Filamentous Ones Research Articles

Understanding filamentous cyanobacteria and their adaptive niches in Lake Honghu, a shallow eutrophic lake

Freshwater lakes globally are witnessing an escalation in the frequency and intensity of cyanobacterial harmful blooms. However, underlying factors influencing the succession or coexistence of cyanobacteria, especially filamentous ones, remain poorly understood. Lake Honghu, a Ramsar Wetland of International Importance with degrading aquatic ecological quality, served as a case study to elucidate the intricate relationship between environmental changes and cyanobacterial dynamics. Our analysis revealed a significant increase in the dominance of filamentous cyanobacteria, marked by high spatiotemporal variability in community structure. This dominance of filamentous diazotrophic cyanobacteria is attributed to a decrease in the ratio of dissolved inorganic nitrogen to total phosphorus and their capacity to utilize organic phosphorus in phosphorus-deficient conditions. Species-specific density variations were linked to diverse environmental factors, with total nitrogen or total phosphorus concentration remaining as a crucial factor influencing dominant cyanobacterial density fluctuations. The dominance of low-temperature-tolerant Aphanizomenon and Pseudanabaena was evident in spring and winter, whereas Dolichospermum and Cylindrospermopsis, which prefer higher temperatures, thrived in summer and autumn. Additionally, non-algal turbidity and heterogeneity can potentially alter the competitive outcome among filamentous cyanobacteria or foster coexistence under conditions of elevated temperatures and nutrient limitation. This study predicts that filamentous cyanobacteria may spread and persist in lakes spanning a wide trophic range. Current findings enhance our comprehension of the dynamic responses exhibited by filamentous bloom-forming cyanobacteria in the face of environmental changes within shallow eutrophic lakes and provide valuable insights for lake managers involved in the remediation of degraded shallow lakes.

Structural Insights into Plant Viruses Revealed by Small-Angle X-ray Scattering and Atomic Force Microscopy.

The structural study of plant viruses is of great importance to reduce the damage caused by these agricultural pathogens and to support their biotechnological applications. Nowadays, X-ray crystallography, NMR spectroscopy and cryo-electron microscopy are well accepted methods to obtain the 3D protein structure with the best resolution. However, for large and complex supramolecular structures such as plant viruses, especially flexible filamentous ones, there are a number of technical limitations to resolving their native structure in solution. In addition, they do not allow us to obtain structural information about dynamics and interactions with physiological partners. For these purposes, small-angle X-ray scattering (SAXS) and atomic force microscopy (AFM) are well established. In this review, we have outlined the main principles of these two methods and demonstrated their advantages for structural studies of plant viruses of different shapes with relatively high spatial resolution. In addition, we have demonstrated the ability of AFM to obtain information on the mechanical properties of the virus particles that are inaccessible to other experimental techniques. We believe that these under-appreciated approaches, especially when used in combination, are valuable tools for studying a wide variety of helical plant viruses, many of which cannot be resolved by classical structural methods.

Promising effect of propolis and a by-product on planktonic cells and biofilm formation by the main agents of human fungal infections.

Few antifungals available today are effective in treating biofilms. Thus, it is urgent to discover new compounds, such as natural products, that provide improvements to existing treatments or the development of new antifungal therapies. This study aimed to perform a comparative analysis between the green propolis extract (PE) and its by-product, a waste of propolis extract (WPE) through a screening with Candida sp., Fusarium sp. and Trichophyton sp. The antifungal property of PE and WPE was assessed by the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) determination in planktonic cells. The influence of both extracts on the inhibition of biofilm formation in these fungi was also tested. The WPE MIC and MFC values (68.75 to 275.0 µg/mL) were three to twelve times lower than the values obtained for PE (214.06 to 1712.5 µg/mL). PE was more efficient than WPE in inhibiting the biofilm initial phase, especially in C. albicans. Meanwhile, WPE had dose-dependent behavior for the three fungi, being more effective on filamentous ones. Both PE and WPE showed excellent antifungal activity on planktonic cells and demonstrated great efficacy for inhibiting biofilm formation in the three fungi evaluated.

