Unbranched Filaments Research Articles

CryoET of β-amyloid and tau within postmortem Alzheimer’s disease brain

A defining pathological feature of most neurodegenerative diseases is the assembly of proteins into amyloid that form disease-specific structures1. In Alzheimer’s disease, this is characterized by the deposition of β-amyloid and tau with disease-specific conformations. The in situ structure of amyloid in the human brain is unknown. Here, using cryo-fluorescence microscopy-targeted cryo-sectioning, cryo-focused ion beam-scanning electron microscopy lift-out and cryo-electron tomography, we determined in-tissue architectures of β-amyloid and tau pathology in a postmortem Alzheimer’s disease donor brain. β-amyloid plaques contained a mixture of fibrils, some of which were branched, and protofilaments, arranged in parallel arrays and lattice-like structures. Extracellular vesicles and cuboidal particles defined the non-amyloid constituents of β-amyloid plaques. By contrast, tau inclusions formed parallel clusters of unbranched filaments. Subtomogram averaging a cluster of 136 tau filaments in a single tomogram revealed the polypeptide backbone conformation and filament polarity orientation of paired helical filaments within tissue. Filaments within most clusters were similar to each other, but were different between clusters, showing amyloid heterogeneity that is spatially organized by subcellular location. The in situ structural approaches outlined here for human donor tissues have applications to a broad range of neurodegenerative diseases.

1.63-billion-year-old multicellular eukaryotes from the Chuanlinggou Formation in North China.

Multicellularity is key to the functional and ecological success of the Eukarya, underpinning much of their modern diversity in both terrestrial and marine ecosystems. Despite the widespread occurrence of simple multicellular organisms among eukaryotes, when this innovation arose remains an open question. Here, we report cellularly preserved multicellular microfossils (Qingshania magnifica) from the ~1635-million-year-old Chuanlinggou Formation, North China. The fossils consist of large uniseriate, unbranched filaments with cell diameters up to 190 micrometers; spheroidal structures, possibly spores, occur within some cells. In combination with spectroscopic characteristics, the large size and morphological complexity of these fossils support their interpretation as eukaryotes, likely photosynthetic, based on comparisons with extant organisms. The occurrence of multicellular eukaryotes in Paleoproterozoic rocks not much younger than those containing the oldest unambiguous evidence of eukaryotes as a whole supports the hypothesis that simple multicellularity arose early in eukaryotic history, as much as a billion years before complex multicellular organisms diversified in the oceans.

FRESHWATER STROMATOLITES FROM AN EARLY PERMIAN WETLAND (MANEBACH, THURINGIAN-FOREST BASIN, GERMANY): STRUCTURE, DEVELOPMENT, AND PALEOENVIRONMENTAL CONTEXT

Abstract Fossil stromatolites enclosing structurally preserved land plant remains have rarely been documented and studied in detail. Permineralized woody Tylodendron sp. conifer axes (slender stems, branches) from a lacustrine sedimentary sequence in the lower Permian fossil Lagerstätte of Manebach (Thuringian-Forest Basin, central Germany) are frequently surrounded by stromatolites that consist of successive, usually asymmetrical microbial layers. The stromatolites show various growth forms ranging from laminar to palisadic. They developed in stagnant water from microbial overgrowth dominated by slender, unbranched sessile cyanobacterial filaments aligned vertically into tufts or turf-like stands. Interspersed among the filaments were other filamentous and coccoid microorganisms. Preservation of the Tylodendron axes can be exquisite and sometimes even includes extraxylary tissues containing remains of fungi, suggesting that stromatolite formation began soon after the axes had entered the water and were perhaps even conducive to their preservation. Structurally similar fossil microbialitic structures from elsewhere likewise demonstrate that they were effective in preserving plant morphology. The Manebach stromatolites and the plant remains they contain contribute to a more accurate understanding of the complex biological processes in late Paleozoic lake ecosystems.

