bluuebunny/crossref_metadata_2025_split huggingface dataset:
Actin Gene Expression During Muscle Growth in Carcinus Maenas
Authors: Whiteley N. M. , Taylor E. W. , Haj A. J. El 
Published: April 2021

ABSTRACT
As in other crustaceans, growth in Carcinus maenas (L.) is closely associated with the moult cycle because of the restrictions imposed by the calcified exoskeleton. The greatest increase in body mass occurs after ecdysis when the old exoskeleton is shed and rates of water uptake are elevated with a consequent increase in body volume (Drach, 1939; Mykles, 1980; Hartnoll, 1982). Growth of the walking leg extensor muscles in crustaceans such as Homarus americanus and Carcinus maenas is achieved both by the addition of sarcomeres to lengthen the muscle fibres and by increasing the number of myofibrils to add to their diameter (Govind, 1982; El Haj et al. 1984; El Haj and Houlihan, 1987). Addition of sarcomeric proteins to the fibres is relatively rapid, being restricted to the few days when ecdysis and the immediate postecdysial stages occur, while increases in fibre diameter may occur over the longer intermoult periods (Houlihan and El Haj, 1985; El Haj and Houlihan, 1987). The factors regulating muscle growth in crustaceans have not been identified and the stages of the moult cycle where regulation occurs have not been defined.
The Mechanism Of Tongue Projection In Chameleons: I. Electromyographic Tests Of Functional Hypotheses
Authors: Wainwright Peter C. , Bennett Albert F. 
Published: April 2021

ABSTRACT
In this paper we document the activity of key muscles of the tongue, hyobranchia! apparatus and head during prey capture in the lizard Chamaeleo jacksonii Boulenger and use these data to test current hypotheses of chameleon tongue function. Electromyographic recordings were made during 27 feedings from nine individuals and synchronized with high-speed video recordings (200fields s−1), permitting an assessment of the activity of muscles relative to the onset of tongue projection, contact between tongue and prey, and tongue retraction. Four major results were obtained. (1) The hyoglossi muscles exhibit a single burst of activity that begins between 10 ms before and 20 ms after the onset of tongue projection and continues throughout the period of tongue retraction. (2) The accelerator muscle exhibits a biphasic activity pattern, with the first burst lasting about 185 ms and ending an average of 10.6 ms prior to the onset of projection. (3) The accelerator muscle shows regional variation in morphology that corresponds with variation in motor pattern. The anterior region of the muscle, unlike the posterior portion, exhibits only a single burst of activity that begins 2.5 ms after the onset of tongue projection and is thus not involved in launching the tongue. (4) The geniohyoidei, sternohyoidei, sternothyroidei, depressor mandibulae, adductor mandibulae and pterygoideus all exhibit activity patterns consistent with previously reported kinematic patterns and their proposed roles. The major implications of these results for models of the chameleon feeding mechanism are (1) that the hyoglossi do not act to hold the tongue on the entoglossal process during a loading period prior to tongue projection, and (2) that the presence of 185 ms of intense activity in the accelerator muscle prior to tongue projection suggests the presence of a preloading mechanism, the nature of which is the subject of the companion paper.
Ontogenetic Scaling and Mechanical Behaviour of the Tibiae of the African Desert Locust (Schistocerca Gregaria)
Authors: Katz Stephen L. , Gosline John M. 
Published: April 2021

