bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Tail Shape on Tadpole Swimming Performance
Authors: Buskirk Josh Van , Mccollum S. Andy 
Published: April 2021

ABSTRACT
Many tadpoles respond to insect predators by developing deeper, and sometimes longer, tails. It has been assumed that the larger tail enhances aspects of swimming performance, because deep-tailed tadpoles survive well when confronted with hunting predators. We tested this hypothesis using both naturally occurring and surgically created variation in tail morphology of Hyla versicolor tadpoles. We measured swimming performance (maximum speed, time to reach a 2.5 cm radius, and angle of escape) and morphology (size and shape of the body and tail) in 288 tadpoles, of which half possessed the predator-induced morphology and the other half were from predator-free ponds. Large tadpoles swam faster than small ones, and shape was significantly correlated with size-corrected swimming performance. The fastest tadpoles had relatively shallow bodies and tail fins, and short tails; there was no difference in swimming performance between predator-induced and no-predator tadpoles. We performed an experiment to create independent variation in tail depth and length by surgically manipulating tail shape in 270 tadpoles. Three tail-length treatments reduced the length of the tail fin by 21 %, 34 % and 55 %; three tail-depth treatments reduced the maximum depth of the tail fin by 11 %, 34 % and 59 %; two additional treatments controlled for the effects of anaesthesia and surgery. The angle of escape was unaffected by surgery. Maximum speed and minimum escape time were both significantly impaired by the high-removal treatments, but showed no evidence of decline until 30 % of the tail (length or depth) was removed. These results suggest that the relatively deep tails in predator-induced tadpoles (approximately 10 % deeper than in no-predator tadpoles) do not improve performance in burst swimming. Thus, predator-induced tadpoles are less vulnerable to predation for reasons other than enhanced swimming performance.
Drinking in Snakes: Kinematic Cycling and Water Transport
Authors: Cundall David 
Published: April 2021

ABSTRACT
Snakes are purported to drink by sucking water into their mouths and then compressing the oral cavity to force water into the oesophagus. Video recordings of drinking behaviour in 23 snakes representing 14 species from three families, combined with simultaneous recordings of water volumes consumed, show that all the snakes vary widely in the amount of water taken in when drinking. This variation is not correlated with kinematic events. Kinematic recordings and indirect measurements of water flow suggest that moving water into the mouth can be decoupled from the processes that move water into the oesophagus and that, infrequently, water may continue flowing into the mouth during both opening (suction) and closing (presumed compression) of the mouth. Drinking in snakes is not a simple, stereotyped behaviour.
Different snake species differ in both drinking kinematics and water inflow patterns. Vertical excursions of the mandible are smallest in booids and larger, but highly variable, in different viperids and colubrids. Cyclic movements of the tongue seen in booids are not evident in viperids or colubrids. All the snakes usually take in water at rates far below their potential maximum rate.
Although drinking is apparently achieved by suction, a single model cannot explain all water movement patterns in snakes. At a practical level, functional morphological studies of drinking in snakes (and possibly many other animals) must demonstrate that fluid flow actually correlates with kinematic events. Without such an empirical demonstration, interpretation of other measurements (pressure, movement, etc.) is unlikely to produce meaningful models.
Atp Production from the Oxidation of Sulfide in Gill Mitochondria of the Ribbed Mussel Geukensia Demissa
Authors: Parrino Vincent , Kraus David W. , Doeller Jeannette E. 
Published: April 2021

ABSTRACT
The ribbed mussel Geukensia demissa inhabits intertidal Spartina grass marshes characterized by sulfide-rich sediments. Sulfide poisons aerobic respiration, and G. demissa may cope in this seemingly inhospitable environment by oxidizing sulfide in gill mitochondria. Well-coupled mitochondria isolated from G. demissa gills were used to investigate sulfide oxidation and ATP synthesis. State 3 respiration, maximally stimulated by 5 μmol l−1 sulfide with a P/O ratio of 0.89 and a respiratory control ratio (RCR) of 1.40, remained refractory to sulfide at higher concentrations except in the presence of salicylhydroxamic acid (SHAM), an inhibitor of alternative oxidases. Sulfide-stimulated ATP production was 3–5 times greater than that stimulated by malate and succinate, respectively, giving an ATP/sulfide ratio of 0.63. The inhibition of sulfide-stimulated respiration and ATP production by the complex III inhibitors myxothiazol and antimycin A, respectively, suggests that electrons enter the electron transport chain before complex III. Combined with in vivo evidence for electron entry at cytochrome c, these data suggest that more than one type of sulfide-oxidizing enzyme may function in G. demissa gills. The SHAM-sensitive pathway of electron flux may be a critical component of a physiological strategy to tolerate sulfide. We conclude that G. demissa exploits the energy available from its reduced environment by using sulfide as a respiratory substrate for cellular ATP production.
The Effects of Cell Ageing on Protein Synthesis in Rainbow Trout (Oncorhynchus Mykiss) Red Blood Cells
Authors: Lund Susan G. , Phillips Matthew C. L. , Moyes Christopher D. , Tufts Bruce L. 
Published: April 2021

