Water conservation and protein metabolism in northern elephant seal pups during the postweaning fast

Urine production and N output were monitored in northern elephant seal (Mirounga angustirostris) pups progressing through 10 weeks of a natural postweaning fast. Urine output declind by 84% (to 69±12 ml·day^–1) at 10 weeks (P<0.05). Glomerular filtration rate at 10 weeks was 51% of the 67±3 ml serum·min^–1 observed during week 1 (P<0.05). Urine N excretion fell by 69% to 1.2±0.17 g·day^–1, while urinary concentration increased (P<0.05). Serum urea declined from an initial 11 mmol·1^–1 to 5–7 mmol·1^–1 by 5 weeks. The fall in urinary N loss (and thus amino acid oxidation) was concomitant with depressed metabolic rate. Therefore, protein contributed little toward meeting energy demands (i.e., <4% of average metabolic rate) throughout fasting. These data indicate that fasting pups improve water conservation and minimize protein catabolism during prolonged natural fasts without an exogenous source of water.Abbreviations AA amino acid(s) - AMR average metabolic rate - ANOVA one-way analysis of variance - BMR basal metabolic rate - BUN blood urea nitrogen - EP end product - EWL evaporative water loss - [Gr]_s serum creatinine concentration - GFR glomerular filtration rate - LBM lean body mass - LML Long Marine Laboratory - MR metabolic rate - NEFA non-esterified fatty acids - RMR resting metabolic rate - TCA tricarboxylic acid - U:C ulinary urea: creatinine concentration ratio     

In vitro culture of Cucumis sativus L. V. Stabilizing effect of glycine on leaf protoplasts

A method for leaf mesophyll protoplast isolation and plant regeneration of cucumber (Cucumis sativus L.) is described. Using an isolation solution complemented with 0.1 M glycine, 8.2·10⁶ viable protoplasts were isolated from 1 g of fresh leaves. The effect of the growth substances indole-3-acetic acid, naphthalene acetic acid, 2,4,-dichlorophenoxy acetic acid, 6-benzylaminopurine, 2-isopentenyladenine and kinetin at concentrations from 0.5 to 5 mg·1^–1 was studied using the multi-hanging drop technique. The optimal growth substance combination, namely 5 mg·1^–1 naphthalene acetic acid and 3 mg·1^–1 2-isopentenyladenine, together with agarose medium in a so-called bead culture resulted in a plating efficiency of 21%. Some of the colonies obtained regenerated to plantlets which developed to plants.Abbreviations BAP 6-benzylaminopurine - 2,4-D 2,4-dichlorophenoxy acetic acid - IAA indole-3-acetic acid - 2iP 2-isopentenyladenine - MS Murashige and Skoog - NAA naphthalene acetic acid     

Effect of growth rate on the eicosapentaenoic acid and docosahexaenoic acid content of Isochrysis galbana in chemostat culture

An isolate of Isochrysis galbana rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) has been grown as a chemostat culture at 20° C and pH 8.00 controlled by CO₂ injection. From a low dilution rate (D) of 0.0024 h^–1 to 0.0377 h^–1, close to maximum growth, a decrease in EPA content from 5.21% dry weight (d.w.) to 2.80% d.w. was observed, although the percentage of EPA in the total fatty acids increased. Lipids were fractionated, EPA being the major fatty acid found in the glycolipid fraction, whereas in the neutral lipid fraction were mainly palmitic and palmitoleic acids. At the same time, the biomass concentration also decreased from 1015 mg·l^–1 to 202 mg·l^–1 over the range of Ds mentioned. Nonetheless, EPA productivity had a maximum value of 15.26 mg·l^–1·day^–1 at D=0.0208 h^–1.Correspondence to: E. Molina Grima     

