Biomines-stimulated phosphorylation and (Na+, K+-ATPase in the gills of the chinese crab,Eriocheir sinensis

• 1.1. Subcellular distribution of (NA⁺, K⁺-ATPase and ouabain-insensitive ATPase (Mg²⁺-ATPase) are compared in branchial tissues of the euryhaline crab, Eriocheir sinensis, acclimated to fresh water.
• 2.2. Both the anterior and posterior gills contain cAMP-dependent protein kinase and endogenous protein substrate for phosphorylation.
• 3.3. Phosphorylation occurs in both “particulate” and “soluble” subcellular fractions but its stimulation by cAMP is restricted to the “soluble” fraction.
• 4.4. serotonin (5-HT) and dopamine receptors are present only in the “light particulate” fraction isolated from the posterior gills.

• 1.(a) Serotonin and dopamine have no effect on the phosphorylation observed in a subcellular fraction alone.
• 2.(b) Activation of the phosphorylation by serotonin and dopamine is found when the soluble fraction (source of cAMP-dependent protein kinase) is added to the fraction P₃ from the posterior gills.
• 3.(c) No activation occurs with the fractions P₃ as well as P₁ or P₂ (not shown) from anterior gills of fresh water crab.
• 4.(d) Cyproheptadine, a serotonin receptor antagonist, inhibits the 5-HT dependent increase in phosphorylation.
• 5.(e) The dopamine receptor antagonist, chlorpromazine, inhibits dopamine-stimulated phosphorylation.
• 6.5. Ouabain mimics the effect of cyproheptadine on the serotonin-stimulated phosphorylation found in the posterior gills.

     

Respiration in the eastern water dragon,Physignathus lesueurii (agamidae)

• 1.1. Some aspects of the gas exchange system of a diving lizard, Physignathus lesuewii were studied.
• 2.2. Breathing patterns were analysed.
• 3.3. Breathing rate increases logarithmically with temperature and Q₁₀ = 1.8. LogBR = −0.237 + 0.0256 T.
• 4.4. Gas tensions in lung air and arterial and venous blood were measured. Arterial pH declines with increasing temperature.
• 5.5. Temperature has a marked effect on oxygen affinity of the blood (ΔH = −10.1 kcal mol⁻). A Bohr effect was also noted.
• 6.6. CO₂ equilibrium curves were drawn.
• 7.7. The results are considered with a view to anticipating the efficiency of the gas exchange system of this species under conditions of variable temperature and during diving.

     

Synchrony of dolphin eye movements and their power density spectra

• 1.1. In the laboratory, eye movements in the horizontal and vertical planes of a normal human and two adult dolphins, Tursiops truncatus, were analyzed and compared. Several of the visual conditions included structured, unstructured and moving stimulus fields.
• 2.2. Power spectral density analyses of the dolphin eye movements showed maximal power around 0.1 Hz, lower than the human counterpart.
• 3.3. Coefficients of determination (r²) and correlation coefficients (r) derived from autocorrelation and crosscorrelation of dolphin eye signals produced typically small values scattered randomly around zero.
• 4.4. From 51,200 correlations, the greatest r² value indicated that movements of one dolphin eye predict no more than 30% of the movement variance of the fellow eye.
• 5.5. Although dolphin eyes are mobile at lower fundamental frequencies than in humans, there is a low level of synchrony between the two eyes.

     

The influence of optic nerve section on blood metabolite levels in Carcinus maenas (Crustacea: Brachyura)

• 1.1. Blood metabolite levels were assayed in Carcinus maenas as an indicator of the functioning of the hyperglycemic hormone, HGH, secreted by the crab's eyestalk neuroendocrine tissue.
• 2.2. Bilateral eyestalk ablation eventually resulted in a hypoglycemic response after 2–3 days.
• 3.3. Bilateral optic nerve section produced a significant, long-term hypoglycemic response suggesting that release of HGH from the eyestalk sinus gland is controlled, via a promotive neural pathway, by the CNS and probably by the cerebral ganglia.
• 4.4. Injection of eyestalk extract into operated crabs consistently produced significant, short-term hyperglycemia.

