Polygyny in the Willow Warbler Phylloscopus trochilus in Swedish Lapland

The breeding sex ratio of Willow Warblers Phylloscopus trochilus in a subalpine birch forest was strongly female biased. Very few territorial males remained unmated and most became polygynous. Bigyny was the rule, but some males probably had three females. Male assistance at secondary nests varied and was probably dependent on temporal distance between the females' nests. There was no significant reduction in reproductive output for these females. Variation in the sex ratio of breeding birds can be explained, at least partly, by variation in the timing of male settlement.     

A Rationally Designed Synthetic Mimic of the Discontinuous CD4-Binding Site of HIV-1 gp120

Synthetic mimetics of the CD4-binding site of HIV-1 gp120 are promising candidates for HIV-1 entry inhibition, as well as immunogen candidates for the elicitation of virus-neutralizing antibodies. On the basis of the crystal structure of gp120 in complex with CD4, we have used a recently introduced strategy for the generation of structurally diverse scaffolds to design and synthesize a scaffolded peptide, in which three fragments, making up the sequentially discontinuous binding site of gp120 for CD4, are presented in a nonlinear and discontinuous fashion through a molecular scoffold, which restrains conformational flexibility. The affinities of this molecule to CD4, as well as to the broadly neutralizing antibody mAb b12, whose epitope overlaps the CD4-binding site of gp120, were determined in competitive binding assays.