Analysis of Concomitant Medications Prescribed with Antipsychotics to Patients with Dementia.

INTRODUCTION: Antipsychotics are still commonly prescribed to patients with dementia, despite the many issues that have been identified. This study aimed to quantify antipsychotic prescription in patients with dementia and the types of concomitant medications prescribed with antipsychotics. METHODS: A total of 1,512 outpatients with dementia who visited our department between April 1, 2013 and March 31, 2021, were included in this study. Demographic data, dementia subtypes, and regular medication use at the time of the first outpatient visit were investigated. The association between antipsychotic prescriptions and referral sources, dementia subtypes, antidementia drug use, polypharmacy, and prescription of potentially inappropriate medications (PIMs) was evaluated. RESULTS: The antipsychotic prescription rate for patients with dementia was 11.5%. In a comparison of dementia subtypes, the antipsychotic prescription rate was significantly higher for patients with dementia with Lewy bodies (DLB) than for those with all other dementia subtypes. In terms of concomitant medications, patients taking antidementia drugs, polypharmacy, and PIMs were more likely to receive antipsychotic prescriptions than those who were not taking these medications. Multivariate logistic regression analysis showed that referrals from psychiatric institutions, DLB, N-methyl-d-aspartate (NMDA) receptor antagonists, polypharmacy, and benzodiazepine were associated with antipsychotic prescriptions. CONCLUSIONS: Referrals from psychiatric institutions, DLB, NMDA receptor antagonist, polypharmacy, and benzodiazepine were associated with antipsychotic prescriptions for patients with dementia. To optimise prescription of antipsychotics, it is necessary to improve cooperation between local and specialised medical institutions for accurate diagnosis, evaluate the effects of concomitant medication administration, and solve the prescribing cascade.

Influence of Psychotropic Pro Re Nata Drug Use on Outcomes in Hospitalized Patients with Schizophrenia.

Objective: In the treatment of patients with schizophrenia, pro re nata (PRN) drugs are commonly prescribed for medical indications such as agitation, acute psychiatric symptoms, insomnia, and anxiety. However, high-quality evidence supporting the use of PRN medications is lacking, and these drugs are administered on the basis of clinical experience and habits. Therefore, the actual use of psychotropic PRN drugs and its influence on the patients' outcomes need to be investigated. Methods: This study included 205 patients who underwent inpatient treatment for schizophrenia. We investigated the prescription of psychotropic drugs before admission and at discharge, as well as the dosing frequency of PRN drugs during hospitalization. We also examined the influence of psychotropic PRN drug use on hospitalization days, antipsychotic polypharmacy, and readmission rates. Results: Patients who used psychotropic PRN drugs during hospitalization had significantly longer hospitalization days (p = 7.5 × 10-4) and significantly higher rates of antipsychotic polypharmacy (p = 2.4 × 10-4) at discharge than those who did not use psychotropic PRN drugs. Moreover, a higher number of psychotropic PRN drugs used per day was associated with higher readmission rates within 3 months of discharge (p = 4.4 × 10-3). Conclusion: Psychotropic PRN drug use is associated with prolonged hospitalization, antipsychotic polypharmacy, and increased readmission rates in inpatients with schizophrenia. Therefore, psychiatric symptoms should be stabilized with regularly prescribed medications without the extensive use of psychotropic PRN drugs. Moreover, a system for monitoring and reexamining PRN drug use needs to be established.

Spontaneous Shrinkage of isocitrate dehydrogenase (IDH)-mutant astrocytoma caused by intra-tumoural cyst rupture: a case report.

