A supposed sporulation-deficient mutation of Saccharomyces cerevisiae is found to affect mating in haploids and in diploids, and to be inseparable from the mating-type locus by recombination. The mutation is regarded as a defective a allele and is designated a*. This is confirmed by its dominance relations in diploids, triploids, and tetraploids. Tetrad analysis of tetraploids and of their spor...

Successful haploid induction in loquat (Eriobotrya japonica (Thunb.) Lindl.) through in situ-induced parthenogenesis with gamma-ray irradiated pollen has been achieved. Female flowers of cultivar 'Algerie' were pollinated using pollen of cultivars 'Changhong-3', 'Cox' and 'Saval Brasil' irradiated with two doses of gamma rays, 150 and 300 Gy. The fruits were harvested 90, 105 and 120 days after...

Antiserum inactivation experiments were carried out on electrophoretically purified diploid virions from a cross between two complementing amber mutants of phage M13. The total (homozygous plus heterozygous) diploid population, assayed on a permissive host where only one genome is needed for plaque formation, was inactivated at the same rate as haploids. Heterozygous diploids, assayed on a nonp...

This paper describes some properties of a certain fibered hyperbolic 3manifold which arises ”in nature”; that is, as the cover of a closed manifold constructed by other means. Among other things, the main theorem answers in the affirmative the question of whether it is possible for a fibered hyperbolic manifold to be a double across a connected surface. (We first heard this question from Alan R...

The concept of doubling, introduced around 1840 by Hamilton and Graves, associates with any quadratic algebra A over a field k of characterstic not 2 its double V(A) = A×A, with multiplication (w, x)(y, z) = (wy− z̄x, xȳ + zw). It yields an endofunctor on the category of all quadratic k-algebras which is faithful but not full. We study in which respect the division property of a quadratic k-alge...

Hapluids (sporophytes with lhe gametic chrom06(Jme number) f,um polysomk: p(.Jlyploid~ represem a random gameti'c sample from the parenl and can be used 10 map genes that affect quantltat,ve trai! vmiation (OTV) with the aid of moleculm' markers (isozymes or RFLPs). The objel;ljvc: of (his work was to analyze QTV using isozyme markers in four potato (tetrasomic p0lyploid) haploid populations, A...

Doubled haploid (DH) technology remarkably accelerates the crop breeding by obtaining homozygous lines in a single generation. The present study was targeted generating plants through androgenesis. Anthers from immature flower buds of six tomato genotypes viz., LE-1230, LE-1236, LE-1256 TLCV 2, PKM 1 and TNAU hybrid CO 3 were used for induction haploids. A preliminary based on callus frequency ...