Resistance is conferred by an acquired penicillin-binding protein encoded by the mecA gene which is located on a large chromosomal element SCCmec.
This information, together with the fact that putative ORF 4 to 7 could be amplified from both DNA and RNA templates of ASDD shrimp while the complete 5 kb of ASDE could not, and the fact that chromosomal DNA could hybridize with the RT probe specific for NLRS suggested that NLRS was a host chromosomal element.
Following [ 82] the large chromosomes in this species are traditionally named as A (= X, the sex chromosome), J (= chromosomal element D of Mueller/Sturtevant/Novitski and homologous to arm 3L in Drosophila melanogaster [ 59]), U (= chromosomal element B and homologous to arm 2L), E (= chromosomal element C and homologous to arm 2R), and O (= chromosomal element E and homologous to arm 3R).
Although our results do not confirm the identities of the chromosomal arms fused with the sex chromosomes, independent fusions putatively involving the same chromosomal element in both species groups represents a case of extreme convergence.
Mutation, as determined by testing a uniform random number against the mutation rate (1e−4 and 1e−6) for each chromosomal element, occurs after the new chromosome is created.
Mutation, as determined by testing a uniform random number against the mutation rate (1e−3 or 1e−5) for each chromosomal element, occurs after the new chromosome is created.
Mutation, as determined by testing a uniform random number against the mutation rate (1e−3, 1e−4, 1e−5) for each chromosomal element, occurs after the new chromosome is created.
We further detect an excess of shared gene content between these very distant species, suggesting that despite the diversity of sex determining systems, the same chromosomal element is used as the X throughout a large portion of the order.
Cavalli, G. & Paro, R. The Drosophila Fab-7 chromosomal element conveys epigenetic inheritance during mitosis and meiosis.
Mechanistic models of amplification predict that DNA double-strand breaks must occur at the ends of the amplified chromosomal element.
