Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2022 Jan 6;12(1):87.
doi: 10.3390/biom12010087.

Morphological, Gene, and Hormonal Changes in Gonads and In-Creased Micrococcal Nuclease Accessibility of Sperm Chromatin Induced by Mercury

Gennaro Lettieri  1 , Nadia Carusone  1 , Rosaria Notariale  2 , Marina Prisco  1 , Alessia Ambrosino  1 , Shana Perrella  1 , Caterina Manna  2 , Marina Piscopo  1
Affiliations

Morphological, Gene, and Hormonal Changes in Gonads and In-Creased Micrococcal Nuclease Accessibility of Sperm Chromatin Induced by Mercury

Gennaro Lettieri et al. Biomolecules. .

Abstract

Mercury is one of the most dangerous environmental pollutants. In this work, we analysed the effects of exposure of Mytilus galloprovincialis to 1, 10 and 100 pM HgCl2 for 24 h on the gonadal morphology and on the expression level of three stress genes: mt10, hsp70 and πgst. In this tissue we also evaluated the level of steroidogenic enzymes 3β-HSD and 17β-HSD and the expression of PL protein genes. Finally, we determined difference in sperm chromatin accessibility to micrococcal nuclease. We found alterations in gonadal morphology especially after exposure to 10 and 100 pM HgCl2 and hypo-expression of the three stress genes, particularly for hsp70. Furthermore, decreased labelling with both 3β-HSD and 17β-HSD antibodies was observed following exposure to 1 and 10 pM HgCl2 and complete absence at 100 pM HgCl2 exposure. Gonads of mussels exposed to all HgCl2 doses showed decreased expression of PL protein genes especially for PLIII. Finally, micrococcal nuclease digestions showed that all doses of HgCl2 exposure resulted in increased sperm chromatin accessibility to this enzyme, indicative of improper sperm chromatin structure. All of these changes provide preliminary data of the potential toxicity of mercury on the reproductive health of this mussel.

Keywords: Mytilus galloprovincialis; gonad; hormones; mercury; micrococcal nuclease digestion; morphology; protamine-like proteins genes; spermatozoa.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
RT-qPCR expression analysis of M. galloprovincialis gonadal hsp70, πgst and mt10. In the figure, the change in expression, respect to the control condition (nonexposed mussels), of hsp70 (a), πgst (b) and mt10 (c) is reported under the three HgCl2 exposure conditions. Expression was determined with respect to the GAPDH housekeeping gene. Values are presented as mean ± S.D. (n = 6); asterisks indicate a statistically significant difference from unexposed mussels: * = p < 0.05.
Figure 2
Figure 2
Staining of M. galloprovincialis gonad with hematoxylin and eosin. Gonad morphology of nonexposed (a,b) and exposed mussels to 1 (c,d), 10 (e,f) and 100 pM (g,h) HgCl2, respectively. CT: connective tissue; VTCs: vesicular connective tissue cells; ADGs: adipogranular cells; * (star): degenerative vacuolized areas.
Figure 3
Figure 3
Immunolabeling of M. galloprovincialis male gonad with anti-3β-HSD antibody. Brown coloration indicates the enzyme presence. Nonexposed (a) and exposed mussels to 1 (b), 10 (c) and 100 pM (d) HgCl2, respectively. Germ cells (GC) are positive to antibody in control and 1 and 10 pM treated samples (a–c); the positivity disappears almost completely in 100 pM treated samples (d) In the connective cells (CT, connective tissue) the 3β-HSD enzyme is recognizable in control and 1 pM treated animals (a,b); in 10 and 100 pM treated samples the antibody positivity is poor (c) or totally disappeared (d).
Figure 4
Figure 4
RT-qPCR expression analysis of M. galloprovincialis gonadal PLIII and PLII/IV genes. In the figure, the change in gene expression is reported under the three HgCl2 exposure conditions compared to the control condition (nonexposed mussels: CTR). Expression was determined with respect to the GAPDH housekeeping gene. Values are presented as mean ± S.D. (n = 6).
Figure 5
Figure 5
Micrococcal nuclease (MNase) digestion time course of Mytilus galloprovincialis’ sperm chromatin. Analyses of DNA by electrophoresis on agarose gel: unexposed and exposed mussels to 1 pM HgCl2 (Panel (a)), exposed mussels to 10 and 100 pM HgCl2 (Panel (b)). n.d. = undigested sperm genomic DNA. 1Kb and 100 bp: molecular weight markers.
See this image and copyright information in PMC

References

    1. Outridge P.M., Mason R.P., Wang F., Guerrero S., Heimbürger-Boavida L.E. Updated Global and Oceanic Mercury Budgets for the United Nations Global Mercury Assessment 2018. Environ. Sci. Technol. 2018;52:11466–11477. doi: 10.1021/acs.est.8b01246. - DOI - PubMed
    1. Tortora F., Notariale R., Maresca V., Good K.V., Sorbo S., Basile A., Piscopo M., Manna C. Phenol-Rich Feijoa Sellowiana (Pineapple guava) Extracts Protect Human Red Blood Cells from Mercury-Induced Cellular Toxicity. Antioxidants. 2019;8:220. doi: 10.3390/antiox8070220. - DOI - PMC - PubMed
    1. Piscopo M., Notariale R., Tortora F., Lettieri G., Palumbo G., Manna C. Novel Insights into Mercury Effects on Hemoglobin and Membrane Proteins in Human Erythrocytes. Molecules. 2020;25:3278. doi: 10.3390/molecules25143278. - DOI - PMC - PubMed
    1. Officioso A., Alzoubi K., Lang F., Manna C. Hydroxytyrosol Inhibits Phosphatidylserine Exposure and Suicidal Death Induced by Mercury in Human Erythrocytes: Possible Involvement of the Glutathione Pathway. Food Chem. Toxicol. 2016;89:47–53. doi: 10.1016/j.fct.2016.01.003. - DOI - PubMed
    1. Fathallah S., Medhioub M.N., Medhioub A., Kraiem M.M. Toxicity of Hg, Cu and Zn on Early Developmental Stages of the European Clam (Ruditapes decussatus) with Potential Application in Marine Water Quality Assessment. Environ. Monit. Assess. 2010;171:661–669. doi: 10.1007/s10661-010-1311-0. - DOI - PubMed