bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on the Comparative Physiology of Digestion
Authors: Yonge C. M. 
Published: April 2021

ABSTRACT
The œsophagus is characterised by a great development of mucous glands and cilia, and its function is essentially that of transport The stomach epithelium contains many secretory cells and is in all probability the site of the elaboration of the digestive enzymes. There are no mucous cells. The hind-gut possesses no secretory cells other than mucous cells. Large round or elliptical cells with prominent nuclei and cytoplasm colouring darkly with all glycogen stains are numerous and are also present occasionally in the stomach. The hind-gut is the only part of the gut which possesses muscle-fibres in its walls, food being transported through the gut by ciliary action. Mucous cells are very plentiful and there are. also secretory cells—quite unlike those of the stomach—whose function is problematic. Starch, glycogen and sucrose are digested, the amylolytic ferment having an optimum temperature of between 42° and 43° C. and being destroyed at 64° C. A lipolytic enzyme is present. There is a very weak proteolytic enzyme which acts only in alkaline and neutral media with the formation of albuminoses, but there is no sign of amino-acids after 14 days’ digestion. The glucosides salicin and amygdalin are split up. Absorption takes place primarily in the mid-gut, to a smaller extent in the stomach, and very slightly in the hind-gut. The gut allows dissolved substances to diffuse through it in either direction, but the action of the epithelium causes fluid to flow out of the gut even against strong osmotic pressure. Glycogen is found in the branchial sac, throughout the gut (except the œsophagus) and in the ovary. It is most plentiful in the glycogen cells of the mid-gut and stomach. Fat is present in the œsophagus, stomach, and ovary. Quantitative estimations show that the gut possesses the highest content of fat (including lecithin) and the ovary the highest content of glycogen.
The Metabolism of the Shore-Living Dinoflagellates
Authors: Bruce John Ronald 
Published: April 2021

ABSTRACT
The Dinoflagellata, as a group, are prominently represented in the marine plankton, being second only to the diatoms in their abundance, and in their importance as a source of food for other planktonic forms and some fishes. In addition to the truly planktonic genera, of which Ceratium and Peridinium are the most abundant in British waters, a number of shore-living forms, occurring between the sand-grains in the tidal area, are frequently present in such profusion as to cause discoloration of the sand-surface. These latter, comprised chiefly in the genera Amphidinium and Gymnodinium, have received much attention within recent years, and the series of reports by W. A. Herdman (1911-14), Laurie (1914), and E. C. Herdman (1921-24) upon their occurrence, habits, and morphology, have thrown much light upon a hitherto obscure and neglected group, and have served to emphasise the profound importance of the rôle played by these minute organisms in the biological complex of the sandy beach.
Experiments on the Localisation of the Substances in Pituitary Extracts Responsible For Metamorphic and Pigmentary Changes in Amphibia
Authors: Spaul E. A. 
Published: April 2021

ABSTRACT
Metamorphosis can, as originally stated by Hogben, be induced in the neotenous axolotl larva of the Mexican salamander by regular injection of fresh extracts of the anterior lobe of bovine pituitary; the failure of Smith to obtain this result in experiments upon the Colorado axolotl appears to be due to the necessity of performing the extraction in acid medium. Such traces of melanophore stimulant as are found in the anterior lobe of the mammalian pituitary result from post-mortem diffusion. The substances responsible for production of metamorphic changes and pigmentary response are not identical.
Experiments on the Silver Nitrate Method for the Histological Demonstration of Ascorbic Acid (Vitamin C)
Authors: Barnett S. A. , Fisher R. B. 
Published: April 2021

ABSTRACT
A 10 % solution of silver nitrate in 10 % acetic acid has been widely used to show the presence of ascorbic acid in microscopical preparations (Bourne, 1936; Giroud, 1938). When there is ascorbic acid in the cells a black precipitate of metallic silver is obtained. This precipitate is often observed to be on or in the Golgi material, and it has been supposed that where this is the case the ascorbic acid is itself located in the Golgi substance (Giroud, 1938; Bourne, 1935). However, it has been pointed out that this conclusion is not necessarily correct, since the localization of the silver precipitate may be a physico-chemical phenomenon, resulting from the presence of a certain type of interface (Barnett, 1942). Experiments have therefore been carried out in vitro to investigate whether silver precipitates tend to accumulate at interfaces in conditions comparable with those in cells.
Disintegration of Epididymal Spermatozoa by Application of Ice to the Scrotal Testis
Authors: Chang Min Chueh 
Published: April 2021

