Host Surface Research Articles

Surface Mounted Active Vibration Cancellation Device Using Raspberry Pi

Active vibration cancellation device detects vibrations on a host surface using a piezoelectric vibration sensor, amplifies them using a signal amplifier, and sends them to a Raspberry Pi board implemented with PID control, responsible for signal processing, which further actuates Piezoelectric actuators vibrating at a phase difference of 180° to the vibrating surface (destructive interference) and reduces the vibrations over the surface. The device presented in this paper suggests an application that tries to make it accessible to a large group of people.

Antibiotic Activity Altered by Competitive Interactions Between Two Coral Reef-Associated Bacteria.

Microbes produce natural products that mediate interactions with each other and with their environments, representing a potential source of antibiotics for human use. The biosynthesis of some antibiotics whose constitutive production otherwise remains low has been shown to be induced by competing microbes. Competition among macroorganism hosts may further influence the metabolic outputs of members of their microbiomes, especially near host surfaces where hosts and microbial symbionts come into close contact. At multiple field sites in Fiji, we collected matched samples of corals and algae that were freestanding or in physical contact with each other, cultivated bacteria from their surfaces, and explored growth-inhibitory activities of these bacteria against marine and human pathogens. In the course of the investigation, an interaction was discovered between two coral-associated actinomycetes in which an Agrococcus sp. interfered with the antibiotic output of a Streptomyces sp. Several diketopiperazines identified from the antibiotic-producing bacterium could not, on their own, account for the antibiotic activity indicating that other, as yet unidentified molecule(s) or molecular blends, possibly including diketopiperazines, are likely involved. This observation highlights the complex molecular dynamics at play among microbiome constituents. The mechanisms through which microbial interactions impact the biological activities of specialized metabolites deserve further attention considering the ecological and commercial importance of bacterial natural products.

Insight into the Taxonomic Resolution of the Pleosporalean Species Associated with Dead Woody Litter in Natural Forests from Yunnan, China.

In the course of investigating the systematics of woody litter micromycete associates in Yunnan Province, China, we found one new species in Phaeoseptaceae, one new genus and three new species in Sulcatisporaceae from 16 specimens collected (ten collections of ascomycetous teleomorphs, four collections of hyphomycetous and two collections of coelomycetes anamorphs) from Ailaoshan, Chuxiong, Diqing, Honghe, Kunming, Lancang, Mengla and Yuxi in Yunnan Province. These taxonomic novelties were recognized with the aid of morphological comparisons and phylogenetic analyses of multiple gene sequences (non-translated loci and protein-coding regions). Pleopunctum menglaense sp. nov. is accommodated in Phaeoseptaceae (Pleosporales) based on its hyphomycetous anamorph, which is characterized by superficial sporodochia on the host surface, macronematous, mononematous, cylindrical, unbranched, aseptate, hyaline and smooth-walled conidiophores, monoblastic, terminal, hyaline conidiogenous cells, hyaline, muriform α conidia, and brown, muriform β conidia with tri-lobed wing like basal cells. Kazuakitanaka gen. nov. (type: K. yuxiensis) is introduced in Sulcatisporaceae (Massarineae, Pleosporales) for a saprobic ascomycete with teleomorphic and anamorphic (coelomycetous) features. The teleomorph possesses globose to subglobose ascomata with acentric ostiole, a peridial wall of textura angularis to textura prismatica, cylindric-clavate, pedicellate asci with an ocular chamber, and 1–2-septate, hyaline, fusiform, guttulate ascospores with a distinct mucilaginous sheath. The anamorph features pycnidial conidiomata, phialidic, ampulliform to cylindrical, hyaline conidiogenous cells and ampulliform to cylindrical, one-to-three-septate, hyaline, guttulate conidia. Loculosulcatispora was known only from its anamorph of L. thailandica. We observed the teleomorph of Loculosulcatispora hongheensis sp. nov. and amended the generic description of Loculosulcatispora accordingly. Loculosulcatispora hongheensis is characterized by globose to subglobose ascomata with a central ostiole, a peridial wall of textura angularis to globosa, branched, septate, pseudoparaphyses, clavate asci with a short pedicel and a minute ocular chamber and hyaline, fusiform, 1-septate ascospores with a thick irregular mucilaginous sheath. This study provides some insights into the diversity of fungi on dead woody litter in terrestrial habitats.

