bluuebunny/crossref_metadata_2025 huggingface dataset:
Pectoralis Muscle Force and Power Output During Different Modes of Flight in Pigeons (Columba Livia)
Authors: Dial Kenneth P. , Biewener Andrew A.
Published: April 2021

In vivo measurements of pectoralis muscle force during different modes of free flight (takeoff, level flapping, landing, vertical ascending and near vertical descending flight) were obtained using a strain gauge attached to the dorsal surface of the delto-pectoral crest (DPC) of the humerus in four trained pigeons (Columbalivia). In one bird, a rosette strain gauge was attached to the DPC to determine the principal axis of strain produced by tension of the pectoralis. Strain signals recorded during flight were calibrated to force based on in situ measurements of tetanic force and on direct tension applied to the muscle’s insertion at the DPC. Rosette strain recordings showed that at maximal force the orientation of tensile principal strain was −15° (proximo-anterior) to the perpendicular axis of the DPC (or +75° to the longitudinal axis of the humerus), ranging from +15 to −25° to the DPC axis during the downstroke. The consistency of tensile principal strain orientation in the DPC confirms the more general use of single-element strain gauges as being a reliable method for determining in vivo pectoralis force generation. Our strain recordings show that the pectoralis begins to develop force as it is being lengthened, during the final one-third of the upstroke, and attains maximum force output while shortening during the first one-third of the downstroke. Force is sustained throughout the entire downstroke, even after the onset of the upstroke for certain flight conditions. Mean peak forces developed by the pectoralis based on measurements from 40 wingbeats for each bird (160 total) were: 24.9±3.1N during takeoff, 19.7±2.0N during level flight (at speeds of about 6–9 ms−1 and a wingbeat frequency of 8.6±0.3Hz), 18.7±2.5N during landing, 23.7±2.7N during near-vertical descent, and 26.0±1.8N during vertical ascending flight. These forces are considerably lower than the maximum isometric force (67N, P0) of the muscle, ranging from 28% (landing) to 39% (vertical ascending) of P0. Based on estimates of muscle fiber length change determined from high-speed (200frames s−1) light ciné films taken of the animals, we calculate the mass-specific power output of the pigeon pectoralis to be 51 W kg−1 during level flight (approximately 8ms−1), and 119W kg−1 during takeoff from the ground. When the birds were harnessed with weighted backpacks (50% and 100% of body weight), the forces generated by the pectoralis did not significantly exceed those observed in unloaded birds executing vertical ascending flight. These data suggest that the range of force production by the pectoralis under these differing conditions is constrained by the force–velocity properties of the muscle operating at fairly rapid rates of shortening (4.4 fiberlengths s−1 during level flight and 6.7fiberlengths s−1 during takeoff).
Tail Muscle Activity Patterns in Walking and Flying Pigeons (Columba Livia)
Authors: Gatesy Stephen M. , Dial Kenneth P.
Published: April 2021

The electrical activity of major caudal muscles of the pigeon (Columba livia) was recorded during five modes of aerial and terrestrial locomotion. Tail muscle electromyograms were correlated with movement using high-speed cinematography and compared to activity in selected muscles of the wings, legs and trunk. During walking, the pectoralis and most tail muscles are normally inactive, but levator muscle activity alternates with the striding legs. In flight, caudal muscles are phasically active with each wingbeat and undergo distinct changes in electromyographic pattern between liftoff, takeoff, slow level flapping and landing modes. The temporal flexibility of tail muscle activity differs significantly from the stereotypic timing of wing muscles in pigeons performing the same flight modes. These neural programs may represent different solutions to the control of flight surfaces in the rapidly oscillating wing and the relatively stationary caudal skeleton. Birds exhibit a novel alliance of tail and forelimb use during aerial locomotion. We suggest that there is evidence of anatomical and functional decoupling of the tail from adjacent hindlimb and trunk muscles during avian evolution to facilitate its specialization for rectricial control in flight.
Giant Fiber Activation of an Intrinsic Muscle in the Mesothoracic Leg of Drosophila Melanogaster
Authors: Trimarchi James R. , Schneiderman Anne M.
Published: April 2021

Cinematographic analysis reveals that an important component of the light-elicited escape response of Drosophila melanogaster is the extension of the femur–tibia joint of the mesothoracic leg. During the jumping phase of the response, this extension works synergistically with extension of the femur. Femur extension is generated by contraction of the tergotrochanteral muscle (TTM), one of four previously described escape response muscles.

Femur–tibia joint extension in the mesothoracic leg has been thought to be controlled by contraction of the tibial levator (TLM), an intrinsic leg muscle. We investigated the activation of the TLM during the escape response. Electrical stimulation of the giant fiber interneuron that mediates the escape response results in activation of the TLM with a latency of 1.46±0.02ms. The TLM is innervated by a motor neuron (TLMn) with a large cell body in the mesothoracic ganglion. The TLMn has extensive arborizations in the lateral mesothoracic leg neuromere and has a prominent medially directed neurite. To investigate possible presynaptic inputs activating the TLMn during the escape response, we analyzed the muscle responses of two mutants, giant fiber A1 and bendless. Our analysis suggests that the TLMn is activated by a novel pathway.
Discontinuous Carbon Dioxide Release in the Eastern Lubber Grasshopper Romalea Guttata and its Effect on Respiratory Transpiration
Authors: Hadley Neil F. , Quinlan Michael C.
Published: April 2021

