Depressed baroreceptor-cardiac reflex sensitivity during simulated diving in ducks

• 1.1. The baroreceptor-cardiac reflex was examined in unanesthetized ducks at rest and during diving. In ducks breathing air an inverse relationship between mean arterial blood pressure and heart rate was observed over the pressure range from 80cm H₂O to 290cm H₂O.
• 2.2. Increases in pressure were obtained by bolus intravenous injection of phenylephrine (PE) while the hypotension was achieved by intravenous acetylcholine (ACh).
• 3.3. The inverse relation of blood pressure and heart rate was also observed in ducks without pharmacologic intervention.
• 4.4. The baroreceptor-cardiac reflex sensitivity was -3.13 beats/min/cm H₂O in non-diving ducks and fell to -0.96 beats/min/cm H₂O with PE and ACh derived data.
• 5.5. During diving the baroreceptor-cardiac reflex sensitivity was further reduced to —0.48beats/ min/cm H₂O.
• 6.6. This finding indicates that even during the pronounced bradycardia of diving baroreceptor stimulation continues to influence heart rate.

     

Human-induced tachycardia in wild and tame mallard (Anas platyrhynchos)

• 1.1. The effect of regular handling on fear reactions was investigated in mallard (Anas platyrhynchos) by exposing six hand-reared and four wild ducks to an approaching human being and recording heart rates with an external ECG device.
• 2.2. All ducks reacted to the approach with tachycardia, but the response was significantly less in tame birds.
• 3.3. Hand-reared females showed less response than males. No sex-linked differences were apparent in the wild ducks.
• 4.4. Decreasing responses throughout the experiments were only found in tame birds.
• 5.5. Fear or stress reactions can apparently be diminished through habituation induced by regular handling.

     

The influences of individual variations in metabolic rate and tidal conditions on the response to hypoxia in Carcinus maenas (L.)

• 1.1. The oxygen consumption of crabs in normoxic and hypoxic (50% O₂) seawater was measured directly after collection.
• 2.2. The influences of size and lunar cycles were removed by scaling the data.
• 3.3. Strong negative correlations between low individual levels of O₂ consumption and the ability to compensate for hypoxia were apparent in Wicklow (subtidal) crabs.
• 4.4. Compensation for hypoxia was much greater on the flood tide than on the ebb.
• 5.5. Crabs from Roscoff (intertidal) had lower levels of compensation than those from Wicklow.
• 6.6. Size, sex and condition had no apparent effect upon these relationships.
• 7.7. Crabs acclimated to laboratory conditions have not shown this tidal variation in compensation for hypoxia.

     

Synaptic interaction between the giant interneuron and the giant motorneuron in the hermit crab,Pagurus pollicarus

• 1.1. An anatomical and physiological investigation was made of several components in the withdrawal escape response of the hermit crab, Pagurus pollicarus.
• 2.2. In the fused last thoracic-first abdominal ganglion, the giant axon (GA) synapses with the giant motor (GM) neuron which innervates the abdominal flexor muscles.
• 3.3. The synapse is unidirectional, conducting impulses only from the GA to the GM.
• 4.4. The synaptic delay time is less than 0.4 msec.
• 5.5. Concentrations of MgCl₂ and MnCl₂ which normally block chemical synapses were ineffective in interfering with GA-GM transmission.
• 6.6. The GA-GM synapse was reversibly blocked by 0.5 mM DNP.
• 7.7. It is concluded that GA-GM connection is a rectifying electrical synapse.

     

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Main serum protein of rainbow trout (Salmo gairdnerii): its biological properties and significance

• 1.1. Main serum α₁-protein (α₁P) of rainbow trout was purified and its biochemical and physico-pathological properties were studied.
• 2.2. α₁P was suggested to be a primitive protein having both properties of albumin and AFP in serum proteins of mammals according to the following results.
• 3.3. Molecular weight (75,000), two kinds of molecules (pI 4.55 and 5.05) and amino acid composition.
• 4.4. Dye- or ConA binding activity.
• 5.5. Estrogen binding activity and inhibitory effect on lymphoblastoid-forming activity.
• 6.6. Possible osmotic regulator.
• 7.7. Significant elevation of blood α₁P level in the course of hepatoma induction.

