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In 2021, White Trevally or Striped Jack cultured in the western part of Japan exhibited mild, but chronic mortalities from late September through early October. The cumulative mortality rate was approximately 0.02% per a net pen containing approximately 50,000 fish. Although the cumulative mortality rate was not high, most of the fish in net pens showed characteristic gross signs and an abnormal swimming behaviour. The body of diseased fish became pale and the yellow lines on the lateral sides of fish body became darken. In addition, silver lines along the dorsal fin became apparent. Loss of schooling behaviour was noted during the mortality event. In addition, affected fish became lethargic and failed to swim against current, or frequently stopped swimming and sank to the bottom of net pens after feeding. The goal of this study was to identify the cause of the mortality event. To achieve the goal, we used histopathology and metatranscriptome analysis. Histopathological examination revealed that xenoma of microsporidian were frequently observed in the nerve axon in the brain and spinal cord. Spores observed in the sections were stained with a fluorescent dye, Uvitex 2B, indicating those spores are microsporidian. The data from metatranscriptome analysis indicated that the microsporidian is Spraguea sp. The microsporidian was frequently detected from diseased fish with similar symptoms collected in the same region, suggesting that the microsporidian was highly associated with abnormal swimming behaviour of fish. [ABSTRACT FROM AUTHOR]

Vairimorpha (Nosema) ceranae is a single-cellular fungus that obligately infects the midgut epithelial cells of adult honeybees, causing bee microsporidiosis and jeopardizing bee health and production. This work aims to construct the full-length transcriptome of V. ceranae and conduct a relevant investigation using PacBio single-molecule real-time (SMRT) sequencing technology. Following PacBio SMRT sequencing, 41,950 circular consensus (CCS) were generated, and 25,068 full-length non-chimeric (FLNC) reads were then detected. After polishing, 4387 high-quality, full-length transcripts were gained. There are 778, 2083, 1202, 1559, 1457, 1232, 1702, and 3896 full-length transcripts that could be annotated to COG, GO, KEGG, KOG, Pfam, Swiss-Prot, eggNOG, and Nr databases, respectively. Additionally, 11 alternative splicing (AS) events occurred in 6 genes were identified, including 1 alternative 5′ splice-site and 10 intron retention. The structures of 225 annotated genes in the V. ceranae reference genome were optimized, of which 29 genes were extended at both 5′ UTR and 3′ UTR, while 90 and 106 genes were, respectively, extended at the 5′ UTR as well as 3′ UTR. Furthermore, a total of 29 high-confidence lncRNAs were obtained, including 12 sense-lncRNAs, 10 lincRNAs, and 7 antisense-lncRNAs. Taken together, the high-quality, full-length transcriptome of V. ceranae was constructed and annotated, the structures of annotated genes in the V. ceranae reference genome were improved, and abundant new genes, transcripts, and lncRNAs were discovered. Findings from this current work offer a valuable resource and a crucial foundation for molecular and omics research on V. ceranae. [ABSTRACT FROM AUTHOR]

Despite the economic and evolutionary significance of microsporidian species that infect aquatic hosts, little is known about how microsporidia interact with hosts. This study focused on Potaspora macrobrachium, a new microsporidium identified in the oriental river prawn, Macrobrachium nipponense. Gross pathology, histology with H.E. staining, and transmission electron microscopy (TEM) were performed to confirm the microsporidian infections. To learn more about the prawn anti-microsporidian response, de novo transcriptome sequencing of the hepatopancreas tissue—a significant source of innate immune molecules—was also conducted. The clean reads of the microsporidian-infected and control groups were 40.46 M and 40.83 M, respectively. 117,853 unigenes were functionally annotated using homology searches and six databases: Nr, Swiss-Prot, KEGG, eggNOG, Pfam, and G.O. 107 genes were considerably up-regulated, whereas 71 genes were down-regulated. The primary immune and metabolic signalling pathways, such as the ''MAPK signalling pathway,'' ''apoptosis,'' ''autophagy,'' ''endocytosis,'' ''lysosome,'' ''fatty acid biosynthesis,'' ''protein processing in the endoplasmic reticulum,'' ''spliceosome,'' and ''pancreatic secretion,'' were linked to the differentially expressed genes (DEGs). This implies that M. nipponense adopts various strategies to deal with microsporidian infection. To ensure the accuracy of the transcriptome data, eight DEGs were randomly chosen to participate in qRT-PCR validation. Additionally, single nucleotide polymorphisms (SNPs) and simple sequence repeats (SSRs) were detected within the gene library. These findings allow us to understand better the underlying processes governing the interactions of microsporidian parasites and the commercially important prawn, M. nipponense.

Parasites can play key roles in ecosystems, especially when they infect common hosts that play important ecological roles. Daphnia are critical grazers in many lentic freshwater ecosystems and typically reach peak densities in early spring. Daphnia have also become prominent model host organisms for the field of disease ecology, although most well-studied parasites infect them in summer or fall. Here, we report field patterns of virulent microsporidian parasites that consistently infect Daphnia in springtime, in a set of seven shallow ponds in Georgia, USA, sampled every 3–4 weeks for 18 months. We detected two distinct parasite taxa, closely matching sequences of Pseudoberwaldia daphniae and Conglomerata obtusa, both infecting all three resident species of Daphnia: D. ambigua, D. laevis, and D. parvula. To our knowledge, neither parasite has been previously reported in any of these host species or anywhere in North America. Infection prevalence peaked consistently in February–May, but the severity of these outbreaks difered substantially among ponds. Moreover, host species differed markedly in terms of their maximum infection prevalence (5% [D. parvula] to 72% [D. laevis]), mean reduction of fecundity when infected (70.6% [D. ambigua] to 99.8% [D. laevis]), mean spore yield (62,000 [D. parvula] to 377,000 [D. laevis] per host), and likelihood of being infected by each parasite. The timing and severity of the outbreaks suggests that these parasites could be impactful members of these shallow freshwater ecosystems, and that the strength of their effects is likely to hinge on the composition of ponds’ zooplankton communities. [ABSTRACT FROM AUTHOR]