A 10-Year Retrospective Clinical Analysis of Fungal Keratitis in a Portuguese Tertiary Centre.

PurposeTo determine the microbiological profile, risk factors, treatment and surgical intervention rates of fungal keratitis at a tertiary referral centre.MethodsA retrospective review of microbiological and medical records from hospitalised patients treated for fungal keratitis at Centro Hospitalar Universitário de São João from 2009 to 2019 was conducted.ResultsOverall, 43 patients were included in our study. The mean age of patients was 63.7 years and 46.5% were men. In culture were isolated 22 (51.2%) filamentous fungi and 21 (48.8%) yeast. Candida species (n = 20, 46.5%), Fusarium species (n = 10, 23.4%) and Aspergillus species (n = 4, 9.3%) were the most common isolated species. Important risk factors were contact lens use (n = 24, 55.8%), long-term users of topical corticosteroids (n = 19, 44.2%) and previous keratitis (n = 19, 44.2%). Yeast isolates had a statistically significant higher prevalence in long-term users of topical corticosteroids compared to filamentous ones (p = 0.043). Twenty-four cases (55.8%) required surgical intervention, of which 23 cases underwent therapeutic penetrating keratoplasty. Ocular complications, such as evisceration was noted in 12 patients (27.9%) and endophthalmitis in 5 (11.6%). No statistically significant changes of best corrected visual acuity (BCVA) were found after treatment (p = 0.687).ConclusionMost patients with fungal keratitis have associated risk factors. Filamentous and yeast species have equally prevalent etiologies. In general, our results mirror how difficult and challenging the approach and treatment of fungal keratitis could be.

A thermostable, chromatographically purified Ebola nano-VLP vaccine

BackgroundFilovirus virus-like particles (VLP) are strong immunogens with the potential for development into a safe, non-infectious vaccine. However, the large size and filamentous structure of this virus has heretofore made production of such a vaccine difficult. Herein, we present new assays and a purification procedure to yield a better characterized and more stable product.MethodsSonication of VLP was used to produce smaller “nano-VLP”, which were purified by membrane chromatography. The sizes and lengths of VLP particles were analyzed using electron microscopy and an assay based on transient occlusion of a nanopore. Using conformationally-sensitive antibodies, we developed an in vitro assay for measuring GP conformational integrity in the context of VLP, and used it to profile thermal stability.ResultsWe developed a new procedure for rapid isolation of Ebola VLP using membrane chromatography that yields a filterable and immunogenic product. Disruption of VLP filaments by sonication followed by filtration produced smaller particles of more uniform size, having a mean diameter close to 230 nm. These reduced-size VLP retained GP conformation and were protective against mouse-adapted Ebola challenge in mice. The “nano-VLP” consists of GP-coated particles in a mixture of morphologies including circular, branched, “6”-shaped, and filamentous ones up to ~1,500 nm in length. Lyophilization conferred a high level of thermostability on the nano-VLP. Unlike Ebola VLP in solution, which underwent denaturation of GP upon moderate heating, the lyophilized nano-VLP can withstand at least 1 h at 75°C, while retaining conformational integrity of GP and the ability to confer protective immunity in a mouse model.ConclusionsWe showed that Ebola virus-like particles can be reduced in size to a more amenable range for manipulation, and that these smaller particles retained their temperature stability, the structure of the GP antigen, and the ability to stimulate a protective immune response in mice. We developed a new purification scheme for “nano-VLP” that is more easily scaled up and filterable. The product could also be made thermostable by lyophilization, which is highly significant for vaccines used in tropical countries without a reliable “cold-chain” of refrigeration.Electronic supplementary materialThe online version of this article (doi:10.1186/s12967-015-0593-y) contains supplementary material, which is available to authorized users.

