bluuebunny/crossref_metadata_2025_split huggingface dataset:
The life cycle of Gyrodinium instriatum (Dinophyceae) in culture*
Authors: Uchida Takuji , Matsuyama Yukihiko , Yamaguchi Mineo , Honjo Tsuneo 
Published: February 2006

SUMMARYThe life cycle events of an unarmored dinoflagellate Gyrodinium instriatum Freudenthal et Lee has been investigated using clonal cultures. After the inoculation of vegetative cells into fresh medium, clumping of gametes was observed after a period of 10 days. In the clumps, a number of gametes were observed to be swimming in close contact with each other, pairing successively and then forming a plano‐zygote. This clumping behavior is considered to be useful in the performance of sexual reproduction, particularly in the event of low cell density, because it increases the chance of fusion. Gametes of this species were most often isogarnous, although apparent amsogamous fusions were occasionally observed. When planozygotes were isolated and placed in fresh medium, they enlarged their size and finally divided into two cells. The daughter cells continued to multiply by binary fission and produced vegetative cells. Thus, G. instriatum has an alternative cycle between vegetative cells and zygotes without a hypnozygote stage. However, cysts of this species were transformed from large motile cells (pre‐cyst cells) which are oblong and dorso‐ventrally flattened in shape. These mottle pre‐cyst cells have two longitudinal flagella, which may indicate that cysts of this species are of zygote origin. On the basis of these results, the relationship between zygotes and pre‐cysts of G. instriatum is discussed. Excystment was enhanced by dark and cold treatments prior to the incubation for germination experiments with a germination success rate of 26–64%. Encystment was greatly inhibited by the lack of dark and cold treatments.
Fine filaments observed within the cytoplasm surrounding the leading edge of the septum in telophase cells ofSpirogyra(Zygnematales, Chlorophyta)
Authors: Nishino Takeshi , Asakawa Shinjiro , Ogawa Shigeru 
Published: February 2006

SUMMARYElectron microscope observation revealed the presence of many fine filaments within the cytoplasm surrounding the leading edge of the septum in telophase cells ofSpirogyra verruculosaJao. These filaments, about 7 nm each in diameter, ran parallel to one another along the leading edge of the septum and, sometimes, they appeared to be gathered into at least two bundles. These filament distribution patterns coincided well with those of the fluorescence of rhodamine‐labeled phalloidin in the vicinity of the septum in telophase cells. The present results suggest that the fine filaments observed within the cytoplasm surrounding the leading edge of the septum may be actin filaments.
First report of Chloropelta caespitosa (Ulvaceae, Ulvales, Ulvophyceae) in Japan*
Authors: Lima Masafumi , Fukusumi Kenji 
Published: February 2006

SUMMARY Chloropelta caespitosa Tanner was found in Nagasaki Prefecture, in western Japan. This is the first record of this species in Japan and the western Pacific. Morphology and early development in culture corresponded with the original description of this species. Reproduction is by asexual quadriflagellate (rarely biflagetlate) zoospores. Sexual reproduction was not observed. Morphology and habitat are very similar to Ulva conglobata Kjellman; however, C. caespitosa (frond diameter 1–2 cm) is smaller than U. conglobata (frond diameter 1–4 cm) and juvenile plants have saccate and tubular fronds.
The morphology and taxonomy of Womersleya monanthos, an endemic species and genus of Delesseriaceae (Ceramiales, Rhodophyta) from southeastern Australia
Authors: Lin Showe‐Mei , Kraft Gerald T. 
Published: February 2006

SUMMARY Womersleya monanthos (J. Agardh) Papenfuss is typically an epiphyte of larger brown and red algae that are common in drift along the southeastern coasts of Australia. A hitherto little‐known member of the Phycodrys group of the Nitophylloideae, its reproductive features have been studied in detail and its taxonomic position clarified. Blades are polystromatic throughout and lack veins or nerves, with blades originating from apical cells of primary and second‐order cell rows. Intercalary cell divisions take place in primary cell rows and all other branch orders, with third‐order laterals arising both abaxially and adaxially on cells of second‐order rows. Fertile central cells bear procarps on pericentral cells on both sides of the blade, the procarps consisting of two 4‐celled carpogonial branches and a single central group of sterile cells that enlarge and persist at the distal end of a bicampanulate fusion cell at maturity. Spermatangia and tetrasporangia form in circular subapical sori on both sides of the blade or in marginal lobes or proliferations. After comparing it to other members of the Phycodrys group, we conclude that Womersleya is a monotypic genus well distinguished from other genera and with probable closest affinities to the Northern Hemisphere Polyneura, Erythroglossum and Sorella, as well as the Australian endemic, Crassilingua.
Immunofluorescence study of mitosis and cytokinesis in Acrosiphonia duriuscula (Acrosiphoniales, Chlorophyta)*
Authors: Aruga Hirofumi , Motomura Taizo , Ichimura Terunobu 
Published: February 2006

