Language：English   Publishing type：Research paper (scientific journal)  

Molecular phylogenetic analyses based on plastid-encoded rbcL and mitochondrial cox3 gene sequences, in combination with morphological observations, revealed the existence of the following four bistratose Padina species previously unreported from Australian coasts: Padina calcarea Ni-Ni-Win, S.G.A.Draisma, W.F.Prud’homme van Reine & H.Kawai, characterised by its bright yellow–orange inferior thallus surface and chalky white, heavily calcified superior surface, and the presence of hairlines only on the inferior surface; P. macrophylla Ni-Ni-Win, M.Uchimura & H.Kawai, characterised by a moderately calcified thallus with broad, depressed hairlines on the inferior surface and narrow, not depressed hairlines on the superior surface, those hairlines that are largely spaced on each surface;P. moffittiana I.A.Abbott & Huisman, characterised by lightly calcified thalli with narrow, slightly depressed hairlines that are distributed in alternate sequence between the two surfaces at unequal distances, and broad reproductive sori in one or two rows in the fertile zone; and P. okinawaensisNi-Ni-Win, S.Arai,M.Uchimura & H.Kawai, characterised by heavily calcified thalli, except at the hairlines, which form an alternation of uncalcified furrows and calcified glabrous zones on the inferior surface. With the addition of these four species, 13 Padina species are known from Australia.

DOI： https://doi.org/10.1071/SB13025

Language：English   Publishing type：Research paper (scientific journal)  

Taxonomic study of the brown algal genus Padina (Dictyotales, Phaeophyceae) mainly
from Southeast Asian countries, Japan, Hawaii, Australia and Taiwan as well as the Mediterranean Sea was conducted based on morphology and molecular phylogenetic analyses using chloroplast encoded large subunit RuBisCo (rbcL) gene sequences. Detailed descriptions of each species found in this study as well as key to species identifi cation are described. Several morphological characters, such as number of cell layers composing the thallus, presence or absence and degree of calcifi cation, presence or absence of small groups of rhizoid-like hairs, presence or absence of Vaughaniella stage, structure, position and arrangement of hairlines and reproductive sori, reproductive system (monoecism or dioecism), and presence or absence of indusium over/surrounding reproductive sori, are considered to be reliable morphological characters for species delineation. Variation of the presence (female gametophyte) and absence (male gametophyte and tetrasporophyte) of indusium was recognized in P. australis, indicating a necessary of a careful examination on this character. Molecular phylogenetic analyses using rbcL gene sequences revealed that multi-layered species formed monophyletic, whereas 2-layered and 2/4-layered species were paraphyletic. Only a single species with 2/3-layered thallus was included in the molecular analyses.

Language：English   Publishing type：Research paper (scientific journal)  

Two new species of Padina – 1. Padina sulcata sp. nov. and 2. P. calcarea sp. nov. – from Malaysia, Indonesia and Palau were described based on morphological and molecular phylogenetic observations. Padina sulcata was a three-layered species characterised by a covering of thick fibrous hairs from the base to the middle of the inferior surface (away from the in-rolled margin) of the thallus; conspicuous equally spaced hairlines that alternated between both frond surfaces; and broad, indusiate oogonial and tetrasporangial sori that occupied nearly the entire fertile zones, and the fertile zones were separated by sterile zones of equal width. Padina calcarea was a two-layered species characterised by a bright yellow inferior surface and a thick calcification on the superior surface (facing to the in-rolled margin), which imparted a strikingly whitish color; inconspicuous hairlines were confined to the inferior surface; and indusiate tetrasporangial sori were just above the hairlines and were found only on the inferior surface. Molecular phylogenetic analyses used chloroplast rbcL and mitochondrial cox3 gene sequences and revealed that the two new species each form strongly supported clades that were genetically distant. Padina calcarea formed an isolated clade that made an early divergence; whereas, P. sulcata showed a sister relationship to P. ryukyuana, indicating a more recent divergence. Padina calcarea was very similar to the Hawaiian P. melemele in gross appearance, particularly in the bright orange to yellow color of the inferior thallus surface and the heavy calcification on the superior surface. However, they were distinguished mainly by the position and arrangement of reproductive sori that were found on the inferior surface and located just above the hairlines in P. calcarea but that were found on the superior surface between the hairlines of the opposite surface in P. melemele. Molecular phylogenetic analyses did not reflect the morphological similarity of the two species because they occupied two distantly related clades.

