ORCID Profile
0000-0003-4024-1418
Current Organisations
Temasek Life Sciences Laboratory
,
Imperial College London
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Publisher: Wiley
Date: 10-2010
Publisher: Elsevier BV
Date: 02-2021
Publisher: Wiley
Date: 28-10-2020
DOI: 10.1111/RAQ.12514
Publisher: Frontiers Media SA
Date: 12-02-2021
DOI: 10.3389/FVETS.2021.646652
Abstract: Sea lice (Copepoda: Caligidae) are ectoparasites which negatively impact marine aquaculture species around the world. There are a limited number of treatments licensed for use against sea lice in tropical and semi-tropical farmed fish species. Emamectin benzoate (EB) was an effective pharmaceutical drug against sea lice infestations in several salmon industries before resistance to the product developed. This drug has not been extensively tested in marine fish within Asia. The objective of this study was to determine whether this drug could be used to treat oral infections with sea lice in hybrid grouper ( Mycteroperca tigris × Epinephelus lanceolatus ) cultured in saltwater net-pen sites in Hong Kong. We observed an overall reduction in sea lice infections over time, starting on the last day of the treatment up to the end of our study (i.e., 14 days after the last EB treatment). We also observed a large variation in concentrations of EB in fish on the last day of the treatment, which provides an explanation for the variation in response to the treatment. It also suggests that distribution of the medication to fish in saltwater net-pens is difficult, especially when medication is hand-mixed in the feed and possibly unevenly distributed in the daily rations. Overall, this study provides preliminary evidence that EB could be used to treat sea lice found in Hong Kong and potentially in other regions of SE Asia.
Publisher: Wiley
Date: 17-06-2011
DOI: 10.1002/JMOR.10962
Abstract: Mouthpart and alimentary canal development was examined in Lysmata amboinensis larvae using scanning electron microscopy and histology. The gross morphological features of external mouthparts and internal digestive tract structures of larvae at different developmental stages indicate that ingestive and digestive capabilities are well developed from early on. With increasing age of the larvae the mouthpart appendages increased in size, the hepatopancreas in tubular density and the midgut in length. The density of setae and robustness of teeth and spines of in idual structures increased. The most pronounced changes from early to late stage larvae involved formation of pores on the paragnaths and labrum, transformation of the mandibular spine-like teeth to molar cusps, development of the filter press in the proventriculus and of infoldings in the previously straight hindgut. The results suggest that early stage L. amboinensis larvae may benefit from soft, perhaps gelatinous prey, whereas later stages are better equipped to handle larger, muscular or more fibrous foods.
Publisher: Elsevier BV
Date: 12-2018
DOI: 10.1016/J.VETPAR.2018.10.009
Abstract: The genus Chilodonella includes free-living ciliated protozoa as well as pathogenic species for freshwater fish, with Chilodonella hexasticha and Chilodonella piscicola being the most important ones. These parasites cause outbreaks with high mortalities among farmed freshwater fishes with great economic losses. There are few reports of these species in China, and their identification has been based mostly on their morphological characteristics. In the present work, the parasites causing five outbreaks occurring in China between 2014 and 2017 have been identified by morphological and genetic analysis. We provide the first records of Ctenopharingodon idella and Siniperca chuatsi as hosts of C. hexasticha, and of Procypris rabaudi and Schizothorax wangchiachii as hosts of C. piscicola. There are no differences in the gross pathological findings produced by C. hexasticha and C. piscicola, consisting in desquamation and necrosis of epithelial cells in the skin and gills and in severe fusion of gill lamellae. However, both species differ in their geographic distribution: C. piscicola was found in farms located at altitudes over 1500 m above sea level and with a water temperature ≤18 °C, while C. hexasticha was found in farms located at altitudes under 50 m above sea level and with a water temperature ≥21 °C. Present results confirm that C. hexasticha and C. piscicola are two different species that can be differenced by their morphology however, their biological variability may lead to erroneous identifications and the diagnosis should be preferably based in genetic analysis including nuclear LSU rDNA and mitochondrial SSU rDNA sequences.
