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Rodriguez-Valverde D, Giron JA, Hu Y, Nataro JP, Ruiz-Perez F, Santiago AE. Highly-conserved regulatory activity of the ANR family in the virulence of diarrheagenic bacteria through interaction with master and global regulators. Sci Rep 2023; 13:7024. [PMID: 37120613 PMCID: PMC10148876 DOI: 10.1038/s41598-023-33997-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Accepted: 04/22/2023] [Indexed: 05/01/2023] Open
Abstract
ANR (AraC negative regulators) are a novel class of small regulatory proteins commonly found in enteric pathogens. Aar (AggR-activated regulator), the best-characterized member of the ANR family, regulates the master transcriptional regulator of virulence AggR and the global regulator HNS in enteroaggregative Escherichia coli (EAEC) by protein-protein interactions. On the other hand, Rnr (RegA-negative regulator) is an ANR homolog identified in attaching and effacing (AE) pathogens, including Citrobacter rodentium and enteropathogenic Escherichia coli (EPEC), sharing only 25% identity with Aar. We previously found that C. rodentium lacking Rnr exhibits prolonged shedding and increased gut colonization in mice compared to the parental strain. To gain mechanistic insights into this phenomenon, we characterized the regulatory role of Rnr in the virulence of prototype EPEC strain E2348/69 by genetic, biochemical, and human organoid-based approaches. Accordingly, RNA-seq analysis revealed more than 500 genes differentially regulated by Rnr, including the type-3 secretion system (T3SS). The abundance of EspA and EspB in whole cells and bacterial supernatants confirmed the negative regulatory activity of Rnr on T3SS effectors. We found that besides HNS and Ler, twenty-six other transcriptional regulators were also under Rnr control. Most importantly, the deletion of aar in EAEC or rnr in EPEC increases the adherence of these pathogens to human intestinal organoids. In contrast, the overexpression of ANR drastically reduces bacterial adherence and the formation of AE lesions in the intestine. Our study suggests a conserved regulatory mechanism and a central role of ANR in modulating intestinal colonization by these enteropathogens despite the fact that EAEC and EPEC evolved with utterly different virulence programs.
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Affiliation(s)
- Diana Rodriguez-Valverde
- Child Health Research Center, Department of Pediatrics, University of Virginia School of Medicine, 409 Lane Road, MR-4 Building, P.O. Box 801326, Charlottesville, VA, 22908, USA
| | - Jorge A Giron
- Centro de Detección Biomolecular, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
- Translational Genomics Research Institute, 445 N. 5th St, Phoenix, AZ, 85004, USA
| | - Yang Hu
- CD Genomics, Shirley, NY, USA
| | - James P Nataro
- Child Health Research Center, Department of Pediatrics, University of Virginia School of Medicine, 409 Lane Road, MR-4 Building, P.O. Box 801326, Charlottesville, VA, 22908, USA
| | - Fernando Ruiz-Perez
- Child Health Research Center, Department of Pediatrics, University of Virginia School of Medicine, 409 Lane Road, MR-4 Building, P.O. Box 801326, Charlottesville, VA, 22908, USA
| | - Araceli E Santiago
- Child Health Research Center, Department of Pediatrics, University of Virginia School of Medicine, 409 Lane Road, MR-4 Building, P.O. Box 801326, Charlottesville, VA, 22908, USA.
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Belyea BC, Santiago AE, Vasconez WA, Nagalakshmi VK, Xu F, Mehalic TC, Sequeira-Lopez MLS, Gomez RA. A primitive type of renin-expressing lymphocyte protects the organism against infections. Sci Rep 2021; 11:7251. [PMID: 33790364 PMCID: PMC8012387 DOI: 10.1038/s41598-021-86629-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Accepted: 03/02/2021] [Indexed: 12/11/2022] Open
Abstract
The hormone renin plays a crucial role in the regulation of blood pressure and fluid-electrolyte homeostasis. Normally, renin is synthesized by juxtaglomerular (JG) cells, a specialized group of myoepithelial cells located near the entrance to the kidney glomeruli. In response to low blood pressure and/or a decrease in extracellular fluid volume (as it occurs during dehydration, hypotension, or septic shock) JG cells respond by releasing renin to the circulation to reestablish homeostasis. Interestingly, renin-expressing cells also exist outside of the kidney, where their function has remained a mystery. We discovered a unique type of renin-expressing B-1 lymphocyte that may have unrecognized roles in defending the organism against infections. These cells synthesize renin, entrap and phagocyte bacteria and control bacterial growth. The ability of renin-bearing lymphocytes to control infections-which is enhanced by the presence of renin-adds a novel, previously unsuspected dimension to the defense role of renin-expressing cells, linking the endocrine control of circulatory homeostasis with the immune control of infections to ensure survival.
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Affiliation(s)
- Brian C Belyea
- Department of Pediatrics, Child Health Research Center, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Araceli E Santiago
- Department of Pediatrics, Child Health Research Center, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Wilson A Vasconez
- Department of Pediatrics, Child Health Research Center, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Vidya K Nagalakshmi
- Department of Pediatrics, Child Health Research Center, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Fang Xu
- Department of Pediatrics, Child Health Research Center, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Theodore C Mehalic
- Department of Pediatrics, Child Health Research Center, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Maria Luisa S Sequeira-Lopez
- Department of Pediatrics, Child Health Research Center, University of Virginia School of Medicine, Charlottesville, VA, USA.
| | - R Ariel Gomez
- Department of Pediatrics, Child Health Research Center, University of Virginia School of Medicine, Charlottesville, VA, USA.
