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Snow-ice microbes, which adapted to harsh conditions such as low temperature and high dose of UV, inhabit the cryospheric environments. They cause unique phenomena represented by colored snow and ice occurring with blooms of snow and glacier ice algae, and cryoconite holes formed by filamentous cyanobacteria with inorganic matter. These phenomena also darken glacial surface and have a significant effect on the albedo of snow and ice. It is important to understand factors controlling the abundance of all microbes including consumers of algae and cyanobacteria (tardigrades and rotifers) for evaluating the collective influence of biological communities on albedo (biological albedo reduction: BAR). However, most studies have focused only on each taxon (algae, cyanobacteria, fungi or heterotrophic bacteria), and there is a lack of information on whole microbial communities. In this study, we aimed to describe spatiotemporal changes of microbial communities, and discuss the process of their growth and the factors determining their distribution. The fieldworks were carried out from June to September of 2022 on Gulkana Glacier in the Alaska Range, Alaska. Three different types of samples (snow, bare-ice, cryoconite) were collected spatially at maximum 51 points across the glacier. Microscopic observation and analysis of Chlorophyll a concentration, which is a proxy for the total abundance of snow and glacier ice algae, revealed that the algae were most abundant around the snow line and that their maximum occurred in the end of July (1.0 × 103 μg/m2) and in the middle of August (7.8 × 103 μg/m2) on the snow and ice surfaces, respectively. Their distribution in the ice area showed a similar spatial pattern throughout the season, higher abundance in the upper right side and lower in the left side. Consumers of algae (tardigrades and rotifers) were found only in the upper parts of the glacier. These results suggest that each microbial species on the glacier have different distribution and that their growth is associated with local characteristics such as microtopography of the glacier surfaces. In this presentation, we will show more data of spatial distribution of chemical composition, total impurities, and concentration of each microbe in all three surface types and discuss the factors of their growth and distribution.

Glacier retreat due to the warming climate is remarkable all over the world. In addition to climate warming, the “biological albedo reduction”, which the pigmented algae reduce the albedo of the glacier, enhances ice melting. Therefore, the spatial distribution of those algae is important for the glacier's mass balance. Although the altitude result in the air temperature and the duration of snow cover is recognized as the factor to affect the spatial distribution, the distribution pattern is more heterogeneous in the same altitude area. To understand the heterogeneity of snow algae and associating microbes and their effects on the glacier albedo, both eukaryotic and prokaryotic communities were analyzed using an amplicon sequencing approach in the dense coverage of the ablation area of a single glacier (total 54 sites over Gulkana Glacier, AK, USA). Furthermore, microbial diversities were analyzed with environmental factors such as carbon contents and nutrients. As a result, we found the green algae amplicon sequence variants (ASVs) closely related to the pigmented algae, Sanguina nivaloides, and Chlainomonas sp. from the surface ice and cryoconite and will show the spatial variation of microbial community structures and diversities and the relationship between the environmental factors.

Pancreatic ductal adenocarcinoma (PDA) is a fatal cancer for which even unfavorable clinicopathological factors occasionally fail to preclude long-term survival. We sought to establish a scoring system that utilizes measurable pre-intervention factors for predicting survival following surgical resection.We retrospectively analyzed 34 patients who died from short-term recurrences and 32 long-term survivors among 310 consecutively resected patients with PDA. A logistic regression model was used to define factors related to clinical parameters, molecular profiles of 18 pancreatic cancer-associated genes, and aberrant expression of major tumor suppressors.Carbohydrate antigen 19-9 (CA19-9) had the best ability to classify patients with short-term recurrence and long-term survivors [odds ratio 21.04, 95% confidence interval (CI) 4.612-96.019], followed by SMAD4 and TP53 mutation scoring (odds ratio 41.322, 95% CI 3.156-541.035). Missense TP53 mutations were strongly associated with the nuclear expression of p53, whereas truncating mutations were associated with the absence of nuclear p53. The former subset was associated with a worse prognosis. The combination of aberrant SMAD4 and mutation types of TP53 exhibited a better resolution for distinguishing patients with short-term recurrences from long-term survivors (compared with the assessment of the number of mutated KRAS, CDKN2A, TP53, and SMAD4 genes). Calibration of mutation scores combined with CA19-9 in a logistic regression model setting demonstrated a practical effect in classifying long survivors and patients with early recurrence (c-statistic = 0.876).Genetic information, i.e., TP53 mutation types and SMAD4 abnormalities, combined with CA19-9, will be a valuable tool for improving surgical strategies for pancreatic cancer.

