Enhancers are cis-acting elements that can promote the expression of target genes and respond to estrogen to induce the transcription of eRNAs, which are closely associated with cancer development. Further study on eRNAs may lead to a better understanding of the significance of transcriptional regulation and the progression of malignant tumors. SMAD7 enhancer RNA (SMAD7e) is an estrogen-responsive eRNA. However, the relationship between SMAD7e and bladder cancer remains unclear. SMAD7e was significantly upregulated in bladder cancer tissues and estrogen-stimulated cells. Knockdown of SMAD7e by CRISPR-Cas13a suppressed cell proliferation and migration, and induced cell apoptosis and inhibited cell invasion. Estrogen caused overexpression of SMAD7e and played a facilitating role in bladder cancer cells. Furthermore, knockdown of SMAD7e by CRISPR-Cas13a prevented the cancer-promoting effects of estrogen on bladder cancer both in vitro and in vivo. The present study suggested the crucial role of SMAD7e in bladder cancer. Estrogen might promote the development of bladder cancer by inducing SMAD7e production. These findings may provide a potential target for CRISPR-mediated gene therapy for bladder cancer in the future.

The loach (Misgurnus anguillicaudatus) is a significant freshwater economic fish in China, renowned for its tender meat, delicious taste, and high nutritional value. It is widely distributed across the country, except for the western plateau. However, the loach is currently at risk of population decline and degradation of wildlife resources. Research on genetic diversity provides a crucial foundation for the conservation and development of these fish resources. To enhance the protection and utilization of wild loach germplasm resources, we analyzed the genetic structure and diversity of 60 wild loach populations from Xiangtan City (XT), Shaoyang City (SY), and Yueyang City (XY) in Hunan, Guilin City (GL) and Guiping City (GP) in Guangxi, and Wuhan City (WH) in Hubei. Additionally, we mapped the DNA fingerprints of these 60 wild loaches using 12 high-quality SNP sites. Whole genome resequencing (WGRS) was conducted on 60 loaches from six regions, yielding a total of 1047.17 Gb of raw data and 1046.98 Gb of clean data. From this 2,812,906 high-quality single nucleotide polymorphisms (SNPs) were identified, of which 10,022 core SNPs were selected to analyze the population genetic structure, and 12 core SNPs were used to assess the genetic diversity and DNA fingerprint. The analysis revealed that the 60 loach samples could be grouped into three clusters: Cluster A comprised the XT, SY, and XY groups; Cluster B included the WH group; and Cluster C consisted of the GL and GP groups. The mean nucleic acid diversity (Pi), heterozygosity (Ho), and expected heterozygosity (He) of SNP markers were 0.130, 0.140, and 0.123, respectively. The average inbreeding coefficient was 0.552, indicating high levels of inbreeding. Whole genome resequencing is an effective high-throughput approach for identifying SNP information in loach germplasm and describing genetic relationships within this genus. DNA fingerprinting based on SNP marker technology can accurately assess the genetic structure and variation within natural loach populations, making it a valuable tool for strain and variation identification. Our findings provide a scientific basis for the conservation, development, and optimal breeding of native loach germplasm resources and contribute to expanding the genetic diversity database of wild loach populations.

Background: Distant hybridization is an important breeding technique for creating new strains with superior traits by integrating two different genomes. Successful hybridization of Megalobrama amblycephala (Blunt snout bream, BSB, 2n = 48) and Culter alburnus (Topmouth culter, TC, 2n = 48) was achieved to establish hybrid lineages (BT and TB), which provide valuable materials for exploring the mechanisms of distant hybridization fertility. In this study, the gonadal tissue transcriptomes of BSB, TC, BT-F₁, and TB-F₁ were sequenced using Illumina high-throughput sequencing technology to analyze the reproductive characteristics of BT and TB. Results: Differential gene expression analysis showed that the differentially expressed genes in BT vs BSB and BT vs TC were mainly enriched in signaling pathways not directly associated with meiosis. While, the differentially expressed genes of TB vs BSB and TB vs TC were mainly enriched in pathways related to meiosis, and most of them were down-regulated, indicating that meiosis is suppressed in TB. Under-dominance (UD) genes were enriched in pathways related to meiosis and DNA repair in TB. Over-dominance (OD) genes were enriched in MAPK signaling pathway, expression level dominance-BSB (ELD-B) genes were enriched in pathways related to steroid hormone synthesis and expression level dominance-TC (ELD-T) genes were not significantly enriched in any pathway in both BT and TB. Conclusions: These results suggest that meiotic progression may not be affected in BT, whereas it is clearly inhibited in TB. Offspring of M. amblycephala maternal parent may have better genomic compatibility and fertility. Our study provides important information on the molecular mechanisms of breaking reproductive isolation in distantly hybridized fertile lineages.

