Discharge patterns of lagenar and saccular neurones of the goldfish eighth nerve: Displacement sensitivity and directional characteristics

• 1.1. The responses of goldfish lagenar and saccular neurones were analyzed for underwater sound stimulation and head vibration in three orthogonal directions.
• 2.2. Both organs show similar sound pressure and displacement sensitivity below 200 Hz, and respond to a motional stimulus component at 100 Hz.
• 3.3. Calculated directions of best sensitivity in the saggital and horizontal planes correspond with hair cell orientation maps.
• 4.4. Stimulus-response phase-angles correspond only roughly with the patterns to be expected from a simple model for hair cell stimulation.
• 5.5. Variation in the degree of coupling between hair cell cilia and the otolith, and complex three-dimensional relative motion patterns probably occur in both organs.

     

Effects of water stress on hemolymph volume,osmotic potential and chemical composition in Megetra cancellata

• 1.1. Rates of water loss in Megetra cancellata were very high compared to those reported for other xeric arthropods.
• 2.2. Hemolymph weight in hydrated animals was 43.0% of the total body weight while it was 24.7% in desiccated animals that had lost 16.1% of their body weight as water.
• 3.3. Hemolymph osmotic potential increased from 417 to 447 mOsm/kg in desiccated beetles, but osmotic regulation was evident.
• 4.4. Total hemolymph protein mass and concentration decreased in desiccated beetles while amino acid concentrations remained constant (at about 70 mM).
• 5.5. Na⁺ and −PO₄ concentrations increased in desiccated beetles.
• 6.6. Cl⁻ and K⁺ concentrations in desiccated beetles were equal to those in undesiccated beetles.

     

Thermoregulation in the cicada Platypedia putnami variety lutea (Homoptera: Tibicinidae) with a test of a crepitation hypothesis

• 1.Measurements of body temperature (T_b) in the field demonstrate that Platypedia putnami var. lutea Davis regulates T_b through behavioral mechanisms.
• 2.Thermal responses (minimum flight temperature 17.3°C, maximum voluntary tolerance-temperature 32.5°C, and heat torpor temperature 44.4°C) of P. putnami var. lutea are related to the altitude of their habitat.
• 3.Water loss rates increase with ambient temperature (T_a). Water loss rates are not significantly different at the extremes of the active T_b range but increase significantly when exposed to elevated T_a.
• 4.Acoustic activity was restricted at 6.7°C T_b range. This is similar to the lower end of the T_b range for singing measured in cicada species that produce sound with a timbal mechanism.
• 5.The use of the wing musculature to produce acoustic signals in P. putnami var. lutea does not increase the T_b range over which the species can call compared to timbal calls produced by other cicada species.

     

Identification and estimation of dopamine released from the anterior byssus retractor muscle of Mytilus californianus in response to nerve stimulation

• 1.1. Small quantities of sea water were recyclically perfused over the surface of paired anterior byssus retractor muscles of Mytilus californianus.
• 2.2. Dopamine was identified in the perfusate by thin-layer chromatography.
• 3.3. Stimulation of the pedal ganglion caused the dopamine content of the perfusate to increase.
• 4.4. A significant increment of release of dopamine was detected at stimulation frequencies above 3 Hz and increased progressively with increase in stimulation frequency.
• 5.5. The possibility of a role for dopamine as a relaxing or inhibitory neurotransmitter in Mytilus is considered in relation to the present and related evidence and to the actions of 5-HT, the probable relaxing transmitter.

     

Detection of substrate vibrations by salamanders: Frequency sensitivity of the ear

• 1.1. The sensitivity of salamander ears varies with the frequency of substrate vibration.
• 2.2. The saccule is sensitive to vibrations (20–450 Hz) and appears to perform as a simple harmonic oscillator undergoing forced resonance.
• 3.3. Saccular sensitivity appears related to the normal environment occupied by the salamander, with that of an aquatic animal being more sensitive at low frequencies than that of a terrestrial animal.
• 4.4. Prostrate adult N. viridescens can use the middle ear to transmit vibrations to the inner ear.

     

Multiple hemoglobins in Triturus cristatus: their study by analytical isoelectrofocusing

• 1.1. Electrophoretic separation of the hemoglobin of healthy adult Triturus cristatus reveals four components.
• 2.2. Isoelectric focusing of the samee hemolysates in various commercial ampholytes of different chemical composition and pH range results in the separation of eight individual hemoglobin bands.
• 3.3. The bands obtained by electrophoresis are not homogeneous as revealed by individual gel electrofocusing. They finally separate into the same eight components, as in the whole hemolysate.
• 4.4. From the above findings it is concluded that this species has not four but eight individual hemoglobin molecular forms.
• 5.5. Our results demonstrate lack of hemoglobin polymorphism in this species.

