Behavioural studies on the sensitivity to sound in the desert tenebrionid beetle phrynocolus somalicus Wilke

• 1.1. Desert tenebrionid beetles of the species Phrynocolus somalicus communicate by means of sound, which they produce by tapping their abdomen against the substratum. The sound production seems to serve the purpose of attracting other individuals of the same species.
• 2.2. Experiments with stimulation of the beetles with artificially produced sound indicate that they respond to sound with frequencies in the range from about 100 to about 600 Hz, and with repetition frequencies in the range from 2–4 Hz.
• 3.3. Male and female beetles produce sound with the same repetition frequencies. Thus, the beetles cannot use the sound signals for determination of the sex of other beetles.
• 4.4. Acceleration is probably the adequate stimulus of the beetles. A protuberance between the tarsal claws might be the sound sensitive organ.

     

Functional differentiation of crayfish statocyst receptors in sensory adaptation

• 1.1. Response characteristics of tonic- and phasic-type receptors in the crayfish statocyst were investigated with intracellular recording technique.
• 2.2. They were identified to be either tonic- or phasic-type according to their response patterns to the hair deflection performed by water jet stimulation.
• 3.3. Constant depolarizing current applied intracellularly evoked long-lasting spike discharge in the tonic-type neurons and transient discharge in the phasic-type neurons.
• 4.4. These tonic- and phasic-type neurons also showed different patterns of spike discharge to depolarizing pulse stimulus of 50 msec duration.
• 5.5. On the basis of the response patterns to this pulse stimulus, it was shown that the statocyst receptor neurons consist of 46% tonic- and 54% phasic-type neurons.

     

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.

     

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.

     

Differences in response patterns of labellar chemosensilla of the fleshfly Sarcophaga bullata

• 1.1. Electrophysiological responses to NaCl, sucrose, and a complex mixture containing NaCl, glucose, fructose, phenylalanine and valine were obtained from large, medium, and small hair sensilla on the proboscis of the fleshfly Sarcophaga bullata.
• 2.2. Responses from up to three cells in each sensillum were analysed and compared across the three types of sensilla.
• 3.3. We found qualitative differences in the patterns of responses from the different hair types.

     

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.

     

Modulation of mitochondrial ATPase sensitivity to inhibitors and stimulators by diet-induced changes in membrane lipid

• 1.1. Weanling rats were fed diets differing in fatty acid composition to determine if changes induced in cardiac mitochondrial membrane structural components alter the sensitivity of mitochondrial ATPase to inhibition by oligomycin and stimulation by 2,4-dinitrophenol.
• 2.2. Mitochondrial ATPase assayed in situ within the mitochondrial membrane isolated from animals fed diets higher in fatty acids of longer chain length, exhibited greater oligomycin sensitivity and lower 2,4-dinitrophenol-induced stimulation.
• 3.3. Concomitant diet-induced changes occur in the fatty acid, composition of phosphatidylcholine, phosphatidylethanolamine and cardiolipin, increasing overall length of fatty-acyl tails in the membrane phospholipids.
• 4.4. Diet fat mediated alterations in oligomycin sensitivity of mitochondrial ATPase and membrane fatty acid chain length suggest that _vivo changes in thickness of the lipid bilayer may alter mitochindrial ATPase functions.
• 5.5. The present study extends the concept that dietary fat affects mitochondrial membrane structure and function by demonstrating that the membrane-dependent sensitivity of mitochondrial ATPase to inhibitors and stimulators may be modulated by dietary fat.

     

Organ specific changes in energy metabolism due to anaerobiosis in the sea mussel Mytilus edulis (L.)