Chlorophytes of biological soil crusts in Gurbantunggut Desert, Xinjiang Autonomous Region, China

In this paper, chlorophytes collected from 253 biological soil crust samples in Gurbantunggut Desert in Xinjiang Autonomous Region, China were studied by field investigation and microscopical observation in lab. The flora composition, ecological distribution of chlorophytes in the desert and dynamic changes of species composition of chlorophytes in different developing stages of biological soil crusts are preliminarily analyzed. Results showed that there were 26 species belonging to 14 genera and 10 families, in which unicellular chlorophytes were dominant. There existed some differences in distribution of varied sand dune positions. The taxa of chlorophytes in leeward of sand dunes are most abundant, but the taxa in windward, interdune and the top of sand dunes reduced gradually. Chlorophytes were mainly distributed within the crust and the taxa of chlorophytes decrease obviously under the crust. In the developing stages of the biological soil crust, species diversity of chlorophytes changed a little, but species composition presented some differences. Chlorococcum humicola, Chlorella vulgaris, Chlamydomonas ovalis and Chlamydomonas sp. nearly existed in all developing stages of biological crusts. In several former stages of the biological soil crust there were spherical chlorophytes and filamentous ones. When moss crust formed, filamentous chlorophytes disappeared, such as Microspora and Ulothrix.

An Endolithic Microbial Community in Dolomite Rock in Central Switzerland: Characterization by Reflection Spectroscopy, Pigment Analyses, Scanning Electron Microscopy, and Laser Scanning Microscopy

A community of endolithic microorganisms dominated by phototrophs was found as a distinct band a few millimeters below the surface of bare exposed dolomite rocks in the Piora Valley in the Alps. Using in situ reflectance spectroscopy, we detected chlorophyll a (Chl a), phycobilins, carotenoids, and an unknown type of bacteriochlorophyll-like pigment absorbing in vivo at about 720 nm. In cross sections, the data indicated a defined distribution of different groups of organisms perpendicular to the rock surface. High-performance liquid chromatography analyses of pigments extracted with organic solvents confirmed the presence of two types of bacteriochlorophylls besides chlorophylls and various carotenoids. Spherical organisms of varying sizes and small filaments were observed in situ with scanning electron microscopy and confocal laser scanning microscopy (one- and two-photon technique). The latter allowed visualization of the distribution of phototrophic microorganisms by the autofluorescence of their pigments within the rock. Coccoid cyanobacteria of various sizes predominated over filamentous ones. Application of fluorescence-labeled lectins demonstrated that most cyanobacteria were embedded in an exopolymeric matrix. Nucleic acid stains revealed a wide distribution of small heterotrophs. Some biological structures emitting a green autofluorescence remain to be identified.

Formation and instability of aerobic granules under high organic loading conditions

The cultivation and instability of aerobic granular sludge in a sequencing batch reactor under high loading conditions were investigated. Compact bacteria-dominated aerobic granules with a mean diameter of 1 mm were formed at a chemical oxygen demand (COD) loading rate of 6.0 kg m −3 d −1 within 30 d. However, the compact bacteria-dominated aerobic granules were not stable and transited to large-sized filamentous ones gradually. With the formation of bacteria-dominated granules, the hydrophobicity and specific gravity of the sludge increased. When the granules were transited to filamentous ones, the hydrophobicity and specific gravity decreased. Both granules had a high COD removal efficiency, excellent settling ability and showed a clear, regular round-shaped outline. After the filamentous granules reached a diameter of 16 mm, due to the mass transfer limitation and the possible presence of anaerobes in the inner part of the granules, they began to disintegrate and be washed out of the reactor, follow by failure of the reactor.

Transmission electron microscopy of the scolex and neck microtriches of Silurotaenia siluri (Batsch, 1786) (Cestoda: Proteocephalidea)

Microtriches on different parts of the scolex and neck of the gangesiine cestode Silurotaenia siluri (Batsch 1786) were studied. The neodermis of the central frontal scolex part (around the rostellar furrow) bears filamentous microtriches only. The lateral frontal part and the parts between and posterior to the suckers cover filamentous and spine-like microtriches. Within the suckers there are short spine-like microtriches with bases enforced by electron-dense ribs. The proximal neck part bears filamentous and spine-like microtriches, the middle part solitary distributed blade-like and spine-like microtriches among filamentous ones, and the distal part blade-like microtriches. The functions of different types of microtriches are discussed.