Whey protein isolate nanofibrils formed with phosphoric acid: Formation, structural characteristics, and emulsion stability

In this study, phosphoric acid was used to replace hydrochloric acid which is widely reported in the production of whey protein isolate fibrils (WPF). The pH, temperature, and protein concentration for the phosphoric acid-induced fibrillation were optimized (4% w/v, pH 2.5, 90 °C). Under this condition, the mean particle size and molecular weight decreased significantly while the ζ-potential increased slightly, it suggested that the fibrillation was accompanied by hydrolysis. WPF was already formed via intermolecular interactions at 6 h, which exhibited a semiflexible and unbranched filament of about 10 nm in diameter. A few single-filament flexible fibrils (about 5 nm in diameter) formed at 24 h. Thioflavin T analysis supported by Intrinsic fluorescence showed that the use of phosphoric acid accelerated the fibrillation. The ANS fluorescence and Second-derivative UV–vis spectra indicated the increase in surface hydrophobicity, peaking after 12 h of heating. Compared with the hydrochloric acid induced, WPF induced by phosphoric acid exhibited a shorter lag phase and maintained a more stable dispersion state with a nanoscale particle size. The great interfacial properties and proper aspect ratio (length/diameter) provided the contribution that WPF effectively absorbed at the oil-water interface. Moreover, the emulsion stability of the WPF improved with increasing salt concentration. The phosphoric acid-induced WPF had the best emulsion stability at pH 5.5 which was further enhanced by proper heating. • The whey protein isolate fibrils (WPF) were formed via phosphoric acid. • The optimal preparation of WPF was at pH 2.5, 4%, 90 °C. • The surface hydrophobicity of WPF-12 (WPF formed at 12 h) reached the highest. • The WPF-12 exhibited excellent emulsion stability at pH 5.5.

Two different morphotypes of freshwater Cladophora surera (Cladophorales, Chlorophyta) produce similar sulfated cell wall polysaccharides

The Cladophoraceae (Cladophorales) includes branched (Cladophora) and unbranched (Chaetomorpha and Rhizoclonium) filamentous species, living in marine and freshwater environments. Species-level taxonomy is impeded by considerable morphological plasticity, related to environmental conditions, and switches between branched and unbranched morphologies have been reported within species. In this work, it was shown that Cladophora surera, a species widely distributed in streams in the Pampa Plains of Argentina, appears in two different morphotypes, branched and unbranched filaments. Phylogenetic analysis indicated that they correspond to the same species. The presence of these morphotypes could not be related with season or water flow. Moreover, under the same culture conditions it was possible to develop the branched morphotype from the unbranched one. The general structure of sulfated galactoxyloarabinans biosynthesized by the branched morphotype of this alga were studied previously. In this work, these sulfated 4-linked pyranosic arabinans were studied in relation to morphotype and season. It was shown that differences in structure of the water-soluble polysaccharides between samples could not be related to the morphotype but depend on the season. A detailed study by principal components analysis (PCA) of variables related with the main structural features showed clear differences between sulfated polysaccharides extracted from algae collected in spring, compared to those collected in other seasons. Structural analysis by chemical and spectroscopic methods of these sulfated arabinans collected in the different seasons are reported and discussed.

First report of leaf spot on Elaeagnus pungens caused by Neopestalotiopsis clavispora in China.

First report of leaf spot on Elaeagnus pungens caused by Neopestalotiopsis clavispora in China.

The greening ashore.

More than half a billion years ago a streptophyte algal lineage began terraforming the terrestrial habitat and the Earth's atmosphere. This pioneering step enabled the subsequent evolution of all complex life on land, and the past decade has uncovered that many traits, both morphological and genetic, once thought to be unique to land plants, are conserved across some streptophyte algae. They provided the common ancestor of land plants with a repertoire of genes, of which many were adapted to overcome the new biotic and abiotic challenges. Exploring these molecular adaptations in non-tracheophyte species may help us to better prepare all green life, including our crops, for the challenges precipitated by the climate change of the Anthropocene because the challenges mostly differ by the speed with which they are now being met.

Calcification patterns of Rivularia-type cyanobacteria: examples from the Miocene of the North Alpine Foreland Basin

During the Middle Miocene, an extensive lake district existed along the southern margin of today’s Swabian Alb (Baden–Württemberg). Sediments include a wide range from marls to pure carbonates of lacustrine and palustrine origin that contain microbialites studied here. These sediments are part of the Obere Süßwassermolasse known as Silvana Beds. Macroscopically the studied microbialites show a distinctive layering with an alternation of whitish and tan-colored layers. Petrographic thin sections as well as SEM studies reveal a microstructure of the microbialites comprising an unbranched filament zone formed by erect and parallel calcified filaments as well as a zone of branching filaments forming shrubs of the Dichothrix morphotype. We define two patterns of mineralization for the studied microbialites: (1) shape-retentive mineralization: successive carbonate precipitation along the filament surface. (2) shape-obscuring mineralization: clusters of clotted micritic precipitates along and within the vicinity of micro-sparitic tubules that probably represent remains of the former cyanobacterial sheaths.

