National Committee on Marine Sciences (NCMS)
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- Microscopic stages of North Atlantic Laminaria digitata (Phaeophyceae) exhibit trait-dependent thermal adaptation along latitudesSchimpf, Nele M.; Liesner, Daniel; Franke, Kiara; Roleda, Michael Y.; Bartsch, Inka (Frontiers Media SA, 2022-06-17)Kelp forests in the North Atlantic are at risk of decline at their warm temperature distribution margins due to anthropogenic temperature rise and more frequent marine heat waves. To investigate the thermal adaptation of the cold-temperate kelp Laminaria digitata, we sampled six populations, from the Arctic to Brittany (Spitsbergen, Tromsø, Bodø [all Norway], Helgoland [Germany], Roscoff and Quiberon [both France]), across the species’ entire distribution range, spanning 31.5° latitude and 12-13°C difference in mean summer sea surface temperature. We used pooled vegetative gametophytes derived from several sporophytes to approximate the genetic diversity of each location. Gametophytes were exposed to (sub-) lethal high (20-25°C) and (sub-) optimal low (0-15°C) temperature gradients in two full-factorial, common-garden experiments, subjecting subsets of populations from different origins to the same conditions. We assessed survival of gametophytes, their ability to develop microscopic sporophytes, and subsequent growth. We hypothesized that the thermal performance of gametophytes and microscopic sporophytes corresponds to their local long-term thermal history. Integrated gametophyte survival revealed a uniform upper survival temperature (UST) of 24°C among five tested populations (Tromsø to Quiberon). In contrast, following two weeks of thermal priming of gametophytes at 20-22°C, sporophyte formation at 15°C was significantly higher in southern populations (Quiberon and Roscoff) compared to the high-latitude population of Tromsø. Between 0-15°C, survival of the Arctic population (Spitsbergen) was negatively correlated with increasing temperatures, while the southern-most population (Quiberon) showed the opposite. Thus, responses of survival at low, and sporophyte formation at high temperatures, support the concept of local adaption. On the other hand, sporophyte formation between 0-15°C peaked at 6-9°C in the Quiberon and at 9-12°C in the Spitsbergen population. Sporophyte growth rates (GR) both in length and width were similar for Spitsbergen, Tromsø and Quiberon; all had maximum GRs at 12-15°C and low GRs at 0-6°C. Therefore, responses of sporophyte formation and growth at low temperatures do not reflect ecotypic adaptation. We conclude that L. digitata populations display trait-dependent adaptation, partly corresponding to their local temperature histories and partly manifesting uniform or unpredictable responses. This suggests differential selection pressures on the ontogenetic development of kelps such as L. digitata.We would like to thank A. Wagner for the sampling and clonal isolation of kelp material and technical assistance in the laboratory, C. Daniel for support with the image analysis, L. Foqueau for the SST data, C. Gauci for statistical advice and S. DeAmicis for supervision in this BSc Thesis.
- Expressed sequence tags (ESTs) from the marine red alga Gracilaria gracilisLluisma, Arturo O.; Ragan, Mark A. (Springer, 1997-06)Expressed sequence tags (ESTs) are partial sequences of cDNAs, and can be used to characterize gene expression in organisms or tissues. We have constructed a 200-sequence EST database from vegetative thalli of Gracilaria gracilis, the first ESTs reported from any alga. This database contains recognizable ESTs corresponding to genes of carbohydrate metabolism (seven), amino acid metabolism (three), photosynthesis (five), nucleic acid synthesis, repair and processing (three), protein synthesis (14), protein degradation (six), cellular maintenance and stress response (three), other identifiable protein-coding genes (13) and 146 sequences for which significant matches were not found in existing sequence databases. We have already used this EST database to recover genes of carbohydrate biosynthesis from G. gracilis.
