Glycohistochemistry of a marine sponge, Chondrilla nucula (Porifera, Desmospongiae), with remarks on a possibly related antimicrobial defense strategy and a note on exopinacoderm function

Based on carbohydrate histochemistry, including the use of lectins, and TEM, the study describes the distribution of terminal sugars in different structures of the demosponge Chondrilla nucula. The results of the general and specific carbohydrate histochemical approaches confirmed the presence of acidic and neutral glycoconjugates in the cells, and, with declining amounts from the ectosome to the mesohyl, in the extracellular matrix (ECM). AB-PAS staining indicated acidic complex carbohydrates particularly in the exopinacoderm, and more neutral ones in the cells and the ECM of the mesohyl. The PO-lectins applied demonstrated a general spectrum of free saccharide residues (α-d-mannose, α-/β-d-N-acetylglucosamine, α-d-N-acetylgalactosamine, α-d-galactose, β-d-galactose) in both sponge parts; α-l-fucose was only distinct in the ectosome. Sialic acids [siaα(2,3)-galactose, siaα(2,6)-N-acetylgalactosamine] were dominant in the very thin exopinacoderm, indicating O-linked high molecular weight glycoproteins. In this way a glycophysiologically ‘rigid’ outer mucus cover is developed as protection against mechanical hazards. Some of the free sugars (α-d-mannose, N-acetylglucosamine, N-acetylgalactosamine β-d-galactose, α-l-fucose) are known to prevent the adherence of different bacteria and fungi to cellular surfaces. Thus a high concentration of such sugars, may impede massive attacks of micro-inhabitants on mobile sponge cells, pinacocytes, and the exopinacoderm layer.     

Alloimmune memory for glycoproteid recognition molecules in sea anemones competing for space

A highly specific recognition system, capable of distinguishing between allogeneic (non-clonemates) and syngeneic (clonemates) conspecifics, exists in Anemonia sulcata (Coelenterata: Anthozoa). During a competitive interaction between allogeneic individuals, specialized structures (acrorhagi) are exposed and used to sting opponents. This complex behavior is called the acrorhagial response. In order to quantify this behavior we measured the acrorhagial response time (period from first contact with opponent to full expansion of acrorhagi). More than 320 reciprocal histoincompatibility responses were recorded. These histoincompatibility (H) markers are free components of the sea anemone mucus: they were characterized as glyco-proteins of a molecular weight <18 KD (Kilo-Dalton) containing terminal -d-glucose and/or -d-mannose. In alloimmune memory testing experiments, the memory trace in A. sulcata was found to persist for 5 d.     

Digestive carbohydrases from the hepatopancreas of two Antarctic euphausiid species (Euphausia superba and E. crystallorophias)

The hepatopancreatic extracts of Euphausia superba Dana and E. crystallorophias Holt and Tattersall collected from the Antarctic. Ocean during January 1985, are most effective in hydrolysing substrates containing (13)--glucosidic linkages. Three enzymes appear to be involved in the depolymerization of (13)--D-glucans in the euphausiid diet: (1) an exo-(13)--D-glucanase, (2) an endo-(13)--D-glucanase and (3) a -D-glucosidase. The glucanases have a pH optimum of 5.4, a temperature optimum of 50°C and are optimally extracted in bistripropane buffer, pH 7.2. Levels of (13)-D-glucanase in laboratory-cultured E. superba are inversely affected by food availability, and activities double after starvation for 12 d. The increase is due mainly to higher activities of exo-acting glucanases. -Amylase and endo-(14)--D-glucanase (cellulase) activity are also present in the extracts in addition to glycosidase activity against a range of p-nitrophenyl substrates (-and -D-glocose, - and -D-galactose, -D-xylose, - and -D-mannose). Digestive activity against several acidic polysaccharides, including the acidic mucilage polysaccharide of the ice diatom Stauroneis amphioxys, is minimal and is not induced when the polysaccharide is present in the diet of E. superba. These results indicate that some, but not all, components of the algal material in the euphausiid diet can be hydrolyzed and assimilated.     

