Dietary supplementation with milk lipids leads to suppression of developmental and behavioral phenotypes of hyperexcitable Drosophila mutants

Dietary modifications often have a profound impact on the penetrance and expressivity of neurological phenotypes that are caused by genetic defects. Our previous studies in Drosophila melanogaster revealed that seizure-like phenotypes of gain-of-function voltage-gated sodium (Na_v) channel mutants (para^Shu, para^bss1, and para^GEFS+), as well as other seizure-prone "bang-sensitive" mutants (eas and sda), were drastically suppressed by supplementation of a standard diet with milk whey. In the current study we sought to determine which components of milk whey are responsible for the diet-dependent suppression of their hyperexcitable phenotypes. Our systematic analysis reveals that supplementing the diet with a modest amount of milk lipids (0.26% w/v) mimics the effects of milk whey. We further found that a minor milk lipid component, α-linolenic acid, contributed to the diet-dependent suppression of adult para^Shu phenotypes. Given that lipid supplementation during the larval stages effectively suppressed adult para^Shu phenotypes, dietary lipids likely modify neural development to compensate for the defects caused by the mutations. Consistent with this notion, lipid feeding fully rescued abnormal dendrite development of class IV sensory neurons in para^Shu larvae. Overall, our findings demonstrate that milk lipids are sufficient to ameliorate hyperexcitable phenotypes in Drosophila mutants, providing a foundation for future investigation of the molecular and cellular mechanisms by which dietary lipids modify genetically induced abnormalities in neural development, physiology, and behavior.

Deficits in the vesicular acetylcholine transporter alter lifespan and behavior in adult Drosophila melanogaster

The neurotransmitter acetylcholine (ACh) is involved in critical organismal functions that include locomotion and cognition. Importantly, alterations in the cholinergic system are a key underlying factor in cognitive defects associated with aging. One essential component of cholinergic synaptic transmission is the vesicular ACh transporter (VAChT), which regulates the packaging of ACh into synaptic vesicles for extracellular release. Mutations that cause a reduction in either protein level or activity lead to diminished locomotion ability whereas complete loss of function of VAChT is lethal. While much is known about the function of VAChT, the direct role of altered ACh release and its association with either an impairment or an enhancement of cognitive function are still not fully understood. We hypothesize that point mutations in Vacht cause age-related deficits in cholinergic-mediated behaviors such as locomotion, and learning and memory. Using Drosophila melanogaster as a model system, we have studied several mutations within Vacht and observed their effect on survivability and locomotive behavior. Here we report for the first time a weak hypomorphic Vacht allele that shows a differential effect on ACh-linked behaviors. We also demonstrate that partially rescued Vacht point mutations cause an allele-dependent deficit in lifespan and defects in locomotion ability. Moreover, using a thorough data analytics strategy to identify exploratory behavioral patterns, we introduce new paradigms for measuring locomotion-related activities that could not be revealed or detected by a simple measure of the average speed alone. Together, our data indicate a role for VAChT in the maintenance of longevity and locomotion abilities in Drosophila and we provide additional measurements of locomotion that can be useful in determining subtle changes in Vacht function on locomotion-related behaviors.

Significance of DopEcR, a G-protein coupled dopamine/ecdysteroid receptor, in physiological and behavioral response to stressors

Organisms respond to various environmental stressors by modulating physiology and behavior to maintain homeostasis. Steroids and catecholamines are involved in the highly conserved signaling pathways crucial for mounting molecular and cellular events that ensure immediate or long-term survival under stress conditions. The insect dopamine/ecdysteroid receptor (DopEcR) is a dual G-protein coupled receptor for the catecholamine dopamine and the steroid hormone ecdysone. DopEcR acts in a ligand-dependent manner, mediating dopaminergic signaling and unconventional "nongenomic" ecdysteroid actions through various intracellular signaling pathways. This unique feature of DopEcR raises the interesting possibility that DopEcR may serve as an integrative hub for complex molecular cascades activated under stress conditions. Here, we review previously published studies of Drosophila DopEcR in the context of stress response and also present newly discovered DopEcR loss-of-function phenotypes under different stress conditions. These findings provide corroborating evidence that DopEcR plays vital roles in responses to various stressors, including heat, starvation, alcohol, courtship rejection, and repeated neuronal stimulation in Drosophila. We further discuss what is known about DopEcR in other insects and DopEcR orthologs in mammals, implicating their roles in stress responses. Overall, this review highlights the importance of dual GPCRs for catecholamines and steroids in modulating physiology and behavior under stress conditions. Further multidisciplinary studies of Drosophila DopEcR will contribute to our basic understanding of the functional roles and underlying mechanisms of this class of GPCRs.

Milk-whey diet substantially suppresses seizure-like phenotypes of paraShu, a Drosophila voltage-gated sodium channel mutant

The Drosophila mutant para^Shu harbors a dominant, gain-of-function allele of the voltage-gated sodium channel gene, paralytic (para). The mutant flies display severe seizure-like phenotypes, including neuronal hyperexcitability, spontaneous spasms, ether-induced leg shaking, and heat-induced convulsions. We unexpectedly found that two distinct food recipes used routinely in the Drosophila research community result in a striking difference in severity of the para^Shu phenotypes. Namely, when para^Shu mutants were raised on the diet originally formulated by Edward Lewis in 1960, they showed severe neurological defects as previously reported. In contrast, when they were raised on the diet developed by Frankel and Brousseau in 1968, these phenotypes were substantially suppressed. Comparison of the effects of these two well-established food recipes revealed that the diet-dependent phenotypic suppression is accounted for by milk whey, which is present only in the latter. Inclusion of milk whey in the diet during larval stages was critical for suppression of the adult para^Shu phenotypes, suggesting that this dietary modification affects development of the nervous system. We also found that milk whey has selective effects on other neurological mutants. Among the behavioral phenotypes of different para mutant alleles, those of para^GEFS+ and para^bss were suppressed by milk whey, while those of para^DS and para^ts1 were not significantly affected. Overall, our study demonstrates that different diets routinely used in Drosophila labs could have considerably different effects on neurological phenotypes of Drosophila mutants. This finding provides a solid foundation for further investigation into how dietary modifications affect development and function of the nervous system and, ultimately, how they influence behavior.