BACKGROUND: T2-fluid-attenuated inversion recovery (FLAIR) mismatch sign is a specific imaging finding of isocitrate dehydrogenase (IDH)-mutant astrocytomas. Histologically, a hypointense area on FLAIR images indicates the presence of microcysts. Here we report a case of IDH-mutant astrocytoma that shrunk spontaneously. CASE DESCRIPTION: A 26-year-old woman presented with a complaint of headache. Her magnetic resonance (MR) images revealed a lesion mass with a T2-FLAIR mismatch sign in the left frontal lobe. Subsequently, after 1 month, she was referred to our department, and we found that the lesion had unexpectedly shrunk; however, no further shrinkage was observed in the next 3 months. Furthermore, a biopsy was performed, and the results indicated a diagnosis of astrocytoma, IDH-mutant CNS WHO grade 3. Thus, she underwent subtotal resection. We found no neurological deficits in the patient, and she received 60 Gy of radiotherapy at the local site and chemotherapy with nimustine hydrochloride (ACNU), followed by the administration of ACNU every 8 weeks for 2 years. Overall, after 36 months of tumour resection, she was in good health and exhibited no recurrence. Notably, her histological and MR image findings suggested that the macroscopic cyst was formed by the fusion of microcysts, which is a characteristic feature of IDH-mutant astrocytoma with a T2-FLAIR mismatch sign, and that the tumour shrunk because of the rupture of the cyst in the Sylvian cistern. CONCLUSION: The present case report suggests that IDH-mutant astrocytoma cannot be ruled out even when the lesion shrinks spontaneously.

Evolution and functionalization of vitellogenin genes in the termite Reticulitermes speratus.

Eusociality has been commonly observed in distinct animal lineages. The reproductive division of labor is a particular feature, achieved by the coordination between fertile and sterile castes within the same nest. The sociogenomic approach in social hymenopteran insects indicates that vitellogenin (Vg) has undergone neo-functionalization in sterile castes. Here, to know whether Vgs have distinct roles in nonreproductive castes in termites, we investigated the unique characteristics of Vgs in the rhinotermitid termite Reticulitermes speratus. The four Vgs were identified from R. speratus (RsVg1-4), and RsVg3 sequences were newly identified using the RACE method. Molecular phylogenetic analysis supported the monophyly of the four termite Vgs. Moreover, the termites Vg1-3 and Vg4 were positioned in two different clades. The  dN/dS ratios indicated that the branch leading to the common ancestor of termite Vg4 was under weak purifying selection. Expression analyses among castes (reproductives, workers, and soldiers) and females (nymphs, winged alates, and queens) showed that RsVg1-3 was highly expressed in fertile queens. In contrast, RsVg4 was highly expressed in workers and female nonreproductives (nymphs and winged adults). Localization of RsVg4 messenger RNA was confirmed in the fat body of worker heads and abdomens. These results suggest that Vg genes are functionalized after gene duplication during termite eusocial transition and that Vg4 is involved in nonreproductive roles in termites.

Efficient RNA interference method during caste differentiation with hormone treatment in the termite Reticulitermes speratus (Isoptera: Rhinotermitidae).

Unveiling the proximate mechanism of caste differentiation is crucial for understanding insect social evolution, and gene function analysis is an important tool in this endeavor. The RNA interference (RNAi) technique is useful in termites, but its knockdown effects may differ among species. One of the most important model species in the field of termite sociogenomics is Reticulitermes speratus Kolbe (Isoptera: Rhinotermitidae). Presoldier and worker differentiation of this species can be artificially induced by juvenile hormone and 20-hydroxyecdysone application, respectively. However, appropriate RNAi technique of genes expressed during caste differentiation has never been considered. To clarify this issue, first, we injected nine different volumes of nuclease-free water (NFW, 0-404.8 nL) into workers and found that survival and caste differentiation rates were strongly reduced by the application of the top three largest volumes. Second, we injected double-stranded (ds) RNA of ecdysone receptor homolog (RsEcR) (2.0 µg/151.8 nL NFW) into workers with hormone treatments. The expression levels of RsEcR were significantly reduced at 9 days after dsRNA injection. RsEcR RNAi strongly affected both molting events during presoldier and worker differentiation induced by hormone treatments. The present results highlight the need for caution regarding injection volumes for RNAi experiments using hormone treatments. We suggest that the injection of dsRNA solution (2 µg; approximately 100-200 nL) is suitable for RNAi experiments during caste differentiation induced by hormone application in R. speratus.

Metal-Free Homocoupling of Pyrene inside the Pores of Mesoporous Carbons via Electrochemical Oxidation: Application for Electrochemical Capacitors.

