Four new complete mitochondrial genomes of Gobioninae fishes (Teleostei: Cyprinidae) and their phylogenetic implications.

The subfamily Gobioninae is one of the most diverse fish groups within Cyprinidae. Their taxonomy and phylogenetic relationships are not completely resolved. In this study, the complete mitochondrial genomes (mitogenome) of four Gobioninae species (Microphysogobio elongatus, Microphysogobio chinssuensis, Gobio rivuloides and Rhinogobio nasutus) were sequenced and compared. The mitogenomes of four species ranges from 16603 bp to 16609 bp in length, consisting of 13 protein-coding genes (PCGs), 22 tRNA genes, two rRNA genes, and a control region. Most PCGs had significant codon usage bias. Except for the tRNASer (GCT), all the nucleotide substitutions of tRNA loops higher than the stems could fold into a stable secondary structure. The nucleotide compositions of Gobioninae mitogenome were biased toward A/T, and NAD4 was subjected to low purification selection and had a faster evolution rate among 13 PCGs. Bayesian inference and maximum likelihood phylogenetic analyses showed the consistent results. The four sequenced species clustered together with their congener species. However, more samples and mitogenome data are needed to untangle the phylogenetic relationships among genera Microphysogobio, Romanogobio, Hugobio, Biwia and Platysmacheilus.

Pleistocene Landscape Dynamics Drives Lineage Divergence of a Temperate Freshwater Fish Gobio rivuloides in Coastal Drainages of Northern China.

Understanding historical processes underlying lineage distribution patterns is a primary goal of phylogeography. We selected Gobio rivuloides (Cypriniformes: Gobionidae) as a model to improve our knowledge about how intraspecific genetic divergence of freshwater fishes arises in coastal drainages of northern China via statistical analysis using cytochrome b gene. The time-calibrated phylogeny of G. rivuloides showed the divergence of two major lineages (I and II) at ~0.98 Ma (million years ago). Lineage I can be divided into two sub-lineages (I-A and I-B) with a divergence time of ~0.83 Ma. Sub-lineage I-A inhabits the Amur River, and sub-lineage I-B lives in the Luan River and Liao River. Lineage II is distributed in the Yellow River and Hai River, with close genetic relationships between the two drainages, and can be split into two sub-lineages (II-C and II-D) with a divergence time of ~0.60 Ma. Our findings indicate that the splitting of lineages and sub-lineages could be attributed to geographic isolation caused by the formation of the Bohai Sea, river capture, and the episodic hydrologic closing of a paleolake during the late Lower-Middle Pleistocene. It is also the first report we know of displaying a clear phylogeographic break for freshwater fishes across coastal drainages in northern China.

The complete mitochondrial genome of Microphysogobioelongatus (Teleostei, Cyprinidae) and its phylogenetic implications.

Mitochondria are important organelles with independent genetic material of eukaryotic organisms. In this study, we sequenced and analyzed the complete mitogenome of a small cyprinid fish, Microphysogobioelongatus (Yao & Yang, 1977). The mitogenome of M.elongatus is a typical circular molecule of 16,612 bp in length containing 13 protein-coding genes (PCGs), 22 transfer RNA genes, two ribosomal RNA genes, and a 930 bp control region. The base composition of the M.elongatus mitogenome is 30.8% A, 26.1% T, 16.7% G, and 26.4% C. All PCGs used the standard ATG start codon with the exception of COI. Six PCGs terminate with complete stop codons, whereas seven PCGs (ND2, COII, ATPase 6, COIII, ND3, ND4, and Cyt b) terminate with incomplete (T or TA) stop codons. All tRNA genes exhibited typical cloverleaf secondary structures with the exception of tRNASer(AGY), for which the dihydrouridine arm forms a simple loop. The phylogenetic analysis divided the subfamily Gobioninae in three clades with relatively robust support, and that Microphysogobio is not a monophyletic group. The complete mitogenome of M.elongatus provides a valuable resource for future studies about molecular phylogeny and/or population genetics of Microphysogobio.

Complete mitochondrial genome of Ladislavia taczanowskii (Cypriniformes: Gobionidae).

Mitochondrial genomes of two individuals of Tachanovsky's gudgeon Ladislavia taczanowskii have been determined on the basis of Sanger dideoxy sequencing. The gene compositions of two genomes contain 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes, and 1 control region with the same length 16,614 bp. The phylogenetic tree reveals that the monotypic genus Ladislavia is a sister group of the subfamily Gobioninae within the family Gobionidae.

Complete mitochondrial genome of freshwater fish, Microphysogobio jeoni (Actinopterygii, Cypriniformes, Cyprinidae), from South Korea.

