bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transduction of mechanical energy into sound energy in the cicada Cyclochila australasiae
Authors: Bennet-Clark H. C. , Daws A. G. 
Published: April 2021

ABSTRACT
The anatomy of the paired tymbal muscles of Cyclochila australasiae was described. Force–distance relationships of the sound-producing in–out cycle of tymbal movement were measured. The largest forces were measured when the push occurred at the apodeme pit on the tymbal plate at angles similar to the angles of internal pull of the tymbal muscle. Initially, inward movement was opposed by the elasticity of the tymbal, which stored energy. At a mean force of 0.38 N after a mean inward strain of 368 μm, the tymbal ribs buckled, the mean energy release being 45.1 μJ. The energy release occurred over 2–10 ms in three or four sound-producing steps as successive tymbal ribs buckled inwards. After the ribs had buckled, the force decreased to a mean value of 0.17 N. The force returned to zero during the outward movement, during which the tymbal ribs buckled outwards. The mean energy dissipated in the outward movement was 32.8 μJ. During contraction, the tymbal muscle produced mean values for the peak active force of 0.31 N over 295 μm, which gave mean values for the area of the work loops of 47.0 μJ.
The calling song of C. australasiae had a mean pulse rate of 234 Hz (117 Hz for each side of the insect). The peak power to mean power ratio for the songs was 8.51:1 (+9.30 dB). Measurements of the sound field around tethered insects and of the peak power to mean power ratio of the songs gave values for the mean power of the song of 3.15–7 mW; these correspond to an energy per song pulse of 13.5–30 μJ. Previously reported mean values are 3.15 mW for protest song and 5.1 mW for calling song. The efficiency of transduction of mechanical energy into sound energy is between 18 and 46 %
Lipid accumulation in the ovaries of a marine shrimp Penaeus semisulcatus (de haan)
Authors: Ravid T. , Tietz A. , Khayat M. , Boehm E. , Michelis R. , Lubzens E. 
Published: April 2021

ABSTRACT
By the end of oocyte development, the ovaries of Penaeus semisulcatus have accumulated almost equal amounts (approximately 16 mg lipid g−1 protein) of phospholipids and triacylglycerols. The phospholipids consist mainly of phosphatidylcholine (75–80 %) and phosphatidylethanolamine (20–25 %). Approximately 30 % of the total fatty acid content of both phospholipids and triacylglycerols is made up of polyunsaturated fatty acids. In fractions obtained by centrifugation of ovarian homogenates, most of the increase in levels of ovarian lipids during ovarian maturation was associated with an increase in triacylglycerol levels in the floating fat fraction and of phospholipids in the infranatant fraction. The presence of polyunsaturated fatty acids in the ovaries indicates the occurrence of lipid transport to the ovary during oocyte maturation. The gradual decrease in the relative abundance of polyunsaturated fatty acids as the ovaries matured supports previously published results suggesting intra-ovarian synthesis of saturated and mono-unsaturated fatty acids.
Most of the lipids found in the female haemolymph (64.8 %) were recovered in the high-density lipoprotein fraction after density ultracentrifugation. The haemocyanin fraction recovered from this stage of fractionation contained substantial amounts of lipid (16.8 %) that could be removed by further sequential centrifugation at a higher NaBr density, leaving less than 0.9 % of the total haemolymph lipids associated with this fraction. While 16.2 % of the lipids were recovered from the very high-density lipoprotein fractions, these lipoproteins carried only 64–89 μg lipid mg−1 protein compared with 538.9 μg lipid mg−1 protein in the high-density lipoprotein fraction, indicating that the high-density lipoproteins are more likely to be the main transporters of lipids to the ovary. However, the contribution of very high-density lipoproteins to lipid transport cannot be ruled out at this stage.
In this study, we present two models for lipid transport to the ovary based on the abundance of phospholipids and triacylglycerols in the haemolymph and on the amounts of polyunsaturated fatty acids accumulated within the ovary during vitellogenesis.
Learning walks and landmark guidance in wood ants (Formica rufa)
Authors: Nicholson D. J. , Judd S. P. D. , Cartwright B. A. , Collett T. S. 
Published: April 2021

