scholarly journals Biofilms and Extracts from Bacteria Producing "Quorum Sensing" Signaling Molecules Promote Chemotaxis and Settlement Behaviors in Hydractinia symbiolongicarpus (Cnidaria: Hydrozoa) Larvae

2019 ◽  
Vol 24 (1) ◽  
pp. 150-162 ◽  
Author(s):  
Angel G. Franco ◽  
Luis F. Cadavid ◽  
Catalina Arévalo-Ferro
Keyword(s):  
Quorum Sensing ◽  
Marine Invertebrates ◽  
Shigella Flexneri ◽  
Life Cycles ◽  
Hermit Crabs ◽  
Substrate Selection ◽  
Bacterial Strains ◽  
Hydractinia Symbiolongicarpus ◽  
Larval Attachment ◽  
Rdna Sequencing

Many sessile marine invertebrates have life cycles involving the development of larvae that settle on specific substrates to initiate metamorphosis to juvenile forms. Although is recognized that bacterial biofilms play a role in this process, the responsible chemical cues are beginning to be investigated. Here, we tested the role of substrate-specific bacteria biofilms and their Quorum Sensing Signaling Molecule (QSSM) extracts on chemotaxis and settlement of larvae from Hydractinia symbiolongicarpus, a hydroid that grows on gastropod shells occupied by hermit crabs. We isolated and taxonomically identified by 16S rDNA sequencing, 14 bacterial strains from shells having H. symbiolongicarpus. Three isolates, Shigella flexneri, Microbacterium liquefaciens, and Kocuria erythromyxa, were identified to produce QSSMs using biosensors detecting N-acyl-L-homoserine lactones. Multispecies biofilms and QSSM extracts from these bacteria showed a positive chemotactic effect on H. symbiolongicarpus larvae, a phenomenon not observed with mutant strains of E. coli and Chromobacterium violaceum that are unable to produce QSSMs. These biofilms and QSSMs extracts induced high rates of larval attachment, although only 1 % of the attached larvae metamorphosed to primary polyps, in contrast to 99 % of larvae incubated with CsCl, an artificial inductor of attachment and metamorphosis. These observations suggest that bacterial QSSMs participate in H. symbiolongicarpus substrate selection by inducing larval chemotaxis and attachment. Furthermore, they support the notion that settlement in cnidarians is decoupled into two processes, attachment to the substrate and metamorphosis to a primary polyp, where QSSMs likely participate in the former but not in the latter.

I Feel That! Fluid Dynamics and Sensory Aspects of Larval Settlement across Scales

2018 ◽  
Keyword(s):  
Fluid Dynamics ◽  
Marine Invertebrates ◽  
Larval Settlement ◽  
External Environment ◽  
Life Cycles ◽  
Decision Making Process ◽  
Larval Biology ◽  
Sea Floor ◽  
External Cues ◽  
Juvenile Habitat

A commonality among oceanic life cycles is a process known as settlement, where dispersing propagules transition to the sea floor. For many marine invertebrates, this transition is irreversible, and therefore involves a crucial decision-making process through which larvae evaluate their juvenile habitat-to-be. In this chapter, we consider aspects of the external environment that could influence successful settlement. Specifically, we discuss water flow across scales, and how larvae can engage behaviors to influence where ocean currents take them, and enhance the likelihood of their being carried toward suitable settlement locations. Next, we consider what senses larvae utilize to evaluate their external environment and properly time such behavioral modifications, and settlement generally. We hypothesize that larvae integrate these various external cues in a hierarchical fashion, with differing arrangements being employed across ontogeny and among species. We conclude with a brief discussion of the future promises of larval biology, ecology, and evolution.

scholarly journals Bacterial Nucleobases Synergistically Induce Larval Settlement and Metamorphosis in the Invasive MusselMytilopsis sallei

2019 ◽  
Vol 85 (16) ◽  
Author(s):  
Jian He ◽  
Qi Dai ◽  
Yuxuan Qi ◽  
Pei Su ◽  
Miaoqin Huang ◽  
...  
Keyword(s):  
Marine Invertebrates ◽  
Larval Settlement ◽  
Aquatic Systems ◽  
Substrate Selection ◽  
Content Type ◽  
Dreissenid Mussels ◽  
Settlement And Metamorphosis ◽  
Environmental Bacteria ◽  
Fouling Organisms ◽  
Chemical Mediators

