Uso de herramientas genómicas en Ciencia animal

CEST+I: Chile-European Union STI Initiative. CEST+I Invitation for expressions of interest - Working Visits in Europe and ChileSeminario celebrado en la Universidad de La Frontera (UFRO

Looking for adaptive footprints in the HSP90AA1 ovine gene

BackgroundClimatic factors play an important role in determining species distributions and phenotypic variation of populations over geographic space. Since domestic sheep is managed under low intensive systems animals could have retained some genome adaptive footprints. The gene encoding the Hsp90? has been extensively studied in sheep and some polymorphisms located at its promoter have been associates with differences in the transcription rate of the gene depending on climatic conditions. In this work the relationships among the distribution and frequencies of 11 polymorphisms of the ovine HSP90AA1 gene promoter in 31 sheep breeds and the climatic and geographic variables prevailing in their regions of origin have been studied. Also the promoter sequence has been characterized in 9 species of the Caprinae subfamily. ResultsCorrelations among several climatic variables and allele frequencies of the polymorphisms of the HSP90AA1 gene promoter linked with differences in the transcription activity of the gene under heat stress conditions have been assessed. A group of breeds reared in semi dry climates have high frequencies of the insertion allele of the g.667-668insC associated with the heat stress response. Other group of breeds native to semi arid conditions showed very low frequencies of this same allele. However, in some cases, this previous correlation has not been achieved, revealing the high levels of gene flow among populations occurred following domestication. The Bayesian Test of Beaumont and Balding identified two outlier loci, the g.522A?>?G and g.703_704del(2)A candidates to balancing and directional selection, respectively. Polymorphisms detected in O. aries are also present in several species of the Caprinae subfamily being C. hircus, O. musimon and O. moschatus those sharing the highest number of them with O. aries.ConclusionsDespite domestication, sheep breeds showed some genetic footprints related to climatic variables. Adaptation of breeds to heat climates can suppose a selective advantage to cope with global warming caused by climatic change. Polymorphisms of the HSP90AA1 gene detected in the Ovis aries species are also present in wild species from the Caprinae subfamily, indicating a great antiquity of these mutations and its importance in the adaptation of species to past climatic conditions existing in its native environments.Publishe

Estudo da influência dos genes calpaína (CAPN1) e calpastatina (CAST) na dureza da carne bovina

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Ovine HSP90AA1 Expression Rate Is Affected by Several SNPs at the Promoter under Both Basal and Heat Stress Conditions

The aim of this work was to investigate the association between polymorphisms located at the HSP90AA1 ovine gene promoter and gene expression rate under different environmental conditions, using a mixed model approach. Blood samples from 120 unrelated rams of the Manchega sheep breed were collected at three time points differing in environmental conditions. Rams were selected on the basis of their genotype for the transversion G/C located 660 base pairs upstream the gene transcription initiation site. Animals were also genotyped for another set of 6 SNPs located at the gene promoter. Two SNPs, G/C−660 and A/G−444, were associated with gene overexpression resulting from heat stress. The composed genotype CC−660-AG−444 was the genotype having the highest expression rates with fold changes ranging from 2.2 to 3.0. The genotype AG−522 showed the highest expression levels under control conditions with a fold change of 1.4. Under these conditions, the composed genotype CC−601-TT−524-AG−522-TT−468 is expected to be correlated with higher basal expression of the gene according to genotype frequencies and linkage disequilibrium values. Some putative transcription factors were predicted for binding sites where the SNPs considered are located. Since the expression rate of the gene under alternative environmental conditions seems to depend on the composed genotype of several SNPs located at its promoter, a cooperative regulation of the transcription of the HSP90AA1 gene could be hypothesized. Nevertheless epigenetic regulation mechanisms cannot be discarded.Publishe

Differences in the Ovine HSP90AA1 Gene Expression Rates Caused by Two Linked Polymorphisms at Its Promoter Affect Rams Sperm DNA Fragmentation under Environmental Heat Stress Conditions

