bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Kinematics and Mechanism of Prey Capture in the African Pig-Nosed Frog (Hemisus Marmoratum): Description of a Radically Divergent Anuran Tongue
Authors: Ritter Dale , Nishikawa Kiisa 
Published: April 2021

ABSTRACT
High-speed videography and muscle denervation experiments were used to quantify the feeding kinematics of Hemisus marmoratum and to test hypotheses of muscle function. The feeding behavior of H. marmoratum, which feeds on ants and termites, differs radically from that of other frogs that have been studied. During feeding in H. marmoratum, the tongue ‘telescopes’ straight out of the mouth, as opposed to the ‘flipping’ tongue trajectory observed in most other frogs. At the time of prey contact, two lateral lobes of tissue at the tongue tip envelop the prey. These lateral lobes are capable of applying significant pulling forces to the prey and the tongue is, therefore, described as prehensile. The trajectory of the tongue can be adjusted throughout protraction so that the frog can ‘aim’ its tongue in all three dimensions; distance, azimuth and elevation. Bilateral denervation of the genioglossus muscles results in a complete lack of tongue protraction, indicating that the genioglossus muscle is the main tongue protractor in H. marmoratum, as in other frogs. Thus, H. marmoratum provides strong evidence of functional conservatism of the genioglossus muscle within anurans. Bilateral denervation of the hyoglossus muscle indicates that although the hyoglossus is involved in several aspects of normal tongue retraction, including the prehensile capability of the tongue tip, it is not necessary for tongue retraction. Unilateral denervation of the genioglossus muscle causes significant deviation of the tongue towards the denervated side, providing evidence for a mechanism of lateral tongue aiming. On the basis of the kinematics of prey capture, the anatomy of the tongue and the results of the denervation experiments, we propose that H. marmoratum uses a hydraulic mechanism to protract its tongue.
The Function of Olfactory Input in Pigeon Orientation: Does it Provide Navigational Information or Play Another Role?
Authors: Wiltschko Roswitha 
Published: April 2021

ABSTRACT
In 1972, Papi and his colleagues reported that anosmic pigeons were severely impaired in orientation and homing performance. This observation was followed up in a series of experiments involving numerous elaborate experimental manipulations. On the basis of their results, the hypothesis of olfactory navigation was proposed. Attempts to replicate these findings at other lofts produced widely differing effects, which suggested a highly variable role of olfaction. However, meteorological data, as well as certain other aspects of the findings, throw doubt on the role of odours as navigational cues. (1) Odours of the required characteristics and distribution do not seem to exist. (2) Some effects of ‘olfactory’ manipulations do not seem to depend on the availability of odours. (3) Olfactory treatments proved mostly effective, but often the effect was not as predicted. In view of these findings, explanations other than olfactory orientation cannot be excluded; accepting olfactory input as navigational information seems premature. Some of the findings are in agreement with the assumption that olfactory manipulations impair the birds’ general processing and integration of information in some unknown way.
Spatial Memory and Navigation by Honeybees on the Scale of the Foraging Range
Authors: Dyer Fred C. 
Published: April 2021

ABSTRACT
Honeybees and other nesting animals face the problem of finding their way between their nest and distant feeding sites. Many studies have shown that insects can learn foraging routes in reference to both landmarks and celestial cues, but it is a major puzzle how spatial information obtained from these environmental features is encoded in memory. This paper reviews recent progress by my colleagues and me towards understanding three specific aspects of this problem in honeybees: (1) how bees learn the spatial relationships among widely separated locations in a familiar terrain; (2) how bees learn the pattern of movement of the sun over the day; and (3) whether, and if so how, bees learn the relationships between celestial cues and landmarks.
Path Integration in Mammals and its Interaction With Visual Landmarks
Authors: Etienne Ariane S. , Maurer Roland , Séguinot Valérie 
Published: April 2021