A pyrene dimer (PYD) is synthesized by electrochemical oxidation via homocoupling of pyrene (PY) inside the pores of MgO-templated mesoporous carbons without any metal catalysts or organic solvents. The resulting MgO-C/PYD hybrids can be used as high-performance aqueous electrochemical capacitor electrodes due to the reversible redox property of PYD and large contact area between the hybridized PYD and conductive carbon surfaces, which enable rapid charge transfer at the large contact interface. In our previous study, PY was considered to polymerize through electrochemical oxidation, and activated carbon with the pore sizes of ∼4 nm was used as a porous carbon substrate. In this study, the MgO-templated carbons have the average pore sizes of 5, 10, and 30 nm, and their large mesopore volumes can accommodate a large amount of PYD for enhancing the capacitance. To develop high-performance electrochemical capacitors, the dependence of the capacitance enhancement and the capacitance retention on the amount of PY and the pore sizes of MgO-templated carbons are studied. It is found that mesopores are necessary for fast charging/discharging, but the capacitance retention and capacitance enhancement decrease with increasing the mesopore sizes and the amount of PY due to the decreased utilization ratio of PY.

Synthesis of Polynorbornadiene within the Pores of Activated Carbons: Effects on EDLC and Hydrogen Adsorption Performances.

Norbornadiene (NBD) is adsorbed on activated carbon (AC), and the adsorbed NBD is polymerized within the pores of AC. Two kinds of ACs─AC-2 with only micropores of ∼2 nm and AC-4 with not only micropores but also mesopores below 4 nm─are examined to study the effects of the hybridized polynorbornadiene (PNBD) on the electric double-layer capacitor and hydrogen adsorption performance. Various measurements are performed to determine the form of the hybridized PNBD inside the pores of AC. Scanning and transmittance electron microscopy observations of the AC/PNBD hybrids confirm that PNBD is hybridized inside the pores of AC, and there is little PNBD on the surface of AC particles. The nitrogen adsorption/desorption measurement for the hybrids of AC-4 reveals that PNBD is not hybridized preferentially inside micropores rather than mesopores irrespective of the amount of PNBD. In addition, both micropore and mesopore volumes decrease at a constant rate with increasing amounts of PNBD. These results suggest that PNBD is hybridized not as a layer but as an agglomerate for both ACs, and the agglomerate delocalizes over the whole AC pores, which is supported by the results of electrochemical measurements and hydrogen adsorption behavior of the hybrids.

Comparison of gene expression profiles among caste differentiations in the termite Reticulitermes speratus.

Termite castes express specialized phenotypes for their own tasks and are a good example of insect polyphenism. To understand the comprehensive gene expression profiles during caste differentiation, RNA-seq analysis based on the genome data was performed during the worker, presoldier, and nymphoid molts in Reticulitermes speratus. In this species, artificial induction methods for each molt have already been established, and the time scale has been clarified. Three different periods (before the gut purge (GP), during the GP, and after the molt) were discriminated in each molt, and two body parts (head and other body regions) were separately sampled. The results revealed that many differentially expressed genes (head: 2884, body: 2579) were identified in each molt. Based on the independent real-time quantitative PCR analysis, we confirmed the different expression patterns of seven out of eight genes in the presoldier molt. Based on the GO and KEGG enrichment analyses, the expressions of genes related to juvenile hormone titer changes (e.g., JH acid methyltransferase), nutrition status (e.g., Acyl-CoA Delta desaturase), and cell proliferation (e.g., insulin receptor), were shown to specifically fluctuate in each molt. These differences may have a crucial impact on caste differentiation. These data are important resources for future termite sociogenomics.

Genomic and transcriptomic analyses of the subterranean termite Reticulitermes speratus: Gene duplication facilitates social evolution.