DOI： https://doi.org/10.2216/11-94.1

Language：English   Publishing type：Research paper (scientific journal)  

A study of the genus Padina in the Mediterranean Sea, based on detailed morphological and molecular analyses using chloroplast rbcL and mitochondrial cox3 gene sequences, as well as RuBisCO spacer and partial rbcS sequences, revealed the presence of two new species, P. ditristromatica Ni-Ni-Win & H. Kawai and P. pavonicoides Ni-Ni-Win & H. Kawai. They are two to three-layered and three-layered species, respectively. Padina ditristromatica is characterized by a thallus composed of two cell layers from the marginal portion to the inrolled margin and a mixture of two and three layers in the other portions; heavy calcification on both surfaces of the thallus except for the hair lines; alternating hair lines that are spaced at unequal distances between the upper and lower surfaces; and broad indusiate oogonial and tetrasporangial sori forming broken lines or patches arranged in a concentric row, which are distally close to the hair lines and half immersed in the epidermis layer only on the lower surface. Padina pavonicoides is characterized by a thallus composed of three cell layers from the base to the marginal portion and two layers at the inrolled margin; alternating hair lines that are spaced at equal distances between the upper and lower surfaces; and indusiate oogonial and tetrasporangial sori forming patches located distal to the hair lines only on the lower surface. All molecular phylogenetic analyses indicated that the new species are closely related to P. pavonica, a common species in the Mediterranean Sea. However, the cox3 region could not be amplified for P. ditristromatica. Therefore, the RuBisCO spacer and partial rbcS were analysed for the Mediterranean specimens in order to confirm their identity as well as their closest relationships. The combined rbcL, RuBisCO spacer and partial rbcS data also support their genetic separation and show that P. pavonica is more closely related to P. pavonicoides than P. ditristromatica, as in other molecular analyses.

DOI： 10.1080/09670262.2011.614355

Language：English   Publishing type：Research paper (scientific journal)  

A taxonomic study of the genus Padina from Japan, Southeast Asia, and Hawaii based on morphology and gene sequence data (rbcL and cox3) resulted in the recognition of four new species, that is, Padina macrophylla and Padina ishigakiensis from Ryukyu Islands, Japan; Padina maroensis from Hawaii; and Padina usoehtunii from Myanmar and Thailand. All species are bistratose and morphologically different from one another as well as from any known taxa by a combination of characters relating to degree of calcification; the structure, position, and arrangement of hairlines (HLs) and reproductive sori; and the presence or absence of rhizoid-like groups of hairs and an indusium. Molecular phylogenetic analyses demonstrated a close relationship between P. ishigakiensis, P. macrophylla, P. maroensis, and Padina australis Hauck. The position of P. usoehtunii, however, was not fully resolved, being either sister to a clade comprising the other three new species and P. australis in the rbcL tree or more closely related to a clade comprising several other recently described species in the cox3 tree. The finding of the four new species demonstrates high species diversity particularly in southern Japan. The following characters were first recognized here to be useful for species delimitation: the presence or absence of small rhizoid-like groups of hairs on the thallus surface, structure and arrangement of HLs on both surfaces either alternate or irregular, and arrangement of the alternating HLs between both surfaces in equal or unequal distance. The evolutionary trajectory of these and six other morphological characters used in species delineation was traced on the phylogenetic tree.

