bluuebunny/crossref_metadata_2025_split huggingface dataset:
Honeybee Waggle Dance: Recruitment Success Depends on the Dance Floor
Authors: Tautz Juergen 
Published: April 2021

ABSTRACT
The waggle dance of the honeybee Apis mellifera, used to recruit nestmates to a food source, takes place on the surface of the combs in the dark hive. The mechanism of information transfer between dancer and follower bees is not entirely understood.
The results presented here reveal a novel factor that must be brought into any consideration of this mechanism, namely that the nature of the floor on which the bees dance has a considerable influence on the recruitment of nestmates to a food source. Dancers on combs with open empty cells recruit three times as many nestmates to a food source as dancers on capped brood cells.
Membrane Energization by Proton Pumps is Important for Compartmentalization of Drugs and Toxins: a New Type of Active Transport
Authors: Moriyama Yoshinori 
Published: April 2021

ABSTRACT
Many organelles are energized by proton pumps: mitochondria form an inside-negative membrane potential by means of the respiratory chain and endomembrane structures, such as lysosomes and synaptic vesicles, establish an internal acidic pH by means of a vacuolar-type H+-ATPase (V-ATPase). Various amphipathic drugs such as local anesthetics and neuron blockers are accumulated in acidic organelles upon energization by proton pumps. However, this process does not require any transporters specific for the drugs: these drugs penetrate through the lipid bilayer against a concentration gradient so as to accumulate inside the energized organelles. Essentially the same transport process takes place in liposomes that have been reconstituted with purified V-or F-ATPase. Various hydrophobic cations are also accumulated in mitochondria by a similar mechanism. The energy-dependent but transporter-independent accumulation does not belong to the known transport categories and seems to represent a new type of transport which may be important for understanding the mode of action of drugs and toxins.
Function of the Intercostal Muscles in Trotting Dogs: Ventilation or Locomotion?
Authors: Carrier David R. 
Published: April 2021

ABSTRACT
Although the intercostal muscles play an important role in lung ventilation, observations from fishes and ectothermic tetrapods suggest that their primary function may be locomotion. To provide a broader understanding of the role these muscles play in locomotion, I measured ventilatory airflow at the mouth and activity of the fourth and ninth intercostal muscles in four dogs trotting on a treadmill. During rest and thermoregulatory panting, activity of the intercostal muscles was associated with inspiratory and expiratory airflow. However, during trotting, activity of the interosseous portions of the intercostal muscles was correlated with locomotion. When ventilation and stride cycles were not synchronized, activity of the interosseous intercostal muscles stayed locked to the locomotor events and drifted in time relative to ventilation. In contrast, activity of the parasternal portion of the internal intercostal muscles was always associated with inspiratory airflow. These observations suggest that, in dogs, locomotion is the dominant function of the interosseous portions of the intercostal muscles. However, the parasternal intercostal muscles are primarily inspiratory in function.
Oxidative Stress and Antioxidants in Overwintering Larvae of Cold-Hardy Goldenrod Gall Insects
Authors: Joanisse Denis R. , Storey Kenneth B. 
Published: April 2021

ABSTRACT
Antioxidant and pro-oxidant systems were studied in overwintering larvae of two cold-hardy gall insect species, the freeze-tolerant fly Eurosta solidaginis and the freeze-avoiding moth Epiblema scudderiana. An increase in the levels of the oxidized form of glutathione suggested slight oxidative stress in both species during the winter. Freeze-tolerant Eurosta solidaginis larvae generally had decreased activities of antioxidant enzymes in the winter, indicating that these larvae do not face increased challenge from oxidative stress during the numerous freeze–thaw events they experience. Instead, existing defences must be sufficient to prevent any damage. By contrast, increased winter activities of antioxidant enzymes in freeze-avoiding Epiblema scudderiana suggest that these larvae must defend against the formation of reactive oxygen species. This may result from the oxidative nature of winter metabolism in these larvae, as well as a dependence on lipid oxidation as their fuel over this season. Xanthine dehydrogenase activity decreased dramatically in both species during the autumn, reducing the potential for the formation of the pro-oxidant xanthine oxidase. Indeed, xanthine oxidase activity fell to undetectable levels by winter in Epiblema scudderiana and was not detectable at any time in Eurosta solidaginis.
Measurement of Crustacean Hyperglycaemic Hormone Levels in the Edible Crab Cancer Pagurus During Emersion Stress
Authors: Webster S. G. 
Published: April 2021

