A GABAergic Maf-expressing interneuron subset regulates the speed of locomotion in Drosophila

This work was funded by grants from INSERM and a 3-year Ph.D. funding from the Association Française contre les Myopathies (AFM) for H.B (Doctoral funding n°19408) and from ANR (17-CE37-0019) for T.J.Interneurons (INs) coordinate motoneuron activity to generate appropriate patterns of muscle contractions, providing animals with the ability to adjust their body posture and to move over a range of speeds. In Drosophila larvae several IN subtypes have been morphologically described and their function well documented. However, the general lack of molecular characterization of those INs prevents the identification of evolutionary counterparts in other animals, limiting our understanding of the principles underlying neuronal circuit organization and function. Here we characterize a restricted subset of neurons in the nerve cord expressing the Maf transcription factor Traffic Jam (TJ). We found that TJ+ neurons are highly diverse and selective activation of these different subtypes disrupts larval body posture and induces specific locomotor behaviors. Finally, we show that a small subset of TJ+ GABAergic INs, singled out by the expression of a unique transcription factors code, controls larval crawling speed.Publisher PDFPeer reviewe

The role of genetic factors in predisposition to squamous cell cancer of the head and neck

© 1999 Cancer Research Campaig

concentration of pahs in forest ecosystems of the protected natural resource "Avala"

Belgrade is one of the greenest capitals in Europe. The protected natural area, "Avala" (i.e. a separate part of unit that is declared as a landscape of outstanding features) is located on the territory of Belgrade and attracts the attention of all profiles of researchers. It should be noted also that the area of Avala was bombed in 1999 and the Avala Tower was destroyed. Researches aiming to determine the pollutant loading of the area are of particular importance. The aim of this research is to determine the content of 16 types of PAHs in three different locations on Avala sites 1, 2 and 3, with sampling of soil at two different depths (0-10 cm and 10-20 cm). One of the most frequent streets in downtown Belgrade (locality 4) was chosen as control site. On the basis of the results, it can be concluded that the soil of Avala is well preserved, which is in line with the declaration that Avala is a protected area

High-Throughput Analysis of Stimulus-Evoked Behaviors in <i>Drosophila</i> Larva Reveals Multiple Modality-Specific Escape Strategies

<div><p>All organisms react to noxious and mechanical stimuli but we still lack a complete understanding of cellular and molecular mechanisms by which somatosensory information is transformed into appropriate motor outputs. The small number of neurons and excellent genetic tools make <i>Drosophila</i> larva an especially tractable model system in which to address this problem. We developed high throughput assays with which we can simultaneously expose more than 1,000 larvae per man-hour to precisely timed noxious heat, vibration, air current, or optogenetic stimuli. Using this hardware in combination with custom software we characterized larval reactions to somatosensory stimuli in far greater detail than possible previously. Each stimulus evoked a distinctive escape strategy that consisted of multiple actions. The escape strategy was context-dependent. Using our system we confirmed that the nociceptive class IV multidendritic neurons were involved in the reactions to noxious heat. Chordotonal (ch) neurons were necessary for normal modulation of head casting, crawling and hunching, in response to mechanical stimuli. Consistent with this we observed increases in calcium transients in response to vibration in ch neurons. Optogenetic activation of ch neurons was sufficient to evoke head casting and crawling. These studies significantly increase our understanding of the functional roles of larval ch neurons. More generally, our system and the detailed description of wild type reactions to somatosensory stimuli provide a basis for systematic identification of neurons and genes underlying these behaviors.</p></div

Detailed characterization of the larval reactions to vibration and the role of chordotonal neurons.