A late Paleoproterozoic microfossil community from siliceous granules, Dahongyu Formation, North China

After the first great oxygenation event (GOE), microorganism communities flourished in various habitats in shallow marine settings as a response to elevated oxygen contents in atmosphere and seawater. Abundant microorganisms have been reported from microbialites and siliceous dolomites and siliciclastic rocks. Here we report a diverse microfossil assemblage from siliceous granules within chert grainstones of the ca. 1.6 Ga late Paleoproterozoic Dahongyu Formation in the Jixian section, North China. These microfossils are confined to granules and absent in inter-granular chalcedony interpreted as cementing matrix. The microfossil assemblage is made up of the five morphotypes: two types of large spheroidal forms, much smaller unicells, unbranched filaments of cyanobacterial affinity, and chain-like filaments (CLFs) composed of hematitic pseudomorphs after pyritization. The CLF possesses a carbonaceous sheath structure which is mostly obscured by previous pyrite crystals, suggesting a potential bacterial origin. The unique morphology and distinctive chemical composition both distinguish these filamentous objects from filaments known in the Archean and Proterozoic worldwide. However, similar CLFs have been found in a variety of lithofacies worldwide, and coexist with other microfossils or microbial mats, implying that they all may represent a once-widespread group of microbes. The hosting granules are interpreted as depositional products that were transported from shallow marine into a deeper ramp setting, and the microfossils and mat debris therefore likely represent a phototrophic community. The inferred high minus-cement porosity and the predominantly grain-supporting texture of these granules signal the early silicification and cementation. Thus, chert grainstones formed in this way may effectively preserve traces of early life and provide snapshots of early microorganisms after the GOE.

Occurrence of Neopestalotiopsis clavispora Causing Leaf Spot on Dendrobium officinale in China.