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Cunningham AL, Mann BJ, Qin A, Santiago AE, Grassel C, Lipsky M, Vogel SN, Barry EM. Characterization of Schu S4 aro mutants as live attenuated tularemia vaccine candidates. Virulence 2021; 11:283-294. [PMID: 32241221 PMCID: PMC7161688 DOI: 10.1080/21505594.2020.1746557] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
There is a need for development of an effective vaccine against Francisella tularensis, as this potential bioweapon has a high mortality rate and low infectious dose when delivered via the aerosol route. Moreover, this Tier 1 agent has a history of weaponization. We engineered targeted mutations in the Type A strain F. tularensis subspecies tularensis Schu S4 in aro genes encoding critical enzymes in aromatic amino acid biosynthesis. F. tularensis Schu S4ΔaroC, Schu S4ΔaroD, and Schu S4ΔaroCΔaroD mutant strains were attenuated for intracellular growth in vitro and for virulence in vivo and, conferred protection against pulmonary wild-type (WT) F. tularensis Schu S4 challenge in the C57BL/6 mouse model. F. tularensis Schu S4ΔaroD was identified as the most promising vaccine candidate, demonstrating protection against high-dose intranasal challenge; it protected against 1,000 CFU Schu S4, the highest level of protection tested to date. It also provided complete protection against challenge with 92 CFU of a F. tularensis subspecies holarctica strain (Type B). Mice responded to vaccination with Schu S4ΔaroD with systemic IgM and IgG2c, as well as the production of a functional T cell response as measured in the splenocyte-macrophage co-culture assay. This vaccine was further characterized for dissemination, histopathology, and cytokine/chemokine gene induction at defined time points following intranasal vaccination which confirmed its attenuation compared to WT Schu S4. Cytokine, chemokine, and antibody induction patterns compared to wild-type Schu S4 distinguish protective vs. pathogenic responses to F. tularensis and elucidate correlates of protection associated with vaccination against this agent.
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Affiliation(s)
| | - Barbara J Mann
- Department of Medicine, Division of Infectious Diseases and International Heath, University of Virginia, Charlottesville, VA, USA
| | - Aiping Qin
- Department of Medicine, Division of Infectious Diseases and International Heath, University of Virginia, Charlottesville, VA, USA
| | - Araceli E Santiago
- Department of Pediatrics, University of Virginia, Charlottesville, VA, USA
| | - Christen Grassel
- Center for Vaccine Development, University of Maryland Baltimore, Baltimore, MD, USA
| | - Michael Lipsky
- Department of Pathology, University of Maryland Baltimore, Baltimore, MD, USA
| | - Stefanie N Vogel
- Department of Microbiology and Immunology, University of Maryland Baltimore, Baltimore, MD, USA
| | - Eileen M Barry
- Center for Vaccine Development, University of Maryland Baltimore, Baltimore, MD, USA
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Boisen N, Østerlund MT, Joensen KG, Santiago AE, Mandomando I, Cravioto A, Chattaway MA, Gonyar LA, Overballe-Petersen S, Stine OC, Rasko DA, Scheutz F, Nataro JP. Redefining enteroaggregative Escherichia coli (EAEC): Genomic characterization of epidemiological EAEC strains. PLoS Negl Trop Dis 2020; 14:e0008613. [PMID: 32898134 PMCID: PMC7500659 DOI: 10.1371/journal.pntd.0008613] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Revised: 09/18/2020] [Accepted: 07/20/2020] [Indexed: 11/19/2022] Open
Abstract
Although enteroaggregative E. coli (EAEC) has been implicated as a common cause of diarrhea in multiple settings, neither its essential genomic nature nor its role as an enteric pathogen are fully understood. The current definition of this pathotype requires demonstration of cellular adherence; a working molecular definition encompasses E. coli which do not harbor the heat-stable or heat-labile toxins of enterotoxigenic E. coli (ETEC) and harbor the genes aaiC, aggR, and/or aatA. In an effort to improve the definition of this pathotype, we report the most definitive characterization of the pan-genome of EAEC to date, applying comparative genomics and functional characterization on a collection of 97 EAEC strains isolated in the course of a multicenter case-control diarrhea study (Global Enteric Multi-Center Study, GEMS). Genomic analysis revealed that the EAEC strains mapped to all phylogenomic groups of E. coli. Circa 70% of strains harbored one of the five described AAF variants; there were no additional AAF variants identified, and strains that lacked an identifiable AAF generally did not have an otherwise complete AggR regulon. An exception was strains that harbored an ETEC colonization factor (CF) CS22, like AAF a member of the chaperone-usher family of adhesins, but not phylogenetically related to the AAF family. Of all genes scored, sepA yielded the strongest association with diarrhea (P = 0.002) followed by the increased serum survival gene, iss (p = 0.026), and the outer membrane protease gene ompT (p = 0.046). Notably, the EAEC genomes harbored several genes characteristically associated with other E. coli pathotypes. Our data suggest that a molecular definition of EAEC could comprise E. coli strains harboring AggR and a complete AAF(I-V) or CS22 gene cluster. Further, it is possible that strains meeting this definition could be both enteric bacteria and urinary/systemic pathogens.
