Gastric nematodes can cause severe diarrheal diseases of waterfowl and threaten waterfowl health and productivity. The immune response mechanism of the host against this parasite is unclear. We investigated the transcriptomic changes, immune related pathways and adaptive molecular responses in infected ducks. RNA sequencing of the gastric tissues of infected and control ducks was followed by differential expression using DESeq2, and functional enrichment and protein-protein interaction networks were constructed. There were 1983 differentially expressed genes (DEGs), including 1317 upregulated genes and 666 downregulated genes. GO and KEGG analyses showed considerable enrichment in immune response, extracellular matrix organization, and chemotaxis and cytokine-mediated signaling pathways, suggesting systemic immune activation and tissue remodeling. The protein-protein interaction network indicated several hub genes that might be central to host defense. Validation by RT-qPCR showed consistent expression trends for some DEGs. These results systematically outline the transcriptomic landscape of ducks infected with Eustrongylides tubifex, offering new insights into host-parasite interactions and immune modulation. The results enhance our understanding of anti-helminth immunity in waterfowl and may inform strategies for disease control in poultry production.

The emergence and spread of antibiotic resistance genes (ARGs) mediated by mobile genetic elements (MGEs) pose a significant threat to public and environmental health. While aquaculture ecosystems are recognised as critical reservoirs for ARGs, the genomic architecture of MGEs that facilitate resistance dissemination in aquatic pathogens - particularly Aeromonas veronii (A. veronii) - remains underexplored. This study isolated a highly virulent, multidrug-resistant strain of A. veronii (Y6) from diseased largemouth bass, underscoring its potential dual threat to aquaculture and public health. Whole-genome sequencing revealed that strain Y6 harbours a chromosomal genomic island, GI22, containing a integron 1, which encodes 15 ARGs. Embedded within this island is a novel composite transposon, TnY6-1, which carries five of these ARGs and has the potential to facilitate horizontal gene transfer. Phylogenetic analysis revealed that strain Y6 clusters closely with human clinical isolates, underscoring its zoonotic potential. Comparative genomic analysis revealed that the resistance gene cassettes in integron 1 of strain Y6 are highly conserved across fish, human, and environmental isolates, suggesting the possibility of ARG transmission between different ecosystems. To quantify the environmental threat posed by TnY6-1, we applied a multidimensional risk assessment framework adapted from the PIPdb database. This marks the first classification of TnY6-1 as a Level IV high-risk MGE. These findings highlight the importance of implementing risk-based surveillance systems targeting hazardous MGEs in aquaculture to reduce the environmental-to-clinical spillover of antimicrobial resistance.

The subfamily Schizopygopsinae (Cyprinidae), endemic to high-altitude Asian ecosystems, is widely used as a model for studying adaptive evolution, owing to specialized hypoxia tolerance and reduced squamation in high-altitude environments. Despite advances in mitochondrial genomics, comprehensive analyses of conserved genomic features and phylogenetic relationships within this subfamily remain limited. Herein, we sequenced and annotated the mitochondrial genome of Diptychus maculatus Steindachner, 1866 (16 764 bp; GenBank: ON872378) and comparatively analyzed the mitogenomes across 56 Cyprinidae species, including 33 Schizopygopsinae members, 21 Schizothoracinae members and two Leuciscinae outgroups (Leuciscus baicalensis, Rutilus rutilus). The mitochondrial genome of D. maculatus exhibited conserved teleost features, including 13 protein-coding genes (PCGs), 22 tRNAs, and 2 rRNAs. Its gene order and strand distribution align with those of related taxa. Notable AT bias (54.3%) and negative GC skew (−0.163) were observed, consistent with mutation-driven thymine accumulation in PCGs. Codon usage analysis revealed a preference for A/T-ending codons, with lineage-specific reductions in relative synonymous codon usage in Diptychus. Phylogenetic reconstructions using Bayesian and maximum likelihood methods resolved Schizopygopsinae and Schizothoracinae into two primary clades, supporting their monophyly but revealing paraphyly in genera Schizothorax and Gymnocypris, which are likely due to rapid radiation and ecological diversification. The placement of D. maculatus as sister to Gymnodiptychus underscores shared adaptations to plateau environments. Our findings highlight conserved mitogenomic architecture shaped by mutation pressure and selection, while phylogenetic discordance with morphology-based classifications emphasizes the need for integrative taxonomic approaches. This study provides critical genomic insights into the evolutionary mechanisms driving high-altitude adaptation and diversification in Schizopygopsinae and offers a foundation for future research on Cyprinidae biogeography and speciation.