<p>(A and B) Vibration evokes a characteristic dynamic sequence of behaviors. (A) Graphs of mean normalized crawling speed, head angle, and normalized spine length as a function of time averaged across many animals from experiments in which wild-type <i>Canton S</i> (CS) larvae were presented with 30 s of continuous vibration (1000 Hz, 2 V) at ambient temperature of 32°C (red, N = 342) or 25°C (black, N = 248). Normalized crawling speed was computed as in Fig. 2D. Gray shading indicates the period of stimulation. Dark lines, mean value. Light lines, ± s.e.m. AC, <i>avoidance crawl</i>. OR, <i>avoidance crawl off-reaction</i> by speeding up. T, head cast (turn). H, hunch. Graphs highlight the dynamics of the reaction to vibration. Following vibration onset, there is a sharp well in the norm. spine length function, corresponding to the hunch (H), then a sharp peak in the head angle function (T), corresponding to the increase in head casting and turning. As these two functions return to baseline there is a raise in the speed function as larvae start crawling again. At 32°C the mean speed during vibration raises significantly above the speed prior to stimulation – indicating larvae are trying to actively avoid vibration by crawling faster (<i>avoidance crawl</i>). Following vibration offset there is significant increase in crawling speed relative to the baseline prior to stimulation at both 32°C and 25°C (<i>avoidance crawl off-reaction</i>, OR). Interestingly, while <i>avoidance crawling</i> in response to vibration offset happens at both temperatures, <i>avoidance crawl</i> during vibration only happens at 32°C, but not at 25°C. The precise nature of the reaction to vibration, like the reaction to noxious stimulation, is highly context-dependent. (B) Bar charts show the mean absolute larval crawling speed, the mean maximum head angle during head casts and the head casting and hunching probability in a 5 s time window before stimulation (−5 s to 0 s) and in two consecutive 5 s time windows after stimulation (0 s to 5 s and 5 s to 10 s). Error bars indicate s.e.m. * and *, <i>p</i><0.001.⁺and ⁺, <i>p</i><0.01. The mean absolute larval crawling speed is significantly higher at 32°C than at 25°C, in all three time windows. At 32°C, but not at 25°C, the absolute mean crawling speed is higher in the 5 s to 10 s, than in the 0 s to 5 s window indicating that <i>avoidance crawl</i> during stimulation only happens at the higher temperature (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0071706#pone.0071706.s002" target="_blank">Table S2</a> for further details). Head cast angle and probability are higher at 32°C than at 25°C, whereas hunch probability is higher at 25°C than at 32°C. Even though the reactions to vibration are significantly different at different temperatures, many aspects of the reaction are pronounced enough at 25°C to allow the use of the permissive temperature <i>UAS-Shibire^ts1</i> control. (C and D) Ch neurons are implicated in most aspects of the larval reaction to vibration. (C) Graphs of mean normalized crawling speed, head angle, and normalized spine length as in A at 32°C. Gray shading indicates the period of stimulation. Dark lines, mean value. Light lines, ± s.e.m. Data from larvae with inactivated ch neurons (red, <i>iav>shibire^ts1</i> at restrictive temperature of 32°C, N = 820) is compared to three different kinds of control larvae. Blue, <i>iav>shibire^ts1</i> at permissive temperature of 25°C (N = 299). Green, <i>iav>Canton S</i> at 32°C (N = 457). Black, <i>pBDPGAL4U>shibire^ts1</i> at 32°C (N = 24,865). Most aspects of the reaction to vibration are compromised in larvae with inactivated ch neurons, compared to controls. Avoidance crawl and off-reaction in the normalized speed function are not visible. The peak in the head angle function is drastically reduced. The well in the norm. spine length function is gone and instead a small peak is visible – indicating that the residual reaction to vibration that is left is actually opposite in sign and abnormal. (D) Bar charts show the mean absolute larval crawling speed, the mean maximum head angle during head casts and the head casting and hunching probability as in B. Error bars indicate s.e.m. * (blue star), * (green star) and * (black star) indicate <i>p</i><0.001 when <i>iav>shibire^ts1</i> at 32°C is compared to <i>iav>shibire^ts1</i> at 25°C, <i>iav>Canton S</i> at 32°C and <i>pBDPGAL4U>shibire^ts1</i> at 32°C, respectively. The magnitude of the head cast angle and the head cast and hunch probability following stimulation are significantly reduced in <i>iav>shibire^ts1</i>, compared to all three controls (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0071706#pone.0071706.s002" target="_blank">Table S2</a> for further details).</p

Noxious heat reactions are altered when class IV or class I neurons are inactivated.