DOI： 10.1111/j.1529-8817.2011.01054.x

Language：English   Publishing type：Research paper (scientific journal)  

Molecular phylogenetic analyses of Padina species collected from the western Pacific Ocean using rbcL and mitochondrial cox3 genes revealed the occurrence of four genetically distinctive clades of unknown Padina species: clade A ( = Padina okinawaensis sp. nov.) from Ryukyu Islands (Japan), Hawaii, Indonesia and Thailand, clade B ( = Padina undulata sp. nov.), clade C ( = Padina terricolor sp. nov.) and clade D ( = Padina fasciata sp. nov.) from Ryukyu Islands (Japan). Morphologically, these new taxa are all bistratose species, and different from any known species in the following morphological features: P. okinawaensis sp. nov., reniform or circular thallus of entire margin with inconspicuous hair lines on the superior surface of the thallus, and reproductive organs (oogonia and tetrasporangia) in small groups or discontinuous sori under thin flakes of calcium on the inferior surface; P. undulata sp. nov., circular or semicircular thallus with undulate margin, conspicuous hair lines on both surfaces of the thallus, oogonial and tetrasporangial sori in continuous or discontinuous lines covered with a persistent indusium, and cylindrical oogonia; P. terricolor sp. nov., grayish brown on the inferior surface of the thallus, and oogonial and tetrasporangial sori in continuous lines covered with a persistent indusium; P. fasciata sp. nov., broad white stripes on both surfaces of the thallus due to unique calcification, and oogonial and tetrasporangial sori in continuous lines, which are entirely embedded in a gelatinous layer, on the inferior surface of the thallus. In addition, the independence of Padina japonica from Padina sanctae-crucis is suggested on the basis of molecular and morphological evidence.

DOI： http://dx.doi.org/10.2216/09-54.1

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1111/j.1440-1835.2008.00510.x

Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://ir.kochi-u.ac.jp/dspace/bitstream/10126/4388/1/marine22-065.pdf

Language：English   Publishing type：Research paper (bulletin of university, research institution)  

A total of nine species belonging to five genera from two families of seagrasses was collected from the three coastal regions of Myanmar. These are Cymodocea rotundata, C serrulata, Halodule pinifolia, H. uninervis, Syringodium isotoefolium, Enhalus acoroides, Halophila beccarii, H. decipiens and H. ovalis. Due to turbid water by enormous sediment discharge of two greatest rivers, the Ayeyarwady and the Thanlwin, the subtidal vegetation of seagrasses is totally absent in the Ayeyarwady Delta and the Gulf of Mottama (Martaban) Coastal Region. The family Hydrocharitaceae represents the most dominant genera of seagrasses in both the Rakhine and the Tanintharyi Coastal Regions. However, the family Cymodoceaceae occurs mainly in the Rakhine Coastal Region, except for Cymodocea rotundata, which is unique to the Tanintharyi Coastal Region. In addition, the phytogeographic distribution and conservation plans of seagrasses of Myanmar have been briefly described.

DOI： https://ir.kochi-u.ac.jp/dspace/handle/10126/4380

Publisher：Phycologia  

The brown algal genus Dictyota (Dictyotales, Phaeophyceae) is widespread, particularly in warm temperate and tropical waters, and plays a vital role in coastal ecosystems. This study reassessed the taxonomy of Dictyota, focusing on specimens from Myanmar and Japan, using a combination of morphological and molecular analyses. Molecular phylogenetic analyses using concatenated DNA sequences of rbcL, psaA, psbA, cox1 and cox3 genes revealed that Dictyota specimens from Myanmar, Japan, and other regions, belong to nine different clades, each representing a different species. Based on morphological and molecular data, seven out of these nine clades are identified as known species, while the remaining two clades are described as new species D. recumbens sp. nov. (=D. sp. A) and D. dimorphosa sp. nov. (=D. sp. B). Dictyota recumbens is characterized by the recumbent thallus, with transverse yellowish-green iridescent lines, and the formation of solitary spores irregularly distributed over the thallus. Dictyota dimorphosa is characterized by two morphological forms: decumbent and erect thalli, with bluish iridescence mainly in the decumbent thallus, and the formation of spores in oval ring shapes distributed over both thallus surfaces. Dictyota recumbens was typically found in tropical regions, while D. dimorphosa appears to be a cool-warm temperate species, distributed from northeastern Hokkaido to southern Kyushu with an extension along South Korea. Our molecular phylogenetic analyses have revealed the existence of several species whose names appeared in multiple clades, suggesting the potential for future increases in species diversity and the presence of cryptic species within certain groups.