Ventilatory patterns were examined in the Eastern lubber grasshopper Romalea guttata and correlated with respiratory transpiration. Discontinuous release of CO2 was only observed in quiescent individuals during their scotophase. Interburst periods (spiracles closed) alternated with bouts of CO2 emission and O2 consumption (burst phase); no true ‘flutter’ phase was observed. Cycle duration decreased with increasing temperature in both hydrated and dehydrated individuals. Metabolic rates for this large, sluggish species are lower than those reported for smaller and/or more active grasshoppers. Water loss rates fell within an expected range of values for arthropods from mesic environments. Respiratory transpiration accounted for only 1.9–3.9% of the total water loss between 15 and 30 °C and for only 7% of the water loss during the burst phase of the cycle. These data indicate that the cyclic release of CO2 in this adult insect does not result in substantial savings of water.
Identification of β-Like Adrenoceptors Associated With Bioluminescence in the Sea Pansy Renilla Koellikeri
Authors: Awad Edward W. , Anctil Michel
Published: April 2021

Previous studies have reported pharmacological and biochemical evidence for the involvement of adrenergic substances in the regulation of neuroeffector activities in the bioluminescent cnidarian Renilla koellikeri (Cnidaria, Anthozoa). Therefore, direct radiobinding assays were developed to identify and characterize β-adrenergic binding in membrane preparations from this species, using the two β-antagonists [3H]dihydroalprenolol and [3H]CGP12177 as tracers. In addition, the effect of various β-adrenergic agents on luminescence was examined. Binding of the radioligands at 25°C was rapid, reversible, saturable and specific. Saturation studies revealed the presence of two different and independent classes of binding site, site1 and site2, in the body of the colony (rachis). In contrast, homogeneous populations of binding sites corresponding to site1 were detected in autozooid polyps and to site2 in the peduncle. The pharmacological profile of β-adrenergic binding in R. koellikeri membrane preparations displayed properties consistent with the presence of two sites and followed a pattern similar to β2-and β1-adrenergic receptor subtypes for site1 and site2, respectively. Bioluminescence in polyps was induced by β-agonists as well as by one β1-selective antagonist, atenolol, and was blocked by several β-blockers including (±)CGP12177. The specificity pattern of the physiological effect of β-adrenergic drugs on luminescence mirrors that of the radioligand interaction with site1. This suggests that radioligand binding to site1 represents binding to the receptor that mediates luminescence excitation in R. koellikeri. Blockade of the luminescent responses to site1 agonists by isotonic MgCl2 indicates that this β-adrenergic mechanism must rely on interneuronal transmission. Collectively, these results suggest the evolutionary conservation of β-adrenoceptors and of their dual character from coelenterates to higher vertebrates.
Akh Biosynthesis: Transcriptional and Translational Control of Two Co-Localised Prohormones
Authors: Fischer-Lougheed Jacqueline , O’Shea Michael , Cornish Ian , Losberger Christophe , Roulet Emmanuelle , Schulz-Aellen Marie-Francoise
Published: April 2021

The neurosecretory cells of the locust corpora cardiaca (CC) express two co-localised transcripts which are translated into the two preprohormones required in adipokinetic hormone I (AKH I) and AKH II biosynthesis. At different stages of postembryonic development, the relative amounts of the two transcripts (AKH I mRNA and AKH II mRNA) change in parallel with the relative rates of synthesis of proAKH I and proAKH II. Differential regulation of transcript expression, however, cannot account for the changes in neuropeptide ratios seen during postembryonic development. Comparison of in vivo and in vitro translation shows that protein synthesis in vivo is biased towards the translation of AKH I mRNA by a factor of about 2.6. This factor appears to be constant during postembryonic development and is required to produce the observed developmental changes in neuropeptide ratios. Both transcriptional and translational mechanisms are therefore necessary to alter neuropeptide ratios in the CC. The mechanisms we describe can account for the developmentally changing pattern of peptide expression. We suggest that regulation of neuropeptide ratios indicates that signalling functions can be attributed to the precise configuration of peptide cocktails.
Escape Trajectories in Angelfish (Pterophyllum Eimekei)
Authors: Domenici Paolo , Blake Robert W.
Published: April 2021

Although fish escape trajectories are linearly related to stimulus direction, they vary considerably after the initial turn away from the stimulus. Past studies of escape trajectories in fish and other animals have been analysed by employing linear plots of stimulus angle versus body turning angle. Here, we define escape trajectories as a circular variable, with 0° as stimulus direction.

Angelfish (Pterophyllum eimekei) escape in non-random trajectories when the stimulus is presented laterally, within an angular zone of approximately 30–120° (discriminating zone). The circular plot of escape trajectories shows a bimodal pattern that cannot be revealed by linear analysis. Angelfish escape preferentially at 180° and 130° away from the stimulus, maximizing the distance covered from the stimulus and escaping at the limit of their discriminating zone, respectively. Angelfish correct their responses when turning towards the stimulus, suggesting that escape trajectories are modulated by sensory feedback.