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Affiliation(s)
- Nadia Boisen
- Statens Serum Institut, Department of Bacteria, Parasites and Fungi, Copenhagen, Denmark
| | - Mark T. Østerlund
- Statens Serum Institut, Department of Bacteria, Parasites and Fungi, Copenhagen, Denmark
| | - Katrine G. Joensen
- Statens Serum Institut, Department of Bacteria, Parasites and Fungi, Copenhagen, Denmark
| | - Araceli E. Santiago
- University of Virginia School of Medicine, Department of Pediatrics, Charlottesville, Virginia, United States of America
| | - Inacio Mandomando
- Centro de Investigação em Saúde da Manhiça (CISM), Maputo, Mozambique
| | - Alejandro Cravioto
- Universidad Nacional Autónoma de México, Faculty of Medicine, Mexico City, Mexico
| | - Marie A. Chattaway
- Public Health England, Gastrointestinal Bacteria Reference Unit (GBRU), Colindale, United Kingdom
| | - Laura A. Gonyar
- University of Virginia School of Medicine, Department of Pediatrics, Charlottesville, Virginia, United States of America
| | | | - O. Colin Stine
- University of Maryland School of Medicine, Department of Epidemiology and Public Health, Baltimore, Maryland, United States of America
| | - David A. Rasko
- University of Maryland School of Medicine, Institute for Genome Sciences, Department of Microbiology and Immunology, Baltimore, Maryland, United States of America
| | - Flemming Scheutz
- Statens Serum Institut, Department of Bacteria, Parasites and Fungi, Copenhagen, Denmark
| | - James P. Nataro
- University of Virginia School of Medicine, Department of Pediatrics, Charlottesville, Virginia, United States of America
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Belmont-Monroy L, Saitz-Rojas W, Soria-Bustos J, Mickey AS, Sherman NE, Orsburn BC, Ruiz-Perez F, Santiago AE. Characterization of a novel AraC/XylS-regulated family of N-acyltransferases in pathogens of the order Enterobacterales. PLoS Pathog 2020; 16:e1008776. [PMID: 32845938 PMCID: PMC7478709 DOI: 10.1371/journal.ppat.1008776] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 09/08/2020] [Accepted: 07/04/2020] [Indexed: 11/18/2022] Open
Abstract
Enteroaggregative Escherichia coli (EAEC) is a diarrheagenic pathotype associated with traveler’s diarrhea, foodborne outbreaks and sporadic diarrhea in industrialized and developing countries. Regulation of virulence in EAEC is mediated by AggR and its negative regulator Aar. Together, they control the expression of at least 210 genes. On the other hand, we observed that about one third of Aar-regulated genes are related to metabolism and transport. In this study we show the AggR/Aar duo controls the metabolism of lipids. Accordingly, we show that AatD, encoded in the AggR-regulated aat operon (aatPABCD) is an N-acyltransferase structurally similar to the essential Apolipoprotein N-acyltransferase Lnt and is required for the acylation of Aap (anti-aggregation protein). Deletion of aatD impairs post-translational modification of Aap and causes its accumulation in the bacterial periplasm. trans-complementation of 042aatD mutant with the AatD homolog of ETEC or with the N-acyltransferase Lnt reestablished translocation of Aap. Site-directed mutagenesis of the E207 residue in the putative acyltransferase catalytic triad disrupted the activity of AatD and caused accumulation of Aap in the periplasm due to reduced translocation of Aap at the bacterial surface. Furthermore, Mass spectroscopy revealed that Aap is acylated in a putative lipobox at the N-terminal of the mature protein, implying that Aap is a lipoprotein. Lastly, deletion of aatD impairs bacterial colonization of the streptomycin-treated mouse model. Our findings unveiled a novel N-acyltransferase family associated with bacterial virulence, and that is tightly regulated by AraC/XylS regulators in the order Enterobacterales. Although the regulatory scheme of AggR is well understood, the biological relevance of half of AggR-regulated proteins remains unknown. In this study we provide experimental evidence that the AggR-regulated AatD is a novel N-acyltransferase restricted to pathogens of the order Enterobacterales, including EAEC, ETEC, Yersinia sp., and C. rodentium. AatD is structurally similar to Lnt. However, unlike Lnt which is essential for cellular functions, AatD is a dedicated N-acyltransferase required for post-translational modification of virulence factors. Aap was identified as a lipoprotein acylated by AatD. Lipid modification in Aap provides an important post-translational mechanism to regulate the trafficking, stability and subcellular localization of Aap. In the absence of AatD, Aap is retained in the periplasmic space and cannot be translocated to the bacterial surface, presumably, restricting the biological function of the protein. Our data suggest that AggR and Aar virulence regulators, not only regulate the expression of Aap virulence factor at the transcriptional level, but also regulate translocation of Aap to the bacterial surface, which is required for full virulence of EAEC, unveiling an important mechanism of virulence regulation.
