suns. The extension of the Andromeda nebula beyond the photographic limits is presumably typical of what may be found for other such objects. Comparisons with the surface brightness of the galaxy are still hampered by uncertainties in the data for our own system. There may be no part of the galaxy which, seen from outside, would be as bright as the central portion of M 31. In the latter system ...

H A P L O I D vertebrates may occur spontaneously but are very rare (Fankhauser, 1941; Humphrey & Fankhauser, 1957); however, haploids may be experimentally produced in fish (Swarup, 1959) and in mammals (Beatty, 1953), while amphibian eggs may be so treated that all developing embryos are haploid (Porter, 1939; Gurdon, 1960). The full descriptions of the development of haploid Rana pipiens (Po...

Chromosome doubling of microspore-derived plants is an important factor in the practical application of microspore culture technology because breeding programs require a large number of genetically stable, homozygous doubled haploid plants with a high level of fertility. In the present paper, 29 populations of microspore-derived plantlets from cabbage (Brassica oleracea var. capitata) and brocc...

We tested the hypothesis that the time course of the evolution of antifungal drug resistance depends on the ploidy of the fungus. The experiments were designed to measure the initial response to the selection imposed by the antifungal drug fluconazole up to and including the fixation of the first resistance mutation in populations of Saccharomyces cerevisiae. Under conditions of low drug concen...

Precise control of chromosome pairing is vital for conferring meiotic, and hence reproductive, stability in sexually reproducing polyploids. Apart from the Ph1 locus of wheat that suppresses homeologous pairing, little is known about the activity of genes that contribute to the cytological diploidization of allopolyploids. In oilseed rape (Brassica napus) haploids, the amount of chromosome pair...

Cultivated and wild potato species synthesize a wide variety of steroidal glycoalkaloids (GA) that may affect either human health or biotic stress resistance. Therefore, GA composition must be a major criterion in the evaluation of breeding products when species genomes are merged and/or manipulated. This work reports the results of GA analysis performed on unique haploid (2n=2x=24) plants obta...

Abstract This work focuses on the achievements of Polish researchers in field vegetative reproduction plants under vitro conditions. For more than 50 years, micropropagation methods have been used Poland whenever is necessary. Most perennial horticultural crops, such as fruit plants, majority ornamental geophytes, and some vegetables (e.g., rhubarb horseradish), require clonal owing to their hi...

The seedling traits is a simple and non-destructive methodology used to identify haploids/diploids in maize. This study aimed at establishing an optimal germination temperature evaluate this verify its effectiveness. Haploid diploid seeds, obtained from crosses with the haploidy inducer TAIL9, were classified using R1-Navajo marker placed germinated growth chambers maintained different temperat...