Re-analysis of published work on other animals, by employing circular histograms of escape trajectories, reveals multimodal patterns which are also not apparent from the linear plots. We suggest that the presence of multiple preferred trajectories may be adaptive in preventing predators from learning any single fixed pattern of response and compensating for it.
The relationship between intracellular pH and seasonal temperature in the brown trout Salmo trutta
Authors: Butler P. J. , Day N.
Published: April 2021

Early studies on reptiles demonstrated that plasma pH increases as body temperature falls (Robin, 1962). Rahn (1967) proposed that plasma pH in all poikilothermic vertebrates is regulated as body temperature changes so as to maintain a constant relative alkalinity, i.e. a constant [OH−]/[H+] ratio, and Reeves (1972) suggested a way in which this could be achieved. Known as the ‘imidazole alphastat hypothesis’, it postulates that is regulated (by way of ventilation) so that the fractional dissociation (α) of the imidazole moiety of histidine is kept constant. As the pK′−of imidazole changes with temperature in about the same manner as the neutral pH of water (Heisler, 1986), the alphastat hypothesis is consistent with that of constant relative alkalinity.
Epinephrine Stimulation of Glucose Release From Perfused Trout Liver: Effects of Assay and Acclimation Temperature
Authors: McKinley Susan J. , Hazel Jeffrey R.
Published: April 2021

Since fish are poikilothermic, changes in temperature may perturb hormonal activation of cell function. To test this hypothesis, and determine the extent to which hormonal responses are thermally compensated, the effect of temperature on epinephrine-stimulated glucose release in perfused trout liver was studied. Thermally acclimated (5 and 20°C) rainbow trout (Oncorhynchus mykiss) were responsive to epinephrine (0.5×10−6 mol l−1) at both 5 and 20°C. Metoprolol (β2 antagonist) and propranolol (α1and2) decreased the response significantly (to 1.4% and 8.4% of stimulated values, respectively) while phentolamine (α1and2) was without effect, implying the response is β2-mediated. Both basal (86 and 19μ,mol g−1 liver h−1 in 5 and 20°C trout, respectively) and epinephrine-stimulated (210 and 168 μ,molg−1 h−1) rates of glucose release were higher (2.4-fold higher for epinephrine-stimulated and 8.8-fold for basal) in 5°C-than in 20°C-acclimated fish, regardless of perfusion temperature. Although the dose–response curve for epinephrine was markedly temperature-dependent, cold-and warm-acclimated fish were affected in different ways. Cold-acclimated fish (5°C) were less responsive to epinephrine when perfused at 5°C (ED50 6.8×10−9 mol l−1) than when perfused at 20°C (ED50 8.2×10−10 mol l−1); in contrast, warm-acclimated fish (20°C) were less responsive to epinephrine when perfused at 20°C (ED50 4.6×10−7 mol l−1) than at 5°C (ED50 6.6×10−9 mol l−1). These results are interpreted as being indicative of adaptations to maintain the capacity for hepatic glucose mobilization at low temperature.
Ontogenetic Scaling of Jump Performance in the African Desert Locust (Schistocerca Gregaria)
Authors: Katz Stephen L. , Gosline John M.
Published: April 2021

Ontogenetic growth was used as a model for the effect of body size on jumping performance of the African desert locust (Schistocerca gregaria). Using models that generated relationships between morphology and body size proposed by McMahon and the relationships between morphology and performance described by Hill, we generated testable predictions of how jumping performance measures may change as a function of body mass. Data were collected over an ontogenetic sequence that ranged from 1-day-old first instars to 45-day-old adults. Performance was quantified using a high-sensitivity, three-dimensional force plate. Performance parameters quantified included the force, acceleration, take-off velocity, kinetic energy and power output. With the exception of power output, each measure of performance scaled to body mass in a manner consistent with the predictions of the elastic similarity model. Power output scaled to body mass in a manner consistent with the predictions of the constant stress similarity model. As we noted previously for the scaling of flexural stiffness of the metathoracic tibiae, the elastic similarity model is approximated by the performance of the locust in spite of the morphological design that deviates from that model’s predictions.

These results indicate that the jump has separate functions in the flightless juvenile instars and in the flying adult stage of the life history. Juvenile locusts produce take-off velocities of between 0.9 and 1.2 ms−1 that are relatively scale-independent. The take-off velocity in juveniles produces a distance of ballistic travel that averages between 20 and 30cm. In adults, the take-off velocity is also relatively scale-independent at a level approximately twice as high as in juveniles (i.e. 2.5 ms−1). This velocity is coincident with the minimum flight speed reported by Weis-Fogh and a minimum flight speed that we have estimated using actuator disc theory. We suggest that, in juveniles, the jump is designed to achieve a characteristic distance travelled and in adults the jump is designed to achieve a minimum velocity necessary to fly.
Neuronal Feedback In Egg-Laying Behaviour of the Pond Snail Lymnaea Stagnalis
Authors: Ferguson Graham P. , Pieneman Anton W. , Jansen Rene F. , Maat Andries Ter
Published: April 2021