Seasonal changes of locomotor activity patterns in ruin lizards Podarcis sicula

Seasonal differences in the locomotor activity pattern of Podarcis sicula held in constant conditions in the laboratory were found to be associated with systematic differences in both the freerunning period of locomotor rhythms () and the circadian activity time (). In order to establish whether the pineal played a role in the control of seasonal changes in circadian parameters, we examined the effects of pinealectomy in constant conditions on the locomotor behavior of lizards displaying the bimodal activity pattern typical of summer. In most lizards pinealectomy lengthened , shortened and abolished the bimodal activity pattern. Pinealectomy induced a sudden transition from the typical locomotor behavior of summer, characterized by a marked bimodal pattern, short and long , to the typical locomotor behavior of autumn, characterized by a unimodal pattern, a long and short . These results demonstrate that the pineal plays a central role in the seasonal reorganization of the circadian system that occurs in P. sicula.     

Influence of biological and environmental factors on nitrogenous extractives of the spurdog Squalus acanthias

The influence of sex, sexual maturity, feeding habits and season on the most important nitrogenous extractives in the muscle tissue of the spurdog Squalus acanthias L. of the southern North Sea has been studied. Feeding habits and sex have no influence, whereas the contents of -amino nitrogen, -alanine, glutamic acid and glycine decrease after sexual maturity. Only peptides are influenced by season; higher amounts occur in the spring/summer period.     

Effect of ionizing radiation on haemoglobin of marine lamellibranchs

The effect of ionizing radiation on the iron-linked protein (haemoglobin) of the marine lamellibranchs Anadara granosa (Linn.) and Cardita antiquata (Lam.) from Bombay waters, India is discussed. Purified haemoglobin solutions were exposed to a ⁶⁰Cobalt source delivering a dose of about 4,600 rad/min, at the sample irradiation point. Radiation damage or degradation was measured spectrophometrically by studying changes in the absorption spectra following irradiation in the presence and absence of oxygen. Exposure to ionizing radiation in general caused a decrease in absorption of both haemoglobins, irrespective of location, viz extra-versus intracellular, at Soret (412 m), (540 to 42 m) and (574 to 76 m) peaks, and an increase in absorption at 510 and 630 m. Upon exposure to a higher dose, O₂Hb of C. antiquata showed an increase in absorption at the protein peak (280 m); exposure to a lower dose, however, resulted in decreased absorption. Furthermore, the changes following irradiation were dependent upon the initial state of the pigment. Oxyhaemoglobin, when exposed to radiation, oxidized to hemiglobin, and hemiglobin reduced to oxyhaemoglobin. The extracellular haemoglobin of high molecular weight (3x10⁶) of the false cockle C. antiquata was found to be extremely radio-resistant, whereas intracellular haemoglobin of low molecular weight (74,000) of the arcid clam A. granosa was highly radiosensitive, since it could not be exposed to doses exceeding 18,000 r.     

Pathway and products of CO2-fixation by green prokaryotic algae in the cloacal cavity of Diplosoma virens

Light-dependent ¹⁴CO₂ fixation by the algae of Diplosoma virens (Hartmeyer) ranged between about 3 and 27 moles mg^-1 chlorophyll h^-1. The principal first products of ¹⁴C fixation were 3-phosphoglyceric acid and phosphorylated sugars, indicating that ribulose bisphosphate carboxylase was the primary carboxylation enzyme. The activity of this enzyme in crude extracts of the algae was 4 to 6 moles CO₂ mg^-1 chlorophyll h^-1. The principal end product of ¹⁴C fixation by these algae in the ascidian host was a water-soluble oligosaccharide which was an -1,4-glucan. A maximum of 7% of the ¹⁴C fixed was found in insoluble materials of the algae or its host after 60 min ¹⁴CO₂ fixation. Whether the -1,4-glucan is a product of algal or animal metabolism remains to be determined.     