DOI： 10.1080/00318884.2024.2335606

Web of Science

Scopus

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Informa UK Limited  

Taxonomy, species diversity, and geographical distribution of the marine brown algal genus Padina (Dictyotales, Phaeophyceae) from tropical South-East Asian waters were investigated through a combination of morphological and molecular analyses. The study presents a new schematic diagram showing a suite of morphological characters including thallus hairline structures that are useful for species delineation in the genus. This study also revealed two new species from Myanmar, P. gracilis sp. nov. and P. lata sp. nov. based on molecular and morphological data. P. gracilis is characterised by a 2-layered thallus, thin hairlines on both surfaces of the thallus at equal distances, non-indusiate reproductive sori distally very close to the hairlines on the inferior surface, and the presence of Vaughaniella stage. P. lata is characterized by a 2–4-layered tiny thallus, broad hairlines located only on the inferior thallus surface, non-indusiate reproductive sori abutting the hairlines on the inferior surface and irregularly spreading on the superior surface, and the presence of Vaughaniella stage. This study also revealed new distributional records for four Padina species: P. okinawaensis from Myanmar and P. fasciata, P. ryukyuana and P. terricolor from the Philippines. These findings point to elevated species diversity in central Indo-Pacific waters. This study confirmed that most of the Padina species in the Pacific regions are showing overlapping distribution across the regions, in contrast to species from the Indian Ocean, which tend to be confined to specific localities.

DOI： 10.1080/09670262.2021.1883742

Web of Science

Scopus

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Language：English   Publishing type：Research paper (scientific journal)  

Bilin pigments play important roles for both light perception and harvesting in cyanobacteria by binding to cyanobacteriochromes (CBCRs) and phycobilisomes (PBS), respectively. Among various cyanobacteria, Acaryochloris marina MBIC 11017 (A. marina 11017) exceptionally uses chlorophyll d as the main photosynthetic pigment absorbing longer wavelength light than the canonical pigment, chlorophyll a, indicating existence of a system to sense longer wavelength light than others. On the other hand, A. marina 11017 has the PBS apparatus to harvest short-wavelength orange light, similar to most cyanobacteria. Thus, A. marina 11017 might sense longer wavelength light and harvest shorter wavelength light by using bilin pigments. Phycocyanobilin (PCB) is the main bilin pigment of both systems. Phycocyanobilin:ferredoxin oxidoreductase (PcyA) catalyzes PCB synthesis from biliverdin via the intermediate 18#D1^{R,182-dihydrobiliverdin (181,182-DHBV), resulting in the stepwise shortening of the absorbing wavelengths. In this study, we found that A. marina 11017 exceptionally encodes two PcyA homologs, AmPcyAc and AmPcyAp. AmPcyAc is encoded on the main chromosome with most photoreceptor genes, whereas AmPcyAp is encoded on a plasmid with PBS-related genes. High accumulation of 181,182-DHBV for extended periods was observed during the reaction catalyzed by AmPcyAc, whereas 181,182-DHBV was transiently accumulated for a short period during the reaction catalyzed by AmPcyAp. CBCRs could sense longer wavelength far-red light through 181,182-DHBV incorporation, whereas PBS could only harvest orange light through PCB incorporation, suggesting functional diversification of PcyA as AmPcyAc and AmPcyAp to provide 181,18#U2}-DHBV and PCB to the light perception and harvesting systems, respectively.

DOI： https://doi.org/10.1111/febs.15230

Language：English   Publishing type：Research paper (scientific journal)  