Dendrobium officinale Kimura L., an endangered orchid plant, is a rare and precious Chinese herb and widely used to prepare Chinese traditional medicine (Zheng et al. 2005). In August 2021, significant indications of an unknown leaf spot disease were observed on greenhouse-grown D. officinale in Yueqing of Wenzhou (28.39°N, 121.04°E), Zhejiang Province, China, the main producing location of this orchid plant. Approximately twenty percent of plants surveyed showed typical infection symptoms. Initially, the symptoms appeared as small, circular black spots. As the disease developed, the center of the lesions was sunken with a black border. To determine the causal agent, 10 symptomatic plant samples were collected and all pieces from symptomatic plant leaves were used for isolating pathogen. Tissues between healthy and necrotic area were cut into pieces (5 × 5 mm, n=10), disinfected with 10% sodium hypochlorite for 1 minute, rinsed 3 times with sterile water, and dried on sterile tissue. Samples were then placed on potato dextrose agar medium (PDA) for 1 piece per plate, and incubated at 25℃ in a dark biochemical incubator. After 3 days, hyphal tips growing from the disinfected tissues were individually transferred to new PDA plates and incubated at 25℃ in the dark. Twelve same fungal isolates were obtained from all symptomatic leave fragments, then DDO11 was chosen as a representative isolate for further study. The colonies showed white aerial mycelium after 5 days culture at 25°C on PDA. Black viscous acervuli appeared and scattered on the surface of the colony after 8-12 days culture. Conidia were spindle shape, five cells, four septa, average 29.3 × 8.5 μm (n = 30; length × width). The apical and basal cells were lighter in color, and most of them were hyaline. The middle three cells were darker in color, and mostly brown. There are 2 to 4 colorless and transparent unbranched accessory filaments at the top, 32.5 µm in average length, and the basal cell has a small appendage, 9.2 µm in average length, n=30. For fungal identification to species level, Internal transcribed spacer (ITS) region, β-tubulin gene (TUB2) and translation elongation factor-1α (TEF-1α) were amplified (Qiu et al. 2020), respectively. The ITS, TUB2 and TEF-1α gene sequences of the representative isolate DDO11 were deposited in NCBI GenBank nucleotide database with accession numbers OK631881, OK655895 and OK655896, respectively. BLASTn analysis respectively showed 100%, 100% and 99.6% nucleotide sequence identity with Neopestalotiopsis clavispora strain accessions MG729690, MG740736 and MH423940, which indicated that the pathogen belonged N. clavispora. A maximum-likelihood phylogenetic analysis based on multi-locus sequence (ITS, TUB2, and TEF-1α) using MEGA X showed the similar result (Kumar et al. 2018). To verify pathogenicity, thirty 1-year-old healthy D. officinale plants of cultivar Yandang1 were used for inoculation tests. Spores of N. clavispora DDO11 were produced on PDA for 7 days at 28°C and washed with sterile distilled water, and the concentrations were adjusted to 1 × 106 spores/ml using a hemocytometer. Fifteen surface disinfected healthy plants were inoculated by spraying the suspension (2 ml, 1 × 106 spores/ml) and covered with plastic bags for 24 h, and another 15 plants treated with sterile distilled water were used as control. The plants were placed in a humidified chamber (>95% relative humidity) at 25°C for 48 h after inoculation and kept in a growth chamber (Kiangnan, China) at 25°C with 12-h day/night cycle for 8 days (Cao et al. 2019). All inoculated leaves showed symptoms identical to those observed in the field. No disease occurred on the controls. The Neopestalotiopsis isolate was reisolated from the symptomatic leaves, and species identification was confirmed by the morphological and molecular method described above. N. clavispora has been reported to cause diseases on a variety of plants all over the world, such as strawberry (Gilardi et al. 2019), blue berry (Shi et al. 2021), Syzygium cumini (Banerjee et al. 2020), Macadamia (Qiu et al. 2020), and so on. To the best of our knowledge, this is the first report of N. clavispora causing leaf spot on D. officinale in China. This report will help us to recognize the leaf spot disease of D. officinale and establish a foundation for future studies on N. clavispora to address effective management strategies.

First Report of Neopestalotiopsis clavispora Causing Calyx and Receptacle Blight on Strawberry in China.

Strawberry (Fragaria × ananassa) is widely cultivated in Liaoning Province, the most important strawberry production area in China. In November 2020, extensive brown spotting on the calyces and receptacles and dark brown necrotic lesions on the leaves of 'YanLi' strawberry plants were observed in the greenhouse, College of Horticulture, in Shenyang Agriculture University of Liaoning Province, China. The incidence ranged from 15% to 20% in the greenhouse. As the disease progressed, the spots extended to cover the entire receptacles and entire leaves. Fresh samples (5 mm2) were cut from the margin of healthy and infected tissues. The isolation and purification of methods were as described previously (Obregón et al. 2018). Fungal isolations are suborbicular with irregular edges. The colonies showed white aerial mycelium at the early stage and formed concentric circles after 5 days culture at 28°C on PDA. Black viscous acervuli appeared and scattered on the surface of the colony after 7~10 days culture. Acervulus was 162.4 µm in average diameter, n= 30. Conidia were spindle shape, five cells, four septa, 7.0 µm (average width) and 24.0 µm (average length), n=30. The apical and basal cells are lighter in color, most of them are hyaline, the middle three cells are darker in color, mostly brown. There are 2 to 4 colorless and transparent unbranched accessory filaments at the top, 30.8 µm in average length, and the basal cell has a small appendage, 9.0 µm in average length, n=30 (Fig. 1c-g). For fungal identification to species level, genomic DNA was extracted by the 2% CTAB method. Internal transcribed spacer (ITS) region, β-tubulin gene (TUB2) and translation elongation factor-1α (TEF-1α) were amplified (Qiu et al. 2020), respectively. Purified PCR products were sequenced in single direction. BLASTn searches of GenBank, using the partial ITS (MW861730), β-tubulin (MW856302) and TEF-1α (MW861729) sequences of representative isolate NP102 as the queries, revealed 97%, 100% and 100% sequence identity, respectively, to Neopestalotiopsis clavispora strain WJ31 accessions MG729690, MG740736 and MG740759. The phylogenetic tree was constructed by MEGA X (Fig. 2) (Kumar et al. 2018). Pathogenicity assay was carried out by spraying a spore suspension (1 × 106 spores/ml) of 8-day-old culture of fungus on six healthy 'YanLi' strawberry plants. An additional six control plants were only sprayed with sterile distilled water, and the inoculated plants were maintained in a light incubator at 25 ± 1°C, 90% relative humidity, with a photoperiod of 12 h. Calyx and receptacle blight and leaf spot symptoms resembled those observed in the greenhouse on all inoculated tissues after 10 days (Fig. 1h and i), whereas calyces, receptacles and leaves on control plants remained asymptomatic. The experiment was repeated twice. Neopestalotiopsis clavispora was successfully reisolated from the infected tissues, fulfilling Koch's postulates. Researchers in Spain (Chamorro et al. 2016) reported N. clavispora for the first time on strawberry. After two years, N. clavispora was found in Argentina (Obregón et al. 2018). The reports characterized it mainly as a root rot pathogen. In January 2021, Neopestalotiopsis spp. were reported that it is a pathogen of strawberry leaves and fruits in Florida strawberry fields (Juliana et al. 2021). Our studies indicated that isolate NP102 was more aggressive. In the warm and humid greenhouse, the disease struck suddenly at the early stages of strawberry fruiting. Unlike previous reports, symptoms were a calyx and receptacle blight as well as a leaf spot. This pathogen can cause serious economic losses to strawberry growers. To the best of our knowledge, this is the first report of calyx and receptacle blight by N. clavispora on strawberry in China.

