Complete mitochondrial genome sequence of Lepus yarkandensis Günther, 1875 (Lagomorpha, Leporidae): characterization and phylogenetic analysis

Comparative study of cytochrome P450 expression in the kidneys of Lepus yarkandensis and Oryctolagus cuniculus

Lepus yarkandensis is a desert hare of the Tarim Basin in western China, and it has strong adaptability to drought environments. Cytochrome P450s (CYP450s) are important metabolic enzymes, and their metabolites (19-hydroxyeicosatetraenoic acid (19-HETE), 20-HETE, and epoxyeicosatrienoic acids (EETs)) are important for regulating kidney water absorption and sodium excretion. This study aimed to investigate the expression of CYP450 enzymes in the kidneys of L. yarkandensis. Our results revealed significant upregulation of CYP2E1 in L. yarkandensis kidneys compared with Oryctolagus cuniculus kidneys, particularly on the basolateral plasma membrane of proximal convoluted tubule (PCT) and proximal straight tubule (PST) cells, as well as in the outer medullary collecting duct and in the beginning and middle sites of the inner medullary collecting duct. In contrast, the expression of CYP2C, CYP2J, CYP4A11, and CYP4F3 was notably downregulated in the kidneys of L. yarkandensis, primarily in the basolateral plasma membrane of PCT and PST cells. Additionally, the levels of 19-HETE are greater, whereas those of 20-HETE and EETs are lower in the kidneys of L. yarkandensis than in those of O. cuniculus. The altered expression patterns of these CYP450 enzymes suggest that L. yarkandensis has a greater capacity for renal water reabsorption.

The first complete mitochondrial genome of Sumatran striped rabbit Nesolagus netscheri (Schlegel, 1880), and its phylogenetic relationship with other Leporidae

Nesolagus netscheri, a Sumatran striped rabbit, is one of the rarest rabbits in the Leporidae family, and its genetic information is still limited. This study provides the first mitochondrial genome and molecular systematic characterization of the Sumatran striped rabbit, Nesolagus netscheri, Indonesia's rarest rabbit. It consists of a circular double-stranded DNA of 16,709 bp. It showed that the mitochondrial genome structure of N. netscheri is similar to that of N. timminsi. The mitochondrial genome of N. netscheri contained 22 transfer RNA (tRNA) genes, and all tRNA except for trnS1 showed a characteristic cloverleaf secondary structure. Evidence was found that the atp8 gene of N. netscheri is under positive selection pressure. The phylogenetic analysis shows Leporidae was monophyletic, with Nesolagus at the basal. The study indicates a split between N. netscheri and N. timminsi in the Late Pleistocene around 0.43 million years ago. This research is a fundamental reference for the conservation of the rarest lagomorph species and provides important information for future evolutionary studies in the Leporidae family.

The Functional Identification of the CYP2E1 Gene in the Kidney of Lepus yarkandensis

This study aims to identify the function of the cytochrome P450 2E1 (CYP2E1) gene in the kidneys of Lepus yarkandensis. CYP2E1 is a significant metabolic enzyme involved in the metabolism of various endogenous and exogenous compounds and is associated with the occurrence and progression of multiple diseases. Given L. yarkandensis's ability to survive in the extremely arid L. yarkandensis, we hypothesize that CYP2E1 in its kidneys plays a crucial role in adaptability. Through molecular cloning and sequence analysis, we discovered that the CYP2E1 gene of Lepus yarkandensis encodes a protein of 493 amino acids. The 493-amino acid protein encoded by the Lepus yarkandensis CYP2E1 gene shows 13 amino acid variation sites compared to the homologous protein in Oryctolagus cuniculus. The protein is primarily localized to the endoplasmic reticulum membrane and lacks transmembrane structures. In the yeast expression system, the heterologous expression of the CYP2E1 gene enhanced the yeast's tolerance to drought, salinity, and high temperatures, achieved by increasing antioxidant enzyme activity and reducing levels of oxidative stress markers. Additionally, this study identified a "Yeast Oxidative Stress Lethal Threshold (Yeast OSLT)" under specific stress conditions. Once this threshold is exceeded, the cell's antioxidant defense system can no longer maintain cellular homeostasis, leading to massive cell death. Although CYP2E1 did not change this threshold, it contributed to cell survival to some extent. These findings not only reveal the function of L. yarkandensis CYP2E1 in stress adaptation but also provide valuable molecular insights into its survival strategy in extreme environments.

