RESUMO
A genome linkage scan was carried out using a resource flock of 1029 sheep in six half-sib families. The families were offspring of sires derived by crossing divergent lines of sheep selected for response to challenge with the intestinal parasitic nematode Trichostrongylus colubriformis. All animals in the resource flock were phenotypically assessed for worm resistance soon after weaning using a vaccination/challenge regime. After correcting for fixed effects using a least squares linear model the faecal egg count data obtained following the first challenge and the faecal egg count data obtained after the second challenge were designated Trait 1 and Trait 2, respectively. A total of 472 lambs drawn from the phenotypic extremes of the Trait 2 faecal egg count distribution were genotyped with a panel of 133 microsatellite markers covering all 26 sheep autosomes. Detection of quantitative trait loci (QTL) for each of the faecal egg count traits was determined using interval analysis with the Animap program with recombination rates between markers derived from an existing marker map. No chromosomal regions attained genome-wide significance for QTL influencing either of the traits. However, one region attained chromosome-wide significance and five other regions attained point-wise significance for the presence of QTL affecting parasite resistance.
Assuntos
Característica Quantitativa Herdável , Doenças dos Ovinos/genética , Tricostrongilose/veterinária , Análise de Variância , Animais , Mapeamento Cromossômico , Feminino , Marcadores Genéticos , Imunidade Inata , Masculino , Ovinos , Doenças dos Ovinos/imunologia , Doenças dos Ovinos/parasitologia , Tricostrongilose/genéticaRESUMO
Hereditary sensory neuropathy type I (HSN1) is the most common dominantly inherited degenerative disorder of sensory neurons. The gene mutation was mapped to chromosome 9 in a large Australian family, descended from an ancestor from southern England who was a convict. Dawkins et al. recently reported gene mutations in the SPTLC1 gene, in this and other families. The first description of hereditary sensory neuropathy, by Hicks, was in a family from London and Exeter. To determine if the families in the present study that have SPTLC1 mutations are related to English families with HSN1 and, possibly, to the family studied by Hicks, we performed haplotype analysis of four Australian families of English extraction, four English families, and one Austrian family. Three Australian families of English extraction and three English families (two of whom have been described elsewhere) had the 399T-->G SPTLC1 mutation, the same chromosome 9 haplotype, and the same phenotype. The Australian and English families may therefore have a common founder who, on the basis of historical information, has been determined to have lived in southern England prior to 1800. The sensorimotor neuropathy phenotype caused by the 399T-->G SPTLC1 mutation is the same as that reported by Campbell and Hoffman and, possibly, the same as that originally described by Hicks.
Assuntos
Efeito Fundador , Genética Populacional , Neuropatias Hereditárias Sensoriais e Autônomas/genética , Inglaterra/etnologia , Europa (Continente)/etnologia , Haplótipos , Humanos , Dados de Sequência MolecularRESUMO
A medium-density linkage map of the ovine genome has been developed. Marker data for 550 new loci were generated and merged with the previous sheep linkage map. The new map comprises 1093 markers representing 1062 unique loci (941 anonymous loci, 121 genes) and spans 3500 cM (sex-averaged) for the autosomes and 132 cM (female) on the X chromosome. There is an average spacing of 3.4 cM between autosomal loci and 8.3 cM between highly polymorphic [polymorphic information content (PIC) > or = 0.7] autosomal loci. The largest gap between markers is 32.5 cM, and the number of gaps of > 20 cM between loci, or regions where loci are missing from chromosome ends, has been reduced from 40 in the previous map to 6. Five hundred and seventy-three of the loci can be ordered on a framework map with odds of > 1000 : 1. The sheep linkage map contains strong links to both the cattle and goat maps. Five hundred and seventy-two of the loci positioned on the sheep linkage map have also been mapped by linkage analysis in cattle, and 209 of the loci mapped on the sheep linkage map have also been placed on the goat linkage map. Inspection of ruminant linkage maps indicates that the genomic coverage by the current sheep linkage map is comparable to that of the available cattle maps. The sheep map provides a valuable resource to the international sheep, cattle, and goat gene mapping community.