Heat stress is a major environmental stressor that affects fish metabolism, growth, and death rates. This research examined the impact of dietary rutin addition (0, 100, 300, or 500 mg/kg) for 60 days on juvenile hybrid fish (Carassius auratus cuvieri, WCC, ♀ × Carassius auratus red var, RCC, ♂, WR) (27.97 ± 0.56 g) under heat stress conditions (32 ± 1 °C for 48 h). The analysis focused on blood parameters, oxidative stress biomarkers, and hepatic hsp70 and hsp90 gene expression in WR. The results demonstrated that rutin supplementation elevated blood glucose levels and the liver activities of glutathione reductase, glutathione peroxidase, catalase, and total superoxide dismutase in comparison to the control group. Additionally, rutin supplementation also significantly reduced serum cortisol and hepatic malondialdehyde levels while upregulating hepatic hsp70 and hsp90 gene expression. These findings suggest that rutin supplementation enhances antioxidant responses and alleviates the impact of heat stress on fish physiological and biochemical markers and heat shock protein gene expression.

The ecological impact of microplastic pollution in freshwater ecosystems has received growing scientific attention, although research on freshwater species remains limited compared to marine organisms. This study investigates the individual and combined toxicological impacts of polystyrene nanoparticles (PSNPs) and dibutyl phthalate (DBP) on hybrid snakehead (Channa maculata ♀ × Channa argus ♂), a commercially important freshwater fish. PSNPs inhibited growth, induced hepatic and intestinal lesions, and delayed ovarian development, co-exposure with DBP exacerbated these effects. qPCR analysis revealed significant up-regulation of inflammation-related genes in the liver but inhibitory effects in the intestines, indicating that PSNPs and DBP provoke immune modulation and systemic pro-inflammatory responses. Furthermore, PSNPs and DBP induced oxidative damage in the liver and intestines by affecting antioxidant enzyme activity. 16S rRNA sequencing revealed that PSNPs and DBP altered intestinal microbiota composition, particularly reducing Proteobacteria abundance. Correlation analyses indicated negative associations between the abundances of Proteobacteria and Firmicutes and antioxidant parameters (SOD and MDA), suggesting microbiota-mediated impacts on host metabolism and physiological health. These findings highlight the ecological threat of microplastics and phthalates in freshwater environments and underscore the need for targeted conservation strategies.

Figla is one of the earliest expressed genes in the oocyte during ovarian development. In this study, Figla was characterized in C. maculata, one of the main aquaculture species in China, and designated as CmFigla. The length of CmFigla cDNA was 1303 bp, encoding 197 amino acids that contained a conserved bHLH domain. CmFigla revealed a female-biased expression patterns in the gonads of adult fish, and CmFigla expression was far higher in ovaries than that in testes at all gonadal development stages, especially at 60~180 days post-fertilization (dpf). Furthermore, a noteworthy inverse relationship was observed between CmFigla expression and the methylation of its promoter in the adult gonads. Gonads at 90 dpf were used for in situ hybridization (ISH), and CmFigla transcripts were mainly concentrated in oogonia and the primary oocytes in ovaries, but undetectable in the testes. These results indicated that Figla would play vital roles in the ovarian development in C. maculata. Additionally, the frame-shift mutations of CmFigla were successfully constructed through the CRISPR/Cas9 system, which established a positive foundation for further investigation on the role of Figla in the ovarian development of C. maculata. Our study provides valuable clues for exploring the regulatory mechanism of Figla in the fish ovarian development and maintenance, which would be useful for the sex control and reproduction of fish in aquaculture.