Small Spores Research Articles

Inocybe shawarensis sp. nov. in the Inosperma clade from Pakistan

A new species, Inocybe shawarensis, was collected during field research on ectomycorrhizal fungi associated with oak forests in Swat district, Pakistan. This species, supported by a combination of morphological and molecular phylogenetic analyses, is characterized by a brown, fibrillose campanulate pileus, grayish lamellae, slightly bulbous stipe base, slightly pruinose silvery white stipe, small phaseoliform spores, and clavate cheilocystidia. We present phylogenetic analyses based on DNA sequences from the internal transcribed spacer (ITS) region and large subunit (LSU) of the nuclear ribosomal RNA (rRNA). Phylogenies from both DNA regions cluster I. shawarensis within the Maculata subclade in the Inosperma clade.

Three new species of Lactarius (Russulaceae, Russulales) from Northeast China

Three new species of Lactarius are described from Northeast China, based on morphological comparisons and analyses on ITS nrDNA sequences. Samples of these species were mostly collected from deciduous or mixed forests with oaks. Lactarius albidocinereus, a member of L. subg. Plinthogalus is very similar to European L. azonites in the morphology and the sequence data. It differs from L. azonites by more ellipsoid spores with thinner ornamentation and shorter terminal cells in the pileipellis. Lactarius dilutisalmoneus belongs to L. sect. Zonarii of L. subg. Lactarius due to the pale salmoneus subzonate pileus with glabrous margin, unchanging latex and spore ornamentation composed of isolated elements. In comparison with its relatives, i.e. European L. zonarioides and North American L. olympianus, this new species has smaller spores with more prominent ornamentation. Lactarius olivaceorimosellus, a member of L. subg. Russularia, has areolate-rimulose pileus and lacks rosettes in the pileus and stipe cortex. Apart from the concentrically cracked pileus and absence of rosettes, the species can be easily distinguished by the olivaceo-brownish tinge of the pileus and spores with more dispersed elements of the ornamentation. Of the three species, at least L. albidocinereus represents a link with the Lactarius mycota of subtropical China.

Spore morphology of some Turkish moss species

In this study, spore morphology of Hedwigia ciliata (Hedw.) P.Beauv., H. stellata Hedenäs, Leucodon immersus Lindb. and Funaria hygrometrica Hedw. were examined by light microscopy (LM) and scanning electron microscopy (SEM). All species except L. immersus have small spores, the length of the polar axis (P) is between 8.43 µm and 31.75 µm, equatorial diameter (E) is between 13.09 µm and 38.21 µm. The smallest spores are seen in F. hygrometrica, while the largest spores are seen in L. immersus. The shapes of the spores are determined as oblate for H. ciliata, H. stellata, F. hygrometrica, and suboblate for L. immersus. Ornamentations are differing near leptoma and on distal ornamentation types were observed on the distal pole. Granulate-psilate, psilate, loose baculate-clavate ornamentation types were observed near leptoma. In addition to spore morphology, capsule structures were also examined and were photographed with LM and SEM. As a result, the spore size, shapes and ornamentation types and the capsule structures show differences among these species and these differences can be used as a distinctive characters in the identifications of them

Is interspecific gene flow and speciation in peatmosses (Sphagnum) constrained by phylogenetic relationship and life-history traits?

Peatmosses are interesting for studies of speciation processes not only because of their frequent hybridization and recent diversification, but also their phenotypic diversity, ecological importance and ancient history. Diverse and widespread hybridization has been widely documented in the genus, but little is known about what factors underlie this phenomenon. We hypothesize that these factors include phylogenetic distance and variation in life-history traits of parental species. We summarize current knowledge about the occurrence of hybridization in peatmosses and explore how it is associated with phylogenetic distance and life-history trait variation of parental species. Possibly as much as one out of five (or more) peatmoss species hybridize, mostly producing allopolyploid hybrids. Parents of admixed haploids are more closely related to each other than parents of allopolyploids. Hybridization seems to be most frequent in 1) monoicous and polyoicous species exhibiting 2) relatively high sporulation frequency, 3) producing relatively small spores, as well as 4) growing in poor habitats. Surprisingly, neither phylogenetic proximity nor life-history trait variation explain patterns of hybridization in peatmosses, and other likely explanations for patterns observed are discussed.

