bluuebunny/crossref_metadata_2025_split huggingface dataset:
Long-Term Memory of an Operantly Conditioned Respiratory Behaviour Pattern in Lymnaea Stagnalis
Authors: Lukowiak Ken , Cotter Ralph , Westly Jackie , Ringseis Erika , Spencer Gaynor , Syed Naweed 
Published: April 2021

ABSTRACT
The freshwater snail Lymnaea stagnalis breaths bimodally either through its skin (cutaneous respiration) or via a rudimentary lung opening called the pneumostome (aerial respiration). Aerial respiratory behaviour can be operantly conditioned. Animals placed in an aquatic, hypoxic environment received a tactile stimulus to the pneumostome area every time they attempted to breathe. Over a period of five training sessions (2.5 days), the animals learned not to breathe, and the number of stimuli received in the fifth session was significantly lower than in the first session. These changes in the respiratory behaviour following the operant paradigm were shown to persist for at least 24 h. We aimed to determine whether the changes in the learned behaviour would persist for longer. We obtained direct evidence that the behavioural changes following operant conditioning persisted for at least 4 weeks following the last training session. However, we found that the persistence of this memory was dependent upon the training procedure used. Memory persisted longer following a spaced training procedure (4 weeks) as opposed to a massed training procedure (2 weeks). Yoked control animals showed no changes in their respiratory behaviour over the same time periods. However, if these yoked control animals were subjected to an operant conditioning procedure, their ability to learn was not impeded. This study demonstrated that operant conditioning of a behaviour pattern in a molluscan preparation can result in long-term memory and that the persistence of the memory is contingent on the training procedure used.
Whole-Body Composition of Xenopus Laevis Larvae: Implications for Lean Body Mass During Development
Authors: Territo Paul R. , Smits Allan W. 
Published: April 2021

ABSTRACT
Body composition in developing animals has been extensively investigated in fish larvae and bird embryos. However, no studies to date have attempted to determine whole-animal body composition or lean body mass (MLB) in developing amphibians. The present study investigates how body composition changes during development in Xenopus laevis and the potential implications of MLB for substrate turnover, energy stores, oxygen consumption and other physiological measures. Whole-animal composition was determined during development from eggs (NF stage 1) to 2 weeks post-feeding (NF 50–51), which represents two-thirds of the developmental period. Wet and dry masses were found to be highly correlated, with water content remaining constant at 93% of wet mass. Whole-animal nucleic acid content was linearly correlated with both wet and dry masses, and declined relative to mass as development progressed. Similarly, total protein content was linearly correlated with wet and dry masses; however, total protein content increased with developmental stage. Amounts of individual neutral lipids were variable although, overall, total neutral lipid content declined progressively with development. The stoichiometric ene.rgy balance paralleled the changes seen in mass-specific with the energy primarily from lipids fueling respiration up to NF 44–45. Quantification of total body composition revealed that lipid stores greatly influenced the calculations of MLB and therefore had profound underestimating effects on the mass-specific expression of numerous physiological measures through development.
Strategies for Hearing in Noise: Peripheral Control Over Auditory Sensitivity in the Bushcricket Sciarasaga Quadrata (Austrosaginae: Tettigoniidae)
Authors: Römer Heiner , Bailey Winston 
Published: April 2021

ABSTRACT
The carrier frequency of the call of the Australian bushcricket Sciarasaga quadrata is unusually low for tettigoniids at 5 kHz. The sound transmission measured in the habitat of the insect reflects the advantages of producing low-rather than high-frequency signals; attenuation is explained almost entirely by the spherical spreading of sound. The natural vibration frequency of the wings is controlled by size and stiffness. The small tegmina are unusually fleshy, with an order-of-magnitude higher water content than in comparable sagine species. Reduced stiffness allows the insect to call at low carrier frequencies, albeit at lower intensity levels (60 dB SPL at 1 m), than bushcrickets of comparable size (80–90 dB SPL). The responses of the tympanic nerve and a first-order interneurone (omega neurone) in the afferent auditory pathway showed that the hearing system is most sensitive to frequencies of 15–20 kHz, an effective mismatch to the conspecific call resulting in a reduced sensitivity of approximately 20 dB at the carrier frequency of the call. S. quadrata can occlude its spiracular opening, which increases the sensitivity of the ear to lower frequencies. Under such conditions, the best frequency of the ear matched that of the carrier frequency of the call. We measured the activity of auditory neurones in the field, noting the ability of the open and partially closed ear to filter out potentially masking calls of congenerics. At the same time, the directionality of the system was only slightly reduced in the closed relative to the open spiracle status. We discuss the evolutionary advantages of an insect both calling with a low carrier frequency and having the ability to close down the tracheal system to avoid the effects of masking. In addition, we consider the advantages of such a signalling system in avoiding the most significant predator of the male, the ormine fly Homotrixa alleni.
Scaling of Intrinsic Contractile Properties and Myofibrillar Protein Composition of Fast Muscle in the Fish Myoxocephalus Scorpius L
Authors: James Rob S. , Cole Nicholas J. , Davies Melissa L. F. , Johnston Ian A. 
Published: April 2021

