Frederick C Leung

Chittagong Veterinary and Animal Sciences University, Chittagong Ghat, Chittagong, Bangladesh

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Publications (56)308.87 Total impact

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    ABSTRACT: Recent studies have described the bacterial community residing in the guts of giant pandas, together with the presence of lignocellulolytic enzymes. However, a more comprehensive understanding of the intestinal microbial composition and its functional capacity in giant pandas remains a major goal. Here, we conducted a comparison of bacterial, fungal and homoacetogenic microbial communities from fecal samples taken from two geriatric and two adult captive giant pandas. 16S rDNA amplicon pyrosequencing revealed that Firmicutes and Proteobacteria are the most abundant microbiota in both geriatric and adult giant pandas. However, members of phylum Actinobacteria found in adult giant pandas were absent in their geriatric counterparts. Similarly, ITS1 amplicon pyrosequencing identified developmental changes in the most abundant fungal classes from Sordariomycetes in adult pandas to Saccharomycetes in geriatric pandas. Geriatric pandas exhibited significantly higher abundance of a potential probiotic fungus (Candida tropicalis) as compared to adult pandas, indicating their importance in the normal digestive physiology of aged pandas. Our study also reported the presence of a lignocellulolytic white-rot fungus, Perenniporia medulla-panis, and the evidence of novel homoacetogens residing in the guts of giant pandas.
    PLoS ONE 01/2014; 9(1):e79902. · 3.73 Impact Factor
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    ABSTRACT: The emergence and spread of Type 2 Porcine Reproductive and Respiratory Syndrome virus (Type 2 PRRSV) in North America is heavily influenced by the multiple site production system used in the hog industry. However, it is unclear how anthropogenic factors such has this have shaped the current spatial distribution of PRRSV genotypes. We employed Bayesian phylogeographic analyses of 7040 ORF5 sequences to reveal the recent geographical spread of Type 2 PRRSV in North America. The directions and intensities in our inferred virus traffic network closely mirror the hog transportation. Most notably, we reveal multiple viral introductions from Canada into the United States causing a major shift in virus genetic composition in the Midwest USA that went unnoticed by the regular surveillance and field epidemiological studies. Overall, these findings provide important insights into the dynamics of Type 2 PRRSV evolution and spread that will facilitate programs for control and prevention.
    Virology 12/2013; 447(1-2):146-54. · 3.35 Impact Factor
  • Mang Shi, Edward C Holmes, Manreetpal Singh Brar, Frederick Chi-Ching Leung
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    ABSTRACT: In 2009-2010 there was a marked increase in the number of infections of Highly Pathogenic Porcine Reproductive and Respiratory Syndrome virus (HP-PRRSV) in China. Through phylogenetic analysis we show that viruses from this outbreak originated from a single recombination event, illustrating the potential importance of this process for disease emergence.
    Journal of Virology 07/2013; · 5.08 Impact Factor
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    ABSTRACT: To investigate the origins, evolution and patterns of spread of HPAI H5N1 outbreaks in Bangladesh, we performed a phylogenetic reconstruction analysis using Bayesian methods. The analysis was conducted using 81 hemagglutinin (HA) gene sequences from the H5N1 viruses isolated in Bangladesh from 2007 to 2011, together with 264 publicly available HA sequences of clade 2.2, 2.3.2 and 2.3.4 retrieved from GenBank. Our study provides evidence that clade 2.2.2 viruses that caused outbreaks in Bangladesh were lineages independent from the viruses introduced earlier into India. Furthermore, the Bangladesh clade 2.2.2 descendents subsequently spread to India and Bhutan. This has implications for avian influenza control in southern Asia suggesting multiple routes of entry of the virus including one pathway that spread to neighboring countries via Bangladesh.