In this study, we determined the complete mitochondrial genome sequences of cyprinid freshwater fish, Microphysogobio jeoni, belonging to the subfamily Gobioninae in the order Cypriniformes. The complete mitogenome of M. jeoni was 16,602 bp in length and consisted of 13 protein-coding genes (PCGs), 22 tRNAs, and two rRNAs. The gene order was identical with other Microphysogobio species. The overall nucleotide composition of M. jeoni was A + T: 56.1% and G + C: 43.9%, with slightly AT bias. In the phylogenetic tree, M. jeoni and other congeneric species clearly formed a monophyletic clade, and each species distinguished against each other well.

Seasonal variations in food resource partitioning among four sympatric gudgeon species in the upper Yangtze River.

Knowledge of food resource partitioning among sympatric fish species is crucial for understanding the potential mechanisms of species coexistence. Gudgeons (Teleostei: Cyprinidae: Gobioninae) often dominate fish assemblages in the upper Yangtze River. However, little research has been conducted on their trophic interactions. In this paper, seasonal diet and feeding strategy variations of four sympatric gudgeon species, Coreius guichenoti, Coreius heterodon, Rhinogobio ventralis, and Rhinogobio cylindricus, were investigated by analysis of intestinal tract contents, aiming to explore whether food resource partitioning occurred among them. Fish specimens were collected during spring (April-May) and autumn (August-October) in 2010 in Hejiang, a free-flowing stretch of the upper Yangtze River. Coreius guichenoti, C. heterodon, and R. cylindricus showed omnivorous feeding habits, while R. ventralis exhibited an obligate carnivore feeding habit. Diet overlap among the four studied species was high, especially in spring. However, changes in feeding strategies were observed in autumn. Specifically, C. guichenoti and R. cylindricus expanded their dietary niche breadth and consumed detritus, Sinopotamidae or Hydropsychidae as important complementary food resources. In contrast, C. heterodon and R. ventralis reduced their dietary niche breadth and became more specialized on mussels (Limnoperna lacustris). These results confirmed that sympatric fish species can coexist with high diet overlap, and food resource partitioning among these species may also fluctuate with the seasons.

Infection Status with Clonorchis sinensis Metacercariae in Fish from Yangcheon (Stream) in Sancheong-gun, Gyeongsangnam-do, Korea.

The infection status with Clonorchis sinensis metacercariae (CsMc) was examined in freshwater fishes from Yangcheon (a branch of Gyeongho-gang), which is located in Sancheong-gun, Gyeongsangnam-do, the Republic of Korea. Total 2,201 fishes in 26 species were examined by the artificial digestion method through 7 years. CsMc were detected in 1,171 (53.2%) fishes in 21 spp. (80.8%) and their density was 85 per fish infected. Total 532 (99.6%) out of 534 Pungtungia herzi (index fish) examined were infected with 147 CsMc per fish infected. Metacercarial densities in this fish were highest in 2015 (179 CsMc), followed by 2012 (168), 2013 (152), 2016 (145), 2014 (114), and 2017 (89) respectively. In the gobioninid fish group, i.e., P. herzi, Sarcocheilichthys spp., Squalidus spp., Pseudogobio esocinus, Hemibarbus longirostris, and Hemibarbus labeo, 841 (92.7%) fishes were infected with 117 CsMc per fish infected. Total 250 (54.7%) acheilognathinid fish (bitterlings), Acheilognathus spp. and Acanthorhodeus spp. were infected with 5.8 CsMc. In the rasborinid fish (chubs) group, i.e., Zacco platypus, Zacco temminckii, and Zacco koreanus, 77 (13.7%) out of 563 fish examined were infected with 2.4 CsMc in average. The susceptibility indices of CsMc were 49.09 in the overall positive fish group, 104.15 in the gobioninid group, 3.17 in the acheilognathinid group and 0.35 in the rasborinid fish group respectively. Only 1 CsMc was detected in 3 fish species, Coreoperca herzi, Channa argus, and Lepomis macrochirus, respectively. Conclusively, it was confirmed that CsMc are moderately prevalent in fishes from Yangcheon in Sancheon-gun, Gyeongsangnam-do, Korea.

Three complete mitochondrial genomes of freshwater fishes in the genus Abbottina (Cypriniformes: Gobionidae).

Abbottina binhi has been misidentified as Abbottina rivularis in China for a long time. In this study, we determined three mitochondrial genomes of A. rivularis and A. binhi such that these data should contribute to molecular identifications of the two species. The size of new mitochondrial genomes was 16,609 or 16,599 bp with A + T bias of 55.7-56.5% in the base compositions. Our reconstructed phylogeny showed that A. rivularis and A. binhi formed a sister taxon relationship, and they together were a monophyletic group.

