bluuebunny/crossref_metadata_2025_split huggingface dataset:
Horomonal control of larval diapause and metamorphosis of the southwestern corn borer Diatraea grandiosella
Authors: Yin C. M. , Chippendale G. M. 
Published: April 2021

ABSTRACT
Changes in haemolymph juvenile hormone (JH) concentrations of larvae of the southwestern corn borer, Diatraea grandiosella, were used to estimate the activity of the corpora allata. The haemolymph of penultimate nondiapause instars contained a maximum JH titre of 3000 Galleria units (GU)/ ml, whereas the titre in the final instar had dropped to 140 GU/ml within 6 h of the ecdysis and continued to remain low. Corpora allata of last-stage nondiapause larvae therefore remain inactive. Some signal other than a rapidly declining JH titre in mid-instar triggers the release of ecdysiotropin because the pupal moulting cycle did not become independent of the brain and ecdysial glands until 4·25 and 4 ·75 days after the final larval ecdysis, respectively. Newly diapaused immaculate larvae had a haemolymph JH titre of ca. 1500 GU/ml. Three JH mimics applied to early last stage non-diapause larvae induced the formation of the immaculate diapause morph. The mimics did not activate the recipient’s corpora allata, but elevated the functional JH concentration, each having a different intrinsic hormonal activity. Threshold JH concentrations which control larval ecdyses, diapause maintenance, and metamorphosis are presented.
Studies on the mechanism of fluid secretion by isolated salivary glands of Calliphora
Authors: Berridge M. J. , Lindley B. D. , Prince W. T. 
Published: April 2021

ABSTRACT
Previous studies on isolated salivary glands of Calliphora have concentrated on the role of cyclic AMP and calcium in mediating the action of 5-hydroxytryptamine (5-HT) (Berridge, 1970; Berridge & Prince, 1972a, b; Prince & Berridge, 1972, 1973; Prince, Berridge & Rasmussen, 1972). Electrophysiological studies suggested that cyclic AMP stimulated a cation pump whereas calcium increased anion permeability. The role of calcium in altering membrane permeability has been confirmed by measuring the resistance of both the apical and basal membranes during the action of 5-HT (Berridge, Lindley & Prince, 1975 a). These resistance measurements have been used to develop a model which adequately accounts for all the potential changes normally observed during the action of 5-HT. The basis of this model depends on having an active pump on the apical membrane which transports potassium from the cell into the lumen. Chloride follows passively. Potassium and chloride transported from the cell into the lumen is replaced by a passive influx of these ions across the basal plasma membrane into the cell.
A method for recording the respiratory and hatching movements of the chick embryo
Authors: Dawes C. M. 
Published: April 2021

ABSTRACT
An artificial air space was made in the narrow end of the pipped egg by separating the shell membranes from the shell. The respiratory and hatching movements of the embryo set up pressure changes within the artificial air space and these were recorded up until the moment when the chick emerged from the shell. Random movements appeared to be inhibited during the period of hatching. The ways in which the presence of the artificial air space might affect the embryo have been discussed.
Some Advanced Flight Manoeuvres of Bats
Authors: Norberg Ulla M. 
Published: April 2021

ABSTRACT
Two manoeuvres in bats are described: rolls through 180°, in Nyctalus noctula, and a series of sideslips in Otomops martiensseni. These manoeuvres cause a rapid loss of height. They are initiated by pronation of one wing and supination of the other. After the roll, when the bat is in an upside down position, the lift force of the wings is directed downwards, causing a tight turn downwards (apparently for insect catching). During sideslip the body drag of the bat is increased. This reduces the total lift/drag ratio, thus steepening the equilibrium gliding angle.
Responses of trout gill ion transport systems to acute acidosis
Authors: Kerstetter T. H. , Mize R. 
Published: April 2021

ABSTRACT
The response of rainbow trout Na+ and Cl− uptake systems to acute acidosis was tested by slow infusion of lactic acid into anaesthetized animals. Depression of blood pH by 0·4 pH unit had no effect on influx rates for either ion, and we conclude that gill ion uptake systems do not respond rapidly to blood pH changes.
Polarization variations induced by high hydrostatic pressures in the isolated frog skin as related to the effects on passive ionic permeability and active Na+ transport
Authors: Pequeux A. 
Published: April 2021

