Ultrastructural analysis of apoptosis and autophagy in the midgut epithelium of Piscicola geometra (Annelida, Hirudinida) after blood feeding

Abstract

Cell death in the endodermal region of the digestive tract of the blood-feeding leech Piscicola geometra was analyzed using light and transmission electron microscopes and the fluorescence method. Sexually mature specimens of P. geometra were bred under laboratory conditions and fed on Danio rerio. After copulation, the specimens laid cocoons. The material for our studies were non-feeding juveniles collected just after hatching, non-feeding adult specimens, and leeches that had been fed with fish blood (D. rerio) only once ad libitum. The fed leeches were prepared for our studies during feeding and after 1, 3, 7, and 14 days (not sexually mature specimens) and some weeks after feeding (the sexually mature). Autophagy in all regions of the endodermal part of the digestive system, including the esophagus, the crop, the posterior crop caecum (PCC), and the intestine was observed in the adult non-feeding and feeding specimens. In fed specimens, autophagy occurred at very high levels—in 80 to 90 % of epithelial cells in all four regions. In contrast, in adult specimens that did not feed, this process occurred at much lower levels—about 10 % (esophagus and intestine) and about 30 % (crop and PCC) of the midgut epithelial cells. Apoptosis occurred in the feeding adult specimens but only in the crop and PCC. However, it was absent in the non-feeding adult specimens and the specimens that were collected during feeding. Moreover, neither autophagy nor apoptosis were observed in the juvenile, non-feeding specimens. The appearance of autophagy and apoptosis was connected with feeding on toxic blood. We concluded that autophagy played the role of a survival factor and was involved in the protection of the epithelium against the products of blood digestion. Quantitative analysis was prepared to determine the number of autophagic and apoptotic cells.

Apoptosis and necrosis during the circadian cycle in the centipede midgut

“…Thus, apoptosis represents a mechanism that protects against infection and inflammation in the different organs and tissues of the organism. Similar results have been described in the digestive epithelium of many arthropods (Baton and Ranford-Cartwright 2007;Rost-Roszkowska et al 2008, 2015b. S. cingulata did not have any rickettsia-like microorganisms in the cytoplasm of the digestive cells.…”

“…Many stress factors that originate from the external environment can disrupt and damage cell organelles, causing the activation of the cell death pathways (Okuda et al 2007;Menze et al 2010;Maghsoudi et al 2012;Jain et al 2013;Teixeira et al 2013;Lipovšek and Novak 2015). Among all of the processes of cell death that are known, only apoptosis, necrosis, and autophagy have been clearly described in the digestive epithelium of invertebrates (Parthasarathy and Palli 2007;Park and Takeda 2008;Park et al 2009;Tettamanti et al 2011;Franzetti et al 2012;Rost-Roszkowska et al 2008, 2015bLipovšek and Novak 2015). Additionally, functions of the digestive cells (e.g., enzymes synthesis, transport of ions and nutrients, storage of the reserve material and toxic substances) can cause the accumulation of reactive oxygen species (ROS), which trigger apoptosis and necrosis.…”

“…Inflammation is activated when apoptotic cells do not release their organelles and content into the extracellular space that surrounds neighboring tissues and where they are phagocytosed by the surrounding cells, e.g., macrophages and/or parenchymal cells (Kurosaka et al 2003;Elmore 2007). In the midgut epithelium of invertebrates, cells that have phagocytic abilities do not appear and therefore, another mechanism is created-apoptotic cells or apoptotic bodies are discharged into the gut lumen where they are digested (Rost-Roszkowska et al 2008, 2015b. To date, the dependence between apoptosis and circadian rhythms has been described in vertebrates Potten 1988, 1990;Granda et al 2005;Sankar 2011a, 2011b), while no information can be found in the literature about these processes in the gut epithelium of invertebrates.…”

Towards a Proteomic Catalogue and Differential Annotation of Salivary Gland Proteins in Blood Fed Malaria Vector Anopheles culicifacies by Mass Spectrometry

“…Therefore, our observations indicate that these identified proteins in salivary glands of blood fed mosquitoes might play a role as a survival factor against unwanted microorganism or pathogen and external stress enhanced during blood feeding. The role of autophagy was also implicated in epithelium protection against the products of blood digestion in insect as mentioned earlier by Rost-Roszkowskan et al [39]. In addition, Beclin-1/autophagy-related protein 6 was also identified to be up regulated in our studies that might play a central role in autophagy as suggested by earlier studies in Drosophila by Sharavage et al [40].…”

Autophagy and its role in regeneration and remodeling within invertebrate

“…However, the degradation of hemoglobin, the most abundant protein in vertebrate blood, results in the generation of amino acids and heme, which may be toxic or even lethal [ 150 , 151 ]. For example, under laboratory breeding conditions, signs of death of cells or even organisms given blood meals were observed [ 152 , 153 ]. In order to maintain homeostasis, several mechanisms have been developed to neutralize toxic molecules in blood-feeding animals [ 154 , 155 ].…”