bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Growth of Brown Trout (Salmo Trutta Linn.)
Authors: Brown Margaret E. 
Published: April 2021

ABSTRACT
Since fish form an important source of human food, a considerable amount of data is available concerning their distribution and size under natural conditions. This is especially true for the Salmonidae because of their popularity with sporting fishermen. With the development of commercial hatcheries, there has been a certain amount of experimental work concerning the effect of various factors on the growth and life history, particularly of ‘trout’—Salmo trutta, S. irideus and Salvelinus fontinalis. However, it is impossible to define the effect of any particular factor on trout growth, since several environmental factors varied at the same time, without being measured accurately. In some experiments (Surber, 1935; Pentelow, 1939) individual trout were isolated and their growth recorded, while in others (McCay & Tunison, 1935, 1937; Wingfield, 1940) the fish were kept in groups and their average sizes recorded at intervals. There is thus no record of the effect of intraspecific relationships on the growth of individuals.
The Development of the Rat Eye in Graft
Authors: Tansley Katharine 
Published: April 2021

ABSTRACT
Successful grafts were obtained when 15-day embryo rat eyes were transplanted into the brains of 2-day old rats. In the grafts differentiation of the various ocular tissues proceeded at the normal rate. The lens and retina first degenerate and then regenerate, the lens from its epithelium, the retina from its ciliary area. It was not possible to establish whether or not Wolffian regeneration of the lens can occur in the rat.
Run and hide: visual performance in a brittle star
Authors: Sumner-Rooney Lauren , Kirwan John D. , Lüter Carsten , Ullrich-Lüter Esther 
Published: April 2021

ABSTRACT
Spatial vision was recently reported in a brittle star, Ophiomastix wendtii, which lacks discrete eyes, but little is known about its visual ecology. Our aim was to better characterize the vision and visual ecology of this unusual visual system. We tested animal orientation relative to vertical bar stimuli at a range of angular widths and contrasts, to identify limits of angular and contrast detection. We also presented dynamic shadow stimuli, either looming towards or passing the animal overhead, to test for potential defensive responses. Finally, we presented animals lacking a single arm with a vertical bar stimulus known to elicit a response in intact animals. We found that O. wendtii orients to large (≥50 deg), high-contrast vertical bar stimuli, consistent with a shelter-seeking role and with photoreceptor acceptance angles estimated from morphology. We calculate poor optical sensitivity for individual photoreceptors, and predict dramatic oversampling for photoreceptor arrays. We also report responses to dark stimuli moving against a bright background – this is the first report of responses to moving stimuli in brittle stars and suggests additional defensive uses for vision in echinoderms. Finally, we found that animals missing a single arm orient less well to static stimuli, which requires further investigation.
Algorithms underlying flexible phototaxis in larval zebrafish
Authors: Chen Alex B. , Deb Diptodip , Bahl Armin , Engert Florian 
Published: April 2021

ABSTRACT
To thrive, organisms must maintain physiological and environmental variables in suitable ranges. Given that these variables undergo constant fluctuations over varying time scales, how do biological control systems maintain control over these values? We explored this question in the context of phototactic behavior in larval zebrafish. We demonstrate that larval zebrafish use phototaxis to maintain environmental luminance at a set point, that the value of this set point fluctuates on a time scale of seconds when environmental luminance changes, and that it is determined by calculating the mean input across both sides of the visual field. These results expand on previous studies of flexible phototaxis in larval zebrafish; they suggest that larval zebrafish exert homeostatic control over the luminance of their surroundings, and that feedback from the surroundings drives allostatic changes to the luminance set point. As such, we describe a novel behavioral algorithm with which larval zebrafish exert control over a sensory variable.
Observations On the Effect of Microclimate on Biting by Aedes Aegypti (L.) (Dipt., Culicid.)
Authors: Lumsden W. H. R. 
Published: April 2021