ABSTRACT
The effects of a wide range of hydrostatic pressures (from 50 to 1000 kg/cm2) have been investigated on the spontaneous potential difference (PD), the short-circuit current (SCC) and the activity of the membrane ATPases of the isolated abdominal skin from the frog Rana temporaria L. Two types of variations in PD are induced by pressure changes: short and transient potential variations which appear to be related to the pressure change (compression and decompression) and lasting variations which persist as long as pressure is applied and whose nature appears to be related to the pressure magnitude.
Long-lasting potential changes have particularly been investigated. At pressures lower than 500 kg/cm2, the skin potential increases while a pressure over 500–600 kg/cm2 induces a depolarization. Both variations consecutively occur at 500 + 100 kg/cm2. These effects of pressure have been shown to be reversible up to about 800 kg/cm2.
The question of the origin of the potential changes is discussed and it is proposed that the lasting hyperpolarization results from an effect on the passive permeabilities to Na+, K+ and Cl- ions inducing in turm a secondary readjustment (stimulation) of the Na+ active transport while the depolarization at high pressures reflects a direct inhibition of the Na+ pump.
These interpretations are supported by experimental data on the effects of pressure on the short-circuit current and on the activity of the skin (Na+ + K+) ATPase.
Ultrasonic Clicks Produced by the Peacock Butterfly: A Possible Bat-Repellent Mechanism
Authors: Møhl Bertel , Miller Lee A. 
Published: April 2021

ABSTRACT
Torpid peacock butterflies (Inachis io) produce intense ultrasonic clicks that startle captive vespertilionid bats (Plecotus auritus and Pipistrellus pipistrellus). The clicks occur as the wings are opened and are generated by a stiff portion of wing membrane between the costal and subcostal veins near the base of the forewing. The power spectrum of a click matches the most sensitive area of a bat’s audiogram. Clicks may serve as acoustic equivalents of the attack-retarding eyespot display in the same species.
Elastic energy storage in primary feather shafts
Authors: Pennycuick C. J. , Lock A. 
Published: April 2021

ABSTRACT
It is proposed that the kinetic energy of a pigeon’s wing, in hovering or slow forward flight, is transferred to the air at the end of the downstroke by a mechanism involving temporary storage of additional energy in bent primary feather shafts. Estimates of the amounts of energy which can be stored and recovered in this way are compared with the requirements of the theory. The hypothesis is not rejected, as far as present evidence goes. If it is correct, high-velocity pulses of calculable magnitude should be detectable in the wake.
The influence of various factors on fluid secretion by in vitro salivary glands of ixodid Ticks
Authors: Kaufman W. 
Published: April 2021

ABSTRACT
Salivary glands of the female ixodid tick, Dermacentor andersoni, secrete fluid in vitro when bathed in a slightly modified version of the mammalian tissue culture medium ‘TC 199’. Rate of salivation in vitro increases with progression of feeding, but there is no comparable increase in dry weight of the salivary glands during the early phase of engorgement. Engorged ticks secreted at only 25 % the rate of 90−250 mg ticks, indicating that salivary gland degeneration has already begun in the very early post-engorgement stage. A salivary gland stimulating factor can be detected in the nervous system but not in other tissues. Male salivary glands secrete at only 1/20th the rate of female glands. Thus males probably do not use their salivary glands as osmoregulatory organs. From the uniform lack of response to ACh and uniform response to DA in 7 ixodid tick species, it is suggested that the control of salivation is similar throughout the ixodid family.
Anatomy and development of the somatic musculature of the nematode Ascaris
Authors: Stretton A. O. 
Published: April 2021