ABSTRACT
Current models for scaling of skeletal morphology were examined to test their applicability to the ontogenetic growth of an exoskeletal animal, the African desert locust ( Schistocerca gregaria). It was found that the tibial leg segments of both the mesothoracic (i.e. non-jumping) and the metathoracic (jumping) legs scaled in a manner that produced relatively longer, more slender skeletal elements as the animal grew. Metathoracic tibial length scaled to tibial diameter raised to the power 1.21. This result deviates both from isometric (i.e. geometric similarity) and distortive (constant stress, elastic similarity) allometric models.
The mechanical properties of the metathoracic tibiae were measured using a dynamic, three-point bending technique. The flexural stiffness of metathoracic tibiae scaled to body mass raised to the power 1.53. This was intermediate to the predictions made by constant stress and elastic similarity models. Thus, the mechanical properties scaled as predicted by mechanical scaling expectations in spite of the morphological developmental programme.
It may be that the thin-walled skeleton developed in the exoskeletal body plan has allowed a finer control over the distribution of load-bearing material in the leg. Such a distribution may be responsible for the observed increase in mechanical stiffness of legs that exhibit an unexpectedly spindly morphology. The rationale for the observed morphological programme may be a design that takes advantage of the inherent deformability of long, slender beams. Thus, it may be that the tibiae, which have been treated as rigid levers, are in fact flexible springs. Calculations indicate that the energy stored in the substantial deflection of the adult, metathoracic tibiae during a jump may be as high as 10% of the total kinetic energy of the jump.
The Mechanism of Tongue Projection in Chameleons: II. Role of Shape Change in a Muscular Hydrostat
Authors: Wainwright Peter C. , Bennett Albert F. 
Published: April 2021

ABSTRACT
In this paper we investigate the interaction between the accelerator muscle (the muscle that powers tongue projection) and the entoglossal process (the tongue’s skeletal support) that occurs during tongue projection in chamaeleonid lizards. Previous work has shown that there is a delay of about 185 ms between the onset of accelerator muscle activity and the onset of tongue projection. In conjunction with anatomical observations, in vitro preparations of the accelerator muscle mounted on isolated entoglossal and surrogate processes were stimulated tetanically, and the resulting movements were recorded on video at 200 fields s−1. Three results indicate that morphological features of the entoglossus and the accelerator muscle delay the onset of tongue projection following the onset of accelerator contrac-tion: ( 1) the entoglossus is parallel-sided along the posterior 90% of its shaft, only tapering at the very tip, (2) the sphincter-like portion of the accelerator muscle, which effects tongue projection, makes up the posterior 63% of the muscle and does not contact the tapered region of the entoglossus at rest, and (3) accelerator muscles mounted on the entoglossus undergo longitudinal extension and lateral constriction for 83 ms following the onset of electrical stimulation, before projecting off the entoglossus. It is proposed that, during elongation of the accelerator muscle, the sphincter-like region ultimately comes into contact with the tapered region of the entoglossus, causing the onset of projection. This conclusion is supported by the observation that the time between the onset of stimulation and the onset of projection was longer in preparations with surrogate entoglossal processes that had no tapered tip and shorter with surrogate processes that had a tapered tip about four times as long as the natural entoglossus.
Tetanically stimulated accelerator muscles reached 90% of peak force 110 ms after the onset of stimulation, indicating that the 185 ms delay between the onset of accelerator activity and the onset of projection seen in vivo allows the accelerator to achieve peak force prior to the onset of projection. Thus, the delay in projection may be crucial in maximizing the acceleration and velocity achieved by the projected chameleon tongue.
Mechanics and Protein Content of Insect Flight Muscles
Authors: Peckham Michelle , Cripps Richard , White David , Bullard Belinda 
Published: April 2021

ABSTRACT
In asynchronous insect flight muscles, stretch activation may arise from a matching of the helix periodicities of actin target sites to myosin heads and/or a special form of troponin subunit called troponin-H (Tn-H, relative molecular mass 80×103), which has so far only been found in the asynchronous flight muscles of Drosophila (Diptera) and Lethocerus (Hemiptera). The sequence of Tn-H in Drosophila shows it to be a fusion protein of tropomyosin and a hydrophobic proline-rich sequence. Tn-H in Lethocerus is immunologically similar. From immunoblots of synchronous (non-stretch-activated) and asynchronous flight muscles from a wide range of insects, using antibodies against tropomyosin and the hydrophobic sequence of Tn-H, raised against Lethocerus proteins, we found two forms of Tn-H. One, found in most flight muscles, only reacted with antibodies to the hydrophobic sequence. The other, found in asynchronous flight muscles from Diptera and Hemiptera, reacted with antibodies to both the hydrophobic sequence and to tropomyosin, although in the Hemiptera the reaction of Tn-H with anti-tropomyosin was weak. When we compared the mechanics of most of the asynchronous flight muscles used in this study, we found that in the Diptera Ca2+-activated tension was much lower at rest length and stretch-activated tension was more highly dependent on muscle length than in other orders of insects. This suggests that, when Tn-H is in the form found in Diptera, it may be able to modulate Ca2+-activated and stretch-activated tension. We conclude that Tn-H is not sufficient for stretch-activation, but it may enhance stretch-activation, particularly when it is in the form found in the Diptera.
A Neural Mechanism for Processing Colour Information in Molluscan Extra-Ocular Photoreceptors
Authors: Nishi Takako , Gotow Tsukasa 
Published: April 2021