Termites are model social organisms characterized by a polyphenic caste system. Subterranean termites (Rhinotermitidae) are ecologically and economically important species, including acting as destructive pests. Rhinotermitidae occupies an important evolutionary position within the clade representing a transitional taxon between the higher (Termitidae) and lower (other families) termites. Here, we report the genome, transcriptome, and methylome of the Japanese subterranean termite Reticulitermes speratus Our analyses highlight the significance of gene duplication in social evolution in this termite. Gene duplication associated with caste-biased gene expression was prevalent in the R. speratus genome. The duplicated genes comprised diverse categories related to social functions, including lipocalins (chemical communication), cellulases (wood digestion and social interaction), lysozymes (social immunity), geranylgeranyl diphosphate synthase (social defense), and a novel class of termite lineage-specific genes with unknown functions. Paralogous genes were often observed in tandem in the genome, but their expression patterns were highly variable, exhibiting caste biases. Some of the assayed duplicated genes were expressed in caste-specific organs, such as the accessory glands of the queen ovary and the frontal glands of soldier heads. We propose that gene duplication facilitates social evolution through regulatory diversification, leading to caste-biased expression and subfunctionalization and/or neofunctionalization conferring caste-specialized functions.

Unilateral nephrectomy for young infants with congenital nephrotic syndrome of the Finnish type.

BACKGROUND: The management of congenital nephrotic syndrome of the Finnish type (CNF) is challenging. It is difficult to withdraw intravenous albumin infusions, resulting in long-term hospitalization. In addition, fatal hypotension after bilateral nephrectomy has been reported. In our center, we have performed unilateral nephrectomy during early infancy. METHODS: Infants diagnosed with CNF between 2011 and 2020 in our institution were enrolled. We examined the clinical course before and after unilateral nephrectomy and evaluated the effectiveness of this strategy. RESULTS: Seven patients (all showing NPHS1 mutations) were enrolled. All required daily intravenous albumin infusion via central venous catheter (CVC). Unilateral nephrectomy was performed at a median of 76 days of age (59-208 days). Surgical complications did not occur in any of patients. The mean albumin dose was decreased after unilateral nephrectomy (2.0 vs 0.4 g/kg/day; p = 0.02). Intravenous albumin infusion could be withdrawn at a median of 17 days, the CVC removed at a median of 21 days, and they discharged at a median of 82 days after unilateral nephrectomy. Although bacterial infections were noted seven times before unilateral nephrectomy, only one episode occurred after surgery. Four patients initiated peritoneal dialysis at two to three years of age and all of them underwent kidney transplantation thereafter. CONCLUSIONS: Unilateral nephrectomy during early infancy may be an effective treatment allowing for withdrawal from albumin infusion, prevention of complications, withdrawal from CVCs and shortening hospital stay for patients with CNF.

Successful endoscopic surgical treatment of pleuroperitoneal communication in two infant cases.

BACKGROUND: Pleuroperitoneal communication (PPC) is an uncommon, but potentially life-threatening complication of peritoneal dialysis (PD). If a fistula does not close with conservative treatment, surgical repair is required. However, approximately half of these patients are forced to shift from PD to hemodialysis. Although it is important to confirm the site of the fistula to achieve a successful surgical treatment, this identification is more difficult in pediatric patients than in adults. CASE PRESENTATION: We report two infantile cases of severe PPC associated with PD. In both cases, the age at onset was less than 2 years, and right-sided pleural effusion with dyspnea was observed. PPC was diagnosed by the change in color of the pleural fluid after the injection of a dye into the peritoneal cavity. Peritoneal scintigraphy and single-photon emission computed tomography and computed tomography (SPECT/CT) were performed, and these were effective in locating the fistula site. Endoscopic surgery (video-assisted thoracic surgery (VATS) and laparoscopic surgery) was performed. Indocyanine green (ICG), which was injected into the abdominal cavity, showed the exact site of the fistula. The fistula was successfully closed by attaching an absorbable sheet to it from the thoracic side and an autograft (the falciform ligament) to it from the abdominal side in one patient. In the other patient, the fistula site was resected and sutured, and reinforced with an absorbable sheet. In both cases, PD was resumed without any complication. CONCLUSION: We successfully treated two infants of PPC by endoscopic surgery. To identify the fistula site, the ICG navigation method was useful. Even in small infants, PPC can be treated successfully by endoscopic surgical repair if the site of the fistula is identified.

