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Pyropia nereocystis is an annual northeastern Pacific‐bladed bangialean species whose macroscopic stage epiphytized the annual canopy forming bull kelp Nereocystis luetkeana. I examined three in situ facets of these epiphyte‐host dynamics in the central California region: (1) spatial and temporal variation in the presence of P. nereocystis epiphytes as a function of host density, (2) the relationship between individual host morphology and epiphytic P. nereocystis biomass, and (3) the ecophysiological growth ramifications for subtidal transplants of both life stages of P. nereocystis. Swath canopy surveys and whole host collections were conducted at five sites between November 2017 and February 2019. Additionally, transplants of P. nereocystis gametophytes and sporophytes were conducted across multiple subtidal depths. I observed temporal changes in the proportions of hosts epiphytized by P. nereocystis, with differences in seasonal persistence of P. nereocystis among sites and between years. Biomass of P. nereocystis was positively correlated with individual host stipe length, stipe surface area, and the primary principal component (PC) of stipe morphometrics denoted by principal component analysis (PCA). Gametogenesis in P. nereocystis epiphytes was spatially heterogeneous and limited for the 2018–2019 cohort due to comprehensive removal of hosts by the February 2019 sampling period. Transplants of P. nereocystis gametophytes yielded similar growth responses among depths, and sporophyte (conchocelis) transplant areal growth was positively correlated with transplant depth. These findings detail spatiotemporal complexity and multi‐scale (individual, site, and whole region) phenological nuances for central Californian P. nereocystis epiphytes. [ABSTRACT FROM AUTHOR]

Porphyra corallicola was described based on a filamentous red alga inadvertently introduced into culture from a crustose coralline alga. This species is known only in its sporophyte (Conchocelis) stage, being possibly asexual and lacking the charismatic and "collectable" gametophyte stage. Consequently, little is known of its range and distribution. Taxon-targeted metabarcoding was explored as a pathway to gain insights into the vertical (intertidal versus subtidal) and biogeographical distribution of this species, as well as to assess host diversity. We also wanted to ascertain if other species occur in only the Conchocelis stage in the Canadian flora. Primers targeting a short (521 bp) region of the plastid rbcL gene in the Bangiales were used to screen DNA from 285 coralline crusts collected throughout Canada and adjacent waters. In addition to confirming the presence of P. corallicola in the Bay of Fundy, this species was recovered from coralline crusts along the coast of Nova Scotia (n = 1) and in the low Arctic (Labrador; n = 2), greatly extending its range and suggesting it is a cold-water taxon. We have confirmed its presence in both the low intertidal and subtidal (to 10 m), and its occurrence in three different coralline species, suggesting that it lacks host specificity. In total, nine genetic groups of Bangiales were uncovered in our survey, six matching entries currently in GenBank and three apparently novel genetic groups—two from the northeast Pacific and one from the low Arctic. Notable host and ecological patterns are discussed. This method, when further developed, will facilitate the study of Conchocelis stages in nature, which will greatly enhance ecological knowledge of bangialean species. [ABSTRACT FROM AUTHOR]

The species of the genus Pyropia have a diplohaplontic life cycle, in which there is a gametophytic phase (n) or blade, and a microscopic sporophytic phase (2n), known as conchocelis, as well as intermediate stages of development. Pyropia species, together with Porphyra species, belong to the group of the most commercialized and produced macroalgae worldwide, mainly due to their high nutritional value and high content of bioactive compounds with antioxidant and anti-inflammatory activity. The interest in cultivating and exploiting this marine resource has increased in recent years; nevertheless, despite the development of cultivation techniques and technologies for these species, there are still difficulties involved in their successful cultivation, mainly related to the great interspecific and intraspecific variability in the required culture conditions. In this work, we study the life cycle development of Pyropia orbicularis, a species endemic to the South Pacific, to determine the effect of abiotic culture parameters, such as the temperature and photoperiod, on the formation and development of early and late life cycle stages, such as conchocelis formation, cochoesporangial filaments, conchospore release and blade growth. Our results demonstrate that the conchocelis phase grew rapidly under 8:16 h (L:D) photoperiod conditions at both 15 °C and 20 °C. The lower temperatures favored the formation of conchosporangia and conchospores; the rate of their development was increased at 15 °C. The development of the blades in the suspended culture system was constant during the experimental period, generating blades of the same color and shape as those from natural populations. Our results reflect the adaptation of P. orbicularis to the seasonal environmental conditions it is exposed to and the importance of maintaining optimal abiotic parameters for the success of its culture. This work is the first to describe the full life cycle development of P. orbicularis under controlled conditions, which has important implications for commercial production.

Temperature is one of the major factors controlling the growth and development of Pyropia. Here, we set out to discover the most important changes arising at the growth rate, ultrastructure, lipids and low‐molecular‐weight carbohydrates of Neoporphyra haitanensis conchocelis under low temperature (12°C), mid‐temperature (23°C) and high temperature (28°C). Results showed that lower growth rate was at 12°C, while the conchosporangia formed under 28°C. Thicker cell wall was under 28°C. Larger size of plastoglobuli exhibited under 12°C. Less total contents of monogalactosyldiacylglycerols, digalactosyldiacylglycerols, sulfoquinovosyldiacylglycerols and phosphatidylinositols were under 12°C, while more total contents of phosphatidylcholines, phosphatidylethanolamines, phosphatidylglycerols and triglycerides were under 12°C. The ratio of unsaturated to saturated fatty acids in phosphatidylcholines, phosphatidylethanolamines, phosphatidylglycerols, monogalactosyldiacylglycerols, digalactosyldiacylglycerols, and sulfoquinovosyldiacylglycerols increased at 12°C and decreased at 28°C. The contents of floridoside and isofloridoside were more under 12 and 28°C than that under 23°C. Taken together, these findings indicated that temperature affected the physiological properties of Neoporphyra haitanensis. [ABSTRACT FROM AUTHOR]

Porphyra corallicola was described based on a filamentous red alga inadvertently introduced into culture from a crustose coralline alga. This species is known only in its sporophyte (Conchocelis) stage, being possibly asexual and lacking the charismatic and “collectable” gametophyte stage. Consequently, little is known of its range and distribution. Taxon-targeted metabarcoding was explored as a pathway to gain insights into the vertical (intertidal versus subtidal) and biogeographical distribution of this species, as well as to assess host diversity. We also wanted to ascertain if other species occur in only the Conchocelis stage in the Canadian flora. Primers targeting a short (521 bp) region of the plastid rbcL gene in the Bangiales were used to screen DNA from 285 coralline crusts collected throughout Canada and adjacent waters. In addition to confirming the presence of P. corallicola in the Bay of Fundy, this species was recovered from coralline crusts along the coast of Nova Scotia (n = 1) and in the low Arctic (Labrador; n = 2), greatly extending its range and suggesting it is a cold-water taxon. We have confirmed its presence in both the low intertidal and subtidal (to 10 m), and its occurrence in three different coralline species, suggesting that it lacks host specificity. In total, nine genetic groups of Bangiales were uncovered in our survey, six matching entries currently in GenBank and three apparently novel genetic groups—two from the northeast Pacific and one from the low Arctic. Notable host and ecological patterns are discussed. This method, when further developed, will facilitate the study of Conchocelis stages in nature, which will greatly enhance ecological knowledge of bangialean species.

