Journal of Eukaryotic Microbiology

Publisher: Society of Protozoologists; International Society of Protistologists, Blackwell Publishing

Description

  • Impact factor
    2.16
  • 5-year impact
    2.24
  • Cited half-life
    8.70
  • Immediacy index
    0.60
  • Eigenfactor
    0.00
  • Article influence
    0.67
  • Other titles
    Journal of eukaryotic microbiology (Online), The journal of eukaryotic microbiology
  • ISSN
    1550-7408
  • OCLC
    47723595
  • Material type
    Document, Periodical, Internet resource
  • Document type
    Internet Resource, Computer File, Journal / Magazine / Newspaper

Publisher details

Blackwell Publishing

  • Pre-print
    • Author can archive a pre-print version
  • Post-print
    • Author cannot archive a post-print version
  • Restrictions
    • Some journals impose embargoes typically of 6 or 12 months, occasionally of 24 months
    • no listing of affected journals available as yet
  • Conditions
    • See Wiley-Blackwell entry for articles after February 2007
    • Publisher's version/PDF cannot be used
    • On author's server, institutional server or subject-based server
    • Server must be non-commercial
    • Publisher copyright and source must be acknowledged with set statement ("The definitive version is available at www.blackwell-synergy.com")
    • Articles in some journals can be made Open Access on payment of additional charge
    • 'Blackwell Publishing' is an imprint of 'Wiley'
  • Classification
    ​ yellow

Publications in this journal

  • [Show abstract] [Hide abstract]
    ABSTRACT: We investigated the toxicity of Karenia mikimotoi toward three model grazers, the cladoceran Moina mongolica, the copepod Pseudodiaptomus annandalei and the crustacean Artemia salina, and explored its chemical response upon zooplankton grazing. An induction experiment, where K. mikimotoi was exposed to grazers or waterborne cues from the mixed cultures revealed that K. mikimotoi might be toxic or nutritionally inadequate toward the three grazers. In general, direct exposure to the three grazers induced the production of hemolytic toxins and the synthesis of eicosapentaenoic acid (EPA). Both EPA and the hemolytic toxins from K. mikimotoi decreased the survival rate of the three grazers. In addition, the survival rates of M. mongolica, P. annandalei and A. salina in the presence of induced K. mikimotoi that had previously been exposed to a certain grazer were lower than their counterparts caused by fresh K. mikimotoi, suggesting that exposure to some grazers might increase the toxicity of K. mikimotoi. The chemical response and associated increased resistance to further grazing suggested that K. mikimotoi could produce deterrents to protect against grazing by zooplankton and that the substances responsible might be hemolytic toxins and EPA.This article is protected by copyright. All rights reserved.
    Journal of Eukaryotic Microbiology 12/2014;
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    ABSTRACT: The benthic foraminifer Virgulinella fragilis Grindell and Collen 1976 has multiple putative symbioses with both bacterial and kleptoplast endobionts, possibly aiding its survival in environments from dysoxia (5-45 μmol-O2/liter) to microxia (0-5 μmol-O2/liter) and in the dark. To clarify the origin and function of V. fragilis endobionts, we used genetic analyses and transmission electron microscope observations. Virgulinella fragilis retained δ-proteobacteria concentrated at its cell periphery just beneath the cell membranes. Unlike another foraminifer Stainforthia spp., which retain many bacterial species, V. fragilis has a less variable bacterial community. This suggests that V. fragilis maintains specific intracellular bacterial flora. Unlike the endobiotic bacteria, V. fragilis kleptoplasts originated from various diatom species and are found in the interior cytoplasm. We found evidence of both retention and digestion of kleptoplasts, and of fragmentation of the kleptoplastid outer membrane that likely facilitates transport of kleptoplastid products to the host. Accumulations of mitochondria were observed encircling endobiotic bacteria. It is likely that the bacteria use host organic material for carbon oxidation. The mitochondria may use oxygen available around the δ-proteobacteria and synthesize ATP, perhaps for sulfide oxidation.This article is protected by copyright. All rights reserved.
