Studies in the biochemistry of cirripede eggs. V. Changes in the general biochemical composition during development of Chthamalus stellatus (Poli)

The biochemical composition of the eggs of Chthamulus stellatus (Poli) during their development has been investigated. The eggs are incubated within the mantle cavity of the adult but no substrates are contributed by the latter. Carbohydrates, protein, and lipid are all utilized. In contrast to two cold-water species, Balanus balanoides and B. balanus perviously investigated lipid rather than protein is consumed during the early stages. Possible explanations for this are considered.     

Seasonal changes in the activity of certain enzymes in crude tissue extracts of two common cirripedes, Balanus balanoides (L.) and B. balanus (L.).

The activity of glutamate-oxaloacetate transaminase (GOT), glutamate-pyruvate transaminase (GPT), lactate dehydrogenase (LDH), malate dehydrogenase (MDH), isocitrate dehydrogenase (ICDH), and aldolase in tissue extracts of Balanus balanoides (L.) and B. balanus (L.) have been determined at regular intervals over a year, and an attempt made to relate the results to known biochemical changes in the animals.The work was ecologically orientated. Preliminary studies on the effects of extractant, dialysis, and possible endogenous interference were made and the subsequent procedure rigorously standardized.Transamination was investigated by TLC. LDH and aldolase show striking seasonal changes; an abundance of the former is associated with the production of semen. MDH, concerned in carbohydrate and lipid metabolism, was present in considerable quantities but there were no marked seasonal changes. GPT activity is high when reproductive products are being produced from reserves of food and the activity is also related to the production of semen. GOT showed no clear seasonal trends.The results are discussed relative to the metabolism of crustaceans: the part played by proteins and lipids is stressed.     

The early development of the cement apparatus in the barnacle, Balanus balanoides (L.) (Crustacea: Cirripedia)

The development of the cement cells of Balanus balanoides (L.) has been followed over a 26-day post-settlement period. Cells of the cyprid cement glands de-differentiate to form part of the juvenile barnacle apparatus, but the majority of juvenile cement cells develop by differentiation of collecting duct cells. These latter cement cells are recognized by apical invaginations which are continuous with the collecting duct lumen. Collecting ducts are present in the cyprid. The cement duct system was not studied in detail, but preliminary observations of the arrangement in B. balanoides and Elminius modestus Darwin have shown them to differ, the system in E. modestus being simpler.     

Influx and net flux of amino acids into larval and juvenile European flat oysters, Ostrea edulis (L.)

Influx and net flux of amino acids into veliger, pediveliger, and juvenile stages of the oyster, Ostrea edulus (L.), were examined. Influx of alanine and glycine was determined using ¹⁴C-labelled substrates and monitoring the disappearance of radioactivity in the medium. Net influx was determined fluorometrically by following the disappearance of primary amines from solutions containing known substrates. Rates of influx and net influx are comparable for juvenile Ostrea down to ambient substrate levels of 2 μM. Net influx of amino acids into veliger and pediveliger larvae occurs at all concentrations examined (9 μM minimum). Rates of maximum influx (J_maxⁱ) and ambient substrate concentration at which influx is half-maximal (K_t) are reported for each stage. The K_t for glycine and alamine influx is 35–40 μM, decreasing to ≈ 15 μM in 1.5 mm sized juvenile oysters.     

Regulatory Factors Associated with Synthesis of the Osmolyte Glycine Betaine in the Halophilic Methanoarchaeon Methanohalophilus portucalensis

The halophilic methanoarchaeon Methanohalophilus portucalensis can synthesize de novo and accumulate β-glutamine, N-acetyl-β-lysine, and glycine betaine (betaine) as compatible solutes (osmolytes) when grown at elevated salt concentrations. Both in vivo and in vitro betaine formation assays in this study confirmed previous nuclear magnetic resonance ¹³C-labelling studies showing that the de novo synthesis of betaine proceeded from glycine, sarcosine, and dimethylglycine to form betaine through threefold methylation. Exogenous sarcosine (1 mM) effectively suppressed the intracellular accumulation of betaine, and a higher level of sarcosine accumulation was accompanied by a lower level of betaine synthesis. Exogenous dimethylglycine has an effect similar to that of betaine addition, which increased the intracellular pool of betaine and suppressed the levels of N-acetyl-β-lysine and β-glutamine. Both in vivo and in vitro betaine formation assays with glycine as the substrate showed only sarcosine and betaine, but no dimethylglycine. Dimethylglycine was detected only when it was added as a substrate in in vitro assays. A high level of potassium (400 mM and above) was necessary for betaine formation in vitro. Interestingly, no methylamines were detected without the addition of KCl. Also, high levels of NaCl and LiCl (800 mM) favored sarcosine accumulation, while a lower level (400 mM) favored betaine synthesis. The above observations indicate that a high sarcosine level suppressed multiple methylation while dimethylglycine was rapidly converted to betaine. Also, high levels of potassium led to greater amounts of betaine, while lower levels of potassium led to greater amounts of sarcosine. This finding suggests that the intracellular levels of both sarcosine and potassium are associated with the regulation of betaine synthesis in M. portucalensis.     