SPECIES DIVERSITY GRADIENT TO DARKNESS STRESS IN BLUE-GREEN ALGAE/CYANOBACTERIA: A MICROSCALE TEST IN A PREHISTORIC CAVE, MOUNT CARMEL, ISRAEL

Species diversity of epilithic cyanobacteria was studied in a 90 m deep prehistoric el-Wad cave eroded in Cenomanian limestones of Mount Carmel, Israel. The degree of illumination is the most variable index throughout the cave, whereas humidity and temperature vary moderately. In a number of sites inside the cave dripping water occurs due to filtration of rain water. In el-Wad cave 42 species from 20 genera of blue-green algae were found. The share of coccoid forms decreased and filamentous (especially oscillatorial) ones increased from the entrance to the end of the cave. Intensity of light was the governing factor for distribution of cyanobacteria in el-Wad cave; the availability of dripping affected it to a lesser extent due to the constantly high humidity of the air. Diversity of species composition and taxonomic spectrum of cyanophytes was reduced from the entrance to the end of the cave, covarying positively with darkness stress.

Electrophoretic separation of two unicyanobacterial strains leading to purification

The Flat Bed Electrophoresis Apparatus FBE-3000 was used to obtain axenic cultures of the two unicyanobacterial strains Synechocystis sp. and Synechococcus sp. isolated from marine environments. All the cells examined migrated towards the anode with different mobilities separating cyanobacteria from accompanying chemoorganotrophic bacteria. Coccoid cyanobacteria remained viable in all cases while tests with filamentous species were less successful in terms of viability. However chemoorganotrophic bacteria were efficiently eliminated even from these filamentous ones.

Fine structure of influenza A virus observed by electron cryo-microscopy.

A rapidly frozen vitrified aqueous suspension of influenza A virus was observed by high resolution electron cryomicroscopy. The influenza particles were grouped into small (diameter < 150 nm) spherical particles with well organized interiors, large spherical ones with less internal organization, and filamentous ones. Envelopes of most of the large virus particles were phospholipid bilayers, and the chromatography fraction containing these large particles was largely devoid of viral activity. The envelopes of most of the filamentous and small spherical virus particles, on the other hand, gave a strange contrast which could be ascribed to a combination of a thin outer lipid monolayer and a 7.2 nm thick protein-containing inner layer. These latter particles represented most of the viral activity in the preparation. Densitometric traces of the near in-focus images confirmed these structural differences. Some viral envelope structures apparently intermediate between these two distinct types of membrane were also detected. A structural model of intact biologically active influenza virus particles was formulated from these results, together with computer simulations.

Gluconic acid production at high concentrations by Aspergillus niger immobilized on a nonwoven fabric

Batch production of gluconic acid in the presence of a high concentration of glucose was investigated using free and immobilized mycelia of Aspergillus niger IAM 2094 with the aim of achieving repeatable constant production. Accumulation of 300 g/ l of gluconate with a productivity of 60 g/ l·h was achievable by intermittent addition of powdered glucose using filamentous-form mycelia in the presence of 150 ppm dissolved oxygen. However, this productivity became unattainable after a few repetitions. The use of pellet-form mycelia, in place of filamentous ones, did not prove effective either. However, when the mycelia were immobilized on a nonwoven fabric, a sustained level (220 g/ l) of gluconate production was reproducible. Immobilized mycelia grown in a gas phase (air or oxygen) had a much longer durability than mycelia grown in a liquid culture medium. The gluconate-producing activity of immobilized mycelia grown in the presence of oxygen was much higher than that of mycelia grown in air. At 150 ppm dissolved oxygen, 220 g/ l of gluconate was repeatedly produced 14 times at a constant production rate in a period of about 1,000 h.