SUMMARYThe behaviors of nuclei and microtubules (MT) in Acrosiphonia duriuscula (Ruprecht) Collins were observed in detail using fluorescence and electron microscopy. Numerous nuclei exist in cells of A. duriuscula (multinucleate cells). Cortical MT radiate from the apex of the tip cell and run parallel to its long axis. Between 30 and 40% of nuclei in the upper part of cytoplasm migrate downward to the region where cytokinesis will take place, and these numerous nuclei form a ‘nuclear ring’ before mitosis. The parallel array of the cortical MT changes to a transverse orientation at the region where cytokinesis will take place, and finally forms a characteristic circumferential band. Mitosis starts from the nuclei in the ring. Cortical MT disappear in the region of the nuclear ring and many mitotic spindles form. The band‐shaped array of MT remains. Mitosis spreads in an apparent wave to the other nuclei. After mitosis, daughter nuclei that formed a nuclear ring migrate apically and repopulate the apical daughter cell. When the numerous daughter nuclei have relocated, a rearrangement of the cortical MT occurs. They are randomly arranged at first, but finally become parallel to the long axis of the cell. Cytokinesis occurs by furrowing of the cell, and the band‐shaped array of MT could be detected at the leading edge of the furrow.
A morphometric comparison of Ecklonia kurome (Laminariales, Phaeophyta) from Japan*
Authors: Tsutsui Isao , Arai Shogo , Terawaki Toshinobu , Ohno Masao 
Published: February 2006

SUMMARYA morphological comparison was made of Ecklonia kurome Okamura collected from seven localities, including a lectotype locality (Shirahama), in Japan. Morphometric characters and their size ranges were recorded as follows: the central lamina width (5.1–67.8 cm), the median fascia thickness (0.9–3.3 mm), the primary pinna width (2.2–24.0 cm), the ratio of width to length of the primary pinna (0.07–0.56) and the primary pinna number index (PPNI; 0.24–2.21). The results suggested that the morphological variations observed within this species were related to their habitat. A thick and distinct median fascia and an undulate central lamina margin were found on plants from moderate wave‐exposed locations. Plants having narrow primary pinnae with indistinct ruga were observed on shores facing open sea. Wide and thin plants grew in wave‐sheltered habitats. Flat plants were found on a shore exposed to a continuous strong current throughout the year. There were noticeable differences in morphology among the Tateyama, Tsuno, Aburatsubo and Tonoshima populations. The yellow and crisp primary pinna edge was a major characteristic of the Tateyama population. Narrow plants in which the central lamina and primary pinnae were half as wide as those of the Shirahama population were found in Tsuno. Wide and thin plants were observed in Aburatsubo. In this locality, the central lamina and primary pinnae were nearly three times wider but half the thickness of those of the Shirahama population. Flat plants grew in Tonoshima. The Muroto and Oki populations exhibited morphologically similar characteristics to the Shirahama population. A hollow stipe and slightly high PPNI value were found in the Muroto population, and a slightly low PPNI value was found on the Oki population.
Medullary structure differences in Gelidium and Pterocladia (Gelidiales, Rhodophyceae): Taxonomic meaning
Authors: Rodriguez Dení , Santelices Bernabé 
Published: February 2006

SUMMARYStudy of the apical portions of vegetative thalli of 21 species of the genera Gelidium and Pterocladia (Gelidiales‐Rhodophyta) revealed the existence of six patterns of medullary structure. Each pattern is characterized by the organization of the medullary tissue and the changes in cellular dimensions from apex to subapex. These characters can be used to separate groups of species within each genus.
A re‐examination of the morphology, ultrastructure and classification of genera in the Lemaneaceae (Batrachospermales, Rhodophyta)
Authors: Sheath Robert G. , Müller Kirsten M. , Vis Morgan L. , Entwisle Timothy J. 
Published: February 2006