3,4-Dicaffeoylquinic Acid from the Medicinal Plant Ilex kaushue Disrupts the Interaction Between the Five-Fold Axis of Enterovirus A-71 and the Heparan Sulfate Receptor

While infections by enterovirus A71 (EV-A71) are generally self-limiting, they can occasionally lead to serious neurological complications and death. No licensed therapies against EV-A71 currently exist. Using anti-virus-induced cytopathic effect assays, 3,4-dicaffeoylquinic acid (3,4-DCQA) from Ilex kaushue extracts was found to exert significant anti-EV-A71 activity, with a broad inhibitory spectrum against different EV-A71 genotypes. Time-of-drug-addition assays revealed that 3,4-DCQA affects the initial phase (entry step) of EV-A71 infection by directly targeting viral particles and disrupting viral attachment to host cells. Using resistant virus selection experiments, we found that 3,4-DCQA targets the glutamic acid residue at position 98 (E98) and the proline residue at position 246 (P246) in the 5-fold axis located within the VP1 structural protein. Recombinant viruses harboring the two mutations were resistant to 3,4-DCQA-elicited inhibition of virus attachment and penetration into human rhabdomyosarcoma (RD) cells. Finally, we showed that 3,4-DCQA specifically inhibited the attachment of EV-A71 to the host receptor heparan sulfate (HS), but not to the scavenger receptor class B member 2 (SCARB2) and P-selectin glycoprotein ligand-1 (PSGL1). Molecular docking analysis confirmed that 3,4-DCQA targets the 5-fold axis to form a stable structure with the E98 and P246 residues through noncovalent and van der Waals interactions. The targeting of E98 and P246 by 3,4-DCQA was found to be specific; accordingly, HS binding of viruses carrying the K242A or K244A mutations in the 5-fold axis was successfully inhibited by 3,4-DCQA.The clinical utility of 3,4-DCQA in the prevention or treatment of EV-A71 infections warrants further scrutiny. IMPORTANCE The canyon region and the 5-fold axis of the EV-A71 viral particle located within the VP1 protein mediate the interaction of the virus with host surface receptors. The three most extensively investigated cellular receptors for EV-A71 include SCARB2, PSGL1, and cell surface heparan sulfate. In the current study, a RD cell-based anti-cytopathic effect assay was used to investigate the potential broad spectrum inhibitory activity of 3,4-DCQA against different EV-A71 strains. Mechanistically, we demonstrate that 3,4-DCQA disrupts the interaction between the 5-fold axis of EV-A71 and its heparan sulfate receptor; however, no effect was seen on the SCARB2 or PSGL1 receptors. Taken together, our findings show that this natural product may pave the way to novel anti-EV-A71 therapeutic strategies.

Effects of host state and body condition on parasite infestation of bent-wing bats

BackgroundEctoparasites inhabit the body surface or outgrowths of hosts and are usually detrimental to host health and wellbeing. Hosts, however, vary in quality and may lead ectoparasites to aggregate on preferred hosts, resulting in a heterogeneous distribution of parasite load among hosts.ResultsWe set out to examine the effects of host individual state and body condition on the parasite load of multiple nycteribiid and streblid bat flies and Spinturnix wing mites on eastern bent-wing bats Miniopterus fuliginosus in a tropical forest in southern Taiwan. We detected a high parasite prevalence of 98.9% among the sampled bats, with nearly 75% of the bats harboring three or more species of parasites. The parasite abundance was higher in the wet season from mid spring to early fall, coinciding with the breeding period of female bats, than in the dry winter season. In both seasonal periods, the overall parasite abundance of adult females was higher than that of adult males. Among the bats, reproductive females, particularly lactating females, exhibited a higher body condition and were generally most infested. The Penicillidia jenynsii and Nycteribia parvula bat flies showed a consistent female-biased infection pattern. The N. allotopa and Ascodipteron speiserianum flies, however, showed a tendency towards bats of a moderate to higher body condition, particularly reproductive females and adult males.ConclusionsWe found an overall positive correlation between parasite abundance and reproductive state and body condition of the host and female-biased parasitism for M. fuliginosus bats. However, the effects of body condition and female-biased infestation appear to be parasite species specific, and suggest that the mobility, life history, and potential inter-species interactions of the parasites may all play important roles.

