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91.
Molecular evolution of mitochondrial 12S RNA and cytochrome b sequences in the pantherine lineage of Felidae 总被引:4,自引:2,他引:2
DNA sequence comparisons of two mitochondrial DNA genes were used to infer
phylogenetic relationships among 17 Felidae species, notably 15 in the
previously described pantherine lineage. The polymerase chain reaction
(PCR) was used to generate sequences of 358 base pairs of the mitochondrial
12S RNA gene and 289 base pairs of the cytochrome b protein coding gene.
DNA sequences were compared within and between 17 felid and five nonfelid
carnivore species. Evolutionary trees were constructed using phenetic,
cladistic, and maximum likelihood algorithms. The combined results
suggested several phylogenetic relationships including (1) the recognition
of a recently evolved monophyletic genus Panthera consisting of Panthera
leo, P. pardus, P. onca, P. uncia, P. tigris, and Neofelis nebulosa; (2)
the recent common ancestry of Acinonyx jubatus, the African cheetah, and
Puma concolor, the American puma; and (3) two golden cat species, Profelis
temmincki and Profelis aurata, are not sister species, and the latter is
strongly associated with Caracal caracal. These data add to the growing
database of vertebrate mtDNA sequences and, given the relatively recent
divergence among the felids represented here (1-10 Myr), allow 12S and
cytochrome b sequence evolution to be addressed over a time scale different
from those addressed in most work on vertebrate mtDNA.
相似文献
92.
Sea urchin Hox genes: insights into the ancestral Hox cluster 总被引:3,自引:0,他引:3
We describe the Hox cluster in the radially symmetric sea urchin and
compare our findings to what is known from clusters in bilaterally
symmetric animals. Several Hox genes from the direct-developing sea urchin
Heliocidaris erythrogramma are described. CHEF gel analysis shows that the
Hox genes are clustered on a < or = 300 kilobase (kb) fragment of DNA,
and only a single cluster is present, as in lower chordates and other
nonvertebrate metazoans. Phylogenetic analyses of sea urchin, amphioxus,
Drosophila, and selected vertebrate Hox genes confirm that the H.
erythrogramma genes, and others previously cloned from other sea urchins,
belong to anterior, central, and posterior groups. Despite their radial
body plan and lack of cephalization, echinoderms retain at least one of the
anterior group Hox genes, an orthologue of Hox3. The structure of the
echinoderm Hox cluster suggests that the ancestral deuterostome had a Hox
cluster more similar to the current chordate cluster than was expected Sea
urchins have at least three Abd-B type genes, suggesting that Abd-B
expansion began before the radiation of deuterostomes.
相似文献
93.
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95.
Gennady V. Pogorelko Sekhar Kambakam Trevor Nolan Andrew Foudree Olga A. Zabotina Steven R. Rodermel 《PloS one》2016,11(4)
The immutans (im) variegation mutation of Arabidopsis has green- and white- sectored leaves due to action of a nuclear recessive gene. IM codes for PTOX, a plastoquinol oxidase in plastid membranes. Previous studies have revealed that the green and white sectors develop into sources (green tissues) and sinks (white tissues) early in leaf development. In this report we focus on white sectors, and show that their transformation into effective sinks involves a sharp reduction in plastid number and size. Despite these reductions, cells in the white sectors have near-normal amounts of plastid RNA and protein, and surprisingly, a marked amplification of chloroplast DNA. The maintenance of protein synthesis capacity in the white sectors might poise plastids for their development into other plastid types. The green and white im sectors have different cell wall compositions: whereas cell walls in the green sectors resemble those in wild type, cell walls in the white sectors have reduced lignin and cellulose microfibrils, as well as alterations in galactomannans and the decoration of xyloglucan. These changes promote susceptibility to the pathogen Pseudomonas syringae. Enhanced susceptibility can also be explained by repressed expression of some, but not all, defense genes. We suggest that differences in morphology, physiology and biochemistry between the green and white sectors is caused by a reprogramming of leaf development that is coordinated, in part, by mechanisms of retrograde (plastid-to-nucleus) signaling, perhaps mediated by ROS. We conclude that variegation mutants offer a novel system to study leaf developmental programming, cell wall metabolism and host-pathogen interactions. 相似文献
96.
