Monozoic caryophyllidean cestodes, intestinal parasites of cyprinid fishes, represent a group of tapeworms with an unclear evolutionary history. As spermatology may provide phylogenetically important data, the spermiogenesis and ultrastructure of the mature spermatozoon have been investigated using an integrative approach combining transmission electron microscopy, cytochemistry and electron tomography in Khawia rossittensis (Szidat, 1937). The process of spermatid formation is accompanied by the presence of ultrastructural characters not described in traditional models of spermiogenesis, e.g., apical electron-dense material, the two striated roots situated unusually opposite each other, branching of typical striated roots, an intercentriolar body comprising five electron-dense and four electron-lucent layers, rotation of both free flagella and flagellar buds to the median cytoplasmic process at 90°, and a complete proximodistal fusion. The synchronous rotation of both flagellar buds and growing free flagella is an evolutionarily linked pattern favouring the hypothesis that the Caryophyllidea are not ancestral but are secondarily derived from polyzoic forms. Electron tomography analysis has revealed a unique feature of two helicoidal tubular structures in the central electron-dense core of the axoneme of mature spermatozoon. These data provide new insights into the architecture of the 9 + '1' axoneme, which is shared by male gametes of all trepaxonematan Platyhelminthes.
Spermatozoon formation in Caryophyllaeides fennica (Schneider, 1902) is characterised by the following: (1) apical electron-dense material in the zone of differentiation, (2) typical striated roots situated unconventionally in opposite directions in early stages of spermiogenesis, (3) intercentriolar body composed of three electron-dense and two electron-lucent plates, (4) free flagellum and a flagellar bud that correspond to a greatly reduced flagellum and (5) rotation of free flagellum and a flagellar bud to the median cytoplasmic process at 90°. The development of two flagella of significantly unequal length clearly supports a derived form of spermiogenesis in the Caryophyllidea. New for cestodes is a finding of two additional striated roots situated opposite each other, in conjunction with both the flagellar bud and free flagellum. Mutual position of additional striated roots and typical striated roots is parallel in early stages and perpendicular in advanced stages of spermiogenesis. A complete proximodistal fusion gives rise to a mature spermatozoon consisting of one axoneme, parallel cortical microtubules, a nucleus and a moderately electron-dense cytoplasm with glycogen particles, detected by a technique of Thiéry (J Microsc 6:987-1018, 1967), in the principal regions (II, III, IV). Electron tomography analysis of the free flagellum and one axoneme of a mature spermatozoon of C. fennica provides clear evidence, for the first time, that two tubular structures are present in the central axonemal electron-dense core. Phylogenetically important aspects of spermiogenesis of the Caryophyllidea with one axoneme, and other cestodes with one or two axonemes, are briefly reviewed and discussed.
- MeSH
- axonema ultrastruktura MeSH
- buněčné jádro ultrastruktura MeSH
- Cestoda ultrastruktura MeSH
- cestodózy MeSH
- flagella ultrastruktura MeSH
- mikrotubuly ultrastruktura MeSH
- spermatogeneze fyziologie MeSH
- spermie ultrastruktura MeSH
- tomografie elektronová MeSH
- transmisní elektronová mikroskopie MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Oxidative stress is the imbalance between the oxygen radicals and antioxidant defence system of the organism and leads to cell damage. Antioxidant enzymes are an important part of the defense against oxidative stress and the crucial ones are superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase. Superoxide dismutase catalyses the conversion of superoxide to hydrogen peroxide, which can be further degraded by catalase to oxygen and water. Peroxidases are enzymes catalysing the reduction of the number of peroxides to alcohols. Glutathion peroxidases are selenium dependent enzymes using reduced glutathione (GSH) as a cofactor. They catalyze the conversion of hydrogen peroxide to water while the reduced glutathione is oxidized. The GSH is then being renewed by the activity of glutathione reductase, another antioxidative enzyme that reduces oxidized glutathione (GSSG) to GSH.
- MeSH
- antioxidancia * fyziologie chemie metabolismus MeSH
- glutathionperoxidasa analýza chemie metabolismus MeSH
- glutathionreduktasa analýza chemie metabolismus MeSH
- katalasa analýza chemie metabolismus MeSH
- oxidační stres * MeSH
- superoxiddismutasa analýza chemie metabolismus MeSH
- Publikační typ
- práce podpořená grantem MeSH
