Ki Wan Nam

Morphology of Chondrophycus undulata and C. parvipapillata and its implications for the taxonomy of the Laurencia (Ceramiales, Rhodophyta) complex

Laurencia Lamouroux subgenus Chondrophycus Tokida et Saito was recently raised to generic status as Chondrophycus (Tokida et Saito) Garbary et Harper (Ceramiales, Rhodophyta). The previously unknown morphology and anatomy of two Chondrophycus species, C. undulata (Yamada) Garbary et Harper and C. parvipapillata (C.K. Tseng) Garbary et Harper, were studied in specimens from Korea, Japan and Hawaii. These species share some features, such as a strongly compressed thallus, vegetative axes with two pericentral cells, tetrasporangial production from pericentral cells and spermatangial development of the trichoblast type. However, they differ from each other in the position of the first pericentral cell relative to the trichoblast in axial segments and in the position of the tetrasporangial pericentral cell. In C. undulata, the first pericentral cell is always produced at one side of the basal cell of a trichoblast, whereas in C. parvipapillata it is formed underneath this cell. While tetrasporangia in C. undul...

Taxonomy and phylogeny of Osmundea (Rhodomelaceae, Rhodophyta) in Atlantic Europe

Two species of Osmundea Stackhouse (Rhodomelaceae, Rhodophyta) that occur in Atlantic Europe have been confused under the names Osmundea ramosissima (Oeder) Athanasiadis and Osmundea truncata (Kützing) Nam et Maggs, regarded until now as a synonym of O. ramosissima. An epitype from its type locality (Stavanger, Norway) is selected for Osmundea ramosissima Athanasiadis, recognized here as a valid name for Fucus ramosissimus Oeder, nom. illeg. Details of vegetative and reproductive morphology of O. ramosissima are reported, based on material from France, the British Isles, and Helgoland. Osmundea ramosissima resembles other species of Osmundea in its vegetative axial segments with two pericentral cells and one trichoblast, spermatangial development from apical and epidermal cells (filament type), the formation of five pericentral cells in the procarp‐bearing segment of the female trichoblast, and tetrasporangial production from random epidermal cells. Among the species of Osmundea, O. ramosissima is most similar to O. truncata. Both species have discoid holdfasts, secondary pit connections between epidermal cells, and cup‐shaped spermatangial pits. They differ in that: (a) O. ramosissima lacks lenticular wall thickenings and refractive needle‐like inclusions in medullary cells, both of which are present in O. truncata; (b) O. ramosissima has branched spermatangial filaments that terminate in a cluster of several cells, whereas in O. truncata the unbranched spermatangial filaments have a single large terminal sterile cell; and (c) cystocarps of O. ramosissima lack protuberant ostioles but ostioles are remarkably protuberant in O. truncata. Phylogenetic analyses of rbcL sequences of Laurencia obtusa (Hudson) Lamouroux and all five Atlantic European species of Osmundea, including the type species, strongly support the generic status of Osmundea. Osmundea ramosissima and O. truncata are closely related (5.2% sequence divergence) and form a well‐supported clade sister to a clade consisting of O. pinnatifida (Hudson) Stackhouse, O. osmunda Stackhouse and O. hybrida (A. P. de Candolle) Nam. The formation of secondary pit connections between epidermal cells is a synapomorphy for the O. ramosissima+O. truncata clade. The close relationship between species with cup‐shaped spermatangial pits (Osmundea hybrida) and urn‐shaped pits (Osmundea pinnatifida and Osmundea osmunda) shows that spermatangial pit shape is not an important phylogenetic character. Parsimony analysis of a morphological data set also supports the genus Osmundea but conflicts with the molecular trees in infrageneric relationships, placing O. hybrida basal within the Osmundea clade and grouping O. osmunda and O. pinnatifida but not O. truncata and O. ramosissima. A key to Osmundea species is presented.

A new antibacterial dioxopiperazine alkaloid related to gliotoxin from a marine isolate of the fungus Pseudallescheria

A new antibacterial dioxopiperazine, dehydroxybisdethiobis(methylthio)gliotoxin (1), and the previously described bisdethiobis(methylthio)gliotoxin (2) and gliotoxin (3), have been isolated from the broth of a marine-derived fungus of the genus Pseudallescheria. The structure and absolute stereochemistry of the new compound was assigned on the basis of NMR and CD experiments. Compounds 1~3 exhibit potent antibacterial activity against the methicillin-resistant and multidrug-resistant Staphylococcus aureus with MIC values of 31.2, 31.2, and 1.0 µg/ml, respectively. Compound 3 also exhibited a significant radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) with IC50 value of 5.2 µM.

