Time-dependent cadmium-neurotoxicity in rat brain synaptosomal plasma membranes

• 1.1. The modulation of lipid dynamics and lipid protein interactions were studied in rat brain synaptosomal plasma membranes (SPM) up to 24 hr after exposure to cadmium (Cd).
• 2.2. The activity of acetylcholinesterase and adenylate cyclase showed a considerable decrease after 6 hr of Cd exposure, followed by a progressive increase up to 24 hr.
• 3.3. SPM chemiluminescence showed a maximum decrease at 12 hr, demonstrating a considerable increase in lipid peroxidation.
• 4.4. SPM of Cd-exposed animals showed a statistical significant increase in fluorescence anisotropy parameter [(r₀/r) — 1]⁻¹ at 18 and 24 hr compared to SPM of the control, indicating a decrease of membrane fluidity.

     

Sodium transport in red blood cells of lamprey LAmpetra fluviatilis

• 1.1. Unidirectional Na⁺ influx in lamprey red blood cells was determined using ²²Na as a tracer.
• 2.2. Total Na⁺ uptake and amiloride-inhibitable Na⁺ influx increased in a saturable fashion as a function of external Na⁺ concentration (Na_e).
• 3.3. At 141 mM Na_e, the average value of net Na⁺ influx was 13 ± 1.1 and the amiloride-sensitive Na⁺ influx was 5.3±1.1 mmol/l cells per hr (±SE).
• 4.4. The amiloride-sensitive component of Na⁺ influx was significantly activated by 10⁻⁵ M isoproterenol, by 2 × 10⁻⁵ M DNP, and by cell shrinkage.
• 5.5. Furosemide (1 mM) had no effect on the Na⁺ transport in red cells.
• 6.6. The residual amiloride-insensitive component of Na⁺ transport was a linear function of Na_e in the range of 5–141 mM. This transport seems to be accounted for by simple diffusion.

     

Influence of dietary sources of fat on lipid synthesis in mink (Mustela vison) mammary tissue

• 1.1. The fatty acid composition of the triglyceride fraction of mink milk sampled during mid-lactation (day 28 post partum) from two nursing mink was compared to that of plasma samples and to the fatty acid composition of the feed rations used.
• 2.2. Chemical analysis of the triglyceride composition of mink milk demonstrated only minute concentrations of fatty acids with a chain length below C₁₄.
• 3.3. The saturated C_16:0- and C_18:0-unit fatty acids in mink milk made up for 24–40% of the total amount of fatty acids extracted, the remainder being represented by mono and polyunsaturated long-chain (C₁₆-C₂₄) fatty acids.
• 4.4. Preliminary in vitro experiments proved the incorporation of¹⁴C-labelled glucose, acetate or palmitate into triacylglycerols in cultures of mink mammary tissue to be linear for at least 2 hr.
• 5.5. The in vitro capacity for de novo fatty acid synthesis in mink mammary tissue using 14C-labelled glucose or acetate was low, i.e. ranging from 0.096–0.109 nmol/g (fresh tissue)/min, and amounted to only about 5% of that obtained in the case of [¹⁴C]palmitic acid incubation.
• 6.6. Following ¹⁴C-labeIled acetic or palmitic acid incubation of mink mammary tissue neither desaturation nor chain elongation was observed.
• 7.7. In response to long-term feeding on rations with two different sources of animal fat (F = fish oil or L = lard) the influence of compositional changes in dietary neutral lipids on the fatty acid composition of the lipids of mink milk is discussed.

     

Comparative nuclear magnetic resonance studies of diffusional water permeability of red blood cells from different species. V—Rabbit (Oryctolagus Cuniculus)

