scholarly journals Elevated CO2and Phosphate Limitation Favor Micromonas pusilla through Stimulated Growth and Reduced Viral Impact

2014 ◽  
Vol 80 (10) ◽  
pp. 3119-3127 ◽  
Author(s):  
Douwe S. Maat ◽  
Katherine J. Crawfurd ◽  
Klaas R. Timmermans ◽  
Corina P. D. Brussaard
Keyword(s):  
Latent Period ◽  
Burst Size ◽  
Virus Production ◽  
Fold Increase ◽  
Trophic Levels ◽  
Phosphate Limitation ◽  
Viral Lysis ◽  
Content Type ◽  
P Limitation ◽  
Micromonas Pusilla

ABSTRACTGrowth and viral infection of the marine picoeukaryoteMicromonas pusillawas studied under a future-ocean scenario of elevated partial CO2(pCO2; 750 μatm versus the present-day 370 μatm) and simultaneous limitation of phosphorus (P). Independent of the pCO2level, the ratios ofM. pusillacellular carbon (C) to nitrogen (N), C:P and N:P, increased with increasing P stress. Furthermore, in the P-limited chemostats at growth rates of 0.32 and 0.97 of the maximum growth rate (μmax), the supply of elevated pCO2led to an additional rise in cellular C:N and C:P ratios, as well as a 1.4-fold increase inM. pusillaabundance. Viral lysis was not affected by pCO2, but P limitation led to a 150% prolongation of the latent period (6 to 12 h) and an 80% reduction in viral burst sizes (63 viruses per cell) compared to P-replete conditions (4 to 8 h latent period and burst size of 320). Growth at 0.32 μmaxfurther prolonged the latent period by another 150% (12 to 18 h). Thus, enhanced P stress due to climate change-induced strengthened vertical stratification can be expected to lead to reduced and delayed virus production in picoeukaryotes. This effect is tempered, but likely not counteracted, by the increase in cell abundance under elevated pCO2. Although the influence of potential P-limitation-relieving factors, such as the uptake of organic P and P utilization during infection, is unclear, our current results suggest that when P limitation prevails in future oceans, picoeukaryotes and grazing will be favored over larger-sized phytoplankton and viral lysis, with increased matter and nutrient flow to higher trophic levels.

scholarly journals Characterization of the Proteomic Profiles of the Brown Tide Alga Aureoumbra lagunensis under Phosphate- and Nitrogen-Limiting Conditions and of Its Phosphate Limitation-Specific Protein with Alkaline Phosphatase Activity

2012 ◽  
Vol 78 (6) ◽  
pp. 2025-2033 ◽  
Author(s):  
Ming-Ming Sun ◽  
Jin Sun ◽  
Jian-Wen Qiu ◽  
Hongmei Jing ◽  
Hongbin Liu
Keyword(s):  
Alkaline Phosphatase ◽  
Phosphatase Activity ◽  
Alkaline Phosphatase Activity ◽  
Specific Protein ◽  
Brown Tide ◽  
Mass Spectrometry Analysis ◽  
Phosphate Limitation ◽  
Content Type ◽  
P Limitation ◽  
Aureoumbra Lagunensis

ABSTRACTThe persistent bloom of the brown tide algaAureoumbra lagunensishas been reported in coastal embayments along southern Texas, but the molecular mechanisms that sustain such algal bloom are unknown. We compared the proteome and physiological parameters ofA. lagunensisgrown in phosphate (P)-depleted, P- and nitrogen (N)-depleted, and nutrient-replete cultures. For the proteomic analysis, samples from three conditions were subjected to two-dimensional electrophoresis and tandem mass spectrometry analysis. Because of the paucity of genomic resources in this species, ade novocross-species protein search was used to identify the differentially expressed proteins, which revealed their involvement in several key biological processes, such as chlorophyll synthesis, antioxidative protection, and protein degradation, suggesting thatA. lagunensismay adopt intracellular nutrient compensation, extracellular organic nutrient regeneration, and damage protection to thrive in P-depleted environments. A highly abundant P limitation-specific protein, tentatively identified as a putative alkaline phosphatase, was further characterized by enzyme activity assay on nondenaturing gel and confocal microscopy, which confirmed that this protein has alkaline phosphatase activity, is a cytoplasmic protein, and is closely associated with the cell membrane. The abundance, location, and functional expression of this alkaline phosphatase all indicate the importance of organic P utilization forA. lagunensisunder P limitation and the possible role of this alkaline phosphatase in regenerating phosphate from extra- or intracellular organic phosphorus.

