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1
Hochstrate, P., e K. Hamdorf. "Microvillar components of light adaptation in blowflies." Journal of General Physiology 95, n. 5 (1 maggio 1990): 891–910. http://dx.doi.org/10.1085/jgp.95.5.891.
Testo completoAbstract (sommario):
The process of light adaptation in blowfly photoreceptors was analyzed using intracellular recording techniques and double and triple flash stimuli. Adapting flashes of increasing intensity caused a progressive reduction in the excitability of the photoreceptors, which became temporarily suppressed when 3 x 10(6) quanta were absorbed by the cell. This suppression was confirmed by subsequently applying an intense test flash that photoactivated a considerable fraction of the 10(8) visual pigment molecules in the cell. The period of temporary desensitization is referred to as the refractory period. The stimulus intensity to render the receptor cell refractory was found to be independent of the extracellular calcium concentration over a range of 10(-4) and 10(-2) M. During the refractory period (30-40 ms after the adapting flash) the cell appears to be "protected" against further light adaptation since light absorption during this period did not affect the recovery of the cell's excitability. Calculations showed that the number of quantum absorptions necessary to induce receptor refractoriness is just sufficient to photoactivate every microvillus of the rhabdomere. This coincidence led to the hypothesis that the refractoriness of the receptor cells is due to the refractoriness of the individual microvilli. The sensitivity of the receptor cells after relatively weak adapting flashes was reduced considerably more than could be accounted for by the microvilli becoming refractory. A quantitative analysis of these results suggests that a photoactivated microvillus induces a local adaptation over a relatively small area of the rhabdomere around it, which includes several tens of microvilli. After light adaptation with an intense flash, photoactivation of every microvillus by the absorption of a few quanta produced only a small receptor response whereas photoactivation of every rhodopsin molecule in every microvillus produced the maximum response. The excitatory efficiency of the microvilli therefore increases with the number of quanta that are absorbed simultaneously.
2
Komo, Larissa, e Damien Charabidze. "Balance between larval and pupal development time in carrion blowflies". Journal of Insect Physiology 133 (agosto 2021): 104292. http://dx.doi.org/10.1016/j.jinsphys.2021.104292.
Testo completo
3
Fukushi, Tsukasa. "Visual learning in walking blowflies,Lucilia cuprina". Journal of Comparative Physiology A 157, n. 6 (novembre 1985): 771–78. http://dx.doi.org/10.1007/bf01350074.
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4
Campbell, H. R. "Orientation discrimination independent of retinal matching by blowflies". Journal of Experimental Biology 204, n. 1 (1 gennaio 2001): 15–23. http://dx.doi.org/10.1242/jeb.204.1.15.
Testo completoAbstract (sommario):
Blowflies, Phaenicia sericata, can be trained to discriminate in a learning paradigm in which one of the two visual cues is positively rewarded. Retinotopic matching of a learned visual image to the same retinal location from viewing to viewing has been hypothesized to underlie visual pattern learning and memory in insects. To address the theory of retinotopic matching, a detailed analysis was made of the flies' body orientations during learned discriminations between +45 degrees and −45 degrees gratings. Initial approaches to the positive rewarded visual cue did not originate from the same spatial location within the behavioral arena with respect to the visual cues; thus, individual flies approached the positive cue from a different vantage point from trial to trial. During initial approaches to the rewarded visual cue, the distributions of body angles with respect to the cue were different from trial to trial for each individual. These data suggest that Phaenicia sericata can learn a visual pattern with one eye region and later recognize the same pattern with another eye region. Thus, retinotopic matching is not necessary for the recognition of pattern orientation in the experimental paradigm used here. The average amount of head turning in the yaw plane was too small to compensate for the changes in body orientation exhibited by the flies. Flies view the visual patterns with distinct retinal regions from trial to trial during orientation discrimination.
5
Blaj, G., e J. H. van Hateren. "Saccadic head and thorax movements in freely walking blowflies". Journal of Comparative Physiology A 190, n. 11 (20 luglio 2004): 861–68. http://dx.doi.org/10.1007/s00359-004-0541-4.
Testo completo
6
Liscia, A. "Taste Modulators are Tools to Gain a Better Insight into Specific Sensitivity of Chemoreceptors in Blowflies". Chemical Senses 30, Supplement 1 (1 gennaio 2005): i279—i280. http://dx.doi.org/10.1093/chemse/bjh223.
Testo completo
7
Park, K. C., e A. Cork. "Electrophysiological responses of antennal receptor neurons in female Australian sheep blowflies, Lucilia cuprina, to host odours". Journal of Insect Physiology 45, n. 1 (gennaio 1999): 85–91. http://dx.doi.org/10.1016/s0022-1910(98)00102-4.
Testo completo
8
Stavenga, D. G., P. B. W. Schwering e J. Tinbergen. "A THREE-COMPARTMENT MODEL DESCRIBING TEMPERATURE CHANGES IN TETHERED FLYING BLOWFLIES". Journal of Experimental Biology 185, n. 1 (1 dicembre 1993): 325–33. http://dx.doi.org/10.1242/jeb.185.1.325.