Regeneration of the penis in Balanus balanoides (L.)

In Balanus balanoides (L.) the penis is ‘lost’ each autumn. The regeneration of the penis is described. The primordium contains mesenchyme. The pedicel structures develop early as thickened areas of the exoskeleton and give rise to the characteristic structural features of the mature pedicel. Tissue differentiation begins in the pedicel and later extends to the penis proper which becomes annulated. The ductus eventually opens by a terminal invagination of the exoskeleton.     

Heavy metal complexation in polluted molluscs II. Oysters (Ostrea edulis and Crassostrea gigas)

Cadmium, zinc and copper, accumulated from polluted habitats by the oysters Ostrea edulis and Crassostrea gigas, were studied. Three distinct low molecular weight (less than 3000 daltons) zinc complexes were separated from highly contaminated C. gigas, one of which may be a complex with the amino acid taurine. Only one of these zinc complexes was present in less contaminated specimens of O. edulis. On gel permeation chromatography of oyster extracts, copper was eluted together with amino acids (principally taurine) and the betaine homarine. No evidence of metallothionein type proteins was found.     

Glycine Betaine as a Direct Substrate for Methanogens (Methanococcoides spp.)

Nine marine methanogenic Methanococcoides strains, including the type strains of Methanococcoides methylutens, M. burtonii, and M. alaskense, were tested for the utilization of N-methylated glycines. Three strains (NM1, PM2, and MKM1) used glycine betaine (N,N,N-trimethylglycine) as a substrate for methanogenesis, partially demethylating it to N,N-dimethylglycine, whereas none of the strains used N,N-dimethylglycine or sarcosine (N-methylglycine). Growth rates and growth yields per mole of substrate with glycine betaine (3.96 g [dry weight] per mol) were similar to those with trimethylamine (4.11 g [dry weight] per mol). However, as glycine betaine is only partially demethylated, the yield per methyl group was significantly higher than with trimethylamine. If glycine betaine and trimethylamine are provided together, trimethylamine is demethylated to dimethyl- and methylamine with limited glycine betaine utilization. After trimethylamine is depleted, dimethylamine and glycine betaine are consumed rapidly, before methylamine. Glycine betaine extends the range of substrates that can be directly utilized by some methanogens, allowing them to gain energy from the substrate without the need for syntrophic partners.     

Interactions of Patella and macroalgae with settling Semibalanus balanoides (L.)

Biological interactions affecting densities of settling and newly-settled Semibalanus balanoides (L.) have been investigated by manipulative field experiments on the Isle of Man.The effects of sweeping by fucoid clumps of different species and Patella browsing have been compared on moderately-exposed shores. Patella allowed barnacle settlement by preventing growth of competing green algae, but reduced post-settlement densities. Small clumps of Fucus spiralis L., F. vesiculosus L, and F. serratus L. all reduced settlement considerably more so than limpets. F. serratus had the greatest sweeping effect.Interactions between macroalgae and Semibalanus balanoides have been investigated at all levels on sheltered shores and low down on more exposed shores. In the Fucus spiralis and F. vesiculosus zones, post-settlement numbers were higher than in adjacent areas where the canopy was removed. Barnacles did not settle readily in the Ascophyllum zone in either experimental or control areas. Settlement occurred in the upper part of the Fucus serratus zone in experimental areas where the canopy was removed but not in control areas. No settlement occurred in either treatment or control areas lower in the F. serratus zone. At all levels on the shore fucoid canopies seemed to reduce cyprid settlement, but the effect was greatest amongst F. serratus where there was total prevention. High on the shore the effect of enhanced post-settlement survival under the canopy outweighs reduction of cyprid settlement thus there are greater numbers in the controls. Competition with red algal turfs was shown to set the lower limit of the barnacle zone on a vertical pier face.     

