126 research outputs found
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
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
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
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
Permeability studies and dehiscence of spermatophores
The mechanism of release of sperm from crustacean spermatophores
has long been debated. Many factors such as external
physical pressure, inbibition of water by substances within and
an Qviducal secretion have been suggested to be responsible for
the opening up of spermatophores (Mouchet/ 1931 ; Bloch,
1935 ; Subramoniam, 1977)
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