scholarly journals Lachnospiraceae and Bacteroidales Alternative Fecal Indicators Reveal Chronic Human Sewage Contamination in an Urban Harbor

2011 ◽  
Vol 77 (19) ◽  
pp. 6972-6981 ◽  
Author(s):  
Ryan J. Newton ◽  
Jessica L. VandeWalle ◽  
Mark A. Borchardt ◽  
Marc H. Gorelick ◽  
Sandra L. McLellan
Keyword(s):  
Sequence Analysis ◽  
Genetic Marker ◽  
Microbial Community Composition ◽  
Fold Increase ◽  
Fecal Pollution ◽  
Plate Count ◽  
Rrna Gene ◽  
Fecal Indicators ◽  
Fecal Indicator ◽  
Content Type

ABSTRACTThe complexity of fecal microbial communities and overlap among human and other animal sources have made it difficult to identify source-specific fecal indicator bacteria. However, the advent of next-generation sequencing technologies now provides increased sequencing power to resolve microbial community composition within and among environments. These data can be mined for information on source-specific phylotypes and/or assemblages of phylotypes (i.e., microbial signatures). We report the development of a new genetic marker for human fecal contamination identified through microbial pyrotag sequence analysis of the V6 region of the 16S rRNA gene. Sequence analysis of 37 sewage samples and comparison with database sequences revealed a human-associated phylotype within theLachnospiraceaefamily, which was closely related to the genusBlautia. This phylotype, termed Lachno2, was on average the second most abundant fecal bacterial phylotype in sewage influent samples from Milwaukee, WI. We developed a quantitative PCR (qPCR) assay for Lachno2 and used it along with the qPCR-based assays for humanBacteroidales(based on the HF183 genetic marker), totalBacteroidalesspp., and enterococci and the conventionalEscherichia coliand enterococci plate count assays to examine the prevalence of fecal and human fecal pollution in Milwaukee's harbor. Both the conventional fecal indicators and the human-associated indicators revealed chronic fecal pollution in the harbor, with significant increases following heavy rain events and combined sewer overflows. The two human-associated genetic marker abundances were tightly correlated in the harbor, a strong indication they target the same source (i.e., human sewage). Human adenoviruses were routinely detected under all conditions in the harbor, and the probability of their occurrence increased by 154% for every 10-fold increase in the human indicator concentration. Both Lachno2 and humanBacteroidalesincreased specificity to detect sewage compared to general indicators, and the relationship to a human pathogen group suggests that the use of these alternative indicators will improve assessments for human health risks in urban waters.

scholarly journals Lytic Myophage Abp53 Encodes Several Proteins Similar to Those Encoded by Host Acinetobacter baumannii and Phage phiKO2

2011 ◽  
Vol 77 (19) ◽  
pp. 6755-6762 ◽  
Author(s):  
Chia-Ni Lee ◽  
Tsai-Tien Tseng ◽  
Juey-Wen Lin ◽  
Yung-Chieh Fu ◽  
Shu-Fen Weng ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Burst Size ◽  
Sputum Sample ◽  
Polyacrylamide Gel Electrophoresis ◽  
Multiple Drug ◽  
Lytic Phage ◽  
Tail Fiber ◽  
Drug Resistant ◽  
Content Type ◽  
Multiple Drug Resistant

