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81.
18S rRNA data indicate that Aschelminthes are polyphyletic in origin and consist of at least three distinct clades 总被引:7,自引:1,他引:6
Winnepenninckx B; Backeljau T; Mackey LY; Brooks JM; De Wachter R; Kumar S; Garey JR 《Molecular biology and evolution》1995,12(6):1132-1137
The Aschelminthes is a collection of at least eight animal phyla,
historically grouped together because the absence of a true body cavity was
perceived as a pseudocoelom. Analyses of 18S rRNA sequences from six
Aschelminth phyla (including four previously unpublished sequences) support
polyphyly for the Aschelminthes. At least three distinct groups of
Aschelminthes were detected: the Priapulida among the protostomes, the
Rotifera-Acanthocephala as a sister group to the protostomes, and the
Nematoda as a basal group to the triploblastic Eumetazoa.
相似文献
82.
Familial apolipoprotein A-I and C-III deficiency, variant II 总被引:8,自引:0,他引:8
E J Schaefer J M Ordovas S W Law G Ghiselli M L Kashyap L S Srivastava W H Heaton J J Albers W E Connor F T Lindgren 《Journal of lipid research》1985,26(9):1089-1101
The biochemical, clinical, and genetic features were examined in the proband (homozygote) and heterozygotes (n = 17) affected with familial apolipoprotein A-I and C-III deficiency, variant II (previously described as apolipoprotein A-I absence). The proband was a 45-year-old white female with mild corneal opacification and significant three-vessel coronary artery disease (CAD), who died shortly after bypass surgery. Autopsy findings included significant atherosclerosis in the coronary and pulmonary arteries and the abdominal aorta as well as extracellular stromal lipid deposition in the cornea. No reticuloendothelial lipid deposits in the liver, bone marrow, or spleen were noted (unlike Tangier disease). Laboratory features included marked high density lipoprotein (HDL) deficiency and undetectable plasma apolipoproteins (apo) A-I and C-III. The percentage of plasma cholesterol in the unesterified form was normal at 30%. The activity and mass of lecithin:cholesterol acyltransferase (LCAT) were 42% and 36% of normal, respectively, and the cholesterol esterification rate was 43% of normal. Deficiencies of plasma vitamin E and essential fatty acid (linoleic, C18:2) were also noted. Evaluation of plasma lipoproteins and apolipoproteins in 37 kindred members revealed 17 heterozygotes with HDL cholesterol values below the 10th percentile of normal. Of these, all had apoA-I levels more than one standard deviation below the normal mean, and 37.5% had a similar decrease in apoC-III values. Mean (+/- SD) plasma HDL cholesterol, apoA-I, and apoC-III values (mg/dl) in heterozygotes were 54.0%, 62.4%, and 79.2% of normal, respectively. No evidence of CAD was observed in 10 heterozygotes 40 years of age or less; however, CAD was detected in 3 of 7 heterozygotes over 40 years of age, one of whom died at age 56 years of complications of myocardial infarction and stroke. The inheritance pattern in this kindred was autosomal codominant. ApoA-I isolated from a heterozygote had an isoelectric focusing pattern and amino acid composition similar to normal. Utilizing DNA isolated from two obligate heterozygotes, no abnormalities in the apoA-I or apoC-III genes were detected by Southern blot analysis utilizing specific probes following restriction enzyme digestion. The data indicate that familial apolipoprotein A-I and C-III deficiency, variant II, is similar to variant I (described by Norum et al. 1982. N. Engl. J. Med. 306: 1513-1519), but differs at the clinical level (lack of xanthomas), the biochemical level (lack of detectable apoA-I, lower apoA-II level), and at the gene level.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
83.