ABSTRACT
Work on the factors controlling the avidity of Aëdes aegypti females for a blood meal previously reported by Seaton & Lumsden (1941) was continued. Mosquitoes were kept after hatching for 96–120 hr. in darkness at about 25° C. and 80% relative humidity, and were then offered a blood meal on the human arm in darkness. Wide variations in the light intensity during the few minutes’ manipulation immediately previous to offering the host did not significantly affect the numbers feeding. The relative humidity of the environment at the time of biting appeared to be of little or no importance. The optimum environmental temperature for biting was near 35° C. At 35° C., out of batches of ten mosquitoes offered 5 min. opportunity to feed, means of 8·8 ± 0·44 and 9·2 ± 0·33 fed at high and low humidities respectively. Large proportions of A. aegypti females, confined within 8·5 cm. of a host and in darkness, were able to locate the host and to feed when environmental temperatures approximated closely to the skin temperature or even were above it. Some factor other than the presence of a temperature gradient rising to the skin must therefore be responsible for their orientation to, and probing of, the host. In the majority of fed mosquitoes blood was found in the stomach alone, but partly fed mosquitoes showed a higher proportion with blood in the diverticula than did those fully gorged. Such an effect is probably due to regurgitation of blood from the stomach when feeding is interrupted before its normal completion.
Molecular and physiological characterization of a crustacean cardioactive signaling system in a lophotrochozoan – the Pacific oyster (Crassostrea gigas): a role in reproduction and salinity acclimation
Authors: Réalis-Doyelle Emilie , Schwartz Julie , Dubos Marie-Pierre , Favrel Pascal 
Published: April 2021

ABSTRACT
The crustacean cardioactive peptide (CCAP) is an important neuropeptide involved in the regulation of a variety of physiological processes in arthropods. Although this family of peptides has an ancestral origin, its function remains poorly understood among protostome species – apart from arthropods. We functionally characterized three G protein-coupled receptors (GPCRs) in the oyster Crassostrea gigas, phylogenetically related to ecdysozoan CCAP receptors (CCAPRs) and to chordate neuropeptide S receptors (NPSRs). Cragi-CCAPR1 and Cragi-CCAPR2 were specifically activated by the Cragi-CCAP1 and Cragi-CCAP2 peptides, respectively, both derived from the same CCAP precursor. In contrast, Cragi-CCAPR3 was only partially activated by CCAP1 and CCAP2 at high concentrations. The Cragi-CCAPR1 and Cragi-CCAPR2 genes were expressed in various adult tissues. They are both most expressed in the gills, while Cragi-CCAPR3 is mainly expressed in the visceral ganglia (VG). Cragi-CCAP precursor transcripts are higher in the VG, the labial palps and the gills. Receptor and ligand-encoding transcripts are more abundantly expressed in the gonads in the first stages of gametogenesis, while the Cragi-CCAP precursor is upregulated in the VG in the last stages of gametogenesis. This suggests a role of the CCAP signaling system in the regulation of reproductive processes. A role in water and ionic regulation is also supported considering the differential expression of the CCAP signaling components in oysters exposed to brackish water.
The Physiology of Sea-Urchin Spermatozoa
Authors: Rothschild Lord 
Published: April 2021

ABSTRACT
Echinus esculentus spermatozoa are normally motionless in undiluted semen. They become active when the semen is diluted with sea water or seminal plasma obtained by gentle centrifugation (1500 r.p.m., 12 cm. radius, for 15 min.). A sperm-immobilizing substance can, however, be obtained in seminal plasma by more prolonged centrifugation of semen. Spermatozoa can be made motile in undiluted semen by increasing the O2 tension in the atmosphere surrounding the semen. This O2 activation is completely inhibited by N2; the N2 effect is reversible. Measurements of seminal O2 tension were made with an O2 electrode. The O2 tension of semen is low, being at most 15 mm. Hg. It was not possible to decide whether this residual tension was due to O2 or some other substance reacting at the electrode. The K content of seminal plasma is about 1·55 mg./ml., which is four times higher than that of perivisceral fluid or sea water. The pH of semen is lower than that of sea water, being approx. 7·5. Neither K concentration nor pH is responsible for the inactivity of sperm in semen. A hormone, Androgamone I, is often considered to be responsible for the inactivity of spermatozoa in non-mammalian semen. No support has been found for this view and it is concluded that in E. esculentus semen the spermatozoa are motionless through lack of O2.
The Water-Balance Principle of Crustacean Eye-Stalk Extracts
Authors: Heller H. , Smith B. 
Published: April 2021

