bluuebunny/crossref_metadata_2025 huggingface dataset:
Myotomal Slow Muscle Function of Rainbow Trout Oncorhynchus Mykiss During Steady Swimming
Authors: Hammond Lucy , Altringham John D. , Wardle Clement S.
Published: April 2021

Strain and activity patterns were determined during slow steady swimming (tailbeat frequency 1.5–2.5 Hz) at three locations on the body in the slow myotomal muscle of rainbow trout Oncorhynchus mykiss using sonomicrometry and electromyography. Strain was independent of tailbeat frequency over the range studied and increased significantly from ±3.3 % l0 at 0.35BL to ±6 % at 0.65BL, where l0 is muscle resting length and BL is total body length. Muscle activation occurred significantly later in the strain cycle at 0.35BL (phase shift 59 °) than at 0.65BL (30 °), and the duration of activity was significantly longer (211 ° at 0.35BL and 181 ° at 0.65BL). These results differ from those of previous studies. The results have been used to simulate in vivo activity in isolated muscle preparations using the work loop technique. Preparations from all three locations generated net positive power under in vivo conditions, but the negative power component increased from head to tail. Both kinematically, and in the way its muscle functions to generate hydrodynamic thrust, the rainbow trout appears to be intermediate between anguilliform swimmers such as the eel, which generate thrust along their entire body length, and carangiform fish (e.g. saithe Pollachius virens), which generate thrust primarily at the tail blade.
Spatial Vision in the Prosobranch Gastropod Ampularia Sp.
Authors: Seyer Jan-Olof , Nilsson Dan-E. , Warrant Eric J.
Published: April 2021

The eyes of gastropods of the genus Ampularia superficially resemble the well-developed camera-type eyes of Littorina littorea and Strombus raninus. The eyes are of the closed-vesicle type, having a cornea and a lens that is separated from the retina by a narrow vitreous body.

Light and electron microscopy were used to generate an accurate geometrical model of the Ampularia sp. eye, which was then used to predict its optical performance. The image quality of the lens was investigated using a modified microscope and revealed that images suffer from severe aberrations. The focal length was estimated to be approximately 430 μm, putting the plane of best focus in or just proximal to the rhabdoms. The aberrant optics result in a large retinal blur-circle with a diameter of approximately 120 μm and an angular half-width of approximately 17 °, allowing only comparatively poor resolution compared with the eyes of Littorina littorea and Strombus raninus. Behavioural experiments revealed no significant optomotor response.

The results imply that Ampularia sp. has poor spatial vision, limited by the blur-circles on the retina. The eyes appear to be suitable only for relatively simple visual tasks, such as finding an open water surface for breathing, but the large size of the eye allows it to perform this task even at night.
A Study of the Temporary Adhesion of the Podia in the Sea Star Asterias Rubens (Echinodermata, Asteroidea) through their Footprints
Authors: Flammang Patrick , Michel Alain , Van Cauwenberge Anne , Alexandre Henri , Jangoux Michel
Published: April 2021

Sea stars are able to make firm but temporary attachments to various substrata owing to secretions released by their podia. A duo-glandular model has been proposed in which an adhesive material is released by two types of non-ciliated secretory (NCS1 and NCS2) cells and a de-adhesive material is released by ciliated secretory (CS) cells. The chemical composition of these materials and the way in which they function have been investigated by studying the adhesive footprints left by the asteroids each time they adhere to a substratum. The footprints of Asterias rubens consist of a sponge-like material deposited as a thin layer on the substratum. Inorganic residues apart, this material is made up mainly of proteins and carbohydrates. The protein moiety contains significant amounts of both charged (especially acidic) and uncharged polar residues as well as half-cystine. The carbohydrate moiety is also acidic, comprising both uronic acids and sulphate groups. Polyclonal antibodies have been raised against footprint material and were used to locate the origin of footprint constituents in the podia. Extensive immunoreactivity was detected in the secretory granules of both NCS1 and NCS2 cells, suggesting that their secretions together make up the bulk of the adhesive material. No immunoreactivity was detected in the secretory granules of CS cells, and the only other structure strongly labelled was the outermost layer of the cuticle, the fuzzy coat. This pattern of immunoreactivity suggests that the secretions of CS cells are not incorporated into the footprints, but instead might function to jettison the fuzzy coat, thereby allowing the podium to detach.
Glutamatergic Neuromuscular Transmission in the Heart Of The Isopod Crustacean Ligia Exotica
Authors: Sakurai Akira , Mori Akihiko , Yamagishi Hiroshi
Published: April 2021

Neuromuscular transmission between the cardiac ganglion (CG) and the myocardium was examined in the adult heart of the isopod crustacean Ligia exotica. Intracellular injection of neurobiotin into the CG neurones revealed that all six CG neurones send their axons onto the cardiac muscle, where they form axon terminals bearing varicosities. All the CG neurones and their processes exhibited glutamate-like immunoreactivity. The cardiac muscle showed depolarizing membrane potential responses to glutamate applied focally to sites close to axon terminals bearing varicosities. Both the glutamate-induced response and the excitatory junctional potential (EJP) showed desensitization in response to the repeated application of glutamate. Under voltage-clamp conditions, the cardiac muscle produced inward current responses to focally applied glutamate. The reversal potential for the glutamate-induced current estimated from extrapolation of the linear current/voltage relationship was similar to that of the excitatory junctional current evoked by ganglionic nerve stimulation. Both the glutamate-induced response and the EJP were blocked by a glutamate-specific antagonist, Joro spider toxin. These results led us to conclude that the CG neurones of Ligia exotica are glutamatergic motoneurones.
Acid–Base and Respiratory Responses to Hypoxia in the Grasshopper Schistocerca Americana
Authors: Greenlee Kendra J. , Harrison Jon F.
Published: April 2021