    Journal of Eukaryotic Microbiology 12/2014;
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    ABSTRACT: Prorocentrum minimum is a neritic dinoflagellate that forms seasonal blooms and red tides in estuarine ecosystems. While known to be mixotrophic, previous attempts to document feeding on algal prey have yielded low grazing rates. In this study, growth and ingestion rates of P. minimum were measured as a function of nitrogen (-N) and phosphorous (-P) starvation. A P. minimum isolate from Chesapeake Bay was found to ingest cryptophyte prey when in stationary phase and when starved of N or P. P. minimum ingested two strains of Teleaulax amphioxeia at higher rates than 6 other cryptophyte species. In all cases -P treatments resulted in the highest grazing. Ingestion rates of -P cells on T. amphioxeia saturated at ~5 prey predator−1 day−1, while ingestion by -N cells saturated at 1 prey predator−1 day−1. In the presence of prey, -P treated cells reached a maximum mixotrophic growth rate (μmax) of 0.5 d−1, while -N cells had a μmax of 0.18 d−1. Calculations of ingested C, N, and P due to feeding on T. amphioxeia revealed that phagotrophy can be an important source of all three elements. While P. minimum is a proficient phototroph, inducible phagotrophy is an important nutritional source for this dinoflagellate.This article is protected by copyright. All rights reserved.
    Journal of Eukaryotic Microbiology 12/2014;
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    ABSTRACT: The isolate ATCC® 50979™ is a small amoebozoan whose actin gene was previously characterized, but did not allow a stable phylogenetic placement. This isolate was originally mis-identified upon deposition, and subsequently mis-illustrated in a recent publication. Here, we provide both a detailed morphological description as well as additional molecular analyses in order to clarify the isolate's phylogenetic relationships. The amoeba is minute (less than 5μm), and presents the behavior of staying in a fixed location, while emitting one or two thin pseudopods. Transmission electron-microscopy reveals that the cell is covered in a layer with embedded scales, giving the cell an armored appearance. Molecular phylogenetic analyses of data (actin, alpha- and beta- tubulin, elongation factor 2, and 14-3-3) from transcriptomes of this and four other isolates reveals that ATCC® 50979™ is closely related to the recently described Squamamoeba japonica and in a novel, stable clade. Due to the unique nature of the scale covering, as well as other gross morphological characters and the molecular phylogenetic analyses, we formally describe the isolate as Sapocribrum chincoteaguense n. gen. n. sp. This article is protected by copyright. All rights reserved.
    Journal of Eukaryotic Microbiology 12/2014;
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    ABSTRACT: Toxoplasma gondii infects virtually all warm-blooded hosts worldwide. Recently, attention has been focused on the genetic diversity of the parasite to explain its pathogenicity in different hosts. It has been hypothesized that interaction between feral and domestic cycles of T. gondii may increase unusual genotypes in domestic cats and facilitate transmission of potentially more pathogenic genotypes to humans, domestic animals, and wildlife. In the present study, we tested black bear (Ursus americanus), bobcat (Felis rufus), and feral cat (Felis catus) from the state of Pennsylvania for T. gondii infection. Antibodies to T. gondii were found in 32 (84.2%) of 38 bears, both bobcats, and 2 of 3 feral cats tested by the modified agglutination test (cut off titer 1:25). Hearts from seropositive animals were bioassayed in mice, and viable T. gondii was isolated from 3 of 32 bears, 2 of 2 bobcats, and 2 of 3 feral cats. DNA isolated from culture-derived tachyzoites of these isolates was characterized using multilocus PCR-RFLP markers. Three genotypes were revealed, including ToxoDB PCR-RFLP genotype #1 or #3 (Type II, 1 isolate), #5 (Type 12, 3 isolates), and #216 (3 isolates), adding to the evidence of genetic diversity of T. gondii in wildlife in Pennsylvania. Pathogenicity of 3 T. gondii isolates (all #216, 1 from bear, and 2 from feral cat) was determined in outbred Swiss Webster mice; all three were virulent causing 100% mortality. Results indicated that highly mouse pathogenic strains of T. gondii are circulating in wildlife, and these strains may pose risk to infect human through consuming of game meat. This article is protected by copyright. All rights reserved.
