Trypsin-like Hatching Enzyme of Mouse Blastocysts: Evidence for Its Participation in Hatching Process before Zona Shedding of Embryos : (embryo/hatching enzyme/protease/trypsin/strypsin).

Effects of twelve protease inhibitors on hatching of mouse embryos were investigated. Mouse hatching was strongly or moderately inhibited by trypsin inhibitors including p-toluenesulfonyl-Lys-CH Cl (TLCK) and chicken ovomucoid, while inhibitors for chymotrypsin and elastase showed weak or no inhibition. These results indicate the participation of a trypsin-like protease in the hatching of mouse embryos as a hatching enzyme.

Inhibition of Mouse Blastocyst Hatching by Subsite-Specific Trypsin Inhibitors, Peptidyl Argininals.

To explore the substrate or subsite specificity of a mouse hatching enzyme, effects of leupeptin [acetyl(P )-Leu(P )-Leu(P )-argininal(P )] and its analogs (peptidyl argininals) on mouse blastocyst hatching were investigated. The compounds containing benzyloxycarbonyl group (Z) in the P position inhibited the hatching more strongly than those containing acetyl group or unprotected N-terminal amino acid. Among five Z-Leu-P -argininals, a derivative containing a P Ser residue was the most potent inhibitor, and the derivatives containing Leu, Thr, Pro, and Gly in the P position followed in this order.

CELL CYCLE STUDY UP TO THE TIME OF HATCHING IN THE EMBRYOS OF THE SEA URCHIN, HEMICENTROTUS PULCHERRIMUS.

Cell cycles have been analyzed in 10 divisions up to the time of hatching in the embryos of the sea urchin, Hemicentrotus pulcherrimus. In the first 5 cleavages, division synchrony is very high. On the average, T = 55.

CHANGES OF CHROMOSOMES DURING THE EARLY NEURAL DEVELOPMENT OF A JAPANESE NEWT, CYNOPS PYRRHOGASTER.

The karyotype of Cynops pyrrhogaster was determined on the mitotic chromosomes in the presumptive neural area of an early gastrula. 24 chromosomes of a diploid set consisted of 8 metacentric and 4 submetacentric pairs. Individual chromosomes were identified on the basis of their morphology and characteristic C-binding patterns.