Validation of the Generic Name Palisada (Rhodomelaceae, Rhodophyta)

The name Palisada, which recently was proposed but not validly published for a new genus in the Laurencia complex,is validated by the provision of a Latin diagnosis. Relevant omenclatural changes for several species of Chondrophycus are included.

Effects of daylength, irradiance and settlement density on the growth and reproduction of Undaria pinnatifida gametophytes

The effects of daylength, irradiance and spore settlement density on the growth, maturation and sporophyte production of Undaria pinnatifida (Harvey) Suringar gametophytes were examined using a factorial experimental design in culture. The growth of Undaria gametophytes increased with increasing daylength (8, 12 and 16 h), but the maximum fertility occurred at a daylength of 12 h followed by 8 and 16 h. Gametophytes grew better at the 16 h daylength under the same mean daily irradiance (MDI) of 20 μmol photons m−2 s−1. However, the fertility was higher at the short daylength (8 h), indicating that the maturation of U. pinnatifida gametophytes is influenced by daylength rather than by the MDI. Vegetative growth and sporophyte production of gametophytes were better at 60 μmol photons m−2 s−1 than at 30 μmol photons m−2 s−1 under a 8:16 h LD (Light: Dark) cycle, and their growth and maturation were density-dependant in 16 and 12 h daylength, respectively. These results suggest that the U. pinnatifida gametophytes require a certain amount of light for the growth and reproduction, and intraspecific competition occurred under the optimal growth and maturation conditions. However, the sporophyte recruits per unit has been enhanced with increasing spore settlement density at 8 and 12 h daylengths indicating that high settlement density gives a benefit for maintaining population, even though the sporophyte production of each female plant is inhibited. In conclusion, the vegetative growth, reproduction and sporophyte production of U. pinnatifida gametophytes are retarded at a low irradiance above growth saturation and a high settlement density, and are determined by daylength.

Seasonal Variation in Biomass and Community Structure of Intertidal Seaweeds at Heuksando and Hongdo, Southwestern Coast of Korea

해양생태계에서 일차생산자의 중요한 구성원의 하나인 해조 류는 무척추동물과 척추동물의 산란장과 섭이장 그리고 포식 자에 대한 은신처뿐만 아니라, 부착 동·식물에게는 착생기질로 이용되므로 해양생물의 종다양성과 생산성을 증대에 일조한다 (Lindstrom, 2009). 온대해역의 해조류 군집구조는 계절적으로 변화하는 수온, 염분 및 광주기 등 무생물적 환경요인(Lobban and Harrison, 1997)과 경쟁과 섭식압 등의 생물학적요인, 그리 고 인간의 직·간접적 활동(부영양화, 퇴적물의 증가 등)에 따라 변화한다(Tribollet and Vroom, 2007). 특히, 인간활동에 기인 한 환경오염이나 부영양화가 발생한 해역에서는 해조류의 종 다양성이 낮고 단순화된 군집구조를 가지는 것으로 알려져 있 어 해조상과 군집구조로 생태계의 환경변화를 예측 혹은 진단 할 수 있어 생물학적 지시자(biological indicator)로 사용된다 (Diez et al., 1999; Wells et al., 2007). 우리나라 전라남도 연안은 해안선의 굴곡이 심하고 다양한 크 기의 많은 섬들로 구성되어 있을 뿐만 아니라, 해류, 수온, 수심 과 탁도의 변화가 매우 심한 해황적 특성을 보인다(Kang, 1966; Choi, 1992). 전라남도 해역에서 해조류 연구의 시초는 정약전 이 1814년에 집필한 자산어보에서 흑산도에 35종이 출현한 것 으로 기록되어 있는 것이며, 해조학자인 Kang (1966)은 한국 산 해조류의 지리적 분포를 구분하면서 대흑산도와 소흑산도에 서 89종이 생육하는 것을 보고하였다. 이후 Lee et al. (1986a) 은 대흑산도와 소흑산도를 포함한 6개 섬의 하계 조사에서 129 종을 기재하였고 Kang (1966)의 연구 결과와 비교하여 이곳 에 서식하는 해조류는 총 160종으로 기록하였다. 이외에도 홍 도와 흑산도가 포함된 행정구역인 신안군의 우이도의 계절별

