bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Putative Cortisol Receptor in The Rainbow Trout Erythrocyte: Stress Prevents Starvation-Induced Increases in Specific Binding of Cortisol
Authors: Pottinger T. G. , Brierley I. 
Published: April 2021

ABSTRACT
Binding sites for the steroid hormone cortisol, with characteristics typical of a steroid receptor, were detected in the rainbow trout (Oncorhynchus mykiss) erythrocyte. Binding of [3H]cortisol to a washed and purified erythrocyte suspension was saturable (Bmax=0.33±0.06 fmol per 2×106 cells; approximately 100±18 sites per cell; mean ± S.E.M., N=6), of high affinity (Kd=4.7±0.4 nmol l−1) and reversible in the presence of an excess of unlabelled ligand. Maximum levels of specific binding were observed within 60 min of the addition of [3H]cortisol at 4 °C and were stable for 2–3 h. Within 20 min of the addition of excess unlabelled ligand, 60 % of specifically bound [3H]cortisol had dissociated. Both dexamethasone and cortisol completely displaced specifically bound [3H]cortisol at 100-fold excess, whereas a 1000-fold excess of unlabelled cortisone, 11-ketotestosterone, oestradiol-17β, testosterone and 17α,20β-dihydroxy-4-pregnen-3-one failed to displace specifically bound [3H]cortisol completely. Specific binding sites for [3H]cortisol were located predominantly (92 %) within the cytosolic fraction of the erythrocyte, with a trace amount of specific binding (8 %) detectable in the membrane fraction. No specific binding of [3H]cortisol was apparent in the erythrocyte nuclear fraction. A 7 day period of confinement stress resulted in no significant change in the number of erythrocyte cortisol-binding sites in rainbow trout, although plasma cortisol levels were significantly elevated in the stressed fish. However, in control unconfined fish, there was a progressive and significant increase in the amount of specifically bound cortisol per cell during the course of the experiment (from 0.097±0.030 to 0.260±0.070 fmol per 2×106 cells). A similar result was obtained when the experiment was repeated for confirmation. In both experiments, food was withheld from control and confined fish because of the negative impact of stress on appetite. The possibility that the increase in the number of erythrocyte cortisol-binding sites was related to the withdrawal of food was tested by quantifying the amount of specifically bound cortisol in erythrocytes over a 14 day period in unstressed rainbow trout maintained on normal rations and in unstressed fish from which food was withheld. A significant increase in the amount of specifically bound cortisol was observed with time in the fasted fish (from 0.33±0.07 to 0.53±0.03 fmol per 2×106 cells). These data suggest that the abundance of erythrocyte cortisol-binding sites in trout is a function of nutritional status and that stress opposes a fasting-induced increase in the number of binding sites.
The Olfactory Memory of The Honeybee Apis Mellifera: III. Bilateral Sensory Input is Necessary for Induction and Expression of Olfactory Blocking
Authors: Thorn Robert S. , Smith Brian H. 
Published: April 2021

ABSTRACT
The associative learning phenomenon termed ‘blocking’ demonstrates that animals do not necessarily associate a conditioned stimulus (e.g. X) with reinforcement if X is coincident with a second conditioned stimulus (e.g. A) that had already been associated with the same reinforcement. Blocking therefore represents a tactic that animals can use to modulate associative learning in order to focus on the most predictive stimuli at the expense of novel ones. Using an olfactory blocking paradigm in the honeybee, we investigated the mechanistic basis for olfactory blocking. We show that removing input from one antenna eliminates the blocking of one odor by another. Since antennal sensory neurons only project to the ipsilateral antennal lobe in the honeybee, more central processing regions of the brain than the antennae must be crucial for establishing blocking. Further experiments show that this bilateral interaction between brain hemispheres is crucial during both the induction and the expression of blocking. This result implies that blocking involves an active inhibition of odor association and recall, and that this inhibition is mediated by a structure that spans both brain hemispheres. This interpretation is consistent with a role for identified bilateral modulatory neurons in the production of blocking.
Trafficking of Adoptively Transferred B Lymphocytes in B-Lymphocyte-Deficient Mice
Authors: Roth Rita , Mamula Mark J. 
Published: April 2021

