Basis for hyperexcitation symptom caused by high doses of chlordimeform in the American cockroach

• 1.1. Exposure of isolated ventral nerve cords of the American cockroach to chlordimeform was followed by spontaneous and stimulus-induced hyperactivity which different from that induced by dieldrin in the distribution of spike amplitudes, the delay between stimulus and response and the stimulus threshold to induce hyperactivity.
• 2.2. Calcium (20 mM) abolished the impulse-evoked hyper-response of the nerve to chlordimeform but not to dieldrin.
• 3.3. Magnesium (40 mM) abolished the impulse-evoked hyper-responce of the nerve to dieldrin but not to chlordimeform.
• 4.4. Treatment of the insects with reserpine prior to dissection had no effect on the subsequent hyper-response of the isolated nerve to chlordimeform.
• 5.5. The observed action of chlordimeform is probably axonal, and is unrelated to its known aminergic effects.

     

Effects of hypoxia on resting potential and transmitter release at cercal afferent,giant interneurone synapses in the cockroach,Periplaneta americana L.

• 1.1. Studies of experimentally induced hypoxia were carried out on synapses in the isolated sixth abdominal (A6) ganglion of the cockroach using electrophysiological methods.
• 2.2. During a break of saline superfusion, oxygen tension (PO₂) decreased and depolarization of presynaptic and postsynaptic membranes was observed.
• 3.3. During hypoxia EPSP amplitude initially increased, but decreased after a few minutes.
• 4.4. Changes in the EPSP and membranes potential resulting from hypoxia were reversed when the saline superfusion was restarted.
• 5.5. Changes in the amplitude of both the EPSP and the depolarization induced by microiontophoretic injections of ACh indicated that ACh release initially increased during hypoxia and decreased during recovery from oxygen deprivation.

     

Metabolic behaviour of nonhistone chromosomal proteins during differentiation (spherulation) of Physarum polycephalum

• 1.1. Spherulation of Physarum microplasmodia is accompanied by a transient and moderate intranuclear accumulation of nonhistone proteins during the first 12 hr after induction.
• 2.2. At least part of these proteins have been synthesized before induction but migrate to the nucleus after the transfer of plasmodia to non-nutrient medium.
• 3.3. While in the cytoplasm at the final stage of sperulation most of the proteins have been replaced by new molecules, the majority of the nonhistone proteins synthesized before induction were found preserveclin the spherules.

     

Evidence that the 5' end of rabbit globin mRNA is hybridized with its 3' end

• 1.1. A radiopolyadenylated rabbit globin mRNA was treated with different concentrations of ribonuclease V₁ from cobra venom.
• 2.2. The enzymatic digests were chromatographed on an aminophenylboronate-agarose column, which specifically captured the cap structure i.e. n⁷G(5') ppp (5') NmP.
• 3.3. When the capture fragment was chromatographed on a Sephadex G-100 column, its size was smaller than the native molecule and also bore radioactivity, i.e. a poly(A) tail.
• 4.4. These results provide evidence that the 5' end (which encompasses the cap structure) of rabbit globin mRNA is hybridized and in close proximity to its 3' end.
• 5.5. We conclude that this conformation is required for messenger translation efficiency.

     

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.

     

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.

     

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.

     

Effect of bovine milk antigens and egg lysozyme on the binding of 59Fe-lactoferrin to platelet plasma membranes