ABSTRACT
Eye-stalks of the brackish water-crab, Carcinus moenas, and of the fresh-water crayfish, Potamobius fluviatilis, were extracted according to the pharmacopoeia! method for the extraction of posterior pituitary glands. Injection of such eye-stalk extracts resulted in a temporary increase in the body water of frogs. The increase produced by the extract of one eye-stalk of Carcinus was approximately equal to that produced by the injection of 20 milliunits pitocin ( = oxytocic fraction of mammalian posterior pituitary extract). The crustacean eye-stalk extracts had no significant oxytocic, chloruretic, or antidiuretic effect.
The Effect of Sex-Hormones on the Performance of a Learned Response
Authors: Douglas J. W. B. , Hanson D. A. , Zuckerman S. 
Published: April 2021

ABSTRACTThe Hull ‘Goal-Gradient Alley’ is described, and its advantages in the analysis of the effect of hormonal stimulation upon conditioning are discussed. The rate at which spayed rats run the goal-gradient alley was tested before and after the administration of oestrogen alone and oestrogen combined with androgen. It was found that a decrement in the speed of running for food occurs at varying times from 6 to 102 hr. after the administration of oestradiol benzoate. The decrement is still apparent when testosterone propionate and oestradiol benzoate are administered in the proportion 20:1, but is not present when the proportion is 50 :1. The possible physiological mechanisms of this response decrement are considered.
The Physiology of Contractile Vacuoles
Authors: Kitching J. A. 
Published: April 2021

ABSTRACT
The rate of output of the contractile vacuole in a fresh-water peritrich ciliate (Carchesium aselli) varies with temperature with a Q10 of about 2·5–3·2, or a μ of about 17,000, over the range 0–30° C. There is a slow decline in output during exposure for several hours to high temperatures (25–30° C.). At still higher temperatures (34° C.) a high rate of output is maintained for a few minutes, but swelling and death rapidly ensue. The frequency of uptake of food vacuoles also varies with temperature, increasing from o to about 24° C., but decreasing at higher temperatures. At about o° C. and at temperatures above about 30° C. no food vacuoles are taken up and the adoral cilia remain extended and motionless. No change in body volume could be detected during exposure to high temperatures (25–30° C.) for two or more hours, even though the rate of vacuolar output was increased to three or four times its normal level at 15° C. It is concluded that the rate of uptake of water from the outside medium must have been increased correspondingly. It is suggested that temperature affects the permeability of the organism to water, and that the rate of vacuolar output is adjusted accordingly, although on the evidence so far presented other explanations are possible.
The Metabolism of Fertilized and Unfertilized Sea-Urchin Eggs
Authors: Rothschild Lord 
Published: April 2021

ABSTRACT
An investigation has been made into the effect of light and carbon monoxide on the respiration of sea-urchin eggs (Psammechinus miliaris), with special reference to unfertilized eggs. The O2 uptake of unfertilized eggs in air is 38% higher in the dark than in light. This inhibitory action of light persists when gas mixtures containing CO and O2 are substituted for air. Fertilized and unfertilized eggs differ in that the former’s respiration is only about 10% inhibited by light. In 80% CO in O2 in the dark, the O2 uptake of unfertilized eggs is 55% higher than in 80% N2 in O2 in the dark. In 95% CO in O2 in the dark, the O2 uptake of unfertilized eggs is only 7% higher than in 95 % N2 in O2 in the dark, showing that at this partial pressure, CO exerts an inhibitory action on respiration. There is no difference between O2 uptake in 80% CO in O2 in light and dark. O2 uptake in 95 % CO in O2 in light is 45 % higher than in this gas mixture in the dark, showing that at this partial pressure of CO, photo-reversal of respiratory inhibition occurs. Results similar to those in 80% CO in O2 were obtained with gas mixtures containing lower partial pressures of CO. Cytochromes a and were identified spectroscopically in unfertilized eggs. It is concluded that respiration is mediated through the cytochrome system before and after fertilization. In theories which postulate that cytochrome is ‘thrown into circulation’ at fertilization, the simultaneous light-inhibition of respiration, stimulation of O2 uptake by CO, and photo-reversible inhibition of O2 uptake by CO have not been taken into consideration.
The Osmotic Relations of the Earthworm
Authors: Ramsay J. A. 
Published: April 2021