Codon usage bias (CUB) is a universal feature in both mitochondrial and ribosomal genes, shaped by the combined forces of mutation and selection, and serves as a valuable indicator of evolutionary processes and phylogenetic signals. However, comprehensive analysis of CUB is lacking in the Leuciscinae family. We sequenced and annotated the complete mitochondrial genome of Abramis brama orientalis and examined codon usage patterns in all Leuciscinae species, subsequently finding the dominant evolutionary forces and phylogenetic relationships. We performed a PR2 bias plot, neutrality plot, effective number of codons (ENC) vs. GC3, relative synonymous codon use (RSCU) clustering and Ka/Ks calculations for 22 Leuciscinae species. We constructed the phylogenetic trees of Leuciscinae using Bayesian inference and maximum likelihood on concatenated mitochondrial sequences. The complete mitochondrial genome of Abramis brama orientalis was 16,607 bp, with typical vertebrate structure and high A + T bias. The codons of protein-coding genes in Leuciscinae have a preference for ending in A/C. All protein-coding genes were under strong purifying selection (Ka/Ks < 1). RSCU patterns and phylogenetic analyses showed two lines of Leuciscinae in the RSCU, with A. brama orientalis being a monophyletic group with A. brama. The results demonstrate the strong role for selection in shaping mitochondrial codon usage in Leuciscinae, despite mutational biases. The study clarified the taxonomic status of A. brama orientalis and provided a framework for understanding molecular evolution in this ecologically important freshwater fish family.

Codon usage bias (CUB) is a common phenomenon reported among many species and genes, but its unique characteristics in the mitochondrial genome of class Monopisthocotyla remain unknown. The complete mitochondrial genome of Dactylogyrus wunderi was sequenced and characterized, and the mitochondrial genome compositions and CUB of six Dactylogyrus species and 35 Monopisthocotyla species were analyzed using bioinformatics methods. The mitochondrial genome of D. wunderi is a typical circular structure in length of 14,920 bp. The A + T contents of the six Dactylogyrus species (58.4

Monogeneans of the genus Dactylogyrus Diesing, 1850, the largest genus in the family Dactylogyridae, mostly parasitize the gills of cyprinoid hosts; however, only 3 Dactylogyrus' mitochondrial genomes (mitogenomes) are studied so far. The aim of this research is to extend our understanding of the mitogenomes of Dactylogyrus. We sequenced the mitogenomes of D. crucifer and D. zandti isolated from Rutilus rutilus and Abramis brama orientalis in northwest China, and then we compared these mitogenomes with other monogeneans. We used Illumina NovaSeq to sequence the entire mitochondrial genomes of D. crucifer and D. zandti and characterized the mitogenomes to understand the gene structure, Gene identity, the secondary structures of the 22 tRNA genes, and relative synonymous codon usage. We used the analytic Bayesian Information and Maximum Likelihood methods to determine their associated phylogenetic trees. The mitogenomes of D. crucifer and D. zandti were 14,403 and 18,584 bp, respectively. Organization and positioning of these genes were in accordance with Dactylogyrus lamellatus and Dactylogyrus tuba. The nucleotide composition of Dactylogyridae was different from other families of Monogenea, and the A+T count of genus Dactylogyrus (54 - 58.4 %) was lower than other genus species of the family Dactylogyridea (63.9 - 78.4 %) in protein-coding genes. Dactylogyrus members displayed a codon usage bias. The relative synonymous codon used by Dactylogyrus was not conserved and was lower than other monogeneans. The codon use patterns of closely-related species isolated from closely-related hosts were identical. Phylogenetic analyses using mitogenomic dataset produced Dactylogyrus isolated from host subfamily Leuciscinae formed a sister-group. Our results contributed significantly to an increased database of mitogenomes, more than 50%, for Dactylogyrus that may help future studies of mitochondrial genes and codon uses for the analysis of monogenean phylogenetics.

