Diversidad de haplotipos del complejo principal de histocompatibilidad en equinos de la raza Árabe de la República Argentina

La diversidad de los genes del complejo principal de histocompatibilidad (MHC) es clave en su función en la presentación de antígenos en el sistema inmune. La tipificación indirecta basada en microsatélites (STR) del MHC aporta información de la variabilidad genética y de la estructura poblacional y es una estrategia para conocer procesos selectivos y evolutivos. Con el fin de caracterizar una población de caballos de raza Árabe, se identificaron los haplotipos del MHC sobre la base de tres microsatélites (UM011, DRB2-STR2 y COR112) abarcando una región de ~1Mpb. El ADN genómico se extrajo de sangre y pelo de 30 caballos de cinco haras de la provincia de Buenos Aires y los STRs se amplificaron con cebadores fluorescentes para tipificar en secuenciador automático. Seestimaron parámetros poblacionales y de diversidad y la detección de haplotipos se realizó mediante análisis de segregación y con el programa de reconstrucción de haplotipos PHASE. Se reconocieron 24 haplotipos; entre ellos, 12 se verificaron por segregación en los registros de pedigree del StudBook. Los resultados obtenidos demostraron la existencia de ligamiento con alelos conocidos de genes de clase II del equine leukocyte antigen (ELA) y la cantidad de haplotipos identificada permitió expandir la valoración de la diversidad del MHC equino. Esta metodología constituye una herramienta de utilidad y un método alternativo para la tipificación del MHC en linajes de caballos y en estudios poblacionales relacionados con la inmunidad.

First report of cerebellar abiotrophy in an Arabian foal from Argentina

Evidence of cerebellar abiotrophy (CA) was found in a six-month-old Arabian filly with signs of incoordination, head tremor, wobbling, loss of balance and falling over, consistent with a cerebellar lesion. Normal hematology profile blood test and cerebrospinal fluid analysis excluded infectious encephalitis, and serological testing for Sarcocystis neurona was negative. The filly was euthanized. Postmortem X-ray radiography of the cervical cephalic region identified not abnormalities, discounting spinal trauma. The histopathological analysis of serial transverse cerebellar sections by electron microscopy revealed morphological characteristics of apoptotic cells with pyknotic nuclei and degenerate mitochondria, cytoplasmic condensation and areas with absence of Purkinje cells, matching with CA histopathological characteristics. The indirect DNA test for CA was positive in the filly, and DNA test confirmed the CA carrier state in the parents and the recessive inheritance of the disease. To our knowledge this is the first report of a CA case in Argentina.

Effectiveness of a 95 SNP panel for the screening of breed label fraud in the Chinese meat market

Breed assignment has proved to be useful to control meat trade and protect the value of special productions. Meat-related frauds have been detected in China; therefore, 95 SNPs selected from the ISAG core panel were evaluated to develop an automated and technologically updated tool to screen breed label fraud in the Chinese meat market. A total of 271 animals from four Chinese yellow cattle (CYC) populations, six Bos taurus breeds, two Bos indicus and one composite were used. The allocation test distinguished European, Japanese and Zebu breeds, and two Chinese genetic components. It correctly allocated Japanese Black, Zebu and British breeds in 100, 90 and 89% of samples, respectively. CYC evidenced the Zebu, Holstein and Limousin introgression. The test did not detect CYC components in any of the 25 samples from Argentinean butchers. The method could be useful to certify Angus, Hereford and Japanese Black meat, but a modification in the panel would be needed to differentiate other breeds.

Hormonal regulation of pituitary FSH sialylation in male rats

Sialic acid content in FSH is modulated by GnRH and sexual steroids. Galbeta1,3GlcNAcalpha2,3-sialyltransferase (ST3Gal III) and Galbeta1,4GlcNAcalpha2,6-sialyltransferase (ST6Gal I) incorporate sialic acid residues into FSH oligosaccharides. The aim of the present study was to assess pituitary FSH molecular microheterogeneity and ST3Gal III/ST6Gal I expression during sexual development and after castration in male rats. Preparative isoelectric focusing and lectin chromatography were used to isolate FSH glycosylation variants according to charge and complexity of their oligosaccharides; RT-PCR and immunohistochemistry were employed to analyse sialyltransferase expression. Sexual development was associated with a progressive shift towards more acidic/sialylated FSH glycoforms concomitantly with an increment in ST6Gal I gene and protein expression. After castration, a transient decrease followed by a marked increase in ST6Gal I expression were observed. Less acidic/sialylated FSH glycoforms bearing incomplete oligosaccharides increased after castration, despite high ST6Gal I expression. ST3Gal III expression remained unchanged in all the experimental conditions examined. These results show that the synthesis of FSH isoforms possessing alpha2,6-linked sialic acid is hormonally regulated in male rats.

Glucocorticoid-induced apoptosis in lymphoid organs is associated with a delayed increase in circulating deoxyribonucleic acid

Pathological processes like cancer, chronic inflammation and autoimmune phenomena, all of which involve massive cell death, are associated with significant increases in circulating DNA. In order to clarify whether massive apoptosis occurring under physiological circumstances also causes DNA release into the circulation, we correlated the time-course of dexamethasone-induced intra thymic cell apoptosis with plasma DNA dynamics in rats. Animals were given 10 mg/l dexamethasone in their drinking water for up to 7 days. Sequential plasma samples were obtained during the treatment and DNA was quantitated by a micro fluorometric assay. Thymus and spleen weight as well as apoptotic cell levels were assessed at different times. Seven days of glucocorticoid treatment reduced thymic and spleen mass by 82 and 31%, respectively. Intra thymic apoptosis was maximal 24 h after the beginning of glucocorticoid treatment, declining markedly by 48 h. Very little apoptosis was observed in the spleen. Plasma DNA increased steadily during the first 4 days of glucocorticoid treatment (11.8 +/- 1.2 microg/ml on day 0; 24.2 +/- 1.6 microg/ml on day 4) beginning to decline afterward. Thymectomy but not splenectomy, drastically reduced the glucocorticoid-induced increase in plasma DNA. It is concluded that hormone-induced massive intra thymic cell death is followed by a delayed release of nucleosomal DNA into the circulation.