Contrasting drivers of diversity in hosts and parasites across the tropical Andes.

Geographic turnover in community composition is created and maintained by eco-evolutionary forces that limit the ranges of species. One such force may be antagonistic interactions among hosts and parasites, but its general importance is unknown. Understanding the processes that underpin turnover requires distinguishing the contributions of key abiotic and biotic drivers over a range of spatial and temporal scales.

The first locked side-chain analogues of calcitriol (1alpha,25-dihydroxyvitamin D3) induce vitamin D receptor transcriptional activity.

[structure: see text]. We describe the synthesis of the first locked side-chain analogues of the natural hormone 1alpha,25-(OH)2-D3 and their effects on gene transcription in human colon cancer cells. Analogue 2 was more potent than 1alpha,25-(OH)2-D3 at inducing vitamin D receptor (VDR) transcriptional activity.