The egg-laying behaviour of gastropod molluscs is controlled by peptidergic neuroendocrine cells and has provided an important experimental system for behavioural neurobiology. The genes that code for multiple peptides have been sequenced and the peptides themselves have been identified, thus enabling us to investigate how they act on the nervous system to produce the overt behavioural pattern (reviewed by Geraerts et al. 1988). The two animals that have been studied most extensively are the opisthobranch Aplysia californica and the pulmonate Lymnaea stagnalis. In both cases, the peptidergic neurones controlling egg laying are normally electrically silent (both in vivo and in vitro; Kupfermann, 1967; Pinsker and Dudek, 1977; Kits, 1980; Ter Maat et al. 1986) and produce multiple peptides (Rothman et al. 1983; Geraerts et al. 1985; Sigvardt et al. 1986), which are cleaved from a common protein precursor (Scheller et al. 1983; Vreugdenhil et al. 1988). Before egg laying, the cells produce a long-lasting discharge of action potentials (Pinsker and Dudek, 1977; Ter Maat et al. 1986). This electrical discharge initiates egg-laying behaviour, and during it the peptides (one of which initiates ovulation) are released into the blood. The demonstration, in Aplysia californica, that these peptides could have various effects on the activity of central neurones (reviewed by Mayeri and Rothman, 1985) led to the hypothesis that egg-laying behaviour is a neuroendocrine fixed action pattern controlled and coordinated by the concerted actions of the released peptides (Scheller and Axel, 1984). This hypothesis is also thought to apply to Lymnaea stagnalis (Vreugdenhil et al. 1988) because of the structural similarities between precursors of Aplysia californica and Lymnaea stagnalis egg-laying hormones. In this paper we investigate how the sequence of the various components of the egg-laying behaviour pattern is achieved.
Isolation of Epidermal Cell Pairs from an Insect, Tenebrio Molitor, For Dual Whole-Cell Recording of Large-Conductance Gap-Junctional Channels
Authors: Churchill Dennis , Caveney Stanley
Published: April 2021

The segmented insect integument, composed of an epidermal monolayer and its cuticular secretion, is a paradigm for the study of pattern formation during development (Lawrence, 1992). Epidermal activity during development may be coordinated by the transfer of cytoplasmic molecules through cell–cell gap-junctional channels (reviewed in Caveney, 1985). Gap junctions within intact epidermal segments exhibit dynamic changes in their permeability properties during the moult cycle in vivo (Caveney, 1978) and with exposure to the developmental hormone 20-hydroxyecdysone in vitro (Caveney and Blennerhassett, 1980). In addition, the row of epidermal cells at segment borders has distinct permeability properties creating developmental and communication compartments (Warner and Lawrence, 1982; Blennerhassett and Caveney, 1984). This paper documents a method for isolating epidermal cells that are suitable for dual whole-cell voltage-clamp studies of gap-junctional currents. We have identified a large-conductance gap-junctional channel in cell pairs with octanol-reduced junctional currents. This cell model may be useful for examining mechanisms of gap-junctional channel gating during development.
Use of Tc-99m-pertechnetate to follow liquid water uptake by Porcellio scaber
Authors: Drobne D. , Fajgelj A.
Published: April 2021

Terrestrial isopods are, apart from the amphipods, the only group of crustaceans living on land. They have evolved some functional and anatomical adaptations to manage water and ion exchange between themselves and their environment, and these are different from those in all other crustaceans. In higher terrestrial isopods, liquid water is taken in by mouth (Hoese, 1981) and water vapour is absorbed in the pleoventral space (Wright and Machin, 1990; Wright and O’Donnell, 1992). Spencer and Edney (1954) also showed that water from wet filter paper can be taken up by the animals’ rear appendages (uropods).
Retinals and Retinols Induced By Estrogen in the Blood Plasma of Xenopus Laevis
Authors: Azuma Masami , Irie Toshiaki , Seki Takaharu
Published: April 2021

Injection of estrogen into male Xenopus laevis induced the appearance of retinals (retinal and 3-dehydroretinal) and a considerable increase in the amount of retinols (retinol and 3-dehydroretinol) in the blood plasma. These retinoids were mainly in the all-trans form. Without estrogen injection, retinols were normally found in the blood plasma of both males and females, but only trace amounts of retinals were detected and these were restricted to the plasma of females.

The proteins in the blood plasma of estrogen-injected males were separated into two fractions. One fraction included vitellogenin, the precursor of egg yolk proteins, and the other contained some plasma proteins other than vitellogenin. Retinals were detected in the former and retinols in the latter. It is suggested that retinals are bound to vitellogenin and are taken up into oocytes in the process of vitellogenesis.
Ovulation and Oviposition in Anura
Authors: Waring H. , Landgrebe F. W. , Neill R. M.
Published: April 2021

The normal rhythm of sexual activity of both Xenopus and Rana is controlled by secretions of the anterior lobe pituitary. Progesterone and testosterone, as well as extracts of A.L.P., evoke ovulation in normal and hypophysectomized Xenopus. Injection of pregnancy urine into hypophysectomized Xenopus evokes enlargement of the reduced ovary and ovulation. Serial injections of pituitary extracts and oestrin were without effect on the amount of egg jelly secreted. Ovulation in Xenopus is immediately followed by oviposition. The eggs are carried by continuous ciliary tracts from the body cavity via the oviduct to the exterior. In Rana ovulation is not immediately followed by oviposition. The eggs accumulate in the lower third of the oviduct and are expelled en masse. Experiments on extirpation of endocrines and the injection of appropriate extracts, together with the responses to pithing and electrical stimulation, lead to the conclusion that oviposition in Rana is probably under nervous not humoral control. The muscular and skeletal mechanism involved in the retention and extrusion of eggs in Rana is described.
On Chromatic Effector Speed in Xenopus and Anguilla and the Level of Melanophore Expanding Hormone in Eel Blood
Authors: Waring H. , Landgrebe F. W.
Published: April 2021