Publisher: Informa UK Limited
Date: 17-02-2020
DOI: 10.1080/00480169.2020.1718564
Abstract: The ornamental fish industry is growing quickly globally. Asia represents 51% of the export market for this industry and in Singapore alone, it has an estimated market value of US$66 million. Despite the economic importance of this industry for Australasia, aquatic veterinary support for the ornamental fish sector is scarce. In many cases, ornamental fish owners do not seek advice from veterinarians. While the reasons behind this are difficult to elucidate, the low perceived value of fish compared to the cost of consulting a veterinarian, and limited knowledge about the availability of veterinary services for aquatic animals may contribute to the lack of interaction with veterinarians. Considering the growing importance of the ornamental fish industry, more education and data are needed about the services offered by veterinarians with aquatic animal health expertise. Knowledge on aquatic veterinary medicine is limited, reinforcing the need for more educational programmes and dissemination of aquatic veterinary services within the Australasian region.
Publisher: eLife Sciences Publications, Ltd
Date: 23-08-2021
DOI: 10.7554/ELIFE.65285
Abstract: Eukaryotic cells deploy autophagy to eliminate invading microbes. In turn, pathogens have evolved effector proteins to counteract antimicrobial autophagy. How adapted pathogens co-opt autophagy for their own benefit is poorly understood. The Irish famine pathogen Phytophthora infestans secretes the effector protein PexRD54 that selectively activates an unknown plant autophagy pathway that antagonizes antimicrobial autophagy at the pathogen interface. Here, we show that PexRD54 induces autophagosome formation by bridging vesicles decorated by the small GTPase Rab8a with autophagic compartments labeled by the core autophagy protein ATG8CL. Rab8a is required for pathogen-triggered and starvation-induced but not antimicrobial autophagy, revealing specific trafficking pathways underpin selective autophagy. By subverting Rab8a-mediated vesicle trafficking, PexRD54 utilizes lipid droplets to facilitate biogenesis of autophagosomes erted to pathogen feeding sites. Altogether, we show that PexRD54 mimics starvation-induced autophagy to subvert endomembrane trafficking at the host-pathogen interface, revealing how effectors bridge distinct host compartments to expedite colonization.
Publisher: Wiley
Date: 30-07-2016
DOI: 10.1111/JFD.12523
Abstract: Freshwater fish farming contributes to more than two-thirds of global aquaculture production. Parasitic ciliates are one of the largest causes of production loss in freshwater farmed fishes, with species from the genus Chilodonella being particularly problematic. While Chilodonella spp. include 'free-living' fauna, some species are involved in mortality events of fish, particularly in high-density aquaculture. Indeed, chilodonellosis causes major productivity losses in over 16 species of farmed freshwater fishes in more than 14 countries. Traditionally, Chilodonella species are identified based on morphological features however, the genus comprises yet uncharacterized cryptic species, which indicates the necessity for molecular diagnostic methods. This review synthesizes current knowledge on the biology, ecology and geographic distribution of harmful Chilodonella spp. and examines pathological signs, diagnostic methods and treatments. Recent advances in molecular diagnostics and the ability to culture Chilodonella spp. in vitro will enable the development of preventative management practices and sustained freshwater fish aquaculture production.
Publisher: Elsevier BV
Date: 09-2012
DOI: 10.1016/J.CBPB.2012.05.008
Abstract: Myostatin (MSTN) is a pivotal protein that regulates vertebrate muscle growth and development. Teleost fish possess two MSTN paralogs (MSTN-1 and MSTN-2) whose respective physiological functions are still largely unclear. To clarify the role of each of these paralogs the transcript abundance of Mstn-1 and Mstn-2 was quantified during embryonic and larval development of the teleosts, barramundi, Lates calcarifer. Histological analyses of developing muscle fibers were also obtained to correlate Mstn paralog expression with muscle hypertrophy as larvae undergo metamorphosis. Mstn-1 and Mstn-2 transcripts were detected as early as immediately postfertilization of eggs, with the level of expression observed to increase during embryonic development and reach a peak near hatching. Mstn-2 expression was thousands-fold higher than that observed for Mstn-1. Close to metamorphosis, the expression of Mstn-1 was non-significantly, although positively associated, with muscle hypertrophy (r=0.384, p=0.064), while that of Mstn-2 showed a highly significant negative correlation (r=-0.691, p<0.0001) suggesting that this paralog may be responsible for muscle hypertrophy that occurs post-metamorphosis. Altogether, findings from this study support the hypothesis that Mstn paralogs are differentially regulated during various phases of fish development and that they may have evolved different functions in fish, particularly that related to muscle hypertrophy.