Rapid Treatment of Acute Ischemic Stroke Using a Computed Tomography-Based Reperfusion Protocol: The Reality of a Local Community Hospital with Limited Resources.

Objective: In patients with acute ischemic stroke (AIS), prognosis strongly depends on the onset-to-recanalization time. The Ishinomaki protocol for rapid recanalization has been used since October 2017. This protocol determines the indication for reperfusion therapy based on computed tomography (CT)/three-dimensional CT angiography (3DCTA) findings and intends to reduce the onset-to-recanalization time. We aimed to compare the outcomes before and after protocol introduction. Methods: Our hospital is the only thrombectomy-capable center in Ishinomaki, Tome, and Kesennuma medical area. Before protocol introduction (April 2014-June 2016), both CT and magnetic resonance imaging were performed to determine the indications for intravenous (IV) recombinant tissue-plasminogen activator (rt-PA) or mechanical thrombectomy within 6 hours of disease onset. However, after protocol introduction (from October 2017), plain CT and 3DCTA were used. We collected data on patients who underwent mechanical thrombectomy and/or IV rt-PA before (n = 13) and after (n = 34) the protocol introduction. The required time from onset to door (OTD), door to needle (DTN), needle to puncture (NTP), puncture to recanalization (PTR), and door to recanalization (DTR) were compared before and after protocol introduction. Furthermore, thrombolysis in cerebral infarction (TICI) grades and modified Rankin scale (mRS) scores at discharge were compared. Results: The outcomes before and after protocol introduction were as follows: OTD: 105 ± 73.8 (mean ± standard deviation) vs. 120 ± 68.1 min (p = 0.376, Mann-Whitney U test); DTN: 62.9 ± 15.9 vs. 41 ± 17 min (p <0.01); NTP: 112 ± 69.8 vs. 39.9 ± 33.7 min (p <0.01); PTR: 87.9 ± 45.4 vs. 52.5 ± 27.9 min (p <0.01); and DTR, 230 ± 69.9 vs. 110 ± 40.3 min (p <0.0001). Before and after protocol introduction, the proportion of patients with TICI grade 2b-3, mRS score of 0-2 at discharge, and mRS score of 5-6 were 54% vs. 50% (p = 0.815, Fisher's exact test), 23% vs. 21% (p = 0.854), and 15% vs. 50% (p = 0.046), respectively. Conclusion: The Ishinomaki protocol reduced the mean DTR time by 120 min. The reduction in treatment time was due to the change in CT-based recanalization and collaboration with emergency physicians and paramedics. There was no increase in good outcomes, but there was a significant increase in poor outcomes at discharge. Patients who could not be salvaged were indicated for reperfusion therapy as CT and 3DCTA cannot detect the ischemic core.

Investigating interest in orthopedic surgery within an entire medical faculty: A cross-sectional study.

BACKGROUND: Discrepancies exist between the magnitude of musculoskeletal problems and the competency of physicians practicing musculoskeletal medicine, which likely stems from medical school-level educational deficiencies. Therefore, inadequate orthopedic surgery education during medical school may affect the number of students aspiring to practice orthopedic surgery. However, the motivating factors underlying medical students' selection of a career specialty are largely unknown. This study aims to use a survey to examine the motivations of medical students who consider orthopedic surgery as a potential career specialty. METHODS: A questionnaire survey was administered to medical students in our medical faculty. The results were stratified on the basis of gender, year, and experience as a patient; results were then compared between students who wished to practice orthopedic surgery and those who did not consider it a potential specialty. RESULTS: Of the 499 students who responded to the questionnaire, 47% considered orthopedic surgery as their career specialty. Being male and having experienced orthopedic surgery as a patient were significant factors influencing the aspiration to practice orthopedic surgery (p < 0.001). In addition, the motivation for choosing orthopedic surgery was academic interest for 55% of students. In the first and fifth years, more than half of the students preferred an orthopedic surgery specialty. The percentage of fifth-year students who were candidates for orthopedic surgery as their career specialty significantly exceeded that of students in other years (p = 0.03). However, the percentage of students considering orthopedic surgery decreased in the sixth year. CONCLUSION: Our findings suggest that orthopedic surgeons should provide a clearer, more informative job description to attract female medical students' attention and change their negative perception of orthopedic surgery. Furthermore, including education that incorporates experiences closer to clinical practice at the medical-school level is important for increasing the number of candidates for orthopedics.

