Worm Breeder's Gazette 5(2): 28
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
The first postembryonic event in the development of the ventral cord in C. elegans is the migration of the 12 precursor (P) cells. We now have 20 independent alleles defective in P cell migrations. Seven ( e1408, e1409, n159, n320 , n331, n368 and n370) define the unc-83 V locus, and the remaining 13 define the unc-84 X locus. All 20 alleles are temperature-sensitive, even though no selection for temperature- sensitivity had been used, and all show variable expressivity. Of the 13 X-linked alleles, all but two are recessive; e1174/+ and n322/+ heterozygotes have, on average, 52 neurons in their ventral cords rather than the normal 57, but are not visibly uncoordinated. Complementation studies of the 13 alleles of the unc-84 locus, when analyzed by ventral cord counts, define four classes: Class I (e1174, e1411, n322), Class II (e1410, e1748, n296, n321, n399), Class III ( e1412, n323, n371)and Class IV ( n369, n400). Class I complements II but not I. Class II complements I but not II. Class III partially complements Class I but does not complement II or III. Class IV fails to complement any of the classes. We know that members of the Classes I and II map in the same general region, but the precise nature of the unc-84 locus remains to be determined. Cord counts were made using a DAPI (4'-6-diamidino-2-phenylindole di- hydrochloride, Polysciences, Inc.) staining protocol based upon previously developed techniques of D. Albertson, M. Chalfie and S. Ward. (We have found that DAPI quenches much less quickly than Hoechst 33258.) Worms are picked into a 3-5 lambda drop of water placed on a slide. A few drops of Carnoy's fixative (6:3:1; absolute ethanol:chloroform:glacial acetic acid) are dropped onto the worms using a Pasteur pipette and the slide is then allowed to air dry. ( The slide will keep in this state for several days.) Once dry, 3-5 lambda of stain (1 ml of water: 1-2 lambda of phenoxypropanol:1-2 lambda of 1 mg/ml DAPI) is placed on the slide and a coverslip is laid on top. Nuclei can then be observed immediately using fluorescence microscopy as for Hoechst 33258. Single animals can also be reliably stained using this protocol.