ABSTRACT
During locomotion, mammals update their position with respect to a fixed point of reference, such as their point of departure, by processing inertial cues, proprioceptive feedback and stored motor commands generated during locomotion. This so-called path integration system (dead reckoning) allows the animal to return to its home, or to a familiar feeding place, even when external cues are absent or novel. However, without the use of external cues, the path integration process leads to rapid accumulation of errors involving both the direction and distance of the goal.
Therefore, even nocturnal species such as hamsters and mice rely more on previously learned visual references than on the path integration system when the two types of information are in conflict. Recent studies investigate the extent to which path integration and familiar visual cues cooperate to optimize the navigational performance.
Structure and Function of Learning Flights in Bees and Wasps
Authors: Zeil Jochen , Kelber Almut , Voss Rüdiger 
Published: April 2021

ABSTRACT
Bees and wasps perform systematic flight manoevres when they leave their nest or a foodplace, during which they acquire or update their visual memory of the goal location. In a typical learning flight, the insect backs away from the goal in a series of arcs that are roughly centred on the goal. The mean rate of turning is rather constant and tends to balance the angular speed at which the arc is described. As a result, the insect views the goal at relatively fixed retinal positions in its left and right visual field, depending on flight direction. The general direction in which the insect backs away from the goal and the transition from one arc segment to the next are influenced by the local scene and by compass cues. Insects returning to the goal repeat some of the flight manoeuvres of their preceding learning flights. Their orientation in space and the retinal positions at which they view nearby landmarks are similar. One important function of learning flights appears to be the acquisition of visual depth information. We review the consequences of the structure of learning flights for visual information processing and discuss how they may relate to the acquisition of a visual representation and the task of pinpointing the goal.
Small-Scale Navigation in the Honeybee: Active Acquisition of Visual Information About the Goal
Authors: Lehrer Miriam 
Published: April 2021

ABSTRACT
In a series of behavioural studies we found that bees use depth information extracted from self-induced image motion in several visual tasks involving pin-pointing the goal. Some of the results are reviewed here in an attempt to emphasise the active nature of this performance. They show that bees acquire depth information during free flight by employing two different strategies. One is to adapt flight behaviour, upon arrival at the food source, to the requirements of the task, a performance that is based on a learning process. The other is based on a stereotyped, innate flight pattern performed upon departure from the food source. The latter has probably evolved specifically for the acquisition of depth information.
Pectoral Fin Locomotion in the Striped Surfperch: II. Scaling Swimming Kinematics and Performance at a Gait Transition
Authors: Drucker Eliot G. , Jensen Jeffrey S. 
Published: April 2021

ABSTRACT
In this study, we report the first allometric equations relating gait parameters and swimming speed to body size for fish employing pectoral fin locomotion. Comparisons of locomotor kinematics and performance among striped surfperch (Teleostei: Embiotocidae) are made at the pectoral–caudal gait transition speed (Up−c). Up−c is considered to elicit physiologically equivalent levels of exercise in animals varying over 100-fold in body mass (Mb) by virtue of dynamically similar pectoral fin movements (constant duty factor, length-specific stride length and fin-beat amplitude) and size-independent propulsive efficiency. At Up−c, pectoral fin-beat frequency scales in proportion to Mb−0.12±0.03, a size-dependence consistent with that observed for stride frequency in fishes swimming by axial undulatory propulsion and in many running tetrapods. It is proposed that the similarity in the scaling of frequency in these vertebrate groups reflects an underlying similarity in the allometry of the maximal velocity of muscle shortening. Absolute Up−c (m s−1) generally increases with body size, but the fastest speeds are not exhibited by the largest animals. A pattern of declining performance in fish 23 cm in standard length and longer may be related to their disproportionately small fin areas and aspect ratios. The pronounced negative allometry of Up−c expressed as standard body lengths per second indicates that a given length-specific speed does not induce comparable levels of activity in large and small fish. Thus, normalization of swimming speed to body length may not be a sufficient correction for kinematic comparisons across size.
Endosymbiotic Chloroplasts in Molluscan Cells Contain Proteins Synthesized After Plastid Capture
Authors: Pierce Sidney K. , Biron Rachel W. , Rumpho Mary E. 
Published: April 2021

ABSTRACT
Endosymbiotic chloroplasts within the cells of the ascoglossan slug Elysia chlorotica synthesize a variety of proteins including the large subunit of ribulose-1,5-bisphosphate-carboxylase oxygenase (RuBisCO) and the photosystem II protein D1. In addition, the effects of protein synthesis inhibitors suggest that some chloroplast-associated proteins are synthesized in the animal cytosol and subsequently translocated into the chloroplasts. Thus, the plastids not only synthesize proteins during this long-lived association, but the host cell seems to play a role in plastid protein turnover.
Pre- and Postembryonic Development, Growth and Turnover of Olfactory Receptor Neurones in Crayfish Antennules
Authors: Sandeman R. E. , Sandeman D. C. 
Published: April 2021