• 1.1. The diffusional water permeability (P_d) of rabbit red blood cell (RBC) membrane has been monitored by a doping nuclear magnetic resonance (NMR) technique on control cells and following inhibition with p-chloromercuribenzene sulfonate (PCMBS).
• 2.2. The values of P_d were around 6.3 × 10⁻³ cm/sec at 15°C, 7.0 × 10⁻³cm/sec at 20°C, 8.0 × 10⁻³ cm/sec at 25°C, 9.1 × 10⁻³ cm/sec at 30°C and10.7 × 10⁻³ cm/sec at 37°C.
• 3.3. Systematic studies on the effects of PCMBS on water diffusion indicated that the maximal inhibition was reached in 15 min at 37°C with 0.5 mM PCMBS.
• 4.4. The values of maximal inhibition were around 71–74% at all temperatures.
• 5.5. The basal permeability to water was estimated as 1.6 × 10⁻³cm/sec at 15°C, 2.0 × 10⁻³cm/sec at 20°C, 2.4 × 10⁻³cm/sec at 25°C, 2.6 × 10⁻³cm/sec at 30°C, and 3.1× 10^{−3 cm/secat 37°C}.
• 6.6. The activation energy of water diffusion was around 18 kJ/mol and increased to 27 kcal/mol after incubation with PCMBS in conditions of maximal inhibition of water diffusion.
• 7.7. The membrane polypeptide electrophoretic pattern of rabbit RBCs has been compared with its human counterpart.
• 8.8. The rabbit membrane contained a higher amount of spectrin (bands 1 and 2), while the band 6 (glyceraldehyde-3-phosphate dehydrogenase) was markedly less intense.
• 9.9. Considerable differences in the electrophoretic patterns of the two sources of RBC membranes appeared in the bands migrating in the band 4.5 region and in front of band 7, where some polypeptides were apparent in higher amounts in the rabbit RBC membrane.

     

Sodium balance in adult atlantic salmon (Salmo salar L.) during migration into neutral and acid fresh water

• 1.1. In sea-water, adult salmon (S. salar) exchange an average of 12.6% of total body sodium/hr.
• 2.2. Following transfer to fresh water sodium uptake follows Michaelis-Menton kinetics. F_max = 2.40 mmol Na/1 ECF/hr, K_m = 0.26 mmol Na/1. The uptake system is fully activated immediately following transfer to fresh water.
• 3.3. Post smolts adapted to sea-water for 3 months take up sodium at only one third of the rate of adult fish following return to fresh water.
• 4.4. The concentration of prolactin in the plasma is low in sea-water adapted fish and does not rise during the first 8 hr in fresh water.
• 5.5. At pH 5 sodium uptake is reduced by almost 90%, even in the absence of aluminium, but recovers immediately on return to neutral water.
• 6.6. At pH 5 and 20 μmol Al/1 there is little further effect on sodium uptake but after 6 hr in aluminium the inhibition of sodium uptake continues after return to neutral aluminium fresh water and uptake is only 50% of normal 24 hr later.

     

The effect of triiodothyronine on glucose utilization in adipocytes from obese rats

• 1.1. In the presence of insulin, 10⁻⁵ M 3,3',5-triiodothyronine (T₃) treatment for 1/2 hr decreased fatty acid synthesis 35% only in adipocytes from lean rats, whereas at 10⁻¹¹ M through 10⁻⁷M T₃ the obese adipocytes had nearly a 20% increase in fatty acid synthesis.
• 2.2. A 2 hr pretreatment of adipocytes with 10⁻⁹ and 10⁻⁷ M T₃ decreased insulin-stimulated fatty acid synthesis by nearly 20% in both lean and obese adipocytes.
• 3.3. In the absence of insulin, the 2 hr pretreatment with 10⁻⁹ M T₃ resulted in a 45% increase in lean adipocyte fatty acid synthesis, though the obese adipocytes required at least 10⁻⁷ M T₃ for 2 hr to increase the non-insulin-stimulated fatty acid synthesis by 50%.
• 4.4. At 10⁻⁹M T₃ concentrations non-insulin-stimulated fatty acid synthesis was increased by 200% in lean adipose tissue explants, but obese adipose expiants were not significantly affected under these conditions.
• 5.5. The addition of 10⁻⁹ M T₃ plus insulin to the explant media decreased fatty acid synthesis by 35% in both the lean and obese tissues.
• 6.6. The results also imply that the low T₃ status of the obese rat may be contributory to the elevated fatty acid synthesis observed in obese adipocytes.

     

The effect of salinity on coelomic fluid osmolyte concentration and intracellular water content in Luidia clathrata (Say) (Echinodermata: Asteroidea)

• 1.1. The concentrations (mM) of osmolytes in the coelomic fluid of Luidia clathrata kept at 25‰S seawater (control individuals) were: 345, Na⁺; 10, K⁺; 10, Ca²⁺; 44, Mg²⁺; 387, Cl⁻; 0.67, amino acids; 0.09, NH₄⁺.
• 2.2. When individuals were transferred from 25‰S to 15‰S or 35‰S, the concentrations of inorganic ions in the coelomic fluid usually equilibrated within 24hr and became the same as those in the medium.
• 3.3. The intracellular water content (g intracellular H₂O/g solute-free dry tissue) of the pyloric caeca and tube feet of control individuals throughout the experiment was 2.13 and 5.40, respectively.
• 4.4. In tissues of individuals transferred to 15‰S, the intracellular water content increased by an average 50% in 12 hr but returned to 19% above control levels during 1 week.
• 5.5. In tissues of individuals transferred to 35‰S, the intracellular water content decreased by an average 17% in 12 hr and did not change during 1 week.
• 6.6. Luidia clathrata is an osmoconformer and partial cell volume regulator within the seasonal salinity range it encounters.

