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101.
Maria Luz Perez José Ramón Valverde Beatriz Batuecas Francisco Amat Roberto Marco Rafael Garesse 《Journal of molecular evolution》1994,38(2):156-168
From the cloned mitochondrial DNAs (mtDNAs) isolated from two bisexual species, one Mediterranean, Artemia salina, and one American, Artemia franciscana, and two parthenogenetic (diploid and tetraploid) strains of Artemia parthenogenetica collected in Spain, physical maps have been constructed and compared. They are extremely different among themselves, much more than the differences between Drosophila melanogaster and D. yakuba and in the same range of different mammalian species such as mouse/rat or man/cow. The nucleotide sequences of two regions of mtDNA encoding parts of the cytochrome c oxidase subunit I (COI) and cytochrome b (Cytb) genes have been determined in the two bisexual species and the two parthenogenetic strains. Comparisons of these sequences have revealed a high degree of divergence at the nucleotide level, averaging more than 15%, in agreement with the differences found in the physical maps. The majority of the nucleotide changes are silent and there is a strong bias toward transitions, with the CT substitutions being highly predominant. The evolutionary distance between the two Artemia parthenogenetica is high and there is no clear relationship with any of the bisexual species, including the one present nowadays in Spain. Using a combination of molecular (mtDNA) and morphological markers it is possible to conclude that all of these Artemia isolates should be actually considered as belonging to different species, even the two Artemia parthenogenetica diploidica and tetraploidica.On sabbatical leave from Departamento de Bioquímica, Facultad de Veterinaria, Universidad Complutense de Madridearly Italian artemiologists to designate the Medi-Beatriz Batuecas died in an accident during the Christmas holy days of 1988 after she had initiated this workCorrespondence to: R. Garesse 相似文献
102.
Victoriano Garre Francisco J. Murillo Santiago Torres-Martínez 《Molecular & general genetics : MGG》1994,244(3):278-286
A 5.6 kb DNA fragment from the fungus Phycomyces blakesleeanus has been cloned and sequenced. The fragment contains a gene that probably codes for the enzyme acetyl-coenzyme A synthetase (facA). The amino acid sequence deduced for the P. blakesleeanns protein is highly homologous to those of acetyl-coA-synthetases from other organisms. When placed under the control of a constitutive promoter from Aspergillus nidulans, the cloned gene complemented a facA mutation of this organism. In P. blakesleeanns, the expression of facA is induced by acetate. 相似文献
103.
Xavier Roig Isabel S. Novella Ernest Giralt David Andreu 《Letters in Peptide Science》1994,1(1):39-49
Summary The conformation of a peptide that represents antigenic site A of foot-and-mouth disease virus strain C-S8c1 (residues 136–156 of VP1; YTASARGDLAHLTTTHARHLP) has been studied by circular dichroism and compared with three analogs that reproduce amino acid substitutions at position 146 (HisArg, Gln or Asp) which affect antibody recognition. Four other peptides, incorporating replacements at position 147 predicted to maintain (LeuIle, Nle and Ala) or disrupt (LeuGly) helical structure at this site, have also been studied. In aqueous solution or in 4 M urea, the spectra of all eight peptides were typical of aperiodic conformation and independent of concentration or pH. However, upon addition of solvents such as methanol or hexafluoroisopropanol, spectral patterns evidenced significant levels (ca. 50%) of helical structure. The single residue substitutions at positions 146 and 147 caused minor to significant variations in the calculated amount of -helix of the peptides. An attempt to relate these changes in helical content to the antigenic behaviour of the peptides towards five monoclonal antibodies elicited with virus and mapping at site A could not find any straightforward correspondence between the two sets of results. The parent peptide and its His146Arg analog were also analyzed by circular dichroism in the presence of the Fab fragment of SD6, a monoclonal antibody mapping at site A and much less reactive with viruses carrying the referred mutation. Although a peptide-antibody interaction was evident from spectral changes, careful inspection of the difference spectra (peptide-Fab minus Fab) of both peptides failed to detect any significant distinction between them that could be attributed to their different immunoreactivity. While these findings do not necessarily conflict with previous reports that the interaction of antigenic site A with antibodies is mediated to some extent by the adoption of a helix structure, they suggest that, at least for C-serotype viruses, other structural features in addition to a helical conformation are critically involved in antigenic recognition. 相似文献
104.
Luís C. Duarte Alexandra P. Nobre Francisco M. Gírio M. T. Amaral-Collaço 《Biotechnology Techniques》1994,8(12):859-864
Summary The kinetic parameters of the yeastDebaryomyces hansenii grown in continous cultivation on D-xylose were determined by different methods. While the values obtained for μm by the steady state and the washout methods only gave a 3% difference, the determined Ks values by the steady state and the maximal biomass output methods led a to a 305% difference. The latter method was suggested
to overestimate the Ks value. 相似文献
105.
Renu Tuteja Narendra Tuteja Franco Lilliu Bruno Bembi Renzo Galanello Antonio Cao Francisco E. Baralle 《Human genetics》1994,94(3):314-315
We report a novel mutation in exon 9 of the glucocerebrosidase gene of a patient with Gaucher disease and of Sardinian origin. 相似文献
106.
