Characterization of the ßγ-crystallin domains of ßγ-CAT, a non-lens ßγ-crystallin and trefoil factor complex, from the skin of the toad Bombina maxima.

ßγ-CAT is a naturally existing 72-kDa complex of a non-lens ßγ-crystallin (α-subunit, CAT-α) and a trefoil factor (ß-subunit, CAT-ß) that contains a non-covalently linked form of αß(2) and was isolated from the skin secretions of the toad Bombina maxima. The N-terminal region of CAT-α (CAT-αN, residues 1-170) contains two ßγ-crystallin domains while the C-terminal region (CAT-αC) has sequence homology to the membrane insertion domain of the Clostridium perfringens epsilon toxin. To examine the biochemical characteristics of the ßγ-crystallin domains of ßγ-CAT, CAT-αN, CAT-αC and CAT-ß were expressed in Escherichia coli. Co-immunoprecipitation of the naturally assembled ßγ-CAT confirmed that the CAT-α and CAT-ß complex always exists. Furthermore, recombinant CAT-ß bound recombinant CAT-αN. Ca(2+)-binding motifs were identified in CAT-αN, and recombinant CAT-αN was able to bind the calcium probe terbium. However, the conformation of CAT-αN was not significantly altered upon Ca(2+) binding. ßγ-CAT possesses strong hemolytic activity toward human erythrocytes, and treatment of erythrocytes with ßγ-CAT resulted in a rapid Ca(2+) influx, eventually leading to hemolysis. However, in the absence of extracellular Ca(2+), no significant hemolysis was detected, even though the binding and oligomerization of ßγ-CAT in the erythrocyte membrane was observed. Our data demonstrate the binding of CAT-ß (a trefoil factor) to CAT-αN (ßγ-crystallin domains) and provide a basis for the formation of a ßγ-crystallin and trefoil factor complex in vivo. Furthermore, the ßγ-crystallin domains of ßγ-CAT are able to bind Ca(2+), and ßγ-CAT-induced hemolysis is Ca(2+) dependent.

[Detection and comparison of physiological indexes in the wild and laboratory tree shrew].

To provide fundamental basis for the tree shrew models of human diseases, we examined and compared the physiological and biochemical indexes between wild and laboratory tree shrews. Blood samples were taken from 54 wild tree shrews that were housed in laboratory for 1-2 months, and from 54 first-generation of the laboratory tree shrews; each group had nearly equal male and female composition. Some of the first reported physiological and biochemical indexes were showed no significant differences between genders, and these indexes in laboratory tree shrews were as follows [medium (inter-quartile range) ]: CK 1449 (956) U/L, CTNI 5.94 (7.23) ug/L, TBA15.6 (19.7) µmol/L, FRUC 393.5 (80.8) µmol/L and LDL-C0.36 (0.32); and in the wild tree shrews, 986 (564) U/L, 4.01 (4.10) µg/L, 20.0 (20.6) µmol/L, 379.0 (104.0) µmol/L and 0.46 (0.23) mmol/L, respectively. In the laboratory tree shrews, the variations of physiological and biochemical indexes were smaller, but the mean values of some indicators related to liver and heart functions became higher. These data would be valuable for the development of tree shrew models of human diseases.