ABSTRACT
Osmotic pressure and chloride concentration have been determined for the coelomic fluid, blood and urine of earthworms kept in various saline media. About 50% of the osmotic pressure of the coelomic fluid and of the blood can be accounted for as chloride. The blood is very slightly hypotonic to the coelomic fluid. As the concentration of the medium is increased the osmotic pressure of the body fluids also increases and is always greater than that of the medium; the chloride increases proportionately, but is less than that of the medium when the latter exceeds 0·35% NaCl. The urine is always strongly hypotonic to the body fluids except possibly in the most concentrated media (over 1·0% NaCl). The osmotic relations of the earthworm are such as are characteristic of fresh-water animals generally.
A New Method of Freezing-Point Determination for Small Quantities
Authors: Ramsay J. A. 
Published: April 2021

ABSTRACT
A method is described for determining the freezing-point of small quantities (0·1 - 1·0 × 10-3cu.mm.) of fluid. Tested on solutions of NaCl of concentration up to 2% the probable error of the method is less than 0·01% NaCl. The potentialities of the method are discussed.
The Relation Between the Epidermal Mitotic Activity and the Blood-Sugar Level in the Adult Male Mouse, Mus Musculus L
Authors: Bullough W. S. 
Published: April 2021

ABSTRACT
An investigation has been made of the relation between the concentration of the blood sugar and the mitotic activity of the ear epidermis of the adult male mouse. It has been shown that, within limits, an increase in the blood-sugar level, induced by subcutaneous injections of starch, results in an increased mitosis rate. Conversely, a decrease in the blood-sugar level, induced by insulin, causes a decreased mitosis rate. A deep mitosis depression is also caused by injections of phloridzin. Since it is known that phloridzin interferes with the phosphorylation of sugar, and since it is also shown that injections of phosphate augment the effect produced by starch alone, the tentative suggestion is put forward that sugar may act by satisfying the energy requirements of mitosis. However, in the normal animal the diurnal changes in the blood-sugar level are the inverse of the diurnal changes in mitotic activity, the concentration of the blood sugar being relatively low during sleep when the mitosis rate is relatively high. It is therefore evident that, within normal limits, the level of the blood sugar as such is not an important factor in the control of the diurnal mitosis cycles. It is considered probable that the critical factor in the control of these cycles is the concentration of sugar, or glycogen, within the tissues themselves. Thus during sleep, sugar is probably deposited in the tissues, as it is known to be in the liver, so accounting simultaneously for the fall in the level of the blood sugar and the rise in the mitosis rate.
Influence of the Corpus Allatum on the Oxygen Consumption of Adult Calliphora Erythrocephala Meig
Authors: Thomsen Ellen 
Published: April 2021

ABSTRACT
The possible influence of the corpus allatum on the metabolism of adult Calliphora erythrocephala was studied by measuring the oxygen consumption of allatectomized females and males by means of the Warburg apparatus. As a basis for the experiments on operated flies, the oxygen consumption of normal unoperated females and males was measured. The oxygen consumption of the two sexes was found to be of the same order. In the females allatectomy resulted in a decrease in the oxygen consumption of 24%. Implantation of three corpora allata from females into females which retained their own corpus allatum increased the oxygen consumption by 19%. In the males allatectomy likewise caused a reduction in the oxygen consumption, but the exact amount of the decrease was somewhat difficult to evaluate owing to a great number of abnormally high values in the operated controls. Implantation of three corpora allata from males into males which retained their own corpus allatum did not raise the oxygen consumption. A possible cause of this negative result is discussed. It was thus found that the corpus allatum is necessary for the normal metabolism of Calliphora.
The Fertilization Reaction in the Sea-Urchin Egg
Authors: Rothschild Lord 
Published: April 2021