ABSTRACT
The musculature of the nematode Ascaris has been studied by the examination of serial sections by light and electron microscopy. The muscle cells of nematodes are unusual in that they send branches to the neurones in contrast to the more usual situation in other animals where neurones send processes to the muscles. The neuromuscular synapses are made at the ends of the arms. Muscle cells receive multiple innervations and perform integration of the combined inputs. The action potentials are initiated near the ends of the arms so each arm acts as an integrative centre. It is shown that it is common for a muscle cell to have several arms, raising the possibility that each arm may integrate different combinations of neuronal inputs.
In the second larval stage the total number of muscle cells is 83. The adult has approximately 5 × 104 muscle cells. The very striking increase in cell numbers of the musculature is not matched by a corresponding increase in the number of cells in the nervous system. A model for the way in which a small number of neurones can co-ordinate the activity of an increasing population of muscle cells is presented.
The Coordinate Roles of Branchial Nerve Activity and Potassium in the Stimulation of Ciliary Activity in Mytilus Edulis: Observations with Phenoxybenzamine, Bromolysergic Acid and Fluorescence Histochemistry
Authors: Paparo Anthony A. 
Published: April 2021

ABSTRACT
Potassium concentrations in excess of 30 mm increase the rate of beating of lateral cilia on the gill of Mytilus edulis. Cilioexcitation produced by low frequency (5 beats/s) electrical stimulation was potentiated with potassium but blocked with bromolysergic acid (a serotonergic inhibitor). Cilio-inhibition produced by high frequency (50 beats/s) stimulation was decreased with potassium and phenoxybenzamine (a dopaminergic inhibitor). Phenoxy-benzamine enhanced the cilioexcitation produced by potassium. Potassium doses incapable of maintaining a basal rate of beating (&lt; 30 mm) could increase ciliary activity if phenoxybenzamine was also added. After transection of the branchial nerve, the yellow-fluorophore (serotonergic storage) and cilioexcitatory effect of potassium gradually decrease.
This study shows that the potassium effect on ciliary activity (a) increases with low frequency nerve stimulation, presumably through the release of serotonin and (b) decreases with high frequency nerve stimulation, presumably through the release of dopamine.
Proline Inhibition of A Sea Anemone Alarm Pheromone Response
Authors: Howe Nathan R. 
Published: April 2021

ABSTRACT
L-proline, by itself or in animal tissue extracts, inhibits the response of the sea anemone Anthopleura elegantissima to the alarm pheromone, anthopleurine. The effect of proline is mediated by a receptor that is specific for the structure and configuration of the part of the L-proline molecule containing the carboxyl and imino groups. Proline inhibition is competitive, in the sense that the effects of a given proline concentration can be overridden by an increase in anthopleurine concentration. The magnitude of proline inhibition increases with proline concentration and decreases as the duration of exposure to proline increases. Neither the final conducting system mediating the alarm response nor the responding muscles are inhibited by proline. Inhibition presumably occurs at or soon after the level of anthopleurine receptors. Proline inhibition may resolve the potential conflict between Anthopleura’s mutually exclusive feeding and alarm pheromone responses.
A ‘TEA+−Insensitive’ Mutant with Increased Potassium Conductance in Paramecium Aurelia
Authors: Satow Youko , Kung Ching 
Published: April 2021

ABSTRACT
A single-gene mutant of Paramecium aurelia is analysed electrophysiologically. (a) The regenerative Ca-response, triggered by small or moderate current, was smaller and slower in the mutant than in wild type. (b) Input resistance of the mutant membrane is about half of that of wild type bathed in various solutions. This is true for the zero-current input resistance and the chord resistance measured with high depolarizing current, (c) Membrane resistance of the mutant measured with hyperpolarizing currents is smaller than that of wild type only when K+ is the major external cation, (d) Internally applied TEA+ or externally applied Ba+ increases the membrane resistance of the mutant to that of wild type similarly treated. We conclude that the mutant has an increased K conductance.
Spirillum Swimming: Theory and Observations of Propulsion by the Flagellar Bundle
Authors: Winet H. , Keller S. R. 
Published: April 2021