ABSTRACT
The effect of temperature on spermatogenesis and on spermatozoa in mammals is very distinctive. Testicular temperature is a few degrees below body temperature, 1·5–2·5°C. lower in rabbits, 2·0–3·5° C. in guinea-pigs, 4–8° C. in rats (Moore & Quick, 1924), 4–9° C. in rams (Phillips & McKenzie, 1934). Spermatogenesis is retarded or even completely stopped by increasing the normal temperature of the testis, as for example by natural and artificial cryptorchidism (Moore, 1922, 1924 a, rats and guinea-pigs) or by applying heat to the testis (Fukui, 1923a, rabbits; Moore, 1924b, guinea-pigs; Young, 1927, guinea-pigs ; Phillips & McKenzie, 1934, rams ; Macleod & Hotchkiss, 1941, human). An optimum temperature, a few degrees below that of the body, can therefore be postulated for spermatogenesis. Although the contraction and relaxation of the scrotum in response to the outside temperature can bring about thermo-regulation of the testes by both raising and lowering the temperature as suggested by Crew (1922), and this mechanism undoubtedly plays a part in reducing temperature, no ill effect on spermatogenesis of lowering the temperature below the optimum has-been found even when the testes of rats were subjected to a temperature as low as 6–8° C. (Phillips & McKenzie, 1934). It may be that spermatogenesis is less susceptible to injury at a lower than at a higher than normal temperature.
The Functional Significance of the Hypocercal Tail in Pteraspis Rostrata
Authors: Kermack K. A. 
Published: April 2021

ABSTRACT
It is now many years since Kiaer (1924) demonstrated the existence of the hypocercal tail in the Anaspida, and subsequently it has been found to be universally present in the Heterostraci (Stetson, 1931; Kiaer, 1932; White, 1935). No experimental attempt seems to have been made, however, to investigate its functional significance (see Harris, 1936), although it has been realized for a considerable time that the hypocercal tail would tend to depress the hinder end of the body during swimming (Ahlborn, 1896; Grove & Newell, 1936). An attempt is made in this paper to determine, by experimental methods, this functional significance.
The Basic Food Requirements of Several Insects
Authors: Fraenkel G. , Blewett M. 
Published: April 2021

ABSTRACT
It is well known that insects, as a class, feed on an immense variety of different substances, and that each food has its specific insects. But it has never been explained whether, or to what extent, this relationship of insects and food is due to differences in the basic food requirements of different insects. In studying the dietetics of insects it was hoped to find an answer to the question: What determines the distribution of insects on different foods ? It was also hoped to gain more information about the requirements of insects for accessory food factors. The advantages in using insects for the identification and estimation of vitamins are obvious and have often been pointed out. The advantage in using for dietary studies insects which normally feed on flour-lies in the fact that the diet is. powdery and relatively dry. A diet, of the consistency of a powder is easy to prepare by mixing ground ingredients together. The normal water content of grain or flour is about 14 %. This minimizes the danger of contamination of experimental diets by micro-organisms. The following six different insect species which are known as widespread pests of flour were used :
Tribolium ccmfusum Duv. Tenebrionidae, Coleoptera.
Silvanas (Oryza ep hilus) surinamensis. Cucujidae, Coleoptera.
Sitodrepa panicea L. Anobiidae, Coleoptera.
Lasioderma serricome Fab. Anobiidae, Coleoptera.
Ptinus tectus Boield. Ptinidae, Coleoptera.
Ephestia kuehmella Zell. Phycitidae, Lepidoptera.
On the Behaviour of Wireworms of the Genus Agriotes Esch. (Coleoptera, Elateridae)
Authors: Lees A. D. 
Published: April 2021

ABSTRACT
The influence of water, as distinct from humidity, on insect behaviour has not been widely investigated, but with regard to the special problem of wireworm distribution, soil moisture has been recognized as an environmental factor of considerable importance (Thomas, 1940).
The Stimulus to Feeding in Anemonia Sulcata
Authors: Pantin C. F. A. , Pantin A. M. P. 
Published: April 2021

