bluuebunny/crossref_metadata_2025_split huggingface dataset:
Initial Recruitment of Anaerobic Metabolism During Sub-Maximal Swimming in Rainbow Trout (Oncorhynchus Mykiss)
Authors: Burgetz Ingrid J. , Rojas-Vargas Anibal , Hinch Scott G. , Randall David J. 
Published: April 2021

ABSTRACT
Lactate and phosphocreatine concentrations were monitored in the white muscle of rainbow trout Oncorhynchus mykiss following swimming at 70, 80 and 100 % of critical swimming speed (Ucrit) using 31P-nuclear magnetic resonance (NMR) spectroscopy. Lactate was detected following swimming at all speeds, but its concentration was greatest following swimming at 80 and 100 %Ucrit. Phosphocreatine stores were reduced following swimming at 70 and 80 %Ucrit, but were further depleted following swimming at 100 %Ucrit. Following swimming at 70 and 80 %Ucrit, lactate concentrations were higher in the rostral, relative to the caudal, musculature, whereas phosphocreatine stores were least depleted in the mid, relative to the rostral and caudal, musculature. There were no differences among muscle locations in concentrations of lactate and phosphocreatine following swimming to 100 %Ucrit. Our results indicate that anaerobic metabolism is required to support swimming at speeds equal to and greater than 70 %Ucrit. Estimates of the relative cost of anaerobic metabolism during sub-maximal swimming are presented for swimming at 70 %, 80 % and 100 %Ucrit, and the implications of these results to energy budgets are discussed.
Influence of Cycle Frequency, Muscle Strain and Muscle Length on work and Power Production of Rainbow Trout (Oncorhynchus Mykiss) Ventricular Muscle
Authors: Harwood Claire L. , Young Iain S. , Altringham John D. 
Published: April 2021

ABSTRACT
This study investigates the effects of cycle frequency, strain and length on work and power output of isolated rainbow trout (Oncorhynchus mykiss) ventricular preparations using the work loop technique. These effects are discussed in the context of the whole heart using analogies with heart rate, stroke volume and end-diastolic volume.
Power output was dependent on cycle frequency, increasing threefold beween 0.3 and 1.1 Hz. The frequency for maximum power output was approximately 1.1 Hz, corresponding to the frequency for maximum power in perfused heart experiments.
The length for maximum work production (Lopt) was found to be the same as the length for maximum isometric force production (Lmax). The decline in net work at lengths greater than Lopt/Lmax was attributed to an increase in passive work (the work done on an unstimulated muscle) or to hysteresis and to a large increase in lengthening work.
The strain yielding maximum work decreased with increasing frequency. This is discussed in the context of the decline in stroke volume observed at increased heart rates in vivo.
Muscle strain in intact hearts paced at 0.3 Hz was ±11.9 % (23.8 % peak to peak), a value similar to the optimum strain at 0.3 Hz in vitro (±12 %).
Cardiac Output as a Predictor of Metabolic Rate in Cod Gadus Morhua
Authors: Webber D. M. , Boutilier R. G. , Kerr S. R. 
Published: April 2021

ABSTRACT
Adult Atlantic cod (2 kg Gadus morhua) were fitted with Doppler ultrasonic flow-probes to measure ventral aortic outflow (i.e. cardiac output). The probes remained patent for upwards of 3 months, during which time detailed relationships between cardiac output (Q̇), heart rate (fH) and rate of oxygen consumption were determined as a function of swimming speed and temperature (5 °C and 10 °C).The rate of oxygen consumption increased linearly with Q̇ and exponentially with swimming speed. A verygood correlation was observed between and Q̇ (r2=0.86) compared with the correlation between and fH (r2=0.50 for all 10 °C data and r2=0.86 for all 5 °C data). However, the versus fH correlation gradually improved over approximately 1 week after surgery (r2=0.86). The relationship between and Q̇ was independent of temperature, while the relationship between and fH changed with temperature. Hence, calculating from Q̇ is simpler and does not require that temperature be recorded simultaneously. Variations in cardiac output were determined more by changes in stroke volume (Vs) than by fH; therefore, fH was a less reliable predictor of metabolic rate than was Q̇. Given that Q̇ can be used to estimate so faithfully, the advent of a cardiac output telemeter would enable robust estimates to be made of the activity metabolism of free-ranging fish in nature, thereby strengthening one of the weakest links in the bioenergetic models of fisheries biology.
Effects Of Nonylphenol And 17β-Oestradiol On Vitellogenin Synthesis, Testicular Structure And Cytology In Male Eelpout Zoarces Viviparus
Authors: Christiansen T. , Korsgaard B. , Jespersen Å. 
Published: April 2021

