bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Experimental Production of Goblet Cells and Inclusion Bodies
Authors: Meirowsky E. , Behr G. , Keys S. 
Published: April 2021

ABSTRACT
1. Goblet cells have been produced experimentally in rabbits’ and guineapigs’ corneae by ten methods.
2. Goblet cells can develop from ordinary epithelial cells.
3. The secretion antecedents originate in the nucleus.
4. Intranuclear and cytoplasmic inclusions can be produced experimentally and form the response mechanism of the cell towards animate and inanimate stimuli.
The Localization of Dehydrogenase Activity and Sulphydryl Groups in Wool and Hair Follicles by the use of Tetrazolium Salts
Authors: Rogers G. E. 
Published: April 2021

ABSTRACT
Three tetrazolium salts are used as histochemical indicators of dehydrogenase activity in the skin of sheep and other mammals. Of these compounds 2-(p-iodophenyl) -3-(p-nitrophenyl)-5-phenyl-tetrazolium chloride (INT) is shown to be the most satisfactory. It enables various histological structures of the wool follicle to be conveniently demonstrated.
In the presence of appropriate substrates and DPN and ATP, the intracellular deposition of the granular formazan in frozen sections has revealed the distribution of succinic, αglycerophosphoric, lactic, and malic dehydrogenases, and regions where some phosphorylated carbohydrate intermediates promote reduction. Metabolic activity in the Malpighian layers and in the undifferentiated epidermal cells of the hair matrix reduces INT enzymatically up to the pre-keratinous zone. Here the proteinbound sulphydryl groups reduce INT and produce intense red staining which is easily distinguished from the granular enzymic staining.
The distribution of cytochrome oxidase in the wool follicle resembles the distribution of dehydrogenase activity.
INT is used for the estimation of succinic dehydrogenase in skin and kidney tissues.
A Sharpening Machine for a New Type of Microtome Knife
Authors: Dilworth S. , Appleyard H. M. 
Published: April 2021

ABSTRACT
A description is given of the manufacture of a new type of microtome knife made from selected portions of discarded low tungsten steel power hacksaw blades. A machine for sharpening this type of knife is described. Its main feature is a lapping plate of 14 in. plate glass which can be adjusted for height to give cutting angles ranging from 24 to 32°, these angles being accurately reproducible on resharpening. Results of tests with a series of knives covering this range of cutting angles is given.
Studies of the Development of the imaginal Cuticle of Calliphora erythrocephala
Authors: Wolfe L. S. 
Published: April 2021

ABSTRACT
The development of the imaginal cuticle has been studied with particular emphasis on the microtrichia and the pupal moulting fluid.
The microtrichia are formed from acidophil filaments of epidermal cytoplasm which remain as the cuticular pore canals after secretion of the endocuticle. Microtrichia at the base of the bristles are associated with nerves.
The cuticle before emergence consists of a single-layered epicuticle less than 1 μ thick and an endocuticle 3–5 μ thick. The epicuticle and the endocuticle of the sclerites are completely sclerotized after emergence.
The pupal moulting fluid was found to be a clear, salt-free, watery liquid containing protein and lipoid and devoid of proteinases or chitinases. No evidence of dissolution was found in the pupal cuticle. The aqueous part of the moulting fluid is absorbed before emergence and this may be prevented by the addition of salts.
Evidence is presented for the formation of a denatured, hydrophobic, protein-lipoid film from the moulting fluid on the surface of the epicuticle after emergence.
Resistance to water loss develops after emergence and is not entirely dependent on cuticle darkening and hardening. A film of moulting fluid spread and dried on natural and artificial membranes lowers the rate of water permeation. Such films possibly are operative in regulation of water loss from the imaginal cuticle immediately after emergence. Waxy materials appear on the cuticle surface during the hardening phase. Their possible origin is discussed.
On the Relationship between Mammary, Sweat, and Sebaceous Glands
Authors: Carlisle D. B. 
Published: April 2021

ABSTRACT
Stages are described in the development of the mammae of male rabbits responding to regular injections of oestrogen and progesterone. It is suggested that the extra mammary lobes which develop under this treatment are derived from hair follicles and sebaceous glands by the loss of the hairs from the follicles and the proliferation of sebaceous glands and ducts. This may throw light on the phylogenetic origin and homology of the mammary gland.
The Post-embryonic Development of the Tracheal System in Drosophila melanogaster
Authors: Whitten Joan M. 
Published: April 2021

