Population Genetics

African Y chromosome and mtDNA divergence provides insight into the history of click languages. Knight, A et al. Curr. Biol. 13, 464–473 (2003)

The authors carried out a phylogenetic analysis of Y chromosome and mitochondrial DNA sequences from a number of African ethnic groups, including those that use click consonants. All click-speaking peoples, such as the San, are limited to southern Africa, except for the Hadzabe people of eastern Africa. Sequence analysis shows that the San and the Hadzabe are distantly related, which indicates that the origin of click consonants might date back to early in the history of modern humans.

Evolution

Molecular genetics and evolution of melanism in the cat family. Eizirik, E. et al. Curr. Biol. 13, 448–453 (2003)

Mutations in agouti signalling protein (ASIP) and melanocortin-1 receptor (MC1R) are associated with melanism in mice. Eizirik et al. cloned and sequenced these genes from cat species and found that melanic jaguars and jaguarundis carry two different deletions in MC1R, whereas black-coloured domestic cats have a deletion in ASIP. Because these mutations were not found in melanistic cats from five other species, there must have been at least four independent genetic origins of melanism in the cat family.

Epigenetics

Effects of tethering HP1 to euchromatic regions of the Drosophila genome. Li, Y. et al. Development 130, 1817–1824 (2003)

Heterochromatin protein 1 (HP1) is a non-histone chromosomal protein. Li et al. found that, when tethered to euchromatic sites, HP1 silenced nearby reporters. HP1 has been shown to interact with the methylated lysine 9 of histone 3 at centric regions, but in this system, the methylation requirement might be bypassed because silencing is not dependent on the dosage of the histone methyltransferase SU(VAR)3-9.

RNA World

The microRNAs of Caenorhabditis elegans. Lim, L. P. et al. Genes Dev. 17 (10.1101/gad.1074403)

Lim et al. used a computer program, called MiRscan, to identify 35 new candidate miRNA genes in Caenorhabditis elegans. Candidates were verified by sequencing small RNA clones and Northern blots. Extensive cloning of small RNAs identified a further 20 new miRNAs, taking the total of validated C. elegans miRNAs to 88 — at least one-third of which have homologues in humans and other vertebrates. The authors also investigated the expression patterns of 62 C. elegans miRNAs and found that one-third were differentially expressed during larval development.