The effect of 4-weeks exposure to music on social bonding between rats.

Interpersonal synchronization of movement induced by music is believed to facilitate social bonding between human beings, but it is unknown whether it also works in animals. We allowed rats to interact and develop social bonding with a specific subject for four weeks under one of the three acoustic conditions: playback of K.448 at its original tempo, playback at its double-tempo, and silence. The strength of social bonding between each pair of rats was then measured. The results showed an increase in preference for rats that had interacted under the original tempo playback compared to the other acoustic conditions. Considering that rats move in synchrony with the beat more robustly and consistently between subjects under the original tempo playback than under the double-tempo playback, this result suggests that motor synchronization between subjects through music may facilitate social bonding between rats.

Oddball-irrelevant visual stimuli cross-modally attenuate auditory mismatch negativity in rats.

OBJECTIVE: To elaborate the recent theory of prediction models of the brain in light of actual neural activities, it is important to investigate the cross-modal interactions in the context of prediction construction. To this end, in this study, we assessed whether cross-modal disturbances would result in the attenuation of mismatch negativity in anesthetized animal models. METHODS: A surface electrode array recorded neural activities from the visual and auditory cortices of rats under isoflurane anesthesia, during an auditory oddball paradigm over the course of three audiovisual sequences. In the audiovisual sequences, the visual stimuli were simultaneously presented with the first, second, or third standard before the deviants. RESULTS: The interrupting visual stimuli decrease the amplitude of mismatch negativity in the auditory and visual cortices. In addition, the correlation coefficients between the amplitude of middle-latency potential for the interrupting visual stimuli and the amplitude of mismatch negativity to the following auditory deviant stimuli were smaller when the visual stimuli were presented alongside the third standards from the deviants. CONCLUSION: Such attenuation in mismatch negativity has been often associated with a top-down mechanism and the present anesthesia selectively attenuates top-down transmission. Taken together, our study's findings indicate that the cross-modal disturbances on prediction and deviation detection may also be mediated by bottom-up mechanisms, as well as previously reported top-down mechanisms.

Role of vitamin E in the treatment of non-alcoholic steatohepatitis.

Non-alcoholic steatohepatitis (NASH), a severe form of non-alcoholic fatty liver disease (NAFLD), can progress to cirrhosis, hepatocellular carcinoma (HCC), and hepatic failure/liver transplantation. Indeed, NASH will soon be the leading cause of HCC and liver transplantation. Lifestyle intervention represents the cornerstone of NASH treatment, but it is difficult to sustain. However, no pharmacotherapies for NASH have been approved. Oxidative stress has been implicated as one of the key factors in the pathogenesis of NASH. Systematic reviews with meta-analyses have confirmed that vitamin E reduces transaminase activities and may resolve NASH histopathology without improving hepatic fibrosis. However, vitamin E is not recommended for the treatment of NASH in diabetes, NAFLD without liver biopsy, NASH cirrhosis, or cryptogenic cirrhosis. Nevertheless, vitamin E supplementation may improve clinical outcomes in patients with NASH and bridging fibrosis or cirrhosis. Further studies are warranted to confirm such effects of vitamin E and that it would reduce overall mortality/morbidity without increasing the incidence of cardiovascular events. Future clinical trials of the use of vitamin E in combination with other anti-fibrotic agents may demonstrate an additive or synergistic therapeutic effect. Vitamin E is the first-line pharmacotherapy for NASH, according to the consensus of global academic societies.

Prepulse inhibition predicts subjective hearing in rats.

Auditory studies in animals benefit from quick and accurate audiometry. The auditory brainstem response (ABR) and prepulse inhibition (PPI) have been widely used for hearing assessment in animals, but how well these assessments predict subjective audiometry still remains unclear. Human studies suggest that subjective audiometry is consistent with the ABR-based audiogram, not with the PPI-based audiogram, likely due to top-down processing in the cortex that inhibits PPI. Here, we challenged this view in Wistar rats, as rodents exhibit less complexity of cortical activities and thereby less influence of the cerebral cortex on PPI compared to humans. To test our hypothesis, we investigated whether subjective audiometry correlates with ABR- or PPI-based audiograms across the range of audible frequencies in Wistar rats. The subjective audiogram was obtained through pure-tone audiometry based on operant conditioning. Our results demonstrated that both the ABR-based and PPI-based audiograms significantly correlated to the subjective audiogram. We also found that ASR strength was information-rich, and adequate interpolation of this data offered accurate audiometry. Thus, unlike in humans, PPI could be used to predict subjective audibility in rats.