ABSTRACT
The hydrodynamics and energetics of helical swimming by the bacterium Spirillum sp. is analysed using observations from medium speed cine photomicrography and theory. The photographic records show that the swimming organism’s flagellar bundles beat in a helical fashion just as other bacterial flagella do. The data are analysed according to the rotational resistive theory of Chwang & Wu (1971) in a simple-to-use parametric form with the viscous coefficients Cs and Cn calculated according to the method of Lighthill (1975). Results of the analysis show that Spirillum dissipates biochemical energy in performing work against fluid resistance to motion at an average rate of about 6 × 10−8 dyne cm s-1 with some 62−72 % of the power dissipation due to the non-contractile body. These relationships yield a relatively low hydromechanical efficiency which is reflected in swimming speeds much smaller than a representative eukaryote. In addition the Cn/Cs ratio for the body is shown to lie in the range 0·86−1·51 and that for the flagellar bundle in the range 1·46−1·63. The implications of the power calculations for the Berg & Anderson (1973) rotating shaft model are discussed and it is shown that a rotational resistive theory analysis predicts a 5-cross bridge M ring for each flagellum of Spirillum.
Neuronal Basis of A Sensory Analyser, the Acridid Movement Detector System
Authors: Rowell C. H. Fraser , O’shea Michael 
Published: April 2021

ABSTRACT
The Lobular Giant Movement Detector neurone (LGMD) of Schistocerca responds with spikes when small areas of the visual field change in luminance. Previous work has shown that changes of ± 1 log10 unit are enough to produce maximal ON and OFF responses. Using a 5° test area, it is shown that the number of spikes generated by such a stimulus depends on the luminance of the surrounding area. When the surround is dark, the response is maximal; when it is brightly lit, the response is minimal. Intermediate intensities produce intermediate values of response. A × 2 change in response is produced by about 3 log10 units change in surround intensity. A bright annulus, with diameters of 10·5° and 25·8°, inhibits both ON and OFF responses when concentric with the 5° test area, but not when it is 30° eccentric to the test area. The inhibitory effect shows no decrease after 4 min. These results are interpreted to indicate a tonic lateral inhibitory network, sited peripherally in the optic lobe prior to the divergence of the separate ON and OFF channels found in the projection from the medulla to the LGMD. It is probably identical with that described for the lamina by previous workers.
Neuronal mechanisms for object discrimination in the weakly electric fish Eigenmannia virescens
Authors: Feng Albert S. , Bullock Theodore H. 
Published: April 2021

ABSTRACT
The peripheral sensory basis for object discrimination was investigated in the weakly electric fish Eigenmannia virescens. Single unit recordings were made from the primary afferent fibres in the posterior branch of the anterior lateral line nerve while the local electric field (self-generated and simulated) was modified by external resistance and capacitance shunts. Both fibre types (probability and phase coders) responded differentially to capacitance and resistance shunts of equivalent impedance. The degree of response differentiation between the two shunting conditions varied with the intensity of the electrical stimulus at the receptor. These data suggest that the primary electroreceptors can discriminatively encode the two electrical characteristics of ‘objects’. However, since the response of primary electroreceptors also varied with the spatial orientation of the shunting electrodes, central structures must play an important role in object discrimination.
Correlation of the startle reflex and Mauthner cell auditory responses in unrestrained goldfish
Authors: Zottoli Steven J. 
Published: April 2021

ABSTRACT
Stainless-steel electrodes were implanted near the left or right Mauthner cells (M-cells) of goldfish to determine if these cells can initiate the startle reflex evoked by a brief sinusoidal sound stimulus. Recordings of the M-cell extracellular spike were obtained for the duration of 10 experiments. Fish with chronic implants were allowed to free-swim and exposed to at least 10 consecutive sound stimuli consisting of 2 cycles of 200 Hz. Seventy-three startle responses were analysed. In 34 cases the implanted M-cell electrode was contralateral to the contracting musculature, and in each of these cases, a M-cell spike preceded the EMG response by 1· 1−2· 1 ms. In the remaining 39 cases the electrode was ipsilateral to the active musculature, and the M-cell only fired in one of these trials. There were no startle responses and no M-cell firings in an additional 52 tests. Since the M-cell activates contralateral motoneurones, the results indicate it is responsible for initiation of the startle reflex.
Regulation of rectal secretion in saline-water mosquito larvae living in waters of diverse ionic composition*
Authors: Bradley T. J. , Phillips J. E. 
Published: April 2021

