Displaying publications 1 - 20 of 36 in total

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  1. Dehling JM, Matsui M
    Zootaxa, 2013;3670:33-44.
    PMID: 26438919
    We describe a new species of Leptolalax from Gunung Mulu National Park in eastern Sarawak, Malaysian Borneo. The new species had been assigned to Leptolalax dringi and Leptolalax gracilis in the past. It is shown to differ from both these species and from all other species of the genus by a unique combination of morphological characters including large body size, rounded snout, interorbital distance being smaller than width of upper eyelid, bipartite subgular vocal sac in males, basal toe webbing, shagreened skin with tiny tubercles on dorsum and dorsal side of head, angled supratympanic fold, small pectoral glands, absence of supraaxillary glands and ventrolateral glandular ridges, spotted venter, advertisement call consisting of long series of 8-289 notes, each composed of three or four pulses, and dominant frequency at 7225-9190 Hz, with prominent frequency modulation.
  2. Djong TH, Matsui M, Kuramoto M, Belabut DM, Sen YH, Nishioka M, et al.
    Zoolog Sci, 2007 Dec;24(12):1197-212.
    PMID: 18271636 DOI: 10.2108/zsj.24.1197
    In order to elucidate the taxonomic status of the Fejervarya limnocharis complex relative to Malaysia and Japan populations, morphological observations and molecular phylogenetic analysis were carried out using three populations from Indonesia (type locality), Malaysia, and Japan. In addition, we conducted histological and spermatogenic observations using hybrids among these populations. Principal component and cluster analyses demonstrated that these populations could be clearly separated from one another. Abnormal testes were found in the hybrids between the Japan and Indonesia populations and between the Japan and Malaysia populations, but testes of the controls and hybrids between the Malaysia and Indonesia populations were quite normal. The mean number of univalents per cell was 5.42, 4.58, and 0.20 in hybrids between the Indonesia and Japan populations, Malaysia and Japan populations, and Indonesia and Malaysia populations, respectively. Sequence divergences in 16S rRNA and Cyt b genes were 0-0.4% (xbar=0.2%) and 0.3-1.5% (xbar=1.0%), respectively, between the Malaysia and Indonesia populations, and 2.4-2.6% (xbar=2.5%) and 11.0-12.0% (xbar=11.5%) between the Japan population and F. limnocharis complex, including the Malaysia and Indonesia populations and F. multistriata from China. This study indicated that the Malaysia population and F. multistriata from China should be designated as a subspecies of topotypic F. limnocharis, and that the Japan population should be regarded as a distinct species.
  3. Foong CP, Lau NS, Deguchi S, Toyofuku T, Taylor TD, Sudesh K, et al.
    BMC Microbiol, 2014;14:318.
    PMID: 25539583 DOI: 10.1186/s12866-014-0318-z
    Special features of the Japanese ocean include its ranges of latitude and depth. This study is the first to examine the diversity of Class I and II PHA synthases (PhaC) in DNA samples from pelagic seawater taken from the Japan Trench and Nankai Trough from a range of depths from 24 m to 5373 m. PhaC is the key enzyme in microorganisms that determines the types of monomer units that are polymerized into polyhydroxyalkanoate (PHA) and thus affects the physicochemical properties of this thermoplastic polymer. Complete putative PhaC sequences were determined via genome walking, and the activities of newly discovered PhaCs were evaluated in a heterologous host.
  4. Fukuyama I, Vogel G, Matsui M, Eto K, Munir M, Hossman MY, et al.
    Zoolog Sci, 2020 Dec;37(6):586-594.
    PMID: 33269875 DOI: 10.2108/zs200100
    The red-bellied form of Calliophis intestinalis (Laurenti, 1768) sensu lato was originally reported from Pahang, west Malaysia. To determine the taxonomic status of this form, we examined the type specimens of Elaps sumatranus Lidth De Jeude, 1890, Calliophis intestinalis everetti (Boulenger, 1896), and Callophis furcatus var. nigrotaeniatus Peters, 1863. The results indicated that the red-bellied form of C. intestinalis should be named as Calliophis nigrotaeniatus comb. nov., whose valid species status was based on morphological and molecular analyses. We designate a lectotype and redescribe the species, which is genetically close to Calliophis bilineatus (Peters, 1881) from the Philippines, and is clearly distinguishable from other congeners by possessing a pair of gray or dark blue lateral stripes and by being bright red on the ventrum. Elaps sumatranus and C. i. everetti are relegated to subjective junior synonyms of C. nigrotaeniatus.
  5. Honda Y, Onodera S, Takemoto H, Harun NFC, Nomoto T, Matsui M, et al.
    Pharm Res, 2023 Jan;40(1):157-165.
    PMID: 36307662 DOI: 10.1007/s11095-022-03414-8
    PURPOSE: Controlling small interfering RNA (siRNA) activity by external stimuli is useful to exert a selective therapeutic effect at the target site. This study aims to develop a technology to control siRNA activity in a thermo-responsive manner, which can be utilized even at temperatures close to body temperature.