ABSTRACT
Nonylphenol has been found to be oestrogenic in fish and may influence the reproductive system of male fish. In the present study, the effects of low (10 µg g−1 week−1 ) and high (100 µg g−1 week−1 ) doses of nonylphenol and of 17β-oestradiol on the synthesis of vitellogenin and on testicular structure and cytology were investigated in male eelpout Zoarces viviparus during active spermatogenesis (May) and late spermatogenesis (June). Twenty-five days after injection, a significant dose-dependent increase in the plasma vitellogenin concentration, measured by enzyme-linked immunosorbent assay, was observed in the treated groups. A highly significant reduction in the gonadosomatic index was observed concomitant with the increase in the plasma vitellogenin concentration. Macroscopically, milt was observed to be present in the control fish, but was sparse or absent in the treated fish. Histological examination using light microscopy revealed severe effects of nonylphenol as well as of oestradiol treatment on testicular structure. Control fish had seminiferous lobules containing spermatogenic cysts and only a few spermatozoa (May) or had the walls of their seminiferous lobules lined with cuboidal Sertoli cells (June). In the treated fish, the seminiferous lobules were degenerated (May) or were filled with numerous spermatozoa and the Sertoli cells appeared very squamous (June). Electron microscopy revealed greater numbers of phagocytozed spermatozoa in these Sertoli cells. In rats, γ-glutamyl transpeptidase (γ-GTP) has been used as a specific marker of Sertoli cell function. In the present study, both nonylphenol and 17β-oestradiol treatment resulted in a reduction in the activity of this enzyme. The study provides evidence that nonylphenol is oestrogenic, as indicated by the large increase in vitellogenin synthesis, and that both nonylphenol and oestradiol have marked effects on the testicular structure and cytology of germ cells and Sertoli cells of male Z. viviparus.
Two Types of mRNA Encoding Myosin Regulatory Light Chain in Carp Fast Skeletal Muscle Differ in Their 3′ Non-Coding Regions and Expression Patterns Following Temperature Acclimation
Authors: Hirayama Yasushi , Kobiyama Atsushi , Ochiai Yoshihiro , Watabe Shugo 
Published: April 2021

ABSTRACT
cDNA clones encoding the myosin regulatory light chain (RLC) were isolated from a cDNA library prepared from fast skeletal muscle of the carp Cyprinus carpio L. Two types of cDNA clone encoding carp RLC were found with identical deduced amino acid sequences. The two mRNAs differed in the number of polyadenylation signals prior to the poly(A) tail in the 3′ non-coding region. The two mRNA species, with approximate sizes of 1.4 and 0.8 kilobases, were also observed in northern blot analysis. Carp were acclimated for a minimum of 5 weeks to either 10 °C or 30 °C (14 h:10 h light:dark photoperiod). The total levels of mRNA transcripts coding for the RLC and myosin heavy chain were, respectively, 3.3 and 3.9 times higher in cold-than in warm-acclimated fish. Differences in the levels of RLC in mRNA transcripts were largely due to the concentration of the 1.4 kilobase mRNA species.
Receptor Cell Habituation in the a1 Auditory Receptor of Four Noctuoid Moths
Authors: Coro Frank , Pérez Martha , Mora Emanuel , Boada Danilo , Conner William E. , Sanderford Mark V. , Avila Héctor 
Published: April 2021