ABSTRACT
The effects of cell age on protein synthesis were examined in the nucleated red blood cells of rainbow trout (Oncorhynchus mykiss). Total DNA content was unaffected by cell age, whereas total RNA content in young red blood cells was roughly ten times as high as that in old red blood cells. The mRNA levels for haemoglobin, carbonic anhydrase and the chloride/bicarbonate (Cl−/HCO3−) exchanger were also approximately tenfold higher in young red blood cells. Although young red blood cells synthesized roughly five times more protein under steady-state conditions, total protein concentration was not affected by cell age. Despite large reductions in mRNA levels with red blood cell ageing, the concentrations and/or activities of the respiratory proteins were largely preserved. In contrast, the ability to mount a heat shock response was greatly reduced in older red blood cells. Young red blood cells produced 13 times more heat shock protein 70 mRNA following heat shock and four times more 70 kDa protein after recovery. They also transcribed much more heat shock cognate 71 and heat shock factor mRNA than did older red blood cells under steady-state conditions.
Nacl Uptake by the Branchial Epithelium in Freshwater Teleost Fish: An Immunological Approach to Ion-Transport Protein Localization
Authors: Wilson Jonathan M. , Laurent Pierre , Tufts Bruce L. , Benos Dale J. , Donowitz Mark , Vogl A. Wayne , Randall David J. 
Published: April 2021

ABSTRACT
Teleost fishes, living in fresh water, engage in active ion uptake to maintain ion homeostasis. Current models for NaCl uptake involve Na+uptake via an apical amiloride-sensitive epithelial Na+channel (ENaC), energized by an apical vacuolar-type proton pump (V-ATPase) or alternatively by an amiloride-sensitive Na+/H+exchange (NHE) protein, and apical Cl−uptake mediated by an electroneutral, SITS-sensitive Cl−/HCO3−anion-exchange protein. Using non-homologous antibodies, we have determined the cellular distributions of these ion-transport proteins to test the predicted models. Na+/K+-ATPase was used as a cellular marker for differentiating branchial epithelium mitochondria-rich (MR) cells from pavement cells. In both the freshwater tilapia (Oreochromis mossambicus) and rainbow trout (Oncorhynchus mykiss), V-ATPase and ENaC-like immunoreactivity co-localized to pavement cells, although apical labelling was also found in MR cells in the trout. In the freshwater tilapia, apical anion-exchanger-like immunoreactivity is found in the MR cells. Thus, a freshwater-type MR chloride cell exists in teleost fishes. The NHE-like immunoreactivity is associated with the accessory cell type and with a small population of pavement cells in tilapia.
Humboldt Penguins Outmanoeuvring El NiñO
Authors: Culik B. , Hennicke J. , Martin T. 
Published: April 2021

ABSTRACT
We satellite-tracked five Humboldt penguins during the strong 1997/98 El Niño Southern Oscillation (ENSO) from their breeding island Pan de Azúcar (26°09′S, 70°40′W) in Northern Chile and related their activities at sea to satellite-derived information on sea surface temperature (SST), sea surface temperature anomaly (SSTA), wind direction and speed, chlorophyll a concentrations and statistical data on fishery landings.
We found that Humboldt penguins migrated by up to 895 km as marine productivity decreased. The total daily dive duration was highly correlated with SSTA, ranging from 3.1 to 12.5 h when the water was at its warmest (+4 °C). Birds travelled between 2 and 116 km every day, travelling further when SSTA was highest. Diving depths (maximum 54 m), however, were not increased with respect to previous years.
Two penguins migrated south and, independently of each other, located an area of high chlorophyll a concentration 150 km off the coast. Humboldt penguins seem to use day length, temperature gradients, wind direction and olfaction to adapt to changing environmental conditions and to find suitable feeding grounds. This makes Humboldt penguins biological in situ detectors of highly productive marine areas, with a potential use in the verification of trends detected by remote sensors on board satellites.
Expression of Arginine Kinase Enzymatic Activity and mRNA in Gills of The Euryhaline Crabs Carcinus Maenas and Callinectes Sapidus
Authors: Kotlyar Simon , Weihrauch Dirk , Paulsen Ryan S. , Towle David W. 
Published: April 2021