Dynamics of zinc-65 specific activity and total zinc in benthic fishes on the outer continental shelf off Central Oregon

The dynamics of ⁶⁵Zn specific activity and total zinc in benthic fishes on the outer continental shelf off central Oregon (USA) were examined. A differential equation that relates specific activity of ⁶⁵Zn in fish to that in fish food was used to estimate 's (zinc uptake-rate coefficients) for 3 different size classes of the flounder Lyopsetta exillis, a small predator of pelagic Crustacea, and for 1 size class of the flounder Microstromus pacificus, a large predator of infauna. The 's obtained for L. exilis were very close to the obtained in the laboratory for the flounder Pleuronectes platessa. The estimated for M. pacificus was very much smaller than the 's estimated for the other two species. A model that related to predicted weight-specific feeding rates suggested that the smaller of M. pacificus was caused by a low absorption efficiency of zinc from its prey. Sensitivity studies indicated that time histories of specific activity in the fishes are not sensitive to moderate changes in . The negative correlation between specific activity in the diet and in the weight of L. exilis was the major cause of the negative correlative between specific activity and weight in this species. In M. pacificus, where composition of diet does not vary with size, specific activity was independent of weight. The time history of specific activity in M. pacificus was very much lower than those in the different size classes of L. exilis, a result caused mainly by the much lower specific activity of the prey of M. pacificus. Differences in specific activity among other benthic fishes were also correlated with differences in specific activity of their prey. The food-web dynamics responsible for these patterns are discussed. Variation in total zinc concentrations among species was small. Within species of flounder, zinc concentration varied only slightly or not at all with weight.     

Leaf volatiles and polyphenols in pear trees infested byPsylla pyricola. Evidence of simultaneously induced responses

Summary Feeding by the homopteranPsylla pyricola on leaves of pear trees induces the production of volatile compounds, such as (E,E)--farnesene and methyl-salicylate, as well as the production of polyphenols. The inference on induction is based on GC-MS and HPLC chromatograms from the same samples ofPsylla infested leaves, leaves from the same pear tree beforePsylla infestation and uninfested leaves from other pear trees.Psylla infestation greatly enhanced the production of volatiles ((E,E)--farnesene, methyl-salicylate and others) and triggered the production of new polyphenols, characterized by much longer retention times.However, the responses to infestation depend critically on leaf age (defined by leaf distance to apex). With respect to the leaf volatiles it appears that infested, old leaves produce fewer compounds and lower amounts of the volatiles than infested, young leaves. Moreover, there seem to be differences in pattern. Relative to (E,E)--farnesene, methyl-salicylate was found in much lower amounts in heavily infested, old leaves. With respect to polyphenols it was found that infested old leaves collected in August have polyphenols with the same retention times, but more or less equal amounts as uninfested young leaves collected in May. This shows thatPsylla infestation causes the induced response mostly in young leaves.The induced leaf volatiles may act as synomones to heteropteran bugs. As shown elsewhere,Anthocoris nemoralis responds significantly to (E,E)--farnesene and methyl-salicylate when offered in pure form against clean air in a Y-tube olfactometer. The effect of polyphenols on the performance ofP. pyricola is not yet known. Hence, a role in direct defence is still to be investigated.     

Receptor neurones in three heliothine moths responding to floral nd inducible plant volatiles

Summary. Some plant volatiles are produced in response to herbivory of several insect species, including heliothine larvae. In the present study of female heliothine moths, four co-located receptor neurone types were identified, of which three types responded strongest to the inducible compounds E--ocimene, E,E--farnesene and E,E-TMTT, respectively. The fourth type responded strongest to geraniol, which is a common floral volatile. The narrow tuning of each receptor neurone type was demonstrated by responses to a few structurally-related monoterpenes, sesquiterpenes, homo-terpenes and monoterpene alcohols, respectively, out of hundreds of plant constituents tested. The four neurone types showed the same relation of spike amplitudes and ranking of effective compounds in the three heliothine species; the polyphagous Heliothis virescens and Helicoverpa armigera and the oligophagous Helicoverpa assulta. The results indicate the presence of functionally similar types of plant odour-receptor neurones in the three related species, and suggest conservation or reappearance of functionally similar olfactory receptors in related species, independent of the evolution of polyphagy and oligophagy.     

Preliminary report on the digestive enzymes present in the digestive gland ofPerna viridis

Quantitative data on digestive enzymes of bivalves are very limited and so this study was performed to obtain such information, and to find out whether some of these enzymes are well adapted to conditions in the digestive gland. The green musselPerna viridis was obtained from Clementi West Market in 1985. The results show that various carbohydrases are present in the digestive gland. The activities of-amylase, cellulase and-glucosidase are higher than that of other carbohydrases, whilst the activities of both lipase and protease, especially the former, are low. The pH optima of the following enzymes are also given:-amylase = 5.8; laminarinase = 5.5;-glucosidase = 5.8; trehalase = 4.8;-glucosidase = 5.5. The only enzyme which was not well adapted to conditions in the digestive gland (pH 6.2) was trehalase. The wide spectrum of enzymes present in this bivalve indicates that it has the ability to utilize a wide range of nutrients efficiently.     