How do quiescent insects maintain constant rates of oxygen consumption at ambient values as low as 2–5 kPa? To address this question, we examined the response of the American locust Schistocerca americana to hypoxia by measuring the effect of decreasing ambient on haemolymph acid–base status, tracheal and CO2 emission. We also tested the effect of hypoxia on convective ventilation using a new optical technique which measured the changes in abdominal volume during ventilation. Hypoxia caused a progressive increase in haemolymph pH and a decrease in haemolymph . A Davenport analysis suggests that hypoxia is accompanied by a net transfer of base to the haemolymph, perhaps as a result of intracellular pH regulation. Hypoxia caused a progressive increase in convective ventilation which was mostly attributable to a rise in ventilatory frequency. Carbon dioxide conductance (μmol h−1 kPa−1) across the spiracles increased more than threefold, while conductance between the haemolymph and primary trachea nearly doubled in 2 kPa O2 relative to room air. The rise in trans-spiracular conductance is completely attributable to the elevations in convective ventilation. The rise in tracheal conductance in response to hypoxia may reflect the removal of fluid from the tracheoles described by Wigglesworth. The low critical of quiescent insects can be attributed (1) to their relatively low resting metabolic rates, (2) to the possession of tracheal systems adapted for the exchange of gases at much higher rates during activity and (3) to the ability of insects to rapidly modulate tracheal conductance.
Ca2+-ATPase ACTIVITY AND Ca2+ UPTAKE BY SARCOPLASMIC RETICULUM IN FISH HEART: EFFECTS OF THERMAL ACCLIMATION
Authors: Aho Eija , Vornanen Matti
Published: April 2021

This study was designed to compare the activities of sarcoplasmic (SR) Ca2+-ATPase and Ca2+ uptake in fish and mammalian hearts and to determine whether thermal acclimation has any effect on the function of the cardiac SR in fish. To this end, we measured thapsigargin-sensitive Ca2+-ATPase activity and thapsigargin-inhibitable Ca2+ uptake velocity in crude cardiac homogenates of newborn and adult rats and of two teleost fish (crucian carp and rainbow trout) acclimated to low (4°C) and high (17°C and 24°C for trout and carp, respectively) ambient temperatures.

The TG-sensitive Ca2+-ATPase activity was highest in adult rat, and the corresponding activities of cold-acclimated trout, warm-acclimated trout, warm-acclimated carp, cold-acclimated carp and newborn rat were 76, 58, 43, 28 and 23%, respectively, of that of the adult rat at 25°C. SR Ca2+ uptake velocity, measured using Fura-2 at room temperature (approximately 22°C), was highest in cold-acclimated trout, and the values for adult rat, warm-acclimated trout, newborn rat, warm-acclimated carp and cold-acclimated carp were 93, 56, 24, 21 and 14% of the uptake velocity of cold-acclimated trout, respectively. When corrected to the body temperature of the animal, the relative rates of SR Ca2+ uptake were 100, 26, 19, 18, 11 and 2% for adult rat, newborn rat, cold-acclimated trout, warm-acclimated trout, warm-acclimated carp and cold-acclimated carp, respectively.

These findings show that SR Ca2+ uptake is slower in fish than in mammalian hearts and that marked species-specific differences exist among teleost fish in this respect. Furthermore, acclimation to cold increases the Ca2+ uptake rate of trout cardiac SR (complete thermal compensation) but decreases the SR Ca2+ uptake rate of crucian carp heart. This difference in acclimation response probably reflects the different activity patterns of the two species in their natural habitat during the cold season.
Ca2+ Signals During Early Lymphocyte Activation in Carp Cyprinus Carpio L
Authors: Verburg-Van Kemenade B.M. Lidy , Saeij Jeroen P. J. , Flik Gert , Willems Peter H. G. M.
Published: April 2021

To measure cellular responses and the involvement of increased cytosolic Ca2+ levels ([Ca2+]i), peripheral blood leukocytes (PBL) of carp were loaded with the fluorescent intracellular Ca2+ indicators Fluo-3 and Fura-2. Responses of lymphocytes to T-cell mitogen (phytohaemagglutinin, PHA), to B-cell mitogen (lipopolysaccharide, LPS) and to immunoglobulin (Ig) cross-linking with a monoclonal antibody to carp Ig were measured using flow cytometry. Both T-cell stimulation by PHA and B-cell stimulation by membrane Ig cross-linking evoked a rapid elevation of [Ca2+]i. B-cell stimulation by LPS was not linked to an increase in [Ca2+]i. As judged by the percentage of reacting cells, it was concluded that all Ig-positive lymphocytes reacted to Ig cross-linking by elevating [Ca2+]i. At the single-cell level, the reactions of Fura-2-loaded cells were followed every 6 s using digital imaging microscopy. Both cells displaying spontaneous [Ca2+]i oscillations and non-oscillating cells responded to stimulation with an increase in [Ca2+]i, sometimes, in already oscillating cells, accompanied by an increase in frequency and/or amplitude of the oscillations. These results show that intracellular Ca2+ responses of PBL upon activation resemble those in mammals and form a powerful tool for studies into cell-specific regulation.
Redox state, reactive oxygen species and adaptive growth in colonial hydroids
Authors: Blackstone Neil W.
Published: April 2021