Simple Summary Extrahepatic cholangiocarcinoma (EHCC) is an aggressive tumor. The five-year survival rate for patients who undergo surgical resection is only 20-40% due to recurrences. Therefore, elucidating the molecular mechanisms underlying invasion and metastasis in EHCC is crucial for developing adjuvant therapy. The epithelial-mesenchymal transition (EMT) contributes to the metastatic cascade in various tumors. C-C chemokine receptor 7 (CCR7) interacts with its ligand, chemokine (C-C motif) ligand 19 (CCL19), to promote EMT. The association between CCR7 expression and clinicopathological features and EMT status was examined via the immunohistochemical staining of tumor sections from 181 patients with perihilar cholangiocarcinoma. This association was then investigated in two EHCC cell lines. CCR7 mediates cell invasion and migration in EHCC by inducing EMT, which was abrogated by a CCR7 antagonist. CCR7 may be a potential target for adjuvant therapy in EHCC. The epithelial-mesenchymal transition (EMT) contributes to the metastatic cascade in various tumors. C-C chemokine receptor 7 (CCR7) interacts with its ligand, chemokine (C-C motif) ligand 19 (CCL19), to promote EMT. However, the association between EMT and CCR7 in extrahepatic cholangiocarcinoma (EHCC) remains unknown. This study aimed to elucidate the prognostic impact of CCR7 expression and its association with clinicopathological features and EMT in EHCC. The association between CCR7 expression and clinicopathological features and EMT status was examined via the immunohistochemical staining of tumor sections from 181 patients with perihilar cholangiocarcinoma. This association was then investigated in TFK-1 and EGI-1 EHCC cell lines. High-grade CCR7 expression was significantly associated with a large number of tumor buds, low E-cadherin expression, and poor overall survival. TFK-1 showed CCR7 expression, and Western blotting revealed E-cadherin downregulation and vimentin upregulation in response to CCL19 treatment. The wound healing and Transwell invasion assays revealed that the activation of CCR7 by CCL19 enhanced the migration and invasion of TFK-1 cells, which were abrogated by a CCR7 antagonist. These results suggest that a high CCR7 expression is associated with an adverse postoperative prognosis via EMT induction and that CCR7 may be a potential target for adjuvant therapy in EHCC.

In the last 10 yr, the International Atomic Energy Agency (IAEA) revised its safety standards for site evaluations of nuclear installations in response to emerging fault displacement hazard evaluation practices developed in Member States. New amendments in the revised safety guidance (DS507) explicitly recommend fault displacement hazard assessment, including separate approaches for candidate new sites versus existing sites. If there is insufficient basis to conclusively determine that a fault is not capable of surface displacement at an existing site, then a probabilistic fault displacement hazard analysis (PFDHA) is recommended to better characterize the hazard. This new recommendation has generated the need for the IAEA to provide its Member States with guidance on performing PFDHA, including its formulation and implementation. This article provides an overview of current PFDHA state-of-practice for nuclear installations that is consistent with the new IAEA safety standards. We also summarize progress in an ongoing international PFDHA benchmark project that will ultimately provide technical guidance to Member States for conducting site-specific fault displacement hazard assessments.

Some aphid species produce a soldier caste with enlarged forelegs and horns (weapons). It has been hypothesised that the evolution of morphological specialization by soldiers in social aphids is accelerated by high predation pressure, but this possibility has not been tested. Here, we investigated the relationship between local predator abundance and soldiers' weapon size and aggressiveness in a prey-predator system comprising a eusocial aphid, Ceratovacuna japonica, and its predators (larvae of the butterfly Taraka hamada and of the moth Atkinsonia ignipicta) in two populations with different predator abundances. We found that the soldiers in the predator-abundant population had larger weapons and were more aggressive than those in the population with lower predator abundance. Furthermore, the soldiers' defensive prowess (evaluated as the survival of aphids in the presence of predators) was greater in the predator-abundant population. These results provide the first evidence that a population of eusocial aphids experiencing high predation pressure has soldiers with pronounced defensive traits and defensive prowess., Scientific reports, 12(1), art. no. 15874; 2022

