Racocetra cromosomica sp. nov. from Oaxaca, Mexico

Analysis of soil samples collected in the rhizosphere of Agave karwinskii in the Central Valleys of Oaxaca, Mexico, revealed an undescribed species of Racocetra that possesses ornamented spores. The ornamentation on the outer layer of the external spore wall consisted of rounded and elongated processes, which are organized in such a way that they look like chromosomes. Therefore, the new species was named Racocetra cromosomica. It is the first species of Racocetraceae (Gigasporales) described from Oaxaca, one of the Mexican states having the greatest floristic diversity.

Species of the genus Galerina (Hymenogastraceae) with calyptrate spores in Ukraine

The article provides information on distribution of some noteworthy representatives of the genus Galerina in Ukraine. This genus is still rather fragmentarily studied in the country, therefore it is a subject of a series of special articles. The previous two articles, on the species of Galerina with tibiiform cheilocystidia and those possessing pleurocystidia, have already been published. This article reports species with so-called calyptrate spores. In these spores, the outer layer of the spore wall (perisporium) is separated from the main wall to form blisters at the basal (sometimes also apical) part of the spore. One of the reported species, Galerina sahleri, was found for the first time in Ukraine; other three species (G. cerina, G. hypnorum, and G. sphagnicola) were recorded in new localities. All these fungi are bryotrophic, often sphagnicolous. Their diagnoses, data about finds in Ukraine and general distribution as well as original drawings of the fruit bodies and microstructures are provided.

The false mussels (Mytilopsis leucophaeata) can be mechanical carriers of the shrimp microsporidian Enterocytozoon hepatopenaei (EHP)

Enterocytozoon hepatopenaei (EHP) is an obligate intracellular parasite causing hepatopancreatic microsporidiosis (HPM) in cultivated shrimp in Asian countries. One strategy to control EHP is to identify and eliminate biological reservoir(s) in shrimp ponds. Several marine and brackish-water organisms, including false mussels (Mytilopsis) have been reported to test positive for EHP using polymerase chain reaction (PCR) technology. Thus, we tested samples of commonly found Thai false mussel Mytilopsis leucophaeata from 6 EHP-infected shrimp ponds by PCR for the presence of EHP using the spore wall protein (SWP) gene primers. The mussel samples from all 6 ponds were positive. Subsequent bioassays carried out using naive mussels cohabitated with EHP-infected shrimp gave 100% SWP-PCR positive mussels at 20 days. One batch of such PCR-positive mussels was transferred for cohabitation with naive shrimp and gave 37.5% EHP-positive shrimp within 10 days. Tissue analysis of the EHP-PCR-positive mussels using light microscopy, in situ hybridization analysis for the SWP gene and electron microscopy did not confirm EHP infection. In summary, we obtained no evidence that Mytilopsis leucophaeata was itself infected with EHP. However, it was apparently capable carrying infectious spores for some period after ingestion and serving as a mechanical or passive carrier. The results support previous reports warning of the danger of feeding living or fresh bivalves to broodstock shrimp in hatcheries or shrimp in rearing ponds without prior heating or freezing.

New Glomeromycotan Taxa, Dominikia glomerocarpica sp. nov. and Epigeocarpum crypticum gen. nov. et sp. nov. From Brazil, and Silvaspora gen. nov. From New Caledonia

Examination of fungal specimens collected in the Atlantic rain forest ecosystems of Northeast Brazil revealed many potentially new epigeous and semihypogeous glomerocarp-producing species of the phylum Glomeromycota. Among them were two fungi that formed unorganized epigeous glomerocarps with glomoid spores of almost identical morphology. The sole structure that distinguished the two fungi was the laminate layer 2 of their three-layered spore wall, which in spores of the second fungus crushed in PVLG-based mountants contracted and, consequently, transferred into a crown-like structure. Surprisingly, phylogenetic analyses of sequences of the 18S-ITS-28S nuc rDNA and the rpb1 gene indicated that these glomerocarps represent two strongly divergent undescribed species in the family Glomeraceae. The analyses placed the first in the genus Dominikia, and the second in a sister clade to the monospecific generic clade Kamienskia with Kamienskia bistrata. The first species was described here as Dominikia glomerocarpica sp. nov. Because D. glomerocarpica is the first glomerocarp-forming species in Dominikia, the generic description of this genus was emended. The very large phylogenetic distance and the fundamental morphological differences between the second species and K. bistrata suggested us to introduce a new genus, here named as Epigeocarpum gen. nov., and name the new species Epigeocarpum crypticum sp. nov. In addition, our analyses also focused on an arbuscular mycorrhizal fungus originally described as Rhizophagus neocaledonicus, later transferred to the genus Rhizoglomus. The analyses indicated that this species does not belong to any of these two genera but represents a new clade at the rank of genus in the Glomeraceae, here described as Silvaspora gen. nov.