Mismatch-negativity (MMN) in animal models: Homology of human MMN?

Mismatch negativity (MMN) has long been considered to be one of the deviance-detecting neural characteristics. Animal models exhibit similar neural activities, called MMN-like responses; however, there has been considerable debate on whether MMN-like responses are homologous to MMN in humans. Herein, we reviewed several studies that compared the electrophysiological, pharmacological, and functional properties of MMN-like responses and adaptation-exhibiting middle-latency responses (MLRs) in animals with those in humans. Accumulating evidence suggests that there are clear differences between MMN-like responses and MLRs, in particular that MMN-like responses can be distinguished from mere effects of adaptation, i.e., stimulus-specific adaptation. Finally, we discuss a new direction for research on MMN-like responses by introducing our recent work, which demonstrated that MMN-like responses represent empirical salience of deviant stimuli, suggesting a new functional role of MMN beyond simple deviance detection.

Tone frequency representation beyond the tonotopic map: Cross-correlation between ongoing activity in the rat auditory cortex.

Functional maps play crucial roles in the neural representations of the sensory cortices, although such representations occasionally extend beyond these maps. For example, the auditory cortex exhibits distinct tonotopic activation at the onset of tone, which is followed by rapid decays in the majority of neuronal signals and ongoing activities in only a small number of neurons. Such ongoing activity should be maintained by the cortical states. To better understand maintenance of ongoing activity beyond that triggered directly by stimuli, we used a rat model. Here, we hypothesized that neural correlations between local field potentials (LFPs) within a local area of the auditory cortex may serve as a measure of the cortical state underlying ongoing activity. We densely mapped the auditory cortex of rats and demonstrated that cross-correlation patterns of ongoing activity were highly decodable. Informative features were widely distributed over the auditory cortex and across multiple frequency bands. Furthermore, acoustic trauma disrupted tonotopic representation at the onset but did not affect neural representations by the correlation of ongoing activities. These results suggest that cross-correlations of LFP within the auditory cortex represent frequencies of sustained auditory stimuli, and that these representations are made beyond direct tonotopic activation at stimulus onset.

Supplementation with branched-chain amino acids ameliorates hypoalbuminemia, prevents sarcopenia, and reduces fat accumulation in the skeletal muscles of patients with liver cirrhosis.

BACKGROUND: Liver cirrhosis induces marked metabolic disorders, protein-energy malnutrition, and sarcopenia. The objective of the study reported here was to investigate the effects of dietary branched-chain amino acids (BCAAs) on systemic glucose metabolism, skeletal muscle, and prognosis of patients with liver cirrhosis. METHODS: Japanese patients with liver cirrhosis (n = 21) were enrolled into a longitudinal study in which their diets were supplemented with BCAAs. We evaluated glucose metabolism and analyzed the skeletal muscle area index (SAI) and intramuscular adipose tissue content (IMAC) using computed tomography. RESULTS: After 48 weeks of supplementation with BCAAs, there were no changes in glucose metabolism and skeletal muscle findings. In patients with ameliorated hypoalbuminemia, IMAC was significantly decreased and SAI was preserved concomitant with decreasing 90- and 120-min post-challenge plasma glucose levels (P < 0.01 each). In patients without increased albumin levels, IMAC was significantly increased and the SAI was significantly decreased (P < 0.01 each). Liver-related event-free survival rates for 72 months were 63.6% in patients with decreased IMAC and 20.0% in patients with increased IMAC. CONCLUSIONS: Amelioration of hypoalbuminemia associated with BCAA supplementation correlated with decreased fat accumulation in skeletal muscle, maintenance of skeletal muscle mass, and improved glucose sensitivity, all factors which may contribute to improving the survival of patients with liver cirrhosis.

Microelectrode mapping of tonotopic, laminar, and field-specific organization of thalamo-cortical pathway in rat.