    Preventive Veterinary Medicine 06/2013; · 2.39 Impact Factor
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    ABSTRACT: Emus (Dromaius novaehollandiae), large flightless ratites native to Australia, are farmed for their fat and meat. They are omnivorous and feed on a wide variety of plants and insects. Despite having a relatively simple gastrointestinal tract and a short digesta retention time, emus are able to digest a significant portion of the ingested dietary neutral detergent fibre. However, nothing is known about the microbial diversity in their gastrointestinal tract. In this study, we evaluated the phylogenetic diversity of the cecal microbiota of four emus (2 males, 2 females) that were fed a barley-alfalfa-canola based diet, using 454 pyrosequencing after amplification for V3-V5 region of bacterial 16S rRNA gene. Emus were slaughtered in early November, just prior to the onset of their breeding season, but after the seasonal decline in their feed intake had begun. A total of 822 operational taxonomic units (OTUs) (335.3±70.5OTUs/sample) belonging to 9 bacterial phyla were identified. The most predominant bacterial phyla were Bacteroidetes (∼57% of total classified diversity), Proteobacteria (∼24%), Fusobacteria (∼11.3%), and Firmicutes (∼7%). Our results indicate that the emus' ceca may have a higher microbial richness (Chao1: 624±170OTUs, and ACE: 586±161OTUs) than other species of birds, but they have a lower microbial diversity (Shannon diversity index: 3.4±0.2, Simpson index: 0.79±0.02), possibly reflecting their decrease feed intake. This is the first study to characterize the microbial community of the gastrointestinal tract of a ratite using pyrosequencing, providing a baseline for further study.
    Veterinary Microbiology 06/2013; · 3.13 Impact Factor
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    ABSTRACT: Recombination plays an important role in shaping the genetic diversity of a number of DNA and RNA viruses. Although some recent studies have reported bioinformatic evidence of mosaic sequences in a variety of influenza A viruses, it remains controversial as to whether these represent bona fide natural recombination events or laboratory artifacts. Importantly, mosaic genome structures can create significant topological incongruence during phylogenetic analyses, which can mislead additional phylogeny-based molecular evolutionary analyses such as molecular clock dating, the detection of selection pressures and phylogeographic inference. As a result, there is a strong need for systematic screenings for mosaic structures within the influenza virus genome database. We used a combination of sequence-based and phylogeny-based methods to identify 388 mosaic influenza genomic segments, of which 332 are previously unreported and are significantly supported by phylogenetic methods. It is impossible, however, to ascertain whether these represent natural recombinants. To facilitate the future identification of recombinants, reference sets of non-recombinant sequences were selected for use in an automatic screening protocol for detecting mosaic sequences. Tests using real and simulated mosaic sequences indicate that our screening protocol is both sensitive (average >90%) and accurate (average >77%) enough to identify a range of different mosaic patterns. The relatively high prevalence of mosaic influenza virus sequences implies that efficient systematic screens, such as that proposed here, should be performed routinely to detect natural recombinant strains, potential laboratory artifacts, and sequencing contaminants either prior to sequences being deposited in GenBank or before they are used for phylogenetic analyses.
    Infection, genetics and evolution: journal of molecular epidemiology and evolutionary genetics in infectious diseases 03/2013; · 3.22 Impact Factor
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    ABSTRACT: Background Understanding the effects of pretreatment on anaerobic digestion of sludge waste from wastewater treatment plants is becoming increasingly important, as impetus moves towards the utilization of sludge for renewable energy production. Although the field of sludge pretreatment has progressed significantly over the past decade, critical questions concerning the underlying microbial interactions remain unanswered. In this study, a metagenomic approach was adopted to investigate the microbial composition and gene content contributing to enhanced biogas production from sludge subjected to a novel pretreatment method (maintaining pH at 10 for 8 days) compared to other documented methods (ultrasonic, thermal and thermal-alkaline). Results Our results showed that pretreated sludge attained a maximum methane yield approximately 4-fold higher than that of the blank un-pretreated sludge set-up at day 17. Both the microbial and metabolic consortium shifted extensively towards enhanced biodegradation subsequent to pretreatment, providing insight for the enhanced methane yield. The prevalence of Methanosaeta thermophila and Methanothermobacter thermautotrophicus, together with the functional affiliation of enzymes-encoding genes suggested an acetoclastic and hydrogenotrophic methanogenesis pathway. Additionally, an alternative enzymology in Methanosaeta was observed. Conclusions This study is the first to provide a microbiological understanding of improved biogas production subsequent to a novel waste sludge pretreatment method. The knowledge garnered will assist the design of more efficient pretreatment methods for biogas production in the future.