Assuntos
Mapeamento Cromossômico/métodos , Ligação Genética , Genoma , Ovinos/genética , Animais , Bovinos , Feminino , Marcadores Genéticos/genética , Genótipo , Masculino , Meiose/genética , Repetições de Microssatélites/genética , Repetições Minissatélites/genética , Polimorfismo de Fragmento de RestriçãoRESUMO
Hereditary sensory neuropathy type I (HSN1) is the most common hereditary disorder of peripheral sensory neurons. HSN1 is an autosomal dominant progressive degeneration of dorsal root ganglia and motor neurons with onset in the second or third decades. Initial symptoms are sensory loss in the feet followed by distal muscle wasting and weakness. Loss of pain sensation leads to chronic skin ulcers and distal amputations. The HSN1 locus has been mapped to chromosome 9q22.1-22.3 (refs. 3,4). Here we map the gene SPTLC1, encoding serine palmitoyltransferase, long chain base subunit-1, to this locus. Mutation screening revealed 3 different missense mutations resulting in changes to 2 amino acids in all affected members of 11 HSN1 families. We found two mutations to be located in exon 5 (C133Y and C133W) and one mutation to be located in exon 6 of SPTLC1 (V144D). All families showing definite or probable linkage to chromosome 9 had mutations in these two exons. These mutations are associated with increased de novo glucosyl ceramide synthesis in lymphoblast cell lines in affected individuals. Increased de novo ceramide synthesis triggers apoptosis and is associated with massive cell death during neural tube closure, raising the possibility that neural degeneration in HSN1 is due to ceramide-induced apoptotic cell death.
Assuntos
Aciltransferases/genética , Neuropatias Hereditárias Sensoriais e Autônomas/enzimologia , Neuropatias Hereditárias Sensoriais e Autônomas/genética , Mutação , Aciltransferases/química , Sequência de Aminoácidos , Apoptose/genética , Sequência de Bases , Mapeamento Cromossômico , Cromossomos Humanos Par 9/genética , Primers do DNA/genética , Éxons , Glucosilceramidas/biossíntese , Neuropatias Hereditárias Sensoriais e Autônomas/patologia , Humanos , Dados de Sequência Molecular , Subunidades Proteicas , Homologia de Sequência de Aminoácidos , Serina C-PalmitoiltransferaseRESUMO
Hereditary sensory neuropathy type I (HSN-I) is an autosomal dominant peripheral neuropathy affecting sensory and motor neurons. The disease involves distal sensory loss, distal muscle wasting and weakness, and variable neural deafness. The HSN1 locus has been mapped to a genetic interval of 3-4 cM on chromosome 9q22.1-q22.3 and is flanked by markers D9S1781 and FB19B7. This interval contains the gene NFIL3, a transcription factor that is regulated by the cytokine IL-3. Northern blot analysis of NFIL3 showed a ubiquitously expressed 2.2-kb mRNA. Expression was highest in the lung, with lower levels of expression in the brain and spinal cord. Mutation analysis by direct sequencing of reverse transcription/polymerase chain reaction products from HSN-I patients excluded the coding region of the NFIL3 from being involved in the pathogenesis of HSN-I.
Assuntos
Análise Mutacional de DNA , Proteínas de Ligação a DNA/genética , Neuropatias Hereditárias Sensoriais e Autônomas/genética , Fatores de Transcrição/genética , Fatores de Transcrição de Zíper de Leucina Básica , Northern Blotting , Encéfalo/metabolismo , Primers do DNA , Proteínas de Ligação a DNA/biossíntese , Fatores de Ligação G-Box , Expressão Gênica , Testes Genéticos , Humanos , Pulmão/metabolismo , Dados de Sequência Molecular , Especificidade de Órgãos , RNA Mensageiro/biossíntese , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Medula Espinal/metabolismo , Fatores de Transcrição/biossínteseAssuntos
Mapeamento Cromossômico , DNA Satélite/genética , Polimorfismo Genético , Sequências Repetitivas de Ácido Nucleico , Ovinos/genética , Alelos , Animais , Sequência de Bases , Primers do DNA , Feminino , Frequência do Gene , Masculino , Dados de Sequência Molecular , Reação em Cadeia da PolimeraseAssuntos
DNA Satélite/genética , Polimorfismo de Fragmento de Restrição , Ovinos/genética , Alelos , Animais , Sequência de Bases , Mapeamento Cromossômico , Primers do DNA/genética , Feminino , Frequência do Gene , Marcadores Genéticos , Masculino , Dados de Sequência Molecular , Oligodesoxirribonucleotídeos/genética , Reação em Cadeia da Polimerase , Sequências Repetitivas de Ácido NucleicoRESUMO
Polymorphic bands were detected within the DQB and DRB regions of the ovine major histocompatibility complex by probing TaqI digested DNA from three large sheep half-sib families derived from a highly resistant ram. All animals were phenotypically assessed for Haemonchus contortus resistance by faecal egg counts and associations with RFLP bands and haplotypes were estimated using mixed model, best linear unbiased prediction statistical methods. Although the highly resistant sire was homozygous at the MHC, no significant associations were found between any band or haplotype and faecal egg count.
