Actin-mediated chloroplast movement in Griffithsia pacifica (Ceramiales, Rhodophyta)

Chloroplast banding occurs in Griffithsia pacifies Kylin in a daily rhythm. At the start of the light period, chloroplasts have a uniform distribution. During the light period chloroplasts move away from the ends of the cell leaving two chloroplast-free regions by mid-afternoon. Later in the light period these bands disperse as chloroplasts return to the ends of cell where they remain throughout the dark period. After enzyme treatment with β-glucuronidase to permeabilize cell walls, non-banded plants did not form bands after the addition of 5 μg ml^?1 cytochalasin B in dimethyl sulfoxide (DMSO). When enzyme-grown plants with chloroplast bands were treated with cytochalasin B, bands were retained for at least three days. Plants grown in media supplemented with β-glucuronidase or DMSO alone gave banding consistent with untreated controls. Staining of microfilaments with rhodamine-phalloidin before and after treatment with cytochalasin B gave results consistent with chloroplast movement studies. This is the first report of actin-mediated organelle movement in red algae.     

Ultrastructure of the differentiating zygotospores of Porphyra leucosticta (Rhodophyta)

The ultrastructure of zygotosporogenesis is described for the red alga Porphyra leucosticta Thuret. Packets of eight zygotosporangia, each packet derived from a single carpogonium are interspersed among vegetative cells. Zygotospore differentiation in Porphyra can be separated into three developmental stages. (i) Young zygotospores exhibit a nucleus and a large centrally located, lobed plastid with pyrenoid. Mucilage is produced within concentric membrane structures during their dilation, thus resulting in the formation of mucilage sacs. Subsequently, these sacs release their contents, initiating the zygotospore wall formation. Straight‐profiled dictyosomes produce vesicles that also provide wall material. During the later stages of young zygotospores, starch polymerization commences, (ii) Medium‐aged zygotospores are characterized by the presence of fibrous vacuoles. These are formed from the ‘fibrous vacuole associated organelles’. The fibrous vacuoles finally discharge their contents. (iii) Mature zygotospores are recognized by the presence of numerous cored vesicles produced by dictyosomes. Cored vesicles either discharge their contents or are incorporated into the fibrous vacuoles. There is a gradual reduction of starch granules during zygotospore differentiation. Mature zygotospores are surrounded by a fibrous wall, have a large chloroplast with pyrenoid and well‐depicted phycobilisomes but are devoid of starch granules.     

Additional analysis of chemical diversity in Laurencia nipponica (Ceramiales, Rhodophyta)

The red alga Laurencia nipponica Yamada (Rhodomelaceae, Ceramiales) is known to contain several chemical races, each of which is characterized by a particular, major halogenated secondary metabolite. Both field-collected and cultured plants of a population of this species found recently at Shikanoshima Island, Fukuoka Prefecture, southern Japan, produced C₁₅ bromoethers, (3E)-laureatin and (3E)-isolaureatin, and sesquiterpenoids, 2,10-dibromo-3-chloro-9-hydroxy-α-chamigrene and 2,10-dibromo-3-chloro-α-chamigrene. Laurencia nipponica can be referred to as a further chemical race that is characterized by the production of two C₁₅ bromoethers, (3E)-laureatin and (3E)-isolaureatin, and a sesquiterpenoid, 2,10-dibromo-3-chloro-9-hydroxy-α-chamigrene as major compounds.     

Changes in the Expression of β and Actins During Differentiation of PC 12 Cells

Cells of the rat pheochromocytoma line PC12 cease proliferation and develop neurites in response to nerve growth factor (NGF). Quantification of beta and gamma isoforms of nonmuscle actin in extracts of these differentiating cells showed that the beta:gamma ratio decreased from 1.30 +/- 0.05 to 0.99 +/- 0.05 after 6 days of NGF treatment. Cells treated with N6,O2-dibutyryl cyclic AMP (dbcAMP) also showed a shift in the ratio of beta:gamma isoforms, although few of these cells extended neurites. Administration of dbcAMP or both NGF and dbcAMP to cells accelerated the decrease in the beta:gamma actin isoform ratio relative to treatment with NGF alone. Those cells treated with both NGF and dbcAMP also showed an accelerated rate of neurite outgrowth. Suspension-grown PC12 cells treated with NGF showed neither an isoform ratio decrease nor neurite development. Our results suggest that either cyclic AMP may be a "second messenger" for NGF or it may effect the isoform ratio change by an independent mechanism. In addition, our data demonstrate an alteration in actin isoform expression, which accompanies the morphological differentiation of PC12 cells.     