    Biotechnology for Biofuels 03/2013; 6(38). · 5.55 Impact Factor
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    ABSTRACT: In this study, gene structure, tissue expression, and promoter usage of prolactin receptor (PRLR) and its interaction with prolactin (PRL) and the newly identified prolactin-like protein (PRL-L) were investigated in chickens. The results showed that 1) PRLR gene was found to consist of at least 25 exons by 5'-RACE and RT-PCR assays; 2) multiple PRLR 5'-UTR sequences different in exon composition were isolated from chicken liver or intestine by 5'-RACE and could be subdivided into type I and type II transcripts according to the first exon used (exon 1G or exon 1A); 3) PRLR Type I transcripts with exon 1G were detected to be predominantly expressed in adult kidney and small intestine by RT-PCR, implying their expression is likely controlled by a tissue-specific promoter (P1). By contrast, PRLR type II transcripts containing exon 1A are widely expressed in adult and embryonic tissues examined and their expression is controlled by a generic promoter (P2) near exon 1A, which was demonstrated to display promoter activities in cultured DF-1, HEK293 and LoVo cells by the dual-luciferase reporter assay; 4) Using a 5×STAT5-luciferase reporter system, cPRLR expressed in HepG2 cells was shown to be activated by recombinant cPRL and cPRL-L via interaction with PRLR membrane-proximal ligand-binding domain, suggesting that like cPRL, cPRL-L is also a functional ligand of cPRLR. Collectively, characterization of cPRLR gene helps to elucidate the roles of PRLR and its ligands in birds and provides insights into the regulatory mechanisms of PRLR expression conserved in birds and mammals.
    Molecular and Cellular Endocrinology 03/2013; · 4.04 Impact Factor
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    ABSTRACT: The Enterobacter cloacae species includes an extremely diverse group of bacteria that are associated with plants, soil and humans. Publication of the complete genome sequence of the plant growth-promoting endophytic E. cloacae subsp. cloacae ENHKU01 provided an opportunity to perform the first comparative genome analysis between strains of this dynamic species. Examination of the pan-genome of E. cloacae showed that the conserved core genome retains the general physiological and survival genes of the species, while genomic factors in plasmids and variable regions determine the virulence of the human pathogenic E. cloacae strain; additionally, the diversity of fimbriae contributes to variation in colonization and host determination of different E. cloacae strains. Comparative genome analysis further illustrated that E. cloacae strains possess multiple mechanisms for antagonistic action against other microorganisms, which involve the production of siderophores and various antimicrobial compounds, such as bacteriocins, chitinases and antibiotic resistance proteins. The presence of Type VI secretion systems is expected to provide further fitness advantages for E. cloacae in microbial competition, thus allowing it to survive in different environments. Competition assays were performed to support our observations in genomic analysis, where E. cloacae subsp. cloacae ENHKU01 demonstrated antagonistic activities against a wide range of plant pathogenic fungal and bacterial species.
    PLoS ONE 01/2013; 8(9):e74487. · 3.73 Impact Factor
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    ABSTRACT: Haemophilus parasuis is the etiological agent of Glässer's disease in pigs and 15 standard serovars were identified. The widespread disease causes great economic loss in the swine industry worldwide. Aiming to investigate the differences in genome composition and functions among various strains, a highly virulent strain ZJ0906 of H. parasuis serovar 12 from China was analyzed and compared with serovar 5 SH0165. Strain ZJ0906 genome is 2,324,740 base pairs with 40.06% genomic GC content. It contains 2,484 open reading frames (ORF) predicted by Glimmer 3.02, of which 2,352 (∼94.7%) were annotated by NCBI nr blast, 1,745 by COG database and 1,829 by KEGG database. 109 potential virulence factors were annotated in strain ZJ0906 and 3 of which are potentially related to antibiotic resistance. Strain ZJ0906 genome is ∼55 kilobases longer than SH0165 genome, with an extra 211 predicted ORFs. VFDB, ARDB, and PAIDB blast searches showed that ZJ0906 and SH0165 shared a nearly identical panel of potential virulence factors, drug resistant genes and four PAI-like regions which showed high homology to Enterococcus, Escherichia and Salmonella. Synteny analysis showed that gene rearrangements are frequent between the two strains, which may lead to variations in pathogenicity and cross-protection among serovars. KEGG pathway analyses showed strain ZJ0906 shared similar metabolic pathways to strain SH0165. Molecular identification of these genomic elements and potential virulence factors pave the way to the better understanding of mechanisms underlying metabolic capabilities and pathogenicity of H. parasuis and prospective vaccine targets besides the widely used method of inactivated bacteria.