Evolutionarily Conserved Roles for Blood-Brain Barrier Xenobiotic Transporters in Endogenous Steroid Partitioning and Behavior

Central nervous system (CNS) chemical protection depends upon discrete control of small-molecule access by the blood-brain barrier (BBB). Curiously, some drugs cause CNS side-effects despite negligible transit past the BBB. To investigate this phenomenon, we asked whether the highly BBB-enriched drug efflux transporter MDR1 has dual functions in controlling drug and endogenous molecule CNS homeostasis. If this is true, then brain-impermeable drugs could induce behavioral changes by affecting brain levels of endogenous molecules. Using computational, genetic, and pharmacologic approaches across diverse organisms, we demonstrate that BBB-localized efflux transporters are critical for regulating brain levels of endogenous steroids and steroid-regulated behaviors (sleep in Drosophila and anxiety in mice). Furthermore, we show that MDR1-interacting drugs are associated with anxiety-related behaviors in humans. We propose a general mechanism for common behavioral side effects of prescription drugs: pharmacologically challenging BBB efflux transporters disrupts brain levels of endogenous substrates and implicates the BBB in behavioral regulation.

Mutation of orthologous prickle genes causes a similar epilepsy syndrome in flies and humans

OBJECTIVE

Genetically tractable fruit flies have been used for decades to study seizure disorders. However, there is a paucity of data specifically correlating fly and human seizure phenotypes. We have previously shown that mutation of orthologous PRICKLE genes from flies to humans produce seizures. This study aimed to determine whether the prickle-mediated seizure phenotypes in flies closely parallel the epilepsy syndrome found in PRICKLE patients.

METHODS

Virtually all fly seizure studies have relied upon characterizing seizures that are evoked. We have developed two novel approaches to more precisely characterize seizure-related phenotypes in their native state in prickle mutant flies. First, we used high-resolution videography to document spontaneous, unprovoked seizure events. Second, we developed a locomotion coordination assay to assess whether the prickle mutant flies were ataxic. Third, we treated the mutant flies with levetiracetam to determine whether the behavioral phenotypes could be suppressed by a common antiepileptic drug.

RESULTS

We find that the prickle mutant flies exhibit myoclonic-like spontaneous seizure events and are severely ataxic. Both these phenotypes are found in human patients with PRICKLE mutations, and can be suppressed by levetiracetam, providing evidence that the phenotypes are due to neurological dysfunction. These results document for the first time spontaneous, unprovoked seizure events at high resolution in a fly human seizure disorder model, capturing seizures in their native state.

INTERPRETATION

Collectively, these data underscore the striking similarities between the fly and human PRICKLE-mediated epilepsy syndromes, and provide a genetically tractable model for dissecting the underlying causes of the human syndromic phenotypes.

Specific clinical signs and symptoms are predictive of clinical course in sporadic Creutzfeldt-Jakob disease

Background and purpose

Akinetic mutism is thought to be an appropriate therapeutic end‐point in patients with sporadic Creutzfeldt−Jakob disease (sCJD). However, prognostic factors for akinetic mutism are unclear and clinical signs or symptoms that precede this condition have not been defined. The goal of this study was to identify prognostic factors for akinetic mutism and to clarify the order of clinical sign and symptom development prior to its onset.

Methods

The cumulative incidence of akinetic mutism and other clinical signs and symptoms was estimated based on Japanese CJD surveillance data (455 cases) collected from 2003 to 2008. A proportional hazards model was used to identify prognostic factors for the time to onset of akinetic mutism and other clinical signs and symptoms.

Results

Periodic synchronous discharges on electroencephalography were present in the majority of cases (93.5%). The presence of psychiatric symptoms or cerebellar disturbance at sCJD diagnosis was associated with the development of akinetic mutism [hazard ratio (HR) 1.50, 95% confidence interval (CI) 1.14–1.99, and HR 2.15, 95% CI1.61–2.87, respectively]. The clinical course from cerebellar disturbance to myoclonus or akinetic mutism was classified into three types: (i) direct path, (ii) path via pyramidal or extrapyramidal dysfunction and (iii) path via psychiatric symptoms or visual disturbance.

Conclusions

The presence of psychiatric symptoms or cerebellar disturbance increased the risk of akinetic mutism of sCJD cases with probable MM/MV subtypes. Also, there appear to be sequential associations in the development of certain clinical signs and symptoms of this disease.

In Vivo Functional Brain Imaging Approach Based on Bioluminescent Calcium Indicator GFP-aequorin

Functional in vivo imaging has become a powerful approach to study the function and physiology of brain cells and structures of interest. Recently a new method of Ca(2+)-imaging using the bioluminescent reporter GFP-aequorin (GA) has been developed. This new technique relies on the fusion of the GFP and aequorin genes, producing a molecule capable of binding calcium and - with the addition of its cofactor coelenterazine - emitting bright light that can be monitored through a photon collector. Transgenic lines carrying the GFP-aequorin gene have been generated for both mice and Drosophila. In Drosophila, the GFP-aequorin gene has been placed under the control of the GAL4/UAS binary expression system allowing for targeted expression and imaging within the brain. This method has subsequently been shown to be capable of detecting both inward Ca(2+)-transients and Ca(2+)-released from inner stores. Most importantly it allows for a greater duration in continuous recording, imaging at greater depths within the brain, and recording at high temporal resolutions (up to 8.3 msec). Here we present the basic method for using bioluminescent imaging to record and analyze Ca(2+)-activity within the mushroom bodies, a structure central to learning and memory in the fly brain.

Exaggerated Nighttime Sleep and Defective Sleep Homeostasis in a Drosophila Knock-In Model of Human Epilepsy