Primary production as influenced by diel periodicity of phytoplankton photosynthesis

Diel periodicity in parameters of photosynthesis-irradiance (P-I) curves was incorporated into calculations of integral daily phytoplankton production for the Santa Barbara Channel off southern California (USA). Model equations of the relationship between photosynthesis and light were used in combination with observed slope () and asymptote (P _max) values presented in the preceding paper. Primary production was always 19 to 39% less than comparable estimates obtained with the assumption of constant maximum daily and P _max values. Regardless of which P-I formulation was used of 6 tested, observed production (using a temporal series of simulated in situ incubations) ranged from 13% less to 25% more than estimates from constant midday and P _max values. The amplitude and timing of diel oscillations differed somewhat among 3 field stations. Maximum to minimum ratios ranged from approximately 3 to 5 for , and 4 to 6 for P _max. The differences in amplitude and timing of oscillations in P-I curves both contributed to errors in calculating phytoplankton production. Thus, photosynthetic periodicity in the upwelling area of the Santa Barbara Channel influences phytoplankton production. There were oscillations in both and P _max, and the time-dependence of these parameters should be considered to improve the accuracy of predictive models of primary productivity.     

Availability of colloidal ferric oxides to coastal marine phytoplankton

Cell growth of a coastal marine diatom, Phaeodactylum tricornutum (stock cultures), and two red tide marine flagellates, Heterosigma akashiwo and Gymnodinium mikimotoi (stock cultures), in the presence of soluble chelated Fe(III)-EDTA (1:2) and of four different phases of ferric oxide colloids were experimentally measured in culture experiments at 20°C under 3000 lux fluorescent light. Soluble Fe(III)-EDTA induced the maximal growth rates and cell yields. The short-term uptake rate of iron by H. akashiwo in Fe(III)-EDTA medium was about eight times faster than that in solid amorphous hydrous ferric oxide (Fe₂O₃·xH₂O) medium. In culture experiments supplied with four different ferric oxide forms, the orders of cell yields are amorphous hydrous ferric oxide>-FeOOH (lepidocrocite)>Fe₅O₇(OH)·4H₂O (hydrated ferric oxyhydroxide polymer >-FeOOH (goethite). The specific growth rates () at logarithmic growth phase in Fe(III)-EDTA, amorphous hydrous ferric oxide and -FeOOH media were significantly greater than those in Fe₅O₇ (OH)·4H₂O and -FeOOH media. The thermodynamically stable forms such as Fe₅O₇(OH)·4H₂O and -FeOOH supported a little or no phytoplankton growth. The iron solublities and/or proton-promoted iron dissolution rates of these colloidal ferric oxides in seawater at 20°C were determined by simple filtration techniques involving -activity measurements of ⁵⁹Fe. The orders of solubilities and estimated dissolution rate constants of these ferric oxides in seawater were consistent with that of cell yields in the culture experiments. These results suggest that the availability of colloidal iron to provide a source of iron for phytoplankton is related to the thermodynamic stability and kinetic lability of the colloidal ferric oxide phases, which probably control the uptake rate of iron by phytoplankton.     

The distribution of zinc in the oyster Ostrea edulis and its relation to enzymic activity and to other metals

The role of zinc in the oyster Ostrea edulis Linnaeus has been studied in its relation to the zinc-dependent enzymes present and in relation to the copper, calcium, magnesium, sodium, potassium and phosphate contents. Only carbonic anhydrase, alkaline phosphatase, carboxypeptidase A and malic dehydrogenase zinc metalloenzyme activities could be detected. -D-mannosidase, a zinc-dependent enzyme hitherto not reported for the oyster, was also detected. After tissue dissection into muscle, palps, gills, mantle and digestive mass and subcellular fractionation of these tissues, analysis indicated that no single tissue concentrates zinc or the zinc-dependent enzymes. The total amount of zinc found is far in excess of the amount of zinc contributed by the zinc-dependent enzymes, but the amount of non-dialysable zinc is of the same order of magnitude. It is suggested that this apparent excess of dialysable zinc is a consequence of the high levels of calcium found in the tissues, demonstrating a competition between calcium and zinc in their uptake, as is well documented in many other phyla.     