Although studies on snow algae and macroinvertebrates have been frequently conducted on snow patches, only few surveys have been focused on microinvertebrates which reach high biomass and play various trophic roles in other cold habitats. The aims of this study were (1) to search for microinvertebrates in seasonal surface snow patches located on the slope of Mt. Gassan, in northern Japan, and (2) to identify factors determining their distribution associated with snow algal blooms of various colorations (orange, green, and golden-brown) collected from the same sampling site over two seasons (2018, 2019). Microscopic observation revealed presence of two major groups of microinvertebrates: Tardigrada and Rotifera. They were concentrated in green snow colored by blooms of Chloromonas sp. in comparison to orange or golden-brown snow and only a few were found in white snow. Mean body length of tardigrades increased throughout the melt season, their intestine content was green and they laid eggs on colored snow. These results suggest that tardigrades preferentially grew and reproduced on green snow patches. Population densities of tardigrades, rotifers and concentration of chlorophyll a were significantly correlated. Our study indicates that green snow patches in temperate mountainous forests constitute important and unique low-temperature ecosystems for microinvertebrates. Snow covered by algae is an unrecognized novel habitats for tardigrades and rotifers.

Cryoconite is a mixture of mineral and organic material covering glacial ice, playing important roles in biogeochemical cycles and lowering the albedo of a glacier's surface. Understanding the differences in structure of cryoconite across the globe can be important in recognizing past and future changes in supraglacial environments and ice-organisms-dust interactions. Despite the worldwide distribution and over a century of studies, the basic characteristics of cryoconite, including its forms and geochemistry, remain poorly studied. The major purpose of our study is the presentation and description of morphological diversity, chemical and photoautotrophs composition, and organic matter content of cryoconite sampled from 33 polar and mountain glaciers around the globe. Observations revealed that cryoconite included various morphologies including loose and granular forms. Granular cryoconite includes smooth, rounded, or irregularly shaped forms; with some having their surfaces covered by cyanobacteria filaments. The occurrence of granules increased with the organic matter content in cryoconite. Moreover, a major driver of cryoconite colouring was the concentration of organic matter and its interplay with minerals. The structure of cyanobacteria and algae communities in cryoconite differs between glaciers, but representatives of cyanobacteria families Pseudanabaenaceae and Phormidiaceae, and algae families Mesotaeniaceae and Ulotrichaceae were the most common. The most of detected cyanobacterial taxa are known to produce polymeric substances (EPS) that may cementing matter and form granules. Organic matter content in cryoconite varied between glaciers, ranging from 1% to >40%. The geochemistry of all the investigated samples reflected local sediment sources, except of highly concentrated Pb and Hg in cryoconite collected from European glaciers near industrialized regions, corroborating cryoconite as element-specific collectors and potential environmental indicator of anthropogenic activity. Our work supports a notion that cryoconite may be more than just simple sediment and instead exhibits complex structure with relevance for biodiversity and the functioning of glacial ecosystems.

BackgroundThe Japanese honeybee,Apis cerana japonica, shows a specific defensive behavior, known as a “hot defensive bee ball,” used against the giant hornet,Vespa mandarinia. Hundreds of honeybee workers surround a hornet and make a “bee ball” during this behavior. They maintain the ball for around 30 min, and its core temperature can reach 46. Although various studies have been conducted on the characteristics of this behavior, its molecular mechanism has yet to be elucidated. Here, we performed a comprehensive transcriptomic analysis to detect candidate genes related to balling behavior.ResultsThe expression levels of differentially expressed genes (DEGs) in the brain, flight muscle, and fat body were evaluated during ball formation and incubation at 46 °C. The DEGs detected during ball formation, but not in response to heat, were considered important for ball formation. The expression of genes related to rhodopsin signaling were increased in all tissues during ball formation. DEGs detected in one or two tissues during ball formation were also identified.ConclusionsGiven that rhodopsin is involved in temperature sensing inDrosophila, the rhodopsin-related DEGs inA. cerana japonicamay be involved in temperature sensing specifically during ball formation.

