GENETIC VARIATION IN CULTURED STOCKS OF TIGER SHRIMP (Penoeus monodon) IN INDONESIA

Three stocks of tiger shrimps, Penaeus monndon, obtained from brackish water pond culture in Aceh (Sumatera Island), Cilacap (Java Island) and Sumbawa (West Nusatenggara) were assayed for allozyme variation at 9 enzyme loci from muscle biopsies.

FLUCTUATING ASYMMETRY REFLECT THE GROWTH OF HYBRID GROUPER Epinephelus fuscoguttatus AND Epinephelus polyphekadion

Fluctuating asymmetry has been widely used as a measure of developmental stability and as an indicator of individual fish growth. The present study compared fluctuating asymmetry in three bilateral meristic traits of F-1 hybrid between female Epinephelus fuscoguttatus and male Epinephelus polyphekadion and two F-1 pure parental progenies. The fishes were reared by communal and separate tank systems. Hybrids were confirmed by allozymes electrophoresis. After three months of rearing, the F-1 hybrids fish grew faster 45.9% and 66.6% compare to the F-1 pure parental progenies of E. fuscoguttatus and E. polyphekadion (P<005) respectively. Development stability as measured by fluctuating asymmetry was lower in hybrid (20%-40%) than in the pure parental progenies (53%-80%). Among four enzyme loci examined, only Pgm locus showed variants and at that locus all hybrids fish were heterozygous. Heterozygous hybrids showed lower fluctuating asymmetry and related to higher developmental stability. The higher developmental stability positively reflected a faster growth rate. Thus this finding can be used to explain the reason that why hybrids groupers appeared grew faster than parental species.

Complete absence of linkage disequilibrium between enzyme loci in natural populations of Drosophila ananassae

Linkage disequilibrium has been studied among three linked enzyme loci of second chromosome of D. ananassae collected from five natural populations. Each of the three enzyme loci, that is Acph1, Acph 2 and Xdh was represented by two distinct alleles and in three genotypic forms. Thus nine genotypic combinations were recorded for each enzyme pair. The results clearly show absence of non-random occurrence of different genotypic combinations in all the populations studied. The occurrence of all possible genotypic combinations indicates enough frequency of crossing over among these enzyme loci. The absence of linkage disequilibrium in this study thus indicates that selection did not play any role and free recombination among the genes resulted random occurrence of all combinations.

Genetic differentiation of Echinostoma revolutum and Hypodereaum conoideum from domestic ducks in Thailand by multilocus enzyme electrophoresis

Echinostomes are common intestinal parasites causing zoonotic disease, which are endemic worldwide. Of the four species of medically important echinostomes reported in Thailand, two species, Echinostoma revolutum and Hypodereaum conoideum, have been detected in poultry. These two parasites are morphologically similar and are sometimes difficult to distinguish. In the present study, multilocus enzyme electrophoresis was used to differentiate E. revolutum from H. conoideum collected from domestic ducks in Thailand. The parasites were compared using 22 enzymes with 30 presumptive enzyme loci. The two species of echinostome could be distinguished at 17 of the 30 enzyme loci. Several loci were polymorphic within each species, suggesting that these can be used to examine their population genetics.