ABSTRACT
Feeding can be initiated in Anemonia sulcata by mechanical, chemical or electrical stimulation of the tentacles provided the stimulus sets up sufficiently prolonged excitation. Owing to rapid adaptation, mechanical stimuli rarely set up enduring excitation and inert objects are therefore usually rejected. Chemical stimuli set up prolonged excitation and food objects are therefore usually accepted. A series of electrical stimuli can produce rejection or feeding according to whether it is brief or prolonged. The sensitivity of the tentacles varies greatly to different foods. It is greatest to animal foods. There is great sensitivity to certain kinds of mucus. The active substances of natural foods are closely associated with protein. They fail to pass through a membrane which retains colloids. A feeding reaction can be obtained to food substances which appear to be insoluble in water. Though the active substances of many natural foods are not in free solution, soluble derivatives of proteins, such as peptones and amino acids cause a feeding reaction. With pure proteins, the response of the cnidae is diminished. With amino acids, there is no cnida response. From this it follows that increased mechanical contact due to cnida discharge is not essential for excitation of the feeding response. Fat, such as tristearin, and ethereal extracts of food are without effect. Alcoholic Soxhlet extraction of food yields a substance.which causes the food reaction. Carbohydrates are without effect except in the case of glycogen, the action of which may be due to impurities. The lower fatty acids, quinine and bile salts produce a withering contraction of the tentacles which differs from the response of the latter to food. The effect can be produced by prolonged electrical excitation at a higher frequency than that required for the feeding response and is therefore probably due to excessive stimulation. The mouth responds to a greater variety of chemical stimuli than the tentacles. The relative sensitivity of - these organs to different chemical stimuli is not the same, but for most agents the mouth is the more sensitive. Quinine, histamine and 10% bile salts excite the musculature of the mouth directly. The range of chemical sensitivity in different coelenterates is discussed.
Mitotic Activity In The Female Mouse Pituitary
Authors: Kerr T. 
Published: April 2021

ABSTRACT
Mitotic activity in the three cell types of the distal lobe and in the cells of the proximal lobe of the female mouse pituitary during the normal oestrous cycle occurs in two maxima, one in late dioestrus and pro-oestrus and the other in late oestrus, with intervening minima. During a series of six oestrone injections there are again two maxima, after the first and last injections, and an intervening minimum after two and three injections. The relationships of these maxima and minima to the mitogenic properties of oestrone have been discussed.
On The Measurement and Modification of the Olfactory Responses of Blowflies
Authors: Crombie A. C. 
Published: April 2021

ABSTRACT
Froggat suggested that the native primary blowflies in Australia began to attack living sheep because of a change of habit which resulted in their becoming attracted to their wool for oviposition or larviposition. They were supposed to have acquired this habit during great droughts when the carcasses of sheep formed a large part of the carrion on which they normally oviposited. During these times the flies deposited their eggs, or living larvae, among the wool of the dead sheep. Then ‘the smell of the dead wool taught them that the allied damp or soiled wool (of living sheep) was of a similar character’, and consequently they became attracted to the latter for purposes of oviposition or larviposition (Tillyard & Seddon, 1933). Although the evidence seems to be overwhelmingly in favour of the belief that in Australia serious blowfly attack on sheep followed the spread of the introduced species of fly, Lucilia cuprina and L. tericata, Froggat’s suggestion was interesting, and it seemed worth while to investigate experimentally the degree to which the responses of blowflies to odours could be modified by their past experience during larval or adult life. Thorpe & Jones (1937), Thorpe (1938-9) and others have, of course, already shown that such changes of behaviour may occur in insects.
The Biological Action of Ions and the Concentration of Ions at Surfaces
Authors: Danielli J. F. 
Published: April 2021