ABSTRACT
The antennules of the crayfish Cherax destructor can first be observed as antero-laterally located lobes in embryos that have reached the 50 % stage of development. Clusters of cells that are probably the olfactory receptor neurones (ORNs) appear at the distal end of these lobes, which later differentiate into the lateral flagella of the antennules. New clusters of ORNs and segments are added at the proximal end of the lateral flagellum throughout the postembryonic stages and well into the juvenile adult stage. From a comparison of the exuvia and the newly emerged flagella in animals over a wide range of sizes, we conclude that, once the animals reach a certain size (approximately 7 mm carapace length), the most distal, and oldest, segments of the antennule are shed. Growth occurs from the proximal end of the flagellum, and the addition of new ORNs is the result of a delayed differentiation of the flagellar segments that takes place at the proximal end of the chemoreceptor array, about halfway along the flagellum.
Caffeine and Micromolar Ca2+ Concentrations Can Release Ca2+ from Ryanodine-Sensitive Stores in Crab and Lobster Striated Muscle Fibres
Authors: Lea Trevor J. 
Published: April 2021

ABSTRACT
Ca2+ release mechanisms were studied in striated muscle from the walking legs of crabs using isometric tension recordings from isolated myofibrillar bundles. Caffeine-induced phasic contractions had properties consistent with Ca2+ release from a sarcoplasmic store, which could be optimally loaded in the presence of ATP at pCa 6.4–6.1. Ryanodine (10 μmol l−1) abolished the caffeine-induced contractions and in solutions with low Ca2+ buffering (0.1 mmol l−1 EGTA) itself caused phasic contractions, indicative of Ca2+ release. Ca2+-induced Ca2+ release (CICR) was observed in a pCa 5.8 solution (buffered by 1 mmol l−1 EGTA) as a phasic contraction of variable nature, inhibited by ryanodine (10 μmol l−1), procaine (10 mmol l−1) or benzocaine (5 mmol l−1). Ca2+ release was measured as a function of releasing pCa by using the force–time integral of the caffeine-induced contraction as an estimate of the Ca2+ remaining in the store. After the Ca2+ store had been loaded for 2 min at pCa 6.6, CICR was measured in the presence of 1 mmol l−1 Mg2+, 1 mmol l−1 EGTA and 5 mmol l−1 ATP. The threshold pCa for CICR was 6.0–6.4 under these conditions and more than 90 % of stored Ca2+ was released in 1 min by pCa values in the range 3.5–5.3. Benzocaine totally inhibited the release and promoted extra Ca2+ loading. Preliminary experiments showed a similar caffeine-releasable store in lobster abdominal muscle, which was slightly less sensitive to free [Ca2+]. It is concluded that in crustacean muscle caffeine and micromolar [Ca2+] can release Ca2+ from a ryanodine-sensitive store, which in many respects is similar to the sarcoplasmic reticulum of vertebrate skeletal and cardiac muscle.
Gaba-Like Immunoreactivity of an Identified Nonspiking Local Interneurone in the Crayfish Terminal Abdominal Ganglion
Authors: Nagayama Toshiki , Aonuma Hitoshi , Miyata Hiroki 
Published: April 2021

ABSTRACT
Using an antiserum directed against γ-aminobutyric acid (GABA) to label neurones with GABA-like immunoreactivity, approximately 70 central neurones (68±9; mean ± S.E.M., N=9) were labelled in the terminal abdominal ganglion of the crayfish Procambarus clarkii. This mean number of neurones with GABA-like immunoreactivity represents approximately 10 % of the total number of neurones in the terminal ganglion. A combination of intracellular staining using Lucifer Yellow and immunocytochemical staining revealed that an identified nonspiking local interneurone (the local directionally selective interneurone, LDS) showed GABA-like immunoreactivity.
Control of Catecholamine and Serotonin Release from the Chromaffin Tissue of the Atlantic Hagfish
Authors: Bernier Nicholas J. , Perry Steve F. 
Published: April 2021

