Porphyra Perforata Research Articles

Dietary selectivity in the field and food preferences in the laboratory for two herbivorous fishes (Cebidichthys violaceus and Xiphister mucosus) from a temperate intertidal zone

Diets and food selectivity of two stichaeid fishes (Cebidichthys violaceus and Xiphister mucosus) from the rocky intertidal zone of the central California coast (USA) were studied at each season of the year by gut content analysis and abundance measurements of potential macrophyte food items. Both fishes, after reaching a standard length of about 44 mm, were almost exclusively herbivorous. The bulk of the diet consisted of 8 to 10 species of chlorophytes and rhodophytes. These main dietary components were chiefly annual seaweeds with high surfaceto-weight ratios (sheetlike forms or small, highly branched forms). Perennial seaweeds were eaten in relatively large amounts only during the winter. Macrophytes eaten in only trace amounts included about 20 species of chlorophytes, chrysophytes, phaeophytes, rhodophytes and a spermatophyte. The small amount of animal material in the diet (never more than 2% by weight) could well have been ingested incidentally while the fishes were feeding on seaweeds. Food preference tests with up to 19 macrophyte species in the laboratory revealed that both fishes chose to eat three annual rhodophytes (Smithora naiadum, Porphyra perforata and Microcladia coulteri) in preference to Ulva lobata, an annual chlorophyte that was more abundant in the diets of field-caught specimens.

Population and species diversity fluctuations in a rocky intertidal community relative to severe aerial exposure and sediment burial

From a series of 10 quarterly assessment between October 1975 and May 1978 (inclusive), fluctuations in abundance were determined for macroinvertebrates and macrophytes of a rocky intertidal community on Santa Cruz Island, California, USA. During afternoon low tides in late fall and winter of the first 2 yr of study, organisms of the upper and middle intertidal zones were subjected to prolonged aerial exposure. Many species there tolerated this exposure, but die-backs occurred for a barnacle (Chthamalus fissus/C. dalli) and several algae (Endocladia muricata, Pelvetia fastigiata f. gracilis, Corallina officinalis var. chilensis, Corallina vancouveriensis, Cylindrocarpus rugosus and Codium fragile). These die-backs were succeeded by blooms of Ulva californica and Porphyra perforata. In the upper and middle intertidal zones, the major cover organisms that could tolerate prolonged aerial exposure were disproportionately prevalent and appeared to be maintained by the periodic repression of species intolerant to such exposure. In February 1978, heavy rainfall caused sediment inundation of the middle and lower intertidal zones. This event was followed by declines in abundance of a barnacle (Tetraclita rubescens) and several algae (Pelvetia fastigiata f. gracilis and corallina spp.). Shannon-Wiener H′ species diversity fluctuated from a high in October to a low the following May during both 1975–1976 and 1976–1977 in conjunction with the period of increased daytime aerial exposure in late fall and winter. A further decline in diversity following sediment inundation in February 1978 contributed to a long-term trend of declining H′ species diversity (3.06 in October 1975 to 1.87 in May 1978). We hypothesize that predictable late fall to winter aerial exposure stresses, in combination with a random physical disturbance (sediment burial), exceeded an “optimal” intermediate level of disturbance predicted for maximal species diversity.

The Effects of Desiccation on Excitation Energy Transfer at Physiological Temperatures Between the Two Photosystems of the Red Alga Porphyra perforata

Summary Room temperature fluorescence emission and excitation spectra were measured for wet and desiccated thalli of the red alga Porphyra perforata. Porphyra that had been desiccated in the dark showed a reduced efficiency of photosystem II trap closure along with a decrease of the photosystem II fluorescence emission at 687 nm and a concomitant increase of the far red photosystem I fluorescence emission band. Porphyra responds to desiccation by producing a strong increase in the distribution of excitation energy from phycoerythrin of photosystem II to photosystem I that may be mediated by increases in α, the fraction of light that is transferred initially to photosystem I, and increases in spillover or both. No photosystem II trap closure was seen at room temperature in Porphyra that had been dried in strong light, indicating that the photosystem II traps were closed under these conditions. Light dried Porphyra showed a complete loss of the 687 nm fluorescence band compared to dark dried Porphyra . This loss of the 687 nm band was accompanied by a proportionate loss of the 737 nm band. In light dried Porphyra F o is not affected, only part of F v was eliminated. This observation suggests that reaction center quenching of fluorescence in photosystem II may account for these observations. Increased energy transfer to photosystem I in the desiccated state may protect the more photolabile reaction centers of photosystem II from photochemical damage when these plants are subjected to desiccation and high light intensities.

