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The cDNA cloning and molecular evolution of reptile and pigeon lactate dehydrogenase isozymes 总被引:1,自引:0,他引:1
The cDNAs encoding lactate dehydrogenase isozymes LDH-A (muscle) and LDH-B
(heart) from alligator and turtle and LDH-A, LDH-B, and LDH-C (testis) from
pigeon were cloned and sequenced. The evolutionary relationships among
vertebrate LDH isozymes were analyzed. Contrary to the traditional belief
that the turtle lineage branched off before the divergence between the
lizard/alligator and bird lineages, the turtle lineage was found to be
clustered with either the alligator lineage or the alligator-bird clade,
while the lizard lineage was found to have branched off before the
divergence between the alligator/turtle and bird lineages. The pigeon
testicular LDH-C isozyme was evidently duplicated from LDH-B (heart), so it
is not orthologous to the mammalian testicular LDH-C isozymes.
相似文献
23.
Bias-corrected paralinear and LogDet distances and tests of molecular clocks and phylogenies under nonstationary nucleotide frequencies 总被引:10,自引:9,他引:1
The statistical properties of the paralinear and LogDet distances under
nonstationary nucleotide frequencies were studied. First, we developed
formulas for correcting the estimation biases of the paralinear and LogDet
distances, i.e., the bias-corrected distance is estimated by dc = d -
2var(d), where d and var(d) are the estimated distance and sampling
variance, respectively. The performances of these formulas and the formulas
for sampling variances were examined by computer simulation. Second, we
developed a method for estimating the variance- covariance matrix of
paralinear distances, so that statistical tests of DNA phylogenies can be
conducted in the nonstationary case. Third, a new LogDet-based method for
testing the molecular clock hypothesis was developed under nonstationary
nucleotide frequencies.
相似文献
24.
Caffeoyl-coenzyme A (CoA) O-methyltransferase (CCoAOMT) has been proposed to be involved in an alternative methylation pathway of lignin biosynthesis. However, no direct evidence has been available to confirm that CCoAOMT is essential for lignin biosynthesis. To understand further the methylation steps in lignin biosynthesis, we used an antisense approach to alter O-methyltransferase (OMT) gene expression and investigated the consequences of this alteration. We generated transgenic tobacco plants with a substantial reduction in CCoAOMT as well as plants with a simultaneous reduction in both CCoAOMT and caffeic acid O-methyltransferase (CAOMT). Lignin analysis showed that the reduction in CCoAOMT alone resulted in a dramatic decrease in lignin content. The reduction in CCoAOMT also led to a dramatic alteration in lignin composition. Both guaiacyl lignin and syringyl lignin were reduced in the transgenic plants. However, guaiacyl lignin was preferentially reduced, which resulted in an increase in the S/G (syringl/guaiacyl) ratio. We have also analyzed lignin content and composition in transgenic plants having a simultaneous reduction in both CCoAOMT and CAOMT. The reduction in both OMTs resulted in a further decrease in total lignin content. This is in sharp contrast to the effect that resulted from the reduction in CAOMT alone, which only decreased the syringl lignin unit without a reduction in overall lignin content. These results unequivocally demonstrate that methylation reactions in lignin biosynthesis are catalyzed by both CCoAOMT and CAOMT. 相似文献
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Peter Sörös Faisal Al-Otaibi Savio WH Wong J Kevin Shoemaker Seyed M Mirsattari Vladimir Hachinski Ruth E Martin 《BMC neurology》2011,11(1):20
Background
Various functional resonance imaging, magnetoencephalographic and lesion studies suggest the involvement of the insular cortex in the control of swallowing. However, the exact location of insular activation during swallowing and its functional significance remain unclear. 相似文献27.
Population regulation of brook trout (Salvelinus fontinalis) in Hunt Creek,Michigan: a 50‐year study
GARY D. GROSSMAN ANDREW NUHFER TROY ZORN GARY SUNDIN GAYLORD ALEXANDER 《Freshwater Biology》2012,57(7):1434-1448
1. Fisheries models generally are based on the concept that strong density dependence exists in fish populations. Nonetheless, there are few examples of long‐term density dependence in fish populations. 2. Using an information theoretical approach (AIC) with regression analyses, we examined the explanatory power of density dependence, flow and water temperature on the per capita rate of change and growth (annual mean total length) for the whole population, adults, 1+ and young‐of‐the‐year (YOY) brook trout (Salvelinus fontinalis) in Hunt Creek, Michigan, USA, between 1951 and 2001. This time series represents one of the longest quantitative population data sets for fishes. 3. Our analysis included four data sets: (i) Pooled (1951–2001), (ii) Fished (1951–65), (iii) Unfished (1966–2001) and (iv) Temperature (1982–2001). 4. Principle component analyses of winter flow data identified a gradient between years with high mean daily winter flows, high daily maximum and minimum flows and frequent high flow events, and years with an opposite set of flow characteristics. Flows were lower during the Fished Period than during the Unfished Period. Winter temperature analyses elucidated a gradient between warm mean, warm minimum and maximum daily stream temperatures and a high number of minimum daily temperatures >6.1 °C, and years with the opposite characteristics. Summer temperature analyses contrasted years with warm summer stream temperatures vs years with cool summer stream temperatures. 5. Both YOY and adult densities varied several‐fold during the study. Regression analysis did not detect a significant linear or nonlinear stock–recruitment relationship. AIC analysis indicated that density dependence was present in 15 of 16 cases (four population segments × four data sets) for both per capita rate of increase (wi values 0.46–1.00) and growth data (wi values 0.28–0.99). The almost ubiquitous presence of density dependence in both population and growth data is concordant with results from other trout populations and other studies in Michigan. 相似文献
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D Montoya C Arévalo S Gonzales F Aristizabal WH Schwarz 《Journal of industrial microbiology & biotechnology》2001,27(5):329-335
Thirteen new Clostridium strains, previously isolated from soil and found to produce high amounts of solvents from glucose, hydrolyzed a great variety
of α- and β-glycans, including raw starch, xylan, pectin, inulin and cellulose. The sequences of the PCR-amplified DNA fragments
containing the variable 3′ part of one of the 16S rRNA genes were 99.5% identical. The macrorestriction pattern of two endonucleolytic
digests of chromosomal DNA in the pulsed-field gel electrophoresis (PFGE) confirmed their high homogeneity on the DNA level.
The complete 16S rRNA gene sequence of three selected strains was 99.8% identical to the 16S rRNA gene sequence from Clostridium butyricum and separates them from C. acetobutylicum. To the closely related four species of solventogenic clostridia a new group of strains has to be added, which has a great
potential for the direct fermentation of biomass.
Journal of Industrial Microbiology & Biotechnology (2001) 27, 329–335.
Received 12 September 2000/ Accepted in revised form 25 July 2001 相似文献
29.
Background
In proteomics experiments, database-search programs are the method of choice for protein identification from tandem mass spectra. As amino acid sequence databases grow however, computing resources required for these programs have become prohibitive, particularly in searches for modified proteins. Recently, methods to limit the number of spectra to be searched based on spectral quality have been proposed by different research groups, but rankings of spectral quality have thus far been based on arbitrary cut-off values. In this work, we develop a more readily interpretable spectral quality statistic by providing probability values for the likelihood that spectra will be identifiable. 相似文献30.