The pathway of the biosynthesis of non-methylene-interrupted dienoic fatty acids in molluscs

• 1.1. The metabolic fate of 1-¹⁴C-acetate administered to the marine bivalve mollusc Mytilus edulis was investigated.
• 2.2. The active incorporation of the label in 20:2 non-methylene-interrupted dienoic (NMID) fatty acids was found.
• 3.3. Acetate incorporation patterns and specific radioactivity of mussel acids suggest that 22:2Δ7,13 and 22:2/gD7,15 arose by C₂ elongation of 20:2Δ5,11 and 20:2Δ5,13 respectively.
• 4.4. The proposed pathway of NMID fatty acid biosynthesis in molluscs is discussed.

     

The effects of organic and inorganic pollutants on intracellular phosphate compounds in blue mussels (Mythus edulis)

• 1.1. The effects of sublethal concentrations of organic and inorganic pollutants on intracellular energy-rich phosphates in blue mussels, Mytilus edulis, were investigated by in vivo ³¹P-NMR.
• 2.2. Formaldehyde (30 and 10mg/l), phenol, pyridine, mercury and cadmium gave marked reductions in phosphoarginine and, in some cases, the ATP amounts. The reduction in high-energy phosphate was accompanied by an increase in inorganic phosphate in all groups.
• 3.3. A “phosphorus index”, the product of the ratios between phosphoarginine and inorganic phosphate, and ATP and inorganic phosphate, is suggested, which might serve as an early warning (“alarm”) parameter in environmental monitoring.
• 4.4. Diversity in the responses to different pollutants make phosphorus compounds in M. edulis also an interesting element in a finger print parameter system designed to distinguish between pollutants in the marine environment.

     

Organohalogen constituents of the acorn worm Ptychodera bahamensis

• 1.1. Twenty organohalogen compounds, primarily phenols, were detected in the volatile extracts of the acorn worm Ptychodera bahamensis.
• 2.2. Five chlorinated compounds, previously undescribed from acorn worms, were identified.
• 3.3. Enteropneusts can be significant contributors of halogenated organics to the marine environment.

     

Variations of respiratory rate of Tisbe holothuriae humes (copepoda,harpacticoida) in relation to temperature,salinity and food type

• 1.1. The influence of temperature (14,19, 24°C), salinity (26,32, 38,44%.) and food type (artificial diets: Fryfood, Mytilus, Soya, Yeast, Spirulina) on the respiratory rate of Tisbe holothuriae has been studied.
• 2.2. Oxygen consumption decreased with decreasing temperature, but with a greater rate at supra- or subnormal salinities.
• 3.3. Multiple-regression analysis showed the quadratic effect of temperature and the linear effect of salinity to be the more important factors affecting respiration.
• 4.4. The food type also seems to exert an important effect on oxygen consumption.
• 5.5. A significant lowering of respiration was observed for all food tested when the animals were starved.

     

Variations in the levels of progesterone in Mytilus edulis during the annual reproductive cycle

• 1.1. Progesterone levels in Mytilus edulis males and females during the annual reproductive cycle were analysed in the whole animal and in the gonads using gas-liquid chromatography and radioimmunoassays.
• 2.2. The high hormone levels in the whole animal were observed in July and October, coincident with the main spawning seasons.
• 3.3. The levels of progesterone in gonad extracts also show a maximum in summer (July).
• 4.4. The patterns of the progesterone levels in males and females throughout the annual reproductive cycle are similar.
• 5.5. These data are discussed in relation to the role of progesterone in the regulation of sex-specific processes, particularly gametogenesis.

     

S-Adenosyl-l-methionine decarboxylase activities in Mytilus edulis

• 1.1. The activities of S-adenosylmethionine decarboxylase (EC 4.1.1.50) were measured in cell extracts of mantle, hepatopancreas and foot from Mytilus edulis.
• 2.2. The apparent molecular weights of the enzymes estimated by gel filtration chromatography were 65,000 ± 10,000.
• 3.3. The enzymes do not require bivalent cations for catalysis and show optimum pH between 7.0–8.0 in phosphate buffer.
• 4.4. The hepatopancreas enzyme shows different behavior to the other two enzymes against temperature and its activity is strongly inhibited by NH₄⁺.
• 5.5. The apparent K_ms for S-adenosylmethionine were found to be 300, 200 and 250 μM for the hepatopancreas, mantle and foot enzymes, respectively.