Urea hydrolysis and transformations in coastal dune sands and soil

Summary Urea hydrolysis was studied in samples taken from a coastal sand dune succession, from uncolonized sand; the rhizosphere ofAmmophila arenaria and soil from the mature dune. Comparisons were made with urea hydrolysis in a fertile loam soil. Urea was hydrolyzed in all sand and soil samples, with complete hydrolysis occurring after 6 and 3 weeks in the rhizosphere sand and dune soil compared with only 4 days in the fertile loam. A third of the added urea, however, was still present in the uncolonized sand samples 6 weeks after the beginning of the incubation period. Urea hydrolysis broadly correlated with urease activity.The liberated NH ₄ ⁺ was oxidized to NO ₃ ^– –N in all samples. Urea stimulated the release of N from native organic matter in the two soils, but not sands, due presumably to the low organic matter content of the latter. Nitrite accumulated in the dune sands and soil, but not in the fertile loam.Although N-Serve (Nitrapyrin) had no effect on urea hydrolysis in any of the treated samples, it inhibited the nitrification of released NH ₄ ⁺ –N. The relevance of these findings to the use of urea as a fertilizer to improve plant growth and dune stabilization is commented upon.     

Nutritional and hormonal requirements of Ginkgo biloba embryo-derived callus and suspension cell culture

Calli were obtained from Ginkgo biloba embryos grown on Murashige and Skoog (MS) medium. The G. biloba cells could grow on either MS or Gamborg B5 mineral salt medium supplemented with sucrose (3% and 2%, respectively) and naphthaleneacetic acid (NAA) and kinetin (K) in concentrations ranging from 0.1 to 2.0 mg·L^–1. Best growth and maintenance of callus cultures were achieved using MS medium supplemented with 2 mg·L^–1 NAA and 1 mg·L^–1 K (N₂K₁MS). Light was required to maintain healthy growth of the callus tissue.In both MS and B5 based media, sucrose was hydrolyzed extracellularly before being taken up by Ginkgo cell suspension cultures. Specific growth rates of 0.13 d^–1 and 0.08 d^–1 were obtained in MS medium supplemented with 1 mg·L^–1 NAA, 0.1 mg·L^–1 K and 30 g·L^–1 sucrose (N₁K_0.1MS) and B5 medium supplemented with the same growth regulator regime and 20 g·L^–1 sucrose (N₁K_0.1B5) respectively. Complete phosphate and ammonium uptake was observed in 11 days when cultured in MS medium and 10 days and 4 days respectively when cultured in B5 medium. During the culture, G. biloba cells consumed only 64% and 29% of the nitrate content of N₁K_0.1MS and N₁K_0.1B5 media respectively. Maximum dry biomass concentrations were 13.4 g·L^–1 and 7.9 g·L^–1, and yields on carbohydrate were 0.39 and 0.45 in N₁K_0.1MS and N₁K_0.1B5 media respectively. The better performance of MS cultures came from the higher sucrose and nitrogen salts concentrations of this medium.Abbreviations B5 Gamborg mineral salt medium - d.w. Dry weight - K Kinetin - MS Murashige and Skoog mineral salt medium - N or NAA Naphthaleneacetic acid - N_iK_jMS i and j are the respective concentrations (mg·L^–1) of NAA and K - n Number of experimental points - r Linear regression correlation coefficient     

The nitrogen cycle in lodgepole pine forests,southeastern Wyoming

Storage and flux of nitrogen were studied in several contrasting lodgepole pine (Pinus contorta spp.latifolia) forests in southeastern Wyoming. The mineral soil contained most of the N in these ecosystems (range of 315–860 g · m^–2), with aboveground detritus (37.5–48.8g · m^–2) and living biomass (19.5–24.0 g · m^–2) storing much smaller amounts. About 60–70% of the total N in vegetation was aboveground, and N concentrations in plant tissues were unusually low (foliage = 0.7% N), as were N input via wet precipitation (0.25 g · m^–2 · yr^–1), and biological fixation of atmospheric N (<0.03 g · m^–2 · yr^–1, except locally in some stands at low elevations where symbiotic fixation by the leguminous herbLupinus argenteus probably exceeded 0.1 g · m^–2 · yr^–1).Because of low concentrations in litterfall and limited opportunity for leaching, N accumulated in decaying leaves for 6–7 yr following leaf fall. This process represented an annual flux of about 0.5g · m^–2 to the 01 horizon. Only 20% of this flux was provided by throughfall, with the remaining 0.4g · m^–2 · yr^–1 apparently added from layers below. Low mineralization and small amounts of N uptake from the 02 are likely because of minimal rooting in the forest floor (as defined herein) and negligible mineral N (< 0.05 mg · L^–1) in 02 leachate. A critical transport process was solubilization of organic N, mostly fulvic acids. Most of the organic N from the forest floor was retained within the major tree rooting zone (0–40 cm), and mineralization of soil organic N provided NH₄ for tree uptake. Nitrate was at trace levels in soil solutions, and a long lag in nitrification was always observed under disturbed conditions. Total root nitrogen uptake was calculated to be 1.25 gN · m^–2 · yr^–1 with estimated root turnover of 0.37-gN · m^–2 · yr^–1, and the soil horizons appeared to be nearly in balance with respect to N. The high demand for mineralized N and the precipitation of fulvic acid in the mineral soil resulted in minimal deep leaching in most stands (< 0.02 g · m^–2 · yr^–1). These forests provide an extreme example of nitrogen behavior in dry, infertile forests.     