In Silico Designed Gain-of-Function Variants of Complement C2 Support Cytocidal Activity of Anticancer Monoclonal Antibodies.

Simple SummaryThe complement system can be exploited by anticancer antibody-based therapeutics. Activation of the classical complement pathway by the heavy chain of antibodies eventually leads to the lysis of target cells. However, overexpression of complement inhibitors by tumor cells limits the therapeutic efficacy. We designed and produced recombinant gain-of-function variants of complement C2 protein that counteract the activity of complement inhibitors. The dominant character of designed mutations in C2 allows supplementation of human serum with recombinant proteins for enhancing the cytocidal activity of complement-activating antibodies. In vitro functional assays demonstrate that this strategy is compatible with several clinically approved antibodies.The molecular target for the classical complement pathway (CP) is defined by surface-bound immunoglobulins. Therefore, numerous anticancer monoclonal antibodies (mAbs) exploit the CP as their effector mechanism. Conversely, the alternative complement pathway (AP) is spontaneously induced on the host and microbial surfaces, but complement inhibitors on host cells prevent its downstream processing. Gain-of-function (GoF) mutations in the AP components that oppose physiological regulation directly predispose carriers to autoimmune/inflammatory diseases. Based on the homology between AP and CP components, we modified the CP component C2 so that it emulates the known pathogenic mutations in the AP component, factor B. By using tumor cell lines and patient-derived leukemic cells along with a set of clinically approved immunotherapeutics, we showed that the supplementation of serum with recombinant GoF C2 variants not only enhances the cytocidal effect of type I anti-CD20 mAbs rituximab and ofatumumab, but also lowers the threshold of mAbs necessary for the efficient lysis of tumor cells and efficiently exploits the leftovers of the drug accumulated in patients’ sera after the previous infusion. Moreover, we demonstrate that GoF C2 acts in concert with other therapeutic mAbs, such as type II anti-CD20, anti-CD22, and anti-CD38 specimens, for overcoming cancer cells resistance to complement attack.

Temperature-dependent infrared dielectric functions and hybrid phonon-polaritons in wurtzite GaN: A spectroscopic ellipsometry and multiscale simulation study

Polar wurtzite GaN can host surface phonon-polaritons (SPHPs) along its bulk surface and achieve sub-diffraction confinement with an ultralow optical loss and has emerged as a relevant technological material for infrared nanophotonics. Yet, few studies have reported on the temperature-dependent infrared dielectric functions, lattice vibration's influence on the hybrid phonon-polaritons, and the underlying physics that are largely unexplored. Herein, we perform the infrared spectroscopic ellipsometry (SE) measurements and multiscale simulations including first-principles and finite-difference time-domain (FDTD) to systematically study the infrared dielectric function at varying temperatures, phonon dynamics, and SPHPs in wurtzite GaN. SE experiments identify the reststrahlen band where the amplitude of ordinary dielectric function reduces significantly by a factor of 3.5 and the propagation length of SPHPs decreases by a factor of 4.18 as temperature increases from 250 to 800 K, suggesting the strong influence of lattice vibration on SPHPs. First-principles calculations confirm that the reststrahlen band for the ordinary dielectric function lies between the transverse and longitudinal E1 phonon modes, while that of extraordinary dielectric function lies between the transverse and longitudinal A1 phonon modes. FDTD simulations observe the localized surface phonon resonances in the nano-porous GaN thin films deposited on the sapphire substrate only for the transverse magnetic wave mode, which is consistent with the observation of extra dip in the measured pp-polarized reflection spectroscopy. This work provides a deep insight into lattice vibration influence on phonon dynamics and SPHPs in wurtzite GaN and helps engineer them in nanophotonic devices toward achieving better performance.

Transcriptional Network in Colletotrichum gloeosporioides Mutants Lacking Msb2 or Msb2 and Sho1.