ABSTRACT
Larvae of the saline-water mosquito Aedes campestris were adapted to three waters, all having an osmotic concentration of 700 mOsm, but differing in ionic ratios. The (Na + Mg) SO4 medium was much more toxic than the NaHCO3 or the NaCl media. Ionic and osmotic concentrations of haemolymph and rectal secretion were measured in larvae adapted to all three media. The ratio of ionic concentrations in the rectal secretion reflected those in the external medium to which the larvae had been adapted, with the exception of SO42−, which was possibly replaced by HCO3− in the secretion. These differences in rectal fluid composition persisted even though all ligated recta were bathed in the same artificial haemolymph. The Malpighian tubules were found to be the major site of SO42− excretion. In media containing high levels of Na+, Mg2−, K+, Cl− and HCO3−, the rectum secreted a hyperosmotic fluid containing these ions at concentrations several times greater than those found in the haemolymph. These data provide the basis for speculation on the functioning of anal papillae in waters of diverse chemical composition.
The effect of external salinity on drinking rate and rectal secretion in the larvae of the saline-water mosquito Aedes taeniorhynchus*
Authors: Bradley T. J. , Phillips J. E. 
Published: April 2021

ABSTRACT
The drinking rate of the saline-water mosquito larva Aedes taeniorhyncus (100 nl. Mg−1. h−1) is unaffected by the salinity of the external medium, but is directly proportional to the surface area of the animal. Haemolymph Na+, Mg2+, K+, Cl−, SO42− and osmotic concentrations were measured in larvae adapted to 10%, 100% and 200% sea water and were found to be regulated within a narrow range. With the exception of potassium, ionic concentrations in rectal secretion were found to increase with increasing concentrations of the sea water in which larvae were reared. The osmotic concentration of rectal secretion was unaffected by changes in haemolymph osmotic concentration but did rise when sodium or chloride concentrations of the haemolymph were increased. High levels of these ions also stimulated the rate of fluid secretion. Transport of chloride and sodium by the rectum exhibits the kinetics of allosteric rather than classical enzymes.
The Effect of Calcium on Cadmium Uptake by the Shore Crab Carcinus Maenas
Authors: Wright D. A. 
Published: April 2021

ABSTRACT
The accumulation of cadmium by the shore crab Carcinus maenas (L.) is to some extent dependent upon the calcium concentration of the external medium. This effect is apparently independent of the overall salinity of the external medium and may at least partially explain previous reports of a ‘salinity effect’.
Haemolymph cadmium has a highly significant inverse relationship with the external calcium concentration. This effect is less obvious with other tissues, although the whole body cadmium has a significant inverse correlation with the external calcium concentration. Both the haemolymph and gill show a significant inverse relationship between tissue cadmium and calcium.
When postmoult animals were exposed to 20 μ-mol l− 1 Cd in 100% s.w., high concentrations of both calcium and cadmium appeared in the haemolymph. Postmoult animals in cadmium-free sea water generally had a lower haemolymph calcium concentration than intermoult animals, and the rise in haemolymph calcium seen in the presence of cadmium may indicate some degree of competition for ‘deposition sites’ between these two metals.
Swimbladder Permeability to Oxygen
Authors: Lapennas George N. , Schmidt-Nielsen Knut 
Published: April 2021

ABSTRACT
The permeability of the swimbladder to gas was measured as the conductance to oxygen in seven species of fish. The low over-all conductance resides in the low diffusion constant, K, of the middle layer of the wall (submucosa) while the outer and inner layers (tunica externa and mucosa) have diffusion constants similar to other vertebrate tissues.
The low diffusion constant is due to a low diffusion coefficient, D (not to a low-solubility coefficient), apparently caused by multiple layers of very thin (about 0.02 μm) and broad (up to 100 μm) crystals, clearly identifiable in electron micrographs, and presumably consisting of guanine. Crystals occupy only a small fraction of tissue volume. They are flexible as a consequence of their extreme thinness, and subject to being elaborately folded when the mucosa and submucosa of the secretory part of the swimbladder is contracted during reabsorption of gas. The low conductance of the swimbladder wall reduces the metabolic energy needed to maintain swimbladder volume.