Castanospermine inhibits glucosidase I and glycoprotein secretion in human hepatoma cells. 总被引:2,自引:1,他引:1 下载免费PDF全文
We studied the effect of the plant alkaloid castanospermine on the biosynthesis and secretion of human hepatoma glycoproteins. The HepG-2 cells, grown in the presence or absence of the alkaloid, were labelled with [2-3H]mannose and then the labelled glycopeptides were prepared by Pronase digestion. This material was analysed by gel filtration on Bio-Gel P-4 before and after treatment with endo-beta-N-acetylglucosaminidase H. Castanospermine caused an accumulation of high-mannose oligosaccharides, by 70-75% over control. The major accumulated product, which could also be labelled with [3H]galactose and was only partially susceptible to alpha-mannosidase digestion, was identified by h.p.l.c. as a Glc3Man9GlcNAc. Thus the alkaloid inhibits glucosidase I in the human hepatoma cells. Analysis of total glycoproteins secreted by the cells into the medium revealed the presence of only complex oligosaccharides in both control and treated cultures, and the amount of the oligosaccharides labelled with radioactive mannose, galactose or N-acetylmannosamine, secreted by treated cells, was decreased by about 60%. The rate of secretion of total protein labelled with [35S]methionine and precipitated from the medium with trichloroacetic acid was inhibited by up to 40% in the presence of castanospermine. Pulse-chase studies utilizing [35S]methionine labelling were performed to study the effect of the alkaloid on secretion of individual plasma proteins. Immunoprecipitation at different chase times with monospecific antisera showed that castanospermine markedly decreased the secretion rates of alpha 1-antitrypsin, caeruloplasmin and, to a lesser extent, that of antithrombin-III. Secretions of apolipoprotein E, a glycoprotein containing only O-linked oligosaccharide(s), and albumin, a non-glycosylated protein, were not affected by the drug. It is suggested that castanospermine inhibits secretion of at least some glycoproteins containing N-linked oligosaccharides, owing to the inhibition of oligosaccharide processing. 相似文献
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Caccone A; Moriyama EN; Gleason JM; Nigro L; Powell JR 《Molecular biology and evolution》1996,13(9):1224-1232
Drosophila melanogaster belongs to a closely related group of eight species
collectively known as the melanogaster subgroup; all are native to
sub-Saharan Africa and islands off the east coast of Africa. The
phylogenetic relationships of most species in this subgroup have been well
documented; however, the three most closely related species, D. simulans,
D. sechellia, and D. mauritiana, have remained problematic from a
phylogenetic standpoint as no data set has unambiguously resolved them. We
present new DNA sequence data on the nullo and Serendipity-alpha genes and
combine them with all available nuclear DNA sequence data; the total data
encompass 12 genes and the ITS of rDNA. A methodological problem arose
because nine of the genes had information on intraspecific polymorphisms in
at least one species. We explored the effect of inclusion/exclusion of
polymorphic sites and found that it had very little effect on phylogenetic
inferences, due largely to the fact that 82% of polymorphisms are
autapomorphies (unique to one species). We have also reanalyzed our
previous DNA-DNA hybridization data with a bootstrap procedure. The
combined sequence data set and the DNA-DNA hybridization data strongly
support the sister status of the two island species, D. sechellia and D.
mauritiana. This at least partially resolves what had been a paradox of
parallel evolution in these two species.
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87.
INTRoDUCTIoNlYho1iumrePensL,whiteclover,isaneconomicallyimportantplantspeciesintemperatepastures.Asbrieflyreportedby[1],ithas16pairsofchromosomes(2n=32).Asyet,nodetailedcytologicalexaminationofthisspecies,suchasC-banding,hasbeenrep0rted.Inthelastdecade,thetechnique0fC-bandinghasbeenusedt0examinehighlyrepeatedsequencesinplantchrom0s0mesandhasprovidedausefultoolf0rtheanalysis0fcyt0geneticstructureincr0pplants[2-71.Inplants,thechr0m0s0mall0calizationofhighlyrepeatedDNAsequencesbyinsituhybr… 相似文献
88.
The period (per) locus has received much attention in molecular evolution
studies because it is one of the best studied "behavioral genes" and
because it offers insight into the evolution of repetitive sequences. We
studied most of the coding region of per in Drosophila willistoni and
confirmed previously observed patterns of conservation and divergence among
distantly related species. Five regions are so highly diverged that they
cannot be aligned, whereas a region encompassing the PAS domain is very
conserved. Structural and nucleotide polymorphism patterns in the
willistoni group are not the same as those observed in previously studied
species. We sequenced the region homologous to the highly polymorphic
threonine-glycine repeat of D. melanogaster in multiple strains of D.
willistoni, as well as in other members of willistoni group, and found an
unusual amount of conservation in this region. However, the next
nonconserved region downstream in the sequence is quite variable and
polymorphic for the number of repeated glycines. The glycine codon usage is
significantly different in this glycine repeat as compared to other parts
of the gene. We were able to plot the directionality of change in the
glycine repeat region onto a phylogeny and find that the addition of
glycines is the general trend with the diversification of the willistoni
group.
相似文献
89.
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Eva Talavera-Garcia Javier Delgado-Lista Antonio Garcia-Rios Nieves Delgado-Casado Purificacion Gomez-Luna Angela Gomez-Gardu?o Francisco Gomez-Delgado Juan F. Alcala-Diaz Elena Yubero-Serrano Carmen Marin Ana I. Perez-Caballero Francisco J. Fuentes-Jimenez Antonio Camargo Fernando Rodriguez-Cantalejo Francisco J. Tinahones Jose M. Ordovas Francisco Perez- Jimenez Pablo Perez-Martinez Jose Lopez-Miranda 《PloS one》2016,11(6)