Purification and properties of human placental aminopeptidase B.

Aminopeptidase B (EC 3.4.11.6; L-arginyl-beta-naphthylamidase) was purified 1,800-fold from human placental cytoplasm and characterized. The enzyme was subjected to ammonium sulfate fractionation and a series of chromatographies on DE-52, hydroxylapatite, Bio-gel A 0.5 m and L-arginine-Sepharose. The native molecular mass of the enzyme was estimated to be 220,000 by gel filtration. The molecular mass was estimated to be about 83,000 by SDS/PAGE in the absence of 2-mercaptoethanol, suggesting that the enzyme exists in a polymeric form. The isoelectric point of the enzyme was 5.4. The purified enzyme was most active at pH 7.2 with L-arginyl-beta-naphthylamide as substrate and the Km value for this enzyme was 0.3 mmol/l. Human placental aminopeptidase B was markedly activity by Cl-. Bestatin and arphamenin, low molecular weight peptides, showed appreciable inhibition of this enzyme. However, amastatin and puromycin did not inhibit the enzyme. Bacitracin markedly activated this enzyme.     

Inter- and intra-population variations in diapause attribute of the two-spotted spider mite,Tetranychus urticae Koch,in Japan

Populations of the two-spotted spider mite, Tetranychus urticae Koch collected from various localities and from various host plants in Japan showed wide variations in diapause attribute. Diapause percentages at 18°C/9L15D varied from nearly 100% in the north to 0% in the south-west. At intermediate latitudes the mites showed wide inter-population variations. Populations on herbaceous hosts in vinyl- or glass-houses gave significantly lower incidence of diapause than those on roses and deciduous fruit trees. Presence of winter hosts and better host quality under protected environments seemed to favour non-diapausing mites. The temperature threshold for diapause expression also varied widely among local populations. Northern populations consistently had higher and less variable thresholds than populations at intermediate latitudes with thresholds between 15 and 18°C. Inbred lines derived from a population in Kyoto exhibited a wide variation in diapause percentage at 18°C. These results show that diapause in T. urticae is a quantitative threshold trait and that populations in central Japan consist of a variety of genotypes with different diapause traits. This might provide a genetic source for adaptation to local and temporal variations in environmental conditions.     

A calcyclin-associated protein is a newly identified member of the Ca2+/phospholipid-binding proteins, annexin family.

A calcyclin-associated protein with an apparent molecular weight of 50,000 (CAP-50) was purified from rabbit lung. The procedure included ammonium sulfate precipitation, anion and cation ion-exchange, and calcyclin affinity chromatographies. Interestingly, partial amino acid sequences of lysyl-endpeptidase-digested fragments indicated that CAP-50 was a member of the Ca2+/phospholipid-binding proteins, the annexin family. The sequence of a proteolytic peptide with Staphylococcus aureus V8 protease on NH2-terminal region is not homologous with any other annexin family proteins. Phospholipid binding studies showed that CAP-50 bound to phosphatidylserine, phosphatidylethanolamine, phosphatidylinositol, and phosphatidic acid-containing vesicles, in a Ca(2+)-dependent manner. In the presence of Ca2+/calcyclin, CAP-50 formed a complex with calcyclin and bound to the PS-containing vesicles. The apparent Kd value of calcyclin for CAP-50 was calculated to be 1.61 x 10(-6) M. Zero-length cross-linking studies indicated that 1 mol of CAP-50 bound to an equimolar unit of calcyclin. CAP-50 inhibited the phospholipase A2 activity, dose-dependently (IC50 = 0.2 microM), however, calcyclin did not alter the inhibitory effect. With the 125I-calcyclin gel overlay method, calcyclin bound tightly to CAP-50 in a Ca(2+)-dependent manner after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. These results suggest that rabbit lung CAP-50 is a newly identified member of the annexin family. Ca2+/calcyclin apparently regulates the function of CAP-50 on cytosolic face of the plasma membrane.     

The hypotrophic axonopathy mutant in Japanese quail.

A new behavioral mutant showing either head or body quivering, or both, was found in Japanese quail. This trait was characterized by neurofilament deficiency in the axons of the cervical spinal cord and the optic and sciatic nerves and was named "hypotrophic axonopathy." This character was shown to be controlled by an autosomal recessive gene, for which the gene symbol hax was proposed.     

Estimation of the degree of self-fertilization in Porphyra yezoensis (Bangiales,Rhodophyta)

Crosses between genotypically distinct thalli of the monoecious species Porphyra yezoensis were carried out using immature thallus fragments from green- and red-type color mutants and also wild-type thalli. As the genes governing the mutants are monogenic, recessive to the wild-type, and belong to the same linkage group, the degree of self-fertilization could be estimated based on the pigmentation of the resultant diploid conchocelis. The degree of self-fertilization in the cross between the green-type and the wild-type was 48.5–55.0%, and in the cross between the red-type and the wild-type was 45.1–56.5%. In the cross between the green- and red-type mutants, the degree of self-fertilization was 46.0–54.5% when the green-type was the female parent, and was 44.8–55.6% when the red-type was the female parent.     

Cell-division inhibitor produced by a killer strain of cellular slime mold Polysphondylium pallidum

The killer strain CK-8 of cellular slime mold Polysphondylium pallidum produces a cell-division inhibitor, in addition to a killer factor. This inhibitor represses cell division of many strains and species of cellular slime molds, except CK-8 itself and its complementary mating-type strain. It is sensitive to both heat and trypsin, and capable of binding to Con A. Its apparent molecular mass is more than 100 kDa. Repression of cell division by this inhibitor is reversed by trypsin treatment of the cells.