell lines, either parental or transfected with c-fos proto-oncogene. c-fos overexpressing cells had more TGF-α-like activity in their membranes. When TGF-α was removed by elastase or neutralized, the growth rates of both cell lines were markedly reduced, but to a higher extent for parental cells. If membrane TGF-α seemed to play a key contribution in normal cell growth, both cell lines were unable to react to the addition of soluble TGF-α, showing that these two forms of growth factors are not equivalent. 相似文献
63.
64.
Sabine Castano Bernard Desbat Isabelle Cornut Philippe Méléard Jean Dufourcq 《Letters in Peptide Science》1997,4(4-6):195-200
De novo designed extremely simplified amphipathic basicLeuiLysj (i = 2j) peptides of 8, 9 and 15residues were synthesized to clarify the mechanism of action of naturalcytotoxic and hemolytic small proteins or peptides. They proved to havestrong hemolytic activity towards human erythrocytes which increases withpeptide length. These peptides are highly surface active and form stablepeptidic films at the air/water interface. The sensitive and efficient FTIRmodulated polarization technique (PMIRRAS) allows one to obtain in situstructural and orientational information about the peptides at theinterface. A transition of secondary structure is observed: the shorterpeptides (8 and 9 residues) adopt -sheet structures while the longerone (15 residues) is folded into an -helix. In both cases, the peptideslie with the axis parallel to the interface. Their insertion into adimyristoylphosphatidylcholine monolayer can be followed from the increasein the surface and/or pressure of the films. In the mixed films, thepeptides adopt the same structure and orientation as observed at theair/water interface. Therefore, among the same series of peptides, atransition from -sheet to -helix occurs when the length increases(roughly >10 aa), but despite this drastic change both types ofstructures result in strongly hemolytic peptides. 相似文献
65.
Positive role of macaque cytotoxic T lymphocytes during SIV infection: decrease of cellular viremia and increase of asymptomatic clinical period 总被引:1,自引:0,他引:1
66.
Nicolae Barbacar Stefan Hinnisdaels Isabelle Farbos Françoise Monéger ré Lardon Catherine Delichère Armand Mouras Ioan Negrutiu 《The Plant journal : for cell and molecular biology》1997,12(4):805-817
The dioecious white campion (Silene latifolia) has been chosen as a working model for sexual development. In this species, sexual dimorphism is achieved through two distinct developmental blocks: inhibition of carpel development in male flowers, and early arrest of anther differentiation in female flowers. The combined advantages of the dioecious system and the availability of a sexual mutant lacking both male and female reproductive organs have been exploited in a molecular subtraction approach using male and asexual flower buds. This resulted in the cloning of 22 cDNA clones expressed in stamens at distinct stages of development. Fourteen of these clones corresponded to genes whose expression was detected in pre-meiotic stamens, a stage of development for which very little information is presently available. Furthermore, the absence of similarities with database sequences for ten clones suggests that they represent novel genes. Functional analysis of each clone will enable their positioning within the reproductive organ developmental pathway(s). In parallel, these clones are being exploited as developmental markers of early differentiation within the flower. 相似文献
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68.
We have isolated and characterized a mutant of temperate phage Mu-1 carrying an IS2 insertion in the middle of its β region. This mutant gives rise spontaneously to secondary mutants which have deletions of different sizes adjacent to IS2. One particular derivative however, was found to have acquired an additional insertion sequence adjacent to IS2. This derivative gave rise to tertiary mutants carryinh a deletion next to the tandem insertion. The tandem insertion was located at the same place in the Mu β region as another 2.6 kb insertion independently isolated by Chow et al. (1977) and was found to be homologous to that insertion. The properties of this particular secondary mutant show that Mu phage particles lacking their S end are defective for growth and lysogenisation. 相似文献
69.
70.
Corticotropin-releasing factor stimulates adenylate cyclase activity in the anterior pituitary gland
Ovine corticotropin-releasing factor (CRF) stimulates adenylate cyclase activity in rat anterior pituitary homogenate at an ED50 value of 70 nM. GTP increases the stimulatory effect of CRF on [32P] cyclic AMP formation in a rat adenohypophysial particulate fraction and in bovine anterior pituitary plasma membranes. The present data show that CRF stimulates adenylate cyclase activity in the anterior pituitary gland at least partly through a guanyl nucleotide-dependent mechanism. 相似文献