ABSTRACT
This study was conducted to clarify the electrical and spectral properties of the combined photoresponses of two extra-ocular photoreceptor neurones, A-P-l and Es-1, in the abdominal ganglion of the marine mollusc Onchidium verruculatum. The depolarizing receptor potential or inward receptor current of Es-1 appeared to result from a decrease in K+ conductance, in the same way as in A-P-l. The direct photoresponse of Es-1 had a peak at 580 nm, while A-P-l had its peak at 490nm. Under normal conditions, Es-1 was hyperpolarized by blue-green light (490nm) and was depolarized by yellow light (580nm), indicating that its responses were wavelength-dependent. Slow inhibitory synaptic potentials in Es-1 occurred during a sustained depolarization of A-P-l, suggesting that Es-1 received some inhibitory synaptic input from A-P-l. The amplitude of these slow synaptic hyperpolarizations was dependent on graded changes in the depolarization of A-P-l. However, presynaptic spikes in A-P-l were not followed by discrete synaptic potentials in Es-1. These results suggest that graded photoresponses of A-P-l could produce the slow hyperpolarization of Es-1 and that the photore-sponse of A-P-l is thereby transmitted to Es-1 with reversed polarity. The differing responses of Es-1 to light of different wavelengths may have a role in colour discrimination.
In Vivo Analysis of Gas Transport in Arterial and Venous Blood of the Sea Lamprey Petromyzon Marinus
Authors: Tufts B. L. , Bagatto B. , Cameron B. 
Published: April 2021

ABSTRACT
Exercise in sea lampreys resulted in a significant decrease in the extracellular pH (pHe) in both arterial and venous blood. At rest, the erythrocyte pH (pHi) of venous blood was significantly greater than the pHi of arterial blood. Despite the considerable extracellular acidosis after exercise, both arterial and venous pHi were maintained throughout the recovery period. In the venous blood, there was a reversal of the pH gradient (ΔpH) across the erythrocyte membrane immediately after exercise. Exercise also resulted in significant reductions in the partial pressure of oxygen and hemoglobin oxygen-carriage and a significant increase in the partial pressure of CO2 in arterial and venous blood. Although the total CO2 concentration of the plasma decreased after exercise, erythrocyte total CO2 concentrations increased. In venous blood, the immediately after exercise was double the resting value. At rest, partitioning of the total CO2 content between plasma and erythrocytes indicated that 16% and 22% of the total CO2 could be attributed to the erythrocytes in arterial and venous whole blood, respectively. After exercise, these percentages increased to 25% (arterial) and 38% (venous). Changes in accounted for 62% of the arteriovenous difference in whole-blood total CO2 at rest. This increased to 78% immediately after exercise. Thus, unlike other vertebrates, CO2 transport in the lamprey in vivo is largely dependent on erythrocyte CO2-carriage.
The Effects of Glutamate Agonists on Voltage-Clamped Motoneurons of the Lobster Cardiac Ganglion
Authors: Hashemzadeh-Gargari H. , Freschi J. 
Published: April 2021