ABSTRACT
The effects of emersion stress upon circulating hyperglycaemic hormone (CHH) levels in the edible crab Cancer pagurus were investigated using a highly specific and sensitive radioimmunoassay, with an antiserum directed against HPLC-purified C. pagurus CHH. Emersion resulted in hyperglycaemia and immediate hypoxia, as shown by rapid hyperlactaemia. CHH levels increased dramatically during the first hour of emersion, from almost undetectable levels to around 17 pmol l−1, thereafter increasing to around 30 pmol l−1 after 4 h of emersion. Short-term air exposure experiments demonstrated that significant increases in CHH levels (up to 3.5 pmol l−1) could be detected during the first 15 min of emersion. Although CHH appears to be fairly stable in haemolymph in vitro, injected CHH was cleared extremely rapidly from the haemolymph in vivo. The results suggest that emersion results in rapid, massive and prolonged exocytosis of CHH from the sinus gland. The sensitivity of the assay and the utility of this crab model may be useful in further studies to elucidate the control of CHH release in crustaceans.
Salinity Change and Cell Volume: the Response of Tissues from the Estuarine Mussel Geukensia Demissa
Authors: Neufeld Douglas S. , Wright Stephen H. 
Published: April 2021

ABSTRACT
The response of cell volume to changes in external salinity was assessed in four tissues (gill, mantle, hemolymph cells and ventricle) of the estuarine mussel Geukensia demissa by using one or more of the following three indicators of cell volume response: changes in cell dimensions, cell water space and cell solute content. All three techniques indicated that short-term volume regulation was generally absent from gill tissue. Lateral cell height in gills, measured using differential interference contrast (DIC) microscopy, increased by approximately 20 % after an abrupt exposure to reduced salinity (60 % artificial sea water, ASW). There was significant variability in the observance of a regulatory volume decrease (RVD) subsequent to the initial swelling; cells remained swollen for 1 h after low-salinity exposure in two-thirds of the trials, while there was a return of cell volume towards control values in the remaining one-third of the trials. Lateral cell height increased linearly when salinity was gradually decreased from 100 to 60 % ASW over 135 min. Cell height then returned to control values when the salinity was abruptly returned to 100 % ASW, indicating that an RVD was not elicited by a slow change in salinity of the type normally encountered by estuarine mussels. Cumulative cell water space in gills increased by 47 % after exposure to 60 % ASW and the cells remained swollen for at least 4 h, returning to control values when gills were returned to 100 % ASW. Consistent with the overall lack of an RVD, there was only a small decrease (approximately 5 %) in cumulative osmolyte content (primarily taurine, betaine and K+) after 4 h in 60 % ASW. Decreases in both cell water space and osmolyte content after 3 weeks of acclimation to 60 % ASW indicated a long-term RVD of approximately 60 %.
Individual cells in the mantle epithelium also generally lacked an RVD in response to lowered salinity. Both abrupt and gradual decreases in salinity caused an increase in mantle cell height to a maximum of 25–30 %, and cell height returned to the control height when salinity was abruptly returned to 100 % ASW. Corresponding with the lack of an RVD in individual mantle cells, there was no change in solute content of the mantle tissue after 4 h of exposure to low salinity. The response of the volume of spherical hemolymph cells to 1 h of abrupt exposure to low salinity, calculated from measured cell diameters, likewise indicated that an RVD is generally lacking in these hemolymph cells. In the ventricle, however, there was a significant decrease in amino acid and betaine content after 4 h of exposure to low salinity, suggesting tissue-specific variability in the cellular response to salinity change.
The consistent lack of a short-term RVD in many tissues may serve to avoid large energetic expenditures associated with repeated volume regulation in the face of the frequent, short-term changes in salinity encountered by estuarine mussels.
Design of the Oxygen and Substrate Pathways: I. Model and Strategy to Test Symmorphosis in a Network Structure
Authors: Taylor C. Richard , Weibel Ewald R. , Weber Jean-Michel , Vock Ruth , Hoppeler Hans , Roberts Thomas J. , Brichon Gérard 
Published: April 2021

