Zoological Research最新文献

In adult mammals, optic nerve injury leads to irreversible vision loss due to its extremely limited regenerative capacity. In contrast, adult zebrafish possess a robust capacity for spontaneous visual system regeneration, although the spatiotemporal coordination of recovery across the retina, optic nerve, and brain remains poorly understood. In the present study, the regenerative dynamics following optic nerve transection were systematically characterized in adult zebrafish over a 5 week period using hematoxylin-eosin staining, immunohistochemistry, transmission electron microscopy, single-cell RNA sequencing, and optokinetic response (OKR) behavioral assessments. At 1 week post-injury (1 wpi), retinal ganglion cell depletion was evident but showed significant recovery by 2 wpi. Concurrently, the injured optic nerve displayed a marked increase in diameter and cell number at 2 wpi, including widespread expression of proliferating cell nuclear antigen, consistent with heightened proliferative activity. Single-cell transcriptomic profiling at 2 wpi revealed five principal cell populations: fibroblasts, mural cells, immune cells, mature oligodendrocytes, and myelin-forming oligodendrocytes. By 4-5 wpi, remyelination within the optic nerve and re-establishment of synaptic architecture in the optic tectum were strongly correlated with functional restoration of OKR behavior. These findings provide a comprehensive spatiotemporal framework of visual pathway regeneration in zebrafish, establishing a valuable model for elucidating conserved mechanisms of neural repair with translational potential for human vision restoration.

Germ-free mice exhibit profound immunological immaturity. Despite recent studies emphasizing the role of specific bacterium-derived metabolites in immune cell development and differentiation, the mechanisms linking microbiota absence to systemic immune deficits remain incompletely defined. Here, droplet-based single-cell RNA sequencing of bone marrow and peripheral blood from both germ-free and specific pathogen-free mice was performed, identifying 25 transcriptionally distinct cell types. Neutrophil apoptosis was elevated in germ-free mice, potentially due to the absence of niacin dehydrogenase, a metabolite primarily produced by Pseudomonas. In addition, germ-free mice exhibited increased excretion of 5'-methylthioadenosine, enhanced ERK activation driven by reactive oxygen species, and disruption of bone marrow stromal antigen 2 signaling. Monocytes and CD8 ⁺ T cells from germ-free mice showed diminished responses to interferon-β and interferon-γ, consistent with heightened viral susceptibility. These findings establish a microbiota-dependent regulatory pathway linking immunodeficiency to microbial absence in germ-free mice, confirmed through complementary validation techniques.

Ring finger protein 122 (RNF122), an E3 ubiquitin ligase, orchestrates antiviral immune responses in mammals by targeting retinoic acid-inducible gene 1 and melanoma differentiation-associated gene 5 for ubiquitination. However, its functional relevance in teleosts has yet to be clearly defined, particularly regarding the identification of substrate-specific regulatory sites. This study characterized RNF122 from mandarin fish ( Siniperca chuatsi), termed scRNF122, and investigated its regulatory impact on stimulator of interferon genes (STING)-mediated antiviral signaling. Results showed that scRNF122 expression was up-regulated in response to mandarin fish ranavirus (MRV) infection, and its overexpression suppressed scSTING-mediated interferon (IFN) production and enhanced MRV replication. Co-immunoprecipitation confirmed a direct interaction between scRNF122 and scSTING. Functional assays demonstrated that scRNF122 facilitated scSTING degradation through the ubiquitin-proteasome pathway, a process impeded by MG132 treatment. Ubiquitination analyses of various scSTING mutants revealed that scRNF122 catalyzed scSTING ubiquitination at K95, K117, and K155 residues. Moreover, scRNF122 significantly impaired scSTING-dependent antiviral responses by engaging negative regulatory elements within the signaling cascade. Overall, scRNF122 was identified as a negative modulator of STING-mediated IFN signaling in mandarin fish, diminishing STING-dependent antiviral activity and promoting its degradation via the ubiquitin-proteasome pathway at lysine residues K95, K117, and K155. These findings provide mechanistic insight into the post-translational control of STING in teleosts and establish a foundation for future investigations into antiviral immune regulation.