Revisiting the systematics of the genera Grateloupia, Phyllymenia, and Prionitis (Halymeniaceae, Rhodophyta) with a description of a new species-Prionitis taiwani-borealis.

The taxonomy of the genera Grateloupia, Phyllymenia, and Prionitis has been revised several times but remains controversial. The anatomy of female reproductive structures in combination with phylogenetic reconstructions is mostly used to define the genera. However, the architecture and behavior of the auxiliary cell ampullae before and after diploidization are not well documented for most species. To fill this knowledge gap, we examined the female reproductive structures of a new species (Prionitis taiwani-borealis sp. nov.) from Taiwan and compared our observations to the species currently placed in the Phyllymenia/Prionitis complex. The female reproductive structures of the Phyllymenia/Prionitis complex are characterized by (1) 2-celled carpogonial branches with the supporting cell being the basal cell of a third-order ampullar filament; (2) auxiliary cell ampullae composed of three orders of unbranched ampullar filaments before diploidization; (3) cells of auxiliary cell ampullar filaments forming a cellular cluster after diploidization and surrounding the developing gonimoblasts; (4) gonimoblast initials produced from the diploidized auxiliary cells before fusing with them; and (5) branched auxiliary cell ampullar and secondary medullary filaments involved in early pericarp formation. A monophyletic relationship of species possessing female structures similar to those of Pr. taiwani-borealis and related species was highly supported based on combined rbcL and LSU rDNA sequence analyses. The female reproductive structures of other species of Grateloupia sensu lato, phylogenetically closely related to the Prionitis and Phyllymenia assemblage, require reinvestigation as correct interpretations of pre- and post-fertilization events have proven to be informative for resolving the systematics of the Halymeniaceae.

Controlling the Spatial Dimensions of Nanostructured Electrolytes to Stabilize Dendritic Electrodeposition of Silver