ABSTRACT
An in situ saline-perfused systemic heart/posterior cardinal vein preparation of the Atlantic hagfish (Myxine glutinosa) was used to assess (1) the ability of the chromaffin tissue to release catecholamines in response to adrenocorticotropic hormone (ACTH; 7.5 i.u. kg−1), serotonin (250 nmol kg−1), carbachol (100 μmol kg−1), [Asn1-Val5]angiotensin II (Ang II; 100 nmol kg−1), histamine (0.3–300 μmol l−1) and a high-[K+] saline (60 mmol l−1), (2) whether serotonin is co-released with the catecholamines of the chromaffin tissues, and (3) the potential modulatory effects of NECA, an adenosine receptor agonist, and DPSPX, an adenosine receptor antagonist, on catecholamine release.
Bolus injections of ACTH, serotonin or carbachol, or perfusion with high-[K+] saline, all elicited the release of both adrenaline and noradrenaline. Pre-treatment with the serotonergic receptor antagonist methysergide or the cholinergic receptor antagonist hexamethonium abolished the serotonin- and carbachol-mediated catecholamine releases, respectively. Neither receptor antagonist affected the ACTH-mediated catecholamine release. Bolus injections of Ang II or perfusion with a range of histamine concentrations, two potent secretagogues in other vertebrates, did not elicit catecholamine secretion in hagfish.
While injections of Ang II or perfusion with the high-[K+] saline both elicited the release of serotonin, treatments with ACTH, carbachol or histamine did not. Hence, co-release of catecholamines and serotonin was elicited by non-specific cell membrane depolarization using K+, but not by the specific secretagogues assessed in this study.
The adenosine receptor agonist NECA and antagonist DPSPX significantly modified the secretory responses elicited by ACTH, serotonin and carbachol. The results suggest that adenosine may inhibit catecholamine release induced by serotonin or carbachol, while stimulating ACTH-induced release.
Although the contribution of the different secretagogues identified in this study has yet to be explored in vivo, our results suggest that the control of catecholamine and serotonin release from the aneural chromaffin tissue of the Atlantic hagfish can be achieved through hormonal and/or paracrine means.
The Physiology Of Massive Zinc Accumulation In The Liver Of Female Squirrelfish And Its Relationship To Reproduction
Authors: Hogstrand Christer , Gassman Nancy J. , Popova Bilyana , Wood Chris M. , Walsh Patrick J. 
Published: April 2021

ABSTRACT
It is well known that zinc is an essential micronutrient and, as a rule, organisms keep relatively constant low levels of zinc to maintain cellular functions. The squirrelfish family (Holocentridae) is the only known exception from this rule. Squirrelfish accumulate very high concentrations of zinc in the liver. In the present study, we demonstrate that, while female squirrelfish store large amounts of zinc in the liver and ovaries, the males show zinc levels that are typical for vertebrates. The zinc content of the diet is the same in males and females, and zinc is not lost from the liver during starvation. Thus, the difference between genders in zinc storage is not dependent upon the diet. Rather, there are at least two processes that contribute to the accumulation in females. First, females possess high levels of two major zinc-binding proteins: metallothionein (MT) and a novel female-specific zinc-binding protein (FZnBP). In females, but not in males, almost all MT is present in the hepatocyte nucleus. FZnBP is exclusively found in the hepatocyte cytosol of females. Second, hepatocytes of female squirrelfish have a high capacity to transport zinc across the plasma membrane. In addition to the liver, only the gonads of females showed unusually high concentrations of zinc. Administration of exogenous oestrogen to females decreases the hepatic zinc concentration while there is a matching increase in the zinc content of the ovaries. Thus, oestrogen may trigger a redistribution of zinc from liver to ovaries. Together, our findings suggest that female squirrelfish may be uniquely adapted to detoxify zinc and to utilize it as a macronutrient for processes related to reproduction.
Molecular Forces Involved in Force Generation During Skeletal Muscle Contraction
Authors: Murphy Kenneth P. , Zhao Yan , Kawai Masataka 
Published: April 2021

