THE GENETICS OF ARTEMIA SALINA. VI. SUMMARY OF MUTATIONS

¹ Academy of Sciences, Golden Gate Park, San Francisco 94138 and Department of Biology, San Francisco State College, San Francisco, California 94132

1. Seven mutant genes of the brine shrimp have been studied. The mutation s, stump, shortens the abdomen; in extreme cases, all six abdominal segments are missing. An autosomal sex-limited mutation, Cu, curved, determines that females will have small curved antennae similar to those of the male. Two mutations (w, white and r, red) affect color of the eye and two mutations alter eye structure (cy, cyclops and c, crinkle). The garnet mutation, g, affects both color and structure of the eye.

2. Five of the mutant genes are autosomal, one (white) is partially sex-linked, and the mode of inheritance of one (cyclops) is not completely known.

3. Injections of India ink were used to demonstrate the distribution of phagocytic cells. These cells also take up pigment released by degenerating retinular cells in garnet-eyed shrimps.

4. The 11 sex mosaics are consistent with the hypothesis that each cell is male or female rather than intersexual in character.

5. Four shrimps had eyes which were mosaic for red and white or for black and white retinular cells. This suggests that eye pigment is determined autonomously; that is, there is no diffusable factor produced by red or wild-type retinular cells which is lacking in white cells.

6. The gene for white eyes, when homozygous, is epistatic to the genes for garnet and for red eyes. Three possible modes of action of the gene w are discussed.