Production of 4-decanolide by semicontinuous fermentation of Tyromyces sambuceus

Summary Tyromyces sambuceus was cultivated in a stirred tank reactor under semicontinuous conditions for 70 days. Over longer periods of time in submersion, values of 220 and 330 mg·L^–1 of 4-decanolide could be maintained; after dispersion of the headspace mycelia, a single peak product concentration of 880 mg·L^–1 was attained. The productivity was subject to large variations, peak values were 18 and 11 mg·L^–1·h^–1. Depending on the culture conditions, specific growth rates of up to 0.05 h^–1 were reached.     

Influence of water activity on Streptococcus diacetylactis metabolism

During the cheese-making process, water activity (a_w) is one of the essential environmental parameters acting on bacterial growth and metabolic pathways. The influence of a_w on Streptococcus diacetylactis growth and lactic acid production was studied. The specific growth rate was linearly related to water availability in the milk medium. The cell behaviour was quite different above and below a_w=0.95, which can be considered a limiting value. Below this value, the lactic acid production reached 1.4–6.1 mg·g^–1, whereas the specific productivity was 2.0–2.6 mg·10^–10 cells·h^–1. Changes in the consumption of lactose and amino acids during the different growth phases was completely modified by decreasing the water availability in the medium. Correspondence to: N. Cochet     

Secretion by the mandibular gland of the red kangaroo (Macropus rufus) during isoprenaline infusion

Summary Intracarotid infusion of isoprenaline, either alone or in combination with acetylcholine infusion was used to stimulate salivation by the mandibular glands of anaesthetized red kangaroos. Isoprenaline alone (0.20–1.25 mol·kg^–1·min^–1) elicited flow rates ranging from 0.014 to 0.239 ml·min^–1 (1.21–28.1 l·g gland^–1·min^–1). Salivary concentrations of sodium, chloride, phosphate and urea were negatively correlated with flow, whereas potassium, calcium, magnesium, hydrogen ion, bicarbonate, protein, and osmolality were poorly correlated with flow. Relative to cholinergic saliva produced at equivalent flow rates, isoprenaline-evoked saliva had higher osmolality, saliva/plasma urea ratios and concentrations of protein, potassium, magnesium, bicarbonate, and phosphate, but lower sodium, chloride and hydrogen ion levels. At a steady salivary flow (0.5 ml·min^–1), superimposition of isoprenaline infusion (0.15 mol·kg^–1·min^–1) on a pre-existing acetylcholine infusion reduced the rate of acetylcholine administration necessary to maintain flow, increased osmolality and the concentrations of protein, urea, potassium, calcium, magnesium, bicarbonate and phosphate and decreased sodium, chloride and hydrogen ion in the saliva. Salivary amylase activity was low and highly variable and the amylase activity/protein ratio fell substantially during isoprenaline stimulation. These results support the conclusion that the enzyme is of extrinsic origin. The response of the kangaroo mandibular gland to isoprenaline stimulation was very similar to that reported for rat mandibular gland, suggesting that the same ion transport phenomena underlie mandibular secretion in both species and probably in therian mammals generally.     