Mastophoropsis canaliculata (Harvey in Hooker) gen. et comb. nov. (Corallinaceae,Rhodophyta) in Southern Australia

Mastophoropsis canaliculata (Harvey in Hooker) gen. et comb. nov. (Corallinaceae, Rhodophyta) is restricted to south-eastern Australian waters. It is unique among Corallinaceae in possessing an erect, tenacular, branched, taeniform, non-geniculate thallus which produces multiporate tetrasporangial conceptacles. Based on a detailed morphological and anatomical study, including an examination of the designated lectotype, this taxon is referred to the tribe Phymatolitheae in the subfamily Melobesioideae and its relationships to other non-geniculate Corallinaceae are discussed. A simplified microtechnique procedure involving decalcification with nitric acid, resin embedding and staining serially mounted sections with KMnO₄ also is outlined. X-ray microanalysis of surface tissues indicates that calcification occurs largely as CaCO₃ and that various structures contain substantially differing amounts of Ca.     

The reproductive structures of the Mediterranean alga Laurencia pelagosae (Ceramiales,Rhodophyta)

Reproductive structures of Laurencia pelagosae are described for the first time. Tetrasporangia, in parallel arrangement, are cut off from the mother cells adaxially; antheridial branches, which are unramified, are inserted in depressions lacking a row of axial cells on their bases; cystocarps are sessile and subspherical. The occurrence of secondary pit-connections between epidermal cells and of lenticular thickenings in the walls of medullary cells is documented. The species is included in the new section Pelagosae within the subgenus Laurencia.     

Isolation of a cDNA encoding a homologue of actin from Porphyra yezoensis (Rhodophyta)

We report the nucleotide sequence of a cDNA encoding an actin from amarine red alga, Porphyra yezoensis Ueda. A cDNA clone wasisolated from a leafy gametophyte cDNA library and analyzed for the sequence.The clone contained an open reading frame for a protein of 373 amino acidswhichexhibits sequence similarity to known actins. The GC content of the thirdposition (83.9%) was much higher than that at the first (56.3%) and second(42.4%) positions. The actin forms a gene family in the P.yezoensis genome. Comparison of the deduced amino acid sequenceshowed higher similarity to the Florideophycidae Chondruscrispus (85%) than to the ProtoflorideophycidaeCyanidioschyzon merolae (70%). The mRNA was detected inboth the leafy gametophytes and filamentous sporophytes. The nucleotidesequence data reported in this paper will appear in theDDBJ/EMBL/GenBank databases under accession number AB039831.     

The morphology and taxonomy of Womersleya monanthos, an endemic species and genus of Delesseriaceae (Ceramiales, Rhodophyta) from southeastern Australia

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.     

Developmental morphology of Odonthalia floccosa (Ceramiales, Rhodophyta) in laboratory culture

Material of the red alga Odonthalia floccosa (Esper) Fal-kenberg (Rhodomelaceae, Ceramiales), collected from California, was cultured in the laboratory and its life-history was completed. Tetraspores grew into bipolar sporelings that differentiated into a colorless rhizoidal portion and a pigmented upright shoot. The sporelings became compressed apically and formed lateral branches in a regularly distichous manner that were congenitally fused with the main axis. These tetraspore germlings grew into diecious gametophytes. Male ga-metophytes produced numerous spermatangia on modified fertile branchlets (male trichoblasts) that possessed three to four monosiphonous, proximal segments. Female gametophytes formed a single pro-carp on the suprabasal segment of unbranched female trichoblasts. Cystocarps developed on the female gametophytes cocultured with male gametophytes and released viable carpospores that developed into fertile te-trasporophytes. Tetrasporangia were produced from the third and fourth periaxial cells in each of 12–45 successive fertile segments and provided three (two lateral and one basal) cover cells. The occurrence of both spermatangia and procarps on fertile trichoblasts in O. floccosa suggests that the alga is the most derived in these two characters among the species of the genus Odonthalia. This species is distributed in cold temperate regions in the North Pacific, and it should be excluded from the North Atlantic marine algal flora.     