ABSTRACT
Many studies have investigated the fate of adoptively transferred lymphocytes in recipient mice, although little is known of the sites where these transferred cells reside at particular time points. Using flow cytometry, we analyzed the trafficking pattern of adoptively transferred naive B cells into the lymphoid organs of syngeneic B-cell-deficient (μMT) mice. Within the first 24 h of transfer, the location of B cells was highly dependent on the mode of B-cell transfer. When B cells were injected subcutaneously into μMT mice, they showed a different trafficking pattern from cells administered into the peritoneal cavity or injected intravenously. After subcutaneous transfer into the thigh, the greatest number of B cells was detected in the popliteal lymph node nearest to the injection site, whereas the lowest number was detected in the axillary lymph node opposite to the injection side. Within the first 24 h of either intraperitoneal and intravenous injection, B cells were found in approximately equal numbers in the lymph nodes and the spleen. Two days later, the B-cell distribution in the lymphoid organs appeared to be independent of the mode of B-cell transfer. A transient decrease in the numbers of splenic and lymph node B cells occurred 9 days after B-cell transfer (a decrease from 70 to 87 %) prior to the outgrowth of B cells that occurs 21 days after transfer. These studies are useful for understanding the numbers of B cells that may be required in adoptive transfer studies and their potential cellular interactions at particular physiological sites based on the route of cell transfer.
Perireception in Olfaction: Molecular Mass Sieving by Aesthetasc Sensillar Cuticle Determines Odorant Access to Receptor Sites in the Caribbean Spiny Lobster Panulirus Argus
Authors: Derby Charles D. , Cate Holly S. , Gentilcore Lisa R. 
Published: April 2021

ABSTRACT
The responsiveness of chemoreceptor neurons depends on a combination of perireceptor and receptor events. Olfactory neurons of crustaceans are packaged into distinctive cuticular sensilla called aesthetascs. The cuticle of aesthetascs is thin and permeable, even though it does not contain any obvious surface pores or pore tubules. This suggests that this ‘spongy’ aesthetasc cuticle may act as a molecular sieve that restricts large odorant molecules from entering the sensilla and binding to the olfactory neurons. We examined whether this is so for the aesthetasc cuticle of the Caribbean spiny lobster Panulirus argus. We used a chromatographic column packed with aesthetasc cuticle and connected to a flow-through ultraviolet spectrophotometer to measure the elution times of ultraviolet-absorbent molecular mass markers between 165 and 2×106 Da. Molecules larger than approximately 8.5 kDa had similar elution times, indicating that they did not penetrate the cuticle. Molecules smaller than 8.5 kDa had longer elution times that were directly and inversely proportional to their molecular mass. These results suggest that aesthetasc cuticle excludes molecules larger than 8.5 kDa from having access to the olfactory receptor neurons. We conclude that the molecular sieving capacity of the aesthetasc cuticle of P. argus is a perireceptor mechanism that is a critical determinant of the types of molecules capable of stimulating its olfactory receptors.
Heart Rates of Northern Elephant Seals Diving at Sea and Resting on the Beach
Authors: Andrews R. D. , Jones D. R. , Williams J. D. , Thorson P. H. , Oliver G. W. , Costa D. P. , Boeuf B. J. Le 
Published: April 2021

ABSTRACT
Heart rates of northern elephant seals diving at sea and during apnoea on land were monitored to test whether a cardiac response to submergence is an important factor in their ability to make repetitive, long-duration dives. Seven juvenile northern elephant seals were captured at Año Nuevo, CA, instrumented and translocated to release sites around Monterey Bay. Heart rate and dive depth were recorded using custom-designed data loggers and analogue tape monitors during the seals’ return to Año Nuevo. Heart rates during apnoea and eupnoea were recorded from four of the seals after they hauled out on the beach. Diving patterns were very similar to those of naturally migrating juveniles. The heart rate response to apnoea at sea and on land was a prompt bradycardia, but only at sea was there an anticipatory tachycardia before breathing commenced. Heart rate at sea declined by 64 % from the surface rate of 107±3 beats min−1 (mean ± S.D.), while heart rate on land declined by 31 % from the eupnoeic rate of 65±8 beats min−1. Diving heart rate was inversely related to dive duration in a non-linear fashion best described by a continuous, curvilinear model, while heart rate during apnoea on land was independent of the duration of apnoea. Occasionally, instantaneous heart rate fell as low as 3 beats min−1 during diving. Although bradycardia occurs in response to apnoea both at sea and on land, only at sea is heart rate apparently regulated to minimise eupnoeic time and to ration oxygen stores to ensure adequate supplies for the heart and brain not only as the dive progresses normally but also when a dive is abnormally extended.
The Direction of Celestial Rotation Influences the Development of Stellar Orientation in Young Garden Warblers (Sylvia Borin)
Authors: Weindler Peter , Baumetz Mathias , Wiltschko Wolfgang 
Published: April 2021