The tendency of metals to form uncontrolled dendritic morphologies during electrodeposition hinders the development of safe and reliable metal batteries. Multiphase nanostructured electrolytes can suppress dendritic growth if the mechanical modulus of the electrolyte is high relative to that of the metal or if the conducting channels are confined to nanoscale dimensions. Direct visualization and analysis of electrodeposition within polymeric nanostructures elucidates the structure−property relationships and mechanisms underlying the suppression of dendrite growth. To overcome these challenges, we introduce here a generalizable platform by which we can directly characterize electrodeposited metal morphologies in well-defined, multiphase nanostructured electrolytes by top-down SEM imaging [1]. This approach requires no destructive sample preparation techniques between electrodeposition and imaging. The platform consists of coplanar electrodes coated by polymeric structures consisting of alternating ion conducting and nonconducting material which are precisely created by lithography and etch techniques. These fabricated polymeric structures are designed to carefully model deposition of metals in nanostructured polymeric separators and electrolytes.In this study we track the electrodeposition of silver ions (Ag+) dissolved in dry, aprotic poly(ethylene oxide) (PEO) polymer electrolyte confined within channels that are defined by a microfabricated nonconductive polystyrene structures. We find that Ag metal electrodeposition occurs only in the conductive domains with no significant deformation of the adjacent low-modulus nonconductive and confining domains. Moreover, we have shown that the Ag metal deposit morphology was strongly dependent on the dimensions of the conducting domains. When confinement width was similar in scale to the critical length scale for unstable deposition, the metal morphology was dense, unbranched filaments. Gradually increasing the confinement width led to branched dendritic deposition, although the side branch feature size was limited by the size of the confinement. These results demonstrate that in addition to mechanical and transport properties, the nanodimension of the structured electrolyte can also serve to stabilize dendritic morphology growth. This work highlights critical parameters for design of structured battery components such as solid-electrolytes, separators, and current collectors.[1] Sharon, D.; Bennington, P.; Patel, S.N.; Nealey, P.F.*, “Stabilizing Metal Electrodeposition by Limiting Spatial Dimensions in Nanostructured Electrolytes,” ACS Energy Lett. 2020, 5, 2889−2896. Figure 1

Cladophora rigida sp. nov., a new freshwater species within Cladophoraceae (Ulvophyceae, Chlorophyta) from China

ABSTRACT Cladophora is one of the most species-rich and taxonomically challenging taxa of green algae. Recently, some samples of freshwater filamentous algae were collected from Hubei, Yunnan and Guizhou Provinces, China. The specimens grew attached to solid substrates by basal rhizoids or holdfasts, and their thalli were bright to dark green, long and stiff. They were typically composed of uniseriate unbranched filaments of approximately equal length produced by intercalary and apical cell divisions. We studied the taxonomy of these algae based on morphological and molecular data. Microscopic observations showed that the filaments had some characteristics that differed from those of other species of Cladophora, such as being unbranched, with a large cell diameter (180–429 µm) and smaller length:diameter (L:D) ratio (0.5–3.3) than other species. Phylogenetic trees constructed on the basis of small (SSU) and large (LSU) subunits of ribosomal DNA (rDNA) and the internal transcribed spacer (ITS) sequences showed that all collected specimens belonged to one species. These specimens formed a new clade in the freshwater Cladophora lineage. On the basis of the morphological and phylogenetic analyses, we propose a new species, Cladophora rigida sp. nov.

Interdependence of Filament Nucleation, Elongation and Crosslinking in Actin Bundle Assembly

A network of actin-binding proteins tightly regulates each stage of actin assembly, including filament nucleation, elongation and crosslinking. These processes are integrated together to assemble higher-order actin structures specialized for specific cellular roles. Actin bundles are composed of unbranched filaments that are crosslinked in parallel or anti-parallel orientations by bundling proteins. These structures form the basis of a number of cytoskeletal assemblies, including the contractile ring, stress fibers, and filopodia. Aberrant regulation of actin bundles and their associated proteins is linked to diseases such as focal segmental glomerulosclerosis and metastatic cancers. Yet despite their importance, the dynamic properties of actin bundles are not well understood. To gain insight into the mechanism of bundle assembly, we investigated how the processes of nucleation, elongation, and crosslinking influence each other. We utilized formins, which function as both nucleators and actin polymerases, to elucidate the interdependence between nucleation and elongation. We found that, whereas filament nucleation necessarily precedes and promotes filament elongation, the dependence of both processes on actin monomer availability gives rise to competition that ultimately favors nucleation over elongation. To investigate the relationship between elongation and crosslinking, we generated pools of actin filaments of uniform lengths and analyzed their kinetics of crosslinking by the bundling protein fascin. We found that fascin crosslinks short filaments more slowly than long filaments, suggesting that filament elongation plays a role in regulating filament bundling. We propose that elongating filaments undergo changes in curvature and rotational diffusion that modulate the probability of filament alignment and ultimately dictate the efficiency of fascin-mediated crosslinking. This work suggests that upregulation of fascin might alter the mechanical properties of bundled actin structures by promoting the incorporation of short filaments.

