Mastocarpus Stellatus Research Articles

Pharmacologically-Active Amines in Some Marine Algae and Algal Food Products

Pharmacologically-active amines such as histamine and hordenine are of limited occurrence in European marine algae. However, hey are present in high levels in some algae used as a source of gelling agents. Histamine occurs at 600 Lo 2500 pg/g dry weight in Furcellaria lumbricalis which is the source of furcellaran. Hordenine occurs at 1000 to 5500 pg/g dry weight in Mastocarpus stellatus, which together with Chondrus crispus is the source of carrageenan. These latter two algae are also used to produce the algal food product Carrageen. However the traditional practice of bleaching Carrageen in the open reduces its hordenine content to a level which is unlikely to be hazardous in humans.

Thick vs. thin: thallus morphology and tissue mechanics influence differential drag and dislodgement of two co-dominant seaweeds

The lower rocky intertidal zone of many moderately exposed and exposed shores in the Gulf of Maine, USA, is co-dominated by two species of red macroalgae, Chondrus crispus Stackhouse and Mastocarpus stellatus (Stack. in With.) Guiry. These species are anatomically, morphologically, ecologically and phylogenetically similar. We quantified: 1. (1) mechanical properties of the stipe; and 2. (2) flow forces on the stipe relative to thallus area and biomass of these species, to determine mechanical and morphological characteristics that could explain the greater winter dislodgement of C. crispus thalli in mixed stands. Although stipes of both species broke at the same mean force, C. crispus stipes were relatively thick, weak and extensible compared to the relatively thin, strong and stiff stipes of M. stellatus. Risk of breakage increased with size in both species because: 1. (1) their stipes weakened with increasing cross-sectional area; and 2. (2) cross-sectional area of the stipe failed to increase in linear proportion to frond area. Drag on C. crispus thalli of > 3 g fresh weight was greater than on M. stellatus of the same biomass, whereas drag on smaller fronds ( < 3 g fresh weight) of the two species was similar. Drag on large C. crispus thalli was greater mainly because they exhibit greater surface area for a given biomass than do large M. stellatus. Dislodgement by hydrodynamic forces has more severe ecological consequences for M. stellatus because regeneration from holdfasts is slower than in C. crispus. A reduced surface area:biomass ratio coupled with greater strength may lessen wave-induced disturbance and be important to maintaining a high abundance of M. stellatus in the low intertidal zone of wave-swept shores.

Marine plant harvest in Portugal

This work brings together the scattered information on marine plant harvests and the colloid extraction industry in Portugal, as an initial contribution to the improvement of resource management. The first phase of exploitation of marine plant resources started prior to the 14th century, with the gathering and sale of storm-tossed seaweeds for fertilizer. The harvest of seagrasses and algae at Ria de Aveiro was of great economic importance. The second phase of resource exploitation began with the wider scale harvest of agarophyte species for colloid extraction. Portugal is at present the third largest harvester of the agarophytes Gelidium and Pterocladia (2500 t annually), and it is the fifth largest agar producer (350 t annually). Other colloid-producing species, including Chondrus crispus and Mastocarpus stellatus, are also harvested for export. The total agarophyte landings, agar production and income from agar exports is far below the maximum levels attained in the early 1970s. The status of stocks in each different harvest zone on the continental coast and the Azores is examined. Although there is an effective management structure for the Portuguese marine plant resource, research is needed to provide a sound biological basis for management.

Relationship between Pyrophosphate : Fructose-6-phosphate 1-phosphotransferase, Sucrose Breakdown, and Respiration

Summary The aim of this work was to discover the role of pyrophosphate : fructose-6-phosphate 1-phosphotransferase [PFK(PP;)]. Substrates and enzymes of sucrose breakdown were measured during starch accumulation by the endosperm of wild type and the sh 1 shrunken mutant of Zea mays L. The results suggested that the mutant depended primarily on alkaline invertase to break down sucrose, and showed that the activities of PFK(PPi) and UDPglucose pyrophosphorylase and contents of pyrophosphate and fructose2, 6-bisphosphate (Fru-2,6-P 2 ) were no lower in the mutant than in the wild type. Appreciable activities of PFK(PPi), which were not responsive to Fru-2,6-P 2 , were found in the following red algae, which lack sucrose: Audouninella purpurea, Polysiphonia sp., Mastocarpus stellatus, Rhodymenia pseudopalmata. No PFK(PP;) was found in the bacterium Paracoccus denitrificans. Addition of sucrose to starved suspension cultures of Glycine max L. led to increases in oxygen uptake and Fru-2,6-P2 content. Glucose produced the same effects. It is argued that, although one of the functions of PFK(PP;) is production of pyrophosphate for sucrose breakdown via sucrose synthase, the key role of the enzyme is the maintenance of the cytosolic concentration of pyrophosphate according to the supply and demand of the latter.