     

Changes in cAMP and cGMP levels induced by relaxing drugs in acetylcholine- and potassium-treated molluscan smooth muscle

• 1.1. The changes of cAMP and cGMP levels in response to serotonin, dopamine, papaverine and Aspaminol were investigated in acetylcholine- and potassium-treated molluscan smooth muscle in accordance with the time course of contraction-relaxation process in mechanical response to acetylcholine and potassium.
• 2.2. Acetylcholine (10⁻⁵ M) and potassium (229 mM) had no influences on basal cAMP and cGMP levels.
• 3.3. Serotonin (10⁻⁶ M and 10⁻⁵ M) dose-dependently elevated cAMP level and serotonin (10⁻⁵ M) reduced cGMP level in acetylcholine-treated muscle.
• 4.4. Serotonin (10⁻⁵ M) elevated cAMP level and reduced cGMP level in potassium-treated muscle.
• 5.5. Dopamine (10⁻⁶M and 10⁻⁵M), papaverine (10⁻⁴M) and Aspaminol (10⁻⁴M) had no effect on cAMP and cGMP level in acetylcholine- and potassium-treated muscle.
• 6.6. Relaxing effect of serotonin may be associated with elevated cAMP level and reduced cGMP level at the pharmacological but not physiological level.

     

Effects of K+, Ba2+ and Ca2+ on the excitable membrane in Paramecium tetraurelia

• 1.1. The effects of Ba²⁺ and K⁺ ions on the membrane currents of Paramecium tetraurelia under a voltage clamp were investigated.
• 2.2. External Ba²⁺ suppresses the inward-going K-current and the Ca-induced K-outward current and changes the activation and inactivation kinetics of transient inward current through the Ca-channel.
• 3.3. K⁺ increases the Ca-induced K-conductances but little affects the leakage conductance.
• 4.4. The resting potentials by changing those ionic concentrations shift the voltage sensitivities of all voltage sensitive channels, simultaneously.
• 5.5. The competition between ions to the channel responses was discussed.

     

The multiplicity of neurotransmitters and neurohormones controlling mytilus muscle

• 1.1. The effects of various biogenic amines on contractions of the ABRM of M. edulis in response to repetitive electrical stimulation, ACh and high K⁺ concentration were examined.
• 2.2. Octopamine, serotonin, dopamine, noradrenaline, tyramine and phenylethanolamine potentiated the contractions of ABRM. Octopamine was found to be the most potent. Histamine did not potentiate.
• 3.3. Phentolamine blocked the potentiating action of octopamine and noradrenaline and partially blocked dopamine, but it did not block serotonin. Phentolamine also blocked the potentiating after-effect of repetitive electrical stimulation on subsequent contractions. It is suggested that octopamine is a neurotransmitter or a local neurohormone which potentiates contraction of the ABRM.
• 4.4. Under certain conditions, high concentrations of dopamine and serotonin inhibited contractions in response to ACh and high K⁺ concentration. Thus, these amines have not only potentiating but also inhibitory action on contraction of the ABRM, in addition to relaxing catch.
• 5.5. It is suggested that a wide spectrum of substances participates in the physiological control of contractility in the ABRM.

     

Serotonin,histamine and somatostatin modulation of PMA-stimulated phosphorylation of 130kDa Ca2+ pump-like protein from rat cerebellum synaptosomal membranes

• 1.1. Influence of some neurotransmitters and neuromodulators on the PMA-stimulated phosphorylation in vitro of calcium pump-like protein from rat cerebellum synaptosomal membranes was examined.
• 2.2. The prolonged time (up to 6 min) of synaptosomal membranes preincubation with 1 and 10 μM serotonin results in the increase of phosphorylation. The decrease of phosphorylation up to 80% of control value was observed for 100 μM serotonin.
• 3.3. The most stimulating effect on 130kDa protein phosphorylation was observed with 1μM of histamine (160% of control value).
• 4.4. 1 and 0.1 μM somatostatin triggered a short-time transient increase of 130 kDa phosphorylation (up to 135% of control value).

     

Effect of polarized light on the ERG circadian rhythm in crayfish

• 1.1. Crayfish subjected to constant darkness and temperature displayed an electroretinographic circadian rhythm with both non-polarized and polarized light stimuli.
• 2.2. In the ERG circadian rhythm associated with polarized light there was an observed reduction in period and increment in both amplitude and activity: rest ratio.
• 3.3. The change from non-polarized to polarized light also produced phase advances or delays in the ERG circadian rhythm depending on the circadian time when the change was introduced.
• 4.4. Separate recording of HI and HII ERG components showed that HII is always less conspicuous and more easily saturable than HI circadian rhythm.
• 5.5. These results support that: (a) the detection of polarized light contributes to extend the differences between night and day; (b) the two structures involved in the generation of HI and HII ERG components, i.e. the rhabdom and the retinular cell, operate as two independent elements of the circadian system responsible of ERG circadian rhythm.

