Reproductive engineering in crustacean aquaculture

Crustacean aquaculture industry in India suffers greatly from lack of technological developments. A major constraint in this enterprise is the limitation of seed stock availability. A critical appraisal is made of the techniques used in the manipulation of reproductive processes in order to augment year-round production of seeds. A new possibility of induced ovarian maturation in crustaceans is by administering steroid hormones of vertebrate source. Environmental factors are known to govern the gametogenic cycle of marine crustaceans. Cryopreservation of male gametes and artificial insemination by way of spermatophore transfer could solve some of the problems of mating under laboratory conditions

Analytic Variational Investigation of Euclidean SU(3) Gauge Theory

Analytic variational techniques for lattice gauge theories based on the Rayleigh-Ritz(RR) method were previously developed for euclidean SU(2) gauge theories in 3 and 4 dimensions. Their extensions to SU(3) gauge theory including applications to correlation functions and mass gaps are presented here.Comment: 4-pages in 2-column format, typsetted for LaTeX with document style espcrc2.sty (available on request), IMSc/93-2

Determination of reproductive periodicity in the intertidal mole crab Emerita asiatica

Food supply may be regarded as the primary factor controlling growth rate and egg production in the natural populations of Crustacea (Wcnner et ah, 1974). The faster growth rate can also lead to an altered age/size at sexual maturity. Thus environmental factors not only influence the percentage of berried female in a population, but also the size of sexual maturity

A morphological investigation on the spermatophores of selected crustaceans

In many decapod crustaceans, the male produces discrete aggregations of spermatozoa embedded in some form of protective covering, termed the spermatophores. They are transferred during mating to the oviduct or merely deposited on the sternum of the females

A histological classification of the developmental stages of crustacean oocyte

Oogenesis is a dynamic process comprising i) a generative (proliferative) and ii) a vegetative (growth) phase. The generative phase refers to the mitotic multiplication of the primary oogonial cell (=gonocytes) into the secondary oogonial cell that transforms to primary oocyte. These events normally occur in the germinal zone ( = germarium) of the ovary. The primary oocyte with a diploid number of chromosomes enters into the prophase of meiotic divisio

Eyestalk ligation experiments on the fairy shrimp Streptocephalus dichotomus

The endocrine system of lower crustaceans such as anostracan also shows a similarity with that of decapod crustaceans, especially in the possession of a stalked eye in which is present the X-organ sinus gland complex (Lake, 1969). In the fairy shrimp Streptocephalus dichotomus, the sinus gland is located inbetween the lamina ganglionaris and the optic medulla. The cells in this gland show variation in their secretory contents during reproductively quiescent and reproductively active period

Quantitative assay of non-specific esterases in the developing egg of Emerita asiatica

It is a well known fact that crustacean yolk contains a considerable quantity of storage lipids to be utilized during embryogenesis. Esterases are the main hydrolytic enzymes responsible for converting complex storage lipids into easily utilizable glycerides and free fatty acids. Esterases exist as isozymes which could be characterized histochemically after separating them on polyacrylamide gel

A classification of neurosecretory cells of crustacea

In Crustacea, the distribution of NSCs is limited to the brain, thoracic ganglia, circum-oesophageal connectives and eyestalk. Enami (1951) first described different types of NSCs and mapped them in the brachyuran crab, Sesarma dehaani

Identification and characterization of vitellogenin and lipovitellin of Scylla serrata and Emerita asiatica using disc gel electrophoresis

The appearance of a sex limited plasmatic protein (FSP) in the mature crabs and other higher crustaceans is now well established. As early as 1954, Frentz observed the FSP in the blood of Carcinus maenas during vitellogenesis. This protein is considered to be the precursor of the main yolk protein of the egg

Detection and characterization of esterase isozyme by disc gel electrophoresis using inhibitors

The non-specific esterases include different types of esterases,, acetyl, aryl, carboxyl and cholin esterases. These forms are identified on the basis of their differential activity towards various inorganic inhibitors (Holmes and Master, 1968 ; Dickinson and Johnson, 1978). Similarly isozymes of a type of esterase are detected by the differences in their molecular weight, as shown by their relative mobilities in disc gel electrophoresi