Whole specimens of developmental stages of Penaeus setiferus (Linnaeus, 1767) were homogenized and assayed for activities of digestive enzymes. In all developmental stages, activities were present for trypsin, carboxypeptidase A and B, amylase, and non-specific esterase; none for pepsin or lipase were detected. Activities assayed with substrates for chymotrypsin and aminopeptidase are not apparently due to the presence of these enzymes in the gut. Peak activities for all enzymes occurred during late zoeal or early mysis larval stages; low activities occurred at metamorphosis. During postlarval development, amylase activity increased steadily (by a tenfold increase over five weeks), whereas most other enzyme activities were relatively constant until the fifth week of postlarval development. Although it alters enzyme activity, diet does not appear to be the primary effector of ontogenetic change in digestive enzyme activity. Instead, ontogenetic change in digestive enzyme activity may reflect either a devel...

Ontogenetic Change in Digestive Enzyme Activity of Larval and Postlarval White Shrimp Penaeus setiferus (Crustacea, Decapoda, Penaeidae).

Histoehemische Methoden s ind in den le tz ten Jah ren in zunehmendem MaBe als Hi l f smi t t e l f l i t die Diagnos t ik u n d zur K l a r u n g eytogenet i seher F ragen herangezogen worden. Von den zahlreiehen seit 1939 ver6ffent l iehten Naehweisverfahren ffir E n z y m e haben jedoeh bisher n u t die Methoden zur Loka l i sa t ion der a lkal isehen Phosphomonoes te rasen E ingang in die h/Lmatologisehe Diagnos t ik gefunden. Sehon ba ld naeh En twiek lung der h is toehemisehen Naehweismethoden ffir Phospha tasen ( G o ~ o a I 1939, 19¢I; TAKA~IA~S~') wurden Verfahren angegeben, welehe die Lokal i sa t ion der Aktivit /~t yon Lipase u n d unspezif iseher Esterase erm6gliehen (GoMo~I 1945; NAO~LAS u n d SELmMA~ 1949). Diese Methoden ffihrten bei Auss t r i ehun te r suehungen zu keinen posir iven Resu l t a t en ( G o ~ o a I 1953; WACHs'r:EI~ 1955), SO dab eine weitere Anwendung wenig Effolg ver-

Cytochemical proof of nonspecific esterase in smears. Contributions on the technic and findings in human blood smears

Both histological and histochemical studies have been made of the food, mode of feeding, gut cell structure and digestive sequences in a selected number of digenetic trematodes.The species investigated range from gut-dwelling trematodes feeding on the superficial epithelial tissues and associated mucoid secretions of the host to those forms living within the respiratory and circulatory system and feeding exclusively on blood.The mode of feeding is suctorial, brought about by the muscular pharynx and normal attachment process of the oral sucker. In one case there is evidence that this purely mechanical process is supplemented with enzymic secretions produced by the trematode which have a histolytic effect upon host tissues.On the basis of gut cell structure the species investigated are divided into those with cells and associated microvilli that vary in size and appearance so that the gastrodermal border is irregular in outline, and those with a gastrodermis comprising regular cuboidal or columnar cells bearing microvilli organized into a striated border. There is evidence to suggest that this difference in gut cell structure reflects differences in digestion. In all cases, gland cells are absent from the gastrodermis which is capable of both secretory and absorptive functions.Digestion is predominantly an extracellular process, but the exact sequence varies according to the nature of the food ingested and different degrees of adaptation are shown by the trematodes to the blood-feeding habit. The tissue-feeding species show less modification.I wish to thank Dr J. B. Jennings for helpful discussion and advice throughout the course of this work. The study was undertaken during the tenure of a Studentship from the Department of Scientific and Industrial Research.

Observations on the nutrition of digenetic trematodes

In confirmation of previous reports, the thiolacetic acid technique represents a simple and reliable method for the demonstration of motor endplates in striated muscles. This type of esterase is present in many other locations as well. When its distribution pattern was compared with that for nonspecific esterase, it was found to be identical, although in some locations nonspecific esterase was active in additional sites. The effect of various inhibitors on the staining reaction, which was carried out in most instances in sections fixed in chilled Baker's CaCl2 formalin, was also quite similar. A notable exception, however, was observed in the pancreas of various species. In contrast to the marked activity of nonspecific esterase in the acinar cells, no staining was noticed in sections incubated in the thiolacetic acid medium. However, addition of sodium taurocholate converted this negative reaction into a strong positive one, indicating that under this circumstance a true lipase was visualized. Following ...

Histochemistry of thiolacetic acid esterase: a comparison with nonspecific esterase with special regard to the effect of fixatives and inhibitors on intracellular localization:

The histochemistry of ovarian macrophages in the rat.

The Histochemistry of Indoxylesterase of Rat Kidney with Special Reference to its Cathepsin-like Activity

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The Histochemistry of Indoxylesterase of Rat Kidney with Special Reference to its Cathepsin-like Activity