Copyright of Journal of Hydrobiology is the property of Editorial Department of Journal of Hydrobiology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A wide range of tip-growing cells in plants display polarized cell growth, which is an essential cellular process for the form and function of individual cells. Understanding of the regulatory mechanisms underlying tip growth in terrestrial plants has improved. Cellular processes involved in tip growth have also been investigated in some algae species that form filamentous cells, but their regulatory mechanisms remain unclear. In the macro red alga Neopyropia yezoensis , for which genome information has recently been released, the conchocelis apical cell exhibits tip growth and forms a filamentous structure. Here, we report a live-imaging technique using high-resolution microscopy to analyze the tip growth and cell division of N. yezoensis conchocelis. This imaging analysis addressed tip growth dynamics and cell division in conchocelis apical cells. The directionality and tip growth expansion were disrupted by the application of cytoskeletal drugs, suggesting the involvement of microtubules (MTs) and actin filaments (AFs) in these processes. A growing apical cell mostly contained a single chloroplast that moved toward the expanding part of the apical cell. Drug application also inhibited chloroplast movement, implying that the movement may be dependent on the cytoskeleton. The study determined that live-imaging analysis is a versatile approach for exploring the dynamics of tip growth and cell division in N. yezoensis conchocelis, which provides insights into the regulatory mechanisms underlying cellular growth in multicellular red algae. [ABSTRACT FROM AUTHOR]

A wide range of tip-growing cells in plants display polarized cell growth, which is an essential cellular process for the form and function of individual cells. Understanding of the regulatory mechanisms underlying tip growth in terrestrial plants has improved. Cellular processes involved in tip growth have also been investigated in some algae species that form filamentous cells, but their regulatory mechanisms remain unclear. In the macro red alga Neopyropia yezoensis, for which genome information has recently been released, the conchocelis apical cell exhibits tip growth and forms a filamentous structure. Here, we report a live-imaging technique using high-resolution microscopy to analyze the tip growth and cell division of N. yezoensis conchocelis. This imaging analysis addressed tip growth dynamics and cell division in conchocelis apical cells. The directionality and tip growth expansion were disrupted by the application of cytoskeletal drugs, suggesting the involvement of microtubules (MTs) and actin filaments (AFs) in these processes. A growing apical cell mostly contained a single chloroplast that moved toward the expanding part of the apical cell. Drug application also inhibited chloroplast movement, implying that the movement may be dependent on the cytoskeleton. The study determined that live-imaging analysis is a versatile approach for exploring the dynamics of tip growth and cell division in N. yezoensis conchocelis, which provides insights into the regulatory mechanisms underlying cellular growth in multicellular red algae.

Copyright of Journal of Hydrobiology is the property of Editorial Department of Journal of Hydrobiology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Light quality is an important factor on regulating growth and development of algae. Two trials were conducted to evaluate the effect of light quality on filmentous conchocelis (sporophyte in the heteromorphic life cycle) of Pyropia haitanensis. Trial I studied the effect of white, blue, and green light on growth rate, ultrastructure, pigments, and the membrane lipids of P. haitanensis. In trial II, the effect of white, blue, and green light was evaluated on the formation of P. haitanensis conchosporangia. In trial I, growth rate decreased 28.54% under blue light compared with white light, and no difference was observed under green and white light. Compared with white light, chlorophyll a and carotenoid reduced under blue (23.95%, 22.76%) and green (41.21%, 37.90%), and phycoerythrin and phycocyanin under green decreased 53.56% and 45.64%. The content of membrane lipids significantly decreased under blue (81.15%) and green (85.63%), and the ratio of unsaturated to saturated fatty acids decreased under blue and green. The cell wall under green light was thicker (0.153 ± 0.014 μm) than blue (0.117 ± 0.010 μm) and white light (0.121 ± 0.011 μm). Larger size of plastoglobuli exhibited under green (3.23 × 10−4 ± 1.95 × 10−4 μm3) than under white (3.97 × 10−5 ± 1.70 × 10−5 μm3) and blue light (1.41 × 10−4 ± 7.91 × 10−5 μm3). Starch granules occurred only under green light. In trial II, blue light enhanced conchosporangial branch formation, while green light inhibited conchosporangial branch formation compared with white light. Taken together, these findings indicated that light quality effected growth, ultrastructure, pigments, and lipids of P. haitanensis. [ABSTRACT FROM AUTHOR]

Bladed Bangiales of the genus Porphyra/Pyropia are highly valuable red algae and extensively farmed in South East Asia. Interest is rising in cultivating species local to the North East Atlantic but the control of the heteromorphic life cycle of native species remains difficult as previous studies reported high inter- and intraspecific variability in required cultivation conditions. Here, working with Porphyra dioica from a UK source population, we conducted a series of experiments investigating the influence of substrate, temperature, photoperiod and light intensity on the development of early life history stages (conchocelis (filamentous sporophyte) and young thalli (gametophyte)). Special focus was the influence of temperature and photoperiod on mature conchocelis to induce a conchospore mass release—the current bottleneck of European Porphyra cultivation. Sporophytes grew largest on an oyster shell substrate and under long day conditions at 18 °C. A decrease in temperature from 18 to 9 °C initiated a mass conchospore release (498 ± 146 spores mL−1) from a P. dioica conchocelis culture grown in suspension. Released conchospores germinated into small thalli on nylon ropes, with best growth (7.2 ± 0.9% day−1) at low temperatures of 9 °C. Conchospore germination increased with decreasing light intensity but germination success was generally very low (< 5%), indicating the cultivation protocol needs further improvement. Our results reflect the adaptation of P. diocia to seasonal environmental conditions in temperate regions and the importance of these conditions for the successful cultivation. We are the first to describe a mass conchospore release for P. diocia growing in suspension which has important implications for commercial production. [ABSTRACT FROM AUTHOR]

In the present study, karyological observations on Pyropia suborbiculata (Bangiophycidae) at various stages of the life cycle were carried out. Living material of different life cycle stages of Py. suborbiculata were fixed in Carnoy's fixative fluid and stored under the light conditions of 60–80 μmol photons m−2 s−1 to leach phycobilin pigments and then the samples were stained with Wittmann's aceto-iron hematoxylin chloral hydrate and examined under a photomicroscope. The results indicated that vegetative cells, spermatangia, and carpogonia in gametophytic blade phase were haploids (n = 3), while zygotospores, vegetative cells, and conchosporangial branch cells in conchocelis phase were diploids (2n = 6). Meiosis occurred during the initial two-cell divisions of the germinating conchospores. Subsequently, the chromosome changed from diploid (2n = 6) to haploid (n = 3). When the blades released monospores for asexual reproduction, both the monospores and the cells of their germlings were haploid karyotypes (n = 3). In addition, when filamentous conchocelis cells at different developmental stages underwent mitosis, pairing of homologous chromosomes would occur in the nucleus during the prophase of division. [ABSTRACT FROM AUTHOR]