     

Hemolymph osmoregulation in three species of beetles

• 1.1. Hemolymph osmoregulation was examined in Chrysochus auratus, Tetraopes tetrophthalmus and Tenebrio molitor. These beetles differed in their water loss rates and in the availability of free water in their habitats.
• 2.2. During dehydration at comparable rates, osmotic responses were similar in these species. Osmoregulation after rehydration was better in C. auratus.
• 3.3. Osmoregulation ability was not significantly affected by the beetle's rate of dehydration.

     

Metabolic rates of Calathus melanocephalus (L.) (coleoptera,carabidae) from alpine and lowland habitats (jeløy and finse,norway and drenthe,the netherlands)

• 1.1. Metabolic rates (ml O₂/mg/hr) of three geographically separated populations of the carabid beetle Calathus melanocephalus L. (Finse and Je 10y, Norway and Drenthe, The Netherlands) were measured and compared by ANCOVA.
• 2.2. No significant relationship (P > 0.05) between metabolic rates and body weight or sex of the animals were found.
• 3.3. Individuals mostly acclimated to low temperatures by increased metabolic rates and in the opposite direction to higher temperatures. Individuals collected in early summer also showed higher metabolic rates than those caught later in the autumn.
• 4.4. Contradicting the theory of metabolic cold adaptation, beetles from The Netherlands had the highest metabolic rates, beetles from Finse intermediate rates and beetles from Jeløy the lowest rates.
• 5.5. No significant relation were found between geographical origin of the beetles and their respective chill-coma temperature.

     

A test of the thermal coadaptation hypothesis with black rat snakes (Elaphe obsoleta) and northern water snakes (Nerodia sipedon)

• 1.The thermal coadaptation hypothesis predicts that (1) ectotherms experiencing a narrow range of body temperatures in the wild will evolve to perform well over a narrow range of body temperatures and that (2) the optimal temperature for performance will be equal to the preferred body temperature of the species.
• 2.We tested the predictions of the thermal coadaptation hypothesis with black rat snakes (Elaphe obsoleta) and northern water snakes (Nerodia sipedon) because black rat snakes experience lower and more variable body temperatures than northern water snakes at our study site.
• 3.We measured swimming speed, tongue-flicking speed, and striking speed in black rat snakes, and swimming speed and tongue-flicking speed in northern water snakes.
• 4.Adult water snakes generally had narrower performance breadths and higher optimum performance temperatures than adult black rat snakes.
• 5.Performance breadths were the same for swimming, tongue flicking, and striking within adult black rat snakes, but performance optima for these behaviours differed significantly. Performance breadths differed and performance optima were the same for swimming and tongue flicking within adult northern water snakes.
• 6.The relative swimming performance of neonates of the two species was similar in breadth to that of adults, but the thermal optimum for neonate black rat snakes was higher than that of adults.
• 7.Overall, our results provided support for the thermal coadaptation hypothesis.

     

Secretory oedema in diabetic submandibular glands during parasympathetic nerve stimulation: Relationship to microvascular abnormalities in streptozotocin-treated rats

• 1.1. Submandibular secretion during parasympathetic stimulation (5 Hz) was examined in streptozotocin-diabetic and age-matched control rats.
• 2.2. At 3 weeks, but not 3 and 6 months, flow rate was initially greater than in controls, but it declined rapidly after 30 min.
• 3.3. The reduction in flow rate was associated with oedema of the gLond.
• 4.4. At 3 months, graded stimulation revealed a tendency to oedema at frequencies of 10 Hz and above.
• 5.5. Morphologically, submandibular capillary density was increased in diabetic rats.
• 6.6. Thus, in diabetes the submandibular gland appears less able to withstand continuous parasympathetic stimulation, due in part to an increase in tissue capillary area.

     

Changes in blood metabolite concentrations in response to repeated capture,anaesthesia and blood sampling in the golden perch,Macquaria ambigua

• 1.1. The major metabolic changes associated with repeated capture, aquarium transfer, anaesthesia and blood sampling were investigated in an Australian freshwater fish, the golden perch (Macquaria ambigua),
• 2.2. A compounded stress response was seen after repetition of the procedure, in which the plasma glucose rose within 3 hr and amino acid concentrations rose and the serum free fatty acids concentration fell after 24 hr.
• 3.3. Alanine was identified as an important circulating energy store in the stress response of golden perch.
• 4.4. No change was noted in the serum protein, plasma lactate or β-hydroxybutyrate concentrations, indicating that tissue damage and hypoxia were absent, and that degradation of free fatty acids did not produce metabolites excess to the requirements of gluconeogenesis and the tricarboxylic acid cycle.

     

Osmoregulatory adjustments by three atherinids (Leptatherina presbyteroides; Craterocephalus mugiloides; Leptatherina wallacei) to a range of salinities

• 1.1. Patterns of osmoregulation were studied in three species of Swan river atherinids (Leptatherina presbyteroides, lower estuarine and marine; Craterocephalus mugiloides, mid estuarine; Leptatherina wallacei, upper estuarine) over a wide range of salinities.
• 2.2. The plasma Na⁺ concentration was elevated with an increase in salinity.
• 3.3. Haematocrit and body water content decreased with acclimation to higher salinity.
• 4.4. All three species of atherinids osmotically regulated over a salinity range greater than that which these fish are reported to occur in.