ABSTRACT
Contractile properties were determined for fast muscle fibres from short-horn sculpin (Myoxocephalus scorpius L.) ranging from 5 to 35 cm total body length (L) and from 2.0 to 758 g body mass. Maximum unloaded shortening velocity (V0) decreased with increasing body size, scaling as 19.5L−0.34, and isometric twitch activation and tetanus relaxation times became longer, scaling as 12.0L0.31 and 19.5L0.42 respectively. Myofibrillar Mg2+/Ca2+-ATPase activity scaled as 2.51L−0.28. In order to investigate the mechanisms underlying the scaling of contractile properties, myofibrillar protein composition and I filament lengths were determined. One-dimensional SDS–PAGE and two-dimensional isoelectric focusing/non-equilibrium isoelectric focusing–PAGE revealed no differences in the myofibrillar protein isoforms of myosin light chains, actin, tropomyosin, troponin-T and troponin-C in fish of differing body size. Peptide maps of purified myosin heavy chains digested with eight different proteolytic enzymes were also similar in all fish examined. Three isoforms of troponin-I were present in fish less than 20 cm in total length with relative molecular masses of 17 (TnIf3), 22 (TnIf2) and 23 (TnIf1). The ratio of TnI isoforms varied with body length, and only TnIf3 was present in fish greater than 28 cm total length. The length of I filaments was independent of body length. Thus, although the expression of TnI isoforms changes during growth, the underlying mechanism responsible for increased shortening velocity with decreased body size remains unknown.
Morphological Characterization of the Bursting and Nonbursting Neurones in the Olfactory Centre of the Terrestrial Slug Limax Marginatus
Authors: Watanabe Satoshi , Kawahara Shigenori , Kirino Yutaka 
Published: April 2021

ABSTRACT
We investigated the morphological characteristics of physiologically characterized neurones in the procerebrum (PC) of the terrestrial slug Limax marginatus. The electrophysiological characteristics of the neurones were determined using the perforated patch recording technique. By comparing the shapes and sizes of somata, we found that the somata of bursting neurones were larger and had more oblong shapes than those of nonbursting neurones, indicating that the bursting and nonbursting neurones in the PC could be discriminated on the basis of the sizes and shapes of their soma. Injection of fluorescent dyes into the bursting and nonbursting neurones revealed morphological differences in the neurites. The bursting neurones had extensive projections within the cell body layer, and the major neurites of the bursting neurones were oriented along the dorsal–ventral axis. In contrast, the nonbursting neurones had neurites extending into the neuropile layers, where terminals of both sensory and presumed output neurones exist.
Development of Heart Rate in the Precocial King Quail Coturnix Chinensis
Authors: Pearson James T. , Tsudzuki Masaoki , Nakane Yoshifumi , Akiyama Ryuichi , Tazawa Hiroshi 
Published: April 2021