Untangling filamentous marine cyanobacterial diversity from the coast of South Florida with the description of Vermifilaceae fam. nov. and three new genera: Leptochromothrix gen. nov., Ophiophycus gen. nov., and Vermifilum gen. nov.

Benthic cyanobacterial mats are an integral component of aquatic communities in tropical marine waters. These mats can develop into massive nuisances at risk of expansion due to climate change. The extent of diversity occurring within these mats, still remains largely unexplored, especially in Florida. To reveal this diversity, coastal environments of South Florida were sampled and subsequently processed for isolation and systematic identification. Three new genera are proposed based on the molecular phylogeny, morphology, and ecology. These new genera are characterized by discoid cells and homocytous, unbranched filaments without sheaths. Individual genus morphological differences include either rounded bent, rounded, or conical rounded apical cells. A unique molecular fingerprint including a base pair insert within the 16S rRNA gene sequence and genetic similarities facilitates the delimitation of a novel family Vermifilaceae. Using the polyphasic approach, our research presents three new genera and four new species of marine cyanobacteria inhabiting coastal ecosystems of South Florida.

Systematics and Biogeography of the Red Algal Genus Yonagunia (Halymeniaceae, Rhodophyta) from the Indo-Pacific Including the Description of Two New Species from Taiwan.

Carpopeltis maillardii has been regarded as a widely distributed species in the Indo-Pacific region. In this study, we analyzed the genetic diversity of C. maillardii and related species collected from Taiwan and the Indian Ocean based on rbcL sequences, in order to elucidate species boundaries, diversity, and biogeographic patterns. Our analyses show that C. maillardii specimens are only distantly related to the genus Carpopeltis (type: C. phyllophora) but instead form a clade together with species of Yonagunia. We therefore propose the new combination Yonagunia maillardii comb. nov. In addition, two new species (Yonagunia palmata sp. nov. and Yonagunia taiwani-borealis sp. nov.) are described from Taiwan. The close relationship of Yonagunia to Grateloupia is corroborated by detailed observations of the female reproductive structures, which demonstrate that the development of auxiliary cell ampullae before and after diploidization is similar to that of Grateloupia sensu stricto. Namely, the ampullae are composed of only two orders of unbranched filaments in which only a few ampullar cells are incorporated into a basal fusion cell after diploidization of the auxiliary cell and the pericarp consists almost entirely of secondary medullary filaments. Of all Yonagunia species, Y. maillardii has the widest distribution in the Indo-Pacific, and can be identified in the field by its relatively thin, feathery, and highly branched morphology. Most other species, including those that occur in Taiwan, are seemingly more range-restricted. Our phylogenetic analyses resulted in a well-resolved phylogeny of Yonagunia, with an origin estimated in the Eocene-Oligocene, and diversification of species mainly in the Miocene.

SPIN90 associates with mDia1 and the Arp2/3 complex to regulate cortical actin organization.

Cell shape is controlled by the submembranous cortex, an actomyosin network mainly generated by two actin nucleators: the Arp2/3 complex and the formin mDia1. Changes in relative nucleator activity may alter cortical organization, mechanics and cell shape. Here we investigate how nucleation-promoting factors mediate interactions between nucleators. In vitro, the nucleation-promoting factor SPIN90 promotes formation of unbranched filaments by Arp2/3, a process thought to provide the initial filament for generation of dendritic networks. Paradoxically, in cells, SPIN90 appears to favour a formin-dominated cortex. Our in vitro experiments reveal that this feature stems mainly from two mechanisms: efficient recruitment of mDia1 to SPIN90-Arp2/3 nucleated filaments and formation of a ternary SPIN90-Arp2/3-mDia1 complex that greatly enhances filament nucleation. Both mechanisms yield rapidly elongating filaments with mDia1 at their barbed ends and SPIN90-Arp2/3 at their pointed ends. Thus, in networks, SPIN90 lowers branching densities and increases the proportion of long filaments elongated by mDia1.