Head morphology of the smallest beetles (Coleoptera: Ptiliidae) and the evolution of sporophagy within Staphyliniformia

Ptiliidae include the smallest known beetles. External and internal head structures of species with different body sizes and feeding preferences were examined and described in detail. Saprophagous and sporophagous species are compared. The observed features are evaluated with respect to their phylogenetic and functional significance, and their correlation with extreme size reduction. A putative autapomorphy of Staphyliniformia is an unusual extrinsic maxillary muscle, which among ptiliids is only present in the saprophagous species. Synapomorphies of Ptiliidae and their sister group Hydraenidae are a lateral mandibular process forming a unique locking device with a lateral groove of the labrum, and mandibles divided into a main body and a mesal molar part, both connected by a membrane. Extreme body size reduction is a presumptive autapomorphy of Ptiliidae that probably resulted in the following derived features: the loss of cephalic sutures and ridges, a simplified tentorium, and a brain modified in shape and very large in relation to the head size. The ptiliid species with saprophagous and sporophagous feeding habits show only subtle differences in their cephalic structures, notably in details of the epipharynx and galeae and in the configuration of maxillary muscles. Two alternative scenarios are suggested for the evolution of feeding habits, based on the morphological results and presently available information on phylogenetic relationships. One option is to assign saprophagy to the groundplan of the family, with two switches to sporophagy; first in the basal Nossidium and then a second time in the extremely small Nanosellini, which are characterized by feeding habits that we address as microsporophagy. An alternative scenario is that feeding on spores is ancestral for Ptiliidae, with reversals to saprophagy in several branches of the family, and a specialization on very small spores in the strongly miniaturized nanoselline species. A well-founded species level phylogeny of Ptiliidae with a dense taxon sampling will help to clarify this issue.

Postharvest dip, drench and wax coating application of pyrimethanil on citrus fruit: Residue loading and green mould control

Residue loading of pyrimethanil (PYR) with application methods typically used in South African packhouses and green mould control was studied. PYR was applied curatively (after inoculation) and protectively (before inoculation) in dip, drench and wax coating treatments and fruit were inoculated with an imazalil (IMZ)-sensitive or an IMZ-resistant isolate of Penicillium digitatum, the causal agent of citrus green mould. The dip treatments consisted of PYR concentrations 0, 50, 100, 250, 500 and 1000 mg L−1; fruit were dipped for 60 s at 18 °C at pH 7. Residues loaded differed between fruit type and batch. At the registered concentration of 1000 mg L−1, an average of 1.96 mg kg−1 PYR (range 1.40–2.95 mg kg−1) was loaded. Increased residue levels generally resulted in improved control, but better curative than protective control was observed with effective residue levels of 0.27 and 0.91 mg kg−1 for 50% and 75% curative control of green mould, respectively. Effective residue levels for 50% protective control were 0.97–1.43 mg kg−1. Drench treatments consisted of exposure times of 30, 60 and 90 s with 1000 mg L−1 PYR. PYR residues on Valencia oranges were 2.46–4.22 mg kg−1 PYR, and on navel oranges were 2.09–7.64 mg kg−1. Green mould control on Valencia orange fruit was moderate (57.3–69.8% for curative treatment after 6 h) to relatively poor (4.9–14.6% control for curative treatments after 24 h and 18.1–26.4% for protective treatments). Control on navel oranges following these treatments was poor (0–7%). Drench applications with different combinations of PYR, IMZ, thiabendazole (TBZ), guazatine (GZT) and didecyl dimethyl ammonium chloride were applied to navel orange fruit with 60 s exposure time. In general, fungicide mixtures performed better than single fungicides (44.4–64.6% for mixtures vs. 24.3, 39.6 and 46.5% for PYR, GZT and TBZ respectively). Drench applications where fruit were inoculated with spore suspensions containing 106, 105, 104 or 103 spores mL−1 showed that infections from lower inoculum loads were better controlled (90.6–98.6% vs. 32.6–62.2% for 103vs. 106 spores mL−1). Wax with 2000 or 4000 mg L−1 PYR was applied at 0.6, 1.2 and 1.8 L wax ton−1 of fruit. Residues loaded on navel oranges were 1.75–6.33 mg kg−1, and on Valencia oranges were 1.05–9.91 mg kg−1. Green mould control on navel oranges was poor and were 0–12.2%. On Valencia oranges, higher levels of protective control (28.8–54.0%) than curative treatments (10.5–27.3%) was observed. The IMZ-resistant isolate was successfully controlled by all PYR treatments, in some cases better than the sensitive isolate. In conclusion, PYR provided very good curative control in dip applications, but gave poor results in drench and wax applications. Green mould control following PYR drench treatment improved on fruit inoculated with smaller spore loads, or when PYR was mixed with other fungicides.