SUMMARYVegetative and reproductive morphology and ultrastructure were examined for the three genera of the freshwater red algal family Lemaneaceae: Lemanea (two species, seven populations), Paralemanea (two species, three populations) and Psilosiphon (one species, one population). Psilosiphon is readily distinguished from the other two genera in having an outer cortex composed of well‐defined filaments interconnected with a dense medulla (both cell types being little vacuolated), spores cleaving off obliquely, putative spermatangia scattered on the thallus surface and reproduction by adventitious filaments. Based on the distinctness of this genus (and corroborated by molecular phylogenies in preparation), a new family is described, the Psilosiphonaceae. Lemanea and Paralemanea appear to be closely related, with an outer cortex that has cells of increasing size and vacuolation from the periphery to the interior and not in obvious rows, a central lumen that contains few ray cells but no medullary filaments, sexual reproduction with spermatangia in distinct clusters, and carpospores in chains, some of which can germinate in the thallus lumen. Lemanea and Paralemanea have distinguishing characteristics that the other genus does not: for Lemanea, hair cells, ray cells abutting the outer cortex and spermatangia in patches; for Paralemanea, no hair cells or ray cells appressed to the outer cortex, inner cortical filaments surrounding the central axis and spermatangia in rings.
Typification of species of Codium (Bryopsidales, Chlorophyta) described by Okamura
Authors: Silva Paul C. , Yoshida Tadao , Shimada Satoshi 
Published: February 2006

SUMMARYType specimens of six species of Codium described by Okamura are illustrated, including the holotype of Codium barbatum and lectotypes of Codium coactum, Codium intricatum, Codium pugniforme, Codium saccatum, and Codium subtubulosum. All species are currently recognized except C. pugniforme, which is indistinguishable from the previously described Codium spongiosum Harvey, Codium subtubulosum was abandoned by Okamura in favor of the previously described Codium divaricatum Holmes, but because of the prior existence of C. divaricatum (C. Agardh) Biasoletto, C. subtubulosum is the correct name for this species.
Effects of light photon flux density and spectral quality on photosynthesis and respiration in Porphyra yezoensis (Bangiales, Rhodophyta)
Authors: Zhang Xuecheng , Brammer Eric , Pedersén Marianne , Fei Xiuging 
Published: February 2006

SUMMARYA comparative study on the effects of photon flux density and spectral quality on photosynthesis and respiration in the marine red alga Porphyra yezoensis Ueda was conducted using a light dispenser. Results showed that the photosynthetic response, expressed in light utilization efficiency (LUE) for preselected wave bands of photosynthetically active radiation, could be ranked as follows: white > green > red > blue. Differences in LUE were also found between conchocelis and gametophyte stages and different strains of the alga. Pre‐illumination light compensation, post‐illumination light compensation, light saturation, respiration and photorespiration were also measured and compared. The relationships between light exposure, photosynthetic capacity, and the natural environmental conditions are discussed.
Microhabitat and plant structure of Batrachospermum (Batrachospermales, Rhodophyta) populations in four streams of São Paulo State, southeastern Brazil
Authors: Necchi Orlando 
Published: February 2006

SUMMARYMicrohabitat and plant structure of seven Batrachospermum populations (four of Batrachospermum delicatulum (=Sirodotia delicatula), one of Batrachospermum macrosporum and two of the ‘Chantransia’ stage), including the influence of physical variables (current velocity, depth, irradiance and substratum), were investigated in four streams of São Paulo State, southeastern Brazil. The populations of B. delicatulum and the ‘Chantransia’ stage occurred under very diverse microhabitat conditions, which probably contributes to their wide spatial and seasonal distribution in Brazilian streams. Results suggest branch reconfiguration as a probable mechanism of adaptation to current velocity based on the occurrence of: (i) B. macrosporum (a large mucilaginous form with presumably little ability for branch reconfiguration) under lower current velocity than B. delicatulum; (ii) only dense plants in populations with high current velocities (> 60 cm s−1), whereas 53–77% of dense plants were seen in populations exposed to lower currents (< 40 cm s−1); (iii) positive correlations of plant length with internode length in populations under low current velocities and negative correlation in a population with high velocity (132 cm s−1); and (iv) negative correlations of current velocity with plant diameter and internode length in a population under high flow. This study, involving mainly dioecious populations, revealed that B. delicatulum displayed higher fertilization rates than B. macrosporum. A complementary explanation for a dioecious species to increase fertilization success was proposed consisting of outcrossing among intermingled male and female adjacent plants within an algal spot.
Natural populations of the Closterium ehrenbergii (Desmidiales, Chlorophyta) species complex in Nepal
Authors: Ichimura Terunobu 
Published: February 2006