    Journal of Eukaryotic Microbiology 11/2014;
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    ABSTRACT: We studied the protist grazers of Boiling Springs Lake (BSL), an acid geothermal feature in Lassen Volcanic National Park, using a combination of culture and genetic approaches. The major predator in BSL is a vahlkampfiid amoeba closely related (95% 18S+ITS rRNA identity) to Tetramitus thermacidophilus, a heterolobose amoeboflagellate recently isolated from volcanic geothermal acidic sites in Europe and Russia, as well as an uncultured heterolobosean from the nearby Iron Mountain acid mine drainage site. T. thermacidophilus strain BSL is capable of surviving the physical extremes of BSL, with optimal growth at 38-50 °C and pH 2-5. This bacterivore also ingested conidiospores of the ascomycete Phialophora sp., but ultrastructural observations reveal the latter may not be readily digested, and conidia were not separable from the ameoboflagellate culture, suggesting a possible symbiosis. DGGE fingerprint transects studies showed the organism is restricted to near-lake environs, and we detected an average of ~500 viable cysts mg−1 on the shoreline. Other grazing protists were isolated from lakeshore environments, including the lobose amoebae Acanthamoeba sp. and Hartmannella sp., and the kinetoplastid flagellate Bodo sp., but none could tolerate both low pH and high temperature. These appear to be restricted to cooler near-lake geothermal features, which also contain other potential grazer morphotypes observed but not successfully cultured, including ciliates, euglenids, testate amoebae, and possible cercozoans. We compare the food web of BSL with other acidic or geothermal sites, and discuss the impact of protists in this unique environment.This article is protected by copyright. All rights reserved.
    Journal of Eukaryotic Microbiology 11/2014;
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    ABSTRACT: Traditionally classifications of the Urostyloida have been mainly based on morphology and morphogenesis. Recent molecular phylogenetic analyses have been largely based on single-gene data for a limited number of taxa. Consequently, incongruence has arisen between the morphological/morphogenetic and the molecular data. In this study, the three phylogenetic markers (SSU rDNA, ITS1-5.8S-ITS2 region and LSU-rDNA) of three urostyloid genera represented by four species (Bakuella granulifera, Anteholosticha monilata, Caudiholosticha sylvatica and C. tetracirra) were sequenced in order to investigate their phylogeny. The results show that: (1) all three genera should be regarded as the members of the order Urostyloida within the subclass Hypotrichia, as indicated by morphological characters; (2) phylogenetic analyses and sequence similarities both indicate that neither Anteholosticha nor Caudiholosticha are monophyletic and the systematic assignment of both genera awaits further evaluation; and (3) Bakuella has a closer relationship with Urostyla than with bakuellids (e.g. Apobakuella and Metaurostylopsis), suggesting Bakuella may belong to the family Urostylidae rather than the family Bakuellidae.This article is protected by copyright. All rights reserved.
    Journal of Eukaryotic Microbiology 11/2014;
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    ABSTRACT: Photosynthetic euglenids acquired chloroplasts by secondary endosymbiosis, which resulted in changes to their mode of nutrition and affected the evolution of their morphological characters. Mapping morphological characters onto a reliable molecular tree could elucidate major trends of those changes. We analyzed nucleotide sequence data from regions of three nuclear-encoded genes (nSSU, nLSU, hsp90), one chloroplast-encoded gene (cpSSU) and one nuclear-encoded chloroplast gene (psbO) to estimate phylogenetic relationships among 59 photosynthetic euglenid species. Our results were consistent with previous works; most genera were monophyletic, except for the polyphyletic genus Euglena, and the paraphyletic genus Phacus. We also analyzed character evolution in photosynthetic euglenids using our phylogenetic tree and eight morphological traits commonly used for generic and species diagnoses, including: characters corresponding to well-defined clades, apomorphies like presence of lorica and mucilaginous stalks, and homoplastic characters like rigid cells and presence of large paramylon grains. This research indicated that pyrenoids were lost twice during the evolution of phototrophic euglenids, and that mucocysts, which only occur in the genus Euglena, evolved independently at least twice. In contrast, the evolution of cell shape and chloroplast morphology was difficult to elucidate, and could not be unambiguously reconstructed in our analyses.This article is protected by copyright. All rights reserved.