• 1.1. Anaerobic energy metabolism was investigated in different organs of Mytilus edulis and the whole animal.
• 2.2. Succinate accumulates to high levels in most organs but remains low in the hemolymph.
• 3.3. After 16 hours propionate accumulation is observed in all organs. Experimental evidence is not sufficient yet to point out organs that produce more propionate than others.
• 4.4. Acetate is a minor end product.
• 5.5. Acetate and propionate are found in the hemolymph in amounts equal to those in the organs.
• 6.6. Animals incubated in oxygen-free seawater accumulate more end products than animals exposed to air, in the form of volatile fatty acids that are excreted into the incubation water.
• 7.7. Alanine and glutamine increase in the posterior adductor muscle. Aspartate decreases in the total animal, posterior adductor muscle and gills, while in the hemolymph decrease in alanine, asparagine, serine, threonine and proline are observed.

     

A model of sensible heat transfer across the boundary layer of animal hair coat

• 1.1.|A mechanistic model that predicts the sensible heat loss through the boundary layer of animal hair coat in relation to the climatic environment and hair coat properties is presented.
• 2.2.|The predicted sensible heat loss is positively related with hair density but is negatively related with depth of hair coat.
• 3.3.|Wind speed is a major determinant of the rate of heat loss across the boundary layer especially at low air temperatures.

     

Protein differences in cilia of mechanoreceptor hair and gill cells of the scallop Mizuhopecten yessoensis

• 1.1. In search for mechanosensory molecules the composition of the ciliary proteins of mechanoreceptor hair cells of the abdominal organ and less mechanosensitive gill cells were compared electrophoretically.
• 2.2. The hair cells and gill cilia were very similar in their polypeptide sets but differed by contents of three axonemal polypeptides with molecular weights of 125, 149 and 300 kilodaltons (kDa) and one membrane polypeptide of 159 kDa.
• 3.3. The membrane polypeptide with a molecular weight of 159 kDa represented approximately 3% of the total ciliary protein of hair cells. There was only a trace of this polypeptide in gill cilia and their membrane fraction.
• 4.4. A peculiarity of ciliary membranes of the hair cells was a high content of the 159 kDa-polypeptide, which constituted more than 20% of the total protein of membrane fraction.

     

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.

     

Serotonin or electrical optic nerve stimulation increases the photosensitivity of the Aplysia eye

• 1.1. Exposure of isolated Aplysia eyes to serotonin (10⁻⁷ M) produces large and long-lasting (hours) increases in the ERG recorded from the surface of the eye.
• 2.2. Dopamine, octopamine, or acetylcholine do not mimic the effect of 5-HT on the ERG.
• 3.3. Brief electrical optic nerve stimulation (2 Hz, 2 min) also increases the ERG and this effect also lasts a long period of time (0.5–2 hr).
• 4.4. Our results suggest that serotonin increases the response of photoreceptor cells to light and that efferent optic nerve activity may modulate photosensitivity through release of serotonin in the eye.

     

The pharmacology of insect visceral muscle

• 1.1. At least five sites-of-action must be considered in most visceral nerve-muscle preparations.
• 2.2. L-Glutamate is perhaps the excitatory neuromuscular transmitter in some organs of the viscera but not others. Proctolin is probably a neuromuscular transmitter in some organs of the viscera defined criteria for rapid chemical transmission.
• 3.3. Although 5-HT and certain catecholamines are present in insects and have a pronounced effect on visceral muscle no functional roles has been established for them.
• 4.4. Various peptides released from neuroendocrine organs probably regulate visceral muscle function. Moreover such hormonal actions seem to be mediated by cyclic AMP in some cases.
• 5.5. Recent developments in methods for detecting peptides and prospective transmitters have increased the possibility of rapid progress in insect nerve-muscle pharmacology.

     

The oxidation-reduction activity of organs in Sorex araneus Linnaeus, 1758

• 1.1. Examination was made of variations in the oxidation-reduction activity of organs of the common shrew, identified by the chemiluminescence method, from the seasonal and age aspect.
• 2.2. Differences were found in the level of investigated activity depending on the given function in the organism, and four types of organs were distinguished, differing in respect of length of the period during which the given organ was highly active.
• 3.3. The investigated activity of all the organs examined in young adult shrews abruptly increased in autumn.
• 4.4. No correlation was found between the weights of organs and their investigated activity.
• 5.5. Variations in oxidation-reduction activity were compared with the variations, previously examined. in the activity of metabolically active substances in the organs of shrews in relation to seasonal and age variations in the metabolism of animals of this species.

