QUANTITATIVE STUDY OF DNA (FEULGEN) IN ENTAMOEBA INVADENS

1. 1. Standard technique of Feulgen reaction [25] in Entamoeba invadens gave a poor staining which could not be measured in Deeley's [6] microspectrophotometer. 2. 2. Schiff's reagent (prepared with purified pararosaniline) having a higher pH (i.e. pH 2.7-2.9) than normal (pH 1.6) rendered the nuclei of E. invadens measurable in Deeley's apparatus, set at the highest sensitivity range. 3. 3. Pretreatments of proteolytic enzymes (trypsin, pepsin, and protease) or a reducing agent, cysteine in vitro did not improve the Feulgen staining of E. invadens nuclei. 4. 4. Feulgen photometric measurements have been made on the nuclei of trophozoites and precysts of E. invadens. The cystic nuclei could not be measured because of their poor staining. Metacystic stage could not be studied because of its rarity in cultures. 5. 5. A quantitative variation of DNA content between precysts and trophozoites of E. invadens has been observed. 6. 6. In a given population of E. invadens trophozoites, no variation in DNA (Feulgen) content was detected in three arbitrary size groups. 7. 7. A rather homogeneous distribution of DNA (Feulgen) in E. invadens trophozoites has been observed with a wide spread of about 4-fold quantity of DNA, the majority of values falling within a 2-fold range. © 1969.