TY - JOUR

T1 - Fine structure of the microsporidian parasite (Holomycota: Microsporidia) found in the freshwater tardigrade Grevenius pushkini (Tardigrada: Isohypsibioidea)

AU - Туманов, Денис Владимирович

AU - Камышацкая, Оксана Геннадьевна

AU - Смирнов, Алексей Валерьевич

AU - Насонова, Елена Станиславовна

PY - 2024/12/4

Y1 - 2024/12/4

N2 - Proliferative stages and spores of a microsporidian parasite were identified in the freshwater tardigrade Grevenius pushkini (Tardigrada: Isohypsibioidea). Infection with microsporidia was confirmed by transmission electron microscopy (TEM). Parasites were detected in hypodermal cells, storage cells within the body cavity, muscle cells, epithelial gonadal cells, germ cells, and nurse cells within the gonad cavity. The typical stages of the microsporidian life cycle were observed, including meronts, sporonts, sporoblasts, and spores. Early proliferative stages developed in direct contact with the host cell’s cytoplasm, while sporoblasts, immature, and mature spores were enclosed within voluminous vacuoles. The mature spores were elongated and contained a single nucleus. The isofilar polar filament formed 7–9 coils, arranged in a single row. The exospore was ornamented with a thick layer of densely packed prismatic elements, displaying a honeycomb-like structure in tangential sections. The spore wall showed an interruption at the anterior pole of the spore, positioned above the polar sac-anchoring disc complex. In this area, the spores displayed a nipplelike protrusion filled with loose amorphous material and bounded with an electron-dense envelope, distinctive from any other spore wall layer. The unique morphological features of the discovered microsporidian parasite differentiate it from any known microsporidian species, warranting its classification as a new species of microsporidia, designated as Microsporidium papillum sp. nov. This study provides the first detailed morphological description of a microsporidia found in tardigrades, and represents the second documented case of tardigrade-invading microsporidia described by TEM, highlighting Tardigrada as a new group in the list of microsporidian host taxa.

AB - Proliferative stages and spores of a microsporidian parasite were identified in the freshwater tardigrade Grevenius pushkini (Tardigrada: Isohypsibioidea). Infection with microsporidia was confirmed by transmission electron microscopy (TEM). Parasites were detected in hypodermal cells, storage cells within the body cavity, muscle cells, epithelial gonadal cells, germ cells, and nurse cells within the gonad cavity. The typical stages of the microsporidian life cycle were observed, including meronts, sporonts, sporoblasts, and spores. Early proliferative stages developed in direct contact with the host cell’s cytoplasm, while sporoblasts, immature, and mature spores were enclosed within voluminous vacuoles. The mature spores were elongated and contained a single nucleus. The isofilar polar filament formed 7–9 coils, arranged in a single row. The exospore was ornamented with a thick layer of densely packed prismatic elements, displaying a honeycomb-like structure in tangential sections. The spore wall showed an interruption at the anterior pole of the spore, positioned above the polar sac-anchoring disc complex. In this area, the spores displayed a nipplelike protrusion filled with loose amorphous material and bounded with an electron-dense envelope, distinctive from any other spore wall layer. The unique morphological features of the discovered microsporidian parasite differentiate it from any known microsporidian species, warranting its classification as a new species of microsporidia, designated as Microsporidium papillum sp. nov. This study provides the first detailed morphological description of a microsporidia found in tardigrades, and represents the second documented case of tardigrade-invading microsporidia described by TEM, highlighting Tardigrada as a new group in the list of microsporidian host taxa.

UR - https://www.zin.ru/journals/protistology/num18_4/num18_4.html

U2 - 10.21685/1680-0826-2024-18-4-5

DO - 10.21685/1680-0826-2024-18-4-5

M3 - Article

VL - 18

SP - 293

EP - 301

JO - Protistology

JF - Protistology

SN - 1680-0826

IS - 4

ER -