MC1R) Gene Polymorphism Is Useful for Authentication of Massese Sheep Dairy Products
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Journal of Dairy Research (2011) 78 122–128. © Proprietors of Journal of Dairy Research 2010 122 doi:10.1017/S0022029910000890 A melanocortin 1 receptor (MC1R) gene polymorphism is useful for authentication of Massese sheep dairy products Luca Fontanesi1*†, Francesca Beretti1,2*†, Stefania Dall’Olio1, Baldassare Portolano2, Donato Matassino3 and Vincenzo Russo1 1 DIPROVAL, Sezione di Allevamenti Zootecnici, University of Bologna, Via F.lli Rosselli 107, 42123 Reggio Emilia, Italy 2 Dipartimento S.En.Fi.Mi.Zo., Sezione di Produzioni Animali, University of Palermo, Viale delle Scienze – Parco d’Orleans, 90128 Palermo, Italy 3 ConSDABI, Contrada Piano Cappelle, 82100 Benevento, Italy Received 12 May 2010; accepted for publication 26 October 2010 Massese is an Italian sheep breed, with black or grey coat colour, mainly reared in the Tuscany and Emilia Romagna regions. Recently, the emerging interests in this breed have resulted in the production of Pecorino cheese obtained with only Massese milk. In order to be profitable, this marketing link between Massese breed and its products should be defended against fraudsters who could include milk of other sheep breeds or cow milk in Massese labelled productions. To identify the genetic factors affecting coat colour in sheep, we have recently analysed the melanocortin 1 receptor (MC1R) gene and identified several single nucleotide polymorphisms (SNPs). In this work, as a first step to set up a DNA based protocol for authentication of Massese dairy products, we further investigated the presence and distribution of one of these SNPs (c.-31G>A) in 143 Massese sheep and in another 13 sheep breeds (for a total of 351 animals). The Massese breed was fixed for allele c.-31A, whereas in all other breeds allele c.-31 G was the most frequent or with frequency of 0·50. At the same nucleotide position the cattle MC1R gene carries the G nucleotide. Using these data we developed a method to detect adulterating milk (from other sheep breeds or from cow) in Massese dairy products based on the analysis of the c.-31G>A SNP. We first tested the sensitivity of the protocol and then applied it to analyse DNA extracted from ricotta and Pecorino cheese obtained with only Massese milk or obtained with unrestricted sheep and cattle milk. To our knowledge, this system represents the first one that can be used for breed authentication of a sheep production and that, at the same time, can reveal frauds derived from the admixture of milk of an unreported species. Keywords: authentication, Massese, MC1R, mono-breed products, sheep breeds, SNP. Massese is an Italian sheep breed, with black or grey coat biodiversity, as already achieved by several other dairy and colour, mainly reared in the Tuscany and Emilia Romagna meat mono-breed animal products (Fontanesi 2009). regions. It accounts for about 5,000 animals registered to the However, in order to be profitable, this marketing link herdbook. Massese is considered a dairy breed even if its between Massese breed and its products should be defended importance for lamb meat has increased during the last against fraudsters who include milk or lamb meat of other years. Recently, emerging interests in this breed have sheep breeds in Massese labelled productions. resulted in the production of Pecorino cheese obtained Another important problem of ovine dairy products is with only Massese milk and in marketing heavy lamb meat of fraud involving the use of unreported cow milk mixed with Massese breed. These mono-breed labelled products have ovine milk. This fraud can be easily detected with the use of been developed in order to differentiate productions and, in conventional or DNA based methods, therefore the appli- turn, to improve profitability with expected impacts on rural cation of protocols to evidence the presence of cow milk in economy of marginal areas and conservation of ovine ovine dairy products (species identification) is just a matter of sensitivity and practical implementation of specific proto- cols (e.g. Moio et al. 1990; Anguita et al. 1997; Bottero et al. *For correspondence; e-mail: [email protected] 2003). On the contrary, the identification of the breed of †Authors Fontanesi & Beretti1 contributed equally to this work origin of animal products still remains a challenge in all farm Genetic authentication of sheep dairy products 123 animal species, including sheep. In general, if the question is the others by the common presence of a polymorphism at the breed level it is better to use the terms of breed (c.-31G >A) in the 5′-untranslated region (5′-UTR) (Fontanesi authentication because what is requested is to confirm that et al. 2010a). the claims about the breed of origin of the products are true. As a first step to identify a DNA marker that could be useful Two approaches that use DNA marker information have for authentication of Massese sheep dairy products, we been proposed for breed authentication: i) a probabilistic further investigated the presence and distribution of the approach, mainly based on the use of highly variable micro- MC1R c.