     

Immunochemical and immunohistochemical determination of ubiquitin in molluscan (Mytilus edulis) smooth muscle

• 1.1. Immunochemical and immunohistochemical distribution of ubiquitin in the anterior byssus retractor muscle (ABRM) of Mytilus edulis was investigated.
• 2.2. In immunostaining, specific ubiquitin immunoreactivity was observed in the cross-sectioned ABRM, and was uniformly localized in this section.
• 3.3. The amount of free ubiquitin in the ABRM homogenate was 130 ± 4.6 ng/mg protein by western blot analysis, and ubiquitin conjugates were found at about 25, 29 and 200–230 kDa.
• 4.4. These findings were similar to those obtained in the skeletal muscle of rat.

     

The glycogen content in stressed marine bivalves: The initial absence of a decrease

• 1.1. Changes in the glycogen content, condition, stomach content and acetic acid concentration of mussels Mytilus edulis and cockles Cerastoderma edule were followed during periods of up to 14 days of exposure (to air) at temperatures of 5 and 20°C.
• 2.2. In animals with a high glycogen content the glycogen is not used during the first 3 to 7 days, at high and low temperature respectively.
• 3.3. After this latent period the glycogen concentration often decreased, coinciding with a high mortality and an increase of the concentration of acetic acid.
• 4.4. In cockles with a low glycogen content, and kept at a high temperature, glycogen can be used from the beginning of the stress period.
• 5.5. Between species no clear differences were found.
• 6.6. The stomach content decreased during exposure; however, the stomach content amounted to only 0.5 to 0.7% of the body weight, and is thought to be of minor importance as an energy source during the stress period.
• 7.7. Especially at the higher temperatures glycogen finally is transformed into acetic acid.
• 8.8. It is concluded that during exposure, the animals do not die because of a lack of energy reserves, but because of a high accumulation of acids.

     

Is the metal binding protein metallothionein present in the coelenterate Hydra attenuata?

• 1.1. Studies have been performed on untreated and heavy metal treated Hydra attenuata in order to reveal the presence of low mol. wt metal-binding proteins.
• 2.2. A prepared rat metallothionein (Mt) standard, gel permeation, polyacrylamide gel electrophoresis and autoradiographic techniques were used in the experiments.
• 3.3. Our results indicate that H. attenuata, and three species of marine coelenterates, lack metallothionein (Mt) or other metal binding proteins.

     

The regulation of glucose 6-phosphate dehydrogenase from Dicentrarchus labrax (bass) liver

• 1.1. Kinetic constant values of the reaction catalyzed by bass liver glucose 6-phosphate dehydrogenase show to be modified between 10 and 40°C.
• 2.2. The Arrhenius plot between 10 and 50°C shows two slopes with different activation energies.
• 3.3. These results suggest a regulation of this enzyme by environmental temperature.
• 4.4. Kinetics of ATP inhibition were examined between pH 6.2 and 7.8: patterns and K_i values obtained are affected by the pH variation.
• 5.5. NADH is an effective inhibitor of bass glucose 6-phosphate dehydrogenase but this enzyme does not show NAD-linked activity.
• 6.6. Kinetics of pyridoxal 5′-phosphate inhibition have indicated the presence of a lysine in the catalytic site for NADP⁺.

     

Root effect hemoglobins in marine fish

• 1.1. The Root effect was evaluated in hemolysates from 26 species of bony fish and 20 species of cartilaginous fish found on the Brazilian southeastern coast.
• 2.2. Teleost Root shifts, with a single exception, are correlated with the presence of the choroid rete mirabile but not with its counterpart in the swimbladder.
• 3.3. Five ray species displayed weak and moderate Root effects despite the absence of choroid and swimbladder rete.
• 4.4. The presence and intensity of the Root effect is probably primarily related to the high oxygen demand of the retina and with the importance of visual perception in fish.
• 5.5. In marine teleosts the magnitude of the Root effect seems to be associated with the presence and size of both the choroid rete and the pseudobranch.
• 6.6. An antioxidant protection of the fish eyes can be advocated for the pseudobranch.

     

Relative contribution of two mechanisms to post-stimulus hyperpolarization in leech retzius cells

• 1.1. In Retzius cells of the horse leech, Haemopis sanguisuga, intensive firing is followed by prolonged post-stimulus hyperpolarization (PSH) mediated by an increase in K-conductance and activation of the electrogenic sodium pump.
• 2.2. The recovery of membrane potential during PSH can be described by a biexponential model from which the relative contribution of the early and the late component to the peak amplitude of PSH may be calculated.
• 3.3. The time course of the calculated early component coincides with the time course of changes that occur in input membrane resistance during PSH.
• 4.4. The relative contribution of the late component increases linearly with an increase in stimulus duration. The rate constants of the two phases did not change with changes in stimulus duration.
• 5.5. It was concluded that the proposed model is useful for the estimation of the relative contribution and kinetics of two PSH mediating mechanisms (K-conductance increase and activation of an electrogenic sodium pump) in different experimental conditions.

