Kinetics of the ontogenic and reversible hemoglobin switching in the mouflon (Ovis musimon) and sheep x mouflon hybrid

Phenotype transition from wild mouflon to domestic sheep

The domestication of animals started around 12,000 years ago in the Near East region. This "endless process" is characterized by the gradual accumulation of changes that progressively marked the genetic, phenotypic and physiological differences between wild and domesticated species. The main distinctive phenotypic characteristics are not all directly attributable to the human-mediated selection of more productive traits. In the last decades, two main hypotheses have been proposed to clarify the emergence of such a set of phenotypic traits across a variety of domestic species. The first hypothesis relates the phenotype of the domesticated species to an altered thyroid hormone-based signaling, whereas the second one relates it to changes in the neural crest cells induced by selection of animals for tameness. These two hypotheses are not necessarily mutually exclusive since they may have contributed differently to the process over time and space. The adaptation model induced by domestication can be adopted to clarify some aspects (that are still controversial and debated) of the long-term evolutionary process leading from the wild Neolithic mouflon to the current domestic sheep. Indeed, sheep are among the earliest animals to have been domesticated by humans, around 12,000 years ago, and since then, they have represented a crucial resource in human history. The aim of this review is to shed light on the molecular mechanisms and the specific genomic variants that underlie the phenotypic variability between sheep and mouflon. In this regard, we carried out a critical review of the most recent studies on the molecular mechanisms that are most accredited to be responsible for coat color and phenotype, tail size and presence of horns. We also highlight that, in such a complicate context, sheep/mouflon hybrids represent a powerful and innovative model for studying the mechanism by which the phenotypic traits related to the phenotypic responses to domestication are inherited. Knowledge of these mechanisms could have a significant impact on the selection of more productive breeds. In fact, as in a journey back in time of animal domestication, the genetic traits of today's domestic species are being progressively and deliberately shaped according to human needs, in a direction opposite to that followed during domestication.

The sequence and phylogenesis of the ?-globin genes of Barbary sheep (Ammotragus lervia), goat (Capra hircus), European mouflon (Ovis aries musimon) and Cyprus mouflon (Ovis aries ophion)

In order to investigate the polymorphism of ?-globin chain of hemoglobin amongst caprines, the linked (I)? and (II)? globin genes of Barbary sheep (Ammotragus lervia), goat (Capra hircus), European mouflon (Ovis aries musimon), and Cyprus mouflon (Ovis aries ophion) were completely sequenced, including the 5? and 3? untranslated regions. European and Cyprus mouflons, which do not show polymorphic ? globin chains, had almost identical ? globin genes, whereas Barbary sheep exhibit two different chains encoded by two nonallelic genes. Four different ? genes were observed and sequenced in goat, validating previous observations of the existence of allelic and nonallelic polymorphism. As in other vertebrates, interchromosomal gene conversion appears to be responsible for such polymorphism. Evaluation of nucleotide sequences at the level of molecular evolution of the (I)?-globin gene family in the caprine taxa suggests a closer relationship between the genus Ammotragus and Capra. Molecular clock estimates suggest sheep-mouflon, goat-aoudad, and ancestor-caprine divergences of 2.8, 5.7, and 7.1 MYBP, respectively.

Barbary sheep (Ammotragus lervia): The structure of the adult β-globin gene and the functional properties of its hemoglobin

The adult beta-globin gene of Ammotragus lervia (Barbary sheep or aoudad) has been sequenced completely, including 185 base pairs of 5' flanking region and 168 base pairs 3' to the stop codon, and compared with that of other caprines such as goat (Capra hircus), wild Corsico-Sardinian (Ovis aries musimon) and Cypriot (O. a. ophion) mouflons, and domestic sheep (Ovis aries). The gene was identified as being located on a triplicated four-gene set cluster containing the HBBA locus (A-haplotype) as is the case of goat, sheep of the Hb A type and Corsico-Sardinian mouflon. Phylogenetic analyses support the evidence that caprines share a common ancestor that probably carried the A-haplotype and that a more recent deletion of a gene set gave rise to the duplicated cluster containing the HBBB locus (B-haplotype) found in sheep of the Hb B type and Cypriot mouflon, which evolved independently. Data also suggests that the Ammotragus beta-globin gene is older than genes of the examined caprines and indicates it followed an independent evolution after separating from species having the same HBBA locus. Similarly, phylogenetic analyses of beta-globin chain sequences suggest a different evolution for globins coded by the HBBA locus with respect to the HBBB. Ammotragus beta-globin chain shows all the amino acids responsible for the low oxygen affinity of ruminant Hbs. Investigations on the oxygen transport properties indicate that the intrinsic oxygen affinity of aoudad Hb is higher than the Hb B of the domestic sheep and, at the same time, more similar to that of other A type Hbs, whereas in the presence of the Cl(-) effector the oxygen affinity is approximately the same as that of the other species.