ABSTRACT
It is pointed out that at the surface of a cell the absolute concentration of ions, and the ratios of the concentrations of the individual ions, are usually different from the corresponding quantities in the environmental fluid. It is suggested that the necessity for a Na : Ca ratio of the order of 50:1 in a physiologically balanced fluid is found because such a ratio in the environmental fluid produces a Na : Ca ratio of the order of unity at the cell surface. The concentrations of calcium and sodium ions at the surface of ovalbumin molecules are calculated. It is shown that calcium is bound (a) by electrostatic forces, (b) by formation of apparently unionized complexes with carboxyl groups. The complex formation obeys the law of mass action. The ratio, total Na:total Ca at the surface of various cells in physiological media is calculated from the electrokinetic potentials of the cells. The calculated ratio is of the order of unity. In two cases calculation of the maximum possible total Ca at the cell surface by two other independent methods gives values of the same order of magnitude as the calculation from electrokinetic potentials. It is shown that, where the toxic action of ions is due to complex formation with anions present at a surface, the logarithms of the equitoxic concentrations of the metals should be a linear function of the standard electrode potentials of the metals. Calculations show that the concentration of colloidal Fe at the surface of organisms in sea-water should be far greater than the concentration in the environment: it is suggested that marine plants derive their iron from this layer of adsorbed colloidal iron. A mechanism is suggested which provides for intense adsorption of drugs at specific surfaces.
Bafilomycins and concanamycins as inhibitors of V-ATPases and P-ATPases
Authors: Dröse Stefan , Altendorf Karlheinz 
Published: April 2021

ABSTRACT
Bafilomycins and concanamycins, two groups of the plecomacrolide-defined class of macrolide antibiotics, have recently been recognized as important tools for studying the physiological role of vacuolar-type, proton-translocating ATPases (V-ATPases) and ATPases with phosphorylated states (P-ATPases) in animal and plant cells as well as in yeast, fungi and bacteria. The following review will give an account of the classification and function of these antibiotics.
Characterisation of the Binding of Leukotriene B4 To Macrophages of the Rainbow Trout Oncorhynchus Mykiss
Authors: Bowden Linda A. , Fiore Stefano , Restall Colin J. , Serhan Charles N. , Rowley Andrew F. 
Published: April 2021

Summary
The binding of leukotriene B4 (LTB4) to macrophages from the head kidney of the rainbow trout Oncorhynchus mykiss was measured. Binding of [3H]LTB4 achieved a steady state after approximately 30 min of incubation and was 30 % reversible in the presence of a minimum of 1000-fold excess of LTB4. Scatchard analysis of the kinetics of LTB4 binding over a range of [3H]LTB4 concentrations indicated the existence of only a single class of receptor with a dissociation constant, KD, of 0.14 nmol l−1 and a maximum receptor density, Bmax, of approximately 17 800 sites per macrophage. The LTB4 receptor antagonist LY223982 was ineffective in inhibiting the binding of [3H]LTB4 to trout macrophages, although another receptor antagonist, LTB4-dimethylamide, displaced a maximum of 25 % of the total binding. LTB5 was equally effective as LTB4 at displacing [3H]LTB4, while other eicosanoids tested were without significant effect. It is suggested that the putative receptors for LTB4 on trout macrophages are similar to the high-affinity receptors for this compound reported to occur on mammalian granulocytes, although any structural similarities of the binding sites await further investigation.
Dynamic Imaging of Functional Nerve Terminals and Schwann Cells in Presynaptic ‘Nerve Plates’ Isolated From the Skate Electric Organ
Authors: Dowdall Michael J. , Green A. Chris , Richardson C. Mark 
Published: April 2021

ABSTRACT
The cholinergic innervation and its glial support were isolated in a functional state from the electric organ of the skate (Raja species) using a combined enzymatic and mechanical dissociation technique. Examination using light and electron microscopy showed that this ‘nerve plate’ is a disc-shaped structure several hundred micrometres in diameter consisting of a dense plexus of nerve terminals attached to branching nerve fibrils with numerous associated myelinating and perisynaptic Schwann cells. In unfixed nerve plates, depolarisation and Ca2+-dependent staining of the nerve terminals was seen with RH-414, a fluorescent marker for functional motor terminals. The components of the nerve plate could be loaded with the Ca2+-sensitive dyes Fluo-3 and Fura-2. Depolarisation of nerve plates loaded with either dye leads to an immediate increase of intracellular Ca2+ levels ([Ca2+]i) in the nerve terminals. This response was blocked by certain Ca2+ channel antagonists from the ω-conotoxin family. Glial cell responses to depolarisation were in general minimal. However, increases of [Ca2+]i were seen in these cells, but not in nerve terminals, during applications of ATP and acetylcholine. These results show that both nerve terminal and glial elements in this ‘nerve plate’ preparation are functional. The ease of this preparation and its functional reliability give it considerable potential as a useful model for elucidating presynaptic mechanisms.
An All-or-Nothing Rise in Cytosolic [Ca2+] in Vorticella SP.
Authors: Katoh Kaoru , Kikuyama Munehiro 
Published: April 2021