Despite an established link between epilepsy and sleep behavior, it remains unclear how specific epileptogenic mutations affect sleep and subsequently influence seizure susceptibility. Recently, Sun et al. (2012) created a fly knock-in model of human generalized epilepsy with febrile seizures plus (GEFS+), a wide-spectrum disorder characterized by fever-associated seizing in childhood and lifelong affliction. GEFS+ flies carry a disease-causing mutation in their voltage-gated sodium channel (VGSC) gene and display semidominant heat-induced seizing, likely due to reduced GABAergic inhibitory activity at high temperature. Here, we show that at room temperature the GEFS+ mutation dominantly modifies sleep, with mutants exhibiting rapid sleep onset at dusk and increased nighttime sleep as compared to controls. These characteristics of GEFS+ sleep were observed regardless of sex, mating status, and genetic background. GEFS+ mutant sleep phenotypes were more resistant to pharmacologic reduction of GABA transmission by carbamazepine (CBZ) than controls, and were mitigated by reducing GABAA receptor expression specifically in wake-promoting pigment dispersing factor (PDF) neurons. These findings are consistent with increased GABAergic transmission to PDF neurons being mainly responsible for the enhanced nighttime sleep of GEFS+ mutants. Additionally, analyses under other light conditions suggested that the GEFS+ mutation led to reduced buffering of behavioral responses to light on and off stimuli, which contributed to characteristic GEFS+ sleep phenotypes. We further found that GEFS+ mutants had normal circadian rhythms in free-running dark conditions. Interestingly, the mutants lacked a homeostatic rebound following mechanical sleep deprivation, and whereas deprivation treatment increased heat-induced seizure susceptibility in control flies, it unexpectedly reduced seizure activity in GEFS+ mutants. Our study has revealed the sleep architecture of a Drosophila VGSC mutant that harbors a human GEFS+ mutation, and provided unique insight into the relationship between sleep and epilepsy.

Modulation of innate and learned sexual behaviors by the TRP channel Painless expressed in the fruit fly brain: behavioral genetic analysis and its implications

Transient receptor potential (TRP) channels have attracted considerable attention because of their vital roles in primary sensory neurons, mediating responses to a wide variety of external environmental stimuli. However, much less is known about how TRP channels in the brain respond to intrinsic signals and are involved in neurophysiological processes that control complex behaviors. Painless (Pain) is the Drosophila TRP channel that was initially identified as a molecular sensor responsible for detecting noxious thermal and mechanical stimuli. Here, we review recent behavioral genetic studies demonstrating that Pain expressed in the brain plays a critical role in both innate and learned aspects of sexual behaviors. Several members of the TRP channel superfamily play evolutionarily conserved roles in sensory neurons as well as in other peripheral tissues. It is thus expected that brain TRP channels in vertebrates and invertebrates would have some common physiological functions. Studies of Pain in the Drosophila brain using a unique combination of genetics and physiological techniques should provide valuable insights into the fundamental principles concerning TRP channels expressed in the vertebrate and invertebrate brains.

Insulin-producing cells regulate the sexual receptivity through the painless TRP channel in Drosophila virgin females

In a variety of animal species, females hold a leading position in evaluating potential mating partners. The decision of virgin females to accept or reject a courting male is one of the most critical steps for mating success. In the fruitfly Drosophila melanogaster, however, the molecular and neuronal mechanisms underlying female receptivity are still poorly understood, particularly for virgin females. The Drosophila painless (pain) gene encodes a transient receptor potential (TRP) ion channel. We previously demonstrated that mutations in pain significantly enhance the sexual receptivity of virgin females and that pain expression in pain^GAL4-positive neurons is necessary and sufficient for pain-mediated regulation of the virgin receptivity. Among the pain^GAL4-positive neurons in the adult female brain, here we have found that insulin-producing cells (IPCs), a neuronal subset in the pars intercerebralis, are essential in virgin females for the regulation of sexual receptivity through Pain TRP channels. IPC-specific knockdown of pain expression or IPC ablation strongly enhanced female sexual receptivity as was observed in pain mutant females. When pain expression or neuronal activity was conditionally suppressed in adult IPCs, female sexual receptivity was similarly enhanced. Furthermore, both pain mutations and the conditional knockdown of pain expression in IPCs depressed female rejection behaviors toward courting males. Taken together, our results indicate that the Pain TRP channel in IPCs plays an important role in controlling the sexual receptivity of Drosophila virgin females by positively regulating female rejection behaviors during courtship.

A novel role for ecdysone in Drosophila conditioned behavior: linking GPCR-mediated non-canonical steroid action to cAMP signaling in the adult brain

The biological actions of steroid hormones are mediated primarily by their cognate nuclear receptors, which serve as steroid-dependent transcription factors. However, steroids can also execute their functions by modulating intracellular signaling cascades rapidly and independently of transcriptional regulation. Despite the potential significance of such "non-genomic" steroid actions, their biological roles and the underlying molecular mechanisms are not well understood, particularly with regard to their effects on behavioral regulation. The major steroid hormone in the fruit fly Drosophila is 20-hydroxy-ecdysone (20E), which plays a variety of pivotal roles during development via the nuclear ecdysone receptors. Here we report that DopEcR, a G-protein coupled receptor for ecdysteroids, is involved in activity- and experience-dependent plasticity of the adult central nervous system. Remarkably, a courtship memory defect in rutabaga (Ca²⁺/calmodulin-responsive adenylate cyclase) mutants was rescued by DopEcR overexpression or acute 20E feeding, whereas a memory defect in dunce (cAMP-specific phosphodiestrase) mutants was counteracted when a loss-of-function DopEcR mutation was introduced. A memory defect caused by suppressing dopamine synthesis was also restored through enhanced DopEcR-mediated ecdysone signaling, and rescue and phenocopy experiments revealed that the mushroom body (MB)--a brain region central to learning and memory in Drosophila--is critical for the DopEcR-dependent processing of courtship memory. Consistent with this finding, acute 20E feeding induced a rapid, DopEcR-dependent increase in cAMP levels in the MB. Our multidisciplinary approach demonstrates that DopEcR mediates the non-canonical actions of 20E and rapidly modulates adult conditioned behavior through cAMP signaling, which is universally important for neural plasticity. This study provides novel insights into non-genomic actions of steroids, and opens a new avenue for genetic investigation into an underappreciated mechanism critical to behavioral control by steroids.

Significance of the centrally expressed TRP channel painless in Drosophila courtship memory

Considerable evidence has demonstrated that transient receptor potential (TRP) channels play vital roles in sensory neurons, mediating responses to various environmental stimuli. In contrast, relatively little is known about how TRP channels exert their effects in the central nervous system to control complex behaviors. This is also true for the Drosophila TRP channel encoded by painless (pain). The Pain TRP channel is expressed in a subset of sensory neurons and involved in behavioral responses to thermal, chemical, and mechanical stimuli. Its physiological roles in brain neurons, however, remain largely elusive. Using multiple mutant alleles and tranformants for pain, here we demonstrate that the brain-expressed Pain TRP channel is required for long-term memory (LTM), but not for short-lasting memory, induced by courtship conditioning in adult males. The courtship LTM phenotype in pain mutants was rescued by expressing wild-type pain temporarily, prior to conditioning, in adult flies. In addition, targeted expression of painRNAi in either the mushroom bodies (MBs) or insulin-producing cells (IPCs) resulted in defective courtship LTM. These results indicate that the Pain TRP channels in the MBs and IPCs control neuronal plasticity that is required for the formation of a certain type of long-lasting associative memory in Drosophila.