     

Acute toxicity and bioaccumulation of endosulfan in rotifer (Brachionus calyciflorus)

• 1.1. The acute toxicity of endosulfan was determined for the freshwater rotifer Brachionus calyciflorus.
• 2.2. The mean 24 hr lc₅₀ value for endosulfan was 5.15 ppm with a coefficient of variation of 14.7%.
• 3.3. Rotifers were exposed at two sublethal concentrations (1.5–2.0 ppm) of endosulfan for bioaccumulation experiments, for an exposure time of 24, 48, 72 and 96 hr. The rotifers were fed with Nannochloris oculata (5 × 10⁵cell/ml).
• 4.4. The highest accumulation of endosulfan was found 24 hr after the start of the exposure to 1.5 ppm of the toxicant. A steady-state concentration in rotifer was reached between 24–48 hr, followed by a gradual decrease until 96 hr.

     

The oxygen consumption rates of three gastrotrichs

• 1.1. The oxygen consumption rates for three sympatric species of marine gastrotrichs (anatomically similar, except that one contains hemoglobin) were measured with a Cartesian diver microrespirometer.
• 2.2. The rates for the two species without hemoglobin, Turbanella ocellata and Dolichodasys carolinensis, were 307.2 μl O₂ g⁻¹ hr⁻¹ and 108.0 μl O₂ g⁻¹ hr⁻¹, respectively, while the rate for the hemoglobin-containing species, Neodasys, was 208.9 μl O₂ g⁻¹ hr⁻¹.
• 3.3. The possession of hemoglobin by Neodasys (14% by volume) cannot be explained by an unusually high demand for oxygen.
• 4.4. Instead, the hemoglobin may be useful as an oxygen store providing continued aerobic metabolism in anoxic conditions, thus allowing Neodasys to exploit a different niche.

     

Preparation of two neurotoxic esterases from the chick central nervous system

• 1.1. A standard procedure for lipid-extraction of lyophilized hen brain material is decribed.
• 2.2. Nine carboxylesterase isoenzymes (EC 3.1.1.1) are identified in lipid-extracted lyophilized material (LELM) using kinetic analysis of organophosphate inhibition. Total phenyl valerate (PV) hydrolysing carboxylesterase activity in LELM is 43.3U.g⁻¹
• 3.3. Two carboxylesterase isoenzymes of LELM are classified as neurotoxic esterases (NTE_A and NTEg_B).
• 4.4. Using n-octylglucoside 51% of the water-insoluble neurotoxic esterase activity from LELM are solubilized.
• 5.5. Six carboxylesterase isoenzymes including NTE_A (6.5 U-l⁻¹) and NTE_B (4.2 U-l⁻¹) are present in the solubilized preparation.
• 6.6. Throughout purification and separation steps carboxylesterase isoenzymes are identified by their rate constants for the reaction with organophosphorus inhibitors.

     

Purification and properties of a β-1,4-xylanase from a cellulolytic extreme thermophile expressed in Escherichia coli

• 1.1. An endoxylanase (EC 3.2.1.8) was purified from an Escherichia coli strain carrying a xylanase gene from the extreme thermophile “Caldocellum saccharolyticum strain Tp8T6.3.3.1. It was found to have an M_r of 42,000 and an isoelectric point of approx. 5.0.
• 2.2. The enzyme showed optimum activity at pH 5.0–7.7 and had an activation energy of 44 kJ mol⁻¹. It was stable at room temperature at pH 4.5–11.5 in the presence of 0.5 mg ml⁻¹ bovine serum albumin. The half-life of the enzyme at 75°C was 20 min at pH 6.0 in the presence of 0.5 mg ml⁻¹ bovine serum albumin.
• 3.3. The xylanase had highest activity on oat spelts xylan, releasing xylobiose and some xylotriose. The K_m for oat spelts xylan was 0.021% (w/v) at pH6.0.
• 4.4. The enzyme had high activity on sugar cane bagasse hemicelluloses A and B, lower activity on larchwood xylan and also hydrolysed carboxymethylcellulose, 4-methylumbelliferyl β-D-cellobioside and p-nitrophenyl β-D-cellobioside, but could not hydrolyse xylobiose.
• 5.5. It showed transferase activity on p-nitrophenyl β-D-xylopyranoside. Xylose did not inhibit the enzyme.

