scholarly journals Microsporidian Infection in a Free-Living Marine Nematode

2012 ◽  
Vol 11 (12) ◽  
pp. 1544-1551 ◽  
Author(s):  
A. M. Ardila-Garcia ◽  
N. M. Fast
Keyword(s):  
Marine Nematode ◽  
Free Living ◽  
Content Type ◽  
Infection Pattern ◽  
Transmission Electron ◽  
Muscle Tissues ◽  
Natural Hosts ◽  
In The Wild ◽  
Microsporidian Infection

ABSTRACT Microsporidia are unicellular fungi that are obligate endoparasites. Although nematodes are one of the most abundant and diverse animal groups, the only confirmed report of microsporidian infection was that of the “nematode killer” ( Nematocida parisii ). N. parisii was isolated from a wild Caenorhabditis sp. and causes an acute and lethal intestinal infection in a lab strain of Caenorhabditis elegans . We set out to characterize a microsporidian infection in a wild nematode to determine whether the infection pattern of N. parisii in the lab is typical of microsporidian infections in nematodes. We describe a novel microsporidian species named Sporanauta perivermis (marine spore of roundworms) and characterize its infection in its natural host, the free-living marine nematode Odontophora rectangula. S. perivermis is not closely related to N. parisii and differs strikingly in all aspects of infection. Examination by transmission electron microscopy (TEM) revealed that the infection was localized in the hypodermal and muscle tissues only and did not involve the intestines. Fluorescent in situ hybridization (FISH) confirmed infection in the muscle and hypodermis, and surprisingly, it also revealed that the parasite infects O. rectangula eggs, suggesting a vertical mode of transmission. Our observations highlight the importance of studying parasites in their natural hosts and indicate that not all nematode-infecting microsporidia are “nematode killers”; instead, microsporidiosis can be more versatile and chronic in the wild.

scholarly journals Behavior of Yersinia enterocolitica in the Presence of the Bacterivorous Acanthamoeba castellanii

2013 ◽  
Vol 79 (20) ◽  
pp. 6407-6413 ◽  
Author(s):  
E. Lambrecht ◽  
J. Baré ◽  
I. Van Damme ◽  
W. Bert ◽  
K. Sabbe ◽  
...  
Keyword(s):  
Yersinia Enterocolitica ◽  
Pathogenic Bacteria ◽  
Acanthamoeba Castellanii ◽  
Ecological Niches ◽  
Free Living ◽  
Content Type ◽  
Food Borne ◽  
Transmission Electron ◽  
Set Up ◽  
The Impact

ABSTRACTFree-living protozoa play an important role in the ecology and epidemiology of human-pathogenic bacteria. In the present study, the interaction betweenYersinia enterocolitica, an important food-borne pathogen, and the free-living amoebaAcanthamoeba castellaniiwas studied. Several cocultivation assays were set up to assess the resistance ofY. enterocoliticatoA. castellaniipredation and the impact of environmental factors and bacterial strain-specific characteristics. Results showed that allY. enterocoliticastrains persist in association withA. castellaniifor at least 14 days, and associations withA. castellaniienhanced survival ofYersiniaunder nutrient-rich conditions at 25°C and under nutrient-poor conditions at 37°C. Amoebae cultivated in the supernatant of oneYersiniastrain showed temperature- and time-dependent permeabilization. Intraprotozoan survival ofY. enterocoliticadepended on nutrient availability and temperature, with up to 2.8 log CFU/ml bacteria displaying intracellular survival at 7°C for at least 4 days in nutrient-rich medium. Transmission electron microscopy was performed to locate theYersiniacells inside the amoebae. AsYersiniaandAcanthamoebashare similar ecological niches, this interaction identifies a role of free-living protozoa in the ecology and epidemiology ofY. enterocolitica.

