Volume 43, Issue 3

The maintenance of isomorphic life histories in algae has been difficult to explain when there is no difference between the ecological niche of the two adult phases. However, at the level of spores, physiological differences could exist in the reproduction and development between tetraspores and carpospores that could influence the composition of both phases in the field and interspecific competition. The release, attachment (winter vs. beginning of autumn) and survival (seasonal), of tetraspores and carpospores of Gracilaria pacifica Abbott from Estero de Punta Banda, Baja California, México, were studied in a gradient of temperature and irradiance. The release of tetraspores was directly affected by irradiance, while that of carpospores was affected by irradiance and temperature. The attachment of tetraspores was directly affected by temperature and season while the attachment of carpospores showed a response to changes in irradiance. Survival was influenced mainly by seasons. In spring, summer, and autumn (May, August–September, and November/December respectively) both types of spores responded similarly, with the lowest survival rate in summer and the highest in other seasons. However in winter (January/February), the rate of survival of tetraspores was an order of magnitude greater than in carpospores. The highest survival rate occurred at 21 °C and 24 °C, whereas the survival rate at 15 °C was close to zero for both types of spores. These different responses between tetraspores and carpospores, suggest a different ecophysiological response with regard to survival and interspecific competition in nature of the gametophyte vs sporophyte.

The fine structure of the asci and ascospore appendages of Linocarpon appendiculatum and L. nipae is reported. The ascus wall in both species comprised a single electron-dense granular layer. The apical ring in L. appendiculatum comprised a C-shaped electron-dense structure, and this is compared with similar pyrenomycetes. The ascospore wall of both species comprised a thin episporium and a thick bipartite mesosporium, and the basal appendages comprised a fibrillar component. The appendicular fibrils in L. appendiculatum were surrounded by a collar-like structure, which was absent in L. nipae .

A mass development of benthic Sarcinochrysidales (Chrysophyceae s.l. ), especially of Chrysoreinhardia giraudii comb. nov. (basionym: Tetraspora giraudii ) and Nematochrysopsis marina comb. nov. (basionym: Tribonema marinum ), is reported from the Corsican coast. Morphology, habitat and seasonal development of these taxa as well as of the less regularly observed Chrysonephos lewisii and of some Chrysophyceae s.l. associated with Chrysoreinhardia giraudii sheaths are presented.

Forty eight HPLC peaks from three distinct TLC zones obtained from crude lipid extracts of the tropical marine red alga Spyridia filamentosa were assayed against five pathogenic microorganisms. Of these, nineteen showed detectable activities (seven HPLC peaks from TLC zone 5; five peaks from TLC zone 9; seven peaks from TLC zone 12). Activities by single HPLC peaks were generally against one or two assay microorganisms. The total number of biologically active compounds in a given alga is shown to be substantially greater than can be ascertained by assaying whole-algal extracts.

The 13 C nuclear magnetic resonance spectra of unsubstituted algal galactans of simple diad structure, together with their sulfated, methylated and permethylated analogues, are recorded as sets of signals, and provisional assignments are presented in matrix form for those spectra previously unassigned. This use of discrete mathematics permits a concise and transparent presentation of changes in chemical shifts arising from various substitutions. Regularities in the chemical shifts due to substitution, represented in matrix form, are observed for methylation and to a lesser extent for sulfate ester. Different reference matrices are required for each conformational state about linkage bonds, and some irregularities, particularly where there is sulfate ester near the linkage bond, can be interpreted in terms of changes in conformation brought about by the substitution. The β-shifts due to substitution are provisionally interpreted in terms of changes of the magnetic vector potential from residual magnetization fields from the region of substitution. The chemical shifts of methoxyl carbon atoms vary by approximately 6 ppm, are characteristic of their location on the polymer and may be of use for structural analysis. Changes of chemical shift due to substitution are sufficiently regular for the examples described here that they should be useful for predicting spectra of unknown red algal galactans.

In this report, the 13 C NMR chemical shifts of some red algal galactans which are not based on one diad repeat unit, together with their methylated derivatives, are examined for regularities using the techniques of discrete mathematics. Evidence is found for a new carrageenan diad, 3-linked galactose-4-sulfate and 4-linked galactose 3-sulfate, from a commercial sample of ι-carrageenan and from the α-carrageenan-bearing Catenella nipae . The utility of set theory is shown for the unravelling of features of spectra containing several diads. Further confirmation is found that the polysaccharide from Pachymenia lusoria occurs as a block copolymer in that selective hydrolysis of the anhydrogalactosyl bonds permitted a polymer fraction to be obtained which contained only 3-linked D-galactose-2-sulfate and 4-linked D-galactose or 2- O -methyl-D-galactose.