SUMMARYSeveral natural populations of the Closterium ehrenbergii Meneghini ex Ralfs species complex were collected in Nepal, in October–December 1982. Water temperature and pH were also recorded. Clonal isolates from these populations were identified to one of four mating groups (H, I, J and M) by test crossing with standard mating‐type strains of known mating groups. Groups H and M have smooth walled zygospores, while Groups I and J have scrobiculated zygospore walls. Several undetermined isolates were found in some population samples. In contrast to the previously reported population samples from Nepal, especially from dried soil samples, some of these populations appeared to be rather heavily loaded with mutations that are deleterious to the sexual cycle (i.e. sexual compatibility, zygospore formation and germination). By genetic analysis, a zygote maturation‐defective mutation (zym) was detected. One reason for such a heavy genetic load was suggested to be that most population samples had been maintained exclusively by asexual reproduction for a long period in large lakes and nearby ponds, or left‐over vegetative populations in paddy fields after other members entered into dormancy through sexual reproduction. The significance of studying such mutations at sexual gene loci is discussed in the light of speciation problems in microalgae.
Hidden deleterious genetic factors affecting post‐meiotic viability in zygospore progeny of a unicellular haplontic alga, mating group A of the Closterium ehrenbergii species complex (Chlorophyta)
Authors: Ichimura Terunobu 
Published: February 2006

SUMMARYIn a haplontic green alga, mating group A of the Closterium ehrenbergii Meneghini ex Ralfs species complex, viability of meiotic progeny was studied by isolating two gone cells from a single germinating zygospore. In F1 progeny of a cross between mating‐type plus M‐16‐4a and mating‐type minus M‐16‐4b, studied in six independent experiments, percentage survivals varied little from 86 to 96 with a mean of 93 ± 1.4 SE. In F2 progenies of crosses among eight mating‐type plus and eight mating‐type minus F1 clones of the M‐16‐4a · M‐16‐4b cross, percentage survival varied considerably from 24 to 100, with a mean of 70.8 ± 2.2. In B1 progenies of the above eight mating‐type plus F1 clones, survival values were significantly different between backcrosses to the recurrent M‐16‐4b (range = 32–83, mean ± SE = 58.3 ± 6.8) and backcrosses to a genetically unrelated mating‐type minus, R‐13‐20, (85–97, 92 ± 1.6). Also in B1 progenies of the above mating‐type minus F1 clones, survival values were significantly different between backcrosses to the recurrent M‐16‐4a (56–90, 68.3 ± 4,4) and backcrosses to a genetically unrelated mating‐type plus, R‐13‐131 (78–93, 86.1 ± 1.6). Clearly, viabilities of meiotic progeny differed considerably between outbreedings (M‐16‐4a × M‐16‐4b, and F, clones × R‐13‐20 or R‐13‐131) and inbreedings (F2 and F1 clones × M‐16‐4a, or M‐16‐4b). These data suggest the presence of hidden deleterious genetic factors that may reduce viability of zygospore progeny if inbred between a pair of wild‐type strains from the normally outbreeding mating group A of the C. ehrenbergii species complex.
Temperature responses of macroalgae from the tropical island Hainan (P.R. China)
Authors: Bischoff‐Bäsmann Bettina , Bartsch Inka , Xia Bangmei , Wiencke Christian 
Published: February 2006

SUMMARYThe temperature tolerances of 24 tropical macroalgae collected on Hainan Island (P.R. China) were investigated. For some isolates, growth response curves were also determined. The upper survival temperatures (USTs, 32–37°C) of these tropical west Pacific strains are similiar to those of tropical Atlantic species. With regard to their lower survival temperatures (LSTs) the species investigated show high variations: 12 species have LSTs between 16 and 7°C (Hypnea musciformis (Wulfen) Lamx. var esperi J, Ag., Centroceras clavulatum (C. Ag) Mont., Falkenbergia hillebrandii (Bornet) Falkenberg, Gelidiopsis intricata (Ag.) Vickers, Halymenia maculata J. Ag., Hypnea cenomyce J. Ag., Hypnea spinella (C. Ag.) Kütz., Gracilaria changii (Xia et Abott) Abott, Chang et Xia, Dictyopteris repens (Okam.) Boerg., Laurencia cartilaginea Yamada, Gelidium pusillum (Stackh.) Le Jol., Laurencia sp.). Their LSTs and temperature requirements for growth (range: 15–30 °C, optimum: 25–30 °C) are mostly similar to those of tropical west Atlantic and amphi‐Atlantic (sub)tropical macroalgae as well as to tropical isolates of species with an Atlantic tropical to warm‐temperate distribution. The remaining 12 species have LSTs between 6 and 1 °C (Ulva conglobata Kjellm., Ulva fasciata Delile, Padina boryana Thivy, Dictyosphaeria cavernosa (Forssk.) Boerg., Boodlea composita (Harv.) Brand, Boergesenia forbesii (Harv.) Feldm., Cladophora vagabunda (L.) van den Hoek, Enteromorpha compressa (L,) Grev., Enteromorpha intestinalis (L.) Link, Gracilaria tenuistipitata Chang et Xia, var liui Chang et Xia, Monostroma nitidum Wittr. and Valonia aegagropila C. Ag.). Their LSTs are mostly similar to those of Atlantic macroalgae with a tropical to (warm‐) temperate distribution. The results are discussed with respect to the factors which may have triggered the development of the temperature requirements of the various species.
Ultrastructure of carpogonia and carpogonial branches of Batrachospermum helminthosum and Batrachospermum involution (Batrachospermales, Rhodophyta)
Authors: Sheath Robert G. , Müller Kirsten M. 
Published: February 2006