ABSTRACTAcinetobacter baumanniiis an important Gram-negative opportunistic pathogen causing nosocomial infections. The emergence of multiple-drug-resistantA. baumanniiisolates has increased in recent years. Directed toward phage therapy, a lytic phage ofA. baumannii, designated Abp53, was isolated from a sputum sample in this study. Abp53 has an isometric head and a contractile tail with tail fibers (belonging toMyoviridae), a latent period of about 10 min, and a burst size of approximately 150 PFU per infected cell. Abp53 could completely lyse 27% of theA. baumanniiisolates tested, which were all multiple drug resistant, but not other bacteria. Mg2+enhanced the adsorption and productivity of, and host lysis by, Abp53. Twenty Abp53 virion proteins were visualized in SDS-polyacrylamide gel electrophoresis, with a 47-kDa protein being the predicted major capsid protein. Abp53 has a double-stranded DNA genome of 95 kb. Sequence analyses of a 10-kb region revealed 8 open reading frames. Five of the encoded proteins, including 3 tail components and 2 hypothetical proteins, were similar to proteins encoded byA. baumanniistrain ACICU. ORF1176 (one of the tail components, 1,176 amino acids [aa]), which is also similar to tail protein gp21 ofKlebsiellaphage phiKO2, contained repeated domains similar to those within the ACICU_02717 protein ofA. baumanniiACICU and gp21. These findings suggest a common ancestry and horizontal gene transfer during evolution. As phages can expand the host range by domain duplication in tail fiber proteins, repeated domains in ORF1176 might have a similar significance in Abp53.

scholarly journals Role of Serum Mycoplasma pneumoniae IgA, IgM, and IgG in the Diagnosis of Mycoplasma pneumoniae-Related Pneumonia in School-Age Children and Adolescents

2016 ◽  
Vol 24 (1) ◽  
Author(s):  
Wei-Ju Lee ◽  
Eng-Yen Huang ◽  
Chih-Min Tsai ◽  
Kuang-Che Kuo ◽  
Yi-Chuan Huang ◽  
...  
Keyword(s):  
Children And Adolescents ◽  
Mycoplasma Pneumoniae ◽  
Immunoglobulin A ◽  
Fold Increase ◽  
Laboratory Diagnosis ◽  
Diagnostic Value ◽  
Immunoglobulin M ◽  
School Age Children ◽  
School Age ◽  
Content Type

ABSTRACT Mycoplasma pneumoniae is an important causative pathogen of community-acquired pneumonia in children. Rapid and reliable laboratory diagnosis of M. pneumoniae infection is important so that appropriate antibiotic treatment can be initiated to reduce the misuse of drugs and resistance rates. Anti-M. pneumoniae immunoglobulin M (IgM) is an indicator of recent primary infection but can persist for several months after initial infection. It has been suggested that anti-M. pneumoniae immunoglobulin A (IgA) can be a reliable indicator for recent M. pneumoniae infection in adults. We investigated the clinical diagnostic value of M. pneumoniae IgA in school-age children and adolescents with M. pneumoniae-related pneumonia. Eighty children with pneumonia and seropositive for M. pneumoniae IgM or with a 4-fold increase of anti-M. pneumoniae immunoglobulin G (IgG) were enrolled from May 2015 to March 2016. The titers of M. pneumoniae IgA, IgM, and IgG, the clinical features, and laboratory examinations of blood, C-reactive protein, and liver enzymes were analyzed. The initial positivity rates for M. pneumoniae IgM and IgA upon admission to the hospital were 63.6 and 33.8%, respectively. One week after admission, the cumulative positivity rates for M. pneumoniae IgM and IgA increased to 97.5 and 56.3%, respectively. Detection of M. pneumoniae IgM was more sensitive than detection of M. pneumoniae IgA for the diagnosis of M. pneumoniae-related pneumonia in school-age children and adolescents; however, paired sera are necessary for a more accurate diagnosis.

scholarly journals Metabolic Changes of Amino Acids and Flavonoids in Tea Plants in Response to Inorganic Phosphate Limitation

2018 ◽  
Vol 19 (11) ◽  
pp. 3683 ◽  
Author(s):  
Santosh KC ◽  
Meiya Liu ◽  
Qunfeng Zhang ◽  
Kai Fan ◽  
Yuanzhi Shi ◽  
...  
Keyword(s):  
Amino Acids ◽  
Inorganic Phosphate ◽  
Tea Plant ◽  
Phosphate Limitation ◽  
P Limitation ◽  
Metabolic Genes ◽  
Expression Of Genes ◽  
Tea Plants ◽  
Change Response ◽  
Tof Ms