Testo completoAbstract (sommario):
A three-compartment model is presented that describes temperature measurements of tethered flying blowflies, obtained by thermal imaging. During rest, the body temperature is approximately equal to the ambient temperature. At the start of flight, the thorax temperature increases exponentially with a time constant of 30 s; in steady flight, a temperature of approximately 30°C is reached (ambient temperature approximately 25°C). After flight, the temperature of the thorax decreases exponentially with a time constant of 50 s. Fitting the time courses of the three body compartments, i.e. head, thorax and abdomen, with the model allows the thermal parameters to be calculated. The metabolic heat produced by a blowfly during tethered flight is estimated to be approximately 23 mW.
9
Ouyang, Qin, Hiroyasu Sato, Yoshihiro Murata, Atsushi Nakamura, Mamiko Ozaki e Tadashi Nakamura. "Contribution of the inositol 1,4,5-trisphosphate transduction cascade to the detection of “bitter” compounds in blowflies". Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology 153, n. 3 (luglio 2009): 309–16. http://dx.doi.org/10.1016/j.cbpa.2009.03.004.
Testo completo
10
Hainsworth, F. R., G. Fisher e E. Precup. "Rates of energy processing by blowflies: the uses for a joule vary with food quality and quantity". Journal of Experimental Biology 150, n. 1 (1 maggio 1990): 257–68. http://dx.doi.org/10.1242/jeb.150.1.257.
Testo completoAbstract (sommario):
Data on the variation of crop volumes with time for blowflies (Phormia regina Meigen) fed various volumes and concentrations of fructose or sucrose (from Gelperin, 1966, and Edgecomb et al. 1987) were used to characterize energy processing rates to test the assumption of food energy addivity of optimal foraging theories. Six regression models (linear, square root, cube root, hyperbolic, inverse cube root and exponential) were compared for data from Edgecomb et al. (1987) with measurements of crop volumes from 10 min to 5 h after blowflies were fed 9.7 or 14.5 microliters of 0.25 moll-1 sucrose. Only the hyperbolic regression could be discriminated as statistically different, and the linear model was selected as most parsimonious for examining rates of energy processing. About the same volume bypassed the crop for flies fed 9.7 or 14.5 microliters. Volume rates of crop emptying (from Gelperin, 1966) did not change at intermediate concentrations but decreased from lowest and to highest concentrations. Energy processing patterns indicate that long-term storage rates increase with meal size and at intermediate concentrations and decrease (3.0 moll-1 fructose) or remain constant (2.0 moll-1 sucrose) at high concentrations, so the uses for a unit of energy are not additive across concentrations and meal sizes. Animals that process energy in this way should attempt to maximize meal size and include high-energy foods in their diet out of proportion to the amount of energy gained for the time spent foraging.
11
Busse, F. K., e R. H. Barth. "Physiology of feeding-preference patterns of female black blowflies (Phormia regina Meigen): Modification in responsiveness to salts subsequent to salt feeding". Journal of Insect Physiology 31, n. 1 (gennaio 1985): 23–26. http://dx.doi.org/10.1016/0022-1910(85)90037-x.
Testo completo
12
EDGECOMB, ROBERT S., ANGELA R. PYLE e LARRY L. MURDOCK. "The Role of Water in Tarsal Taste Thresholds to Sugar in the Blowfly Phormia Regina". Journal of Experimental Biology 142, n. 1 (1 marzo 1989): 245–55. http://dx.doi.org/10.1242/jeb.142.1.245.
Testo completoAbstract (sommario):
Thirsty blowflies whose tarsi come into contact with water will respond with proboscis extension. When flies were exposed to high or low relative humidities (RH) prior to testing, the tarsal taste thresholds to sucrose in flies that were unresponsive to water alone increased or decreased, respectively. Evidently, thirst can also be subthreshold and recognizable only as a change in threshold to aqueous sucrose. Thresholds to sucrose and fructose, which were in the millimolar range in 3-day-old adult flies held at 55–70% RH prior to testing, fell significantly after the flies had been held at low humidity (13–20% RH) for several hours. There was no low-humidity-dependent drop in threshold with galactose or xylose, sugars to which flies normally have thresholds in the 102mmoll−1 range. Flies held at low relative humidity exhibited increased tarsal thresholds to sucrose when they were injected with water or were allowed to drink water adlibitum. When multiple injections of water were given, thresholds rose after successive injections. Changes in threshold to sucrose occurred after injection with aqueous NaCl, the direction and magnitude being dependent on the concentration injected. The threshold declined significantly after injection of 2 μ1 of 75 mmoll−1 NaCl, remained unchanged after injection of 150 or 300 mmoll−1 NaCl, and increased after injection of 600 mmoll−1 NaCl. Thirst in blowflies can affect thresholds to food stimuli. The changes in water content of the body resulting from a water-rich meal could contribute significantly to the normal post-meal rises in tarsal thresholds.