The complete mitochondrial genome of Pseudorasbora interrupta and phylogeny of Pseudorasbora.

We sequenced the mitochondrial genome of Pseudorasbora interrupta using Illumina technology and additional Sanger sequencing. The assembled 16601 bp mitogenome had a GC content of 40.98% and consisted of 13 protein-coding genes, 22 tRNA genes, two rRNA genes, and one non-coding control region (CR), with a gene order identical to the fishes. In addition, we downloaded the mitogenome of the closely related species Topmouth Gudgeon P. parva. The mitogenomes of P. interrupta and P. parva showed a sequence identity of 99.2% with the previously published P. parva mitogenome. The phylogenetic reconstruction based on 14 Gobioninae mitogenomes supported P. interrupta and its sister species P. parva as a monophyletic group. However, Pseudorasbora was proved to be a polyphyletic group which means amendments will be needed for the taxonomy of this genus.

Prevalence and Intensity of Clonorchis sinensis Metacercariae in Freshwater Fish from Wicheon Stream in Gunwi-gun, Gyeongsangbuk-do, Korea.

The infection status of Clonorchis sinensis metacercariae (CsMc) was examined in freshwater fish from a highly prevalent site, Wicheon (a branch of Nakdong-gang), which is located in Gunwi-gun, Gyeongsangbuk-do, the Republic of Korea. Total 1,162 fish in 32 species were examined by the artificial digestion method through 6 years. CsMc were detected in 720 (67.5%) out of 1,067 fish (26 spp.) and their density was 610 per fish infected. In the susceptible gobioninid fish group, i.e., Pungtungia herzi, Squalidus gracilis majimae, Squalidus japonicus coreanus, Sarcocheilichthys variegatus wakiyae and Pseudorasbora parva, all of 323 fish were infected with an average of 1,310 CsMc. Total 23 (95.8%) gobioninid fish, i.e., Pseudogobio esocinus, Abbottina springeri, Hemibarbus longirostris, Microphysogobio koreensis, and Microphysogobio jeoni, were infected with 127 CsMc in average. In the acheilognathinid fish (bitterlings) group, the prevalence was 77.0%, and the density was 50 CsMc per fish infected. In the rasborinid fish (chubs) group, i.e., Zacco platypus, Zacco temminckii, Zacco koreanus, and Opsariichthys uncirostris amurensis, 147 (36.5%) out of 403 fish examined were infected with 15 CsMc in average. The susceptibility indices of CsMc were 412 in the overall positive fish group, 1,310 in the gobioninid group-1, 122 in the gobioninid group-2, 38.5 in the acheilognathinid group, and 5.5 in the rasborinid fish group. Conclusively, it was confirmed that CsMc are highly prevalent in fish from Wicheon, and their infection tendency varied according to the subfamily groups in Cyprinidae fish hosts.

Ten fish mitogenomes of the tribe Gobionini (Cypriniformes: Cyprinidae: Gobioninae).

Freshwater fishes of the subfamily Gobioninae (Cypriniformes: Cyprinidae) are composed of three major clades, the tribes Gobionini and Sarcocheilichthyini, and a Hemibarbus-Squalidus group. In this study, we determined ten complete fish mitogenomes from eight of all twelve genera in the tribe Gobionini. The ten mitogenomes displayed similar patterns in gene arrangements, codon use and gene overlaps with the length of 16,605-16,617 bp and base compositions slightly A + T bias of 56.1-58.0%. Our phylogeny of the tribe Gobionini revealed that the genera Gobio, Xenophysogobio, Gobiobotia, Saurogobio and Pseudogobio were monophyletic, and other genera Abbottina, Biwia, Microphysogobio and Platysmacheilus were paraphyletic or polyphyletic. The findings indicate that the genera classifications of Gobionini are needed to be further confirmed.

Complete mitochondrial genome of the Korean oily shinner Sarcocheilichthys nigripinnis morii (Cypriniformes, cyprinidae): mitogenome characterization and phylogenetic analysis.

The Korean oily shinner (Sarcocheilichthys nigripinnis morii) is a subspecies belonging to the subfamily Gobioninae in the family Cyprinidae and is endemic to Korea. Herein, we report the first sequencing and assembly of the complete mitochondrial genome of S. nigripinnis morii. The complete mitochondrial genome is 16,679 bp long, consisting of 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes, and a control region. It has the typical vertebrate mitochondrial gene arrangement. Phylogenetic analysis using mitogenomes of 16 species showed that S. nigripinnis morii was clustered with S. nigripinnis and S. variegatus microoculus and grouped with the other Cyprinidae species.

The complete mitochondrial genome of Fujian rod gugeon Microphysogobio fukienensis (Nichols) (Cypriniformes, Cyprinidae).