Seed potato (Solanum tuberosum L.) yield and tuber number increase after foliar applications of cytokinins and gibberellic acid under field and glasshouse conditions

The purpose of these experiments is to determine the effects of foliar applications of benzylaminopurine (BAP) and gibberellic acid (GA) on tuber number production of seed potatoes. In field experiments conducted during 1989/90 cv. Mailén was used and BAP, 50 mg·l^–1 was foliarly applied at (1) tuber initiation, 36 days after emergence (DAE); (2) 54 DAE; and, (3) 64 DAE. Under glasshouse conditions, in 1991/92 cv. Spunta was used and BAP 50 mg·l^–1+GA 50 mg·l^–1 were applied 30 and 37 days after planting/transplanting. In 1992 cv. Huinkul, Kennebec and Spunta were used and BAP 50 mg·l^–1+GA 50 mg·l^–1 and Biozyme (Techic SA), a commercial product with auxin (IAA, 32.2 mg·l^–1), gibberellic acid (GA₃, 32.2 mg·l^–1) and cytokinins (zeatin, 83.2 mg·l^–1) at 5 ml·l^–1 were applied. In cv. Mailén, a higher tuber number in the seed fraction (<80 g) was found when BAP was applied at each of the three crop stages, while applications 54 and 62 DAE also increased tuber number in the 80–400 g fraction. As a result of BAP applications, tuber yield was also significantly increased. In the glasshouse experiments, cv. Spunta showed a significant increase in minituber production in 3 out of 4 cases, either if the mother plant came from in vitro generated plantlets or minitubers, or if GA + BAP or Biozyme was applied. It can be concluded that the use of these PGRs under both field and glasshouse conditions in cvs. Mailén and Spunta can result in increased tuber number in the seed fraction.     

High efficiency styrene biodegradation in a biphasic organic/water continuous reactor

Styrene was degraded as sole source of carbon and energy by a selected bacterial community in a two-phase aqueous-organic medium (80%:20%, vol/vol). Silicone oil was used to solubilize styrene, which is sparingly soluble in water and to prevent its toxicity toward microorganisms. Preliminary studies with the mixed population in batch cultures indicate that the specific activity and the maximum growth rate at optimal 3H 6.0 were 46 mg·g^–1·h^–1 and 0.15 h^–1, respectively. In pH-regulated chemostat cultures, styrene was degraded at dilution rates ranging from 0.05 to 0.20 h^–1. Kinetic parameters and the proportion of each strain in the mixed culture were followed. At 0.20 h^–1, only one strain as compared to four initially present, remained in the medium. This strain Pseudomonas aeruginosa, degrades styrene with a specific activity of 293 mg·g^–1·h^–1. Such results could lead to industrial treatment of waste gas or water polluted with styrene. Correspondence to: J,-M. Lebeault     

Induction of somatic embryogenesis and caulogenesis from cotyledon and leaf protoplast-derived colonies of melon (Cucumis melo L.)

Summary A procedure leading to the regeneration of whole plants from protoplasts of melon is described. Protoplasts were isolated from cotyledons and leaves of plants grown in vitro. After 14 days of culture, average viability and division rates were respectively 60% and 30% for the two organs, considering total initial protoplasts plated. The manipulation of the exogenous auxin / cytokinin balance in regeneration media enabled to direct morphogenesis towards somatic embryogenesis (1 mg·l^–1 2,4-dichlorophenoxyacetic acid and 0.1 mg·l^–1 6-benzylaminopurine) or caulogenesis (0.5 mg·l^–1 6-benzylaminopurine and 0.5 mg·l^–1 kinetin). Contrary to division ability, regeneration capacity was genotype-dependent under our conditions, but the two organs expressed similar division and regeneration capacities. Maltose was superior to sucrose for the development of caulogenic nodules into buds. Some plants were transplanted to soil, where they appeared to be fertile and produced seeds.Abbreviations BAP 6-benzylaminopurine - CPW Cell and Protoplast Washing medium - KIN kinetin - MES 2-(N-morpholino) ethanesulfonic acid - MS Murashige and Skoog (1962) - NAA 1 — naphthaleneacetic acid - PAS H (staining), Periodic Acid-Schiff / Hematoxylin - 2,4-D 2,4-dichlorophenoxyacetic acid     