scholarly journals Metatranscriptomics by In Situ RNA Stabilization Directly and Comprehensively Revealed Episymbiotic Microbial Communities of Deep-Sea Squat Lobsters

mSystems ◽  
2020 ◽  
Vol 5 (5) ◽  
Author(s):  
Kaori Motoki ◽  
Tomo-o Watsuji ◽  
Yoshihiro Takaki ◽  
Ken Takai ◽  
Wataru Iwasaki
Keyword(s):  
Deep Sea ◽  
Expression Profiles ◽  
Rna Degradation ◽  
Rna Expression ◽  
Free Living ◽  
Content Type ◽  
Living State ◽  
Rna Stabilization ◽  
Squat Lobsters

ABSTRACT Shinkaia crosnieri is an invertebrate that inhabits an area around deep-sea hydrothermal vents in the Okinawa Trough in Japan by harboring episymbiotic microbes as the primary nutrition. To reveal physiology and phylogenetic composition of the active episymbiotic populations, metatranscriptomics is expected to be a powerful approach. However, this has been hindered by substantial perturbation (e.g., RNA degradation) during time-consuming retrieval from the deep sea. Here, we conducted direct metatranscriptomic analysis of S. crosnieri episymbionts by applying in situ RNA stabilization equipment. As expected, we obtained RNA expression profiles that were substantially different from those obtained by conventional metatranscriptomics (i.e., stabilization after retrieval). The episymbiotic community members were dominated by three orders, namely, Thiotrichales, Methylococcales, and Campylobacterales, and the Campylobacterales members were mostly dominated by the Sulfurovum genus. At a finer phylogenetic scale, the episymbiotic communities on different host individuals shared many species, indicating that the episymbionts on each host individual are not descendants of a few founder cells but are horizontally exchanged. Furthermore, our analysis revealed the key metabolisms of the community: two carbon fixation pathways, a formaldehyde assimilation pathway, and utilization of five electron donors (sulfide, thiosulfate, sulfur, methane, and ammonia) and two electron accepters (oxygen and nitrate/nitrite). Importantly, it was suggested that Thiotrichales episymbionts can utilize intercellular sulfur globules even when sulfur compounds are not usable, possibly also in a detached and free-living state. IMPORTANCE Deep-sea hydrothermal vent ecosystems remain mysterious. To depict in detail the enigmatic life of chemosynthetic microbes, which are key primary producers in these ecosystems, metatranscriptomic analysis is expected to be a promising approach. However, this has been hindered by substantial perturbation (e.g., RNA degradation) during time-consuming retrieval from the deep sea. In this study, we conducted direct metatranscriptome analysis of microbial episymbionts of deep-sea squat lobsters (Shinkaia crosnieri) by applying in situ RNA stabilization equipment. Compared to conventional metatranscriptomics (i.e., RNA stabilization after retrieval), our method provided substantially different RNA expression profiles. Moreover, we discovered that S. crosnieri and its episymbiotic microbes constitute complex and resilient ecosystems, where closely related but various episymbionts are stably maintained by horizontal exchange and partly by their sulfur storage ability for survival even when sulfur compounds are not usable, likely also in a detached and free-living state.

scholarly journals Unexpected host dependency of Antarctic Nanohaloarchaeota

2019 ◽  
Vol 116 (29) ◽  
pp. 14661-14670 ◽  
Author(s):  
Joshua N. Hamm ◽  
Susanne Erdmann ◽  
Emiley A. Eloe-Fadrosh ◽  
Allegra Angeloni ◽  
Ling Zhong ◽  
...  
Keyword(s):  
Fluorescent In Situ Hybridization ◽  
Single Species ◽  
Hypersaline Environments ◽  
Free Living ◽  
Metagenome Analysis ◽  
Symbiotic Relationships ◽  
Cell Structures ◽  
Transmission Electron ◽  
Globally Distributed

