bluuebunny/crossref_metadata_2025 huggingface dataset:
Colour Learning in the Hawkmoth Macroglossum Stellatarum
Authors: Kelber Almut
Published: April 2021

Newly eclosed specimens of the day-active hawkmoth Macroglossum stellatarum were trained to artificial flowers in dual-colour choice situations. Learning curves were obtained from learning and reversed-learning experiments. Initially, learning behaviour was influenced by innate colour preferences. In comparison with other lepidopterans, Macroglossum stellatarum learns well. When trained in a dual-choice situation, the moths learned not only to visit the rewarded colour but also to avoid the unrewarded colour. These good learning abilities are discussed in the context of the biology of the species.
A Novel Subunit of Vacuolar H+-ATPase Related to The b Subunit of F-ATPases
Authors: Supekova Lubica , Sbia Mohammed , Supek Frantisek , Ma Yuemei , Nelson Nathan
Published: April 2021

The subunit structure of the vacuolar H+-ATPase (V-ATPase) membrane sector is not entirely known. The proteolipid is the only subunit that has been implicated in the mechanism of energy transfer in the enzyme. We have identified a protein (M16) that co-purifies with the V-ATPase complex from bovine chromaffin granules. Information obtained from the amino acid sequence of a proteolytic fragment of M16 was used to clone a bovine adrenal cDNA encoding this protein. The cDNA encodes a hydrophilic protein of 118 amino acid residues with a calculated molecular mass of 13 682 Da. Amino acid sequence analysis revealed that M16 exhibits a significant homology to subunit b of F-ATPases. M16 is smaller than subunit b and contains no apparent transmembrane segment in its N terminus. The remainder of subunit b is related to M16 not only by its amino acid sequence but also in its predicted structure of helix–turn–helix. The structural and evolutionary implications of these findings are discussed.
Peptidergic Regulation of Chromatophore Function in the European Cuttlefish Sepia Officinalis
Authors: Loi Poh Kheng , Saunders Robin G. , Young Doug C. , Tublitz Nathan J.
Published: April 2021

Color patterning in cephalopod molluscs involves activation of a peripheral chromatophore system that is under neuromuscular control. The complex behavior of individual chromatophores is mediated by a specific set of muscles, the chromatophore muscles, that receive direct innervation from the central nervous system. To date, glutamate is the only excitatory transmitter that has been proposed to act at the chromatophore neuromuscular junction of cephalopods. We present data demonstrating that the chromatophore muscles in the European cuttlefish Sepia officinalis are also regulated by the FMRFamide family of neuropeptides. Using an in vitro chromatophore bioassay, it has been determined that several FMRFamide-related peptides (FaRPs) are potent excitors of the chromatophore muscles, causing chromatophore expansion. Immunocytochemical analyses of the central nervous system using an FMRFamide antibody revealed the presence of FMRFamide-like immunoreactive cell bodies in the posterior chromatophore lobes, the region of the brain containing the chromatophore motoneurons of the fin and mantle. FMRFamide-like immunoreactivity was also seen in the periphery, in the nerves around the chromatophores and in close apposition to the muscles in the chromatophore layer of the fin. HPLC analysis of the fin dermis isolated four bioactive peaks that were FMRFamide-immunoreactive when tested on an immunoblot assay. Two of these peaks co-eluted with known FaRPs, FMRFamide and ALSGDAFLRFamide, a decapeptide isolated from squid. Taken together, these data suggest that the FaRPs are likely to be endogenous excitors of the chromatophore muscles in cephalopods.
Ca2+ Transport Processes of Lobster Hepatopancreatic Brush-Border Membrane Vesicles
Authors: Zhuang Zhenpeng , Ahearn Gregory A.
Published: April 2021