Assuntos
Hemoncose/veterinária , Complexo Principal de Histocompatibilidade/genética , Polimorfismo de Fragmento de Restrição , Doenças dos Ovinos/imunologia , Animais , Southern Blotting , Feminino , Hemoncose/genética , Haplótipos , Imunidade Inata/genética , Masculino , Ovinos , Doenças dos Ovinos/genética , Doenças dos Ovinos/parasitologiaRESUMO
SUMMARY: Restriction fragment length polymorphism (RFLP) within the Major Histocompatibility Complex (MHC) Class II region was examined in 83 sheep. Two restriction enzymes (TaqI and PvuII) and two human cDNA probes (DQα-folke and DRß-malta) were used to probe Southern blots from all sheep. In addition, a second human DRß probe (signe) and the restriction enzyme, EcoRI, were used for 15 sheep to match previously published polymorphism in sheep using the same probe/enzyme combination. All sheep were part of an experiment in which footrot was experimentally induced and then controlled through vaccination with an homologous rDNA pilus vaccine. The four main probe/enzyme combinations detected extensive polymorphism; in total 74 bands were detected of which only 2 were present in all sheep. A similar level of polymorphism was also seen with the EcoRI/DRß-signe probe/enzyme combination, which was greater than previously published for sheep, cattle or goats. After accounting for cross-hybridising bands, the sheep DRß region appeared to be more polymorphic than the DQα region. Similarly the TaqI restriction enzyme revealed more polymorphism than the PvuI enzyme (40 and 34 bands respectively). For all 74 bands, 7 main clusters were identified both within and across probe/enzyme combinations. After removing bands/clusters which were of extreme frequency (< 0.10 and > 0.90), a total of 53 bands/clusters were analysed for their potential association with footrot and antibody responses. One band was significantly associated with susceptibility to footrot over the 27-week period during which footrot was measured. In addition, two single bands and one cluster were significantly (P > 0.001) associated with residual footrot infection after vaccination. Nine bands/clusters were associated with antibody titre during infection, and one cluster with antibody titre after vaccination. These results suggest a possible involvement for genetic polymorphism within the ovine Class II region in variation in response to footrot. ZUSAMMENFASSUNG: Krankheitsresistenz bei Merinos, II. RFLP's in Klasse II MHC und ihre Verbindung mit der Moderhinkeresistenz Restriktionsfragmentlängenpolymorphismus (RFLP) innerhalb des Haupthistokompatibilitätskomplexes (MHC) Klasse II Region wurde bei 83 Schafen untersucht. Zwei Restriktionsenzyme (TaqI und PvuII) und zwei humane cDNA-Sonden (DQα-folke und DRß-malta) wurden für Southern blots bei allen Schafen verwendet. Zusätzlich wurde eine zweite humane DRß-Sonde (signe) und das Restriktionsenzym EcoRI bei 15 Schafen zum Vergleich mit früher publizierten Polymorphismus mit den selben Enzym/Sondenkombinationen durchgeführt. Alle Schafe waren Teil eines Versuches, in welchem Moderhinke experimentell induziert und dann durch Vaccination mit homologer rDNA-pilus vaccine bekämpft worden war. Die 4 Enzym/Sondenkombinationen entdeckten extensiven Polymorphismus. Insgesamt 74 Banden wurden entdeckt, wovon nur zwei in allen Schafen vorhanden waren. Ein ähnliches Ausmaß von Polymorphismus wurde auch mit der EcoRI/DRß-signe Enzym/Sondenkombination entdeckt, das größer war als bisher für Schafe, Rinder oder Ziegen publiziert. Nach Berücksichtigung der Kreuz-Hybridisierungsbande