Hogben and his co-workers (Hogben & Slome, 1931, 1936; Neill, 1940) have drawn conclusions from the time relations of the responses of intact Xenopus and eels which presuppose that the limiting factor in the slow responses is the equilibration of the co-ordinating pituitary hormones in the blood and is not due to the inertia of the melanophores. The present investigation has shown that this supposition is justified. The chromatic effector speed of the two species has been measured by perfusing fully dark animals with saline until they were fully pale and then introducing B hormone into the perfusate to observe the reverse change. It was found that:(a) Complete expansion of the melanophores of Xenopus takes too min. Complete contraction of the melanophores of Xenopus takes 70 min.(b) Complete expansion of the melanophores of the eel takes 30 min. Complete contraction of the melanophores of the eel takes 20 min.Adrenalin exercises a potent contracting effect on the melanophores of the eel even in the presence of excess B. It has no direct effect on the melanophores of Xenopus.Increased concentration of B hormone in the perfusate above the threshold dose does not increase the speed of melanophore expansion in either animal. This implies something approaching an all or nothing reaction on the part of the melanophore itself. The usual interpretation of the “all or nothing” behaviour of effectors is that it is in large measure due to the well-known “all or nothing” action of their efferent nerves.Using eels of approximately the same weight estimations of:(a) concentration of B hormone in the circulation of a dark fish,(b) concentration of B hormone in the pituitary of a dark fish,(c) total blood volume, indicate that the distribution of B between pituitary and circulation in a dark animal is of the order pituitary 1, circulation 10.Caustic soda treated extracts of posterior lobe pituitary which evoke the same rise of melanophore index as untreated extracts do not maintain the expanded condition of the melanophores for the same period. The factors involved are discussed.
The Mechanisms of Humidity Reactions of Terrestrial Isopods
Authors: Waloff Nadejda
Published: April 2021

The humidity reactions of Oniscus asellus, Porcellio scaber and Armadillidium vulgare have been analysed and compared. The mechanism whereby the three species collect in moist air is twofold, Consisting of (a) hygrokinesis, or decrease in activity and speed in moist air, and (b) of more frequent turnings in space, retaining them in the areas of greater humidity. These mechanisms are most clearly expressed in Oniscus asellus and least in Armadillidium vulgare. This sequence may be correlated with the resistance to desiccation of the three species, which is greatest in Armadillidium vulgare, and greater in Porcellio scaber than in Oniscus asellus. It is suggested that the humidity reactions of isopods are controlled by water loss by evaporation from the whole body. A correlation between hygrokinesis and thigmokinesis was observed in Porcellio scaber. There appears to be a reversal from negative to positive phototaxis in Oniscus asellus, correlated with the water loss by evaporation. The humidity reactions, low thigmokinesis and negative phototaxis combine to retain the isopods in damp, dark habitats.
The Pigmentation of Cavernicolous Animals
Authors: Beatty R. A.
Published: April 2021

Organic detritus was examined from Chislehurst Cave and from the Postumia Grotte (north Italy). The origin of carotenoid material in the detritus was closely associated with the influence of underground rivers. In the Postumia Grotte, large quantities of carotenoid material were present in detritus swept in by the underground river and deposited in a pool. A smaller quantity was present in similar detritus which had been exposed to the air. Very little was found in airborne detritus at the mouth of the cave, exposed to the air, to light and to temperatures higher than those prevailing within the cave. No carotenoid pigments were found in sediment from a drip pool, which was not connected with the underground river. In Chislehurst Cave no carotenoid pigments could be detected in detritus exposed to the air. These observations indicate that the cave fauna must have some access to carotenoid pigments. A carotene (apparently the β-compound) was found, together with free xanthophylls in the cave salamander Proteus. The distribution varied in different parts of the body. No carotenoids were detected in the cave amphipod Niphargus, taken from the drip pool mentioned above. In the carotenoid materials of detritus, xanthophylls predominate. This has been observed by other workers in carotenoid pigments from peat associated with calcium carbonate. The absorption maxima of the xanthophyll isolated by these workers agree closely with the maxima found in the present investigation. An unidentified red pigment with a powerful fluorescence was found in all the detritus samples studied. It was soluble in organic solvents and showed absorption maximum at 457 ± 2μμ in carbon disulphide.
A Study of the Relative Toxicity of Anions, with Polycelis Nigra as Test Animal
Authors: Jones J. R. Erichsen
Published: April 2021

A brief review is given of existing knowledge regarding the physiological effects of anions, and literature dealing with their relative toxicity.

The degree of toxicity of twenty-seven anions to Polycelis nigra (Müller) has been assessed, by determining in each case the molar concentration the animal survives for 48 hr. at 15−18° C.

On this basis their order of increasing toxicity is as follows; commas separate ions of similar degree of toxicity:

Generally speaking anions are very much less toxic than cations. Even the most toxic anion (OH) is far less toxic than ionic copper, silver or gold.

The respiration rate of Polycelis is heavily depressed by cyanide, but the survival time is three days or longer, as long as the respiration rate is not less than about 16 % of the normal value. With further depression the survival time shortens rapidly, and at 9 % normal is under 4 hr.