     

Target localization in different luminous environments

• 1.1. A model for target localization, developed for Squilla mantis, was modified for two other stomatopod species.
• 2.2. While Squilla live in dim light, Odontodactylus scyllarus live in medium bright and Gonodactylus in extremely bright habitats.
• 3.3. The critical zones for prey capture, selected by a decision neuron, were identified. These are bifurcated, stretching out for long distances.
• 4.4. A much more limited critical zone is obtained by introducing a strike command neuron, which receives inputs only from the two central ommatidia in the middle band instead of from all six as does the decision neuron.
• 5.5. The results correspond to the different behavior patterns in prey capture for the different species.

     

Morphology and electrophysiological characteristics of caudodorsal cells of Lymnaea stagnalis in dissociated cell culture

• 1.1. The neuroendocrine caudodorsal cells (CDCs) of Lymnaea stagnalis are a network of about 100 electrotonically coupled neurones. The CDCs release multiple peptides, including an ovulation hormone, during a period of electrical activity, the CDC-discharge.
• 2.2. In isolated brains, a similar period of electrical activity (the afterdischarge) can be induced in all CDCs by a period of intracellular repetitive suprathreshold stimulation of one CDC.
• 3.3. In order to study the regulation of this electrical behaviour in the absence of electrical interactions and in a controlled environment, experiments were performed on CDCs in dissociated cell culture.
• 4.4. Methods for isolation and cell culture are described. Cell cultures had long-term viability and outgrowth of neurities occurred under serum-free conditions.
• 5.5. CDCs in cell culture maintained their capability of producing afterdischarges upon electrical stimulation. Cells in culture appeared more excitable than cells in the intact isolated brain.
• 6.6. The characteristic responses of CDCs in intact isolated brains to acetylcholine and FMRFamide were preserved in cultured CDCs. Both agents induced a transient hyperpolarization of the membrane, inexcitability and inhibition of an ongoing discharge.
• 7.7. In experiments where isolated CDCs were closely apposed, but physically separate, it was found that an afterdischarge in one CDC could induce a discharge in the other CDC.
• 8.8. These results confirm previous results which showed that an excitatory factor is released from the brain during the afterdischarge (Ter Maat et al., 1988, Brain Res., 43, 77–82), and demonstrate that this excitatory factor is released from the CDCs themselves.

     

Frequency response characteristics of primary and secondary neurons in the electrosensory system of the thornback ray

• 1.1. Recordings were made from primary afferent and secondary neurons in the electrosensory system of the thornback ray.
• 2.2. The frequency response characteristics of these neurons were determined during sinusoidal modulation of uniform external fields.
• 3.3. The form or the filter curves was similar in all primary and secondary cells, with a maximum amplitude of response occurring at a modulation frequency of 4 Hz.
• 4.4. Secondary neurons showed an increased gain at low stimulus amplitude, and saturated at a much lower level than primary afferents.

     

Comparison of metabolic effects of EGF,TGF-α, and TGF-β1 in primary culture of fetal bovine myoblasts and rat L6 myoblasts