ABSTRACT
This first paper in a series develops a model of structure–function relationships for the oxygen and substrate pathways of oxidative metabolism in working muscle. This will be used in the subsequent experimental papers in asking how biological structures are designed if they serve more than one function and whether one function can be served by more than one structural pathway. We have used the concept of symmorphosis to address this question; in its original form, it postulates that no more structure is built and maintained at each step in a pathway than is required to meet functional demands. The concept of symmorphosis was developed to deal with the problem of modelling the pathway for oxygen from the environment to mitochondria, essentially a single series of interconnected transfer steps. In the present context, the application of this concept is more complex. Both oxygen and substrates are transported directly from the blood to the mitochondria in what appear to be shared steps. The flows along this direct pathway are adjusted during muscular work. However, substrates have an additional option. They can be stored intracellularly as lipid droplets or glycogen, and thus their supply to mitochondria can occur in two steps separated in time: from capillaries to stores during rest, and from stores to mitochondria during work. The integrated pathways have a network structure and the functional flows are partitioned to different branches of the network, and we must ask whether the partitioning of fluxes is related to design constraints. The principle of symmorphosis predicts that the best use is made of the available options and that the design of each step is matched to the specific functional demand in view of a balance to be achieved over the entire network. This will be tested in subsequent papers by determining maximal flows for oxygen, carbohydrates and lipids through each of the transport steps and their respective structural capacities, comparing dogs and goats, animals of the same size whose maximal oxidative capacities differ by more than twofold. Finally, we will ask whether the principle of symmorphosis can be extended to apply to network systems.
Design of the Oxygen and Substrate Pathways: V. Structural Basis of Vascular Substrate Supply to Muscle Cells
Authors: Vock Ruth , Weibel Ewald R. , Hoppeler Hans , Ordway George , Weber Jean-Michel , Taylor C. Richard 
Published: April 2021

ABSTRACT
This paper quantifies the structural capacity of the transport steps for oxygen, glucose and fatty acids from the blood in capillaries to the cytosol of muscle cells and compares it with maximal rates of oxygen and substrate transport measured in the same animals and reported in the preceding papers of this series. Dogs have relatively more muscle per unit body mass than goats (37 versus 26 %), but the maximal rate of oxidation per gram of muscle is still larger in the dog by a factor of 1.55. The maximal rates of substrate supply from the circulation are similar in both species. We predict that these differences in physiological parameters should be matched by proportional differences in structural capacity. We find that capillary volume and surface area are matched to maximal oxygen demand. The rate of vascular substrate supply is proportional neither to the capillary surface area nor to the length of intercellular junctions. The sarcolemmal surface area per gram of muscle is the same in both species. Using the physiological data presented in the companion papers of this series, we have calculated the maximal flux densities of circulatory glucose and fatty acids across the capillary wall and the sarcolemma. We find, for both substrates, that the flux densities across the sarcolemma reach a maximum at nearly the same level and at low exercise intensities in both species. In contrast, the flux densities across the capillary surface and the endothelial junctions are higher in goats than in dogs. We conclude that the capillaries are designed for O2 supply up to maximal rates of oxidation but not for the supply of the substrates (glucose and fatty acids) at the rates required at high exercise intensities. These are limited by the transport capacities of the sarcolemma.
Optomotor Control of Course and Altitude in Drosophila Melanogaster is Correlated With Distinct Activities of at Least Three Pairs of Flight Steering Muscles
Authors: Heide Gerhard , Götz Karl G. 
Published: April 2021