13
Boeddeker, N. "A single control system for smooth and saccade-like pursuit in blowflies". Journal of Experimental Biology 208, n. 8 (15 aprile 2005): 1563–72. http://dx.doi.org/10.1242/jeb.01558.
Testo completo
14
EDGECOMB, ROBERT S., LARRY L. MURDOCK, ANDRÉ B. SMITH e MARGARET D. STEPHEN. "Regulation of Tarsal Taste Threshold in the Blowfly, Phormia Regina". Journal of Experimental Biology 127, n. 1 (1 gennaio 1987): 79–94. http://dx.doi.org/10.1242/jeb.127.1.79.
Testo completoAbstract (sommario):
The nutritional condition of adult blowflies (Phormia regina Meigen) affects their readiness to respond with proboscis extension when their tarsi contact food stimuli. Thresholds are high in sated flies (100–1000 mmol−1 sucrose) and low in starved flies (1–10 mmoll−1 sucrose). Two feeding regimes employing aqueous sucrose were used to reveal factors regulating tarsal taste threshold in this insect: long-term feeding (ad libitum) and single meals administered to starved flies. A positive logarithmic relationship was found between crop weight and tarsal taste threshold, expressed as mean acceptance threshold, in flies fed aqueous sucrose ad libitum for 4 days. Threshold changes after a single meal were positively correlated to both concentration and volume of the sugar solution fed. Thresholds observed in flies fed a single meal were not as high as those in ad libitum-ied flies having the same crop volume. Nerve-transection experiments demonstrated that the median abdominal nerve plays no direct role in threshold regulation in either single-meal-fed or ad libitum-fed flies. Transection of the recurrent nerve (RN), however, significantly attenuated the post-feeding rise in tarsal threshold in starved flies fed a single meal and markedly reduced threshold in sated flies fed ad libitum. Thresholds for RN-transected flies subjected to either feeding regime were still significantly higher than thresholds for starved flies. Haemocoel-injected D-glucose did not significantly elevate threshold in starved flies. These observations establish that the RN plays an important role in the regulation of tarsal taste threshold in blowflies. The effect of the RN on threshold depends largely on the prior feeding activity of the flies. It appears, however, that other factors, in addition to the recurrent nerve, affect taste threshold after feeding.
15
El-Wadawi, R., e K. Bowler. "The development of thermotolerance protects blowfly flight muscle mitochondrial function from heat damage". Journal of Experimental Biology 198, n. 11 (1 novembre 1995): 2413–21. http://dx.doi.org/10.1242/jeb.198.11.2413.
Testo completoAbstract (sommario):
The LD50 of 10-day-old adult blowflies was determined to be 38.12±0.07 °C. A transitory increase in heat resistance occurred following the exposure of adult blowflies to a sublethal heat shock at 36 °C. This thermotolerance was apparent 1 h after the application of the shock, was maximal 2­3 h later and had disappeared 6 h after exposure. Oxidative phosphorylation by flight muscle mitochondria from control flies was impaired by an LD50 dose in vivo using both pyruvate+proline (P+P) and glycerol 3-phosphate (G3P) as substrates. Acceptor control (state III respiration/state IV respiration) was lost with G3P as substrate and so ADP:O ratios were not measurable. The effect of experimental temperature in vitro on respiratory performance of mitochondria isolated from control and thermotolerant flies was also determined between 19 and 39 °C. State III respiration was markedly temperature-dependent in mitochondria from control flies with both substrates; it was maximal at 24­29 °C and fell progressively at higher measuring temperatures. In mitochondria from thermotolerant flies, state III respiration was less temperature-dependent with both substrates but this was most marked for G3P. The effect of experimental temperature on state IV respiration was similar in mitochondria from control and thermotolerant flies with each substrate, but differed between the two substrates. With G3P as substrate, respiration rate rose with temperature with a Q10 of approximately 1.5; however, with P+P as substrate, the trend was for respiration rate to fall as experimental temperature rose. Using G3P as substrate, acceptor control was demonstrable at 34 °C in some preparations of mitochondria from thermotolerant flies but not in those from control flies at that temperature. With P+P as substrates, acceptor control was demonstrable in mitochondria from both control and thermotolerant flies at all experimental temperatures.
16
Liang, Pei, Roland Kern, Rafael Kurtz e Martin Egelhaaf. "Impact of visual motion adaptation on neural responses to objects and its dependence on the temporal characteristics of optic flow". Journal of Neurophysiology 105, n. 4 (aprile 2011): 1825–34. http://dx.doi.org/10.1152/jn.00359.2010.
