title: Developmental competence and expression of the Hsp 70.1 gene in oocytes obtained from Bos indicus and Bos taurus dairy cows in a tropical environment.
abstract: Bos indicus cows usually have better reproductive performance in tropical and subtropical regions than Bos taurus cows, presumably due to their better adaptation to tropical environments. The aim of this study was to evaluate the developmental competence and expression of the Hsp 70.1 gene in immature oocytes from B. taurus (Holstein) and B. indicus (Gyr) dairy cows raised in a tropical region. Cumulus-oocyte complexes were obtained by transvaginal ultrasound-guided follicle aspiration between spring and early autumn, and subjected to in vitro maturation and fertilization. Presumptive zygotes were co-cultured with their own cumulus cells in CR2aa media with 10% fetal calf serum; Grade 1 blastocysts were transferred to synchronized crossbred recipients. The total RNA was extracted from immature Holstein and Gyr oocytes (three pools for each breed) and relative quantification of the Hsp 70.1 transcripts was performed by real time PCR after reverse transcription. Cleavage and blastocyst rates were greater (P<0.05) for Gyr (n=390 oocytes) than Holstein (n=505) breed (66.7% versus 53.1% of cleavage and 19.6% versus 10.8% of blastocysts, respectively), but pregnancy rates were not significantly different following transfer to recipients (44.5% for 36 Gyr embryos; 60% for 10 Holstein embryos). Holstein immature oocytes had a higher level (P<0.05) of Hsp 70.1 relative expression (1.82+/-0.22; mean+/-S.E.M.) than Gyr oocytes (1.12+/-0.11). In conclusion, Gyr oocytes obtained in a tropical region were less subject to stress and more likely to develop (after IVF) than Holstein oocytes.
authors.affiliation: Embrapa Dairy Cattle, Juiz de Fora, MG, Brazil. camargo@cnpgl.embrapa.br
authors.forename: L S A
authors.initials: LS
authors.lastname: Camargo
authors.forename: J H M
authors.initials: JH
authors.lastname: Viana
authors.forename: A A
authors.initials: AA
authors.lastname: Ramos
authors.forename: R V
authors.initials: RV
authors.lastname: Serapião
authors.forename: W F
authors.initials: WF
authors.lastname: de Sa
authors.forename: A M
authors.initials: AM
authors.lastname: Ferreira
authors.forename: M F M
authors.initials: MF
authors.lastname: Guimarães
authors.forename: V R
authors.initials: VR
authors.lastname: do Vale Filho
mesh_terms: D000818:Animals; D001938:Brazil; D002417:Cattle / Q000502:physiology*; D004624:Embryo Transfer / Q000662:veterinary*; D047108:Embryonic Development / Q000502:physiology*; D005260:Female; D005307:Fertilization in Vitro / Q000662:veterinary*; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D008297:Male; D009865:Oocytes / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D011247:Pregnancy; D012313:RNA / Q000737:chemistry / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D014329:Tropical Climate
chemical_list: D018840:HSP70 Heat-Shock Proteins; C081884:heat-shock protein 70.1; D012313:RNA