Copyright of Journal of South China Agricultural University is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Honey bees (Apis mellifera) are critical agricultural pollinators as well as model organisms for research on development, behavior, memory, and learning. The parasite Nosema ceranae, a common cause of honey bee colony collapse, has developed resistance to small-molecule therapeutics. An alternative long-term strategy to combat Nosema infection is therefore urgently needed, with synthetic biology offering a potential solution. Honey bees harbor specialized bacterial gut symbionts that are transmitted within hives. Previously, these have been engineered to inhibit ectoparasitic mites by expressing double-stranded RNA (dsRNA) targeting essential mite genes, via activation of the mite RNA interference (RNAi) pathway. In this study, we engineered a honey bee gut symbiont to express dsRNA targeting essential genes of N. ceranae via the parasite's own RNAi machinery. The engineered symbiont sharply reduced Nosema proliferation and improved bee survival following the parasite challenge. This protection was observed in both newly emerged and older forager bees. Furthermore, engineered symbionts were transmitted among cohoused bees, suggesting that introducing engineered symbionts to hives could result in colony-level protection. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Entomology is the property of Chinese Journal of Applied Entomology, Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The genus Vairimorpha was proposed for several species of Nosema in 1976 (Pilley, 1976), almost 70 years after Nosema apis Zander (Zander, 1909). Tokarev and colleagues proposed the redefinition of 17 microsporidian species in four genera, Nosema , Vairimorpha , Rugispora , and Oligosporidium , based on phylogenetic trees of two genetic markers (SSU rRNA and RPB1) (Tokarev et al., 2020). Several issues should invalidate this new classification, leading to the synonymization of Vairimorpha within Nosema. [ABSTRACT FROM AUTHOR]

As a new generation of high-throughput sequencing technology, PacBio Iso-Seq technology (Iso-Seq) provides a better alternative sequencing method for the acquisition of full-length unigenes. In this study, a total of 22.27 gigabyte (Gb) subread bases and 128,614 non-redundant unigenes (mean length: 2,324 bp) were obtained from six main tissues of Eriocheir sinensis including the heart, nerve, intestine, muscle, gills and hepatopancreas. In addition, 74,732 unigenes were mapped to at least one of the following databases: Non-Redundant Protein Sequence Database (NR), Gene Ontology (GO), Kyoto Encyclopaedia of Genes and Genomes (KEGG), KEGG Orthology (KO) and Protein family (Pfam). In addition, 6696 transcription factors (TFs), 28,458 long non-coding RNAs (lncRNAs) and 94,230 mRNA-miRNA pairs were identified. Hepatospora eriocheir is the primary pathogen of E. sinensis and can cause hepatopancreatic necrosis disease (HPND); the intestine is the main target tissue. Here, we attempted to identify the key genes related to H. eriocheir infection in the intestines of E. sinensis. By combining Iso-Seq and Illumina RNA-seq analysis, we identified a total of 12,708 differentially expressed unigenes (DEUs; 6,696 upregulated and 6,012 downregulated) in the crab intestine following infection with H. eriocheir. Based on the biological analysis of these DEUs, several key processes were identified, including energy metabolism-related pathways, cell apoptosis and innate immune-related pathways. Twelve selected genes from these DEUs were subsequently verified by quantitative real-time PCR (qRT-PCR) analysis. Our findings enhance our understanding of the E. sinensis transcriptome and the specific association between E. sinensis and H. eriocheir infection.

Standing genetic variation is the predominant source acted on by selection. Organisms with high genetic diversity generally show faster responses toward environmental change. Nosema ceranae is a microsporidian parasite of honey bees, infecting midgut epithelial cells. High genetic diversity has been found in this parasite, but the mechanism for the parasite to maintain this diversity remains unclear. This study involved continuous inoculation of N. ceranae to honey bees. We found that the parasites slowly increased genetic diversity over three continuous inoculations. The number of lost single nucleotide variants (SNVs) was balanced with novel SNVs, which were mainly embedded in coding regions. Classic allele frequency oscillation was found at the regional level along the genome, and the associated genes were enriched in apoptosis regulation and ATP binding. The ratio of synonymous and non-synonymous substitution suggests a purifying selection, and our results provide novel insights into the evolutionary dynamics in microsporidian parasites. [ABSTRACT FROM AUTHOR]

Asian honey bee Apis cerana is the original host for Nosema ceranae, a unicellular fungal parasite that causes bee nosemosis throughout the world. Currently, interaction between A. cerana and N. ceranae is largely unknown. Our group previously prepared A. c. cerana workers' midguts at 7days post inoculation (dpi) and 10 dpi with N. ceranae spores as well as corresponding un-inoculated workers' midguts, followed by cDNA library construction and a combination of RNAs-seq and small RNA-seq. Meanwhile, we previously prepared clean spores of N. ceranae, which were then subjected to cDNA library construction and deep sequencing. Here, based on the gained high-quality transcriptome datasets, N. ceranae differentially expressed mRNAs (DEmiRNAs) targeted by host DEmiRNAs, and A. c. cerana DEmRNAs targeted by microsporidian DEmiRNAs were deeply investigated, with a focus on targets involved in N. ceranae glycolysis/glyconeogenesis as well as virulence factors, and A. c. cerana energy metabolism and immune response. In A. c. cerana worker's midguts at 7 (10) dpi (days post inoculation), eight (seven) up-regulated and six (two) down-regulated miRNAs were observed to target 97 (44) down-regulated and 60 (15) up-regulated N. ceranae mRNAs, respectively. Additionally, two up-regulated miRNAs (miR-60-y and miR-676-y) in host midgut at 7 dpi could target genes engaged in N. ceranae spore wall protein and glycolysis/gluconeogenesis, indicating potential host miRNA-mediated regulation of microsporidian virulence factor and energy metabolism. Meanwhile, in N. ceranae at 7 (10) dpi, 121 (110) up-regulated and 112 (104) down-regulated miRNAs were found to, respectively, target 343 (247) down-regulated and 138 (110) down-regulated mRNAs in A. c. cerana workers' midguts. These targets in host were relevant to several crucial cellular and humoral immune pathways, such as phagasome, endocytosis, lysosomes, regulation of autophagy, and Jak-STAT signaling pathway, indicative of the involvement of N. ceranae DEmiRNAs in regulating these cellular and humoral immune pathways. In addition, N. ceranae miR-21-x was up-regulated at 7 dpi and had a target relative to oxidative phosphorylation, suggesting that miR-21-x may be used as a weapon to modulate this pivotal energy metabolism pathway. Furthermore, potential targeting relationships between two pairs of host DEmiRNAs-microsporidian DEmRNAs and two pairs of microsporidian DEmiRNAs-host DEmRNAs were validated using RT-qPCR. Our findings not only lay a foundation for exploring the molecular mechanism underlying cross-kingdom regulation between A. c. cerana workers and N. ceranae, but also offer valuable insights into Asian honey bee-microsporidian interaction. [ABSTRACT FROM AUTHOR]

The microsporidian Desmozoon lepeophtherii Freeman and Sommerville, 2009 is considered significant in the pathogenesis of gill disease in Atlantic salmon (Salmo salar Linnaeus, 1758). Due to the difficulty in detecting D. lepeophtherii in tissue sections, infections are normally diagnosed by molecular methods, routine haematoxylin and eosin (H&E) stained gill tissue sections and the use of other histochemical stains and labels to confirm the presence of spores. An in situ hybridization (ISH) protocol specific for D. lepeophtherii was developed using DIG‐labelled oligonucleotide probes. Diseased Atlantic salmon gills were analysed by ISH, calcofluor white (CW) and H&E. All methods showed high levels of specificity (100%) in their ability to detect D. lepeophtherii, but the sensitivity was higher with ISH (92%), compared with CW (64%) and the presence of microvesicles on H&E stained sections (52%). High levels of D. lepeophtherii spores were significantly associated (p <.05) with the development of D. lepeophtherii‐associated pathology in the gills, with Ct values below 19 and over 100 microsporidia/10 mm2 of gill tissue (from the ISH counts) seemingly necessary for the development of microvesicles. The ISH method has the advantage over other histological techniques in that it allows all life stages of the microsporidian to be detected in infected salmon gill tissue sections. [ABSTRACT FROM AUTHOR]