The normal respiration rate of Polycelis nigra is 0·165 c.c. O2/g./hr. This is not very much less than that of the trout. Polycelis is considerably the more resistant to cyanide. This is probably connected with its capability of surviving very many hours in water containing a very reduced supply of oxygen.
Notes on the Distribution of Pigment Granules in the Retinal Pigment Epithelium of Light- and Dark-Adapted Rana Temporaria, and on the Nature of the Eye Pigment in the Frog and the Ox
Authors: Dawes Ben
Published: April 2021

About two years ago, the writer made a study of the retinal pigment epithelium of twenty-two English frogs which had been subjected to various experimental conditions and found that the dispositions of the pigment granules could not be explained adequately in terms of the oft-described migration which is believed to take place during light- and dark-adaptation of the eye. The results were anomalous, in so far as the amount of pigment present under certain conditions seemed to be greater than at other times.
On the Function of Haemoglobin in Chironomus
Authors: Ewer R. F.
Published: April 2021

At 17° C. the oxygen consumption of Chironomus larvae shows little diminution when the oxygen concentration in the water decreases from 7·5 c.c. per litre (air saturation) to about 3 c.c. per litre. Below 3 c.c. per litre a further decrease in oxygen concentration causes a falling ôff in oxygen consumption. At 17° C. the oxygen consumption of Chironomus larvae whose haemoglobin has been converted to carboxyhaemoglobin is as great as that of normal animals from air saturation down to 3 c.c. per litre. Below this point the oxygen consumption is less than that of normal animals. It follows that at 17° C. the haemoglobin of Chironomus larvae from well aerated water does not function in oxygen transport at air saturation, but only at oxygen pressures below 3 c.c. per litre. Some observations of the habitat of the larvae show that they can live in situations where oxygen concentrations of less than 2 c.c. per litre persist for periods of at least 16 consecutive hours. The larvae are also to be found in situations where the oxygen concentration is high.
On Properties of the Red Cell Ghost
Authors: Ponder Eric
Published: April 2021

This paper is concerned with certain properties of the mammalian red cell ghost. The principal conclusions are:

When red cells are haemolysed by water they increase in volume, changing their shape and becoming spheres. If the degree of hypotonicity is sufficient they haemolyse in the spherical form, but quickly resume the form of disks, even in hypotonic solutions. If the haemolytic systems are rendered isotonic by the addition of salts, the cells shrink temporarily, but finally assume their original volume and shape. It seems that when there are no osmotic forces acting on it, the watery ghosts tend to take up the volume and shape from the red cell from which it was derived. When a red cell haemolyses in a hypotonic medium and becomes a ghost, a considerable amount of haemoglobin is retained, perhaps by adsorption. It is doubtful whether this adsorption could be on a purely surface structure ; to account for the results we might have to postulate an internal structure in addition. After haemolysis by water, red Cells will not form spheres between slide and coverslip, nor by the addition of lecithin. If the watery ghosts are made by precipitation with CO2, no sphering can be observed between slide.and slip, with lecithin, with saponin, or with rose bengal. In the case of the watery ghost, the “form component” seems to be preserved, for the ghosts are biconcave disks; the surface, however, must have been altered, for disk-sphere transformations no longer take place.
The Respiratory Function of the Haemoglobin of the Earthworm1
Authors: Johnson M. L.
Published: April 2021

It was claimed by Davy as early as 1862 that the haemoglobin in the blood of the earthworm has a respiratory function, but subsequent studies have given conflicting results. In the more recent investigations advantage has been taken of the fact that haemoglobin has a greater affinity for carbon monoxide than for oxygen; the oxygen consumption of normal worms is compared with that of worms whose haemoglobin has been put out of action by saturation with carbon monoxide. Using this method, Jordan & Schwarz (1920) concluded that haemoglobin functions as a transporter of oxygen only at low pressures of oxygen (23–30 mm. mercury).2Dolk & van der Paauw (1929) criticized this work on the grounds that the pure carbon monoxide to which the worms were subjected for some hours might have affected the respiratory enzymes as well as the haemoglobin, and that because of individual .variation it was not possible to compare directly the oxygen consumption of normal and carbon monoxide-treated worms. They repeated the work with modifications, and again found that haemoglobin was functional as an oxygen transporter only at low pressures of oxygen, below 57 mm. mercury. Their work was done on narcotized animals, and was therefore criticized by Thomas (1935), who, moreover, considered that the conclusions drawn by Dolk & van der Paauw were not justified by the experimental data they published. Thomas reinvestigated the matter, and came to the conclusion that haemoglobin has no respiratory function at oxygen pressures lower than 114 mm., for the oxygen consumption of normal and carbon monoxide-treated worms was the same. Above 114 mm. oxygen pressure the oxygen uptake of normal worms rose sharply, while that of carbon monoxide-treated worms remained constant, but Thomas did not attribute this difference in behaviour to haemoglobin, and one is left with the impression that in the earthworm haemoglobin is functionless as an oxygen transporter at all pressures of oxygen. Thomas’s results must, however, be accepted with reserve, for he gives data of experiments on only two normal worms and three carbon monoxide-treated worms.
The Biology and Behaviour of Ptinus Tectus Boie. (Coleoptera, Ptinidae), A Pest of Stored Products
Authors: Gunn D. L. , Hopf H. S.
Published: April 2021

The amount of walking about shown by adult Ptinus tectus is not a simple function of temperature. It depends on culture temperature, on whether the temperature is constant or changing and, with changing temperatures, on the speed and direction of change. Thus, at 20° C., about 25 % of animals walk about if the temperature is constant or rising slowly, while about 90 % are active if it is rising fast or falling slowly. None of the temperature-activity curves bear any resemblance to the usual kind of Q10 curve.