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Affiliation(s)
- Laura Belmont-Monroy
- Department of Pediatrics, University of Virginia School of Medicine and University of Virginia Children’s Hospital, Charlottesville, Virginia, United States of America
- Department of Public Health, UNAM School of Medicine and Federico Gomez Children’s Hospital, Mexico City, Mexico
| | - Waleska Saitz-Rojas
- Department of Pediatrics, University of Virginia School of Medicine and University of Virginia Children’s Hospital, Charlottesville, Virginia, United States of America
| | - Jorge Soria-Bustos
- Department of Pediatrics, University of Virginia School of Medicine and University of Virginia Children’s Hospital, Charlottesville, Virginia, United States of America
| | - Abigail S. Mickey
- Department of Pediatrics, University of Virginia School of Medicine and University of Virginia Children’s Hospital, Charlottesville, Virginia, United States of America
| | - Nicholas E. Sherman
- W. M. Keck Biomedical Mass Spectrometry Lab. University of Virginia, Charlottesville, Virginia, United States of America
| | - Benjamin C. Orsburn
- W. M. Keck Biomedical Mass Spectrometry Lab. University of Virginia, Charlottesville, Virginia, United States of America
| | - Fernando Ruiz-Perez
- Department of Pediatrics, University of Virginia School of Medicine and University of Virginia Children’s Hospital, Charlottesville, Virginia, United States of America
| | - Araceli E. Santiago
- Department of Pediatrics, University of Virginia School of Medicine and University of Virginia Children’s Hospital, Charlottesville, Virginia, United States of America
- * E-mail: .
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Aijuka M, Santiago AE, Girón JA, Nataro JP, Buys EM. Escherichia coli isolated from food sources and irrigation water: A potential risk for causing intestinal dysfunction? Food Control 2019. [DOI: 10.1016/j.foodcont.2019.03.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Borgersen Q, Bolick DT, Kolling GL, Aijuka M, Ruiz-Perez F, Guerrant RL, Nataro JP, Santiago AE. Abundant production of exopolysaccharide by EAEC strains enhances the formation of bacterial biofilms in contaminated sprouts. Gut Microbes 2018; 9:264-278. [PMID: 29543544 PMCID: PMC6219584 DOI: 10.1080/19490976.2018.1429877] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 01/02/2018] [Accepted: 01/12/2018] [Indexed: 02/03/2023] Open
Abstract
Enteroaggregative E. coli (EAEC) is associated with food-borne outbreaks of diarrhea and growth faltering among children in developing countries. A Shiga toxin-producing EAEC strain of serotype O104:H4 strain caused one of the largest outbreaks of a food-borne infection in Europe in 2011. The outbreak was traced to contaminated fenugreek sprouts, yet the mechanisms whereby such persistent contamination of sprouts could have occurred are not clear. We found that under ambient conditions of temperature and in minimal media, pathogenic Shiga toxin-producing EAEC O104:H4 227-11 and non-Shiga toxin-producing 042 strains both produce high levels of exopolysaccharide structures (EPS) that are released to the external milieu. The exopolysaccharide was identified as colanic acid (CA). Unexpectedly, Shiga-toxin producing EAEC strain 227-11 produced 3-6-fold higher levels of CA than the 042 strain, suggesting differential regulation of the CA in the two strains. The presence of CA was accompanied by the formation of large biofilm structures on the surface of sprouts. The wcaF-wza chromosomal locus was required for the synthesis of CA in EAEC 042. Deletion in the glycosyltransferase wcaE gene abolished the production of CA in 042, and resulted in diminished adherence to sprouts when co-cultured at ambient temperature. In conclusion, this work suggests that copious production of CA may contribute to persistence of EAEC in the environment and suggests a potential explanation for the large Shiga toxin-producing EAEC outbreak in 2011.