The qualities of tea (Camellia sinensis) are not clearly understood in terms of integrated leading molecular regulatory network mechanisms behind inorganic phosphate (Pi) limitation. Thus, the present work aims to elucidate transcription factor-dependent responses of quality-related metabolites and the expression of genes to phosphate (P) starvation. The tea plant organs were subjected to metabolomics analysis by GC×GC-TOF/MS and UPLC-Q-TOF/MS along with transcription factors and 13 metabolic genes by qRT-PCR. We found P starvation upregulated SPX2 and the change response of Pi is highly dependent on young shoots. This led to increased change in abundance of carbohydrates (fructose and glucose), amino acids in leaves (threonine and methionine), and root (phenylalanine, alanine, tryptophan, and tyrosine). Flavonoids and their glycosides accumulated in leaves and root exposed to P limitation was consistent with the upregulated expression of anthocyanidin reductase (EC 1.3.1.77), leucoanthocyanidin dioxygenase (EC 1.4.11.19) and glycosyltransferases (UGT78D1, UGT78D2 and UGT57L12). Despite the similar kinetics and high correlation response of Pi and SPX2 in young shoots, predominating theanine and other amino acids (serine, threonine, glutamate, valine, methionine, phenylalanine) and catechin (EGC, EGCG and CG) content displayed opposite changes in response to Pi limitation between Fengqing and Longjing-43 tea cultivars.

scholarly journals Albumin Enhances Caspofungin Activity against Aspergillus Species by Facilitating Drug Delivery to Germinating Hyphae

2015 ◽  
Vol 60 (3) ◽  
pp. 1226-1233 ◽  
Author(s):  
Petros Ioannou ◽  
Aggeliki Andrianaki ◽  
Tonia Akoumianaki ◽  
Irene Kyrmizi ◽  
Nathaniel Albert ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Cell Culture ◽  
Antifungal Agents ◽  
Fold Increase ◽  
Culture Conditions ◽  
The Other ◽  
Related Factors ◽  
Content Type

The modestin vitroactivity of echinocandins againstAspergillusimplies that host-related factors augment the action of these antifungal agentsin vivo. We found that, in contrast to the other antifungal agents (voriconazole, amphotericin B) tested, caspofungin exhibited a profound increase in activity against variousAspergillusspecies under conditions of cell culture growth, as evidenced by a ≥4-fold decrease in minimum effective concentrations (MECs) (P= 0. 0005). Importantly, the enhanced activity of caspofungin againstAspergillusspp. under cell culture conditions was strictly dependent on serum albumin and was not observed with the other two echinocandins, micafungin and anidulafungin. Of interest, fluorescently labeled albumin bound preferentially on the surface of germinatingAspergillushyphae, and this interaction was further enhanced upon treatment with caspofungin. In addition, supplementation of cell culture medium with albumin resulted in a significant, 5-fold increase in association of fluorescently labeled caspofungin withAspergillushyphae (P< 0.0001). Collectively, we found a novel synergistic interaction between albumin and caspofungin, with albumin acting as a potential carrier molecule to facilitate antifungal drug delivery toAspergillushyphae.

scholarly journals Mutations in the two component regulator systems PmrAB and PhoPQ give rise to increased colistin resistance in Citrobacter and Enterobacter spp.

2020 ◽  
Vol 69 (4) ◽  
pp. 521-529 ◽  
Author(s):  
Matthew E. Wand ◽  
J. Mark Sutton
Keyword(s):  
Growth Rate ◽  
Type Species ◽  
Galleria Mellonella ◽  
Strain Differences ◽  
Fold Increase ◽  
Colistin Resistance ◽  
Content Type ◽  
Link Type ◽  
Carbapenem Resistant ◽  
Individual Strain

