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Irreversible effects of cadmium on germinal and Sertoli cells in avian species; Conceptualization of AOPs(?)

    While searching for articles to support my statement in class on the industrial pollutant cadmium, specifically in birds, I came across this review. This post is connected to Lecture 4 in regard to gonadal development, and additionally ties in the effects of heavy metals (specifically cadmium) on germinal, Sertoli, and Leydig endocrine cells, mentioned in detail in Lecture 4.


    The review provided insight and data relating to mammals and avian species, but as for this post, I will be referencing the avian related findings. Here is the article should anyone wish to investigate the effects of cadmium further.


Relating cadmium (Cd) to our Lecture 4 topic of sex determination and gonadal development

    In this review by Marettová, the aim is to provide current knowledge on cadmium's toxic effects in germinal and supporting Sertoli cells of seminiferous tubules and Leydig endocrine cells. When exposed to this heavy metal, effects in birds manifest in the germinal epithelium and testis (should the dosage not prove immediately lethal due to kidney failure). All testicular germ cell populations can be affected by Cd, capable of inducing abnormal morphology in all stages of development and apoptosis. A study referenced in the Marettová review (White et al., 1978) shown that after 90 days of consuming 200ppm Cd, testes in Mallard ducks atrophied and the entire spermatogenic process was ceased. Instances of edema, seminiferous tubule degeneration, and necrosis were observed after cadmium exposure in fowl species as well.

    Cadmium is a well known testicular toxicant, and while the mechanism is not fully understood, it is believed that Cd exerts toxic effects in the form of Cd⁺² due to its similarities to calcium and zinc. Because of their similar valence structure, Cd⁺² is likely to substitute calcium or zinc in crucial physiological processes typically mediated by these ions. This could result in disruption of several signaling pathways. In Sertoli cells, evidence of mitochondrial expansion, "aberrant ultrastructure", and DNA damage occurred. Regarding sexual determination, there is data supporting Leydig cell growth disruption in the presence of toxic cadmium. This ultimately leads to decreased/no testosterone secretion depending on viability and dose exposure. Everything mentioned is a brief summation of the negative effects and findings surrounding Cd exposure.


Thinking out loud

    Relating to my area of interest, I am curious as to how Cd contamination, also known to effect energy metabolism, proteins synthesis, and enzyme systems, will affect the stopover migration strategies in migrating shorebirds. Males typically migrate much earlier to set territories for breeding and nesting. Due to this cadmium exposure, will other trends and behaviors typically expressed in non-contaminated males be altered in exposed populations of shorebirds? Will they even be able to maintain healthy metabolite levels for the migration to the Arctic? Dunlin populations of C. alpina are known to make minimal stops at best during their migration to the Artic. Will we have the stopover locations to support populations of exposed birds, now with inhibited metabolism? Seems I am just asking more questions again.

    As with each lecture, 4 and 5 provided a way of thinking on a ideas I am currently developing. The lens of evolutionary and ecological toxicology has led to new questions and ideas surrounding genetic diversity and the overall population and system success.

Comments

  1. Liz Jurado March 29, 2021 at 10:28 AM

    Liz Jurado: I really liked the structure of your blog post, especially your thinking our loud section. I feel like mentioning the specific lecture in class where we covered some of this material was really helpful for me.

    As you highlighted, you have a lot of really great questions. Just out of curiosity, if you were going to try to answer the one about trends and behaviors expressed in non-contaminated versus contaminated males, how would you go about doing this? What trait are you most interested in?

    ReplyDelete

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