Comprehensive phylogeographic insights require the integration of evidence across diverse taxa, ecosystems, and geographical regions. However, our understanding of the arid biota of the vast Asian drylands remains limited. Accordingly, this study combined phylogeographic analyses with ecological niche modeling to investigate patterns of diversification and demography of the Central Asian racerunner ( Eremias vermiculata), a widespread lizard inhabiting arid eastern-Central Asia (AECA). Mitochondrial DNA (mtDNA) sequences were obtained from 876 individuals across 113 localities, while three nuclear genes- CGNL1, MAP1A, and β-fibint7-were sequenced from 204, 170, and 138 individuals, respectively. Analyses identified four distinct mtDNA lineages corresponding to specific geographic subregions within the AECA, reflecting the topographic and ecological heterogeneity of the region. The detection of mito-nuclear discordance indicated the presence of complex evolutionary dynamics. Divergence dating placed the initial lineage splits at approximately 1.18 million years ago, coinciding with major tectonic activity and climatic aridification that likely promoted allopatric divergence. In particular, lineage diversification within the Tarim Basin suggests that recent environmental shifts may have contributed to genetic divergence. Demographic reconstructions revealed signatures of population expansion or range shifts across all lineages during the Last Glacial Maximum, signifying the combined influence of the unique topography and climate dynamics of the AECA on diversification and demographic change. These results highlight the need for fine-scale genomic investigations to clarify the mechanisms underlying mito-nuclear discordance and local adaptation. Such efforts are essential for advancing understanding of how genetic diversity in dryland taxa responds to environmental change, providing insights into the evolutionary adaptability of species in dynamic landscapes.

Chorionic gonadotropin α (Cgα) functions as the shared subunit for thyroid-stimulating hormone subunit β (Tshβ), luteinizing hormone subunit β (Lhβ), and follicle-stimulating hormone subunit β (Fshβ). While these β-subunits have been extensively studied using effective gene knockout models in zebrafish, the biological role of Cgα remains elusive. In this study, cgα-deficient zebrafish generated via transcription activator-like effector nucleases (TALENs) exhibited viability but displayed pronounced developmental abnormalities, including growth retardation, hyperpigmentation, reduced thyroxine (T4) levels, and defective anterior swim bladder inflation during juvenile stages. In adults, cgα deficiency led to disrupted gonadal development, impaired secondary sex characteristics (SSCs), and severely impacted reproductive behavior in both female and male fish. Notably, both testicular and ovarian differentiation were observed in cgα-deficient fish and lhβ ^-/- ; fshβ ^-/- mutants. Gonadal sex differentiation in cgα-deficient zebrafish exhibited a pronounced shift toward testicular fate upon additional disruption of fshβ ( cgα ^-/-; fshβ ^-/-), marked by elevated anti-Müllerian hormone ( amh) expression, or following loss of follicle-stimulating hormone receptor ( fshr) ( cgα ^-/-; fshr ^-/-). In vitro assays in Chinese hamster ovary (CHO) cells revealed increased cAMP response element (CRE) promoter activity following transfection with constructs encoding Fshr, Fshβ/Fshr, or Cgα/Fshβ/Fshr. Collectively, the phenotypes observed in cgα-deficient fish recapitulate those of thyrotropin- and gonadotropin-disrupted models, highlighting the essential role of Cgα in thyroid and gonadal function. Importantly, these findings uncover the role of Fsh signaling in maintaining proper ovarian differentiation in zebrafish, including Cgα-independent Fshβ activity and the constitutive functionality of Fshr.

