Karyological studies on the freshwater prawn Macrobrachium rosenbergii

Isolation and characterization of a female-specific DNA marker in the giant freshwater prawn Macrobrachium rosenbergii

“…This idea is in keeping with the heterogametic female theory of Katakura (1989). However, as the sex chromosome of M. rosenbergii is not distinguishable morphologically (Justo et al, 1991), further research is needed to verify this notion.…”

“…To assess the copy number of the region, FISH was carried out on cells extracted from several male gonads; 2 kb out of the B3 kb first identified in female prawns was used as a probe. The high similarity between the female-specific allele and the female/male shared allele enabled us to perform FISH for the male prawns, for which there is a known protocol for cell extraction (Justo et al, 1991). In all cases in which the field was clean of background signals, the nuclei were scored according to their morphology and the number of signal spots.…”

“…Fluorescent in situ hybridization FISH was carried out as described by Dzikowski et al (2007), with the exceptions that the prawn sample was prepared according to Justo et al (1991) and that the probe used was the PCR probe of nucleotides 1-2003 of the B3 kbp fragment identified (primers available upon request). Samples were prepared from several male and female gonads, and the signal was scored for a total of 74 nuclei that could be distinguished morphologically.…”

“…In all nine species reviewed, the male prawn was found to be the heterogametic sex, bearing XY chromosomes. In the few macruran species for which karyotype studies are available, including those in the giant freshwater prawn Macrobrachium rosenbergii (Justo et al, 1991), sex chromosomes are morphologically indistinguishable from autosomes. It is believed that in M. rosenbergii, as in other macruran species, the female prawn is the heterogametic sex, bearing WZ sex chromosomes, whereas the male prawn is the homogametic sex, bearing ZZ sex chromosomes.…”

On the safety of RNAi usage in aquaculture: The case of all-male prawn stocks generated through manipulation of the insulin-like androgenic gland hormone

“…Thus, the neo-females produced in the present study, having original male chromosomes (ZZ), although acting as phenotypic females, might have been exhibiting growth ability dictated by their genomic background and grow larger than normal females (WZ). In M. rosenbergii, however, such mapping is not yet available, as the sex chromosomes are not morphologically distinguishable (Justo et al, 1991) and further research is needed to test this hypothesis. Moreover, the different growth rates could be attributed to the different ponds in which other environmental variables, including density, could have played a major role (Cohen and Ra'anan, 1983;Karplus et al, 1986;Sandifer and Smith, 1975).…”