Fungal propagules and DNA in feces of two detritus-feeding amphipods

Pathogens and other symbionts of the Amphipoda: taxonomic diversity and pathological significance

With over 10000 species of Amphipoda currently described, this order is one of the most diverse groups of freshwater and marine Crustacea. Members of this group are globally distributed, and many are keystone species and ecosystem engineers within their respective ecologies. As with most organisms, disease is a key factor that can alter population size, behaviour, survival, invasion potential and physiology of amphipod hosts. This review explores symbiont diversity and pathology in amphipods by coalescing a range of current and historical literature to provide the first full review of our understanding of amphipod disease. The review is broken into 2 parts. The first half explores amphipod microparasites, which include data pertaining to viruses, bacteria, fungi, oomycetes, microsporidians, dinoflagellates, myxozoans, ascetosporeans, mesomycetozoeans, apicomplexans and ciliophorans. The second half reports the metazoan macroparasites of Amphipoda, including rotifers, trematodes, acanthocephalans, nematodes, cestodes and parasitic Crustacea. In all cases we have endeavoured to provide a complete list of known species that cause disease in amphipods, while also exploring the effects of parasitism. Although our understanding of disease in amphipods requires greater research efforts to better define taxonomic diversity and host effects of amphipod symbionts, research to date has made huge progress in cataloguing and experimentally determining the effects of disease upon amphipods. For the future, we suggest a greater focus on developing model systems that use readily available amphipods and diseases, which can be comparable to the diseases in other Crustacea that are endangered, economically important or difficult to house.

Novel soil-inhabiting clades fill gaps in the fungal tree of life

BACKGROUND

Fungi are a diverse eukaryotic group of degraders, pathogens, and symbionts, with many lineages known only from DNA sequences in soil, sediments, air, and water.

RESULTS

We provide rough phylogenetic placement and principal niche analysis for >40 previously unrecognized fungal groups at the order and class level from global soil samples based on combined 18S (nSSU) and 28S (nLSU) rRNA gene sequences. Especially, Rozellomycota (Cryptomycota), Zygomycota s.lat, Ascomycota, and Basidiomycota are rich in novel fungal lineages, most of which exhibit distinct preferences for climate and soil pH.

CONCLUSIONS

This study uncovers the great phylogenetic richness of previously unrecognized order- to phylum-level fungal lineages. Most of these rare groups are distributed in different ecosystems of the world but exhibit distinct ecological preferences for climate or soil pH. Across the fungal kingdom, tropical and non-tropical habitats are equally likely to harbor novel groups. We advocate that a combination of traditional and high-throughput sequencing methods enable efficient recovery and phylogenetic placement of such unknown taxonomic groups.

Effects of two fungicide formulations on microbial and macroinvertebrate leaf decomposition under laboratory conditions

Aquatic fungi contribute significantly to the decomposition of leaves in streams, a key ecosystem service. Little is known, however, about the effects of fungicides on aquatic fungi and macroinvertebrates involved with leaf decomposition. Red maple (Acer rubrum) leaves were conditioned in a stream to acquire microbes (bacteria and fungi) or leached in tap water (unconditioned) to simulate potential reduction of microbial biomass by fungicides. Conditioned leaves were exposed to fungicide formulations QUILT (azoxystrobin + propiconazole) or PRISTINE (boscalid + pyraclostrobin) in the presence and absence of the leaf shredder, Hyalella azteca (amphipods; 7-d old at start of exposures) for 14 d at 23 °C. The QUILT formulations (∼0.3 μg/L, 1.8 μg/L, and 8 μg/L) tended to increase leaf decomposition by amphipods (not significant) without a concomitant increase in amphipod biomass, indicating potential increased consumption of leaves with reduced nutritional value. The PRISTINE formulation (∼33 μg/L) significantly reduced amphipod growth and biomass (p < 0.05), effects similar to those observed with unconditioned controls. The significant suppressive effects of PRISTINE on amphipod growth and the trend toward increased leaf decomposition with increasing QUILT concentration indicate the potential for altered leaf decay in streams exposed to fungicides. Further work is needed to evaluate fungicide effects on leaf decomposition under conditions relevant to stream ecosystems, including temperature shifts and pulsed exposures to pesticide mixtures. Environ Toxicol Chem 2016;35:2834-2844. Published 2016 Wiley Periodicals Inc. on behalf of SETAC. This article is a US Government work and, as such, is in the public domain in the United States of America.