Fan-shaped body neurons are involved in period-dependent regulation of long-term courtship memory in Drosophila

In addition to its established function in the regulation of circadian rhythms, the Drosophila gene period (per) also plays an important role in processing long-term memory (LTM). Here, we used courtship conditioning as a learning paradigm and revealed that (1) overexpression and knocking down of per in subsets of brain neurons enhance and suppress LTM, respectively, and (2) suppression of synaptic transmission during memory retrieval in the same neuronal subsets leads to defective LTM. Further analysis strongly suggests that the brain region critical for per-dependent LTM regulation is the fan-shaped body, which is involved in sleep-induced enhancement of courtship LTM.

Factors that Differentially Affect Daytime and Nighttime Sleep in Drosophila melanogaster

Rest in the fruit fly Drosophila melanogaster has key characteristics of mammalian sleep and is thus considered as a fly version of sleep. Drosophila sleep has been studied extensively, with the aim of gaining fundamental insights into the evolutionarily conserved functions of sleep as well as the mechanisms that regulate it. An interesting question that has not yet been addressed is whether fly sleep can be classified into distinct sleep types, each having particular biological roles – like rapid eye movement (REM) and non-REM sleep in birds and mammals. Typically, Drosophila sleep displays a bimodal pattern, consisting of distinct daytime and nighttime components. Notably, daytime and nighttime sleep differ with respect to several qualities, such as sleep-bout lengths and arousal thresholds. In this short review, we describe several genetic and environmental factors that differentially affect daytime and nighttime sleep, highlighting the observations suggesting the notion that these temporally distinct components of Drosophila sleep may have unique biological functions and be regulated by different homeostatic regulatory mechanisms.

Construction of recombinant monoclonal antibodies from a chicken hybridoma line secreting specific antibody

The chicken is a useful animal for the development of the specificantibodies against the mammalian conserved proteins. We generated twotypes of recombinant chicken monoclonal antibodies (mAbs), using a phagedisplay technique from a chicken hybridoma HUC2-13 which secreted themAb to the N-terminal of the mammalian prion protein (PrP). Althoughthe mAb HUC2-13 is a useful antibody for the prion research, thehybridoma produces a low level of antibody production. In order to producea large amount of the mAb, we have constructed a single chain fragmentvariable region (scF(V)) mAb by using the variable heavy(V(H)) and light (V(L))genes which were amplified by using the two primer pairs and theflexible linker. The two phage display mAbs (HUC2p3 and HUC2p5)expressed on a M13 filamentous phage and their soluble type mAbs(HUC2s3 and HUC2s5) were reacted with the PrP peptide antigen in theELISA. In the Western blot analysis, the mAbs HUC2p3 and HUC2s3 wereas reactive to PrP(c) from mouse brains as the mAb HUC2-13 was. The nucleotide sequences of V(H) and V(L) genes from HUC2-13 and the two cloneswere identical except for only one residue. These results indicate that themethods presented here provide an effective tool for the improvement ofthe low levels of antibody production in the chicken hybridoma system.

Beyond molting--roles of the steroid molting hormone ecdysone in regulation of memory and sleep in adult Drosophila

The molting hormone 20-hydroxyecdysone (20E) is an active metabolite of ecdysone and plays vital roles during ontogeny of the fruit fly Drosophila, coordinating critical developmental transitions such as molting and metamorphosis. Although 20E is known to exist throughout life in both male and female flies, its functions in adult physiology and behavior remain largely elusive. Notably, findings from previous studies suggest that this hormone may be involved in adult stress responses. Consistent with this possibility, we have found that ecdysone signaling in adult flies is activated by "stressful" social interactions and plays a role in the formation of long-term courtship memory [Ishimoto et al. (2009). Ecdysone signaling regulates the formation of long-term courtship memory in adult Drosophila melanogaster. PNAS 106, 6381-6386]. In addition, we recently reported that ecdysone signaling contributes to the regulation of sleep, affecting transitions between sleep and wakefulness [Ishimoto and Kitamoto. (2010). The steroid molting hormone ecdysone regulates sleep in adult Drosophila melanogaster. Genetics 185, 269-281]. Here in Extra Views, we first summarize our findings on the unconventional roles of 20E in regulating memory and sleep in adult flies. We then discuss speculative ideas concerning the stress hormone-like features of 20E, as well as the possibility that ecdysone signaling contributes to remodeling of the adult nervous system, at both the functional and structural levels, through epigenetic mechanisms.

Actions of the Japanese Pancreas and Islet Transplantation Association regarding transplanted human islets isolated using Liberase HI

PURPOSE

The potential for introducing transmissible spongiform encephalopathy (TSE) into islet cells was indicated by recognizing that Liberase HI is isolated from Clostridium histolyticum grown in media containing brain-heart infusion broth. A national team within the Japanese Pancreas and Islet Transplantation Association implemented an islet transplantation program in Japan using Liberase HI. The program comprised 65 islet isolations from non-heart-beating donors and 34 transplants into 18 patients. Herein, we have summarized how the Association followed these recipients over the long term.

PROCEDURES

We established an ad hoc committee to follow recipients transplanted with islets isolated using Liberase HI after becoming informed of the associated dangers of using this enzyme. We also stopped islet transplantations using Liberase. The committee addressed the major concerns of the risk of the collagenase being contaminated with TSE and of the recipient follow-up. All recipients were examined by diffusion MRI and EEG and then scheduled for evaluation and follow-up by specialists in Creutzfeldt-Jakob disease (CJD). Bioassays of bovine spongiform encephalopathy prions in the enzyme proceeded using knock-in mice expressing bovine prion protein. These assays could detect contaminating prions at a dilution of 1 × 10(4). After inactivating its collagenase activity, Liberase HI was injected into the abdominal cavities of knock-in mice. Four months later, prion infectivity in Liberase HI was evaluated by immunohistochemical staining and Western blotting of spleen homogenates using anti-prion protein antibodies.

