analysis of the race-and-intelligence debate, and an absorbing tale of the bizarre cult that gathered around the novelist Ayn Rand, described by one of her followers as " the greatest human being who has ever lived. " Shermer's generalizations are less compelling. It scarcely needs a quotation from Sydney Hook (who he?) to instruct us that " Raphael's Sistine Madonna without Raphael, Beethoven'...

In vitro, the methyl-directed mismatch repair system of Escherichia coli requires the single-strand exonuclease activity of either ExoI, ExoVII, or RecJ and possibly a fourth, unknown single-strand exonuclease. We have created the first precise null mutations in genes encoding ExoI and ExoVII and find that cells lacking these nucleases and RecJ perform mismatch repair in vivo normally such that...

Opportunistic pathogens like Cryptococcus neoformans are constantly exposed to changing environments, in their natural habitat as well as when encountering a human host. This requires a coordinated program to regulate gene expression that can act at the levels of mRNA synthesis and also mRNA degradation. Here, we find that deletion of the gene encoding the major cytoplasmic 5'→3' exonuclease Xr...

Ionizing radiation causes different types of genetic damage, ranging from base modifications to single- and double-stranded DNA breaks, which may be deleterious or even lethal to the cell. There are different repair or tolerance mechanisms to counteract the damage. Among them is the Escherichia coli SOS system: a set of genes that becomes activated upon DNA damage to confer better opportunities...

We report the identification of a family of four active genes (Ehodp1, Ehodp2, Ehodp3, and Ehodp4) encoding putative DNA polymerases in Entamoeba histolytica, the protozoan parasite responsible of human amoebiasis. The four Ehodp genes show similarity to DNA polymerases encoded in fungi and plant mitochondrial plasmids. EhODP polypeptides conserve the 3'-5' exonuclease II and 5'-3' polymerizati...

Bacteria contain DNA polymerase I (PolI), a single polypeptide chain consisting of ∼930 residues, possessing DNA-dependent DNA polymerase, 3'-5' proofreading and 5'-3' exonuclease (also known as flap endonuclease) activities. PolI is particularly important in the processing of Okazaki fragments generated during lagging strand replication and must ultimately produce a double-stranded substrate w...

The decapping scavenger enzyme DcpS is known for its role in hydrolyzing the cap structure following mRNA degradation. Recently, we discovered a new function in miRNA degradation activation for the ortholog of DcpS in C. elegans. Here we show that human DcpS conserves its role in miRNA turnover. In human cells, DcpS is a nucleocytoplasmic shuttling protein that activates miRNA degradation indep...