Use of microsatellites as genomic markers to study resistance to cowdriosis

Abstract

Creole goats from Guadeloupe are considered to belong to a same breed. However, following their geographical origin, they can be resistant or susceptible to cowdriosis. A previous study showed that resistance to cowdriosis is most likely under genetic control. The aim of the present study is to provide the basic tools in order to find goat genomic markers correlating with resistance to cowdriosis. What is needed to accomplish such a task is to detect highly polymorphic regions evenly distributed through the genome which will serve as landmarks. Thus, portions of the genome involved in determining a given character can be followed in populations. Such useful landmarks exist and are called microsatellites ; they have already been used with success to map particular traits in the mouse and human species. Microsatellite sequences are composed of di- or trinucleotide repeats, the polymorphism is based on the fact that the number of repeats can vary between individuals. If flanked by non-repetitive sequences, they can be easily detected by the polymerase chain reaction (PCR) techniques. Primers surrounding five microsatellites, which were previously characterized in the bovine genome, were successfully applied on the goat genome. DNA from 70 goats of the Creole (30), Sahelian (10), Guinean (10), Saanen (10) and Alpina (10) breeds was prepared and subjected to PCR. Polymorphism was detected in all five satellites and 3, 4, 8, 14 and 15 alleles were revealed for each microsatellite, respectively. More microsatellites have been found to be useful and will be tested further. Concurrently, Creole goat families involving the crossing of resistant and susceptible animals are being constituted. The technology described here will be applied on DNA of goats of the F1 generation to assess whether a given polymorphic genetic region segregates with the character of resistance to cowdriosis.