MAIN FINDINGS

Western blotting and immunohistochemical staining did not detect prions in Liberase HI. Diffusion MRI and EEG evaluations performed by CJD specialists confirmed that none of the transplanted recipients had CJD.

CONCLUSIONS

Three years of follow-up revealed that none of the Japanese recipients of islet transplants developed CJD. Prion bioassays showed that the Liberase HI used to isolate islets for transplantation was free of infectious TSE prions.

Survival to akinetic mutism state in Japanese cases of MM1-type sporadic Creutzfeldt-Jakob disease is similar to Caucasians

BACKGROUND

It is not known whether the clinical course of Japanese sporadic Creutzfeldt-Jakob disease (sCJD) cases differs from that of Caucasian sCJD cases.

PATIENTS AND METHODS

To investigate the clinical course of Japanese sCJD, clinical findings from 29 patients with Japanese MM1-type sCJD were retrospectively evaluated and compared to Caucasian sCJD findings.

RESULTS

Survival of Japanese MM1-type sCJD up to the time of akinetic mutism state is similar to that of Caucasian subjects. However, the total disease duration of Japanese patients was approximately three times longer.

CONCLUSIONS

The present observations indicate that Japanese sCJD cases generally show a longer disease duration because of the longer survival period after reaching the akinetic mutism state.

Differential expression of CD44 variants among meningioma subtypes

Aims/background-CD44 is a widely distributed cell surface molecule which has numerous isoforms generated by alternative splicing. The diverse functions related to the CD44 variants (CD44v) have been reported in various physiological and pathological conditions. The pattern of expression of CD44v among meningioma subtypes was investigated to ascertain whether CD44 variants play a role in a variety of biological processes, such as epithelial differentiation and extracranial metastasis.Methods-Twenty three meningiomas were studied immunohistochemically using novel antibodies directed against CD44 isoforms. Six of the 23 samples were analysed by reverse transcription polymerase chain reaction (RT-PCR), followed by Southern blotting with CD44v specific probes.Results-In meningothelial, fibrous and anaplastic meningiomas, a standard form of CD44 was detected by RT-PCR and was homogeneously expressed in tumour cells when studied immunohistochemically. CD44v was not detected in these subtypes. In secretory meningiomas, however, CD44v isoforms were strongly expressed in the cell clusters that produce secretory granules and also accumulated in the granules. The population of tumour cells immunopositive for CD44v was similar to that which stained with antibodies directed against carcinoembryonic antigen, epithelial membrane antigen and ezrin. On RT-PCR with Southern blotting, only the secretory type showed high level expression of CD44v.Conclusions-CD44v in meningiomas is expressed in relation to tumour cell differentiation towards the epithelial type.

The amnesiac gene is involved in the regulation of thermal nociception in Drosophila melanogaster

Nociception is a mechanism fundamental to the ability of animals to avoid noxious stimuli capable of causing serious tissue damage. It has been established that in the fruit fly Drosophila melanogaster, the transient receptor potential (TRP) channel encoded by the painless gene (pain) is required for detecting thermal and mechanical noxious stimuli. Little is known, however, about other genetic components that control nociceptive behaviors in Drosophila. The amnesiac gene (amn), which encodes a putative neuropeptide precursor, is important for stabilizing olfactory memory, and is involved in various aspects of other associative and nonassociative learning. Previous studies have indicated that amn also regulates ethanol sensitivity and sleep. Here the authors show that amn plays an additional critical role in nociception. Their data show that amn mutant larvae and adults are significantly less responsive to noxious heat stimuli (greater than approximately 40 degrees C) than their wild-type counterparts. The phenotype of amn mutants in thermal nociception, which closely resembles that of pain mutants, was phenocopied in flies expressing amn RNAi, and this phenotype was rescued by the expression of a wild-type amn transgene. These results provide compelling evidence that amn is a novel genetic component of the mechanism that regulates thermal nociception in Drosophila.

Less protease-resistant PrP in a patient with sporadic CJD treated with intraventricular pentosan polysulphate

Treatment with intraventricular pentosan polysulphate (PPS) might be beneficial in patients with Creutzfeldt-Jakob disease. We report a 68-year-old woman with sporadic Creutzfeldt-Jakob disease who received continuous intraventricular PPS infusion (1-120 microg/kg/day) for 17 months starting 10 months after the onset of clinical symptoms. Treatment with PPS was well tolerated but was associated with a minor, transient intraventricular hemorrhage and a non-progressive collection of subdural fluid. The patient's overall survival time was well above the mean time expected for the illness but still within the normal range. Post-mortem examination revealed that the level of abnormal protease-resistant prion protein in the brain was markedly decreased compared with levels in brains without PPS treatment. These findings suggest that intraventricular PPS infusion might modify the accumulation of abnormal prion proteins in the brains of patients with sporadic Creutzfeldt-Jakob disease.

Changes in expression of sensory organ-specific microRNAs in rat dorsal root ganglia in association with mechanical hypersensitivity induced by spinal nerve ligation

Chronic neuropathic pain caused by peripheral nerve injury is associated with global changes in gene expression in damaged neurons. To understand the molecular mechanisms underlying neuropathic pain, it is essential to elucidate how nerve injury alters gene expression and how the change contributes to the development and maintenance of chronic pain. MicroRNAs are non-protein-coding RNA molecules that regulate gene expression in a wide variety of biological processes mainly at the level of translation. This study investigated the possible involvement of microRNAs in gene regulation relevant to neuropathic pain. The analyses focused on a sensory organ-specific cluster of microRNAs that includes miR-96, -182, and -183. Quantitative real-time polymerase chain reaction (qPCR) analyses confirmed that these microRNAs were highly enriched in the dorsal root ganglion (DRG) of adult rats. Using the L5 spinal nerve ligation (SNL) model of chronic neuropathic pain, we observed a significant reduction in expression of these microRNAs in injured DRG neurons compared to controls. In situ hybridization and immunohistochemical analyses revealed that these microRNAs are expressed in both myelinated (N52 positive) and unmyelinated (IB4 positive) primary afferent neurons. They also revealed that the intracellular distributions of the microRNAs in DRG neurons were dramatically altered in animals with mechanical hypersensitivity. Whereas microRNAs were uniformly distributed within the DRG soma of non-allodynic animals, they were preferentially localized to the periphery of neurons in allodynic animals. The redistribution of microRNAs was associated with changes in the distribution of the stress granule (SG) protein, T-cell intracellular antigen 1 (TIA-1). These data demonstrate that SNL induces changes in expression levels and patterns of miR-96, -182, and -183, implying their possible contribution to chronic neuropathic pain through translational regulation of pain-relevant genes. Moreover, SGs were suggested to be assembled and associated with microRNAs after SNL, which may play a role in modification of microRNA-mediated gene regulation in DRG neurons.