ABSTRACT
Phosphagen kinases catalyze the reversible dephosphorylation of guanidino phosphagens such as phosphocreatine and phosphoarginine, contributing to the restoration of adenosine triphosphate concentrations in cells experiencing high and variable demands on their reserves of high-energy phosphates. The major invertebrate phosphagen kinase, arginine kinase, is expressed in the gills of two species of euryhaline crabs, the blue crab Callinectes sapidus and the shore crab Carcinus maenas, in which energy-requiring functions include monovalent ion transport, acid–base balance, nitrogen excretion and gas exchange. The enzymatic activity of arginine kinase approximately doubles in the ion-transporting gills of C. sapidus, a strong osmoregulator, when the crabs are transferred from high to low salinity, but does not change in C. maenas, a more modest osmoregulator. Amplification and sequencing of arginine kinase cDNA from both species, accomplished by reverse transcription of gill mRNA and the polymerase chain reaction, revealed an open reading frame coding for a 357-amino-acid protein. The predicted amino acid sequences showed a minimum of 75 % identity with arginine kinase sequences of other arthropods. Ten of the 11 amino acid residues believed to participate in arginine binding are completely conserved among the arthropod sequences analyzed. An estimation of arginine kinase mRNA abundance indicated that acclimation salinity has no effect on arginine kinase gene transcription. Thus, the observed enhancement of enzyme activity in C. sapidus probably results from altered translation rates or direct activation of pre-existing enzyme protein.
Modulation of the Cost of pHi Regulation During Metabolic Depression: A 31P-NMR Study in Invertebrate (Sipunculus Nudus) Isolated Muscle
Authors: Pörtner H. O. , Bock C. , Reipschläger A. 
Published: April 2021

ABSTRACT
Extracellular acidosis has been demonstrated to play a key role in the process of metabolic depression under long-term environmental stress, exemplified in the marine invertebrate Sipunculus nudus. These findings led to the hypothesis that acid–base regulation is associated with a visible cost depending on the rate and mode of H+-equivalent ion exchange. To test this hypothesis, the effects of different ion-transport inhibitors on the rate of pH recovery during hypercapnia, on energy turnover and on steady-state acid–base variables were studied in isolated body wall musculature of the marine worm Sipunculus nudus under control conditions (pHe 7.90) and during steady-state extracellular acidosis (pHe 7.50 or 7.20) by in vivo31P-NMR and oxygen consumption analyses. During acute hypercapnia (2 % CO2), recovery of pHi was delayed at pHe 7.5 compared with pHe 7.9. Inhibition of the Na+/H+-exchanger by 5-(N,N-dimethyl)-amiloride (DMA) at pHe 7.5 delayed recovery even further. This effect was much smaller at pHe 7.9. Inhibition of anion exchange by the addition of the transport inhibitor 4,4′-diisothiocyanatostilbene-2,2′-disulphonic acid (DIDS) prevented pH recovery at pHe 7.5 and delayed recovery at pHe 7.9, in accordance with an effect on Na+-dependent Cl−/HCO3− exchange. The effects of ouabain, DIDS and DMA on metabolic rate were reduced at low pHe, thereby supporting the conclusion that acidosis caused the ATP demand of Na+/K+-ATPase to fall. This reduction occurred via an inhibiting effect on both Na+/H+- and Na+-dependent Cl−/HCO3− (i.e. Na+/H+/Cl−/HCO3−) exchange in accordance with a reduction in the ATP demand for acid–base regulation during metabolic depression. Considering the ATP stoichiometries of the two exchangers, metabolic depression may be supported by the predominant use of Na+/H+/Cl−/HCO3− exchange under conditions of extracellular acidosis.
The Effect of Alterations in Activity and Body Temperature on the Pulmonary Surfactant System in the Lesser Long-Eared Bat Nyctophilus Geoffroyi
Authors: Slocombe Nicola C. , Codd Jonathan R. , Wood Philip G. , Orgeig Sandra , Daniels Christopher B. 
Published: April 2021