ABSTRACT
The fate of the tracheal system is traced from the first larval instar to the adult stage. The basic larval pattern conforms to that shown for other Diptera Cyclorrhapha (Whitten, 1955), and is identical in all three instars.
According to previous accounts the adult system directly replaces the larval: the larval system is partly shed, partly histolysed, and the adult system arises from imaginai cell clusters independently of the preceding larval system.
In contrast, it is shown here that in the cephalic, thoracic, and anterior abdominal region there is a definite continuity in the tracheal system, from larval, through pupal to the adult stage, whereas in the posterior abdominal region the larval system is histolysed, and the adult system is independent of it in origin. Moreover, in the pupal stage this region is tracheated by tracheae arising from the anterior abdominal region and belonging to a distinct pupal system.
Moulting of the tracheal linings is complete at the first and second larval ecdyses, but incomplete at the third larval-pupal and pupal-adult ecdyses. In consequence, in both pupal and adult systems there are tracheae which are secreted around preexisting tracheae, others formed as new ‘branch’ tracheae, and those which have been carried over from the previous instar. In the adult the newly formed tracheae of the posterior abdominal region fall into a fourth category. Most of the adult thoracic air sacs correspond to new ‘branch’ tracheae of other instars.
The pre-pupal moult and instar are discussed with reference to the tracheal system and tentative suggestions are made concerning the true nature of the pre-pupal cuticle. There is no pre-pupal tracheal system.
Events traced for Drosophila would seem to be general for Cyclorrhapha, both Acalypterae and Calypterae. The separate fates of the anterior and posterior abdom inal systems, in contrast with the straightforward development in Dipterc Nematocera, would appear to mark a distinct step in the evolution of the system in Diptera.
The Fixation of Adipose Fat by Potassium Dichromate
Authors: Chou J. T. Y. 
Published: April 2021

ABSTRACT
Ordinary adipose fat globules can be rendered resistant to paraffin embedding by the immersion of suitably fixed tissues in a saturated solution of potassium dichromate at 37° C for 7 weeks. Xylene has less tendency to remove the postchromed fat than chloroform, benzene, or toluene.
Adipose fat is usually dissolved out of the tissues during dehydration or embedding. Empty spaces are therefore usually seen in paraffin sections wherever fat globules were present during life. Several authors (Kaufmann and Lehmann, 1926 a, b; 1928; Smith, Mair, and Thorpe, 1909) have claimed that potassium dichromate can in certain circumstances be used to fix adipose fat in such a way that it is retained in paraffin sections, but a full study of this subject has not previously been made. My object has been to find a reliable method of fixing adipose fat by potassium dichromate in such a form that it is not dissolved away when paraffin sections are made.
The Role of Carbonic Anhydrase in Respiration, ion Regulation and Acid-Base Balance in the Aquatic Crab Callinectes Sapidus and the Terrestrial Crab Gecarcinus Lateralis
Authors: Henry Raymond P. , Cameron James N. 
Published: April 2021

ABSTRACT
The enzyme carbonic anhydrase (CA), which is concentrated mainly in the osmoregulatory tissue of the gills, appears to be required for ion regulation but not for CO2 excretion. An injection of the CA inhibitor acetazolamide produced an inhibition of between 90 and 100 %, which took 6 h to be fully effective, and 48 –96 h to wear off. During the period of inhibition in Callinectes sapidus there was no change in either O2 uptake or CO2 excretion, nor was there any increase in blood In blue crabs acclimated to 250mosM salinity, at which the animals are ion regulators, inhibition of CA caused both Na+ and Cl− concentrations in the blood to be lowered, with Cl− being lowered to a greater degree. As a result of an increase in the Na+–Cl− difference the animal experienced a ‘metabolic’ alkalosis: elevated blood pH and HCO3− at constant The data are consistent with the hypothesis that branchial CA functions in providing H+ and HCO3− as counterions for Na+ and Cl− transport through the hydration of respiratory CO2.
In the terrestrial Gecarcinus lateralis, inhibition of CA caused an increase in blood but did not alter O2 uptake or CO2 excretion. After an initial acidosis, blood pH and HCO2− increased and remained elevated. Blood osmolality, Na+, Cl− and Ca2+ concentrations all increased, and the animals experienced a high rate of mortality. These data suggest that CA in the land crab is also important in blood ion regulation, probably to combat desiccation.
The Transition Between Branchial Pumping and Ram Ventilation in Fishes: Energetic Consequences and Dependence on Water Oxygen Tension
Authors: Steffensen John Fleng 
Published: April 2021