Eosinophilic peritonitis in children on chronic peritoneal dialysis.

BACKGROUND: Eosinophilic peritonitis (EP) is sometimes difficult to distinguish from bacterial peritonitis (BP) at onset, as they are often overlapping. Previous reports show EP occurs more frequently in infants, although the reason is unknown. METHODS: The study population was 77 pediatric patients receiving chronic peritoneal dialysis (PD) in our center. We compared clinical and laboratory data at onset of EP with those of BP. We also investigated age distribution at onset of EP and PD-related surgery. RESULTS: Eleven patients developed EP (18 episodes) and 19 patients developed BP (38 episodes). EP patients showed lower rate of cloudy dialysate (44.4% vs. 74.4%; p = 0.04), lower rate of fever (38.9% vs. 56.4%), lower frequency of abdominal pain (16.7% vs. 38.5%), higher peripheral blood eosinophil counts (/µL) (514 vs. 160; p < 0.001), and lower serum C-reactive protein level (mg/dL) (0.4 vs. 4.7; p < 0.001) than BP patients. Thirteen EP events were observed after 169 surgical interventions. Age at surgery-related EP was similar to age at surgery without EP (2.6 vs. 2.1; p = 0.65). There was no significant difference in postoperative EP occurrence between groups <2 years and ≥ 2 years (6.2% vs. 9.1%; p = 0.48). However, infants received more operations than older children. CONCLUSION: Clinical symptoms in children and laboratory data of EP in children were less severe than those of BP. As incidence of postoperative EP did not differ by age, we speculate that higher incidence of EP in infants might be associated with higher incidence of surgery, although further validation is necessary.

Refractory Hypertension in Infantile-Onset Denys-Drash Syndrome.

Denys-Drash syndrome is characterized by progressive nephropathy, gonadal dysgenesis, and Wilms tumor caused by a WT1 gene mutation. Infants with Denys-Drash syndrome frequently experience severe hypertension, but detailed clinical manifestations have yet to be clarified. Cases of infantile-onset Denys-Drash syndrome with severe hypertension at our hospital were retrospectively analyzed and the pathogenesis of hypertension was investigated. Six infants who received the diagnosis of Denys-Drash syndrome at the median age of 10 days (range: 2-182 days) were enrolled. Five infants had the complication of severe hypertension within a few days of diagnosis. All the patients showed rapid progression to end-stage renal disease and urgently required dialysis due to anuria/oliguria and hypervolemia with a median duration of 7.5 days (range: 0-17 days) on the day after diagnosis. Even under dialysis, all the patients continued to need antihypertensive treatment. Five patients underwent a preventive nephrectomy for Wilms tumor, and one patient underwent a nephrectomy due to progression to Wilms tumor. Two patients developed hypotension after a nephrectomy. The main causes of hypertension were hypervolemia in the predialysis stage, renin-associated hypertension in the dialysis stage, and multiple factors, including increased plasma catecholamine-associated hypertension in the postnephrectomy dialysis stage. At last the follow-up after bilateral nephrectomy, four of the five patients required antihypertensive treatment. Not all the patients showed target organ complications caused by hypertension. Severe hypertension is a common complication of infantile-onset Denys-Drash syndrome. The possibility of hypotension after nephrectomy should be considered in patients with Denys-Drash syndrome.

A retrospective study on the diagnosis and treatment of dementia in patients referred to the Sagamihara Municipal Medical Center for Dementia for consultation.