     

l-lysinamidase from Cryptococcus laurenti 112. Purification and properties

• 1.1. The purified enzyme hydrolyzes the linear l-lysinamide and the cycle amide of l-lysine—l-α-amino-ϵ-caprolactam.
• 2.2. The apparent relative molecular mass is 180,000. The enzyme consists of four subunits and the molecular mass of a single subunit was found to be 47,000.
• 3.3. The coefficient of molecular sedimentation equals 8.3 S, the isoelectric point was determined to be pH 4.3
• 4.4. The enzyme is not a glycoprotein. p-Mercuribenzoate binds 10 SH-groups of the native enzyme molecule and 20 SH-groups in the presence of 0.7% SDS.
• 5.5. pH- optimum for the hydrolysis of l-lysine amides was observed to be 7.5–7.7. The enzyme is strictly dependent on Mn²⁺ and Mg²⁺.
• 6.6. The kinetic parameters for the hydrolysis of l-lysinamide where K_m = 3.8 mM and k_cat = 3000 sec⁻¹ For the hydrolysis of cyclic L-lysinamide K_m = 4.8 mM and k_cat = 2600 sec⁻.

     

Blood volume recovery in hemorrhaged japanese quail

• 1.1. Blood volume and plasma biochemical changes and feed and water consumption in response to a hemorrhage by phlebotomy of 30% of the calculated total blood volume with and without replacement of blood volume with physiological saline were determined in juvenile male Coturnix coturnix japonica.
• 2.2. Plasma protein and osmolality decreased rapidly posthemorrhage and did not recover by 72 hr posthemorrhage.
• 3.3. Plasma glucose, Na⁺ and K⁺ increased within Ihr postphlebotomy. Plasma Na⁺ returned to nonphlebotomized levels within 6 hr postphlebotomy.
• 4.4. Saline replacement of blood volume resulted in hypervolemia within 3–5 min postphlebotomy.
• 5.5. Phlebotomized quail receiving no saline recovered blood volume to 0 hr (nonphlebotomized) levels within l hr postphlebotomy.

     

Intracellular localization and characterization of 3-hydroxykynureninase in human liver

• 1.1. 3-hydroxykynureninase in human liver was present in cytosol and mitoehondria.
• 2.2. The cytosolic enzyme and mitochondrial enzyme had the same physiological and enzymic properties.
• 3.3. The enzyme had a mol. wt of 130,000 by gel filtration and isoelectric point of pH 5.9.
• 4.4. The enzyme was active for 3-hydroxykynurenine and kynurenine, and its activity ratio was 15:1. The apparent K_m values of the enzyme were 7.7 × 10⁻⁵M for 3-hydroxykynurenine, 1.0×10⁻³M for kynurenine and 2.5 × 10⁻⁶M for pyridoxal 5'-phosphate with 3-hydroxykynurenine.
• 5.5. Some other properties of purified enzymes are described.

     

Sea water drinking as a homeostatic response to dehydration in hatchling loggerhead turtles Caretta caretta

• 1.1. Hatching Caretta caretta may lose up to 12% of their initial hatched weight from water loss during emergence from the nest.
• 2.2. After subsequent osmotic and excretory water loss in sea water, hatchlings will drink sea water (166 μl 100 g⁻¹ hr⁻¹) and return to their initial weight within 10–15 days, without feeding.
• 3.3. There were no significant changes in plasma osmolarity or sodium levels over this period.
• 4.4. This osmoregulatory strategy is in marked contrast to that seen in the estuarine crocodile, Crocodylus porosus.

     

Purification and properties of tetralysine endopeptidase from Escherichia coli AJ005

• 1.1. A new tetralysine endopeptidase from Escherichia coli AJ005 has been purified about 135-fold.
• 2.2. The peptidase seems to be specific to tetralysine among lysine homopolymers.
• 3.3. The optimal pH was about 7.5
• 4.4. The activity was inhibited by KCN but not inhibited by soybean trypsin inhibitor.
• 5.5. The apparent K_m value was 2.5 × 1O⁻³ M for tetralysine.