Colletotrichum gloeosporioides is a hemibiotrophic ascomycetous fungus that causes anthracnose in many plants worldwide. During infections, C. gloeosporioides produces an appressorium in response to various plant surface signals. However, the mechanism mediating host surface signal recognition remains unclear. In this study, C. gloeosporioides ΔCgMsb2 and ΔCgMsb2Sho1 mutants lacking hypothetical sensors of plant surface signals were examined. The mutations in ΔCgMsb2 and ΔCgMsb2Sho1 adversely affected conidial size and sporulation, while also inhibiting growth. Significant transcriptional changes were detected for nearly 19% and 26% of the genes in ΔCgMsb2 and ΔCgMsb2Sho1, respectively. The lack of these plasma membrane receptors altered the expression of specific genes, especially those encoding hydrolases, ABC transporters, and mitogen-activated protein kinases (MAPKs). The encoded MAPKs participate in the signal transduction of ERK and JNK signaling pathways, activate downstream signals, and contribute to metabolic regulation. Our data demonstrate that the C. gloeosporioides membrane proteins Msb2 and Sho1 affect gene regulation, thereby influencing conidial growth, metabolism, and development. These findings provide new insights into the regulation of C. gloeosporioides’s development and infection of plant hosts.

Variations in host surfaces morphology and biology of ciliate epibionts explaining distribution pattern of epibionts in the invasive signal crayfish Pacifastacus leniusculus (Dana, 1852)

AbstractThe present paper reports the distribution of Epistylididae (Sessilida) epibiotic ciliates on the signal crayfish Pacifastacus leniusculus in relation to specialized structures of the host's exoskeleton for the first time. This species is known to maintain a relatively clean carapace, but it is sometimes overgrown by other organisms. Epibionts cover different parts of the signal crayfish body, mainly antennae, antennules, maxillipedes III and pereiopods with inner edges of chelae; however, some parts of the signal crayfish are not fouled. e.g. dorsal surfaces of the carapace and dorsal surfaces of chelae. Using scanning electron microscopy (SEM), topographies of different parts of the crayfish's exoskeleton were examined. Our investigations revealed that the epibiosis in the signal crayfish was determined by morphology of body surfaces. No epibionts were found on smooth surfaces with regular single setae (a known design that prevents fouling in aquatic environments). The dimpled surfaces with regular single micro‐papillae may be considered as a newly described example of self‐cleaning surfaces. Bio‐inspired surface patterning presents promising approaches to the design of novel functional surfaces that can prevent biofouling. The new self‐cleaning design may be used in further technological applications.

Supramolecular Nanohelix Fabricated by Pillararene-Based Host–Guest System for Chirality Amplification, Transfer, and Circularly Polarized Luminescence in Water

Supramolecular Nanohelix Fabricated by Pillararene-Based Host–Guest System for Chirality Amplification, Transfer, and Circularly Polarized Luminescence in Water

Characterization of Defined Pt Particles Prepared by Ultrasonic Spray Pyrolysis for One-Step Synthesis of Supported ORR Composite Catalysts

Polygonal Pt nanoparticles were synthesized using ultrasonic spray pyrolysis (USP) at different precursor concentrations. Physicochemical analysis of the synthesized Pt particles involved thermogravimetric, microscopic, electron diffractive, and light absorptive/refractive characteristics. Electrochemical properties and activity in the oxygen reduction reaction (ORR) of the prepared material were compared to commercial Pt black. Registered electrochemical behavior is correlated to the structural properties of synthesized powders by impedance characteristics in ORR. The reported results confirmed that Pt nanoparticles of a characteristic and uniform size and shape, suitable for incorporation on the surfaces of interactive hosts as catalyst supports, were synthesized. It is found that USP-synthesized Pt involves larger particles than Pt black, with the size being slightly dependent on precursor concentration. Among ORR-active planes, the least active (111) structurally defined the synthesized particles. These two morphological and structural characteristics caused the USP-Pt to be made of lower Pt-intrinsic capacitive and redox currents, as well as of lower ORR activity. Although being of lower activity, USP-Pt is less sensitive to the rate of ORR current perturbations at higher overpotentials. This issue is assigned to less-compact catalyst layers and uniform particle size distribution, and consequently, of activity throughout the catalyst layer with respect to Pt black. These features are considered to positively affect catalyst stability and thus promote USP synthesis for improved properties of host-supported Pt catalysts.

Microbial Profile and Clinical Outcomes of Fungal Keratitis at a Single-Center Tertiary Care Hospital.