Lambiella arenosa, a new species from the coastal Oregon dunes

Abstract The Lambiella caeca group of North America is a poorly known group of diminutive epiphytes with black lecideine apothecia occurring on conifer bark. We describe a new species in this group, L. arenosa, which occurs on Pinus contorta on the dunes of the Oregon coast. Both Lambiella caeca and L. arenosa share a black disk with raised, thin, persistent, often flexuose, black margins, an internally dark exciple that is thin and even, a thin, usually dark brown epithecium, and branched paraphyses that are moniliform in the upper part with K. The easiest characters to differentiate them are the smaller spores (averaging 8–11 μm long) and more conspicuous thallus of L. caeca, in contrast to somewhat larger spores (averaging over 11 μm long) and endosubstratal thallus in L. arenosa. While the known ranges of L. arenosa and L. caeca s.str. do not overlap (hyperoceanic West Coast for L. arenosa, boreal for L. caeca s.str.), a third group of specimens is problematic. Currently, we lack the data to establish...

Fungi in bottom sediments of the barents and Kara seas

The mycobiota of bottom sediments at depths of 128−472 m was investigated in Barents and Kara sea areas remote from the shore. The species composition and fungal abundance, that is, the number of fungal colony-forming units (CFUs), were determined in 5 samples from the Kara Sea and in 14 samples of the Barents Sea. For the first time for the Arctic seas, the fungal biomass was determined in 12 samples of the bottom sediments from the Barents Sea. It was found that fungal abundance in the bottom sediments of the both seas did not exceed 13 CFUs per 1 g of dry substrate weight. In total, only 58 colonies of filamentous fungi belonging to 22 morphotypes, 8 of which were sterile, were isolated from all the samples. No more than six morphotypes were contained in 1 g of dried substrate; they were mostly species of the genus Cladosporium and sterile isolates. The study of the fungal biomass detected both spores and fungal mycelium in the bottom sediments. The total biomass was extremely low and ranged from 0.1 to 0.620 mg/g of the studied substrate. Small spores (with a diameter less than 3 μm) absolutely predominated (from 88 to 99.7% of the biomass).

Removal of Cr(VI) from solution by free and immobilised spores of Aspergillus niger

Despite the current interest in microbial methods for the detoxification of effluents, relatively little work has focused on the characterisation of metal uptake by small Aspergillus niger spores, particularly for heavy metals present at different and low concentrations. The objective of this study was to determine the ability of A. niger spores (free spores and as immobilised biosorbent) to remove toxic metals from an industrial wastewater as a batch system. The simultaneous influences of the mass of pH and biomass on the ability of spores to uptake of Cr(VI) were analysed. The free and immobilised biosorbent removed Cr(VI) efficiently with a maximum metal removal capacity of 55 and 40 mg/g, respectively. The biosorption mechanism was also investigated using Fourier transfer infrared and scanning electron microscopy. Immobilised spores of A. niger were more stable in solutions at different pH levels and allowed easier separation from aqueous solution than free spores, suggesting significant potential for future industrial application.

Construction of Bacillus thuringiensis Simulant Strains Suitable for Environmental Release