Cyanobacteriochromes (CBCRs) are small, bistable linear tetrapyrrole (bilin)-binding light sensors which are typically found as modular components in multidomain cyanobacterial signaling proteins. The CBCR family has been categorized into many lineages that roughly correlate with their spectral diversity, but CBCRs possessing a conserved DXCF motif are found in multiple lineages. DXCF CBCRs typically possess two conserved Cys residues: a first Cys that remains ligated to the bilin chromophore and a second Cys found in the DXCF motif. The second Cys often forms a second thioether linkage, providing a mechanism to sense blue and violet light. DXCF CBCRs have been described with blue/green, blue/orange, blue/teal, and green/teal photocycles, and the molecular basis for some of this spectral diversity has been well established. We here characterize AM1_1499g1, an atypical DXCF CBCR that lacks the second cysteine residue and exhibits an orange/green photocycle. Based on prior studies of CBCR spectral tuning, we have successfully engineered seven AM1_1499g1 variants that exhibit robust yellow/teal, green/teal, blue/teal, orange/yellow, yellow/green, green/green, and blue/green photocycles. The remarkable spectral diversity generated by modification of a single CBCR provides a good template for multiplexing synthetic photobiology systems within the same cellular context, thereby bypassing the time-consuming empirical optimization process needed for multiple probes with different protein scaffolds.

DOI： https://doi.org/10.1073/pnas.2004273117

Language：English   Publishing type：Research paper (scientific journal)  

Cyanobacteriochromes (CBCRs) are cyanobacterial photoreceptors that sense near-ultraviolet to far-red light. Like the distantly related phytochromes, all CBCRs reported to date have a conserved Cys residue (the “canonical Cys” or “first Cys”) that forms a thioether linkage to C31 of the linear tetrapyrrole (bilin) chromophore. Detection of ultraviolet, violet, and blue light is performed by at least three subfamilies of two-Cys CBCRs that require both the first Cys and a second Cys that forms a second covalent linkage to C10 of the bilin. In the well-characterized DXCF subfamily, the second Cys is part of a conserved Asp-Xaa-Cys-Phe motif. We here report novel CBCRs lacking the first Cys but retaining the DXCF Cys as part of a conserved Asp-Xaa-Cys-Ile-Pro (DXCIP) motif. Phylogenetic analysis demonstrates that DXCIP CBCRs are a sister to a lineage of DXCF CBCR domains from phototaxis sensors. Three such DXCIP CBCR domains (cce_4193g1, Cyan8802_2776g1, and JSC1_24240) were characterized after recombinant expression in Escherichia coli engineered to produce phycocyanobilin. All three covalently bound bilin and showed unidirectional photoconversion in response to green light. Spectra of acid-denatured proteins in the dark-adapted state do not correspond to those of known bilins. One DXCIP CBCR, cce_4193g1, exhibited very rapid dark reversion consistent with a function as a power sensor. However, Cyan8802_2776g1 exhibited slower dark reversion and would not have such a function. The full-length cce_4193 protein also possesses a DXCF CBCR GAF domain (cce_4193g2) with a covalently bound phycoviolobilin chromophore and a blue/green photocycle. Our studies indicate that CBCRs need not contain the canonical Cys residue to function as photochromic light sensors and that phototaxis proteins containing DXCIP CBCRs may potentially perceive both light quality and light intensity.

DOI： https://doi.org/10.1021/acs.biochem.6b00940

Language：English   Publishing type：Research paper (scientific journal)  

Cyanobacteriochromes (CBCRs) are distantly related to the red/far-red responsive phytochromes. Red/green-type CBCRs are widely distributed among various cyanobacteria. The red/green-type CBCRs covalently bind phycocyanobilin (PCB) and show red/green reversible photoconversion. Recent studies revealed that some red/green-type CBCRs from chlorophyll d-bearing cyanobacterium Acaryochloris marina covalently bind not only PCB but also biliverdin (BV). The BV-binding CBCRs show far-red/orange reversible photoconversion. Here, we identified another CBCR (AM1_C0023g2) from A. marina that also covalently binds not only PCB but also BV with high binding efficiencies, although BV chromophore is unstable in the presence of urea. Replacement of Ser334 with Gly resulted in significant improvement in the yield of the BV-binding holoprotein, thereby ensuring that the mutant protein is a fine platform for future development of optogenetic switches. We also succeeded in detecting near-infrared fluorescence from mammalian cells harboring PCB-binding AM1_C0023g2 whose fluorescence quantum yield is 3.0%. Here the PCB-binding holoprotein is shown as a platform for future development of fluorescent probes.