     

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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.

     

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.

     

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Comparative vitellin pattern and cladogenesis in Bacillus (insecta: Phasmatodea)

• 1.1. Under denaturing conditions (SDS-PAGE) the two natural vitellins of Bacillus taxa released five different polypeptides (A₁, A₂, A₃, B₁, B₂).
• 2.2. A₂ and B₂ bands from the two bisexual species (B. rossius and B. grandii) were found to differ; furthermore a non-vitellin yolk protein characterizes the subsepecies B.g. benazzii.
• 3.3. From gels and their densitometric scanning profiles it is clear that parental polypeptides are expressed in the thelytokous parthenogenetic hybrids (B. whitei, B. lynceorum) and in the hybridogenetic B. rossius-grandii benazzii.
• 4.4. A comparative approach of vitellin patterns appears fully adequate for tracing phylogenetic relationships and recognizing cladogenetic events.

     

Characteristics of Crassostrea virginica crystalline style chitin digestion

• 1.1. Fundamental chitin digestion characteristics of Crassostrea virginica crystalline style were investigated.
• 2.2. Optimum temperature and pH were 34°C and 4.8. respectively.
• 3.3. The colloidal regenerated chitin (0.56mol/0.5 ml: GlcNAc equivalents) was saturating under all enzyme levels encountered.
• 4.4. There was no evidence of end product inhibition, even after 100 hr incubation.
• 5.5. Calculated K_m for the chitinase complex was 1.19mM when determined using a 30 min assay, but was only 0.70 mM when determined using a 4.6 hr assay.
• 6.6. Both K_m values are lower than reported for similar assays in other molluscs and for most bacteria.
• 7.7. Effect of substrate preparation on the kinetics are discussed.
• 8.8. Eight peaks of chitinase activity were resolved by DEAE-Fractogel ion exchange chromatography.

     

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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.

     

Some properties of ATPase activity in the intact cells of yeast Saccharomycopsis fibuligera

• 1.1. The properties of ATPase activity were studied with the cells at the early stationary phase of Saccharomycopsis fibuligera.
• 2.2. Optimal pH for the activity was approximately 7.
• 3.3. The activity was stimulated by Mg²⁺.
• 4.4. The activity was inhibited by NaF, DCCD, oligomycin, NaN₃, NaVO₃, or PCMB but not inhibited by ouabain.

     

Isohematoporphyrin-diesters and diethers

• 1.1. A series of diesters of isohematoporphyrin (isoHp), from dimethyl to dioctyl were prepared according to Rimington et al. (1989b). Their optical absorption, fluorescence spectra and high performance liquid chromatography (HPLC) retention times were recorded.
• 2.2. A plot of HPLC retention time against number of C atoms in the alcohol used for esterification was approximately linear at first then rising steeply from diamyl to diocyi ester, whether a gradient elution was used or only methanol: water, 95/5, at pH 7.5.
• 3.3. Preparation of the diethers of isoHp was much more difficult than that of the corresponding derivatives of hematoporphyrin (Hp). Several different methods were investigated, varying both times and temperatures.
• 4.4. These methods included reaction of isoHp or its demethyl ester with
  • 4.1.(i) a bromoalkane in presence of anhydrous K₂CO₃;
  • 4.2.(ii) reaction with bromoalkane and Ag₂O;
  • 4.3.(iii) reaction of brominated-isoHp, prepared by using thionylbromide, with the selected alcohol, or corresponding sodium alcoholate;
  • 4.4.(iv) heating of isoHp alone with an alcohol containing 20% (w/v) H₂SCO₄ (temp. range from 45° to 118°C),
  • 4.5.(v) refluxing as in (iv) at the b.p. of the alcohol; and
  • 4.6.(vi) carrying out this reaction in refluxing ethyleneglycoldimethyl ether (b.p. 85°C) or diethyleneglycoldimethyl ether (b.p. 155°C).
• 5.5. Some diether formation was observable by all these methods but yields were small, a considerable quantity of unreacted isoHp and other products remaining.
• 6.6. Examined by HPLC, the diethers consistently afforded a forked peak which on thin layer chromatography was only resolved into two very closely associated bands by a solvent mixture carefully selected for development.
• 7.7. On elution these materials had virtually identical optical absorption and fluoresence spectra.
• 8.8. The nature of the association is discussed, atropisomers (Gottwald and Ullman, 1969) and possible stacked monomer: dimers (Abraham et al., 1963) being considered as possibilities.

