bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Succinoxidase System in Oyster Muscle
Authors: Humphrey George Frederick 
Published: April 2021

ABSTRACT
The importance of the role which the C4-dicarboxylic acids play in tissue respiration was pointed out by Szent-Györgyi in 1937. It is now known that succinic dehydrogenase is one of the few dehydrogenases which react directly with the cytochromes, and the ‘succinoxidase’ system has been investigated in a large number of vertebrate tissues. The action of succinate on the oxygen uptake of a few invertebrate tissues has been studied, but no detailed consideration has been given to the possible occurrence of a succinoxidase system. This system becomes especially important in view of the varied response of such tissues to agents like cyanide and azide, which have a marked effect on cytochrome oxidase.
The urban-adapted underground mosquito Culex pipiens form molestus maintains exogenously influenceable circadian rhythms
Authors: Epstein Natalie R. , Saez Kevin , Polat Asya , Davis Steven R. , Aardema Matthew L. 
Published: April 2021

ABSTRACT
Genes known to affect circadian rhythms (i.e. ‘clock genes’) also influence the photoperiodic induction of overwintering reproductive diapause in the northern house mosquito, Culex pipiens f. pipiens. This suggests that molecular changes in one or more clock genes could contribute to the inability to diapause in a second form of this mosquito, Culex pipiens f. molestus. Temperate populations of Cx. pipiens f. molestus inhabit underground locations generally devoid of predictable photoperiods. For this reason, there could be limited fitness consequences if the hypothesized molecular changes to its clock genes also eliminated this mosquito's ability to regulate circadian rhythms in response to photoperiod variation. Here, we demonstrate that in contrast to this prediction, underground derived Cx. pipiens f. molestus retain exogenously influenceable circadian rhythms. Nonetheless, our genetic analyses indicate that the gene Helicase domino (dom) has a nine-nucleotide, in-frame deletion specific to Cx. pipiens f. molestus. Previous work has shown that splice variants in this gene differentially influence circadian behavior in Drosophila melanogaster. We also find derived, non-synonymous single nucleotide polymorphisms (SNPs) in eight genes that may also affect circadian rhythms and/or diapause induction in Cx. pipiens f. molestus. Finally, four putative circadian genes were found to have no quantifiable expression during any examined life stage, suggesting potential regulatory effects. Collectively, our findings indicate that the distinct, but molecularly interconnected life-history traits of diapause induction and circadian rhythms are decoupled in Cx. pipiens f. molestus and suggest this taxon may be a valuable tool for exploring exogenously influenced phenotypes in mosquitoes more broadly.
Plasticity of non-shivering thermogenesis and brown adipose tissue in high-altitude deer mice
Authors: Coulson Soren Z. , Robertson Cayleih E. , Mahalingam Sajeni , McClelland Grant B. 
Published: April 2021

ABSTRACT
High altitude environments challenge small mammals with persistent low ambient temperatures that require high rates of aerobic heat production in face of low O2 availability. An important component of thermogenic capacity in rodents is non-shivering thermogenesis (NST) mediated by uncoupled mitochondrial respiration in brown adipose tissue (BAT). NST is plastic, and capacity for heat production increases with cold acclimation. However, in lowland native rodents, hypoxia inhibits NST in BAT. We hypothesize that highland deer mice (Peromyscus maniculatus) overcome the hypoxic inhibition of NST through changes in BAT mitochondrial function. We tested this hypothesis using lab born and raised highland and lowland deer mice, and a lowland congeneric (Peromyscus leucopus), acclimated to either warm normoxia (25°C, 760 mmHg) or cold hypoxia (5°C, 430 mmHg). We determined the effects of acclimation and ancestry on whole-animal rates of NST, the mass of interscapular BAT (iBAT), and uncoupling protein (UCP)-1 protein expression. To identify changes in mitochondrial function, we conducted high-resolution respirometry on isolated iBAT mitochondria using substrates and inhibitors targeted to UCP-1. We found that rates of NST increased with cold hypoxia acclimation but only in highland deer mice. There was no effect of cold hypoxia acclimation on iBAT mass in any group, but highland deer mice showed increases in UCP-1 expression and UCP-1-stimulated mitochondrial respiration in response to these stressors. Our results suggest that highland deer mice have evolved to increase the capacity for NST in response to chronic cold hypoxia, driven in part by changes in iBAT mitochondrial function.
The Measurement of the Oxygen Consumption of Daphnia by a Modification of the Cartesian Diver Technique
Authors: O’Connor R. J. 
Published: April 2021