45Ca2+uptake by hepatopancreatic brush-border membrane vesicles of Atlantic lobster (Homarus americanus) occurred by a combination of three independent processes: (1) an amiloride-sensitive carrier-mediated transport system; (2) an amiloride-insensitive carrier-mediated transport system; and (3) a verapamil-inhibited channel process responsive to transmembrane potential. Both carrier-mediated processes were antiporters and capable of exchanging external Ca2+ with intravesicular Na+ or H+. The kinetic parameters of both carrier-mediated processes have been reported previously. External amiloride and Zn2+ were both competitive inhibitors of 45Ca2+ influx, reducing entry of the divalent cation at a single binding site with Ki values of 370 μmol l−1 for amiloride and 940 μmol l−1 for Zn2+. It is concluded that the mechanisms controlling Ca2+ entry into hepatopancreatic epithelial cells include a previously reported electrogenic 2Na+/1H+ antiporter, an electroneutral 2Na+/1Ca2+ antiporter and a verapamil-sensitive Ca2+ channel, which might also be used for the entry of Zn2+ and possibly other heavy metals. Evidence from an equilibrium-shift experiment, based on the thermodynamics of a coupled transport process, suggested that both monovalent (Na+) and divalent (Ca2+ and Zn2+) cations may enter hepatopancreatic epithelial cells through a common carrier-mediated transport protein. This suite of hepatopancreatic brush-border Ca2+ transport processes qualitatively resembles that previously reported for the luminal membrane of lobster antennal glands and suggests that crustacean epithelial cells from different organs may handle this divalent cation by similar means.
A Computational Fluid Dynamics Study of Tadpole Swimming
Authors: Liu Hao , Wassersug Richard J. , Kawachi Keiji
Published: April 2021

The hydrodynamics and undulating propulsion of tadpoles were studied using a newly developed two-dimensional computational fluid dynamics (CFD) modeling method. The mechanism of thrust generation associated with the flow patterns during swimming is discussed. Our CFD analysis shows that the kinematics of tadpoles is specifically matched to their special shape and produces a jet-stream propulsion with high propulsive efficiency, as high as that achieved by teleost fishes. Investigation of the effect of Reynolds number indicates that the Froude efficiency increases with increasing Reynolds number with no ceiling in generating the jet-stream propulsion. Further studies using tadpole- and fish-shaped models with hindlimbs added to their body profiles reveal that the tadpole shape – a globose head with a tapered tail and hindlimbs at the base of the tail – allows tadpoles, but not fish, to develop hindlimbs with very little handicap on propulsion. The shapes and kinematics of tadpoles appear to be specially adapted to the requirement of these organisms to transform into frogs.
The Effect of Formaldehyde Exposure on the Transmembrane Distribution of Free Amino Acids in Muscles of Mytilus Edulis
Authors: Zachariassen Karl Erik , Olsen Anders Johny , Aunaas Tore
Published: April 2021

Free amino acids in the posterior adductor muscle of mussels (Mytilus edulis) occur in a high-energy gradient group, with energy gradients of 15–18 kJ mol−1 (aspartate, beta-alanine, glycine, taurine and threonine), and a low-energy gradient group, with energy gradients around 12 kJ mol−1 (the rest of the amino acids). Two of the amino acids, glycine and taurine, are present at intracellular concentrations of 100–150 mmol kg−1, while the other amino acids occur at concentrations below 50 mmol kg−1.

Exposure of mussels to formaldehyde causes a marked influx of Na+ into the muscle cells and an increase in cellular water content. The Na+ gradient, which provides the energy for the cellular accumulation of free amino acids, is reduced. The drop in the Na+ gradient is accompanied by a nearly proportional reduction in the energy gradients of all amino acids in the high-energy gradient group and a 150 mmol kg−1 reduction in the total intracellular concentration of free amino acids. Most of this reduction is made up by the Na+-dependent amino acids aspartate, glycine and threonine, the concentrations of which are reduced by about 120 mmol kg−1.

The transmembrane distribution of the low-energy gradient amino acids seems to be independent of the Na+ gradient, and these amino acids display only moderate reductions in their intracellular concentrations when the Na+ gradient is reduced.

The reduction in the concentrations of the free amino acids appears to be a volume-regulatory response, serving to bring the cell volume back to its optimal level after the formaldehyde-induced Na+ influx has caused a cellular swelling. The basis of these differences in Na+-dependence is discussed.