Fouling organisms in the port of Mar del Plata (Argentina). I. Siphonaria lessoni: ecological and biometric aspects

The present paper deals with ecological aspects of the pulmonate gastropod Siphonaria lessoni (Blainville, 1824), a common member of fouling communities in Mar del Plata's port (38°0817 S, 57°3118 W). Populations on colonized panels of an experimental raft were studied during three annual cycles, to determine feeding habits, growth and various factors which restrict their distribution on floating substrata. Although S. lessoni is harmless as a fouling organism, its grazing on the algal belt clears a part of the substratum's surface, which is then quickly colonized by truly aggressive organisms such as Balanus amphitrite.     

Adaptation of solitary corals and their zooxanthellae to low light and UV radiation

Adaptation of solitary corals, Fungia repanda and F. echinata, and their zooxanthellae to low light and ultraviolet light B (UV-B) was studied with respect to changes in their protein contents, photosynthetic pigment contents and the photosynthesis-irradiance (P-I) curves. The corals were collected from 1 to 50 m depths in the Republic of Belau (Paulau) in 1990 and 1991. The chlorophyll a content in a unit surface area of the coral did not change significantly with the depth of the habitat, whereas cellular chlorophyll a in the algae increased with the depth. Zooxanthellae density and protein content in a unit surface area of Fungia spp. decreased with the depth. Photosynthetic parameters normalized by a unit surface area of the Fungia spp., maximum gross photosynthetic rate (P _gmax area^-1) and dark respiration rate (R area^-1), were negatively correlated with the depth, while initial slope of the P-I curve () did not show significant correlation with the depth. Compensation light intensity (Ic) decreased with the depth. In isolated zooxanthellae, P _max chl a ^-1, and R chl a ^-1 decreased with the depth, while _{chl a} was constant. P _gmax cell^-1 and R cell^-1 did not change significantly but _cell increased with the depth. Ic decreased with the depth as in the intact corals. Reduction of protein content in a unit area of the coral from deeper habitat implies decrease of host animal tissues. Reduction of Ic can be explained by decrease of R area^-1, which may be due to the diminution of animal tissues. The photoadaptational response to low light intensity of intact Fungia spp. was found to be a combination of the photoadaptation of symbiotic algae and the decrease of host animal tissue. In order to study their adaptation to ultraviolet (UV) radiation, P-I curves of Fungia spp. and isolated zooxanthellae were analyzed before and after UV-B irradiation. 1 h UV-B irradiation showed no effect on the photosynthetic rate of the shallow water (1 m) corals, while it inhibited the photosynthesis of the deep water (30 m) corals and zooxanthellae isolated from both shallow and deep water corals. These results indicate that the host, Fungia spp., in shallow water have protective mechanism for intense UV-B in their habitat. These photoadaptational mechanisms seem to allow the Fungia spp. to have wide vertical distribution where light intensity spans more than two orders of magnitude.     

Photosynthetic characteristics of marine phytoplankton from contrasting physical environments

Two suites of phytoplankton samples have been collected in consecutive years at various times over a day from selected depths within vertically mixed and stratified water columns in the western Irish Sea, in order to provide a range of possible light histories within the populations collected. Values for the maximum rate of ¹⁴C retention (P _max) and the initial slope of the ¹⁴C retention: light intensity curve () were obtained. Supra-thermocline samples from the stratified water exhibited higher P _max values than corresponding subthermocline samples. Higher values of were also generally associated with samples from the supra-thermocline zone of the stratified region. Differences in the depth distribution of P _max and in the mixed water were small, except in the presence of a shallow thermocline. In one suite of samples from the stratified water, a diurnal increase in the P _max values of the supra-thermocline samples was observed. P _max values obtained from the samples from the mixed water were interpreted in relation to the distribution obtained from the samples from the stratified zone. Data from both the contrasting sites visited for one sample suite demonstrated a two-phase relationship between the chlorophyll a concentration and both P _max and . The rates of ¹⁴C retention of the first suite of samples were estimated by two techniques. The average differences in the retention were greater in samples from the sub-as opposed to suprathermocline zone. No trends were apparent in the smaples from the mixed waters.     