In hypersaline environments, Nanohaloarchaeota (Diapherotrites, Parvarchaeota, Aenigmarchaeota, Nanoarchaeota, Nanohaloarchaeota [DPANN] superphylum) are thought to be free-living microorganisms. We report cultivation of 2 strains of Antarctic Nanohaloarchaeota and show that they require the haloarchaeon Halorubrum lacusprofundi for growth. By performing growth using enrichments and fluorescence-activated cell sorting, we demonstrated successful cultivation of Candidatus Nanohaloarchaeum antarcticus, purification of Ca. Nha. antarcticus away from other species, and growth and verification of Ca. Nha. antarcticus with Hrr. lacusprofundi; these findings are analogous to those required for fulfilling Koch’s postulates. We use fluorescent in situ hybridization and transmission electron microscopy to assess cell structures and interactions; metagenomics to characterize enrichment taxa, generate metagenome assembled genomes, and interrogate Antarctic communities; and proteomics to assess metabolic pathways and speculate about the roles of certain proteins. Metagenome analysis indicates the presence of a single species, which is endemic to Antarctic hypersaline systems that support the growth of haloarchaea. The presence of unusually large proteins predicted to function in attachment and invasion of hosts plus the absence of key biosynthetic pathways (e.g., lipids) in metagenome assembled genomes of globally distributed Nanohaloarchaeota indicate that all members of the lineage have evolved as symbionts. Our work expands the range of archaeal symbiotic lifestyles and provides a genetically tractable model system for advancing understanding of the factors controlling microbial symbiotic relationships.

scholarly journals The Pine Bark Adelgid, Pineus strobi, Contains Two Novel Bacteriocyte-Associated Gammaproteobacterial Symbionts

2013 ◽  
Vol 80 (3) ◽  
pp. 878-885 ◽  
Author(s):  
Elena R. Toenshoff ◽  
Gitta Szabó ◽  
Daniela Gruber ◽  
Matthias Horn
Keyword(s):  
Evolutionary History ◽  
Adelges Tsugae ◽  
Pine Bark ◽  
23S Rrna ◽  
Bacterial Symbionts ◽  
Content Type ◽  
Transmission Electron ◽  
History Of ◽  
Bacterial Endosymbionts

ABSTRACTBacterial endosymbionts of the pine bark adelgid,Pineus strobi(Insecta: Hemiptera: Adelgidae), were investigated using transmission electron microscopy, 16S and 23S rRNA-based phylogeny, and fluorescencein situhybridization. Two morphologically different symbionts affiliated with theGammaproteobacteriawere present in distinct bacteriocytes. One of them (“CandidatusAnnandia pinicola”) is most closely related to an endosymbiont ofAdelges tsugae, suggesting that they originate from a lineage already present in ancient adelgids before the hosts diversified into the two major clades,AdelgesandPineus. The otherP. strobisymbiont (“CandidatusHartigia pinicola”) represents a novel symbiont lineage in members of the Adelgidae. Our findings lend further support for a complex evolutionary history of the association of adelgids with a phylogenetically diverse set of bacterial symbionts.

Working in the Open: lessons from open source on building innovation networks in education

2016 ◽  
Vol 24 (3) ◽  
pp. 280-295 ◽  
Author(s):  
Rafi Santo ◽  
Dixie Ching ◽  
Kylie Peppler ◽  
Christopher Hoadley
Keyword(s):  
New York ◽  
Open Source ◽  
Professional Learning ◽  
Open Approach ◽  
Content Type ◽  
In The Wild ◽  
Building Activities ◽  
Five Practices ◽  
Standard Practices

Purpose This article makes the case that the education community can learn from professional learning and innovation practices, collectively called “Working in the Open” (or “Working Open”), that have roots in the free/open source software (F/OSS) movement. These practices focus on values of transparency, collaboration and sharing within communities of experimentation. This paper aims to argues that Working Open offers a compelling approach to fostering distributed educational professional networks that focus on co-constructing new projects and best practices. Design/methodology/approach Insights presented here are based on three sources: expert perspectives on open source work practices gleaned through interviews and blog posts, a qualitative case analysis of a collaborative project enacted by a group of informal learning organizations within the Hive NYC Learning Network, a community of over 70 youth-facing organizations in New York City, as well as an overview of that network’s participation structures, and, finally, knowledge-building activities and discussions held within the Hive NYC community about the topic in situ. From these sources, the authors derived general principles to guide open work approaches. Findings The authors identify five practices deemed as central to Working Open: public storytelling and context setting, enabling community contribution, rapid prototyping “in the wild”, public reflection and documentation and, lastly, creating remixable work products. The authors describe these practices, show how they are enacted in situ, outline ways that Hive NYC stewards promote a Working Open organizational ecosystem and conclude with recommendations for utilizing a Working Open approach. Originality/value Drawing from the F/OSS movement, this article builds on standard practices of professional learning communities to provide an approach that focuses on pushing forward innovation and changes in practice as opposed to solely sharing reflections or observing practices.