Adaptation of renal function to hypotonic medium in the winter flounder (Pseudopleuronectes americanus)

Summary The kidneys of winter flounders transferred to hypotonic medium were investigated for glomerular and tubular handling of fluid and electrolytes and for the urinary excretion of proteins. Media were sea water (925 mosm·kg^–1) and brackish water (70 mosm·kg^–1).In sea water, the urine was hypertonic to the plasma in 7 fish of this study. Urine flow rate was correlated with the GFR. After adaptation to brackish water a delay of 1 to 3 days was observed until the kidneys switched from fluid retention to the excretion of large amounts of dilute urine. GFR and urine flow rate were increased from 0.61±0.08 to 1.58±0.29 ml·h^–1·kg^–1 and from 0.14±0.02 to 0.68±0.08 ml·h^–1·kg^–1, respectively . With increased filtered load the tubular reabsorption of fluid decreased from 74±2.4% to 45±11.2%. The excretion rates of sodium and potassium were increased due to decreased fractional sodium and potassium reabsorption. The urinary excretion of divalent cations, however, was reduced because the net tubular reabsorption of calcium was increased and the net secretion of magnesium was diminished.Both the urinary total protein concentration and the protein pattern showed no significant change, but the rate of protein excretion was increased from 0.21±0.04 to 0.60±0.05 mg·h^–1·kg^–1. The comparison of protein patterns obtained from urine and serum samples revealed that high molecular weight (HMW) proteins prevail in the serum whereas low molecular weight (LMW) proteins dominate in the urine. The diminished quantity of the HMW-protein fraction in the urine thus may reflect size selectivity of the glomerular filtration barrier for serum proteins also in the winter flounder.Abbreviations BW brackish water - SW sea water - GFR glomerular filtration rate - HMW heigh molecular weight - LMW low molecular weight     

Production of ψ-linolenic acid by the fungus Mucor rouxii on cheap nitrogen and carbon sources

Summary The production of -linolenic acid (GLA) by the fungus Mucor rouxii CBS 416.77 was studied on low budget nitrogen and carbon sources, i.e. rape meal, cocos expeller and two types of yeast extract (nitrogen sources), and starch, starch hydrolysate, beet molasses and cocos expeller (carbon sources). As references, Difco yeast extract and glucose were used. In flask cultivations the three yeast extracts were fully interchangeable, while the Difco yeast extract (the most expensive of those tested) gave a higher productivity of GLA in fermentor cultures (14 mg·l^–1·h^–1). The yield of lipids and GLA were increased in the order yeast extract < rape meal < cocos expeller. Thus the amount of lipid increased from 0.56 to 2.8 g·l^–1, and that of GLA from 0.15 to 0.33 g·l^–1. Use of beet molasses or cocos expeller as carbon sources gave poor growth. Starch and starch hydrolysate resulted in better productivity of GLA than glucose (4.7 and 4.9 compared to 3.4 mg·l^–1·h^–1). Offsprint requests to: A.-M. Lindberg     

(4S)-4-amino-5,6-heptadienoic acid (MDL 72483): A potent anticonvulsant GABA-T inhibitor

(4S)-4-Amino-5,6-heptadienoic acid ((S)--allenyl-GABA; MDL 72483) is a potent inactivator of brain GABA-T in mice; (ED₅₀ (i.p.)=60 mg·kg^–1; ED₅₀ (oral)=70 mg·kg^–1). Its anticonvulsant effects against 3-mercaptopropionic acid (MPA)-induced seizures in mice is related to the elevation of whole brain GABA concentrations: The mentioned doses of MDL 72483 which cause a decrease of GABA-T activity by 50%, produce within 5 h after dosing an increase of GABA concentration by about 3 mol·g^–1, and protect 50% of the mice against seizures in this model of presynaptic GABA deficit. When given orally MDL 72483 is about five times more potent than vigabatrin ((4R/S)-4-amino-5-hexenoic acid) a known antiepileptic GABA-T inhibitor. Complete protection was achieved with a dose of 150 mg·kg^–1. Similar to vigabatrin, MDL 72483 does not protect significantly against metrazol-induced convulsions. However, at a dose of 300 mg·kg^–1, the time elapsing between metrazol administration and onset of convulsions was prolonged by a factor of 3.4. Oral administration of MDL 72483 for up to 19 days at a daily dose of 91–96 mg·kg^–1 did not produce any obvious behavioral changes in mice, nor was the ED₅₀ of the drug in MPA-seizure tests significantly altered by the pretreatment. These observations indicate that MDL 72483 is a promising drug for the treatment of certain epilepsies.Special issue dedicated to Dr. Eugene Roberts.     

