Height control by free-flying Drosophila

ABSTRACT. In a horizontal wind tunnel, Drosophila flew at almost constant height along tracks up to 2 m long. The flies rose or sank only slowly when it was so dark that they no longer responded to movements of the tunnel floor, suggesting that their height control is mediated, at least partly, by responses to their movement relative to the air. In the light, the flies maintained height better than in the dark and were very responsive to movements around them. They faithfully followed the up and down movements of horizon screens at their sides whether they were flying in still air or against a wind, even in the presence of many other stationary visual cues. The flies did not respond by compensatory height changes to real vertical movements of a patterned horizontal disc beneath them, nor to changes in the size of the floor pattern. They did respond to horizontal acceleration of the floor pattern in the direction opposite to their flight (optically simulating a descent by the fly), by an apparently compensatory increase in height, but they also rose (instead of sinking) in response to floor acceleration in the direction of their flight. When the floor was accelerated in either direction they showed compensatory groundspeed-controlling responses. The increases in height might be alarm responses to sudden movements in the visual field beneath them. Both speed and height changing responses to floor movement were reduced when the number of stationary visual cues was increased. Drosophila thus control their height mainly by responses to the apparent movement of nearby visual cues at round about their own height.     

Competition between fixed and moving stripes in the control of orientation by flying Drosophila

ABSTRACT. The direction in which Drosophila hydei Sturtevant flew in response to the movement of a striped pattern beneath them was biased along a direction parallel to the long axis of a stationary stripe between them and the pattern. This was not due to the flies reacting to the movement of the ends of the stripes along the long edges of the stationary one, since a stationary stripe above the flies, not between them and the pattern, similarly biased their flight direction. It was due instead to an optomotor turning reaction induced by the edges of the stationary stripe as the flies were led towards or away from it by their turning and speed control reactions to the moving stripes.     

Uncoupler of Oxidative Phosphorylation Prolongs the Lifespan of <Emphasis Type="Italic">Drosophila</Emphasis>

The effect of a moderate ("soft") uncoupling of mitochondria on the lifespan and some parameters of biological age of Drosophila melanogaster strain Oregon was studied. Addition of the uncoupler 2,4-dinitrophenol (DNP) to the nutritional mixture of larvae significantly increased the average lifespan of the flies without changing their maximal lifespan. DNP significantly increased the rate of oxygen consumption by isolated mitochondria and tissue homogenates of the flies in state 4 (of Chance). DNP also decreased the activity of alcohol dehydrogenase (a parameter of flies' biological age) in the tissue homogenates, especially on octanol as the reaction substrate. However, being deprived of food the DNP-treated flies displayed a markedly decreased viability as compared to the control flies. On the whole, the results suggest that "soft" uncoupling of mitochondria may increase the lifespan.     

Active process mediates species-specific tuning of Drosophila ears

The courtship behavior of Drosophilid flies has served as a long-standing model for studying the bases of animal communication. During courtship, male flies flap their wings to send a complex pattern of airborne vibrations to the antennal ears of the females. These "courtship songs" differ in their spectrotemporal composition across species and are considered a crucial component of the flies' premating barrier. However, whether the species-specific differences in song structure are also reflected in the receivers of this communication system, i.e., the flies' antennal ears, has remained unexplored. Here we show for seven members of the melanogaster species group that (1) their ears are mechanically tuned to different best frequencies, (2) the ears' best frequencies correlate with high-frequency pulses of the conspecific courtship songs, and (3) the species-specific tuning relies on amplificatory mechanical feedback from the flies' auditory neurons. As a result of its level-dependent nature, the active mechanical feedback amplification is particularly useful for the detection of small stimuli, such as conspecific song pulses, and becomes negligible for sensing larger stimuli, such as the flies' own wingbeat during flight.     

The spontaneous change in the optokinetic reactivity in lizards]

The optokinetik reactivity of lizards (Calotes versicolor Daud., Agamidae, Squamata) varies spontaneously within seconds. The animals follow the sinusoidal movement of a striped cylinder with head and eyes. Thereby the line of sight may follow exactly the pattern movement without angular slippage, or a slippage of various degree happens, or the animal does even not react at all. The optokinetic reactivity varies continuously and not stepwise. Both eyes may move independently. Accelerated smooth eye movements which overtake the speed pattern movement were observed. In optokinetic reactions the eyes take the bigger part of the angular movement than the head; in cases of vestibular stimulation the reverse is observed concerning the amplitude of the compensatory countermovement. Similar effects of variable optokinetic reactivity in other animals and in man depending on attention are discussed.     

