Erythropoietin (EPO) is a glycoprotein hormone that plays a principal regulatory role in erythropoiesis and initiates cell homeostatic responses to environmental challenges. The Qinghai-Tibet Plateau is a natural laboratory for hypoxia adaptation. Gymnocypris dobula is a highly specialized plateau schizothoracine fish that is restricted to > 4500 m high-altitude freshwater rivers and ponds in the Qinghai-Tibet Plateau. The role of EPO in the adaptation of schizothoracine fish to hypoxia is unknown. The EPO and EPO receptor genes from G. dobula and four other schizothoracine fish from various altitudinal habitats were characterized. Schizothoracine EPOs are predicted to possess 2–3 N-glycosylation (NGS) sites, 4–5 casein kinase II phosphorylation (CK2) sites, 1–2 protein kinase C (PKC) phosphorylation sites, and four conserved cysteine residues within four helical domains, with variations in the numbers of NGS and CK2 sites in G. dobula. PAML analysis indicated a d N/d S value (ω) = 1.112 in the G. dobula lineage, and a few amino acids potentially under lineage-specific positive selection were detected within the G. dobula EPO. Similarly, EPO receptors of the two high-altitude schizothoracines (G. dobula and Ptychobarbus kaznakovi), were found to be statistically on the border of positive selection using the branch-site model (P-value = 0.096), and some amino acids located in the ligand-binding domain and the fibronectin type III domain were identified as potentially positive selection sites. Tissue EPO expression profiling based on transcriptome sequencing of three schizothoracines (G. dobula, Schizothorax nukiangensis Tsao, and Schizothorax prenanti) showed significant upregulation of EPO expression in the brain and less significantly in the gill of G. dobula. The elevated expression together with the rapid evolution of the EPO gene in G. dobula suggested a possible role for EPO in adaptation to hypoxia. To test this hypothesis, Gd-EPO and Sp-EPO were cloned into an expression vector and transfected into the cultured cell line 293 T. Significantly higher cell viability was observed in cells transfected with Gd-EPO than cells harboring Sp-EPO when challenged by hypoxia. The deduced EPO proteins of the schizothoracine fish contain characteristic structures and important domains similar to EPOs from other taxa. The presence of potentially positive selection sites in both EPO and EPOR in G. dobula suggest possible adaptive evolution in the ligand-receptor binding activity of the EPO signaling cascade in G. dobula. Functional study indicated that the EPO from high-altitude schizothoracine species demonstrated features of hypoxic adaptation by reducing toxic effects or improving cell survival when expressed in cultured cells, providing evidence of molecular adaptation to hypoxic conditions in the Qinghai-Tibet Plateau.

The aim of this study was to provide practical suggestions for land use regulation to mitigate the impacts of intense urbanization using integrated modeling. To achieve effective urbanization management, it is essential to quantify the habitats of critical species and predict their dynamics in response to urbanization impacts in the future. In this study, we developed an integrated bird-habitat modeling that combines maximum entropy and patch-generating land use simulation based on a field survey of bird populations to characterize the habitat dynamics of birds in the Yangtze River Estuary (YRE) under urbanization impacts. Our findings revealed the following: (1) The YRE experienced fundamental fragmentation from 2000. (2) The year 2010 was a turning point, and from 2000 to 2037, habitats for all bird species tended to overlap and fragment, and decreased from 66% to 45%, resulting in a loss of about 4340 km². (3) The maintenance of a buffer area of 300 m around built-up areas was crucial for preserving bird habitats. Based on the identified variables, the hotspots of birds’ habitats were prioritized and the regulation measures to mitigate urbanization impacts are proposed in YRE.

Hypoxia adaptation is developed in many fish species, which helped them to habitat most of water bodies. However, fishes living under high oxygen concentration may lose this feature. Rapid flows provide high level and stable dissolved oxygen, which facilitate organism’s oxygen supply and energy production. Previous studies showed that fish species from rapid-flow habitats exhibited lower hypoxia tolerance compared with fish from intermediate- and slow-flow habitats. Mitochondrial genomes code 13 key components in oxidative phosphorylation pathway; these genes may be under relaxed selection in rapid-flow species.

Antarctic icefish Pagothenia borchgrevinki is an ideal model for studying heat stress mechanisms. The complete mitochondrial genome of P. borchgrevinki was sequenced in this study. The genome sequence is 17,299 bp in length, which comprises 13 protein-coding genes, 22 tRNAs, 2 rRNAs and a control region. The overall base composition is 20.45% G, 25.11% A, 29.46% T and 24.98 C%, with an A:T content of 54.57%.

Psectrocladius, a genus within the species-rich subfamily Orthocladiinae (Diptera: Chironomidae), remains poorly resolved in molecular phylogenetics due to limited available molecular data. Here, we sequenced and analyzed the complete mitogenomes of five Psectrocladius species, using two Rheocricotopus species as outgroups. Our results reveal that the mitogenomes of Psectrocladius are structurally conserved and retain a presumed ancestral gene order. The nucleotide composition of these newly generated mitogenomes exhibits a pronounced A + T bias, which is characteristic of typical insect mitogenomes. The substitution rates, estimated using Ka/Ks ratios, indicate that all protein-coding genes are under purifying selection. The strongest purifying selection pressure was observed in the CO1 gene, while the weakest was in the ND5 gene. Both the maximum likelihood and Bayesian inference trees consistently show the following topology: ((((P. schlienzi + P. bisetus) + P. barbimanus) + P. oligosetus) + P. aquatronus). This study provides key insights into chironomid mitogenomes and their gene properties, offering valuable reference data for future research.