Heat shock (HS) is one of the best-studied exogenous cellular stresses. Almost all tissues, cell types, metabolic pathways and biochemical reactions are affected in greater or lesser extent by HS. However, there are some especially thermo sensible cellular types such as the mammalian male germ cells. The present study examined the role of three INDELs in conjunction with the -660G/C polymorphism located at the HSP90AA1 promoter region over the gene expression rate under HS. Specially, the -668insC INDEL, which is very close to the -660G/C transversion, is a good candidate to be implied in the transcriptional regulation of the gene by itself or in a cooperative way with this SNP. Animals carrying the genotype II-668 showed higher transcription rates than those with ID-668 (FC = 3.07) and DD-668 (FC = 3.40) genotypes for samples collected under HS. A linkage between gene expression and sperm DNA fragmentation was also found. When HS conditions were present along or in some stages of the spermatogenesis, alternative genotypes of the -668insC and -660G/C mutations are involved in the effect of HS over sperm DNA fragmentation. Thus, unfavorable genotypes in terms of gene expression induction (ID-668GC-660 and DD-668GG-660) do not produce enough mRNA (stored as messenger ribonucleoprotein particles) and Hsp90α protein to cope with future thermal stress which might occur in posterior stages when transcriptional activity is reduced and cell types and molecular processes are more sensible to heat (spermatocytes in pachytene and spermatids protamination). This would result in the impairment of DNA packaging and the consequent commitment of the events occurring shortly after fertilization and during embryonic development. In the short-term, the assessment of the relationship between sperm DNA fragmentation sensitivity and ram’s fertility will be of interest to a better understanding of the mechanisms of response to HS and its consequences on animal production and reproduction performance.Publishe

A SNP in the HSP90AA1 gene 5′ flanking region is associated with the adaptation to differential thermal conditions in the ovine species

Molecular chaperones have long been understood to be preferentially transcribed in response to multiple perturbations of the cellular homeostasis. In this study, several polymorphisms in the gene encoding the inducible form of the cytoplasmic Hsp90 (HSP90AA1) were addressed in 24 sheep breeds reared in different climatic regions of Europe, Africa, and Asia. Significant differences in the genotype frequencies for a C/G single nucleotide polymorphism (SNP) located at position −660 in the HSP90AA1 5′flanking region were found between the different breeds. Regression analyses reflected significant correlations (from 0.41 to 0.62) between the alternative genotypes of this polymorphism and several climatic and geographic variables characteristic of the regions where these breeds are reared. Real-time analysis revealed that animals bearing the CC−660 genotype presented higher expression levels than those presenting the CG−660 or GG−660 in summer, but not in spring. Mutation at −660 site seems to affect HSP90AA1 transcription rates which could have important effects on the adaptation to different environmental conditions in sheep. Thus, the variability found in the genotype frequencies for the SNP at −660 in the ovine HSP90AA1 locus could be the result of the different environmental pressures occurring in the regions where these breed are maintained.AGRAMA breeders association, CSIC-León (Spain), CITA-Aragón (Spain), Centro Nacional de Referencia de EETs (Spain), Universidad de Zaragoza (Spain), NEIKER-Vitoria (Spain), Centro de Investigación La Orden-Valdesequera Junta de Extremadura (Spain), Dr. Julián Garde from the Universidad de Castilla-La Mancha (Spain), INIA-Madrid (Spain), and Dr Maziek Murawski from the University of Cracow (Poland) have provided biological samples. We are also very grateful to Dr. Jaime Cubero from INIA for his logistic support and to Helen Neumann for the English corrections. RTA2006-00104-00-00 and RZ2004-28 INIA projects have provided refunding to develop the experimental work

Microbiota Reproductiva

5 Pág.Peer reviewe

The Spanish Assaf sheep breed in the province of Leon

The Spanish Assaf sheep breed, original from Israel, was introduced in Spain in the seventy's, with a exceptional diffusion in the Autonomous Region of Castilla-León, where the importance of this breed is showed by the high census and its contribution to the agrarian production. This dairy sheep breed presents a higher production level than others native races from this region. This implies a racial change in herds and in the traditional management system, based on intensive productions. However, the Spanish Assaf breed neither has been recognized nor coordinated by any official organization until some years ago, so there has not been applied a specific breeding program. Nowadays, breeders and Deputation of León have implemented an official milking recording system, and the collection of pedigree data for the flocks involved in the selection program. It has also been developed an artificial insemination system in order to obtain tested sires. Slight increases in the number of flocks and ewes in milking recording, milk production, artificial inseminated females and number of tested sires have been reached due to the selection scheme. In the next future, the obtainment of a genetic progress according to the hopes of the breeders association is expected

Polymorphisms at the 5' flanking region of the HSP90AA1 gene in native Turkish sheep breeds

In this study, several polymorphisms in the gene encoding the inducible form of the cytoplasmic Hsp90 (HSP90AA1) were characterized in 10 sheep breeds reared in different climatic regions of Turkey. A new indel (AA) polymorphism located at the -704 position in the HSP90AA1 5' flanking region was found in all investigated breeds. This polymorphism create/remove a GR transcription site that could affect heat stress response and is completely linked with the C/G transversion located at -660 in the same region of the gene. Genotype frequencies differed significantly between breeds. No clearcut relationship was found between this polymorphism and climate factors, but breeds from northern Turkey had higher frequencies of the indel AA allele than breeds from southern Turkey. © 2012 Elsevier B.V