Abstract Pyropia aquaculture industries have grown in a recent year, but information is still lacking regarding cultivation techniques for early life stages. In this study, photosynthetic performance and growth of Pyropia dentata in the conchocelis phase was investigated under various culture conditions. Specifically, we used culture conditions with different temperature (10, 15, and 20 °C), light intensity (20 and 70 μmol photons m−2 s−1), and light type (LED Blue , LED Red , LED Blue+Red , and fluorescent lamp) combinations. Photosynthesis was measured using chlorophyll fluorometry (Mini-PAM) after 3 weeks of acclimation under various experimental conditions. Additionally, image analysis was used to determine growth and estimate the 2-dimensional area of complicated conchocelis structures. Results showed that growth rates significantly increased under higher temperatures (15 and 20 °C), but light intensity did not significantly influence photosynthesis and growth. LED Blue+Red and LED Blue treatments had higher growth rates and photosynthetic efficiency than LED Red and fluorescent lamp treatments after the 3-week acclimation period. However, higher photochemical capacity (photosynthesis) was clearly observed in the low temperature condition; thus, depressed growth rates in the low temperature condition are not indicative of physiological senescence of P. dentata conchocelis. Based on these results, we established optimized laboratory cultivation conditions for the conchocelis phase of P. dentata. Specifically, we found that this species requires a higher cultivation temperature to ensure optimal growth. Also, mixing red and blue or solitary blue light sources could be an efficient stabilized laboratory cultivation technique. Highlights • We established optimal culture conditions for the growth of Pyropia dentata in a conchocelis phase (20 °C and blue or blue + red LED light source). • High photosynthesis and low growth under low temperature indicate that the energetic balance is inefficient under stressful conditions. • Light intensity (20 and 40 μmol photons m−2 s−1) had no effect on photosynthesis and growth. [ABSTRACT FROM AUTHOR]

Seaweeds are a recognized source of bioactive compounds and techno-functional ingredients. However, its protein fraction is still underexplored. The aim of this study was to determine the total and free amino acid profile and protein content of four seaweeds species (Porphyra dioica, Porphyra umbilicalis,Gracilaria vermiculophylla, and Ulva rigida) produced in an integrated multi-trophic aquaculture system, while assessing their protein quality. Samples were submitted to acid and alkaline hydrolysis (total amino acids) and to an aqueous extraction (free amino acids) followed by an automated online derivatization procedure, and analyzed by reverse phase-high performance liquid chromatography. Protein-, non-protein and total-nitrogen were quantified by the Kjeldahl method. Crude and true protein contents were estimated based on the nitrogen and amino acid composition. Protein quality was assessed based on the amino acids profile. Porphyra species presented the highest protein content compared to the remaining three seaweed species tested. All samples presented a complete profile of essential amino acids and a high quality protein profile, according to World Health Organization and Food and Agriculture Organization standards. Methionine and tryptophan were the first limiting amino acids in all species. Red species (Porphyra and Gracilaria) presented high levels of free alanine, glutamic, and aspartic acids. The results highlight the potential of using seaweeds as an alternative and sustainable source of protein and amino acids for human nutrition and industrial food processing.

High-temperature stress related to global warming reduces the growth and productivity of seaweeds. Thus, the development of new strains is urgently required for maintaining or even enhancing the productivity of useful seaweeds such as red alga Pyropia yezoenesis in an increasingly warmer sea environment. To develop competitive high-temperature-tolerant strains of P. yezoensis (Sugwawon no. 104), we screened libraries of gamma-irradiated strains and identified high-temperature-resistant (HTR) mutants. Our results showed that HTR-1 and HTR-2 grew well at higher temperatures that inhibited the growth of the wild-type strain. The efficiency of conchosporangium maturation and conchospore release of HTR-1 was similar to or higher than the wild-type strain. Moreover, thallus growth, pigment content, photosynthetic efficiency, and monospore release from the growing thallus in HTR-1 could be maintained even at high temperature. Taken together, our data demonstrate that HTR-1 may be suitable for industrial cultivation at sea, even at elevated temperatures. [ABSTRACT FROM AUTHOR]

Porphyra dioica is a commercial seaweed consumed all over the world, mostly in the shape of nori sheets used for "sushi" preparation. It is a well-known part of the Asian diet with health benefits, which have been associated, among others, to the high levels of n-3 and n-6 fatty acids in this red alga. However, other highly valued lipids of Porphyra are polar lipids that remain largely undescribed and can have both nutritional value and bioactivity, thus could contribute to the valorization of this seaweed. In this context, the present work aims to identify the lipidome of two life cycle stages of the Atlantic species Porphyra dioica: the early life stage conchocelis produced in an indoor-nursery, and young blades produced outdoors using an integratedmultitrophic aquaculture (IMTA) framework. Both the blades (gametophyte) and conchocelis (sporophyte) are commercialized in the food and cosmetics sectors. Liquid chromatography coupled to Q-Exactive high resolution-mass spectrometry (MS) platform was used to gain insight into the lipidome of these species. Our results allowed the identification of 110 and 100 lipid molecular species in the lipidome of the blade and conchocelis, respectively. These lipid molecular species were distributed as follows (blade/conchocelis): 14/15 glycolipids (GLs), 93/79 phospholipids (PLs), and 3/6 betaine lipids. Both life stages displayed a similar profile of GLs and comprised 20:4(n-6) and 20:5(n-3) fatty acids that contribute to n-3 and n-6 fatty acid pool recorded and rank among the molecular species with higher potential bioactivity. PLs' profile was different between the two life stages surveyed, mainly due to the number and relative abundance of molecular species. This finding suggests that differences between both life stages were more likely related with shifts in the lipids of extraplastidial membranes rather than in plastidial membranes. PLs contained n-6 and n-3 precursors and in both life stages of Porphyra dioica the n-6/n-3 ratio recorded was less than 2, highlighting the potential benefits of using these life stages in human diet to prevent chronic diseases. Atherogenic and thrombogenic indexes of blades (0.85 and 0.49, respectively) and conchocelis (0.34 and 0.30, respectively) are much lower than those reported for other Rhodophyta, which highlights their potential application as food or as functional ingredients. Overall, MS-based platforms represent a powerful tool to characterize lipid metabolism and target lipids along different life stages of algal species displaying complex life cycles (such as Porphyra dioica), contributing to their biotechnological application. [ABSTRACT FROM AUTHOR]