Simple Summary: At present, interaction between Nosema ceranae and Apis cerana is poorly understood, though A. cerana is the original host for N. ceranae. Here, comparative investigation was conducted using transcriptome data from N. ceranae infecting Apis cerana cerana workers at seven days post inoculation (dpi) and 10 dpi (NcT1 and NcT2 groups) as well as N. ceranae spores (NcCK group). There were 1411, 604, and 38 DEGs identified in NcCK vs. NcT1, NcCK vs. NcT2, and NcT1 vs. NcT2 comparison groups. Additionally, 10 upregulated genes and nine downregulated ones were shared by above-mentioned comparison groups. GO classification and KEGG pathway analysis suggested that these DEGs were engaged in a number of key functional terms and pathways such as cell part and glycolysis. Further analysis indicated that most of virulence factor-encoding genes were upregulated, while a few were downregulated during the fungal infection. Findings in this current work provide a basis for clarifying the molecular mechanism udnerlying N. ceranae infection and host-microsporidian interaction during bee nosemosis. Apis cerana is the original host for Nosema ceranae, a widespread fungal parasite resulting in honey bee nosemosis, which leads to severe losses to the apiculture industry throughout the world. However, knowledge of N. ceranae infecting eastern honey bees is extremely limited. Currently, the mechanism underlying N. ceranae infection is still largely unknown. Based on our previously gained high-quality transcriptome datasets derived from N. ceranae spores (NcCK group), N. ceranae infecting Apis cerana cerana workers at seven days post inoculation (dpi) and 10 dpi (NcT1 and NcT2 groups), comparative transcriptomic investigation was conducted in this work, with a focus on virulence factor-associated differentially expressed genes (DEGs). Microscopic observation showed that the midguts of A. c. cerana workers were effectively infected after inoculation with clean spores of N. ceranae. In total, 1411, 604, and 38 DEGs were identified from NcCK vs. NcT1, NcCK vs. NcT2, and NcT1 vs. NcT2 comparison groups. Venn analysis showed that 10 upregulated genes and nine downregulated ones were shared by the aforementioned comparison groups. The GO category indicated that these DEGs were involved in a series of functional terms relevant to biological process, cellular component, and molecular function such as metabolic process, cell part, and catalytic activity. Additionally, KEGG pathway analysis suggested that the DEGs were engaged in an array of pathways of great importance such as metabolic pathway, glycolysis, and the biosynthesis of secondary metabolites. Furthermore, expression clustering analysis demonstrated that the majority of genes encoding virulence factors such as ricin B lectins and polar tube proteins displayed apparent upregulation, whereas a few virulence factor-associated genes such as hexokinase gene and 6-phosphofructokinase gene presented downregulation during the fungal infection. Finally, the expression trend of 14 DEGs was confirmed by RT-qPCR, validating the reliability of our transcriptome datasets. These results together demonstrated that an overall alteration of the transcriptome of N. ceranae occurred during the infection of A. c. cerana workers, and most of the virulence factor-related genes were induced to activation to promote the fungal invasion. Our findings not only lay a foundation for clarifying the molecular mechanism underlying N. ceranae infection of eastern honey bee workers and microsporidian–host interaction. [ABSTRACT FROM AUTHOR]

The present study aimed to investigate the pathogenesis of white faeces syndrome (WFS) in Litopenaeus vannamei and its impact on grow-out production. Microsporidian infection clinically causes white gut, loose shell, opaque muscle, jelly-like accumulation in the hepatopancreas and in severe cases the white faeces strands floating on the surface of the ponds. The daily growth rate (DGR) of shrimp in the infected pond (ranged between 0.13 and 0.34 g) was lower than that in the normal pond. The minimum disease prevalence of 4% and a maximum prevalence of 26% were recorded. In the histological study, the hepatopancreas and gut were the most affected organs of shrimps. Hepatopancreatic tubules were sloughing and degenerated where some basophilic inclusions were observed. In the infected midgut, the columnar cells, basement membrane and muscles were severely degraded. The oval-shaped spores of the microsporidian were found to be observed under the examination of a scanning electron microscope, which is confirmed by the transmission electron microscopy. The total length of the matured spores ranged between 1000 and 1300 nm (1130 ± 80 nm). The different maturation phases of microsporidian in infected hepatopancreas were found to be observed under a TEM. The mature spore consisted of exosphore, the outer surface covered with protein layer, and endosphore, the inner layer made up of chitin followed by the plasma membrane. [ABSTRACT FROM AUTHOR]

Abstract Ecological communities are partly structured by indirect interactions, where one species can indirectly affect another by altering its interactions with a third species. In the absence of direct predation, nonconsumptive effects of predators on prey have important implications for subsequent community interactions. To better understand these interactions, we used a Daphnia‐parasite‐predator cue system to evaluate if predation risk affects Daphnia responses to a parasite. We investigated the effects of predator cues on two aspects of host–parasite interactions (susceptibility to infection and infection intensity), and whether or not these effects differed between sexes. Our results show that changes in response to predator cues caused an increase in the prevalence and intensity of parasite infections in female predator‐exposed Daphnia. Importantly, the magnitude of infection risk depended on how long Daphnia were exposed to the cues. Additionally, heavily infected Daphnia that were constantly exposed to cues produced relatively more offspring. While males were ~5× less likely to become infected compared to females, we were unable to detect effects of predator cues on male Daphnia–parasite interactions. In sum, predators, prey, and their parasites can form complex subnetworks in food webs, necessitating a nuanced understanding of how nonconsumptive effects may mediate these interactions.