ABSTRACT
The Cartesian diver microrespirometer has been adapted to the measurement of the oxygen consumption of Daphnia. The modification involves an increase in size of the diver to a total capacity of over 100 μl., and absorption of carbon dioxide by sodium hydroxide in a central cup incorporated in the structure of the diver. The variation in the rate of oxygen consumption of normal Daphnia has been measured. Sources of error in the modified technique have been investigated and the possibility of its wider use discussed.
The Physiology of Contractile Vacuoles
Authors: Kitching J. A. 
Published: April 2021

ABSTRACT
On transfer from sea water to dilute sea water, the marine peritrich ciliate Vorticella marina swells more rapidly at higher temperatures. It is concluded that the permeability of the surface of V. marina to water is influenced by temperature, with a Q10 of very roughly 2·5–3·2. The body volume of the fresh-water peritrich ciliate Carchesium aselli is maintained approximately constant when the organism is transferred to solutions of sucrose of concentrations up to about 0·04 M; in higher concentrations the organism shrinks. The rate of output of the contractile vacuole of C. aselli decreases with increasing concentrations of sucrose in the external medium; the rate of output is very low in 0·05 M-sucrose. From a consideration of the effects of sucrose solutions on the body volume and on the rate of vacuolar output it is concluded that the initial osmotic pressure of C. aselli normally exceeds that of the external pond water by about 0 0·4–0· 05 M non-electrolyte. The. internal osmotic pressure of C. aselli is not materially increased by increase of temperature. It is concluded that the increase in rate of vacuolar output, which accompanies increase of temperature, counterbalances an increased rate of osmotic uptake of water from the external medium, and that this increased rate of uptake is due to an effect of temperature on the permeability of the surface through which the water enters. The rate of vacuolar output is temporarily much increased when C. aselli, which has been equilibrated in solutions of ethylene glycol, is returned to pond water. It is suggested that the temperature and the osmotic pressure of the external solution largely determine the osmotic stress which is imposed on the organism, and that they thus influence the state of hydration of the protoplasm; in turn this may be supposed to determine the activity of the contractile vacuole.
Studies on Tapeworm Physiology
Authors: Smyth J. D. 
Published: April 2021

ABSTRACT
Plerocercoid larvae of the pseudophyllidean cestode Ligula intestinalis from the body cavity of roach, were cultured in vitro at 40°C. in a variety of saline and nutrient media. About 65% of such cultures were aseptic. During cultivation, larvae produced acid by-products (unidentified) and the pH fell rapidly. The presence of these acid by-products slowed down development, or, if present in sufficient quantity, caused death. In order to obtain development in nutrient media in a period (3 days) comparable to that required in a bird (the normal host) it was necessary to renew the medium 24-hourly. 6% of the eggs produced from a worm cultured in horse serum were fertile. Fertile eggs were never obtained from larvae cultured in any other media. Certain bacterial infections had no apparent detrimental effect on development, but others were toxic. Some larvae underwent development in non-nutrient medium (୴ strength Locke’s solution). The exact conditions under which this occurred was not determined. Fragments (3 cm. long), of larvae or larvae with either scolex or posterior half removed, underwent development to the stage of oviposition in nutrient media. Histochemical examination revealed that the plerocercoid larvae were almost fat-free. During cultivation, very large quantities of cytoplasmic fat were produced the quantity being proportional to the duration of cultivation. Fat was produced even under starvation conditions (i.e. during cultivation in saline) and can be considered a metabolic by-product. The fresh plerocercoid contained great quantities of glycogen in the parenchyma and muscle regions. After cultivation in nutrient or saline media, considerable quantities were still present.
The Swimming of Whales and A Discussion of Gray’s Paradox
Authors: Parry D. A. 
Published: April 2021