ABSTRACT
Ram ventilation has been demonstrated in rainbow trout, Salmo gairdneri. The swimming speed eliciting the transition in mode of ventila-tion increased with declining ambient water oxygen tension . The mode of ventilation of fish swimming at a constant speed could be altered by controlled variations in . Oxygen consumption decreased by 10·2% when rainbow trout, swimming at a constant speed, shifted from active to ram ventilation. This difference can be ascribed to a lowering of the energetic cost of active ventilation as well as improved drag characteristics. Water velocity required for the transition from active to ram ventila-tion in the resting sharksucker, Echeneis naucrates, increased with decreas-ing . The results show that water oxygen tension is an important stimulus for setting the ventilatory mode in rainbow trout and sharksucker.
Kinetics of Branchial Calcium Uptake in the Rainbow Trout: Effects of Acclimation to Various External Calcium Levels
Authors: Perry S. F. , Wood C. M. 
Published: April 2021

ABSTRACT
Calcium uptake in freshwater rainbow trout (Salmogairdnert) under control conditions (external [Ca2+] ≃ 1·8mequivl−1, [NaCl] ≃ 0·8mequiv 1−1) occurred at approximately equal rates (12–15 equiv kg−1 h−1) through the gills and the general body surface in vivo. The gut was not involved. Under the same conditions, in vitro branchial in an isolated, saline-perfused head preparation was equal to that in vivo. The cells involved in are mainly located on lamellae rather than on filaments since ∼ 95 % of occurred across the arterio-arterial circulation of the gill. in vitro, displayed Michaelis-Menten kinetics. Acclimation to low external [Ca2+] (50μequivl−1; unchanged [NaCl]) for 1 day caused a five-fold stimulation of characterized by decreased Km and increased Jmax Longer periods of low [Ca2+] acclimation resulted in changes of Jmax only. Jmax gradually returned towards control levels as acclimation time increased, but was still elevated after 30 days. Acclimation to low ambient [Ca2+] caused proliferation and increased exposure of lamellar chloride cells which were correlated with increased Jmax. Fish exposed to high external [Ca2+] (10 μequiv 1−1; unchanged [NaCl]) displayed reduced Similar changes in were observed during in vivo experiments. Plasma Ca2+ concentration remained constant regardless of external [Ca2+], while plasma Na+ and Cl− levels were transiently reduced at 1 day low [Ca2+] exposure but had recovered by 7 days. A possible role for cortisol in Ca2+ regulation is discussed based on observations of cortisol-stimulated lamellar chloride cell proliferation and and elevated plasma [cortisol] in low-[Ca2+] acclimated fish.
Epithelial Amino Acid Transport in Marine Mussels: Role in net Exchange of Taurine Between Gills and Sea water
Authors: Wright Stephen H. , Secomb Timothy W. 
Published: April 2021

ABSTRACT
The exchange of taurine across epidermal epithelia of Mytilus edulis and M. califonianus was studied using radiotracer and chromatographic (HPLC) methods. Gill levels of taurine in both species ranged from 60 to 70μmol g −1 wet weight. Net uptake of taurine, determined using HPLC, occurred down to ambient concentrations as low as 10 nmol 1 −1. The rate of taurine loss from mussels was about 0·02 μmolg −1 wet body weight h −1, and when exposed to amino-acid-free sea water, external taurine concentration increased until a steady-state of about 15 nmol 1 −1 was achieved. Mussels accumulated inhibitors of taurine transport at rates which were directly related to their relative inhibitory capacities: β-alanine&gt;β-aminobutyric acid ≃ γ-aminobutyric acid (GABA). Addition of large concentrations (50–200 μmoll −1) of GABA resulted in a rapid increase in taurine concentration in test solutions. This increase was consistent with a model in which GABA both competitively inhibits the reaccumulation of endogenous taurine lost from epidermal tissues, and accelerates the exchange diffusion of taurine from surface cells. We suggest that epidermal taurine transport in Mytilus assists in the maintenance of large intracellular taurine concentrations, and can serve to reaccumulate up to 30% of the taurine lost from surface tissues by passive processes.
The Effects of Forced and Voluntary Diving on Ventilation, Blood Gases and Ph in the Aquatic Amphibian, Xenopus Laevis
Authors: Boutilier Robert G. , Shelton Graham 
Published: April 2021