Conchocelis is the sporophyte generation of Porphyra sensu lato, and free-living conchocelis is the main form used for preserving the germplasm. Avoiding microbial contamination caused by algal-associated bacteria (AAB) and ensuring the cleanliness of germplasm are important tasks for the preservation of Porphyra germplasm. In this study, we applied dominant bacteria enrichment comprehensive treatment (DBECT) to purify the conchocelis by enriching the dominant bacteria (Ruegeria scottomollicae S1) to occupy the niches of AAB and then remove them via antibiotics. The results showed that DBECT could efficiently remove AAB of Porphyra conchocelis germplasm, the abundance of which decreased 2000 times that of cultures treated with combined antibiotic cocktail methods. The diversity of AAB was reduced. In addition, adding R. scottomollicae S1 could adjust the community composition of algal microorganisms and increase the proportion of beneficial bacteria. Thus, DBECT can effectively purify Porphyra germplasm and provide ultra-clean algal samples for further research. [Display omitted] • Dominant bacteria enrichment comprehensive treatment (DBECT) could purify Porphyra conchocelis. • Ruegeria scottomollicae S1 is the dominant bacteria being enrichment. • DBECT involves sterilization → enrichment of Ruegeria scottomollicae S1 → sterilization. • DBECT reduces algal bacteria 2000 times more than antibiotic cocktail treatment. [ABSTRACT FROM AUTHOR]

Pyropia dentata is a promising species for aquaculture in South China. To develop an efficient protocol for seedling culture, the growth, development, and physiological changes of P. dentata conchocelis were investigated under different temperatures, irradiances, photoperiods, and salinity. After 25 days, conchosporangia formation at 28 °C was 5-7-fold of that at 25 and 31 °C. The percentage of conchosporangia increased as day length increased from 8 to 12 h and then decreased sharply under day length ≥14 h, with no conchosporangia observed under 24L:0D. By contrast, long day length (≥14 h) and lower temperature (≤25 °C) favored the vegetative growth of conchocelis. Conchosporangia formation peaked at 28 °C, 12L:12D, and 40-60 μmol photons m s. The highest F / F , P , and P / R also occurred at 28 °C and/or 12L:12D, which might provide energy for conchosporangia formation. Total soluble proteins (TSPs) content decreased while relative growth rate increased as irradiance and day length increased. Increasing irradiance and day length, and at temperatures of 31 °C caused a reduction in phycoerythrin and chlorophyll a content. However, allophycocyanin content increased at 31 °C and the content of phycocyanin, carotenoids, and TSPs remained steady from 25 to 31 °C. Growth, development, P , content of TSPs and pigments were similar at 25-40 ppt. F / F decreased and R increased significantly at salinities ≥35 ppt. These findings provide informative data on the mechanisms of Pyropia conchocelis development, and help establish an efficient seedling culture protocol for this P. dentata strain. [ABSTRACT FROM AUTHOR]

Porphyra dioica is a commercial seaweed consumed all over the world, mostly in the shape of nori sheets used for “sushi” preparation. It is a well-known part of the Asian diet with health benefits, which have been associated, among others, to the high levels of n-3 and n-6 fatty acids in this red alga. However, other highly valued lipids of Porphyra are polar lipids that remain largely undescribed and can have both nutritional value and bioactivity, thus could contribute to the valorization of this seaweed. In this context, the present work aims to identify the lipidome of two life cycle stages of the Atlantic species Porphyra dioica: the early life stage conchocelis produced in an indoor-nursery, and young blades produced outdoors using an integrated multitrophic aquaculture (IMTA) framework. Both the blades (gametophyte) and conchocelis (sporophyte) are commercialized in the food and cosmetics sectors. Liquid chromatography coupled to Q–Exactive high resolution-mass spectrometry (MS) platform was used to gain insight into the lipidome of these species. Our results allowed the identification of 110 and 100 lipid molecular species in the lipidome of the blade and conchocelis, respectively. These lipid molecular species were distributed as follows (blade/conchocelis): 14/15 glycolipids (GLs), 93/79 phospholipids (PLs), and 3/6 betaine lipids. Both life stages displayed a similar profile of GLs and comprised 20:4(n-6) and 20:5(n-3) fatty acids that contribute to n-3 and n-6 fatty acid pool recorded and rank among the molecular species with higher potential bioactivity. PLs’ profile was different between the two life stages surveyed, mainly due to the number and relative abundance of molecular species. This finding suggests that differences between both life stages were more likely related with shifts in the lipids of extraplastidial membranes rather than in plastidial membranes. PLs contained n-6 and n-3 precursors and in both life stages of Porphyra dioica the n-6/n-3 ratio recorded was less than 2, highlighting the potential benefits of using these life stages in human diet to prevent chronic diseases. Atherogenic and thrombogenic indexes of blades (0.85 and 0.49, respectively) and conchocelis (0.34 and 0.30, respectively) are much lower than those reported for other Rhodophyta, which highlights their potential application as food or as functional ingredients. Overall, MS-based platforms represent a powerful tool to characterize lipid metabolism and target lipids along different life stages of algal species displaying complex life cycles (such as Porphyra dioica), contributing to their biotechnological application.

Traces of microboring microbial endoliths (euendoliths) conform closely to the outlines of their makers as they are made. This habit evolved among prokaryotic cyanobacteria and eukaryotic rhodophytes, chlorophytes, and fungi. Among eukaryotic microborers, the endolithic mode of life is often limited to a phase in the course of their development, which alternates with an epilithic leafy phase. These endolithic phases are sometimes independently described as separate genera and species. This was the case withConchocelis roseaBatters, 1891, later identified as the endolithic phase ofPorphyraandBangiathat helped in identification of fossil bangialean rhodophytes of Silurian age:Palaeoconchocelis starmachiiCampbell, Kazmierczak et Golubic, 1979. However, the traces of Conchocelis phases, although conspicuous and used to characterize the resident body fossil, were never formally described. We present here the formal ichnotaxonomic description of the complex and variable Conchocelis trace asConchocelichnus seilacheriigen. et isp. nov., based primarily on Oligocene (Tertiary) borings in molluscan shells of Mainz Basin, Germany, while consulting similar fossil borings of the Silurian and Jurassic findings and compareing them with modern occurrences in nature and culture. With the new trace nameConchocelichnus seilacheriigen. et isp. nov., we honor the work of the renowned paleontologist and ichnologist, Prof. Dr. Dolf Seilacher. [ABSTRACT FROM AUTHOR]

Microboring or euendolithic microorganisms, which colonize and penetrate various carbonate substrates, are abundant in coral reef ecosystems and play a major role in reef carbonate dissolution. A few studies reported the presence of euendoliths in stylasterid coral skeletons but the biological identity, distribution and abundance of these microorganisms remain largely unknown. Observations of over 100 stylasterid colonies, collected in the Indo-Pacific area, revealed for the first time that the association between these corals and euendolith organisms appears to be quite common in shallow tropical waters. The most abundant euendolith was identified as a cryptic stage in the development of the rhodophytePorphyra(Conchocelis stage). The euendoliths were observed in the skeletons of seven species of three genera (fourStylaster, twoDistichoporaand oneLepidotheca). The presence of euendoliths inside skeletons conferred a particular colour to the studied stylasterid corals. Distribution and abundance of microborings varied significantly among stylasterid species and among branches of a single colony and so did the colour of their skeletons. Colonization of skeletons and the associated colour distribution were almost uniform in some stylasterids, forming an upward gradually diminishing or sharply limited gradient. This study shows that patterns of euendolith colonization and growth in stylasterid skeletons may depend on the stage of the euendolith development as well as on their environmental requirements such as light exposure. [ABSTRACT FROM AUTHOR]