The rat has long been considered an important model system for studying neural mechanisms of auditory perception and learning, and particularly mechanisms involving auditory thalamo-cortical processing. However, the functional topography of the auditory thalamus, or medial geniculate body (MGB) has not yet been fully characterized in the rat, and the anatomically-defined features of field-specific, layer-specific and tonotopic thalamo-cortical projections have never been confirmed electrophysiologically. In the present study, we have established a novel technique for recording simultaneously from a surface microelectrode array on the auditory cortex, and a depth electrode array across auditory cortical layers and within the MGB, and characterized the rat MGB and thalamo-cortical projections under isoflurane anesthesia. We revealed that the ventral division of the MGB (MGv) exhibited a low-high-low CF gradient and long-short-long latency gradient along the dorsolateral-to-ventromedial axis, suggesting that the rat MGv is divided into two subdivisions. We also demonstrated that microstimulation in the MGv elicited cortical activation in layer-specific, region-specific and tonotopically organized manners. To our knowledge, the present study has provided the first and most compelling electrophysiological confirmation of the anatomical organization of the primary thalamo-cortical pathway in the rat, setting the groundwork for further investigation.

Anesthetic effects of isoflurane on the tonotopic map and neuronal population activity in the rat auditory cortex.

Since its discovery nearly four decades ago, sequential microelectrode mapping using hundreds of recording sites has been able to reveal a precise tonotopic organization of the auditory cortex. Despite concerns regarding the effects that anesthesia might have on neuronal responses to tones, anesthesia was essential for these experiments because such dense mapping was elaborate and time-consuming. Here, taking an 'all-at-once' approach, we investigated how isoflurane modifies spatiotemporal activities by using a dense microelectrode array. The array covered the entire auditory cortex in rats, including the core and belt cortices. By comparing neuronal activity in the awake state with activity under isoflurane anesthesia, we made four observations. First, isoflurane anesthesia did not modify the tonotopic topography within the auditory cortex. Second, in terms of general response properties, isoflurane anesthesia decreased the number of active single units and increased their response onset latency. Third, in terms of tuning properties, isoflurane anesthesia shifted the response threshold without changing the shape of the frequency response area and decreased the response quality. Fourth, in terms of population activities, isoflurane anesthesia increased the noise correlations in discharges and phase synchrony in local field potential (LFP) oscillations, suggesting that the anesthesia made neuronal activities redundant at both single-unit and LFP levels. Thus, while isoflurane anesthesia had little effect on the tonotopic topography, its profound effects on neuronal activities decreased the encoding capacity of the auditory cortex.

Amplitude and phase-locking adaptation of neural oscillation in the rat auditory cortex in response to tone sequence.

Sensory adaptation allows stimulus sensitivity to be dynamically modulated according to stimulus statistics and plays pivotal roles in efficient neural computation. Here, it is hypothesized that in the auditory cortex, phase locking of local field potentials (LFPs) to test tones exhibits an adaptation property, i.e., phase-locking adaptation, which is distinct from the amplitude adaptation of oscillatory components. Series of alternating tone sequences were applied in which the inter-tone interval (ITI) and frequency difference (ΔF) between successive tones were varied. Then, adaptation was characterized by the temporal evolution of the band-specific amplitude and phase locking evoked by the test tones. Differences as well as similarities were revealed between amplitude and phase-locking adaptations. First, both amplitude and phase-locking adaptations were enhanced by short ITIs and small ΔFs. Second, the amplitude adaptation was more effective in a higher frequency band, while the phase-locking adaptation was more effective in a lower frequency band. Third, as with the adaptation of multiunit activities (MUAs), the amplitude adaptation occurred mainly within a second, while the phase-locking showed multi-second adaptation specifically in the gamma band for short ITI and small ΔF conditions. Fourth, the amplitude adaptation and phase-locking adaptation were co-modulated in a within-second time scale, while this co-modulation was not observed in a multi-second time scale. These findings suggest that the amplitude and phase-locking adaptations have different mechanisms and functions. The phase-locking adaptation is likely to play more crucial roles in encoding a temporal structure of stimulus than the amplitude adaptation.

Cortical mapping of mismatch negativity with deviance detection property in rat.