Colonial metazoans often encrust surfaces over which the food supply varies in time or space. In such an environment, adaptive colony development entails adjusting the timing and spacing of feeding structures and gastrovascular connections to correspond to this variable food supply. To investigate the possibility of such adaptive growth, within-colony differential feeding experiments were carried out using the hydroid Podocoryna carnea. Indeed, such colonies strongly exhibited adaptive growth, developing dense arrays of polyps (feeding structures) and gastrovascular connections in areas that were fed relative to areas that were starved, and this effect became more consistent over time. To investigate mechanisms of signaling between the food supply and colony development, measurements were taken of metabolic parameters that have been implicated in signal transduction in other systems, particularly redox state and levels of reactive oxygen species. Utilizing fluorescence microscopy of P. carnea cells in vivo, simultaneous measurements of redox state [using NAD(P)H] and hydrogen peroxide (using 2′,7′-dichlorofluorescin diacetate) were taken. Both measures focused on polyp epitheliomuscular cells, since these exhibit the greatest metabolic activity. Colonies 3–5h after feeding were relatively oxidized, with low levels of peroxide, while colonies 24h after feeding were relatively reduced, with high levels of peroxide. The functional role of polyps in feeding and generating gastrovascular flow probably produced this dichotomy. Polyps 3–5h after feeding contract maximally, and this metabolic demand probably shifts the redox state in the direction of oxidation and diminishes levels of reactive oxygen species. In contrast, 24h after feeding, polyps are quiescent, and this lack of metabolic demand probably shifts the redox state in the direction of reduction and increases levels of reactive oxygen species. Within-colony differential feeding experiments were carried out on colonies 24h after the usual, colony-wide feeding. At this time, a single polyp was fed, and this polyp was compared with an otherwise similar polyp from the same colony. A pattern similar to the whole-colony experiments was obtained: the just-fed polyp, as it begins contracting shortly after feeding, appears to be relatively oxidized, with low levels of peroxide compared with the polyp that was not fed. These data are consistent with the hypothesis that adaptive colony development in response to a variable food supply is mediated by redox state or reactive oxygen species or both, although alternative hypotheses are also discussed.
A DROSOPHILA MELANOGASTER Strain From Sub-Equatorial Africa Has Exceptional Thermotolerance But Decreased Hsp70 Expression
Authors: Zatsepina Olga G. , Velikodvorskaia Vera V. , Molodtsov Vasilii B. , Garbuz David , Lerman Daniel N. , Bettencourt Brian R. , Feder Martin E. , Evgenev Michael B.
Published: April 2021

Drosophila melanogaster collected in sub-equatorial Africa in the 1970s are remarkably tolerant of sustained laboratory culture above 30°C and of acute exposure to much warmer temperatures. Inducible thermotolerance of high temperatures, which in Drosophila melanogaster is due in part to the inducible molecular chaperone Hsp70, is only modest in this strain. Expression of Hsp70 protein and hsp70 mRNA is likewise reduced and has slower kinetics in this strain (T) than in a standard wild-type strain (Oregon R). These strains also differed in constitutive and heat-inducible levels of other molecular chaperones. The lower Hsp70 expression in the T strain apparently has no basis in the activation of the heat-shock transcription factor HSF, which is similar in T and Oregon R flies. Rather, the reduced expression may stem from insertion of two transposable elements, H.M.S. Beagle in the intergenic region of the 87A7 hsp70 gene cluster and Jockey in the hsp70Ba gene promoter. We hypothesize that the reduced Hsp70 expression in a Drosophila melanogaster strain living chronically at intermediate temperatures may represent an evolved suppression of the deleterious phenotypes of Hsp70.
In Vitro Effects of Environmental Salinity and Cortisol on Chloride Cell Differentiation in Embryos of Mozambique Tilapia, OREOCHROMIS MOSSAMBICUS, Measured Using a Newly Developed ‘Yolk-Ball’ Incubation System
Authors: Shiraishi Kiyono , Hiroi Junya , Kaneko Toyoji , Matsuda Manabu , Hirano Tetsuya , Mori Takao
Published: April 2021

To examine the functional differentiation of chloride cells in the yolk-sac membrane of tilapia (Oreochromis mossambicus) embryos, we developed a ‘yolk-ball’ incubation system in which the yolk sac was separated from the embryonic body and subjected to incubation in vitro. The yolk-ball preparation consists of the yolk and the covering yolk-sac membrane, which contains a rich population of chloride cells. After appropriate cutting, the incision on the yolk ball healed during incubation in balanced salt solution for 3h, so that the yolk-sac membrane completely enclosed the yolk. Yolk balls prepared from freshwater-acclimated embryos were transferred either to fresh water or to sea water and incubated for 48 and 96h to elucidate the morphological changes in the chloride cells in response to environmental salinity. The chloride cells in the yolk-sac membrane were larger in sea water than in fresh water. In yolk balls transferred to sea water, chloride cells often formed multicellular complexes characteristic of seawater-type chloride cells. In those transferred to fresh water, however, the cells were small and rarely formed such complexes. These responses of chloride cells were identical to those observed in intact embryos. Thus, chloride cells in the yolk-sac membrane could differentiate into the seawater type independent of the embryonic body. To examine the possible effects of exogenous cortisol on chloride cell differentiation, the yolk balls were incubated for 48h in fresh water or sea water containing different doses of cortisol (0.1–10μgml−1). Although chloride cells were consistently larger in sea water than in fresh water in all experimental groups, cortisol administration had no effect on chloride cell surface area in either medium. These findings indicate that the chloride cells in the yolk-sac membrane are equipped with an autonomous mechanism of functional differentiation that is independent of the embryonic endocrine and nervous systems. The yolk-ball incubation system established here is an excellent experimental model for further studies on chloride cell differentiation and function.
Arginine Vasotocin Modulates a Sexually Dimorphic Communication Behavior in the Weakly Electric fish APTERONOTUS LEPTORHYNCHUS
Authors: Bastian Joseph , Schniederjan Stephanie , Nguyenkim Jerry
Published: April 2021

