Genetic linkage mapping of allozyme loci in even- and odd-year pink salmon (Oncorhynchus gorbuscha).

We constructed genetic linkage maps of allozyme loci in even- and odd-year pink salmon (Oncorhynchus gorbuscha), using the total of 320 families (each female was crossed with two different males, and 80 females and 160 males were used for each of even year and odd year). The maps include eight linkage groups involving 22 loci. We observed substantial variation in recombination frequencies among different families within broodline and between sexes within broodlines. In the linkage analysis between sAAT-3* and sMDH-B1,2*, two even-year families and one odd-year family exhibited evidence of association, but two even-year and one odd-year families did not. Recombination rate tends to be reduced in males in pink salmon. The ratio of recombination rate (female/male), which ranged from 1.7 to infinity, averaged 2.8 in the even-year crosses and 3.2 in the odd-year crosses. The linkage groups (LG) I and II involving sAAT and mAH loci, which probably duplicated in the recent tetraploidization event, and the orders of loci in the LGs I (sAAT-3* --> mAH-4*) and II (mAH-3* --> sAAT-4*) were reversed, suggesting the possible paracentric inversion during salmonid evolution after the duplication.

Gene-centromere distances of allozyme loci in even- and odd-year pink salmon, (Oncorhynchus gorbuscha).

We produced gynogenetic progeny families to estimate gene-centromere (G-C) distances of allozyme loci in even-year and odd-year pink salmon (Oncorhynchus gorbuscha). G-C distances of 37 loci distributed on a chromosome ranged from 1 cM at LDH-A1* to 49 cM at ADA-2*, DIA-2*, and sMDH-B1,2*. The distribution of the G-C distances along the chromosome arm was not even and appears telomeric. Eight loci in even-year and seven in odd-year showed high G-C distances (>45 cM), indicating that one crossover per chromosome arm is usual in pink salmon. Variation was observed in the results from different families; 14 loci out of 21 tested, showed heterogeneity. At mAH-3*, G-C distances from five odd-year families ranged from 6 to 37 cM; the widest range observed in this study. At isoloci such as sMDH-A 1,2* and sMDH-B1,2* the distances from different families were grouped into statistically discrete distributions, suggesting that it may be a reflection polymorphism at both isoloci. It appears G-C distances in salmonid species are well conserved with some minor differences.