Potential predation pressure of littoral mysids on herring (Clupea harengus membras L.) eggs and yolk-sac larvae

The predation potential of littoral mysid shrimps (Mysidacea) on Baltic herring (Clupea harengus membras L.) eggs and yolk-sac larvae was studied experimentally. The results showed that littoral mysids feed actively on both eggs and yolk-sac larvae. It was shown that Neomysis integer preys on eggs, which are not attached to the substrate. Alternative food (yolk-sac larvae or zooplankton) did not decrease feeding rate on eggs. Only gravel as a bottom material lowered the ingestion rate to nearly zero. The largest of the mysid species Praunus flexuosus ate yolk-sac larvae more than other mysids and most efficiently. Mysids switched to feed on eggs when larvae and eggs were offered simultaneously, thus predation focused on eggs. It is possible that hydrodynamic signals of moving larvae induced mysids to prey and eggs were easier prey to catch as well as more numerous. In addition egg size is optimal and the nutritive value (measured as C:N ratio) is better compared with larvae. The results indicate that mysids may have local effects on populations of Baltic herring by eating the early life stages, mostly eggs. Especially when large swarms of N. integer shoal in the spawning areas. However, the effect on recruitment of herring is still hard to evaluate.     

Blood group B-specific lectin of Plecoglossus altivelis (Ayu fish) eggs

A lectin that agglutinates human blood group B erythrocytes but not blood group A and O erythrocytes was isolated from eggs of Ayu sweet fish (Plecoglossus altivelis). The lectin also agglutinates Ehrlich ascites carcinoma cells but not rat ascites hepatoma AH109 or rat sarcoma 150 cells tested. The lectin agglutination was most effectively inhibited by monosaccharides with the first type of configuration, i.e., L-rhamnose, L-mannose and L-lyxose at a concentration of 0.03 mM. The lectin agglutination was moderately inhibited by monosaccharides with the second type of configuration, i.e., D-galactose, D-fucose and D-galacturonic acid at a concentration of 0.4 mM. However, the agglutination was not inhibited by various other monosaccharides and oligosaccharides that have other types of configuration. The basis for an apparent B-specific hemagglutination may be due to the steric similarity of the C₂ and C₄ of the galactosyl series, the B-specific determinant, and the L-rhamnosyl series, which are the best inhibitors of the lectin activity. The lectin was affinity purified on an L-rhamnosyl-Sepharose column and was characterized as a homogeneous low molecular weight protein (M_r 14 000) with an abundance of hydrophobic amino acids and dicarboxylic amino acid.     

The constancy and similarity of the amounts of free amino acids in inbred strains of Drosophila and outbred Calliphora

The composition of the free amino acids are compared in adults of two inbred strains of Drosophila subobscura and their hybrids, three inbred lines of Drosophila melanogaster, and in flies from a heterogeneous population of Calliphora erythrocephala. It appears that not only do the amounts of amino acid vary very little from fly to fly, but also very little between inbred lines. Furthermore, the relative amounts of the amino acids in Drosophila are similar to the relative amounts in the blowfly, Calliphora. This characteristic of invariant amounts of the free amino acids in these Diptera occurs in spite of the probably large numbers of genes affecting them.     

Copper toxicity and copper tolerance in Enteromorphacompressa (L.) Grev.

The responses of ship-fouling and non-fouling isolates of Enteromorpha compressa (L.) Grev. have been compared in media containing copper at 0.0?9.6 μmol · dm^?3. The responses of each isolate were found to vary, according to the conditions of the original habitat. Thus ship-fouling E. compressa was found to be tolerant of copper concentrations up to 9.6 μmol · dm^?3 showing a maintenance of all of the physiological processes studied during the present research (cell viability, net photosynthesis, intracellular K⁺ and dimethylsulphoniopropionate content). Non-fouling plant material showed symptoms of copper toxicity at all levels of copper from 1.8 μmol · dm^?3 to 9.6 μmol · dm^?3. Copper tolerance in ship-fouling E. compressa appears to be genetically determined, since the progeny from ship-fouling plants are also tolerant to copper concentrations within the range 1.8 to 9.6 μmol · dm^?3. The rate of accumulation of copper in ship-fouling thalli is, however, almost identical to that of non-fouling thalli, suggesting that tolerance may be due primarily to internal detoxification, rather than an exclusion mechanism.     