PurposeTo evaluate baseline characteristics, microbiological spectrum, management, and outcomes of patients with culture-proven fungal keratitis.MethodsRetrospective review of all patients with culture-proven fungal keratitis seen over 6 years at a tertiary referral center.ResultsThe present study included 62 eyes from 62 patients. Infection with filamentous organisms was more common than with yeast (66.1% vs 27.4%). The most common filamentous organisms were Fusarium (17.7%) and Aspergillus (16.1%), while the most common yeast was Candida (24.2%). The main predisposing factor for filamentous keratitis was contact lens use. Yeast keratitis is most associated with an immunocompromised host and ocular surface disease. Corneal perforation (20.0%) and surgical interventions (46.8%) were common, with 27.4% of eyes requiring at least one penetrating keratoplasty. Filamentous keratitis is more likely than yeast keratitis to require urgent penetrating keratoplasty or enucleation and to receive more than one topical and systemic antifungal agent. Visual outcomes were poor with nearly half of the eyes remaining at 20/200 or worse upon resolution of infection. Worse visual outcomes were associated with poor vision at presentation and a history of ocular surface disease. Antifungal susceptibility testing was not routinely performed, but it demonstrated a relatively high minimum inhibitory concentration for at least one antifungal drug in 90% of cases when performed (16.1%) and guided the direction of treatment for 80% of the cases.ConclusionFungal keratitis is visually devastating. Infections with filamentous fungi predominated over yeast and were generally treated more aggressively both medically and surgically. Filamentous and yeast keratitis had similar durations of infections and visual outcomes. Antifungal susceptibility testing influenced treatment in 80% of cases in which it was performed.

Mechanistic and nanoarchitectonics insight into Li–host interactions in carbon hosts for reversible Li metal storage

Li metal has been regarded as a promising anode for rechargeable batteries with high energy densities. However, the growth of Li dendrites and severe volume changes in the Li anode still hinder its practical use. Three-dimensional (3D) host structures have recently attracted significant attention as an effective strategy to resolving these problems. Herein, we demonstrate reversible Li metal storage in carbon hosts with strong Li–host interactions derived from metal-organic frameworks (MOFs). The combined experimental and computational modeling studies reveal that galvanically displaced Ag enhances Li–host interactions and the spatial distribution characteristics of Ag play a crucial role in controlling Li storage behavior and reversibility. The atomic Ag clusters trigger the outward growth of Li from the internal pores of the host and enables stable battery cycling, whereas the surface-anchored Ag nanoparticles induce uneven Li plating on the outer surface of the carbon host, resulting in a rapid performance drop. This work provides new insights into the development of advanced host materials for reversible Li anodes by utilizing strong Li–host interactions.

Synergistic Interaction of Piperine and Thymol on Attenuation of the Biofilm Formation, Hyphal Morphogenesis and Phenotypic Switching in Candida albicans.

The incidence of fungal infections has significantly increased in recent years due to the emergence of antifungal resistance. Biofilm formation is considered to be a major contributor to both the infectious diseases and to antimicrobial resistance. Consequently, biofilm-associated infections are often problematic to treat with existing therapeutics. Adhesion of C. albicans to the host surface or implanted materials followed by hyphal invasion and biofilm formation enhances C. albicans pathogenicity and virulence. Thus, developing a therapeutic agent that inhibits candidal adherence, biofilm development and morphological switching could improve clinical management of infections. The present investigation studied two emerging and alternatives strategies, namely antibiofilm and combinatorial approach, to attenuate biofilm formation and the expression of Candida virulence factors. Piperine and thymol are major bioactive components of pepper and thyme, respectively. These phytochemicals are known to possess numerous biological activities, including recently reported antibiofilm effects against C. albicans. The minimum biofilm inhibitory concentration (MBIC) of both phytochemicals was determined to be 32 µg/ml. The phytochemical treatment of Candida biofilms using piperine and thymol revealed synergistic effects at four different combinations of concentrations, i.e. 8 and 8, 8 and 4, 8 and 2 and 4 and 8 µg/ml. These synergistic combinations resulted in the significant reduction in adherence of Candida, hyphal extension and morphological transformation. Moreover, limited exposure of synergistic combinations controlled the hyphal elongation. Results were validated through the gene expression analysis. Results from the present investigation suggest that piperine and thymol can be synergistically employed for the treatment of biofilm-associated C. albicans infection.