Cyprinidae is the largest family in the order of freshwater fish Cypriniformes. Increased subfamily members of Cyprinidae have been suggested to be re-classified for decades. In this study, we sequenced the mitochondrial genomes (mitogenomes) of Leuciscus baicalensis and Rutilus rutilus collected from northwest China and compared with other closely related species to determine their associated family or subfamily. We used Illumina NovaSeq to sequence the entire mitochondrial genomes of Leuciscus baicalensis and Rutilus rutilus and characterized the mitogenomes by the gene structure, gene order, and the secondary structures of the 22 tRNA genes. We compared mitogenome features of Leuciscinae with other subfamilies in Cyprinidae. We used the analytic Bayesian Information and Maximum Likelihood methods to determine phylogenetic trees of 13 PCGs. The mitogenomes of Leuciscus baicalensis and Rutilus rutilus were 16,607 bp and 16,606 bp, respectively. Organization and location of these genes were consistent with already studied Leuciscinae fishes. Synonymous codon usage was conservative in Leuciscinae as compared with other subfamilies in Cyprinidae. Phylogenetic analysis indicated that Leuciscinae was a monophyletic group, and genus Leuciscus was a paraphyletic group. Our approach, for the first time, of studying comparative mitochondrial genomics and phylogenetics together provided a supportive platform to the analysis of population genetics and phylogeny for Leuciscinae. Our results indicated a promising potential of comparative mitochondrial genomics in the manifestation of phylogenetic relationships between fishes, leading us to a suggestion that mitogenomes should be routinely considered in clarifying phylogenetics of family and subfamily members of fish.

Background Unresolved taxonomic classification and paraphyly pervade the flatworm class Monogenea: the class itself may be paraphyletic and split into Polyopisthocotylea and Monopisthocotylea; there are some indications that the monopisthocotylean order Dactylogyridea may also be paraphyletic; single-gene markers and some morphological traits indicate that the family Ancyrocephalidae is paraphyletic and intertwined with the family Dactylogyridae. Methods To attempt to study the relationships of Ancyrocephalidae and Monopisthocotylea using a phylogenetic marker with high resolution, we sequenced mitochondrial genomes of two fish ectoparasites from the family Dactylogyridae: Dactylogyrus simplex and Dactylogyrus tuba . We conducted phylogenetic analyses using three datasets and three methods. Datasets were ITS1 (nuclear) and nucleotide and amino acid sequences of almost complete mitogenomes of almost all available Monopisthocotylea mitogenomes. Methods were maximum likelihood (IQ-TREE), Bayesian inference (MrBayes) and CAT-GTR (PhyloBayes). Results Both mitogenomes exhibited the ancestral gene order for Neodermata, and both were compact, with few and small intergenic regions and many and large overlaps. Gene sequences were remarkably divergent for nominally congeneric species, with only trnI exhibiting an identity value > 80%. Both mitogenomes had exceptionally low A + T base content and AT skews. We found evidence of pervasive compositional heterogeneity in the dataset and indications that base composition biases cause phylogenetic artefacts. All six mitogenomic analyses produced unique topologies, but all nine analyses produced topologies that rendered Ancyrocephalidae deeply paraphyletic. Mitogenomic data consistently resolved the order Capsalidea as nested within the Dactylogyridea. Conclusions The analyses indicate that taxonomic revisions are needed for multiple Polyopisthocotylea lineages, from genera to orders. In combination with previous findings, these results offer conclusive evidence that Ancyrocephalidae is a paraphyletic taxon. The most parsimonious solution to resolve this is to create a catch-all Dactylogyridae sensu lato clade comprising the current Ancyrocephalidae, Ancylodiscoididae, Pseudodactylogyridae and Dactylogyridae families, but the revision needs to be confirmed by another marker with a sufficient resolution. Graphical Abstract

