bluuebunny/crossref_metadata_2025_split huggingface dataset:
Innate Preferences for Flower Features in the Hawkmoth Macroglossum Stellatarum
Authors: Kelber Almut 
Published: April 2021

ABSTRACT
The diurnal hawkmoth Macroglossum stellatarum is known to feed from a variety of flower species of almost all colours, forms and sizes. A newly eclosed imago, however, has to find its first flower by means of an innate flower template. This study investigates which visual flower features are represented in this template and their relative importance. Newly eclosed imagines were tested for their innate preferences, using artificial flowers made out of coloured paper or projected onto a screen through interference filters. The moths were found to have a strong preference for 440 nm and a weaker preference for 540 nm. The attractiveness of a colour increases with light intensity. The background colour, as well as the spectral composition of the ambient illumination, influences the choice behaviour. Blue paper disks against a yellowish background are chosen much more often than the same disks against a bluish background. Similarly, under ultraviolet-rich illumination, the preference for 540 nm is much more pronounced than under yellowish illumination. Disks of approximately 32 mm in diameter are preferred to smaller and larger ones, and a sectored pattern is more attractive than a ring pattern. Pattern preferences are less pronounced with coloured than with black-and-white patterns. Tests using combinations of two parameters reveal that size is more important than colour and that colour is more important than pattern.
Nervous Control of Male Sexual Drive in The Hermaphroditic Snail Lymnaea Stagnalis
Authors: De Boer P. A. C. M. , Jansen R. F. , Koene J. M. , Maat A. Ter 
Published: April 2021

ABSTRACT
We studied the role of the prostate gland in determining the level of male sexual drive in the hermaphroditic pond snail Lymnaea stagnalis. Male sexual drive is high after a period of social isolation and decreases after copulation as a male. A positive correlation exists between the level of male sexual drive and the volume of the prostate gland. Like male sexual drive, the volume of the prostate gland increases during a period of social isolation and decreases after copulation as a male. Behavioural experiments demonstrated that animals with a lesion of the nerve that innervates the prostate gland (NP1) have a lower level of male sexual drive after social isolation than control animals. However, lesion of NP1 did not affect the increase in the volume of the prostate gland caused by social isolation. Extracellular recordings from NP1 in a semi-intact preparation show a change in firing pattern during an experimentally induced increase in prostate gland volume. The results indicate that NP1 serves as a nervous pathway for the male sexual drive. We propose a simple motivational model for male sexual behaviour in L. stagnalis in which the volume of the prostate gland sets the level of male sexual drive.
Sodium/Proton Antiporter In The Euryhaline Crab Carcinus Maenas: Molecular Cloning, Expression And Tissue Distribution
Authors: Towle David W. , Rushton Mary E. , Heidysch Doris , Magnani Jason J. , Rose Melanie J. , Amstutz Alice , Jordan Mark K. , Shearer Darcy W. , Wu Wen-Shu 
Published: April 2021

ABSTRACT
Gill epithelial cells of euryhaline crustaceans demonstrate net inward transport of sodium ions, possibly via apical Na+/H+ antiporters, Na+/K+/2Cl− cotransporters or Na+ channels working in series with the basolateral Na++K+-ATPase. We have identified and sequenced the cDNA coding for a crustacean Na+/H+ antiporter, starting with mRNA isolated from gills of the euryhaline green shore crab Carcinus maenas. The complete 2595-base-pair cDNA includes an open reading frame coding for a 673-amino-acid protein. A search of GenBank revealed more than 20 high-scoring matches, all Na+/H+ antiporter sequences from mammalian, amphibian, teleost and nematode species. Injection of Xenopus laevis oocytes with cRNA transcribed from the cloned crab sequence substantially enhanced Na+-dependent H+ efflux from the oocytes. Analysis of crab tissue antiporter mRNA levels by semi-quantitative reverse transcription–polymerase chain reaction revealed that posterior and anterior gills of Carcinus maenas expressed this antiporter the most strongly, followed in decreasing order by skeletal muscle, hepatopancreas, hypodermis and heart. Hydropathy and transmembrane α-helix analysis suggested a 10-helix membrane-spanning topology of the antiporter protein. It is clear from this study that Carcinus maenas gills vigorously transcribe a gene coding for a Na+/H+ antiporter. Whether these gills also express a gene coding for an epithelial Na+ channel or Na+/K+/2Cl− cotransporter remains to be demonstrated.
Balancing Hypoxia and Hypothermia in Cold-Submerged Frogs
Authors: Tattersall G. J. , Boutilier R. G. 
Published: April 2021