scheint die Schaf-DRß-Region stärker polymorph als die DQα-Region zu sein. Ähnlicherweise zeigte das TaqI Restriktionsenzym mehr Polymorphismus als das PvuII Enzym (40 bzw. 34 Bande). Bei allen 74 Banden wurden sieben Hauptkluster identifiziert, sowohl innerhalb als auch über Enzym/Sondenkombinationen. Nach Entfernung von Banden/Kluster mit extremen Häufigkeiten (< 0,10 bzw. > 0.9) wurden insgesamt 53 Bande/Kluster hinsichtlich ihrer potentiellen Verbindung mit Moderhinke und Antikörperreaktion analysiert. Ein Band war signifikant mit Moderhinkeempfindlichkeit während der 27-Wochenperiode assoziiert. Zusätzlich waren zwei einzelne Bande und ein Kluster signifikant (p > 0,001) assoziiert mit Moderhinkeinfektion nach der Impfung. 9 Band/Kluster waren mit Antikörperspiegel während der Infektion verbunden und ein Kluster mit Antikörperspiegel nach Impfung. Die Ergebnisse deuten auf Zusammenhang des genetischen Polymorphismus innerhalb der ovinen Klasse II-Region mit Variabilität im Moderhinkeverlauf.
RESUMO
SUMMARY: RFLP analysis was used to investigate the effect of genetic variation in the Major Histocompatibility Complex (MHC) class II region on resistance of sheep to the intestinal parasite Trichostrongylus colubriformis, using faecal egg count (fec) as the measure of resistance. RFLP analysis of DNA from 335 sheep with the restriction enzymes TaqI, PvuII and HindIII, and DRB, DQA and DQB human class II MHC cDNA clones, revealed 238 bands, of which 233 were polymorphic. Sixteen bands were associated with a significant effect on fec, when analysed using a mixed model, best linear unbiased prediction statistical methods. However, when p values were corrected for the number of bands tested the associations were no longer significant. While no individual band had a significant effect on fec, Fisher's X(2) test of the distribution of p-values showed that RFLP bands, when considered together, do account for a significant proportion of variation in fec. One hundred and thirteen offspring from 11 halb-sib families were classified according to which MHC haplotype they had inherited from their sire. While there was overall no convincing statistical evidence of an effect of MHC haplotype on resistance, results in one family showed evidence for a repeatable MHC effect. ZUSAMMENFASSUNG: Die MHC-Klasse II Region und Resistenz gegenüber Darmparasiten beim Schaf RFLP Analyse betrifft die Auswirkung genetischer Unterschiede im Haupthistokompatibilitäts-Komplex (MHC) Klasse II Region auf Resistenz von Schafen gegen den Darmparasiten Trichostrongylus colubriformis, wobei die fäkale Eizahl (fec) als Maß der Resistenz verwendet worden ist. Die RFLP-Analyse der DNA von 335 Schafen mit Restriktionsenzymen TaqI, PvuII und HndIII und DRB, DQA und DQB menschlicher Klasse II MHC cDNA Klone ergab 238 Bande, wovon 233 polymorph waren. 16 Bande waren mit einer signifikanten Wirkung auf fec verbunden, wobei zur Analyse das gemischte Modell der BLUP verwendet worden ist. Allerdings, nach Korrektur der p-Werte für die Zahl der geprüften Bande zeigt sich die Assoziation nicht länger als signifikant. Während kein individuelles Band eine signifikante Wirkung auf FEC zeigte, ergab Fisher's test hinsichtlich Verteilung der p-Werte Signifikanz bei Gesamtbetrachtung. 113 Nachkommen von 11 Halbgeschwister-Familien wurden nach dem MHC Haplotyp des Vatertieres klassifiziert. Es ergab sich kein insgesamt überzeugender statistischer Hinweis auf Wirkung der MHC Haplotypen, doch in einer Familie Hinweis auf wiederholbare MHC Effekte.