For a surrogate bacterium to be used in outdoor studies, it is important to consider environmental and human safety and ease of detection. Recently, Bacillus thuringiensis, a popular bioinsecticide bacterium, has been gaining attention as a surrogate bacterium for use in biodefense. In this study, we constructed simulant strains of B. thuringiensis with enhanced characteristics for environmental studies. Through transposon mutagenesis, pigment genes were inserted into the chromosome, producing yellow-colored colonies for easy detection. To prevent persistence of spores in the environment, a genetic circuit was designed to produce a spore without sporulation capability. Two loxP sites were inserted, one on each side of the spo0A gene, which encodes a sporulation master regulator, and a sporulation-dependent Cre expression cassette was inserted into the chromosome. This genetic circuit successfully deleted spo0A during sporulation, producing spores that lacked the spo0A gene. In addition, two major α/β-type small acid-soluble spore protein (SASP) genes, predicted by synteny analysis, were deleted. The spores of the mutant strain showed increased UV-C sensitivity and quickly lost viability when tested in a solar simulator. When the spores of the mutant strain were administered to the lungs of BALB/c mice, cells were quickly removed from the body, suggesting enhanced in vivo safety. All strains constructed in this study contain no antibiotic resistance markers and all heterologous genes were inserted into the chromosome, which are useful features for simulants to be released into the environment.IMPORTANCEB. thuringiensis has recently been receiving increasing attention as a good spore simulant in biodefense research. However, few studies were done to properly address many important features of B. thuringiensis as a simulant in environmental studies. Since spores can persist in the environment for years after release, environmental contamination is a big problem, especially when genetically engineered strains are used. To solve these problems, we report here the development of B. thuringiensis simulant strains that are capable of forming yellow colonies for easy detection, incapable of forming spores more than once due to a genetic circuit, and lacking in two major SASP genes. The genetic circuit to produce a spore without sporulation capability, together with the deletion of SASP genes, ensures the environmental and human safety of the simulant strains developed in this study. All of these features will allow wider use of B. thuringiensis as a simulant for Bacillus anthracis in environmental release studies.

Characterization of the rax1 gene encoding a putative regulator of G protein signaling in Aspergillus fumigatus

The filamentous fungus Aspergillus fumigatus is the major cause of life threatening invasive aspergillosis, and its small hydrophobic asexual spores (conidia) are the major infection agent. To better understand biology of A. fumigatus, we have characterized the rax1 gene encoding a putative regulator of G protein signaling (RGS). The deletion (Δ) of rax1 results in restricted colony growth and highly reduced number of conidia in A. fumigatus. Transcript levels of the three central activators of asexual development abaA, brlA, and wetA are significantly reduced in the Δrax1 mutant. However, the Δrax1 conidia, but not vegetative cells, are specifically resistant against H2O2 stress. The Δrax1 conidia accumulate higher mRNA levels of sakA encoding a key MAP kinase for stress response. Moreover, the Δrax1 conidia contain over five-fold amount of trehalose, an osmolyte and protein/membrane protectant. Transmission electron microscopy analyses indicate that the Δrax1 conidia have the thicker melanized-outermost cell wall layer compared to those of wild-type. In summary, Rax1 positively controls growth and development, and modulates intracellular trehalose amount, cell wall melanin levels in conidia, and spore resistance to H2O2.

Intestinal microsporidiosis in Iran: infection in immune-compromised and immunocompetent patients.

Gastroenteritis and the clinical profile caused by Microsporidia, an opportunistic pathogen, may be severe in immunocompromised individuals, especially in AIDS patients. Conventionally, it is necessary to detect the small infective spores in stained smears. However, due to the limitations of the microscopy-based methods, several DNA-based methods such as polymerase chain reaction (PCR) have recently been developed to enhance diagnosis sensitivity. Therefore, we sought to evaluate the rate of infection in immunocompromised patients as compared with immunocompetent patients in Kerman, Iran. We collected stool samples of 199 human subjects (116 males and 83 females), aged 1 to 69 years old. They were divided into immunocompromised (i.e., AIDS [n=72] and cancer-positive patients [n=59]) and immunocompetent (n=68) groups. We comparatively examined the fecal materials using the microscopy and PCR methods. The overall prevalence rate of Microsporidia infection was 10.05% (20/199). Entrocytozoon bieneusi was the only species within the Microsporidia genus that was identified in 14.5% (19/131) of the immunocompromised patients and 1.47% (1/68) of the immunocompetent individuals. Considering the higher prevalence rate of microsporidiosis in patients with immunodeficiency (10.03%), we suggest performing sensitive and specific techniques such as PCR for the detection of these parasites in immunocompromised patients.