Comparison of sarcosine and methionine sulfoxide levels in symbiotic and aposymbiotic larvae of two sibling species,Sitophilus oryzae L. and S. zeamais mots. (Coleoptera: Curculionidae)

Sarcosine and methionine sulfoxide were investigated in several wild or laboratory-reared symbiotic and aposymbiotic strains of Sitophilus oryzae and S. zeamais. The amino acid composition of fourth-instar larvae indicated that a high level in sarcosine found together with a low level of methionine sulfoxide were biochemical characteristics of the aposymbiotic state in this genus. Nutritional experiments demonstrated that the synthesis of these two amino acids depended on dietary precursors. Since sarcosine and methionine sulfoxide are both methionine derivatives, it is therefore suggested that methionine metabolism in Sitophilus larvae might differ according to the presence or the absence of the symbiotic bacteria.     

l-Proline transport in Saccharomyces cerevisiae

Transport of l-proline into Saccharomyces cerevisiae K is mediated by two systems, one with a K_T of 31 μM and J_max of 40 nmol · s^?1 · (g dry wt.)^?1, the other with K_T > 2.5 mM and J_max of 150–165 nmol · s^?1 · (g dry wt.)^?1, The kinetic properties of the high-affinity system were studied in detail. It proved to be highly specific, the only potent competitive inhibitors being (i) l-proline and its analogs l-azetidine-2-carboxylic acid, sarcosine, d-proline and 3,4-dehydro-dl-proline, and (ii) l-alanine. The other amino acids tested behaved as noncompetitive inhibitors. The high-affinity system is active, has a sharp pH optimum at 5.8–5.9 and, in an Arrhenius plot, exhibits two inflection points at 15°C and 20–21°C. It is trans-inhibited by most amino acids (but probably only the natural substrates act in a trans-noncompetitive manner) and its activity depends to a considerable extent on growth conditions. In cells grown in a rich medium with yeast extract maximum activity is attained during the stationary phase, on a poor medium it is maximal during the early exponential phase. Some 50–60% of accumulated l-proline can leave cells in 90 min (and more if washing is done repeatedly), the efflux being insensitive to 0.5 mM 2,4-dinitrophenol and uranyl ions, to pH between 3 and 7.3, as well as to the presence of 10–100 mM unlabeled l-proline in the outside medium. Its rate and extent are increased by 1% d-glucose and by 10 μg nystatin per ml.     

Physical forces experienced by echinoid eggs in the oviduct during spawning: comparison of the geminate pair Echinometra vanbrunti and Echinometra lucunter

During spawning, eggs of echinoids are released from the gonad and traverse a narrow oviduct-gonopore complex before being released into the water surrounding the spawning female. As the eggs traverse the oviduct-gonopore complex, a velocity gradient develops within the fluid formed by the eggs. This velocity gradient imposes a shear stress on the eggs that ranges from a maximal value at the walls of the oviduct-gonopore complex and declines linearly to zero at the center of the complex. In addition to shear stress, the eggs of some echinoids also experience strain. Strain is imposed on the eggs in situations where the diameter of the egg is greater than the diameter of the oviduct-gonopore complex. Both shear stress and strain have the potential to damage echinoid eggs during spawning and are likely selective pressures acting on the physical properties of protective extracellular layers, which surround the eggs of these organisms. The amounts of shear stress and strain experienced by eggs of a geminate pair of echinoids, Echinometra vanbrunti and E. lucunter, are calculated. Calculations of shear stress based on the mean spawning rates and dimensions of the oviduct-gonopore complexes of specimens collected during this study ranged up to 30 Pa for E. vanbrunti and up to 17 Pa for E. lucunter. To obtain conservative estimates of shear stress, these calculations were repeated incorporating a spawning rate that was reduced by one order of magnitude below the mean rate measured for both species. These calculations yielded shear stresses that ranged up to 13 and 6 Pa for E. vanbrunti and E. lucunter, respectively. The diameter of the oviduct-gonopore complex of echinoids increases linearly with the diameter of the tests of the adults. Because the diameter of the oviduct-gonopore complex influences the amount of shear stress experienced by eggs of echinoids, shear stress calculations were repeated incorporating the full range of potential diameters of the oviduct-gonopore complexes from data in the literature. Using the mean spawning rates obtained from each species, the amount of shear stress experienced by eggs ranged up to 32 Pa for E. vanbrunti and up to 398 Pa for E. lucunter. When the mean spawning rates were reduced by one order of magnitude, the amount of shear stress experienced by E. vanbrunti eggs ranged up to 14 Pa and up to 140 Pa for the eggs of E. lucunter. The eggs of E. vanbrunti do not experience strain during spawning because the diameter of the its eggs is smaller than the diameter of its oviduct-gonopore complex at all stages of adult growth. In contrast, the diameter of the eggs of E. lucunter is larger than the diameter of the oviduct-gonopore complex at small adult sizes and the eggs of this species experience true strains ranging up to 1.2. These results indicate that there are substantial differences in the amounts of physical forces that the eggs of echinoids experience during spawning both within species at different stages of adult growth and between species. Different amounts of shear stress and strain experienced by eggs among echinoid species may select for differences in the mechanical properties of protective extracellular layers that surround them.     