     

Modulation of active potassium transport by aldosterone

• 1.1. The role of aldosterone on active potassium transport across lizard colon under voltage-clamped conditions has been investigated.
• 2.2. Control colons exhibited no net potassium flux (J^k_net) despite of the existence of active opposite unidi ectional fluxes.
• 3.3. An important net secretory potassium flux was found in short-circuited aldosterone-stimulated colons.
• 4.4. Mucosal amiloride did not change (J^k_net) either in control or aldosterone-stimulated colons.
• 5.5. Luminal barium alters K ⁺ transport in a manner consistent with the presence of barium-sensitive conductances at the apical membrane of both control and aldosterone-treated colons.
• 6.6. The effects of ouabain and barium on control and aldosterone-induced potassium flows were consistent with a model involving basolateral uptake by an Na ⁺-K ⁺-ATPase and conductive exit across the apical membrane.
• 7.7. The stimulatory effect of aldosterone on potassium secretion is associated with parallel increases of both basolateral K ⁺ entry and the apical conductive pathway.

     

Effects of oxygen on the cercal receptors of the cockroach Periplaneta americana

• 1.1. The activity of the cercal nerve XI and giant interneurons of the cockroach Periplaneta americana is much more intense in situ than in vitro, despite perfusion of the sixth abdominal ganglion by oxygenated saline.
• 2.2. The background cercal nerve activity increases in vitro upon oxygenation from a negligible level. It persists for about 10 min following cessation of oxygenation. The activity in situ remains unaffected.
• 3.3. Oxygenation also substantially increases the frequency of sensory spikes evoked during mechanical stimulation of cercal receptors in vitro, as well as the frequency of generated EPSPs in the interneurons which integrate the cercal activity. The latter effect is apparently due to the increased frequency of afferent spikes.
• 4.4. The intense activity detected in vitro in oxygenated preparations appears to be closer to that existing in situ.

     

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.

     

A dopamine- and octopamine-sensitive adenylate cyclase in the nervous system of Octopus vulgaris

• 1.1. Adenylate cyclase activity was assayed in the optic lobe of Octopus vulgaris.
• 2.2. Both octopamine and dopamine stimulate the octopus adenylate cyclase, apparently by competing with the same receptor site.
• 3.3. (±)-2-Amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene-HBr (6,7-ADTN) and a number of phenylethanolamine derivatives stimulate the octopus adenylate cyclase activity.
• 4.4. The dopamine D-1 antagonists R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine-HCl (SCH-23390) and (±)-7-bromo-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine-HCl (SKF-83566) are unable to antagonize the effects of dopamine and octopamine, and similarly ineffective is the agonist (±)-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine-7,8-diol-HCl (SKF-38393).
• 5.5. No detectable binding of labelled SCH-23390 occurs on membrane preparations from octopus optic lobe.

     

A study of excitatory efferent fibres in the intestinal nerve of the fowl (Gallus domesticus)

• 1.1. The intestinal nerve of the fowl was studied in vitro.
• 2.2. A significantly larger amplitude spike discharge was recorded in side branches of the nerve which innervate the gut when the aboral end of the main nerve trunk was stimulated than when the oral end was stimulated.
• 3.3. Postganglionic autonomic neurones innervating the smooth muscle of the ileum are not located in the intestinal nerve. Evidence is presented, however, supporting the idea that such neurones innervating the rectum are located in the rectal position of the nerve.
• 4.4. The increase in intraluminal pressure and circular muscle tension in the ileum was greater following aboral nerve stimulation than following oral nerve stimulation.
• 5.5. It is suggested that excitatory efferent nerve fibres ascend the intestinal nerve to innervate the ileum.

     

Erg circadian rhythm in the course of ontogeny in crayfish

• 1.1. The objective of the present work was to study the ontogeny of the ERG circadian rhythm in crayfish.
• 2.2. Long-term recordings of ERG and shielding retinal pigments position measured from the instar, the second instar, the third instar and the adult crayfish were obtained.
• 3.3. In the youngest animals (1–8 days old) an ultradian rhythm (15min-4hr periods) in the ERG amplitude was detected.
• 4.4. Older animals showed a progressive increment in the period length before they exhibited a circadian pattern. This last appeared, the first time, in 30-day-old animals and showed noticeable differences in the adult crayfish. At the same time, the crayfish began to show photomotor reflex. Later on (140-day-old crayfish) the circadian rhythm attained its final parameters.
• 5.5. The SD was used as a measure of lability in periods. The 4 hr ultradian rhythm and the 22.4 hr circadian rhythm showed the lowest SD indicating that they are the most precise period values.
• 6.6. Our results support the idea that the ERG circadian rhythm results from the coupling among high frequency (ultradian) oscillators, particularly those of 4 hr periods and that the coupling depends on the action of neurosecretions released from the sinus gland.

