Journal Title
Title of Journal: Chromosoma
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Publisher
Springer Berlin Heidelberg
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Authors: G F Meyer O Hess W Beermann
Publish Date: 2004/08/28
Volume: 12, Issue: 1, Pages: 676-716
Abstract
Morphological manifestations of the chromosomal metabolism have been found in the first spermatocyte nucleus of Drosophila melanogaster These “metabolic structures” include several types of well defined components among which the „tubuli“ and the „reticular elements“ are most conspicuous The metabolic nature of these elements follows from their phase specifity and from cytochemical dataMasses of tubuli of 300–400 Å diameter are found all over the meiotic prophase chromosomes in the spermatocyte nucleus but not in the spermatogonial nucleus The reticular elements appear somewhat later and usually form a single group Both types of metabolic structures are decomposed during diakinesis when they separate from the chromosomesThe chromosomal origin of the tubular as well as the reticular elements follows not only from the observed contact with the chromosomes but also from the fact that spermatocyte nuclei of X/Omales of Drosophila melanogaster do not contain these components This shows that the Ychromosome is involvedThe role of the Ychromosome in the formation of the metabolic structures has been further elucidated by studying males with partial Ychromosomes such as YS YL and Y″ Spermatocytes with the long arm of the Y X/YLc as a rule contain tubular and reticular elements in nearly normal quantity X/YS and X/Y″ testes show a highly variable pattern Some spermatocyte nuclei resemble the X/Otype while the rest represent all intermediate stages between the X/O and the X/YLtypeThe lack of tubuli in X/O or in X/YS and X/YL spermatocyte nuclei is always correlated with the appearance of crystal needles in the nucleus as well as in the cytoplasm Only very rarely in X/YS spermatocytes is an intranuclear crystal found together with a small amount of tubuli The X/O crystal needles persist during spermatogenesis and are still found in sperm bundles The crystal material seems to be a protein which is different from the tubular proteinThe possibilities of the involvement of the Ychromosome in the formation of the metabolic chromosomal structures are discussed It seems probable that tubuli represent a highly modified state of the Ychromosome or parts of this chromosome The formation of protein crystals in X/Ospermatocytes indicates the presence of a biochemical block The relation to fertility ie sperm motility is unclear X/YL males do not produce motile sperms although tubuli are regularly present in spermatocyte nuclei
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