ABSTRACT
Our aim was to examine changes in heart rate (fH) during the embryonic and posthatching periods of the smallest precocial avian species, Coturnix chinensis. In experiment I, repeated measurements of mean fH were made for individual quail by ballistocardiogram (BCG) during incubation, and by both piezo-electric film and electrocardiogram (ECG) during the posthatching period (resting and thermoneutral conditions). Mean fH of all embryos increased during the second half of incubation and the first week posthatching, but a few embryos experienced a very brief period of decreased fH prior to internal pipping. After the first week, fH of posthatching quail was maintained at high levels (550–650 beats min−1), then decreased with age and increase in body mass. The maximal fH of quail chicks represents a greater posthatching increase in fH than is found in larger precocial chickens, this difference being attributable to the higher demands of thermoregulation at small body masses in the quail. In experiment II, the mean fH of quail embryos (day 2–16) was recorded by ECG, and embryonic stage, yolk-free embryo mass (wet and dry) and water content were measured. Mean fH was linearly related to embryo mass throughout incubation, except on the day prior to internal pipping, when the fH of a few embryos declined below this linear relationship. Measurements of instantaneous fH of late incubation embryos, young and adult quail all showed spontaneous fluctuations in fH. Two main frequency components of fH fluctuations were identified for the first time in an avian species. Low-frequency (mean 0.09 Hz, 12.6 s) and high-frequency (1.4 Hz, 0.9 s) oscillations in both young chicks and adult quail were detected and are considered to reflect baroreflex mediation of fH and respiratory sinus arrhythmia, respectively.
Air-Breathing During Activity in the Fishes Amia Calva and Lepisosteus Oculatus
Authors: Farmer C. G. , Jackson D. C. 
Published: April 2021

ABSTRACT
Many osteichthyan fishes obtain oxygen from both air, using a lung, and water, using gills. Although it is commonly thought that fishes air-breathe to survive hypoxic aquatic habitats, other reasons may be more important in many species. This study was undertaken to determine the significance of air-breathing in two fish species while exercising in oxygen-rich water. Oxygen consumption from air and water was measured during mild activity in bowfin (Amia calva) and spotted gar (Lepisosteus oculatus) by sealing a fish in an acrylic flume that contained an air-hole. At 19–23°C, the rate of oxygen consumption from air in both species was modest at rest. During low-level exercise, more than 50% of the oxygen consumed by both species was from the air (53.0±22.9% L. oculatus; 66.4±8.3% A. calva).
Estimating Velocities and Accelerations of Animal Locomotion: A Simulation Experiment Comparing Numerical Differentiation Algorithms
Authors: Walker Jeffrey A. 
Published: April 2021

ABSTRACT
Functional biologists employ numerical differentiation for many purposes, including (1) estimation of maximum velocities and accelerations as measures of behavioral performance, (2) estimation of velocity and acceleration histories for biomechanical modeling, and (3) estimation of curvature, either of a structure during movement or of the path of movement itself. I used a computer simulation experiment to explore the efficacy of ten numerical differentiation algorithms to reconstruct velocities and accelerations accurately from displacement data. These algorithms include the quadratic moving regression (MR), two variants of an automated Butterworth filter (BF1–2), four variants of a method based on the signal’s power spectrum (PSA1–4), an approximation to the Wiener filter due to Kosarev and Pantos (KPF), and both a generalized cross-validatory (GCV) and predicted mean square error (MSE) quintic spline. The displacement data simulated the highly aperiodic escape responses of a rainbow trout Oncorhynchus mykiss and a Northern pike Esox lucius (published previously). I simulated the effects of video speed (60, 125, 250, 500 Hz) and magnification (0.25, 0.5, 1 and 2 screen widths per body length) on algorithmic performance. Four performance measures were compared: the per cent error of the estimated maximum velocity (Vmax) and acceleration (Amax) and the per cent root mean square error over the middle 80% of the velocity (VRMSE) and acceleration (ARMSE) profiles.
The results present a much more optimistic role for numerical differentiation than suggested previously. Overall, the two quintic spline algorithms performed best, although the rank order of the methods varied with video speed and magnification. The MSE quintic spline was extremely stable across the entire parameter space and can be generally recommended. When the MSE spline was outperformed by another algorithm, both the difference between the estimates and the errors from true values were very small. At high video speeds and low video magnification, the GCV quintic spline proved unstable. KPF and PSA2–4 performed well only at high video speeds. MR and BF1–2 methods, popular in animal locomotion studies, performed well when estimating velocities but poorly when estimating accelerations. Finally, the high variance of the estimates for some methods should be considered when choosing an algorithm.
Energy Absorption During Running by Leg Muscles in a Cockroach
Authors: Full Robert J. , Stokes Darrell R. , Ahn Anna N. , Josephson Robert K. 
Published: April 2021