ABSTRACT
The study presented here was conducted in order to analyze the role of the direction of celestial rotation in the development of stellar orientation in young migratory birds. The test birds were garden warblers, Sylvla borin, which leave their breeding ground on a southwesterly compass course. The birds were hand-raised and, during the premigratory period, exposed to an artificial ‘sky’ in the local geomagnetic field. For the control group C, the star pattern was rotating in the natural direction, with the centre of rotation and magnetic North coinciding. For the three experimental groups, the star pattern was rotating in the opposite direction; for group E1, the centre of rotation coincided with magnetic North, for group E2 the centre of rotation was at magnetic West and for group E3 it was at magnetic East. During autumn migration, the birds were tested without magnetic information under the same, now stationary, sky. All four groups were able to use stellar information for orientation, but only the control group preferred the normal southwesterly course. The three experimental groups, in contrast, all oriented towards a significantly different direction, preferring due south. The results for group E1 showed less scatter than those for the other two experimental groups.
These results indicate that the direction of celestial rotation is crucial for the development of the normal migratory course with respect to the stars in young garden warblers. Establishing the species-specific southwesterly migratory course requires an interaction between celestial rotation and magnetic cues; this interaction appears to depend on the natural direction of celestial rotation. Rotation in the reverse direction allowed the birds to respond only in a manner that oriented them away from the centre of rotation.
Do Metabolic Responses to Solar Radiation Scale Directly with Intensity of Irradiance?
Authors: Walsberg Glenn E. , Tracy Randall L. , Hoffman Ty C. M. 
Published: April 2021

ABSTRACT
Endotherms exposed to air temperatures below thermal neutrality reduce their metabolic heat production when exposed to sunlight. The physiological effects of this additional source of heat gain from the environment usually are assumed to be proportional to the intensity of irradiance if other factors are held constant. We test this assumption by measuring changes in metabolic heat production produced by exposing a small mammal, the Siberian hamster (Phodopus sungorus) to four intensities of simulated solar radiation (0 W m−2, 317 W m−2, 634 W m−2 and 950 W m−2).
In the absence of solar radiation, metabolic heat production is inversely correlated with air temperature over the measured range of 3–27 °C. The respiratory quotient varies significantly with ambient temperature, indicating that the catabolic substrate and the thermal equivalent of oxygen consumed or carbon dioxide produced also vary with temperature. The depression of metabolic heat production resulting from exposure to simulated solar radiation is not simply a multiple of the intensity of irradiance. Rather, metabolic responses to higher levels of irradiance are blunted by 14–29 % compared with those expected on the basis of the response to less intense irradiance. Because changes in irradiance levels do not have simple linear effects upon the animal’s metabolic heat production, even in a simplified situation, significant errors may accumulate in biophysical analyses in which an animal’s responses to a restricted set of radiative conditions are measured and the results are extrapolated to a wider range observed in nature.
Honeydew Sugars and Osmoregulation in the Pea Aphid Acyrthosiphon Pisum
Authors: Wilkinson T. L. , Ashford D. A. , Pritchard J. , Douglas A. E. 
Published: April 2021

ABSTRACT
Pea aphids, Acyrthosiphon pisum, containing their symbiotic bacteria (untreated aphids) and experimentally deprived of their bacteria by treatment with the antibiotic rifampicin (antibiotic-treated aphids) were reared on the plant Vicia faba. The sugars in the honeydew produced by untreated aphids comprised predominantly the monosaccharides glucose and fructose, while the honeydew of antibiotic-treated aphids contained considerable amounts of oligosaccharides of up to 16 hexose units. The honeydew and haemolymph of the aphids were iso-osmotic, and their osmotic pressure was significantly lower in untreated aphids (0.91–0.95 MPa) than in antibiotic-treated aphids (1.01–1.05 MPa) (P&lt;0.05). For insects reared on chemically defined diets containing 0.15–1.0 mol l−1 sucrose (osmotic pressure 1.1–4.0 MPa), the osmotic pressure of the aphid haemolymph did not vary with dietary osmotic pressure, but was regulated to approximately 1.0 MPa in untreated and 1.3 MPa in antibiotic-treated aphids. The sugars in the aphid honeydew varied with dietary sucrose concentration; with monosaccharides dominant at low concentrations and oligosaccharides dominant at high concentrations of dietary sucrose. The lowest dietary sucrose concentration at which honeydew oligosaccharides were detected was 0.2 mol l−1 for the antibiotic-treated aphids and 0.3 mol l−1 for untreated aphids. These data indicate that the aphid, and not its associated microbiota, mediates the synthesis of oligosaccharides when the osmotic pressure of the ingesta is high.
Pilocarpine-Induced Motor Rhythms in the Isolated Locust Suboesophageal Ganglion
Authors: Rast Georg F. , Bräunig Peter 
Published: April 2021

