Investigation of Ichthyophthirius multifiliis infection in fish from natural water bodies in the Lhasa and Nagqu regions of Tibet.

This study aimed to examine the prevalence of Ichthyophthirius multifiliis in fish inhabiting natural water bodies in the Lhasa and Nagqu regions of Tibet in September 2020 and August 2021. The results showed that Schizopygopsis selincuoensis had the highest prevalence of I. multifiliis at 33.73% (56/166), followed by Triplophysa tibetana at 30.00% (6/20), Triplophysa brevicauda at 27.91% (12/43) and Schizopygopsis thermalis at 23.66% (31/131). No infection with I. multifiliis was observed in exotic fish species. In addition, the prevalence of I. multifiliis in Boqu Zangbo (river), Selincuo Lake and Cuona Lake in the Nagqu region was found to be significantly higher than that in Lalu Wetland and Chabalang Wetland in the Lhasa region (P < 0.05). The study revealed a significantly lower prevalence in Lhasa River than in Cuona Lake (P < 0.05). Notably, our findings revealed instances of I. multifiliis infections even in saline water bodies, thereby emphasizing the potential threat that this parasite poses to the preservation of indigenous fish resources in Tibet. Consequently, immediate and effective countermeasures are imperative. This study represents the first systematic investigation of I. multifiliis infection in natural water bodies in Tibet.

Comparison of droplet digital PCR and real-time quantitative PCR for quantitative detection of the parasitic ciliate Ichthyophthirius multifiliis in the water environment.

Ichthyophthiriasis, caused by the parasitic ciliate Ichthyophthirius multifiliis (Ich), is considered one of the most harmful diseases affecting freshwater fish globally. It can cause mass mortalities of fish in intensive farming systems. In such systems, it is thus necessary to detect and quantify the number of Ich in the water so that control measures can be implemented before Ichthyophthiriasis breaks out. In recent years, molecular diagnostic methods have become increasingly important in aquaculture. Real-time quantitative polymerase chain reaction (qPCR) and droplet digital polymerase chain reaction (ddPCR) have become robust assays for detecting pathogens. In this study, a set of specific primers and a TaqMan-minor groove binder probe targeting the small-subunit rDNA (SSU rDNA) of Ich were developed. They were used in qPCR and ddPCR assays to compare the performance of these two different methods in quantitatively detecting Ich. After optimizing the reaction conditions, both qPCR and ddPCR assays were found to have high linearity and quantitative correlations for standard plasmid DNA. When used for the detection of Ich eDNA in water samples, the qPCR assay had a wider detection range, making it a suitable method to screen for the prevalence of Ichthyophthiriasis. However, the ddPCR approach had higher sensitivity, which would help provide advance notice of the disease in complex water environmental samples.

Psychological stress in inflammatory bowel disease: Psychoneuroimmunological insights into bidirectional gut-brain communications.

Inflammatory bowel disease (IBD), mainly including ulcerative colitis (UC) and Crohn's disease (CD), is an autoimmune gastrointestinal disease characterized by chronic inflammation and frequent recurrence. Accumulating evidence has confirmed that chronic psychological stress is considered to trigger IBD deterioration and relapse. Moreover, studies have demonstrated that patients with IBD have a higher risk of developing symptoms of anxiety and depression than healthy individuals. However, the underlying mechanism of the link between psychological stress and IBD remains poorly understood. This review used a psychoneuroimmunology perspective to assess possible neuro-visceral integration, immune modulation, and crucial intestinal microbiome changes in IBD. Furthermore, the bidirectionality of the brain-gut axis was emphasized in the context, indicating that IBD pathophysiology increases the inflammatory response in the central nervous system and further contributes to anxiety- and depression-like behavioral comorbidities. This information will help accurately characterize the link between psychological stress and IBD disease activity. Additionally, the clinical application of functional brain imaging, microbiota-targeted treatment, psychotherapy and antidepressants should be considered during the treatment and diagnosis of IBD with behavioral comorbidities. This review elucidates the significance of more high-quality research combined with large clinical sample sizes and multiple diagnostic methods and psychotherapy, which may help to achieve personalized therapeutic strategies for IBD patients based on stress relief.

In Vitro Assessment of Berberine against Ichthyophthirius multifiliis in Goldfish.