Complete Mitogenomes of Xinjiang Hares and Their Selective Pressure Considerations

Comparative analysis based on the mitogenomes of hares in Xinjiang, China, is limited. In this study, the complete mitochondrial genomes of seven hare samples including four hare species and their hybrids from different environments were sequenced, assembled, and annotated. Subsequently, we performed base content and bias analysis, tRNA analysis, phylogenetic analysis, and amino acid sequence analysis of the annotated genes to understand their characteristics and phylogenetic relationship. Their mitogenomes are circular molecules (from 16,691 to 17,598 bp) containing 13 protein-coding genes, two rRNA genes, 22 tRNA genes, and a control region, which are similar with other Lepus spp. worldwide. The relative synonymous codon usage analysis revealed that the adaptation of Lepus yarkandensis to its unique arid and hot environment might be associated with synthesizing amino acids like alanine, leucine, serine, arginine, and isoleucine and the terminator caused by the different usage of codons. Further, we utilized the MEME model and identified two positive selection genes (ND4, ND5) in Lepus tibetanus pamirensis and one (ND5) in L. yarkandensis that might be important to their adaptation to the plateau and dry and hot basin environments, respectively. Meanwhile, Lepus tolai lehmanni and Lepus timidus may have evolved different adaptive mechanisms for the same cold environment. This study explored the evolutionary dynamics of Xinjiang hares' mitochondrial genomes, providing significant support for future research into their adaptation mechanisms in extreme environments.

Selective sweep analysis of the adaptability of the Yarkand hare (Lepus yarkandensis) to hot arid environments using SLAF-seq

The Yarkand hare (Lepus yarkandensis) inhabits arid desert areas and is endemic to China. It has evolved various adaptations to survive in hot arid environments, including stress responses, the ability to maintain water homeostasis and heat tolerance. Here, we performed a selective sweep analysis to identify the candidate genes for adaptation to hot arid environments in the Yarkand hare. A total of 397 237 single-nucleotide polymorphisms were obtained from 80 Yarkand hares, which inhabit hot arid environments, and 36 Tolai hares (Lepus tolai), which inhabit environments with a mild climate, via specific-locus amplified fragment sequencing. We identified several candidate genes that were associated with the heat stress response (HSPE1), oxidative stress response (SLC23A and GLRX2), immune response (IL1R1 and IRG1), central nervous system development (FGF13, THOC2, FMR1 and MECP2) and regulation of water homeostasis (CDK1) according to fixation index values and θπ ratios in the selective sweep analysis, and six of these genes (GLRX2, IRG1, FGF13, FMR1, MECP2 and CDK1) are newly discovered genes. To the best of our knowledge, this is the first study to identify candidate genes for adaptation to hot arid environments in the Yarkand hare. The results of this study enhance our understanding of the adaptation of the Yarkand hare to hot arid environments and will aid future studies aiming to functionally verify these candidate genes.

Sequencing and description of the complete mitochondrial genome of Limatus durhamii (Diptera: Culicidae)

The genus Limatus (Diptera: Culicidae) are wild mosquitoes belonging to the Sabethini tribe that occurs in tropical countries and is related to transmission cycles of Orthobunyavirus (Bunyaviridae), particularly in the Amazon region. Given the unavailability of information related to evolutionary biology and molecular taxonomy aspects of this genus, we report here the first complete sequencing of the mitochondrial genome of Limatus durhamii Theobald, 1901. The NextSeq 500 platform was used for sample sequencing, and the mitochondrial sequence obtained was 14,875 bp long, comprising 37 functional subunits (13 PCGs, 22 tRNA and 02 rRNA). The phylogeny reconstructed by maximum likelihood based on the concatenation of all 13 PCGs corroborated the known taxonomic classification based most on aspects of the external morphology and few molecular studies. The data and information produced here may be useful in the future development of taxonomic and evolutionary studies for the genus, as well as the Culicidae family itself.

Mitogenomic Features and Evolution of the Nile River Dominant Tilapiine Species (Perciformes: Cichlidae)

To better understand the diversity and evolution of cichlids, we sequenced, assembled, and annotated the complete mitochondrial genomes of three Nile tilapiine species (Coptodon zillii, Oreochromis niloticus, and Sarotherodon galilaeus) dominating the Nile River waters. Our results showed that the general mitogenomic features were conserved among the Nile tilapiine species. The genome length ranged from 16,436 to 16,631 bp and a total of 37 genes were identified (two ribosomal RNA genes (rRNAs), 22 transfer RNA genes (tRNAs), 13 protein-coding genes (PCGs), and 1 control region). The ND6 was the only CDS that presented a negative AT skew and a positive GC skew. The most extended repeat sequences were in the D-loop followed by the pseudogenes (trnS^GCU). The ND5 showed relatively high substitution rates whereas ATP8 had the lowest substitution rate. The codon usage bias displayed a greater quantity of NNA and NNC at the third position and anti-bias against NNG. The phylogenetic relationship based on the complete mitogenomes and CDS was able to differentiate the three species as previously reported. This study provides new insight into the evolutionary connections between various subfamilies within cichlids while providing new molecular data that can be applied to discriminate between Nile tilapiine species and their populations.