Taxonomic notes on Laurencia mariannensis (Rhodomelaceae, Rhodophyta)

The marine red alga Laurencia mariannensis Yamada (Rhodomelaceae, Ceramiales) is characterized by pale rose-red, softly fleshy, slender, terete axes (up to 600 μm in diameter), arising from a loosely entangled, stoloniferous basal system among species that have the following combination of features: the presence of longitudinally orientated secondary pit-connections between contiguous superficial cortical cells; the presence of projecting superficial cortical cells at the upper portions of branches; and the presence of lenticular thickenings in the walls of medullary cells, Furthermore, the presence of two or three corps en cerise per superficial cortical cell and one per trichoblast cell may characterize the species.     

Morphological and random amplified polymorphic DNA features in populations ofCeramium kondoi (Rhodophyta)

Morphological and RAPD features ofCeramium kondoi populations were investigated and compared in different locations in Korea. The plant length and branching pattern were more variable in Jindo population than others. RAPD data showed thatC. kondoi plants were divided into two clades; the southern group including Jindo and Bangpo population, and the northern group including Yonpyongdo and Oeyondo population. Morphological features inC. kondoi populations corresponded with RAPD data, which differed from those ofC. boydenii from the same location. These results suggest that RAPD might be useful for elucidating genetic variation among the wild populations ofC. kondoi.     

CERAMIUM INKYUII SP. NOV. (CERAMIACEAE,RHODOPHYTA) FROM KOREA: A NEW SPECIES BASED ON MORPHOLOGICAL AND MOLECULAR EVIDENCE1

Ceramium inkyuii sp. nov. is newly described based on samples collected from the east coast of Korea and compared with similar species such as C. paniculatum and C. tenerrimum. The new species is characterized by pseudo‐dichotomously branched thalli with a twist in the upper part, a single row of spines on the abaxial side, strongly inrolled apices, and the presence of gland cells. In contrast, C. paniculatum has alternate branches and lacks gland cells, and C. tenerrimum is spineless and also lacks gland cells. Ceramium inkyuii was observed to be an annual species producing tetrasporangia in the spring to summer and cystocarps in the fall. Plastid‐encoded rbcL and nuclear small subunit (SSU) rDNA sequences were determined in four samples of C. inkyuii from different locations and six samples of four putative relatives. All four C. inkyuii replicates from three different locations had identical sequences of each gene, and the interspecific sequence divergences were enough to warrant its natural entity. The phylogenies of the rbcL and SSU rDNA sequences also indicate the monophyly of C. inkyuii. The spinous C. inkyuii was more closely related to the spineless C. tenerrimum than to the spinous C. paniculatum.     

Growth of the conchocelis phase of Porphyra columbina (Bangiales, Rhodophyta) at different temperatures and levels of light, nitrogen and phosphorus

Temperature, light, nitrogen and phosphorus all had significant effects on the growth of conchocelis colonies of Porphyra columbina Montagne when grown in vitro using a shell substrate. High rates of growth were recorded at 15°C and at 8°C under low light levels. These fight and temperature conditions are similar to those found in the subtidal environment of southern New Zealand coastlines. Little growth occured at 22°C. Nitrogen stimulated growth at concentrations far greater than are likely to be found in situ, while at concentrations of 120 μmol/L and above phosphorus had an inhibitory effect on growth, The culture parameters were strongly interactive in their effect on growth, in particular temperature and light. Conchosporangia formed in all treatments 14 days after alteration of the photoperiod to 10 h light: 14 h dark. Optimal conditions for culture of the conchocelis of P. columbina from southern New Zealand are a water temperature of approximately 15°C, light levels between 10 and 50 μmol m^?2s^?1 and seawater nitrogen levels maintained above 100 μmol/L.     

