Functional effect of haemoglobin polymorphism on the haematological pattern of Gentile di Puglia sheep

Abstract

The relationship between haemoglobin polymorphism and haematological pattern were studied in Gentile di Puglia, the Apulia Merino native breed. In a sample of 292 individuals, on five different farms, alpha- and beta-globin genetic polymorphism was investigated. A remarkable polymorphism was detected especially at alpha-globin gene where the variations concerned both the quality of the gene product and gene expression. Triplicated and quadruplicated alpha-globin genes were observed in 8.6% and 1.2% of the alpha-haplotypes respectively. At beta-globin (HBB) locus, predominance of HBB(B) allele was found in all flocks, while HBB(A) overall frequency was around 11.2%. Moreover, the effect of genotypes at globin systems on haematological data was evaluated on 289 animals. A significant effect was detected for HBB locus on haematocrit (HCT) and mean corpuscular volume (MCV), with decreasing HCT and MCV for decreasing number of HBB(A) alleles in the genotype. The opposite trend was observed for mean corpuscular haemoglobin concentration. The advances presented by this paper give reasons for inferring that BB genotypes can be expected to be more resilient to climatic stress and to local parasites.

Looking for prognosticators in ovine anaplasmosis: discriminant analysis of clinical and haematological parameters in lambs belonging to differently susceptible breeds experimentally infected with Anaplasma ovis

“…As a consequence, the considered breeds may represent a good model to investigate the molecular basis underlying tolerance to A. ovis . In particular, the unusual haemoglobin polymorphism recorded in Altamurana [6] as well as the other Apulian native sheep breeds [7,12] and the related functional effects may have an adaptive significance related to the local selective pressure exerted by the pathogen and therefore deserve closer examination.…”

“…Thus, breeds traditionally reared below the 41° parallel generally display a good tolerance to TBDs [3]. Due to this feature, breeds from these areas are of particular interest to better understand the phenotype "tolerance to TBDs", which is known to be under complex multi-factorial regulation [4,5] and possibly not unrelated to the erythropoietic system [3] as well as to the haemoglobin genetic systems [6,7]. …”

Tolerance to Tick-Borne Diseases in Sheep: Highlights of a Twenty-Year Experience in a Mediterranean Environment

“…As highlighted in the above section 4, the phenomenon of tolerance is a broad-based one and possibly not unrelated to the erythropoietic system in different sheep breeds or to the haemoglobin genetic systems (Pieragostini et al, 2003;Pieragostini et al, 2006). Anyway, the success of selection for disease resistance is dependent on correctly identifying the disease agent and the phenotype for disease resistance.…”

“…Phenotypic variability induced by parasites is a matter of fact, as impressively exemplified by the high number of haemoglobinopathies in human populations living in malariaendemic areas (Evans & Wellems, 2002). Recalling Feynman's 1 saying that nature repeats itself at every scale, we suggested that the unusual haemoglobin polymorphism recorded in Apulian native sheep breeds and the related functional effects might have an adaptive significance, also being somehow related to the selective pressure of tick borne parasites (TBP) (Pieragostini et al, 1994;Pieragostini et al, 2003;Pieragostini et al, 2006). Based on these considerations, we aimed to define the phenotype of the tick borne diseases in different sheep breeds starting from the one caused by A. ovis, the most common parasite in our area as confirmed by a small survey on sheep TBP performed in 10 farms (throughout Apulia) on 240 individuals.…”

“…Little information is available on the effect of Hb A replacement by Hb C. Owing to the high oxygen affinity of Hb C (Huisman and Kitchens, 1968), the reversible switch from Hb A to Hb C may be considered a way to cope with the reduced amount of oxygen available at higher altitudes and thus suggest a positive effect on the fitness of mountain Caprini. Conversely, in the case of erythropoietic stress, it was suggested (Pieragostini et al, 1994;Pieragostini et al, 2006) that Hb C might negatively affect peripheral oxygen delivery and worsen the clinical picture of sheep breeds native of areas with endemic haemotropic pathogens. Hence, in the present case, the conditio sine qua non for checking the effect of beta globin genotype was the detection of Hb C switched on in AB individuals following a strong erythropoietic stress.…”