Search

Summary A large proportion of mammalian genomes is represented by transposable elements (TE), most of them being long interspersed nuclear elements 1 (LINE-1 or L1). An increased expression of LINE-1 elements may play an important role in cellular stress–related conditions exerting drastic effects on the mammalian transcriptome. To understand the impact of TE on the known horse transcriptome, we masked the horse EST database, pointing out that the amount is consistent with other major vertebrates. A previously developed transcript-derived fragments (TDFs) dataset, deriving from exercise-stimulated horse peripheral blood mononuclear cells (PBMCs), was found to be enriched with L1 (26.8% in terms of bp). We investigated the involvement of TDFs in exercise-induced stress through bioinformatics and gene expression analysis. Results indicate that LINE-derived sequences are not only highly but also differentially expressed during physical effort, hinting at interesting scenarios in the regulation of gene expression in relation to exercise.

It is known that moderate physical activity may have beneficial effects on health, whereas strenuous effort induces a state resembling inflammation. The molecular mechanisms underlying the cellular response to exercise remain unclear, although it is clear that the immune system plays a key role. It has been hypothesized that the physio-pathological condition that develops in athletes subjected to heavy training is caused by derangement of cellular immune regulation. The purpose of the present study was to obtain information on endurance horse gene transcription under strenuous conditions and to identify candidate genes causing immune system derangement. We performed a wide gene expression scan, using microarray technology, on peripheral blood mononuclear cells of ten horses chosen from high-level participants in national and international endurance races. The use of three different timepoints revealed changes in gene expression when post-effort samples (T1, taken immediately after the race; and T2, taken 24 h after the race) were compared with basal sample (T0, at rest). Statistical analysis showed no differences in gene expression between T0 and T2 samples, indicating complete restoration of homeostasis by 24 h after racing, whereas T1 showed strong modulation of expression, affecting 132 genes (97 upregulated, 35 downregulated). Ingenuity pathway analysis revealed that the main mechanisms and biofunctions involved were significantly associated with immunological and inflammatory responses. Real-time PCR was performed on 26 gene products to validate the array data.

Summary The Maremmano is an Italian warmblood horse breed from central Italy. We characterizedthe genetic diversity and the degree of admixture in Maremmano in comparison to 14 otherEuropean horse breeds using 30 microsatellites. Between-breed diversity explained about 9per cent of the total genetic diversity. Cluster analysis, genetic distances and genetic dif-ferentiation coefficients showed a close relationship of Maremmano with Hanoverian andLusitano in accordance with breed history.Keywords clustering analysis, Equus caballus, Maremmano.The Maremmano is an Italian warmblood horse mostly bredin the provinces of Grosseto and Viterbo (Central Italy). It isbelieved that the origin of this horse breed goes back to localEtruscan horse populations which were crossbred withmodern breeds in the last centuries. Pedigree analysis of theMaremmano horses revealed four male lines contributing11.1% to the genetic diversity of all Maremmano stallions(Silvestrelli 1991). In 1980, Maremmano breeders estab-lished a stud book for Maremmano.The objective of this study was to investigate the geneticstructure and the degree of admixture of Maremmano to-gether with the Italian nucleus of Lipizzan and Lusitano aswell as twelve further horse breeds previously characterizedby Aberle et al. (2004). This data set consisted of Hanove-rian, Arabian, Exmoor, Icelandic, Przewalski, Sorraia andall German coldblood horse breeds. We used the samemarker set of 30 autosomal microsatellites and the samePCR conditions and reference samples as described else-where (Aberle et al. 2004).A total of 146 animals that were not closely related weregenotyped in this study: Maremmano (n = 50), the Italiannucleus of Lipizzan (n = 49) and Lusitano (n = 47) fromPortugal. DNA was extracted from EDTA-blood usingstandard methods.Genetic variability of the breeds genotyped in this studywas determined by the mean number of alleles, observedand expected heterozygosities, breed-specific alleles and themolecular variance (