For experiments in which the temperature has been constant for a day the temperature-activity curve of Ptinus rises from 3 to 15° Q., then is steady or falling somewhat to 30 or 35° C., and then falls steeply to 40° C. The activity level depends on the temperature at which the animals have been kept during the previous weeks. When the temperature is raised slowly (3·7’5° C. per hour), activity rises steeply up to about io° C., then falls to the level appropriate to constant temperatures and, at about 30° C., rises steeply again. When the temperature is raised more quickly (14° C. per hour) the activity rise is at first similar to that for slowly rising temperature, but it continues until 90–100 % activity is reached at about 15° C. ; activity remains at this high level until damaging changes occur at about 40° C. When the temperature is slowly lowered, the activity curve is similar to that for quickly rising temperature. There is thus a stimulating effect of change of temperature—whether rising or falling—the magnitude of which depends on the speed and direction of the change.

The results obtained have a considerable bearing on the testing arid use of insecticides whose effectiveness depends on the activity of the insects.
The Biology and Behaviour of Ptinus Tectus Bole. (Coleoptera, Ptinidae), A Pest of Stored Products
Authors: Ewer D. W. , Ewer R. F.
Published: April 2021

At 70 % R.H. development of Ptinus tectus from egg laying to emergence from the cocoon is minimal at 23 – 25° C. and takes an average of about 62 days; at 15° C. the time taken is about 130 days. The minimum temperature at which complete development can occur is below 10° C. and the maximum is between 28 and 30 ° C. ; considerable mortality occurs in eggs and larvae at 28 ° C. and the eggs require a humidity of 100 % R.H. for hatching at this temperature.

At 75 % R.H. and above it is difficult to prevent moulds growing on the food of Ptinus. It appears that 70 % R.H. is a satisfactory humidity for all developmental stages, but in air drier than this (at 25 ° C.Jboth eggs and larvae show an increased mortality and a prolonged development. The hatching of the egg, rather than embryonic development, seems to be sensitive to low humidity.

Adults given food but not water live longer at 70 % R.H. (27° C.) and at 90 % R.H. (15° C.) than at lower humidities. At 25 ° C., below 70 % R.H. feeding is much reduced if water to drink is not given ; at 34 % there is little feeding even when free water is available. Larval feeding is also reduced at low humidities. Oviposition soon ceases unless drinking water is available, at any rate at low humidities.

Ptinus tectus is thus adapted to a temperate climate with a high humidity.
The Ultrastructure And Formation Of Iron Granules In The Honeybee (Apis Mellifera)
Authors: Hsu Chin-Yuan , Li Chia-Wei
Published: April 2021

The honeybee is one of the few organisms that can deposit iron minerals intracellularly. Numerous iron granules are formed in the trophocytes, which are located in the abdomen, beginning on the second day after eclosion. The sequential events of iron deposition in honeybees have been determined and the special features of this biomineralization system are (1) that iron deposition vesicles (IDVs) enlarge by fusing with one another; (2) that dense particles (approx. 7.5nm in diameter) are the basic building blocks in the formation of iron granules; and (3) that a cloudy layer just beneath the membrane of IDVs may play an important role in the formation of the dense particles. The iron granules seem to be randomly distributed in the trophocytes of the worker and drone. In the queen, however, they are clustered and peripherally located. This distinct difference in the iron granule distribution between members of the hive suggests that these iron granules may have some biological functions. A detailed analysis of total iron content during the life cycle of honeybees has shown that iron granules in the adult worker contain approximately 1% of the total iron content and also account for approximately 3% of the increase in iron content that occurs between the newly eclosed worker stage and the adult worker stage.
Anoxic Depression of Spontaneous Locomotor Activity in Crucian Carp Quantified by A Computerized Imaging Technique
Authors: Nilsson Göran E. , Rosén Peter , Johansson Dan
Published: April 2021

The crucian carp (Carassius carassius L.) is one of the most anoxia-tolerant fishes. An important strategy used by the crucian carp to survive anoxia is to lower its rate of energy consumption. Anoxia-tolerant fish are known to utilize simultaneously two different strategies for reducing energy consumption during anoxia, the first being a reduction in locomotor activity and the second being a depression of cellular energy demands. Nevertheless, the reduction in locomotor activity during anoxia has never been measured quantitatively. This lack of information is apparently because technical problems have prevented the measurement of spontaneous locomotor activity in fish. It is now possible to use computerized video-imaging techniques to record the movement of an animal continuously. By the use of such a technique, we show that crucian carp respond to anoxia (330min at 9°C) by rapidly decreasing their locomotor activity (spontaneous swimming distance) to about 50% of that displayed during normoxia. Frequency diagrams of spontaneous swimming speed showed no bimodality and indicated a general decrease in swimming speed from a median value of 1.82 m min−1 during normoxia to 0.82 m min−1 during anoxia. It is tentatively estimated that the anoxic depression of locomotor activity corresponds to a 35–40% reduction in total energy consumption. The role of locomotor activity in fish energy budgets is discussed.
Determination of the Constants of the Henderson–Hasselbalch Equation, αCO2 and pKa, in Sea Turtle Plasma
Authors: Stabenau Erich K. , Heming Thomas A.
Published: April 2021