The fruit fly Drosophila melanogaster favors dim light and times its activity peaks to early dawn and late dusk

The light preferences of fruit flies were tested by 2 different means. First, flies were allowed to choose between different illuminations, and their favorite resting, grooming, and feeding places were determined with an infrared-sensitive camera. Second, the activity levels of the animals during their main daily activity period were determined photoelectrically (via infrared light beams) under different light intensities. Both methods revealed that the flies prefer dim light. They rested, groomed, and fed preferentially in places with a light intensity between 5 and 10 lux, and they showed the highest activity level when the light intensity during the day was kept at 10 lux. Furthermore, when dawn and dusk were simulated by logarithmically increasing/decreasing the light intensity during a 1.5-h interval, the flies' activity maxima occurred at about 7.5 lux during early dawn and late dusk. The results suggest that fruit flies time their clocks by early dawn and late dusk and avoid bright light during the day.     

Responses of Paramecium to Temperature Change

SYNOPSIS. The effect of temperature on the swimming velocity of Paramecium was investigated. When paramecia cultured at 25 C were transferred to various temperatures, their swimming velocity was increased immediately and then decreased exponentially with time to a new steady velocity. The relaxation time was about 1 min, independent of the new temperature. At a constant temperature the steady velocity was inversely proportional to viscosity. The velocity acceleration was observed when the sudden temperature change was larger than ± 1 C. Its magnitude became constant when the temperature change was greater than several degrees. The steady velocity as a function of temperature had a sharp maximum at the culture temperature and decreased on both sides of this temperature. Incubation of paramecia at 30 C for several hr after cultivation at 25 C shifted the maximum temperature of the steady velocity to 30 C. The temperature at which paramecia gathered in a temperature gradient cell correlated closely with the temperature of the maximum steady velocity.     

Do tsetse flies ‘see’ zebras? A field study of the visual response of tsetse to striped targets

Abstract A field study in Zimbabwe of Glossina pallidipes Austen and G. morsitans morsitans Westwood supported Waage's (1981) hypothesis that the striped pattern of zebras may protect them from being bitten by blood-sucking flies. In addition, the results suggest that the orientation of the stripes may be crucially important for the unattractiveness of zebras. The relative attractiveness of five different stationary targets (black, white, grey, vertically-striped and horizontally-striped; stripe width = 5 cm) were each tested on their own and in pairs of all combinations, with artificial host odour (CO₂ plus acetone) always present. Electric nets were used to catch flies as they attempted to land on or circle the targets. The results were similar for the two species of tsetse. When tested on their own, grey and vertically-striped targets caught similar numbers of flies and both caught significantly fewer than black or white targets (c. 36% as many). Horizontally-striped targets caught <10% as many flies as any other single target. Although there was no significant difference between the attractiveness of grey and vertically striped targets when they were presented together, when paired with the other targets, grey was as attractive as black or white, but the vertically-striped target was significantly less attractive than black or white (P < 0.001). In other words, a difference between grey and vertical stripes was found only in their attractiveness in relation to other targets. The horizontally-striped target, however, always caught the fewest flies, regardless of whether it was presented alone or alongside another target.     

Selection in the context of provocation in artificial populations of Drosophila melanogaster]

The experimental potentials of the method for selection against provocative background (autoselection) in artificial populations of Drosophila melanogaster were analysed. The dynamics of adaptation of Drosophila population under increasing NaCl concentration in food was studied. It appeared that selection was successful in case of feedback between the selection pressure, mediated by alteration of salt concentration, and the rate of flies adaptation determined by the intensity of their reproduction. Within a short period of time, as the result of autoselection, the flies' ability for development with NaCl of up to 8% concentration in food was registered. It was shown that this resistance of flies to the salt was inherited within twelve successive generations.     