Yili River system hosts a diverse fauna of fishes and parasites. Gymnodiptychus dybowskii is a rare and endangered aboriginal cold-water fish inhabit in the Yili river system. Our research identified a new species Gyrodactylus gymnodiptychi n. sp. isolated from G. dybowskii in the Kunes River (Yili River, China). Morphological comparison revealed identifiable differences between the new species and other parasites, including Gyrodactylus aksuensis, and Gyrodactylus tokobaevi, which are two known parasites living in G. dybowskii inhabit in the Aksu River west of Frunze (Kyrgyzstan), as well as Gyrodactylus montanus living in Shizothorax intermedius inhabited in the Tadzhikistan or Uzbekistan. Especially, the dorsal bar of G. gymnodiptychi n. sp. was raised at both ends with a hollow, and its hamulus roots were curved inward. The BLASTN search of GenBank did not detect any other ITS1-5.8S-ITS2 rDNA sequences same as G. gymnodiptychi's. Using the Bayesian Information and Maximum Likelihood methods to analyze the ITS1-5.8S-ITS2 rDNA gene sequences, we constructed phylogenetic trees for G. gymnodiptychi n. sp. Accordingly, our morphological and molecular research indicated that G. gymnodiptychi n. sp. was not only a new species of parasites but also the first Gyrodactylus member identified in the Yili River in China.

为了探明叶尔羌河流域长身高原鳅(Triplophysa tenuis)体内寄生线虫(Nematodes)的感染情况及分布类型,于2019年5月-2020年7月对叶尔羌河长身高原鳅进行3次采样,通过运用统计学方法对长身高原鳅感染线虫情况和分布类型进行分析.结果显示:在捕获的414尾长身高原鳅中共检出2种线虫,分别为杆咽线虫(Rhabdo-chona sp.)、鲁道夫对盲囊线虫(Contracaecum rudolphii),其中杆咽线虫为优势虫种;线虫的总感染率为53.38％,平均感染丰度为7.00±0.99,平均感染强度为13.10±0.56;杆咽线虫和鲁道夫对盲囊线虫平均感染丰度均随着长身高原鳅体长增加而增大,在大于14 cm体长组取得最大值;不同体长段宿主中,杆咽线虫感染强度差异性极显著,鲁道夫对盲囊线虫感染强度差异性不显著;两种线虫在宿主种群中的分布类型均为聚集型分布.

2019年5月至2020年7月期间,运用形态学和分子生物学方法对叶尔羌河流域(塔县河段)塔里木裂腹鱼肠道内寄生的2种线虫进行种类鉴定及系统发育分析.结果显示,采集到的线虫据其形态数据可初步鉴定为杆咽属和对盲囊属,用PCR扩增的受检样本JG1、JG2的CO Ⅰ mtDNA序列与GenBank中已知的Rhabdochona salgadoi的同源性最高,为89.9％;用PCR扩增的受检样本JD1、JD2的ITS1 rDNA序列与鲁道夫对盲囊线虫B的同源性最高,为99.27％;鉴定结果表明,塔里木裂腹鱼上寄生的2种线虫为杆咽线虫未定种和鲁道夫对盲囊线虫;利用最大似然法和贝叶斯法分别构建了 2种线虫的分子系统发育关系,并进行分析,其中杆咽属线虫的不同种类均能形成一个单系,CO Ⅰ mtDNA序列能很好地作为分子标记对其进行分析,但由于目前公布的杆咽属线虫分子数据较少,尚需要很多数据有待补充;待测对盲囊属线虫(Contracaecum(s.l))与来自波兰、中国、意大利等地区的鲁道夫对盲囊线虫聚为一支,系统发育结果很好地佐证了该线虫为鲁道夫对盲囊线虫.这些实验结果也为杆咽属线虫和对盲囊属线虫的系统发育进化研究补充了相关资料.