SUMMARYThe carpogonial branches of Batrachospermum involutum of section Batrachospermum are similar in ultrastructure to nearby fascicles, having uninucleate cells with abundant starch granules and several peripheral, well‐developed chloropiasts (up to 10 μm long). In contrast, the short carpogonial branch cells of Batrachospermum helminthosum (section Virescentia) have no visible starch and chloropiasts are reduced in size (up to 2 μm long) with few thylakoids. The breakdown of cross walls among cells of the carpogonial branch is also common in B. helminthosum but does not occur in B. involutum. As a result of cross wall breakdown in the former species, 2‐7 nuclei can occur in a continuous cytoplasm. Trichogynes in both species contain scattered mitochondria, vesicles/small vacuoles, osmiophilic globules, endoplasmic reticulum (ER) and small chloropiasts. Polylamellate structures also occur in the trichogyne in B. involution. The carpogonial base was fully observed only in B. involutum and it contains a prominent nucleus, ER, chloropiasts and a pit plug connecting it to the subtending carpogonial branch cell. Partial observations of carpogonial branches and carpogonia were made on four other members of the family Batrachospermaceae.
Morphology and life history of Coelocladia arctica (Dictyosiphonales, Phaeophyceae), new to Japan*
Authors: Kawai Hiroshi 
Published: February 2006

SUMMARYThe occurrence of Coelocladia arctica Rosenvinge (Dictyosiphonales, Phaeophyceae) is reported for the first time in the Pacific Ocean, from Oshoro, Hokkaido, Japan. The field material was approximately 30 mm in height, up to 300 M‐μn in diameter, 2‐3 times irregularly branched and provided with phaeophycean hairs and plurilocular sporangia. The thallus was composed of several (usually four) large, hyaline, rounded, isodiametric inner cells, with smaller sub‐cortical and pigmented cortical cells. The plurilocular sporangia were 3‐4 celled, often branched, and protruded from the cortical cells, arranged in a crown‐shaped complex. In culture, the plurispores germinated unipolarly leaving an emptied original spore wall, and developed into a branched protonema. Cells of the protonema as well as the erect thallus contained several disc‐shaped chloroplasts with pyrenoids. Uniseriate erect filaments arose from the protonema, then became polystichous and formed branches. Unilocular sporangia were never observed in the field or in cultured material. Erect thalli were formed under culture conditions of 5‐15°C, and developed a thick parenchyma at 5‐10°C, irrespective of the day length.
Cytomorphogenesis in cenocytic green algae. V. Segregative cell division and cortical microtubules in Dictyosphaeria cavernosa (Siphonocladales, Chlorophyceae)*
Authors: Okuda Kazuo , Mine Ichiro , Morinaga Takeshi , Kuwaki Norie 
Published: February 2006

SUMMARYDisassembly and reassembly of cortical microtubules (MT) during and after segregative cell division (SCO) in Dictyosphaeria cavernosa (Forssk.) Børgesen were observed using fluorescence microscopy. Parallel cortical MT in a mother cell were intact just after the initiation of SCD, but soon circular, MT‐free patches appeared. Protoplasmic contraction enlarged the patches, and in these areas, the protoplasm eventually became perforated. Long and undulating cortical MT were arranged densely in the reticulate protoplasm. During further protoplasmic contraction, cortical MT appeared to be random and decreased in density. Finally, short and random cortical MT were present in the segregated protoplasts. Parallel cortical MT reassembled in the expanding daughter cells. After the daughter cells came in contact with one another, a radial system of cortical MT was constructed at the side that faced the inside of the mother cell wall. A microtubule inhibitor (amiprophos methyl, APM) had no effect on SCO. Segregative cell division was not induced directly by mechanical wounding. A comparison between SCO and wound‐induced protoplasmic contraction was made.