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98.
Free rectus abdominis muscle flap reconstruction of the middle and posterior cranial base 总被引:3,自引:0,他引:3
A multidisciplinary approach by the neurosurgeon, ENT surgeon, and plastic surgeon has been used in seven patients with extensive tumors involving the middle and posterior skull base. Wide resection of these tumors was accomplished, and the resultant defect of the cranial base was reconstructed using free rectus abdominis muscle flaps. The free muscle flap has been used to reconstruct defects in the posterior and lateral walls of the nasopharynx, obliterate the exposed paranasal sinuses, and cover tenuous dural repairs or dural grafts overlying the temporal lobe and posterior fossa to prevent cerebrospinal fluid leakage and ascending meningitis. 相似文献
99.
Pseudomonas aeruginosa diaminopimelate decarboxylase: evolutionary relationship with other amino acid decarboxylases 总被引:1,自引:0,他引:1
Martin C; Cami B; Yeh P; Stragier P; Parsot C; Patte JC 《Molecular biology and evolution》1988,5(5):549-559
The lysA gene encodes meso-diaminopimelate (DAP) decarboxylase
(E.C.4.1.1.20), the last enzyme of the lysine biosynthetic pathway in
bacteria. We have determined the nucleotide sequence of the lysA gene from
Pseudomonas aeruginosa. Comparison of the deduced amino acid sequence of
the lysA gene product revealed extensive similarity with the sequences of
the functionally equivalent enzymes from Escherichia coli and
Corynebacterium glutamicum. Even though both P. aeruginosa and E. coli are
Gram-negative bacteria, sequence comparisons indicate a greater similarity
between enzymes of P. aeruginosa and the Gram- positive bacterium C.
glutamicum than between those of P. aeruginosa and E. coli enzymes.
Comparison of DAP decarboxylase with protein sequences present in data
bases revealed that bacterial DAP decarboxylases are homologous to mouse
(Mus musculus) ornithine decarboxylase (E.C.4.1.1.17), the key enzyme in
polyamine biosynthesis in mammals. On the other hand, no similarity was
detected between DAP decarboxylases and other bacterial amino acid
decarboxylases.
相似文献
100.
The binding of NAD+ to liver alcohol dehydrogenase was studied by stopped-flow techniques in the pH range from 6.1 to 10.9 at 25 degrees C. Varying the concentrations of NAD+ and a substrate analogue used to trap the enzyme-NAD+ complex gave saturation kinetics. The same maximum rate constants were obtained with or without the trapping agent and by following the reaction with protein fluorescence or absorbance of a ternary complex. The data fit a mechanism with diffusion-controlled association of enzyme and NAD+, followed by an isomerization with a forward rate constant of 500 s-1 at pH 8: E E-NAD+ *E-NAD+. The isomerization may be related to the conformational change determined by X-ray crystallography of free enzyme and enzyme-coenzyme complexes. Overall bimolecular rate constants for NAD+ binding show a bell-shaped pH dependence with apparent pK values at 6.9 and 9.0. Acetimidylation of epsilon-amino groups shifts the upper pK to a value of 11 or higher, suggesting that Lys-228 is responsible for the pK of 9.0. Formation of the enzyme-imidazole complex abolishes the pK value of 6.9, suggesting that a hydrogen-bonded system extending from the zinc-bound water to His-51 is responsible for this pK value. The rates of isomerization of E-NAD+ and of pyrazole binding were maximal at pH below a pK of about 8, which is attributable to the hydrogen-bonded system. Acetimidylation of lysines or displacement of zinc-water with imidazole had little effect on the rate of isomerization of the E-NAD+ complex.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献