Taurine, which is the quantitatively dominating organic solute and an important volume-regulatory osmolyte in mussels, does not take part in the volume-regulatory response. This may be due the role of taurine in the protection against potentially toxic Ca2+, which enters the cells in large quantities when mussels are exposed to formaldehyde.
Magnetic Compass Cues and Visual Pattern Learning in Honeybees
Authors: Frier Helen J. , Edwards Emma , Smith Claire , Neale Susi , Collett Thomas S.
Published: April 2021

We show that honeybees can learn to distinguish between two 360 ° panoramic patterns that are identical except for their compass orientation; in this case, the difference was a 90 ° rotation about the vertical axis. To solve this task, bees must learn the patterns with respect to a directional framework. The most powerful cue to direction comes from the sky, but discrimination between patterns is possible in the absence of celestial information. Under some conditions, when other potential directional cues have been disrupted, we show that bees can use a magnetic direction to discriminate between the patterns.
An Increase in Activity of Serotonergic Retzius Neurones May not be Necessary for the Consummatory Phase of Feeding in the Leech Hirudo Medicinalis
Authors: Wilson R. J. A. , Kristan W. B. , Kleinhaus A. L.
Published: April 2021

During the consummatory phase of feeding, in which blood is ingested, medicinal leeches display a characteristic set of behaviours: they extend their jaws, are less responsive to sensory input, produce mucus, relax the body wall and exhibit waves of peristalsis that can run the length of the body. Earlier reports suggested that this pattern of behaviour is orchestrated by serotonin released from Retzius cells in response to the appropriate sensory stimulation of the lip.

We have developed a semi-intact preparation in which only the nervous system in the posterior half of the leech was exposed. The front half of the leech was free to explore, bite through and feed until satiated from a blood-filled sausage casing while continuous intracellular and extracellular recordings were made from identified cells and the nerve roots of the exposed segments.

Prior to attachment of the animal to the feeding device, the firing frequency of the Retzius cell increased transiently during spontaneous movements or tactile stimuli to its front or posterior end. In contrast, Retzius cell activity decreased after the anterior sucker attached to the membrane of the feeding device at about the time when ingestion was initiated.

Increased activity of Leydig cells, which are known to modulate several circuits in the leech, was also associated with exploration. However, unlike that of Retzius cells, the activity of Leydig cells increased significantly following the onset of consumption.

These results suggest that increased activity of Retzius cells in midbody ganglia is not a prerequisite for the consummatory phase of feeding and raises questions regarding the role of serotonin in regulating this behaviour.
Control of the Systemic Heart and the Portal Heart of Myxine Glutinosa
Authors: Johnsson Marianne , Axelsson Michael
Published: April 2021

The effects of preload and afterload on the performance of the systemic heart of the hagfish Myxine glutinosa were investigated before and during sotalol treatment using an in situ perfusion technique. Elevation of input pressure (preload) increased flow by means of increased stroke volume and heart rate in accordance with Starling’s law of the heart, while increased output pressure (afterload) decreased flow mainly because of decreased stroke volume. Treatment with the β-adrenoceptor antagonist sotalol did not change the quality of the responses to increased preload or afterload, although power output decreased by 40 % and flow rate was reduced by 35 % mainly due to a decrease in heart rate.

Isolated preparations of the systemic heart and the portal heart provided information on the chronotrop effects of different agonists and antagonists. Both the systemic heart and the portal heart were insensitive to adrenergic and cholinergic agonists, adrenocorticotropic hormone and the cholinoceptor antagonist atropine. Sotalol treatment lowered the rate of spontaneous contractions by 30 % in the systemic heart preparation and by 21 % in the portal heart preparation.

This study has given further evidence for the existence of a tonic β-adrenoceptor stimulation of the hagfish systemic heart and portal heart, and demonstrated the importance of that stimulation in maintaining systemic heart performance.
Active Absorption Of Na+ and CL− Across the Gill Epithelium of the Shore Crab Carcinus Maenas: Voltage-Clamp and Ion-Flux Studies
Authors: Riestenpatt Sven , Onken Horst , Siebers Dietrich
Published: April 2021

Mechanisms of active NaCl uptake across the posterior gills of the shore crab Carcinus maenas were examined using radiochemical and electrophysiological techniques. In order to measure short-circuit current (Isc), transepithelial conductance (Gte) and area-related unidirectional fluxes of Na+ and Cl−, single split gill lamellae (epithelium plus cuticle) of hyperregulating shore crabs were mounted in a modified Ussing chamber. The negative short-circuit current measured with haemolymph-like NaCl saline on both sides of the epithelium could be inhibited by application of basolateral ouabain (ouabain inhibitor constant KOua=56±10 μmol l−1), 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB; KNPPB=7.5±2.5 μmol l−1) or Cs+ (10 mmol l−1). From the apical side, Isc was nearly completely blocked by Cs+ (10 mmol l−1) or Ba2+ (15 mmol l−1), whereas apical addition of furosemide (1 mmol l−1) resulted in only a small current decrease. Cl− influxes were linearly related to negative Isc.