Background: Diplozoidae are monogenean (Monogenea: Polyopisthocotylea) fish parasites characterised by a unique life history: two larvae permanently fuse into an X-shaped "Siamese" organism. Taxonomy and phylogeny of Diplozoidae and Polyopisthocotylea remain unresolved due to the unavailability of molecular markers with sufficiently high resolution. Mitogenomes may be a suitable candidate, but there are currently only 12 available for the Polyopisthocotylea (three for Diplozoidae). The only available study of diplozoid mitogenomes found unique base composition patterns and elevated evolution rates in comparison with other Monogenean mitogenomes. Methods: To further explore their evolution and generate molecular data for evolutionary studies, we sequenced the complete mitogenomes of two Diplozoidae species, Paradiplozoon homoion and Paradiplozoon yarkandense, and conducted a number of comparative mitogenomic analyses with other polyopisthocotyleans. Results: We found further evidence that mitogenomes of Diplozoidae evolve at a unique, elevated rate, which was reflected in their exceptionally long branches, large sizes, unique base composition, skews, and very low gene sequence similarity levels between the two newly sequenced species. They also exhibited remarkably large overlaps between some genes. Phylogenetic analysis of Polyopisthocotylea resolved all major taxa as monophyletic, and Mazocraeidea was split into two major clades: (Diplozoidae) + (all four remaining families: Diclidophoridae, Chauhaneidae, Mazocraeidae and Microcotylidae). It also provided further confirmation that the genus Paradiplozoon is paraphyletic and requires a taxonomic revision, so the two species may have to be renamed Indodiplozoon homoion and Diplozoon yarkandense comb. nov. Conclusions: Although our findings indicate that mitogenomes may be a promising tool for resolving the phylogeny of Polyopisthocotylea, elevated evolutionary rates of Diplozoidae may cause phylogenetic artefacts, so future studies should pay caution to this problem. Furthermore, as the reason for their elevated evolution remains unknown, Diplozoidae are a remarkably interesting lineage for other types of evolutionary mitogenomic studies.

研究贝加尔雅罗鱼(Leuciscus baicalensis)感染的单殖吸虫的群落多样性及感染情况,为额尔齐斯河鱼类寄生虫病防治提供基础资料.2009年8月到2016年7月,剖检贝加尔雅罗鱼296尾,共感染了6种单殖吸虫,分别为号筒指环虫(Dactylogyrus tuba Linstow,1878)、双髻指环虫(D.sphyra Linstow,1878)、小刺指环虫(D.mic-racanthus Nybelin,1937)、多小枝指环虫(D.ramulosus Malewitzkaja,1941)、普氏三代虫(Gyrodactylus prostate Erergns,1963)和斯氏拟双身虫(Paradiplozoon skrjabini Achmerov,1974);贝加尔雅罗鱼单殖吸虫的总感染率为20.27％,平均感染强度为3.05只/尾(1～18只/尾),平均感染丰度为(0.62±2)只/尾;混合感染率相对较低,仅占2.36％;各单殖吸虫的感染率均小于10％,平均感染强度均小于5只/尾,其中小刺指环虫为优势种;在5个体长段中,14 cm≤L＜16 cm体长段感染单殖吸虫的种类、感染率及感染强度均达到最高;体长段之间的多样性指数、优势度指数、均匀度指数及丰富度指数结果相差不大,不同体长段宿主中单殖吸虫种群的分布类型均为聚集分布;体长段14 cm≤L＜16 cm与L≥16 cm感染强度差异显著,其余体长段之间的感染强度差异均不显著.

2018年9月至2019年10月,对新疆乌鲁木齐市区及巴楚县的鱼类进行寄生虫病原调查过程中,在斑点叉尾鮰(Ictaluruspunctatus)和云斑鮰(I nebulosus)鳃部发现有单殖吸虫寄生,两种鱼所寄生的虫种形态基本一致,仅连接片形态稍有差异,通过形态学鉴定为锚首虫科(Ancyrocephalidae)趋鮰虫属(Ligictaluridus)的普氏趋鮰虫(L.pricei).为验证形态鉴定的准确性,扩增了寄生虫的28S rDNA序列,并进行了系统发育分析.结果显示,两种鱼所寄生的单殖吸虫与普氏趋鮰虫的相似度均达98％以上,在系统进化树中紧密聚为一支,置信度均为100;同时,两种虫与普氏趋鮰虫间的遗传距离数值接近于零,表现出了很高的相似度和亲缘关系.因此根据形态特征和系统发育分析,确定这两种鱼感染的是同一种寄生虫.研究结果可为新疆人工养殖鮰科鱼类的病害防治提供依据.