ABSTRACT
Whales swim by oscillating the tail and the flukes in a vertical plane. Tail and flukes move out of phase, the flukes leading on the tail by quarter of a wave-length. Photographic evidence is given and anatomical evidence referred to. Previous accounts of the movement are reviewed. A theoretical treatment of the dynamics of swimming gives results in fair agreement with the only known observation of the frequency of tail-beat. Support is given to Gray’s suggestion that the drag of an actively swimming whale is less than that of a rigid model. The possibility that whales develop more power (weight for weight) than man without going into oxygen debt is discussed. It is concluded to be unlikely.
Shape and Shape Transformations of Heated Human Red Cells
Authors: Ponder Eric 
Published: April 2021

ABSTRACT
The action of temperatures above 48° C. on the red cell is usually regarded as a classical example of the irreversible effects of injury, the lysis which follows being attributed to a surface membrane becoming permeable because its lipid components are melted or because its protein components become denatured. Recently it has been found that the effects are considerably more complex, and increasing emphasis is being placed on the role which fragmentation plays in the phenomenon of heat haemolysis. Ham, Shen, Fleming & Castle (1948) have pointed out that the fragmentation which precedes haemolysis results in the cells of the system becoming more and more spherical, so that the extent to which each cell can swell before its surface is stretched becomes less and less, and the tonicity in which it haemolyses becomes greater and greater; when there is sufficient fragmentation, indeed, human red cells will haemolyse even in an isotonic medium such as plasma. The tonicityvolume relations of cells which have lost one or more of these fragments during heating to temperatures in the neighbourhood of 48° C., however, are substantially the same as those of intact cells (Ponder, 1948a), and both cells and fragments show substantially the same resistance to haemolysis by saponin and by digitonin; these observations point to the osmotic properties and the properties which determine the resistance to lysins being shared by cell and fragment, and to the unit structure upon the integrity of which these properties depend being smaller than the intact red cell. The possibility that this is so suggests that something may be learned by examining the shape of the red cells and fragments more closely, since the ability to maintain shape and to undergo shape transformations are also properties which are usually thought of as associated with the red cell as a unit structure.
The Effects of High and Low Temperatures on the Epidermal Mitotic Activity of the Adult Male Mouse, Mus Musculus L
Authors: Bullough W. S. 
Published: April 2021

ABSTRACT
The form of the diurnal cycles of epidermal mitotic activity in the adult male mouse has been shown to be determined by the times of sleeping and waking, high mitotic activity being associated with both natural and artificial sleep, and low mitotic activity with muscular exercise (Bullough, 1948 a, b).
The Pigmentation of Cavernicolous Animals
Authors: Beatty R. A. 
Published: April 2021

ABSTRACT
The visible coloration of three species of amphipod Crustacea (Gammarus pulex, G. marinus and Orchestia gammarella) was found to be due almost exclusively to carotenoid pigments, including in each case a proportion of an astacin-like carotenoid acid. No carotenoid pigments could be demonstrated, even in traces, in three species of the cavernicolous Amphipod genus Niphargus. Carotenoid pigmentation is thought to be characteristic of Amphipoda and would therefore be the ancestral pigment of the cave forms. The lack of pigment in cave Amphipoda may be due to absence of light; it is not due to lack of carotenoid pigments in the food.
The Absorption of Water by the Eggs of Corixa Punctata Illig. (Hemiptera-Corixidae) Under Experimental Conditions
Authors: Banks C. J. 
Published: April 2021

ABSTRACT
Poisson (1924) states that the eggs of aquatic Hemiptera increase in volume as they develop. Kerenski (1930), Ludwig (1932), Evans (1933), Johnson (1937), Roonwal (1936), and Birch & Andrewartha (1942), all have described in various insects the changes which take place in the developing egg and which are generally associated with the absorption of water.
The Utilization of Reserve Substances in Drosophila During Flight
Authors: Wigglesworth V. B. 
Published: April 2021