The ratio between net influxes of Cl− and Na+ was found to be approximately 2:1. With a single membrane preparation, achieved by permeabilizing the basolateral membrane with amphotericin B, Cl− influxes which were driven by a concentration gradient were shown to depend on the presence of apical Na+ and K+. On the basis of these observations, we propose that active and electrogenic absorption of NaCl across the gill epithelium of hyperregulating shore crabs proceeds as in the thick ascending limb of Henle’s loop in the mammalian nephron. Accordingly, branchial NaCl transport is mediated by apical K+ channels in cooperation with apical Na+/K+?2Cl− cotransporters and by the basolateral Na+/K+-ATPase and basolateral Cl− channels.
Autonomic Nervous Control of Heart Rate in Muskrats During Exercise in Air and Under Water
Authors: Signore Pierre E. , Jones David R.
Published: April 2021

Neural control of the cardiac responses to exercise in air (running) and under water (diving) was studied in the muskrat (Ondatra zibethicus) by means of acute pharmacological blockade with the muscarinic blocker atropine and the β-adrenergic blocker nadolol. Saline injection was used as a control. Controls running on a treadmill showed a marked increase in heart rate with exercise. Atropine-treated animals had a higher resting heart rate than controls, but heart rate still increased with running. Nadolol-treated animals had a lower resting heart rate than controls and displayed a less pronounced increase in heart rate with running than controls. Animals treated with a combination of atropine and nadolol had a resting heart rate similar to that of controls but their heart rate was unaffected by running. Thus, exercise tachycardia in muskrats is due to activation of the sympathetic system and also to a reduction in parasympathetic tone. Heart rate decreased markedly during voluntary submergence in controls but rose as muskrats swam submerged against increasing water flows. Nevertheless, diving bradycardia was still present. Free-diving bradycardia and the relative increase in heart rate with underwater exercise were abolished by atropine and unaffected by nadolol. Hence, unlike the cardiac response to exercise in air, the cardiac response to underwater exercise is due only to a reduction in parasympathetic tone. Injection of the β-adrenergic agonist isoproterenol markedly increased heart rate in air but had little effect during voluntary and forced dives, indicating a marked decrease in the sensitivity of cardiac cells to adrenergic stimulation during submergence. These results strongly suggest that accentuated antagonism between the two branches of the autonomic nervous system occurs during diving so that parasympathetic influences on the heart predominate and inhibit any chronotropic response to adrenergic stimulation.
Seasonal-, Tidal-Cycle- and Microhabitat-Related Variation in Membrane Order of Phospholipid Vesicles from Gills of the Intertidal Mussel Mytilus Californianus
Authors: Williams E. Eugene , Somero George N.
Published: April 2021

Alterations in the order, or fluidity, of cellular membranes in response to variations in environmental temperature are well known. The mussel Mytilus californianus, a common inhabitant of mid-intertidal regions along the Pacific coast of North America, can experience large (20 °C or more) and cyclic (every 6 h) changes in body temperature (Tb ) during tidal cycles. In the present study, we explore membrane order during seasonal and tidal temperature cycles and find that vesicles prepared from gill phospholipids exhibit significant seasonal differences in order that are consistent with homeoviscous adaptation and suggest winter-acclimatization to mean Tb values and summer-acclimatization to upper extreme Tb values or to large cyclic thermal fluctuations, despite repeated resubmergence in sea water at 10 °C during both seasons. Phospholipid vesicles prepared from the gills of mussels acclimated for 6 weeks to constant high or low temperatures in the laboratory fail to exhibit temperature-compensatory differences in order. In addition, during the summer, mussels inhabiting high intertidal sites, but not those from low sites, possess the ability to alter membrane order rapidly (within hours). This alteration of order appears to represent a mechanism designed to offset the thermal variations encountered during the tidal cycle. Thus, M. californianus have the ability to adjust membrane order on seasonal as well as hourly time scales and do so on the basis of their height in the intertidal region.
Design of the Oxygen and Substrate Pathways: II. Defining the Upper Limits of Carbohydrate and Fat Oxidation
Authors: Roberts Thomas J. , Weber Jean-Michel , Hoppeler Hans , Weibel Ewald R. , Taylor C. Richard
Published: April 2021

