Apoptosis and necrosis during the circadian cycle in the centipede midgut.
Three types of cells have been distinguished in the midgut epithelium of two centipedes, Lithobius forficatus and Scolopendra cingulata: digestive, secretory, and regenerative cells. According to the results of our previous studies, we decided to analyze the relationship between apoptosis and necrosis in their midgut epithelium and circadian rhythms. Ultrastructural analysis showed that these processes proceed in a continuous manner that is independent of the circadian rhythm in L. forficatus, while in S. cingulata necrosis is activated at midnight. Additionally, the description of apoptosis and necrosis showed no differences between males and females of both species analyzed. At the beginning of apoptosis, the cell cytoplasm becomes electron-dense, apparently in response to shrinkage of the cell. Organelles such as the mitochondria, cisterns of endoplasmic reticulum transform and degenerate. Nuclei gradually assume lobular shapes before the apoptotic cell is discharged into the midgut lumen. During necrosis, however, the cytoplasm of the cell becomes electron-lucent, and the number of organelles decreases. While the digestive cells of about 10 % of L. forficatus contain rickettsia-like pathogens, the corresponding cells in S. cingulata are free of rickettsia. As a result, we can state that apoptosis in L. forficatus is presumably responsible for protecting the organism against infections, while in S. cingulata apoptosis is not associated with the elimination of pathogens. Necrosis is attributed to mechanical damage, and the activation of this process coincides with proliferation of the midgut regenerative cells at midnight in S. cingulata.
Department of Animal Histology and Embryology, University of Silesia, Bankowa 9, 40-007, Katowice, Poland. magdalena.rost-roszkowska@us.edu.pl.|Silesian Medical College in Katowice, Mickiewicza 29, 40-085, Katowice, Poland. magdalena.rost-roszkowska@us.edu.pl.
M M
MM
Rost-Roszkowska
Department of Animal Histology and Embryology, University of Silesia, Bankowa 9, 40-007, Katowice, Poland.|Silesian Medical College in Katowice, Mickiewicza 29, 40-085, Katowice, Poland.
Ł
Ł
Chajec
Faculty of Science, Department of Zoology, Charles University, Vinicna 7, 128 44, Prague 2, Czech Republic.
J
J
Vilimova
Biology Centre CAS, Institute of Soil Biology, Na Sadkach 7, CZ-370 05, Ceske Budejovice, Czech Republic.
K
K
Tajovský
D000818:Animals; D017209:Apoptosis; D001181:Arthropods / Q000166:cytology* / Q000382:microbiology; D002940:Circadian Rhythm; D053938:DNA Fragmentation; D004064:Digestive System / Q000166:cytology / Q000382:microbiology; D004847:Epithelial Cells / Q000382:microbiology / Q000502:physiology / Q000648:ultrastructure; D005260:Female; D008297:Male; D009336:Necrosis
Cell death; Centipede; Digestive cells; Midgut epithelium; Ultrastructure