Effect of halogenated indoles on biofilm formation, virulence, and root surface colonization by Agrobacterium tumefaciens

Agrobacterium tumefaciens is a plant pathogen that causes crown gall disease in several plant species by transferring its T-DNA to the host genome. Its chemotactic response to a range of chemical compounds released by hosts facilitates its colonization to host surfaces, and thus, novel anti-agrobacterium compounds are needed to prevent its biofilm formation. Here, we investigated 83 indole derivatives against A. tumefaciens, and based on the screening, 4-chloroindole, 6-iodoindole, and 5-chloro-2-methyl indole were selected as candidates that at 50 μg mL−1 significantly inhibited the adherence and biofilm formation of A. tumefaciens to abiotic (nitrocellulose and polystyrene) and biotic (roots of Brassica juncea) surfaces. Furthermore, they reduced bacterial growth in a time and concentration-dependent manner and significantly reduced log CFU mL−1 and survival (%). Changes in biofilm morphologies and biomasses, thicknesses, and substratum coverages were determined, and 2-D and 3-D analyses were performed using a crystal violet assay and bright field, CLSM, and SEM microscopies. Virulence factors such as swimming motility, exopolysaccharide, and exo-protease production, and cell surface hydrophobicity were markedly inhibited by the three compounds. Transcriptional analysis showed multi-fold downregulation of biofilm, virulence, motility, and stress-related genes; however, the degrees of these downregulations were variably affected. B. juncea seed germination was only severely affected by 4-chloroindole. This study demonstrates the promising antibiofilm and antivirulence activities of the three indole derivatives tested and their potentials for targeting and curbing A. tumefaciens infections.

Neuromuscular organization and haptoral armament of Polyclithrum ponticum (Monogenea: Gyrodactylidae).

Most gyrodactylids have a haptor armed with a pair of hamuli, two connecting bars and 16 marginal hooks. In some gyrodactylids, however, the haptor is disc-shaped and reinforced by additional sclerites. The genus Polyclithrum has arguably the most elaborate haptor in this group. This study aimed to gain better understanding of the anatomy of Polyclithrum by examining neuromusculature and haptoral armament of Polyclithrum ponticum, a species parasitizing Mugil cephalus in the Black Sea, with emphasis on haptoral sclerites and musculature in connection with host-attachment mechanisms. Musculature was stained by phalloidin, the nervous system by anti-serotonin and anti-FMRFamide antibodies, and haptoral sclerites were visualized in reflected light. The study provided new information on sclerites: in addition to previously described supplementary sclerites (A1-6), ear-shaped sclerites (ESSs) and two paired groups of ribs, reflected light revealed a rod-shaped process on the ESSs and a pair of small posterior sclerites. The sclerites were shown to be operated by 16 muscles, the most prominent of which were two transverse muscles connecting the hamular roots, three muscles attached to sclerite A2, the muscle fibres of anterior ribs and a set of extrinsic muscles. The nervous system consists of a pair of cerebral ganglia connected by a commissure and three pairs of nerve cords that unite in the haptor to form a loop between the opposite cords. The arrangement of sclerites and muscles suggests that Polyclithrum initiates the attachment by clamping a host's surface with longitudinally folded haptor and then secures its position with marginal hooks.

Supplementation with lipids enhances zoosporulation of Perkinsus species

The protozoan parasite Perkinsus olseni is a major pathogen of marine mollusks. A large number of zoospores (the most infective stage) is required to experimentally examine the transmission and invasion processes of this parasite, but the conventional zoosporulation method in seawater is inefficient. A recent study found that P. olseni zoosporulation was highly enhanced in a nutrient-rich medium which was developed for trophozoite proliferation in Perkinsus. Here, we examined the effect of each medium component on P. olseni zoosporulation and found that lipids enhanced zoosporulation. Moreover, zoospores failed to develop into trophozoites in seawater supplemented with lipids, indicating that this zoosporulation method using seawater supplemented with lipids is ideal for preparing a large number of P. olseni zoospores for various biological assays. Lipid supplementation also significantly enhanced zoosporulation in P. honshuensis, P. chesapeaki, and P. marinus, although the enhancing effect of the lipid supplementation varied by species. Considering the limited availability of lipids in the sea water column, our findings suggest that Perkinsus zoosporulation likely occurs mainly in the vicinity of hosts (not in the sea water column), such as in the mantle cavity or on the body surface of mollusk hosts.