- Seasonal variations in the yield, gelling properties, and chemical composition of agars from Gracilaria eucheumoides and Gelidiella acerosa (Rhodophyta) from the PhilippinesVillanueva, R. D.; Montaño, N. E.; Romero, J. B.; Aliganga, A. K. A.; Enriquez, E. P. (Walter de Gruyter GmbH, 1999-01-01)The yield, physical, and chemical properties of agars from two Philippine red seaweeds, Gracilaria eucheumoides and Gelidiella acerosa, were investigated on a bimonthly basis. The yield of agar from Gracilaria eucheumoides was at a maximum during the early rainy season (May, 29%) and at a minimum during the summer month of March (20%). In Gelidiella acerosa, a peak in agar yield was also recorded in May (21%), with generally higher yields recorded during the rainy than in the dry season. Agar gel strengths fluctuated from 225 to 430 g cm−2 and from 160 to 820 g cm−2 for Gracilaria eucheumoides and Gelidiella acerosa, respectively, and both agars exhibited strongest gels in July. Significant seasonal variations were observed in the gelling and melting temperatures of agar from Gracilaria eucheumoides, but not from Gelidiella acerosa. Sulphate content only varied slightly in agar samples from Gracilaria eucheumoides, while a higher sulphate content was found in Gelidiella acerosa agar during the dry season. Moreover, the sulphate content in G. acerosa agar fluctuated inversely with the 3,6-anhydrogalactose content. A FT-IR analysis showed a fairly constant spectrum for temporal Gracilaria eucheumoides agar while peaks attributed to S–O vibrations intensified in Gelidiella acerosa samples which were recorded to contain high sulphate residues and possess low gel strengths. Diagnosis of the FT-IR spectra in the 1000–400 cm−1 frequency range was also conducted in comparison with agarose and Gracilaria chilensis agar.
- Highly methylated agar from Gracilaria edulis (Gracilariales, Rhodophyta)Villanueva, Ronald; Montaño, Nemesio (Springer, 1999-04)The structure and gelling properties of alkali-modified agar from Gracilaria edulis were investigated. 1H and 13C NMR experiments revealed a basic repeating unit of alternating 3-linked 6- O-methyl-β-D-galactopyranose and 4-linked 3,6-anhydro-α-L-galactopyranose. Partial methylation at O-2 of the anhydrogalactose moiety was also revealed. Meanwhile, the O-4 of the methylated galactose residue was detected to exhibit partial sulfation by NMR and FT-IR spectroscopy. The gel strength and syneresis index of the extracted agar were considerably enhanced by the addition of sodium, potassium, and calcium ions. The ion-driven gelation and peculiar sulfate position conferred the agar's similarity to κ-carrageenan.
- Occurrence of closely spaced genes in the nuclear genome of the agarophyte Gracilaria gracilisLluisma, Arturo O.; Ragan, Mark A. (Springer, 1999)Little is known about the structure and organisation of nuclear genomes in red algae. In particular, it is not known whether genes are densely or loosely packed, whether gene order is conserved, whether their genes tend to occur in one or multiple copies and whether their nuclear genes tend to be compact or interrupted by numerous introns. Sequencing of cloned genomic DNA from Gracilaria gracilis has begun to provide provisional answers to some of these questions. Four pairs of closely spaced genes have been found in G. gracilis upon sequencing genomic clones that contain genes for UDPglucose pyrophosphorylase, galactose-1-phosphate uridylyltransferase, the β subunit of tryptophan synthetase, and methionine sulphoxide reductase (a fifth pair of closely spaced genes, encoding polyubiquitin and aconitase, was reported earlier). An open reading frame with significant similarity to another known gene occurs close (< 1.7 kbp) to each of these genes. In two pairs the intergenic region is less than 400 bp in length, and for these the location of the putative polyadenylation signals indicates that the gene transcripts, encoded on opposite strands, have overlapping (hence complementary) 3′ regions. These somewhat unexpected findings begin to establish a basis for genome-level characterisation of red algae.