Francisco José García José Carlos García-Gómez Jesús S. Troncoso Juan Lucas Cervera 《Polar Biology》1994,14(4):261-268
During the expedition “ANTARTIDA 9101”, organized by the Spanish Oceanographic Institute to the South Orkney Islands, four specimens of notaspidean gastropods were collected. Three of them have been identified as Bathyberthella antarctica Willan and Bertsch, 1987. However, one specimen, although externally similar to B. antarctica, had an internal anatomy exhibiting features that have enabled us to consider it to be a new genus and species. This new taxon is characterized by the presence of jaws without mandibular elements, and a vaginal gland that partially surrounds the distal region of the vaginal duct. In this paper the new genus and species is described. Additional anatomical data of the specimens of B. antarctica collected during the expedition are also included. 相似文献
107.
Enzymeimmunoassays (EIAs) for estrone conjugates (EC), pregnanediol-3-glucuronide (PDG), and C-19 and C-21 progesterone metabolites (C-19/C-21) were used to analyze urine samples from four nondomestic equid species, four tapir species, and two rhinoceros species in an attempt to identify if these assays could be used for diagnosing and monitoring pregnancy. The same urine samples were also analyzed for the presence of equine chorionic gonadotropin (eCG) activity, using a field dipstick test and a radioimmunoassay (RIA). The EC EIA was validated for three equid species and the Malayan tapir. Neither the PDG nor the C-19/C-21 EIAs were validated in any species evaluated. In equid species, the EC EIA demonstrated a specificity (the percentage of nonpregnant samples identified correctly) of 100% and a sensitivity (the percentage of pregnant samples identified correctly) of ≥ 88%. With the exception of the Grevy's zebra, the C-19/C-21 EIA showed a similar accuracy in identifying pregnant and nonpregnant equids. The PDG EIA was not sufficiently accurate to merit its use in equids or tapirs for pregnancy diagnosis. From the data collected, it appears analysis of a single urine by both the EC EIA and the C-19/C-21 EIA would be the best method of pregnancy detection during the last 2 trimesters of gestation, in equid species. In tapirs, the C-19/C-21 EIA was slightly more accurate for pregnancy diagnosis than the EC EIA. The C-19/C-21 EIA had a specificity of 93%, but a sensitivity of only 73% in tapir species. None of the EIAs evaluated demonstrated a sufficient specificity or sensitivity to be useful, as presently performed, for pregnancy diagnosis from a single sample in the black rhinoceros. The eCG dipstick used in this study did not prove a sufficiently reliable test for routine pregnancy in nondomestic equids. The eCG RIA results in the Przewalski's horses and the Hartman's mountain zebra were positive early in gestation, and indicate that gonadotropin analysis may be useful for pregnancy detection in these species. Only very low amounts of eCG activity was measured by the eCG RIA in the tapir and rhinoceros urine samples. © 1994 Wiley-Liss, Inc. 相似文献
108.
Gemma Fabris M. Pilar Marco Francisco Camps 《Archives of insect biochemistry and physiology》1994,27(2):77-87
The control of Spodoptera littoralis sex pheromone biosynthesis has been investigated with synthetic pheromone biosynthesis activating neuropeptide (PBAN) and different labeled tracers using an in vitro isolated gland system. Responsiveness of the glands to PBAN stimulation was impaired by careless tissue manipulation. The fact that PBAN is active in the isolated gland system suggests that this might be a target organ for this peptide in S. littoralis. As reported previously with Br-SOG extracts and intact females, label incorporation into the pheromone increased in glands treated with PBAN from all the precursors tested. However, the formation of labeled intermediates from d5E11–14:Acid also occurred in glands incubated in the absence of the peptide, but the amounts of d5Z9, E11–14:Acid were lower in PBAN treated glands than in controls. These results indicate that PBAN controls pheromone biosynthesis in S. littoralis by regulating the reduction of acyl moieties. © 1994 Wiley-Liss, Inc. 相似文献
109.
Molecular dynamics simulations of triclinic hen egg white lysozyme in aqueous solution were performed to calculate the intrinsic pKas of 14 ionizable residues. An all-atom model was used for both solvent and solute, and a single 180 ps simulation in conjunction with a Gaussian fluctuation analysis method was used. An advantage of the Gaussian fluctuation method is that it only requires a single simulation of the system in a reference state to calculate all the pKas in the protein, in contrast to multiple simulations for the free energy perturbation method. pKint shifts with respect to reference titratable residues were evaluated and compared to results obtained using a finite difference Poisson-Boltzmann (FDPB) method with a continuum solvent model; overall agreement with the direction of the shifts was generally observed, though the magnitude of the shifts was typically larger with the explicit solvent model. The contribution of the first solvation shell to the total charging free energies of the titratable groups was explicitly evaluated and found to be significant. Dielectric shielding between pairs of titratable groups was examined and found to be smaller than expected. The effect of the approximations used to treat the long-range interactions on the pKint shifts is discussed. © 1994 Wiley-Liss, Inc. 相似文献
110.
Rosario Haro María A. Bañuelos Francisco J. Quintero Francisco Rubio Alonso Rodríguez-Navarro 《Physiologia plantarum》1993,89(4):868-874
A yeast strain carrying disruptions in TRK1 and ENA genes was very sensitive to Na+ because uptake discriminated poorly between K+ and Na+ , and Na+ efflux was insignificant. Transformation with TRK1 and ENA1 restored discrimination, Na+ efflux and Na+ tolerance. Increasing external Ca2+ increased Na+ tolerance almost in the same proportion in TRK1 enal cells and in trkl ENAI cells, suggesting an unspecific effect of this cation. By using a vacuolar ATPase mutant, the role of the vacuole in Na+ tolerance was also demonstrated. The yeast model of Na+ exclusion and Na+ tolerance may be extended to plants. 相似文献