Morphology of Laurencia clavata and L. elata (Ceramiales, Rhodophyta) in relation to generic circumscription in the Laurencia complex

Laurencia Lamouroux (Rhodophyta) was recently separated into three genera–Laurencia, Chondrophycus (Tokida et Saito) Garbary et Harper and Osmundea Stackhouse – each of which was newly defined based on vegetative and reproductive structures. In this study, the previously unknown vegetative and reproductive morphology of two Australian endemic species of Laurencia, L. clavata Sonder and L. elata (C. Agardh) Harvey, was studied, particularly in the context of the revised generic delineation. These species exhibit vegetative axes with four pericentral cells and trichoblast-type spermatangial development. Tetrasporangia are abaxially produced from the existing third and fourth pericentral cells. L. clavata has terete thalli with distinctive verticillate branching and is similar to Chondria C. Agardh, rather than to Laurencia, in having an unusually marked constriction at the base of the branches and starch accumulation in subcortical and medullary cells. Compared to Laurencia, apical cells of this species exh...

Notes on Marine Algal Species from Korea

해양 생물은 중요한 생물자원으로 인식되고 있다. 특히, 해조류 자원은 식용, 유용 유기물질 추출, 바이오연료 생산, 탄소 흡수 등과 같은 많은 잠재적인 이용 가능성을 갖는다. 한국산 자생생물 조사의 일환으로 Halymenia latifolia P.L. Crouan et H.M. Crouan ex Kutzing, Grateloupia livida (Harvey) Yamada and Hypnea boergesenii Tanaka의 3종이 동해 연안에서 채집되었다. 본 3종에 대한 형태학 및 분류학적 주해가 본 연구에서 제시된다. 이 중에서 Halymenia latifolia는 한국산 미기록 종으로 여기서 처음으로 보고된다.

Notes on Three Marine Algal Species from Korea

한국산 해조 3종, Umbraulva olivascens (P.J.L. Dangeard) G. Furnari, Bryopsis minor Womersley, Sargassum polycystum C. Agardh에 대한 형태학적 및 분류학적 주해가 제시된다. Umbraulva olivascens는 뚜렷한 올리브 체색, 파상형 연변, 엽체의 구멍 및 조하대 서식처에 의해 특징지어진다. Bryopsis minor는 작은 조체, 모든 방향에서 많은 분지, 기부에 잘록함이 없는 선형의 소지, 두드러진 가지 흔적을 결여하는 축, 뚜렷한 중심 피레노이드를 갖는 엽록체, 주축과 비슷한 길이의 가지 및 뚜렷하지 않은 주축을 갖는 것이 특징적이다. Sargassum polycystum은 조체 모든 부분에서 나는 원통형 내지난형의 돌기, 가시가 있는 뚜렷한 중륵을 갖는 전연 내지 다소 거치연의 잎과 드물게 나는 기낭을 갖는 것으로 특징지어진다. 이 3종은 여기서 한국 해조상에 처음 기록된다.

Vegetative and reproductive development of Laurencia venusta (Ceramiales, rhodophyta)

Abstract The previously unknown vegetative and reproductive development of Laurencia venusta Yamada (Ceramiales, Rhodophyta) were studied based on specimens collected from Korea and Japan. Each vegetative axial segment bears a trichoblast and four pericentral cells; the first of the latter is always produced below the basal cell of the trichoblast; the second pericentral cell is formed at some distance from the first, followed by the third and fourth pericentral cells in an alternating sequence. Spermatangial branches are produced from one of two laterals on the suprabasal cell of a trichoblast in cup-shaped spermatangial pits. The procarp-bearing segment of the female trichoblast has five pericentral cells, of which the fifth becomes the supporting cell of the carpogonial branch. Mature cystocarps are ovoid with a non-protuberant ostiole. Tetrasporangia, with two pre- and one post-sporangial cover cells, are produced abaxially from the existing third and fourth pericentral cell, or occasionally only the fourth pericentral cell, and are parallel to the stichidial axis. Two pre-sporangial cover cells are aligned transversely to the stichidial axis in surface view. These features confirm the placement of L. venusta in the revised Laurencia Lamouroux. Laurencia venusta is characterized by a loosely intricate, small thallus without percurrent axis, numerous holdfasts from the creeping and coalesced basal branches, and abundant medullary lenticular thickenings. Furthermore, it seems to be distinct from other species in having a single, comparatively large (20–30 μm diam.) corps en cerise per epidermal cell.