Testo completoAbstract (sommario):
It is still unclear how sensory systems efficiently encode signals with statistics as experienced by animals in the real world and what role adaptation plays during normal behavior. Therefore, we studied the performance of visual motion-sensitive neurons of blowflies, the horizontal system neurons, with optic flow that was reconstructed from the head trajectories of semi-free-flying flies. To test how motion adaptation is affected by optic flow dynamics, we manipulated the seminatural optic flow by targeted modifications of the flight trajectories and assessed to what extent neuronal responses to an object located close to the flight trajectory depend on adaptation dynamics. For all types of adapting optic flow object-induced response increments were stronger in the adapted compared with the nonadapted state. Adaptation with optic flow characterized by the typical alternation between translational and rotational segments produced this effect but also adaptation with optic flow that lacked these distinguishing features and even pure rotation at a constant angular velocity. The enhancement of object-induced response increments had a direction-selective component because preferred-direction rotation and natural optic flow were more efficient adaptors than null-direction rotation. These results indicate that natural dynamics of optic flow is not a basic requirement to adapt neurons in a specific, presumably functionally beneficial way. Our findings are discussed in the light of adaptation mechanisms proposed on the basis of experiments previously done with conventional experimenter-defined stimuli.
17
Warzecha, A., W. Horstmann e M. Egelhaaf. "Temperature-dependence of neuronal performance in the motion pathway of the blowfly calliphora erythrocephala". Journal of Experimental Biology 202, n. 22 (15 novembre 1999): 3161–70. http://dx.doi.org/10.1242/jeb.202.22.3161.
Testo completoAbstract (sommario):
Raising the head temperature within a behaviourally relevant range has strong effects on the performance of an identified neuron, the H1 neuron, in the visual motion pathway of blowflies. The effect is seen as an increase in the mean amplitude of the responses to motion under both transient and steady-state conditions, a considerable decrease in the response latency and an improvement in the reliability of the responses to motion. These temperature-dependent effects are independent of whether the animal is exposed to transient temperature changes or is maintained continuously at the same temperature for its entire life. The changes in the neuronal response properties with temperature may be of immediate functional significance for the animal under its normal operating conditions. In particular, the decrease in latency and the improvement in the reliability with increasing temperature may be relevant for the fly when executing its extremely virtuosic flight manoeuvres.
18
Campbell, H. R., e N. J. Strausfeld. "Learned discrimination of pattern orientation in walking flies". Journal of Experimental Biology 204, n. 1 (1 gennaio 2001): 1–14. http://dx.doi.org/10.1242/jeb.204.1.1.
Testo completoAbstract (sommario):
To determine the pattern-orientation discrimination ability of blowflies, Phaenicia sericata, a learning/memory assay was developed in which sucrose served as the reward stimulus and was paired with one of two visual gratings of different orientations. Individual, freely walking flies with clipped wings were trained to discriminate between pairs of visual patterns presented in the vertical plane. During training trials, individual flies learned to search preferentially at the rewarded stimulus. In subsequent testing trials, flies continued to exhibit a learned preference for the previously rewarded stimulus, demonstrating an ability to discriminate between the two visual cues. Flies learned to discriminate between horizontal and vertical gratings, +45 degrees (relative to a 0 degrees vertical) and −45 degrees gratings, and vertical and +5 degrees gratings. Individual patterns of learning and locomotive behavior were observed in the pattern of exploration during training trials. The features of the visual cue critical for discrimination of orientation are discussed.
19
Berrigan, D., e J. R. Lighton. "Bioenergetic and kinematic consequences of limblessness in larval Diptera". Journal of Experimental Biology 179, n. 1 (1 giugno 1993): 245–59. http://dx.doi.org/10.1242/jeb.179.1.245.
Testo completoAbstract (sommario):
We report the cost of transport and kinematics of terrestrial locomotion by larval blowflies (Protophormia terraenovae, Diptera: Calliphoridae). We contrast inter- and intra-individual methods for estimating minimum cost of transport (MCOT) and the relationship between speed, contraction frequency and distance traveled per contraction. The minimum cost of transport calculated from intra-individual data is 2297 +/− 317 J kg-1 m-1 (S.E.M.) and the MCOT calculated from inter-individual comparisons is statistically indistinguishable at 1910 +/− 327 J kg-1 m-1. These values are almost ten times higher than the predicted value for a similar-sized limbed arthropod. Fly larvae travel by repeated peristaltic contractions and individual contractions cost about the same amount as individual strides in limbed insects. Both contraction frequency and distance traveled per contraction increase linearly with speed. Doubling the contraction frequency or the distance traveled per contraction approximately doubles speed. The cost of transport in fly larvae is among the highest recorded for terrestrial locomotion, confirming the suggestion that biomechanical and kinematic properties of limbless organisms with hydraulic skeletons lead to very high costs of transport.
20
Meglič, Andrej, e Gregor Zupančič. "Changes in redox states of respiratory pigments recorded from the eyes of live blowflies exposed to light stimuli and hypoxia". Journal of Comparative Physiology A 197, n. 3 (1 dicembre 2010): 301–10. http://dx.doi.org/10.1007/s00359-010-0612-7.
Testo completo
21
Hateren, J. H., e C. Schilstra. "Blowfly flight and optic flow. II. Head movements during flight". Journal of Experimental Biology 202, n. 11 (1 giugno 1999): 1491–500. http://dx.doi.org/10.1242/jeb.202.11.1491.
