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Titolo:
UNORTHODOX MALE MEIOSIS IN TRICHOSIA-PUBESCENS (SCIARIDAE) - CHROMOSOME ELIMINATION INVOLVES POLAR ORGANELLE DEGENERATION AND MONOCENTRIC SPINDLES IN FIRST AND 2ND DIVISION
Autore:
FUGE H;
Indirizzi:
UNIV KAISERSLAUTERN,DEPT BIOL,POB 3049 D-67653 KAISERSLAUTERN GERMANY
Titolo Testata:
Journal of Cell Science
, volume: 107, anno: 1994,
parte:, 1
pagine: 299 - 312
SICI:
0021-9533(1994)107:<299:UMMIT(>2.0.ZU;2-1
Fonte:
ISI
Lingua:
ENG
Soggetto:
MICROTUBULES; SPERMATOCYTES; COPROPHILA; CENTROSOME; BEHAVIOR;
Keywords:
GIANT CENTRIOLE; SPINDLE FORMATION; KINETOCHORE ORIENTATION; MONOPOLAR MONOCENTRIC DIVISION; BIPOLAR MONOCENTRIC DIVISION; SERIAL SECTION ELECTRON MICROSCOPY; IMMUNOFLUORESCENCE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
30
Recensione:
Indirizzi per estratti:
Citazione:
H. Fuge, "UNORTHODOX MALE MEIOSIS IN TRICHOSIA-PUBESCENS (SCIARIDAE) - CHROMOSOME ELIMINATION INVOLVES POLAR ORGANELLE DEGENERATION AND MONOCENTRIC SPINDLES IN FIRST AND 2ND DIVISION", Journal of Cell Science, 107, 1994, pp. 299-312

Abstract

Male meiosis in Trichosia pubescens (Sciaridae) was investigated by means of serial section electron microscopy and immunofluorescence light microscopy. From earlier studies of another sciarid fly, Sciara coprophila (Phillips (1967) J. Cell. Biol. 33, 73-92), it is known that the spindle poles in sciarid spermatogonia are characterized by pairs of'giant centrioles', ring-shaped organelles composed of large numbers of singlet microtubules. In the present study spermatocytes in early prophase of Trichosia were found to possess single giant centrioles at opposite sides of the nucleus. The obvious reduction in centriole number from the spermatogonial to the spermatocyte stage is suggested to be the result of a suppression of daughter centriole formation. In lateprophase, a large aster is developed around the centriole at one pole. At the opposite pole no comparable aster is formed. Instead, a number of irregular centriolar components appear in this region, a process that is understood to be a degeneration of the polar organelle. The components of the degenerate pole migrate into a cytoplasmic protrusion ('bud'), which later is also utilized for the elimination of paternal chromosomes. The existence of only one functional polar centre is the reason for the formation of a monopolar monocentric spindle in first meiotic division, which in turn is one of the prerequisites for the elimination of paternal chromosomes. While the moves towards the pole, paternal chromosomes seem to be unable to contact the pole, possibly dueto an inactivation of their kinetochores. Retrograde ('away from the pole') chromosome motion not involving kinetochores is assumed. Eventually, paternal chromosomes move into the pole-distal bud and are eliminated by casting off, together with the components of the degenerate polar organelle. Chromosome elimination can be delayed until the secondmeiotic division. The spindle of the second meiotic division is bipolar and monocentric. One spindle pole is marked by the polar centre of first division. The opposite spindle apex is devoid of a polar centre. It is assumed that spindle bipolarity in the second division is induced by the amphi-orientated chromosomes themselves. The maternal and L chromosome set (except the non-disjunctional X chromosome, which is found near the polar centre) congress in a metaphase plate, divide and segregate. Of the two daughter nuclei resulting from the second meioticdivision, the one containing the X chromatids is retained as the nucleus of the future spermatozoon. The other nucleus becomes again eliminated within a second cytoplasmic bud.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 25/11/20 alle ore 00:59:35