Lucifer Yellow Histology

SUMMARYWe analyzed the courtship song of the field cricket Gryllus assimilis. The song comprises two elements: groups of ca. 10 pulses (chirps) with low fundamental frequency (3.5-3.7kHz) alternating with high-frequency (15-17kHz) pulses (ticks) that usually occur as doublets. Some elements of courtship song are quite variable (high coefficient of variation) both within and between males, whereas others are more stereotypical. In experiments with playback of synthesized courtship songs, we studied the importance of several song parameters for mating success, which we evaluated as the probability with which females mounted muted, courting males. Altering some features that show little variability, such as chirp-pulse rate or carrier frequency of ticks, resulted in significant decreases in mounting frequency, consistent with the notion that trait values showing little variability are constrained by stabilizing selection exerted by females. However, alteration of one invariant trait, the occurrence of both song components, by omitting either component from test songs only slightly affected female responsiveness. Alteration of a variable song trait, the number of ticks per song phrase, had no effect on female response rate, thus failing to provide support for the idea that variable traits provide a substrate for sexual selection. An unusual characteristic feature of the song of G. assimilis is that chirp pulses often contain substantial high-frequency power, and indeed may entirely lack power at the fundamental frequency. Playback experiments showed that such songs are, nevertheless, behaviorally effective. To understand the neural basis for this, we recorded the responses of the two principal ascending auditory interneurons of crickets, AN1 and AN2. Our results suggest that the frequency selectivity of the neurons is sufficiently broad to tolerate the spectral variability of courtship chirps.

Section: Electrophysiologymentioning

confidence: 99%

Recognition of variable courtship song in the field cricketGryllus assimilis

Vedenina

Pollack

2012

“…The prothoracic ganglion and cervical connectives were exposed by ventral dissection and bathed in physiological saline (Strausfeld et al, 1983). ON1 was recorded extracellularly with a glass microelectrode (5-10·M⍀, 1·mol·l -1 NaCl) from its soma-contralateral processes in the auditory neuropil, where its spikes can be recognized unambiguously by response preference for electrodecontralateral (i.e.…”

Section: Neurophysiologymentioning

confidence: 99%

Flight and hearing: ultrasound sensitivity differs between flight-capable and flight-incapable morphs of a wing-dimorphic cricket species

Pollack

Martins

2007

Predation by echolocating bats has been an important selective pressure on insects, favoring the evolution of ultrasound-sensitive ears (Hoy, 1992;Jones and Rydell, 2003). Aerially hawking bats emit ultrasonic probes and detect flying insect prey by the echoes that return from their bodies. In some hearing species flight is restricted to one gender, and sensitivity to ultrasound is reduced in the non-flying gender, e.g. moths (Cardone and Fullard, 1988) and mantises (Yager, 1990). These observations suggest that sensitivity to ultrasound is closely linked to flight physiologically, as well as evolutionarily.Many cricket species are flight dimorphic, occurring both as long-winged and short-winged forms (Zera, 2004;Roff and Fairbairn, 2007). The long-winged form is initially capable of flight, but individuals may lose this ability when flight muscles undergo histolysis, which becomes increasingly probable with advancing adult age (Shiga et al., 1991). The short-winged form is incapable of flight throughout life. Unlike the cases cited above, in flight-dimorphic crickets the risk of bat predation varies within a single gender and, for long-winged crickets, within a single individual. Moreover, crickets use hearing not only to detect bats but also, in a lower range of frequencies, for intraspecific communication (Moiseff et al., 1978). We compare auditory sensitivity between flightcapable and flight-incapable forms of the cricket Gryllus texensis, both to ultrasonic stimuli and to the sonic frequency of intraspecific signals. We find, using both behavioral and neurophysiological measures, that sensitivity to ultrasound, but not to low sound frequencies, varies according to the ability to fly. Our findings suggest that ultrasound sensitivity is one of a suite of developmental and physiological phenotypes that are linked to flight, and thus to the risk of predation by aerially hawking bats. Materials and methodsAnimals Gryllus texensis (Cade and Otte) were reared in the laboratory at 25-28°, on a 12·h:12·h photoperiod, with ad libidum access to Purina TM Cat Chow and water. Under these conditions, approximately half the males develop as long-winged, and half as short-winged individuals. The frequency of short-winged females is much lower, approximately 10%. We studied males aged 7-21 days after the final molt. Both long-and short-winged males were selected from the same cohorts, the adult ages of which were known to within 1 week. Thus, both wing morphs were represented approximately equally over the entire range of ages. Experiments were performed during the animals' scotophase. Sound stimuliStimuli were produced by National Instruments (Austin, TX, USA) digital-to-analog boards (AT-MIO 16E4, 12-bit resolution or PCI-6251, 16-bit) with sampling rate of 100·kHz. Sound level (r.m.s. of a constant tone with the same peak amplitude as actual stimuli) was adjusted by a programmable attenuator (PA4, Tucker-Davis, Alachua, FL, USA or 50P-076, JFW Industries, Indianapolis, IN, USA) and calibrated with Bruël and Kjaer instrum...

“…Interestingly, synaptic potentials persisted long after contractions faded and did not exhibit signs of decay. It is possible that our Sarcophaga saline, an insect Ringer's solution referenced by Strausfeld et al (Strausfeld et al, 1983), may benefit from customization to the larval body wall tissue as HL-3 was customized for Drosophila by Stewart et al (Stewart et al, 1994).…”

Section: Discussionmentioning

confidence: 99%

“…Experiments utilizing Sarcophaga were performed in insect saline (Strausfeld et al, 1983) Stewart et al (Stewart et al, 1994). Temperature was maintained during Sarcophaga experiments between 16°C and 18°C via recirculation of coolant through the preparation stage.…”

Section: Physiologymentioning

confidence: 99%

Hysteresis in the production of force by larval Dipteran muscle

Paterson

Anikin

Krans

2010

SUMMARYWe describe neuromuscular hysteresis -the dependence of muscle force on recent motoneuron activity -in the body wall muscles of larval Sarcophaga bullata and Drosophila melanogaster. In semi-intact preparations, isometric force produced by a train of nerve impulses at a constant rate was significantly less than that produced by the same train of stimuli with a brief (200ms) high-frequency burst of impulses interspersed. Elevated force did not decay back to predicted values after the burst but instead remained high throughout the duration of the stimulus train. The increased force was not due to a change in excitatory junction potentials (EJPs); EJP voltage and time course before and after the high-frequency burst were not statistically different. Single muscle and semi-intact preparations exhibited hysteresis similarly, suggesting that connective tissues of the origin or insertion are not crucial to the mechanism of hysteresis. Hysteresis was greatest at low motoneuron rates -yielding a ~100% increase over predicted values based on constant-rate stimulation alone -and decreased as impulse rate increased. We modulated motoneuron frequency rhythmically across rates and cycle periods similar to those observed during kinematic analysis of larval crawling. Positive force hysteresis was also evident within these more physiological activation parameters.