ABSTRACT
Many animals respond to hypoxic stress by selecting cooler environments, the so-called ‘behavioural hypothermia’ response. Amphibians overwintering in ice-covered ponds and lakes offer an ecologically relevant test of this response since they must choose between the confounding metabolic effects of profound hypothermia or hypoxia; thermal and chemical conditions can vary from 0 °C and normoxic at the ice–water interface to 4 °C and markedly hypoxic at depths of 2–4 m. To mimic such environmental conditions, we constructed an experimental chamber that enabled continuous electronic surveillance of an animal’s movement along a thermal gradient. When Rana temporaria pre-acclimated to 3.5 °C were placed in a normoxic thermal gradient ranging from 0.8 to 8 °C, they invariably favoured the warmer end of the chamber. Upon exposure to hypoxia, however, their preferred temperature shifted from a median of 6.8 °C ( 1 mmHg=0.133 kPa) to 1.9 °C . Metabolic rate measurements from animals exposed simultaneously to acute changes in water temperature and suggest that movement to colder conditions in hypoxia effects the greatest metabolic savings and prolongs the onset of a plasma lactacidosis.
An Auditory Interneurone Tuned to the Male Song Frequency In The Duetting Bushcricket Ancistrura Nigrovittata (Orthoptera, Phaneropteridae)
Authors: Stumpner A. 
Published: April 2021

ABSTRACT
An auditory interneurone (AN1) of the bushcricket Ancistrura nigrovittata is described; it has a soma and dendrites in the prothoracic ganglion, an ascending axon and axon collaterals in the protocerebrum. As judged from morphological and physiological similarity, it is probably homologous to AN1 described in Tettigonia viridissima and to AN1 described in Gryllus bimaculatus. The occurrence and physiology of AN1 are not sex-specific. It receives predominant excitation between 12 and 16 kHz (male song frequency) and inhibition at lower frequencies and more strongly at higher frequencies. It shows optimum-type intensity/response curves. Frequency tuning and intensity-dependence compare well with female behaviour. Lesion experiments demonstrate that AN1 receives excitation and frequency-dependent inhibition from the soma-contralateral ear and inhibition from the soma-ipsilateral ear. The latter contributes to the clear left–right difference in its responses. AN1 does not obviously discriminate between temporal patterns of different behavioural effectivity. Its spiking, however, is coupled to the temporal pattern. It is hypothesized that AN1 may be involved in frequency processing by female A. nigrovittata.
The Changes in Power Requirements and Muscle Efficiency During Elevated Force Production in the Fruit Fly Drosophila Melanogaster
Authors: Lehmann Fritz-Olaf , Dickinson Michael H. 
Published: April 2021

ABSTRACT
The limits of flight performance have been estimated in tethered Drosophila melanogaster by modulating power requirements in a ‘virtual reality’ flight arena. At peak capacity, the flight muscles can sustain a mechanical power output of nearly 80 W kg−1 muscle mass at 24 °C, which is sufficient to generate forces of approximately 150 % of the animal’s weight. The increase in flight force above that required to support body weight is accompanied by a rise in wing velocity, brought about by an increase in stroke amplitude and a decrease in stroke frequency. Inertial costs, although greater than either profile or induced power, would be minimal with even modest amounts of elastic storage, and total mechanical power energy should be equivalent to aerodynamic power alone. Because of the large profile drag expected at low Reynolds numbers, the profile power was approximately twice the induced power at all levels of force generation. Thus, it is the cost of overcoming drag, and not the production of lift, that is the primary requirement for flight in Drosophila melanogaster. By comparing the estimated mechanical power output with respirometrically measured total power input, we determined that muscle efficiency rises with increasing force production to a maximum of 10 %. This change in efficiency may reflect either increased crossbridge activation or a favorable strain regime during the production of peak forces.
Variability of leg Kinematics in Free-Walking Crayfish, Procambarus Clarkii, and Related Inter-Joint Coordination
Authors: Jamon Marc , Clarac François 
Published: April 2021