In insects infections trigger hemocyte-mediated immune reactions including degranulation by exocytosis; however, involvement of mediator enzymes in degranulation process is unknown in insects. We report here that in silkworm Bombyx mori, infection by endoparasitoid Exorista bombycis and microsporidian Nosema bombycis activated granulation in granulocytes and promoted degranulation of accumulated structured granules. During degranulation the mediator lysosomal enzyme β-hexosaminidase showed increased activity and expression of β-hexosaminidase gene was enhanced. The events were confirmed in vitro after incubation of uninfected hemocytes with E. bombycis larval tissue protein. On infection, cytotoxicity marker enzyme lactate dehydrogenase (LDH) was released from the hemocytes illustrating cell toxicity. Strong positive correlation (R2 = 0.71) between LDH activity and β-hexosaminidase released after the infection showed parasitic–protein-induced hemocyte damage and accompanied release of the enzymes. Expression of β-hexosaminidase gene was enhanced in early stages after infection followed by down regulation. The expression showed positive correlation (R2 = 0.705) with hexosaminidase activity pattern. B. mori hexosaminidase showed 98% amino acid similarity with that of B. mandarina showing origin from same ancestral gene; however, 45–60% varied from other lepidopterans showing diversity. The observation signifies the less known association of hexosaminidase in degranulation of hemocytes induced by parasitic infection in B. mori and its divergence in different species. [ABSTRACT FROM AUTHOR]

Apis cerana is the original host for Nosema ceranae, a widespread fungal parasite resulting in honey bee nosemosis, which leads to severe losses to the apiculture industry throughout the world. However, knowledge of N. ceranae infecting eastern honey bees is extremely limited. Currently, the mechanism underlying N. ceranae infection is still largely unknown. Based on our previously gained high-quality transcriptome datasets derived from N. ceranae spores (NcCK group), N. ceranae infecting Apis cerana cerana workers at seven days post inoculation (dpi) and 10 dpi (NcT1 and NcT2 groups), comparative transcriptomic investigation was conducted in this work, with a focus on virulence factor-associated differentially expressed genes (DEGs). Microscopic observation showed that the midguts of A. c. cerana workers were effectively infected after inoculation with clean spores of N. ceranae. In total, 1411, 604, and 38 DEGs were identified from NcCK vs. NcT1, NcCK vs. NcT2, and NcT1 vs. NcT2 comparison groups. Venn analysis showed that 10 upregulated genes and nine downregulated ones were shared by the aforementioned comparison groups. The GO category indicated that these DEGs were involved in a series of functional terms relevant to biological process, cellular component, and molecular function such as metabolic process, cell part, and catalytic activity. Additionally, KEGG pathway analysis suggested that the DEGs were engaged in an array of pathways of great importance such as metabolic pathway, glycolysis, and the biosynthesis of secondary metabolites. Furthermore, expression clustering analysis demonstrated that the majority of genes encoding virulence factors such as ricin B lectins and polar tube proteins displayed apparent upregulation, whereas a few virulence factor-associated genes such as hexokinase gene and 6-phosphofructokinase gene presented downregulation during the fungal infection. Finally, the expression trend of 14 DEGs was confirmed by RT-qPCR, validating the reliability of our transcriptome datasets. These results together demonstrated that an overall alteration of the transcriptome of N. ceranae occurred during the infection of A. c. cerana workers, and most of the virulence factor-related genes were induced to activation to promote the fungal invasion. Our findings not only lay a foundation for clarifying the molecular mechanism underlying N. ceranae infection of eastern honey bee workers and microsporidian–host interaction.

Ecological communities are partly structured by indirect interactions, where one species can indirectly affect another by altering its interactions with a third species. In the absence of direct predation, nonconsumptive effects of predators on prey have important implications for subsequent community interactions. To better understand these interactions, we used a Daphnia‐parasite‐predator cue system to evaluate if predation risk affects Daphnia responses to a parasite. We investigated the effects of predator cues on two aspects of host–parasite interactions (susceptibility to infection and infection intensity), and whether or not these effects differed between sexes. Our results show that changes in response to predator cues caused an increase in the prevalence and intensity of parasite infections in female predator‐exposed Daphnia. Importantly, the magnitude of infection risk depended on how long Daphnia were exposed to the cues. Additionally, heavily infected Daphnia that were constantly exposed to cues produced relatively more offspring. While males were ~5× less likely to become infected compared to females, we were unable to detect effects of predator cues on male Daphnia–parasite interactions. In sum, predators, prey, and their parasites can form complex subnetworks in food webs, necessitating a nuanced understanding of how nonconsumptive effects may mediate these interactions. [ABSTRACT FROM AUTHOR]

Nosema ceranae is a pathogen of Apis mellifera, which seems to have jumped from its original host Asiatic honey bee Apis ceranae. Nosemosis which affects the honey bee Apis mellifera is caused by two parasitic fungi described as etiologic agents of the disease. Nosema apis was the only microsporidian infection identified in A. mellifera until N. ceranae in Taiwan and Europe. Nosema spp. positive samples of adult worker bees from the Venezuelean state of Lara were determined through light microscopy of spores. Samples were then tested to determine Nosema species (N.apis/N.ceranae) using previously reported PCR primers for the 16S rRNA gene. A multiplex PCR assay was used to differentiate both N. apis and N. ceranae species. Only N. ceranae was found in the analyzed samples and the percentage of infected foragers fluctuated between 18% and 60%.

Background: Opportunistic parasites have been identified as human pathogens, especially in immunodeficient patients. Microsporidian and coccidian infections cause chronic diarrhea as common clinical manifestation in HIV positive patients. In this study, the frequency of opportunistic infections, including microsporidian and coccidian infections, was evaluated in HIV/AIDS patients from Tehran and phylogenic analysis was performed for E. bieneusi isolates from these patients. Methods: One hundred and two stool samples were collected from confirmed HIV/AIDS patients, referred to Consult Center of Behavior Diseases, West Health Center, Iran University of Medical Sciences in Tehran, Iran. The samples were transferred to Research Center of Pediatric Infectious Diseases, Institute of Immunology and Infectious Diseases, Iran University of Medical Sciences from Jan 2016 to Dec 2016. After conventional formalin-ether concentration, aniline blue staining method and acid-fast staining technique were used for detection of microsporidian spores and Cyclospora oocysts. DNA was extracted and nested PCR was performed. Results: Two (1.96%) cases were found to be positive for intestinal microsporidia infection using aniline blue staining method and were confirmed as E. bieneusi by nested PCR. One patient was found with Cyclospora cayetanensis infection by acid-fast staining method and PCR. Giardia lamblia and Blastocystis hominis were detected as non-opportunistic parasites in 1/102 (0.98%) and 2/102 (1.96%) of the HIV positive patients, respectively. Conclusion: With respect to the use of antiretroviral therapy (ART) in HIV positive patients, we found a low frequency of infection.