Sesquiterpenoids of Laurencia majuscula (Ceramiales, Rhodophyta) from the Ryukyu Islands, Japan

Two populations of the red alga Laurencia majuscula (Harvey) Lucas (Rhodomelaceae, Ceramiales) from Taketomi Island and Hateruma Island, the Ryukyu Islands, Japan, have been characterized on the basis of both morphological features and halogenated secondary metabolite content. These populations have smaller and more slender thalli than those of other regions. Furthermore, the populations contain two chamigrane-type Sesquiterpenoids, (2R, 3R, 5S)-5-acetoxy-2-bromo-3-chlorochamigra-7(14),9-dien-8-one and (2R, 3R)-2-bromo-3-chlorochamigra-7(14), 9-dien-8-one, and a laurane-type sesquiterpenoid, debromoisolaurinterol, as secondary metabolites which are different from those previously reported from other populations. These results are consistent with the concept of ‘chemical races’ within a single species of Laurencia.     

Porphyra aeodis sp. nov. (Bangiales,Rhodophyta), an epiphyte of Aeodes orbitosa from South Africa

A new species of Porphyra is described from the south western Cape, South Africa. The gametophyte of Porphyra aeodis sp. nov. grows epiphytically on Aeodes orbitosa (Suhr) Schmitz, and has a seasonal life history that matches that of its host. Although P. aeodis has been confused with P. capensis Kützing in the past, P. aeodis is more similar to the sympatric but epilithic P. saldanhae Stegenga, Bolton et Anderson. There is considerable morphological overlap between P. aeodis and P. saldanhae, although they may be distinguished using a combination of morphological and ecological characters. The taxonomic separation of P. aeodis and P. saldanhae was confirmed using isozyme electrophoresis.     

On primary production in the South Bight of the North Sea

The area of the North Sea next to the Belgian and Dutch coasts has been surveyed since January 1971. The photosynthetic capacity (potential production) of samples collected at 63 stations and 4 depths has been measured using the ¹⁴C technique.

The homogeneity of the water column was demonstrated almost everywhere. A general pattern of decrease of the potential production from the coast to the open sea was demonstrated in all seasons. Figures ranged from 3 to 30 mg C m^-3 h^-1. Primary production was also determined both by calculations, using the Steemann Nielsen (1952) formula, and by in situ measurements. The higher turbidity near the coast has proved to limit considerably the primary production. Figures usually range from 100 to 1500 mg C m^-2 day^-1.

The following topics have also been discussed: relationship between photosynthetic capacity and pigment content, transparency of the water, solar radiation, comparison between production calculated from photosynthetic capacity and production measured in situ, and nutrient uptake.     

Porphyra monospore system (Bangiales, Rhodophyta): A model for the developmental biology of marine plants

We have developed an experimental system of cohort monospores from clonal culture of leafy gametophytes in Porphyra yezoensis Ueda (strain TU-1). This system is quite different from traditional systems for algal protoplast experimentation, which require expensive enzymatic treatment and utilize an ineffective method of preservation. Cohort monospores were obtained by utilizing a mode of asexual reproduction in the culture strain (monospores) and artificial regulation (thallus length, temperature, light, etc.) of monospore release. When the leafy gametophytes that formed monospores were frozen at - 20°C in a cryoprotective solution composed of 5% DMSO and 5% dextran in 100% seawater, about 98% survived for 3 months. When stored at 5°C without cryoprotectants, these leafy gametophytes could be kept without monospore release for 1 week. Maximum monospore yield was about 3000 spores per 100 gametophytes, and germination rate was about 70%, This system will accelerate developmental biology studies in Porphyra.     

Life history in culture of the obligate epiphyte Porphyra subtumens (Bangiales, Rhodophyta) endemic to New Zealand

This is the first report of the growth in culture of Porphyra subtumens J. Agardh ex Laing (Bangiales, Rhodophyta), an obligate epiphyte of Durvillaea species and endemic to New Zealand waters. Archeospores, previously observed on field material, develop directly into the blade phase. Spores released from field collected blades form conchocelis. Conchospores develop into new blades, completing the life history in culture. Earlier reports of reproduction in P. subtumens gave conflicting accounts with some authors citing this species as having an asexual, monophasic life history with an unusual form of spore production, while others described spermatangia and carposporangia on the blade phase.