• 1.1. Platelets bind specifically to lactoferrin. A significant similarity between human lactoferrin and some bovine milk proteins has been established.
• 2.2. Because of the structural homology of lactoferrin and cows milk proteins they are able to influence lactoferrins regulatory function on the level of its binding to membrane receptors on platelets.
• 3.3. An inhibitory effect of bovine α-lactalbumin and of β-lactoglobulin on lactoferrin-receptor interaction was shown.
• 4.4. Bovine α-lactalbumin competes with lactoferrin for the binding sites.
• 5.5. Scatchard plot analysis of data shows one binding site for lactoferrin in the presence of α-lactalbumin with an affinity constant, Ka = 0.46 × 10⁹ mol/1 and 335 receptors/cell.
• 6.6. The inhibitory effect of β-lactoglobulin reaches 62% and is different for the common fraction ⨿-lactoglobulin and the genetic variants β-lactoglobulin A and B.
• 7.7. β-lactoglobulin does not compete with lactoferrin for the membrane receptors.
• 8.8. Bovine casein and egg lysozyme stimulate ⁵⁹Fe-lactoferrin binding to the receptors. The mechanism of these effects is still unknown.
• 9.9. Tested alimentary antigens are able to interact with lactoferrin and also with some platelet membrane structures.
• 10.10. Established changes in lactoferrin binding to the platelet membrane might be in relation to lactoferrins regulatory function and (or) eliminating mechanisms of these alimentary antigens.

     

Demonstration of specific receptors for calcitonin in isolated trout gill cells

• 1.1. Salmon calcitonin binding by isolated gill cells from rainbow trout, Salmo gairdneri has been investigated.
• 2.2. The calcitonin receptor interaction is time- and temperature-dependent.
• 3.3. 50% of inhibition of the ¹²⁵I labeled calcitonin binding is observed in presence of 1.5 ng/ml unlabeled salmon calcitonin.
• 4.4. Two types of receptors are described: a high affinity-low capacity site and a low affinity-large capacity site.
• 5.5. These studies strongly support the role of calcitonin as a hormone regulating the gill function in physiological conditions.

     

Effects of Na+ and/or K+ on the Mg2+-dependent ATPase activities in shrimp (Macrobrachium amazonicum) gill homogenates

• 1.1. Homogenates of gills from the freshwater shrimp M. amazonicum exhibit the following ATPase activities: (i) a basal, Mg²⁺-dependent ATPase; (ii) an ouabain-sensitive, Na⁺ + K⁺-stimulated ATPase; (iii) an ouabain-insensitive, Na⁺-stimulated ATPase; and (iv) an ouabain-insensitive, K⁺-stimulated ATPase.
• 2.2. K⁺ suppresses the Na⁺-stimulated ATPase activity in a mixed-type kind of inhibition, whereas Na⁺ does not exert any noticeable effect on the K⁺-stimulated ATPase activity.
• 3.3. The Na⁺- and the K⁺-stimulated ATPase activities are totally inhibited by 5 mM ethacrynic acid in the incubation medium.
• 4.4. The Na⁺- and the K⁺-stimulated ATPase activities are not expressions of the activation of a Ca-ATPase.
• 5.5. The possible localization and roles of the described ATPases within the gill epithelium are briefly discussed and evaluated.

     

Electrical transport characteristics of Aplysia californica intestinal epithelium

• 1.1. Replacing chloride (Cl⁻) with sulfate (SO₄²⁻) in the bathing medium drastically reduced the mucosal membrane potential difference (ψ_m).
• 2.2. The voltage divider ratio was significantly greater than one.
• 3.3. Mucosal ^d-glucose decreased the input resistance of the intestinal epithelium.
• 4.4. Addition of furosemide to the mucosal bathing medium inhibited transepithelial potential difference and short-circuit current.
• 5.5. Addition of SITS to the mucosal bathing medium partially inhibited transepithelial potential difference and short-circuit current.
• 6.6. Diffusion potentials in the intestinal epithelium were symmetrical.

     

Crayfish retinular cells: Influence of extracellular sodium and calcium upon receptor potential

• 1.1. In crayfish, light stimulation of the retinular cells induces a depolarizing receptor potential.
• 2.2. Experiments were designed to determine the role of Na⁺ and Ca²⁺ on receptor potential during dark And light states.
• 3.3. Depolarization depends on Na⁺ and Ca²⁺ availability to the retinular cell.
• 4.4. Repolarization velocity and response duration depend on extracellular Ca²⁺ availability.
• 5.5. Light adaptation increases receptor potential dependence on calcium and sodium ions.
• 6.6. We analyse these results with respect to other invertebrate photoreceptors.