Intestinal Microsporidiosis in Iran (Kerman): Comparison in immune-compromised patients and immune competent people with diarrhea

Background and Purpose:Gastroenteritis and the clinical profile caused by Microsporidia, an opportunistic pathogen, may be severe in immunocompromised individuals, especially in AIDS patients. Conventionally, it is necessary to detect the small infective spores in stained smears. However, due to the limitations of the microscopy-based methods, several DNA-based methods such as polymerase chain reaction (PCR) have recently been developed to enhance diagnosis sensitivity. Therefore, we sought to evaluate the rate of infection in immunocompromised patients as compared with immunocompetent patients in Kerman, Iran.Materials and Methods:We collected stool samples of 199 human subjects (116 males and 83 females), aged 1 to 69 years old. They were divided into immunocompromised (i.e., AIDS [n=72] and cancer-positive patients [n=59]) and immunocompetent (n=68) groups. We comparatively examined the fecal materials using the microscopy and PCR methods.Results: The overall prevalence rate of Microsporidia infection was 10.05% (20/199). Entrocytozoon bieneusi was the only species within the Microsporidia genus that was identified in 14.5% (19/131) of the immunocompromised patients and 1.47% (1/68) of the immunocompetent individuals.Conclusion:Considering the higher prevalence rate of microsporidiosis in patients with immunodeficiency (10.03%), we suggest performing sensitive and specific techniques such as PCR for the detection of these parasites in immunocompromised patients.

Ecophysiology of bryophytes in the changing environment

Studies of the impact of climate change on plants are generally based on vascular plants. Bryophytes basically differ from tracheophytes in having a smaller size and a poikilohydric strategy for water and nutrients. Their survival and growth are highly dependent on their external environment. Bryophytes are able to lose most of their cell water without dying, and resume normal metabolism after rehydration, gaining positive carbon balance over wet-dry cycles. This sort of adaptation is called desiccation tolerance. Desiccation tolerance is a common phenomenon among bryophytes: cells of bryophytes in exposed sunny sites can switch from full turgor to air dryness quickly, while the species of moist habitats dry more slowly, and can suffer stress by even moderate drying. Bryophytes can maintain efficient photosynthesis under low light conditions, have low chl a/b ratios, and their optimum growth is possible within a limited temperature range. When certain bryophytes’ CO2 assimilation is suppressed, photorespiration activity increases and becomes the main electron sink. Bryophytes, as sensitive components of various vegetation types, are capable of effective light absorption during their desiccation, rehydration, freezing and melting, with the help of coexisting alga and vascular plant energy dissipation mechanisms. They have a relatively low optimal temperature for growth (with narrow T range for net photosynthetic gain), with only minor differences between the optimum temperatures for net photosynthesis in polar, temperate and tropical populations of the same species. Bryophytes have a low acclimatization potential for high temperatures, taking into account that they are generally drought avoiders. Temperature acclimatization potential is of high importance for the physiological basis of altitudinal distribution and the likely responses of bryophytes to climate change. Bryophytes with their small and resistant spores are able to disperse over long distances by wind, which might help their survival in a changing environment. Dominant vascular vegetation might change as temperature will increase; however, suitable microhabitats for bryophytes might still persist. The abundance and species composition of bryophytes in plant communities is predicted to be altered, just as the function of the whole ecosystem. Based on recent literature and own data, the author makes an attempt to summarize the physiological mechanisms, morphological features and alternative strategies that make bryophytes successful in a constantly changing terrestrial environment. These plants represent a sophisticated solution to the challenges of life at their scale. Further exploration of bryophyte ecophysiology in the changing and stressful environment will provide new information that will assist bryophyte conservation.

Multiple Mating Events and Spermatia-Mediated Gene Flow in the Lichen-Forming FungusLobaria pulmonaria

Keller, C. & Scheidegger, C. 2016. Multiple mating events and spermatia-mediated gene flow in the lichen-forming fungus Lobaria pulmonaria. — Herzogia 29: 435–450.Lichen-forming fungi have developed combined reproductive strategies that involve both sexual and asexual propagules, which are produced in varying frequencies over space and time. Lobaria pulmonaria reveals the characteristic traits of genetically diverse, fully recombinant populations, despite the generally rare occurrence of sexual reproductive structures. This study aimed at investigating the genetic diversity of the progenies of single apothecia of L. pulmonaria from different populations. Because the percentage of germinating ascospores is often very small and single spore cultures are thus difficult to obtain, we tested a protocol of DNA isolation from a multispore fraction and identified the alleles of three fungus-specific microsatellite markers. Multispore samples analysed from single apothecia revealed two to three different alleles. This confirms a heterothallic mating system in L. pulmonaria and indicates multiple matings in single apothecia. Paternal thalli were found at different distances up to more than one hundred meters. Our results show that spermatia are an important source of gene flow with dispersal distances in the same order of magnitude as vegetative and sexual diaspores.