Effects of light and temperature on conchocelis growth of Pyropia hollenbergii were evaluated with the hypothesis that conchocelis phase is most adapted to environmental extremes as compared to the gametophyte phase. Growth rates were measured weekly over a 3-month experimental period. Our results have shown that the best growth rate was 6.4 to 7.5 % area day at 25 °C, at photon fluence rates between 50 and 150 μmol photons m s and at a photoperiod of 15:9 h L: D. The upper temperature tolerance limit of Py. hollenbergii was at 33 °C at a photon fluence rate between 10 and 50 μmol photons m s and photoperiods of 9:15 and 12:12 h L:D. At a temperature of 5 °C, growth was inhibited (<0.5 % area day), but no mortality was observed. Archeospores were detected at 5-35 °C. Maximum archeospore production was observed at 5-10 °C, 50-150 μmol photons m s, and at 9:15 h L:D. The highest number of conchosporangia was detected at 15-20 °C, 100-150 μmol photons m s, and at 15:9 h L:D. The conchocelis phase of Py. hollenbergii is the critical perennating phase and is adapted to survive the highest temperatures in its habitat in the Gulf of California. The monospore and conchosporangium production is controlled by the combination of the temperatures and photon fluence rates. [ABSTRACT FROM AUTHOR]

White spot disease is the most frequent and harmful disease affecting the shell-boring conchocelis stage of the economically important red alga Porphyra yezoensis (= Pyropia yezoensis (Ueda) Hwang & Choi) (Bangiales, Rhodophyta). To date, its potential pathogens and pathogenesis remain poorly understood. In this study, we isolated 7 bacteria, 26 fungi, and 10 actinomycetes from sick conchocelis. Re-infection experiments revealed that only one fungus, GF014, caused disease. Morphological characteristics of the colony, mycelium, sporangium, and spore of GF014 suggested that the strain belongs to the order Pleosporales and the genus Phoma. Classification based on internal transcribed spacer (ITS) sequences supported the results of morphological identification. These results indicate that GF014 is a species of Phoma and a specific pathogen for Porphyra. GF014 preferred organic nitrogen sources, and 20-28 °C and low salinity water were its optimal living conditions. Our findings will play an active role in preventing and treating white spot disease in P. yezoensis. [ABSTRACT FROM AUTHOR]

Photosynthetic characteristics of four Porphyra yezoensis Ueda [a taxonomic synonym of Pyropia yezoensis (Ueda) M. S. Hwang et H. G. Choi] strains in conchocelis phase were investigated and compared with one wildtype of P. yezoensis and two strains of Porphyra haitanensis T. J. Chang et B. F. Zheng [a taxonomic synonym of Pyropia haitanensis (T. J. Chang et B. F. Zheng) N. Kikuchi et M. Miyata]. Results showed that experimental strains had higher contents of chl a and carotenoids, but a lower content of total phycobiliproteins than the wildtype. Meanwhile, photochemical efficiency of PSII was measured using pulse amplitude modulation (PAM) fluorometry technology. The value of PSII photosynthetic parameters of P. yezoensis strains were all higher than the wild strain, and the maximal quantum yields ( Fv/ Fm), effective quantum yields Y(II), and relative photosynthetic electron transport rates (rETR) of P. haitanensis were higher than those of P. yezoensis. The present study verified the possibility of selective breeding of P. yezoensis using the filamentous sporophyte instead of the gametophytic thallus, the advantages being (i) nonrequirement of control of life cycle and (ii) direct and rapid cultivar improvement by artificial selection. We consider the method to be a promising technique for selective breeding of P. yezoensis cultivars. [ABSTRACT FROM AUTHOR]

Photosynthetic characteristics of four Porphyra yezoensis Ueda [a taxonomic synonym of Pyropia yezoensis (Ueda) M. S. Hwang et H. G. Choi] strains in conchocelis phase were investigated and compared with one wildtype of P. yezoensis and two strains of Porphyra haitanensis T. J. Chang et B. F. Zheng [a taxonomic synonym of Pyropia haitanensis (T. J. Chang et B. F. Zheng) N. Kikuchi et M. Miyata]. Results showed that experimental strains had higher contents of chl a and carotenoids, but a lower content of total phycobiliproteins than the wildtype. Meanwhile, photochemical efficiency of PSII was measured using pulse amplitude modulation (PAM) fluorometry technology. The value of PSII photosynthetic parameters of P. yezoensis strains were all higher than the wild strain, and the maximal quantum yields ( Fv/ Fm), effective quantum yields Y(II), and relative photosynthetic electron transport rates (rETR) of P. haitanensis were higher than those of P. yezoensis. The present study verified the possibility of selective breeding of P. yezoensis using the filamentous sporophyte instead of the gametophytic thallus, the advantages being (i) nonrequirement of control of life cycle and (ii) direct and rapid cultivar improvement by artificial selection. We consider the method to be a promising technique for selective breeding of P. yezoensis cultivars. [ABSTRACT FROM AUTHOR]

L ópez-V ivas J.M., P acheco-R uiz I., R iosmena-R odríguez R. and Y arish C. 2011. Life history of Dawson (Bangiales, Rhodophyta) from the Gulf of California, México. Phycologia 50: 520-529. DOI: 10.2216/10-58.1 The life history of Dawson, a species endemic to the Gulf of California (Mexico), was investigated in relation to temperature, photoperiod and photon fluence rates. The hypothesis was that its life history is controlled by extremes of temperature (< 10°C to > 30°C), photoperiod (short/neutral/long) and photon fluence levels (low/high light). Culture experiments were set up using a factorial 5 × 5 × 3 design with five photon fluence levels (10, 20, 40, 60 and 80) µmol photons m−2 s−1), five temperatures (10, 15, 20, 25 and 30°C) and three photoperiods [[8∶∶16, 12∶∶12 and 16∶∶8 light∶∶dark (L∶∶D)]]. For the gametophyte phase, the optimal release of zygotospores was at 15°C, with photon fluence level of 60 µmol photons m−2 s−1 and long photoperiod 16∶∶8 L∶∶D. Germination was best at 20°C, a photon fluence level of 60 µmol photons m−2 s−1 and under a long photoperiod 16∶∶8 L∶∶D. The abundance of archeospores differed significantly at temperatures of 25 and 30°C. The number of archeospores mm−2 of the conchocelis tufts was significantly different in the long photoperiod 16∶∶8 L∶∶D when compared with the neutral 12∶∶12 and short 8∶∶16 L∶∶D. The abundance of conchosporangia at temperatures of 15, 25 and 30°C were different and differed from the other conditions. In addition, abundance of conchosporangia mm−2 were significantly different in all photoperiod treatments. Conchospores were released after 6 weeks at 10°C, 20 µmol photons m−2 s−1 at 8∶∶16 L∶∶D. On the basis of our results, we found that water temperatures were the limiting factor for conchocelis growth. However, it is the combination of photoperiod and high water temperatures that are the environmental conditions that appear to control the development of archeospores and conchospores. life history is controlled by an array of factors at each stage, strongly suggesting the environmental influence of the habitat on this species. [ABSTRACT FROM AUTHOR]