Erythrotrichopeltis, a new genus of the Erythropeltidaceae (Bangiophyceae, Rhodophyta)

In culture experimentsErythropeltis discigera (Berth.) Schmitz andErythrotrichia discigera Berth. proved to be heteromorphous stages in the life history of the same entity, incorporated into the new genusErythrotrichopeltis. There is no obligate alternation of generations, the peltoid and the trichoid phase both propagate asexually by monospores. In addition, the trichoid phase releases spermatia in abundance, while carpogonia cannot be distinguished from vegetative cells. Thus far, the present statements are in full accordance with Berthold's observations, made at Naples more than 100 years ago, which have, however, recently been challenged. Moreover, the cultivation experiments made supplement Berthold's results as to the post fertilization process. A few days after the appearance of spermatia, peltoid plants are met with among the filamentous ones: they obviously originate from carpospores. The transition of the peltoid to the trichoid phase, at first observed accidentally in 3-month old moribund cultures, was reconstructed on more than one occasion by designed experiments. This study was started with discoid plants isolated from crude cultures of sublitoral algae from Helgoland (North Sea). NeitherErythrotrichia discigera Berth. norErythropeltis discigera (Berth.) Schmitz were ever found in the field around Helgoland. Recognized by Batters to be identical withBangia ciliaris Carmichael, the name of the typical representative of the new genus isErythrotrichopeltis ciliaris (Carm. ex Harv. in Hook.) nov. comb.

Classification of Old World Velloziaceae

Summary. The Velloziaceae of the Old World have been revised, a new classification, incorporating anatomical evidence, is proposed, and a key to all the genera of the family is given. This is followed by identification keys, synonymy and distribution of the members of the two Old World genera, the monotypic South African genus Talbotia, and the genus Xerophyta which contains three sections, defined on anatomical features, and 28 species, 4 of which are described as new. In preparing a treatment of the Velloziaceae for the Flora of Tropical East Africa we have found it a necessary preliminary to review not only the Old World species but also the highly controversial generic limits of the whole family. The difficulties with generic limitation have been twofold. The first involves the choice and emphasis of limiting characters. The second stems from the attempt to classify Old World species under New World genera and vice versa. The first significant generic classification was that of Seubert in 'Flora Brasiliensis' (1847) where he keyed Barbacenia as having flattened bifid filaments and Vellozia filamentous ones. In the descriptions he further noted the dorsifixed anthers and capitate or clavate stigmas of Barbacenia as against the basifixed anthers and usually horizontal 3-lobed stigma of Vellozia. All of these characters correlated with each other and with the later noted features of leaf-anatomy. Most subsequent authors have misapplied these characters or used characters that do not correlate, such as the number of stamens or the length of the perianth-tube. In 1875 Baker revised the African species of Xerophyta on the basis of its six stamens and lack ofa perianth-tube, but included similar speciesof Vellozia without noting the distinctions of filament and stigma. Later (1889, 1896) he reversed the synonymy in favour of the earlier Vellozia and this time included all species regardless of the number of stamens. Pax (1887) distinguished the genera by the number and position of the stamens. He placed all species with six stamens under Barbacenia and species with more than six under Vellozia. Baillon (1895) united all species under Barbacenia while Durand & Schinz treated all African members, including Talbotia, as Xerophyta. The first serious attempt to revise all Old World species of the Velloziaceae was by Greves (1921) who classified them all as Vellozia with characterization based on the lack of a perianth-tube. Smith (1962) also overlooked the great distinction in stigmas. Perrier (1946) pointed out, when preparing for the revision of the Velloziaceae of Madagascar, that botanists are not at all in agreement on the taxonomy of the family. However, he could recognize three genera: Xerophyta, Vellozia, and Barbacenia. Hutchinson (1934) was indeed right in suggesting that 'The family needs a careful monograph, and possibly more than two genera should be recog

A Peculiar New Species of Trichomanes sect. Selenodesmium and Several of Its Probable Hybrids