     

The dynamics of the permeation of an analogue of insect juvenile hormone into nematodes

• 1.1. ¹⁴C-dichlorofarnesoate permeated rapidly into Haemonchus contortus (infective juveniles) and Panagrellus redivivus (mixed cultures) and was strongly bound by hydrophobic association (K_s > 10⁻⁴M).
• 2.2. Uptake rose linearly with increases in temperature (5–38°C) and external concentration (C₀; 0.07–2.15 × 10⁻⁴ M). Within 1 hr the internal concentration, C₁ was >C C₀.
• 3.3. The pH of the medium (6–8) did not affect uptake.
• 4.4. Efflux of dichlorofarnesoate was low: the half-time of release was > 18 hr.
• 5.5. The uptake curve approximated to the expression C₁/C₀ = a(1 − e^−bt) with a and b as constants and t in hr.
• 6.6. These results clarify previous work on the inhibitory action of juvenile hormone on the development of nematodes.

     

Toxicity of cadmium administration to the toad and the treatment of its poisoning with EDTA

• 1.1. The effect of cadmium administration on female Bufo regularis was studied. The median lethal doses were 22, 18, 15 and 6.2 Cd²⁺/kg after 24, 48, 72 and 96 hr respectively.
• 2.2. After a single intramuscular injection of 6.2 Cd²⁺/kg (representing 96-hr ld₅₀), the results indicated that Cd²⁺ causes severe physiological abnormalities to this experimental animal.
• 3.3. The serums alanine aminotransferase (AlAt), aspartate aminotransferase (AAt), alkaline phosphatase (A1P) and lactic dehydrogenase (LDH) were elevated while the calcium serum was not influenced by Cd²⁺ throughout the experimental period
• 4.4. On the other hand, phosphorus, total protein and total bilirubin were increased.
• 5.5. EDTA treatment (0.2 mmole/kg protected female toads from mortality up to 20 mg Cd²⁺/kg. It overcame the physiological alterations that were caused by the Cd²⁺ injection.
• 6.6. This may be due to the fact that Cd²⁺ is bound to EDTA in a strong complex which is readily excreted via the kidneys.

     

Ca2+-dependent stimulation of muscle and liver phosphorylase kinase by heparin

• 1.1. Heparin stimulates the activity of nonactivated and activated skeletal muscle phosphorylase kinase in a Ca²⁺-dependent manner.
• 2.2. The stimulatory effect of heparin on the activity of nonactivated phosphorylase kinase is also expressed in the presence of calmodulin and glycogen. Heparin acted in synergism with glycogen.
• 3.3. Heparin increases the affinity of phosphorylase kinase to Ca²⁺ 5–12 fold depending upon the activation conditions.
• 4.4. Ca²⁺ influences the stimulation of liver phosphorylase kinase by heparin in a similar way.

     

Evidence that the alkaline P-nitrophenylphosphate phosphatase from Halobacterium halobium is a manganese-containing enzyme

• 1.1. Alkaline p-nitrophenylphosphate phosphatase of Halobacterium halobiium, either purified or in crude extracts, was progressively inactivated by treatment with several metal chelators.
• 2.2. The activity of treated crude extracts was fully restored in the presence of 25–50 μM Mn²⁺ or 1 mM Co²⁺, and partially restored in the presence of 1 mM Cd²⁺.
• 3.3. Zn²⁺ ions, as well as other divalent cations tested, were without effect.
• 4.4. In the presence of a saturating concentration of Mn²⁺, but not Co²⁺ or Cd²⁺, the activity of the metal-depleted enzyme reached values well over the native control activity.
• 5.5. Activation of the metal-depleted enzyme by Mn²⁺ showed cooperative kinetics, whereas activation by Co²⁺ showed Lineweaver-Burk kinetics.
• 6.6. The results suggest that the enzyme contains two different types of metal-binding sites: essential site(s), occupied by endogenous Mn²⁺ ions, and regulatory site(s), that can be occupied by exogenous Mn²⁺ with an activating effect.

     

The digestive enzymes of the pacific brown shrimp Penaeus californiensis.: I—Properties of amylase activity in the digestive tract

• 1.1. Crude extract of the whole digestive tract from the brown shrimp (P. californiensis) was investigated for digestive amylase activity.
• 2.2. Considerable amylase activity was found at pH 6.5–8.0, with optimum pH at around 7.5.
• 3.3. Optimum temperature was found between 30–40°C, similar to amylases from other crustaceans.
• 4.4. Amylase activity was highly halotolerant, having 50% maximum activity at 3 M NaCl.
• 5.5. Maximum amylase activity was found at 0.01 M NaCl.
• 6.6. Amylase activity was partially inhibited by the divalent ions Hg²⁺, Zn²⁺, Cu²⁺ and Cr²⁺.
• 7.7. Mg²⁺ and Ca²⁺ ions seemed to enhance amylase activity.