三角鲂和长春鳊肌肉营养成分分析与品质评价

用常规方法测定、分析了三角鲂(Megalobrama tarminalis)和长春鳊(Parabramis pekinensis肌肉中营养成分组成与含量.结果显示,三角鲂肌肉蛋白质、脂肪含量分别为18.19％和3.06％,长春鳊肌肉蛋白质、脂肪含量分别为19.38％和2.89％.三角鲂和长春鳊肌肉中均检测出18种氨基酸,其中包括了8种人体必需氨基酸.三角鲂肌肉中氨基酸总量为76.27％,其中,8种人体必需氨基酸含量为32.17％,占氨基酸总量的42.18％;长春鳊肌肉中氨基酸总量为77.60％,其中,8种人体必需氨基酸含量为31.70％,占氨基酸总量的40.85％.必需氨基酸的构成比例基本符合FAO/WHO的标准.三角鲂肌肉中限制性氨基酸主要为甲硫氨酸加胱氨酸,必需氨基酸指数为63.55,4种呈味氨基酸为氨基酸总量的32.81％;长春鳊肌肉中限制性氨基酸主要为色氨酸,必需氨基酸指数为66.81,4种呈味氨基酸为氨基酸总量的33.80％.脂肪酸中二十碳五烯酸(EPA)与二十二碳六烯酸(DHA)含量均较高,三角鲂为7.96％,长春鳊为3.11％.矿物元素比值合理.以上分析表明,三角鲂和长春鳊均为营养价值、经济价值都较高的优质鱼类,相比而言,三角鲂肌肉脂肪、脂肪酸含量和质量更优,而长春鳊肌肉在蛋白质、氨基酸组成与含量方面更优.     

Neutral amino acid transport in Leishmania promastigotes

Neutral amino acid transport was investigated in Leishmania promastigotes. Proline and alanine transport occur against their concentration gradient although there is a very rapid (40% at 30 min) conversion of proline to alanine. Uptake of these amino acids occurs by a sodium-independent route which is completely eliminated by addition of CCCP or KCN. $\text{K}{}_{\mathrm{<mtext>m</mtext>}}$ values for proline and alanine are 80 μM and 63 μM with $\text{V}{}_{\mathrm{<mtext>max</mtext>}}$ values of 6.4 and 7.2 nmol/min per mg dry weight, respectively. Countertransport of proline, alanine and phenylalanine was measured by loading the cells with a variety of neutral amino acids and proline analogs, followed by CCCP addition. The effect of aminooxyacetic acid, an inhibitor of alanine aminotransferase (EC 2.6.1.2), on proline and alanine countertransport was also examined. The results obtained are consistent with the presence of at least two systems for neutral amino acid transport in Leishmania promastigotes.     

Utilizable surface nutrients on Heliothis zea available for growth of Beauveria bassiana

Amino acids and glucosamine are present on the surface of Heliothis zea larvae. The amino acid compositions vary among instars and with time following completion of the gross molting process. Larvae collected from ears of corn have many surface amino acids. All amino acid combinations found on larval surfaces are sufficient for initiation of germination and growth by Beauveria bassiana. Amines and peptides are also present; these do not inhibit germination of B. bassiana or Aspergillus niger.