Determination of evolutionary relationships among sheep breeds using microsatellites

Eight ovine microsatellite loci were amplified in 40 to 50 unrelated individuals from six sheep populations representing five breeds: Romney, Border Leicester, Suffolk, Awassi, and both Australian and New Zealand Merino. For all of the microsatellite loci analyzed, there were highly significant differences in allele frequencies between samples from the different breeds. The allele frequencies generated can be used to determine the breed of an individual, given that it comes from one of the above breeds, to a high degree of accuracy. There were also some alleles that were found in only one breed, although these alleles were at such low frequencies that they are unlikely to be useful as markers for a breed. Genetic distances between breeds were obtained using Nei's formula to construct a phylogenetic tree. The tree grouped the Merino's in one branch and the Border Leicester, Suffolk, and Romney in another branch, while the Awassi, which was used as an outgroup, had its own branch. Using Nei's unbiased genetic distance formula to calculate the time of divergence of the British breeds from the Merino and the time of divergence between the Australian and the New Zealand Merino, we obtained t = 1094 and t = 227 years, respectively. Microsatellite genotyping in sheep appears to provide a useful tool for examining the evolutionary relationships between breeds.

Cloning and expression of the cervine interleukin 4 gene

Interleukin 4 (IL-4), a cytokine produced by the T helper 2 subset of T lymphocytes is involved in up regulating antibody responses. A source of recombinant cervine IL-4 would be useful for studying the immune response of deer to tuberculosis. We report here the cloning, sequencing and expression of recombinant cervine IL-4. To achieve this mRNA was isolated from red deer (Cervus elaphus) mononuclear leucocytes. First strand cDNA was synthesized from the mRNA and the IL-4 cDNA was amplified, cloned and sequenced. The IL-4 cDNA is 408 bp in length and the deduced amino acid sequence is 92% homologous with the published bovine IL-4 amino acid sequence. IL-4 was expressed using the baculovirus expression system in Spodoptera frugiperda Sf9 cells. Northern blot, SDS-PAGE analysis and bioassay were used to confirm the expression of IL-4.

The Booroola fecundity (FecB) gene maps to sheep chromosome 6

The Booroola (FecB) mutation in sheep is linked to markers from a region of syntenic homology to human chromosome HSA4q, but the chromosomal location in sheep has not been determined. Analysis of linkage in Booroola half-sib pedigrees and 17 full-sib families identified genetic linkage between platelet-derived growth factor receptor-alpha (PDGFRA) and alpha s1-casein (CSN1S1) at 12 cM (Zmax = 9.14) and between PDGFRA and the microsatellite markers BM143 and OarHH55 (Zmax = 6.28 and 3.83, respectively). The microsatellite markers OarAE101 and BM143 and genes from the linkage group (PDGFRA, SPP1, and EGF) were mapped in a partial sheep x hamster somatic cell hybrid panel. All markers identified bands specific to somatic cell hybrids containing the sheep chromosome t1 (rob6;24) or t1q (chromosome 6). In sheep the casein genes alpha s1 (CSN1S1), alpha s2 (CSN1S2), beta (CSN2), and kappa (CSN3) are tightly linked, and CSN2 has been mapped to sheep chromosome 6q23-q31. We conclude that the Booroola mutation is located within a conserved syntenic group that maps to sheep chromosome 6.

Sheep linkage mapping: nineteen linkage groups derived from the analysis of paternal half-sib families

Nineteen linkage groups containing a total of 52 markers have been identified in the sheep genome after typing large paternal half-sib families. The linkage groups range in size from 2 markers showing no recombination to a group containing 6 markers covering approximately 30 cM of the sheep genome. Thirteen of the groups have been assigned to a sheep chromosome. Three groups contain markers from bovine syntenic groups U2, U7 and U29, and one other group contains a marker that has been mapped only in humans. The remaining three groups are unassigned. This information will provide a useful foundation for a genetic linkage map of sheep.

Assignment of five polymorphic ovine microsatellites to bovine syntenic groups

A panel of bovine somatic cell hybrids was used to map ovine microsatellites. Five of seven microsatellites were assigned to five bovine syntenic groups. These microsatellites were designated D5S10 (MAF23), D1S4 (MAF46), D13S1 (MAF18), D4S3 (MAF50), and DXS2 (MAF45), mapped to syntenic groups U3 (chromosome 5), U10 (chromosome 1), U11, U13, and the X chromosome, respectively. Two remaining sheep microsatellites amplified rodent DNA in the hybrid somatic cell panel, and were not assigned to bovine syntenic groups. Assignment of ovine-derived microsatellites to bovine syntenic groups provides additional evidence of the usefulness of microsatellites for mapping closely related species. The use of ovine and bovine microsatellites will aid in development of comparative genomic maps for these two species.