    METHODS: siRNA was conjugated with a thermo-responsive copolymer that was synthesized by copolymerization of N-isopropylacrylamide (NIPAAm) and hydrophilic N,N-dimethylacrylamide (DMAA) to permit thermally controlled interaction between siRNA and an intracellular gene silencing-related protein by utilizing the coil-to-globule phase transition of the copolymer. The composition of the copolymer was fine-tuned to obtain lower critical solution temperature (LCST) around body temperature, and the phase transition behavior was evaluated. The cellular uptake and gene silencing efficiency of the copolymer-siRNA conjugates were then investigated in cultured cells.

    RESULTS: The siRNA conjugated with the copolymer with LCST of 38.0°C exhibited ~ 11.5 nm of the hydrodynamic diameter at 37°C and ~ 9.8 nm of the diameter at 41°C, indicating the coil-globule transition above the LCST. In line with this LCST behavior, its cellular uptake and gene silencing efficiency were enhanced when the temperature was increased from 37°C to 41°C.

    CONCLUSION: By fine-tuning the LCST behavior of the copolymer that was conjugated with siRNA, siRNA activity could be controlled in a thermo-responsive manner around the body temperature. This technique may offer a promising approach to induce therapeutic effects of siRNA selectively in the target site even in the in vivo conditions.

  6. Huy NT, Chico RM, Huan VT, Shaikhkhalil HW, Uyen VNT, Qarawi ATA, et al.
    PLoS One, 2021;16(12):e0258348.
    PMID: 34936646 DOI: 10.1371/journal.pone.0258348
    BACKGROUND: Since the COVID-19 pandemic began, there have been concerns related to the preparedness of healthcare workers (HCWs). This study aimed to describe the level of awareness and preparedness of hospital HCWs at the time of the first wave.

    METHODS: This multinational, multicenter, cross-sectional survey was conducted among hospital HCWs from February to May 2020. We used a hierarchical logistic regression multivariate analysis to adjust the influence of variables based on awareness and preparedness. We then used association rule mining to identify relationships between HCW confidence in handling suspected COVID-19 patients and prior COVID-19 case-management training.

    RESULTS: We surveyed 24,653 HCWs from 371 hospitals across 57 countries and received 17,302 responses from 70.2% HCWs overall. The median COVID-19 preparedness score was 11.0 (interquartile range [IQR] = 6.0-14.0) and the median awareness score was 29.6 (IQR = 26.6-32.6). HCWs at COVID-19 designated facilities with previous outbreak experience, or HCWs who were trained for dealing with the SARS-CoV-2 outbreak, had significantly higher levels of preparedness and awareness (p<0.001). Association rule mining suggests that nurses and doctors who had a 'great-extent-of-confidence' in handling suspected COVID-19 patients had participated in COVID-19 training courses. Male participants (mean difference = 0.34; 95% CI = 0.22, 0.46; p<0.001) and nurses (mean difference = 0.67; 95% CI = 0.53, 0.81; p<0.001) had higher preparedness scores compared to women participants and doctors.