Changes in the gaze fixation reaction in rhesus monkeys during the initial stage of water immersion

The gaze fixation reaction was studied in three rhesus monkeys before and during thermoneutral (34.5 degrees C) water immersion to the mid-chest level. The angular vestibulo-ocular reflex gain increased and the head angular velocity decreased significantly in all monkeys in 5 h after the start of immersion. Additionally, one animal was immersed to the neck level. Two hours in the condition of more pronounced support deprivation decreased significantly angular velocity of the head but not increased the angular vestibulo-ocular reflex gain. Therefore, support deprivation act upon the head movement control first.     

Light and temperature cooperate to regulate the circadian locomotor rhythm of wild type and period mutants of Drosophila melanogaster

In the wild type (Canton-S) and period mutant flies of Drosophila melanogaster, we examined the effects of light and temperature on the circadian locomotor rhythm. Under light dark cycles, the wild type and per(S) flies were diurnal at 25 degrees C. However, at 30 degrees C, the daytime activity commonly decreased to form a rather nocturnal pattern, and ultradian rhythms of a 2 approximately 4h period were observed more frequently than at 25 degrees C. The change in activity pattern was more clearly observed in per(0) flies, suggesting that these temperature dependent changes in activity pattern are mainly attributable to the system other than the circadian clock. In a 12h 30 degrees C:12h 25 degrees C temperature cycle (HTLT12:12), per(0) flies were active during the thermophase in constant darkness (DD) but during the cryophase in constant light (LL). The results of experiments with per(0);eya flies suggest that the compound eye is the main source of the photic information for this reversal. Wild type and per(0) flies were synchronized to HTLT12:12 both under LL and DD, while per(S) and per(L) flies were synchronized only in LL. This suggests that the circadian clock is entrainable to the temperature cycle, but the entrainability is reduced in the per(S) and per(L) flies to this particular thermoperiod length, and that temperature cycle forces the clock to move in LL, where the rhythm is believed to be stopped at constant temperature.     

Angular acceleration,compensatory head movements and the halteres of flies (Lucilia serricata)

Summary Tethered flies were subjected to accelerations about their vertical axes while flying or walking. These accelerations were applied either suddenly to stationary animals or continuously by oscillating the animal from side to side. Head and wing movements resulting from the imposed angular accelerations were photographed with a camera and a stroboscopic flash.Analysis of the photographs shows that the wing movements act to counter the imposed angular accelerations and that during sinusoidal oscillations about the vertical axis, head turns are in antiphase with angular acceleration.Head turns do not occur when the halteres are absent or present and not oscillating. When oscillating, the halteres detect high values of angular acceleration, outside the known capabilities of the visual movement detection system.     

Dynamic properties of neurons sensitive to visible movement in scarabaeid beetles (coleoptera scarabaeidae)

The responses of individual neurons of the optic lobe of beetles to moving light stimuli were studied. It was established that the reactions of neurons to the movement of a single light band in a preferred direction at a rate of 1–150 deg/sec are proportional to the logarithm of the angular velocity. The reactions to the movement of a striped pattern vary nonlinearly with the angular velocity. After an initial volley of discharges, the reaction to steady movement of the pattern drops more sharply than during a single movement of the band. When the pattern is stopped, an inhibitory pause occurs in the neuron's activity. The properties of the transitional processes can be explained by adaptation of local areas of the receptive field and by mutual inhibition between neuron systems sensitive to counter-oriented movements. The neurons which detect rotation of the optical environment have binocular receptive fields. The system for transmitting a turning command to the motor neurons has a time constant of 3–5 sec.Institute of Zoology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 3, No. 3, pp. 325–330, May–June, 1971.     

Walking deficits and centrophobism in an α‐synuclein fly model of Parkinson's disease

Parkinson's disease (PD) is a movement neurodegenerative disorder, characterized by bradykinesia, rigidity and tremor, constituting difficulties in walking and abnormal gait. Previous research shows that Drosophila expressing human α‐synuclein A30P (A30P) develop deficits in geotaxis climbing; however, geotaxis climbing is a different movement modality from walking. Whether A30P flies would exhibit abnormal walking in a horizontal plane, a measure more relevant to PD, is not known. In this study, we characterized A30P fly walking using a high‐speed camera and an automatic behavior tracking system. We found that old but not young A30P flies exhibited walking abnormalities, specifically decreased total moving distance, distance per movement, velocity, angular velocity and others, compared with old control flies. Those features match the definition of bradykinesia. Multivariate analysis further suggested a synergistic effect of aging and A30P, resulting in a distinct pattern of walking deficits, as seen in aged A30P flies. Psychiatric problems are common in PD patients with anxiety affecting 40–69% of patients. Central avoidance is one assessment of anxiety in various animal models. We found old but not young A30P flies exhibited increased centrophobism, suggesting possible elevated anxiety. Here, we report the first quantitative measures of walking qualities in a PD fly model and propose an alternative behavior paradigm for evaluating motor functions apart from climbing assay.     