ABSTRACT
Pre-and post-dive breathing patterns, blood oxygenation and acid-base balance have been examined in voluntarily and forcibly submerged Xenopus laevis. Enforced 30-min dives led to a large acidosis with both respiratory (CO2) and metabolic (lactic acid) components. Complete recovery of the arterial blood variables after such dives took more than 4h. Lung ventilation (measured by a pneumotachograph) following enforced dives was always markedly elevated compared with levels either before or after voluntary dives of the same duration. In undisturbed Xenopus, diving freely for periods of 30 min or more, there was no accumulation of lactic acid and the fall in blood oxygen, increase in CO2 and the associated respiratory acidosis were all corrected within the first few breaths upon surfacing. The evidence presented here leads us to conclude that anaerobiosis is unimportant during voluntary dives, even when these are of considerable duration.
Recovery From Anaerobiosis in the Intertidal Worm Sipunculus Nudus: I. Restoration of Aerobic, Steady-State Energy Metabolism
Authors: Pörtner H. O. , Vogeler S. , Grieshaber M. K. 
Published: April 2021

ABSTRACT
Recovery from 24 h of anaerobiosis was investigated in Sipunculus nudus L. by monitoring changes in the concentrations of anaerobic metabolites in the musculature and in the coelomic plasma. The metabolic events in animals collected during March and October were compared.
Anaerobiosis led to an increase of succinate, propionate and acetate in the muscle tissues and the coelomic plasma. Strombine, octopine and alanine (predominantly L-rather than D-alanine) accumulated in the musculature, whereas aspartate and phospho-L-arginine levels decreased. A higher metabolic rate was observed during anaerobiosis in October than in March animals, as indicated by the higher amounts of strombine, octopine and acetate formed. An increase in metabolic rate appears to entail an increase of flux through the Embden–Meyerhof pathway which favours the accumulation of direct derivatives of pyruvate.
During recovery, regeneration of phospho-L-arginine occurred during the first 3 h, whereas disposal of succinate, octopine and propionate was observed during the entire 24-h period of recovery. Strombine, alanine and, to a lesser extent, acetate contents remained elevated. The concentration of D-alanine approached that of L-alanine during recovery, indicating the activity of alanine racemase. Malate levels increased transiently, possibly linked to the repletion of the aspartate pool.
In October animals, strombine seemed to accumulate transiently during initial recovery, indicating that the energy demand was not met by aerobic metabolism alone. In contrast to the situation in March animals, however, anaerobic glycolysis during recovery obviously becomes important only when the metabolic rate during anaerobiosis was high enough.
Oviposition Digging in the Grasshopper: II. Descending Neural Control
Authors: Thompson Karen J. 
Published: April 2021

ABSTRACT
Transection of the ventral nerve cord of female grasshoppers activates the rhythmical motor programme for oviposition digging. Electrical stimulation of the cut nerve cord had the following effects on elicited oviposition motor activity: (i) short- and long-lasting inhibition of activity, (ii) phase resetting and (iii) modulation of burst frequency. Cold saline applied to the nerve cord reversibly elicited the oviposition motor programme. The effects of transection and stimulation at different levels of the nerve cord indicate that the higher neural control of the motor pattern is not confined to the head ganglia, but includes a thoracic component. In intracellular recordings of ventral opener motoneurones, stimulus-related IPSPs were observed in response to stimulation of the cut nerve cord. Stimulation also abolished slow wave synaptic input to the motoneurones during inhibition of the oviposition motor programme. It is suggested that oviposition digging behaviour is initiated and maintained by a mechanism of ‘release’ from descending neural inhibition.
Resting Potential and Potassium-Selective Electrode Measurements in Locust Skeletal Muscles
Authors: Leech C. A. 
Published: April 2021

ABSTRACT
The membrane of locust skeletal muscle fibres is permeable to both potassium and chloride ions in the resting state and has a potassium selectivity similar to that of a potassium electrode (Usherwood, 1967). The experiments described here were performed on the isolated retractor unguis muscle of the locust Schistocerca gregaria. The composition of the standard locust saline was similar to that of Hoyle (1953) except that in most experiments the HPO4/HCO3 buffer was replaced by Tris-maleate (pH 6·8). Conventional electrophysiological techniques were used and electrodes had tip potentials of less than 5 mV.
Release of Octopamine From the Photomotor Neurones of the Larval Firefly Lanterns
Authors: Carlson Albert D. , Jalenak Mary 
Published: April 2021