ABSTRACT
Flight control in the fruitfly Drosophila melanogaster is achieved by minute sets of muscles on either side of the thorax. Control responses of wings and muscles were elicited during fixed flight by moving a striped pattern in front of the eyes. For example, pattern motion from the lower right to the upper left signals to the test fly a rotatory course deviation to the right and simultaneously a translatory altitude displacement downwards. The counteracting response to the displacement of the retinal image is an increase in thrust and lift on the right, accomplished mainly by increasing the wingbeat amplitude (WBA) on that side. A comparison of such responses with the simultaneously recorded action potentials in the prominent basalar muscles M.b1 and M.b2 and axillary muscles M.I1 and M.III1 on either side suggests that three of these muscles act on the WBA more or less independently and contribute to the optomotor control of course and altitude.
During flight, M.b1 is almost continuously active with a frequency equal to or slightly below 1 spike per wingbeat cycle. The spikes occur within a narrow phase interval of this cycle, normally at the beginning of the transition from upstroke to downstroke. However, the visual stimulus described above causes a substantial phase lead in M.b1 on the right; the spikes occur shortly before the end of the upstroke. Such phase shifts are accompanied by comparatively smooth ‘tonic’ responses of the WBA. The activities of M.b2 and M.I1 are normally very low. However, the stimulus described above activates M.b2 on the right in a phase interval approximately two-thirds into the upstroke and M.I1 on the left in a phase interval at the beginning of the downstroke. The spikes tend to occur in bursts. These bursts are correlated with WBA-increasing ‘hitches’ (rapid changes in amplitude) on the right and WBA-decreasing hitches on the left. As fast ‘phasic’ responses, the burst-induced hitches are likely to account for the course-controlling ‘body saccades’ observed during free flight. For unknown reasons, M.I1 is activated by pattern motion but cannot conceivably assist the other muscles in altitude control. Unlike its homologues in larger flies (Musca domestica, Calliphora erythrocephala), M.III1 does not participate in optomotor flight control. Its activation seems to support the termination of flight and wing retraction at rest.
The essential properties of the three pairs of muscles M.b1, M.b2 and M.I1 resemble those found in larger flies; the muscles are controlled by motion detectors with muscle-specific ‘preferred directions’ in the hexagonal array of retinal elements. Optomotor control of the three pairs of muscles in Drosophila melanogaster could explain most, but not all, of the WBA responses recorded so far.
Extracellular Ca2+ and its Effect on Acid Extrusion in the Crayfish Stretch Receptor Neurone
Authors: Moser H. , Mair N. , Fresser F. 
Published: April 2021

ABSTRACT
In the stretch receptor neurones of the crayfish Astacus astacus, the intracellular pH (pHi), the intracellular Na+ concentration ([Na+]i) and the membrane potential (Em) were measured simultaneously using ion-selective and conventional microelectrodes. Normal Astacus saline (NAS), and salines containing varying amounts of Ca2+ (Ca2+-NAS) but of constant ionic strength, with Na+, Mg2+ or Ba2+ as substituting ions, were used to investigate the effects of extracellular Ca2+ concentration ([Ca2+]o) on pHi and pHi regulation, on [Na+]i and on Em. The maximum rate of pHi recovery was used as a measure of pHi regulation. Acid loads were imposed using the NH4+/NH3 rebound technique. [Ca2+]o affected pHi, pHi regulation, [Na+]i and Em. The magnitudes of the effects were inversely related to [Ca2+]o and were specific to the ion used for [Ca2+]o substitution. Compared with controls, increasing [Ca2+]o threefold (in exchange for Na+) elicited some alkalization, a 7 % faster maximum rate of pHi recovery and generally lower values of [Na+]i. In low-Ca2+ or Ca2+-free NAS (substitutions by Na+ or Mg2+), pHi became more acid, the maximum rate of pHi recovery was reduced by up to 50 % and [Na+]i was generally higher. The effects were faster and larger at lower [Ca2+]o, and stronger with Na+ than with Mg2+ as the substituting ion. In Ca2+-free NAS (Ca2+ substituted for by Ba2+), the effects on pHi, on the maximum rate of pHi recovery and on [Na+]i were generally small. In this respect, Ba2+ had similar physiological properties to Ca2+ and was almost equally effective. Changes in Em, including rapid depolarizations and occasional burst activity in Ca2+-free NAS, indicate that alterations in the properties of the membrane, such as a change in its permeability or selectivity, are occurring. Measurements of [Na+]i support this view. In addition, Ba2+per se induced a (small) depolarization, as shown when Ba2+ was present in NAS or in low-Ca2+ NAS. Changes in [Ca2+]o affected [Na+]i. *[Na+]i is defined as [Na+]i determined at the onset of the maximum rate of pHi recovery, and the ratio *[Na+]i/[Na+]o at that instant was calculated. A linear relationship between the maximum rate of pHi recovery and the *[Na+]i/[Na+]o ratio was found, irrespective of the amount and of the ion species used for [Ca2+]o substitution. This is strong evidence that pHi and pHi regulation were indirectly affected by [Ca2+]o, which altered membrane properties and thus caused a change in [Na+]i. We could find no evidence for a direct contribution of [Ca2+]o to acid extrusion or to a direct modulatory action on the transport protein of the Na+/H+ antiporter.
Periodic Fluctuations in the Numbers of Animals: Their Causes and Effects
Authors: Elton C. S. 
Published: April 2021