ABSTRACT
The respiratory quotient in Drosophila during flight is about 1·0 (Chadwick, 1947), and the duration of flight to exhaustion varies with the age of the fly in the same manner as does the total glycogen—increasing steeply during the first 5 days of adult life, remaining at a maximum for about 10 days and then falling gradually until the fly is 5 or 6 weeks old (Williams, Barness & Sawyer, 1943). It appears certain that glycogen is the main or sole reserve substance consumed during flight.
It is the object of the present work to provide a histological picture of the distribution of the reserve substances and their mobilization during sustained flight. In the course of the work it has been possible to compare directly the efficiency of different substances as sources of energy for flight. D. melanogaster has been used throughout. The insects have been reared and maintained on standard maize-meal medium at 250C.
Vascular Patterns of the Mammalian Testis and Their Functional Significance
Authors: Harrison R. G. , Weiner J. S. 
Published: April 2021

ABSTRACT
Even a superficial examination of the testes of various animals, for example rat and rabbit, is sufficient to make obvious that there are fundamental differences in their vascular supply and that the vessels display remarkable complexity both in their venous and arterial course. That morphological differences may exist between different animals has long been realized; thus de Graff (1677) clearly depicts the contrasting patterns of dog and dormouse. Nevertheless, comparative studies of these patterns have been meagre and their functional significance has not been elucidated.
In this communication is presented first a description of these testicular vascular patterns in a number of animals, drawing attention especially to the course and relations of the vessels within the spermatic cord. In a second section evidence is offered in support of the suggestion that the morphology of the blood vessels in the cord is connected with the temperature regulating mechanism of the testis—specifically, as a determining factor of the abdomino-testicular temperature ‘gradient’.
The Kinetics of Locomotion of the Grass-Snake
Authors: Gray J. , Lissmann H. W. 
Published: April 2021

ABSTRACT
The propulsion of an undulating grass-snake, Natrix (Tropidonotus) natrix, depends on the ability of the animal to adopt a sinusoidal form and brace the lateral surface of its body against rigid external objects (Gray, 1946). Under such conditions the forces acting normally to the sides of the body provide a propulsive force equal but opposite to the frictional forces tending to restrain the motion of the animal. The present paper represents an attempt to give quantitative expression to these conclusions by observation of the forces acting against the body of a living snake.
The Nutritional Requirements of Drosophila Melanogaster
Authors: Begg Michael , Robertson Forbes W. 
Published: April 2021

ABSTRACT
Methods are described for the aseptic culture of Drosophila. All the factors necessary for normal development can be extracted from yeast in water-soluble form. A chemically defined medium sufficient for almost normal growth is described and includes : casein (and gelatin) as a source of amino-acids, dextrose, cholesterol, ergosterol, yeast nucleic acid, inositol, biotin, aneurin hydrochloride, riboflavine, nicotinic acid, pyridoxin hydrochloride, Ca-pantothenate, choline chloride, thymine and folic acid. For completely normal development an alkali-soluble fraction must be added. This fraction shows nucleoprotein-like reaction, but it is neither arginine nor nucleic acid. Folic acid is essential for pupation. Attention is drawn to the need for caution in gene-action studies with synthetic media which do not give completely normal development even in the wild type.
The Physiology of Sea-Urchin Spermatozoa
Authors: Rothschild Lord 
Published: April 2021

ABSTRACT
Spermatozoa and seminal plasma of Echinus esculentus contain catalase. At 15° C., 4 ml. of a suspension of semen diluted with neutral phosphate buffer in the ratio 1:13 produced in 1 min. 90 μl. O2 from an H2O2 solution containing 150 μl. O2. The dry weight of semen in the suspension was 45 mg. and the number of spermatozoa 8·55 × 10−9. Under the same conditions, seminal plasma obtained by centrifuging semen produced 50 μl. O2 in 1 min. The dry weight of seminal plasma in the suspension was 12 mg. Human blood, dry weight 229·3 mg./ml., must be diluted with phosphate buffer in the ratio 1:1700 to produce the same amount of O2 in 1 min. as the above suspension of semen. If catalatic activity is defined by the equation Ae= (gt)−1 In {a/(a—x)}, where g = weight in g./ml. of the catalase-containing material, t=i min., a = initial substrate concentration (H2O2), and x = amount of H2O2 decomposed in 1 min. at 15° C., Ac= 80–100, 150–200 and 6800 respectively for sea-urchin semen, sea-urchin seminal plasma and human blood. The catalatic activity of semen and seminal plasma is strongly inhibited by hydroxylamine. The 02 uptake and motility of sea-urchin spermatozoa is unaffected by M/5000 H2O2. Higher concentrations of H2O2, M/3000·5000, produce a pronounced ‘shock’ effect, from which the spermatozoa often completely recover. Low concentrations of hydroxylamine, M/3000, reduce O2 uptake and motility. Sea-urchin spermatozoa are almost instantly killed by combinations of hydroxylamine and H2O2, at concentrations which are relatively innocuous when the substances are added separately. A rough calculation indicates that a single spermatozoon contains less than 500 molecules of catalase. A new method of adding H2O2 to catalase-containing material in a manometer is described.
A Note on the Catalase Content of Sea-Urchin Eggs
Authors: Rothschild Lord 
Published: April 2021