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Affiliation(s)
- Quintin Borgersen
- Department of Pediatrics, University of Virginia School of Medicine and University of Virginia Children's Hospital, Charlottesville, Virginia
| | - David T. Bolick
- Center for Global Health, Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, VA , USA
| | - Glynis L. Kolling
- Center for Global Health, Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, VA , USA
| | - Matthew Aijuka
- Department of Pediatrics, University of Virginia School of Medicine and University of Virginia Children's Hospital, Charlottesville, Virginia
| | - Fernando Ruiz-Perez
- Department of Pediatrics, University of Virginia School of Medicine and University of Virginia Children's Hospital, Charlottesville, Virginia
| | - Richard L. Guerrant
- Center for Global Health, Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, VA , USA
| | - James P. Nataro
- Department of Pediatrics, University of Virginia School of Medicine and University of Virginia Children's Hospital, Charlottesville, Virginia
| | - Araceli E. Santiago
- Department of Pediatrics, University of Virginia School of Medicine and University of Virginia Children's Hospital, Charlottesville, Virginia
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Santiago AE, Yan MB, Hazen TH, Sauder B, Meza-Segura M, Rasko DA, Kendall MM, Ruiz-Perez F, Nataro JP. The AraC Negative Regulator family modulates the activity of histone-like proteins in pathogenic bacteria. PLoS Pathog 2017; 13:e1006545. [PMID: 28806780 PMCID: PMC5570504 DOI: 10.1371/journal.ppat.1006545] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 08/24/2017] [Accepted: 07/20/2017] [Indexed: 02/04/2023] Open
Abstract
The AraC Negative Regulators (ANR) comprise a large family of virulence regulators distributed among diverse clinically important Gram-negative pathogens, including Vibrio spp., Salmonella spp., Shigella spp., Yersinia spp., Citrobacter spp., and pathogenic E. coli strains. We have previously reported broad effects of the ANR members on regulators of the AraC/XylS family. Here, we interrogate possible broader effects of the ANR members on the bacterial transcriptome. Our studies focused on Aar (AggR-activated regulator), an ANR family archetype in enteroaggregative E. coli (EAEC) isolate 042. Transcriptome analysis of EAEC strain 042, 042aar and 042aar(pAar) identified more than 200 genes that were differentially expressed (+/- 1.5 fold, p<0.05). Most of those genes are located on the bacterial chromosome (195 genes, 92.85%), and are associated with regulation, transport, metabolism, and pathogenesis, based on the predicted annotation; a considerable number of Aar-regulated genes encoded for hypothetical proteins (46 genes, 21.9%) and regulatory proteins (25, 11.9%). Notably, the transcriptional expression of three histone-like regulators, H-NS (orf1292), H-NS homolog (orf2834) and StpA, was down-regulated in the absence of aar and may explain some of the effects of Aar on gene expression. By employing a bacterial two-hybrid system, LacZ reporter assays, pull-down and electrophoretic mobility shift assay (EMSA) analysis, we demonstrated that Aar binds directly to H-NS and modulates H-NS-induced gene silencing. Importantly, Aar was highly expressed in the mouse intestinal tract and was found to be necessary for maximal H-NS expression. In conclusion, this work further extends our knowledge of genes under the control of Aar and its biological relevance in vivo. The AraC Negative Regulators (ANR) is a large family of negative regulators distributed in several clinically relevant Gram-negative pathogens, including Vibrio spp., Salmonella spp., Shigella spp., Yersinia spp., Citrobacter spp., pathogenic E. coli, and members of the Pasteurellaceae. Previously, we showed that the ANR family suppresses transcriptional expression of virulence factors such as fimbriae, toxins, and the type VI secretion system by directly down-regulating AraC/XylS master regulators. Transcriptome and biochemical analysis of Aar (AggR-activated regulator), an ANR family archetype in enteroaggregative E. coli (EAEC) 042, demonstrated that Aar binds directly to H-NS and modulates the H-NS-induced gene expression. Accordingly, mutation of aar decreased expression of the H-NS-regulated Lpf fimbriae, LPS-related enzymes, GadXW operon and porins. Importantly, Aar was highly expressed in the mouse intestinal tract and was found to be necessary for maximal H-NS expression. These findings unveil an exquisite regulatory network in pathogenic bacteria, which operates by concomitant control of master transcriptional regulators of the AraC family and global negative H-NS regulators.
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Affiliation(s)
- Araceli E. Santiago
- Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
- * E-mail:
| | - Michael B. Yan
- Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
| | - Tracy H. Hazen
- Institute for Genome Sciences, Department of Microbiology and Immunology. University of Maryland, Baltimore, Maryland, United States of America
| | - Brooke Sauder
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia, United States of America
| | - Mario Meza-Segura
- Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
| | - David A. Rasko
- Institute for Genome Sciences, Department of Microbiology and Immunology. University of Maryland, Baltimore, Maryland, United States of America
| | - Melissa M. Kendall
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia, United States of America
| | - Fernando Ruiz-Perez
- Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
| | - James P. Nataro
- Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
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Santiago AE, Yan MB, Tran M, Wright N, Luzader DH, Kendall MM, Ruiz-Perez F, Nataro JP. A large family of anti-activators accompanying XylS/AraC family regulatory proteins. Mol Microbiol 2016; 101:314-32. [PMID: 27038276 PMCID: PMC4983702 DOI: 10.1111/mmi.13392] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/01/2016] [Indexed: 11/29/2022]
Abstract
AraC Negative Regulators (ANR) suppress virulence genes by directly down‐regulating AraC/XylS members in Gram‐negative bacteria. In this study, we sought to investigate the distribution and molecular mechanisms of regulatory function for ANRs among different bacterial pathogens. We identified more than 200 ANRs distributed in diverse clinically important gram negative pathogens, including Vibrio spp., Salmonella spp., Shigella spp., Yersinia spp., Citrobacter spp., enterotoxigenic (ETEC) and enteroaggregative E. coli (EAEC), and members of the Pasteurellaceae. By employing a bacterial two hybrid system, pull down assays and surface plasmon resonance (SPR) analysis, we demonstrate that Aar (AggR‐activated regulator), a prototype member of the ANR family in EAEC, binds with high affinity to the central linker domain of AraC‐like member AggR. ANR‐AggR binding disrupted AggR dimerization and prevented AggR‐DNA binding. ANR homologs of Vibrio cholerae, Citrobacter rodentium, Salmonella enterica and ETEC were capable of complementing Aar activity by repressing aggR expression in EAEC strain 042. ANR homologs of ETEC and Vibrio cholerae bound to AggR as well as to other members of the AraC family, including Rns and ToxT. The predicted proteins of all ANR members exhibit three highly conserved predicted α‐helices. Site‐directed mutagenesis studies suggest that at least predicted α‐helices 2 and 3 are required for Aar activity. In sum, our data strongly suggest that members of the novel ANR family act by directly binding to their cognate AraC partners.