This paper quantifies maximal flows of carbohydrates and lipids through the pathways supplying the mitochondria. Maximal flow rates are the main functional parameter used in testing the principle of symmorphosis, which states that structural capacities are quantitatively matched to functional demand. Only under rate-limiting conditions will all of the structural capacity be used. Dogs and goats were compared to obtain large differences in absolute rates. We exercised the animals for long enough to reach steady-state O2 and CO2 exchange rates at intensities eliciting 40 %, 60 %. and 85 % of the maximal rate of oxygen consumption (). We then calculated rates of fat and carbohydrate oxidation from the ratio of CO2 produced to O2 consumed (the respiratory exchange ratio). The dog’s was more than twice that of the goat (6517 versus 3026 μmol O2 kg−1 min−1). We found the same pattern of fuel selection as a function of exercise intensity in both species, and it appears to be general to mammals. Maximal rates of fat oxidation were reached at 40 % exercise intensity, where 77 % of the energy was supplied by fat. As exercise intensity increased, all additional energy was supplied by carbohydrates. We conclude that the partitioning of fuel supply to the fat and carbohydrate pathways follows the same pattern in both dogs and goats.
Design of the Oxygen and Substrate Pathways: III. Partitioning Energy Provision from Carbohydrates
Authors: Weber Jean-Michel , Roberts Thomas J. , Vock Ruth , Weibel Ewald R. , Taylor C. Richard
Published: April 2021

This paper quantifies maximal fluxes through the pathway supplying carbohydrates to the mitochondria of muscle cells. Continuous infusions of D-[3-3H]glucose together with indirect calorimetry were used to investigate the partitioning of the supply of carbohydrates through the two branches of the pathway: from circulating glucose and from glycogen stores within the muscle cells to the mitochondria. The relative contribution of circulating glucose to total carbohydrate oxidation was small, accounting for only 13 % and 23 % of the carbohydrate oxidized at exercise intensities approaching in dogs and goats, respectively. Unexpectedly, maximal rates of circulating glucose oxidation were nearly the same in the two species (when expressed in absolute terms; dog:goat ratio = 1.2), despite the 2.2-fold difference in aerobic capacity. We conclude that the glycogen stores in the muscle cells are the major source of substrates at maximal rates of oxidation, supplying 60–70 % of the total energy. Furthermore, it is this branch of the carbohydrate pathway that is adapted to the large difference in aerobic capacity between dogs and goats.
Temporal Resolution in Olfaction: Stimulus Integration Time of Lobster Chemoreceptor Cells
Authors: Gomez George , Atema Jelle
Published: April 2021

The stimulus integration time of lobster olfactory receptor cells in situ was determined using extracellularly recorded spiking responses from receptor cells and on-line high-resolution measurement of odor square pulses. At a fixed odor concentration, odor steps of 200 ms duration elicited maximum responses; shorter odor steps did not drive the cells to their maximum response and longer odor steps added spikes but did not result in higher firing rates. Excitatory processes peaked within 220 ms of stimulus onset. At 160–300 ms, stimulus intensity discrimination was most evident. Adaptation processes reduced response magnitude to near-zero levels within 1000 ms of stimulus onset. Olfactory receptor cells thus resolve odor peak onsets within the first few hundred milliseconds: this time window corresponds to the 4–5 Hz frequency of olfactory sampling (i.e. ‘sniffing’) as well as the rapid fluctuations in odor concentration that are common in natural odor plumes. The stimulus integration time of 200 ms may play a role in the filtering of information used by lobsters to orient to distant odor sources.
Do Australian Desert Frogs Co-Accumulate Counteracting Solutes with Urea During Aestivation?
Authors: Withers Philip C. , Guppy Michael
Published: April 2021