DOI： 10.3389/fmicb.2016.00588

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1073/pnas.1504228112

Language：English   Publishing type：Research paper (scientific journal)  

Cyanobacteriochromes (CBCRs) are diverse photoreceptors that are found only from cyanobacteria and cover wide range of light qualities. CBCRs are divided into two types regarding the chromophore species they contain: phycocyanobilin (PCB) and phycoviolobilin. Red/green-type CBCRs are widely distributed subfamily among the PCB-binding CBCRs and photoconvert between a red-absorbing thermostable form and a green-absorbing metastable form. Our recent study discovered that a red/green-type CBCR, AM1_1557g2, from a cyanobacterium Acaryochloris marina covalently binds not only PCB but also biliverdin (BV). By-binding AM1_1557g2 photoconverts between a far-red absorbing form and an orange-absorbing form. We report, herein, that another red/green-type CBCR, AM1_1870g3, from the cyanobacterium A. marina also bound both PCB and By. PCB- and By-binding ones showed red/green and farred/orange reversible photoconversions, respectively. Unexpectedly, absorbing wavelengths are 10 -20 nm red-shifted compared with those of AM1_1557g2. These red-shifted characteristics may be useful for optogenetic light switches that work in various organisms. (C) 2015 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.bbrc.2015.04.045

Language：English   Publishing type：Research paper (scientific journal)  

Cyanobacteriochromes (CBCRs) are linear tetrapyrrole-binding photoreceptors in cyanobacteria that absorb visible and near-ultraviolet light. CBCRs are divided into two types based on the type of chromophore they contain: phycocyanobilin (PCB) or phycoviolobilin (PVB). PCB-binding CBCRs reversibly photoconvert at relatively long wavelengths, i.e., the blue-to-red region, whereas PVB-binding CBCRs reversibly photoconvert at shorter wavelengths, i.e., the near-ultraviolet to green region. Notably, prior to this report, CBCRs containing biliverdin (BV), which absorbs at longer wavelengths than do PCB and PVB, have not been found. Herein, we report that the typical red/green CBCR AM1_1557 from the chlorophyll d–bearing cyanobacterium Acaryochloris marina can bind BV almost comparable to PCB. This BV-bound holoprotein reversibly photoconverts between a far red light–absorbing form (Pfr, λmax = 697 nm) and an orange light–absorbing form (Po, λmax = 622 nm). At room temperature, Pfr fluoresces with a maximum at 730 nm. These spectral features are red-shifted by 48~77 nm compared with those of the PCB-bound domain. Because the absorbance of chlorophyll d is red-shifted compared with that of chlorophyll a, the BV-bound AM1_1557 may be a physiologically relevant feature of A. marina and is potentially useful as an optogenetic switch and/or fluorescence imager.

DOI： 10.1038/srep07950

Language：English   Publishing type：Research paper (scientific journal)  

The northern Andaman Sea including the Myanmar waters is one of the least studied regions of the northern Indian Ocean. The freshwater and suspended sediments carried by Ayeyawady/Irrawaddy, the peculiar surface circulation, coastline morphology and shallow bathymetry in the Gulf of Mottama facilitate several diverse environmental settings in the study region. In order to understand the environmental settings and their linkages to the plankton community in the study region, this paper combined in situ data of 'First India-Myanmar Joint Oceanographic Expedition' with satellite oceanography observations. The study period was the Spring Intermonsoon (March-May), which was characterized by high tidal activity in the Gulf of Mottama region (tidal height 6-8 m) causing strong tidal currents and re-suspension of sediments. The tidal currents and eastward advection of Ayeyawady influx caused the lowest salinity, highest concentration of nutrients, suspended sediments and chlorophyll a in the Gulf of Mottama region. Conversely, high salinity, highest temperature, lowest nutrients and suspended sediments prevalent in the offshore waters of the northern Andaman Sea induced a massive bloom of Trichodesmium elythraeum, which was mostly in the declining phase during the observation. The in situ and satellite remote sensing data clearly showed that the T. erythraeum bloom observed in the offshore waters was closely linked to a warm core eddy. The decomposition of the bloom favored swarms of siphonophores and hydromedusae through atrophic link involving copepods and appendicularians. Aided by satellite remote sensing data and multivariate statistical tools, five diverse environmental settings have been identified in the study domain. The analysis showed a close coupling between phytoplankton biomass and nutrients with their higher values in the Gulf of Mottama, off Rakhine, Ayeyawady and Thanintharyi region as compared to the offshore waters in the northern Andaman Sea. The zooplankton community dominated by copepods and chaetognaths preferred regions with high salinity, chlorophyll, deep mixed layer and low suspended sediments as existed off Rakhine, Ayeyawady and Thanintharyi regions. The study evidences, for the first time, the spatial segregation of environmental settings and its linkages to the plankton community off Myanmar during the Spring Intermonsoon. (C) 2014 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jmarsys.2014.08.003