     

An insect epidermal cell line (UMBGE-4): Structural and electrophysiological characterization

• 1.1. The cellular organization (including junctional connectivity) and electrophysiological characteristics of the UMBGE-4 epithelial cell line originally derived from the cockroach were studied. These cells grew in culture in the form of hollow vesicles which could reach 5 mm in diameter. The wall of the vesicles varied in form and thickness from resembling a squamous to a columnar epithelium. Parts of the vesicle wall were multi-cellular with some cytoplasmic variability in the constituent cells. On the whole, the cellular architecture of the vesicles resembled that of a secretary epithelium with abundant microvilli and apical vacuoles, an extensive network of endoplasmic reticulum and prominent Golgi apparatus.
• 2.2. The main type of cell junction was septate-like and comprised extensive, convoluted regions of cellular apposition with some gap junctions therein. The septate junctions were permeated extensively by lanthanum and the epithelium appeared to be leaky.
• 3.3. A small negative trans-cellular (lumen) potential (mean value, −2.7 mV) was present and this was only transiently affected by changes in extracelluar Na⁺, K⁺ or Cl⁻ concentrations.
• 4.4. The cells' resting membrane potentials were distributed normally around a mean of − 77 mV. Some 64% of resting membrane electrogenesis could be accounted for in terms of K⁺ and Cl⁻ permeabilities; Na⁺ had no involvement.
• 5.5. The structural, electrophysiological and biochemical characteristics taken together would suggest that the UMBGE-4 cells could serve as a useful model for the epidermal epithelium in insects.

     

Na+-K+ ATPase and carbonic anhydrase activities in larvae,postlarvae and adults of the shrimp Penaeus japonicus (Decapoda,Penaeidea)

• 1.1. Activities of Na⁺-K⁺ ATPase and carbonic anhydrase were measured through the early post-embryonic development of Penaeusjaponicus. In adults, only the Na⁺-K⁺ ATPase activity was measured.
• 2.2. ATPase activity was variable in the successive development stages. From zero in nauplii, the activity slightly increased in zoeae, and rose sharply in mysis stages 2 and 3.
• 3.3. A further significant increase in activity was noted at the transition from late mysis to early postlarvae, concomitant with a change from the larval osmoconforming pattern of osmoregulation to the postlarval and adult hyper-hyporegulating pattern.
• 4.4. The activity of Na⁺-K⁺ ATPase, measured in isolated cephalothorax, increased from PL3 to PL4 to its maximum value in PL5; at this stage, osmoregulatory capacity was fully efficient.
• 5.5. In young stages of P. japonicus, the variations in Na⁺-K⁺ ATPase activity appear correlated with the development of osmoregulatory ultrastructures, and with osmoregulation and salinity tolerance.
• 6.6. These results are discussed with regard to their ecological and physiological implications.
• 7.7. In adults, the activity of Na⁺-K⁺ ATPase was high in gills and epipodites and no activity was detected in branchiostegites. These results are related to the ultrastructure of these organs.
• 8.8. The activity of carbonic anhydrase did not change significantly in larval and postlarval stages.
• 9.9. From these results, it is proposed that the effector sites of osmoregulation are located in branchiostegites, pleurae and epipodites in postlarvae, and in epipodites and mainly in gills in adults.

     

Active transport of d-glucose in intestinal segments,in vitro,of the scup,Stenotomus versicolor and the puffer,Spheroides maculatus

• 1.1. Active transport of d-glucose was shown using intestinal sac preparations, in vitro, made from two marine fish, the scup, Stenotomus versicolor and the puffer, Spheroides maculatus.
• 2.2. Differences in absorption characteristics were evident in populations from year to year.
• 3.3. Anaerobiotic conditions, i.e. 100 per cent nitrogen gassing of the incubation medium, inhibit the active transport of d-glucose in scup and puffer intestine.
• 4.4. Phlorizin, 5 × 10⁻⁴ M, inhibits the active transport of d-glucose in scup intestine.
• 5.5. Intestinal transmural glucose transport mechanisms operate well at incubation temperatures, 20°–27°C, i.e. temperatures close to habitat and holding tank temperatures, whereas movement of the sugar against a concentration gradient is interrupted at higher incubation temperatures, 29° and 30°C.
• 6.6. Detailed comparison of procedures and results with those used by other workers in the field of in vitro intestinal absorption of poikilotherms suggests that aerobic metabolism may not be a uniformly significant energy source in intestinal active transport.