The γ-irradiation of aqueous solutions of urea. Implications for chemical evolution

0.05 mole dm^–3, O₂-free aqueous solutions of urea were studies after receiving various doses of⁶⁰Co gamma rays (0.14–600 kGy). Urea was found to be relatively stable under radiation; its radiation chemical yield of decomposition was 0.47. Hydrogen (G=0.50), carbon dioxide (G=0.44), ammonia (G=0.22), oxalic acid (G=0.0054), malonic acid (G=0.000064) and three unidentified oligomers were found to be the main radiolytic products. The origin of these products is explained by free radical reactions initiated by the transients from water radiolysis (H·,·OH,e _aq ^– ).     

Organic reduction of tapioca wastewaters using modified RBC

A modified Rotating Biological Contactor (RBC) was used for the treatability studies of synthetic tapioca wastewaters. The RBC used was a four stage laboratory model and the discs were modified by attaching porous nechlon sheets to enhance biofilm area. Synthetic tapioca wastewaters were prepared with influent concentrations from 927 to 3600 mg/l of COD. Three hydraulic loads were used in the range of 0.03 to 0.09 m³·m^–2·d^–1 and the organic loads used were in the range of 28 to 306 g COD· m^–2·d^–1. The percentage COD removal were in the range from 97.4 to 68. RBC was operated at a rotating speed of 18 rpm which was found to be the optimal rotating speed. Biokinetic coefficients based on Kornegay and Hudson models were obtained using linear analysis. Also, a mathematical model was proposed using regression analysis.List of Symbols A m² total surface area of discs - d m active depth of microbial film onany rotating disc - K _s mg ·l^–1 saturation constant - P mg·m^–2·^–1 area capacity - Q l·d^–1 hydraulic flow rate - q m³·m^–2·d^–1 hydraulic loading rate - S ₀ mg·l^–1 influent substrate concentration - S _e mg·l^–1 effluent substrate concentration - w rpm rotational speed - V m³ volume of the reactor - X _f mg·l^–1 active biomass per unit volume ofattached growth - X _s mg·l^–1 active biomass per unit volume ofsuspended growth - X mg·l^–1 active biomass per unit volume - Y _s yield coefficient for attachedgrowth - Y _A yield coefficient for suspendedgrowth - Y yield coefficient, mass of biomass/mass of substrate removed Greek Symbols hr mean hydraulic detention time - (_max)_A d^–1 maximum specific growth rate forattached growth - (_max)_s d^–1 maximum specific growth rate forsuspended growth - _max d^–1 maximum specific growth rate - d^–1 specific growth rate - _v mg·l^–1·hr^–1 maximum volumetric substrateutilization rate coefficient     

Nitrogen fixation in subarctic streams influenced by beaver (Castor canadensis)