- Enrichment of the protein content of the macroalgae Saccharina latissima and Palmaria palmataAasen, Inga Marie; Sandbakken, Ingrid S.; Toldnes, Bendik; Roleda, Michael Y.; Slizyte, Rasa (Elsevier, 2022-06)The large brown seaweeds (kelps) are potential sources of protein for animal feed. They have lower protein contents than most red and green algae, but due to potential for large-scale production, they may represent a significant future protein source. The impact of pH, temperature and polysaccharide-degrading enzymes on the solubility and extraction yields of protein from wet Saccharina latissima biomass was investigated. The protein solubility increased with increasing pH and reached maximum of 23% at pH 11, determined as total amino acids (TAA). The enzyme treatments increased the release of soluble compounds by 30–35%. The highest protein yield obtained was 19%, using a ratio of water to wet seaweed of 1:1 for extraction. Even if the yields can be increased by increasing the water amounts used for extraction, the majority of the protein would remain in the insoluble residue after separation. The strategy for production of a larger quantity of protein-enriched biomass was therefore to maintain the insoluble fraction as the product. A pilot scale production was carried out, also including the red algae Palmaria palmata. In total 750 kg S. latissima and 195 kg P. palmata were processed. The protein content in the product increased from 10 to 20% of dry weight (dw) for S. latissima and from 12 to 28% for P. palmata, with yields of 79 and 69%, respectively. The ash content was reduced from 44 to 26% and from 12 to 5% of dw, respectively, for the two species. The main protein loss was free amino acids, which constituted approximately 10% of TAA in the feedstocks. Less essential than non-essential amino acids were lost, thus, the essential amino acids were enriched in the product.The work was funded by The Research Council of Norway, grant no. 244244.
- Marine macroalgal reference culture collection at the University of the Philippines Marine Science Institute (UP-MMARCC): Status and prospects for advancing Philippine phycologySantiañez, Wilfred John E.; Guerta, Christian Ace T.; Lastimoso, John Michael L. (Assocation of Systematic Biologists in the Philippines, 2022-11-16)Seaweeds research in the Philippines-from studies on their diversity, natural products chemistry, and the utilization of their derivatives-is largely based on spot collections of large and conspicuous components of the seaweed flora found along the coasts. Such efforts are often focused on commercially important seaweeds; thus, most of the smaller and even microscopic seaweeds remain understudied, if not completely overlooked. Consequently, little to none is known on many aspects of the biology, ecology, and even biochemistry of these components of the Philippine seaweed flora. To understand aspects of seaweed biology and serve as a facility for preserving the genetic resources of Philippine seaweeds, we established the Marine Macroalgal Reference Culture Collection at the University of the Philippines Marine Science Institute (UP-MMARCC). We are currently maintaining 446 seaweed strains (or isolates) collected from several coastal and offshore areas in the Philippines, the latter including the Kalayaan Island Group in the West Philippine Sea, and 25 isolates from Okinawa, Japan. To our knowledge, the UP-MMARCC is the most diverse and widely sampled culture collection in the Philippines so far. Moreover, our preliminary molecular-assisted biodiversity studies suggest that UP-MMARCC houses several isolates that are either new records to the Philippines or putative new taxa. We anticipate that with continued support, we will be able to sustain and expand our culture collection, not only to facilitate discoveries but also to cater to the needs of the Philippine seaweed industry and in support of its call for diversifying our seaweed commodities and their products.
