No abstract

No abstract

Four microsatellite loci were identified for Clarias macrocephalus and the forward and reverse primers for each locus were designed according to their unique flanking regions. One locus, Cma-1 *, was monomorphic, three loci, Cma-2*, Cma-3 * and Cma-4*, were polymorphic having 5, 14 and 30 al leles per locus respectively. The polymorphic microsatellite loci were studied in four natural populations of C. macrocephalus collected from different locations in Thailand. Mean number of alleles per locus were 8.0, 8.7, 6.0 and 10.0, respective to populations from Pattani, Pattalung, Chiangrai and Prachin buri. Mean heterozygosities were 0.744, 0.765, 0.718 and 0.810 respectively. Nei's genetic distance showed the closest relationship between Pattalung and Prachinburi (0.230) and the largest genetic dis tance between Pattalung and Chiangrai (0.535). However, the genetic distances obtained in this study were not accorded with geographic distance.

No abstract

No abstract

The critically endangered Pangasianodon gigas is endemic to the Mekong River. Despite its importance, little is known about its genetic diversity and conservation efforts are hampered. Ten polymorphic dinucleotide microsatellite primer pairs were developed from DNA of P. gigas . The analysis of 20 individuals from hatchery stocks using these primers resulted in two to six alleles/locus; H O = 0.05 -0.95; H E = 0.05 -0.81. All but one locus (Pg-3) conformed to Hardy-Weinberg expectation. Eight, six and seven primer pairs were amplified with the DNA from Pangasianodon hypophthalmus , Pangasius larnaudii and Pangasius sanitwongsei , respectively. These markers will be useful for genetic monitoring of wild and hatchery stocks of these pangasiids.

This chapter focuses on ways to assess the likelihood of gene flow before approved use and actual entry of transgenic fish into the environment. A step-by-step approach for assessing gene flow based on a fault tree of the chain of events necessary for introgression of transgenes into a wild population is presented. Partition entry and introgression into subcomponents are discussed. The importance of assessing how both the transgene and overall genetic background of the escaping transgenic fish may affect the likelihood and consequences of gene flow to wild relatives is addressed. The main data needed for assessing gene flow are identified. Moreover, possible modelling, field and laboratory studies to obtain the data needed are described.

No abstract