The Temporal Structure of Vertical Arm Movements

The present study investigates how the CNS deals with the omnipresent force of gravity during arm motor planning. Previous studies have reported direction-dependent kinematic differences in the vertical plane; notably, acceleration duration was greater during a downward than an upward arm movement. Although the analysis of acceleration and deceleration phases has permitted to explore the integration of gravity force, further investigation is necessary to conclude whether feedforward or feedback control processes are at the origin of this incorporation. We considered that a more detailed analysis of the temporal features of vertical arm movements could provide additional information about gravity force integration into the motor planning. Eight subjects performed single joint vertical arm movements (45° rotation around the shoulder joint) in two opposite directions (upwards and downwards) and at three different speeds (slow, natural and fast). We calculated different parameters of hand acceleration profiles: movement duration (MD), duration to peak acceleration (D PA), duration from peak acceleration to peak velocity (D PA-PV), duration from peak velocity to peak deceleration (D PV-PD), duration from peak deceleration to the movement end (D PD-End), acceleration duration (AD), deceleration duration (DD), peak acceleration (PA), peak velocity (PV), and peak deceleration (PD). While movement durations and amplitudes were similar for upward and downward movements, the temporal structure of acceleration profiles differed between the two directions. More specifically, subjects performed upward movements faster than downward movements; these direction-dependent asymmetries appeared early in the movement (i.e., before PA) and lasted until the moment of PD. Additionally, PA and PV were greater for upward than downward movements. Movement speed also changed the temporal structure of acceleration profiles. The effect of speed and direction on the form of acceleration profiles is consistent with the premise that the CNS optimises motor commands with respect to both gravitational and inertial constraints.     

用红外方法对蝇翅视动行为的探索

本文报告了利用红外装置对蝇翅视动行为实验研究的初步结果及其分析:1.在红外探测器探测到的信号中找到了一个能反映蝇翅拍动幅度的参数.2.双侧、单侧刺激域的宽度及刺激域的高度对视动反应发生几率在一定范围内正相关,当超过一阈值(即饱和阈值)后,即出现稳定的视动反应,它们的饱和阈值分别为60°,30°,40°刺激条纹的亮度生有类似情况.刺激条纹的运动速度在一定范围内对视动反应无影响.3.当刺激没有达到饱和时,蝇翅出现断续的典型的视动反应,即“0-1波动反应”.4.单侧条纹由前向后运动时,蝇翅出现典型反应,而条纹从后向前运动时,不出现典型的视动反应或反应很弱.双侧刺激时,条纹向前运动几乎不诱发反应;条纹向后运动诱发明显的蝇翅视动反应,且蝇翅平面的方向在拍动过程中发生变化.     

ATP consumption and efficiency of human single muscle fibers with different myosin isoform composition

Chemomechanical transduction was studied in single fibers isolated from human skeletal muscle containing different myosin isoforms. Permeabilized fibers were activated by laser-pulse photolytic release of 1.5 mM ATP from p(3)-1-(2-nitrophenyl)ethylester of ATP. The ATP hydrolysis rate in the muscle fibers was determined with a fluorescently labeled phosphate-binding protein. The effects of varying load and shortening velocity during contraction were investigated. The myosin isoform composition was determined in each fiber by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. At 12 degrees C large variations (three- to fourfold) were found between slow and fast (2A and 2A-2B) fibers in their maximum shortening velocity, peak power output, velocity at which peak power is produced, isometric ATPase activity, and tension cost. Isometric tension was similar in all fiber groups. The ATP consumption rate increased during shortening in proportion to shortening velocity. At 12 degrees C the maximum efficiency was similar (0.21-0.27) for all fiber types and was reached at a higher speed of shortening for the faster fibers. In all fibers, peak efficiency increased to approximately 0.4 when the temperature was raised from 12 degrees C to 20 degrees C. The results were simulated with a kinetic scheme describing the ATPase cycle, in which the rate constant controlling ADP release is sensitive to the load on the muscle. The main difference between slow and fast fibers was reproduced by increasing the rate constant for the hydrolysis step, which was rate limiting at low loads. Simulation of the effect of increasing temperature required an increase in the force per cross-bridge and an acceleration of the rate constants in the reaction pathway.     