    Journal of Eukaryotic Microbiology 11/2014;
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    ABSTRACT: T and B cell-deficient BALB/c SCID mice become severely ill and die of amoebic encephalitis after intranasal infection with Balamuthia mandrillaris, while adult immunocompetent BALB/c wild-type (WT) mice are resistant. To further investigate the role of lymphocytes in protection from Balamuthia amoebic encephalitis (BAE), SCID mice were reconstituted with and WT mice selectively depleted of lymphocytes before infection. Reconstitution of SCID mice with whole spleen cells from WT mice rendered the recipients as resistant to BAE as WT mice. SCID mice that had received spleen cells depleted of CD4+ T cells remained susceptible. When adult WT mice were depleted of both CD4+ and CD8+ T cells or of CD4+ T cells alone, these mice also became susceptible to BAE. Depletion of CD8+ T cells alone increased susceptibility only marginally. All morbidity and mortality data were underpinned by histological analysis of the brain.This article is protected by copyright. All rights reserved.
    Journal of Eukaryotic Microbiology 11/2014;
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    ABSTRACT: Monothalamous (single-chambered) foraminifera have long been considered as the “poor cousins” of multi-chambered species, which calcareous and agglutinated tests dominate in the fossil record. This view is currently changing with environmental DNA surveys showing that the monothalamids may be as diverse as hard-shelled foraminifera. Yet, the majority of numerous molecular lineages revealed by eDNA studies remain anonymous. Here, we describe a new monothalamous species and genus isolated from the sample of sea grass collected in Gulf of Eilat (Red Sea). This new species, named Leannia veloxifera, is characterized by a tiny ovoid theca (about 50-100μm) composed of thin organic wall, with two opposite apertures. The examined individuals are multinucleated and show very active reticulopodial movement. Phylogenetic analyses of SSU rDNA, actin and beta-tubulin (ß-tubulin) show that the species represents a novel lineage branching separately from other monothalamous foraminifera. Interestingly, the SSU rDNA sequence of the new species is very similar to an environmental foraminiferal sequence from Bahamas, suggesting that the novel lineage may represent a group of shallow-water tropical allogromiids, poorly studied until now.This article is protected by copyright. All rights reserved.
    Journal of Eukaryotic Microbiology 11/2014;
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    ABSTRACT: Hemistasia phaeocysticola is a marine flagellate that preys on diatoms and dinoflagellates among others. Although its morphology and ultrastructure were previously observed and characterized, its phylogenetic position has not been analyzed using molecular sequence data. This flagellate was classified as a kinetoplastid on the basis of the presence of a kinetoplast in the mitochondrion. However, several morphological characteristics similar to those of diplonemids, a sister group of kinetoplastids, have also been noted. Herein, we report that H. phaeocysticola branches within the diplonemid clade in the phylogenetic tree reconstructed by analyzing 18S rRNA gene sequences. Its systematic placement based on this finding is also discussed.This article is protected by copyright. All rights reserved.
    Journal of Eukaryotic Microbiology 11/2014;
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    ABSTRACT: This study analyses the morphological characters of Strombidium paracalkinsi, a species bearing thigmotactic membranelles, collected from Jangmok Bay at the southern coast of Korea. The small subunit ribosomal RNA (SSU rRNA) gene of S. paracalkinsi was sequenced for the first time. By a combination of characters, the thigmotactic membranelles of Strombidium paracalkinsi differ from the thigmotactic membranelles of other strombidiids. They are 1) positioned on dorsal side; 2) contiguous with three membranelles of the adoral zone, but separated by non-ciliated portions of the polykinetids and 3) composed of two rows of kinetids. Except for the thigmotactic membranelles, the morphology of Strombidium paracalkinsi conforms to the diagnosis of the genus Strombidium. Our phylogenetic tree confirms the non-monophyly of the genus Strombidium. The thigmotactic membranelles are a promising feature for a future split of the genus Strombidium, but require further studies, especially on Strombidium calkinsi Fauré-Fremiet 1932.This article is protected by copyright. All rights reserved.