Microstructural and carbohydrate compositional changes induced by enzymatic saccharification of green seaweed from West Africa

The use of marine macroalgae as carbon source for fermentation is gaining increasing attention due to their high carbohydrate content and availability. Three green seaweed species Chaetomorpha linum, Ulva fasciata and Caulerpa taxifolia were investigated for their amenability to enzymatic saccharification. Microstructural changes were studied in order to understand the physical changes occurring in the seaweeds during saccarification and to identify structural barriers. C. linum had highest glucan content (20%), compared to 16% in U. fasciata and 6% in C. taxifolia indicating large differences in composition. Glucose yields obtained after 24 h of enzymatic saccharification were 59, 38 and 60% for C. taxifolia, U. fasciata and C. linum, respectively, based on the glucan content. Pre-autoclaving increased the saccharification yield to 81, 99 and 71%, respectively. Morphologically, C. linum displayed unbranched filaments, U. fasciata two-cell layer large sheets and C. taxifolia featured leaf like structures. Enzymatic saccharification resulted in cell wall degradation and release of the chlorophyll content in C. linum, delamination of sheets in U. fasciata and surface erosion of leaves in C. taxifolia. C. taxifolia deviated in being very rich in β-1,3 linked xylan (46%), which was only hydrolysed at 1% xylose yield due to lack of β-1,3-xylanase. Based on the high cellulose content and no need for pre-treatment C. linum was the best source of glucose among the three types of green seaweed species. Further studies are warranted to assess fermentation. We also conclude that for C. taxifolia enzymatic saccharification with β-1,3-xylanase might enable further xylose release than obtained here with the enzymatic cellulase treatment.

Morphological identification, isolation, and culturing of cyanobacteria derived from hot spring of Cisolok and Galunggung Mountain based on enrichment method

Research on isolating and culturing of cyanobacteria from hot springs of Cisolok and Galunggung Mountain in West Java Indonesia had been done. This research was a study to find a fast and accurate method to identify, isolate and culture the cyanobacteria originating from extreme region, especially from the hot springs. Identification based on morphological characters performed in line with the process of isolation of the founded cyanobacteria strains. In the process of isolation, enrichment methods carried out in stages to determine the viability of each strain to be easily cultured (culturable). Four (4) types of media used in this study, i.e. BBM, BG-11, CT and MA. Pipette method was used to create a single culture. At the initial observations of the fresh samples, 3 types of cyanobacteria thallus were found, i.e. the form of thread/filament (unbranched filament), branched filament, and rounded shapes (coccoid). Furthermore, from all the enrichment samples (stage-1 and stage-2), 12 genera of cyanobacteria were found, i.e. Leptolyngbya, Gloeocapsa, Chroococcus, Oscillatoria, Synechococcus, Fischerella, Scytonema, Hapalosiphon, Microcystis, Nostoc, Gloeotrichia, and Stanieria. In the first stage of enrichment culture samples of Cisolok, eight (8) genera were found, i.e. Leptolyngbya, Chroococcus, Oscillatoria, Synechococcus, Scytonema, Hapalosiphon, Nostoc, and Gloeotrichia, while in the hot spring of Galunggung mountain, only four (4) genera were found (Leptolyngbya, Oscillatoria, Hapalosiphon, and Nostoc). There were several filaments and coccoid cyanobacteria that could not be identified by morphological characters. Meanwhile, in the second stage of enrichment culture samples of Cisolok, nine (9) genera were found, i.e. six (6) genera similar to those found in the first stage of enrichment (Leptolyngbya, Chroococcus, Oscillatoria, Synechococcus, Scytonema, Hapalosiphon), and added with the genus of Gloeocapsa, Microcystis, and Stanieria. From the hot spring of Mt Galunggung, nine (9) genera were found, i.e. four (4) genera similar to those found in the first stage of enrichment (Leptolyngbya, Oscillatoria, Hapalosiphon, and Nostoc), and added with the genus of Chroococcus, Gloeocapsa, Microcystis, Synechococcus, and Fischerella. Both from Cisolok and from Galunggung, the three genera (Leptolyngbya, Oscillatoria, Hapalosiphon) could be found in fresh samples and enrichment samples (stage-1 and stage-2). The research concluded that the enrichment process in stages (first and second) can be used for the isolation of strains of cyanobacteria to be adaptable, and therefore easy to be cultured (culturable). The genus Scytonema and Gloeotrichia are genera that known to be difficult to be cultured, and in this study, they grow only in stage-1, while the genus Stanieria appears in stage-2. Isolates obtained consist of 31 strains from Cisolok hot spring, and 13 strains from Galunggung mountain hot spring, then would be identified (re-identification) using molecular characters (16S rDNA).