Testo completoAbstract (sommario):
The position and orientation of the thorax and head of flying blowflies (Calliphora vicina) were measured using small sensor coils mounted on the thorax and head. During flight, roll movements of the thorax are compensated by counter rolls of the head relative to the thorax. The yaw turns of the thorax (thorax saccades) are accompanied by faster saccades of the head, starting later and finishing earlier than the thorax saccades. Blowfly flight can be divided into two sets of episodes: ‘during saccades’, when high angular velocities of up to a few thousand degrees per second are reached by both the thorax and head, and ‘between saccades’, when the orientation of the thorax and, in particular, the head is well stabilized. Between saccades, the angular velocities of the head are approximately half those of the thorax and lie mostly in the range 0–100 degrees s-1 for any rotation (yaw, pitch and roll). These velocities are low enough to limit the visual blur attributable to rotation. It is argued that the split into periods during which either rotational optic flow (‘during saccades’) or translatory optic flow (‘between saccades’) dominates is helpful for processing optic flow when signals and neurons are noisy.
22
Simmons, P., S. Jian e F. Rind. "CHARACTERISATION OF LARGE SECOND-ORDER OCELLAR NEURONES OF THE BLOWFLY CALLIPHORA ERYTHROCEPHALA". Journal of Experimental Biology 191, n. 1 (1 giugno 1994): 231–45. http://dx.doi.org/10.1242/jeb.191.1.231.
Testo completoAbstract (sommario):
1. Blowflies have twelve large, second-order ocellar neurones (L-neurones) with axons in the single ocellar nerve. These neurones have fairly restricted arborizations in the posterior slope neuropile of the protocerebrum and cell bodies in the nerve, near to the fused ocellar retinae. 2. Like ocellar L-neurones of other insects, or large second-order neurones of the fly compound eye, blowfly L-neurones hyperpolarise in response to increases in light intensity and depolarise in response to decreases in light intensity. Both polarities of response have a strong phasic component. Adaptation to sustained illumination shifts the intensity­response curve, with little change in its gradient. 3. The maximum responses of blowfly L-neurones to sinusoidal changes in light intensity occur at stimulus frequencies of 5­10 Hz. 4. Hyperpolarising an L-neurone with small currents causes an increase in input resistance. Larger hyperpolarising currents cause oscillations in the membrane potential. The amplitude of the oscillations increases with current strength. Repolarisation generates brief rebound spikes of variable amplitude. 5. Injection of small hyperpolarising currents increases the amplitude of a response to a subsaturating pulse of light. This effect is not seen for saturating responses to light and is likely to be due to the increase in membrane resistance caused by hyperpolarisation.
23
Lent, C. M., e M. H. Dickinson. "On the termination of ingestive behaviour by the medicinal leech". Journal of Experimental Biology 131, n. 1 (1 settembre 1987): 1–15. http://dx.doi.org/10.1242/jeb.131.1.1.
Testo completoAbstract (sommario):
Hungry leeches, Hirudo medicinalis, ingest blood meals averaging 890% of their mass in 29 min. Ingestion is terminated as a result of distension of the body: experimentally distending leeches as they feed causes an immediate cessation of ingestion and inhibits any subsequent biting behaviour; if distension is circumvented by various experimental procedures, leech ingestive periods are prolonged significantly. Ingestion is not terminated as a result of fatigue, chemical cues or mass change. Distension also underlies satiation, for removing blood from the crops of recently fed leeches qualitatively alters their satiated behaviour to biting. Biting is not a defensive reaction to injury. In rostral ganglia, impulses of the serotonergic Retzius (RZ) and LL neurones evoke the physiological components of ingestion. Localized warming of the prostomial lip induces impulses in these large effector neurones. Distending the body wall tonically hyperpolarizes the RZ and LL cells. This inhibitory response to distension is conducted from the mid-body to the anterior neurones via the ventral nerve cord. Distensive inhibition antagonizes the synaptic excitation evoked in RZ and LL neurones by thermal stimulation. Thus, a stimulus which evokes feeding synaptically excites 5-HT neurones and a stimulus which terminates ingestion inhibits them. The integration of these inputs controls the expression of leech feeding behaviour and these connections match precisely a model proposed to regulate the ingestive behaviour of blowflies.
24
Warzecha, A. K., M. Egelhaaf e A. Borst. "Neural circuit tuning fly visual interneurons to motion of small objects. I. Dissection of the circuit by pharmacological and photoinactivation techniques". Journal of Neurophysiology 69, n. 2 (1 febbraio 1993): 329–39. http://dx.doi.org/10.1152/jn.1993.69.2.329.