English

A study was undertaken along land use gradients with different soil types in subtropical ecosystem of Northern India to evaluate the accurance of arbuscular mycorrhizal fungi (AMF). The gradients was from natural land with forest tree, farmer’s field under chemically managed, farmer’s field under organically managed and Industrial wasteland with five different plant species. We investigate the total AMF species in land use system of different soil types and also in trap culture set from same land use system.Distribution of mycorrhizal species were calculated directly by quantification AMF spores and indirectly by sequencing the SSU-ITS and LSU regions of rDNA. A total 19 AMF morphotypes from direct field sampling and additional 35 morphotypes from trap culture were recovered, which represented seven genera and eighteen species. Result suggested that few Rhizophagus and Funneliformis species came from organically managed and natural land; most of the species came from sites representing chemically managed and industrial wasteland sites from which Gigaspora and Scutellospora species were absent. Organically managed land contributed the largest number of AMF species and diversity, even more than those found in natural sites, which suggests that factors contributing to the diversity of AMF are indeed complex: For example, chemically managed sites not only causes loss of fungal biodiversity but also selectively favors smaller spores of genera Rhizophagus and Funneliformis. Key words: Tillage, diversity, ribosomal dna, raised bed plantation, arbuscular mycorrhizal (AM), morphotypes.

Why did heterospory evolve?

The primitive land plant life cycle featured the production of spores of unimodal size, a condition called homospory. The evolution of bimodal size distributions with small male spores and large female spores, known as heterospory, was an innovation that occurred repeatedly in the history of land plants. The importance of desiccation-resistant spores for colonization of the land is well known, but the adaptive value of heterospory has never been well established. It was an addition to a sexual life cycle that already involved male and female gametes. Its role as a precursor to the evolution of seeds has received much attention, but this is an evolutionary consequence of heterospory that cannot explain the transition from homospory to heterospory (and the lack of evolutionary reversal from heterospory to homospory). Enforced outcrossing of gametophytes has often been mentioned in connection to heterospory, but we review the shortcomings of this argument as an explanation of the selective advantage of heterospory. Few alternative arguments concerning the selective forces favouring heterospory have been proposed, a paucity of attention that is surprising given the importance of this innovation in land plant evolution. In this review we highlight two ideas that may lead us to a better understanding of why heterospory evolved. First, models of optimal resource allocation-an approach that has been used for decades in evolutionary ecology to help understand parental investment and other life-history patterns-suggest that an evolutionary increase in spore size could reach a threshold at which small spores yielding small, sperm-producing gametophytes would return greater fitness per unit of resource investment than would large spores and bisexual gametophytes. With the advent of such microspores, megaspores would evolve under frequency-dependent selection. This argument can account for the appearance of heterospory in the Devonian, when increasingly tall and complex vegetative communities presented competitive conditions that made large spore size advantageous. Second, heterospory is analogous in many ways to anisogamy. Indeed, heterospory is a kind of re-invention of anisogamy within the context of a sporophyte-dominant land plant life cycle. The evolution of anisogamy has been the subject of important theoretical and empirical investigation. Recent work in this area suggests that mate-encounter dynamics set up selective forces that can drive the evolution of anisogamy. We suggest that similar dispersal and mating dynamics could have underlain spore size differentiation. The two approaches offer predictions that are consistent with currently available data but could be tested far more thoroughly. We hope to re-establish attention on this neglected aspect of plant evolutionary biology and suggest some paths for empirical investigation.