Sperm dimorphism in the free-living marine nematode Terschellingia glabricutis (Nematoda: Monhysterida: Linhomoeidae)

Nematology ◽  
2008 ◽  
Vol 10 (2) ◽  
pp. 189-205 ◽  
Author(s):  
Vladimir Yushin
Keyword(s):  
Biological Significance ◽  
Marine Species ◽  
Anterior Testis ◽  
Sperm Nucleus ◽  
Marine Nematode ◽  
Free Living ◽  
Transmission Electron ◽  
Sperm Development ◽  
Sperm Dimorphism ◽  
Female Genital

AbstractThe structure and development of the dimorphic spermatozoa of the free-living marine nematode Terschellingia glabricutis (Monhysterida, Linhomoeina, Linhomoeidae) were studied with transmission electron microscope (TEM). The linhomoeid pattern of spermatozoa includes absence of fibrous bodies (FB) in spermatocytes and their appearance in spermatids as spindle-shaped bodies never associating with membranous organelles (MO); presence of centrioles near the sperm nucleus; occurrence of filopodia in the spermatids and immature spermatozoa; unpolarised concentric structure of the mature spermatozoa; microtubule-like elements in spermatids and spermatozoa. The linhomoeins differ from their closest relatives, monhysterins (Xyalidae, Sphaerolaimidae), by total absence of MO at all the stages of spermatogenesis. This peculiarity is also found in the sperm development of some chromadorids, desmodorids and tylenchomorphs. In T. glabricutis the anterior testis produces large (20 μm) 'macrospermatozoa' of the linhomoeid pattern; the posterior testis produces much smaller (10 μm) 'microspermatozoa' of simplified structure. The female genital tubes also contain two types of amoeboid spermatozoa of different size and internal structure. Thus, T. glabricutis demonstrates a pattern of sperm dimorphism in which each testis of the diorchic male produces its own type of spermatozoa. Both types are found in the genital tube of fertilised females. Such sperm dimorphism is known from light microscope observations for several distantly related marine species although the biological significance of this dimorphism is obscure.

scholarly journals A Novel Regulatory Pathway for K+ Uptake in the Legume Symbiont Azorhizobium caulinodans in Which TrkJ Represses the kdpFABC Operon at High Extracellular K+ Concentrations

2017 ◽  
Vol 83 (19) ◽  
Author(s):  
Lowela Siarot ◽  
Hiroki Toyazaki ◽  
Makoto Hidaka ◽  
Keigo Kurumisawa ◽  
Tomoki Hirakawa ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Uptake System ◽  
Azorhizobium Caulinodans ◽  
Free Living ◽  
Content Type ◽  
High K ◽  
Living State ◽  
In The Wild ◽  
Low K ◽  
Distinct Locus