    PLoS ONE 01/2013; 8(9):e68350. · 3.73 Impact Factor
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    ABSTRACT: Emus (Dromaius novaehollandiae) are farmed for their oil for pharmaceutical and cosmetic uses. This emu pituitary expressed sequence tag study was undertaken to identify novel transcripts in the emu pituitary to propel their identification and functional studies. By mapping reads derived from the Roche 454 GS Junior pyrosequencer to 8 reference species (human, mouse, chicken, zebra finch, fruit fly, turkey, round worm, and Carolina anole lizard) from the UniGene database, a total of 81,788 reads (53,312 mapped reads) were obtained and assembled with Reference Sequence (RefSeq). We annotated 6,676 potential emu genes by referencing 7 species (excluding lizard) and identified 1,232 potential genes common among 3 species (human, mouse, and chicken) with complete available reference genomes. Gene Ontology analysis revealed 376 Gene Ontology terms showing, with the highest counts, their involvements in biological processes, metabolism, and cellular components. These potential genes were detected to associate with 20 pathways including mitogen-activated protein kinase, insulin, neurotrophin signaling pathways, and carbohydrate digestion and absorption pathway. We also revealed a panel of tissue-specific genes including regulator of G-protein signaling protein (RGS), glucagon-like peptide receptor (GLPR), and growth hormone-inducible transmembrane protein (GHITM). Additionally, fatty acid binding protein (FABP), fatty acid desaturase (FAS), and stearoyl-coenzyme A desaturase (SCD), key enzyme genes in fat metabolism, were found to be also expressed in emu pituitary. This expressed sequence tag study represents the first step in functional characterization of emu pituitary gene expression and SNP identification for the improvement of fat production in the emu.
    Poultry Science 01/2013; 92(1):90-6. · 1.52 Impact Factor
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    ABSTRACT: Enterobacter cloacae subsp. cloacae strain ENHKU01 is a Gram-negative endophyte isolated from a diseased pepper (Capsicum annuum) plant in Hong Kong. This is the first complete genome sequence report of a plant-endophytic strain of E. cloacae subsp. cloacae.
    Journal of bacteriology 11/2012; 194(21):5965. · 3.94 Impact Factor
  • John Chi Wang Ho, Tim Jacobs, Yajun Wang, Frederick C Leung
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    ABSTRACT: In mammals, the neuropeptide galanin exerts a variety of physiological roles in the neuroendocrine system through its interactions with three galanin receptor subtypes (GalR1, GalR2 and GalR3). However, little is known about the characteristics of galanin receptors in birds, and it is only recently that avian GalR1 and a novel GalR1-like receptor were first identified in chickens. In this study, we report the cDNA cloning and characterization of the other two chicken galanin receptors, the galanin type II receptor (cGalR2) and a novel GalR2-like receptor (GalR2-L), which share high degrees of similarity in sequence identity, gene structure and signaling properties. cGalR2 and cGalR2-L cDNAs encode two putative receptors of 371 and 370 amino acids, in which they show considerable amino acid sequence identities (65-67%, and 53-55%, respectively) with the mammalian GalR2. RT-PCR assays revealed that cGalR2 and cGalR2-L mRNA were widely expressed in the adult chicken tissues including the whole brain, intestine, lung, ovary, pituitary and different regions of the oviduct. As assayed with different luciferase reporter systems, chicken galanin (cGal 1-29) and human galanin-like peptide (hGALP 1-60) were demonstrated to stimulate the luciferase activities in Chinese hamster ovary cells expressing cGalR2 and cGalR2-L through the activations of cAMP/PKA, Ca(2+)/calcineurin and MAPK/ERK signaling pathways, hence suggesting that both receptors are functionally coupled to the G(s) and G(q) proteins. Furthermore, the previously identified cGalR1 and cGalR1-L were found to be solely coupled to the G(i/o) proteins, and the hGALP (1-60) exhibited only a low potency to cGalR1, cGalR1-L, cGalR2 and cGalR2-L activations.