Nitrogen fixation was measured in four subarctic streams substantially modified by beaver (Castor canadensis) in Quebec. Acetylene-ethylene (C₂H₂ C₂H₄) reduction techniques were used during the 1982 ice-free period (May–October) to estimate nitrogen fixation by microorganisms colonizing wood and sediment. Mean seasonal fixation rates were low and patchy, ranging from zero to 2.3 × 10^–3 µmol C₂H₄ · cm^–2 · h^–1 for wood, and from zero to 7.0 × 10^–3 µmol C₂H₄ · g AFDM^–1 · h^–1 for sediment; 77% of all wood and 63% of all sediment measurements showed no C₂H₂ reduction. Nonparametric statistical tests were unable to show a significant difference (p > 0.05) in C₂H₂ reduction rates between or within sites for wood species or by sediment depth.Nitrogen contributed by microorganisms colonizing wood in riffles of beaver influenced watersheds was small (e.g., 0.207 g N · m^–2 · y^–1) but greater than that for wood in beaver ponds (e.g., 0.008 g N · m^–2 · y^–1) or for streams without beaver (e.g., 0.003 g N · m^–2 · y^–1). Although mass specific nitrogen fixation rates did not change significantly as beaver transform riffles into ponds, the nitrogen fixed by organisms colonizing sediment in pond areas (e.g., 5.1 g N · m^–2 · y^–1) was greater than that in riffles (e.g., 0.42 g N · m^–2 · y^–1). The annual nitrogen contribution is proportional to the amount of sediment available for microbial colonization. We estimate that total nitrogen accumulation in sediment, per unit area, is enhanced 9 to 44 fold by beaver damming a section of stream.     

Calcium-supported calpain degradation rates for cardiac myofibrils in diabetes

Objective The purpose was to investigate the calcium required for calpain-mediated degradation of selected cardiac myofibril proteins modified by diabetes, sulfhydryl (SH) and hydrophobic reagents.Methods: After 20 weeks of streptozotocin-induced (55 mg·kg^–1) diabetes, calcium sensitive calpain (1.5 U·ml^–1) degradation rates of purified cardiac myofibrillar proteins (1 mg·ml^–1) were measured,in vitro, and compared to degradation rates for N-ethylmaleimide (NEM) and 2-ptoluidinylnapthalene-6-sulfonate (TNS) treated samples.Results: Diabetes (blood glucose of 550±32 mg·dl^–1) reduced the yield of purified myofibrillar protein with minimal change in fibril protein composition. Total SH group reactivities (nmol·mg^–130min) were 220±21, 163±17 and 156±24 for control, diabetic and NEM-treated (0.5mM) myofibrils (p0.05). Calpain degradation rates were faster for all diabetic and SH modified myofibrillar proteins (p0.05), with a 45 and 35% reduction in the pCa₅₀ for a 37 kDa protein of diabetic and NEM-treated fibril complexes. For control myofibrils, both 100 and 200 uM TNS, reduced calpain degradation rates to a similar extent for all substrate proteins. In contrast, diabetic and NEM-treated samples showed a further reduction in calpain degradation rates with increasing TNS from 100 to 200 divi.Conclusion Our results support the hypothesis that in diabetes the calcium requirements for calpain degradation rates are reduced and dependent upon sulfhydryl group status and Ca²⁺-induced hydrophobic interactions, implicating a 37 kDa myofbillar-complexed protein.     

Growth and hyoscyamine production of ‘hairy root’ cultures of Datura stramonium in a modified stirred tank reactor

Summary The growth and hyoscyamine production of transformed roots of Datura stramonium have been examined in a modified 14-1 stirred tank reactor in both batch and continuous fermentations on media containing half or full strength Gamborg's B5 salts and at three different temperatures. Under a range of conditions, roots grown on half strength B5 salts with 3% w/v sucrose had a higher dry matter content (up to 8.3% w/w) and a higher hyoscyamine content (up to 0.52 mg·g^–1 wet weight) than roots grown on full strength B5 salts with the same level of sucrose (up to 4.6% w/w dry matter and up to 0.33 mg hyoscyamine g^–1 wet weight). Growth at 30°C was initially faster than at either 25°C or 35°C and by day 12, the drained weight of roots in the fermentor at 30°C was about fourfold greater than at 25°C and twice that at 35°C. The ultimate hyoscyamine levels attained (approximately 0.5 mg·g^–1 wet weight) were similar at both 25°C and 30°C but some 40% lower at 35°C. Final packing densities of 70% w/v were achieved for roots after 37 days growth at 25°C and the highest production rate of 8.2 mg hyoscyamine l^–1 per day was obtained for roots grown at 30°C. In continuous fermentation at 25°C, the release of hyoscyamine into the culture medium was low (less than 0.5% w/w of the total) but was up to sevenfold higher in fermentors operated at 30°C or 35°C. Offprint requests to: M. G. Hilton