     

In situ phosphorylation of contractile proteins of a molluscan Mytilus edulis catch muscle in different functional states

• 1.1. The incorporation of ³²P into the contractile proteins of the anterior byssus retractor muscle of Mytilus edilus L. was analyzed during the different stages of a contraction-catch-relaxatin cycle.
• 2.2. The experiments were performed with saponin-skinned fibers preincubated with γ-³²P-ATP.
• 3.3. The total amount of ³²P incorporated into the fiber proteins was anlyzed by measuring the label of TCA-insoluble protein in a scintillation counter.
• 4.4. The dose incorporated was about twice as high during Ca²⁺ induced contraction and serotonin induced accelerated relaxation as during test and catch.
• 5.5. The molecular mass of the phosphorylated proteins was analyzed by autoradiography of the proteins separated by SDS-PAGE.
• 6.6. Up to 26 protein spots of different molecular masses were labelled, including such well characterized protein spe+cies as myosin heavy and light chains, paramyosin and tropomyosin.

     

Sterol composition of three marine sponge species from the genus Cinachyrella

• 1.1. The hitherto undescribed sterol compositions of three marine sponge species belonging to the genus Cinachyrella are reported: C. alloclada and C. kükenthali from the Senegalese coast, at two different depths, and C. aff. schulzei from the lagoon of Nouméa, New Caledonia.
• 2.2. Fourteen free sterols have been identified by GC and GC/MS studies, including the 23,24ξ-dimethylcholesta-5,22-dien-3β-ol (10) and the rare 24-norcholesta-5,22-dien-3β-ol (1).
• 3.3. The first compound (10) is reported for the second time in a marine sponge and it was found only in Senegalese sponges collected in shallow waters.
• 4.4. Sterol (10) has been isolated by HPLC and identified by NMR techniques.
• 5.5. Significant amounts of cholest-7-en-3β-ol (7) were also found in the Senegalese sponge species.
• 6.6. Apart from these two compounds, the three sponge sterol compositions are found to be very similar.

     

Responses of antioxidants and lipid peroxidation in mussels to oxidative damage exposure

• 1.1. The aim of this work was to evaluate the relationships between free radical scavengers and lipid peroxidation in the common mussel Mytilus edulis.
• 2.2. Mussels were exposed to compounds known for their ability to produce free radicals (carbon tetrachloride, CCl₄) and reactive oxygen species via redox cycling (menadione), and the effects on digestive gland, gills and remaining tissues were studied.
• 3.3. Lipid peroxidation parameters and the status of free radical scavengers (glutathione, vitamins A, E and C) were affected more by exposure to menadione than to CCl₄.
• 4.4. The observed changes in the free radical scavengers content are indicative of a role in detoxication of damaging reactive species.

     

Comparative examination of the soluble muscle proteins of two species of angler-fish (Lophiidae): Lophius piscatorius (L.) and Lophius budegassa (Spinola)

• 1.1. A comparative examination of sarcoplasmic proteins of the two nominal European species of angler-fish, Lophius piscatorius and L. budegassa was carried out using isoelectric focusing techniques.
• 2.2. Two protein bands differing in isoelectric point proved diagnostic for L. budegassa (pI 4.40 and pI 5.75) while a third characterized L. piscatorius (pI 4.65).
• 3.3. These species-specific protein profiles provide a method of species discrimination independent of morphological criteria.
• 4.4. Within-species heterogeneity of banding pattern suggested the presence of polymorphic gene loci of potential use in studies of population structure.

     

Investigation of phycocyanin-membrane interaction: Promotion of membrane interactions

• 1.1. In a continuing investigation of phycocyanin-membrane surface interaction, fluorescence quenching experiments were performed with a mixture of two populations of fluorescence probe-encapsulated phospholipid bilayer vesicles in the presence and absence of phycocyanin.
• 2.2. These membrane vesicles were prepared with 1,2-dimyristoyl phosphatidylcholine (DMPC), cholesterol and a probe molecule.
• 3.3. A fluorophore was encapsulated in one population of membrane vesicles, while a quencher was encapsulated in another population of membrane vesicles.
• 4.4. The result was compared with those of experiments in the presence of other biomolecules, including albumin, cytochrome c, hemoglobin, myoglobin or RNA.
• 5.5. Interestingly, a one-third reduction of the fluorescence intensity was observed in the mixture of these two populations of membrane vesicles in phycocyanin's presence.
• 6.6. In contrast, the other biomolecules caused no significant reduction in the fluorescence intensity.
• 7.7. These findings were evidence of a phycocyanin-induced membrane perturbation.
• 8.8. This was further demonstrated by a phycocyanin-induced change in the thermotropic behavior of DMPC vesicles, as measured by differential scanning microcalorimetry.
• 9.9. Such a unique property of phycocyanin is believed to be associated with its known membrane surface-interacting character.
• 10.10. A possible phycocyanin-modulated membrane-membrane interaction was discussed.