-31G > A SNP in a larger number of Massese sheep satellites, AFLP markers or tens of single nucleotide poly- and in several other sheep breeds. Moreover, analysing this morphisms (SNPs) combined with different computational SNP, we set up a protocol to investigate admixture of milk of analyses that assign individuals to a particular breed with a different sheep breeds and/or cattle milk in Massese dairy certain probability (e.g. Ciampolini et al. 2000; Maudet et al. products. To our knowledge, this system represents the first 2002; Negrini et al. 2009); ii) a deterministic approach, one that can be used for breed and species authentication at based on the use of a few breed specific or exclusive the same time. markers, whose usefulness is due only to their fixation or absence in the considered breeds and, as a consequence, in the analysed products (e.g. Maudet & Taberlet 2002; Materials and Methods D’Alessandro et al. 2007; Russo et al. 2007). It is quite Animals and dairy products clear that the probabilistic approach cannot be applied for breed authentication of dairy products, because they usually Blood, milk and/or hair were collected from 351 sheep of 14 derive from milk of more than one animal. On the contrary, different breeds (Table 1). Massese, Sarda, and Valle del the deterministic approach can be applied to a mixture of Belice (the breeds with the larger number of samples) sheep products obtained from more animals as it relies on the were sampled from four, three, and three different flocks in identification of markers that are present or absent in all the North of Italy (Massese and Sarda) and in Sicily (Valle del (or most) animals of a particular breed. However, the main Belice), respectively. Samples from all other breeds were problem for this approach is the identification of DNA collected from one or two flocks or were obtained from markers with these characteristics. Useful markers for this animals analysed for pedigree verification by the Italian purpose can be identified by looking at mutations in genes Breeder Association laboratory. In addition, hair or milk determining the most important traits that differentiate the samples were collected from five Italian Holstein and five breeds, like coat colour (Russo & Fontanesi 2004; Fontanesi Italian Brown cattle. 2009). Three samples of Pecorino cheese (3–6 months old) and A large number of genes affect coat colour in mammals one sample of ricotta cheese obtained with only Massese but two main loci (Agouti and Extension) are the major deter- milk were purchased directly from the producers. Another minants of the relative amounts of black/brown (eumelanin) cheese sample, purchased directly from the producer and red/yellow (phaeomelanin) pigments produced in (3 months old), was prepared with Massese milk mixed melanocytes (Searle 1968). These loci encode for the agouti with about 20% cows’ milk. Three other Pecorino cheeses signalling protein (ASIP) and melanocortin 1 receptor (4–6 months old) not labelled as mono-breed products were (MC1R) genes, respectively (Bultman et al. 1992; Robbins purchased in retailer markets of North Italy together with et al. 1993). Mutations in these genes have been shown to a sample of cheese produced with both ovine and bovine affect coat colours in a large number of mammals, including milk (3 months old). These products were considered as several farm animal species like cattle (Klungland et al. obtained from undefined sheep without breed limitation. 1995; Girardot et al. 2006), pig (Kijas et al. 1998), horse (Marklund et al. 1996), goat (Fontanesi et al. 2009a, b), and DNA extraction rabbit (Fontanesi et al. 2006, 2010b). Mutations in the ASIP and MC1R genes have been also shown to affect coat colour DNA from individual samples was extracted using a stan- in sheep (Våge et al. 1999; Norris & Whan, 2008; Royo et al. dard phenol-chloroform protocol for blood, the Wizard® 2008; Fontanesi et al. 2011). We recently re-sequenced the Genomic DNA Purification kit for blood and milk (Promega MC1R gene in several sheep breeds and confirmed the Corporation, Madison, WI, USA) or rapid extraction presence of two missense mutations (p.M73 K and methods for milk and hair roots (Russo et al. 2007). For p.D121N) causing the dominant black Extension (ED) allele. dairy products (cheese and ricotta cheese), DNA was ex- We also identified a novel MC1R missense mutation tracted using a commercial kit designed for blood (QIAamp (p.R67C) that we suggested to cause the recessive e allele DNA Blood Midi Kit, Qiagen) as reported by Russo et al. at the ovine Extension series (Fontanesi et al. 2010a). In (2007). Briefly, about 1–2 g cheese was homogenized in a addition, we determined four MC1R haplotypes derived 15 ml tube.