A Comparative Study of a Cyclic AMP-Like Compound Isolated from Higher Plants and Adenosine 3′,5′-Pyrophosphate Found in the Red Alga Porphyra perforata

Adenosine 3′,5′-pyrophosphate, previously isolated from the red alga Porphyra perforata, possesses biological properties similar to those of a cyclic AMP-like compound isolated from higher plants. Both compounds are potent inhibitors of bovine cyclic AMP-dependent protein kinase and bovine phosphodiesterase.

Photoassimilatory Products and Osmoregulation in Marine Rhodophyceae

Summary A variety of intertidal and subtidal marine representatives of the Rhodophyceae including Porphyra perforata, Porphyra umbilicalis, Chondrus crispus, Iridaea flaccida, Dumontia incrassata, Rhodymenia palmata and some other species have been investigated with special regard to their synthesis of accumulated photoassimilatory products in relation to the osmotic value (salt content) of the incubation medium. Percentages of 14 C-Iabelling of floridoside (2-O-D-glycerol- a -D-galactopyranose) as well as of digeneaside (1-O-D-glycerate- a -D-mannopyranose) show that biosynthesis of these heterosides during photosynthetic carbon assimilation is not affected by osmotic stress over a wide salinity range. Further evidence from pulse-chase experiments and quantitative determinations suggests that in marine Rhodophyceae osmotic regulation is not achieved on the level of soluble carbohydrates involving floridoside or related compounds.

Colonization of Porphyra Perforata Thallus Discs by Pythium Marinum, A Marine Facultative Parasite

SummaryLaboratory infections of Porphyra perforata thallus discs with zoospores of Pythium marinum showed that the colonization rate is markedly influenced by temperature, salinity, and the reproductive stage of the algal discs. The most rapid colonization rate occurred on discs obtained from reproductive areas of the alga, or areas immediately adjacent to these, when the discs were in diluted seawater with a salinity of 24%. and at 20 C. All species of Porphyra examined were capable of being infected in the laboratory as was Porphyrella gardneri.

Colonization of Porphyra perforata Thallus Discs by Pythium marinum, a Marine Facultative Parasite

SummaryLaboratory infections of Porphyra perforata thallus discs with zoospores of Pythium marinum showed that the colonization rate is markedly influenced by temperature, salinity, and the reprodu...

An examination of the original specimens of Porphyra perforata J. Ag. (Rhodophyceae, Bangialas)

Abstract In describing Porphyra perforata, a widely distributed species along the Pacific coast of North America, J.G. Agardh (1883) did not designate a type but supported his description by reference to specimens presently housed in the Agardh Herbarium at Lund, Sweden. Detailed examination shows that they comprise a number of species that can now be separated. A lectotype (LD 13037) and at least two syntypes (LD 13031 and LD 13048) which appear to be the basis of the original description are readily distinguished

Comparative Photosynthetic Capacities of Intertidal Algae under Exposed and Submerged Conditions

Photosynthetic rates were measured for five species of intertidal marine algae, in the air and submerged. Ulva expansa and Prionitis lanceolata from the lower intertidal show reduced photosynthetic capacity air in air compared to submergedrates. In contrast, species from the middle and upper littoral (Iridaea flaccida, Porphyra perforata, Fucus distichus, and Endocladia muricata) reach maximum photosynthesis after some degree of drying. For these latter species, photosynthetic rates can be 1.6 to 6.6 times greater in air than in water at the same illumination and temperature. Desiccation rates under natural conditions are slow enough that these algae are capable of continuing a high rate of photosynthetic activity for extended periods while exposed and may fix the bulk of their carbon at this time. The capacity of these algae for sustained photosynthesis in air vary according to their intertidal zonation. It is suggested that these relationships may be partially responsible for the vertical distribution of intertidal marine algae.