ABSTRACT
Recent advances in protein chemistry and the kinetic analysis of tension transients in skeletal muscle fibres have enabled us to elucidate the molecular forces involved in force generation by cross-bridges. On the basis of the temperature effect, we conclude that the elementary step that generates force is an endothermic reaction (the enthalpy change ΔH°=124 kJ mol−1 at 15 °C), which accompanies a large entropy increase (ΔS°= 430J K−1mol−1) and a reduction in the heat capacity (ΔCp=—6.4 kJ K−1 mol−1). Thus, it can be concluded that the force-generating step is an entropy-driven reaction. The above results suggest that hydrophobic interactions are the primary cause of force generation, and that polar interactions (hydrogen bonding and charge interactions) are involved to a lesser degree. On the basis of the thermodynamic data, we estimate that during force generation approximately 50 nm2 of surface area is involved for hydrophobic interactions and another 30 nm2 for polar interactions. These data suggest that both the actomyosin interaction and the cleft closure of the myosin head are essential for force generation.
Ontogeny of Visual and Mechanosensory Structure and Function in Atlantic Menhaden Brevoortia Tyrannus
Authors: Higgs Dennis M. , Fuiman Lee A. 
Published: April 2021

ABSTRACT
The importance of visual, mechanoreceptive and auditory inputs to escape responses was examined in larvae of the Atlantic menhaden (Brevoortia tyrannus) presented with a simulated predatory stimulus. Ontogenetic changes in the retina, superficial neuromasts and auditory bullae were examined in concert with behavioral trials in which sensory inputs were selectively blocked. Menhaden larvae showed a decrease in cone photoreceptor density and first developed rod photoreceptors when their total length (TL) reached 8–10 mm; they began summing photoreceptive inputs at 12–14 mm TL. Inflation of the auditory bullae was complete by 15 mm TL. The proliferation of superficial neuromasts varied depending on their location, with cephalic superficial neuromasts decreasing in number beginning at 19 mm TL and numbers of trunk neuromasts continuing to increase throughout the larval period. In behavioral trials, responsiveness and the reactive distance to the approaching probe increased with increasing larva total length when all sensory inputs were available (control larvae). When visual inputs were blocked, responsiveness was lower than in control larvae, but still increased ontogenetically, while reactive distance showed no difference between control larvae and those lacking visual information. When neuromasts were ablated, ontogenetic increases in responsiveness and reactive distance were absent. Inflation of the auditory bullae had no discernible effect on behavior. The anatomical and behavioral results suggest that both vision and mechanoreception are used to trigger a response to a looming predatory stimulus and that mechanoreception, but not vision, contributes to the timing of the response. Ontogenetic improvements in performance are attributed mainly to neuromast proliferation and not to ontogenetic changes in the retina.
An N-Terminal Partial Sequence of the 13 kDa Pycnopodia Helianthoides Sperm Chemoattractant ‘Startrak’ Possesses Sperm-Attracting Activity
Authors: Miller Richard L. , Vogt Richard 
Published: April 2021

ABSTRACT
Freshwater extracts of starfish ovaries were used to purify the sperm-attracting peptide ‘startrak’ from Pycnopodia helianthoides using hydrophobic interaction chromatography and DEAE–high-pressure liquid chromatography. Partially purified attractant had a molecular mass of 13 kDa, estimated from gel filtration and polyacrylamide gel electrophoresis results. The purified attractant was subjected to amino acid analysis and direct sequencing, and was found to consist largely of a single peptide composed of an estimated 127 residues based on a molecular mass of 13 kDa. An N-terminal sequence of amino acids from positions 3 to 34 was obtained and synthesized as: NH 2-Ala-Glu-Leu-Gly-Leu-Cys-Ile-Ala-Arg-Val-Arg-Gln-Gln-Asn-Gln-Gly-Gln-Asp-Asp-Val-Ser-Ile-Tyr-Gln-Ala-Ile-Met-Ser-Gln-Cys-Gln-Ser-COOH. The synthetic peptide possessed sperm-attracting activity 130 times greater than the activity of partially purified startrak and showed a pattern of species-specificity of sperm chemotaxis similar to that of startrak. Antibody prepared against synthetic peptide removed the sperm-attracting activity from crude and partially purified preparations of startrak. The partial sequence of startrak was not homologous with that of any of the known echinoid sperm motility-activating peptides.