ABSTRACT
The peritrich ciliate Vorticella sp. exhibits cellular contraction of an all-or-nothing type in response to a mechanical stimulus. Many authors have suggested that the contraction may be controlled by the cytosolic level of Ca2+, since glycerol-extracted Vorticella contracts when Ca2+ is added to the external solution. However, no direct evidence for the increase in cytosolic [Ca2+] has yet been obtained in living Vorticella.
In the present study, by injecting a fluorescent Ca2+ indicator into living Vorticella and monitoring the cytosolic [Ca2+] with a confocal microscope, we have demonstrated that a mechanical stimulus evoked an all-or-nothing rise in cytosolic [Ca2+] (Ca2+ ‘spike’). The onset of the Ca2+ spike was similar in its time course to that of cellular contraction. Since the Ca2+ spike was recorded in a Ca2+-deprived solution containing 1 mmol l−1 EGTA, we concluded that release of Ca2+ from intracellular Ca2+ storage site(s) is responsible for the Ca2+ spike.
Modification of Ciliary Beating in Sea Urchin Larvae Induced by Neurotransmitters: Beat-Plane Rotation and Control of Frequency Fluctuation
Authors: Wada Yuuko , Mogami Yoshihiro , Baba Shoji A. 
Published: April 2021

ABSTRACT
The modification of ciliary beating by neurotransmitters in sea urchin larvae at the four-armed pluteus stage was analyzed in terms of the direction of beating and fluctuation in the beat period. Application of dopamine to Pseudocentrotus depressus causes the cilia to turn their beat plane but retain its characteristic planar feature up to the complete ‘reversal’ of the beat direction. This new type of response was termed the ‘beat-plane turning response’.
It was also found that neurotransmitters, especially dopamine and serotonin, can modify the length of the beating cycle in P. depressus and Hemicentrotus pulcherrimus. Dopamine decreased and serotonin increased the beat frequency averaged over the ciliated epithelium with the standard deviation from the mean increasing in the presence of dopamine and decreasing with serotonin. The beat-period fluctuation and its modification suggested by this observation was confirmed from measurements of the beating of individual cilia in the presence or absence of these neurotransmitters. Further analysis of the correlation between angular velocity and beat period indicates that variation in the beat period is not controlled by the same processes as those that modulate angular velocity.
These findings in sea urchin larvae suggest that both the stability and the direction of ciliary beating is under nervous control.
Hindleg Targeting During Scratching in the Locust
Authors: Matheson T. 
Published: April 2021

ABSTRACT
Intact locusts (Schistocerca gregaria) respond to tactile stimulation of their folded wings with rhythmic scratching movements of the ipsilateral hindleg that are directed towards the site of stimulation. For example, sites near the base of a wing elicit anteriorly directed scratches, whereas sites near the distal end of a wing elicit posteriorly directed scratches.
Locusts also scratch in response to tactile stimulation of a wing that is held outstretched in a posture similar to that normally adopted during flight, but they fail to alter their leg targeting to compensate for this changed position of the stimulus site. Instead, they scratch at an empty point in space near the abdomen, where the stimulus site would have been if the wing was folded in the resting posture. This inappropriate scratching does not result from mechanical constraints on the hindleg’s movement, from stimulation of abdominal sensory receptors, or from an absence of sensory information from the outstretched wing. It also persists when the metathoracic ganglion that controls movements of the hindlegs is isolated from the remainder of the central nervous system (CNS).
Targeted scratching of sites on the wings of locusts therefore appears to be fixed relative to body coordinates and does not take into account alterations of the target wing’s position.