Description of mitochon genome and phylogenetic considerations of Sabethes bipartipes, Sabethes cyaneus, Sabethes quasicyaneus, and Sabethes tarsopus (Diptera: Culicidae)

The genus Sabethes (Diptera: Culicidae) comprises species of great epidemiological relevance, particularly involved in transmission cycles of the Yellow fever virus in South America. Given the unavailability of information related to aspects of evolutionary biology and molecular taxonomy of species of this genus of mosquitoes, we report here the first sequencing of the mitochondrial genomes of Sabethes bipartipes, Sabethes cyaneus, Sabethes tarsopus, and Sabethes quasicyaneus. The sequences obtained showed an average length of 14,920 bp, comprising 37 functional genes (13 PCGs, 22 tRNA, and 02 rRNA). The phylogenies reconstructed by Maximum likelihood and Bayesian inference methods, based on the concatenated sequences of all 13 PCGs, produced similar topologies and strongly supported the monophyletic relationship between the Sabethes subgenera, corroborating the known taxonomic classification based on aspects of the external morphology of the taxa assessed. The data and information produced from the Sabethes species evaluated here may be useful for future taxonomic and evolutionary studies of the genus, as well as the Culicidae family.

Expression Regulation of Water Reabsorption Genes and Transcription Factors in the Kidneys of Lepus yarkandensis

Lepus yarkandensis is a desert-dwelling animal that has various adaptations to cope with drought. The kidney maintains water and acid-base balance mainly through the vasopressin-regulated water reabsorption pathway and proximal tubular bicarbonate reabsorption pathway. In this study, we compared the differentially expressed genes (DEGs) and transcription factors in the kidneys of L. yarkandensis and Oryctolagus cuniculus to explore the relationship between the DEGs in kidneys and the animals’ adaptations. Transcriptome sequencing data were used to predict the differentially-expressed water reabsorption genes and their transcription factors. Quantitative real-time PCR, immunohistochemistry, and western blotting were used to detect and verify the expression of DEGs in the kidney at mRNA and protein levels. Transcriptome analysis of the kidney of L. yarkandensis and O. cuniculus showed that 6,610 genes were up-regulated and 5,727 genes down-regulated in data shared by both species. According to the data, 232 transcription factors and their corresponding target genes were predicted, from which genes and transcription factors related to renal water reabsorption were screened. Quantitative RT-PCR results showed AQP1, AQP2, ADCY3, HIF1A, CREB3, and NFATc1 had higher expression in the L. yarkandensis kidney; in comparison, FXYD2 mRNA expression levels were lower. In western blotting, transcription factors HIF1A, NFATc1, NF-κB1, and critical genes ADCY3, ATPA1, and SLC4A4, were highly expressed in the kidneys of L. yarkandensis. Immunohistochemical results showed that the ADCY3 protein was in the basolateral membrane of the collecting duct, the ATP1A1 protein was in the basolateral membrane and medulla of proximal tubules, and the SLC4A4 protein was in the basolateral membrane of proximal tubules. According to these results can be inferred that HIF1A, NFATc1, and NF-κB1 play a certain role in regulating the expression of genes related to water reabsorption in the kidney of L. yarkandensis, thus improving the water reclamation efficiency of L. yarkandensis, so as to adapt to the arid desert environment.

Characterisation of the Complete Mitochondrial Genome of Critically Endangered Mustela lutreola (Carnivora: Mustelidae) and Its Phylogenetic and Conservation Implications

In this paper, a complete mitochondrial genome of the critically endangered European mink Mustela lutreola L., 1761 is reported. The mitogenome was 16,504 bp in length and encoded the typical 13 protein-coding genes, two ribosomal RNA genes and 22 transfer RNA genes, and harboured a putative control region. The A+T content of the entire genome was 60.06% (A > T > C > G), and the AT-skew and GC-skew were 0.093 and −0.308, respectively. The encoding-strand identity of genes and their order were consistent with a collinear gene order characteristic for vertebrate mitogenomes. The start codons of all protein-coding genes were the typical ATN. In eight cases, they were ended by complete stop codons, while five had incomplete termination codons (TA or T). All tRNAs had a typical cloverleaf secondary structure, except tRNA^Ser(AGC) and tRNA^Lys, which lacked the DHU stem and had reduced DHU loop, respectively. Both rRNAs were capable of folding into complex secondary structures, containing unmatched base pairs. Eighty-one single nucleotide variants (substitutions and indels) were identified. Comparative interspecies analyses confirmed the close phylogenetic relationship of the European mink to the so-called ferret group, clustering the European polecat, the steppe polecat and the black-footed ferret. The obtained results are expected to provide useful molecular data, informing and supporting effective conservation measures to save M. lutreola.