South American weakly electric fish produce a variety of electric organ discharge (EOD) amplitude and frequency modulations including chirps or rapid increases in EOD frequency that function as agonistic and courtship and mating displays. In Apteronotus leptorhynchus, chirps are readily evoked by the presence of the EOD of a conspecific or a sinusoidal signal designed to mimic another EOD, and we found that the frequency difference between the discharge of a given animal and that of an EOD mimic is important in determining which of two categories of chirp an animal will produce. Type-I chirps (EOD frequency increases averaging 650Hz and lasting approximately 25ms) are preferentially produced by males in response to EOD mimics with a frequency of 50–200Hz higher or lower than that of their own. The EOD frequency of Apteronotus leptorhynchus is sexually dimorphic: female EODs range from 600 to 800Hz and male EODs range from 800 to 1000Hz. Hence, EOD frequency differences effective in evoking type-I chirps are most likely to occur during male/female interactions. This result supports previous observations that type-I chirps are emitted most often during courtship and mating. Type-II chirps, which consist of shorter-duration frequency increases of approximately 100Hz, occur preferentially in response to EOD mimics that differ from the EOD of the animal by 10–15Hz. Hence these are preferentially evoked when animals of the same sex interact and, as previously suggested, probably represent agonistic displays. Females typically produced only type-II chirps. We also investigated the effects of arginine vasotocin on chirping. This peptide is known to modulate communication and other types of behavior in many species, and we found that arginine vasotocin decreased the production of type-II chirps by males and also increased the production of type-I chirps in a subset of males. The chirping of most females was not significantly affected by arginine vasotocin.
Neuropeptides are ubiquitous chemical mediators: Using the stomatogastric nervous system as a model system
Authors: Skiebe Petra
Published: April 2021

The stomatogastric nervous system (STNS) controls the movements of the foregut and the oesophagus of decapod crustaceans and is a good example for demonstrating that peptides are ubiquitously distributed chemical mediators in the nervous system. The stomatogastric ganglion (STG), one of the four ganglia of the STNS, contains the most intensively investigated neuronal circuits. The other ganglia, including the two commissural ganglia (CoGs) and the oesophageal ganglion (OG), are thought to be modulatory control centres. Peptides reach the STNS either as neurohormones or are released as transmitters. Peptide neurohormones can be released either from neurohaemal organs or from local neurohaemal release zones located on the surface of nerves and connectives. There were thought to be no peptidergic neurones with cell bodies in the STG itself. However, some have recently been described in adults of four species, in addition to a transient expression of peptides during development in two species. None of these peptidergic neurones has been investigated physiologically, in contrast to peptidergic neurones that project to the STG and have cell bodies in either the CoGs or the OG. It has been shown that neurones containing the same peptide elicit different motor patterns, that the peptide transmitter and the classical transmitter are not necessarily co-released and that the effect of a peptidergic neurone depends on its firing frequency and on which other modulatory neurones are co-active. The activity of modulatory projection neurones can be elicited by sensory neurones, and their activity can depend on the firing frequency of the sensory neurone. In addition to being found within the neuropile of ganglia, peptides are present in neuropile patches located within the nerves of the STNS, suggesting that these nerves can integrate as well as transfer information. Furthermore, sensory neurones and muscles exhibit peptide-like immunoreactivity and are modulated by peptides. Bath-applied peptides elicit peptide-specific motor patterns within the STG by targeting subsets of neurones. This divergence is contrasted by a convergence at the level of currents: five different peptides modulate a single current. Peptides not only induce motor patterns but can also switch the alliance of neurones from one network to another or are able to fuse different networks. In general, peptides are the most abundant group of modulators within the STNS; they are ubiquitously present, indicating that they play multiple roles in the plasticity of neural networks.
Differential and overlapping expression patterns ofX-dll3andPax-6genes suggest distinct roles in olfactory system development of the African clawed frogXenopus laevis
Authors: Franco Marie-Dominique , Pape Michael P. , Swiergiel Jennifer J. , Burd Gail D.
Published: April 2021

