DNA colony hybridization with three 18to 20-base-long synthetic oligonucleotide probes for cholera toxin (CT) was used to screen 12 clinical isolates of Aeromonas hydrophila. Under stringent hybridizing (overnight at 40°C) and washing (1 h at 50°C) conditions, nine strains reacted with the 32P-labeled CT probes. Concentrated (10x) céll-free supernatants or lysates from eight cultures, heated at 56°C for 20 min, produced cytotonic effects in Y-1 mouse adrenal cells and Chinese hamster ovary (CHO) cells and caused a 1.5to 22-fold increase in production of cyclic AMP in CHO cells. Preincubation with anti-CT reduced the CHO cell titer of cell lysates by 10-fold. In the GM1 ganglioside enzyme-linked immunosorbent assay, heated supernatants and lysates gave readings equivalent to 3.5 to 100 ng of CT. Three proteins with molecular weights of 89,900, 37,000, and 11,000 reacted with anti-CT on immunoblots of cell lysates from sodium dodecyl sulfate-polyacrylamide gels. These results suggest that there is DNA homology and immunological cross-reactivity between CT and the A. hydrophila cytotonic toxin.

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CHICAGOMasculinization of the female fetus by androgens given to the mother is well established. The purpose of this study is to determine whether feminization in the male infant occurs when estrogens are administered in pregnancy.Jones and Wilkins 1 have summarized recent concepts of the development of sexual structures. Experimental observations on a variety of mammals and marsupials were performed during the indifferent or bisexual phase of sexual differentiation.2 At this point the embryo has both wolffian and m\l=u"\llerianducts. The external genitalia are underdeveloped and are capable of development in either direction, male or female. If

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