Adult specimens of Pomphorhynchus fuhaiensis were identified from common carp (Cyprinus carpio L.) in Ulungur Lake of northwest China, and acanthors, acanthellae, cystacanths dissected from Gammarus lacustris in a small tributary of Ulungur River for the first time. The acanthocephalans were also found in crucian carp (Carassius carassius L.), tench (Tinca tinca L.), oriental bream (Abramis brama orientalis Berg), and ide (Leuciscus idus L.) in the lake. This species is distinguished from other species in Pomphorhynchus by its large, spherical bulb and very long neck as well as by a cylindrical proboscis armed with 15-17 longitudinal rows of 9-12 hooks each. The anterior proboscis hooks are almost uniform in size and shape, the sixth hook in a short row and the seventh hook in long row decrease abruptly in size posteriorly with the last end hook being a little larger than the prebasal hook, and in a ring; posterior proboscis hooks much more widely spaced. Furthermore, the lemnisci are claviform. The mean neck:trunk ratio is about 0.5, which is larger than most other species in Pomphorhynchus. Females are larger than males. In males, the testes are in one-third to one-half of the trunk, equal, ovoid-spheroid, usually contiguous, and small relative to the body size, and there are 6 ovoid cement glands. Pomphorhynchus fuhaiensis is similar to Pomphorhynchus laevis but can be distinguished by the number of longitudinal rows of hooks. Pomphorhynchus laevis is armed with 18-20 longitudinal rows of 11-13 hooks, P. fuhaiensis is armed with 15-17 longitudinal rows of 9-12 hooks.

本试验对阿勒泰地区的富蕴县、福海县、哈巴河县、清河县4个地区马血样(n =2697)进行马梨形虫病感染情况调查.结果 显示:马梨形虫病感染率为18.69％ (504/2697);其中,马泰勒虫感染率为9.12％ (246/2697),马驽巴贝斯虫感染率为10.05％ (271/2697),混合感染0.48％(13/2697).4个地区马梨形虫感染率分别为哈巴河县30.80％(158/513)、清河县19.10％(114/597)、富蕴县17.86％(135/756)、福海县11.60％(97/831),差异显著(P＜0.05);不同年龄段马梨形虫感染情况显著差异(P＜0.05);春季感染明显高于秋季感染,差异显著(P＜0.05).此数据可补充阿勒泰地区马梨形虫病的区域性流行病学数据.

建立多房棘球绦虫粪抗原双抗体夹心ELISA检测方法,为犬感染多房棘球绦虫的早期诊断提供技术支撑.以5E10H5杂交瘤细胞株腹腔接种Balb/c鼠制备的腹水作为包被抗体,多房棘球绦虫成虫可溶性抗原免疫新西兰大白兔制备的多克隆抗体血清作为检测抗体,HRP标记的驴抗兔IgG作为二抗,建立双抗体夹心ELISA方法,检测试验犬(感染多房棘球绦虫)和阴性对照犬犬粪.结果显示,多房棘球绦虫成虫可溶性抗原具有良好的抗原性并能产生高效价抗体;对该方法的灵敏度进行检测,阳性粪样稀释至1:10000时仍显示为阳性;在感染动态分析中,该方法最早可在犬感染72 h后,最迟6 d后检测到多房棘球绦虫粪抗原.表明建立的方法可用于诊断犬多房棘球绦虫感染,为后期研制犬多房棘球绦虫粪抗原双抗体夹心ELISA检测试剂盒奠定了基础.

