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241.
One major parvalbumin each was isolated from the skeletal muscle of two
reptiles, a boa snake, Boa constrictor, and a map turtle, Graptemys
geographica, while two parvalbumins were isolated from an amphibian, the
salamander Amphiuma means. The amino acid sequences of all four
parvalbumins were determined from the sequences of their tryptic peptides,
which were ordered partially by homology to other parvalbumins.
Phylogenetic study of these and 16 other parvalbumin sequences revealed
that the turtle parvalbumin belongs to beta lineage, while the salamander
sequences belong, one each, to the alpha and beta lineages defined by
Goodman and Pechere (1977). Boa parvalbumin, however, while belonging to
the beta lineage, clusters within the fish in all reasonably parsimonious
trees. The most parsimonious trees show many parallel or back mutations in
the evolution of many parvalbumin residues, although the residues
responsible for Ca2+ binding are very well conserved. These most
parsimonious trees show an actinopterygian rather than a crossoptyrigian
origin of the tetrapods in both the alpha and beta groups. One of two
electric eel parvalbumins is evolving more than 10 times faster than its
paralogous partner, suggesting it may be on its way to becoming a
pseudogene. It is concluded that varying rates of amino acid replacement,
much homoplasy, considerable gene duplication, plus complicated lineages
make the set of parvalbumin sequences unsuitable for systematic study of
the origin of the tetrapods and other higher-taxa divergence, although it
may be suitable within a genus or family.
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The concentrations of alpha-, beta- and gamma-endorphin were determined by radioimmunoassay in HPLC fractionated extracts of post mortem hypothalamic tissue obtained from schizophrenic patients and controls. The hypothalamic concentration of alpha- and gamma-endorphin was significantly higher in patients than in controls (+72.9% and +50.5% respectively). No difference was found in the concentration of beta-endorphin, the putative precursor of alpha- and gamma-endorphins. These results suggest a deviant metabolism of beta-endorphin in the brain of schizophrenic patients. Whether this phenomenon is related to the psychopathology, or is a consequence of ante mortem farmacotherapy, remains to be established. 相似文献