Testo completoAbstract (sommario):
1. Visual interneurons tuned to the motion of small objects are found in many animal species and are assumed to be the neuronal basis of figure-ground discrimination by relative motion. A well-examined example is the FD1-cell in the third visual neuropil of blowflies. This cell type responds best to motion of small objects. Motion of extended patterns elicits only small responses. As a neuronal mechanism that leads to such a response characteristic, it was proposed that the FD1-cell is inhibited by the two presumably GABAergic and, thus, inhibitory CH-cells, the VCH- and the DCH-cell. The CH-cells respond best to exactly that type of motion by which the activity of the FD1-cell is reduced. The hypothesis that the CH-cells inhibit the FD1-cell and, thus, mediate its selectivity to small moving objects was tested by ablating the CH-cells either pharmacologically or by photoinactivation. 2. After application of the gamma-aminobutyric acid (GABA) antagonist picrotoxinin, the FD1-cell responds more strongly to large-field than to small-field motion, i.e., it has lost its small-field selectivity. This suggests that the tuning of the FD1-cell to small moving objects relies on a GABAergic mechanism and, thus, most likely on the CH-cells. 3. The role of each CH-cell for small-field tuning was determined by inactivating them individually. They were injected with a fluorescent dye and then ablated by laser illumination. Only photoinactivation of the VCH-cell eliminated the specific selectivity of the FD1-cell for small-field motion. Ablation of the DCH-cell did not significantly change the response characteristic of the FD1-cell. This reveals the important role of the VCH-cells in mediating the characteristic sensitivity of the FD1-cell to motion of small objects. 4. The FD1-cell is most sensitive to motion of small objects in the ventral part of the ipsilateral visual field, whereas motion in the dorsal part influences the cell only weakly. This specific feature fits well to the sensitivity of the VCH-cell to ipsilateral motion that is most pronounced in the ventral part of the visual field. The spatial sensitivity distribution of the FD1-cell matches also the characteristics of figure-ground discrimination and fixation behavior.
25
Schilstra, C., e J. H. Hateren. "Blowfly flight and optic flow. I. Thorax kinematics and flight dynamics". Journal of Experimental Biology 202, n. 11 (1 giugno 1999): 1481–90. http://dx.doi.org/10.1242/jeb.202.11.1481.
Testo completoAbstract (sommario):
The motion of the thorax of the blowfly Calliphora vicina was measured during cruising flight inside a cage measuring 40 cmx40 cmx40 cm. Sensor coils mounted on the thorax picked up externally generated magnetic fields and yielded measurements of the position and orientation of the thorax with a resolution of 1 ms, 0.3 degrees and 1 mm. Flight velocities inside the cage were up to 1.2 m s-1, and accelerations were up to 1 g (approximately 10 m s-2) vertically and 2 g horizontally. During flight, blowflies performed a series of short (approximately 20–30 ms) saccade-like turns at a rate of approximately 10 s-1. The saccades consisted of a succession of rotations around all axes, occurring in a fixed order. First, a roll was started. Second, the rolled thorax pitched (pulling the nose up) and yawed, resulting in a turn relative to the outside world. Finally, the thorax rolled back to a level position. Saccades had yaw amplitudes of up to 90 degrees, but 90 % were smaller than 50 degrees. Maximum angular velocities were 2000 degrees s-1, and maximum accelerations were 10(5) degrees s-2. The latter correspond to torques consistent with the maximal force (2×10(−3)N) that can be generated by the flight motor as inferred from the maximal linear acceleration. Furthermore, the sequence of energy investment in consecutive rotations around different axes appears to be optimized during a saccade.
26
Nässel, D. R., M. Y. Kim e C. T. Lundquist. "Several forms of callitachykinins are distributed in the central nervous system and intestine of the blowfly Calliphora vomitoria." Journal of Experimental Biology 198, n. 12 (1 dicembre 1995): 2527–36. http://dx.doi.org/10.1242/jeb.198.12.2527.
Testo completoAbstract (sommario):
We have examined the distribution of two tachykinin-related neuropeptides, callitachykinin I and II (CavTK-I and CavTK-II), isolated from whole-animal extracts of the blowfly Calliphora vomitoria. Extracts of dissected brains, thoracic-abdominal ganglia and midguts of adult blowflies and the entire central nervous system of larval flies were analysed by high performance liquid chromatography (HPLC) combined with enzyme-linked immunosorbent assay (ELISA) for the presence of CavTKs. To identify the two neuropeptides by HPLC, we used the retention times of synthetic CavTK-I and II as reference and detection with an antiserum raised to locustatachykinin II (shown here to recognise both CavTK-I and II). The brain contains only two immunoreactive components, and these have exactly the same retention times as CavTK-I and II. The thoracic-abdominal ganglia and midgut contain immunoreactive material eluting like CavTK-I and II as well as additional material eluting later. The larval central nervous system (CNS) contains material eluting like CavTK-I and II as well as a component that elutes earlier. We conclude that CavTK-I and II are present in all assayed tissues and that additional, hitherto uncharacterised, forms of tachykinin-immunoreactive material may be present in the body ganglia and midgut as well as in the larval CNS. An antiserum was raised to CavTK-II for immunocytochemistry. This antiserum, which was found to be specific for CavTK-II in ELISA, labelled all the neurones and midgut endocrine cells previously shown to react with the less selective locustatachykinin antisera. It is not clear, however, whether CavTK-I and II are colocalised in all LomTK-immunoreactive cells since there is no unambiguous probe for CavTK-I.