ABSTRACT
The effects of L-glutamate and its analogues were studied in voltage-clamped motoneurons of the lobster cardiac ganglion. These excitatory amino acids caused a dose-dependent increase in membrane conductance and an inward current at the resting membrane potential. The EC50 for L-glutamate was 150 μmoll−1. The rank order of potencies of the various agonists was quisqualate &gt; L-glutamate= L-aspartate&gt;kainate&gt;cysteine. Kainate, unlike the other agonists, showed no desensitization. Of various antagonists studied, only the quinoxalinediones inhibited the response to glutamate. These antagonists also reduced the amplitude and duration of the pacemaker-driven burst potential, suggesting that glutamate may be released by some of the endogenous synapses within the ganglion. The reversal potential of the glutamate-induced current was −15 mV. When Na+ was replaced with K+, the glutamate-induced current still reversed between 0 and −20 mV. When Na+ was replaced with the impermeant ion N-methyl-D-glucamine, the current was inhibited. The amplitude of responses evoked by glutamate and its analogues was reduced in salines containing either high or low concentrations of Ca2+. These results of pharmacological and of reversal potential and ion substitution experiments indicate that glutamate acts on receptors of the non-NMDA (N-methyl-D-aspartate), quisqualate/kainate type to open a channel permeable to both Na+ and K+.
The Response of the Water-Regulating Mechanism of Developmental Stages of the Common Toad, Bufo Bufo Bufo (L.), to Treatment with Extracts of the Posterior Lobe of the Pituitary Body
Authors: Howes N. H. 
Published: April 2021

ABSTRACT
Investigations made in recent years have demonstrated a connexion between the posterior lobe of the pituitary gland and water regulation in Amphibia. Injection of extracts causes a retention of water in the body of frogs (Brunn, 1921 ; Heller, 1930; Steggerda, 1931 ; Collin & Drouet, 1932; teggerda & Essex, 1934; Oldham, 1936 ; Boyd & Brown, 1938 ; Boyd & Whyte, 1939), toads (Steggerda, 1931 ; Novelli, 1933), Amblystoma (Bëlehràdek & Huxley, 1927), Necturus maculatus (Steggerda, 1937), and some reptiles (Boyd & Dingwall, 1939). In mammals the antidiuretic effect of the posterior lobe is now well established. On the other hand, freshwater fish show no such effect even when given doses of pituitrin up to 2·0 1.u. per 10 g. body weight. Nevertheless, the fish pituitary contains a substance causing a typical water retention in frogs (Boyd & Dingwall, 1939). It appears therefore that while the principle concerned is elaborated in the fish pituitary, either the appropriate effector is not developed or an alternative system which deals with the greater part of water regulation, is present. Thus, on the basis of the data available, it may be said that the regulation of the body water by agents of the posterior pituitary is characteristic of terrestrial but not of primarily aquatic vertebrates.
The Experimental Modification of the Oestrous Cycle in the Ferret by Different Intensities of Light Irradiation and other Methods
Authors: Marshall F. H. A. 
Published: April 2021

ABSTRACT
The original discovery by Bissonette (1932) that the recurrence of oestrus in the ferret was greatly accelerated by light was corroborated and extended by Marshall & Bowden (1934, 1936), who found that ultra-violet light had a more long-continued effect than rays from the visible part of the spectrum, but that rays of long wave-lengths caused no acceleration. The experiments described in this paper were upon (1) the effects of different degrees of light intensity as obtained by placing the cages at different distances from the electric lamp, (2) the effect of ultra-violet light on the duration of oestrus, (3) the effect of feeding vitamin D to anoestrous animals, and (4) the effects of copulation as shown by the discontinuance of oestrus and the subsequently observed state of the ovaries and other reproductive organs. Under present circumstances it has not been possible to continue the experiments, but the results, although not so complete as originally hoped for, seem sufficiently conclusive to make their publication desirable.
A Note on the Biochemistry of Embryonic Determination in Echinoderms
Authors: Needham Joseph , Needham Dorothy M. 
Published: April 2021

ABSTRACT
Apart from the Amphibia, the echinoderms are the class of animals about which our knowledge of embryonic determination and its biochemical basis has in recent times made the most important forward strides. This is largely due to the brilliant work of the Scandinavian school. The fundamental facts of echinoderm experimental embryology are now available in a review in the English language by Hörstadius (1939), while on the biochemical side there are general accounts by Runnström (1935 a) and particularly by Lindahl (1936).
A Note on the Osmotic Pressure of the Blood of Various Animals
Authors: Aldred Patricia 
Published: April 2021

