No abstract

No abstract

Background: Gonadal steroids, in particular 5 alpha-dihydrotestosterone (DHT) and 17 betaestradiol (E2), have been shown to feed back on the hypothalamic-pituitary-gonadal (HPG) axis of the ranid frog. However, questions still remain on how DHT and E2 impact two of the less-studied components of the ranid HPG axis, the hypothalamus and the gonad, and if the feedback effects are consistently negative. Thus, the goal of the study was to examine the effects of DHT and E2 upon the HPG axis of the gonadally-intact, sexually mature male leopard frogs, Rana pipiens.

Crystals of a 26-nucleotide pseudoknot RNA, PK26, have been grown. The RNA was produced using phosphoramidite chemistry and was purified by denaturing polyacrylamide electrophoresis. The crystallization was robust with respect to changes in the number of nucleotides and to the salt used as precipitant. The crystals belong to space group P4122 or P4322 with unit-cell dimensions a=b=61.6, c=98.9A. The best crystals diffract X-rays to 2.9,~. Three different sequences incorporating a single 5-bromo-deoxyuridine or 5-bromouridine nucleotide were also crystallized. Two of these derivatives are being used to determine the structure by multiple isomorphous replacement.