    Journal of Eukaryotic Microbiology 11/2014;
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    ABSTRACT: Free-living amoebae are ubiquitous protozoa commonly found in water. Among them, Acanthamoeba and Vermamoeba (formerly Hartmannella) are the most represented genera. In case of stress, such as nutrient deprivation or osmotic stress, these amoebae initiate a differentiation process, named encystment. It leads to the cyst form, which is a resistant form enabling amoebae to survive in harsh conditions and resist disinfection treatments. Encystment has been thoroughly described in Acanthamoeba but poorly in Vermamoeba. Our study was aimed to follow the encystment/excystment processes by microscopic observations. We show that encystment is quite rapid, as mature cysts were obtained in 9h, and that cyst wall is composed of two layers. A video shows that a locomotive form is likely involved in clustering cysts together during encystment. As for Acanthamoeba, autophagy is likely active during this process. Specific vesicles, possibly involved in ribophagy, were observed within the cytoplasm. Remarkably, mitochondria rearranged around the nucleus within the cyst, suggesting high needs in energy. Unlike Acanthamoeba and Naegleria, no ostioles were observed in the cyst wall suggesting that excystment is original. During excystment, large vesicles, likely filled with hydrolases, were found in close proximity to cyst wall and digest it. Trophozoite moves inside its cyst wall before exiting during excystment. In conclusion, Vermamoeba encystment/excystment displays original trends as compare to Acanthamoeba.This article is protected by copyright. All rights reserved.
    Journal of Eukaryotic Microbiology 10/2014;
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    ABSTRACT: Chagas disease, a chronic systemic parasitosis caused by the Kinetoplastid protozoon Trypanosoma cruzi, is the first cause of cardiac morbidity and mortality in poor rural and suburban areas of Latin America and the largest parasitic disease burden in the continent, now spreading worldwide due to international migrations. A recent change of the scientific paradigm on the pathogenesis of chronic Chagas disease has led to a consensus that all T. cruzi-seropositive patients should receive etiological treatment. This important scientific advance has spurred the rigorous evaluation of the safety and efficacy of currently available drugs (benznidazole and nifurtimox) as well as novel anti-T. cruzi drug candidates in chronic patients, who were previously excluded from such treatment. The first results indicate that benznidazole is effective in inducing a marked and sustained reduction of the circulating parasites’ level in the majority of these patients, but adverse effects can lead to treatment discontinuation in 10-20% of cases. Ergosterol biosynthesis inhibitors, such as posaconazole and ravuconazole, are better tolerated but their efficacy at the doses and treatment duration used in the initial studies was significantly lower; such results are probably related to suboptimal exposure and/or treatment duration. Combination therapies are a promising perspective but the lack of validated biomarkers of response to etiological treatment and eventual parasitological cures in chronic patients remains a serious challenge.This article is protected by copyright. All rights reserved.
    Journal of Eukaryotic Microbiology 10/2014;
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    ABSTRACT: High-throughput DNA sequencing platforms are continuing to increase resulting read lengths, which is allowing for a deeper and more accurate depiction of environmental microbial diversity. With the nascent Reagent Kit v3, Illumina MiSeq now has the ability to sequence the eukaryotic hyper-variable V4 region of the SSU-rDNA locus with paired-end reads. Using DNA collected from soils with analyses of strictly- and nearly-identical amplicon, here we ask how the new Illumina MiSeq data compares with what we can obtain with Roche/454 GS FLX in regards to quantity and quality, presence and absence, and abundance perspectives. We show that there is an easy qualitative transition from the Roche/454 to the Illumina MiSeq platforms. The ease of this transition is more nuanced quantitatively for low-abundant amplicons, although estimates of abundances are known to also vary within platforms.This article is protected by copyright. All rights reserved.
