Hazards related to the presence of cadmium in food - Studies on the European soil centipede, Lithobius forficatus.

The soil is an environment rich in numerous potentially toxic substances/elements when present at elevated concentrations. They can be transported through the successive levels of the trophic chain. Animals living in a contaminated environment or eating contaminated food can accumulate potentially toxic elements in their bodies. One of the potentially toxic metals is cadmium, which accumulates significantly in soils. The aim of our research was to evaluate the changes caused by cadmium supplied with the food administered to invertebrates living in uncontaminated soil. The results were compared with those obtained for animals raised in contaminated soil, where cadmium entered the body via the epidermis. As the material for studies, we chose a common European soil centipede, Lithobius forficatus. Adult specimens were divided into the following experimental groups: C - control animals, Cd12 and Cd45 - animals fed with Chironomus larvae maintained in water containing 80 mg/l CdCl2, for 12 and 45 days, respectively. The material was analyzed using qualitative and quantitative analysis (transmission electron microscopy, confocal microscopy, flow cytometry, atomic absorption spectrometry). Eventually, we can conclude that the digestive system is an effective barrier against the effects of toxic metals on the entire organism, but among the gonads, ovaries are more protected than testes, however, this protection is not sufficient. Accumulation of spherites and mitochondrial alterations are probably involved in survival mechanisms of tissues after Cd intoxication.

Ovaries and testes of Lithobius forficatus (Myriapoda, Chilopoda) react differently to the presence of cadmium in the environment.

Proper reproduction depends on properly functioning gonads (ovaries and testes). Many xenobiotics, including heavy metals, can cause changes in somatic and germ line cells, thus damaging the reproductive capacity. The aim of this study was to investigate the effect of the heavy metal cadmium on the gonads, including germ line and somatic cells. It is important to determine whether cell death processes are triggered in both types of cells in the gonads, and which gonads are more sensitive to the presence of cadmium in the environment. The research was conducted on the soil-dwelling arthropod Lithobius forficatus (Myriapoda, Chilopoda), which is common for European fauna. Animals were cultured in soil supplemented with Cd for different periods (short- and long-term treatment). Gonads were isolated and prepared for qualitative and quantitative analysis, which enabled us to describe all changes which appeared after both the short- and long-term cadmium treatment. The results of our study showed that cadmium affects the structure and ultrastructure of both gonads in soil-dwelling organisms including the activation of cell death processes. However, the male germ line cells are more sensitive to cadmium than female germ line cells. We also observed that germ line cells are protected by the somatic cells of both gonads.

Effects of short- and long-term exposure to cadmium on salivary glands and fat body of soil centipede Lithobius forficatus (Myriapoda, Chilopoda): Histology and ultrastructure.

Cadmium (Cd) is the most widely studied heavy metal in terms of food-chain accumulation and contamination because it can strongly affect all environments (e.g., soil, water, air). It can accumulate in different tissues and organs and can affect the organism at different levels of organization: from organs, tissues and cells though cell organelles and structures to activation of mechanisms of survival and cell death. In soil-dwelling organisms heavy metals gather in all tissues with accumulation properties: midgut, salivary glands, fat body. The aim of this study was to describe the effects of cadmium on the soil species Lithobius forficatus, mainly on two organs responsible for gathering different substances, the fat body and salivary glands, at the ultrastructural level. Changes caused by cadmium short- and long-term intoxication, connected with cell death (autophagy, apoptosis, necrosis), and the crosstalk between them, were analyzed. Adult specimens of L. forficatus were collected in a natural environment and divided into three experimental groups: C (the control group), Cd1 (cultured in soil with 80 mg/kg of CdCl2 for 12 days) and Cd2 (cultured in soil with 80 mg/kg of CdCl2 for 45 days). Transmission electron microscopy revealed ultrastructural alterations in both of the organs analyzed (reduction in the amount of reserve material, the appearance of vacuoles, etc.). Qualitative analysis using TUNEL assay revealed distinct crosstalk between autophagy and necrosis in the fat body adipocytes, while crosstalk between autophagy, apoptosis and necrosis in the salivary glands was detected in salivary glands of the centipedes examined here. We conclude that different organs in the body can react differently to the same stressor, as well as to the same concentration and time of exposure. Different mechanisms at the ultrastructural level activate different types of cell death and with different dynamics.

Apoptosis and autophagy in the midgut epithelium of Acheta domesticus (Insecta, Orthoptera, Gryllidae).

The midgut epithelium of Acheta domesticus (Insecta, Orthoptera, Gryllidae), which is composed of columnar digestive cells and regenerative crypts, degenerates in two manners: necrotic and apoptotic. While necrosis was described in our previous paper, programmed cell death was the aim of the present studies. The first morphological signs of programmed cell death in midgut epithelium cells are alterations in the cytoplasm connected with shrinkage of the cells. Gradual modifications in a cell's structure cause it to be discharged into the midgut lumen, where it disintegrates. Autophagy is involved in the disintegration of organelles. The transitions of apoptotic cells are described at the ultrastructural level. Immunostaining methods were used in order to indicate the early stages of apoptosis when DNA fragmentation, which results from apoptotic signaling cascades, occurs.