ABSTRACT
Four main points are dealt with :— (a) The widespread existence of fluctuations in the numbers of animals. (b) The existence, in many birds and mammals, of periodic fluctuations (p.f.). (c) The cause of the latter, which must be some periodic climatic change acting over wide areas. (d) The effects of fluctuations in general, and in particular of the p.f., on the method of evolution and other biological phenomena. A short sketch is given of what is known about short-period climatic cycles (2 to 20 years), and their causes. P.f. of lemmings have an average period of about 312 years. The maxima in numbers occur synchronously in North America and Europe, and probably all round the arctic regions. The varying hare in Canada has a period of 10 to 11 years. The only regular periods shown by the animals dealt with are the short one of 312 years and the longer one of 10 to 11 years. The former is probably more marked in the arctic and the other further south. The sandgrouse p.f. point to the existence of an 11-year climatic cycle in the deserts of Central Asia. The effects of these p.f. on evolution must be very great, although at present problematical; but the following suggestions are made :— (a) Natural selection of some characters must be periodic. (b) There will be different .types of natural selection at the maxima and minima of numbers. (c) The struggle for existence, and therefore natural selection, tend to cease temporarily during the rapid expansion in numbers from a minimum, and new mutations have then a chance to get established and spread, i.e. without the aid of natural selection. This might happen only rarely. (d) This would explain the origin and survival of non-adaptive characters in a species. (e) On the other hand periodic reduction in numbers will act as an important factor causing uniformity in the species. (f) The opposing factors (c) and (e) will vary much in different species, and the problem will require the combined attentions of mathematicians, and of ecologists working on the methods of regulation of the numbers of animals. (g) This mechanical uniformity factor, since it acts independently of natural selection, explains how a particular structure or habit may evolve, when it only has a general adaptive significance.
A pH Method for Determining the Carbon Dioxide Exchanges of Marine, Brackish - Water, and Freshwater Organisms
Authors: Bruce John Ronald 
Published: April 2021

ABSTRACT
The pH method of determining carbon dioxide exchange has hitherto been available only for freshwater and marine organisms, the necessary determinations of the relation between pH, excess base and CO2-content having been made, in the one case by Prideaux, and in the other by M’Clendon and co-workers.
In order to extend the method to the study of organisms inhabiting brackish waters, of excess base content between that of fresh water and sea water, the determinations of Buch have been utilised, and have been recalculated to a common basis with the foregoing.
The combined results have been plotted as a series of regular curves, which should be of value in comparative metabolic studies of littoral and estuarine forms.
A Minute-Like III-Chromosome Recessive in Drosophila Melanogaster
Authors: Mohr Otto L. 
Published: April 2021

ABSTRACT
Among the numerous cases of mutant changes with multiple effects the so-called “Minutes” discovered by Bridges form an interesting group. In 1919 Bridges discovered the first mutant of this type, the Ill-chromosome dominant mutant Minute, the most obvious characteristic of which is “that all the bristles of the fly, especially those on the thorax, the scutellum and the head, are much more slender and considerably shorter than normal” (Bridges and Morgan, 1923). In most Minute flies the minuteness of the bristles is the only departure from normal that is readily seen. But there is also a tendency for the flies to be paler in general colour, to show a dark trident pattern, to be smaller in size, and to have blunter and dull-coloured wings. This aggregate of somatic peculiarities is accompanied by the following fundamental characteristics : considerably delayed hatching, frequent female sterility, and lowered viability.