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Affiliation(s)
- Araceli E Santiago
- Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Michael B Yan
- Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Minh Tran
- Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Nathan Wright
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, VA, USA
| | - Deborah H Luzader
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, School of Medicine, Charlottesville, VA, USA
| | - Melissa M Kendall
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, School of Medicine, Charlottesville, VA, USA
| | - Fernando Ruiz-Perez
- Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - James P Nataro
- Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, VA, USA.,Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, School of Medicine, Charlottesville, VA, USA
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Santiago AE, Mann BJ, Qin A, Cunningham AL, Cole LE, Grassel C, Vogel SN, Levine MM, Barry EM. Characterization of Francisella tularensis Schu S4 defined mutants as live-attenuated vaccine candidates. Pathog Dis 2015; 73:ftv036. [PMID: 25986219 PMCID: PMC4462183 DOI: 10.1093/femspd/ftv036] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/10/2015] [Indexed: 01/11/2023] Open
Abstract
Francisella tularensis (Ft), the etiological agent of tularemia and a Tier 1 select agent, has been previously weaponized and remains a high priority for vaccine development. Ft tularensis (type A) and Ft holarctica (type B) cause most human disease. We selected six attenuating genes from the live vaccine strain (LVS; type B), F. novicida and other intracellular bacteria: FTT0507, FTT0584, FTT0742, FTT1019c (guaA), FTT1043 (mip) and FTT1317c (guaB) and created unmarked deletion mutants of each in the highly human virulent Ft strain Schu S4 (Type A) background. FTT0507, FTT0584, FTT0742 and FTT1043 Schu S4 mutants were not attenuated for virulence in vitro or in vivo. In contrast, Schu S4 gua mutants were unable to replicate in murine macrophages and were attenuated in vivo, with an i.n. LD50 > 105 CFU in C57BL/6 mice. However, the gua mutants failed to protect mice against lethal challenge with WT Schu S4, despite demonstrating partial protection in rabbits in a previous study. These results contrast with the highly protective capacity of LVS gua mutants against a lethal LVS challenge in mice, and underscore differences between these strains and the animal models in which they are evaluated, and therefore have important implications for vaccine development. Mutations in guanine biosynthesis genes, but not in four other hypothetical virulence factors in highly virulent Francisella tularensis strain Schu S4 resulted in attenuation in macrophage replication and mouse virulence.
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Affiliation(s)
- Araceli E Santiago
- Departments of Pediatrics, University of Virginia Children's Hospital, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Barbara J Mann
- Department of Medicine, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Aiping Qin
- Department of Medicine, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Aimee L Cunningham
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Leah E Cole
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Christen Grassel
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Stefanie N Vogel
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Myron M Levine
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Eileen M Barry
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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Ayala-Lujan JL, Vijayakumar V, Gong M, Smith R, Santiago AE, Ruiz-Perez F. Broad spectrum activity of a lectin-like bacterial serine protease family on human leukocytes. PLoS One 2014; 9:e107920. [PMID: 25251283 PMCID: PMC4176022 DOI: 10.1371/journal.pone.0107920] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Accepted: 08/25/2014] [Indexed: 11/21/2022] Open
Abstract
The serine protease autotransporter from Enterobacteriaceae (SPATE) family, which number more than 25 proteases with apparent diverse functions, have been phylogenetically divided into two distinct classes, designated 1 and 2. We recently demonstrated that Pic and Tsh, two members of the class-2 SPATE family produced by intestinal and extraintestinal pathogenic E. coli, were able to cleave a number of O-glycosylated proteins on neutrophils and lymphocytes resulting in impaired leukocyte functions. Here we show that most members of the class-2 SPATE family have lectin-like properties and exhibit differential protease activity reliant on glycoprotein type and cell lineage. Protease activity was seen in virtually all tested O-glycosylated proteins including CD34, CD55, CD164, TIM1, TIM3, TIM4 and C1-INH. We also show that although SPATE proteins bound and cleaved glycoproteins more efficiently on granulocytes and monocytes, they also targeted glycoproteins on B, T and natural killer lymphocytes. Finally, we found that the characteristic domain-2 of class-2 SPATEs is not required for glycoprotease activity, but single amino acid mutations in Pic domain-1 to those residues naturally occurring in domain-1 of SepA, were sufficient to hamper Pic glycoprotease activity. This study shows that most class-2 SPATEs have redundant activities and suggest that they may function as immunomodulators at several levels of the immune system.