ABSTRACTMarine bacterial biofilms have long been recognized as potential inducers of larval settlement and metamorphosis in marine invertebrates, but few chemical cues from bacteria have been identified. Here, we show that larval settlement and metamorphosis of an invasive fouling mussel,Mytilopsis sallei, could be induced by biofilms of bacteria isolated from its adult shells and other substrates from the natural environment. One of the strains isolated,Vibrio owensiiMS-9, showed strong inducing activity which was attributed to the release of a mixture of nucleobases including uracil, thymine, xanthine, hypoxanthine, and guanine into seawater. In particular, the synergistic effect of hypoxanthine and guanine was sufficient for the inducing activity ofV. owensiiMS-9. The presence of two or three other nucleobases could enhance, to some extent, the activity of the mixture of hypoxanthine and guanine. Furthermore, we determined that bacteria producing higher concentrations of nucleobases were more likely to induce larval settlement and metamorphosis ofM. salleithan were bacteria producing lower concentrations of nucleobases. The present study demonstrates that bacterial nucleobases play an important role in larval settlement and metamorphosis of marine invertebrates. This provides new insights into our understanding of the role of environmental bacteria in the colonization and aggregation of invasive fouling organisms and of the metabolites used as chemical mediators in cross-kingdom communication within aquatic systems.IMPORTANCEInvasive species are an increasingly serious problem globally. In aquatic ecosystems, invasive dreissenid mussels are well-known ecological and economic pests because they appear to effortlessly invade new environments and foul submerged structures with high-density aggregations. To efficiently control exotic mussel recruitment and colonization, the need to investigate the mechanisms of substrate selection for larval settlement and metamorphosis is apparent. Our work is one of very few to experimentally demonstrate that compounds produced by environmental bacteria play an important role in larval settlement and metamorphosis in marine invertebrates. Additionally, this study demonstrates that bacterial nucleobases can be used as chemical mediators in cross-kingdom communication within aquatic systems, which will enhance our understanding of how microbes induce larval settlement and metamorphosis of dreissenid mussels, and it furthermore may allow the development of new methods for application in antifouling.

Fine structure of Metchnikovella incurvata Caullery and Mesnil 1914 (microsporidia), a hyperparasite of gregarines Polyrhabdina sp. from the polychaete Pygospio elegans

Parasitology ◽  
2013 ◽  
Vol 140 (7) ◽  
pp. 855-867 ◽  
Author(s):  
Y. Y. SOKOLOVA ◽  
G. G. PASKEROVA ◽  
Y. M. ROTARI ◽  
E. S. NASSONOVA ◽  
A. V. SMIRNOV
Keyword(s):  
Electron Microscopy ◽  
Marine Invertebrates ◽  
Light And Electron Microscopy ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Life Cycles ◽  
Single Family ◽  
Host Cytoplasm ◽  
History Of ◽  
Multinuclear Cells

SUMMARYClass Rudimicrosporea Sprague 1977, with its single family Metchnikovellidae, comprises hyperparasites of gregarines from the guts of marine invertebrates. Metchnikovellids remain poorly studied in spite of their significance to the evolutionary history of microsporidia; their ultrastructure and life cycles require further investigation. Here we present results of the light- and electron-microscopy study of Metchnikovella incurvata Caulleri and Mesnil 1914, isolated from lecudinid gregarines, parasitizing polychaetes Pygospio elegans in the White Sea littoral zone, and yet described only on the light-microscopic level. The life cycle of this microsporidium includes 2 sporogonies: free (FS) and sac-bound (SBS). In FS, sporonts develop into multinuclear cells (sporogonial plasmodia), which generate sporoblasts and free spores residing in direct contact with the host cytoplasm. Electron microscopy revealed their metchnikovellidean structure: a horseshoe-shaped nucleus, short manubrium perpendicular to the long axis of the spore, and a polar cap in a separate membrane container. Merogony was not observed. The earliest stages of SBS were chains of binucleate cells. They underwent a series of nuclear and cell divisions, produced extracellular envelopes, and split into boomerang-shaped spore sacs, containing up to 16 spores each. Ultrastructure and sizes of sac-bounded spores were similar to those of free-living ones. An amended diagnosis of M. incurvata is provided.

Determination of Histamine in Japanese Spanish Mackerel (Scomberomorus niphonius) Meat Implicated in a Foodborne Poisoning

2019 ◽  
Vol 82 (10) ◽  
pp. 1643-1649 ◽  
Author(s):  
CHIU-CHU HWANG ◽  
PEI-HUI TSENG ◽  
YI-CHEN LEE ◽  
HSIEN-FENG KUNG ◽  
CHUN-YUNG HUANG ◽  
...  
Keyword(s):  
Meat Products ◽  
Pcr Amplification ◽  
Enterobacter Aerogenes ◽  
Potential Hazard ◽  
Bacterial Strains ◽  
Spanish Mackerel ◽  
Rdna Sequencing ◽  
Fish Samples ◽  
Raw Fish ◽  
Scomberomorus Niphonius