The DNA replication stress (RS) response is crucial for maintaining cellular homeostasis and promoting physiological longevity. However, the mechanisms by which long-lived species, such as bats, regulate RS to maintain genomic stability remain unclear. Also, recent studies have uncovered noncanonical roles of ribosome-associated factors in maintaining genomic stability. In this study, somatic skin fibroblasts from the long-lived big-footed bat ( Myotis pilosus) were examined, with results showing that bat cells exhibited enhanced RS tolerance compared to mouse cells. Comparative transcriptome analysis under RS conditions revealed pronounced species-specific transcriptional differences, including robust up-regulation of ribosome biogenesis genes in bat cells and a markedly reduced activation of the P53 signaling pathway. These features emphasize a distinct homeostatic strategy in bat cells. Nuclear fragile X mental retardation-interacting protein 1 ( Nufip1), a ribosome-associated factor highly expressed in bat fibroblasts, was identified as a potential integrator of ribosomal and P53 signaling via its association with ribosomal protein S27-like (Rps27l). These findings provide direct cellular and molecular evidence for a noncanonical RS response in bats, highlighting a deeper understanding of the biological characteristics and genomic maintenance mechanisms of long-lived species.

Bromodomain (BRD)-containing proteins are central mediators of gene regulation, serving as key components of chromatin remodeling complexes and histone recognition scaffolds. By specifically recognizing acetylated lysine residues on histones (Kac) via their conserved BRD, these proteins influence chromatin structure and gene expression. Although their overarching role is well-established, the precise molecular functions and mechanisms of individual BRD proteins remain incompletely characterized. The ciliate Tetrahymena thermophila, a unicellular eukaryote with a transcriptionally active macronucleus enriched in histone acetylation, is an excellent model for exploring the significance of BRD-containing proteins. In this comprehensive review, all BRD-containing proteins encoded in the T. thermophila genome are systematically examined, including their expression profiles, histone acetylation targets, interacting proteins, and potential roles. This review lays the groundwork for future investigations into the complex roles of BRD proteins in chromatin remodeling and transcription regulation, offering insights into basic eukaryotic biology and the molecular mechanisms underlying BRD-linked diseases.

The yellow boxfish ( Ostracion cubicus) exhibits a combination of derived morphological traits specialized for coral reef environments and ancestral characteristics, including a fused dermal plate. Contradictory evolutionary evidence hinders true classification of O. cubicus. To clarify its evolutionary position within Tetraodontiformes, a chromosome-level genome assembly was generated, representing the most contiguous and complete genome to date for this lineage. Notably, O. cubicus possessed the largest genome within the order Tetraodontiformes, primarily due to extensive transposable element expansion. Phylogenetic analysis based on 19 whole genomes and 131 mitochondrial genomes resolved Tetraodontiformes into three major sister groups (Ostraciidae-Molidae, Tetraodontidae, and Balistidae-Monacanthidae). Comparative genomic evidence indicated that O. cubicus diverged early from the common ancestor of modern Tetraodontiformes and retained the highest number of HOX genes among surveyed taxa. Although overall genomic architecture was largely conserved, certain genetic and environmental changes may have contributed to its phenotypic adaptations, including climate cooling during the Miocene-Pliocene Transition, recent DNA and long interspersed nuclear element (LINE) transposon bursts, lineage-specific chromosomal rearrangements, and gene family expansion. Many positively selected genes and rapidly evolving genes were associated with skeletal development, including bmp7, egf7, and bmpr2. Transcriptomic comparisons between carapace and tail skin revealed various candidate genes and pathways related to carapace formation, such as postn, scpp1, and components of the TGF-β signaling pathway. A derived amino acid substitution in eda, coupled with protein structural modeling, suggested potential molecular convergence in dermal plate formation among teleosts. These findings provide novel insights into the genomic and developmental basis of carapace evolution and coral reef-adaptation in O. cubicus, offering a strong case for evolutionary balance between genomic conservation with regulatory innovation to achieve coral reef specialization.