On December 27, 1965 a peculiar species of Trichomanes, first thought to be in the sect. Davalliopsis, was collected in New Caledonia. It proved to be the first species of Trichomanes sect. Selenodesmium that has leaf blades more than one cell thick. The relatively exposed habitat (altitude ca. 300 m along the trail from the Dumbea Dam to Montagne des Sources) which, however, seemed to be supplied with subsurface water, correlates with the nearly sclerophyllous fronds of the new species. Substratum samples unfortunately yielded no hymenophyllaceous gametophytes, only thallose ones identified as Blechnum sp. and filamentous ones clearly belonging to Schizaea fistulosa. Bierhorst NC460 included two mature specimens, and Bierhorst NC465 included one sterile, halfgrown plant with associated substratum. The material was preserved in a chromic acid-acetic acid-formaldehyde solution in the field and was later transferred to glycerine alcohol. Type material will be dried and deposited in the Gray Herbarium, Harvard University. Freehand sections of all parts of the plant were prepared and stained with 1% Methyl Green for 5 min followed by two rinses in water. The sections illustrated in Figs. 11 and 13-18 were prepared in this manner. The cleared leaf shown in Figs. 4 and 20-22 was bleached in Clorox until white (ca. 15 min; monostromaticous species generally take 1-3 min), rinsed with three changes of water, dehydrated in 70%, 95%, and 100% ethanol (5 min each). It was then stained with Fast Green (1% in 100% ethanol) for 3-5 min, rinsed in two changes of 100% ethanol (total ca. 5 min), then one change of 1:1 xylene-absolute ethanol, then cleared in xylene (two changes of 5 min each), and finally mounted in synthetic resin HSR. The new species is designated:

What is Australia antigen?

When negatively stained preparations of Australia antigen are examined in the electron microscope, three types of particle can be distinguished. The most plentiful are approximately spherical and about 160 to 220 angstroms in diameter. Substructure is difficult to find, but the appearance suggests that the particles are built up of a number of identical subunits. 1 Long particles are also seen in most instances. These have about the same diameter as the small spherical particles but vary greatly in length from bacilliform or ovoid structures to long filamentous ones. Some have expanded ends, some are bent at sharp angles, and many exhibit cross-striations which have a periodicity of 35 A. 2 The third particle type is the double-shelled or doughnut form which is about 450 A in diameter and consists of a central core which is sometimes penetrated by the stain, surrounded by a shell which also seems to be

Changes in mitochondrial structure of dimorphic cells of Endomycopsis fibuligera in saline medium.

Since we first developed in 1964 to investigate electronmicroscopically the fine structure of an yeast,Endomycopsis fibuligera which behaves to grow in dimorphic type of the cell, namely yeast-like and filamentous ones, many papers concerned with the representations of the cell structure in comparison between two types of the cell. The purpose of the present investigation, therefore, is to clarify the significance of the effect of NaCl-hypertonicity on the structural changes in the grown cells in each type and the intracellular localization of NaCl taken up by the cells. An unique feature of grown cells in NaCl medium under shaking condition was a reminiscence of membrane system, resulted from the progressive degradation of mitochondria in growing cells. The difference of pronounced changes in mitochondrial degradation between yeast-like and filamentous cells indicated that the shape and the structure were differently linked to the cell metabolism in each type. This evidence has been approached by considering the comparative biogenesis of the irregular outline of vacuole in shape and the intravacuolar localization of NaCl taken up by the cell. The mitochondria can be identified both as a specific structural and a specific biochemical system, and current investigations aim at a more detailed understanding of the relationship between metabolic activity and structure. Halophytes and halophilic microorganisms must grow with high energy efficiency supplied by mitochondrial function to overcome the severe saline environment (Yabe et al. 1965, 1966). Conversely, although it has been obvious that slight but significant departures from a linear growth response of a non-halophilic yeast such asEndomycopsis fibuligera (formerly nomenclatured asE. fibuliger), under saline condition, must be taken into account of a specific ion effect in addition to the osmotic effect as so called dual effect, it will be expected that the progressive increase in cellular osmotic pressure with increasing salt concentration of external medium was directly and primarily related to the formation and the function of the mitochondria during decreased growth by added salt (Takada andKasakawa 1966 a, b). On the other hand, we have previously reported that when the cells ofEndomycopsis fibuligera were grown anaerobically, we could not found any mitochondrial structure within the cell and found concentrically arranged membrane system by means of electron microscopy (Hiraoka et al. 1966 b). There has been another experimental basis for believing that added NaCl or LiCl to hypertonic medium might to disintegrate the mitochondrial structure during growth, because this condition induced to enhance the anaerobic respiration associated with the depressed aerobic respiration accompanied with modified and different cytochrome pattern. A correlated ultrastructural study of mitochondrial structural states inEndomycopsis fibuligera has provided direct evidence of the effect of saline condition on mitochondrial morphologyin vivo.