PHOTOSYNTHETIC ENERGY TRANSFER REVERSIBLY INHIBITED BY HYDROSTATIC PRESSURE*

Abstract— Hydrostatic pressure is found to affect reversibly the emission spectra of Porphyra perforata. At 1200atm phycoerythrin and phycocyanin fluorescence show a remarkable increase, whereas at the same time chlorophyll a (Chl a) fluorescence decreases. Upon release of pressure the fluorescence intensities of the individual pigments return to their original levels. This effect indicates that hydrostatic pressure acts as a unique reversible inhibitor of energy transfer between phycobilins and Chi a in the chloroplast.The effects of pressure and its release are relatively slow (minutes). It is suggested that pressure changes thylakoid membrane structure sufficiently to alter the critical distance between the phycobilisomes and Chl a, thus blocking the inductive resonance transfer of excitation energy.

Ultrastructure of Porphyra perforata infected with Pythium marinum, a marine fungus

A marine species of Pythium, P. marinum Sparrow, was isolated from lesions occurring on Porphyra miniata collected at the north end of the Cape Cod Canal. Zoospores obtained from the isolates were used to infect Porphyra perforata artificially. The fine structure of the host–parasite interaction indicates that during penetration, the fungus modifies the host cell boundary very little while the fungal hypha itself apparently is also not modified during the penetration process. No sheath membrane or sheath was observed surrounding the hyphae. The dissolution of starch grains and finally the disintegration of nearly the entire algal cell culminated the infection process.

On the ultrastructure of pit connections in the conchocelis phase of the red alga Porphyra perforata J. Ag

Ultrastructural observations of the conchocelis phase of Porphyra perforata J. Ag. (Bangiophycidae) confirm the presence of pit connections in the transverse walls of the cells of the filaments. These are similar to the pit connections already reported in the Florideophycidae.

THE CONCHOCELIS PHASE OF THREE SPECIES OF PORPHYRA IN CULTURE.

The Conchocelis phases of Porphyra perforata f. patens, P. cuneiformis and P. nereocystis were cultured from spores in a sterile artificial medium at 12 C and with 25 ft-c illumination for 10 hr daily. The cultures showed differences in duration of the vegetative phase, sporulation, liberation of spores, and the return to the leafy phase. Morphological differences were also noticed. Since the 3 species were grown under identical conditions, it is inferred that these characteristics are probably different for the 3 species studied.

LIGHT‐INDUCED SHIFTS IN THE ABSORPTION SPECTRUM OF CAROTENOIDS IN RED AND BROWN ALGAE

Abstract— Changes in light absorption in the region 450–540 nm were observed upon illumination of the red algae Iridaea splendens, Schizymenia pacifica and Porphyra perforata and the brown alga Pheostrophion irregulare. The difference spectra of these changes in Iridaea and Schizymenia showed maxima and minima at about 465, 480, 495, 515 nm. The spectra were similar to difference spectra earlier observed in photosynthetic bacteria, and the location of the maxima and minima suggested a shift towards longer wavelength of a compound with absorption maxima at about 440, 470, and 500 nm, probably a carotenoid. Similar, but more distorted difference spectra were observed in the other algae. Time courses and size of the signals induced by light of different wavelengths suggest that excitation of both photosynthetic pigment systems causes a shift in carotenoid absorption, with kinetics which appear to be similar to those of the well‐known change at 515 nm in green plants.