DNA fingerprinting analysis of Booroola pedigrees: a search for linkage to the Booroola gene

Seven minisatellite probes from a variety of sources were used to analyse 11 paternal half-sib families in which the Booroola gene was segregating. A total of 402 bands that showed segregation in the pedigrees were examined for linkage to the Booroola gene. None of the bands showed segregation with the Booroola gene. The most likely evidence for a linked band was produced by the HaRas HVR probe in Family 902 (θ=0.0; LOD 2.3). The conclusion, however, is that the minisatellite probes used in this study could not be used as markers for the Booroola gene. The study highlighted problems associated with the use of minisatellite probes in linkage studies in half-sib families. The complex banding patterns found on fingerprinting gels was a major source of scoring error. In a few cases both of the sire's alleles could be identified at a particular locus, but in most cases only one of the alleles could be identified. For the most part, the bands had to be treated as dominant alleles. The contribution of dam alleles to the banding pattern could only be estimated. There was an indication that minisatellite loci in sheep are clustered in particular regions of the sheep genome as the rate at which bands segregated with each other was higher than one would expect from loci randomly distributed throughout the genome.

The ovine Booroola fecundity gene (FecB) is linked to markers from a region of human chromosome 4q

The autosomal Booroola fecundity gene (FecB) mutation in sheep increases ovulation rate and litter size, with associated effects on ovarian physiology and hormone profiles. Analysis of segregation in twelve families (379 female progeny) identified linkage between the mutation, two microsatellite markers (OarAE101 and OarHH55, Zmax > 9.0) and epidermal growth factor (EGF) from human chromosome 4q25 (Zmax > 3.0). The marker OarAE101 was linked to secreted phosphoprotein 1 (SPP1, which maps to chromosome 4q21-23 in man) in the test pedigrees and independent families (Zmax > 9.7). The identification of linkage between the FecB mutation and markers from human chromosome 4q is an important step towards further understanding the control of ovulation rates in mammals.

Microsatellites and associated repetitive elements in the sheep genome

To determine the frequency and clustering of a variety of simple di- and trinucleotide repeats, an Artiodactyl short interspersed element (SINE), an ovine satellite repeat, and a human Alu 1 repeat were used to screen a random selection of cosmids containing inserts of ovine genomic DNA. In total, 197 individual cosmids were digested with EcoRI and the fragments separated on 0.7% agarose gels. Southern blots of these gels were then sequentially probed with (AC)7, (CT)9, and (CAC)6 oligonucleotides, and the repeats described above. The frequency at which (AC)n, (CT)n, and (CAC)n repeats were found in the cosmids indicated that they occurred at average intervals of 65 kb, 367 kb, and 213 kb respectively within the ovine genome. The Artiodactyl SINE was the most common, occurring at an average interval of 20 kb. No human Alu 1 sequences were detected. There was a significant positive association between the (AC)n and the Artiodactyl SINE. This association is quite strong as there was significant clustering of the two repeats both within cosmids and also within the EcoRI fragments of the digested genomic fragments. With the exception of the sheep satellite sequence, which occurs in tandem arrays, none of the other repeats showed significant clustering within the 41-kb (average size) cosmid inserts. The first 25 ovine microsatellites we characterized had an average polymorphic information content (PIC) of 0.65. The different microsatellite types, containing either perfect, imperfect, or compound repeats, had similar average PICs of 0.64, 0.65, and 0.66 respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

MAF45, a highly polymorphic marker for the pseudoautosomal region of the sheep genome, is not linked to the FecXI (Inverdale) gene

A highly polymorphic dinucleotide repeat, or microsatellite, that shows partial sex-linked inheritance in sheep has been isolated from the sheep genome. Our data indicate that the locus is in the pseudoautosomal region approximately 13 cm from the boundary with the sex-linked regions. The locus, designated MAF45, has 12 alleles with a PIC of 0.84. The same primers amplify a single polymorphic locus in cattle and goats. This locus was not linked to the Inverdale gene, an X-linked gene that increases the ovulation rate in sheep.