ABSTRACT An incident of foodborne poisoning causing illness in seven victims due to ingestion of fried Japanese Spanish mackerel (JS mackerel; Scomberomorus niphonius) meat occurred in September 2014 in Hualien County, eastern Taiwan. Of the two suspected fish meats, one raw sample contained 3,318 ppm of histamine and one fried sample contained 1,906 ppm of histamine, levels which are greater than the potential hazard action level (500 ppm) in most illness cases. Given the allergy-like symptoms of the victims and the high histamine content in the suspected fish samples, this foodborne poisoning was strongly suspected to be caused by histamine intoxication. In addition, five histamine-producing bacterial strains isolated from suspected raw fish samples, capable of producing 152 to 1,020 ppm of histamine in Trypticase soy broth supplemented with 1.0% l-histidine, were identified as Hafnia alvei (one strain), Enterobacter aerogenes (two strains), Raoultella ornithinolytica (one strain), and Morganella morganii (one strain) by 16S rDNA sequencing with PCR amplification. Moreover, 12 raw fish samples and 39 fried fish samples from retail stores were collected and tested to determine the occurrence of histamine. Two of 12 commercial raw fish samples (16.7%) had histamine levels greater than the U.S. Food and Drug Administration guideline for decomposition of 50 ppm for scombroid fish or product or a combination of both. To our knowledge, this is the first report in Taiwan to demonstrate that the JS mackerel meat products could cause histamine intoxication.

scholarly journals Integrated Genomic and Metabolomic Approach to the Discovery of Potential Anti-Quorum Sensing Natural Products from Microbes Associated with Marine Samples from Singapore

Marine Drugs ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 72 ◽  
Author(s):  
Ji Ong ◽  
Hui Goh ◽  
Swee Lim ◽  
Li Pang ◽  
Joyce Chin ◽  
...  
Keyword(s):  
Drug Discovery ◽  
Quorum Sensing ◽  
Large Scale ◽  
Marine Ecosystem ◽  
Gene Clusters ◽  
Integrated Approach ◽  
Rrna Gene ◽  
Dependent Manner ◽  
Bacterial Strains ◽  
Reporter System

With 70% of the Earth’s surface covered in water, the marine ecosystem offers immense opportunities for drug discovery and development. Due to the decreasing rate of novel natural product discovery from terrestrial sources in recent years, many researchers are beginning to look seaward for breakthroughs in new therapeutic agents. As part of an ongoing marine drug discovery programme in Singapore, an integrated approach of combining metabolomic and genomic techniques were initiated for uncovering novel anti-quorum sensing molecules from bacteria associated with subtidal samples collected in the Singapore Strait. Based on the culture-dependent method, a total of 102 marine bacteria strains were isolated and the identities of selected strains were established based on their 16S rRNA gene sequences. About 5% of the marine bacterial organic extracts showed quorum sensing inhibitory (QSI) activity in a dose-dependent manner based on the Pseudomonas aeruginosa QS reporter system. In addition, the extracts were subjected to mass spectrometry-based molecular networking and the genome of selected strains were analysed for known as well as new biosynthetic gene clusters. This study revealed that using integrated techniques, coupled with biological assays, can provide an effective and rapid prioritization of marine bacterial strains for downstream large-scale culturing for the purpose of isolation and structural elucidation of novel bioactive compounds.

A versatile plasmid biosensor useful to identify quorum sensing LuxR-family orphans in bacterial strains

2008 ◽  
Vol 73 (3) ◽  
pp. 273-275 ◽  
Author(s):  
Laura Steindler ◽  
Giulia Devescovi ◽  
Sujatha Subramoni ◽  
Vittorio Venturi
Keyword(s):  
Quorum Sensing ◽  
Bacterial Strains

scholarly journals Selective enrichment of R−segregants as the main mechanism of ‘curing’ of the R factor by acridine dyes

1971 ◽  
Vol 17 (1) ◽  
pp. 9-16 ◽  
Author(s):  
Masanosuke Yoshikawa
Keyword(s):  
Shigella Flexneri ◽  
Host Cells ◽  
Bacterial Strains ◽  
Initial Inoculum ◽  
Selective Enrichment ◽  
E Coli ◽  
R Factor ◽  
Acridine Dyes ◽  
Increased Sensitivity ◽  
R Factors