2019年对新疆伊犁河流域巩乃斯河段鱼类进行寄生虫病原调查过程中发现,在新疆裸重唇鱼(Gymnodipty-chus dybowskii)体表有三代虫寄生,经形态学特征及分子生物学鉴定确定为同一种三代虫,定为新种(暂未公布).为了解该三代虫在新疆裸重唇鱼鳍条上的寄生特点,运用统计学方法对新疆裸重唇鱼鳍条寄生三代虫的感染情况及空间分布特点进行分析.结果显示:在检查的69尾新疆裸重唇鱼中,共检出459只同种三代虫,总感染率和平均感染丰度分别为91.3％和(6.65±5.24);统计三代虫在各个鳍条的感染率,腹鳍的感染率最高为78％,尾鳍感染率最低为41％,在宿主胸鳍与尾鳍之间的感染强度差异显著;三代虫随着宿主体长的增大,其感染率、感染丰度和强度逐渐上升,在14～19 cm体长组达到最高,不同大小的宿主其感染强度之间差异显著.结果表明,新疆裸重唇鱼寄生三代虫对宿主体长及鳍条具有一定的选择偏好性,更偏好寄生于体长14～19 cm的宿主的胸鳍.三代虫在宿主种群中的分布类型为聚集分布和均匀分布.

2018年11月至2019年5月,在乌鲁木齐市周边市场及养殖场进行鱼类寄生虫调查过程中发现,不同地域的罗非鱼鳃部有大量锚首虫寄生,经染色观察,对后吸器及交接器等结构进行绘图、测量,同时选用28S、18S-ITS1-5.8S和COⅠ3个分子标记进行扩增、克隆和序列测定,利用核糖体RNA与相关物种进行系统发育分析.研究结果显示,形态学结果可初步鉴定,该虫体为锚首虫亚科嗜丽鱼虫属的几丁嗜丽鱼虫和彼丽嗜丽鱼虫.扩增得到几丁嗜丽鱼虫的28S、18S-ITS1-5.8S及COⅠ序列长度分别为863、1019 bp和592 bp,与GenBank中已发表的几丁嗜丽鱼虫的相似性均超99.5％;扩增得到彼丽嗜丽鱼虫的28S、18S-ITS1-5.8S及COⅠ序列长度分别为863、1005 bp和572 bp,与GenBank中的彼丽嗜丽鱼虫的相似性均超94％,且与刀茎嗜丽鱼虫的相似性均达99.3％以上.从基于核糖体RNA所构建的最大似然树和遗传矩阵来看,本试验中几丁嗜丽鱼虫与不同地区的几丁嗜丽鱼虫聚为一支,且遗传距离均为0;彼丽嗜丽鱼虫与巴西的彼丽嗜丽鱼虫、捷克的刀茎嗜丽鱼虫聚成的拓扑结构自展值为99％和100％,且遗传距离为0.000～0.003,其结果与形态学结果相一致.试验结果补充了该虫在国内分子方面的资料,同时从分子生物学角度彼丽嗜丽鱼虫与刀茎嗜丽鱼虫为同物异名的分类观点提供支撑.

为了解单式指环虫在斑重唇鱼(Diptychus maculates)鳃部寄生的空间分布特点,于2019年5月至2020年6月对新疆叶尔羌河流域斑重唇鱼进行了3次取样调查,运用统计学方法对斑重唇鱼鳃部寄生单式指环虫(Dactylogyrus simplex)的感染情况及空间分布特点进行分析.结果 显示,在检查的325尾斑重唇鱼中,共检出3994只单式指环虫,总感染率和平均感染丰度分别为67.7％和12.3±1.2;左鳃及右鳃的感染率分别为59.4％和57.2％,两者之间的感染丰度无显著差异(P＞0.05);在各鳃片中,鳃Ⅰ(最靠近鳃盖的鳃片)、鳃Ⅱ的平均感染丰度显著高于鳃Ⅳ(P＜0.01);单式指环虫随着宿主的生长,其感染率、感染丰度和强度先上升,后下降,在13～18 cm体长组达到最高,但是各体长组间的感染没有显著差异(P＞0.05).结果 表明,单式指环虫对宿主左右鳃和年龄没有选择偏好性,但在鳃片分布上更偏好寄生于鳃Ⅰ和鳃Ⅱ,单式指环虫在宿主种群中的分布类型为聚集分布.