The efficacy of preoperative neoadjuvant chemoradiotherapy (NAC) in cases of pancreatic cancer with extremely poor prognoses has been reported. In this study, we aimed to identify novel biomarkers that reflect prognoses following chemoradiotherapy using tertiary lymphoid organs (TLO) expressed in the tumor microenvironment. Resected tumor specimens were obtained from 140 pancreatic cancer patients. We retrospectively investigated the clinical relevance of TLO by categorizing patients into those who underwent upfront surgery (surgery first [SF]) and those who received NAC. The immunological elements within TLO were analyzed by immunohistochemistry (IHC). In the IHC analysis, the proportions of CD8+ T lymphocytes, PNAd+ high endothelial venules, CD163+ macrophages and Ki‐67+ cells within the TLO were higher in the NAC group than in the SF group. In contrast, the proportion of programmed cell death‐1+ immunosuppressive lymphocytes within TLO was lower in the NAC group than in the SF group. The NAC group demonstrated favorable prognoses compared with the SF group. In the multivariate analysis, the TLO/tumor ratio was determined as an independent predictive prognostic factor. In conclusion, the administration of preoperative chemoradiotherapy may influence the immunological elements in the tumor microenvironment and result in favorable prognoses in pancreatic ductal adenocarcinoma patients.

The following design details of the high temperature engineering test reactor (HTTR) are described: nuclear, thermal-hydraulic seismic and safety performance, metal and graphite components, core components and reactor internals, and cooling, reactivity control, instrumentation and control systems. The new design criteria have been developed for graphite structures, and a super heat-resistant alloy, Hastelloy XR, was newly developed for high temperature components such as heat transfer tubes of an intermediate heat exchanger. The performance and structural integrity of the fuel core components and reactor internals were verified in advance by the research and development described in Chapter 3, R&D on Components. As for the safety design, the strategy of defense in depth was implemented so that the safety engineering functions such as control of reactivity, removal of residual heat, and confinement of fission products shall be well performed to ensure safety.

Although studies on snow algae and macroinvertebrates have been frequently conducted on snow patches, no attention have been paid to ubiquitous microinvertebrates which in other cold habitats reach high biomass and play various trophic roles. The aim of this study was to search microinvertebrates in seasonal snow patches in Mt. Gassan, in northern Japan, and identify factors determining their distribution associated with snow algal blooming of various coloration (red, green, and yellow). Microscopic observation revealed presence of two major groups of microinvertebrates Tardigrada and Rotifera. Tardigrades and rotifers were the most abundant and frequent in green snow formed by blooming of Chloromonas sp., but few in red or yellow snow. Body length of tardigrades increased through the melting season and animals laid eggs on colored snow. These results suggest tardigrades successfully grew and reproduced on snow patches. Taking into account the presence of tardigrades and rotifers mostly in green snow (only few found in red and yellow) with high densities, we may assume green snow patches constitute important and unique low-temperature ecosystems for microinvertebrates in a temperate mountainous forest. Area of snow algae blooming worldwide are unrecognized novel habitat for tardigrades and rotifers.

Honey bees and bumble bees belong to the same family (Apidae) and their workers exhibit a division of labor, but the style of division of labor differs between species. The molecular and neural bases of the species-specific social behaviors of Apidae workers have not been analyzed. Here, we focused on two immediate early genes, hormone receptor 38 (HR38) and early growth response gene-1 (Egr1), and late-upregulated ecdysone receptor (EcR), all of which are upregulated by foraging flight and expressed preferentially in the small-type Kenyon cells of the mushroom bodies (MBs) in the honey bee brain. Gene expression analyses in Bombus ignitus revealed that HR38 and Egr1, but not EcR, exhibited an immediate early response during awakening from CO2 anesthesia. Both premature mRNA for HR38 and mature mRNA for Egr1 were induced during foraging flight, and mRNAs for HR38 and Egr1 were sparsely detected inside the whole MB calyces. In contrast, EcR expression was higher in forager brains than in nurse bees and was expressed preferentially in the small-type Kenyon cells inside the MBs. Our findings suggest that Kenyon cells are active during foraging flight and that the function of late-upregulated EcR in the brain is conserved among these Apidae species.

In the late 1980s, the seismic classification of the high temperature engineering test reactor (HTTR) was formulated during its design stage. Because of the HTTR’s lack of operation experiences to sufficiently understand the safety characteristics of high temperature gas cooled reactors (HTGRs) at that time, the seismic classification of commercial light water reactors (LWRs) was applied to HTTR. However, subsequent operation experiences and test results using HTTR made it clear that the seismic classification of commercial LWRs was somewhat too conservative for the HTGRs. The seismic classification of HTTR was reevaluated using the following approach. Class S facilities with high safety requirements ensured that they maintained their function even when the safety functions of Class B and Class C facilities were lost during earthquake-triggered accidents, thereby safely controlling the accident without exposing the members of the public in the vicinity of the reactor to excessive radiation exposure. Consequently, Class S facilities were downgraded compared with the commercial LWRs. Moreover, an evaluation was conducted to verify the validity of the new seismic classification under the conditions where the functions of Class B and Class C facilities are lost. It was confirmed that the reactor was stable and that the evaluated public dose was below the authorized limit. In June 2020, the Nuclear Regulatory Authority in Japan confirmed that the results of the seismic classification conformed to the standard rules of the reactor installation change.