ABSTRACT
We have examined a behaviour pattern in wood ants which in some respects resembles and in other respects differs from the learning flights of bees and wasps. Wood ants returning to their nest from a newly discovered food source turn back and look at landmarks near to the feeder, but the feeder itself does not attract sustained fixations. The frequency of landmark inspections is highest when the ant is close to the feeder and falls as the ant moves away. In common with learning flights, inspections of landmarks on departure become less frequent as ants become familiar with their surroundings and reappear after a long interval without foraging. A principal difference between the learning flights of wasps and bees and this putative learning behaviour in ants is the emphasis that ants place on landmark fixation. Ants and honeybees move differently when searching for a goal within an array of transformed landmarks. We have explored, using computer simulation, whether this difference can be explained by the prominence ants give to the matching of landmarks viewed in the frontal visual field.
No evidence for olfactory blocking in honeybee classical conditioning
Authors: Gerber Bertram , Ullrich Juliane 
Published: April 2021

ABSTRACT
We use binary odorant compounds to investigate ‘blocking’ in honeybees which learn to associate an odorant (A–D) with a sucrose reward as the reinforcer (+). ‘Blocking’ means that learning about a stimulus B is reduced when trained in compound with a stimulus A that has previously been trained alone. Thus, reinforcement of B in these circumstances is not sufficient to induce learning. Such blocking is a frequently observed phenomenon in vertebrate learning and has also recently been reported in honeybee olfactory learning. To explain blocking, current models of conditioning include cognition-like concepts of attention or expectation which, consequently, seem also to apply to honeybees. Here, we first reproduce a blocking-like effect in an experimental design taken from the literature. We identify two confounding variables in that design and experimentally demonstrate their potential to support a blocking-like effect. After eliminating these confounding variables using a series of different training procedures, the blocking-like effect disappeared. Thus, convincing evidence for blocking in honeybee classical conditioning is at present lacking. This casts doubt on the applicability of cognition-like concepts to honeybees.
Tympanal hearing in the sarcophagid parasitoid fly Emblemasoma sp.: the biomechanics of directional hearing
Authors: Robert D. , Miles R. N. , Hoy R. R. 
Published: April 2021

ABSTRACT
In Diptera, tympanal hearing has evolved at least twice in flies that belong to two different families, the tachinids and the sarcophagids. Common to these flies is their parasitoid reproductive strategy, both relying on the acoustic detection and localization of their hosts, singing insects, by means of tympanal hearing organs. In the present study, the external anatomy of the unusual hearing organs of the sarcophagid fly Emblemasoma sp. is described. The sarcophagid ears bear numerous anatomical similarities with those of ormiine tachinids: they are located on the ventral prosternum and possess a pair of scolopidial mechanoreceptive sense organs. A striking difference, however, resides in the lack of a well-defined presternum in the sarcophagid tympanal system. Instead, a deep longitudinal fold, the tympanal fold, spans both hemilateral tympanal membranes across the midline of the animal. Measured using laser Doppler vibrometry, the tympanal mechanical response in the sound field reveals asymmetrical deflection shapes that differ from those of tachinids. Lacking a central fulcrum, the sarcophagid tympanal complex presents different vibrational modes that also result in interaural coupling. The evolutionarily convergent, yet distinct, solutions used by these two small auditory systems to extract directional cues from the sound field and the role of tympanal coupling in this process are discussed.
Ixodid ticks avoid contact with liquid water
Authors: Kröber T. , Guerin P. M. 
Published: April 2021

ABSTRACT
Larvae of the cattle tick Boophilus microplus and all life stages of the European sheep tick Ixodes ricinus avoid walking on a wet membrane surface surrounding a dry patch. Of 170 reactions made at a border with liquid water by 22 B. microplus larvae, 40 % consisted of immediate turns to the opposite side to bring all the legs back onto a dry patch, 41 % were walks along the border, during which the ticks maintained contact with both the dry and wet zones, and 19 % were returns to the dry patch after a short excursion onto the wet surround. Since contact with one front leg tip was sufficient to cause return reactions from the wet surface in most of the border contacts, the water receptor(s) that enable ticks to perceive the wet surface are probably located in terminal pore sensilla on the first-leg tarsi. Observations on the return reactions of ticks with different groups of chemosensilla masked confirmed this. Ticks have an ambiguous relationship with water: they appear to avoid direct contact with it, but they need a high humidity to compensate for any deficit in body water.
Functional complementation of the malvolio mutation in the taste pathway of Drosophila melanogaster by the human natural resistance-associated macrophage protein 1 (Nramp-1)
Authors: D’Souza Jasmine , Cheah Peh Yean , Gros P. , Chia W. , Rodrigues V. 
Published: April 2021