SUMMARYBy the use of appropriate strains ofEscherichia coli, Shigella flexneriandSalmonella typhimuriumwith and without an R factor, R100, the mechanism of ‘curing’ of R factor by acridine dyes was examined. This R factor was shown to confer increased sensitivity to acriflavine upon the host cells.E. colistrain W-3630, once infected with R100, has never been observed to segregate R−cells. When mixtures of R+and R−cells of this strain were grown in acriflavine broth, the proportion of R−cells increased and was also correlated with the proportion in the initial inoculum. Other bacterial strains carrying R100segregate R~ cells spontaneously. Growth tests starting with varying proportion of R+and R−cells of these strains in acriflavine broth also gave a marked correlation between the initial and final proportions of R−cells, and indicated that the main cause of ‘curing’ the R factor was the selective enrichment of R−segregants present in the initial inocula or arising spontaneously during growth of the R+culture. These results suggest that the mechanisms underlying the ‘curing’ of F and R factors are different. Tests with several acridine dyes gave results similar to those with acriflavine.

Verification of Intermediate Hosts in the Life Cycles of Microsporidia by Small Subunit rDNA Sequencing

1998 ◽  
Vol 45 (3) ◽  
pp. 290-292 ◽  
Author(s):  
Charles R. Vossbrinck ◽  
Theodore G. Andreadis ◽  
Bettina A. Debrunner-Vossbrinck
Keyword(s):  
Small Subunit ◽  
Life Cycles ◽  
Intermediate Hosts ◽  
Rdna Sequencing ◽  
Small Subunit Rdna

Characterization of two LuxI/R homologs in Pantoea ananatis LMG 2665T

2016 ◽  
Vol 62 (11) ◽  
pp. 893-903 ◽  
Author(s):  
Siphathele Sibanda ◽  
Jacques Theron ◽  
Divine Y. Shyntum ◽  
Lucy N. Moleleki ◽  
Teresa A. Coutinho
Keyword(s):  
Quorum Sensing ◽  
Genome Sequence ◽  
Biofilm Formation ◽  
Biological Significance ◽  
Bacterial Strains ◽  
Pantoea Ananatis ◽  
Ecological Fitness ◽  
Host Interactions

Quorum sensing (QS) plays an important role in the regulation of bacteria–host interactions and ecological fitness in many bacteria. In this study, 2 luxI/R homologs, namely eanI/eanR and rhlI/rhlR, were identified in the genome sequence of Pantoea ananatis LMG 2665T. To determine a role for these luxI/R homologs in pathogenicity and biofilm formation, mutant bacterial strains lacking either eanI/R or rhlI/R and both of these homologs were generated. The results indicated that both the RhlI/R and EanI/R systems are required for pathogenicity and biofilm formation in strain LMG 2665T. This is the first study to characterize the biological significance of the RhlI/R QS system in P. ananatis.

Novel bacteria associated with Arctic seashore lichens have potential roles in nutrient scavenging

2014 ◽  
Vol 60 (5) ◽  
pp. 307-317 ◽  
Author(s):  
Margrét Auður Sigurbjörnsdóttir ◽  
Starri Heiðmarsson ◽  
Anna Rut Jónsdóttir ◽  
Oddur Vilhelmsson
Keyword(s):  
Denaturing Gradient Gel Electrophoresis ◽  
Symbiotic Association ◽  
Bacterial Strains ◽  
Rdna Sequencing ◽  
Gradient Gel Electrophoresis ◽  
Species Specific ◽  
Mutualistic Association ◽  
Modest Level

While generally described as a bipartite mutualistic association between fungi and algae or cyanobacteria, lichens also host diverse and heretofore little explored communities of nonphototrophic endolichenic bacteria. The composition and possible roles of these bacterial communities in the lichen symbiotic association constitute an emerging field of research. Saxicolous (rock-dwelling) seashore lichens present an unusual environment, characterized by rapid fluctuations in temperature, salinity, exposure to solar radiation, etc. The present study focuses on the bacterial biota associated with 4 species of crustose, halophilic, saxicolous seashore lichens found in northern Iceland. A denaturing gradient gel electrophoresis based characterization of the composition of the lichen-associated microbiotas indicated that they are markedly lichen-species-specific and clearly distinguishable from the environmental microbiota represented by control sampling. A collection of bacterial strains was investigated and partially identified by 16S rDNA sequencing. The strains were found to belong to 7 classes: Alphaproteobacteria, Bacilli, Actinobacteria, Flavobacteria, Cytophagia, Sphingobacteria, and Gammaproteobacteria. Several isolates display only a modest level of similarity to their nearest relatives found in GenBank, suggesting that they comprise previously undescribed taxa. Selected strains were tested for inorganic phosphate solubilization and biodegradation of several biopolymers, such as barley β-glucan, xylan, chitosan, and lignin. The results support a nutrient-scavenging role of the associate microbiota in the seashore lichen symbiotic association.

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