Two male juvenile central bearded dragons (Pogona vitticeps) were submitted for postmortem examination after dying at their respective homes. Dragon 1 had marked hemopericardium with restrictive epicarditis. The inner aspect of the distended pericardial sac was lined by a fibrinoheterophilic membrane. In addition, granulomas abutted the testes. Dragon 2 had acute hemopericardium and granulomatous arteritis of the great vessels exiting the heart. Histologically, both animals had granulomatous arteritis of the large arteries with intrahistiocytic gram-positive, slightly elongated, up to 2 μm long microorganisms that contained a vacuole. These microorganisms were also present in the paratesticular granulomas. On transmission electron microscopy, the microorganisms were identified as microsporidians given the presence of exospore, endospore, vacuole, nucleus, and a filament with 4–6 coils. The microsporidia were identified as Encephalitozoon pogonae based on sequencing of the internal transcribed spacer 1 of the ribosomal RNA genes. Microsporidia are agents of disease in bearded dragons. Intrapericardial arteritis of large arteries with hemopericardium or restrictive epicarditis is a fatal manifestation of this infection. [ABSTRACT FROM AUTHOR]

Abstract ATP-binding cassette (ABC) transporters comprise the largest family of transmembrane proteins and are found in all domains of life. The ABCs are involved in a variety of biological processes and as exporters play important roles in multidrug resistance. However, the ABC transporters have not been addressed in microsporidia, which are a very large group of obligate intracellular parasites that can infect nearly all animals, including humans. Here, a total of 234 ABC transporters were identified from 18 microsporidian genomes and classified into five subfamilies, including 74 ABCBs, 2 ABCCs, 18 ABCEs, 15 ABCFs, 102 ABCGs and 23 uncategorized members. Two subfamilies, ABCA and ABCD, are found in most organisms, but lost in microsporidia. Phylogenetic analysis indicated that microsporidian ABCB and ABCG subfamilies expanded by recent gene duplications, which resulted in the two largest subfamilies in microsporidia. Functional analysis via qRT-PCR and Western blotting revealed that NoboABCG1.1 , an ABCG member of Nosema bombycis , is expressed in mature spores and up-regulated from 1 dpi to 6 dpi in infected silkworm midgut. IFA and IEM analysis showed that NoboABCG1.1 is localized on the plasma membrane of the sporoplasm, meront and mature spore. The propagation of N. bombycis was significantly inhibited after the RNAi of NoboABCG1.1 expression, indicating that NoboABCG1.1 is important to the pathogen proliferation. In conclusion, our study uncovered that the ABCs evolved during microsporidia adaption to intracellular parasitism and play important roles in the pathogen development. Highlights • 234 ABC genes are identified from 18 microsporidian genomes • Microsporidian ABC genes are assigned to five subfamilies: ABCB, ABCC, ABCE, ABCF, ABCG • Gene expansions of ABCB and ABCG subfamily were caused by recent gene duplications • NoboABCG1.1 is localized on the plasma membrane of sporoplasm, meront and mature spore in Nosema bombycis. • NoboABCG1.1 plays important role in substrate transportation during spore propagation. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Southern Agriculture is the property of Journal of Southern Agriculture and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Gill disease (GD) in farmed Atlantic salmon may be due to the impact of several agents that may interact. We followed the infections of four gill disease-associated agents during the first year of production in six farms; examining the correlation between their densities in the gills. These farms were located in an area with high risk of developing gill disease, and three of the farms were diagnosed with GD in the autumn. In the present study we show temporal changes in pathogens in salmon from all 6 farms, revealing recurring infection patterns by Desmozoon lepeophtherii and Candidatus Branchiomonas cysticola (C. B. cysticola), and large variation without an apparent pattern in densities of Ichthyobodo salmonis . Infections with the microsporidian D. lepeophtherii show a clear seasonal pattern, and high densities are associated with GD. Ca. B. cysticola appears not to be directly connected to the disease, albeit densities of this bacterium may coincide with high D. lepeophtherii densities. Amoebae ( Paramoeba spp.) were only sporadically detected with low densities. Salmon with low condition had elevated densities of D. lepeophtherii and Ichthyobodo spp., while no such pattern was seen for the other pathogens. Challenge studies are needed to substantiate the role of D. lepeophtherii in GD, but realistic challenge model (i.e. bath) has so far not been developed. Based on the present molecular screening, we suggest that D. lepeophtherii infections both may be responsible for GD, and cause runting in farmed salmon populations. Statement of relevance This is an epizootiological study of Atlantic salmon and gill diseases. There is much known about pathogen in connection with GD outbreak, less is known about the occurrence of potential pathogen in healthy farmed salmon or how such infections develop over time. High densities of the microsporidian parasite Paranucleospora theridion in the gills coincide with gill disease, making P. theridion a possible primary source to this condition. Densities of Paranucleospora theridion , Candidatus Branchiomonas cysticola and Ichthyobodo salmonis may be correlated in farmed salmon populations with gill disease. P.theridion and I. salmonis densities are elevated in Atlantic salmon with low condition (‘runts’). [ABSTRACT FROM AUTHOR]

Honey bees ( Apis mellifera ) are critical agricultural pollinators as well as model organisms for research on development, behavior, memory, and learning. The parasite Nosema ceranae , a common cause of honey bee colony collapse, has developed resistance to small-molecule therapeutics. An alternative long-term strategy to combat Nosema infection is therefore urgently needed, with synthetic biology offering a potential solution. Honey bees harbor specialized bacterial gut symbionts that are transmitted within hives. Previously, these have been engineered to inhibit ectoparasitic mites by expressing double-stranded RNA (dsRNA) targeting essential mite genes, via activation of the mite RNA interference (RNAi) pathway. In this study, we engineered a honey bee gut symbiont to express dsRNA targeting essential genes of N. ceranae via the parasite's own RNAi machinery. The engineered symbiont sharply reduced Nosema proliferation and improved bee survival following the parasite challenge. This protection was observed in both newly emerged and older forager bees. Furthermore, engineered symbionts were transmitted among cohoused bees, suggesting that introducing engineered symbionts to hives could result in colony-level protection.

[Display omitted] • Most relevant findings from 374 Tawera elliptica clams examined were intracellular microcolonies of bacteria (IMC) in digestive gland and intestine, and an intraoocytic microsporidian. • Scanning electron images of histological sections of IMC and the Steinhausia- like intraoocytic microsporidian. • No OIE listed pathogens detected. • No disease risks for the cultivation of this clam at actual prevalences and infection intensities. Tawera elliptica (commonly known as "Almeja Juliana", is a venerid clam that inhabits sandy bottoms and is distributed from Valparaíso on the Pacific coast up to the Mar del Plata area along the Atlantic coast. Harvests of this clam have declined substantially over the last decade. Therefore, an analysis of common parasites and pathological conditions of this clam was undertaken along with histopathology. Monthly samples were prepared for routine histology for examination under light and electron microscopy. T. elliptica has a sex ratio of 1:1 and the relationship between the shell length and the wet tissue weight is not significantly different between females and males. The maximum values for de condition index and meat yield were found during the austral winter. The following parasites (and their overall prevalence) were detected: intracellular microcolonies of bacteria in digestive gland (22.9%), intestinal epithelium (9.3%) and gills (3.17%), an unidentified cyst in gills (59,3%), a Steinhausia -like intraoocytic microsporidian (5.2%), Gregarine spores (41.3%), ciliated protozoa (16.7%), two metazoa, a Paravortex like flatworm (4.3%), and a digenean trematode (8%). The monthly mean intensity of the most relevant parasites was between 2.3 and 35.6 for digestive gland intracellular microcolonies of bacteria (IMC), 0–5.1 for intestinal epithelium IMC, 0–2 for branchial IMC and 0 – 48 for intraoocytic microsporidium. The prevalence and the infection intensity were low-to very low, and no World Organisation for Animal Health OIE listed parasite was detected. It is concluded that this is a healthy clam, and no disease risks for the cultivation are visualized at present. However, IMC at high prevalence and intensities of infection could be potentially impactful, and the intraoocytic microsporidian could jeopardize reproduction if present in high intensities of infection. [ABSTRACT FROM AUTHOR]

