Impact of Heavy Metal Exposure on Mytilus galloprovincialis Spermatozoa: A Metabolomic Investigation

Metabolomics Reveal Key Metabolic Pathway Responses to Anxiety State Regulated by Serotonin in Portunus trituberculatus

BACKGROUND

Anxiety refers to the pathological persistence and intensification of emotional responses to danger, affecting health from psychological and physical aspects. Serotonin is an important neurotransmitter involved in the onset of anxiety.

METHODS AND RESULTS

To explore the biological changes in the formation of anxiety in crustaceans under the regulation of serotonin, we applied the open field-like test method for assessing anxiety states of larval Portunus trituberculatus, a highly aggressive crustacean species with a more simple neural structure compared with rodents and mammals. Compared with the control group, serotonin treatment resulted in a significant decrease in the time spent by the larvae in the central zone, suggesting anxiety-like behavior. Clonazepam treatment reversed this result and provided further evidence that the behavior of larval P. trituberculatus displayed anxiety. Moreover, a non-targeted metabolomic analysis found a significant alteration in the metabolites involved in tryptophan metabolism pathways associated with anxiety, including L-kynurenine, N-acetyl serotonin, and serotonin. These metabolites are involved in the serotonin pathway, the kynurenine pathway, and other pathways that affect anxiety through tryptophan metabolism. There were no significant differences in tryptophan metabolism levels between the control and clonazepam treatment groups.

CONCLUSIONS

Our results demonstrate the possible existence of anxiety-like behavior in the larvae of P. trituberculatus from two perspectives. Being a species with a simpler neural structure than that of mammals, the larvae of P. trituberculatus offer a convenient model for studying the mechanisms of anxiety in crustaceans.

Molecular and toxicological mechanisms behind the effects of chromium (VI) on the male reproductive system of Mytilus galloprovincialis: First evidence for poly-ADP-ribosylation of protamine-like II

Studies on the molecular mechanisms of heavy metal toxicity in invertebrate reproduction are limited. Given that PARP-catalysed ADP-ribosylation is also involved in counteracting heavy metal toxicity and maintaining genomic integrity, and that PARylation is implicated in chromatin remodelling but its role in sperm chromatin remains to be elucidated, we investigated the effects of chromium(VI) at 1, 10 and 100 nM on the reproductive health of Mytilus galloprovincialis. The damage to the gonads was assessed by morphological analyses and the damage indices PARP and ɣH2A.X were measured. Changes in the binding of protamine-like (PL) to DNA and the possibility of poly(ADP-ribosyl)ation of PL proteins were also investigated. Gonadal chromium accumulation and morphological damage were found, especially when the mussels were exposed to the highest dose of chromium(VI). In addition, the maximum expression of gonadal ɣH2A.X and PARP were obtained at 100 and 10 nM Cr(VI), respectively. Interestingly, for the first time in all exposed conditions, poly(ADP)-ribosylation was detected on PL-II, which, together with PL-III and PL-IV, are the major nuclear basic proteins of Mytilus galloprovincialis sperm chromatin. Since PL-II is involved in the final high level of sperm chromatin compaction, this post-translational modification altered the binding of the PL protein to DNA, favouring the action of micrococcal nuclease on sperm chromatin. This study provides new insights into the effects of chromium(VI) on Mytilus galloprovincialis reproductive system and proposes a molecular mechanism hypothesis describing the toxic effects of this metal on PL-DNA binding, sperm chromatin and gonads.

The Protective Role of L-Cysteine in the Regulation of Blood-Testis Barrier Functions-A Brief Review

Blood-testis barrier (BTB) genes are crucial for the cellular mechanisms of spermatogenesis as they protect against detrimental cytotoxic agents, chemicals, and pathogens, thereby maintaining a sterile environment necessary for sperm development. BTB proteins predominantly consist of extensive tight and gap junctions formed between Sertoli cells. These junctions form a crucial immunological barrier restricting the intercellular movement of substances and molecules within the adluminal compartment. Epithelial tight junctions are complex membrane structures composed of various integral membrane proteins, including claudins, zonula occludens-1, and occludin. Inter-testicular cell junction proteins undergo a constant process of degradation and renewal. In addition, the downregulation of genes crucial to the development and preservation of cell junctions could disrupt the functionality of the BTB, potentially leading to male infertility. Oxidative stress and inflammation may contribute to disrupted spermatogenesis, resulting in male infertility. L-cysteine is a precursor to glutathione, a crucial antioxidant that helps mitigate damage and inflammation resulting from oxidative stress. Preclinical research indicates that L-cysteine may offer protective benefits against testicular injury and promote the expression of BTB genes. This review emphasizes various BTB genes essential for preserving its structural integrity and facilitating spermatogenesis and male fertility. Furthermore, it consolidates various research findings suggesting that L-cysteine may promote the expression of BTB-associated genes, thereby aiding in the maintenance of testicular functions.

The Multifaceted Impact of Environmental Pollutants on Health and Ecosystems

Environmental pollutants have pervasive and far-reaching effects on both ecosystems and human health [...].