Quenching of chlorophyll fluorescence by quinones in algae and chloroplasts

1. A number of quinones and substituted quinones quenched strongly chlorophyll fluorescence in Swiss chard chloroplasts and in the intact algae, Ulva lobata and Porphyra perforata. Quenching occurred in the absence as well as in the presence of 3(3,4-dichlorophenyl)-1,1-dimethylurea. 2. Among the quinones found to have a high quenching activity were 2,3,5,6-tetramethylbenzoquinone, 2-methyl-1,4-naphthoquinone, 5-hydroxy-1,4-naphthoquinone, phenanthrenequinone, and 1,2-dihydroxyanthraquinone. Reduced quinones had no or little quenching activity. 3. The quinones tested quenched less strongly the initial fluorescence, observed immediately upon illumination, than the subsequent rise of fluorescence yield during illumination. For the most active compounds, the concentrations needed for 50% quenching of the initial and the subsequent increase of fluorescence were about 70 and 15 μM, respectively. 4. The kinetics of fluorescence quenching at different light intensities and concentrations of quencher and absence of stimulation of O 2 evolution indicate that the quenchers do not stimulate photosynthetic electron transport but interact directly with chlorophyll molecules of photosystem 2 by formation of traps for the excitation energy. 5. In agreement with the assumption that the site of action of the quinones is near system 2, a number of these compounds inhibited light-induced cytochrome reduction in Porphyra in vivo. However, for most compounds no quantitative relation was found between the extent of inhibition of cytochrome reduction or of the Hill reaction in chloroplasts and the activity in quenching chlorophyll fluorescence.

Carbohydrates and nucleotides in the red alga Porphyra perforata. II. Separation and identification of nucleotides.

Carbohydrates and nucleotides in the red alga Porphyra perforata. II. Separation and identification of nucleotides.

Carbohydrates and nucleotides in the red alga Porphyra perforata. I. Isolation and identification of carbohydrates.

Carbohydrates and nucleotides in the red alga Porphyra perforata. I. Isolation and identification of carbohydrates.

CATION REGULATION AND SURVIVAL OF THE RED ALGA, PORPHYRA PERFORATA, IN DILUTED AND CONCENTRATED SEA WATER

1. Over a wide range of salinity (10 to 200 per cent sea water) cells of Porphyra perforata accumulate K and partially exclude Na. Apparent osmotic volume is nearly constant between 50 and 100 per cent sea water. This imperfect volume control is thought to be due to differential shrinking and swelling of structural polysaccharides and not to active water secretion. 2. Survival of Porphyra in diluted and concentrated sea water is discussed with respect to ion transport. Rain is potentially a more serious threat to survival, due in part to breakdown of ion transport, than is concentration of sea water. Calcium seems especially important in maintaining membrane selectivity toward K and Na.

Potassium accumulation and sodium efflux by Porphyra perforata tissues in lithium and magnesium sea water.

Cells of Porphyra perforata, a red marine alga, accumulate K in the absence of concomitant Na or Li extrusion while immersed in Li- or Mg-sea waters lacking Na. This suggests that the coupling observed between K and Na transport is facultative. No evidence is obtained for net extrusion of Li. Na efflux, with the concentration gradient, is facilitated by K and is proportional to the cellular Na content. Either Na efflux does not involve an ion carrier or the number of Na sites is large. Because K accumulation has been observed in the absence of Na extrusion, but not vice versa, it seems that K uptake is the primary secretory event, with Na extrusion a secondary process dependent upon K accumulation.

POTASSIUM-DEPENDENT SODIUM EXTRUSION BY CELLS OF PORPHYRA PERFORATA, A RED MARINE ALGA

Potassium-free artificial sea water causes a loss of cell potassium and a gain of cell sodium in Porphyra perforata, which is not attributable to an inhibition of respiration. On adding KCl or RbCl to such low potassium, high sodium tissues, net accumulation of potassium or rubidium takes place, accompanied by net extrusion of sodium. Rates of potassium or rubidium accumulation and sodium extrusion are proportional to the amount of KCl or RbCl added only at low concentrations. Saturation of rates is evident at KCl or RbCl concentrations above 20-30 mM, suggesting the role of an ion carrier mechanism of transport. Evidence for and against mutually dependent sodium extrusion and potassium or rubidium accumulation is discussed.