Background: The mitochondrial genome is widely used to understand the phylogeny and evolution of fish. This study aims to deepen the understanding of the mitochondrial genome of Schistura fasciolata and the evolutionary implications within Nemacheilini. 
 
Methods: This study utilized high-throughput sequencing technology and bioinformatics analysis to investigate the mitochondrial genome of the Schistura fasciolata. The aim was to reveal its structural or compositional characteristics, phylogenetic location and evolutionary rate. 
 
Result: We conducted a comprehensive sequence analysis of the complete mitochondrial genome of S. fasciolata, in which it contains 16,570 base pairs (bp) including 37 genes, i.e., 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs) and two ribosomal RNA genes (rRNAs). The base composition analysis indicated an A+T content of 56.51% and a G+C content of 43.49%. Phylogenetic analysis based on the 13 PCGs revealed extensive polyphyly within Nemacheilini. Furthermore, accelerated evolution in ND4, ND5 and CYTB genes were observed in Homatula and Troglonectes, suggesting an adaptation to specific environmental conditions. This study provides critical insights into the phylogeny and adaptive evolution within Nemacheilini. 
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The Complete Mitochondrial Genome of Schistura fasciolata: Phylogenetic and Evolutionary Implications within Tribe Nemacheilini

Background: The mitochondrial genome serves as a pivotal molecular marker for delving into systematic relationships and adaptive mechanisms. The genus Eothenomys (Cricetidae: Arvicolinae) has consistently attracted attention due to its similar biological characteristics and the analysis of its mitochondrial genome offers a fresh perspective for comprehending the phylogeny and adaptation within Cricetidae. 
 
Methods: We sequenced and analyzed the entire mitochondrial genome of E. olitor and utilized the 13 PCGs derived from this genome to delineate the phylogenetic relationships within the Cricetidae and further evaluated the evolutionary rate of each PCG. 
 
Result: The findings revealed that the mitochondrial genome of E. olitor was 16,351 bp in length, including 13 PCGs with ATN initiation codons, 22 tRNAs, 2 rRNAs and 1 D-loop. Apart from the nad6 and 8 tRNAs positioned on the J-strand, the majority of the genetic elements were situated on the N-strand. The phylogenetic examination yielded a robust phylogenetic tree for Cricetidae, but the placement of some genera remained contentious, which needs more integrative and effective data. Among of them, E. olitor was a sister of E. chinensis and Eothenomys was monophyletic. Moreover, a selective analysis showed that evolutionary rates are significant differences among the 13 PCGs. Among these genes, atp8 a high evolutionary rate, while cox1 has a low. This research uncovered the mitochondrial genome analysis of E. olitor, offering valuable perspectives the phylogeny and adaptation within Cricetidae.

Phylogenetic Insights from the Mitochondrial Genome of Eothenomys olitor (Thomas, 1911): A Cricetidae Perspective

Background: Astragalus is one of the largest angiosperms and has important economic value. The chloroplast genomes (Cp) of most plants in its family have been sequenced and annotated, but there are fewer studies on the characteristics of the chloroplast genomes and codon usage bias of Astragalus. In this study, we sequenced and annotated the complete chloroplast genomes of three Astragalus species, that systematically compared the chloroplast genome and codon usage characteristics of three Astragalus. 
 
Methods: In this study, we used three Astragalus species as materials. Firstly, we sequenced and assembled their chloroplast genomes. Subsequently, we analyzed the codon usage bias of the chloroplast genomes of the three medicinal Astragalus species using software such as CodonW, CUSP and SPSS. 
 
Result: The results illustrated that the length of Astragalus chloroplast genome ranges from 122,815 bp (A. dahuricus) to 123,729 bp (A. melilotoides Pall.). There were 107-110 genes, including 75-76 protein-coding genes (PCGs), four ribosomal RNA genes (rRNAs) and 28-30 transfer RNA genes (tRNAs). In addition, the results illustrated that codons in three Cp genomes from Astragalus had the same 11 Optimal codons and ending with A/U. The codon usage frequency of five model creatures were compared and the results revealed that the codon preferences of Astragalus and five model creatures were pretty significant, the natural selection was the main factor in codon preference. Our research provides some value for the researches of chloroplast genetic engineering and molecular breeding in Astragalus.

The Complete Mitochondrial Genome of Schistura fasciolata: Phylogenetic and Evolutionary Implications within Tribe Nemacheilini

Phylogenetic Insights from the Mitochondrial Genome of Eothenomys olitor (Thomas, 1911): A Cricetidae Perspective

Comparison of the Complete Chloroplast Genomes in the Astragalus