Multiomics Reveals the Microbiota and Metabolites Associated with Sperm Quality in Rongchang Boars

In this study, we investigated the correlation between the composition and function of the gut microbiota and the semen quality of Rongchang boars. Significant differences in gut microbial composition between boars with high (group H) and low (group L) semen utilization rates were identified through 16S rRNA gene sequencing, with 18 differential microbes observed at the genus level. Boars with lower semen utilization rates exhibited a higher relative abundance of Treponema, suggesting its potential role in reducing semen quality. Conversely, boars with higher semen utilization rates showed increased relative abundances of Terrisporobacter, Turicibacter, Stenotrophomonas, Clostridium sensu stricto 3, and Bifidobacterium, with Stenotrophomonas and Clostridium sensu stricto 3 showing a significant positive correlation with semen utilization rates. The metabolomic analyses revealed higher levels of gluconolactone, D-ribose, and 4-pyridoxic acid in the H group, with 4 pyridoxic acid and D-ribose showing a significant positive correlation with Terrisporobacter and Clostridium sensu stricto 3, respectively. In contrast, the L group showed elevated levels of D-erythrose-4-phosphate, which correlated negatively with Bifidobacterium and Clostridium sensu stricto 3. These differential metabolites were enriched in the pentose phosphate pathway, vitamin B6 metabolism, and antifolate resistance, potentially influencing semen quality. These findings provide new insights into the complex interplay between the gut microbiota and boar reproductive health and may offer important information for the discovery of disease biomarkers and reproductive health management.

Potential Causal Association between Plasma Metabolites, Immunophenotypes, and Female Reproductive Disorders: A Two-Sample Mendelian Randomization Analysis

BACKGROUND

While extensive research highlighted the involvement of metabolism and immune cells in female reproductive diseases, causality remains unestablished.

METHODS

Instrumental variables for 486 circulating metabolites (N = 7824) and 731 immunophenotypes (N = 3757) were derived from a genome-wide association study (GWAS) meta-analysis. FinnGen contributed data on 14 female reproductive disorders. A bidirectional two-sample Mendelian randomization study was performed to determine the relationships between exposures and outcomes. The robustness of results, potential heterogeneity, and horizontal pleiotropy were examined through sensitivity analysis.

RESULTS

High levels of mannose were found to be causally associated with increased risks of gestational diabetes (GDM) (OR [95% CI], 6.02 [2.85-12.73], p = 2.55 × 10-6). A genetically predicted elevation in the relative count of circulating CD28-CD25++CD8+ T cells was causally related to increased female infertility risk (OR [95% CI], 1.26 [1.14-1.40], p = 1.07 × 10-5), whereas a high absolute count of NKT cells reduced the risk of ectopic pregnancy (OR [95% CI], 0.87 [0.82-0.93], p = 5.94 × 10-6). These results remained consistent in sensitivity analyses.

CONCLUSIONS

Our study supports mannose as a promising GDM biomarker and intervention target by integrating metabolomics and genomics.

The effect of geraniol on nickel-induced embryotoxicity and cardiotoxicity in rats

BACKGROUND

Nickel (Ni), commonly-used heavy metals in industrial activities, can lead to embryo and organ toxicity, especially cardiovascular damage. Geraniol (GER) has various beneficial effects such as anti-oxidant, anti-inflammatory, anti-tumor, anti-ulcer, anti-microbial, and neuroprotective activities.

OBJECTIVE

The objective of this study was to investigate the effect of GER on Ni-induced embryotoxicity and cardiotoxicity in rats.

METHODS

40 mother Wistar rats were randomly divided into five groups: Control, GER 250, Ni, Ni + GER 100, and Ni + GER 250. On the 20th day of pregnancy, the animals were sacrificed and fetuses along with blood and tissue samples were collocated for morphological, serological, biochemical, and histopathologic analysis.

RESULTS

Morphological assessments revealed GER's capacity to mitigate the incomplete ossification of fetal skeletons, indicating a potential safeguarding against the impact of Ni-induced embryotoxicity. Serological and biochemical analyses further affirm GER's role, with noteworthy reductions in cardiac injury markers, such as CRP, CKMB, CPK, LDH, and troponin, in response to GER administration, thereby suggesting its cardioprotective potential. Moreover, treatment with GER 250 could significantly reduce the level of MDA and increase the level of TAC compared to the Ni group. Histopathological examinations corroborated these findings, underscoring GER's ability to counteract cardiac injury and diminish structural damage in affected tissue.

CONCLUSIONS

These multidimensional analyses indicate the protective prowess of GER against Ni-induced embryotoxic and cardiotoxic effects, shedding light on its potential therapeutic significance in combating adverse impacts stemming from Ni exposure.

A Metabolomic Analysis to Assess the Responses of the Male Gonads of Mytilus galloprovincialis after Heavy Metal Exposure

In recent years, metabolomics has become a valuable new resource in environmental monitoring programs based on the use of bio-indicators such as Mytilus galloprovincialis. The reproductive system is extremely susceptible to the effects of environmental pollutants, and in a previous paper, we showed metabolomic alterations in mussel spermatozoa exposed to metal chlorides of copper, nickel, and cadmium, and the mixture with these metals. In order to obtain a better overview, in the present work, we evaluated the metabolic changes in the male gonad under the same experimental conditions used in the previous work, using a metabolomic approach based on GC-MS analysis. A total of 248 endogenous metabolites were identified in the male gonads of mussels. Statistical analyses of the data, including partial least squares discriminant analysis, enabled the identification of key metabolites through the use of variable importance in projection scores. Furthermore, a metabolite enrichment analysis revealed complex and significant interactions within different metabolic pathways and between different metabolites. Particularly significant were the results on pyruvate metabolism, glycolysis, and gluconeogenesis, and glyoxylate and dicarboxylate metabolism, which highlighted the complex and interconnected nature of these biochemical processes in mussel gonads. Overall, these results add new information to the understanding of how certain pollutants may affect specific physiological functions of mussel gonads.