Mismatch Negativity (MMN) is an N-methyl-d-aspartic acid (NMDA)-mediated, negative deflection in human auditory evoked potentials in response to a cognitively discriminable change. MMN-like responses have been extensively investigated in animal models, but the existence of MMN equivalent is still controversial. In this study, we aimed to investigate how closely the putative MMN (MMNp) in rats exhibited the comparable properties of human MMN. We used a surface microelectrode array with a grid of 10 × 7 recording sites within an area of 4.5 × 3.0 mm to densely map evoked potentials in the auditory cortex of anesthetized rats under the oddball paradigm. Firstly, like human MMN, deviant stimuli elicited negative deflections in auditory evoked potentials following the positive middle-latency response, termed P1. Secondly, MMNp exhibited deviance-detecting property, which could not be explained by simple stimulus specific adaptation (SSA). Thirdly, this MMNp occurred focally in the auditory cortex, including both the core and belt regions, while P1 activation focus was obtained in the core region, indicating that both P1 and MMNp are generated in the auditory cortex, yet the sources of these signals do not completely overlap. Fourthly, MMNp significantly decreased after the application of AP5 (D-(-)-2-amino-5-phosphonopentanoic acid), an antagonist at NMDA receptors. In stark contrast, AP5 affected neither P1 amplitude nor SSA of P1. These results provide compelling evidence that the MMNp we have examined in rats is functionally comparable to human MMN. The present work will stimulate translational research into MMN, which may help bridge the gap between electroencephalography (EEG)/magnetoencephalography (MEG) studies in humans and electrophysiological studies in animals.

Cell type-specific transcriptome of Brassicaceae stigmatic papilla cells from a combination of laser microdissection and RNA sequencing.

Pollination is an early and critical step in plant reproduction, leading to successful fertilization. It consists of many sequential processes, including adhesion of pollen grains onto the surface of stigmatic papilla cells, foot formation to strengthen pollen-stigma interaction, pollen hydration and germination, and pollen tube elongation and penetration. We have focused on an examination of the expressed genes in papilla cells, to increase understanding of the molecular systems of pollination. From three representative species of Brassicaceae (Arabidopsis thaliana, A. halleri and Brassica rapa), stigmatic papilla cells were isolated precisely by laser microdissection, and cell type-specific gene expression in papilla cells was determined by RNA sequencing. As a result, 17,240, 19,260 and 21,026 unigenes were defined in papilla cells of A. thaliana, A. halleri and B. rapa, respectively, and, among these, 12,311 genes were common to all three species. Among the17,240 genes predicted in A. thaliana, one-third were papilla specific while approximately half of the genes were detected in all tissues examined. Bioinformatics analysis revealed that genes related to a wide range of reproduction and development functions are expressed in papilla cells, particularly metabolism, transcription and membrane-mediated information exchange. These results reflect the conserved features of general cellular function and also the specific reproductive role of papilla cells, highlighting a complex cellular system regulated by a diverse range of molecules in these cells. This study provides fundamental biological knowledge to dissect the molecular mechanisms of pollination in papilla cells and will shed light on our understanding of plant reproduction mechanisms.

Pre-attentive, context-specific representation of fear memory in the auditory cortex of rat.

Neural representation in the auditory cortex is rapidly modulated by both top-down attention and bottom-up stimulus properties, in order to improve perception in a given context. Learning-induced, pre-attentive, map plasticity has been also studied in the anesthetized cortex; however, little attention has been paid to rapid, context-dependent modulation. We hypothesize that context-specific learning leads to pre-attentively modulated, multiplex representation in the auditory cortex. Here, we investigate map plasticity in the auditory cortices of anesthetized rats conditioned in a context-dependent manner, such that a conditioned stimulus (CS) of a 20-kHz tone and an unconditioned stimulus (US) of a mild electrical shock were associated only under a noisy auditory context, but not in silence. After the conditioning, although no distinct plasticity was found in the tonotopic map, tone-evoked responses were more noise-resistive than pre-conditioning. Yet, the conditioned group showed a reduced spread of activation to each tone with noise, but not with silence, associated with a sharpening of frequency tuning. The encoding accuracy index of neurons showed that conditioning deteriorated the accuracy of tone-frequency representations in noisy condition at off-CS regions, but not at CS regions, suggesting that arbitrary tones around the frequency of the CS were more likely perceived as the CS in a specific context, where CS was associated with US. These results together demonstrate that learning-induced plasticity in the auditory cortex occurs in a context-dependent manner.

Comprehensive network analysis of anther-expressed genes in rice by the combination of 33 laser microdissection and 143 spatiotemporal microarrays.