ABSTRACT
Pulmonary surfactant is a mixture of phospholipids, neutral lipids and proteins that controls the surface tension of the fluid lining the lung. It is critical for lung stability and function. The amount and composition of surfactant are influenced by physiological variables such as metabolic rate, body temperature and ventilation. We investigated the plasticity of the pulmonary surfactant system in the microchiropteran bat Nyctophilus geoffroyi throughout a natural 24 h cycle. Bats were housed at 24 °C on a fixed (8 h:16 h) light:dark photoperiod. At 4 h intervals throughout the 24 h period, bats were lavaged and the surfactant analysed for absolute and relative amounts of total phospholipid (PL), disaturated phospholipid (DSP) and cholesterol (Chol). N. geoffroyi experienced two peaks of activity, at 18:00 h and 06:00 h. The amount of surfactant increased 1.5-fold upon arousal from torpor. The proportion of DSP to PL in the surfactant remained constant. Similarly, the Chol/PL and Chol/DSP ratios remained relatively constant. Surfactant cholesterol content did not increase during torpor in N. geoffroyi. Cholesterol does not appear to control surfactant fluidity during torpor in these bats, but instead the cholesterol content exactly mirrored the diurnal changes in body temperature.
Ventilatory and Cardiovascular Responses of a Python (Python Molurus) To Exercise and Digestion
Authors: Secor Stephen M. , Hicks James W. , Bennett Albert F. 
Published: April 2021

ABSTRACT
To investigate the potential limiting steps of peak metabolic rates, we examined gas exchange rates , respiratory exchange ratio (RER), breathing frequency, tidal volume, minute ventilation volume as well as the heart rate, systemic blood flow and stroke volume of Burmese pythons (Python molurus) while fasting at rest, exercising, digesting and exercising while digesting. All measured variables increased significantly during exercise (crawling at 0.4 km h−1 and at ), highlighted by a 17-fold increase in and a 24-fold increase in .
During the digestion of a meal equivalent to 25 % of the snake’s body mass, pythons responded with increases in and heart rate similar to those experienced during exercise, along with a 4.5-fold increase in systemic blood flow. Interestingly, pythons hyperventilated while exercising, whereas they hypoventilated during digestion. The combined demands of exercise and digestion resulted in significantly higher breathing frequency and heart rate than during either exercise or digestion alone. Evidently, the capacities of the ventilatory and cardiovascular systems to transport oxygen to locomotor muscles are not a limiting factor in the attainment of peak metabolic rates during exercise in pythons
Early Specialization of the Superfast Myosin in Extraocular and Laryngeal Muscles
Authors: Briggs Margaret M. , Schachat Fred 
Published: April 2021

ABSTRACT
Extraocular muscle (EOM) exhibits high-velocity, low-tension contractions compared with other vertebrate striated muscles. These distinctive properties have been associated with a novel myosin heavy chain (MyHC) isoform, MyHC-EO. An atypical MyHC, MyHC IIL, has also been identified in laryngeal muscles that have similarly fast contractile properties. It co-migrates with MyHC-EO on high-resolution SDS gels, but appeared to be encoded by a different mRNA. We combined CNBr peptide maps and full-length cDNA sequences to show that rabbit muscle EO and IIL MyHCs are identical. Analysis of the 5′ untranslated region (5′UTR) of the mRNAs identified three variants that result from a combination of alternative splicing and multiple transcription initiation sites. This complex pattern of 5′UTRs has not been reported previously for MyHC genes. We identified the human homologue of the MyHC-EO gene in GenBank, and analyzed the 5′ upstream region, which revealed a paucity of muscle-specific transcription factor binding sites compared with the other MyHC genes. These features are likely to be critical to the unique regulation and tissue-specific expression of the MyHC-EO/IIL gene.
Phylogenetic analysis indicates that MyHC-EO/IIL diverged from an ancestral MyHC gene to generate the first specialized fast myosin. The catalytic S1 head domain is more closely related to the fast MyHCs, while the rod is more closely related to the slow/cardiac MyHCs. The exon boundaries of the MyHC-EO are identical to those of the embryonic MyHC gene and virtually identical to those of the α and β cardiac genes. This implies that most of the current exon boundaries were present in the ancestral gene, predating the duplications that generated the family of skeletal and cardiac myosin genes.
Evidence of a Guanylyl Cyclase Natriuretic Peptide Receptor in the Gills Of the New Zealand Hagfish Eptatretus Cirrhatus (Class Agnatha)
Authors: Callahan Will , Forster Malcolm , Toop Tes 
Published: April 2021

