title: Nucleus behavior during the closed mitosis of Tritrichomonas foetus.
abstract: We present observations on the fine structure and the division process of the nucleus in the protist Tritrichomonas foetus, parasite of the urogenital tract of cattle. The nucleus was followed by immunofluorescence and electron microscopy during interphase and mitosis. Conventional karyotyping coupled to image processing and bright field Panotic staining were used to follow nucleus modifications, chromosome number and condensation pattern along the whole cell cycle. Confocal laser scanning microscopy (CLSM) using DNA fluorescent probes, followed by image processing in the SURF-Driver program, produced three-dimensional reconstruction data of the mitotic nucleus under each phase of the division process. Immunocytochemistry in thin-sections revealed the chromosome spatial arrangement after bromodeoxyuridine incorporation and immunogold labeling using anti-DNA monoclonal antibodies. Our results indicate that: (1) the nucleus assumes different size and shapes along mitosis: it appears oval in interphase, becoming lobed or concave in prophase, then undergoing torsion and constriction, displaying an 'S' shape (metaphase). Next, it becomes elongated and it is finally separated in two nuclei at the transition of anaphase to telophase; (2) T. foetus nucleus harbors five chromosomes; (3) chromosomes become condensed in a pre-mitotic phase; (4) the nucleolus persists during the mitosis.
authors.affiliation: Programa de Pós-Graduação em Ciências Morfológicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Karla Consort
authors.initials: KC
authors.lastname: Ribeiro
authors.forename: Rafael Meyer
authors.initials: RM
authors.lastname: Mariante
authors.forename: Letícia Lopes
authors.initials: LL
authors.lastname: Coutinho
authors.forename: Marlene
authors.initials: M
authors.lastname: Benchimol
mesh_terms: D000705:Anaphase / Q000235:genetics; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000235:genetics* / Q000378:metabolism; D002466:Cell Nucleolus / Q000235:genetics / Q000648:ultrastructure; D002467:Cell Nucleus / Q000235:genetics* / Q000648:ultrastructure; D020090:Chromosome Segregation / Q000235:genetics; D002875:Chromosomes / Q000235:genetics* / Q000648:ultrastructure; D005455:Fluorescent Antibody Technique; D007399:Interphase / Q000235:genetics; D007621:Karyotyping; D008677:Metaphase / Q000235:genetics; D008854:Microscopy, Electron; D008938:Mitosis / Q000235:genetics*; D011418:Prophase / Q000235:genetics; D011528:Protozoan Infections / Q000235:genetics* / Q000378:metabolism; D016835:Tritrichomonas foetus / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure