From Dark to Light – An Overview of Over 70 Years of Endocrine Disruption Research on Marine Mollusks

Fodor, I; Pirger, Zsolt

doi:10.3389/fendo.2022.903575

Cited by 9 publications

(5 citation statements)

References 101 publications

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“…Like ours, this study also yielded positive staining ( 50 ). As with CYP19A, the nPR gene is not present in mollusks ( 2 , 3 , 36 , 58 , 61 ), the L. stagnalis transcriptome data also confirming its absence ( Supplementary Table 2 ) ( 37 ). This again calls into question the meaningfulness of positive immunostaining with certain vertebrate antibodies for identifying or localizing specific proteins in molluscan tissues.…”

Section: Discussionmentioning

confidence: 58%

“…Such positive staining with anti-human CYP19A (i.e. aromatase) antibodies ( 8 , 10 – 12 ) has been claimed as evidence for the presence of this enzyme in these animals; despite the aromatase gene not being found in the genome of any species outside chordates ( 2 , 3 , 36 , 58 – 61 ). Our own neuronal transcriptome analysis of L. stagnalis also failed to reveal CYP19A ( Supplementary Table 2 ) ( 37 ), yet, like the other studies, we also found positive staining with an anti-human CYP19A.…”

Section: Discussionmentioning

confidence: 99%

“…Another problem concerning the putative role of vertebrates steroids in the mollusks is the fact that three crucial steps in the classical vertebrate steroid biosynthetic pathway - cholesterol side-chain cleavage, 17-hydroxylation, and aromatization – appear to be either absent or have very weak activity in mollusks ( Supplementary Figure 1 ) [reviewed by ( 2 , 3 , 34 – 36 )]. Most importantly, the protein homologues of the enzymes that catalyze the first and third of these reactions in vertebrates, CYP11A and CYP19A, respectively, as well as functional sex steroid nuclear receptors, have so far not been found in molluscan genomes ( Supplementary Figure 1 ; Supplementary Table 1 ) [reviewed by ( 2 , 3 , 34 – 36 )]. These facts are at odds, however, with the immunohistochemical evidence in the literature – which show that tissues in a range of mollusks can be stained with antibodies to human enzymes and steroid nuclear receptors.…”

Section: Introductionmentioning

confidence: 99%

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Studies on a widely-recognized snail model species (Lymnaea stagnalis) provide further evidence that vertebrate steroids do not have a hormonal role in the reproduction of mollusks

et al. 2022

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Experiments were carried out to determine whether, as with other mollusks that have been studied, the snail, Lymnaea stagnalis, can absorb, esterify and store vertebrate steroids that are present in the water. We also carried out experiments to determine whether neural tissues of the snail could be immunohistochemically stained with an antibody to human aromatase (a key enzyme that catalyzes the conversion of testosterone [T] to 17β-estradiol [E2]); and, if so, to determine the significance of such staining. Previous studies on other mollusks have reported such staining and have proposed this as decisive evidence that mollusks have the same steroid synthesis pathway as vertebrates. We found that snails absorb, esterify and retain esterified T, E2, progesterone and ethinyl-estradiol (albeit with an absorption rate about four times slower, on a weight basis, than the mussel, Mytilus edulis). We also found that not only anti-human aromatase, but also anti-human nuclear progesterone receptor (nPR) and anti-human gonadotropin-releasing hormone antibodies immunohistochemically stained snail neural cells. However, further experiments, involving gel electrophoretic separation, followed by immunostaining, of proteins extracted from the neural tissue, found at least two positively-stained bands for each antibody, none of which had masses matching the human proteins to which the antibodies had been raised. The anti-aromatase antibody even stained the 140 kDA ladder protein used as a molecular weight marker on the gels. Mass spectrometric analysis of the bands did not find any peptide sequences that corresponded to the human proteins. Our findings confirm that the presence of vertebrate-like sex steroids in molluscan tissues is not necessarily evidence of endogenous origin. The results also show that immunohistochemical studies using antibodies against human proteins are grossly non-specific and likely to have little or no value in studying steroid synthesis or activity in mollusks. Our conclusions are consistent with the fact that genes for aromatase and nPR have not been found in the genome of the snail or of any other mollusk. Our overarching conclusion, from this and our previous studies, is that the endocrinology of mollusks is not the same as that of humans or any other vertebrates and that continuing to carry out physiological and ecotoxicological studies on mollusks on the basis of this false assumption, is an unconscionable waste of resources.

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Section: Discussionmentioning

confidence: 58%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Studies on a widely-recognized snail model species (Lymnaea stagnalis) provide further evidence that vertebrate steroids do not have a hormonal role in the reproduction of mollusks

et al. 2022

Self Cite

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“…But research on GnRH signaling pathway is scarce in mollusks. Although vertebrate sex steroids have been detected in molluscan tissues and the sex steroid levels have seasonal changes during the reproductive cycle and seem to regulate reproductive events in mollusks ( Siah et al, 2002 ; Avila-Poveda et al, 2015 ), a controversy exists regarding whether mollusks can synthesize vertebrate sex steroids ( Fernandes et al, 2011 ; Nuurai et al, 2020 ; Fodor and Pirger, 2022 ). In Yesso scallop, a putative pathway for sex steroid synthesis has been proposed ( Thitiphuree et al, 2019 ), and GnRH may participate in the regulation of steroidogenesis ( Zhang et al, 2020 ).…”

Section: Discussionmentioning

confidence: 99%

Identification and characterization of gonadotropin-releasing hormone (GnRH) in Zhikong scallop Chlamys farreri during gonadal development

et al. 2023

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Gonadotropin-releasing hormone (GnRH) controls synthesis of sex steroid hormones through hypothalamic-pituitary-gonadal (HPG) axis in vertebrates. But in mollusks, research on neuroendocrine control of gonadal function, such as the function of GnRH during gonadal development is limited. In this study, we investigated the morphology and structure of the nerve ganglia of Zhikong scallop Chlamys farreri by physiological and histological observations. We also cloned the ORF and studied the expression patterns of GnRH in the scallop. Tissue expression analysis showed that GnRH was highly expressed in parietovisceral ganglion (PVG). The in situ hybridization result further confirmed that GnRH mRNA only distributed in some good-sized neurons in the posterior lobe (PL) and some pint-sized neurons in the lateral lobe (LL). In addition, by examining the expression of GnRH during gonadal development in ganglia, we found GnRH displayed higher expression in the female scallops, and showed significant high expression at the growing stage of female scallops in PVG. This study would contribute to gaining insight into the mechanism underlying reproduction regulation by GnRH in the scallop and help to provide a better understanding of reproductive neuroendocrine in mollusks.

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“…Stress-induced neuroendocrine responses play a critical role in the physiology and overall well-being of animals. While glucocorticoids are recognized as the key hormonal regulators of the physiological stress response in vertebrates (Cockrem, 2013), the underlying mechanisms that govern neuroendocrine responses to stressors in invertebrates, specifically in cephalopods, remain unclear (Fodor and Pirger, 2022).…”

Section: Introductionmentioning

confidence: 99%

The skin microbiome as a new potential biomarker in the domestication and welfare of Octopus vulgaris

Costas-Imbernon,

Costas-Prado,

Sequeiro

et al. 2024

Preprint

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Over the past decade, there has been a growing interest in common octopus aquaculture, prompted by the increasing market demand, the decline in overall fisheries and the search for a more sustainable food resource. Nevertheless, this interest has raised concerns about the potential impact of large-scale production and intensified farming practices in the future. Given the growing interest in octopus aquaculture and society's increasing concern for animal welfare, this study investigates the mucosal skin microbiota of wild and captive-bred common octopuses. The primary aim is to determine if breeding in captivity affects these communities and consequently animal welfare, using 16S ribosomal RNA metabarcoding. The core microbiota of common octopus mucosal skin is composed of the phyla Bacteroidota, Proteobacteria, Campylobacterota and Verrucomicrobiota, according to our findings. Although variations in abundance were observed, wild and aquaculture octopuses had comparable microbiota composition and diversity. Gammaproteobacteria were found to be enriched in wild mucosal skin samples, and some of the species were described as potentially pathogenic. However, these species were absent or in lower abundance in aquaculture mucosal skin samples. Additionally, analysis of KEGGs predictions showed that wild mucosal skin samples had a higher overall enrichment in functional pathways, primarily associated with xenobiotic remediation pathways, compared to the aquaculture mucosal skin samples. This is the first study to characterize the mucosal skin microbiome of the common octopus and compare the microbiome of wild and aquaculture individuals of this species. The results indicate that current aquaculture practices align with animal welfare through the use of controlled hatchery environments and high-quality water conditions. This study offers valuable insights into the microbiome of the common octopus, which can serve as a biomarker for evaluating animal welfare. It also explores the implications of these findings for the development of sustainable and responsible aquaculture practices.

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From Dark to Light – An Overview of Over 70 Years of Endocrine Disruption Research on Marine Mollusks

Cited by 9 publications

References 101 publications

Studies on a widely-recognized snail model species (Lymnaea stagnalis) provide further evidence that vertebrate steroids do not have a hormonal role in the reproduction of mollusks

Studies on a widely-recognized snail model species (Lymnaea stagnalis) provide further evidence that vertebrate steroids do not have a hormonal role in the reproduction of mollusks

Identification and characterization of gonadotropin-releasing hormone (GnRH) in Zhikong scallop Chlamys farreri during gonadal development

The skin microbiome as a new potential biomarker in the domestication and welfare of Octopus vulgaris

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