    INTERPRETATION: There was an unsurprising high level of awareness and preparedness among HCWs who participated in COVID-19 training courses. However, disparity existed along the lines of gender and type of HCW. It is unknown whether the difference in COVID-19 preparedness that we detected early in the pandemic may have translated into disproportionate SARS-CoV-2 burden of disease by gender or HCW type.

  7. Kurita T, Nishikawa K, Matsui M, Hikida T
    Zootaxa, 2017 05 03;4258(6):525-538.
    PMID: 28609895 DOI: 10.11646/zootaxa.4258.6.2
    A new species of Asian rock gecko, genus Cnemaspis, is described from Padawan, western Sarawak, Malaysian Borneo. The new species forms a clade with C. paripari and C. nigridia of the C. nigridia group in a mitochondrial DNA phylogeny and is similar to them morphologically in some characters such as caudal scalation. It differs from the other Asian Cnemaspis species in its unique combination of snout-vent length (up to 62.7 mm), 4-9 precloacal pores in males, keeled subcaudals with an enlarged, smooth, median row, presence of ventrolateral caudal tubercles, and coloration (head and upper flanks dark-yellow; anterior portion of tail black; posterior portion of tail white with black, paravertebral blob). Phylogenetic relationships within the C. nigridia group and the distributional ranges of species within the group suggest allopatric speciation by geographic isolation.
  8. Lau NS, Foong CP, Kurihara Y, Sudesh K, Matsui M
    PLoS One, 2014;9(1):e86368.
    PMID: 24466058 DOI: 10.1371/journal.pone.0086368
    The photosynthetic cyanobacterium, Synechocystis sp. strain 6803, is a potential platform for the production of various chemicals and biofuels. In this study, direct photosynthetic production of a biopolymer, polyhydroxyalkanoate (PHA), in genetically engineered Synechocystis sp. achieved as high as 14 wt%. This is the highest production reported in Synechocystis sp. under photoautotrophic cultivation conditions without the addition of a carbon source. The addition of acetate increased PHA accumulation to 41 wt%, and this value is comparable to the highest production obtained with cyanobacteria. Transcriptome analysis by RNA-seq coupled with real-time PCR was performed to understand the global changes in transcript levels of cells subjected to conditions suitable for photoautotrophic PHA biosynthesis. There was lower expression of most PHA synthesis-related genes in recombinant Synechocystis sp. with higher PHA accumulation suggesting that the concentration of these enzymes is not the limiting factor to achieving high PHA accumulation. In order to cope with the higher PHA production, cells may utilize enhanced photosynthesis to drive the product formation. Results from this study suggest that the total flux of carbon is the possible driving force for the biosynthesis of PHA and the polymerizing enzyme, PHA synthase, is not the only critical factor affecting PHA-synthesis. Knowledge of the regulation or control points of the biopolymer production pathways will facilitate the further use of cyanobacteria for biotechnological applications.
  9. Lau NS, Makita Y, Kawashima M, Taylor TD, Kondo S, Othman AS, et al.
    Sci Rep, 2016 06 24;6:28594.
    PMID: 27339202 DOI: 10.1038/srep28594
    Hevea brasiliensis Muell. Arg, a member of the family Euphorbiaceae, is the sole natural resource exploited for commercial production of high-quality natural rubber. The properties of natural rubber latex are almost irreplaceable by synthetic counterparts for many industrial applications. A paucity of knowledge on the molecular mechanisms of rubber biosynthesis in high yield traits still persists. Here we report the comprehensive genome-wide analysis of the widely planted H. brasiliensis clone, RRIM 600. The genome was assembled based on ~155-fold combined coverage with Illumina and PacBio sequence data and has a total length of 1.55 Gb with 72.5% comprising repetitive DNA sequences. A total of 84,440 high-confidence protein-coding genes were predicted. Comparative genomic analysis revealed strong synteny between H. brasiliensis and other Euphorbiaceae genomes. Our data suggest that H. brasiliensis's capacity to produce high levels of latex can be attributed to the expansion of rubber biosynthesis-related genes in its genome and the high expression of these genes in latex. Using cap analysis gene expression data, we illustrate the tissue-specific transcription profiles of rubber biosynthesis-related genes, revealing alternative means of transcriptional regulation. Our study adds to the understanding of H. brasiliensis biology and provides valuable genomic resources for future agronomic-related improvement of the rubber tree.
  10. Lau NS, Matsui M, Abdullah AA
    Biomed Res Int, 2015;2015:754934.
    PMID: 26199945 DOI: 10.1155/2015/754934
