Identification and characterization of two polymorphic Ya5 Alu repeats

Two new polymorphic Alu elements (HS2.25 and HS4.14) belonging to the young (Ya5/8) subfamily of human-specific Alu repeats have been identified. DNA sequence analysis of both Alu repeats revealed that each Alu repeat had a long 3′-oligo-dA-rich tail (41 and 52 nucleotides in length) and a low level of random mutations. HS2.25 and HS4.14 were flanked by short precise direct repeats of 8 and 14 nucleotides in length, respectively. HS2.25 was located on human chromosome 13, and HS4.14 on chromosome 1. Both Alu elements were absent from the orthologous positions within the genomes of non-human primates, and were highly polymorphic in a survey of twelve geographically diverse human groups.     

Characterization of 42 highly polymorphic bovine microsatellite markers

We have isolated 42 highly polymorphic microsatellite (GT/CA)_n markers from Japanese black cattle Wagyu ( Bos taurus ). Forty-one of the markers were assigned to bovine autosomes with lod scores > 6, through linkage analyses performed on the International Bovine Reference Family Panel (IBRP). The remaining marker showed X-linked inheritance. These markers exhibited an average heterozygosity value of 0.67 with between four and 17 alleles on the IBRP.     

Mononucleotide repeats represent an important source of polymorphic microsatellite markers in Aspergillus nidulans

In fungi, microsatellites occur less frequently throughout the genome and tend to be less polymorphic compared with other organisms. Most studies that develop microsatellites for fungi focus on dinucleotide and trinucleotide repeats, and thus mononucleotide repeats, which are much more abundant in fungal genomes, may represent an overlooked resource. This study examined the relative probabilities of polymorphism in mononucleotide, dinucleotide and trinucleotide repeats in Aspergillus nidulans. As previously found, the probability of polymorphism increased with increasing number of repeating units. Dinucleotide and trinucleotide repeats had higher probabilities of polymorphism than mononucleotide repeats, but this was offset by the presence of numerous long mononucleotide repeats within the genome. Mononucleotide microsatellites with 20 or more repeating units have a probability of polymorphism similar to dinucleotide and trinucleotide microsatellites, and therefore, consideration of mononucleotide repeats will substantially increase the number of potential markers available.     

Isolation of polymorphic AGC repeats located 3' to bovine SINEs

A bovine genomic library was screened for the presence of (AGC)n repeats. All isolated AGC repeats were located adjacent to the 3′ end of bovine short interspersed nuclear elements (SINE). Polymerase chain reactions (PCR) using either two unique primers or one unique and one SINE primer produced high-resolution products without the secondary artifact ladders typical of dinucleotide microsatellites. Four AGC microsatellites were found to be polymorphic with 2–4 alleles each and polymorphism information context (PIC) values ranging between 0.26 and 0.49. One microsatellite, AR025, was mapped to chromosome 26 with the CSIRO reference families. Because of their strong association with AGC repeats and high frequency in the genome, SINE-3′ PCR may prove to be a novel source of polymorphic trinucleotide markers in the bovine genome.     

Identification of grapevine clone genotypes by use of microsatellite markers

An SSR-analysis of rootstock, technical, and table grapevine cultivar clones was performed. The allelic characteristics of grapevine cultivar clones were obtained at microsatellite loci; this characteristic can be used to identify and sertificate grapevine clone genotypes. A high level of mutation variability among the rootstock and technical cultivars was discovered. DNA passports for prospective clones were created. The genotyping results can be used for the registration of clones and the protection of breeders’ rights.