     

Characterization of chicken intestinal brush border membrane Ns/H exchange

• 1.1. Na/H exchange is the major pathway for Na uptake in brush border membrane vesicles from chicken small intestine. Hanes-Woolf analysis demonstrated that Na and H competed at the same extravesicular site. The K_Na for Na⁺ at extravesicular pH 6.6 is 35 mM and at pH 7.4, 12 mM.
• 2.2. Similar to mammalian intestinal cells, the Na/H exchanger does not appear to have an internal proton modifier site. Varying intravesicular pH from 6.1 to 7.8 stimulates uptake, but a sigmoidal relationship is not observed.
• 3.3. The ability of several amiloride analogs to inhibit the exchanger was tested and the inhibitory profile was similar, but not identical to Na/H exchangers in mammalian tissues. The potency series (from most to least potent) is hexamethylamiloride ≈ ethylisopropylamiloride > methylisobutylamiloride > dimethyl-amiloride > amiloride.

     

Differential effects of fatty acid chain length on the viability of two species of cactophilic Drosophila

• 1.1. Two columnar cacti in the Sonoran Desert, agria and organpipe, contain medium chain (C₈−C₁₂) fatty acids.
• 2.2. Necrotic tissues of these cacti serve as feeding and breeding substrates for Drosophila mojavensis but not D. nigrospiracula.
• 3.3. Results show that capric and lauric acids are the predominant fatty acids of both cacti.
• 4.4. Fatty acid chain length exhibits a differential effect on larval viability with caprylic acid (Q) having the greatest and myristic acid (C₁₄) having the least effect.
• 5.5. Drosophila mojavensis is more tolerant of free fatty acids than D. nigrospiracula, and this partly explains the ability of D. mojavensis to utilize agria and organpipe cacti.

     

Demonstration of highly specific and sensitive antibodies to a naturally occurring tetrahydroisoquinoline alkaloid,salsolidine

• 1.1. We report for the first time on the production and characterization of antibodies against a naturally occurring tetrahydroisoquinoline, namely salsolidine (6,7-dimethoxy-1-methyl-1,2,3,4-tetrahydroisoquinoline).
• 2.2. Immunogen synthesis was carried out by coupling the hapten salsolidine to bovine serum albumin (BSA) as carrier protein on the basis of reductive amination.
• 3.3. By immunization of rabbits with salsolidine-BSA conjugate antisalsolidine antibodies were produced.
• 4.4. At a final dilution of 1:1700 the highest-litre antiserum bound 35% of 0.21 pmol [³H] salsolidine. This antiserum was used to develop a radioimmunoassay for salsolidine.
• 5.5. Cross-reactivity studies revealed a high specificity of the antiserum to the hapten.
• 6.6. The antibodies had a high affinity to salsolidine (K_a = 1.5 × 10⁹ M⁻¹).
• 7.7. Standard curves covered a measuring range of 0.5–70 pmol/tube and the detection limit was found to be 0.27 pmol/tube.

     

Increased muscle glucose uptake in response to chronic glyburide treatment is not related to changes in glucose transporter (GLUT4) protein

• 1.1. The mechanism of action of glyburide (a sulfonylurea) on muscle has been investigated by measuring glucose uptake and glucose transporter (GLUT4) protein levels after chronic glyburide treatment.
• 2.2. A dietary induced insulin resistant rat model (4 wk of high-fat, high-sucrose feeding) was given glyburide (2mg/kg/day) for 10 days and glucose uptake was measured in a perfused hindquarter preparation.
• 3.3. Protein levels of the GLUT4 glucose transporter were determined by Western analysis.
• 4.4. After 7 days of treatment, rats fed glyburide had lower blood glucose concentrations 2 hr (72 ± 5 vs 103 ± 12 mg/dl) and 24 hr (97 ± 7 vs 123 ± 7 mg/dl) after glyburide administration with no difference in serum insulin levels compared to vehicle treated animals.
• 5.5. Glucose uptake was approx doubled in basal state (0 insulin) in response to glyburide (2.8 + 0.4 vs 1.7 ± 0.2μ mol/g per hr).
• 6.6. Maximal insulin (100 nM) stimulated glucose uptake tended to be higher in the glyburide treated group, but did not reach statistical significance (8.0 ± 0.7 vs 7.0 ± 0.6 μmol/g per hr).
• 7.7. Western analysis revealed no significant effect of glyburide on the GLUT4 protein level in skeletal muscle.
• 8.8. These results suggest that glyburide alters glucose uptake through some mechanism other than alterations in the level of the GLUT4 glucose transporter protein.