ABSTRACT
The malvolio (mvl) gene of Drosophila melanogaster encodes a protein with a high degree of homology to natural resistance-associated macrophage proteins (Nramps). This family of integral membrane proteins, many of which appear to function as cation transporters, is remarkably conserved in several phylogenetically distinct species. In Drosophila melanogaster, the protein Mvl is expressed in macrophages and in differentiated neurons; loss-of-function mutations lead to defects in gustatory behaviour. The human Nramp-1 protein was expressed in Drosophila melanogaster using the hsp70 promoter. Overexpression in normal animals does not lead to any alterations in their behaviour or physiology. In mutants, however, ubiquitous expression of human Nramp-1 can totally rescue the taste defect. This finding that Nramp-1 can complement the taste defect in mvl mutants provides a potent means of exploiting behavioural genetics to dissect the function of Nramp-1 and to identify other molecules involved with this transport system.
The photoreceptors and visual pigments in the retina of a boid snake, the ball python (Python regius)
Authors: Sillman A. J. , Carver J. K. , Loew E. R. 
Published: April 2021

ABSTRACT
The photoreceptors and visual pigments of Python regius were studied using microspectrophotometry and scanning electron microscopy. The retina contains rods and cones, with rods constituting at least 90 % of the photoreceptor population. The rods are of a single type with long, narrow outer segments and are tightly packed. The wavelength of maximum absorbance (λmax) of the visual pigment in the rods is in the region of 494 nm. Two distinct types of cone are present. The most common cone, with a stout but stubby outer segment, contains a visual pigment with λmax at approximately 551 nm. A relatively rare cone, with a long, slender outer segment, contains an ultraviolet-sensitive visual pigment with λmax at approximately 360 nm. All the visual pigments have chromophores based on vitamin A1. The results are discussed in relation to the behavior of P. regius.
Voltage-activated whole-cell K+ currents in lamina cells of the desert locust Schistocerca gregaria
Authors: Benkenstein Christian , Schmidt Manfred , Gewecke Michael 
Published: April 2021

ABSTRACT
Voltage-dependent outward currents were studied in freshly dissociated somata of locust lamina cells. These currents were recorded in 142 somata using the whole-cell patch-clamp technique. By measuring the reversal potential at altered external [K+] and by replacing internal K+ with Cs+, we determined that the outward currents were carried by K+. The outward currents consist of a transient A-type K+ current (KA) and a delayed-rectifier-like K+ current (KD). Amongst the cells studied, we observed two distinct groups of cells. The most obvious difference between the two groups is that in group I cells the total outward current is dominated by KA (KA/KD=12.5), whereas in group II cells KA makes a smaller contribution (KA/KD=2.1). Furthermore, in cells of group I, the KA current shows a steeper voltage-dependence of activation, where VG50 is −29.9 mV and s is 11.9 (N=22), and inactivation, where VI50 is −84.5 mV and s is −6.3 (N=18), compared with the KA current in cells of group II: VG50=−7.9 mV; s=26.6 (N=36) and VI50=−68.4 mV; s=−7.5 (N=21) (VG50 is the voltage at which the whole-cell conductance G is half-maximally activated, VI50 is the voltage of half-maximal inactivation and s is the slope of the voltage-dependence). The transient KA current in group I cells decayed mono-exponentially. The decay of the KA current in group II cells was fitted with a double-exponential curve and was significantly faster than in group I cells. In contrast to the large differences in KA currents, the KD currents appeared to be quite similar in the two groups of cells.
Chemolithoheterotrophy in a metazoan tissue: sulfide supports cellular work in ciliated mussel gills
Authors: Doeller Jeannette E. , Gaschen Brian K. , Parrino Vincent , Kraus David W. 
Published: April 2021

