Higher-Order Homoplasy Tests

The Le Quesne test of character compatibility uses pairwise comparisons of characters to detect homoplasy in phylogenetic character data. If a pair of characters fails this test we can conclude that a minimum of a single extra step is required by the pair of characters. The rationale of the Le Quesne test is extended to comparisons of triplets of characters. The triplet homoplasy test can reveal that that there is a minimum of four extra steps across a triplet of characters and thus that there are at least two extra steps associated with one of the characters. The triplet homoplasy test can thus detect higher orders of homoplasy than can be detected by the pairwise Le Quesne test. The possibility of quartet and other higher-order homoplasy tests is discussed. The utility of higher-order homoplasy tests is discussed. It is suggested higher-order homoplasy tests have potential uses analogous to the uses of the Le Quesne test, particularly with respect to data exploration.     

Identification and functional analysis of NOL7 nuclear and nucleolar localization signals

Background  

NOL7 is a candidate tumor suppressor that localizes to a chromosomal region 6p23. This locus is frequently lost in a number of malignancies, and consistent loss of NOL7 through loss of heterozygosity and decreased mRNA and protein expression has been observed in tumors and cell lines. Reintroduction of NOL7 into cells resulted in significant suppression of in vivo tumor growth and modulation of the angiogenic phenotype. Further, NOL7 was observed to localize to the nucleus and nucleolus of cells. However, the mechanisms regulating its subcellular localization have not been elucidated.     

The karyotype of Alligator mississippiensis,and chromosomal mapping of the ZFY/X homologue,Zfc

Comparative mapping studies of X-linked genes in mammals have provided insights into the evolution of the X chromosome. Many reptiles including the American alligator, Alligator mississippiensis, do not appear to possess heteromorphic sex chromosomes, and sex is determined by the incubation temperature of the egg during embryonic development. Mapping of homologues of mammalian X-linked genes in reptiles could lead to a greater understanding of the evolution of vertebrate sex chromosomes. One of the genes used in the mammalian mapping studies was ZFX, an X-linked copy of the human ZFY gene which was originally isolated as a candidate for the mammalian testis-determining factor (TDF). ZFX is X-linked in eutherians, but maps to two autosomal locations in marsupials and monotremes, close to other genes associated with the eutherian X. The alligator homologue of the ZFY/ZFX genes, Zfc, has been isolated and described previously. A detailed karyotype of A. mississippiensis is presented, together with chromosomal in situ hybridisation data localising the Zfc gene to chromosome 3. Further chromosomal mapping studies using eutherian X-linked genes may reveal conserved chromosomal regions in the alligator that have become part of the eutherian X chromosome during evolution.