ABSTRACT Bacteria have multiple K+ uptake systems. Escherichia coli, for example, has three types of K+ uptake systems, which include the low-K+-inducible KdpFABC system and two constitutive systems, Trk (TrkAG and TrkAH) and Kup. Azorhizobium caulinodans ORS571, a rhizobium that forms nitrogen-fixing nodules on the stems and roots of Sesbania rostrata, also has three types of K+ uptake systems. Through phylogenetic analysis, we found that A. caulinodans has two genes homologous to trkG and trkH, designated trkI and trkJ. We also found that trkI is adjacent to trkA in the genome and these two genes are transcribed as an operon; however, trkJ is present at a distinct locus. Our results demonstrated that trkAI, trkJ, and kup were expressed in the wild-type stem nodules, whereas kdpFABC was not. Interestingly, Δkup and Δkup ΔkdpA mutants formed Fix– nodules, while the Δkup ΔtrkA ΔtrkI ΔtrkJ mutant formed Fix+ nodules, suggesting that with the additional deletion of Trk system genes in the Δkup mutant, Fix+ nodule phenotypes were recovered. kdpFABC of the Δkup ΔtrkJ mutant was expressed in stem nodules, but not in the free-living state, under high-K+ conditions. However, kdpFABC of the Δkup ΔtrkA ΔtrkI ΔtrkJ mutant was highly expressed even under high-K+ conditions. The cytoplasmic K+ levels in the Δkup ΔtrkA ΔtrkI mutant, which did not express kdpFABC under high-K+ conditions, were markedly lower than those in the Δkup ΔtrkA ΔtrkI ΔtrkJ mutant. Taking all these results into consideration, we propose that TrkJ is involved in the repression of kdpFABC in response to high external K+ concentrations and that the TrkAI system is unable to function in stem nodules. IMPORTANCE K+ is a major cytoplasmic cation in prokaryotic and eukaryotic cells. Bacteria have multiple K+ uptake systems to control the cytoplasmic K+ levels. In many bacteria, the K+ uptake system KdpFABC is expressed under low-K+ conditions. For years, many researchers have argued over how bacteria sense K+ concentrations. Although KdpD of Escherichia coli is known to sense both cytoplasmic and extracellular K+ concentrations, the detailed mechanism of K+ sensing is still unclear. In this study, we propose that the transmembrane TrkJ protein of Azorhizobium caulinodans acts as a sensor for the extracellular K+ concentration and that high extracellular K+ concentrations repress the expression of KdpFABC via TrkJ.

scholarly journals ‘Candidatus Xiphinematincola pachtaicus' gen. nov., sp. nov., an endosymbiotic bacterium associated with nematode species of the genus Xiphinema (Nematoda, Longidoridae)

2021 ◽  
Vol 71 (7) ◽  
Author(s):  
Juan E. Palomares-Rius ◽  
Carlos Gutiérrez-Gutiérrez ◽  
Manuel Mota ◽  
Wim Bert ◽  
Myriam Claeys ◽  
...  
Keyword(s):  
Nematode Species ◽  
Rrna Gene ◽  
Host Cell Membrane ◽  
Content Type ◽  
Transmission Electron ◽  
The Family ◽  
Curved Rods ◽  
Bacterium Strain ◽  
Partial Genome

An intracellular bacterium, strain IAST, was observed to infect several species of the plant-parasitic nematode genus Xiphinema (Xiphinema astaregiense, Xiphinema incertum, Xiphinema madeirense, Xiphinema pachtaicum, Xiphinema parapachydermum and Xiphinema vallense). The bacterium could not be recovered on axenic medium. The 16S rRNA gene sequence of IAST was found to be new, being related to the family Burkholderiaceae, class Betaproteobacteria. Fungal endosymbionts Mycoavidus cysteinexigens B1-EBT (92.9 % sequence identity) and ‘Candidatus Glomeribacter gigasporarum’ BEG34 (89.8 % identity) are the closest taxa and form a separate phylogenetic clade inside Burkholderiaceae. Other genes (atpD, lepA and recA) also separated this species from its closest relatives using a multilocus sequence analysis approach. These genes were obtained using a partial genome of this bacterium. The localization of the bacterium (via light and fluorescence in situ hybridization microscopy) is in the X. pachtaicum females clustered around the developing oocytes, primarily found embedded inside the epithelial wall cells of the ovaries, from where they are dispersed in the intestine. Transmission electron microscopy (TEM) observations supported the presence of bacteria inside the nematode body, where they occupy ovaries and occur inside the intestinal epithelium. Ultrastructural analysis of the bacterium showed cells that appear as mostly irregular, slightly curved rods with rounded ends, 0.8–1.2 µm wide and 2.5–6.0 µm long, possessing a typical Gram-negative cell wall. The peptidoglycan layer is, however, evident only occasionally and not detectable by TEM in most cells. Another irregularly occurring shell surrounding the endosymbiont cells or the cell clusters was also revealed, probably originating from the host cell membrane. Flagella or spore-like cells do not occur and the nucleoid is diffusely distributed throughout the cell. This endosymbiont is transmitted vertically through nematode generations. These results support the proposal of IAST as a new species, although its obligate intracellular and obligate endosymbiont nature prevented isolation of a definitive type strain. Strain IAST is therefore proposed as representing ‘Candidatus Xiphinematincola pachtaicus’ gen. nov., sp. nov.