ABSTRACT
Rhythmic activity was recorded from the mandibular motor nerves after treating isolated locust suboesophageal ganglia with the muscarinic agonist pilocarpine. The rhythmic motor pattern consisted of alternating bursts of activity in the antagonistic mandibular opener and closer motoneurones on each side and was synchronised in contralateral homologues. This pattern closely resembled the activity recorded from mandibular muscles in intact feeding locusts. The chewing frequency, however, was approximately three times higher in intact insects than the frequency of the motor pattern recorded from isolated ganglia. Serotonergic neurosecretory cells showed activity synchronous with the pilocarpine-evoked motor pattern. Similarly, rhythmic activity of the motoneurones innervating the two mandibular muscle receptor organs was synchronised with the mandibular motor pattern.
The Locust Dcmd, a Movement-Detecting Neurone Tightly Tuned to Collision Trajectories
Authors: Judge Sarah J. , Rind F. Claire 
Published: April 2021

ABSTRACT
A Silicon Graphics computer was used to challenge the locust descending contralateral movement detector (DCMD) neurone with images of approaching objects. The DCMD gave its strongest response, measured as either total spike number or spike frequency, to objects approaching on a direct collision course. Deviation in either a horizontal or vertical direction from a direct collision course resulted in a reduced response. The decline in the DCMD response with increasing deviation from a collision course was used as a measure of the tightness of DCMD tuning for collision trajectories. Tuning was defined as the half-width of the response when it had fallen to half its maximum level. The response tuning, measured as averaged mean spike number versus deviation away from a collision course, had a half-width at half-maximum response of 2.4 °–3.0 ° for a deviation in the horizontal direction and 3.0 ° for a deviation in the vertical direction. Mean peak spike frequency showed an even sharper tuning, with a half-width at half-maximum response of 1.8 ° for deviations away from a collision course in the horizontal plane.
Cold-Induced Angiogenesis in Seasonally Acclimatized Rainbow Trout (Oncorhynchus Mykiss)
Authors: Egginton Stuart , Cordiner Sandra 
Published: April 2021

ABSTRACT
Seasonal acclimatization of rainbow trout induced an inverse relationship between environmental temperature and the capillary:fibre ratio of slow locomotory muscle, which increased from 1.73±0.09 in the summer (18 °C) to 2.50±0.15 in the winter (4 °C). However, the rate of capillary growth (angiogenesis) was exceeded by that of fibre growth at low temperatures such that the extensive fibre hypertrophy found at 4 °C led to a decrease in capillary density, NA(c,f), to 57 % of that found at 11 °C and 85 % of that at 18 °C. Cold-induced angiogenesis resulted in an expanded capillary bed of similar topology to the existing network, with capillary orientation deviating from that of muscle fibres by only 4–7 %. Capillary length density was maximal at 11 °C, JV(c,f)=2421±239 mm-2, which as previously described corresponds to the point when muscle blood flow is highest and the scope for aerobic swimming is greatest, reflecting an integrated response to optimize aerobic performance at intermediate temperatures. In contrast, ventricular NA(c,f) parallels heart rate and hence was highest at 18 °C, while there was no seasonal variation in myocyte diameter. Although a systemic response to seasonal adjustments in humoral factors may occur, the data reported here suggest that angiogenesis is probably stimulated by different mechanical factors in these two muscles.
An Analysis of Clock-Shift Experiments: is Scatter Increased and Deflection Reduced in Clock-Shifted Homing Pigeons?
Authors: Chappell Jackie 
Published: April 2021