In Xenopus laevis, the formation of the adult olfactory epithelium involves embryonic, larval and metamorphic phases. The olfactory epithelium in the principal cavity (PC) develops during embryogenesis from the olfactory placode and is thought to respond to water-borne odorants throughout larval life. During metamorphosis, the PC undergoes major transformations and is exposed to air-borne odorants. Also during metamorphosis, the middle cavity (MC) develops de novo. The olfactory epithelium in the MC has the same characteristics as that in the larval PC and is thought to respond to water-borne odorants. Using in situ hybridization, we analyzed the expression pattern of the homeobox genes X-dll3 and Pax-6 within the developing olfactory system. Early in development, X-dll3 is expressed in both the neuronal and non-neuronal ectoderm of the sense plate and in all cell layers of the olfactory placode and larval PC. Expression becomes restricted to the neurons and basal cells of the PC by mid-metamorphosis. During metamorphosis, X-dll3 is also expressed throughout the developing MC epithelium and becomes restricted to neurons and basal cells at metamorphic climax. This expression pattern suggests that X-dll3 is first involved in the patterning and genesis of all cells forming the olfactory tissue and is then involved in neurogenesis or neuronal maturation in putative water- and air-sensing epithelia. In contrast, Pax-6 expression is restricted to the olfactory placode, larval PC and metamorphic MC, suggesting that Pax-6 is specifically involved in the formation of water-sensing epithelium. The expression patterns suggest that X-dll3 and Pax-6 are both involved in establishing the olfactory placode during embryonic development, but subtle differences in cellular and temporal expression patterns suggest that these genes have distinct functions.
Mechanical properties of red and white swimming muscles as a function of the position along the body of the eelAnguilla anguilla
Authors: D’Août K. , Curtin N. A. , Williams T. L. , Aerts P.
Published: April 2021

The way in which muscles power steady swimming depends on a number of factors, including fibre type and recruitment, muscle strain, stimulation pattern and intensity, and the intrinsic mechanical properties of the muscle fibres. For a number of undulatory swimming fish species, in vivo studies have shown that muscles at different positions along the body are stimulated during different phases of the strain cycle. Moreover, some intrinsic contractile properties of the muscles have been found to vary according to their position along the body.

We report the first results on the mechanical properties of the red and white muscles of an anguilliform swimmer, Anguilla anguilla. Small preparations (0.147–1.335mg dry mass) were dissected from positions at fractions of 0.2, 0.4, 0.6 and 0.8 of total body length (BL). We determined the time to 50% and 100% peak force and from the last stimulus to 50% relaxation for isometric contractions; we measured the sarcomere lengths that coincided with in situ resting length. None of these quantities varied significantly with the longitudinal position from which the fibres were taken. We also measured power and work output during contractions under conditions approximating those used in vivo (cycle frequency, 1Hz; strain amplitude, ±10%L0, where L0 is the length giving maximum isometric force). During these experiments, work output was affected by stimulation phase, but did not depend on the longitudinal position in the body from which the muscles were taken.

Our results indicate that red and white eel muscles have uniform properties along the body. In this respect, they differ from the muscle of most non-anguilliforms, in which muscle kinetics varies in a systematic way along the body. Uniform properties may be beneficial for anguilliform swimmers, in which the amplitude of the travelling wave can be pronounced over the entire body length.
Analysis of epithelial K+ transport in Malpighian tubules ofDrosophila melanogaster: evidence for spatial and temporal heterogeneity
Authors: Rheault Mark R. , O’Donnell Michael J.
Published: April 2021

Transport of K+ by the lower, main and distal segments of the Malpighian tubules of Drosophila melanogaster was analyzed using self-referencing K+-selective microelectrodes. Transport properties of the Malpighian tubules of Drosophila melanogaster change along their length. Self-referencing ion-selective (SeRIS) microelectrode measurements (relative to the bath concentration of 20 mmoll−1) showed a 1% reduction (P<0.05) of [K+] in the unstirred layer adjacent to the main segment of the Malpighian tubules, confirming secretion of K+ from the bath to the tubule lumen. Conversely, SeRIS measurements showed a 0.7% increase (P<0.05) in [K+] in the unstirred layer adjacent to the lower segment of Malpighian tubules, confirming reabsorption of K+ from the luminal fluid to the bath. Measurements using SeRIS also showed that the distal segment neither secreted nor reabsorbed K+. There was pronounced spatial heterogeneity in K+ transport by the lower segment and the main segment; not all morphologically similar cells participated equally in K+ transport, nor did all main segment cells respond equally to stimulation of K+ transport by cyclic AMP. Pronounced temporal heterogeneity in K+ reabsorption by the lower Malpighian tubules was also observed. We suggest that this reflects periodic reduction in K+ reabsorption due to retention of fluid within the lower segment when the ureter contracts.
Cone-based vision of rats for ultraviolet and visible lights
Authors: Jacobs Gerald H. , Fenwick John A. , Williams Gary A.
Published: April 2021

Rats (Rattus norvegicus) have two classes of cone, one containing an ultraviolet (UV)-sensitive photopigment and the other housing a pigment maximally sensitive in the middle (M) wavelengths of the visible spectrum. The manner in which signals from these two cone types contribute to rat vision was investigated through recordings of a gross electrical potential (the electroretinogram, ERG) and behavioral discrimination tests. Spectral sensitivity functions obtained from both types of measurement indicate clear contributions from each of the cone classes, but there is a marked enhancement of the relative sensitivity to UV light in the behavioral index; for instance, under some photopic test conditions, rats are approximately equally sensitive to middle-wavelength and UV lights. In adaptation tests, thresholds for UV and M lights were found to be differentially elevated in the presence of chromatic adapting backgrounds, thus providing the possibility that signals from the two cones could be used by the rat visual system to support color discriminations. Evidence of dichromatic color vision in the rat was subsequently obtained from tests of wavelength discrimination.
Polarized light detection in spiders
Authors: Dacke Marie , Doan Thuy A. , O’Carroll David C.
Published: April 2021