ABSTRACT
The inter-joint coordination in leg 4 of the crayfish Procambarus clarkii was investigated while they travelled freely along straight paths. Video analysis of the kinematics of the leg’s three-dimensional motion, combined with a statistical method based on conjugate cross-correlation functions, showed stable inter-joint coordination in the leg kinematics. In particular, the inter-joint coordination involved a strong movement in the distal mero-carpopodite (M-C) joint occurring between the movements of the proximal thoraco-coxopodite and coxo-basal joints; thus, the leg extended during the swing phase and flexed during the stance phase. This synchronisation was mainly independent of global changes in the locomotor pattern induced by variation in speed or contralateral inter-leg coupling which occurred during free walking. The main changes in inter-joint coordination were found to be related to the appearance of a biphasic flexion/extension movement during each stroke of the step cycle when the leg retracted far backwards. This movement was observed more frequently in large animals and was therefore possibly related to changes in postural control. The functional role of this distal M-C joint movement in the leg motion is discussed.
Power Output From a Flight Muscle of the Bumblebee Bombus Terrestris: II. Characterization of the Parameters Affecting Power Output
Authors: Josephson Robert K. 
Published: April 2021

ABSTRACT
Length–tension relationships and work output were investigated in the intact, dorso-ventral flight muscle of the bumblebee Bombus terrestris. The muscle is an asynchronous muscle. Like other asynchronous flight muscles, it has high resting stiffness and produces relatively low active force in response to tetanic stimulation. The muscle shows shortening deactivation and stretch activation, properties that result in delayed force changes in response to step changes in length, a phase lag between force and length during imposed sinusoidal strain and, under appropriate conditions, positive work output during oscillatory length change. Work loops were used to quantify work output by the muscle during imposed sinusoidal oscillation. The curves relating net work per cycle with muscle length, oscillatory strain and oscillatory frequency were all roughly bell-shaped. The work–length curve was narrow. The optimum strain for net work per cycle was approximately 3 %, which is probably somewhat greater than the strain experienced by the muscle in an intact, flying bumblebee. The optimum frequency for net work output per cycle was 63 Hz (30 °C). The optimum frequency for power output was 73 Hz, which agrees well with the normal wing stroke frequency if allowance is made for the elevated temperature (approximately 40 °C) in the thorax of a flying bumblebee. The optimal strain for work output was not strongly dependent on oscillation frequency. Resilience (that is the work output during shortening/work input during lengthening) for unstimulated muscle and dynamic stiffness (=Δstress/Δstrain) for both stimulated and unstimulated muscles were determined using the strain (3 %) and oscillation frequency (64 Hz) which maximized work output in stimulated muscles. Unstimulated muscle is a good energy storage device. Its resilience increased with increasing muscle length (and increasing resting force) to reach values of over 90 %. The dynamic stiffness of both stimulated and unstimulated muscles increased with muscle length, but the increase was relatively greater in unstimulated muscle, and at long muscle lengths the stiffness of unstimulated muscle exceeded that of stimulated muscle. Effectively, dynamic stiffness is reduced by stimulation! This is taken as indicating that part of the stiffness in an unstimulated muscle reflects structures, possibly attached cross bridges, whose properties change upon stimulation.
Power Output From a Flight Muscle of the Bumblebee Bombus Terrestris :III. Power During Simulated Flight
Authors: Josephson Robert K. 
Published: April 2021