     

Oxygen binding by the hemocyanin of Busycon canaliculatum

• 1.1. This study examined the effect of the monoamines dopamine and octopamine, as well as tyrosine on the oxygen affinity and cooperativity of oxygen binding by the hemocyanin of the marine gastropod Busycon canaliculatum. The effect of temperature on hemocyanin oxygen affinity was also examined.
• 2.2. Freezing Busycon hemocyanin did not affect the binding of oxygen.
• 3.3. Dopamine, octopamine and tyrosine had no significant effect on the oxygen affinity or cooperativity of oxygen binding by the hemocyanin of B. canaliculatum.
• 4.4. It was concluded that Busycon hemocyanin either has no binding sites for the two monoamines or for tyrosine, or that binding of the molecules has no functional significance.
• 5.5. Both temperature sensitivity and affinity of hemocyanin-oxygen binding were similar to values previously reported for hemocyanin of Busycon from other localities.

     

Metabolic roles of carnitine expressed through the carnitine acetyltransferase system in Candida pintolopesii

• 1.1. The carnitine-responsive mutant yeast, Candida pintolopesii ATCC 26014 and the wild type strain (ATCC 22987) were used to investigate the role of carnitine and the carnitine acetyltransferase system.
• 2.2. [³H]l-Carnitine, supplied to the cells, was incorporated into acetylcamitine and [¹⁴C]pantothenate was incorporated into CoA and its derivatives.
• 3.3. Both bioautography and quantitative assays indicated that the relative amounts of CoA and acetylCoA were very different in the mutant and wild type cells.
• 4.4. The wild type yeast maintained an acetylCoA/CoA ratio of 0.33 ± 0.09 indicating that most of the CoA in the cell is in the free CoA form. Carnitine was not required to establish this ratio nor did its presence lower it further.
• 5.5. In contrast, the mutant cells contained a high acetylCoA/CoA ratio (12.8 ± 3.0).
• 6.6. In the mutant cells, carnitine lowered the ratio by decreasing the intracellular acetylCoA concentration and releasing free CoA.
• 7.7. These data indicated that wild type yeast possess an effective mechanism that is not related to the CAT system for regulating the acetylCoA/CoA ratio.
• 8.8. This mechanism appears to be lacking in the mutant. The CAT system decreased the acetylCoA/CoA ratio in the mutant cells but not to the value which is found in the wild type strain.
• 9.9. In both stains of Candida pintolopesii, in the presence of carnitine, an acetylcamitine pool can be created whose concentration exceeds that of acetylCoA.
• 10.10. The intracellular apparent equilibrium constant (K_app) for carnitine acetyltransferase for wild type Candida pintolopesii ATCC 22987 was 0.73 ± 0.12, close to the established value of 0.6, indicating that the CAT system ran close to equilibrium.
• 11.11. The K_app for the CAT system of the carnitine-responsive mutant yeast was 7.7 ± 1.7 indicating that this reaction was not at equilibrium.

     

Insulin,glucagon and catecholamine interactions in avian liver explants

• 1.1. A mechanical tissue chopper was used to obtain liver explants (35–75 mg) from 2- to 3-week-old chickens to determine both tissue sensitivity and metabolic effects of isoproterenol, avian insulin and glucagon.
• 2.2. Avian insulin had no effect on lipogenesis; however, lipogenesis was decreased by dibutyryl cyclic AMP. Insulin did not overcome a decrease in lipogenesis caused by catecholamines. Therefore, this control mechanisms is not modulated by insulin.
• 3.3. Preincubation in the presence of glucagon decreased in vitro lipogenesis. Preincubation in the presence of a 19–29 amino acid construct that approximated the radioimmune site for glucagon did not result in a similar effect. Therefore, this site does not relate to the biopotency of the hormone.
• 4.4. A previously noted catecholamine induced decrease in in vitro lipogenesis was verified, showing that points of in vitro regulation are under phosphorylation-dephosphorylation control.
• 5.5. Preincubation of slices (1 hr) with propranolol blocked the inhibition of lipogenesis caused by α and β adrenergic agonists (arterenol or isoproterenol) during a subsequent 2-hr incubation.
• 6.6. Preincubation of slices with either of these agonists decreased lipogenesis even following an extensive washout.
• 7.7. Inhibition could be overcome with propranolol, a β adrenergic antagonist.