Hydration of CO2 yields HCO3−via the reaction: Acid–base physiologists traditionally simplify the reaction by omitting the H2CO3 term and lumping all ionic CO2 species into the HCO3− term. The simplified reaction forms the basis for the familiar Henderson–Hasselbalch equation of the CO2–HCO3− buffer system: where αCO2 is the solubility coefficient relating [CO2] and (Henry’s Law). The apparent pK (pKa) in this equation lacks a rigorous thermodynamic definition. Instead, it is an empirical factor relating pH, the product of αCO2 and and the apparent [HCO3−] (i.e. the sum of all ionic CO2 species).
Pre- and Postbranchial Carbon Dioxide Content of Rainbow Trout (Oncorhynchus Mykiss) Blood After Catecholamine Injection
Authors: Nikinmaa Mikko , Vihersaari Laila
Published: April 2021

It is generally accepted that plasma bicarbonate is the major source of carbon dioxide excreted in the gills of teleost fish (Perry, 1986). Although anion exchange across the membrane of rainbow trout erythrocytes is rapid, with a half-time of 0.8s for chloride equilibration at 15°C (Romano and Passow, 1984), the rate of bicarbonate influx into the erythrocytes limits the rate of conversion of plasma bicarbonate to carbon dioxide and, thereby, carbon dioxide excretion per unit volume of blood in gills, because the residence time of blood in the secondary lamellae of the gills is only 1–6s (Hughes et al. 1981; Bhargava et al. 1992). Thus, factors that reduce the net rate of bicarbonate influx through the anion exchanger may reduce the efficiency of carbon dioxide excretion in gills. The effect is, however, temporary. If carbon dioxide production remains constant, the reduction of carbon dioxide excretion will increase the venous carbon dioxide tension and content, thus increasing the diffusion gradient across the gills and speeding up CO2 removal until the CO2 excretion again matches production.
Anatomical and Physiological Identification of Inhibitors of the Motor Giant and Segmental Giant Neurones In The Crayfish
Authors: Fraser K. , Heitler W. J.
Published: April 2021

We anatomically and physiologically identify four interneurones which inhibit the motor giant neurone (MoG) and an interneurone which inhibits both the MoG and the segmental giant (SG) neurone of crayfish. We term these the MoG-I1, -I2, -I3, -I4 and MoG/SG-I neurones. MoG-I1 is almost always very strongly dye-coupled to its bilateral homologue. It is one of the interneurones mediating recurrent feedforward inhibition from the giant fibres (GFs) to the MoG. The GFs activate MoG-I1 by a disynaptic path through the SGs (GF → SG → MoG-I1), which is entirely mediated by rectifying electrical synapses. The resulting trisynaptic path (i.e. GF → SG → MoG-I1 → MoG), in which the first two synapses are electrical, ensures reliable and constant short-latency inhibition of the MoGs following their monosynaptic electrical activation by the GFs (GF → MoG). The remaining MoG-Is receive input from the GFs and other sources through unidentified polysynaptic pathways.

Each interneurone inhibits the MoG and/or SG through depolarising IPSPs, which can be as large as 25mV in amplitude. These IPSPs can effectively block transmission from the GFs to the MoG. The unique morphology of the MoG allows the inhibitory connections from the MoG-Is to be visualised at the light microscope level following staining with Lucifer Yellow. The MoG-Is project a high-density cobweb-like network of fine synaptic branches over the surface of the MoG, which spread from the region of the electrical input from the GFs within the connectives, across the expanded integrating region of the MoG, and onto its axon in the proximal region of the third root. The extensiveness of this anatomical connection correlates well with the high effectiveness of the inhibition mediated by some of the MoG-Is.
Visual Control of Velocity of Approach by Pigeons When Landing
Authors: Lee David N. , Davies Mark N. O. , Green Patrick R. , (Ruud) Van Der Weel F. R.
Published: April 2021

Films of pigeons flying to a perch were analysed to test a theory of how speed of approach and timing of foot extension in preparation for landing are visually controlled. Rapid neural computation of distance to perch and of speed and deceleration would seem to be required. However, according to the theory, none of this is necessary. Simpler control is possible based solely on the value of the tau function of certain optic variables x, where the tau function of x is x divided by its rate of change; i.e. is a first-order approximation of time to contact with the perch and so could be used for timing foot extension. Controlled braking is possible by simply keeping , the rate of change of τ(x), constant. The results indicated that pigeons did regulate their braking when approaching the perch by keeping constant and initiated foot extension when τ(x) reached a threshold value of approximately 150ms. They followed this procedure even when they had one eye covered, and so binocular vision was not necessary for regulating braking or timing foot extension. It is shown that an optic variable that the pigeons could be using is the width of the optic projection of the gap between foot and perch. It is further shown that they could be using the same optic variable for controlling the trajectory of their feet to contact the perch.