Effects of cadmium on mitochondrial structure and function in different organs: studies on the soil centipedeLithobius forficatus(Myriapoda, Chilopoda)

Abstract

Mitochondria are organelles that play a crucial role in cell physiology, cell death, and aging. They are among the first responders to different stressors that originate from the environment. Cadmium as a heavy metal affects different levels of body organization: from organs through tissues and cells to organelles. Based on our previous research results, we decided to check how the exposure to cadmium affects the functioning of mitochondria in different organs of soil living centipede Lithobius forficatus. The activity of mitochondria in somatic and germ cells has been analyzed using transmission electron microscopy (TEM), confocal microscopy, and flow cytometry. Changes in the mitochondrial membrane potential and mitochondrial dismutase (MnSOD) activity in relation to the accumulation of reactive oxygen species (ROS) caused by cadmium exposure have been studied. Individuals were divided into 3 experimental groups depending on cadmium concentration in soil. Changes in mitochondrial ultrastructure caused by cadmium are tissuedependent and associated with an increase of ROS levels. The system of ROS and MnSOD activation works more efficiently in the case of gonads than in the digestive system. While the short-term cadmium exposure alters the fine structure of both the somatic and germ-line cells in gonads, the long-term cadmium exposure causes mitochondrial ultrastructure regeneration.

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

“…Both in oocytes and L. forficatus spermatocytes, changes in ultrastructure were observed only in a few mitochondria. In contrast, significant changes in their activity were observed, as described in detail in the previous paper 32 . Much greater ultrastructural changes were observed in the mitochondria of the spermatids of the studied species after both 12 and 45 days of exposure to cadmium.…”

“…It can enter the body directly from the environment through the body wall or food 35 , 36 . In our previous studies, we analyzed the effect of short- and long-term soil cadmium exposure on midgut, salivary glands, fat body, and mitochondria activity in somatic and germ cells in the centipede Lithobius forficatus 30 – 32 . Our research results indicated that different organs in the body might react differently to the same stressor at the same concentration and duration of exposure.…”

“…Animals were divided into three groups according to our previous research 30 – 32 : C—control group, animals bred in laboratory conditions as described above; 12Cd—animals bred in a horticultural soil containing 80 mg Cd kg −1 for 12 days (short-term cadmium exposure); 45Cd—animals bred in a horticultural soil containing 80 mg Cd kg −1 for 45 days (long-term cadmium exposure) (Fig. 1 ).…”

“…Before sectioning, the animals were anesthetized, and ovaries and testes were dissected 30 , 31 . The cadmium concentration was selected based on an experiment conducted by Descamps et al 28 , Vandelbucke et al 29 , and our previous studies 30 – 32 . The number of specimens (females and males) used in the experiment is presented in Table 1 .…”

“…In our earlier papers, we described the changes under cadmium's influence in the midgut, the salivary glands, and the fat body of that species 30 , 31 . We also analyzed the effect of cadmium on mitochondria in both somatic and germ line cells 32 . As mentioned previously, it is necessary to analyze how cadmium affects the structure and ultrastructure of the gonads, including both germ line cells and somatic cells in ovaries and testes.…”