Histochemical classification based upon reaction types and its application to carbohydrate histochemistry

Summary A method of classification is presented, which divides histochemical visualization reactions into categories based on general reaction types. This scheme is dependent upon the reaction between two elements, the substrate and the probe. The substrate represents a tissue component(s) with one or more reactive groups that can combine directly with the probe. Alternatively, the substrate reactive groups are chemically modified (activation) with a suitable reagent before reaction with the probe. Probes are of three types: those that yield a coloured product, those that result in a colourless product, and those that produce a coloured product only after a further reaction.Methods used in carbohydrate histochemistry are divided into one, two and three probe reactions. Two probe reactions are further subdivided into sequences involving one or two coloured products (one and two dye sequences); three probe reactions into sequences involving one, two or three coloured products (one, two and three dye sequences). This classification permits the rationalization and organization of methods, and provides a framework for the examination of existing methods and the development of new ones.     

A quantitative histochemical study of NADPH-ferrihemoprotein reductase activity

Summary A quantitative histochemical assay for NADPH-ferrihemoprotein (P450) reductase had been developed. For optimal activity, it is necessary to use a relatively electropositive tetrazolium salt such as neotetrazolium chloride as the final acceptor. The apparentK _m of the reaction is 0.83 mM. Its specificity has been proven in two ways: (i) activity is increased selectively in the pericentral zone of liver from rats treated with phenobarbitone, an inducer of the reductase, though not in liver of rats injected with 3-methylcholanthrene, which induces NAD(P)H dehydrogenase; (ii) it is competitively inhibited by NADP⁺ (K _i=1.50mm) though unaffected by dicumarol, an inhibitor of NAD(P)H dehydrogenase activity. An NADP⁺ concentration ten times greater than the substrate concentration inhibits the histochemical reaction and the reaction in a microsomal fraction assayed biochemically to the same degree (70% inhibition). The amount of inhibition is independent of temperature, of the zone of the acinus and of the treatment of the animal.Continuous microdensitometric monitoring of the reaction product as it is formed has shown that the specific reaction is linear with incubation up to 10 min, thus allowing end-point measurements to be used for cytophotometric analysis.     

Differentiation of histochemically visualized mercury and silver

Summary Accumulations of silver and mercury can be visualized in tissue sections by a technique called autometallography or physical development. In order to make a histological differentiation between mercury and silver in tissue exposed to both metals, it is necessary to remove one of the metals while leaving the other untouched. The present paper describes a technique by which silver accumulations in histological sections can be removed by potassium cyanide, yet leaving mercury accumulations intact to be developed autometallographically.     

Ecological basis of heterochrony in early-ontogenesis gonad development in different races of Kura sturgeon (Acipenser guldenstadti persicus Borodin)

Early germ cell development in Persian sturgeon appears to be faster in the marine environment than in aquaculture conditions. Adaptation plasticity differs significantly for gonad formation and sex determination in the sturgeon fry and depends to differing extents on the temperature. The sturgeon gonads are more sensitive to low temperatures on the early stages of sex determination than in the period of gonad formation; the differences between sexes are preconditioned by the earlier start of sex determination in females when compared to males. The rates of the early gonad and germ cell development in sturgeon are conditioned by its reproduction season. In the population of the late spring race, the delay in both early sex determination and germ cell development stays even for the ages of 1+, 2+, and 3+ when compared to the population of the early spring race. The biophysiological quality of parents is transmitted to their offspring.     

Location of gene specifying cytosine deaminase in Escherichia coli

Summary The gene specifying cytosine deaminase (cod) is shown to be located at approximately 86 minutes on the linkage map of E. coli. The corresponding gene in S. typhimurium has been reported to have a different location.