Co-expression networks systematically constructed from large-scale transcriptome data reflect the interactions and functions of genes with similar expression patterns and are a powerful tool for the comprehensive understanding of biological events and mining of novel genes. In Arabidopsis (a model dicot plant), high-resolution co-expression networks have been constructed from very large microarray datasets and these are publicly available as online information resources. However, the available transcriptome data of rice (a model monocot plant) have been limited so far, making it difficult for rice researchers to achieve reliable co-expression analysis. In this study, we performed co-expression network analysis by using combined 44 K agilent microarray datasets of rice, which consisted of 33 laser microdissection (LM)-microarray datasets of anthers, and 143 spatiotemporal transcriptome datasets deposited in RicexPro. The entire data of the rice co-expression network, which was generated from the 176 microarray datasets by the Pearson correlation coefficient (PCC) method with the mutual rank (MR)-based cut-off, contained 24,258 genes and 60,441 genes pairs. Using these datasets, we constructed high-resolution co-expression subnetworks of two specific biological events in the anther, "meiosis" and "pollen wall synthesis". The meiosis network contained many known or putative meiotic genes, including genes related to meiosis initiation and recombination. In the pollen wall synthesis network, several candidate genes involved in the sporopollenin biosynthesis pathway were efficiently identified. Hence, these two subnetworks are important demonstrations of the efficiency of co-expression network analysis in rice. Our co-expression analysis included the separated transcriptomes of pollen and tapetum cells in the anther, which are able to provide precise information on transcriptional regulation during male gametophyte development in rice. The co-expression network data presented here is a useful resource for rice researchers to elucidate important and complex biological events.

Early effects of oral administration of lafutidine with peppermint oil, compared with lafutidine alone, on intragastric pH values.

BACKGROUND/AIMS: Ideally, medications for the treatment of acid-related diseases should have a rapid onset of action to promote hemostasis and the resolution of symptoms. The aim of our study was to investigate the inhibitory effects on gastric acid secretion of a single oral administration of lafutidine alone or combined with peppermint oil. METHODOLOGY: Ten Helicobacter pylori-negative male subjects participated in this randomized, two-way crossover study. Intragastric pH was monitored continuously for 4 hours after a single oral administration of lafutidine (10 mg) or the administration of lafutidine (10 mg) with peppermint oil (0.64 mL). Each administration was separated by a 7-day washout period. RESULTS: No significant difference in the average pH was observed during the 4-hour period after the combined administration of lafutidine and peppermint oil and after the administration of lafutidine alone (median gastric pH: 5.09 versus 5.29; p = 0.3122). CONCLUSIONS: In H. pylori-negative healthy male subjects, an oral dose of lafutidine combined with peppermint oil did not increase the intragastric pH faster than lafutidine alone.

Distributed representation of tone frequency in highly decodable spatio-temporal activity in the auditory cortex.

Although the place code of tone frequency, or tonotopic map, has been widely accepted in the auditory cortex, tone-evoked activation becomes less frequency-specific at moderate or high sound pressure levels. This implies that sound frequency is not represented by a simple place code but that the information is distributed spatio-temporally irrespective of the focal activation. In this study, using a decoding-based analysis, we investigated multi-unit activities in the auditory cortices of anesthetized rats to elucidate how a tone frequency is represented in the spatio-temporal neural pattern. We attempted sequential dimensionality reduction (SDR), a specific implementation of recursive feature elimination (RFE) with support vector machine (SVM), to identify the optimal spatio-temporal window patterns for decoding test frequency. SDR selected approximately a quarter of the windows, and SDR-identified window patterns led to significantly better decoding than spatial patterns, in which temporal structures were eliminated, or high-spike-rate patterns, in which windows with high spike rates were selectively extracted. Thus, the test frequency is also encoded in temporal as well as spatial structures of neural activities and low-spike-rate windows. Yet, SDR recruited more high-spike-rate windows than low-spike-rate windows, resulting in a highly dispersive pattern that probably offers an advantage of discrimination ability. Further investigation of SVM weights suggested that low-spike-rate windows play significant roles in fine frequency differentiation. These findings support the hypothesis that the auditory cortex adopts a distributed code in tone frequency representation, in which high- and low-spike-rate activities play mutually complementary roles.

Long-term combination therapy of ezetimibe and acarbose for non-alcoholic fatty liver disease.