ABSTRACT
The work loop approach was used to measure mechanical power output from an asynchronous flight muscle, the dorso-ventral muscle of the bumblebee Bombus terrestris. Measurements were made at the optimum muscle length for work output at 30 °C and at a muscle temperature (40 °C) and oscillatory frequency (141–173 Hz, depending on the size of the animal) characteristic of free flight. Oscillatory strain amplitude was adjusted to maximize power output. There was much preparation-to-preparation variability in power output. Power output in the muscles with the highest values was slightly greater than 100W kg−1. It is argued that there are many experimental factors which might reduce measured power output below that in the living bumblebee, and no obvious factors which might lead to overestimates of muscle power. The conclusion is that flight muscle in the intact bumblebee can produce at least 100 W kg−1.
Mental Rotation in A California Sea Lion (Zalophus Californianus)
Authors: Mauck B. , Dehnhardt G. 
Published: April 2021

ABSTRACT
Mental rotation is a widely accepted concept that suggests an analogue mode of visual information-processing in certain visuospatial tasks. Typically, these tasks demand the discrimination between the image and mirror-image of rotated figures, for which human subjects need an increasing reaction time depending on the angular disparity between the rotated figures. In pigeons, tests of this kind yielded a time-independent rotational invariance, suggested as being the result of a non-analogue information-processing that has evolved in response to the horizontal plane that birds perceive from above while flying. Given that marine mammals use the water surface as the horizontal plane for orientation while diving, the ability of a California sea lion to mentally rotate two-dimensional shapes was tested. Using a successive two-alternative matching-to-sample procedure, the animal had to decide between the image and mirror-image of a previously shown sample. Both stimuli were rotated by a multiple of 30 ° with respect to the sample. The animal’s reaction time was measured by a computer-controlled touch-screen device, rewarding the animal for pressing its snout against the stimulus matching the sample. A linear regression analysis of the animal’s mean reaction time against the angular rotation of the stimulus yielded a significant correlation coefficient. Thus, the present data can be explained by the mental rotation model, predicting an image-like representation of visual stimuli in this species. The present results therefore correspond well with those found for human subjects, but are inconsistent with the data reported for pigeons.
Measurement of the Threshold Sensitivity of Honeybees to Weak, Extremely Low-Frequency Magnetic Fields
Authors: Kirschvink Joseph L. , Padmanabha S. , Boyce C. K. , Oglesby J. 
Published: April 2021

ABSTRACT
Experiments reported previously demonstrate that free-flying honeybees are able to detect static intensity fluctuations as weak as 26 nT against the background, earth-strength magnetic field. We report here an extension of this work to weak, alternating fields at frequencies of 10 and 60 Hz. Our results indicate that the sensitivity of the honeybee magnetoreception system decreases rapidly with increasing frequency. At 60 Hz, alternating field strengths above 100 μT are required to elicit discrimination. These results are consistent with biophysical predictions of a magnetite-based magnetoreceptor.
Predictions of the Time Course of Force and Power Output by Dogfish White Muscle Fibres During Brief Tetani
Authors: Curtin N. A. , Gardner-Medwin A. R. , Woledge R. C. 
Published: April 2021

ABSTRACT
The aim of this study was to identify the principal factors that determine the time course of force and power output by muscle during patterns of stimulation and movement similar to those during fish swimming. Fully activated, white muscle fibres isolated from dogfish Scyliorhinus canicula were used to characterize the force–velocity relationship of the contractile component (CC) and the stress–strain relationship of the passive, elastic component (SEC) in series with the CC. A simple model of the time course of crossbridge activation during brief contractions was devised. Using the mechanical properties of the CC and SEC and the activation time course, force and power were predicted for brief contractions with constant-velocity movement and also for brief contractions starting at various times during sinusoidal movement. The predicted force and power were compared with observations for these patterns of stimulation and movement. The predictions matched the observations well for the period during stimulation. Matching of force was much less good for some specific conditions during relaxation, the period during which force persists after the end of stimulation. If either the slow rise of activation or the SEC was omitted from the calculation, the predictions were poor, even during stimulation. Additional factors which may influence force are discussed. These include the after-effects of shortening and stretch, the variation of force during constant-velocity stretch and non-uniform behaviour within the muscle.
Collagen Orientation and Molecular Spacing During Creep and Stress-Relaxation in Soft Connective Tissues
Authors: Purslow Peter P. , Wess Tim J. , Hukins David W. L. 
Published: April 2021