Neuronal mechanisms of learning and memory revealed by spatial and temporal suppression of neurotransmission using shibire, a temperature-sensitive dynamin mutant gene in Drosophila melanogaster

The fruit fly Drosophila melanogaster is an excellent model organism to identify genes and genetic pathways important for learning and memory. However, its small size makes surgical treatment and electrophysiological manipulation technically difficult, hampering the functional analysis of neuronal circuits that play critical roles in memory processing. To circumvent this problem, we developed a unique experimental strategy that uses the temperature-sensitive allele of the Drosophila dynamin gene, shibire(ts1) (shi(ts1)), in combination with the GAL4/UAS expression system. This strategy allows for rapid and reversible perturbation of synaptic neurotransmission in identifiable neurons, and analysis of the behavioral consequences of such manipulation in free-moving animals. Since its introduction in 2001, this GAL4/UAS-shi(ts1) strategy has been widely used to study the neuronal basis of learning and memory. This review focuses on how this strategy has revitalized Drosophila memory research, and contributed to our understanding of dynamic neuronal processes that control various aspects of memory.

A putative amino acid transporter of the solute carrier 6 family is upregulated by lithium and is required for resistance to lithium toxicity in Drosophila

Lithium is an efficacious drug for the treatment of mood disorders, and its application is also considered a potential therapy for brain damage. However, the mechanisms underlying lithium's therapeutic action and toxic effects in the nervous system remain largely elusive. Here we report on the use of a versatile genetic model, the fruit fly Drosophila melanogaster, to discover novel molecular components involved in the lithium-responsive neurobiological process. We previously identified CG15088, which encodes a putative nutrient amino acid transporter of the solute carrier 6 (SLC6) family, as one of the genes most significantly upregulated in response to lithium treatment. This gene was the only SLC6 gene induced by lithium, and was thus designated as Lithium-inducible SLC6 transporter or List. Either RNA interference (RNAi)-mediated knockdown or complete deletion of List resulted in a remarkable increase in the susceptibility of adult flies to lithium's toxic effects, whereas transgenic expression of wild-type List significantly suppressed the lithium hypersensitive phenotype of List-deficient flies. Other ions such as sodium, potassium and chloride did not induce List upregulation, nor did they affect the viability of flies with suppressed List expression. These results indicate that lithium's biochemical or physical properties, rather than general osmotic responses, are responsible for the lithium-induced upregulation of List, as well as for the lithium-susceptible phenotype observed in List knockdown flies. Interestingly, flies became significantly more susceptible to lithium toxicity when List RNAi was specifically expressed in glia than when it was expressed in neurons or muscles, which is consistent with potential glial expression of List. These results show that the List transporter confers resistance to lithium toxicity, possibly as a consequence of its amino acid transporter activity in CNS glia. Our results have provided a new avenue of investigation toward a better understanding of the molecular and cellular mechanisms that underlie lithium-responsive neurobiological process.

The Drosophila TRPA channel, Painless, regulates sexual receptivity in virgin females

Transient receptor potential (TRP) channels play crucial roles in sensory perception. Expression of the Drosophila painless (pain) gene, a homolog of the mammalian TRPA1/ANKTM1 gene, in the peripheral nervous system is required for avoidance behavior of noxious heat or wasabi. In this study, we report a novel role of the Pain TRP channel expressed in the nervous system in the sexual receptivity in Drosophila virgin females. Compared with wild-type females, pain mutant females copulated with wild-type males significantly earlier. Wild-type males showed comparable courtship latency and courtship index toward wild-type and pain mutant females. Therefore, the early copulation observed in wild-type male and pain mutant female pairs is the result of enhanced sexual receptivity in pain mutant females. Involvement of pain in enhanced female sexual receptivity was confirmed by rescue experiments in which expression of a pain transgene in a pain mutant background restored the female sexual receptivity to the wild-type level. Targeted expression of pain RNA interference (RNAi) in putative cholinergic or GABAergic neurons phenocopied the mutant phenotype of pain females. However, target expression of pain RNAi in dopaminergic neurons did not affect female sexual receptivity. In addition, conditional suppression of neurotransmission in putative GABAergic neurons resulted in a similar enhanced sexual receptivity. Our results suggest that Pain TRP channels expressed in cholinergic and/or GABAergic neurons are involved in female sexual receptivity.

Effects of lithium chloride on the gene expression profiles in Drosophila heads

To gain insight into the basic neurobiological processes regulated by lithium--an effective drug for bipolar disorder--we used Affymetrix Genome Arrays to examine lithium-induced changes in genome-wide gene expression profiles of head mRNA from the genetic model organism Drosophila melanogaster. First, to identify the individual genes whose transcript levels are most significantly altered by lithium, we analyzed the microarray data with stringent criteria (fold change>2; p<0.001) and evaluated the results by RT-PCR. This analysis identified 12 genes that encode proteins with various biological functions, including an enzyme responsible for amino acid metabolism and a putative amino acid transporter. Second, to uncover the biological pathways involved in lithium's action in the nervous system, we used less stringent criteria (fold change>1.2; FDR<0.05) and assigned the identified 66 lithium-responsive genes to biological pathways using DAVID (Database for Annotation, Visualization and Integrated Discovery). The gene ontology categories most significantly affected by lithium were amino acid metabolic processes. Taken together, these data suggest that amino acid metabolism is important for lithium's actions in the nervous system, and lay a foundation for future functional studies of lithium-responsive neurobiological processes using the versatile molecular and genetic tools that are available in Drosophila.

Clinical features and diagnosis of dura mater graft-associated Creutzfeldt-Jakob disease

BACKGROUND

A subset of patients with dura mater graft-associated Creutzfeldt-Jakob disease (dCJD) demonstrates atypical clinical features and plaque formation in the brain (plaque type).

OBJECTIVE

To elucidate the frequency and clinical features of plaque type dCJD in comparison with the non-plaque type.