ABSTRACT
Moths of both sexes of Empyreuma affinis (=pugione) and Syntomeida epilais (Arctiidae, Ctenuchinae), Maenas jussiae (Arctiidae, Arctiinae) and Spodoptera frugiperda (Noctuidae, Amphipyrinae) were studied. Spike activity in the A1 cell was recorded using a stainless-steel hook electrode from the tympanic nerve in the mesothorax. Acoustic stimuli consisting of 25 and 100 ms pulses at the best frequency for the species and at intensities that evoke A1 cell saturation response were used at repetition rates of 0.5 and 5 Hz for 100 ms stimuli, and between 2 and 20 Hz for 25 ms stimuli. Stimuli at a repetition rate corresponding to a duty cycle of 5 % (25 ms at 2 Hz and 100 ms at 0.5 Hz) did not evoke monotonic changes in the responses of the A1 cell. With 25 ms pulses, rates above 5 Hz evoked an exponential decrease in the number of spikes and an increase in the latency of the responses of all the 37 specimens tested. The response duration showed no apparent change with stimulus repetition rates even at the highest duty cycle used (50 %), i.e. 25 ms at 20 Hz and 100 ms at 5 Hz. The higher the rate of stimulus repetition, the more marked were the changes in the A1 cell responses. In 16 of 17 preparations from two species, habituation had no effect on the adaptation rate in each response, while in seven of eight specimens of another species, the adaptation rate decreased with stimulus repetition. These results, and those from another mechanoreceptor cell, indicate that receptor cell adaptation (changes evoked in the response by a stimulus of constant intensity) and habituation (changes in the responses due to stimulus repetition rate) are two distinctive phenomena. The A1 cell in its habituated state showed an increase in its response to incremental increases in stimulus intensity of 10 dB. This result supports the idea that receptor cell habituation does not seem to be due to fatigue, i.e. to a temporary loss of the ability to respond to stimulation induced in a sensory receptor by continued stimulation.
Structure and function of the vomeronasal organ
Authors: Døving Kjell B. , Trotier Didier 
Published: April 2021

ABSTRACT
Many animals use their vomeronasal organs to gain direct and specific contact with chemical cues released by congeners and in biological fluids. These cues provide information about the physiological status of the emitter and facilitate or regulate social interactions such as sexual relationships. The present review gives a short description of the discovery of the vomeronasal organ and the pivotal findings of Jacobson. The distribution of the organ and its anatomy in some vertebrates are described. The mechanisms for stimulus entry and egress are discussed, and the findings that led to the appreciation of the vomeronasal organ in mammals as a main chemosensory organ for pheromones mediating reproductive status and inducing sexual behaviour are reported. The anatomical, biochemical and functional properties of the receptor neurones are described.
The effect of respiratory pattern on water loss in desiccation-resistant Drosophila melanogaster
Authors: Williams Adrienne E. , Bradley Timothy J. 
Published: April 2021

ABSTRACT
We measured CO2 and H2O release from individual fruit flies from five populations of Drosophila melanogaster selected for resistance to desiccation (D flies). Our previous work found that these flies survive for an extended period in dry air, have an increase in the peak height and frequency of CO2 release, as measured by the standard error of a linear regression (SER) of CO2 release for the en. tire survival period, and have reduced water loss rates compared with their control or ancestor populations. In the present study, we examined the following respiratory characteristics: , the SER of CO2 release and the ratio of to in the D flies. Correlations between these characters were calculated in order to determine the effect of respiratory pattern on water loss. We found that, within the D flies, neither periodic release of CO2 nor an increased SER for CO2 release was associated with reduced water loss. In addition, an increased SER was positively correlated with both an increased water loss rate and a decreased survival time. Therefore, although selection for desiccation resistance leads to both an increased SER and a decreased rate of water loss in the D flies, the increased SER does not significantly reduce respiratory water loss.
Effects of food nutrient content, insect age and stage in the feeding cycle on the fmrfamide immunoreactivity of diffuse endocrine cells in the locust gut
Authors: Zudaire Enrique , Simpson Steve J. , Montuenga Luis M. 
Published: April 2021