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Affiliation(s)
- Jorge Luis Ayala-Lujan
- Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
- Unidad Academica de Ciencias Quimicas, Universidad Autonoma de Zacatecas, Zacatecas, Mexico
| | - Vidhya Vijayakumar
- Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
- Department of Immunology and Microbiology, University of Maryland at Baltimore, Baltimore, Maryland, United States of America
| | - Mei Gong
- Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
| | - Rachel Smith
- Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
| | - Araceli E. Santiago
- Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
| | - Fernando Ruiz-Perez
- Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
- * E-mail:
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Santiago AE, Ruiz-Perez F, Jo NY, Vijayakumar V, Gong MQ, Nataro JP. A large family of antivirulence regulators modulates the effects of transcriptional activators in Gram-negative pathogenic bacteria. PLoS Pathog 2014; 10:e1004153. [PMID: 24875828 PMCID: PMC4038620 DOI: 10.1371/journal.ppat.1004153] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Accepted: 04/16/2014] [Indexed: 11/21/2022] Open
Abstract
We have reported that transcription of a hypothetical small open reading frame (orf60) in enteroaggregative E. coli (EAEC) strain 042 is impaired after mutation of aggR, which encodes a global virulence activator. We have also reported that the cryptic orf60 locus was linked to protection against EAEC diarrhea in two epidemiologic studies. Here, we report that the orf60 product acts as a negative regulator of aggR itself. The orf60 protein product lacks homology to known repressors, but displays 44–100% similarity to at least fifty previously undescribed small (<10 kDa) hypothetical proteins found in many gram negative pathogen genomes. Expression of orf60 homologs from enterotoxigenic E. coli (ETEC) repressed the expression of the AraC-transcriptional ETEC regulator CfaD/Rns and its regulon in ETEC strain H10407. Complementation in trans of EAEC 042orf60 by orf60 homologs from ETEC and the mouse pathogen Citrobacter rodentium resulted in dramatic suppression of aggR. A C. rodentium orf60 homolog mutant showed increased levels of activator RegA and increased colonization of the adult mouse. We propose the name Aar (AggR-activated regulator) for the clinically and epidemiologically important orf60 product in EAEC, and postulate the existence of a large family of homologs among pathogenic Enterobacteriaceae and Pasteurellaceae. We propose the name ANR (AraC Negative Regulators) for this family. We report here the identification and characterization of a new family of negative regulators in Gram-negative bacteria, including many pathotypes of diarrheagenic Enterobacteriaceae and members of the Pasteurellaceae. Members of this regulator family in enteroaggregative (EAEC) and enterotoxigenic E. coli (ETEC) and in Citrobacter rodentium downregulate the expression of positive regulator partners AggR, CfaD/Rns and RegA, respectively, all members of the AraC/XylS family of regulators. Accordingly, we propose the name ANR (AraC Negative Regulators) for this family. ANR members orf60 (termed Aar), orf02851 (Rnr), orf0450 and orf01070 (Cnr) from EAEC, C. rodentium and ETEC respectively were characterized in this study. Deletion of ANR homologs upregulated the expression of AggR and RegA in EAEC strain 042 and C. rodentium respectively; overexpression of orf60, orf02851, orf0450 and orf01070 in EAEC strain 042 down-regulated AggR. C. rodentium harboring a null mutation in orf02851 exhibited a significant increase in expression of the regA and RegA-regulated fimbriae. The orf02851 mutant showed higher levels of C. rodentium in feces and colonic contents, and greater weight loss compared to mice inoculated with the wild-type.
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Affiliation(s)
- Araceli E. Santiago
- Department of Pediatrics, University of Virginia School of Medicine and University of Virginia Children's Hospital, Charlottesville, Virginia, United States of America
- * E-mail:
| | - Fernando Ruiz-Perez
- Department of Pediatrics, University of Virginia School of Medicine and University of Virginia Children's Hospital, Charlottesville, Virginia, United States of America
| | - Noah Y. Jo
- Department of Pediatrics, University of Virginia School of Medicine and University of Virginia Children's Hospital, Charlottesville, Virginia, United States of America
| | - Vidhya Vijayakumar
- Department of Pediatrics, University of Virginia School of Medicine and University of Virginia Children's Hospital, Charlottesville, Virginia, United States of America
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Mei Q. Gong
- Department of Pediatrics, University of Virginia School of Medicine and University of Virginia Children's Hospital, Charlottesville, Virginia, United States of America
| | - James P. Nataro
- Department of Pediatrics, University of Virginia School of Medicine and University of Virginia Children's Hospital, Charlottesville, Virginia, United States of America
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Ohtake S, Martin RA, Saxena A, Lechuga-Ballesteros D, Santiago AE, Barry EM, Truong-Le V. Formulation and stabilization of Francisella tularensis live vaccine strain. J Pharm Sci 2011; 100:3076-3087. [PMID: 21491457 DOI: 10.1002/jps.22563] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Revised: 02/04/2011] [Accepted: 03/09/2011] [Indexed: 11/10/2022]
Abstract
Francisella tularensis live vaccine strain (F. tularensis LVS), a promising vaccine candidate for protection against F. tularensis exposure, is a particularly thermolabile vaccine and difficult to stabilize sufficiently for storage under refrigerated conditions. Our preliminary data show that F. tularensis LVS can be stabilized in the dried state using foam drying, a modified freeze drying method, with sugar-based formulations. The process was conducted under mild drying conditions, which resulted in a good titer retention following processing. The inclusion of osmolytes in the growth media resulted in an acceleration of growth kinetics, although no change in osmotolerance was observed. The optimized F. tularensis formulation, which contained trehalose, gelatin, and Pluronic F68 demonstrated stability for approximately 1.5 weeks at 37°C (i.e., time required for the vaccine to decrease in potency by 1 log(10) colony forming unit) and for 12 weeks at 25°C. At refrigerator storage condition (4°C), stabilized F. tularensis LVS vaccine exhibited no activity loss for at least 12 weeks. This stabilization method utilizes conventional freeze dryers and pharmaceutically approved stabilizers, and thus can be readily implemented at many manufacturing sites for large-scale production of stabilized vaccines. The improved heat stability of the F. tularensis LVS could mitigate risks of vaccine potency loss during long-term storage, shipping, and distribution.