    Journal of Eukaryotic Microbiology 10/2014;
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    ABSTRACT: Hammondia hammondi and Toxoplasma gondii are feline coccidian that are morphologically, antigenically, and phylogenitically related. Both parasites multiply asexually and sexually in feline intestinal enterocytes but H. hammondi remains confined to enterocytes whereas T. gondii also parasitizes extra-intestinal tissues of the cat. Here, we studied multiplication of H. hammondi in feline intestine and compared with T. gondii cycle. Five parasite–free cats were inoculated orally with tissue cysts and free bradyzoites from skeletal muscles of gamma interferon gene knock out mice and killed at 1, 3, 4, 6, and 7 days later. At 1 and 3 day post inoculation (DPI) numerous individual intracellular bradyzoites were detected in histological sections of small intestine. At 4 DPI only schizonts were found and they were located in enterocyte cytoplasm above the host cell nucleus. At 6 and 7 DPI both schizonts and gamonts were seen and they were located in enterocytes. Ultrastucturally, schizogonic and gametogonic development of H. hammondi was similar to T. gondii. However, in H. hammondi merozoites rhoptries were longer, and coiled and contained more micronemes than in T. gondii. Ultrastructural development is illustrated in detail.This article is protected by copyright. All rights reserved.
    Journal of Eukaryotic Microbiology 10/2014;
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    ABSTRACT: Species of Acanthamoeba were first described using morphological characters including cyst structure and cytology of nuclear division. More than twenty nominal species were proposed using these methods. Morphology, especially cyst shape and size, has proven to be plastic and dependent upon culture conditions. The DNA sequence of the nuclear small subunit (18S) rRNA, the Rns gene, has become the most widely accepted method for rapid diagnosis and classification of Acanthamoeba. The Byers-Fuerst lab first proposed an Rns typing system in 1996. Subsequent refinements, with an increasing DNA database and analysis of diagnostic fragments within the gene, have become widely accepted by the Acanthamoeba research community. The development of the typing system, including its current state of implementation is illustrated by three cases: (i) the division between sequence types T13 and T16; (ii) the diversity within sequence supertype T2/T6, and (iii) verification of a new sequence type, designated T20. Molecular studies make clear the disconnection between phylogenetic relatedness and species names, as applied for the genus Acanthamoeba. Future reconciliation of genetic types with species names must become a priority, but the possible shortcomings of the use of a single gene when reconstructing the evolutionary history of the acanthamoebidae must also be resolved.This article is protected by copyright. All rights reserved.
    Journal of Eukaryotic Microbiology 10/2014;
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    ABSTRACT: Ciliate nuclear architecture, in particular the sequestration of a transcriptionally silent germline genome, allows for the accumulation of mutations that are “hidden” from selection during many rounds of asexual reproduction. After sexual conjugation, these mutations are expressed, potentially resulting in highly variable phenotypes. Morphological traits are widely used in ciliate taxonomy, however, the extent to which the values of these traits are robust to change in the face of mutation is largely unknown. In this study, we examine the effects of mutations accumulated in the germline genome to test the mutational robustness of four traits commonly used in ciliate morphological taxonomy (number of somatic kineties, number of post-oral kineties, macronuclear size, and cell size). We find that the number of post-oral kineties is robust to mutation, confirming that it should be preferentially used in taxonomy. By contrast, we find that, as in other unicellular and multicellular species, cell/macronucleus size changes in response to mutation. Thus, we argue that cell/macronucleus sizes, which are widely used in taxonomy, should be treated cautiously for species identification. Finally, we find evidence of correlations between cell and macronucleus sizes and fitness, suggesting possible mutational pleiotropy. This study demonstrates the importance of, and methods for, determining mutational robustness to guide morphological taxonomy in ciliates.This article is protected by copyright. All rights reserved.
    Journal of Eukaryotic Microbiology 09/2014;