Photosynthetic performance of Laminaria solidungula measured in situ in the Alaskan High Arctic

Photosynthetic performance in the kelp Laminaria solidungula J. Agardh was examined from photosynthesis irradiance (P-I) parameters calculated from in situ ¹⁴C uptake experiments, using whole plants in the Stefansson Sound Boulder Patch, Alaskan Beaufort Sea, in August 1986. Rates of carbon fixation were determined from meristematic, basal blade, and second blade tissue in young and adult sporophytes. Differences in saturating irradiance (I _k, measured as photosynthetically active radiation, PAR), photosynthetic capacity (P _max), and relative quantum efficiency () were observed both between young and adult plants and between different tissue types. I _k was lowest in meristematic tissue (20 to 30 E m^–2 s^–1) for both young and adult plants, but consistently 8 to 10 E m^–2 s^–1 higher in young plants compared to adults in all three tissues. Average I _k for non-meristematic tissue in adult plants was 38 E m^–2 s^–1. Under saturating irradiances, young and adult plants exhibited similar rates of carbon fixation on an area basis, but under light limitation, fixation rates were highest in adult plants for all tissues. P _max was generally highest in the basal blade and lowest in meristematic tissue. Photosynthetic efficiency () ranged between 0.016 and 0.027 mol C cm^–2 h^–1/E m^–2 s^–1, and was highest in meristematic tissue. The relatively lower I _k and higher exhibited by L. solidungula in comparison to other kelp species are distinct adaptations to the near absence of light during the eight-month ice-covered period and in summer when water turbidity is high. Continuous measurement of in situ quantum irradiance made in summer showed that maximum PAR can be less than 12 E m^–2 s^–1 for several days when high wind velocities increase water turbulence and decrease water transparency.The Univeristy of Texas Marine Science Institute Contribution No. 695     

Diel oscillations of the photosynthesis-irradiance (P-I) relationship in natural assemblages of phytoplankton

Diel oscillations in the photosynthesis-irradiance (P-I) relationship are described for marine phytoplankton assemblages at 6 stations in an upwelling area off the southern California coast (USA) between May and August 1980. The initial slope () and asymptote (P _max) of P-I curves changed significantly over the day; both parameters were in phase and had similar changes in amplitude. The diel oscillations in photosynthesis appeared unrelated to changes in chlorophyll a concentrations. Amplitudes of daily variations in photosynthesis ranged from approximately 3 to 9, as measured by the maximum to minimum ratio for photosynthetic capacity (P _max). Diatom-rich samples collected during an upwelling event and those dominated by dinoflagellates both had midday to early afternoon maxima in and P _max. Samples from other locations had peak photosynthetic activity later in the afternoon. The relationship between and P _max was consistent in all phytoplankton samples analyzed, with a surprisingly high correlation considering the spatial and temporal scales encompassed in this study. These results indicate that the photosynthesis-irradiance (P-I) relationship is time-dependent and, moreover, that changes in and P _max are closely coupled for a variety of natural phytoplankton assemblages.     

Triterpenoid and caffeic acid derivatives in the leaves of ragweed, <Emphasis Type="Italic">Ambrosia artemisiifolia</Emphasis> L. (Asterales: Asteraceae), as feeding stimulants of <Emphasis Type="Italic">Ophraella communa</Emphasis> LeSage (Coleoptera: Chrysomelidae)

Summary. The leaf beetle Ophraella communa infests almost exclusively Ambrosia artemisiifolia in the fields of Japan, even though it normally feeds on several Asteraceous plants. A filter paper bioassay showed that the feeding of O. communa is strongly stimulated by methanolic extracts of A. artemisiifolia. The feeding stimulants for O. communa have been isolated from methanolic extracts of A. artemisiifolia. -Amyrin acetate, -amyrin acetate, 5-caffeoylquinic acid (chlorogenic acid) and 3,5-dicaffeoylquinic acid from A. artemisiifolia have been identified as feeding stimulants for O. communa. Triterpenoid derivatives (-amyrin acetate or -amyrin acetate) and caffeic acid derivatives (3, 5-dicaffoylquinic acid or 5-caffeoylquinic acid) showed feeding stimulant activity when mixed together.