METHODS

We analyzed clinicopathologic findings of 66 patients who had been registered as having dCJD by the Creutzfeldt-Jakob Disease Surveillance Committee, Japan, between April 1999 and February 2006.

RESULTS

1) Analysis of pathologically confirmed dCJD patients (n = 23) demonstrated plaque type dCJD in 11 patients (48%). In contrast to the non-plaque type with classic CJD features, the plaque type commonly presented with ataxic gait as an initial manifestation, relatively slow progression of neurologic symptoms, and no or late occurrence of periodic sharp-wave complexes (PSWCs) on EEG. MRI, especially diffusion-weighted images, and CSF 14-3-3 protein and neuron specific enolase (NSE) showed high diagnostic sensitivities for plaque as well as non-plaque types. 2) Analysis of clinically diagnosed dCJD patients (n = 34) demonstrated that 7 patients (21%) had atypical clinical features without PSWCs, probably corresponding to plaque type dCJD.

CONCLUSION

The frequency of the plaque type in dura mater graft-associated Creutzfeldt-Jakob disease is apparently higher than previously recognized. For the clinical diagnosis of the plaque type dura mater graft-associated Creutzfeldt-Jakob disease, MRI and CSF markers would be useful, in addition to the core features, i.e., onset with ataxic gait disturbance, relatively slow progression, and no or late occurrence of periodic sharp-wave complexes on EEG.

Drosophila cholinergic neurons and processes visualized with Gal4/UAS-GFP

Using 7.4 kb of 5' flanking DNA from the Drosophila cholinergic gene locus to drive Gal4 expression we can visualize essentially all cholinergic neurons and neuropiles after genetic recombination with a UAS-GFP (S65T) reporter gene. In contrast to previous methods somata and neuropiles can be observed in the same samples. Fluorescence intensity is strong enough to allow observations in live animals at all developmental stages. Three-dimensional reconstructions made from confocal sections of whole-mount preparations reveal the extensive cholinergic connections among various regions of the nervous system.

Differential roles of two major brain structures, mushroom bodies and central complex, for Drosophila male courtship behavior

Drosophila male courtship is a complex and robust behavior, the potential for which is genetically built into specific neural circuits in the central nervous system. Previous studies using male-female mosaics and the flies with defects in particular brain structures implicated the critical central regions involved in male courtship behavior. However, their acute physiological roles in courtship regulation still largely remain unknown. Using the temperature-sensitive Dynamin mutation, shibire(ts1), here we demonstrate the significance of two major brain structures, the mushroom bodies and the central complex, in experience-independent aspects of male courtship. We show that blocking of synaptic transmission in the mushroom body intrinsic neurons significantly delays courtship initiation and reduces the courtship activity by shortening the courtship bout length when virgin females are used as a sexual target. Interestingly, however, the same treatment affects neither initiation nor maintenance of courtship toward young males that release courtship-stimulating pheromones different from those of virgin females. In contrast, blocking of synaptic transmission in a central complex substructure, the fan-shaped body, slightly but significantly reduces courtship activity toward both virgin females and young males with little effect on courtship initiation. Taken together, our results indicate that the neuronal activity in the mushroom bodies plays an important role in responding to female-specific sex pheromones that stimulate initiation and maintenance of male courtship behavior, whereas the fan-shaped body neurons are involved in maintenance of male courtship regardless of the nature of courtship-stimulating cues.

The MM2-cortical form of sporadic Creutzfeldt-Jakob disease presenting with visual disturbance

A subclass of sporadic Creutzfeldt-Jakob disease (sCJD) characterized by onset with visual symptoms (Heidenhain variant) has been reported to belong to the MM1 or MV1 type according to Parchi's classification. The authors report a 65-year-old woman with MM2-cortical sCJD with slowly progressive visual disturbance as the initial symptom. Diffusion-weighted MRIs revealed hyperintensity in both occipital cortices at an early stage.

Involvement of the peripheral nervous system in human prion diseases including dural graft associated Creutzfeldt-Jakob disease

OBJECTIVE

To investigate abnormal prion protein (PrP) deposition in the peripheral nervous system (PNS) in human prion diseases.

METHODS

Eight patients with prion diseases were examined: three with sporadic Creutzfeldt-Jakob disease (sCJD), two with dural graft associated CJD (dCJD), one with Gerstmann-Straussler-Scheinker disease (GSS) with a PrP P102L mutation (GSS102), and two with a P105L mutation (GSS105). An atypical case of sCJD with PrP plaques in the brain presented clinically with peripheral neuropathy, and showed demyelination in 12% of the teased fibres of the sural nerve. The PNS was investigated by immunohistochemical and western blotting analyses of PrP.

RESULTS

In immunohistochemical studies, granular PrP deposits were detected in some neurones of dorsal root ganglia and a few fibres of peripheral nerves and spinal posterior roots in one sCJD and two dCJD patients, but not in GSS102 or GSS105 patients. The atypical case of sCJD with peripheral neuropathy showed no obvious PrP deposition in the nerves. Western blotting analysis of the PNS from the dCJD patients revealed a small amount of protease K resistant PrP in the dorsal root ganglia and peripheral nerves.

CONCLUSIONS

Abnormal PrP deposition occurs in the dorsal root ganglia and peripheral nerves in sCJD and dCJD. The PrP deposits in the PNS are not correlated with clinical manifestation of peripheral neuropathy in CJD.

Clinical diagnosis of MM2-type sporadic Creutzfeldt-Jakob disease

BACKGROUND

No method for the clinical diagnosis of MM2-type sporadic Creutzfeldt-Jakob disease (sCJD) has been established except for pathologic examination.

OBJECTIVE

To identify a reliable marker for the clinical diagnosis of MM2-type sCJD.

METHODS

CSF, EEG, and neuroimaging studies were performed in eight patients with MM2-type sCJD confirmed by neuropathologic, genetic, and western blot analyses.

RESULTS

The eight cases were pathologically classified into the cortical (n = 2), thalamic (n = 5), and combined (corticothalamic) (n = 1) forms. The cortical form was characterized by late-onset, slowly progressive dementia, cortical hyperintensity signals on diffusion-weighted imaging (DWI) of brain, and elevated levels of CSF 14-3-3 protein. The thalamic form showed various neurologic manifestations including dementia, ataxia, and pyramidal and extrapyramidal signs with onset at various ages and relatively long disease duration. Characteristic EEG and MRI abnormalities were almost absent. However, all four patients examined with cerebral blood flow (CBF) study using SPECT showed reduction of the CBF in the thalamus as well as the cerebral cortex. The combined form had features of both the cortical and the thalamic forms, showing cortical hyperintensity signals on DWI and hypometabolism of the thalamus on [18F]2-fluoro-2-deoxy-d-glucose PET.

