The floral organ identity gene APETALA3 (AP3) is a MADS-box transcription factor involved in stamen and petal identity that belongs to the B-class of the ABC model of flower development. Thalictrum (Ranunculaceae), an emerging model in the non-core eudicots, has AP3 homologs derived from both ancient and recent gene duplications. Prior work has shown that petals have been lost repeatedly and independently in Ranunculaceae in correlation with the loss of a specific AP3 paralog, and Thalictrum represents one of these instances.

In many species females choose a mate from among several available males; in other species, the social system provides no apparent opportunity for making a decision among alternative suitors, and decision-making capacity is assumed to be minimal. The origins, bases, and logic of female mate choices are contentious questions with important cognitive implications. Female short-finned mollies, Poecilia sphenops, have never been observed to choose mates in the wild, where instead a male-contest social system prevails. Nevertheless they readily choose between models of males in the laboratory.

Abstract Human immunodeficiency virus type 1 (HIV) infection of the central nervous system frequently causes HIV-associated neurocognitive disorders (HAND). The role of HIV Nef and other accessory proteins in HAND pathogenesis is unclear. To determine whether HIV nef undergoes adaptive selection in brain, we cloned 100 nef sequences (n?=?30 brain and n?=?70 lymphoid) from four patients with AIDS and HIV-associated dementia (HAD).