Study On The Development Of Hatching Gland And The Biochemical Characteristics Of Hatching Enzyme Of Misgurnus Anguillicandatus

This paper deals with the hatching gland cells (HGC) and hatching enzyme (HE) of Misgurnus anguillicaudatus.The development of the HGC was examined in the embryo of Misgurnus anguillicaudatus. Histological examination of the HGC revealed that they first became differentiated on neural plate stage. The oval-like HGC is located on anterior end of yolk sac's surface where the endoderm wall of the pharyngeal will be developed from. Thus it can be certain that HGC of Misgurnus anguillicaudatus origin from endoderm. At auditory vesicle stage, it was found in mesoderm that HGCs were arranged in rows and filled with enzyme granules. At muscular effect stage and pre-hatching stage, the number of HGC increased greatly and mainly concentrated on the ventral part of the head and around the eye socket. Some were filled with enzyme granules, others were emptied already. At the same stage, HGC was observed in ectoderm. At the hatching stage and post-hatching stage, most HGC were emptied and began to degenerate. From 24 hours to 48 hours after hatching , most HGC degenerated and disappeared. Further more, the final location of HGC were the wall of pharyngeal cavity, upper jaw and lower jaw. Nevertheless, HGC was not found in posterior part of body.The hatching enzyme was purified and its molecular weight was identified through Sephadex-G-100 column chromatography, PAGE and SDS-PAGE, the result revealed that the HE consist of two ingredients named HE1 and HE2, respectively, and their molecular weight were 75 kDa and 80 kDa respectively. Moreover, the HE activity was examined based on the revised kunitz method and the relative activity varied from 2.7 g-1min-1 to 3.2 g-1min-1. In addition, effect of temperature variation on HE activity was studied. The result indicated optimal temperature for HE activity was 28 and its activity was restrained when the temperature lower than 10 or higher than 35 . The relationship between HE activity and pH was also examined. The result revealed the optimal pH was 7.8~8.2 for HE activity and if pH were below 6.5 or over 8.5, the activity of HE would be restrained greatly.