ABSTRACT
The experiments described below were undertaken originally in conjunction with Dr Dacie of King’s College Hospital in an attempt to determine whether a relation exists between the osmotic pressure and the “fragility” of blood corpuscles. It was found, however, that the osmotic pressure differences hardly accounted for the fragility differences, and the experiments were continued on the osmotic pressure alone.
The Choice of Drinking Water by the Honeybee
Authors: Butler C. G. 
Published: April 2021

ABSTRACT
A brief review of the literature on this subject is given. By means of “training table” experiments in which use was made of the Latin square system in order to allow of rapid statistical analysis of the results obtained, it was shown that:
The honeybee prefers dilute sodium chloride and ammonium chloride solutions to distilled water. It does not prefer concentrations of these salts higher than N/20 solutions and solutions of various other salts to distilled water. The honeybee appears unable to distinguish between N/160 sodium chloride or N/160 ammonium chloride and distilled water. The honeybee is probably largely attracted to such sources of drinking water as rain water from gutters choked with decaying organic matter, sewage effluent, etc.: by a water perception sense coupled with an olfactory appreciation of various volatile substances contained in these sources of water. The volatile substances present in the distillates from the various naturally occuring solutions examined could be absorbed on to animal charcoal to a large extent, in which case the resulting supernatant fluid was found to have lost its great attraction for the honeybee and was no longer clearly distinguished from distilled water. The salts contained in these sources of drinking water do not appear to play an important part in attracting the bee thither. It was found possible to express the preference shown by the honeybee for various solutions by means of numerical factors based on distilled water having an arbitrary factor of 10. Forty different solutions have been arranged in order of preference by this means.
The Daily Rhythm of Activity of the Cockroach, Blatta Orientalis L
Authors: Gunn D. L. 
Published: April 2021

ABSTRACT
In an aktograph at 25 ·5 ° C., at upwards of 75% relative humidity and with food present, the average locomotory activity of the cockroach per day does not depend on whether there is continuous light for weeks, or continuous darkness, or a daily alternation of light and darkness. When temperature and humidity do not vary during the day and other factors are kept as constant as possible, the cockroach’s activity can be largely concentrated into any desired half of the day, simply by suitably adjusting the time of onset of the half-day’s darkness. A rhythm can thus be set up, so that the main activity occurs at the same hours each day. This activity rhythm persists for some days in continuous light or continuous darkness, but eventually activity becomes much more evenly spread over the whole day, leaving only a slight residual rhythm which is unrelated to the previous conspicuous one. A new conspicuous rhythm can then be started at once by alternation of light and darkness. There are indications that animal responses to physical stimuli may depend to a considerable extent on whether the animal is in the active or the inactive phase of its daily cycle. A method is suggested for making it possible to study the nocturnal phase during the daytime.
The Humidity Behaviour of the Mealworm Beetle, Tenebrio Molitor L
Authors: Gunn D. L. , Pielou D. P. 
Published: April 2021

ABSTRACT
It has previously been shown that, under suitable experimental conditions, Tenebrio molitor reacts clearly to humidity (Pielou & Gunn, 1940) and that the humidity receptors are probably the pit-peg organs and peg organs on the antennae (Pielou, 1940). The present work is an attempt to analyse the mechanism of this reaction both qualitatively and quantitatively, in terms of elementary animal behaviour.
The Effects on the Fat and Starch Metabolism of Gebia by the Parasite Gyge Branchialis
Authors: Hughes T. E. 
Published: April 2021

ABSTRACT
Males of Upogebia Uttoralis parasitized by Gyge branchialis show a marked increase in fat content from 1·04 to 1·6%. Parasitized females have a fat content practically the same as that of ordinary non-ovigerous females, 1·2 %. Ovigerous females have a fat content considerably higher than that of parasitized males or non-ovigerous females, namely 2·2%. The parasite Gyge has a relatively high fat content, 4·4 %. There is a significant difference in glycogen content between normal males and females. There may be a slight increase in glycogen following parasitization. The results are essentially in agreement with the theory of metabolic stimuli put forward by Geoffrey Smith.