BACKGROUND/AIMS: Non-alcoholic fatty liver disease (NAFLD) is a hepatic manifestation of metabolic syndrome that is closely associated with multiple factors such as obesity, hyperlipidemia, type 2 diabetes mellitus and hypertension, making it difficult to treat NAFLD effectively using any monotherapy available to date. In this study, we propose a novel combination therapy for NAFLD comprising ezetimibe (EZ), a cholesterol absorption inhibitor, and acarbose (AC), an alpha-glucosidase inhibitor. METHODS: C57BL/6J mice were divided into five treatment groups as follows: basal diet (BD), high-fat diet (HFD) only, HFD with EZ (5mg/kg/day), HFD with AC (100mg/kg/day), and HFD with both EZ and AC for 24 weeks. RESULTS: Long-term combination therapy with EZ and AC significantly reduced steatosis, inflammation and fibrosis in the liver, compared with long-term monotherapy with either drug, in an HFD-induced NAFLD mouse model; the combination therapy also significantly increased the expression of microsomal triglyceride transfer protein (MTP) and peroxisome proliferators-activated receptor-alpha1 (PPAR-alpha1) in the liver, compared with either monotherapy, which may have led to the improvement in lipid metabolic disorder seen in this model. CONCLUSIONS: Combination therapy with EZ and AC for 24 weeks improved the histopathological findings in a mouse model of NAFLD.

Does postprandial coffee intake enhance gastric emptying?: a crossover study using continuous real time 13C breath test (BreathID system).

BACKGROUND/AIMS: Coffee is one of the most popular beverages worldwide, however, few studies have examined the effects of coffee on the gastrointestinal system. The aim of this study was to determine whether there was a correlation between coffee intake and gastric emptying using a novel non-invasive technique for measuring gastric emptying with a continuous real time 13C breath test (BreathID system: Oridion, Israel). METHODOLOGY: Six healthy male volunteers participated in this randomized, two-way crossover study. The subjects were randomly assigned to receive a test meal (200 kcal per 200 mL) plus postprandial 190 mL black coffee or the test meal alone after fasting overnight. A 13C-acetic acid breath test was continuously performed using the BreathID system, which monitors gastric emptying, for 4 hours after the administration of the test meal. Using Oridion Research Software (beta version), the time for emptying of 50% of the labeled meals (T 1/2) and the analog to the scintigraphy lag time for 10% emptying of the labeled meal (T lag) were calculated. The parameters between two occasions were compared using the Wilcoxon signed-rank test. RESULTS: After coffee intake the T 1/2 and T lag constant were significantly decreased. CONCLUSIONS: The decrease in the T 1/2 and T lag suggests the acceleration of gastric emptying. This study showed that postprandial coffee intake enhances gastric emptying, suggesting the potential use of coffee in clinical settings for patients with functional gastrointestinal disorders.

Penetration of the sigmoid colon to the posterior uterine wall secondary to diverticulitis: a case report.

INTRODUCTION: Penetration of the colon to the posterior uterine wall secondary to diverticulitis is unusual, with diagnostic methods not yet established. Non-invasive imaging, such as computed tomography and magnetic resonance imaging may help to establish a proper diagnosis, but confirmation may be reached only after surgical exploration. CASE PRESENTATION: We report the case of a 78-year-old Japanese woman who presented with a low grade fever and mild diarrhea which occurred two or three times a week. Computed tomography and magnetic resonance imaging demonstrated a capsular lesion including an air structure with a diameter of 5 cm, between the posterior aspect of the uterine body and the sigmoid colon. A gastrograffin enema and colonoscopy demonstrated a giant diverticulum of the sigmoid colon with no evidence of malignancy. These data confirmed the diagnosis of diverticulitis complicated by a giant diverticulum. Because of a relapsing fever after therapy with antibiotics, the patient had en bloc surgical treatment of the uterus, fallopian tubes, ovaries and sigmoid colon, the organs involved in the diverticulitis, followed by an uneventful recovery. CONCLUSION: This is a rare case report of penetration of the sigmoid colon to the posterior uterine wall secondary to diverticulitis.

Various spatiotemporal expression profiles of anther-expressed genes in rice.

The male gametophyte and tapetum play different roles during anther development although they are differentiated from the same cell lineage, the L2 layer. Until now, it has not been possible to delineate their transcriptomes due to technical difficulties in separating the two cell types. In the present study, we characterized the separated transcriptomes of the rice microspore/pollen and tapetum using laser microdissection (LM)-mediated microarray. Spatiotemporal expression patterns of 28,141 anther-expressed genes were classified into 20 clusters, which contained 3,468 (12.3%) anther-enriched genes. In some clusters, synchronous gene expression in the microspore and tapetum at the same developmental stage was observed as a novel characteristic of the anther transcriptome. Noteworthy expression patterns are discussed in connection with gene ontology (GO) categories and gene annotations, which are related to important biological events in anther development, such as pollen maturation, pollen germination, pollen tube elongation and pollen wall formation.