The chromosome constitution of plants derived from pollen of hexaploid triticale X common wheat F1 hybrids

Summary The anthers of three F₁ hybrids of hexaploid triticale and common wheat (Rosner X Kedong 58, Beagle X Kedong 58 and Beagle X Jinghua No. 1) were cultured on four media in vitro. More than 900 green plants were obtained. The chromosome numbers ranged from 17 to 27 for haploid derivatives and from 38 to 52 for diploid regenerates. The chromosome constitutions of the pollen plants reflect those of the gametes found in the donor plants (genome formula: AABBDR). The value of such pollen plants for genetical analysis of rye wheat addition and substitution lines, as well as for breeding purposes, is discussed.     

The effect of chromosome constitution on growth in culture of human spontaneous abortions

Summary The effect of chromosome constitution on growth in culture was evaluated by comparing the length of time in culture until cytogenetic analysis among chromosomally normal and abnormal spontaneous abortions. We observed a significant effect of both tissue type and cell type, but not chromosome constitution, on the rate of growth of the cultures.     

The chromosome constitution of 1000 human spermatozoa

Summary Chromosomal analysis of 1000 spermatozoa from 33 normal men was performed using in vitro fertilization of zonafree golden hamster eggs. The frequency of abnormal sperm complements was 8.5%: 5.2% were aneuploid and 3.3% had a structural chromosome abnormality. The frequencies of hyperhaploid (2.4%) and hypohaploid (2.7%) sperm complements were not significantly different and all chromosome groups were represented among the aneuploid complements. The majority (22/33) of structurally abnormal complements had a chromosome break. The percentages of X and Y-bearing sperm were 53.9% and 46.1%, which is significantly different from the expected one to one ratio.     

Protein constitution of the chromosome axis

Diverse studies indicate that certain nonhistone proteins may be responsible for maintaining the integrity of the eukaryotic chromosomes. In view of their dispersal during nuclear division and their acknowledged role in gene expression, none of the nuclear matrix proteins can be regarded as integral proteins of the chromosome. Topoisomerase II, structural maintenance of chromosome (SMC) proteins and high-mobility-group (HMG) proteins exhibit characteristic enzymatic and mechanochemical roles as well as transitory association with chromosomes. Hence they may be regarded as accessory chromosome proteins. In contrast, certain high molecular weight synaptonemal complex proteins (SCPs) exhibit chemical and physical properties that suggest a structural role as the chromosome axis. It is proposed in an experimentally testable model that, in the minimal structure of a eukaryotic chromosome, the terminals of the loops of DNA-histone solenoids are constitutively affixed to chromosome axis proteins that have elastic properties.     

The effect of selection upon mendelian characters manifested in one sex only

Ohne Zusammenfassung

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Heredity of the race-characters univoltinism and bivoltinism in the silkworm (Bombyx mori), a case of non-mendelian inheritance

     

Experimental alterations in the chromosome constitution of Sciara

Summary Using two reciprocal translocations between chromosomes X and IV in S. coprophila it has been possible to derive two kinds of aneuploid females. Both of the aneuploid complements are detrimental — one is lethal, the other may give rise to viable, fertile adults. Males with aneuploid somatic complements have not been obtained; three different aneuploid complements were tested but gave negative results. Males with euploid soma and aneuploid germ line have been produced in three separate instances; they are viable and fertile.Dedicated to Professor H. Bauer on the occasion of his sixtieth birthday.The studies reported here were supported by grant GB-42 from the National Science Foundation.     

Characters of DNA constitution in the rye B chromosome

We have used chromosome microdissection and microcloning to construct a DNA library of the entire B chromosome （B） of rye. New rye B-specific sequences have been screened from this pool, blasted with other sequences and analyzed to elucidate the characters of DNA constitution and the possible pathway of the origin of the rye B chromosome. We report the discovery of a new sequence that is specific to the rye B centromere.