Metabarcoding-based fungal diversity on coarse and fine particulate organic matter in a first-order stream in Nova Scotia, Canada

Most streams receive substantial inputs of allochthonous organic material in the form of leaves and twigs (CPOM , coarse particulate organic matter). Mechanical and biological processing converts this into fine particulate organic matter (FPOM). Other sources of particles include flocculated dissolved matter and soil particles. Fungi are known to play a role in the CPOM conversion process, but the taxonomic affiliations of these fungi remain poorly studied. The present study seeks to shed light on the composition of fungal communities on FPOM and CPOM as assessed in a natural stream in Nova Scotia, Canada. Maple leaves were exposed in a stream for four weeks and their fungal community evaluated through pyrosequencing. Over the same period, four FPOM size fractions were collected by filtration and assessed. Particles had much lower ergosterol contents than leaves, suggesting major differences in the extent of fungal colonization. Pyrosequencing documented a total of 821 fungal operational taxonomic units (OTU), of which 726 were exclusive to particles and 47 to leaf samples. Most fungal phyla were represented, including yeast lineages (e.g., Taphrinaceae and Saccharomycotina), Basidiomycota, Chytridiomycota and Cryptomycota, but several classes of Pezizomycontina (Ascomycota) dominated. Cluster dendrograms clearly separated fungal communities from leaves and from particles. Characterizing fungal communities may shed some light on the processing pathways of fine particles in streams and broadens our view of the phylogenetic composition of fungi in freshwater ecosystems.

Metabarcoding-based fungal diversity on coarse and fine particulate organic matter in a first-order stream in Nova Scotia, Canada

Most streams receive substantial inputs of allochthonous organic material in the form of leaves and twigs (CPOM , coarse particulate organic matter). Mechanical and biological processing converts this into fine particulate organic matter (FPOM). Other sources of particles include flocculated dissolved matter and soil particles. Fungi are known to play a role in the CPOM conversion process, but the taxonomic affiliations of these fungi remain poorly studied. The present study seeks to shed light on the composition of fungal communities on FPOM and CPOM as assessed in a natural stream in Nova Scotia, Canada. Maple leaves were exposed in a stream for four weeks and their fungal community evaluated through pyrosequencing. Over the same period, four FPOM size fractions were collected by filtration and assessed. Particles had much lower ergosterol contents than leaves, suggesting major differences in the extent of fungal colonization. Pyrosequencing documented a total of 821 fungal operational taxonomic units (OTU), of which 726 were exclusive to particles and 47 to leaf samples. Most fungal phyla were represented, including yeast lineages (e.g., Taphrinaceae and Saccharomycotina), Basidiomycota, Chytridiomycota and Cryptomycota, but several classes of Pezizomycontina (Ascomycota) dominated. Cluster dendrograms clearly separated fungal communities from leaves and from particles. Characterizing fungal communities may shed some light on the processing pathways of fine particles in streams and broadens our view of the phylogenetic composition of fungi in freshwater ecosystems.

Morphology, phylogeny, and ecology of the aphelids (Aphelidea, Opisthokonta) and proposal for the new superphylum Opisthosporidia

The aphelids are a small group of intracellular parasitoids of common species of eukaryotic phytoplankton with three known genera Aphelidium, Amoeboaphelidium, and Pseudaphelidium, and 10 valid species, which form along with related environmental sequences a very diversified group. The phyla Microsporidia and Cryptomycota, and the class Aphelidea have recently been considered to be a deep branch of the Holomycota lineage forming the so called the ARM-clade which is sister to the fungi. In this review we reorganize the taxonomy of ARM-clade, and establish a new superphylum the Opisthosporidia with three phyla: Aphelida phyl. nov., Cryptomycota and Microsporidia. We discuss here all aspects of aphelid investigations: history of our knowledge, life cycle peculiarities, the morphology (including the ultrastructure), molecular phylogeny, ecology, and provide a taxonomic revision of the phylum supplied with a list of species. We compare the aphelids with their nearest relatives, the species of Rozella, and improve the diagnosis of the phylum Cryptomycota.

Gromochytrium mamkaevae gen. & sp. nov. and two new orders: Gromochytriales and Mesochytriales (Chytridiomycetes)

During the last decade several new orders were established in the class Chytridiomycetes on the basis of zoospore ultrastructure and molecular phylogeny. Here we present the ultrastructure and molecular phylogeny of strain x-51 CALU – a parasite of the alga Tribonema gayanum, originally described as Rhizophydium sp. based on light microscopy. Detailed investigation revealed that the zoospore ultrastructure of this strain has unique characters not found in any order of Chytridiomycetes: posterior ribosomal core unbounded by the endoplasmic reticulum and detached from the nucleus or microbody-lipid complex, and kinetosome composed of microtubular doublets. An isolated phylogenetic position of x-51 is further confirmed by the analysis of 18S and 28S rRNA sequences, and motivates the description of a new genus and species Gromochytrium mamkaevae. The sister position of G. mamkaevae branch relative to Mesochytrium and a cluster of environmental sequences, as well as the ultrastructural differences between Gromochytrium and Mesochytrium zoospores prompted us to establish two new orders: Gromochytriales and Mesochytriales.