ABSTRACT
Natriuretic peptide binding sites were examined in the gills of the hagfish Eptatretus cirrhatus (Class Agnatha, subfamily Eptatretinae) using radio-ligand binding techniques, molecular cloning and guanylyl cyclase assays. Iodinated rat atrial natriuretic peptide (125 I-rANP) and iodinated porcine C-type natriuretic peptide (125 I-pCNP) bound specifically to the lamellar folds and cavernous tissue of E. cirrhatus gills, and 0.3 nmol l−1 rat ANP competed for 50 % of specific 125 I-rANP binding sites. Affinity cross-linking of 125 I-rANP to gill membranes followed by sodium dodecylsulphate–polyacrylamide gel electrophoresis revealed a single binding site of 150 kDa. In the presence of Mn2+, 0.1 nmol l−1 rANP inhibited cGMP production, whereas 1 μmol l−1 rANP stimulated cGMP production rates. At 1 μmol l−1, pCNP also stimulated cGMP production. The production of cGMP was also measured in the presence and absence of ATP with either Mn2+ or Mg2+.
Reverse transcriptase polymerase chain reaction (RT-PCR) of hagfish gill RNA, followed by cloning and sequencing of PCR products, produced a partial cDNA sequence of a natriuretic peptide guanylyl cyclase receptor. The deduced amino acid sequence indicated 87–91 % homology with other natriuretic peptide guanylyl cyclase receptors. This study indicates the presence of a natriuretic peptide guanylyl cyclase receptor in the gills of E. cirrhatus that is similar to the natriuretic peptide guanylyl cyclase receptors in higher vertebrates. These observations demonstrate that the coupling of natriuretic peptide receptors with guanylyl cyclase has a long evolutionary history.
Early Thermal Experience has Different Effects on Growth and Muscle Fibre Recruitment in Spring- and Autumn-Running Atlantic Salmon Populations
Authors: Johnston Ian A. , Mclay H. Anne , Abercromby Marguerite , Robins Duncan 
Published: April 2021

ABSTRACT
The consequence of early thermal experience for subsequent growth patterns was investigated in Atlantic salmon (Salmo salar L.). Spring- and autumn-running salmon were caught in upland (Baddoch) and lowland (Sheeoch) tributaries of the River Dee, Aberdeenshire, Scotland, respectively, on the final stages of their spawning migrations. The eggs were incubated at the simulated natural temperature regime of each stream, which was on average 2.8 °C lower for the Baddoch. The offspring, representing 11 families per population, were transferred at first feeding to constant environmental conditions (12–14 °C; 16 h:8 h light:dark photoperiod) and reared in replicate tanks. Salmon of both populations were longer and heavier at 6 and 12 weeks in fish initially reared under the cooler Baddoch regime. Length frequency distributions became bimodal after 18 weeks, and only the upper growth mode was studied. Modelling of length distributions at 40 weeks revealed significantly different patterns of muscle growth according to initial temperature regime, but only for the Sheeoch salmon. In fish of Sheeoch origin, significantly more white muscle fibres were recruited per mm2 increase in myotomal cross-sectional area at Sheeoch than at Baddoch temperatures (P&lt;0.01). After 40 weeks, the density of white fibres was 10.4 % higher in fish initially reared at the Sheeoch (533±6 mm−2 ) than at the Baddoch (483±5 mm−2 ) thermal regimes (means ± S.E.M., 16 fish per group; P&lt;0.001). Muscle satellite cells were identified using an antibody to c-met. At 24 weeks, the density of muscle satellite cells was 29 % higher in Sheeoch salmon reared to first feeding at the temperature of their natal stream than at cooler Baddoch temperatures (P&lt;0.01). In contrast, the number and size distributions of white muscle fibres in the myotomes of Baddoch salmon were independent of early thermal experience.