scholarly journals Novel Parachlamydia acanthamoebae Quantification Method Based on Coculture with Amoebae

2008 ◽  
Vol 74 (20) ◽  
pp. 6397-6404 ◽  
Author(s):  
Junji Matsuo ◽  
Yasuhiro Hayashi ◽  
Shinji Nakamura ◽  
Marie Sato ◽  
Yoshihiko Mizutani ◽  
...  
Keyword(s):  
Fluorescent In Situ Hybridization ◽  
Vero Cells ◽  
Host Cells ◽  
Human Pathogens ◽  
Free Living ◽  
Infectious Dose ◽  
Quantification Method ◽  
Transmission Electron ◽  
Dilution Curves

ABSTRACT Parachlamydia acanthamoebae, belonging to the order Chlamydiales, is an obligately intracellular bacterium that infects free-living amoebae and is a potential human pathogen. However, no method exists to accurately quantify viable bacterial numbers. We present a novel quantification method for P. acanthamoebae based on coculture with amoebae. P. acanthamoebae was cultured either with Acanthamoeba spp. or with mammalian epithelial HEp-2 or Vero cells. The infection rate of P. acanthamoebae (amoeba-infectious dose [AID]) was determined by DAPI (4′,6-diamidino-2-phenylindole) staining and was confirmed by fluorescent in situ hybridization. AIDs were plotted as logistic sigmoid dilution curves, and P. acanthamoebae numbers, defined as amoeba-infectious units (AIU), were calculated. During culture, amoeba numbers and viabilities did not change, and amoebae did not change from trophozoites to cysts. Eight amoeba strains showed similar levels of P. acanthamoebae growth, and bacterial numbers reached ca. 1,000-fold (109 AIU preculture) after 4 days. In contrast, no increase was observed for P. acanthamoebae in either mammalian cell line. However, aberrant structures in epithelial cells, implying possible persistent infection, were seen by transmission electron microscopy. Thus, our method could monitor numbers of P. acanthamoebae bacteria in host cells and may be useful for understanding chlamydiae present in the natural environment as human pathogens.

scholarly journals Identification of Encephalitozoon and Enterocytozoon (Microsporidia) Spores in Stool and Urine Samples Obtained from Free-Living South American Coatis (Nasua nasua)

2012 ◽  
Vol 78 (12) ◽  
pp. 4490-4492 ◽  
Author(s):  
Maria Anete Lallo ◽  
Patrícia Calábria ◽  
Eduardo Fernandes Bondan ◽  
Liliane Milanelo
Keyword(s):  
Staining Technique ◽  
Enterocytozoon Bieneusi ◽  
Urine Samples ◽  
South American ◽  
Free Living ◽  
Content Type ◽  
Large Cities ◽  
Nasua Nasua ◽  
Microsporidian Infection ◽  
Positive Results

ABSTRACTThis study emphasizes the importance of free-living coatis as a potential source of microsporidian infection for humans living in large cities. We found 19 (31.7%) positive results among 60 fecal samples analyzed by PCR-based analysis and the Gram-Chromotrope staining technique (11.7% were positive forEncephalitozoon cuniculi, 6.7% forE. intestinalis, 6.7% forE. hellem, and 6.7% forEnterocytozoon bieneusi). Only 5 (8.4%) urine samples tested positive forE. cuniculias assessed by the two techniques.

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