Australian desert frogs of the genera Neobatrachus, Cyclorana and Heleioporus experience significant dehydration, and iono- and osmoconcentration, during aestivation in the laboratory and accumulate substantial amounts of urea (100–200 mmol l−1). We expected a priori that aestivating frogs probably would not need to accumulate balancing osmolytes but would accumulate trimethylamine oxide (TMAO) or betaine as counteracting solutes to urea. These aestivating frogs did not co-accumulate a substantial quantity of any particular balancing osmolyte or counteracting solute, such as a methylamine [TMAO, trimethylamine amine (TMA), betaine, sarcosine, glycerophosphorylcholine (GPC)] or polyol (inositol, mannitol, sorbitol) in plasma or muscle relative to urea accumulation. However, for aestivating frogs, the total concentration of all measured methylamines and polyols (TMAO + TMA + betaine + sarcosine + GPC + inositol) in muscle was approximately 35–45 mmol kg−1, and so it is possible that all of these solutes have a combined counteracting osmolyte role in aestivating frogs at a ratio to urea of approximately 1:2.5, as has been described for elasmobranch fishes. Alternatively, the absence of substantial co-accumulation with urea of any particular solute suggests that aestivating frogs might not require any major extracellular or intracellular counteracting solutes (TMAO, betaine, GPC). The enzyme systems of these aestivating frogs may be insensitive to the perturbing effects of urea, or the perturbing effects of accumulated urea may be a mechanism for metabolic depression, during aestivation.
The Modulus of Elasticity of Equine Hoof Wall: Implications for the Mechanical Function of the Hoof
Authors: Douglas J. E. , Mittal C. , Thomason J. J. , Jofriet J. C.
Published: April 2021

During normal weight-bearing and locomotion, the equine hoof wall deforms in a consistent pattern: the proximal dorsal wall rotates caudo-ventrally about the distal dorsal border and there is latero-medial flaring posteriorly. The aim of this study is to examine whether there are regional differences in the modulus of elasticity of hoof wall material and whether such differences correlate with the pattern of deformation which occurs in vivo.

The modulus of elasticity of equine hoof wall was determined in tension and compression for samples from six forefeet. Samples were tested at the mid-point of the inner and outer halves of the wall thickness at two positions along the proximo-distal axis of the dorsal wall, and from the mid-point of its thickness at the lateral and medial quarters. Test samples were oriented both parallel and perpendicular to the tubules that characterise the microstructure of the wall. The colour of each sample was noted, and the moisture content measured.

The range in the mean modulus of elasticity for all samples and tests was 460–1049 MPa, the dorsal outer wall having the highest values, the dorsal inner wall the lowest, and the quarters having intermediate values. The mean value obtained for the quarters was similar to the average of the values for the dorsal inner and outer walls. At all sites, the modulus of elasticity was marginally higher in compression than in tension, possibly owing to microstructural defects. The difference in stiffness between the outer wall and the inner wall was inversely related to moisture content.

The difference in stiffness between the dorsal outer and inner walls demonstrates that the equine hoof wall has a comparatively rigid external capsule with a lining of lower stiffness. This arrangement presumably provides some stress protection to the internally adjacent living tissues. The similarity in stiffness between the samples from the quarters and the mean of the two dorsal wall sites suggests that the wall at the quarters has a similar change in stiffness across its thickness as the dorsal wall. However, the reduced thickness of the wall at the quarters compared with the dorsal wall means that, functionally, the quarters are more flexible than the dorsal wall. This will facilitate the flaring of the lateral and medial walls which occurs during weight-bearing. Anisotropy was evident only in tensile tests of the dorsal wall samples. Contrary to popular assertions that white hooves are mechanically inferior, horn pigmentation had no detectable effect on stiffness.
A Preliminary Note on the Pollen Development of Lathyrus Odoratus
Authors: Latter Joan
Published: April 2021

In this paper the main points in the pollen development of Lathyrus odoratus are briefly described. At the beginning of the meiotic phase the reticulum contracts from the nuclear membrane and exhibits an entirely granular appearance. During thread formation, occasional amœboid nucleoli are observed. Nucleolar “budding” is also seen. Connecting strands are constantly found between the synizetic knot and the nucleolus. The thread at all stages appears usually to be a continuous structure. The synizetic knot is followed by a stage in which the thread is thrown into seven definite loops which radiate out from the centre of the nucleus. For this stage, which has frequently been called the second contraction stage in cytological literature, the name broxonema is proposed. The haploid number of chromosomes in Lathyrus odoratus is seven. Each loop represents one pair of homologous chromosomes joined distally end to end. The arms of each loop are twisted round one another at one period. This affords opportunity for exchange of segments of chromosomes, and gives a possible physical basis for crossing over in a telosynaptic form. These stages are followed by typical diakinesis and heterotypic divisions. During homotypic telophase evanescent cell plates occur between the daughter nuclei. Later, the cell walls are formed by furrowing. The tapetum remains uninucleate throughout.
Birds Without Gonads: Their Origin, Behaviour, and Bearing On the Theory of the Internal Secretion of the Testis
Authors: Riddle Oscar
Published: April 2021

Sixteen cases of pigeons without a discoverable trace of gonadal tissue have been found and described. Supplementary groups, one of fifteen birds in which one gonad only was abnormally absent, and still another of seventeen cases of nearly suppressed gonads, comprise the principal material obtained and examined.