<p>(A and C) Graphs show head angle, crabspeed and normalized crawling speed as a function of time as in Fig. 2D. Dark lines, mean value. Light lines, ± s.e.m. Grey lines at 0 s mark the stimulus onset and duration. Data from control <i>pBDPUGAL4>shibire^ts1</i> (black, N = 8461) and <i>R38A10</i>><i>Canton S</i> or <i>R20C06>Canton S</i> at 32°C (green, N = 76 and 55, respectively) and <i>R38A10>shibire^ts1</i> or <i>R20C06>shibire^ts1</i> (red, N = 915 and 1144, respectively) is compared. (B and D) Bar charts show head casting and rolling probability and the mean value of the maximum stride frequency and stride speed as in Fig. 2E. Error bars indicate s.e.m. * (black star), <i>p</i><0.001 when compared to <i>pBDPUGAL4>shibire^ts1</i> in the same time window. * (green star), <i>p</i><0.001 when compared to <i>R38A10</i>><i>Canton S</i> or <i>R20C06>Canton S</i> in the same time window. Rolling probability of <i>R38A10>shibire^ts1</i> (B, red, 29.1%, N = 915) is drastically reduced compared to <i>pBDPUGAL4>shibire^ts1</i> (B, black, 42.6%, N = 8461; <i>p</i><10⁻⁶) and <i>R38A10</i>><i>Canton S</i> (B, green, 71.1%, N = 76; <i>p</i><10⁻⁶) in the time window following noxious heat stimulation. Likewise, stride frequency and stride speed are significantly decreased compared to controls, both prior to stimulation and following stimulation (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0071706#pone.0071706.s001" target="_blank">Table S1</a> for further details). Rolling probability of <i>R20C06>shibire^ts1</i> (D, red, 32.7%, N = 1144) is drastically reduced compared to <i>pBDPUGAL4>shibire^ts1</i> (D, black, 42.6%, N = 8461; <i>p</i><10⁻⁶) and <i>R20C06</i>><i>Canton S</i> (D, green, 63.6%, N = 55; p = 0.000045) in the time window following noxious heat stimulation. Likewise, stride frequency and stride speed are significantly decreased compared to both controls, both prior to stimulation and following stimulation (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0071706#pone.0071706.s001" target="_blank">Table S1</a> for further details), consistent with the role of these neurons in proprioception.</p

<i>painless</i> mutant larvae are impaired in rolling responses to noxious heat.

<p>(A and C) Graphs show head angle, crabspeed and normalized crawling speed as a function of time, as in Fig. 2. Dark lines, mean value. Light lines, ± s.e.m. Grey lines at 0 s mark stimulus onset and duration. Data from the control <i>painless¹>w1118</i> (light green, N = 53), <i>painless³>w1118</i> (dark green, N = 45) and <i>piezoKO>w1118</i> (blue, N = 51) is compared to <i>painless¹</i> (orange, N = 126), <i>painless³</i> (red, N = 181) and <i>piezoKO</i> (red, N = 130) mutants, respectively. In both <i>painless¹</i> and <i>painless³</i> mutants the peaks in the mean crabpseed and the mean normalized speed functions are highly reduced compared to controls. They show virtually no <i>escape crawl</i>. (B and D) Bar charts show head casting and rolling probability and the mean value of the maximum stride frequency as in Fig. 2E. Error bars indicate s.e.m. * (light green star), * (dark green star) and * (blue star) indicate <i>p</i><0.001 when <i>painless¹</i>, <i>painless³</i> and <i>piezoKO</i> is compared to <i>painless¹>w1118, painless³>w1118</i> and <i>piezoKO>w1118</i>, respectively. In response to noxious heat stimulus, the rolling probability of <i>painless¹</i> (11.9%, N = 126) and <i>painless³</i> (6.1%, N = 181) larvae, defective in thermal nociception, is significantly reduced compared to the hemizygous controls (49.1%, N = 53, p<10⁻⁶ and 31.1%, N = 45, p = 0.000054). The mutants also have significantly reduced stride frequency and stride speed following stimulation and reduced stride frequency prior to stimulation (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0071706#pone.0071706.s001" target="_blank">Table S1</a> for further details). In contrast, <i>piezoKO</i> mutant larvae defective in mechanical nociception roll slightly, but not significantly more than the hemizygous controls. Interestingly they are significantly defective in escape crawl and in stride speed prior to stimulation.</p