Aristolochic acid I (AAI), the predominant compound in Aristolochiaceae plants and Asarum species, is a widespread environmental contaminant capable of accumulating in soil, contaminating water and crops, ultimately entering the human body. Its nephrotoxic, carcinogenic, and reproductive toxic effects pose significant health concerns. This study investigates the impact of maternal AAI exposure on meiotic prophase I (MPI) during early fetal oogenesis. Pregnant mice were orally administered AAI at doses of 0.03125, 0.125, and 1 mg/kg from 14.5 to 16.5 dpc, with fetal ovaries collected at 17.5 dpc. AAI exposure induced meiotic defects in fetal oocytes, including delayed progression of MPI, increased DNA damage, and impaired homologous recombination. Furthermore, AAI induced oxidative stress, reduced mitochondrial membrane potential and triggered apoptosis, leading to a diminished ovarian reserve in neonatal ovaries. Mechanistically, these defects were mediated by heat shock proteins which altered protein-protein interactions crucial for DNA repair. Given the pivotal role of early oogenesis in determining female fertility and ensuring the health of offspring, these findings underscore the potential reproductive risks of AAI exposure during pregnancy. This study highlights the urgent need for greater awareness of foodborne contaminants and the implementation of preventative measures to mitigate maternal AAI exposure, thereby safeguarding offspring fertility and health.

The mechanism of perchlorate resistance of the desert cyanobacterium Chroococcidiopsis sp. CCMEE 029 was investigated by assessing whether the pathways associated with its desiccation tolerance might play a role against the destabilizing effects of this chaotropic agent. During 3 weeks of growth in the presence of 2.4 mM perchlorate, an upregulation of trehalose and sucrose biosynthetic pathways was detected. This suggested that in response to the water stress triggered by perchlorate salts, these two compatible solutes play a role in the stabilization of macromolecules and membranes as they do in response to dehydration. During the perchlorate exposure, the production of oxidizing species was observed by using an oxidant-sensing fluorochrome and determining the expression of the antioxidant defense genes, namely superoxide dismutases and catalases, while the presence of oxidative DNA damage was highlighted by the over-expression of genes of the base excision repair. The involvement of desiccation-tolerance mechanisms in the perchlorate resistance of this desert cyanobacterium is interesting since, so far, chaotropic-tolerant bacteria have been identified among halophiles. Hence, it is anticipated that desert microorganisms might possess an unrevealed capability of adapting to perchlorate concentrations exceeding those naturally occurring in dry environments. Furthermore, in the endeavor of supporting future human outposts on Mars, the identified mechanisms might contribute to enhance the perchlorate resistance of microorganisms relevant for biologically driven utilization of the perchlorate-rich soil of the red planet.

Mount Everest provides natural advantages to finding radiation-resistant extremophiles that are functionally mechanistic and possess commercial significance. (1) Background: Two bacterial strains, designated S5-59T and S8-45T, were isolated from moraine samples collected from the north slope of Mount Everest at altitudes of 5700m and 5100m above sea level. (2) Methods: The present study investigated the polyphasic features and genomic characteristics of S5-59(T) and S8-45(T). (3) Results: The major fatty acids and the predominant respiratory menaquinone of S5-59(T) and S8-45(T) were summed as feature 3 (comprising C16:1 omega 6c and/or C16:1 omega 7c) and ubiquinone-10 (Q-10). Phylogenetic analyses based on 16S rRNA sequences and average nucleotide identity values among these two strains and their reference type strains were below the species demarcation thresholds of 98.65% and 95%. Strains S5-59(T) and S8-45(T) harbored great radiation resistance. The genomic analyses showed that DNA damage repair genes, such as mutL, mutS, radA, radC, recF, recN, etc., were present in the S5-59(T) and S8-45(T) strains. Additionally, strain S5-59(T) possessed more genes related to DNA protection proteins. The pan-genome analysis and horizontal gene transfers revealed that strains of Sphingomonas had a consistently homologous genetic evolutionary radiation resistance. Moreover, enzymatic antioxidative proteins also served critical roles in converting ROS into harmless molecules that resulted in resistance to radiation. Further, pigments and carotenoids such as zeaxanthin and alkylresorcinols of the non-enzymatic antioxidative system were also predicted to protect them from radiation. (4) Conclusions: Type strains S5-59(T) (=JCM 35564T =GDMCC 1.3193T) and S8-45(T) (=JCM 34749T =GDMCC 1.2715T) represent two novel species of the genus Sphingomonas with the proposed name Sphingomonas qomolangmaensis sp. nov. and Sphingomonas glaciei sp. nov. The type strains, S5-59(T) and S8-45(T), were assessed in a deeply genomic study of their radiation-resistant mechanisms and this thus resulted in a further understanding of their greater potential application for the development of anti-radiation protective drugs.