Introduction. Colistin is a last resort antibiotic for treating infections caused by carbapenem-resistant isolates. Mechanisms of resistance to colistin have been widely described in Klebsiella pneumoniae and Escherichia coli but have yet to be characterized in Citrobacter and Enterobacter species. Aim. To identify the causative mutations leading to generation of colistin resistance in Citrobacter and Enterobacter spp. Methodology. Colistin resistance was generated by culturing in increasing concentrations of colistin or by direct culture in a lethal (above MIC) concentration. Whole-genome sequencing was used to identify mutations. Fitness of resistant strains was determined by changes in growth rate, and virulence in Galleria mellonella. Results. We were able to generate colistin resistance upon exposure to sub-MIC levels of colistin, in several but not all strains of Citrobacter and Enterobacter resulting in a 16-fold increase in colistin MIC values for both species. The same individual strains also developed resistance to colistin after a single exposure at 10× MIC, with a similar increase in MIC. Genetic analysis revealed that this increased resistance was attributed to mutations in PmrB for Citrobacter and PhoP in Enterobacter , although we were not able to identify causative mutations in all strains. Colistin-resistant mutants showed little difference in growth rate, and virulence in G. mellonella, although there were strain-to-strain differences. Conclusions. Stable colistin resistance may be acquired with no loss of fitness in these species. However, only select strains were able to adapt suggesting that acquisition of colistin resistance is dependent upon individual strain characteristics.

scholarly journals Transcriptional Profiling Analysis of the Global Regulator NorG, a GntR-Like Protein of Staphylococcus aureus

2011 ◽  
Vol 193 (22) ◽  
pp. 6207-6214 ◽  
Author(s):  
Q. C. Truong-Bolduc ◽  
P. M. Dunman ◽  
T. Eidem ◽  
D. C. Hooper
Keyword(s):  
Staphylococcus Aureus ◽  
Target Genes ◽  
Efflux Pump ◽  
Transcriptional Profiling ◽  
Fold Increase ◽  
Regulatory Function ◽  
Drug Transporter ◽  
Content Type ◽  
Global Regulators ◽  
Inorganic Ion

The GntR-like protein NorG has been shown to affectStaphylococcus aureusgenes involved in resistance to quinolones and β-lactams, such as those encoding the NorB and AbcA transporters. To identify the target genes regulated by NorG, we carried out transcriptional-profiling assays usingS. aureusRN6390 and its isogenicnorG::catmutant. Our data showed that NorG positively affected the transcription of global regulatorsmgrA,arlS, andsarZ. The three putative drug efflux pump genes most positively affected by NorG were the NorB efflux pump (5.1-fold), the MmpL-like protein SACOL2566 (5.2-fold), and the BcrA-like drug transporter SACOL2525 (5.7-fold) genes. TheS. aureuspredicted MmpL protein showed 53% homology with the MmpL lipid transporter ofMycobacterium tuberculosis, and the putative SACOL2525 protein showed 87% homology with the bacitracin drug transporter BcrA ofStaphylococcus hominis. Two pump genes most negatively affected by NorG were the NorC (4-fold) and AbcA (6-fold) genes. Other categories of genes, such as those participating in amino acid, inorganic ion, or nucleotide transporters and metabolism, were also affected by NorG. Real-time reverse transcription (RT)-PCR assays formgrA,arlS,sarZ,norB,norC,abcA,mmpL, andbcrA-like were carried out to verify microarray data and showed the same level of up- or downregulation by NorG. ThenorGmutant showed a 2-fold increase in resistance to norfloxacin and rhodamine, both substrates of the NorC transporter, which is consistent with the resistance phenotype conferred by overexpression ofnorCon a plasmid. These data indicate that NorG has broad regulatory function inS. aureus.

scholarly journals Tagging Frogs with Passive Integrated Transponders Causes Disruption of the Cutaneous Bacterial Community and Proliferation of Opportunistic Fungi

2014 ◽  
Vol 80 (15) ◽  
pp. 4779-4784 ◽  
Author(s):  
Rachael E. Antwis ◽  
Gerardo Garcia ◽  
Andrea L. Fidgett ◽  
Richard F. Preziosi
Keyword(s):  
Bacterial Community ◽  
Microbial Communities ◽  
Bacterial Communities ◽  
Pathogenic Fungus ◽  
Fold Increase ◽  
Bacterial Strains ◽  
Opportunistic Fungi ◽  
Content Type ◽  
Pit Tagging