ABSTRACT
Hydrogen sulfide, a common constituent of marine intertidal sediments, is both a potent toxin of aerobic cellular respiration and an electron-rich molecule used by some prokaryotic organisms as a source of energy. In ciliated gills from Geukensia demissa, a marine mussel from sulfide-rich sediments, sulfide oxidation supports cellular work. Evidence for this comes from measurements of ciliary beat frequency (fCB) as a measure of ATP turnover rate, the rate of gill oxygen consumption as a measure of ATP production rate, and mitochondrial cytochrome redox state as an indicator of the path of electron flow. Results from experiments performed in the presence and absence of the mitochondrial complex III inhibitor antimycin A to limit endogenous carbon substrate oxidation showed that exposure to sulfide stimulated oxygen consumption and ciliary beating, with cytochrome c being the dominant redu ced species. These results, along with the resultant ratio, are qualitatively and quantitatively consistent with the hypothesis that electrons from sulfide oxidation support mitochondrial ATP production. We propose that Geukensia demissa gills use sulfide as a respiratory substrate when given the choice and thus function metabolically as facultative chemolithoheterotrophs. Similar conclusions could not be drawn for the ciliated gills from Mytilus edulis, a marine mussel from aerated habitats, or for the ciliated lungs from the phylogenetically distinct leopard frog Rana pipiens.
Haemoglobin H+ equilibria in lamprey (Lampetra fluviatilis) and hagfish (Myxine glutinosa)
Authors: Jensen Frank B. 
Published: April 2021

ABSTRACT
Agnathans, comprising lamprey and hagfish species, have been reported to be practically devoid of HCO3−/Cl− exchange across the red blood cell membrane. This suggests that the capacity of their haemoglobin (Hb) to remove H+ is essential for obtaining a high CO2-carrying capacity in the blood. Hydrogen ion titrations were performed on oxygenated and deoxygenated composite Hbs from river lamprey and from Atlantic hagfish at 15 °C and an ionic strength of 0.1 (0.1 mol l−1 KCl). Lamprey Hb was characterised by very low buffer values when the degree of oxygenation was constant, whereas the fixed-acid Haldane effect was large (uptake of approximately 0.9 H+ per monomer upon deoxygenation). Hagfish Hb, in contrast, had large buffer values and a moderate fixed-acid Haldane effect. In deoxygenated Hb, the low buffer values in lamprey correlated with the presence of only 1–1.5 titratable ‘neutral’ groups (normally histidines and α-amino groups) per monomer, whereas there were 4–5 titratable ‘neutral’ groups per monomer in hagfish. The large differences in Hb/H+ equilibria between the two species reflect the early evolutionary divergence between lampreys and hagfish. With respect to CO2 transport, the special Hb/H+ equilibria and the high red blood cell pH in lamprey ensure a high concentration of free HCO3− inside the red cells in venous blood, which compensates for the absence of a shift of HCO3− to the plasma. The Hb/H+ equilibria in hagfish are less effective in ensuring a high CO2-carrying capacity given the virtual absence of a red blood cell HCO3−/Cl− exchange, and other adaptations may be involved.
Flight performance during hunting excursions in Eleonora’s falcon Falco eleonorae
Authors: Hedenström Anders , Rosén Mikael , Åkesson Susanne , Spina Fernando 
Published: April 2021