The polysaccharide from Cladhymenia oblongifolia and some of its derivatives have been examined by 13 C nuclear magnetic resonance spectroscopy and the spectra analysed with the techniques of set theory. The polysaccharide is an agaroid with significant levels of sulfation at most positions other than the axial hydroxyl group. The 4-linked units consist of anhydrogalactosyl and galactosyl units in the approximate ratio of 3:2. The galactose, but not the anhydrogalactose, units in the natural polymer have high levels of 2-sulfate ester, while low levels of galactose-3-sulfate are also present in the galactosyl residues. The 4-linked galactosyl units also contain significant levels of 6-sulfate, which is converted to anhydrogalactose by alkali treatment, including significant levels of anhydrogalactose-2-sulfate. The 3-linked units consist of high levels of galactose 2-sulfate, moderate levels of galactose 6-sulfate, and very low levels of pyruvate acetal. Methylation is largely absent from this polysaccharide. The approximate structure can be summarized in set theory nomenclature as 3DG∣2S 0.4 (4,6)P 0.05 6S 0.4 ∣ – 4L{AG 0.6 , G 0.4 ∣2S 0.35 3S 0.1 6S 0.3 ∣}. The polysaccharide is similar to those extracted from other members of the Rhodomelaceae to the extent that it is a non-gelling agaroid, but the high levels of 2-sulfation are unusual as is the total variation in sulfation.

Following the 1982–83 El Niño, Macrocystis pyrifera (L.) C. Agardh, forests disappeared throughout their range in Baja California. The giant kelp forests subsequently recovered within this range except at their extreme southern limit, a region encompassing 50 km of coastline with a former giant kelp standing stock of 28,000 wet tons. Two techniques were tested to restore these forests: juvenile transplantation and seeding with sporophylls. For transplanting, juvenile M. pyrifera sporophytes were attached to Eisenia arborea stumps seasonally over a two-year period. Average survival of transplants ranged from 7% in spring to 41% in winter. After two years, the average number of basal fronds per plant increased from 2 to 64 per plant and surface fronds from 0 to 34 per plant. Average frond growth rate of the transplants ranged from 8.1 cm day −1 in summer to 10.8 cm day −1 in winter. No significant differences in growth rate were found among treatments (seasons) for the transplants, but control plants showed a seasonal variation, with higher frond growth rates in winter (13.3 cm day −1 ) and spring (9.3 cm day −1 ) and lower in summer (4.4 cm day −1 ). The seeding technique was tested in a fully orthogonal-block design with three factors with two levels (factors: ± sporophylls addition, ± Eisenia arborea and ± understory algae). Macrocystis pyrifera recruitment occurred only in treatments with added sporophylls. The highest recruitment occurred where all algae were removed from the bottom, followed by the treatments without understory algae but with Eisenia arborea . This results suggest that a lack of spores and the presence of understory algae were the main factors inhibiting Macrocystis pyrifera recruitment in the area. Lower sea water temperatures and high nutrient concentrations occurred in spring and high temperatures and low nutrients in summer suggesting, as in southern California, an inverse relationship between these two factors. The results suggest a combined approach of transplanting juveniles and seeding during spring would be most effective for restoring the M . pyrifera forests.

Dark treatments both in the laboratory and in the wild have been used to promote the enzymic conversion of L-galactopyranosyl-6-sulfate residues to 3,6-anhydro-α-L-galactopyranosyl residues in the agar type polysaccharide of the red alga Gracilaria chilensis . The native agar extracted after dark treatment has a significantly improved gel strength.

Details of vegetative and reproductive development of Osmundea osmunda (S. G. Gmelin) Nam et Maggs (Rhodomelaceae, Rhodophyta), the type species of the resurrected genus Osmundea Stackhouse, are presented based on an examination of liquid-preserved and herbarium specimens collected from the British Isles. Each axial segment bears one trichoblast and two pericentral cells on either side of basal cell of the trichoblast. Spermatangial development follows the typical filament type in which spermatangial filaments derive from apical and epidermal cells in pocket-shaped pits with ostiole-like upper openings. Procarp-bearing segments of female trichoblasts have five pericentral cells, of which the fifth acts as the supporting cell of the carpogonial branch. Tetrasporangia are produced from random epidermal cells in apical pits of branchlets, and are arranged parallel to the stichidial axis. Two presporangial cover cells also exhibit parallel arrangement to the stichidial axis as seen in surface view. Among the known Osmundea species, O. osmunda is characterized by having a strongly compressed thallus with distichous branching, a discoid holdfast, lack of secondary pit connections between epidermal cells, presence of lenticular medullary thickenings, non-palisade-like arrangement of epidermal cells in a transverse section of branchlets, pocket-shaped spermatangial pits in adaxial series between a branchlet and its parent axis, clustering terminal sterile cells in spermatangial filaments, procarp-bearing segments with five pericentral cells in female trichoblasts and cystocarps with non-protuberant ostioles. A discussion on phylogenetic implications of these vegetative and reproductive features is also included.

The reproductive phenology of Hypnea musciformis (Wulfen) Lamouroux was analyzed, over a period of two years, in two subtidal epiphytic populations located in Sepetiba Bay and another intertidal epilithic population on a shore exposed to the open sea. All sites are located in Rio de Janeiro State. These investigations suggest that in this species asexual reproduction predominates over sexual reproduction. There are more vegetative than reproductive thalli under environmentally stressful conditions for growth. Cystocarpic plants were only collected from the intertidal epilithic population and always only represented by a low proportion of biomass whereas male plants were not found. The rarity of gametophytes can probably be explained by the replacement of sexual reproduction by asexual reproduction via apomixis or vegetative reproduction.