Millipedes represent a model for the study of organic matter transformation, animal-microbial interactions, and compartmentalisation of digestion. The activity of saccharidases (amylase, laminarinase, cellulase, xylanase, chitinase, maltase, cellobiase, and trehalase) and protease were measured in the midgut and hindgut contents and walls of the millipedes Archispirostreptus gigas and Epibolus pulchripes. Assays done at pH 4 and 7 confirmed activities of all enzymes except xylanase. Hydrolysing of starch and laminarin prevailed. The hindgut of E. pulchripes was shorter, less differentiated. Micro-apocrine secretion was observed only in the midgut of A. gigas. Merocrine secretion was present in midgut and hindgut of E. pulchripes, and in the pyloric valve and anterior hindgut of A. gigas. Alpha-polysaccharidases were mostly active in the midgut content and walls, with higher activity at pH 4. The low activity of amylase (A. gigas) and laminarinase (E. pulchripes) in midgut tissue may indicate their synthesis in salivary glands. Cellulases were found in midgut. Chitinases, found in midgut content and tissue (E. pulchripes) or concentrated in the midgut wall (A. gigas), were more active at an acidic pH. Polysaccharidases were low in hindguts. Protease shows midgut origin and alkaline activity extending to the hindgut in E. pulchripes, whereas in A. gigas it is of salivary gland origin and acid activity restricted to the midgut. Some disaccharidases, with more alkaline activity, showed less apparent midgut-hindgut differences. It may indicate an axial separating of the primary and secondary digestion along the intestinal pH gradient or the presence of enzymes of hindgut parasites.
- MeSH
- celulasa metabolismus MeSH
- chitinasy metabolismus fyziologie MeSH
- členovci klasifikace enzymologie MeSH
- gastrointestinální trakt enzymologie MeSH
- koncentrace vodíkových iontů MeSH
- polysacharidy metabolismus MeSH
- proteasy metabolismus MeSH
- substrátová specifita MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The process of autophagy has been detected in the midgut epithelium of four millipede species: Julus scandinavius, Polyxenus lagurus, Archispirostreptus gigas, and Telodeinopus aoutii. It has been examined using transmission electron microscopy (TEM), which enabled differentiation of cells in the midgut epithelium, and some histochemical methods (light microscope and fluorescence microscope). While autophagy appeared in the cytoplasm of digestive, secretory, and regenerative cells in J. scandinavius and A. gigas, in the two other species, T. aoutii and P. lagurus, it was only detected in the digestive cells. Both types of macroautophagy, the selective and nonselective processes, are described using TEM. Phagophore formation appeared as the first step of autophagy. After its blind ends fusion, the autophagosomes were formed. The autophagosomes fused with lysosomes and were transformed into autolysosomes. As the final step of autophagy, the residual bodies were detected. Autophagic structures can be removed from the midgut epithelium via, e.g., atypical exocytosis. Additionally, in P. lagurus and J. scandinavius, it was observed as the neutralization of pathogens such as Rickettsia-like microorganisms. Autophagy and apoptosis ca be analyzed using TEM, while specific histochemical methods may confirm it.
- MeSH
- apoptóza * MeSH
- autofagie * MeSH
- členovci * MeSH
- fagozomy ultrastruktura MeSH
- fluorescenční mikroskopie MeSH
- lyzozomy ultrastruktura MeSH
- mikroskopie MeSH
- Rickettsia imunologie MeSH
- střevní sliznice imunologie patologie MeSH
- transmisní elektronová mikroskopie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The midgut epithelium of two centipedes, Lithobius forficatus and Scolopendra cingulata, is composed of digestive, secretory and regenerative cells. In L. forficatus, the autophagy occurred only in the cytoplasm of the digestive cells as a sporadic process, while in S. cingulata, it occurred intensively in the digestive, secretory and regenerative cells of the midgut epithelium. In both of the species that were analyzed, this process proceeded in a continuous manner and did not depend on the day/night cycle. Ultrastructural analysis showed that the autophagosomes and autolysosomes were located mainly in the apical and perinuclear cytoplasm of the digestive cells in L. forficatus. However, in S. cingulata, the entire cytoplasm was filled with autophagosomes and autolysosomes. Initially the membranes of phagophores surround organelles during autophagosome formation. Autolysosomes result from the fusion of autophagosomes and lysosomes. Residual bodies which are the last stage of autophagy were released into the midgut lumen due to necrosis. Autophagy in the midgut epithelia that were analyzed was confirmed using acid phosphatase and mono-dansyl-cadaverine stainings.
- MeSH
- autofagie * MeSH
- cirkadiánní rytmus * MeSH
- členovci cytologie fyziologie MeSH
- cytoplazma ultrastruktura MeSH
- epitelové buňky fyziologie ultrastruktura MeSH
- fagozomy ultrastruktura MeSH
- fotoperioda * MeSH
- gastrointestinální trakt fyziologie MeSH
- lyzozomy ultrastruktura MeSH
- střevní sliznice fyziologie MeSH
- transmisní elektronová mikroskopie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The midgut epithelia of the millipedes Polyxenus lagurus, Archispirostreptus gigas and Julus scandinavius were analyzed under light and transmission electron microscopies. In order to detect the proliferation of regenerative cells, labeling with BrdU and antibodies against phosphohistone H3 were employed. A tube-shaped midgut of three millipedes examined spreads along the entire length of the middle region of the body. The epithelium is composed of digestive, secretory and regenerative cells. The digestive cells are responsible for the accumulation of metals and the reserve material as well as the synthesis of substances, which are then secreted into the midgut lumen. The secretions are of three types - merocrine, apocrine and microapocrine. The oval or pear-like shaped secretory cells do not come into contact with the midgut lumen and represent the closed type of secretory cells. They possess many electron-dense granules (J. scandinavius) or electron-dense granules and electron-lucent vesicles (A. gigas, P. lagurus), which are accompanied by cisterns of the rough endoplasmic reticulum. The regenerative cells are distributed individually among the basal regions of the digestive cells. The proliferation and differentiation of regenerative cells into the digestive cells occurred in J. scandinavius and A. gigas, while these processes were not observed in P. lagurus. As a result of the mitotic division of regenerative cells, one of the newly formed cells fulfills the role of a regenerative cell, while the second one differentiates into a digestive cell. We concluded that regenerative cells play the role of unipotent midgut stem cells.
- MeSH
- členovci fyziologie ultrastruktura MeSH
- epitel sekrece ultrastruktura MeSH
- kmenové buňky fyziologie ultrastruktura MeSH
- trávicí systém sekrece ultrastruktura MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Česká republika MeSH