27
Beckers, Ulrich, Martin Egelhaaf e Rafael Kurtz. "Synapses in the Fly Motion–Vision Pathway: Evidence for a Broad Range of Signal Amplitudes and Dynamics". Journal of Neurophysiology 97, n. 3 (marzo 2007): 2032–41. http://dx.doi.org/10.1152/jn.01116.2006.
Testo completoAbstract (sommario):
Synapses are generally considered to operate efficiently only when their signaling range matches the spectrum of prevailing presynaptic signals in terms of both amplitudes and dynamics. However, the prerequisites for optimally matching the signaling ranges may differ between spike-mediated and graded synaptic transmission. This poses a problem for synapses that convey both graded and spike signals at the same time. We addressed this issue by tracing transmission systematically in vivo in the blowfly's visual-motion pathway by recording from single neurons that receive mixed potential signals consisting of rather slow graded fluctuations superimposed with highly variable spikes from a small number of presynaptic elements. Both pre- and postsynaptic neurons were previously shown to represent preferred-direction motion velocity reliably and linearly at low fluctuation frequencies. To selectively assess the performance of individual synapses and to precisely control presynaptic signals, we voltage clamped one of the presynaptic neurons. Results showed that synapses can effectively convey signals over a much larger amplitude and frequency range than is normally used during graded transmission of visual signals. An explanation for this unexpected finding might lie in the transmission of the spike component that reaches larger amplitudes and contains higher frequencies than graded signals.
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Yan, Liping, Thomas Pape, Karen Meusemann, Sujatha Narayanan Kutty, Rudolf Meier, Keith M. Bayless e Dong Zhang. "Monophyletic blowflies revealed by phylogenomics". BMC Biology 19, n. 1 (27 ottobre 2021). http://dx.doi.org/10.1186/s12915-021-01156-4.
Testo completoAbstract (sommario):
Abstract Background Blowflies are ubiquitous insects, often shiny and metallic, and the larvae of many species provide important ecosystem services (e.g., recycling carrion) and are used in forensics and debridement therapy. Yet, the taxon has repeatedly been recovered to be para- or polyphyletic, and the lack of a well-corroborated phylogeny has prevented a robust classification. Results We here resolve the relationships between the different blowfly subclades by including all recognized subfamilies in a phylogenomic analysis using 2221 single-copy nuclear protein-coding genes of Diptera. Maximum likelihood (ML), maximum parsimony (MP), and coalescent-based phylogeny reconstructions all support the same relationships for the full data set. Based on this backbone phylogeny, blowflies are redefined as the most inclusive monophylum within the superfamily Oestroidea not containing Mesembrinellidae, Mystacinobiidae, Oestridae, Polleniidae, Sarcophagidae, Tachinidae, and Ulurumyiidae. The constituent subfamilies are re-classified as Ameniinae (including the Helicoboscinae, syn. nov.), Bengaliinae, Calliphorinae (including Aphyssurinae, syn. nov., Melanomyinae, syn. nov., and Toxotarsinae, syn. nov.), Chrysomyinae, Luciliinae, Phumosiinae, Rhiniinae stat. rev., and Rhinophorinae stat. rev. Metallic coloration in the adult is shown to be widespread but does not emerge as the most likely ground plan feature. Conclusions Our study provides the first phylogeny of oestroid calyptrates including all blowfly subfamilies. This allows settling a long-lasting controversy in Diptera by redefining blowflies as a well-supported monophylum, and blowfly classification is adjusted accordingly. The archetypical blowfly trait of carrion-feeding maggots most likely evolved twice, and the metallic color may not belong to the blowfly ground plan.
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Stavenga, D. G., R. Kruizinga e H. L. Leertouwer. "Dioptrics of the facet lenses of male blowflies Calliphora and Chrysomyia". Journal of Comparative Physiology A 166, n. 3 (febbraio 1990). http://dx.doi.org/10.1007/bf00204809.
Testo completo
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Monteagudo, José, Martin Egelhaaf e Jens Peter Lindemann. "Random attention can explain apparent object choice behavior in free-walking blowflies". Journal of Experimental Biology, 29 marzo 2022. http://dx.doi.org/10.1242/jeb.243801.
Testo completoAbstract (sommario):
Flies are often observed to approach dark objects. To a naïve observer they seem to pay selective attention to one out of several objects although previous research identified as a possible underlying mechanism a reflex-like fixation behavior integrating responses to all objects. In a combination of behavioral experiments and computational modelling, we investigated the choice behavior of flies freely walking towards an arrangement of two objects placed at a variable distance from each other. The walking trajectories were oriented towards one of the objects much earlier than predicted by a simple reactive model. We show that object choice can be explained by a continuous control scheme in combination with a mechanism randomly responding to the position of each object according to a stochastic process. This may be viewed as a special form of an implicit attention-like mechanism, for which the model does not require an explicit decision mechanism or a memory for the drawn decision.