    General and Comparative Endocrinology 09/2012; 179(2):305-12. · 2.82 Impact Factor
  • Amy H Y Kwok, Yajun Wang, Frederick C Leung
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    ABSTRACT: Prostaglandin E and F regulate diverse physiological functions including gastrointestinal motility, fever induction and reproduction. This multitude of biological effects is mediated via their four E receptor subtypes (EP(1), EP(2), EP(3) and EP(4)) and F receptor (FP), respectively. Majority of these studies was performed in mammalian species, while investigations on their roles were impeded by inadequate information on their receptors in avian species. In present study, full-length cDNAs of chicken EP(3) (cEP(3)) and two isoforms of FP - cFPa and cFPb - were cloned from adult hen ovary. The putative cEP(3) and cFPa share high amino acid sequence identity with their respective orthologs, while the predicted cFPb is a novel middle-truncated splice variant which lacks 107 amino acids between transmembrane domains 4 and 6. RT-PCR showed that cEP(3), cFPa and cFPb are widely expressed in adult tissues examined, including ovary and oviduct. Using a pGL3-CRE luciferase reporter system, cEP(3)-expressing DF1 cells inhibited forskolin-induced luciferase activity (EC(50): <1.9pM) upon PGE(2) treatment, suggesting that cEP(3) may functionally couple to Gi protein. Upon PGF(2α) addition, cFPa was shown to potentially couple to intracellular Ca(2+)-signaling pathway by pGL3-NFAT-RE reporter assay (EC(50): 2.9 nM), while cFPb showed no response. Using a pGL4-SRE reporter system, both cEP(3) and cFPa exhibited potential MAPK activation by PGE(2) and PGF(2α) at EC(50) 0.34 and 13nM, respectively. Molecular characterization of these receptors paved the road to the better understanding of PGE(2) and PGF(2α) roles in avian physiology and comparative endocrinology studies.
    General and Comparative Endocrinology 08/2012; 179(1):88-98. · 2.82 Impact Factor
  • Amy H Y Kwok, Yajun Wang, Frederick C Leung
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    ABSTRACT: Prostaglandins E (PGE) and F (PGF) mediate diverse physiological functions via their cell surface receptors - prostaglandin E receptor (EP) subtypes 1, 2, 3 and 4 (EP(1); EP(2); EP(3); EP(4)) and F receptor (FP). In teleost fishes, PGE was implicated in gill epithelium ion transport, while both PGE and PGF were involved in oocyte maturation, follicular rupture and coordination of reproductive behaviors. However, little is known about the mechanisms behind their actions. In present study, we first identified the full-length ORF cDNA clones of three zebrafish prostaglandin E receptor subtype 1 (zEP(1)) isoforms - zEP(1a), zEP(1b) and zEP(1c) - and FP (zFP) from adult ovary. RT-PCR showed that zEP(1a), zEP(1b) and zFP are widely expressed in adult tissues, while zEP(1c) mRNA expression is mainly confined in brain and kidney. Using a pGL3-NFAT-RE luciferase reporter system, both zEP(1a) and zEP(1b) expressed in DF-1 cells were shown to be activated by PGE(2) potently while zEP(1c) and zFP were activated by PGF(2a) effectively, suggesting that the four receptors are functionally coupled to intracellular Ca(2+)-signaling pathway. Furthermore, EP1a and EP1b, but not EP1c were suggested to couple to cAMP-PKA signaling pathway using a pGL3-CRE luciferase reporter assay. Although zEP(1c) might originate as a paralog to zEP(1a) and zEP(1b), its functional coupling to PGF(2α) instead of PGE(2) suggested that zEP(1) isoforms might have sub-functionalized in their ligand binding and G protein coupling specificity, in addition to differential tissue distribution. Characterization of these receptors undoubtedly furthered our understanding on the diverse yet highly target-specific responses of prostaglandins in teleosts.