CONCLUSION

For the clinical diagnosis of MM2-type sporadic Creutzfeldt-Jakob disease, cortical hyperintensity signals on diffusion-weighted MRI are useful for the cortical form and thalamic hypoperfusion or hypometabolism on cerebral blood flow SPECT or [18F]2-fluoro-2-deoxy-d-glucose PET for the thalamic form.

Clinical features of Creutzfeldt-Jakob disease with V180I mutation

The authors describe the clinical features of Creutzfeldt-Jakob disease (CJD) with the causative point mutation at codon 180. The symptoms never started with visual or cerebellar involvement. The patients showed slower progression of the disease compared with sporadic CJD. They never showed periodic sharp and wave complexes in EEG. MRI demonstrated remarkable high-intensity areas with swelling in the cerebral cortex except for the medial occipital and cerebellar cortices. These characteristic MRI findings are an important clue for an accurate premortem diagnosis.

A clock gene, period, plays a key role in long-term memory formation in Drosophila

The cAMP-responsive transcription factor, CREB, is required for formation of long-term memory (LTM) in Drosophila melanogaster and regulates transcription of a circadian clock gene, period (per). Involvement of CREB both in LTM and circadian rhythm raises the possibility that per also plays a role in LTM. Assaying the experience-dependent courtship inhibition in male flies as a measure for LTM, we show here that per mutants are defective in LTM formation. This defect was rescued by induction of a wild-type per transgene in a per-null mutant, and overexpression of per enhanced LTM formation in the wild-type background. Furthermore, we found that synaptic transmission through per-expressing cells is most likely to be required during retrieval of LTM. In contrast, mutations in other clock genes (timeless, dClock, and cycle) did not affect LTM formation. Thus, independent of the core oscillator of circadian clock, per plays a key role in LTM formation.

Excitatory and inhibitory switches for courtship in the brain of Drosophila melanogaster

BACKGROUND

Courtship is the best-studied behavior in Drosophila melanogaster, and work on its anatomical basis has concentrated mainly on the functional identification of sexually dimorphic sites in the brain. Much less is known of the more expansive, nondimorphic, but nonetheless essential, neural elements subserving male courtship behavior.

RESULTS

Sites in the CNS mediating initiation and early steps of male courtship in Drosophila melanogaster were identified by analyzing the behavior of mosaic flies expressing transgenes designed either to suppress neurotransmission or enhance neuronal excitability. Suppression of neurotransmission was accomplished by means of the dominantly acting, temperature-sensitive dynamin mutation shibire(ts1), whereas enhanced neuronal excitability was produced by means of a novel, dominantly acting, truncated eag potassium channel. By using a new, landmark-based procedure for aligning diverse expression patterns among the various mosaic strains, a comparison of courtship performance and affected brain sites in strains expressing the transgenes identified a cluster of cells in the posterior lateral protocerebrum that exerts reciprocal effects on the initiation of courtship, suppressing it when they are inactivated and enhancing it when they are hyperactivated, indicative of cells that normally play an excitatory, triggering role. A separate group of nearby cells, slightly more anterior in the lateral protocerebrum, was found to inhibit courtship when its activity is enhanced, indicative of an inhibitory role in courtship.

CONCLUSIONS

A cluster of cells, some excitatory and some inhibitory, in the lateral protocerebrum regulates courtship initiation in Drosophila. These cells are likely to be an integration center for the multiple sensory inputs that trigger male courtship.

MRI characteristics of sporadic CJD with valine homozygosity at codon 129 of the prion protein gene and PrPSc type 2 in Japan

Two Japanese sporadic Creutzfeld-Jakob disease (sCJD) patients with valine homozygosity at codon 129 of the prion protein gene and protease-resistant prion protein (PrP(Sc)) type 2 (VV2) are described. In contrast with Western countries, this type of sCJD is very rare in Japan. In 123 sCJD cases, only two were recognised as VV2 by the Japanese CJD surveillance committee. The clinical symptoms and pathological findings of the patients were similar to those of European and US patients. The noteworthy finding of diffusion weighted MRI (DWI) was that an abnormal high intensity covered a wide range of the thalamus including the dorsomedial nucleus, the pulvinar, and the ventral anterior, lateral, and posterolateral nuclei. This thalamic pattern has not been recognised in sCJD with methionine homozygosity and PrP(Sc) type 1 (MM1) or methionine/valine heterozygosity and PrP(Sc) type 1 (MV1) which comprises the vast majority of sCJD. This finding may be characteristic to VV2 and may distinguish it from MM1, MV1, and variant CJD. DWI can provide a very important clue for the antemortem diagnosis of VV2 subjects.

Targeted expression of shibire ts and semaphorin 1a reveals critical periods for synapse formation in the giant fiber of Drosophila

In order to determine the timing of events during the assembly of a neural circuit in Drosophila we targeted expression of the temperature-sensitive shibire gene to the giant fiber system and then disrupted endocytosis at various times during development. The giant fiber retracted its axon or incipient synapses when endocytosis was blocked at critical times, and we perceived four phases to giant fiber development: an early pathfinding phase, an intermediate phase of synaptogenesis, a late stabilization process and, finally, a mature synapse. By co-expressing shibire(ts) and semaphorin 1a we provided evidence that Semaphorin 1a was one of the proteins being regulated by endocytosis and its removal was a necessary part of the program for synaptogenesis. Temporal control of targeted expression of the semaphorin 1a gene showed that acute excess Semaphorin 1a had a permanent disruptive effect on synapse formation.

Sporadic Creutzfeldt-Jakob disease with MM1-type prion protein and plaques

The authors report a 75-year-old woman with atypical sporadic Creutzfeldt-Jakob disease (CJD) characterized by MM1-type prion protein (PrP) (methionine homozygosity at codon 129 in the PrP gene and type-1 protease-resistant PrP) and PrP plaques. This patient is the first case of sporadic CJD with plaque-forming MM1-type PrP, suggesting either a shared prion strain with the plaque-forming subset of dural graft-associated CJD or shared host genetic factors that are unrelated to the PrP genotype.