ABSTRACT
Clock-shifting (altering the phase of the internal clock) in homing pigeons leads to a deflection in the vanishing bearing of the clock-shifted group relative to controls. However, two unexplained phenomena are common in clock-shift experiments: the vanishing bearings of the clock-shifted group are often more scattered (with a shorter vector length) than those of the control group, and the deflection of the mean bearing of the clock-shifted group from that of the controls is often smaller than expected theoretically. Here, an analysis of 55 clock-shift experiments performed in four countries over 21 years is reported. The bearings of the clock-shifted groups were significantly more scattered than those of controls and less deflected than expected, but these effects were not significantly different at familiar and unfamiliar sites. The possible causes of the effects are discussed and evaluated with reference to this analysis and other experiments. The most likely causes appear to be conflict between the directions indicated by the sun compass and either unshifted familiar visual landmarks (at familiar sites only) or the unshifted magnetic compass (possible at both familiar and unfamiliar sites).
Lactate accumulation in the shell of the turtle Chrysemys picta bellii during anoxia at 3 °C and 10 °C
Authors: Jackson Donald C. 
Published: April 2021

ABSTRACT
Lactate concentrations were measured in the shell and plasma of the turtle Chrysemys picta bellii after 3 months of submergence anoxia at 3 °C and during and after 9 days of submergence anoxia at 10 °C. Liver and skeletal muscle lactate levels were also measured in control and anoxic animals at each temperature. At 3 °C, mean shell lactate concentration (N=4) reached 133 mmol kg−1 shell mass and plasma lactate levels were 144 mmol l−1; at 10 °C, shell and plasma lactate concentrations (N=5) rose in parallel during anoxic exposure, to 70.8 mmol kg−1 shell mass and 78.9 mmol l−1, respectively, and returned in parallel to control levels during 9 days of recovery. At the end of the anoxic periods, an estimated 44 % of the total body lactate resided in the shell at 3 °C and 43 % at 10 °C, and indirect evidence suggests that the shell buffered these same fractions of the acid load. Because of the high lactate concentration per kilogram of shell water (416 mmol kg−1 at 3 °C; 221 mmol kg−1 at 10 °C) and the known formation of calcium lactate complexes, it is postulated that most of the lactate existed in the shell in combined form. I conclude that sequestration of lactate within the shell represents a potentially major adaptation to anoxic acidosis for this animal and, together with the previously described release of shell carbonates, may account for up to two-thirds of the total lactic acid buffering in this animal.
Forewing asymmetries during auditory avoidance in flying locusts
Authors: Dawson Jeff W. , Dawson-Scully Ken , Robert Daniel , Robertson R. Meldrum 
Published: April 2021

ABSTRACT
Flying locusts orient to sounds in their environment. Sounds similar to those produced by echolocating bats cause a flying locust to change its flight path. We used high-speed cinematography and videography to study changes in body posture and wing kinematics of tethered locusts in response to stimulation with bat-like sounds. Locusts showed both negative and positive phonotaxis to this stimulus. Within a few wingbeats of stimulus onset (between 126 and 226 ms), locusts deflected their abdomens to one side, and the angle of the left and right forewings with respect to the dorsal–ventral body axis became asymmetrical during the downstroke. This forewing asymmetry, in which the forewing on the inside of the turn became more depressed, ranged from 20 to 45 ° (37±9.7 °, mean ± S.D.) and was correlated with the direction and magnitude of abdomen deflection, a measure of steering in tethered, flying locusts. Hindwing stroke angle asymmetries were minimal or non-existent after stimulation. Coincident with changes in forewing asymmetry and abdomen deflection was a decrease in stroke amplitude (19±6.5 °) of the forewing on the inside of the attempted turn. Motor patterns from forewing first basalar (M97) muscles showed an asymmetry in the timing of left and right depressor activation that ranged from 10.4 to 1.6 ms (4.23±2.85 ms). The number of spikes per depressor burst increased to a maximum of three spikes in the muscle on the inside of the attempted turn, and depressor frequency (wingbeat frequency) increased by approximately 2 Hz (2.17±0.26 Hz). We suggest that the asymmetry in forewing first basalar activity is causally related to the asymmetry in the timing of the initiation of the downstroke, resulting in an asymmetry in the ranges of the stroke angles of the forewings, which would impart a roll torque to the locust. This would augment the steering torques generated by concurrent changes in the angle of attack of the fore- and hindwings and changes in abdomen position to effect rapid avoidance manoeuvres.