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Liang J.-H.,Jinan University | Fu Y.-W.,Jinan University | Zhang Q.-Z.,Jinan University | Xu D.-H.,Aquatic Animal Health Research Unit | And 2 more authors.
Journal of Agricultural and Food Chemistry | Year: 2015

Ichthyophthirius multifiliis (Ich) is an important ciliate that parasitizes gills and skin of freshwater fish and causes massive fish mortality. In this study, two flavonoids (kuwanons G and O) with anti-Ich activity were isolated by bioassay-guided fractionation from the root bark of Morus alba, an important plant for sericulture. The chemical structures of kuwanons G and O were elucidated by spectroscopic analyses. Kuwanons G and O caused 100% mortality of I. multifiliis theronts at the concentration of 2 mg/L and possessed a median effective concentration (EC50) of 0.8 ± 0.04 mg/L against the theronts. In addition, kuwanons G and O significantly reduced the infectivity of I. multifiliis theronts at concentrations of 0.125, 0.25, 0.5, and 1 mg/L. The median lethal concentrations (LC50) of kuwanons G and O to grass carp were 38.0 ± 0.82 and 26.9 ± 0.51 mg/L, which were approximately 50 and 35 times the EC50 for killing theronts. The results indicate that kuwanons G and O have the potential to become safe and effective drugs to control ichthyophthiriasis. © 2015 American Chemical Society. Source

Dong H.T.,Chulalongkorn University | LaFrentz B.,Aquatic Animal Health Research Unit | Pirarat N.,Chulalongkorn University | Rodkhum C.,Chulalongkorn University
Journal of Fish Diseases | Year: 2015

Flavobacterium columnare is the aetiological agent of columnaris disease and severely affects various freshwater aquaculture fish species worldwide. The objectives of this study were to determine the phenotypic characteristics and genetic variability among F. columnare isolates isolated from red tilapia in Thailand. Forty-four F. columnare isolates were recovered from diseased fish in different geographical locations. The isolates exhibited homologous phenotypic characteristics but exhibited genetic diversity. One isolate was assigned to genomovar I, and the remainder were assigned to genomovar II, indicating the coexistence of these genomovars but predominance of genomovar II. Phylogenetic analysis of the 16S-23S ISR sequences revealed that a subset of the Thai isolates (n = 25) contained a smaller intergenic spacer region (ISR) (523-537 bp) and formed a unique ISR phylogenetic group. Phylogenetic analysis of the 16S rRNA gene supported the unique cluster of Thai isolates. This is the first description of the phenotypic and molecular characteristics of F. columnare isolated from red tilapia in Thailand as well as five isolates of F. columnare derived from other fish species including Nile tilapia, koi carp and striped catfish. © 2015 John Wiley & Sons Ltd. Source

Yeh H.-Y.,Aquatic Animal Health Research Unit | Yeh H.-Y.,Poultry Microbiological Safety Research Unit | Klesius P.H.,Aquatic Animal Health Research Unit
Fish Physiology and Biochemistry | Year: 2012

Tetraspanins, a large cell surface protein superfamily characterized by having four transmembrane domains, play many critical roles in physiological and pathological processes. In this study, we report the identification, characterization and phylogenetic analysis of the channel catfish tetraspanin 3 and tetraspanin 7 (CD231) transcripts. The full-length nucleotide sequences of tetraspanin 3 and tetraspanin 7 cDNA have 1,453 and 1,842 base pairs, respectively. Analysis of the nucleotide sequences reveals that each has one open reading frame (ORF). The ORF of tetraspanin 3 appears to encode 241 amino acids with calculated molecular mass of 26.8 kDa, while the ORF of tetraspanin 7 potentially encodes 251 amino acids with calculated molecular mass of 27.9 kDa. By comparison with the human counterparts, the channel catfish tetraspanin 3 and tetraspanin 7 peptides have four transmembrane domains, three intracellular domains and two (small and large) extracellular domains. In addition, several characteristic features critical for structure and functions in mammalian tetraspanins are also conserved in channel catfish tetraspanin 3 and tetraspanin 7. The transcripts were detected by RT-PCR in restrictive organs. These results with those from our previous studies on other channel catfish tetraspanins provide important information for further investigating the roles of various tetraspanins in channel catfish infection with microorganisms. © 2012 Springer Science+Business Media B.V. (outside the USA). Source

Yeh H.-Y.,Aquatic Animal Health Research Unit | Klesius P.H.,Aquatic Animal Health Research Unit
Molecular Biology Reports | Year: 2010

The ubiquitin-proteasome cycle is a complex, non-lysosomal biochemical process for intracellular protein degradation. This process involves many enzymes. One enzyme involved in this process is ubiquitin carboxyl-terminal hydrolase L5 (UCHL5), which deubiquitylates the polyubiquitin chain into ubiquitin. In this report, we isolated, sequenced, and characterized the channel catfish UCHL5 cDNA. The complete nucleic acid sequence of the channel catfish UCHL5 cDNA is comprised of 1,357 nucleotides, including an open reading frame, which appears to encode a putative peptide of 329 amino acid residues. The estimated molecular mass and pI of this peptide are 37.6 kDa and 4.84 at pH 7.0, respectively. The degree of conservation of the channel catfish UCHL5 amino acid sequence in comparison to other species ranged from 85% (vs. mouse) to 92% (vs. zebrafish and spotted green pufferfish). The channel catfish UCHL5 transcript was detected by RT-PCR in spleen, head kidney, liver, intestine, skin and gill, suggesting the UCHL5 transcript is constitutively expressed. This research provides important information for further elucidating UCHL5 in the channel catfish ubiquitin-proteasome pathway. © Springer Science+Business Media B.V. 2009. Source

Abernathy J.,Aquatic Genomics Unit | Xu D.-H.,Aquatic Animal Health Research Unit | Peatman E.,Aquatic Genomics Unit | Kucuktas H.,Aquatic Genomics Unit | And 2 more authors.
Comparative Biochemistry and Physiology - Part D: Genomics and Proteomics | Year: 2011

The ciliate parasite Ichthyophthirius multifiliis (Ich) infects many freshwater fish, causing white spot disease that leads to heavy economic losses to aquaculture and ornamental industries. Despite its economic importance, molecular studies examining fundamental processes such as life stage regulation and infectivity have been scarce. In this study, we developed an oligo microarray platform using all available I. multifiliis expressed sequence tag (EST) information as well as probes designed through comparative genomics to other protozoa. Gene expression profiling for developmental and virulence factors was conducted using this platform. For the developmental study, the microarray was used to examine gene expression profiles between the three major life stages of Ich: infective theront, parasitic trophont, and reproductive tomont. A total of 135 putative I. multifiliis genes were found to be differentially expressed among all three life-stages. Examples of differentially expressed transcripts among life stages include immobilization antigens and epiplasmin, as well as various other transcripts involved in developmental regulation and host-parasite interactions. I. multifiliis has been shown to lose infectivity at later cell divisions potentially due to cellular senescence. Therefore, the microarray was also used to explore expression of senescence-associated genes as related to the passage number of the parasite. In this regard, comparison between tomont early and late passages yielded 493 differently expressed genes; 1478 differentially expressed genes were identified between trophont early and late passages. The EST-derived oligo microarray represents a first generation array of this ciliate and provided reproducible expression data as validated by quantitative RT-PCR. © 2011 Elsevier Inc. Source

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