Ichthyophthirius multifiliis is a pathogenic ciliate parasite, which infects almost all freshwater teleost fish and leads to significant economic losses. The present study aimed to evaluate the acute toxicity of berberine to the free-living stages of I. multifiliis, that is, theronts and tomonts. Our results indicated that 99.30% of I. multifiliis theronts were killed by a concentration of 15 mg/L berberine during the 4 h exposure time, while berberine had no effect on protomonts. Nevertheless, berberine at a concentration of 5 mg/L could effectively reduce the release of theronts from tomonts treated for 4 h. Additionally, according to the transmission electron microscopy results, berberine at 15 mg/L could strongly change the shape of protomonts, destroy their organelles, and significantly decrease the number of ribosomes. The median lethal concentration (LC50) of berberine for goldfish at 96 h was 528.44 mg/L, which was almost 67 times the median effective concentration (EC50) of berberine for killing theronts (7.86 mg/L). The results demonstrated that berberine could be an effective and safe potential parasiticide for killing I. multifiliis.

Morphological and molecular characterization of a new ciliate Nyctotheroides grimi n. sp. (Armophorea, Clevelandellida) from Chinese frogs.

A new species of clevelandellid ciliate, Nyctotheroides grimi n. sp., is described from the frog Fejervarya limnocharis. Light and scanning electron microscopy were used for the morphological studies, and the DNA encoding the SSU rRNA gene (SSU rDNA) and the ITS1-5.8S subunit rRNA-ITS2 region (ITS) were sequenced for genetic comparisons and phylogenetic analysis. The main distinctive morphological feature is a knob-like projection in the left-posterior end; other differential characters are the cell size, the length of the oral groove and the shape of the infundibulum. Nyctotheroides grimi possess an apical suture line in the left and right side of the anterior end and in the left side of the caudal end. In the phylogenetic analyses, the new species engroups with other Nyctotheroides species forming a monophyletic group. The high similarity in the SSU rDNA and ITS sequences between Nyctotheroides species suggests a relative recent divergence. The genetic data and the different host range support the separation of Nyctotheroides and Nyctotherus; however the morphological criterion based on the presence (in Nyctotheroides)/absence (in Nyctothterus) of an apical kinetal suture line should be modified to consider the presence of kinetal suture lines in the apical and/or the caudal left side in Nyctotheroides.

Morphological description of Opalina obtrigonoidea Metcalf, 1923 (Heterokonta, Opalinea) from Duttaphrynus melanostictus and evaluation of the ITS region as a suitable genetic marker for inter-species identification in Opalina.

The redescription of Opalina obtrigonoidea Metcalf, 1923, collected from the rectum of the toads Duttaphrynus melanostictus, is presented in this paper based on detailed morphological information and molecular data. Our results revealed that O. obtrigonoidea varies greatly in body dimensions. Its morphological characteristics allow its differentiation from Opalina undulata. Surprisingly, we sequenced its SSU rDNA-ITS1-5.8S rDNA-ITS2-LSU rDNA (5' end) and found the SSU rDNA of O. obtrigonoidea is nearly identical to that of O. undulata. However, there are differences in both the ITS1 and ITS2 regions that allow their distinction and confirm the morphological differences. Our results indicate that O. obtrigonoidea and O. undulata are closely related species in which morphological and genetic markers have evolved at different speeds. Due to this, the SSU rDNA gene may not be a valid marker for inter-species identification in Opalina, but the ITS is a valid marker for differentiating species in this genus.

Redescription of Opalina triangulata (Heterokonta, Opalinea) from Fejervarya limnocharis based on morphological and molecular data.

Opalinids are a large group of anaerobic protists, mainly inhabiting the cloacae of amphibians (frogs and toads). The classification of this group has not been fully resolved, because of a lack of molecular information. Here, we give a redescription of Opalina triangulata Metcalf, 1923, collected from the rectum of the frog Fejervarya limnocharis, based on detailed morphological and molecular data. Our phylogenetic analyses confirmed the monophyly of Opalinata. Within it, Opalinea were monophyletic with O. triangulata and O. undulata as well as two Protoopalina species grouping together. Karotomorpha and Proteromonas did not group together confirming the paraphyly of Proteromonadea. Meanwhile, the ITS2 secondary structural similarities as well as G-C content revealed greater similitudes between Opalina species and P. lacertae than with Blastocystis hominis, which is in accordance with their position as sister clades in the SSU rDNA-based phylogenies.