Language：English   Publishing type：Research paper (scientific journal)  

Cyanobacteria have unique photoreceptors, cyanobacteriochromes, that show diverse spectral properties to sense near-UV/visible lights. Certain cyanobacteriochromes have been shown to regulate cellular phototaxis or chromatic acclimation of photosynthetic pigments. Some cyanobacteriochromes have output domains involved in bacterial signaling using a second messenger cyclic dimeric GMP (c-di-GMP), but its role in cyanobacteria remains elusive. Here, we characterize the recombinant Tlr0924 from a thermophilic cyanobacterium Thermosynechococcus elongatus, which was expressed in a cyanobacterial system. The protein reversibly photoconverts between blue- and green-absorbing forms, which is consistent with the protein prepared from Escherichia coli, and has diguanylate cyclase activity, which is enhanced 38-fold by blue light compared with green light. Therefore, Tlr0924 is a blue light-activated diguanylate cyclase. The protein's relatively low affinity (10.5 mm) for Mg2+, which is essential for diguanylate cyclase activity, suggests that Mg2+ might also regulate c-di-GMP signaling. Finally, we show that blue light irradiation under low temperature is responsible for Thermosynechococcus vulcanus cell aggregation, which is abolished when tlr0924 is disrupted, suggesting that Tlr0924 mediates blue light-induced cell aggregation by producing c-di-GMP. Given our results, we propose the name “sesA (sessility-A)” for tlr0924. This is the first report for cyanobacteriochrome-dependent regulation of a sessile/planktonic lifestyle in cyanobacteria via c-di-GMP.

DOI： 10.1074/jbc.M114.583674

Language：English   Publishing type：Research paper (scientific journal)  

Cyanobacteriochromes (CBCRs) form a large, spectrally diverse family of photoreceptors (linear tetrapyrrole covalently bound via a conserved cysteine) that perceive ultraviolet to red light. The underlying mechanisms are reasonably well understood with, in certain cases, reversible formation of an adduct between a second cysteine and the chromophore accounting, in part, for their spectral diversity. These CBCRs are denoted as dual-Cys CBCRs, and most such CBCRs had been shown to reversibly absorb blue and green light. Herein, we report the structural and mechanistic characterization of a new type of dual-Cys CBCR, AM1_1186, which exhibits reversible photoconversion between a red-absorbing dark state (λmax = 641 nm) and a blue-absorbing photoproduct (λmax = 416 nm). The wavelength separation of AM1_1186 photoconversion is the largest found to date for a CBCR. In addition to one well-conserved cysteine responsible for covalent incorporation of the chromophore into the apoprotein, AM1_1186 contains a second cysteine in a unique position of its photosensory domain, which would be more properly classified as a red/green CBCR according to its sequence. Carboxyamidomethylation and mutagenesis of the cysteines revealed that the second cysteine forms an adduct with the tetrapyrrole, the phycocyanobilin, that can be reversed under blue light. The proline immediately upstream of this cysteine appears to determine the rate at which the cysteinylation following photoexcitation of the dark state chromophore can occur. We propose a possible reaction scheme and color-tuning mechanism for AM1_1186 in terms of its structure and its place in a phylogenetic tree.