Neglected epiphytism: Accidental epiphytes dominate epiphytic communities on tree ferns in the Atlantic Forest

AbstractVascular epiphytes and tree ferns constitute an important part of the Atlantic Forest structure. We characterized vascular epiphyte communities on two tree fern species (Alsophila setosa Kaulf. and Cyathea phalerata Mart.) including accidental epiphytes (i.e., species that are usually terrestrial, without necessarily completing their life cycle as an epiphyte), which have been overlooked in many previous studies. We aimed to understand epiphytism in terms of distribution, diversity, community composition, and host attributes that affect the richness and abundance of accidental epiphytes. Despite the great species richness of accidental epiphytes, they were—in contrast to true epiphytes—generally low in abundance and heavily represented by singletons and doubletons. We did not identify a difference in accidental epiphytic diversity and composition between host species, implying that both host species provide similar habitats for accidental epiphytes—although some epiphytic species showed a preference for a specific host species and/or stratum. Epiphyte richness and abundance were positively associated with a codependence of host surface area and moisture content, but only for accidental epiphytes. Our study illustrates the importance of two tree fern species as epiphyte hosts in the rainforest understory. It also shows that, although frequently overlooked, accidental epiphytism can be common in the understory of tropical forests and a phenomenon that merits further study in this region.Abstract in Portuguese is available with online material.

Characterization of the MYB Genes Reveals Insights Into Their Evolutionary Conservation, Structural Diversity, and Functional Roles in Magnaporthe oryzae.

The myeloblastosis (MYB) transcription factor family is evolutionarily conserved among plants, animals, and fungi, and contributes to their growth and development. We identified and analyzed 10 putative MYB genes in Magnaporthe oryzae (MoMYB) and determined their phylogenetic relationships, revealing high divergence and variability. Although MYB domains are generally defined by three tandem repeats, MoMYBs contain one or two weakly conserved repeats embedded in extensive disordered regions. We characterized the secondary domain organization, disordered segments, and functional contributions of each MoMYB. During infection, MoMYBs are distinctively expressed and can be subdivided into two clades of being either up- or down-regulated. Among these, MoMYB1 and MoMYB8 are up-regulated during infection and vegetative growth, respectively. We found MoMYB1 localized predominantly to the cytosol during the formation of infection structures. ΔMomyb1 exhibited reduced virulence on intact rice leaves corresponding to the diminished ability to form hypha-driven appressorium (HDA). We discovered that MoMYB1 regulates HDA formation on hard, hydrophobic surfaces, whereas host surfaces partially restored HDA formation in ΔMomyb1. Lipid droplet accumulation in hyphal tips and expression of HDA-associated genes were strongly perturbed in ΔMomyb1 indicating genetic interaction of MoMYB1 with downstream components critical to HDA formation. We also found that MoMYB8 is necessary for fungal growth, dark-induced melanization of hyphae, and involved in higher abiotic stress tolerance. Taken together, we revealed a multifaceted picture of the MoMYB family, wherein a low degree of conservation has led to the development of distinct structures and functions, ranging from fungal growth to virulence.

The transmembrane protein AaSho1 is essential for appressorium formation and secondary metabolism but dispensable for vegetative growth in pear fungal Alternaria alternata

The high-osmolarity glycerol response (HOG) pathway is pivotal in environmental stress response, differentiation and virulence of Alternaria alternata. The synthetic high osmolarity sensitive sensor Sho1 has been postulated to regulate the HOG pathway. To determine the regulatory role of transmembrane protein Sho1 on vegetative growth, secondary metabolism and infection structure formation, a gene (AaSho1) encoding Sho1 was cloned and characterized from A. alternata (JT-03). Sequence analysis showed that AaSho1 has all four characteristic transmembrane domains and the SH3 domain present in another Sho1 gene from several filamentous fungal. The quantitative RT-PCR analysis showed that fruit wax extract significantly up-regulated AaSho1 gene expression in vitro. Pharmacological experiments showed that A. alternata treated with nystatin, a specific AaSho1 inhibitor, had no significant effect on the morphology of A. alternata and the invasive growth in pear fruit. However, nystatin treatment significantly reduced spore germination rates on different wax-coated hydrophobic surfaces, with 58.00, 46.70 and 83.72% reduced for fruit wax, beeswax and paraffin coated. Meanwhile, the secondary metabolism altenuene (ALT), tentoxin (TEN) toxin, and melanin content were also affected by nystatin treatment. These findings suggest that AaSho1 is required for the infection structure differentiation and secondary metabolism of A. alternata in response to physiochemical signals on the host surfaces.