[Display omitted] • EHP spores are dormant, resilient, and infective and can survive outside the host. • The germination of spores indicates the viability and infectivity of EHP. • The ions generated during radiolysis under SEM induce EHP spore germination. • This study is the first to demonstrate microsporidian spore germination under SEM. Enterocytozoon hepatopenaei (EHP), is an emerging microsporidian pathogen responsible for hepatopancreatic microsporidiasis (HPM) in shrimps and is associated with severe growth retardation. The disease causes economic losses in shrimp aquaculture. In this study, EHP spore germination was induced and demonstrated with a scanning electron microscope (SEM). The ions (cations and anions) generated by high-energy electrons during frozen water radiolysis in the SEM specimen chamber induce EHP spore germination. This study is the first to demonstrate the induction of a microsporidian spore germination by ions generated under SEM. This study will enhance our understanding of EHP biology, life cycle and lead to the development of prophylactics and therapeutics for EHP control. Also, this method will help standardize the study of germination in other microsporidians. [ABSTRACT FROM AUTHOR]

This paper utilises histological, ultrastructure and molecular phylogenetic data to describe a novel genus and species ( Paradoxium irvingi n.gen., n.sp.) within clade 5 of the phylum Microsporidia. The parasite infects the musculature of the pink shrimp Pandalus montagui captured from United Kingdom waters. The novel microsporidium is morphologically and phylogenetically dissimilar to its nearest phylogenetic branch relative Thelohania butleri infecting the sister shrimp taxon Pandalus jordani . Furthermore, it is morphologically distinct from the type species of the genus Thelohania , Thelohania giardi infecting European brown shrimp Crangon crangon . Since phylogenetic data pertaining to type T. giardi is not currently available, our discovery places some doubt on the likelihood that T. butleri represents the proposed surrogate for the type taxon. Further it demonstrates potential for significant morphological plasticity in this clade of muscle-infecting microsporidians of crustaceans which contains the genera Myospora, Cucumispora, Thelohania, and now Paradoxium. Since it cannot be stated with certainty that T. butleri (or other taxa within the clade) represent true close relatives of T. giardi, clarity on this issue will only occur with re-discovery and genotyping of type T. giardi infecting C. crangon from European waters. [ABSTRACT FROM AUTHOR]

Feminisation of amphipod crustaceans is associated with the presence of at least three microsporidian parasites and one paramyxean parasite, suggesting that the ability to feminise has evolved multiple times in parasites of amphipods. Co-infection by a paramyxean with one of the putative microsporidian feminisers, Dictyocoela duebenum , has inspired the alternative hypothesis that all feminisation of amphipods is caused by paramyxea and that all microsporidian associations with feminisation are due to co-infection with paramyxea ( Short et al., 2012 ). In a population of the amphipod Gammarus duebeni , breeding experiments demonstrate that the microsporidia D. duebenum and Nosema granulosis are associated with feminisation in the absence of paramyxea. Co-infection of the two microsporidia is no more frequent than expected at random and each parasite is associated with feminisation in the absence of the other. These findings support the original hypothesis that the ability to feminise amphipods has evolved in microsporidia on multiple occasions. Additionally, the occurrence of a non-feminising strain of D. duebenum in Gammarus pulex suggests that different strains vary in their feminising ability, even within microsporidian species. The presence or absence of feminising ability in a particular microsporidian strain should not therefore be generalised to the species as a whole. [ABSTRACT FROM AUTHOR]

Copyright of Archivos de Medicina Veterinaria is the property of Universidad Austral de Chile, Facultad de Ciencias Veterinarias and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A new microsporidium was isolated from Histia rhodope Cramer (Lepidoptera, Zygaenidae), a pest of Bischofia javanica BL. in China. The morphology and molecular systematic of this novel microsporidian isolate had been described in this study. The spores were long oval and measured 3.1 × 1.9 μm on fresh smears. Ultrastructure of the spores was characteristic for the genus Nosema: 14-15 polar filament coils, posterior vacuole, and a diplokaryon. The sequenced rRNA gene of this isolate is 4309 bp long. The organization of the rRNA gene is 5′-LSU rRNA-ITS-SSU rRNA-IGS-5S-3′, which is similar to that of other Nosema species (such as Nosema bombycis). Phylogenetic analysis based on LSU rRNA gene and SSU rRNA gene both revealed that this novel micorsporidian which isolated from H. rhodope had close relationship to the genus Nosema. Additionally, this isolate can also cause systemic infection of Bombyx mori. So, we should pay attention not only to N. bombycis, but also to other microsporidian (such as Nosema sp. HR) in sericulture in the future. [ABSTRACT FROM AUTHOR]

Two pathogens co-infecting a common host can either interact positively (facilitation), negatively (competition) or act independently. A correlative study has suggested that two pathogens of the honey bee, Nosema ceranae and Deformed wing virus (DWV), interact negatively within a host (Costa et al., 2011). To test this hypothesis, we sequentially co-infected honey bees with these pathogens in a reciprocally crossed experimental design. Prior establishment in the host ventriculus by N. ceranae inhibited DWV while prior infection by DWV did not impact N. ceranae , highlighting an asymmetry in the competitive interaction between these emerging pathogens. [ABSTRACT FROM AUTHOR]

The substantial harm to ecosystems resulted from applying chemical pesticides has attracted the interest to biopesticides for controlling grasshoppers. Paranosema locustae was applied for controlling grasshoppers at Qilian rangeland in 2000. Population of the most abundant grasshopper, Myrmeleotettix palpalis, declined from 13.04/m² in the year of treatment to 6.96/m2 and 1.14/m² by the first and second years after treatment. Population of this species fluctuated regularly in years 2-5 post-treatment with densities varying from 1.14 to 3.52/m², while it increased after the fifth year and peaked (9.09/m²) by the seventh year. However, there were large increases in grasshopper populations in the treated area with chemical insecticide to 35.3/m² after the fifth year leading to re-treatment with a chemical insecticide. In the year of treatment, 51.64-65.39% of surviving grasshoppers of different species were found infected. Disease prevalence was 66.11-68.36% after the first year for these primary grasshopper species, but gradually decreased by approximately 20- 30% by the 6th year where it remained for the rest of the period, thus indicating that the pathogen remained in grasshopper populations for successive years. Infection prevalence of grasshoppers and natural enemies may be vital in keeping densities below economic injury level (EIL) for more than nine years after treatment with P. locustae. [ABSTRACT FROM AUTHOR]