DOI： 10.1021/bi500376b

Event date： 2018.11

Language：English   Presentation type：Symposium, workshop panel (public)  

Venue：National Sun Yat-sen University, Kaohsung City, Taiwan   Country：Taiwan, Province of China  

The brown algal genus Padina Adanson is widely distributed from warm temperate to tropical waters where species occur from the intertidal to deep subtidal zones. A series of recent taxonomic and phylogenetic studies of Padina has revealed many new species of Padina along the Indo-Pacific and Mediterranean Seas, particularly from southern Japan, with more than 70% increases of the recognized Indo-Pacific species. This study also uncovers the existence of additional four new species in southern Japan based on morphological and molecular analyses, showing unexpected high species diversity. A total number of Padina species in Japan increases to 25 species, indicating three times increase of the previous level of species richness, with Ryukyu Is. being the most species-rich area. A close affinity of species is found along the Pacific regions, being somewhat distinct from SE Asia regions (or the Indian Ocean), and species found in the Mediterranean Sea and the Atlantic also seem to have restricted distributions confined only to those areas. Several useful morphological characters for species delineation and morphological distinctiveness of four new species are discussed.

Event date： 2017.12

Language：English  

Venue：University of the Philippines Cebu, Cebu City, Philippines   Country：Philippines  

The brown algal genus Padina is worldly distributed around the world. Recent molecular and taxonomic studies uncovered the existence of many new species based on the molecular and morphological data. This study also reveals the occurrence of four new species and four unknown species that are considered to be new species, indicating unexpectedly high species diversity especially in southern Japan. Given this information Padina species in Japan increase to three times the previous level of species richness, with Ryukyu islands being the most species-rich area. A close affinity of species was found along the Pacific regions, being somewhat distinct from Southeast Asia regions (or the Indian Ocean). Species found in the Mediterranean Sea and the Atlantic seem to have restricted distributions confined only to those areas.

Event date： 2010.4

Language：English   Presentation type：Public lecture, seminar, tutorial, course, or other speech  

Country：Malaysia  

Language：English  

Country：Other  

New records of Padina species from subtropical water of Japan

Language：English  

Country：Other  

Taxonomic revision of the genus Padina in the Western Pacific Ocean

Language：English  

Country：Other  

Systematic revision of the genus Padina in the Pacific Ocean

Language：English  

Country：Other  

Taxonomy and phylogeny of the genus Padina (Dictyotales, Phaeophyceae)

Language：English  

Country：Other  

Taxonomy of the genus Padina (Dictyotales, Phaeophyceae) based on morphological and molecular observations, with a special emphasis on Japanese and Australian species

Language：English  

Country：Other  

Phylogeny, taxonomy, species diversity and distribution of the genus Padina (Dictyotales, Phaeophyceae), with an emphasis on four new records of Australian Padina

Language：English  

Country：Other  

Molecular systematics unveils increased diversity of the genus Padina (Dictyotales, Phaeophyceae), especially in subtropical southern Japan

Language：English  

Country：Other  

Molecular phylogeny and phylogeography of marine algae with special emphasis on systematics, species diversity, geographical distribution and seasonal species compositions

Language：English  

Country：Other  

Systematics, species diversity and global distribution pattern of the brown algal genus Padina (Dictyotales, Phaeophyceae) based on molecular and morphological data

Language：English  

Country：Other  

Phylogenetic and morphological studies of the brown algal genus Padina (Dictyotales, Phaeophyceae): new insights into global species diversity and geographical distribution, with the confirmation of four new species

Language：English  

Country：Other  

Molecular phylogeny and phylogeography of marine algae with special emphasis on systematics, biodiversity, geographical distribution and their correlations with the environment

Language：English  

Country：Other  

One of only two calcareous genera in brown algae, Padina: new insights into current systematics, global species diversity and geographical distribution

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：3

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：1

Proceedings of International Conference Number of peer-reviewed papers：1

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：3

Type：Academic society, research group, etc. 

Type：Peer review 

Number of peer-reviewed articles in foreign language journals：2

Proceedings of International Conference Number of peer-reviewed papers：2

Spring marine biological field course for undergraduate students

Spring and summer marine biological field courses for under- and postgraduate students

Spring and summer marine biological field course for under- and postgraduate students

Summer Marine Biological Field Training Course for Undergraduate and postgraduate students

Spring and Summer marine biological field course for under and postgraduate students