ABSTRACT
During experiments on the catalase content of sea-urchin spermatozoa, opportunities arose of measuring the catalatic activity of sea-urchin eggs. Fertilized and unfertilized eggs of Echinus esculentus were examined, the jelly having been removed in each case. Holter & Linderstrom-Lang (1936) and Holter (1937) investigated the catalase content of sea-urchin eggs, but they were particularly concerned with the location of this enzyme in the cell. The catalatic activity of sea-urchin eggs has attracted attention on several occasions in the past (see, for example, Kobert, 1903), but the results were unquantitative and sometimes contradictory. Furthermore, no workers examined the effect of low concentrations of hydroxylamine on the apparent catalatic activity of these cells. Hydroxylamine is a specific inhibitor of catalase as opposed to other substances which catalytically decompose H2O2 into O2 and H2O.
The Role of the Coelomic Fluid in the Movements of Earthworms
Authors: Newell G. E. 
Published: April 2021

ABSTRACT
A short review is given of the coelom and of its morphological relations in the earthworm. The arrangement of the intrinsic muscles in a typical septum is described. Four main sets of muscles are recognized: viz. radial muscles, circular muscles, oblique muscles, and the sphincter around the ventral foramen. It is suggested that the function of the radial, circular and possibly of the oblique muscles is to control bulging of the septa, and so serve to localize differences in pressure in the coelomic fluid. Normally, in active worms, the sphincter of the ventral foramen is contracted and forms an effective barrier to the passage of fluid from one coelomic compartment to the next. This was verified experimentally and by X-ray photography. A series of measurements of the pressure in the coelomic fluid in different regions of active worms was recorded by means of a capillary manometer and by the use of a spoon-gauge apparatus. Manometric measurements showed the average pressure in the anterior third of the body to be 16.0 cm. water and in the tail region to be 8.0 cm. water. The corresponding figures obtained with a spoon gauge were 13.5 and 8.5 cm. water. The pressure in narcotized worms is zero. These results are discussed, and it is pointed out that the manometer readings suffer from the disadvantage of failing to show the rapid fluctuations in pressure which occur during wriggling movements of the worms. It is calculated from these pressure readings that a worm can exert a forward thrust equivalent to forces of between 1.5 and 8.0 g. These figures agree well with those obtained by Gray & Lissman by the use of a special torsion balance. The burrowing movements of earthworms are briefly described. It is shown that the sphincters of the dorsal pores and of the nephridiopores do not normally allow of the escape of coelomic fluid, and will withstand a pressure well outside the normal range.
The Electrical and Mechanical Events of Neuro-Muscular Transmission in the Cockroach, Periplaneta Americana (L.)*
Authors: Roeder Kenneth D. , Weiant Elizabeth A. 
Published: April 2021

ABSTRACT
Though the mechanical activity of insect muscle has been studied by many workers (notably Heidermanns, 1931 ; Solf, 1931 ; Kraemer, 1932; Cremer, 1935), and insect-muscle potentials have been recorded by Rijlant (1932) and Pringle (1939), no attempt has been made to examine the precise relation between motor-nerve impulse, muscle potential, and muscle contraction in this group. The purpose of this account is to examine the electrical and mechanical signs of neuro-muscular events in the cockroach, and to evaluate them in the light of current concepts of neuro-muscular transmission in Crustacea and invertebrates.