As a new generation of high-throughput sequencing technology, PacBio Iso-Seq technology (Iso-Seq) provides a better alternative sequencing method for the acquisition of full-length unigenes. In this study, a total of 22.27 gigabyte (Gb) subread bases and 128,614 non-redundant unigenes (mean length: 2,324 bp) were obtained from six main tissues of Eriocheir sinensis including the heart, nerve, intestine, muscle, gills and hepatopancreas. In addition, 74,732 unigenes were mapped to at least one of the following databases: Non-Redundant Protein Sequence Database (NR), Gene Ontology (GO), Kyoto Encyclopaedia of Genes and Genomes (KEGG), KEGG Orthology (KO) and Protein family (Pfam). In addition, 6696 transcription factors (TFs), 28,458 long non-coding RNAs (lncRNAs) and 94,230 mRNA-miRNA pairs were identified. Hepatospora eriocheir is the primary pathogen of E. sinensis and can cause hepatopancreatic necrosis disease (HPND); the intestine is the main target tissue. Here, we attempted to identify the key genes related to H. eriocheir infection in the intestines of E. sinensis . By combining Iso-Seq and Illumina RNA-seq analysis, we identified a total of 12,708 differentially expressed unigenes (DEUs; 6,696 upregulated and 6,012 downregulated) in the crab intestine following infection with H. eriocheir . Based on the biological analysis of these DEUs, several key processes were identified, including energy metabolism-related pathways, cell apoptosis and innate immune-related pathways. Twelve selected genes from these DEUs were subsequently verified by quantitative real-time PCR (qRT-PCR) analysis. Our findings enhance our understanding of the E. sinensis transcriptome and the specific association between E. sinensis and H. eriocheir infection., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Hou, Wang, Zhu, Ning, Bi, Du, Kong, Gu and Meng.)

Standing genetic variation is the predominant source acted on by selection. Organisms with high genetic diversity generally show faster responses toward environmental change. Nosema ceranae is a microsporidian parasite of honey bees, infecting midgut epithelial cells. High genetic diversity has been found in this parasite, but the mechanism for the parasite to maintain this diversity remains unclear. This study involved continuous inoculation of N. ceranae to honey bees. We found that the parasites slowly increased genetic diversity over three continuous inoculations. The number of lost single nucleotide variants (SNVs) was balanced with novel SNVs, which were mainly embedded in coding regions. Classic allele frequency oscillation was found at the regional level along the genome, and the associated genes were enriched in apoptosis regulation and ATP binding. The ratio of synonymous and non-synonymous substitution suggests a purifying selection, and our results provide novel insights into the evolutionary dynamics in microsporidian parasites., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Wei, Zheng, Evans and Huang.)

Asian honey bee Apis cerana is the original host for Nosema ceranae , a unicellular fungal parasite that causes bee nosemosis throughout the world. Currently, interaction between A. cerana and N. ceranae is largely unknown. Our group previously prepared A. c. cerana workers' midguts at 7 days post inoculation (dpi) and 10 dpi with N. ceranae spores as well as corresponding un-inoculated workers' midguts, followed by cDNA library construction and a combination of RNAs-seq and small RNA-seq. Meanwhile, we previously prepared clean spores of N. ceranae , which were then subjected to cDNA library construction and deep sequencing. Here, based on the gained high-quality transcriptome datasets, N. ceranae differentially expressed mRNAs (DEmiRNAs) targeted by host DEmiRNAs, and A. c. cerana DEmRNAs targeted by microsporidian DEmiRNAs were deeply investigated, with a focus on targets involved in N. ceranae glycolysis/glyconeogenesis as well as virulence factors, and A. c. cerana energy metabolism and immune response. In A. c. cerana worker's midguts at 7 (10) dpi (days post inoculation), eight (seven) up-regulated and six (two) down-regulated miRNAs were observed to target 97 (44) down-regulated and 60 (15) up-regulated N. ceranae mRNAs, respectively. Additionally, two up-regulated miRNAs (miR-60-y and miR-676-y) in host midgut at 7 dpi could target genes engaged in N. ceranae spore wall protein and glycolysis/gluconeogenesis, indicating potential host miRNA-mediated regulation of microsporidian virulence factor and energy metabolism. Meanwhile, in N. ceranae at 7 (10) dpi, 121 (110) up-regulated and 112 (104) down-regulated miRNAs were found to, respectively, target 343 (247) down-regulated and 138 (110) down-regulated mRNAs in A. c. cerana workers' midguts. These targets in host were relevant to several crucial cellular and humoral immune pathways, such as phagasome, endocytosis, lysosomes, regulation of autophagy, and Jak-STAT signaling pathway, indicative of the involvement of N. ceranae DEmiRNAs in regulating these cellular and humoral immune pathways. In addition, N. ceranae miR-21-x was up-regulated at 7 dpi and had a target relative to oxidative phosphorylation, suggesting that miR-21-x may be used as a weapon to modulate this pivotal energy metabolism pathway. Furthermore, potential targeting relationships between two pairs of host DEmiRNAs-microsporidian DEmRNAs and two pairs of microsporidian DEmiRNAs-host DEmRNAs were validated using RT-qPCR. Our findings not only lay a foundation for exploring the molecular mechanism underlying cross-kingdom regulation between A. c. cerana workers and N. ceranae , but also offer valuable insights into Asian honey bee-microsporidian interaction., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Fan, Zhang, Zhang, Zhang, Long, Wu, Zhang, Zhu, Chen and Guo.)

Highlights: [•] Nosema ceranae was found in Apis mellifera from Brazil 34years before the present. [•] N. ceranae has infected honey bees for longer than previously assumed. [•] Historical samples can help to understand the spread of N. ceranae. [Copyright &y& Elsevier]

Aims Enterocytozoon hepatopenaei is an emerging microsporidian parasite that has been linked to recent losses caused by white faeces syndrome ( WFS) in cultivated giant or black tiger shrimp Penaeus ( Penaeus) monodon and whiteleg shrimp Penaeus ( Litopenaeus) vannamei in Asia. To more accurately assess its impact on shrimp production and to determine reservoir carriers for control measures, our objective was to establish a loop-mediated isothermal amplification ( LAMP) assay combined with colorimetric nanogold ( Au NP) for rapid, sensitive and inexpensive detection of this parasite. Methods and Results A set of six specific primers was designed to successfully detect the SSU rRNA gene of E. hepatopenaei by a LAMP reaction of 45 min at 65°C combined with visual detection of the amplification product via hybridization at 65°C for 5 min with a ss DNA-labelled nanogold probe, followed by salt-induced Au NP aggregation (total assay time, approximately 50 min). This method gave similar results to LAMP followed by electrophoresis or spectrophotometric detection, and it was more sensitive (0·02 fg total DNA) than a conventional nested PCR (0·2 fg total DNA). The new method gave negative results with shrimp DNA templates extracted from diseased shrimp containing other pathogens, indicating that the LAMP- Au NP assay was specific for E. hepatopenaei. Conclusions Without sacrificing sensitivity or specificity, the new LAMP- Au NP assay significantly reduced the time, ease and cost for molecular detection of E. hepatopenaei in shrimp. Significance and Impact of the study The new method employs simple, inexpensive equipment and involves simple steps making it applicable for small field laboratories. Wider application of the method to screen broodstock before use in a hatchery, to screen postlarvae before stocking shrimp ponds, to test for natural carriers and to monitor shrimp in rearing ponds would help to assess and reduce the negative impact of this parasite in shrimp farming. [ABSTRACT FROM AUTHOR]