We describe here the detection of polarized light by the simple eyes of spiders. Using behavioural, morphological, electrophysiological and optical studies, we show that spiders have evolved two different mechanisms to resolve the e-vector of light. Wolf spiders (Lycosidae), are able to turn in response to rotation of a polarized pattern at the zenith of their visual fields, and we also describe a strip in the ventral retina of the principal (anterio-median) eyes that views this location and has receptors tiered into two layers. This provides each pair of receptors with a similar optical solution to that provided by the ‘dorsal rim area’ of the insect compound eye. In contrast, gnaphosid spiders have evolved a pair of lensless secondary eyes for the detection of polarized light. These two eyes, each sensitive to orthogonal directions of polarization, are perfectly designed to integrate signals from the larger part of the sky and cooperate to analyse the polarization of light. Built-in polarizers help to improve signal purity. Similar organisation in the eyes of several other spider families suggests that these two mechanisms are not restricted to only a few families.
Ultraviolet colour opponency in the turtle retina
Authors: Ventura D. F. , Zana Y. , Souza J. M. de , DeVoe R. D.
Published: April 2021

We have examined the functional architecture of the turtle Pseudemys scripta elegans retina with respect to colour processing, extending spectral stimulation into the ultraviolet, which has not been studied previously in the inner retina. We addressed two questions. (i) Is it possible to deduce the ultraviolet cone spectral sensitivity function through horizontal cell responses? (ii) Is there evidence for tetrachromatic neural mechanisms, i.e. UV/S response opponency? Using a constant response methodology we have isolated the ultraviolet cone input into the S/LM horizontal cell type and described it in fine detail.

Monophasic (luminosity), biphasic L/M (red-green) and triphasic S/LM (yellow-blue) horizontal cells responded strongly to ultraviolet light. The blue-adapted spectral sensitivity function of a S/LM cell peaked in the ultraviolet and could be fitted to a porphyropsin cone template with a peak at 372nm.

In the inner retina eight different combinations of spectral opponency were found in the centre of the receptive field of ganglion cells. Among amacrine cells the only types found were UVSM−L+ and its reverse. One amacrine and four ganglion cells were also opponent in the receptive field surround.

UV/S opponency, seen in three different types of ganglion cell, provides a neural basis for discrimination of ultraviolet colours. In conclusion, the results strongly suggest that there is an ultraviolet channel and a neural basis for tetrachromacy in the turtle retina.
Flight kinematics of the barn swallow (Hirundo rustica) over a wide range of speeds in a wind tunnel
Authors: Park Kirsty J. , Rosén Mikael , Hedenström Anders
Published: April 2021

Two barn swallows (Hirundo rustica) flying in the Lund wind tunnel were filmed using synchronised high-speed cameras to obtain posterior, ventral and lateral views of the birds in horizontal flapping flight. We investigated wingbeat kinematics, body tilt angle, tail spread and angle of attack at speeds of 4–14ms−1. Wingbeat frequency showed a clear U-shaped relationship with air speed with minima at 8.9ms−1(bird 1) and 8.7ms−1 (bird 2). A method previously used by other authors of estimating the body drag coefficient (CD,par) by obtaining agreement between the calculated minimum power (Vmin) and the observed minimum wingbeat frequency does not appear to be valid in this species, possibly due to upstroke pauses that occur at intermediate and high speeds, causing the apparent wingbeat frequency to be lower. These upstroke pauses represent flap-gliding, which is possibly a way of adjusting the force generated to the requirements at medium and high speeds, similar to the flap-bound mode of flight in other species. Body tilt angle, tail spread and angle of attack all increase with decreasing speed, thereby providing an additional lift surface and suggesting an important aerodynamic function for the tail at low speeds in forward flight. Results from this study indicate the high plasticity in the wingbeat kinematics and use of the tail that birds have available to them in order to adjust the lift and power output required for flight.
TEMPERATURE AND MYOGENIC FACTOR TRANSCRIPT LEVELS DURING EARLY DEVELOPMENT DETERMINES MUSCLE GROWTH POTENTIAL IN RAINBOW TROUT(ONCORHYNCHUS MYKISS) AND SEA BASS (DICENTRARCHUS LABRAX)
Authors: WILKES D. , XIE S. Q. , STICKLAND N. C. , ALAMI-DURANTE H. , KENTOURI M. , STERIOTI A. , KOUMOUNDOUROS G. , FAUCONNEAU B. , GOLDSPINK G.
Published: April 2021

The influence of changes in environmental temperature on the mRNA levels of myogenic regulatory factors (MRFs), i.e. MyoD and myogenin, as well as myosin heavy chain (MyHC) were studied during early larval development in rainbow trout and sea bass. Phosphoimager analysis of northern blots indicated that there is an optimum temperature for the RNA transcript levels of MRF and MyHC RNA in trout and in sea bass larvae. In the trout strain studied, the highest concentration for MRF and MyHC transcripts was found at 8°C rather than 4°C or 20°C. In European sea bass, the highest concentrations of MRF and MyHC mRNA were observed at 15-20°C rather than 13°C. Raising sea bass larvae at 15°C was associated with higher MyHC gene expression as well as a trend towards an increase in total muscle fibre number and higher growth rates after transfer at ambient temperature. Results suggest that mRNA levels of MRF and MyHC can be used to optimise early development. An experiment in which the temperature was changed illustrates the consequence of precise temporal expression of MRF genes in specifying muscle fibre number at critical stages during early development.
EFFECTS OF DURATION AND TIME OF FOOD AVAILABILITY ON PHOTOPERIODIC RESPONSES IN THE MIGRATORY MALE BLACKHEADED BUNTING (EMBERIZA MELANOCEPHALA)
Authors: KUMAR VINOD , SINGH SUDHI , MISRA MANJU , MALIK SHALIE
Published: April 2021