     

Are lysosomes directly involved in the iron uptake by reticulocytes?

• 1.1. The mechanism by which iron is transferred from the plasma protein transferrin into erythroid precursors for incorporation in heme is not completely understood.
• 2.2. To show a direct functional role of lysosomes in the process of iron uptake we tried to isolate lysosomes from reticulocytes, which have been incubated with ¹²⁵ITf⁵⁹Fe.
• 3.3. However, with various cell fractionating techniques described for liver cells no pure lysosomes from reticulocytes could be obtained.
• 4.4. Fluorescence and electron microscopy showed that reticulocytes hardly contain well-defined lysosomes.
• 5.5. There are several indications that in reticulocytes acid vacuoles instead of lysosomes are involved in the removal of iron from endocytosed transferrin.
• 6.6. The presence of apoTf, monoferric TfFe(A), monoferric TfFe(B) in the medium after incubation of reticulocytes with diferric transferrin, together with the fact that both iron binding sites of transferrin release their iron at pH present in acid vacuoles, suggests a second mechanism of iron uptake by reticulocytes, in which acid vacuoles are not involved.

     

Identification of essential amino acids in the active center of thyroidal NAD+ glycohydrolase

• 1.1. Purified thyroidal NAD⁺ glycohydrolase has been subjected to the action of a number of group specific reagents in order to gain information concerning its mode of action.
• 2.2. Modification of histidyl residues with diethylpyrocarbonate strongly suppresses the NAD⁺ glycohydrolase activity. Inactivation with this reagent can be reversed to some extent by subsequent treatment with hydroxylamine.
• 3.3. NAD⁺ and ADP-ribose partially protect against inactivation with similar efficiencies.
• 4.4. The incomplete reactivation with hydroxylamine after diethylpyrocarbonate treatment and the selective inactivation by 2,4-pentanedione indicates that apart from one or more essential histidyl residue(s) also lysyl residues are important for activity. NAD⁺ and to a smaller extent ADP-ribose again protect against inactivation by 2,4-pentanedione.
• 5.5. The sensitivity of the enzyme towards N-ethyl-5-phenyl-isooxazolium-3'-sulfonate further points to the importance of carboxylate containing side chains.
• 6.6. The mechanistic implications of these results are discussed.

     

Phosphorylation of a 25,000-dalton protein in slow and fast muscles of the chicken

• 1.1. Protein phosphorylation in intact chicken latissimus dorsi muscle, slow anterior (ALD) and fast posterior (PLD), was compared.
• 2.2. A major difference in [³²P]phosphate incorporation was found between the ALD and PLD in a 25,000-dalton heat soluble protein.
• 3.3. The 25,000-dalton protein was purified from both the ALD and PLD.
• 4.4. The two proteins had similar amino acid composition and both contained approximately 1 mole phosphate per mole of protein.
• 5.5. The difference in their content of radioactive phosphate was determined to be due to faster turnover in the ALD.

     

Some physical and chemical properties of purified nematocysts of Hydra attenuata pall. (Hydrozoa,cnidaria)

• 1.1. A method for purifying undischarged nematocysts from Hydra and other cnidarians is described.
• 2.2. Isolated cysts (relative densities 1.22–1.24) evaginate their tubular content even after previous dehydration.
• 3.3. The cyst wall is permeable to dyes of mol. wts up to 600,000.
• 4.4. Approximately two-thirds of the cyst's dry wt are soluble proteins. Eighty per cent of them are of low mol. wt and highly anionic, presumably serving as binding sites for Ca²⁺ and Mg²⁺.
• 5.5. The other 20% includes 30 different proteins amongst them toxins and enzymes (phospholipase and little proteases but no collagenase, chitinase or hyaluronidase).

     

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