ABSTRACT
Biologists have traditionally focused on a muscle’s ability to generate power. By determining muscle length, strain and activation pattern in the cockroach Blaberus discoidalis, we discovered leg extensor muscles that operate as active dampers that only absorb energy during running. Data from running animals were compared with measurements of force and power production of isolated muscles studied over a range of stimulus conditions and muscle length changes.We studied the trochanter-femoral extensor muscles 137 and 179, homologous leg muscles of the mesothoracic and metathoracic legs, respectively. Because each of these muscles is innervated by a single excitatory motor axon, the activation pattern of the muscle could be defined precisely. Work loop studies using sinusoidal strains at 8 Hz showed these trochanter-femoral extensor muscles to be quite capable actuators, able to generate a maximum of 19–25 W kg−1 (at 25°C). The optimal conditions for power output were four stimuli per cycle (interstimulus interval 11 ms), a strain of approximately 4%, and a stimulation phase such that the onset of the stimulus burst came approximately half-way through the lengthening phase of the cycle. High-speed video analysis indicated that the actual muscle strain during running was 12% in the mesothoracic muscles and 16% in the metathoracic ones. Myographic recordings during running showed on average 3–4 muscle action potentials per cycle, with the timing of the action potentials such that the burst usually began shortly after the onset of shortening. Imposing upon the muscle in vitro the strain, stimulus number and stimulus phase characteristic of running generated work loops in which energy was absorbed (−25W kg−1) rather than produced. Simulations exploring a wide parameter space revealed that the dominant parameter that determines function during running is the magnitude of strain. Strains required for the maximum power output by the trochanter-femoral extensor muscles simply do not occur during constant, average-speed running. Joint angle ranges of the coxa–trochanter–femur joint during running were 3–4 times greater than the changes necessary to produce maximum power output. None of the simulated patterns of stimulation or phase resulted in power production when strain magnitude was greater than 5%. The trochanter-femoral extensor muscles 137/179 of a cockroach running at its preferred speed of 20 cm s−1 do not operate under conditions which maximize either power output or efficiency. In vitro measurements, however, demonstrate that these muscles absorb energy, probably to provide control of leg flexion and to aid in its reversal.
Atmospheric Oxygen, Giant Paleozoic Insects and the Evolution of Aerial Locomotor Performance
Authors: Dudley Robert 
Published: April 2021

ABSTRACT
Uniformitarian approaches to the evolution of terrestrial locomotor physiology and animal flight performance have generally presupposed the constancy of atmospheric composition. Recent geophysical data as well as theoretical models suggest that, to the contrary, both oxygen and carbon dioxide concentrations have changed dramatically during defining periods of metazoan evolution. Hyperoxia in the late Paleozoic atmosphere may have physiologically enhanced the initial evolution of tetrapod locomotor energetics; a concurrently hyperdense atmosphere would have augmented aerodynamic force production in early flying insects. Multiple historical origins of vertebrate flight also correlate temporally with geological periods of increased oxygen concentration and atmospheric density. Arthropod as well as amphibian gigantism appear to have been facilitated by a hyperoxic Carboniferous atmosphere and were subsequently eliminated by a late Permian transition to hypoxia. For extant organisms, the transient, chronic and ontogenetic effects of exposure to hyperoxic gas mixtures are poorly understood relative to contemporary understanding of the physiology of oxygen deprivation. Experimentally, the biomechanical and physiological effects of hyperoxia on animal flight performance can be decoupled through the use of gas mixtures that vary in density and oxygen concentration. Such manipulations permit both paleophysiological simulation of ancestral locomotor performance and an analysis of maximal flight capacity in extant forms.
Quiescence in Artemia Franciscana Embryos: Reversible Arrest of Metabolism and Gene Expression at Low Oxygen Levels
Authors: Hand Steven C. 
Published: April 2021