The effects of the duration and time of food availability on stimulation of the photoperiodic responses (fattening and gain in body mass, and growth and development of testes) were investigated in the migratory blackheaded bunting(Emberiza melanocephala). Two experiments were performed. Experiment 1 examined the effects of a reduction in the duration of food supply in buntings that were subjected to long day lengths (16 h:8 h L:D) and received food ad libitum (group I) or for restricted durations, coinciding with the end of the lights-on period, of 8 h (group II) and 4 h (group III). Buntings of group I gained in body mass, whereas there was a mixed response in group II (half the birds gained and half lost body mass), and all birds of group III lost body mass. There was no effect on testis growth in groups I and II, but testes grew more slowly in group III. Experiment 2 investigated the effects of both the duration and the time of food availability. Of five groups of birds, group I was exposed to an 8 h:16 h L:D photoperiod, and groups II-V were exposed to 16 h:8 h L:D. Whereas birds of groups I and II received food ad libitum, those of groups III-V were fed only for 5 h, at zt 0-5(group III), zt 5.5-10.5 (group IV) or zt 11-16 (group V), where zt =zeitgeber time and zt 0 refers to the beginning of the lights-on period. Apart from duration, the timing of food availability also had an effect on photoperiodic stimulation under the 16 h:8 h L:D photoperiod. Birds that were fed ad libitum fattened and gained in body mass, whereas among restricted feeding groups, only birds in the group fed during the first 5 h(zt 0-5, group III) showed a significant increase in body mass (albeit considerably lower than in the ad libitum group). Birds fed during the middle 5 h (zt 5.5-10.5, group IV) showed an intermediate response, and those fed during the last 5 h (zt 11-16, group V) lost body mass. Testicular growth was suppressed in birds that were fed for 5 h in the evening, but not in those fed for the same period in the morning or in the middle of the long day. Taken together, these results show that the duration of food supply and/or the time of day at which food is available affect photoperiodic stimulation of fattening and gain in body mass as well as the growth and development of gonads in the blackheaded bunting.
Mechanisms of helical swimming: asymmetries in the morphology, movement and mechanics of larvae of the ascidianDistaplia occidentalis
Authors: McHenry Matthew J.
Published: April 2021

A great diversity of unicellular and invertebrate organisms swim along a helical path, but it is not well understood how asymmetries in the body shape or the movement of propulsive structures affect a swimmer’s ability to perform the body rotation necessary to move helically. The present study found no significant asymmetries in the body shape of ascidian larvae (Distaplia occidentalis) that could operate to rotate the body during swimming. By recording the three-dimensional movement of free-swimming larvae, it was found that the tail possessed two bends, each with constant curvature along their length. As these bends traveled posteriorly, the amplitude of curvature changes was significantly greater in the concave-left direction than in the concave-right direction. In addition to this asymmetry, the tail oscillated at an oblique angle to the midline of the trunk. These asymmetries generated a yawing moment that rotated the body in the counterclockwise direction from a dorsal view, according to calculations from hydrodynamic theory. The tails of resting larvae were bent in the concave-left direction with a curvature statistically indistinguishable from the median value for tail curvature during swimming. The flexural stiffness of the tails of larvae, measured in three-point bending, may be great enough to allow the resting curvature of the tail to have an effect on the symmetry of kinematics. This work suggests that asymmetrical tail motion is an important mechanism for generating a yawing moment during swimming in ascidian larvae and that these asymmetries may be caused by the tail’s bent shape. Since helical motion requires that moments also be generated in the pitching or rolling directions, other mechanisms are required to explain fully how ascidian larvae generate and control helical swimming.
Molecular cloning and characterisation of a novel membrane receptor gene from the lobster Jasus edwardsii
Authors: Khoo Jenny Gaik Imm , Sin Frank Y. T.
Published: April 2021

The eyestalk of the lobster, Jasus edwardsii, is an important source for hormones involved in the regulation of growth and reproduction. How these hormones transfer their messages to the cell and nucleus is not known. This paper describes the cloning, characterization and expression analyses of two genes that code for two membrane-associated peptides that may be involved in signal transduction. These genes, peJK2 and peJK3, were isolated from a cDNA library derived from lobster eyestalk mRNAs. The two clones shared 96.6 % sequence homology, and code for putative proteins of 110 and 113 amino acids, respectively. These were likely to be two allelic forms of the same gene. Northern blot analysis using these clones as probes detected the same mRNA from eyestalk, muscle and epithelial extracts, but with greater intensity in the eyestalk extract. In situ hybridisation also indicated the predominant expression of these genes in the eyestalk. Analysis of the putative protein sequences showed that they contained two transmembrane (TM) helices, a short amino acid sequence sharing high homology with the G-protein-coupled receptor (GPCR) motif in the second TM, a signal sequence between the TMs, and a protein kinase phosphorylation site at the C termini. Sequence analyses therefore suggested that the deduced peptides may function in signal transduction.
Comparison of rural practice in relation to upper gastrointestinal endoscopy
Authors: Kotani Kazuhiko
Published: April 2021

doi: https://doi.org/10.12669/pjms.37.4.4397

How to cite this:Kotani K. Comparison of rural practice in relation to upper gastrointestinal endoscopy. Pak J Med Sci. 2021;37(4):1244-1245.  doi: https://doi.org/10.12669/pjms.37.4.4397