     

Effects of temperature and acid stress on hatching,survival capacity,metabolism and postural reflexes in caenid mayflies (ephemeroptera)

• 1.1. Mortality was 100% at pH 3.5 over a temperature range of 10–30°C for embryos and nymphs of Caenis diminuta and C. hilaris.
• 2.2. Hatching success for both species was highest at pH values above 4.5.
• 3.3. Survival capacities were significantly higher at 20°C over a pH range of 4.0-7.2.
• 4.4. Oxygen consumption rates increase as a function of increasing temperature and reduced acidity.
• 5.5. Loss of the nymphal righting response was observed at pH 3.5. This response can be used as a behavioral assay for acid stress.

     

Adaptation in Helix pomatia neurons

• 1.1. Spike frequency adaptation has been studied on neurons of Helix pomatia subesophageal ganglia and interpreted by means of a behavioural model describing the phenomenon in neurons either silent or autorhythmic at rest.
• 2.2. At low stimulating currents the initial discharge frequency F(0) is linearly related to the current strength G.
• 3.3. In the linearity range F(0)/G each neuron was characterized by means of four model parameters: the proportionality constant between F(0) and G, the decay constant of the frequency, the inhibitory current from a single nerve impulse and the decay time constant of the inhibitory current.
• 4.4. The four parameters varied in different cells with a range of 0.18–4.98 Hz/nA, 1.02–3.85 sec, 0.05–0.95 nA and 1.74–22.33 see, respectively.
• 5.5. Experimental results have been analyzed considering inhibitory current, electrogenie sodium pump and other proposed adaptation parameters.

     

Metabolism of ingested indole compounds in the gut of three species of heteroptera

• 1.1. All kinds of indole compounds used for the experiment were more or less metabolized in the gut of Dolycoris baccarum, Eurydema rugosum and Elasmostethus humeralis.
• 2.2. The metabolic pattern of the bugs was classified into four types (I–IV) for several indole compounds in the same way as for IAA.
• 3.3. The IAA metabolites in the excreta of the three species were probably the high-molecular compound combining with such substances as amino acids, sugars or proteins to some position of indole nucleus.
• 4.4. The crude excreta of E. humeralis fed with each of several indole compounds had a significant auxin activity.
• 5.5. Most of the metabolites of indole-3-acetaldehyde in the excreta of E. humeralis had also a significant auxin activity.
• 6.6. The significance of auxin metabolism in the gut of the bugs and the difference of auxin metabolism between aphids and bugs are discussed.

     

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 effect of myo-inositol on the ability of Ditylenchus dipsaci,D. myceliophagus and Anguina tritici to survive desiccation

• 1.1. The effect of myo-inositol on the ability of three species of nematodes to survive desiccation has been studied.
• 2.2. Survival rates obtained from worms treated with an inositol bathing medium were compared with survival rates of worms treated with distilled or tapwater media.
• 3.3. Highest survival rates were found in those nematodes that were placed in an inositol solution prior to desiccation.
• 4.4. Tapwater facilitated higher revival rates than did distilled water in both D. dipsaci and D. myceliophagous.
• 5.5. No such differences were found for A. tritici.
• 6.6. The results are discussed in relation to the possible mechanisms of protection afforded by the different bathing media.

     

Properties of the transition from short-term to long-term depression in neurons of Helix pomatia

• 1.1. Synaptic short-term depression could be transferred into long term depression by repetition of series of stimuli.
• 2.2. The transition from short-term depression to long-term depression was blocked by puromycin.
• 3.3. The majority of the transition took place during resting periods between stimulus series.
• 4.4. The initiation of the transition process was 83% completed after 5 min of stimulation.
• 5.5. Short- and long-term depression were quantitatively separated into their two serial sites of origin: afferent axons and synaptic terminals.
• 6.6. Long sequences evoked periods with increased and variable EPSPs not conforming to depression.

     

The composition of the skin surface lipids of European cattle and buffalo steers

• 1.1. This study compared the composition of the skin surface lipids (SSL) of cattle (Bos taurus) and of buffalo (Bubalis bubalis) steers at the same level of feed intake in a thermoneutral environment.
• 2.2. There was about eight times less lipid per unit area of skin surface on the buffalo than on cattle.
• 3.3. The distribution of the different lipid classes in the SSL of the two breeds was different. Compared to cattle, the buffalo SSL was characterized by smaller proportions of wax ester bands 2 and 3 and triglycerides.
• 4.4. There were significant species differences in the fatty acid patterns of the individual lipid classes.
• 5.5. The results are discussed in relation to the functional attributes of sebum.