ABSTRACT
The first sign that a sea-urchin egg has been fertilized is a change in cortical structure which spreads over the egg surface from the point of attachment of the fertilizing spermatozoon (Rothschild & Swann, 1949). The velocity of propagation is not uniform, there being a reduction in rate when the change approaches the equator of the egg relative to the point of attachment of the spermatozoon, and a marked increase when the cortical change has nearly covered the egg surface. The conduction mechanism of the cortical change might be similar to that occurring in stimulated nerve or muscle. Alternatively, it might be due to the diffusion of a substance, directly or indirectly derived from the head of the spermatozoon, found the cortex or through the cytoplasm, a change in cortical structure being effected by the arrival at the cortex of a particular concentration of the diffusing substance. If this hypothetical substance diffuses round the cortex and not through the cytoplasm, we must postulate a sympathetic reaction by ‘affected’ parts of the cortex, or an entirely separate cytoplasmic reaction, also initiated by the spermatozoon, to account for the intracellular changes that precede mitosis. By ‘affected’ parts of the cortex, reference is made to that fraction of the cortex which, owing to the arrival of a particular concentration of the diffusing substance, has changed its structure. On the other hand, if diffusion takes place through the cytoplasm, the one process might account for the two phenomena, cortical and intracellular changes, if cortex and cytoplasm are affected at different rates by the diffusing molecules.
Age and Mitotic Activity in the Male Mouse, Mus Musculus L
Authors: Bullough W. S. 
Published: April 2021

ABSTRACT
A study has been made of the mitosis rate and of the diurnal cycles of male mice during each of the first 20 months of life. The mice used belonged to the Kreyberg’s white label and the Strong’s CBA strains. Most of the observations were made on the ear epidermis, but some attention was also given to other tissues. It was discovered that, when judged from the point of view of mitotic activity, the life of a male mouse consists of four ages. During the immature age the animals are still growing and their mitosis rate is generally high, although the ear epidermis provides an exception to this rule. During the mature age which lasts from about the 3rd to the 12th month the mitosis rate is lowered. During the middle age which follows the mitosis rate increases, but in senility it is again reduced. Coincident with these changes in the mitosis rate are changes in the spontaneous bodily activity. The mice are most active during immaturity and maturity. In middle age their activity is reduced by about half, and in senility they spend almost the whole time resting. Particularly in the Strong’s CBA mice there are also changes in the timing of the diurnal cycle of spontaneous bodily activity, and these are immediately mirrored by changes in the timing of the diurnal cycle of mitotic activity so that throughout life a general inverse relationship between bodily activity and mitotic activity is maintained. In middle-aged Strong’s CBA males the daily rest period extends almost without interruption from 06.00 to 18.00 hr. However, the most active cell division develops only at the beginning of this period, and it is evident that in prolonged sleep a lack of some vital factor develops. It is shown that subcutaneous injections of starch overcome this lack in sleeping mice and result almost immediately in the redevelopment of a high mitosis rate. Thus it would appear that sugar is the vital factor involved, and that the sugar content of the tissues is quickly used up during high mitotic activity. These results are discussed particularly in relation to the problem of carcinogenesis.
Studies On Animal Carotenoids
Authors: Steven D. M. 
Published: April 2021

ABSTRACT
In the first paper of this series (Steven, 1948) it was shown that the tissues of the trout (Salmo trutta Linn.) normally contain β-carotene, lutein and astacene. Lutein and astacene occur as esters in the red and yellow chromatophores of the skin, and may also be present in the muscles as free hydroxy-carotenoids. Carotene is present in the liver, which also contains xanthophylls but no astacene. The ripening oocytes, however, contain all three types of carotenoid. Red and yellow chromatophores first appear during the larval period of development before the young fish has commenced to feed independently, and appear to obtain their pigment from the carotenoids laid down in the yolk. This paper records the chemical changes and distribution of these substances from the maturation of the oocytes to the stage of metamorphosis of the larva.
Adult trout were obtained alive from a reservoir near Edinburgh. Some ova were obtained from ripe fish in the laboratory, and fertilized with sperm from males of the same batch. Larger numbers were supplied by the Howietoun and Northern Fisheries, Stirling, as ‘eyed’ ova, and were used for most of the experiments on the larval period of development. Ova and larvae were reared in batches of about 100 each in glass aquarium jars, which were immersed nearly to the rim in a larger tank through which passed a rapid flow of water taken direct from the mains supply. This arrangement gave satisfactory temperature stabilization for the period of the experiments, from January to the end of March. Temperature variation was less than 1° C. for periods of more than a week, and remained within the range 4–6° C. for the whole period.