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Effects of L-carnitine supplementation in diets of broiler chickens
Authors: AZIZI-CHEKOSARI Μ , BOUYE Μ , SEIDAVI AR
Published: April 2021

L-carnitine is a nutritional supplement having fat-burning property and plays an important role in lipid metabolism, energy release, and also improve the production yield, immunity and blood constitute. This paper reviews the effects of L-carnitine on quantitative and qualitative characteristics of broilers. According to the reviewed literature, the application of L-carnitine (50-200 mg/kg) has no significant effect on the growth performance, however, using L-carnitine as much as 300-800 mg/kg resulted to an improvement in the body weight (2226.00-2575.00 g) compared to the control chicks (1998.40-2338.75 g). The feed conversion ratios of the chickens fed the same amount of L-carnitine were 1.66-1.86 kg/kg, which was improved in comparison with the control chicks (1.87-2.09 kg/kg). Abdominal fat of the broiler chickens fed 50-900 mg/kg L-carnitine was 0.98-1.75%, which is lower than the control chicks (1.79-2.16%). For immunity, the antibody titers against the Newcastle virus in the chickens fed 250 mg/kg L-carnitine was between 4.6- 5.5 which is more than control chicks (4.3-5.2). The antibody titer against the influenza virus in the chickens fed the same amount of L-carnitine was between 5.6-6.3, which was more than the control chicks (4.3-5.8). The use of 100-600 mg/kg L-carnitine could reduce triglyceride (90-104.4 mg/dL) compared to the control chicks (125-104.7 mg/dL) and also reduced the cholesterol (109-115 mg/dL) compared to the control chicks (129.25-131 mg/dL). The application of 100-600 mg/kg L-carnitine also could reduce low-density lipoprotein (LDL) from 19.1-72.2 mg/dL to 16.5-49.0 mg/dL. However, the application of 100-900 mg/kg L-carnitine had no significant effect on the sensory characteristics of broiler chicken meat. In general, it can be concluded that L-carnitine can be used as a dietary supplement on the health of broiler chickens without any negative effect on growth performance.
Detection of Mycobacterium avium subsp. paratuberculosis in liver of slaughtered cattle, sheep and goats by PCR and culture
Authors: ZAREI M , TAJBAKHSH S , GHORBANPOUR M , YOUSEFVAND A , RAHIMI S , SHAHPOURI M , AMERI A , MOSAVARI N
Published: April 2021

The presence of Mycobacterium avium subsp. paratuberculosis (MAP) in tissues other than intestines and associated lymph nodes is a potential public health concern. Therefore, the presence of MAP in the liver of slaughtered cattle, sheep and goats with unknown Johne’s disease status was evaluated. Liver samples were collected randomly from 470 mature animals including 200 cattle, 135 sheep and 135 goats. The existence of MAP DNA from obtained liver samples was determined using PCR, thereafter PCR-confirmed samples were cultured. Based on liver PCR results, IS900 genes were detected in 11/200 (5.5%), 3/135 (2.2%), 2/135 (1.48%) liver samples of cattle, sheep and goats, respectively. In cattle, sheep and goats, 6 (54.5%), 1 (33.3%) and 1 (50%) PCR-positive samples showed positive results in culture, respectively. Our results revealed that MAP can be detected and cultured from the liver of slaughtered cattle, sheep and goats with unknown Johne’s disease status. Hence, given concerns about a potential zoonotic role for MAP, there is a crucial need to detect animals with MAP disseminated infection in the liver before slaughter.
Investigation of omentin-1 and metabolic parameters in periparturient cows
Authors: AYGORMEZ S , ATAKISI E
Published: April 2021

We aimed to determine the level of omentin-1 hormone and other in periparturient period of dairy cows. It was also aimed to determine whether there is a correlation between omentin-1, glucose, Non-esterified fatty acids (NEFA), triglycerides (TG) and β-hydroxybutyrate (BHB). Blood samples were taken a month before parturition (PreP30), two weeks before parturition (PreP14), at parturition (P), two weeks after parturition (PostP14) and a month after parturition (PostP30). Concentrations of serum omentin-1 at P, serum glucose at P, PostP14, and PostP30, serum NEFA at P, serum TG PreP30 and PreP14, and serum BHB at P were statistically significantly higher than at other times. A positive correlation was observed between omentin-1 and glucose, NEFA and BHB, glucose and NEFA and BHB, and NEFA and BHB. A negative correlation was found between TG and omentin-1, glucose, NEFA and BHB. In conclusion, findings of the present study shows that omentin-1 may play an important role in the periparturient period. A positive correlation of omentin-1 with energy fuels NEFA, glucose, and BHB suggests that omentin-1 plays a role in energy metabolism like other adipokines. The fact that omentin-1 levels increase during delivery, when the fetus needs energy most, supports this hypothesis.