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Hickner, Paul V., Omprakash Mittapalli, Anjana Subramoniam, Agustin Sagel, Wes Watson, Maxwell J. Scott, Alex P. Arp, Adalberto A. Pérez de León e Zainulabeuddin Syed. "Physiological and molecular correlates of the screwworm fly attraction to wound and animal odors". Scientific Reports 10, n. 1 (27 novembre 2020). http://dx.doi.org/10.1038/s41598-020-77541-w.
Testo completoAbstract (sommario):
AbstractThe screwworm fly, Cochliomyia hominivorax (Coquerel), was successfully eradicated from the United States by the sterile insect technique (SIT). However, recent detection of these flies in the Florida Keys, and increased risk of introductions to the other areas warrant novel tools for management of the flies. Surveillance, a key component of screwworm control programs, utilizes traps baited with rotting liver or a blend of synthetic chemicals such as swormlure-4. In this work, we evaluated the olfactory physiology of the screwworm fly and compared it with the non-obligate ectoparasitic secondary screwworm flies, C. macellaria, that invade necrotic wound and feed on dead tissue. These two species occur in geographically overlapping regions. C. macellaria, along with other blowflies such as the exotic C. megacephala, greatly outnumber C. hominivorax in the existing monitoring traps. Olfactory responses to swormlure-4 constituents between sex and mating status (mated vs unmated) in both species were recorded and compared. Overall, responses measured by the antennograms offered insights into the comparative olfactory physiology of the two fly species. We also present detailed analyses of the antennal transcriptome by RNA-Sequencing that reveal significant differences between male and female screwworm flies. The differential expression patterns were confirmed by quantitative PCR. Taken together, this integrated study provides insights into the physiological and molecular correlates of the screwworm’s attraction to wounds, and identifies molecular targets that will aid in the development of odorant-based fly management strategies.
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Supple, Jack A., Léandre Varennes-Phillit, Dexter Gajjar-Reid, Uroš Cerkvenik, Gregor Belušič e Holger G. Krapp. "Generating spatiotemporal patterns of linearly polarised light at high frame rates for insect vision research". Journal of Experimental Biology, 16 giugno 2022. http://dx.doi.org/10.1242/jeb.244087.
Testo completoAbstract (sommario):
Polarisation vision is commonplace among invertebrates; however, most experiments focus on determining behavioural and/or neurophysiological responses to static polarised light sources rather than moving patterns of polarised light. To this end, we designed a polarisation stimulation device based on superimposing polarised and non-polarised images from two projectors, which can display moving patterns at frame rates exceeding invertebrate flicker fusion frequencies. A linear polariser fitted to one projector enables moving patterns of polarised light to be displayed, whilst the other projector contributes arbitrary intensities of non-polarised light to yield moving patterns with a defined polarisation and intensity contrast. To test the device, we measured receptive fields of polarisation sensitive Argynnis paphia butterfly photoreceptors for both non-polarised and polarised light. We then measured local motion sensitivities of the optic flow-sensitive lobula plate tangential cell H1 in Calliphora vicina blowflies under both polarised and non-polarised light, finding no polarisation sensitivity in this neuron.
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Thyselius, Malin, Yuri Ogawa, Richard Leibbrandt, Trevor J. Wardill, Paloma T. Gonzalez-Bellido e Karin Nordström. "Hoverfly (Eristalis tenax) pursuit of artificial targets". Journal of Experimental Biology, 25 gennaio 2023. http://dx.doi.org/10.1242/jeb.244895.
Testo completoAbstract (sommario):
The ability to visualize small moving objects is vital for the survival of many animals, as these could represent predators or prey. For example, predatory insects, including dragonflies, robber flies and killer flies, perform elegant, high-speed pursuits of both biological and artificial targets. Many non-predatory insects, including male hoverflies and blowflies, also pursue targets during territorial or courtship interactions. To date, most hoverfly pursuits were studied outdoors. To investigate naturalistic hoverfly (Eristalis tenax) pursuits under more controlled settings, we constructed an indoor arena that was large enough to encourage naturalistic behavior. We presented artificial beads of different sizes, moving at different speeds, and filmed pursuits with two cameras, allowing subsequent 3D reconstruction of the hoverfly and bead position as a function of time. We show that male E. tenax hoverflies are unlikely to use strict heuristic rules based on angular size or speed to determine when to start pursuit, at least in our indoor setting. We found that hoverflies pursued faster beads when the trajectory involved flying downwards towards the bead. Furthermore, we show that target pursuit behavior can be broken down into two stages. In the first stage the hoverfly attempts to rapidly decreases the distance to the target by intercepting it at high speed. During the second stage the hoverfly's forward speed is correlated with the speed of the bead, so that the hoverfly remains close, but without catching it. This may be similar to dragonfly shadowing behavior, previously coined ‘motion camouflage’.