The indoor cultivation of the free-living conchocelis of a Porphyra purpurea (Roth) C. Ag. strain, isolated from Long Island Sound, was established, and the effects of both photoperiod and cultural temperature on conchosporangia development were studied. Statistical analysis revealed that temperatures between 10°C and 15°C and light phases between 12 and 16 h per day comprised an ideal growth 'window' for both the vegetative growth and reproductive development of conchocelis. For vegetative growth, there was a significant interaction between temperature and photoperiod. Conchospores were released from mature conchosporangia under both neutral (12/12 h) and long (16/8 h) day lengths. Different seawater supplements, such as full- and half-strength Von Stosch enrichment, showed no significantly different effects on growth or development. This work provides a guideline for maintaining conchocelis cultures of P. purpurea, which is a type of the Porphyra genus. [ABSTRACT FROM AUTHOR]

Previous study has shown that Porphyra conchocelis is sensitive to high levels of PAR (400–700 nm) as well as ultraviolet radiation (UVR: 280–400 nm), resulting in high inhibition of photosynthesis. However, little is known about whether the inner covering layer of the shell, in which the conchocelis lives, may provide protection against solar UVR. Our study indicates that the covering calcareous matrix is about 0.06 mm thick, transmitting 63, 47, and 28% of PAR, ultraviolet radiation A (UVA: 315–400 nm), and ultraviolet radiation B (UVB: 280–315 nm), respectively. We used a shading layer that simulated the above transmissions, and the effective quantum yield of PSII and photosynthetic carbon fixation in the conchocelis increased to greater extents in the presence of UVA or UVB. Attenuation of UVA by 19% and UVB by 37% due to the shading layer increased the PSII yield by 44%–77% and photosynthetic carbon fixation by about 60%. Our study clearly shows that the photosynthetic machinery of Porphyra haitanensis T. J. Chang et B. F. Zheng conchocelis was efficiently protected from harmful UVR by the covering calcareous matrix. [ABSTRACT FROM AUTHOR]

The large-scale cultivation of macroalgae has the potential to act as a carbon sink because macroalgae can release a large amount of organic carbon into the surrounding seawater. However, this needs to be evaluated on the basis of the entire life cycle under a background of changes in pH and light intensity. The present study investigated the difference in organic carbon release between conchocelis and thallus stages of the economically important red alga Pyropia haitanensis in response to three light intensities (10, 50, and 500 μmol m−2 s−1) and two pH conditions (current pH: 8.1, projected future pH: 7.5). The study found that regardless of the light intensity and pH values, the growth rates, production rates of tissue carbon, and dissolved organic carbon (DOC) of thalli tended to be higher than those of conchocelis, by more than 170%, 85%, and 106%, respectively. The DOC production rate was higher than the production rate of particulate organic carbon (POC) by at least two orders of magnitude. Positive correlations were found between growth rate and production rates of tissue carbon and growth rate and DOC production rate, but no clear relationship was found between growth and POC production. The DOC production rate of thallus tended to increase with light intensity but was not significantly influenced by ocean acidification. However, decay of tissue caused by exposure of the conchocelis to high light intensity resulted in increased POC and DOC production rates, indicating the complexity of organic carbon release by P. haitanensis. This study provides insights into the release of organic carbon during the complete life cycle of P. haitanensis , and the results can further our understanding of the carbon metabolism of this cultivated macroalgal species. • DOC production rate of thallus was much higher than that of conchocelis. • DOC production rate of thallus tends to increase with light intensity. • Ocean acidification did not significantly change the DOC production rate of thallus. [ABSTRACT FROM AUTHOR]

Abstract: The free living conchocelis of Porphyra yezoensis Ueda was treated with N-methyl-N-nitro-N-nitrosoguanidine to induce pigmentation mutants. The artificial green pigmentation mutant of P. yezoensis conchocelis, which was composed entirely of green cells, was isolated through visualization with the unaided eye. The acquired green conchocelis was further developed into a green gametophytic blade. This mutant was relatively stable in color in both gametophytic blade and conchocelis phases. The gametophytic blade mutant was successively cultivated for commerce at some Porphyra farms in Rudong, China, and few wild type or sectorially variegated gametophytic blade occurred, indicating that the green mutant has commercial value. The green mutant was characterized as having lower phycoerythrin and higher phycocyanin content, and SDS-PAGE suggested that phycoerythrin was missing the γ-subunit in comparison to the wild type. The wild type and the green mutant showed a clear difference in O2 evolution rates in white, green, yellow, and red light, which might be due to the qualitative and quantitative changes of phycoerythrin, and the quantitative difference of phycocyanin. [Copyright &y& Elsevier]

Abstract: Bangia fuscopurpurea (Rhodophyta) was cultivated in Putian (Fujian province, China). The characteristics of the life history concerned with cultivation were investigated and the cultivation procedure was presented. The gametophytic phase (thallus) and the sporophytic phase (conchocelis) occurred alternately in the life history of B. fuscopurpurea. Young thalli produced archeospores, and the number depended on the environmental factors. Temperature affected the number of archeospore release and percent of germination, and photo flux density (PFD) mainly affected the time of spore release and germination. Thalli matured from December to February and developed into the conchocelis phase through sexual reproduction. The conchocelis grown in shells had three developmental stages: vegetative conchocelis, conchosporangial formation and conchospore formation. Pit-connections were present in the first 2 stages but absent after conchospore formation. Vegetative conchocelis and conchosporangial branches can transform into each other. However, conchospores only developed into the gametophytic phase. Cultivation of B. fuscopurpurea was based on characterization of the life history, consisting of 3 steps: zygotospores collection, indoor cultivation of conchocelis and outdoor cultivation of thalli. Young thalli that developed from conchospores produced numerous archeospores before December. Over 90% of the crop was from the development of archeospores. The results indicated that conchosporelings were a good source of archeospores, and the development of the large quantity of archeospores acted as a more prevailing means to increase the population size. [Copyright &y& Elsevier]