ABSTRACT
Depression of the production and consumption of cellular energy appears to be a prerequisite for the survival of prolonged bouts of anoxia. A correlation exists between the degree of metabolic depression under anoxia and the duration of anoxia tolerance. In the case of brine shrimp (Artemia franciscana) embryos, oxygen deprivation induces a reversible quiescent state that can be tolerated for several years with substantial survivorship. A global arrest of cytoplasmic translation accompanies the transition into anoxia, and rates of protein synthesis in mitochondria from these embryos appears to be markedly reduced in response to anoxia. Previous evidence suggests that the acute acidification of intracellular pH (pHi) by over 1.0 unit during the transition into anoxia contributes to the depression of biosynthesis, but message limitation does not appear to play a role in the down-regulation in either cellular compartment. The ontogenetic increase in mRNA levels for a mitochondrial-encoded subunit of cytochrome c oxidase (COX I) and for nuclear-encoded actin is blocked by anoxia and aerobic acidosis (artificial quiescence imposed by intracellular acidification under aerobic conditions). Further, the levels of COX I and actin mRNA do not decline appreciably during 6 h bouts of quiescence, even though protein synthesis is acutely arrested across this same period. Thus, the constancy of mRNA levels during quiescence indicates that reduced protein synthesis is not caused by message limitation but, instead, is probably controlled at the translational level. This apparent stabilization of mRNA under anoxia is mirrored in an extension of protein half-life. The ubiquitin-dependent pathway for protein degradation is depressed under anoxia and aerobic acidosis, as judged by the acute drop in levels of ubiquitin-conjugated proteins.
Mitochondrial protein synthesis is responsive to both acidification of pHi and removal of oxygen per se. Matrix pH declines in parallel with pHi, and evidence from experiments with nigericin indicates that mitochondrial protein synthesis is depressed directly by acidification of matrix pH. The oxygen dependency of organellar protein synthesis is not explained by blockage of the electron transport chain or by the increased redox state. Rather, this cyanide- and antimycin-insensitive, but hypoxia-sensitive, inhibitory signature for the arrest of protein synthesis suggests the presence of a molecular oxygen sensor within the mitochondrion.
Two Visual Pigments In A Single Photoreceptor Cell: Identification And Histological Localization Of Three Mrnas Encoding Visual Pigment Opsins In The Retina Of The Butterfly Papilio Xuthus
Authors: Kitamoto Junko , Sakamoto Katsuhiko , Ozaki Koichi , Mishina Yuji , Arikawa Kentaro 
Published: April 2021

ABSTRACT
This paper describes the localization of newly identified visual pigment opsins in the tiered retina of the Japanese yellow swallowtail Papilio xuthus. We first cloned three cDNAs encoding visual pigment opsins, PxRh1, PxRh2 and PxRh3, and then carried out histological in situ hybridization to localize their mRNAs in the retina. By combining the present data with our previous electrophysiological results, we concluded that both PxRh1 and PxRh2 correspond to visual pigments expressed in photoreceptor cells sensitive in the green wavelength region (green receptors), whereas PxRh3 corresponds to a pigment in red receptors. The in situ hybridization studies showed that some photoreceptor cells express two opsin mRNAs. In the ventral half of the eye, all green receptors in the distal tier were labelled by both PxRh1 and PxRh2 probes. The labelling by the PxRh2 and PxRh3 probes was detected throughout the eye in the proximal tier; in 18 % of ommatidia, the probes labelled the same photoreceptor cell. These results suggest that the possible co-localization of two different visual pigments will broaden the sensitivity spectrum of the photoreceptor cells.
Rhodopsin-Like Proteins in Planarian Eye and Auricle: Detection and Functional Analysis
Authors: Asano Yoshiya , Nakamura Satoshi , Ishidas Sachiko , Azuma Katsu , Shinozawa Takao 
Published: April 2021

ABSTRACT
The presence of rhodopsin-like proteins in the eyes and auricles of the freshwater planarian Dugesia japonica was confirmed using anti-frog-rhodopsin rabbit IgG. The apparent relative molecular masses of these proteins were 65×103 and 62×103, and positive reactions to IgG were localized to the microvilli of the photoreceptor cells in the eyes and to the sensory cilia, rootlets and microvilli in the auricles. Eye- or head-excised planarians showed no negative phototaxis, whereas intact or auricle-excised planarians did. During regeneration in head-excised planarians, the appearance of rhodopsin-like proteins in the regenerating eyes corresponded to the recovery of negative phototaxis behaviour. Head or auricle excision enhanced asexual fission under continuous illumination. However, eye excision had no such effect. These results suggest that the rhodopsin-like proteins in the eyes work as photoreceptors for negative phototaxis behaviour and that, in the auricles, they are involved in asexual fission originating from the circadian rhythm.