ABSTRACT
Collagen fibres form cross-helical, cross-ply or quasi-random feltworks in extensible connective tissues; strain-induced reorientation of these networks gives rise to the non-linear mechanical properties of connective tissue at finite strains. Such tissues are also generally viscoelastic (i.e. display time-dependent properties). The hypothesis that time-dependent reorientation of collagen fibres is responsible for the viscoelasticity of such tissues is examined here using time-resolved X-ray diffraction measurements during stress-relaxation and creep transients applied to rat skin and bovine intramuscular connective tissue. Differences in the intensity and angular orientation of the third and fifth orders of the 67 nm meridional D-spacing of collagen molecules were shown before and after the application of loads or displacements. However, no changes in the D-spacing or angular orientation of collagen occurred during the time course of either stress-relaxation or creep in both tissues. This indicates that collagen fibre reorientation is not a primary source of their viscoelastic properties. The non-linear (strain-dependent) nature of the stress-relaxation response in these tissues suggests that relaxation processes within the collagen fibres or at the fibre–matrix interface may be responsible for their viscoelastic nature.
Representation of Behaviorally Relevant Sound Frequencies by Auditory Receptors in the Cricket Teleogryllus Oceanicus
Authors: Pollack Gerald S. , Faulkes Zen 
Published: April 2021

ABSTRACT
Teleogryllus oceanicus is particularly sensitive to two ranges of sound frequency, one corresponding to intraspecific acoustical signals (4–5 kHz) and the other to the echolocation cries of bats (25–50 kHz). We recorded summed responses of the auditory nerve to stimuli in these two ranges. Nerve responses consist of trains of compound action potentials (CAPs), each produced by the summed activity of a number of receptor neurons. The amplitude of the CAP is up to four times larger for stimuli at 4.5 kHz than for stimuli at 30 kHz, suggesting either that the extracellular spikes produced by receptors that respond to 4.5 kHz are larger than those that respond to 30 kHz, or that receptors fire more synchronously in response to stimulation at 4.5 kHz, or that more receptors respond to stimulation at 4.5 kHz. Neither unit spike amplitude nor conduction velocity (which is expected to vary with spike amplitude) differs for the two frequencies, and the responses to 4.5 kHz are not produced by more tightly synchronized receptor populations, as judged by CAP breadth. We conclude that more receptors respond to 4.5 kHz than to 30 kHz.
Intergeneric Distribution and Immunolocalization of a Putative Odorant-Binding Protein in True Bugs (Hemiptera, Heteroptera)
Authors: Dickens Joseph C. , Callahan Franklin E. , Wergin William P. , Murphy Charles A. , Vogt Richard G. 
Published: April 2021

ABSTRACT
Lygus antennal protein (LAP) is an olfactory-related protein of the tarnished plant bug Lygus lineolaris (Hemiptera, Heteroptera: Miridae), a hemimetabolous insect. In previous work, a polyclonal antiserum was generated against the N-terminal sequence of LAP; LAP immunoreactivity was strongest in antennae of adult males, but was also present in antennae of adult females and of nymphs. In the current study, LAP immunoreactivity was examined to determine the species specificity and the tissue and cellular localization of LAP expression. Western blot analysis indicated that LAP immunoreactivity was present in the antennae of the male congeners L. lineolaris and L. hesperous, but was not detectable in male antennae of the more distant relatives Podisus maculiventris or Nezara viridula (Hemiptera, Heteroptera: Pentatomidae). Western blot analysis further confirmed that LAP expression was restricted to antennal tissue. Histological analyses showed that LAP expression within the antennae was specifically associated with chemosensory sensilla on the antenna. Within the sensilla, LAP immunoreactivity was distributed throughout the extracellular lumen and was concentrated in dense granules within the cytoplasm of sensillar support cells. LAP immunoreactivity was restricted to a subset of antennal chemosensory sensilla, specifically the multiporous olfactory sensilla. These findings suggest that LAP has an important olfactory function in Lygus sp., possibly related to that of odorant-binding proteins (OBP) found in other insect orders. If so, LAP would be the first OBP-like protein characterized outside the Endopterygota.