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Affiliation(s)
| | | | - Atul Saxena
- Aridis Pharmaceuticals, San Jose, California 95138
| | | | - Araceli E Santiago
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Eileen M Barry
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Vu Truong-Le
- Aridis Pharmaceuticals, San Jose, California 95138.
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Abstract
Francisella tularensis is a Category A select agent for which vaccine and countermeasure development are a priority. In the past eight years, renewed interest in this pathogen has led to the generation of an enormous amount of new data on both the pathogen itself and its interaction with host cells. This information has fostered the development of various vaccine candidates including acellular subunit, killed whole cell and live attenuated. This review summarizes the progress and promise of these various candidates.
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Affiliation(s)
- Eileen M Barry
- University of Maryland School of Medicine, Center for Vaccine Development, Baltimore, MD, USA.
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Santiago AE, Cole LE, Franco A, Vogel SN, Levine MM, Barry EM. Characterization of rationally attenuated Francisella tularensis vaccine strains that harbor deletions in the guaA and guaB genes. Vaccine 2009; 27:2426-36. [PMID: 19368784 DOI: 10.1016/j.vaccine.2009.02.073] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2008] [Revised: 02/02/2009] [Accepted: 02/05/2009] [Indexed: 12/23/2022]
Abstract
Francisella tularensis, the etiologic agent of tularemia, can cause severe and fatal infection after inhalation of as few as 10 -- 100CFU. F. tularensis is a potential bioterrorism agent and, therefore, a priority for countermeasure development. Vaccination with the live vaccine strain (LVS), developed from a Type B strain, confers partial protection against aerosal exposure to the more virulent Type A strains and provides proof of principle that a live attenuated vaccine strain may be efficacious. However LVS suffers from several notable drawbacks that have prevented its licensure and widespread use. To address the specific deficiencies that render LVS a sub-optimal tularemia vaccine, we engineered F. tularensis LVS strains with targeted deletions in the guaA or guaB genes that encode critical enzymes in the guanine nucleotide biosynthetic pathway. F. tularensis LVSDeltaguaA and LVSDeltaguaB mutants were guanine auxotrophs and were highly attenuated in a mouse model of infection. While the mutants failed to replicate in macrophages, a robust proinflammatory cytokine response, equivalent to that of the parental LVS, was elicited. Mice vaccinated with a single dose of the F. tularensis LVSDeltaguaA or LVSDeltaguaB mutant were fully protected against subsequent lethal challenge with the LVS parental strain. These findings suggest the specific deletion of these target genes could generate a safe and efficacious live attenuated vaccine.
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Affiliation(s)
- Araceli E Santiago
- Center for Vaccine Development, University of Maryland, Baltimore, 21201, United States
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Santiago AE, Arcilla RP. Tilapia cage culture and the dissolved oxygen trends in Sampaloc Lake, the Philippines. Environ Monit Assess 1993; 24:243-255. [PMID: 24227382 DOI: 10.1007/bf00545981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/1991] [Indexed: 06/02/2023]
Abstract
The 28-hectare tilapia cage culture that occupied the 104-hectare Sampaloc Lake, a crater lake, shifted to intensive method in 1986 when tilapia growth slowed done at the beginning of 1982. Thus, commercial feeds became the main source of allochthonous organic matter in the lake. Total feeds given annually for the 28-hectare cage culture at 3 croppings per year amounted to 5250 tons. At feed conversion ratio of 1 : 2 a significant portion of the feeds given ended as organic wastes in the lake. In 1988, tilapia cage operators began experiencing their worst occurrences of fishkill, worth millions of pesos. An assessment of the dissolved oxygen condition of Sampaloc lake in late 1989, 1990 and mid-1991 showed ominous trends which might adversely affect the use of Sampaloc lake for fishery.
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Affiliation(s)
- A E Santiago
- Binangonan Freshwater Station, Southeast Asian Fisheries Development Center, Binangonan, Rizal, Philippines
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Abstract
The ecological role of seawater intrusion in Laguna de Bay is assessed due to the operation of the Napindan Hydraulic Control Structure (NHCS). Turbidity is recognized as one limiting factor in the lake's biological productivity. Hence, to stop the natural backflow of seawater to Laguna de Bay removes one important contributory factor in facilitating an early water clearing of Laguna de Bay for a higher annual biological productivity.
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Affiliation(s)
- A E Santiago
- Binangonan Freshwater Station, Southeast Asian Fisheries Development Center, Binangonan, Rizal, Philippines
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