ABSTRACT
The biogenic amine, octopamine, has been proposed as the transmitter in the firefly light organ (Evans, 1980; Robertson, 1981). Whereas initial studies implicated adrenaline (Smalley, 1965; Carlson, 1968a), octopamine was found to be more potent in inducing luminescence than any amine other than synephrine (Carlson, 1968b). Octopamine, but not synephrine, was found in adult lantern segments (Robertson & Carlson, 1976; Copeland & Robertson, 1982) and in larval lantern tissue (Christensen, Sherman, McCaman & Carlson, 1983). Evidence that cyclic nucleotides mediate the effect of octopamine was obtained by Oertel & Case (1976). An octopamine-sensitive adenylate cyclase has been found in the larval lantern and application of exogenous octopamine strongly stimulates cyclic AMP production in adult (Nathanson, 1979) and larval (Nathanson & Hunnicutt, 1979) light organs.
Amino Acid Receptor-Mediated Transmission at Primary Afferent Synapses in Rat Spinal Cord
Authors: Jessell T. M. , Yoshioka K. , Jahr C. E. 
Published: April 2021

ABSTRACT
Intracellular recording techniques have been used to provide information on the identity of excitatory transmitters released at synapses formed between dorsal root ganglion (DRG) and spinal cord neurones in two in vitro preparations. Explants of embryonic rat DRG were added to dissociated cultures of embryonic dorsal horn neurones and synaptic potentials recorded intracellularly from dorsal horn neurones after DRG explant stimulation. More than 80% of dorsal horn neurones received at least one fast, DRG-evoked, monosynaptic input. In the presence of high divalent cation concentrations (5 mmoll−1 Ca2+, 3mmoll−1 Mg2+) the acidic amino acid receptor agonists, L-glutamate, kainate (KA) and quisqualate (QUIS) excited all dorsal horn neurones which received a monosynaptic DRG neurone input, whereas L-aspartate and.V-methyl-D-aspartate (NMDA) had little or no action. 2-Amino-5-phosphonovalerate (APV), a selective NMDA receptor antagonist, was relatively ineffective at antagonizing DRG-evoked synaptic potentials and L-glutamate-evoked responses. In contrast, kynurenate was found to be a potent antagonist of amino acid-evoked responses and of synaptic transmission at all DRG-dorsal horn synapses examined. The blockade of synaptic transmission by kynurenate appeared to result from a postsynaptic action on dorsal horn neurones.
Intracellular recordings from motoneurones in new-born rat spinal cord were used to study the sensitivity of the la excitatory postsynaptic potential (EPSP) to antagonists of excitatory amino acids. Superfusion of the spinal cord with APV did not inhibit the la EPSP but did suppress later, polysynaptic components of the afferent-evoked response. Kynurenate was a potent and selective inhibitor of the la EPSP, acting via a postsynaptic mechanism. These findings indicate that L-glutamate, or a glutamate-like compound, but not L-aspartate, is likely to be the predominant excitatory transmitter that mediates fast excitatory postsynaptic potentials at primary afferent synapses with both dorsal horn neurones and motoneurones.
Regulation of Ion Channels By Inositol Trisphosphate and Diacylglycerol
Authors: Berridge Michael J. 
Published: April 2021

ABSTRACT
Calcium-mobilizing receptors function to regulate ion channels located not only in the plasma membrane but also across the membranes of intracellular organelles, particularly the endoplasmic reticulum. A characteristic feature of such receptors is that they stimulate the hydrolysis of an inositol lipid to generate a pair of second messengers. Diacylglycerol remains within the plasma membrane where it activates protein kinase C leading to the phosphorylation of proteins some of which may regulate specific ionic channels, such as the calcium-dependent potassium channel or the Na+/H+ exchanger which regulates intracellular pH. The inositol trisphosphate (Ins l,4,5P3) released to the cytosol functions as a second messenger to release calcium from the endoplasmic reticulum. The Ins 1,4,5P3 acts on a specific receptor to enhance the passive efflux of calcium while having no effect on the active calcium pump. There are indications that this Ins 1,4,5P3-induced release of calcium from an internal membrane store might provide an explanation of excitation-contraction coupling in skeletal muscle. Skinned skeletal muscle cells can be induced to contract by adding Ins l,4,5P3. Mobilization of calcium from intracellular reservoirs by Ins l,4,5P3 may thus prove to be a ubiquitous and fundamental mechanism for regulating cellular activity.