Erythrocyte Morphology and Haemoglobin Types of Neonatal Roan Antelopes (Hippotragus equinus) with Hypochromic Poikilocytic Anaemia

Neonatal, poikilocytic anaemia in some members of the Hippotragini has previously been documented but not fully investigated. This study was undertaken to describe the erythrocyte morphology of roan antelopes (Hippotragus equinus) during the first 4 weeks after birth and to identify aspects of haemoglobin (Hb) production that might be implicated in this syndrome. Twenty-nine roan antelope calves were sampled on, or close to, 1, 7, 14 and 28 days after birth. Erythrocyte morphology was characterized, and microhaematocrit values and Hb parameters determined, for each sampling occasion. Findings indicated a significant change in erythrocyte morphology during the neonatal period and two haemoglobin types, fetal and adult, were identified. The perinatal onset of adult Hb synthesis was delayed relative to the termination of fetal Hb production, resulting in the observed anaemia. Haemoglobin concentration and erythrocyte morphology were significantly correlated. These findings suggest an intimate relationship between Hb synthesis and the observed poikilocytosis. An imbalance in the synthesis of the alpha- and beta-globin chains of Hb (a thalassaemia) may prove to be the underlying pathophysiology of this syndrome.

In vivo and in vitro fertilizing capacity of cryopreserved European mouflon [Ovis gmelini musimon] spermatozoa used to restore genetically rare and isolated populations

European mouflon sheep are an endangered species of ovidae residing primarily in the mountenous habitat of the islands of Sardinia and Corsica. The purpose of this study was to assess the fertilizing capacity of cryopreserved European mouflon spermatozoa after AI in synchronized mouflon and domestic ewes and after IVF in in vitro matured mouflon and domestic ewe oocytes collected by OPU technique. Domestic ram (Ovis aries) spermatozoa served as control. Semen was collected by artificial vagina from three mouflons and three domestic rams during the breeding season and was cryopreserved. At thawing, no significant differences in sperm viability were found between the wild and the domestic species (53.1 +/- 4.6% versus 56.0 +/- 4.7%) whereas the percentage of acrosome-intact sperm was lower in mouflon (55.5 +/- 4.6%) than in ram semen (62.7 +/- 3.1%; P < 0.05). Lambing rate did not differ between synchronized mouflon and domestic ewes (5/11 versus 8/12) after 150 and 156 days of pregnancy, respectively. After two OPU sessions, 87 and 132 oocytes were collected from three hyperstimulated mouflon and three domestic ewes. Cryopreserved/thawed semen was inseminated with an endoscope into the uterus of corresponding species during the non-breeding season. The oocytes were matured and fertilized in vitro; 61/73 mouflon and 81/101 domestic ewe oocytes were found to be fertilized. From these, we obtained 6/61 and 17/81 blastocysts. After vitrification and thawing, the hatching rate showed no significant difference between mouflon and sheep blastocysts (4/6 versus 14/17). In conclusion, our data showed that cryopreserved mouflon spermatozoa can be successfully used to carry out a genuine and complete program of genetic restoration in small and isolated groups of European mouflons.

A comparative study on the functional properties of the wild European mouflon and domestic sheep hemoglobins

The functional properties of Hb B of the wild European mouflon (Ovis gmelini musimon), Hb B of domestic sheep (Ovis aries), and Hb C isolated from anemic mouflon were investigated. Mouflon and sheep Hbs appear to be very similar in their response to organic anions and protons, whereas sheep Hb B displays an oxygen affinity lower than that of mouflon Hb B and sheep Hb A. Mouflon Hb B and Hb C, like sheep Hb A and Hb C, have similar efficiencies in transporting oxygen to the tissues. As in other ruminant Hbs, the effect of temperature on the oxygen affinity is slight. Data suggest that mouflon Hb B is not only structurally, but even functionally, more similar to sheep Hb A than to sheep Hb B.

Sheep haemoglobin I or beta B13(A10)Gly-->Ser: an example of a CpG mutation in vertebrates. Characterization using FAB-mass spectrometry and amino acid sequencing

1. The amino acid substitution which characterizes the haemoglobin I variant from sheep has been ascertained using a combination of Fast Atom Bombardment mass spectrometry and protein sequencing. 2. A Ser for Gly substitution at position 13 (10 of the A helix) was found in a polypeptide with the overall sequence of the beta B globin. 3. On the basis of the nucleotide sequence of the beta B-globin gene, a C to T transition occurring on a CpG doublet is considered to be responsible for the amino acid substitution. 4. This represents the first observation of a variant sheep Hb due to a mutation which is rather common in the human genome. 5. Amongst ruminants, serine is normally present at position 13 of goat and sheep epsilon II and gamma chains and of bovine gamma chain which had an independent and more ancient evolutionary origin than the beta chains.