It is practically certain that this absence of gonads was complete and persistent—not a temporary condition nor one attained shortly before examination of the birds.

Previous observations on the “no gonad” and “one gonad” condition in birds and in other animals are reviewed.

The basis of the gonadless condition is a purely developmental one, in which it is probable that physiological rather than cytological or genetic disturbance is chiefly concerned.

An attempt is made to identify the type of disturbance involved in this developmental anomaly. It is concluded that such failures of gonad development are a consequence of the failure of all “primordial germ cells” to reach or enter the anlage of the germinal ridge.

Some data are available for a test of this view ; they are found to be in conformity with it.

Despite the complete and persistent absence of testicular tissue, some of these birds developed complete and emphatic masculine behaviour ; some additional secondary sex characters observable in these forms were likewise developed to one or another degree.

Since such birds were, according to all the evidence, entirely without interstitial or spermatogenic tissues, it is clear that the thing which is normally accomplished with the aid of the testis incretion may also be accomplished without it. In such cases it is considered that the effective impulse in the determination of the individual’s sex, is capable of effecting the development of at least certain of these “secondary “sex characters. This material offered no opportunity to examine the effects of loss of gonad incretions on plumage characters.

These results, like those of other parts of our studies, lead to the view that the gonad incretions are “controlled” as well as controlling factors in sex development. That they, like the chromosomal or genetic sex factors, rest upon the more basic condition which we elsewhere identify as metabolic level or rate.
On Sex-Intergrade Pigs: Their Anatomy, Genetics, and Developmental Physiology
Authors: Baker John R.
Published: April 2021

Sex-intergrade pigs show all variations between complete and abortive development of the derivatives of the Müllerian and Wolffian ducts. The external genitalia are, however, always essentially female in type. The seminiferous tubules are degenerate even when the testes are descended. In the two true hermaphrodites described the ovary is on the left and the ovo-testis is on the right ; and in each case the ovarian part of the ovo-testis is anterior. It is not improbable that all sex-intergrades were true hermaphrodites in embryonic or early post-natal stages. A tendency to sexual abnormality in pigs is inherited. The ratio of normals to sex-intergrades among the offspring of intergrade - producing parents is 8: 1 or > 8: 1.

The abnormality does not appear to be associated with abnormality of any other ductless gland.

Sex-intergrades often have male sexual instincts.
Sex Differences in the Requirements of Certain Food Factors
Authors: Hartwell Gladys Annie
Published: April 2021

On certain diets quoted in this paper, the male rat grows at about the same rate as the female, and does not show the more rapid growth which is usually exhibited by the male of the species. Finally the male becomes distinctly the heavier, but his growth is slow during the first weeks of life. It is suggested that the growing male requires more vitamin B than the growing female, and also that he is more susceptible to the quality of the protein in the diet. The expenses of this research were defrayed by a grant from the Medical Research Council.
Some Protein Properties of Plant Protoplasm
Authors: Pearsall W. H. , Ewing James
Published: April 2021

In attempting to explain the reactions and behaviour of living organisms, the experimental biologist is often tempted to fall back on the causal consideration of the observed phenomena in terms of the single living cell. While it is true that our physiological knowledge of this unit is almost negligible, there is at any rate a widely accepted belief that its properties may often be expressed in terms of two of its most important chemically active substances, the various proteins and their derivatives or the fatty bodies. So far as proteins are concerned, this assumption is justified by the classical analyses of Reinke and Rodewald,12’ which show that in the plasmodium of Fuligo varians, about 60 per cent, of the dry weight of protoplasm is composed of protein. It is therefore legitimate to consider the hypothesis that certain properties of normal plant cells appear to be most simply expressed in terms of their protein reactions.
Studies on the Comparative Physiology of Digestion
Authors: Yonge C. M.
Published: April 2021

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

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

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

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

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

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

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

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

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

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

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.