Evolution in Oryctes baculovirus: rate and types of genomic change

Three cloned strains of Oryctes baculovirus were released into a previously unexposed population of the host insect, the coconut palm rhinoceros beetle, Oryctes rhinoceros. The experiment was conducted on Meemu Atoll in the Maldive Islands. Viruses were isolated from the beetle population at 1 year, 1.75 years, and 4 years after release. No changes in genotype were observed in viruses isolated after 1 and 1.75 years. After 4 years, however, three types of genomic change had occurred. A recombinant derived from two of the released strains, an isolate containing a 100-bp insert, and one example of a point mutation were found in the 22 isolates examined.

Engineering of an Oryctes baculovirus recombinant: insertion of the polyhedrin gene from the Autographa californica nuclear polyhedrosis virus

A cotransfection method has been developed for the generation of recombinant Oryctes baculoviruses. The permissive coleopteran cell-line DSIR-HA-1179 was transfected with a mixture of Oryctes baculovirus DNA (strain PV505) and a transfer vector. The transfer vector, a pUC8-based plasmid, contained the polyhedrin gene from the Autographa californica nuclear polyhedrosis virus, flanked by Oryctes baculovirus DNA from the HindIII fragment N. Oryctes baculovirus does not form plaques with DSIR-HA-1179 cells. Therefore an endpoint dilution method was used to screen for, recover and purify recombinants. There was no phenotypic character that could be used for detecting recombinants, so a dot blot assay was used to screen infected cultures for the presence of recombinants. A recombinant generated by this method contained the entire polyhedrin gene inserted at 98.03 map units from the designated start of the Oryctes baculovirus physical map. No evidence of transcription or translation of the polyhedrin gene was obtained.

Characterization of an early gene accelerating expression of late genes of the baculovirus Autographa californica nuclear polyhedrosis virus

The region of the Autographa californica nuclear polyhedrosis virus (AcMNPV) encompassing the EcoRI T fragment (29.0 to 30.1 map units) was characterized by DNA sequencing, transcriptional mapping, and site-directed mutagenesis. The largest transcript from this region, an early 1.7-kilobase (kb) poly(A)+ RNA, encompassed three tandem, nonoverlapping open reading frames (ORFs). The largest of these ORFs, ETL, was proximal to the 5' end of the transcript and had the capacity to encode a 28-kilodalton (kDa) polypeptide. A recombinant virus, vETL beta gal, containing the Escherichia coli beta-galactosidase (beta gal) gene fused to the N-terminal two-thirds of the ETL ORF, produced blue plaques in the presence of a chromogenic indicator of beta gal and wild-type levels of polyhedra in cell culture. This recombinant was also infectious in insect larvae by oral administration of occluded virus. Comparison of vETL beta gal and wild-type viral proteins pulse-labeled at various times postinfection (p.i.) revealed (i) absence of a virus-induced 28-kDa polypeptide, (ii) early expression of a large (approximately 130-kDa) polypeptide which may be the ETL-beta gal fusion protein, (iii) a delay in expression of early 35 and 40-kDa polypeptides, and (iv) a 4- to 6-h delay in the expression of late proteins in vETL beta gal-infected cells. Cycloheximide did not inhibit synthesis of the 1.7-kb RNA but did inhibit its shutoff, which occurs at 12 h p.i. in the absence of inhibitors. Thus, the ETL gene product is apparently an early 28-kDa protein which is necessary, directly or indirectly, for timely expression of many other AcMNPV genes. The promoter-leader regions of the 1.7-kDa transcript showed significant sequence similarities to the leader of the AcMNPV IE-1 gene. The middle ORF within the 1.7-kb transcript, ETM, would encode a hydrophobic polypeptide of 113 amino acid residues. ETS, a small ORF within and proximal to the 3' end of the 1.7-kb transcript, was also transcribed as a set of smaller (approximately 0.5-kb) RNAs initiated heterogeneously in the region between ETL and ETS and persisting throughout infection.

The AHA syndrome: arthritis, hives and angioedema

Nine patients who have intermittently exhibited the concurrent triad of arthritis or arthralgia (A), hives or urticaria (H) and angioedema (A), in the absence of associated infection or connective-tissue disease, are reported. The ratio of women to men is 4:1, with no apparent age specificity. The duration of the disease has been up to 16 years, with an average of seven acute episodes per year, lasting up to 14 days. Upper-airway angioedema has been severe in four patients. Routine laboratory studies were normal, as were studies of complement levels, and both humoral and cellular immunity. Two samples of synovial fluid from one patient contained a marked preponderance of Ia-positive macrophages. The absence of associated infection and connective-tissue disease suggests this recurrent triad represents a distinct entity, which is designated the AHA syndrome.