Anim. Blood Grps biochem. Genet. I (1970) 171-172 SHORT COMMUNICATION Close linkage between the locus for phosphohexose isomerase (PHI) and the H blood group locus in pigs’ E. Andresen Dzpartment of Animal Genetics, Royal Veterinary and Agricultural University, Copenhagen, Denmark Received: 14 August 1970 The H blood group locus was recently shown to be closely linked with the locus for variants of 6-phosphogluconate dehydrogenase (6-PGD) in pigs (Andresen, 1970). This represented the fourth case of close autosomal linkage in that species. The present communication deals with an additional case of linkage involving the H blood group locus. This locus comprises multiple alleles, but merely two of these, Ha and He, were involved in the study. The PHI locus for variants of the enzyme phosphohexose isomerase encompasses the codominant alleles A and B corresponding to three electrophoretic patterns, A, AB and B (Saison, 1970). The three phenotypes have been observed in haemolysates from the two breeds considered in the present study, the Duroc breed and the Danish Landrace breed. A total of ten double backcross matings with 78 offspring of the Duroc breed were observed when the two systems were invcstigated jointly. The ten litters were delivered by ten different sows and sired by eight different boars. Four sows and five boars were doubly heterozygous. The single factor segregations were in agreement with expectations, whereas pronounced joint segregation was observed with regard to variants of the two systems. Among the 78 offspring merely two recombinants were observed. Hence, linkage has been established, and the estimate of the recombination frequency is 2/78 or 2.6%. The autosomal H blood group locus is therefore linked with loci for enzymes of both the Embden-Meyerhof pathway (PHI) and the pentose cycle (6-PGD) of glucose metabolism. A recombination frequency of 3.4% between the H blood group locus and the 6-PGD locus was estimated previously, and the sum of the two estimates is less than the estimate of the recombination frequency between the two enzyme loci (Andresen, in prep.). The most likely order of the three loci is therefore the following: PHI, H, 6-PGD. This represents the first case of an autosomal linkage group involving three loci in larger farm animals (cf. Hutt, 1964). Supported by grant No 51 3/527 from Statens jordbrugs- og veterinaervidenskabelige forskningsrad.

Close linkage between the locus for phosphohexose isomerase (PHI) and the H blood group locus in pigs

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Anim. Blood Grps biochem. Genet. I (1970) 171-172 SHORT COMMUNICATION

Close linkage between the locus for phosphohexose isomerase (PHI) and the H blood group locus in pigs’

E. Andresen

Dzpartment of Animal Genetics, Royal Veterinary and Agricultural University, Copenhagen, Denmark

Received: 14 August 1970

The H blood group locus was recently shown to be closely linked with the locus for variants of 6-phosphogluconate dehydrogenase (6-PGD) i n pigs (Andresen, 1970). This represented the fourth case of close autosomal linkage in that species. The present communication deals with an additional case of linkage involving the H blood group locus. This locus comprises multiple alleles, but merely two of these, Ha and He, were involved in the study. The PHI locus for variants of the enzyme phosphohexose isomerase encompasses the codominant alleles A and B corresponding to three electrophoretic patterns, A, AB and B (Saison, 1970). The three phenotypes have been observed in haemolysates from the two breeds considered in the present study, the Duroc breed and the Danish Landrace breed.

A total of ten double backcross matings with 78 offspring of the Duroc breed were observed when the two systems were invcstigated jointly. The ten litters were delivered by ten different sows and sired by eight different boars. Four sows and five boars were doubly heterozygous. The single factor segregations were in agreement with expectations, whereas pronounced joint segregation was observed with regard to variants of the two systems. Among the 78 offspring merely two recombinants were observed. Hence, linkage has been established, and the estimate of the recombination frequency is 2/78 or 2.6%. The autosomal H blood group locus is therefore linked with loci for enzymes of both the Embden-Meyerhof pathway (PHI) and the pentose cycle (6-PGD) of glucose metabolism. A recombination frequency of 3.4% between the H blood group locus and the 6-PGD locus was estimated previously, and the sum of the two estimates is less than the estimate of the recombination frequency between the two enzyme loci (Andresen, in prep.). The most likely order of the three loci is therefore the following: PHI, H, 6-PGD. This represents the first case of an autosomal linkage group involving three loci in larger farm animals (cf. Hutt, 1964).

Supported by grant No 51 3/527 from Statens jordbrugs- og veterinaervidenskabelige forskningsrad.

Page 2: Close linkage between the locus for phosphohexose isomerase (PHI) and the H blood group locus in pigs

I72 E. ANDRESEN

Acknowledgment

I thank Miss Anna-Lise Poulsen and Mrs Inger Hvidtfeldt Christensen for excellent assistance.

References

Andresen, E., 1970. Linkage between the H and 6-PGD loci in pigs. Acta vet. scand. IZ: 136-137. Hutt, F. B., 1964. Animal genetics. Ronald Press, New York. Saison, R., 1970. Serum and red cell enzyme systems in pigs. Pruc. Xf Eur. Conf. Anim. Blood

Grps biochem. Polymorphisms: 321-330. Junk, The Hague.

Anim. Blood Grps biochem. Genet. 1 (1970)