During mitotic prophase, chromosomes of the pathogenic unicellular eukaryote Giardia intestinalis condense in each of the cell's two nuclei. In this study, Giardia chromosomes were investigated using light microscopy, high-resolution field emission scanning electron microscopy, and in situ hybridization. For the first time, we describe the overall morphology, condensation stages, and mitotic segregation of these chromosomes. Despite the absence of several genes involved in the cohesion and condensation pathways in the Giardia genome, we observed chromatin organization similar to those found in eukaryotes, i.e., 10-nm nucleosomal fibrils, 30-nm fibrils coiled to chromomeres or in parallel arrangements, and closely aligned sister chromatids. DNA molecules of Giardia terminate with telomeric repeats that we visualized on each of the four chromatid endings of metaphase chromosomes. Giardia chromosomes lack primary and secondary constrictions, thus preventing their classification based on the position of the centromere. The anaphase poleward segregation of sister chromatids is atypical in orientation and tends to generate lagging chromatids between daughter nuclei. In the Giardia genome database, we identified two putative members of the kleisin family thought to be responsible for condensin ring establishment. Thus far, Giardia chromosomes (300 nm to 1.5 μm) are the smallest chromosomes that were analyzed at the ultrastructural level. This study complements the existing molecular and sequencing data on Giardia chromosomes with cytological and ultrastructural information.
- MeSH
- adenosintrifosfatasy analýza MeSH
- buněčné jádro ultrastruktura MeSH
- chromozomy fyziologie ultrastruktura MeSH
- DNA vazebné proteiny analýza MeSH
- Giardia lamblia genetika ultrastruktura MeSH
- mitóza MeSH
- multiproteinové komplexy analýza MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Histochemical techniques were applied to whole mounts, to study the distribution of the enzymes alkaline phosphatase, acid phosphatase, adenosine triphosphatase, 5'-nucleotidase and glucose-6-phosphatase in the organs and tissues of a viviparous monogenean, Macrogyrodactylus clarii Gussev, 1961, from the gills of the North African catfish Clarias gariepinus (Burchell) in Egypt. The following organs and tissues were studied: head region, anterior adhesive glands, mouth region, pharynx, intestine, testis, vesicula seminalis, male accessory gland, male accessory reservoir, copulatory organ, receptaculum seminis, egg-cell forming region, embryonic cells, excretory system, nerve cells, haptor, muscle fibres and subtegumental cell bodies (cytons). The enzymes showed marked differences in their activities among the studied organs and tissues. Alkaline phosphatase and acid phosphatase activities were detected in many organs and tissues, while the activities of adenosine triphosphatase, 5'-nucleotidase and glucose-6-phosphatase were restricted to a few organs. Although no positive reaction for any enzyme was observed in the anterior adhesive gland cells, a positive reaction for acid phosphatase was detected in the anterior adhesive areas. All enzymes showed marked activity in the digestive and excretory systems. The distribution of the enzymes in the tissues and organs of M. clarii is compared with those of other monogeneans, including other gyrodactylids parasitizing the same host fish. Some possible functions of the enzymes are discussed.
- MeSH
- 5'-nukleotidasa analýza metabolismus MeSH
- adenosintrifosfatasy analýza metabolismus MeSH
- alkalická fosfatasa analýza metabolismus MeSH
- cestodózy parazitologie veterinární MeSH
- glukosa-6-fosfatasa analýza metabolismus MeSH
- histocytochemie MeSH
- kyselá fosfatasa analýza metabolismus MeSH
- ploštěnci anatomie a histologie enzymologie chemie izolace a purifikace MeSH
- proteiny červů analýza metabolismus MeSH
- sumci parazitologie MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- MeSH
- adenosintrifosfatasy analýza antagonisté a inhibitory MeSH
- buněčná membrána enzymologie MeSH
- krysa rodu rattus MeSH
- myokard enzymologie ultrasonografie MeSH
- organely enzymologie MeSH
- sodíko-draslíková ATPasa MeSH
- terpeny farmakologie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- zvířata MeSH