ABSTRACTSymbiotic bacterial communities play a key role in protecting amphibians from infectious diseases including chytridiomycosis, caused by the pathogenic fungusBatrachochytrium dendrobatidis. Events that lead to the disruption of the bacterial community may have implications for the susceptibility of amphibians to such diseases. Amphibians are often marked both in the wild and in captivity for a variety of reasons, and although existing literature indicates that marking techniques have few negative effects, the response of cutaneous microbial communities has not yet been investigated. Here we determine the effects of passive integrated transponder (PIT) tagging on culturable cutaneous microbial communities of captive Morelet's tree frogs (Agalychnis moreletii) and assess the isolated bacterial strains for anti-B. dendrobatidisactivityin vitro. We find that PIT tagging causes a major disruption to the bacterial community associated with the skin of frogs (∼12-fold increase in abundance), as well as a concurrent proliferation in resident fungi (up to ∼200-fold increase). Handling also caused a disruption the bacterial community, although to a lesser extent than PIT tagging. However, the effects of both tagging and handling were temporary, and after 2 weeks, the bacterial communities were similar to their original compositions. We also identify two bacterial strains that inhibitB. dendrobatidis, one of which increased in abundance on PIT-tagged frogs at 1 day postmarking, while the other was unaffected. These results show that PIT tagging has previously unobserved consequences for cutaneous microbial communities of frogs and may be particularly relevant for studies that intend to use PIT tagging to identify individuals involved in trials to develop probiotic treatments.

scholarly journals Rediscovering Zygorhizidium affluens Canter: Molecular Taxonomy, Infectious Cycle, and Cryopreservation of a Chytrid Infecting the Bloom-Forming Diatom Asterionella formosa

2018 ◽  
Vol 84 (23) ◽  
Author(s):  
Cecilia Rad-Menéndez ◽  
Mélanie Gerphagnon ◽  
Andrea Garvetto ◽  
Paola Arce ◽  
Yacine Badis ◽  
...  
Keyword(s):  
Molecular Taxonomy ◽  
Cost Effective ◽  
Trophic Levels ◽  
Content Type ◽  
Long Term Storage ◽  
Asterionella Formosa ◽  
Infectious Cycle ◽  
Cryopreservation Method ◽  
Term Storage

ABSTRACT Parasitic Chytridiomycota (chytrids) are ecologically significant in various aquatic ecosystems, notably through their roles in controlling bloom-forming phytoplankton populations and in facilitating the transfer of nutrients from inedible algae to higher trophic levels. The diversity and study of these obligate parasites, while critical to understand the interactions between pathogens and their hosts in the environment, have been hindered by challenges inherent to their isolation and stable long-term maintenance under laboratory conditions. Here, we isolated an obligate chytrid parasite (CCAP 4086/1) on the freshwater bloom-forming diatom Asterionella formosa and characterized its infectious cycle under controlled conditions. Phylogenetic analyses based on 18S, 5.8S, and 28S ribosomal DNAs (rDNAs) revealed that this strain belongs to the recently described clade SW-I within the Lobulomycetales. All morphological features observed agree with the description of the known Asterionella parasite Zygorhizidium affluens Canter. We thus provide a phylogenetic placement for this chytrid and present a robust and simple assay that assesses both the infection success and the viability of the host. We also validate a cryopreservation method for stable and cost-effective long-term storage and demonstrate its recovery after thawing. All the above-mentioned tools establish a new gold standard for the isolation and long-term preservation of parasitic aquatic chytrids, thus opening new perspectives to investigate the diversity of these organisms and their physiology in a controlled laboratory environment. IMPORTANCE Despite their ecological relevance, parasitic aquatic chytrids are understudied, especially due to the challenges associated with their isolation and maintenance in culture. Here we isolated and established a culture of a chytrid parasite infecting the bloom-forming freshwater diatom Asterionella formosa. The chytrid morphology suggests that it corresponds to the Asterionella parasite known as Zygorhizidium affluens. The phylogenetic reconstruction in the present study supports the hypothesis that our Z. affluens isolate belongs to the order Lobulomycetales and clusters within the novel clade SW-I. We also validate a cryopreservation method for stable and cost-effective long-term storage of parasitic chytrids of phytoplankton. The establishment of a monoclonal pathosystem in culture and its successful cryopreservation opens the way to further investigate this ecologically relevant parasitic interaction.

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