- Reproductive phenology and morphology of Macrocystis pyrifera (Laminariales, Ochrophyta) from southern New Zealand in relation to wave exposure1Leal, Pablo P.; Roleda, Michael Y.; Fernández, Pamela A.; Nitschke, Udo; Hurd, Catriona L. (Wiley, 2021-07-23)Macrocystis pyrifera is a major habitat forming kelp in coastal ecosystems of temperate regions of the northern and southern hemispheres. We investigated the seasonal occurrence of adult sporophytes, morphological characteristics, and reproductive phenology at two sites within a wave-protected harbour and two wave-exposed sites in southern New Zealand every 3–4 months between 2012 and 2013. Seasonality in reproduction was assessed via the number of sporophylls, the occurrence of sori on sporophylls, and non-sporophyllous laminae (fertile pneumatocyst-bearing blades and fertile apical scimitars), meiospore release, and germination. We found that M. pyrifera was present and reproductive year-round in three of the four sites, and patterns were similar for the wave-exposure conditions. Sori were found on pneumatocyst-bearing blades and apical scimitars in addition to the sporophylls, and viable meiospores were released from all three types of laminae. Morphological variations between sites with different wave exposure indicate that sporophytes from wave-protected sites have bigger blades and holdfasts and are longer than those from wave-exposed sites. We discuss the implications of these biological variables for the ecology of M. pyrifera inhabiting different wave exposure environments in southern New Zealand.Pablo P. Leal was supported by a scholarship from BECAS CHILE-ANID and by Programa Integral de Desarrollo de Acuicultura de Algas para Pescadores Artesanales (Etapa 4), funded by the Subsecretarıa de Economıa y Empresas de Menor Tamano (Convenio 2016). Michael Y. Roleda acknowledges the Philippine’s Department of Science and Technology (DOST) Balik Scientist Program for the fellowship. Udo Nitschke gratefully acknowledges support by Skidmore College, 815 North Broadway, Saratoga Springs, NY 12866, USA. Pamela A. Fernandez was supported by the Chilean National Commission for Scientific and Technological Research (ANID/FONDECYT; Postdoctoral grant 3170225 and grant 1180647) and ANID/Programa Basal (CeBiB, FB-0001). We are grateful to Rocio Suarez for assisting in field sampling.
- Cloning and characterization of a nuclear gene encoding a starch-branching enzyme from the marine red alga Gracilaria gracilisLluisma, A. O.; Ragan, M. A. (Springer, 1998-08-27)The biosynthesis of starch in red algae occurs in the cytosol, in contrast to green plants where it takes place in the plastid. We have cloned a nuclear gene from the red alga Gracilaria gracilis that encodes a homolog of starch-branching enzymes (SBEs); this gene, which is apparently intron-free, was designated as GgSBE1. A potential TATA box, CAAT boxes, and other potential regulatory elements were observed in its 5′ flanking region. The encoded 766-aa peptide shares significant sequence similarity with SBEs from green plants (at least 40%), and with glycogen-branching enzymes (GBEs) from human (46%) and Saccharomyces cerevisiae (45%). Southern-hybridization analysis indicates that the gene is single-copy, although weaker signals suggest that related genes exist in the genome of G. gracilis. Phylogenetic analyses indicate that GgSBE1 groups within the eukaryote branching enzymes (BEs) and not with eubacterial GBEs, suggesting that its gene has not been derived directly from an endosymbiotic cyanobacterium, but instead is ancestrally eukaryotic.
- Chemical characteristics and gelling properties of agar from two Philippine Gracilaria spp. (Gracilariales, Rhodophyta)Montaño, Nemesio E.; Villanueva, Ronald D.; Romero, Jumelita B. (Springer, 1999)The chemical structure of agars extracted from Philippine Gracilaria arcuata and G. tenuistipitata were determined by NMR and infrared spectroscopy. Agar with alternating 3-linked 6-O-methyl-β-D-galactopyranosyl and 4-linked 3,6-anhydro-2- O-methyl-α-L-galactopyranosyl units was isolated from G. arcuata, while the agar from G. tenuistipitata possesses the regular agarobiose repeating unit with partial methylation at the 6-position of the D-galactosyl residues. Both agars exhibit sulphate substitution at varying positions in the polymer. Chemical analyses reveal higher 3,6-anhydrogalactose and lower sulphate contents in alkali-modified than in native agar from both samples. Also, alkali modification enhanced agar gel strength and syneresis. Native G. arcuata agar produces a viscous solution (2000 cP at 75 °C) with a high gelling point (>60 °C) that forms a soft gel even after alkali modification (gel strength: <300 g cm−2). On the other hand, the agar from G. tenuistipitata exhibits gel qualities typical of most Gracilaria agars.