ABSTRACT
We have studied the influence of variations in dietary protein and digestible carbohydrate content, of insect age and of time during the feeding cycle on the endocrine cells of the ampullar region of the midgut in the African migratory locust Locusta migratoria L. Morphometric analysis of FMRFamide-like immunoreactivity was used as an indirect measure of the amount of FMRFamide-related peptides (FaRPs) stored in the gut endocrine cells. There was a highly significant correlation between FaRP content and the nutritional quality of the food, measured relative to the concentrations and ratio of protein to digestible carbohydrate in a nutritionally optimal diet. The direction of the relationship between FaRP content and diet quality varied with age during the fifth stadium. On day 1, FaRP levels increased with the nutritional quality of the food, while on day 4 the opposite relationship was observed. Release of peptide was triggered by the onset of a meal during ad libitum feeding, with cell FaRP levels returning to premeal values within 15 min of the meal ending. The results also suggested that cell contents were released during food deprivation beyond the normal intermeal interval. Locusts switched for a single meal during ad libitum feeding on day 4 from a low-to a high-carbohydrate food did not respond by reducing endocrine cell FaRP content. Our results show a relationship between the diffuse gut endocrine system and feeding and nutrition in locusts. The ampullar endocrine cells are in three-way contact with the midgut luminal contents, with the primary urine from the Malpighian tubules and with the haemolymph. They are thus ideally positioned to play an integrative receptor-secretory function in the regulation of a variety of post-ingestive processes, such as enzyme secretion, absorption, gut motility or nutrient metabolism.
Steroid-regulated morphological plasticity in a set of identified peptidergic neurons in the moth Manduca sexta
Authors: McGraw Hillary F. , Prier Kevin R. S. , Wiley Jesse C. , Tublitz Nathan J. 
Published: April 2021

ABSTRACT
The lateral neurosecretory cells (LNCs) in the tobacco hornworm Manduca sexta undergo a switch in neurotransmitter phenotype during pupation. Concurrent with this change in function, the LNCs undergo a major morphological reorganization. This study characterizes the morphological change and its underlying cause. In the larva, the LNC has a very compact dendritic arborization in a small volume of neuropil ipsilateral to the cell soma. In the adult moth, the LNC arborization extends through a much larger volume of neuropil, including the contralateral side of the ganglion. Using both in vivo manipulations and a single-cell culture system, we show that this change in morphology is probably triggered by two pulses of the steroid hormone 20-hydroxyecdysone (20-HE): a small commitment peak and a larger prepupal pulse. These are the same two pulses of 20-HE as those previously shown jointly to cause the change in transmitter phenotype. This work, in conjunction with a previous study on the transmitter switch, documents the orchestration of major morphological and biochemical changes in a set of identified neurons by a single hormone.
Rostral–caudal variation in troponin T and parvalbumin correlates with differences in relaxation rates of cod axial muscle
Authors: Thys Tierney M. , Blank Jason M. , Schachat Fred H. 
Published: April 2021

ABSTRACT
Relaxation rate is an important determinant of axial muscle power production during the oscillatory contractions of undulatory locomotion. Recently, significant differences have been reported in the relaxation rates of rostral versus caudal white muscle fibers of the Atlantic cod Gadus morhua L. The present study investigates the biochemical correlates of this rostral–caudal physiological variation. Using denaturing gel electrophoresis, a series of fresh muscle samples from the dorsal epaxial muscle region was analyzed and several differences were detected. First, a gradual shift occurs in the expression of two troponin T isoforms along the length of the body. Second, rostral muscles were found to contain significantly greater amounts of parvalbumin than caudal muscles. Third, two soluble Ca2+-binding proteins, in addition to parvalbumin, were also detected in the rostral muscle samples yet were absent from the caudal samples. This suite of rostral–caudal variations provides a strong biochemical basis for regional differences in the relaxation rates of cod white muscle.
Immunolocalization of Na+/K+-ATPase in Branchial Epithelium of Chum Salmon Fry During Seawater and Freshwater Acclimation
Authors: Shikano Takahito , Fujio Yoshihisa 
Published: April 2021

