Gut microbiota homeostasis is important for host health and well-being; however, drugs may affect the composition and function of the gut microbiota. Red-crowned cranes are a vulnerable species. Treatment of red-crowned cranes with avian influenza vaccines and anthelmintics has played pivotal roles in therapeutic management in zoos. To investigate the changes in the diversity and composition of gut microbiota after the avian influenza vaccine and anthelmintic treatment, we used 16S rRNA sequencing to obtain and compare the bacterial community composition before and after the treatment. The alpha diversity of the gut microbiota of red-crowned cranes decreased on the day of the treatment and then fluctuated over time. The composition of gut microbiota tended to be similar in the short term after the treatment, as supported by the beta diversity hierarchical cluster analysis. Only 3, 8, and 72 operational taxonomic units (OTUs) of the three individuals were shared among the five groups before and after treatment. The relative abundance of Firmicutes significantly increased to 99.04% ± 0.28% on the day of the treatment, in which the relative abundance of Lactobacillus was 93.33% ± 5.85%. KEGG pathways analysis indicated that the main function of the gut microbiota is involved in metabolism, and the present study indicates that the gut microbiota of red-crowned cranes is resilient to the avian influenza vaccine and anthelmintic, even disordered in the short term, and could recover over time. More individual experimentation and functional potential in metabolism are needed in the future to support animal disease control and optimal management in the zoo.

We determined the complete mitochondrial genome of Thereuopoda clunifera (Chilopoda: Scutigeridae) to clarify the phylogenetic status within Chilopoda. Using Sanger sequencing and next-generation sequencing technologies, the entire mitogenome of T. clunifera was assembled and annotated, with 14,898 bp in length and 37 genes (13 protein-coding genes, 22 transfer RNA genes, and two ribosomal RNA genes), which are usually found in arthropod mitogenomes. Only one D-loop contained no repeat element. The base composition of T. clunifera was found to be A + T content of 69.55% and G + C content of 30.45%. The AT-skew of T. clunifera was positive, while the GC-skew was negative. The gene order of T. clunifera was identical to that of Scutigera coleoptrata that has been unique among those so far determined for the Arthropoda. We also performed phylogenetic analyses of 25 Myriapoda species to further explore the taxonomic and evolutionary relationships within Myriapoda and Chilopoda. Phylogenetic analyses supported that the division of Chilopoda into subclasses Notostigmophora and Pleurostigmophora.

Identification based on conventional morphological characteristics is typically difficult and time-consuming. The development of molecular techniques provides a novel strategy that relies on specific mitochondrial gene fragments to conduct authentication. For this study, five newly sequenced partial mitogenomes of earthworms (Bimastos parvus, Dendrobaena octaedra, Eisenia andrei, Eisenia nordenskioldi, and Octolasion tyrtaeum) with lengths ranging from 14,977 to 15,715 were presented. Each mitogenome possessed a putative control region that resided between tRNA-Arg and tRNA-His. All of the PCGs were under negative selection according to the value of Ka/Ks. The phylogenetic trees supported the classification of Eisenia and Lumbricus; however, the trees based on cox1 did not. Through various comparisons, it was determined that cox1 fragments might be more suitable for molecular identification. These results lay the foundation for further phylogenetic studies on Lumbricidae.

There has been debate about whether individuals with different color phenotypes should have different taxonomic status. In order to determine whether the different color phenotypes of Nedyopus patrioticus require separate taxonomic status or are simply synonyms, here, the complete mitochondrial genomes (mitogenomes) of two different colored N. patrioticus, i.e., red N. patrioticus and white N. patrioticus, are presented. The two mitogenomes were 15,781 bp and 15,798 bp in length, respectively. Each mitogenome contained 13 PCGs, 19 tRNAs, 2 rRNAs, and 1 CR, with a lack of trnI, trnL2, and trnV compared to other Polydesmida species. All genes were located on a single strand in two mitogenomes. Mitochondrial DNA analyses revealed that red N. patrioticus and white N. patrioticus did not show clear evolutionary differences. Furthermore, no significant divergence was discovered by means of base composition analysis. As a result, we suggest that white N. patrioticus might be regarded as a synonym for red N. patrioticus. The current findings confirmed the existence of color polymorphism in N. patrioticus, which provides exciting possibilities for future research. It is necessary to apply a combination of molecular and morphological methods in the taxonomy of millipedes.

Although the pencilfish is a globally popular economic fish in the aquarium market, its taxonomic classification could be further refined. In order to understand the taxonomy of species of the genus Nannostomus (Characiformes, Lebiasinidae) and their phylogenetic position within the order Characiformes, in this study, we characterized mitochondrial genomes (mitogenomes) from four Nannostomus species for the first time. The four mitogenomes exhibited the typical circular structure, with overall sizes varying from 16,661 bp to 16,690 bp. They contained 13 protein-coding genes (PCGs), 2 ribosomal RNA genes (rRNAs), 22 transfer RNA genes (tRNAs), and 1 control region (CR). Nucleotide composition analysis suggested that the mitochondrial sequences were biased toward A and T. Bayesian inference and maximum likelihood analyses based on PCGs support the family Lebiasinidae classification, described using four Nannostomus species, clustering together with Lebiasina multimaculata from the same family. The results of this study support the current taxonomic classification of the family Lebiasinidae. Phylogenetic analysis also suggested that gene rearrangement would not significantly impact the phylogenetic relationships within the order Characiformes. These results might provide new data regarding the phylogeny and classification of the order Characiformes, thus providing a theoretical basis for the economic development of aquarium fish markets.

Millipedes (Diplopoda) are crucial decomposers in soil ecosystems, as they play a vital role in organic matter degradation while also holding potential as bioindicators of environmental health. This study deciphered the complete mitogenomes of four millipede species (Diplopoda: Spirostreptida and Spirobolida) using next-generation sequencing technology, thus revealing evolutionary relationships among diplopod taxa and characterizing mitochondrial genomic features. The full mitochondrial sequences of Agaricogonopus acrotrifoliolatus, Bilingulus sinicus, Paraspirobolus lucifugus, and Trigoniulus corallinus, ranged in size from 14,906 to 15,879 bp, with each containing 37 typical genes and one D-loop region. Notably, the D-loop regions of A. acrotrifoliolatus and B. sinicus were positioned atypically, thus indicating structural rearrangements. A nucleotide composition analysis revealed pronounced AT-skews, with tRNA sequences exhibiting the highest A+T content. Ka/Ks ratios demonstrated that the ND5 gene experienced the weakest purifying selection pressure, thus suggesting its potential role in adaptive evolution. The results of the phylogenetic analysis showed genetic relationships between the three orders of ((Julida, Spirostreptida), Spirobolida), which was inconsistent with the previous conclusion regarding the three orders, obtained through morphological studies: ((Julida, Spirobolida), Spirostreptida). These findings highlight the role of the mitochondrial genome in resolving phylogenetic conflicts and provide important insights for further studies on millipedes.