i. Early TSP's before fertilization were defined by shifting single ts emb adults to 25 C; laying and hatching kinetics were followed, a la Vanderslice & Hirsh (1976), also downshifting to determine TSP- begin. The number of fertilized eggs in the gonad vs. age was determined, as well as brood size. ii. ts emb adults from 16 C were allowed to lay eggs at various temps to obtain: * critical temp. (50% lethality) If all alleles have same crit. temp., maybe gene product is not ts, rather function is needed only above a certain temp., e.g. if another product (isozyme?) is naturally ts. Then the null phenotype will be ts, and ts alleles 25x more frequent than if missense. Instead, alleles of the highly mutable
emb-9 have different crit. temps. (ditto
emb-6). ** a maximum ts-phenotyPe, constant at all temps. above a minimum may be the null phenotype. Perdurance is less a problem than for non-ts alleles! *** neomorphs at intermediate temps. (For most embs, any Acc phenotype had a lower crit. temp.) iii. For paternal-effect tests, the male ts phenotype and TSP were defined for several embs. Also chromosome loss generated males (Him- effect) among leakies, making one emb appear hermaphrodite specific. iv. Just for fun, N2 and Freiburg (RC301) were crossed to look for growth of Fl's and segregants ar 28 C. One might expect growth if different genes limited the two strains, but no such luck, so their last common ancestor probably didn't grow at 28 C. II. DISCUSSION INVITED ON POTENTIAL & PROBLEMS OF TS MUTANTS: Are most ts embs just for housekeeping? Is polyphasy interesting? It can only be analyzed with ts mutants and pulses. How to identify interesting genes and genetically saturate? Design (localized?) screens to detect and study leakier mutants, not just tightest ones.