Author index for volume 91

We have induced teratocarcinomas in $\text{C3H}\text{He}$ strain mice by extra-uterine transplantation of egg cylinder stage embryos. Embryonal carcinoma cell lines with male karyotypes were isolated from three different tumor lines. One of the cell lines has a normal karyotype. The Y chromosome in each of two lines tested replicates late during the S phase of the cell cycle at the same time as Y chromosomes in male somatic cells.     

Author index for volume 219

Proteinase inhibitors I and II were purified to electrophoretic homogeneity from leaves of tomato plants induced by either wounding intact plants or by supplying excised plants with the proteinase inhibitor inducing factor. Affinity chromatography with chymotrypsin-Sepharose was employed as a final purification step for each inhibitor. The tomato leaf inhibitors are very similar to potato tuber inhibitors I and II in subunit molecular weight, composition, and inhibitory activities against chymotrypsin, trypsin, and subtilisin. However, unlike the potato tuber which contains multiple isoinhibitors by isoelectric focusing, the tomato leaf exhibits only two isoinhibitor forms of inhibitor I and a single form of inhibitor II. The molecular weight of native potato inhibitor I was reevaluated by rigorous ultracentrifugal analysis and compared with data from previous analyses. The data confirm that native inhibitor I has a native M_r of about 41,000 and is a pentamer. Inhibitor II has a molecular weight of near 23,000 and is a dimer.