    General and Comparative Endocrinology 05/2012; 178(2):216-26. · 2.82 Impact Factor
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    ABSTRACT: Understanding how pathogens invade and become established in novel host populations is central to the ecology and evolution of infectious disease. Influenza viruses provide unique opportunities to study these processes in nature because of their rapid evolution, extensive surveillance, large data sets and propensity to jump species boundaries. H5N1 highly pathogenic avian influenza virus (HPAIV) is a major animal pathogen and public health threat. The virus is of particular importance in Indonesia, causing severe outbreaks among poultry and sporadic human infections since 2003. However, little is known about how H5N1 HPAIV emerged and established in Indonesia. To address these questions, we analysed Indonesian H5N1 HPAIV gene sequences isolated during 2003-2007. We find that the virus originated from a single introduction into East Java between November 2002 and October 2003. This invasion was characterized by an initially rapid burst of viral genetic diversity followed by a steady rate of lineage replacement and the maintenance of genetic diversity. Several antigenic sites in the haemagglutinin gene were subject to positive selection during the early phase, suggesting that host-immune-driven selection played a role in host adaptation and expansion. Phylogeographic analyses show that after the initial invasion of H5N1, genetic variants moved both eastwards and westwards across Java, possibly involving long-distance transportation by humans. The phylodynamics we uncover share similarities with other recently studied viral invasions, thereby shedding light on the ecological and evolutionary processes that determine disease emergence in a new geographical region.
    Molecular Ecology 05/2012; 21(12):3062-77. · 6.28 Impact Factor
  • Raymond K Hui, Frederick C Leung
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    ABSTRACT: Foot-and-mouth disease is an endemic animal disease in Hong Kong. In this study, a total of 70 clinical specimens were collected from locally infected pigs from 2001 to 2010. Phylogenetic analysis of VP1 sequences reveal that all Hong Kong FMDV serotype O isolates are classified into three lineages: HK-A and HK-B in Cathay topotype, and HK-C in SEA topotype. Regression analysis projects that the time of divergence from the most recent common ancestor of HK-A and HK-B are 1964 ± 12 and 1987 ± 9 years respectively. Although HK-B shares a common ancestor with strains that caused outbreak in Taiwan and Philippines, there is no consolidated evidence demonstrating the order of introduction events among these regions. HK-C lineage is the latest FMDV isolated in Hong Kong. This virus is likely adopted from bovine into porcine. As local pigs confer immunity mainly against Cathay topotype viruses, introduction of HK-C viruses have led into an unexpectedly high severity and rapid spreading rate of the disease. A systematic surveillance and communication network is essential to provide accurate information in controlling the pandemics.
    Veterinary Microbiology 03/2012; 159(1-2):221-9. · 3.13 Impact Factor
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    ABSTRACT: The feline gastrointestinal microbiota have direct influence on feline health and also human health as a reservoir for potential zoonotic pathogens and antibiotic resistant bacterial strains. In order to describe the feline gastrointestinal microbial diversity, fecal samples from cats have been characterized using both culture-dependent and culture-independent methods. However, data correlating total microbial composition and their functions are lacking. Present descriptive study evaluated both phylogenetic and metabolic diversity of the feline intestinal microbiota using GS Junior titanium shotgun pyrosequencing. A total of 152,494 pyrosequencing reads (5405 assembled contigs) were generated and classified into both phylogenetic and metabolic profiles of the feline intestinal microbiota. The Bacteroides/Chlorobi group was the most predominant bacterial phylum comprising ~68% of total classified diversity, followed by Firmicutes (~13%) and Proteobacteria (~6%) respectively. Archaea, fungi and viruses made up the minor communities in the overall microbial diversity. Interestingly, this study also identified a range of potential enteric zoonotic pathogens (0.02-1.25%) and genes involved in antimicrobial resistance (0.02-0.7%) in feline fecal materials. Based on clustering among nine gastrointestinal metagenomes from five different monogastric hosts (dog, human, mice, cat and chicken), the cat metagenome clustered closely together with chicken in both phylogenetic and metabolic level (>80%). Future studies are required to provide deeper understandings on both intrinsic and extrinsic effects such as impact of age, genetics and dietary interventions on the composition of the feline gastrointestinal microbiome.