Photosynthesis and respiration of three Alaskan Porphyra species, P. abbottiae V. Krishnam., P. pseudolinearis Ueda species complex (identified as P. “ pseudolinearis” below), and P. torta V. Krishnam., were investigated under a range of environmental parameters. Photosynthesis versus irradiance ( P– I) curves revealed that maximal photosynthesis ( Pmax), irradiance at maximal photosynthesis ( Imax), and compensation irradiance ( I c) varied with salinity, temperature, and species. The Pmax of Porphyra abbottiae conchocelis varied between 83 and 240 μmol O2 · g dwt−1 · h−1 (where dwt indicates dry weight) at 30–140 μmol photons · m−2 · s−1 ( Imax) depending on temperature. Higher irradiances resulted in photoinhibition. Maximal photosynthesis of the conchocelis of P. abbottiae occurred at 11°C, 60 μmol photons · m−2·s−1, and 30 psu (practical salinity units). The conchocelis of P. “pseudolinearis” and P. torta had similar Pmax values but higher Imax values than those of P. abbottiae. The Pmax of P. “pseudolinearis” conchocelis was 200–240 μmol O2 · g dwt−1 · h−1 and for P. torta was 90–240 μmol O2 · g dwt−1 · h−1. Maximal photosynthesis for P. “pseudolinearis” occurred at 7°C and 250 μmol photons · m−2 · s−1 at 30 psu, but Pmax did not change much with temperature. Maximal photosynthesis for P. torta occurred at 15°C, 200 μmol photons · m−2 · s−1, and 30 psu. Photosynthesis rates for all species declined at salinities <25 or >35 psu. Estimated compensation irradiances ( I c) were relatively low (3–5 μmol · photons · m−2 · s−1) for intertidal macrophytes. Porphyra conchocelis had lower respiration rates at 7°C than at 11°C or 15°C. All three species exhibited minimal respiration rates at salinities between 25 and 35 psu. [ABSTRACT FROM AUTHOR]

Previous studies showed that photosynthesis and morphogenesis of Porphyra plants could be affected by solar UV radiation (UVR: 280-400 nm). However, little is known about the sensitivity of their conchocelis stage to UVR. We investigated the photosynthetic performance of P. haitanensis conchocelis under natural and simulated solar radiation with or without UVR and compared its responses among different developmental stages (vegetative and sporangial phases). High solar PAR accounted for most of the reduction of the effective quantum yield of PS II. Presence of UVR further reduced the yield by 53-55% in contrast to PAR alone treatment under solar radiation (UV-A of 33.2 W m-2 and UV-B of 0.85 W m-2) or a xenon lamp (UV-A of 25.5 W m-2 and UV-B of 1.15 W m-2). CO2 fixation was more reduced by UVR in the free-living vegetative (38%) than in the sporangial conchocelis (14%). Photosynthetic tolerance of UVR increased from vegetative to sporangial phase, then to thallus stage, correlating with the increased contents of UV-absorbing compounds and/or differentiated structure. [ABSTRACT FROM AUTHOR]

The effect of plant growth substances (PGSs) on conchocelis growth of Alaskan Porphyra ( P. abbottiae V. Krishnam., P. pseudolanceolata V. Krishnam., P. pseudolinearis Ueda) was investigated. Growth was measured under different combinations of PGS concentrations (0, 0.1, 0.2, 0.4, 0.8, 1.6, and 3.2 ppm), PGS type (gibberellic acid, kinetin, and indole-3-acetic acid), temperature (7, 11, and 15°C), and photoperiod (16:8 light:dark [L:D] cycle and 8:16 L:D cycle). Plant growth substances effectively promoted the growth of Porphyra conchocelis. Depending on culture conditions, growth rates were increased relative to controls 6.9%–31.7% for P. abbottiae, 4.7%–25.7% for P. pseudolanceolata, and 8.9%–35.1% for P. pseudolinearis. Maximal growth of P. abbottiae occurred with 0.8 ppm kinetin, 15°C, and short-day conditions (8:16 L:D). Porphyra pseudolanceolata exhibited maximal growth with 0.4 ppm indole-3-acetic acid, 7°C, and long days (16:8 L:D). Indole-3-acetic acid also effected maximal growth of P. pseudolinearis at 0.4 ppm, 15°C, and long-day conditions (16:8 L:D). For P. abbottiae and P. pseudolinearis, intermediate PGS concentrations (0.4–1.6 ppm) had the greatest growth-stimulating effects, whereas for P. pseudolanceolata, higher growth generally occurred at lower concentrations (0.1–0.8 ppm). Kinetin and indole-3-acetic acid had more influence on the conchocelis phase than gibberellic acid. The PGS concentrations greater than 1.6 ppm had a diminishing effect on growth, especially in P. pseudolanceolata. For P. abbottiae and P. pseudolinearis, higher temperatures resulted in higher growth rates, in contrast to P. pseudolanceolata, which grew faster at the lower temperatures. [ABSTRACT FROM AUTHOR]

Cryopreservation of Porphyra yezoensis conchocelis was conducted with cryoprotectants and a proposed pretreatment procedure and thawing methods explored. Six cryoprotectants combined by DMSO with ethylene glycol (EG), propylene glycol (PEG), sorbitol and sucrose were developed. The effect of prefreezing at −40°C or −20°C for different time durations was compared and the thawing methods were screened. It was shown that the cryoprotectant including 10% DMSO with 0.5 molL−1 sorbitol exhibited the optimal effect. The ideal pretreatment was that conchocelis segments were stayed for 20 min at −40°C before stored in liquid nitrogen, and 40°C water bath was proper for quick thawing. The highest recovery rate of cryopreserved P. yezoensis conchocelis reached 89.41%. [ABSTRACT FROM AUTHOR]

Porphyra yezoensis and P. tenera are the representative species of the marine crop Porphyra (nori) in Japan. Since the two species are extremely similar to each other in morphology, nori breeders have tentatively classified many strains of cultivated Porphyra into the two species without strict species identification. In order to facilitate rapid and reliable identification of the many strains of Porphyra currently cultivated in various Japanese regions, 24 conchocelis strains were examined by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis using the plastid RuBisCo spacer and the nuclear internal transcribed spacer regions. From the results, all the strains were identified as P. yezoensis f. narawaensis, and P. tenera was not detected. Hence, it was confirmed that most of the Porphyra strains currently cultivated in Japan are P. yezoensis f. narawaensis, and that intensive selective breeding has led to a reduced genetic diversity in the stock used for nori cultivation. [ABSTRACT FROM AUTHOR]

Polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis of the plastid ribulose-1,5-bisphosphate carboxylase (RuBisCo) spacer region was developed for a more reliable and rapid species identification of cultivated Porphyra in combination with PCR-RFLP analysis of the nuclear internal transcribed spacer (ITS) region. From the PCR-RFLP analyses of the plastid and nuclear DNA, we examined seven strains of conchocelis that were used for cultivation as Porphyra tenera Kjellman but without strict species identification. The PCR-RFLP analyses suggested that two strains, C-32 and 90-02, were cultivated P. tenera and that the other five strains, C-24, C-28, C-29, C-30 and M-1, were Porphyra yezoensis f. narawaensis Miura. To identify species more accurately and to reveal additional genetic variation, the two strains C-32 and 90-02 were further studied by sequencing their RuBisCo spacer and ITS-1 regions. Although RuBisCo spacer sequences of the two strains were identical to each other, each of their ITS-1 sequences showed a single substitution. The sequence data again confirmed that the two strains (C-32 and 90-02) were cultivated P. tenera, and suggested that the two strains showed some genetic variation. We concluded that PCR-RFLP analysis of the plastid and nuclear DNA is a powerful tool for reliable and rapid species identification of many strains of cultivated Porphyra in Japan and for the collection of genetically variable breeding material of Porphyra. [ABSTRACT FROM AUTHOR]