Publisher: MDPI AG
Date: 29-07-2021
DOI: 10.3390/D13080350
Abstract: The adoption of new investigative strategies based on environmental DNA (eDNA) can be used to monitor parasites, associated bacterial microbiomes, and physical-chemical parameters in fish farms. In this study, we used the economically important and globally distributed fish ciliate parasite Cryptocaryon irritans as a model to understand the parasite abundance and potential drivers of its presence in marine fish farms. Environmental (rainfall) and physical-chemical (temperature, oxygen, salinity, pH) data collected from a marine fish farm in Hong Kong were analyzed together with the eDNA approach targeting C. irritans abundance based on digital droplet PCR and 16S metagenomics to determine associations and triggers between parasites and specific bacterial groups. Rainfall and temperature demonstrated positive associations with high abundance of C. irritans (eDNA) at the studied marine fish cage farm. However, rainfall was the only parameter tested that demonstrated a significant association with parasite eDNA, indicating that the raining season is a risky period for fish farmers in Hong Kong. Coraliomargarita was the bacterial genus with the most significant relationship with low abundance of C. irritans in water. Understanding the environmental triggers of ciliate parasites propagation and associated bacterial microbiome could elucidate new insights into environmental control, microbial management, and promote the reduction of chemical use in marine fish farms.
Publisher: Elsevier BV
Date: 03-2019
Publisher: Wiley
Date: 20-12-2011
DOI: 10.1002/JMOR.20000
Publisher: Elsevier BV
Date: 10-2017
Publisher: eLife Sciences Publications, Ltd
Date: 15-06-2021
Publisher: Wiley
Date: 13-07-2022
DOI: 10.1111/RAQ.12708
Abstract: Ciliates are considered the most harmful parasites of fish, causing mass mortalities and thus substantial economic losses to the aquaculture and ornamental fish industries. To better elucidate their pathogenic mechanisms and facilitate the development of effective prevention and control strategies, it is essential to apply novel technologies to ensure the continuous and sufficient supply of parasite specimens. This review discusses the latest research progress in the artificial culture of six important parasitic ciliates affecting both freshwater and marine fish globally: Ichthyophthirius multifiliis , Cryptocaryon irritans , Chilodonella ( C. hexasticha , C. piscicola and C. uncinata ), Balantidium ctenopharyngodoni , Scuticociliatida gen. spp., and Tetrahymena spp. Methods for in vitro and in vivo culture as well as cryopreservation reservation (depending on the specific species) of these organisms are described herein. Challenges and future applications of parasite culture are also discussed.
Publisher: Elsevier BV
Date: 04-2017
DOI: 10.1016/J.VETPAR.2017.03.004
Abstract: Parasitic Chilodonella species, Chilodonella piscicola and Chilodonella hexasticha, cause considerable economic losses globally to freshwater farmed fish production. Some genetic studies of Chilodonella spp. have indicated that many species within the genus may form cryptic species complexes. To understand the ersity of Chilodonella spp. infecting Australian freshwater farmed fish, specimens were isolated from infected barramundi (Lates calcarifer) and Murray cod (Maccullochella peelii) from fish farms in tropical north Queensland (QLD), temperate Victoria (Vic) and New South Wales (NSW) for genetic and morphological analysis. Parasites were stained and measured for morphological description and comparative phylogenetic analyses were performed using the mitochondrial small subunit (mtSSU) rDNA marker. Morphological analyses revealed four distinct morphotypes of Chilodonella infecting farmed barramundi and Murray Cod. Three putative species were isolated from barramundi (Chilodonella hexasticha, C. acuta and C. uncinata) and one from Murray cod (C. piscicola). However, phylogenetic analyses detected only three distinct genotypes, with the putative C. hexasticha and C. piscicola sharing 100% sequence identity. This suggests that Australian isolates of C. hexasticha and C. piscicola could represent the same species and may exhibit phenotypic plasticity. Further molecular analysis, including isolates from the type localities, should be performed to support or refute the synonymy of these species.
Location: Australia
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Start Date: 2016
End Date: 2017
Funder: Fisheries Research and Development Corporation
View Funded ActivityStart Date: 2016
End Date: 2017
Funder: Department of Agriculture and Water Resources, Australian Government
View Funded ActivityStart Date: 2016
End Date: 2017
Funder: James Cook University
View Funded ActivityStart Date: 2017
End Date: 2018
Funder: James Cook University
View Funded ActivityStart Date: 2017
End Date: 2017
Funder: James Cook University
View Funded ActivityStart Date: 2013
End Date: End date not available
Funder: James Cook University
View Funded ActivityStart Date: 2014
End Date: 2014
Funder: Australian Society for Parasitology
View Funded ActivityStart Date: 2014
End Date: 2014
Funder: Australian Society for Parasitology
View Funded Activity