• 1.1. Comparative studies of EGF, TGF-α, and TGF-βl action on the synthesis of DNA and cellular proteins in rat L6 myogenic cells and fetal bovine myoblasts demonstrated considerable differences between particular growth factors, dependent on dose and target cells.
• 2.2. Among examined growth factors only EGF exerted mitostimulatory action, more pronounced at lower concentrations. EGF, progressively with dose, stimulated protein synthesis much more effectively in fetal bovine myoblasts than in L6 cells.
• 3.3. The dynamics of stimulation of protein synthesis by TGF-α was greater than by EGF in both examined types of cell cultures.
• 4.4. The maximal response of fetal bovine myoblasts to TGF-α in a concentration of 100 ng/ml reached 370%, whereas EGF in a 10 times higher concentration stimulated protein synthesis only to 123% of control.
• 5.5. In contrast to EGF, TGF-α significantly inhibits DNA synthesis. Inhibition of the mitogenic response with simultaneous stimulation of protein synthesis by TGF-α may indicate changes toward cell differentiation.
• 6.6. TGF-β 1 in smallest concentration inhibits both DNA and protein synthesis. The suppressive action of TGF-β 1 was more distinct in fetal bovine myoblasts than in the L6 cell line.
• 7.7. Increasing concentrations of TGF-β l diminished its inhibitory effect, even leading to stimulation of protein synthesis at higher doses in L6 myoblasts.

     

A relationship between circulating natural glucocorticoids and the mechanical responses of the heart in atricial and precocial rodents

• 1.1. A comparison was made of the mechanical performance of heart muscle from mouse, an atricial mammal, with corticosterone as glucocorticoid and spiny mouse (Acomys cahirinus), a precocial mammal, with cortisol as glucocorticoid.
• 2.2. Force-frequency responses were negative in mouse and positive in spiny mouse.
• 3.3. During recovery, there was a gradual increase and an overshoot in the mouse, while in the spiny mouse there was an initial enhanced response, diminishing gradually with time.
• 4.4. High calcium concentration inhibited contractile tension in mouse heart, while it was positively inotropic in spiny mouse heart. Changes in the concentration of calcium did not change the patterns of force-frequency response.
• 5.5. Lowering the experimental temperature increased the time course and amplitude of the tension curve. However, various parameters exhibited different temperature sensitivity.
• 6.6. There was a significant difference in the levels of circulating cortisol between male and female spiny mice.
• 7.7. It is proposed that the differences in the mechanical responses of mouse and spiny mouse hearts may be explained in terms of the effects of the specific glucocorticoid hormone on the development of the sodium-calcium exchanger.

     

Skin blood flow in the Wistar-Kyoto rat and the spontaneously hypertensive rat

• 1.1. Using laser Doppler techniques in man, we have previously demonstrated differences in skin blood flow properties at sites with primarily nutritive (NUTR) perfusion, such as the elbow or knee, as compared to sites such as the finger pulp, with predominantly arteriovenous anastomotic (AVA) perfusion.
• 2.2. Basal and heat stimulated flow is greater at AVA sites. In man, blood pressure changes are reflected primarily by changes at AVA rather than NUTR sites.
• 3.3. These blood pressure induced changes affect the red blood cell velocity (VEL) component at AVA sites more than microvascular volume (VOL).
• 4.4. Given these findings in man, we decided to compare skin blood flow properties in a suitable animal model.
• 5.5. We chose the Wistar-Kyoto (WKY) and Spontaneously Hypertensive Rat (SHR) strains, in view of the marked difference in systemic blood pressure in these two related strains.
• 6.6. Skin blood flow varied considerably at different skin sites in the rats. Skin sites with hair covering, on the back and at the base of the tail, showed low basal and heat stimulated blood flow.
• 7.7. In contrast, the plantar surface of the paw behaved similarly to the finger or toe pulps in man, with 3–4-fold higher basal flow than the hair covered areas and a 7–8-fold rise with local heating to 44°C.
• 8.8. Furthermore, there was a 25% greater blood flow at the plantar paw surface in the SHR rats as compared to the WKY rats, corresponding to the 25% higher systemic blood pressure in these animals.
• 9.9. The heat induced increase in flow at the plantar surface of the paw was primarily a result of a marked increase in VEL rather than VOL.
• 10.10. The higher flow at this site in SHR as compared to WKY rats was likewise ascribable to an increase in VEL, VOL being equivalent in the two strains.