Characterization of the mbsA Gene Encoding a Putative APSES Transcription Factor in Aspergillus fumigatus

The APSES family proteins are transcription factors (TFs) with a basic helix-loop-helix domain, known to regulate growth, development, secondary metabolism, and other biological processes in Aspergillus species. In the genome of the human opportunistic pathogenic fungus Aspergillus fumigatus, five genes predicted to encode APSES TFs are present. Here, we report the characterization of one of these genes, called mbsA (Afu7g05620). The deletion (Δ) of mbsA resulted in significantly decreased hyphal growth and asexual sporulation (conidiation), and lowered mRNA levels of the key conidiation genes abaA, brlA, and wetA. Moreover, ΔmbsA resulted in reduced spore germination rates, elevated sensitivity toward Nikkomycin Z, and significantly lowered transcripts levels of genes associated with chitin synthesis. The mbsA deletion also resulted in significantly reduced levels of proteins and transcripts of genes associated with the SakA MAP kinase pathway. Importantly, the cell wall hydrophobicity and architecture of the ΔmbsA asexual spores (conidia) were altered, notably lacking the rodlet layer on the surface of the ΔmbsA conidium. Comparative transcriptomic analyses revealed that the ΔmbsA mutant showed higher mRNA levels of gliotoxin (GT) biosynthetic genes, which was corroborated by elevated levels of GT production in the mutant. While the ΔmbsA mutant produced higher amount of GT, ΔmbsA strains showed reduced virulence in the murine model, likely due to the defective spore integrity. In summary, the putative APSES TF MbsA plays a multiple role in governing growth, development, spore wall architecture, GT production, and virulence, which may be associated with the attenuated SakA signaling pathway.

Notes on lichenicolous species of Opegrapha s. lat. (Arthoniales) on Arthoniaceae and Verrucariaceae, with a key to British and Irish lichenicolous Opegraphaceae

Three species of lichenicolous Opegrapha s. lat. are newly described, all apparently host-specific at genus level. Opegrapha arthoniicola Coppins & S. Y. Kondr. is described from western Britain and Ireland, where it grows on the thallus of Arthonia radiata on Corylus bark; it has small clustered ascomata, asci that are usually 6-spored and rather small ascospores (10.5–)12.5–14.5 μm in length. Opegrapha sawyeriana Coppins occurs on the thallus of Coniocarpon cinnabarinum, also on Corylus bark, from oceanic western parts of Scotland, Ireland and southern England; in comparison to O. arthoniicola it has smaller, often scattered ascomata with a pigmented basal layer, 8-spored asci and slightly larger ascospores 13–14.5(–16) μm in length. Opegrapha hochstetteri Coppins has been found on thalli of Verrucaria hochstetteri and V. muralis on calcareous rocks and stonework in southern England and Luxembourg; collections were formerly identified as Opegrapha rupestris Pers. but it differs from this species by narrower ascomata with a persistent narrow slit, normally 6- rather than 8-spored asci and ascospores with pigmentation in the spore wall rather than the perispore. Lifted from synonymy is Opegrapha opaca Nyl., which inhabits the thallus of Verrucaria nigrescens and V. viridula on calcareous rocks and stonework, and is so far recorded from southern England, Luxembourg, France, northern Spain and Israel. The hosts of the European species of lichenicolous Opegrapha on Verrucaria s. lat. on calcareous rocks (O. hochstetteri, O. opaca and O. rupestris) belong to different phylogenetic lineages within the Verrucariaceae. A key is also provided to the lichenicolous species of Opegraphaceae currently known from Great Britain and Ireland.

RNA Interference-Mediated Knockdown of Genes Encoding Spore Wall Proteins Confers Protection against Nosema ceranae Infection in the European Honey Bee, Apis mellifera

Nosema ceranae (Opisthosporidia: Microsporidia) is an emergent intracellular parasite of the European honey bee (Apis mellifera) and causes serious Nosema disease which has been associated with worldwide honey bee colony losses. The only registered treatment for Nosema disease is fumagillin-b, and this has raised concerns about resistance and off-target effects. Fumagillin-B is banned from use in honey bee colonies in many countries, particularly in Europe. As a result, there is an urgent need for new and effective therapeutic options to treat Nosema disease in honey bees. An RNA interference (RNAi)-based approach can be a potent strategy for controlling diseases in honey bees. We explored the therapeutic potential of silencing the sequences of two N. ceranae encoded spore wall protein (SWP) genes by means of the RNAi-based methodology. Our study revealed that the oral ingestion of dsRNAs corresponding to SWP8 and SWP12 used separately or in combination could lead to a significant reduction in spore load, improve immunity, and extend the lifespan of N. ceranae-infected bees. The results from the work completed here enhance our understanding of honey bee host responses to microsporidia infection and highlight that RNAi-based therapeutics are a promising treatment for honey bee diseases.