    Cyanobacteria are widely distributed Gram-negative bacteria with a long evolutionary history and the only prokaryotes that perform plant-like oxygenic photosynthesis. Cyanobacteria possess several advantages as hosts for biotechnological applications, including simple growth requirements, ease of genetic manipulation, and attractive platforms for carbon neutral production process. The use of photosynthetic cyanobacteria to directly convert carbon dioxide to biofuels is an emerging area of interest. Equipped with the ability to degrade environmental pollutants and remove heavy metals, cyanobacteria are promising tools for bioremediation and wastewater treatment. Cyanobacteria are characterized by the ability to produce a spectrum of bioactive compounds with antibacterial, antifungal, antiviral, and antialgal properties that are of pharmaceutical and agricultural significance. Several strains of cyanobacteria are also sources of high-value chemicals, for example, pigments, vitamins, and enzymes. Recent advances in biotechnological approaches have facilitated researches directed towards maximizing the production of desired products in cyanobacteria and realizing the potential of these bacteria for various industrial applications. In this review, the potential of cyanobacteria as sources of energy, bioactive compounds, high-value chemicals, and tools for aquatic bioremediation and recent progress in engineering cyanobacteria for these bioindustrial applications are discussed.
  11. Luedtke JA, Chanson J, Neam K, Hobin L, Maciel AO, Catenazzi A, et al.
    Nature, 2024 Jan;625(7993):E2.
    PMID: 38040869 DOI: 10.1038/s41586-023-06851-6
  12. Luedtke JA, Chanson J, Neam K, Hobin L, Maciel AO, Catenazzi A, et al.
    Nature, 2023 Oct;622(7982):308-314.
    PMID: 37794184 DOI: 10.1038/s41586-023-06578-4
    Systematic assessments of species extinction risk at regular intervals are necessary for informing conservation action1,2. Ongoing developments in taxonomy, threatening processes and research further underscore the need for reassessment3,4. Here we report the findings of the second Global Amphibian Assessment, evaluating 8,011 species for the International Union for Conservation of Nature Red List of Threatened Species. We find that amphibians are the most threatened vertebrate class (40.7% of species are globally threatened). The updated Red List Index shows that the status of amphibians is deteriorating globally, particularly for salamanders and in the Neotropics. Disease and habitat loss drove 91% of status deteriorations between 1980 and 2004. Ongoing and projected climate change effects are now of increasing concern, driving 39% of status deteriorations since 2004, followed by habitat loss (37%). Although signs of species recoveries incentivize immediate conservation action, scaled-up investment is urgently needed to reverse the current trends.
  13. Makita Y, Ng KK, Veera Singham G, Kawashima M, Hirakawa H, Sato S, et al.
    DNA Res, 2017 Apr 01;24(2):159-167.
    PMID: 28431015 DOI: 10.1093/dnares/dsw056
    Natural rubber has unique physical properties that cannot be replaced by products from other latex-producing plants or petrochemically produced synthetic rubbers. Rubber from Hevea brasiliensis is the main commercial source for this natural rubber that has a cis-polyisoprene configuration. For sustainable production of enough rubber to meet demand elucidation of the molecular mechanisms involved in the production of latex is vital. To this end, we firstly constructed rubber full-length cDNA libraries of RRIM 600 cultivar and sequenced around 20,000 clones by the Sanger method and over 15,000 contigs by Illumina sequencer. With these data, we updated around 5,500 gene structures and newly annotated around 9,500 transcription start sites. Second, to elucidate the rubber biosynthetic pathways and their transcriptional regulation, we carried out tissue- and cultivar-specific RNA-Seq analysis. By using our recently published genome sequence, we confirmed the expression patterns of the rubber biosynthetic genes. Our data suggest that the cytoplasmic mevalonate (MVA) pathway is the main route for isoprenoid biosynthesis in latex production. In addition to the well-studied polymerization factors, we suggest that rubber elongation factor 8 (REF8) is a candidate factor in cis-polyisoprene biosynthesis. We have also identified 39 transcription factors that may be key regulators in latex production. Expression profile analysis using two additional cultivars, RRIM 901 and PB 350, via an RNA-Seq approach revealed possible expression differences between a high latex-yielding cultivar and a disease-resistant cultivar.
  14. Makita Y, Kawashima M, Lau NS, Othman AS, Matsui M
    BMC Genomics, 2018 01 19;19(Suppl 1):922.
    PMID: 29363422 DOI: 10.1186/s12864-017-4333-y
    BACKGROUND: Natural rubber is an economically important material. Currently the Pará rubber tree, Hevea brasiliensis is the main commercial source. Little is known about rubber biosynthesis at the molecular level. Next-generation sequencing (NGS) technologies brought draft genomes of three rubber cultivars and a variety of RNA sequencing (RNA-seq) data. However, no current genome or transcriptome databases (DB) are organized by gene.

