Bright Singh, I S; Vici, V; Sarita,G Bhat(Academic Press, March 10, 2000)
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Abstract:
The fresh water prawn, Macrobrachium rosenbergii, has proven potential for use as an
aquaculture species (Hanson & Goodwin, 1997; Kurup, 1984). In India alone, culture of
this species of prawn in low saline areas requires about 200 million seed per year
(Kurup, 1984). In hatcheries poor survival rate has been associated with vibriosis at
di#erent stages of the larval cycle. Members of the family Vibrionaceae associated with
the larvae of M. rosenbergii were shown to be pathogenic under laboratory conditions
(Bhat et al., 2000, in press). Vibrios have been associated with mortality of penaeid
prawns by several workers (Aquacop, 1977; Hameed, 1993; Karunasagar et al., 1994).
Two methods have been suggested to protect both the larvae and juveniles from
vibriosis; one is the administration of bacterins prepared from pathogenic strains
(Itami et al., 1989, 1991; Adams, 1991; Song & Sung, 1990; Sung et al., 1991) and the
other is the utilization of yeast 1-3 and 1-6 glucans as immunostimulants for
enhancing the non-specific defense system (Sung et al., 1994; Song et al., 1997). In the
light of these observations it was hypothesised that bacterins and yeast glucans may
also be e#ective in protecting the larvae of M. rosenbergii from vibriosis as has been
achieved in the case of penaeids. To examine this hypothesis, the ability of bacterins
and an extracellular glucan-producing yeast to increase the overall survival and
metamorphosis of larvae in a hatchery, as well as to protect against an experimental
challenge under laboratory conditions, was evaluated
Description:
Fish & Shellfish Immunology (2000) 10, 559–563
doi:10.1006/fsim.2000.0278
Sarita,G Bhat; Dr.Bright Singh,I S(Cochin University Of Science And Technology, May 4, 1998)
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Abstract:
Even though Bergey '5 Manual has been recognized globally as the guide to
bacterial systematics, it has to be emphasized that descriptions given to a large extent
are based on studies made with temperate isolates This leads one to conclude that
any attempt to identify the tropical isolates with identification keys and tables
generated from this information may lead to erroneous conclusions. And there is
every possibility of the existence of genotypic and phenotypic variants or even nev.
species in this part ofthe aquatic ecosystem. Applications ofa polythetic scheme of
classification based on the principles of Numerical Taxonomy opens up exciting
avenues for bringing to light, this possibility which otherwise would have been
masked by the unidirectional approach as in monothetic schemes.
Another added advantage of clustering a ‘natural’ bacterial population by
numerical taxonomy, is the ease by which genotypic characterization could be
performed on the clusters by selecting a representative from each cluster This helps
overcome the practical impossibility of analyzing all the isolates in a pani:'_lar
cluster. The genotypic characteizarion would either be mole °/o G-'rC. DNA-D.\_-X
hybridization, DNA-RNA hybridization or DNA fingerprinting. Considering the requirement creating a broad base in the understanding of the family Vibrionaceae associated with the larvae ofM rosenbergii, the present work was undertaken to channelize every new information generated for developing appropriate managerial measures to protect the larvae from vibriosis during the unusually prolonged larval phase.
Description:
School of Environmental Studies.
Cochin University of Science and Technology