VITAL STAINING OF DNA AND RNA IN PARAMECIUMDescriptionDNA and RNA are 2 types of nucleic acids that have different staining properties. DNA is acidic and stains acidic dyes, while RNA, along with proteins, stains basic dyes. The 2 stains used are methyl green and pyronine. DNA stains blue or bluish-green with methyl green, and RNA stains pink with pyronine dyes.

DNA is present in the nucleus and stains blue or bluish-green, while RNA is present in the cytoplasm and stains pink.

MaterialsCultured parameciaCavity slidesPlain slidesCover slipsMethyl green and pyronine stains 0.5%Procedure1. Pipette out a few paramecia onto a cavity slide.2. Blot out excess water using filter paper.3. Put 2 or 3 drops of methyl green pyronine stain and keep it for 5 to 10 minutes.4. Transfer the paramecia onto a clean slide. Put them under a cover slip in an aqueous medium and observe under the microscope.ObservationDNA (nucleus) stain blue and RNA (cytoplasm) stain pink.

Life cycle of Drosophila melanogasterDrosophila melanogaster is a common fruit fly used as a test system and has contributed to the establishment of the basic principles of heredity. It is also called the Cinderella of Genetics. Drosophila melanogaster is a dipterous, holometabolous insect. It has a characteristic larval stage preceded by the egg and succeeded by the pupalstage.

EggEgg is about 0.5 mm in length, ovoid in shape, and white. Extending from the anterior dorsal surface, there is a pair of egg filaments. The terminal portion of these filaments are flattened into spoonlike floats. This floats keep the egg from sinking into the semi-liquid medium.LarvaThe larva hatches out from the egg. It is white, segmented, and wormlike. The head is narrow and has black mouth parts (jaw hooks). The larva undergoes 2 moults, so that the larval phase consists of 3 instars. After this stage, the larva crawls out of the medium and finally attaches to the inner drier surface of the bottle. This culminates in pupation.PupaSoon after the formation of the pupal horn from the anterior spiracle, the larval body is shortened and the skin becomes hardened and pigmented. The pupa is considered a reorganization stage. During this process, most of the adult structures are developed from the imaginal disc. A fully transformed adult fly emerges out through the anterior end of the pupal case. At the times of eclosion, the fly is greatly elongated and light in color, with wings yet to be unfolded. Immediately after this, the wings unfold and the body gradually turns dark and brown. After 6 hours of emergence, the adult fly attains the ability to participate in reproduction.AdultThe body is divided into head, thorax, and abdomen. The head has a pair of compound eyes and a pair of antennae. The thorax is divided into 3 segments prothorax, mesothorax, and metathorax, each with a pair of legs. The mesothorax has a pair of wings and the metathorax has a pair of halters. The abdomen is segmented in 4 or 5 sections in males and 6 or 7 in females. The abdominal tip in males is darkly pigmented.