ABSTRACT
Immunolocalization of the α-subunit of Na+/K+-ATPase was examined in the gill epithelium of chum salmon (Oncorhynchus keta) fry during acclimation to brackish water (25 ‰ salinity) and reintroduction to fresh water. In freshwater fish, strong immunoreactivity was associated with the large spherical cells located on the free surface of the primary lamellae, especially in those found at the base of the secondary lamellae, and with the large spherical cells located on the secondary lamellae.The large spherical cells located near the central venous sinus at the base of the secondary lamellae and in the interlamellar regions, however, showed little or no immunoreactivity. When freshwater fish were acclimated to brackish water, immunoreactivity developed in the large spherical cells near the central venous sinus concomitant with an increase in the hypo-osmoregulatory ability of the fish. In contrast, reintroduction from brackish water to fresh water caused the disappearance of the immunoreactivity in the large spherical cells near the central venous sinus and a reduction in hypo-osmoregulatory ability. During acclimation to brackish water and reintroduction to fresh water, the hypo-osmoregulatory ability of the fish did not correlate with the total number of large spherical cells located on the primary lamellae but was closely correlated with the number of large spherical cells showing strong immunoreactivity for Na+/K+-ATPase. We conjecture that these immunopositive large spherical cells are mature differentiated chloride cells, whereas the immunonegative large spherical cells are young developing chloride cells. The development of immunoreactivity for Na+/K+-ATPase in young chloride cells may be one of the most important factors in the development of hypo-osmoregulatory ability by chum salmon fry.
Na+ -dependent phosphate cotransporters: the NaPi protein families
Authors: Werner Andreas , Dehmelt Leif , Nalbant Perihan 
Published: April 2021

ABSTRACT
In vertebrates, the level of inorganic phosphate (Pi) is tightly balanced both inside the cell and in the whole organism. A number of different Na+ -dependent Pi cotransport systems involved in Pi homeostasis have been identified and characterized at the molecular level in the past 7 years. The transporters constitute three different protein families denoted NaPi-I, NaPi-II and NaPi-III. NaPi-I from the rabbit was the first member of this family to be cloned. However, it still resists efforts to unravel its physiological role and a clear-cut functional identity: is it a Cl− channel, a Na+ /Pi cotransporter, a regulator, or does it perform a combination of these functions? These questions provide a slight taste of the problems associated with orphan genes derived from sequencing projects. The members of the NaPi-II protein family are crucially involved in tightly controlled renal Pi excretion and, as recently discovered, intestinal Pi absorption. The expression and the cellular distribution of NaPi-II in the proximal tubular epithelium are affected by hormonal and metabolic factors known to influence extracellular fluid Pi homeostasis. Recently, the expression of NaPi-II has been demonstrated in osteoclasts and brain; however, the physiological roles of NaPi-II in these tissues remain to be established. The members of the third protein family, NaPi-III, have been identified on the basis of their function as viral receptors. The widespread expression of this family suggests that NaPi-III is involved in supplying the basic cellular metabolic needs for Pi.
Strategies for migration in the terrestrial christmas island red crab gecarcoidea natalis: intermittent versus continuous locomotion
Authors: Adamczewska Agnieszka M. , Morris Stephen 
Published: April 2021

ABSTRACT
The terrestrial red crab Gecarcoidea natalis undertakes an annual breeding migration and must sustain locomotion for prolonged periods. The migrating crabs must travel a specific distance in a fixed time and can either walk at a constant speed or walk faster for short periods and then pause to feed or rest. To simulate the potential differences between continuous and intermittent locomotion during the migration, red crabs were sampled after walking at a voluntary speed for 5 or 20 min without pausing or after 20 min of enforced walking intermittently at approximately twice that speed. The respiratory and metabolic status of the crabs was investigated during the different exercise regimes to assess which strategy might be more advantageous during the migration.
The gills and lungs appeared to function similarly in gas exchange, and the in the haemolymph was 8.2 kPa which fully saturated the haemocyanin with O2. The uptake of O2 by red crabs was diffusion-limited and the diffusion coefficient (Ldiff) varied from 0.53 in resting crabs to 0.8 post-exercise. Post-exercise, red crabs experienced a mixed respiratory/metabolic acidosis which was greatest (0.2 pH units) in crabs walking intermittently, i.e. at a higher speed. Haemolymph L- lactate concentrations peaked at 5 mmol l−1 immediately post-exercise in the intermittent exercise group, whereas after 20 min of continuous exercise haemolymph L-lactate continued to increase, reaching a maximum of 2.5 mmol l−1 at 1 h post-exercise. L-Lactate recovered slowly to basal levels within 5 h. The maximum rate of L- lactate clearance from the haemolymph was only 1.75 mmol l−1 h−1, and short pauses in exercise were insufficient for substantial L-lactate reoxidation. Exercise regimes in the laboratory were within the locomotor speeds determined for migrating red crabs, which overall have a mean walking speed close to their aerobic limit but periodically pause and also exceed this limit by three- to fourfold.