ABSTRACT
Among birds, falcons are high-performance flyers, in many cases adapted for aerial hunting and hence suitable targets for investigating limits to flight performance. Using an optical range finder, we measured flight tracks of Eleonora’s falcon (Falco eleonorae), a species breeding in the Mediterranean region and specialised for hunting autumn passage bird migrants, when commuting between their nesting colony and offshore hunting areas (straight transportation flight) and when searching for prey (transecting and searching flight). Airspeed during searching flight was significantly slower than during straight transportation and transecting flight, but there was no significant difference in airspeed between the latter two flight modes. Straight transportation flight was significantly faster than predicted minimum power speed. Also, during straight transportation flight, the falcons responded to head- and tailwinds by increasing their airspeed when flying into the wind. However, they did not show any significant airspeed adjustments with respect to the angle between the track and the heading, as would be expected in birds trying to maintain a constant track direction. Mean sustainable climb rate (during ≥:240 s) was 1.4±0.31 m s−1 (mean ± S.D., N=13), which is rather a high rate for a bird the size of an Eleonora’s falcon. The climb rate was used to calculate maximum load-carrying capacity and maximum sustained horizontal flapping flight speed. The mean wingbeat frequency during powered climbing flight was 4.68 Hz, which was used to estimate the mass-specific muscle work.
When falcons were leaving the colony for offshore hunting, they gained altitude by slope-soaring when there was an onshore wind. We formulated a simple criterion for the required gliding-flight rate of climb during an initial slope-soaring episode when minimizing the energy cost of reaching a certain altitude far out over the sea (which is where the prey is to be found). This climb rate was 0.36 m s−1, and our observations indicated that the falcons experienced climb rates above this value when soaring in slope-lift.
Neuronal control of catecholamine secretion from chromaffin cells in the rainbow trout (Oncorhynchus mykiss)
Authors: Montpetit Colin J. , Perry Steve F. 
Published: April 2021

ABSTRACT
The goal of the present investigation was to assess the relative involvement of nicotinic and muscarinic cholinergic receptors in the neuronal control of catecholamine secretion from the chromaffin tissue of rainbow trout (Oncorhynchus mykiss). This was accomplished by first developing and validating a nerve-stimulating technique able specifically to activate the nerve fibres innervating the chromaffin cells in order to elicit secretion of catecholamines. Using an in situ saline-perfused posterior cardinal vein preparation, it was demonstrated that whole-body field stimulation caused specific voltage-dependent neuronal stimulation of adrenaline and noradrenaline secretion. The contribution of non-specific depolarization was negligible. Several experimental results confirmed the specificity of the field stimulation technique. First, pre-treatment with neostigmine (an anticholinesterase) prolonged and more than doubled the amount of adrenaline secreted in response to electrical stimulation. Second, pre-treatment with the nicotinic receptor antagonist hexamethonium inhibited the electrically evoked secretion of adrenaline and noradrenaline. Third, perfusion with Na+-free saline or removal of the spinal cord abolished secretion of both catecholamines in response to the electrical stimulus. By using the field stimulation technique, this study is the first to demonstrate conclusively a role for muscarinic receptors in catecholamine secretion from trout chromaffin cells. Specifically, muscarinic cholinergic stimulation enhances nicotinic-evoked secretion of catecholamines and, under intense stimulation, may directly cause secretion. The results of the present study suggest the presence of muscarinic receptors on rainbow trout chromaffin cells with a functional role in the cholinergic control of catecholamine secretion.
Effects of size, motility and paralysation time of prey on the quantity of venom injected by the hunting spider Cupiennius salei
Authors: Malli Heinz , Kuhn-Nentwig Lucia , Imboden Hans , Nentwig Wolfgang 
Published: April 2021

ABSTRACT
Previous experimental studies have shown that neotropical wandering spiders (Cupiennius salei) inject more venom when attacking larger crickets. It has been postulated that this is a consequence of predator–prey interactions during envenomation, which increase in intensity with the size of a given prey species. The present study was designed to test this hypothesis using anaesthetized crickets of different sizes that were moved artificially. Cupiennius salei was found (1) to inject more venom the greater the intensity of the struggling movement of the crickets (prey size kept constant); (2) to inject more venom the longer the duration of the struggling movement of the crickets (prey size and intensity of movement kept constant); and (3) to inject equal amounts into crickets of different size (duration and intensity of movement kept constant). These results indicate that C. salei alters the amount of venom it releases according to the size and motility of its prey. Venom expenditure depends mainly on the extent of the interactions with the prey during the envenomation process, whereas prey size is of minor significance. The regulation of venom injection in concert with behavioural adaptations in response to various types of prey minimizes the energetic cost of venom production, thus increasing the profitability of a given prey item.