    RESULTS: A gene-oriented database is a valuable support for rubber research. Based on our original draft genome sequence of H. brasiliensis RRIM600, we constructed a rubber tree genome and transcriptome DB. Our DB provides genome information including gene functional annotations and multi-transcriptome data of RNA-seq, full-length cDNAs including PacBio Isoform sequencing (Iso-Seq), ESTs and genome wide transcription start sites (TSSs) derived from CAGE technology. Using our original and publically available RNA-seq data, we calculated co-expressed genes for identifying functionally related gene sets and/or genes regulated by the same transcription factor (TF). Users can access multi-transcriptome data through both a gene-oriented web page and a genome browser. For the gene searching system, we provide keyword search, sequence homology search and gene expression search; users can also select their expression threshold easily.

    CONCLUSION: The rubber genome and transcriptome DB provides rubber tree genome sequence and multi-transcriptomics data. This DB is useful for comprehensive understanding of the rubber transcriptome. This will assist both industrial and academic researchers for rubber and economically important close relatives such as R. communis, M. esculenta and J. curcas. The Rubber Transcriptome DB release 2017.03 is accessible at http://matsui-lab.riken.jp/rubber/ .

  15. Matsui M, Belabut DM, Ahmad N
    Zootaxa, 2014;3881(1):75-93.
    PMID: 25543621 DOI: 10.11646/zootaxa.3881.1.6
    Taxonomic status of fanged frogs from the Peninsular Malaysia, previously assigned to Limnonectes kuhlii, is assessed using genetic and morphological approaches. Phylogenetic relationships inferred from sequences of the mitochondrial and nuclear genes revealed that the fanged frogs from the Peninsula form a monophyletic group and are clearly divergent from other species previously, or even now, assigned to L. kuhlii from Mainland Southeast Asia. In both mtDNA and nuDNA phylogeny, the Malay Peninsula clade diverges into two lineages, one from north (Larut Hill, Perak, and Hulu Terengganu, Terengganu) and another from south (Genting Highlands, Pahang, and Gombak, Selangor). These lineages are separated by large genetic distances, comparable with those observed between some other species of L. kuhlii-like frogs. Although the two lineages are very similar morphologically, they are distinguishable in several morphological traits and are considered heterospecific. We therefore describe them as L. utara sp. nov. and L. selatan sp. nov. These new species differ from all other species of kuhlii-like frogs from Mainland Southeast Asia by the surface of tibia, which is densely covered by large warts. 
  16. Matsui M, Zainudin R, Nishikawa K
    Zoolog Sci, 2014 Nov;31(11):773-9.
    PMID: 25366161 DOI: 10.2108/zs140137
    A new megophryid species is described from southwestern Sarawak, Malaysian Borneo. In appearance, Leptolalax marmoratus sp. nov. is most similar to L. hamidi also from southwestern Sarawak, but differs from it by mtDNA sequence, larger body size, and higher dominant frequency of advertisement call. The assumption that more than one species of Leptolalax coexist at one locality in Borneo is supported. The finding of the new species raises the species number of Leptolalax known from Borneo to nine, and the island is thought to be one of the diversification centers of the genus.
  17. Matsui M, Nishikawa K, Yambun P
    Zootaxa, 2014;3753:440-52.
    PMID: 24869507 DOI: 10.11646/zootaxa.3753.5.3