International audience; AbstractGynandromorphy, which is characterized by the coexistence of male and female tissues in a single individual, is known in insects. Gynandromorphs exhibit diverse levels of defects in sexual behavior. The distribution pattern of both sexes within the nervous systems could be responsible for these differences in behavioral traits; however, most studies have mainly focused on the unique external morphological traits of gynandromorphs, and little attention has been paid to the evaluation of nervous systems, at least in Hymenoptera. In this study, we evaluated a gynandromorphic individual of bumblebee (Bombus ignitus) with a bilaterally dimorphic head and thorax (left side, male; right side, female) and a uniformly masculine gaster. The gynandromorph exhibited abnormal sexual behavior; it normally approached and touched virgin queens but rarely made subsequent copulation attempt. Dissection of the gaster indicated that it possessed a set of male reproductive organs. We analyzed the encephalic and antennal expression patterns of the fruitless (fru) gene, which shows sex-specific alternative splicing conserved in various insect orders and has been thought to act as the master regulator of sexual behavior in male nervous systems. The gynandromorph showed left-side-biased expression of male-type fru transcripts. We discuss a possible mechanism for the observed unusual interruption of sexual behavior of the gynandromorph by reference to the fru expression pattern and our recent findings on the sexually dimorphic response to female-derived pheromones.

A society of bumble bees is primitively eusocial, with an annual life cycle, and can be used as a physiological model of social bees for comparative studies with highly eusocial hymenopterans. We investigated the dynamics of biogenic amine levels in the brain, meso-metathoracic ganglia, terminal abdominal ganglion, and hemolymph in queens 1 day after mating (1DAM), during diapause (Dp), and during colony founding (CF) in the bumble bee, Bombus ignitus . Dopamine levels in the brain of CF queens were significantly lower than in 1DAM and Dp queens, and the levels in the thoracic ganglia and hemolymph in CF queens were lower than in 1DAM queens, but did not differ from other groups in the abdominal ganglion. Octopamine levels in the brains were higher in Dp queens than in 1DAM queens. Serotonin and tyramine levels did not differ between the groups in different compartments of the central nervous system (CNS) that we examined. The dopamine levels in the brains were significantly positively correlated with those in the thoracic ganglia, abdominal ganglion, and hemolymph, suggesting the regulation of dopamine levels among three different compartments of the CNS. In isolated virgin queens, there were no significant correlations between the brain levels of biogenic amines that we examined and the lengths of the largest terminal oocytes, whereas, in isolated workers, the brain dopamine levels were positively correlated with oocyte lengths. These results suggest that dopamine is associated with ovarian activity in reproductive workers, but not in either virgin or mated queens.