AIM: In Japan, the Orange Plan was formulated in 2013 to promote community-based integrated care systems, and in 2015, it was revised as the New Orange Plan. Since the introduction of these programmes, adequate research has not been carried out on how these measures affect regional dementia care. The aim of this study was to investigate the state of community-based dementia treatment through a survey of medical consultation pathways, including dementia diagnosis, at the Sagamihara Municipal Medical Center for Dementia. METHODS: The participants included 1480 patients (585 men, 895 women) who presented for consultation at the Sagamihara Municipal Medical Center for Dementia for a differential diagnosis or treatment of dementia. The relationship between the path leading to medical consultation before pharmacotherapy and post-consultation diagnosis was investigated. RESULTS: Significantly more participants who presented for consultation without a referral were not diagnosed with dementia than diagnosed. Furthermore, among participants referred from a non-psychiatric clinic, significantly more patients were diagnosed with dementia than not. A significant difference was observed in a comparison of facility types and the use or non-use of anti-dementia drugs. Notably, the rate of anti-dementia drug prescriptions was significantly higher in psychiatric hospitals and non-psychiatric clinics. Furthermore, it is possible that approximately 30% of anti-dementia drugs prescribed at each facility were not covered by insurance. CONCLUSION: Community-based integrated care systems aim to promote collaboration within each region aimed. However, appropriate pharmacotherapy methods for dementia patients have not been adequately communicated to non-specialist physicians and local residents. For this reason, human resource solutions are needed to help medical staff deepen their understanding of dementia so that they can better provide dementia support to patients.

Histone modifying genes are involved in the molting period during soldier differentiation in Zootermopsis nevadensis.

Caste differentiation in eusocial insects is an outstanding example of phenotypic plasticity. Recent studies indicate that epigenetic regulation, including DNA methylation and histone modification, play a role in the morphological and behavioral polyphenism observed in the caste differentiation of hymenopteran insects. The role of epigenetic regulation in termite caste differentiation, however, is still obscure. In this study, we performed a functional analysis of epigenetic-related genes during soldier differentiation in Zootermopsis nevadensis, for which the entire genome sequence is available. In an incipient colony of this species, the oldest 3rd instar larva (No. 1 larva) always differentiates into a presoldier (intermediate stage of soldier), and the next-oldest 3rd instar larva (No. 2 larva) molts into a 4th instar (which functions as a worker). First, we detected seven epigenetic-related genes with significantly increased expression levels in the soldier-destined No. 1 larvae using RNA-seq data. Second, RNA interference (RNAi) of these seven genes was performed in the No. 1 larvae. RNAi of three histone modifying genes extended the presoldier molting period. Furthermore, these RNAi treatments reduced the expression levels of genes involved in juvenile hormone (JH) synthesis, binding and signaling. These results indicate that epigenetic-related genes do not directly affect termite soldier differentiation; nonetheless, some histone modifying genes have an effect on molting periods, possibly due to the regulation of JH action during soldier differentiation.

Transcriptomic changes during caste development through social interactions in the termite Zootermopsis nevadensis.

One of the most striking examples of phenotypic plasticity is the different phenotypes (i.e., castes) within a same nest of social insects. Castes usually derive from a single genotype initially by receiving social cues among individuals during development. Specific gene expression changes may be involved in caste differentiation, and thus, the regulatory mechanism of these changes should be clarified in order to understand social maintenance and evolution. The damp-wood termite Zootermopsis nevadensis is one of the most important model termite species, due to not only the availability of genomic, transcriptomic, and epigenomic information but also evidence that soldier- and worker-destined individuals can be identified in natural conditions. Given that the nutritional intakes via social interactions are crucial for caste differentiation in this species, there is a possibility that transcriptomic changes are influenced by the nutritional difference among these individuals. Here, whole body RNA-seq analysis of 3rd-instar larvae with biological replications and Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses were conducted. We found the drastic expression differences during caste developments between soldier- and worker-destined individuals. The results indicated that there are several key signaling pathways responsible for caste formations, which are involved in developments and social interactions. Particularly, the nutritional sensitive signaling was upregulated in soldier-destined individuals, while some metabolic pathways were identified in worker-destined individuals. These bioinformatic data obtained should be utilized to examine the molecular mechanisms of caste determination in social insects.