Effect of freezing on photosynthesis of intertidal macroalgae: relative tolerance of Chondrus crispus and Mastocarpus stellatus (Rhodophyta)

The effect of freezing on photosynthetic metabolism was studied in the red algae, Chondrus crispus and Mastocarpus stellatus. Plants of both species were collected from the intertidal at Chamberlain or Kresge Point, Maine, USA (43°56′N, 69°54′W) between February and March 1987. Photosynthetic rates were measured immediately after freezing at-20°C and following recovery periods in seawater. Photosynthesis in C. crispus declined rapidly following freezing, falling to 70% of control values within 1 h and 30% after 3 h exposure. Minimum photosynthetic rates (7 to 9% of controls) occurred following freezing exposures of 12 h or more. Full photosynthetic recovery in C. crispus after 3 h at-20°C required 48 h. Photosynthesis in C. crispus did not fully recover in plants frozen for 6 h or more. In contrast, photosynthesis in M. stellatus was relatively unaffected by freezing exposures of <12 h. Twelve hours or more at-20°C reduced photosynthesis to 55% of controls. Photosynthesis in M. stellatus fully recovered from 24 h at-20°C within 24 h. In both species the reduction of photosynthesis by freezing was associated with damage to the plasma membrane and reduced efficiency of energy transfer from phycobilisomes to chlorophyll a, but did not appear to involve ribulose-1,5-bisphosphate carboxylase oxygenase activity. The freezing tolerance of C. crispus and M. stellatus positively correlates with their respective intertidal distributions, suggesting that freezing may be involved in controlling the distributions of these species on the shore.

Hordenine content of the marine alga Mastocarpus stellatus and the algal food product Carrageen

AbstractHordenine (N,N‐dimethyltryramine) occurs, throughout the year, in the red marine alga Mastocarpus stellatus (Stackh, in With.) Guiry comb, nov., at levels from 1500 μg to 5500 μg/g dry weight. Mastocarpus stellatus constituted 10% to 100% (w/w) of samples of the algal food product Carrageen, the remainder being the red marine alga Chondrus crispus Stackh. The hordenine content of Carrageen samples varied from 10 μg to 1000 μg/g, which was lower than might be expected from the hordenine content of fresh M. stellatus. Studies upon the open air bleaching process used in the production of Carrageen showed it can reduce the hordenine content of M. stellatus by 40% to 90%. However, the hordenine content of some Carrageen may be sufficient to produce adverse pharmacological interactions in some individuals.

Dietary preferences of the common periwinkle, Littorinalittorea (L.)

In gustatory choice experiments with mature macroalgae, grazing by the common periwinkle, Littorina littorea (L.), was highly selective in favour of the foliose ephemeral green algae, Ulva lactuca L. and Enteromorpha intestinalis (L.) Link. The fucoid, Ascophyllum nodosum (L.) Le Jol., and the calcareous red alga, Corallina officinalis L., were rejected even under conditions of considerable nutritional duress. Results of attractiveness trials were similar, emphasizing the important selective rôle of gustatory considerations. Macroalgal edibility was not influenced by a prolonged period of starvation or by enforced habituation to a non-preferred species. There was, however, some evidence to suggest that previous feeding experience altered algal attractiveness significantly, prompting less discriminate feeding. A high degree of selectivity was also apparent for algal germlings. Lawns of germling Ulva lactuca and Enteromorpha intestinalis were strongly preferred to juvenile Mastocarpus stellatus (Stackh.) Guiry (= Gigartina stellata (Stackh.) Batt.), Fucus serratus L. and especially Ascophyllum nodosum. Consistent preferences were displayed for adult over juvenile Ulva lactuca and for juvenile rather than adult Fucus serratus. Experimental examination Littorina littorea microdistribution on the mid-and lower shore reveals that, at sheltered sites, individuals forage predominantly on the rock surface and amongst the understorey of ephemeral algae. Higher up the shore and at exposed sites cast-up “drift” seaweeds assume an important dietary rôle. In controlled population experiments on the shore, Ascophyllum nodosum was not grazed. Consequently, this species cannot be considered a potential food source for Littorina littorea, even on those regions of the shore where it may constitute the only macroalgal cover.

Creaming of Rubber Latex

Abstract The creaming of rubber latex was first observed as far back as 1824 when Hancock, working with what was probably Castilloa latex, observed that if this latex is well shaken with three or four times its volume of water and then allowed to stand, a separation into two layers will take place which thus effects a purification of the dispersion. This phenomenon, reported again by Faraday in 1825, is a spontaneous creaming which takes place with latices of large particle size. Latex of Hevea brasiliensis will not cream spontaneously in this manner and, although other methods of inducing creaming, such as the addition of caustic alkali, were previously known, it remained for Traube in 1924 to patent the first method which would prove satisfactory for commercial concentration. Rahn had reported in 1922 that the natural creaming of milk could be greatly accelerated and made more complete if small amounts of gelatin or of similar hydrophilic colloids, such as gum tragacanth, gum arabic, peptone or albumen, were added to the milk before allowing it to stand. Recognizing the similarity between milk and rubber latex, Traube applied this knowledge to the development of the creaming of latex. He found such substances as carrageen moss, Iceland moss, and other vegetable mucilages to be effective in causing separation of the latex dispersion into two layers—the upper one rich in rubber and the lower one, generally termed serum, almost free of rubber.

Acetolysis of Carrageen Mucilage

IN a series of papers published between 1921 and 1929, Haas and his collaborators1 showed that in the mucilage of carrageen moss (Ghondrus crispus)there are two main constituents one of which can be extracted from the seaweed by cold water, the other only by hot water. They further showed that both constituents are ethereal sulphates of polymeric carbohydrates, occurring chiefly in the form of their calcium salts; but all their attempts to isolate the polymeric carbohydrates by hydrolysis led only to the production of simple hexoses. Galactose and fructose were easily recognized by them among the products of hydrolysis.