// Shoki Sato 1 , Toru Nakamura 1 , Toyomasa Katagiri 2 , Takahiro Tsuchikawa 1 , Toshihiro Kushibiki 1 , Kouji Hontani 1 , Mizuna Takahashi 1 , Kazuho Inoko 1 , Hironobu Takano 1 , Hirotake Abe 1 , Shintaro Takeuchi 1 , Masato Ono 1 , Shota Kuwabara 1 , Kazufumi Umemoto 1 , Tomohiro Suzuki 1 , Osamu Sato 1 , Yusuke Nakamura 3 and Satoshi Hirano 1 1 Department of Gastroenterological Surgery II, Hokkaido University Graduate School of Medicine, Sapporo, Japan 2 Division of Genome Medicine, Institute for Genome Research, Tokushima University, Tokushima, Japan 3 Department of Medicine and Surgery, The University of Chicago, Chicago, IL, USA Correspondence to: Toru Nakamura, email: torunakamura@med.hokudai.ac.jp Keywords: C16orf74; pancreatic ductal adenocarcinoma; cell-permeable peptide; molecular target therapy Received: May 04, 2017 Accepted: July 26, 2017 Published: October 19, 2017 ABSTRACT Background: Chromosome 16 open reading frame 74 ( C16orf74 ) is highly expressed in pancreatic ductal adenocarcinoma (PDAC) and is involved in cancer cell proliferation and invasion through binding to calcineurin (CN). Therefore, C16orf74 is a good target for the development of a PDAC treatment. A cell-permeable dominant-negative (DN) peptide that can inhibit the C16orf74/CN interaction was designed to examine whether this peptide can inhibit PDAC cell proliferation in vitro and in vivo . Method: TheDN-C16orf74 peptide, which corresponds to the portion of C16orf74 that interacts with CN, was synthesized, and we assessed its anti-tumor activity in proliferation assays with human PDAC cells and the underlying molecular signaling pathway. Using an orthotopic xenograft model of PDAC, we treated mice intraperitoneally with phosphate-buffered saline (PBS), control peptide, or DN-C16orf74 and analyzed the tumor-suppressive effects. Result: DN-C16orf74 inhibited the binding of C16orf74 to CN in an immunoprecipitation assay. DN-C16orf74 suppressed PDAC cell proliferation, and the level of suppression depended on the expression levels of C16orf74 in vitro . DN-C16orf74 also exhibited anti-tumor effects in orthotopic xenograft model. Furthermore, the tumor-suppressive effect was associated with inhibition of the phosphorylation of Akt and mTOR. Conclusion: The cell-permeable peptide DN-C16orf74 has a strong anti-tumor effect against PDAC in vitro and in vivo .

The rewarding orchid, Cremastra appendiculata (Orchidaceae), has a strong floral scent and is pollinated by long-tongued bumble bee queens (Bombus diversus tersatus Smith; Hymenoptera: Apidae). The response of queens of B. diversus tersatus to the scent of C. appendiculata was investigated using a gas chromatography–electroantennographic detector system and Y-tube olfactometer. Gas chromatography–electroantennographic detector analysis of flower extracts showed that seven compounds (nerol, methyl decanoate, methyl dodecanoate, methyl tetradecanoate, methyl hexadecanoate, ethyl dodecanoate, and ethyl tetradecanoate) elicited antennal responses from B. diversus tersatus queens. Further, Y-tube olfactometer test results showed that queens significantly preferred both the flower extracts and synthetic mixture of seven EAD active compounds compared with pentane (a solvent control). These results suggest that floral scents play an important role in attracting queens and promote successful pollination.

The Tenth Symposium on Polar Science/Ordinary sessions: [OB] Polar Biology, Wed. 4 Dec. / 3F Multipurpose conference room, National Institute of Polar Research

Stem cell therapy using islet-like insulin-producing cells derived from human pluripotent stem cells has the potential to allow patients with type 1 diabetes to withdraw from insulin therapy. However, several issues exist regarding the use of stem cell therapy to treat type 1 diabetes. In this review, we will focus on the following topics: (1) autoimmune responses during the autologous transplantation of stem cell-derived islet cells, (2) a comparison of stem cell therapy with insulin injection therapy, (3) the impact of the islet microenvironment on stem cell-derived islet cells, and (4) the cost-effectiveness of stem cell-derived islet cell transplantation. Based on these various viewpoints, we will discuss what is required to perform stem cell therapy for patients with type 1 diabetes.

New superconductors, Lix(C2H8N2)yMoTe2 with 0 < x(Li) ≤ 1, have been synthesized via the co-intercalation of Li and ethylenediamine (EDA) into MoTe2. It has been found that the maximum \(T_{\text{c...

We identified mermithid nematodes infecting a post-hibernating Japanese bumblebee (Bombus pseudobaicalensis Vogt) queen in Nemuro, Hokkaido, Japan. The infected queen did not lay eggs or feed on pollen during laboratory rearing. In addition, the queen usually crawled under the straw set in the rearing box, which differed from the typical behavior of a normal queen. Intra-abdominal observation revealed that, compared with the ovaries of a normal queen, those of the infected queen were undeveloped. Infection by mermithid nematodes may result in the sterilization of the bumblebee queen. The molecular phylogenetic analysis revealed that the mermithid species infecting the Japanese bumblebee queen differed from the Pheromermis species reported as a parasite of Hymenopteran insects, and that they were closely related to mermithid nematodes found in spiders and Ovomermis sinensis Chen, a parasite of the tobacco budworm larva Helicoverpa armigera Hubner. These findings constitute the first report of mermithid nematodes infecting Japanese bumblebee.