    Journal of microbiological methods 03/2012; 88(3):369-76. · 2.43 Impact Factor
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    ABSTRACT: Prolactin-releasing peptide (PrRP) and its structurally related peptide, Carassius Arg-Phe-amide peptide (C-RFa), have been reported to play similar roles in regulating food intake and pituitary functions in vertebrates. However, the identity, functionality, and expression of the receptor(s) for PrRP and C-RFa remain largely unknown in nonmammalian vertebrates, including birds. In this study, three receptors homologous to mammalian PrRP receptor (PrRPR), named cPrRPR1, cPrRPR2, and cC-RFaR, respectively, were cloned from chicken brain by RT-PCR. Using a pGL3-NFAT-RE-luciferase reporter system, we demonstrated that cPrRPR1 and cPrRPR2 expressed in Chinese hamster ovarian cells could be activated by cPrRP₂₀ and cC-RFa₂₀ potently, whereas cC-RFaR could only be activated effectively by cC-RFa₂₀ (EC₅₀, 0.11 nM), indicating that cPrRPR1 and cPrRPR2 can function as common receptors for PrRP and C-RFa, whereas cC-RFaR is a receptor specific to C-RFa. Using a pGL3-CRE-luciferase reporter system, cPrRPR1, cPrRPR2, and cC-RFaR expressed in Chinese hamster ovarian cells were also shown to activate intracellular protein kinase A signaling pathway upon cC-RFa₂₀ treatment (100 nM). Moreover, RT-PCR assay revealed that cPrRPR1, cPrRPR2, and cC-RFaR were widely expressed in most adult chicken tissues examined, including various regions of brain. These findings, together with evidence of PrRP and C-RFa encoded by separate genes in chicken, Xenopus, and zebrafish, and the differential expression of PrRP and C-RFa genes in chicken tissues, strongly suggest that PrRP and C-RFa may play similar yet distinctive roles in nonmammalian vertebrates, including chicken, and their actions are mediated by common receptor(s) or a specific C-RFa receptor.
    Endocrinology 02/2012; 153(4):1861-74. · 4.72 Impact Factor
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    ABSTRACT: Pyrosequencing techniques allow scientists to perform prokaryotic genome sequencing to achieve the draft genomic sequences within a few days. However, the assemblies with shotgun sequencing are usually composed of hundreds of contigs. A further multiplex PCR procedure is needed to fill all the gaps and link contigs into complete chromosomal sequence, which is the basis for prokaryotic comparative genomic studies. In this article, we study various pyrosequencing strategies by simulated assembling from 100 prokaryotic genomes. Simulation study shows that a single end 454 Jr. run combined with a paired end 454 Jr. run (8 kb library) can produce: 1) ~90% of 100 assemblies with < 10 scaffolds and ~95% of 100 assemblies with < 150 contigs; 2) average contig N50 size is over 331 kb; 3) average single base accuracy is > 99.99%; 4) average false gene duplication rate is < 0.7%; 5) average false gene loss rate is < 0.4%. A single end 454 Jr. run combined with a paired end 454 Jr. run (8 kb library) is a cost-effective way for prokaryotic whole genome sequencing. This strategy provides solution to produce high quality draft assemblies for most of prokaryotic organisms within days. Due to the small number of assembled scaffolds, the following multiplex PCR procedure (for gap filling) would be easy. As a result, large scale prokaryotic whole genome sequencing projects may be finished within weeks.
    BMC Research Notes 01/2012; 5:80.

Publication Stats

542 Citations
308.87 Total Impact Points


  • 2013
    • Chittagong Veterinary and Animal Sciences University
      Chittagong Ghat, Chittagong, Bangladesh
    • University of Sydney
      Sydney, New South Wales, Australia
    • University of Oxford
      • Department of Zoology
      Oxford, ENG, United Kingdom
  • 2002–2013
    • The University of Hong Kong
      • School of Biological Sciences
      Hong Kong, Hong Kong
  • 2011–2012
    • Sichuan University
      • College of Life Sciences
      Chengdu, Sichuan Sheng, China
  • 2006–2011
    • China Agricultural University
      • College of Veterinary Medicine
      Beijing, Beijing Shi, China
  • 2008
    • Wuhan Institute Of Virology
      Wu-han-shih, Hubei, China
    • The Hong Kong University of Science and Technology
      • Department of Physics
      Kowloon, Hong Kong