Grouping behaviours ( e.g. schooling, shoaling and swarming) are commonly explicated through adaptive hypotheses such as protection against predation, access to mates or improved foraging. However, the hypothesis that aggregation can result from manipulation by parasites to increase their transmission has never been demonstrated. We investigated this hypothesis using natural populations of two crustacean hosts ( Artemia franciscana and Artemia parthenogenetica) infected with one cestode and two microsporidian parasites. We found that swarming propensity increased in cestode-infected hosts and that red colour intensity was higher in swarming compared with non-swarming infected hosts. These effects likely result in increased cestode transmission to its final avian host. Furthermore, we found that microsporidian-infected hosts had both increased swarming propensity and surfacing behaviour. Finally, we demonstrated using experimental infections that these concurrent manipulations result in increased spore transmission to new hosts. Hence, this study suggests that parasites can play a prominent role in host grouping behaviours. [ABSTRACT FROM AUTHOR]

Background: Microsporidian Nosema bombycis has received much attention because the pébrine disease of domesticated silkworms results in great economic losses in the silkworm industry. So far, no effective treatment could be found for pébrine. Compared to other known Nosema parasites, N. bombycis can unusually parasitize a broad range of hosts. To gain some insights into the underlying genetic mechanism of pathological ability and host range expansion in this parasite, a comparative genomic approach is conducted. The genome of two Nosema parasites, N. bombycis and N. antheraeae (an obligatory parasite to undomesticated silkworms Antheraea pernyi), were sequenced and compared with their distantly related species, N. ceranae (an obligatory parasite to honey bees). Results: Our comparative genomics analysis show that the N. bombycis genome has greatly expanded due to the following three molecular mechanisms: 1) the proliferation of host-derived transposable elements, 2) the acquisition of many horizontally transferred genes from bacteria, and 3) the production of abundnant gene duplications. To our knowledge, duplicated genes derived not only from small-scale events (e.g., tandem duplications) but also from largescale events (e.g., segmental duplications) have never been seen so abundant in any reported microsporidia genomes. Our relative dating analysis further indicated that these duplication events have arisen recently over very short evolutionary time. Furthermore, several duplicated genes involving in the cytotoxic metabolic pathway were found to undergo positive selection, suggestive of the role of duplicated genes on the adaptive evolution of pathogenic ability. Conclusions: Genome expansion is rarely considered as the evolutionary outcome acting on those highly reduced and compact parasitic microsporidian genomes. This study, for the first time, demonstrates that the parasitic genomes can expand, instead of shrink, through several common molecular mechanisms such as gene duplication, horizontal gene transfer, and transposable element expansion. We also showed that the duplicated genes can serve as raw materials for evolutionary innovations possibly contributing to the increase of pathologenic ability. Based on our research, we propose that duplicated genes of N. bombycis should be treated as primary targets for treatment designs against pébrine. [ABSTRACT FROM AUTHOR]

Microsporidia, an unusual group of unicellular parasites related to fungi, possess a highly reduced mitochondrion known as the mitosome. Since mitosomes lack an organellar genome, their proteins must be translated in the cytosol before being imported into the mitosome via translocases. We have identified a Tom40 gene ( NbTom40), the main component of the translocase of the outer mitochondrial membrane, in the genome of the microsporidian Nosema bombycis. NbTom40 is reduced in size, but it is predicted to form a β-barrel structure composed of 19 β-strands. Phylogenetic analysis confirms that NbTom40 forms a clade with Tom40 sequences from other species, distinct from a related clade of voltage-dependent anion channels ( VDACs). The NbTom40 contains a β-signal motif that the polar residue is substituted by glycine. Furthermore, we show that expression of NbTom40, as a GFP fusion protein within yeast cells, directs GFP to mitochondria of yeast. These findings suggest that NbTom40 may serve as an import channel of the microsporidian mitosome and facilitate protein translocation into this organelle. [ABSTRACT FROM AUTHOR]

Abstract: Honey bee colonies (Apis mellifera) have been selected for low level of Nosema in Denmark over decades and Nosema is now rarely found in bee colonies from these breeding lines. We compared the immune response of a selected and an unselected honey bee lineage, taking advantage of the haploid males to study its potential impact on the tolerance toward Nosema ceranae, a novel introduced microsporidian pathogen. After artificial infections of the N. ceranae spores, the lineage selected for Nosema tolerance showed a higher N. ceranae spore load, a lower mortality and an up-regulated immune response. The differences in the response of the innate immune system between the selected and unselected lineage were strongest at day six post infection. In particular genes of the Toll pathway were up-regulated in the selected strain, probably is the main immune pathway involved in N. ceranae infection response. After decades of selective breeding for Nosema tolerance in the Danish strain, it appears these bees are tolerant to N. ceranae infections. [Copyright &y& Elsevier]

Parasitism is emerging as one of the forces determining the outcome of biological invasions. Using field survey and laboratory experiments, we investigate parasitism as one of the factors mediating the interactions among invasive and native amphipods. An extensive survey (100 sites) of a small British island, revealed the native Gammarus duebeni celticus to be parasitised by the muscle wasting microsporidian Pleistophora mulleri and the acanthocephalan duck parasite Polymorphus minutus, the introduced European Gammarus pulex only by P. minutus and the North American Crangonyx pseudogracilis by neither. While Gammarus spp. were widespread in rivers (one or both species present in 64% of sites), C. pseudogracilis had a restricted distribution (7% of sites) and always co-occurred with Gammarus spp. In contrast, Gammarus spp. were absent from all pond/reservoir sites, with C. pseudogracilis present in over 90%. While the negative association of C. pseudogracilis with Gammarus spp. undoubtedly results from factors such as physico-chemical tolerance and predation as C. pseudogracilis can be heavily predated by Gammarus spp., it was notable that C. pseudogracilis co-occurred with Gammarus spp. more frequently when the latter were parasitised. Laboratory experiments clearly showed that predation on C. pseudogracilis was greatly diminished when G. d. celticus was parasitised by P. mulleri and G. pulex by P. minutus. Our study provides evidence that parasitism, by mediating a key interspecific interaction, is one of an array of interacting factors that may have a role in driving patterns of exclusion and co-existence in natives and invaders. [ABSTRACT FROM AUTHOR]