     

The suitability of using cryopreservation of spermatozoa for the conservation of genetic diversity in African catfish (Clarias gariepinus)

• 1.1. The effect of cryopreservation of semen on expected Hardy-Weinberg proportions in the f₁ progeny of selected breeding pairs was evaluated.
• 2.2. Four different African catfish breeding pairs were selected, each pair displaying different heterozygous alleles at the glucose-6-phosphate isomerase-1 or 2 loci.
• 3.3. Equal volumes of ova from each female were artificially inseminated with cryopreserved or fresh semen obtained from males possessing corresponding genotypes.
• 4.4. A comparison of growth rates between f₁ groups of offspring produced from fresh and cryopreserved semen was made.
• 5.5. The G-test for goodness of fit showed no significant differences from expected Hardy-Weinberg proportions for allele frequencies obtained in the f₁ progeny.
• 6.6. The application of cryopreservation for the conservation of genetic diversity is discussed.

     

Purification and characterization of the endonuclease present in Physalia physalis venom

• 1.1. Physalia physalis nematocyst venom contains a DNase which has a non-specific endonucleolytic action.
• 2.2. This enzyme has an approximate molecular weight of 75,000 daltons.
• 3.3. The enzyme can cleave DNA over a wide pH range with an optimum near neutrality.
• 4.4. The enzyme is thermolabile and its activity can be stimulated by 80 nM NaCl or 10 mM MgCl₂.

     

The role of citrate derived from glucose in the acetylcholine synthesis in rat brain synaptosomes

• 1.1. Synaptosomes utilizing glucose or glucose plus malate produced citrate with rates of 2.4 and 7.8 nmol/hr/mg of protein, respectively.
• 2.2. (−)Hydroxycitrate increased citrate net synthesis 4 times and inhibited acetylcholine synthesis by 40%.
• 3.3. Oxygen and glucose consumption as well as lactate and CO₂ production were not changed by this inhibitor.
• 4.4. (−)Hydroxycitrate inhibited utilization of exogenous citrate in synaptosomes by 50%.

     

Domain structure of the 90-kDa stress protein: Heparin- and antibody-binding domain

• 1.1. To understand the physiological roles of the 90-kDa stress protein (HSP90), we investigated the heparin- and antibody-binding domains of the protein.
• 2.2. For heparin-binding sites, HSP90 was digested completely with trypsin, and the digests were applied to a heparin-Sepharose column and eluted with 1.0 M NaCl, followed by 8.0 M urea.
• 3.3. Each elutant was purified by a reverse-phase C₁₈ column.
• 4.4. Two peptides from the NaCl-eluted fraction and no peptide from the urea-eluted fraction were purified.
• 5.5. The purified peptides were sequenced by an automated peptide sequencer.
• 6.6. One of the heparin-binding sites was present between Leu-362 and Arg-365; another was present between Leu-645 and Lys-648.
• 7.7. These two peptides were basic and considerably hydrophilic.
• 8.8. For antibody-binding sites, HSP90 was mildly digested with trypsin, electrophoresed on SDS-polyacrylamide gels and transferred to PVDF membranes.
• 9.9. The four bound of the trypsin fragments could be sequenced with a peptide sequencer.
• 10.10. There was only one antibody-binding peptide, 38 kDa, starting from Pro-2. The others showed no cross-reactivity with the antibody and started from Leu-283.
• 11.11. Therefore, the epitopes of HSP90 are present between Pro-2 and Leu-282.
• 12.12. The heparin-binding sites are present from the middle region of the HSP90 molecule, and the antigen sites are at the N-terminal domain.