In this study, the complete mitogenome sequence of the Fujian rod gugeon, Microphysogobio fukienensis (Nichols) (Cypriniformes, Cyprinidae, Gobioninae) has been amplified. The mitogenome, consisting of 16,600 bp, had the typical vertebrate mitochondrial gene arrangement, including 13 protein-coding genes, 22 transfer RNAs, 2 ribosomal RNAs genes and a noncoding control region (CR). CR of 930 bp length is located between tRNA(Pro) and tRNA(Phe). The overall base composition of M. fukienensis is 31.0% for A, 26.0% for C, 26.6% for T and 16.4% for G, with higher AT content of 57.0%. The complete mitogenome may provide rather essential and important DNA molecular data for further phylogenetic analysis for not only congeneric species but also higher different taxa of Cyprinid fishes.

The complete mitochondrial genome of Chinese rod gugeon Abbottina rivularis (Cypriniformes, Cyprinidae).

In this study, the complete mitogenome sequence of the Chinese rod gugeon, Abbottina rivularis (Basilewsky, 1855) has been amplified. The mitogenome, consisting of 16,608 base pairs (bp), had the typical vertebrate mitochondrial gene arrangement, including 13 protein-coding genes, 22 transfer RNAs, 2 ribosomal RNAs genes and a noncoding control region (CR). CR of 929 bp length is located between tRNA(Pro) and tRNA(Phe). The overall base composition of A. rivularis is 29.9% for A, 27.2% for C, 25.7% for T and 17.3% for G, with higher AT content of 55.6%. The complete mitogenome may provide rather essential and important DNA molecular data for further phylogenetic analysis for not only congeneric species but also higher different taxa of Cyprinid fishes.

The complete mitochondrial genome of small sliver gugeon Squalidus gracilis (Teleostei, Cyprinidae).

In this study, the complete mitogenome sequence of small silver gugeon Squalidus gracilis has been amplified. The mitogenome, consisting of 16,605 base pairs (bp), had the typical vertebrate mitochondrial gene arrangement, including 13 protein-coding genes, 22 transfer RNAs, 2 ribosomal RNAs genes and a non-coding control region (CR). CR of 928 bp length is located between tRNA(Pro) and tRNA(Phe). The overall base composition of S. gracilis is 29.8% for A, 27.6% for C, 25.7% for T and 16.9% for G, with higher AT content of 55.5%. The complete mitogenome may provide rather essential and important DNA molecular data for further phylogenetic analysis for not only congeneric species but also higher different taxa of Cyprinid fishes.

Complete mitochondrial genome of the Chinese lizard gudgeon, Saurogobio dabryi (Teleostei: Cypriniformes: Cyprinidae).

The Chinese lizard gudgeon, Saurogobio dabryi Bleeker, belongs to the subfamily Gobioninea, which is an economic fish widely distributed in East Asia. In this study, we sequenced the complete mitochondrial genome of the S. dabryi. The complete mitogenome was 16,601 bp in size, consisting of 13 protein-coding genes, 22 transfer RNA (tRNA) genes, 2 ribosomal RNA (rRNA) genes and 1 control region. It has the typical circular molecule structure of vertebrate's mitochondrial genome. The whole base composition was estimated to be 29.64%A, 26.47%T, 27.06%C and 16.83%G with AT bias of 56.11%. This study is a first report the complete mitogenome of S. dabryi and provides the basis for preservation of genetic resources and phylogenetic analyses on this species.

Complete mitochondrial genome of Pseudorasbora elongata (Cypriniformes: Cyprinidae).

Phylogenetic placement of Pseudorasbora elongate remains unresolved. We determined the first complete mitochondrial genome of P. elongate that its mitogenome data should contribute to clarify the systematics of Pseudorasbora fishes. The mitogenome was 16,607 bp in length, including 13 typical protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes and 1 control region. The overall base composition of the heavy strain was 31.1% for A, 24.8% for C, 28.2% for T and 15.9% for G, with the A + T bias of 59.3%.

Complete mitochondrial genome sequence of a Korean Pungtungia herzi (Cypriniformes, Gobioninae).

The mtDNA sequence of Pungtungia herzi in Korea comprises 16,599 nt and contains 37 genes (13 protein-coding genes, 2 rRNAs and 22 tRNAs). The content and the arrangement of the genome of the Korean specimen were identical to that previously reported for a Japanese specimen, with 98.3% genetic similarity between the two complete mitogenomes. The pairwise distances of three complete mitogenomes obtained among Pungtungia herzi and Pseudopongtungia nigra. Pungtungia herzi and Pseudopongtungia tenuicorpa, and Pungtungia nigra and Pseudopongtungia tenuicorpa were 9.26%, 12.88% and 12.75%, respectively.