Habitat, predators, and hosts regulate disease in Daphnia through direct and indirect pathways

AbstractCommunity ecology can link habitat to disease via interactions among habitat, focal hosts, other hosts, their parasites, and predators. However, complicated food web interactions (i.e., trophic interactions among predators and their impacts on host density and diversity) often obscure the important pathways regulating disease. Here, we disentangle community drivers in a case study of planktonic disease, using a two‐step approach. In step one, we tested univariate field patterns linking community interactions directly to two disease metrics. Density of focal hosts (Daphnia dentifera) was related to density but not prevalence of fungal (Metschnikowia bicuspidata) infections. Both disease metrics appeared to be driven by selective predators that cull infected hosts (fish, e.g., Lepomis macrochirus), sloppy predators that spread parasites while feeding (midges, Chaoborus punctipennis), and spore predators that reduce contact between focal hosts and parasites (other zooplankton, especially small‐bodied Ceriodaphnia sp.). Host diversity also negatively correlated with disease, suggesting a dilution effect. However, several of these univariate patterns were initially misleading, due to confounding ecological links among habitat, predators, host density, and host diversity. In step two, path models uncovered and explained these misleading patterns, and grounded them in habitat structure (refuge size). First, rather than directly reducing infection prevalence, fish predation drove disease indirectly through changes in density of midges and frequency of small spore predators (which became more frequent in lakes with small refuges). Second, small spore predators drove the two disease metrics through fundamentally different pathways: they directly reduced infection prevalence, but indirectly reduced density of infected hosts by lowering density of focal hosts (likely via competition). Third, the univariate diversity–disease pattern (signaling a dilution effect) merely reflected the confounding direct effects of these small spore predators. Diversity per se had no effect on disease, after accounting for the links between small spore predators, diversity, and infection prevalence. In turn, these small spore predators were regulated by both size‐selective fish predation and refuge size. Thus, path models not only explain each of these surprising results, but also trace their origins back to habitat structure.

The structure of fungal biomass and diversity of cultivated micromycetes in Antarctic soils (progress and Russkaya Stations)

The distribution of the fungal biomass and diversity of cultivated microscopic fungi in the profiles of some soils from East (Progress Station, valleys of the Larsemann Hills oasis) and West (Russkaya Station, the Marie Byrd Land) Antarctica regions were studied. The structure of the biomass (spore/mycelium and live cells/dead cells) was analyzed by fluorescence microscopy with staining using a set of coloring agents: calcofluor white, ethidium bromide, and fluorescein diacetate. The species composition of the cultivated microscopic fungi was determined on Czapek’s medium. The fungal biomass in the soils studied is not high (on the average, 0.3 mg/g of soil); the greatest biomass (0.6 mg/g) was found in the soil samples with plant residues. The fungal biomass is mainly (to 70%) represented by small (to 2.5 μm) spores. About half of the fungal biomass is composed of living cells. There are differences in the distribution of the fungal biomass within the profiles of different primitive soils. In the soil samples taken under mosses and lichens, the maximal biomass was registered in the top soil horizons. In the soils with the peat horizon under stone pavements, the greatest fungal biomass was registered in the subsurface horizons. Thirty-eight species of cultivated microscopic fungi were isolated from the soils studied. Species of the genus Penicillium and Phoma herbarum predominated.

Aspergillus fumigatus spore proteomics and genetics reveal that VeA represses DefA-mediated DNA damage response

Aspergillus fumigatus reproduces and infects host by forming a high number of small asexual spores (conidia). The velvet proteins are global transcriptional regulators governing the complex process of conidiogenesis in this fungus. Here, to further understand the velvet-mediated regulation, we carried out comparative proteomic analyses of conidia of wild type (WT) and three velvet mutants (ΔveA, ΔvelB and ΔvosA). Cluster analysis of 184 protein spots showing at least 1.5-fold differential accumulation between WT and mutants reveal the clustering of WT- ΔveA and ΔvelB-ΔvosA. Among 43 proteins identified by Nano-LC-ESI-MS/MS, 23 including several heat shock proteins showed more than two-fold reduction in both the ∆velB and ∆vosA conidia. On the contrary, three proteins exhibited more than five-fold increase in ∆veA only, including the putative RNA polymerase II degradation factor DefA. The deletion of defA resulted in a reduced number of conidia and restricted colony growth. In addition, the defA deletion mutant conidia showed hypersensitivity against the DNA damaging agents NQO and MMS, while the ΔveA mutant conidia were more resistant against to NQO. Taken together, we propose that VeA controls protein level of DefA in conidia, which are dormant and equipped with multiple layers of protection against environmental cues.