In order to extract DNA rapidly from cultivated Porphyra, we extracted total DNA from conchocelis using the ISOPLANT II kit (Nippon Gene) without liquid nitrogen treatment or CsCl-gradient ultracentrifugation. By confirming the reproducibility of RAPD patterns, it is concluded that the quality of the extracted DNA is sufficient to use as a template for molecular investigation. Using this rapid method, the nuclear ribosomal DNA of the internal transcribed spacer (ITS) regions was amplified from seven strains of cultivated Porphyra, which had been maintained as free-living conchocelis by subculturing in the laboratory. From the amplified DNAs, the ITS-1 sequences were determined in order to identify the species and genetic relationship of the strains. The sequences were identical in the seven strains, and all the strains were identified as P. yezoensis. Furthermore, the gametophytic blades of these strains showed long linear or oblanceolate shapes in the laboratory culture. It was concluded that these strains are P. yezoensis form. narawaensis. This rapid DNA extraction method from conchocelis will be a powerful tool for phylogenetic analysis and for genetic improvement of cultivated Porphyra. [ABSTRACT FROM AUTHOR]

In order to maintain axenic seedstock cultures axenically of thecommercially important red seaweed, Porphyra yezoensis, aprocedure was developed for axenic isolation and culture of conchocelis andmonospores. For axenic isolation of the conchocelis, contaminated microalgaewere most effectively removed by filtering contaminated samples through a100-μm mesh after sonication. Removal of bacteria and otheralgaewas accomplished using a mixture of 5 agents (0.02% chitosan, 100 μgml−1 GeO2, 10 μgml−1 ampicillin, 40 μgml−1 kanamycin and 200 μgml−1 streptomycin). Axenic single colonies wereisolatedfrom a semi-solid medium prepared from 1% transfer gel. After collectingmonospores from the 40–50% density layer on a percoll-gradient, removalofbacteria and fungi from the monospores was accomplished using a mixture of 5antibiotics (3.5 μg ml−1 nystatin, 2 mgml−1 ampicillin, 400 μgml−1 kanamycin, 50 μgml−1 neomycin and 800 μgml−1 streptomycin). Axenic single juvenile blades wereisolated from a semi-solid medium prepared from 0.5% transfer gel. [ABSTRACT FROM AUTHOR]

Since 1992, as part of a study to circumscribe the genus Porphyra in New Zealand, an extensive culture programme has been developed at the Museum of New Zealand Te Papa Tongarewa. This collection currently houses more than 800 cultures and 150strains. We currently recognise at least 20 species in New Zealand, most of which are undescribed. Close observation of reproduction and the development of conchocelis-phase filaments grown in the laboratory, under controlled conditions of temperature, irradiance and photoperiod, has enabled the recognition of characters that can assist in species separation. The comparative taxonomic value of a range of such characters is discussed, including reporting a novel reproductive mode. [ABSTRACT FROM AUTHOR]

The conchocelis cells of four strains of Porphyra yezoensis Udea and four Porphyra species were cryopreserved in liquid mitrogen (LN) using a programmable freezer or a simple prefreezing system, which consisted of a Styrofoam box and deep-freezer at -40°C. The cells differed in their freezing tolerance but srevived maximally when prefrozen to -40°C in a cryoprotective solution composed of 10% dimethylsulfoxide and 0.5M sorbitol in 50% seawater. The cryopreservation was successfully performed by applying the simple prefreezing system as well as by a programmable freezer. Conchocelis cells thawed from the LN temperature formed colonies and retained the ability to form conchospores that grew into gametophytic thalli. This technique using a simple prefreezing system will accelerate the spread of Porphyra cryopreservation. [ABSTRACT FROM AUTHOR]

Studies the karyology and effects of temperature and photoperiod on the life- cycle of Porphyra leucosticta. Evaluation of the results of culture investigations; Examination of the microscopic filamentous conchocelis phase; Observation of the three chromosomes.

We have determined the conditions which give optimal growth and conchospore release in laboratory cultures of free conchocelis of the red alga Porphyra torta Krishnamurthy. With cool white fluorescent light on a 16L:8D photoregime, the fastest sustained growth (5% volume increase d[SUP-1]) was observed from 10-15°C and 25-100 μm[SUP-2] s[SUP-1] slightly faster growth was obserted at 15°C and 300 μEm[SUP-2]s[SUP-1] but such conditions are close to lethal. Conehosporangia will form under a wide range of conditions in conchocelis of this species. However, conchospores will mature and release only when the cultures are exposed to a short day photoperiod. The critical photoperiod is just shorter than 12 h. The minimum number of photoinductive cycles for complete conchospore release is four for a range of conditions but can be just one de-pending on pretreatment. [ABSTRACT FROM AUTHOR]

The fine structure of released, attached, and germinating carpospores of Porphyra variegata (Kjellm.) Hus is described. Adhesive vesicles, formed during sporogenesis and discharged upon settling of the spore, produced a layer of adhesive mucilage around the spore and filled a deep invagination on the spores ventral side. The mucilage layer was punctured by the emergence of a germ tube. Both spore and germ tube were lined by newly deposited cell wall. Germination was accompanied by vacuolation and starch mobilization. The morphological development of the sporeling was not noticeably influenced by the great variability of the timing, location, and orientation of septum formation. The attached carpospore possessed a plastid like that of gamatophyte cells: stellate with one large central pyrenoid and no peripheral encircling thylakoids. Cells of mature vegetative cells of the conchocelis had plastids that were elongate and parietal and had multiple pyrenoids and encircling thylakoids. Most stages in the transition between the two forms of plastids occurred during carpospore germination. [ABSTRACT FROM AUTHOR]

Purified cell walls were prepared from both the conchocelis and thallus phases of Porphyra tenera (Kjellm). The nitrogen content of cell walls from the conchocelis was significantly greater that that for the thallus cell walls, being 3.35 ± 0.26% and 2.39 ± 0.03%, respectively. Amino acid analysis revealed important differences. The conchocelis cell wall hydrolyzates were richer in aspartic acid, glutamic acid, methionine, and basic amino acids. The thallus cell wall hydrolyzates, however, contained much more glycine and alanine than did those of the conchocelis. Hydroxyproline was not detected in cell walls of either phase. The neutral sugar content of cell wall hydrolyzates from the thallus was more than double that from the conchocelis being 83.6% and 34.5?%, respectively. The former contained predominantly mannose which accounted for 72.2% of the neutral sugars while the latter was principally galactose (49.9%) and glucose (36.4%). Methylation analysis confirmed the presence of cellulose microfibrils in the conchocelis in contrast to xylan microfibrils in the conchocelis in contrast to xylan microfibrils in the thallus. The result establish that the conchocelis and thallus phases of P. tenera differ markedly in the structure and composition of the cell walls. [ABSTRACT FROM AUTHOR]