    A new species of Leptolalax is described from Kinabalu National Park in western Sabah, Malaysian Borneo. The new species had been assigned to L. dringi, L. gracilis, or L. fritinniens in the past. It differs from all congeners, including these species, by a unique combination of morphological characters, including small body size, rounded snout, narrower interorbital than upper eyelid, basal toe webbing, smooth skin with tiny tubercles on dorsum and dorsal side of head, small pectoral glands, absence of supraaxillary glands and ventrolateral glandular ridges, spotted venter, advertisement call consisting of long series of 1-149 notes, each composed of three or four pulses, and dominant frequency at 6.90-7.35 kHz, without prominent frequency modulation.
  18. Matsui M, Shimada T, Sudin A
    Zoolog Sci, 2014 Jan;31(1):45-51.
    PMID: 24410495 DOI: 10.2108/zsj.31.45
    We record a tree frog of the genus Chiromantis for the first time from outside the Southeast Asian continent and describe it as a new species, Chiromantis inexpectatus. The new species from the Malaysian state of Sabah, Borneo, is a small-sized Chiromantis (male snout-vent length ca. 22 mm), and is distinguished from all other members of the genus by the combination of the following morphological characteristics: dark stripes absent, but dark spots present on dorsum; a dark-brown lateral band present from snout tip to half of body, bordered ventrally by white stripe; third and fourth fingers less than half webbed; third finger disk wider than tympanum diameter; and inner metatarsal tubercle present. Significance of findings of this species from Borneo Island, as well as phylogeny and breeding habit of the genus Chiromantis, are briefly discussed.
  19. Matsui M, Hamidy A, Murphy RW, Khonsue W, Yambun P, Shimada T, et al.
    Mol Phylogenet Evol, 2010 Jul;56(1):259-72.
    PMID: 20302957 DOI: 10.1016/j.ympev.2010.03.014
    By investigating genealogical relationships, we estimated the phylogenetic history and biogeography in the megophryid genus Leptobrachium (sensu lato, including Vibrissaphora) from southern China, Indochina, Thailand and the Sundaland. The genealogical relationships among the 30 named and unnamed taxa were estimated using 2009 bp of sequences from the mitochondrial DNA genes 12S rRNA, tRNA(val), and 16S rRNA using maximum parsimony, maximum likelihood, and Bayesian inference methods. The genus Leptobrachium was a well-supported monophyletic group that contained two major clades. One clade had three subclades primarily from disjunct regions including Borneo, Peninsular Malaysia and Java, and Thailand. The Bornean subclade included one species each from the Philippines and Sumatra. The other major clade consisted of two subclades, one from Indochina and the other from southern China (Vibrissaphora). Divergence times estimated an old evolutionary history of each subclade, one that could not be explained by the geohistory of Southeast Asian major landmasses.
  20. Matsui M
    Zoolog Sci, 2009 Aug;26(8):579-85.
    PMID: 19719411 DOI: 10.2108/zsj.26.579
    A new microhylid, Kalophrynus yongi, Is described from the Cameron Highlands of Peninsular Malaysia. Morphologically, the new species differs from all known congeners by having a very stout forelimb with a humeral spine in males. Acoustically, it resembles K. baluensis and K. heterochirus and sharply differs from K. interlineatus, K. pleurostigma, K. palmatissimus, and K. nubicola.
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