The mechanisms that enable arm motion to enhance vertical jump performance-a simulation study

The reasons why using the arms can increase standing vertical jump height are investigated by computer simulations. The human models consist of four/five segments connected by frictionless joints. The head-trunk-arms act as a fourth segment in the first model while the arms become a fifth segment in the second model. Planar model movement is actuated by joint torque generators. Each joint torque is the product of three variable functions of activation level, angular velocity dependence, and maximum isometric torque varying with joint angle. Simulations start from a balanced initial posture and end at jump takeoff. Jump height is maximized by finding the optimal combination of joint activation timings. Arm motion enhances jumping performance by increasing mass center height and vertical takeoff velocity. The former and latter contribute about 1/3 and 2/3 to the increased height, respectively. Durations in hip torque generation and ground contact period are lengthened by swinging the arms. Theories explaining the performance enhancement caused by arms are examined. The force transmission theory is questionable because shoulder joint force due to arm motion does not precisely reflect the change in vertical ground reaction force. The joint torque/work augmentation theory is acceptable only at the hips but not at the knees and ankles because only hip joint work is considerably increased. The pull/impart energy theory is also acceptable because shoulder joint work is responsible for about half of the additional energy created by arm swings.     

Effect of ontogenetic increases in body size on burst swimming performance in tadpoles of the striped marsh frog, Limnodynastes peronii

The effect of ontogenetic increases in total length on burst swimming performance was investigated in tadpoles of the striped marsh frog (Limnodynastes peronii) over the total-length range of 1. 5-4 cm and Gosner developmental stages 25-38. The burst swimming performance of tadpoles at 10 degrees and 24 degrees C was determined by videotaping startle responses with a high-speed video camera at 200 Hz and analysing the sequences frame by frame. Maximum swimming velocity (Umax) and acceleration (Amax) increased with total length (L) at a rate that was proportionally greater than the increase in total length (i.e., positive allometry; exponents >1) and was described by the allometric equations Umax=0.061L1.34 and Amax=1.15L1.11 at 10 degrees C and Umax=0.114L1.34 and Amax=1.54L1. 11 at 24 degrees C. Stride length increased with a total-length exponent of approximately 1 but was unaffected by temperature. Tail-beat frequency was not affected by total length and increased from 7.8+/-0.2 Hz at 10 degrees C to 21.7+/-0.7 Hz at 24 degrees C. Developmental stage did not significantly influence the relationship between total length and Umax or Amax. Furthermore, temperature and the associated changes in water viscosity did not affect the relationship between total length and burst swimming performance. At their Umax, Reynolds numbers ranged from approximately 1,500 in the smaller tadpoles up to 50,000 for the larger animals at 24 degrees C. We suggest the positive allometry of Umax in larval L. peronii was due in part to the increases in tail width (TW) with total length (TW=-1.36L1.66), possibly reflecting the increasing importance of burst swimming performance to survival during larval development.     

Circadian rhythm in endogenous nerve activity in the eye of Musca dornestica L.

The frequency of occurrence of endogenous bursts of spikes was monitored by external electrode placed on the surface of housefly eyes in darkness. In LD 16:8 the frequency of these bursts showed an entrained rhythm, with a c. 10-fold change in level from rest to active periods. The rate began to increase in anticipation of dawn. The free-running period in DD was c. 21 h and in LL, 16–17 h. The active/rest ratio was 1.0 in DD and 2.5 in LL, the active phase being 10.4 h in DD and 12.3 h in LL. In these respects the rhythm conforms to Aschoff's rule. In groups of flies, the entrained rhythm was apparently lost 4–6 days after transfer from LD to LL, because the individual flies' rhythms changed from the 24 h entrained state to the LL, free-running state at differing rates, leading to asynchrony. After four cycles the phase angles in a sample of ten flies differed by 120 (8 h). In contrast, when flies were transferred from LD to DD, the phase angle variation did not differ markedly, even after 9 days, from that of entrained flies. The findings are discussed in terms of Truman's (1972) clock types.