Recent projects
Control of gas exchange in insects- After identifying two types of ventilatory activity in locusts during discontinuous gas exchange cycles (DGCs) (Huang et al., 2014), we used simultaneous EMG and respirometry in order to establish the interaction in motor activity of ventilatory and spiracle muscles. Across DGCs, the two ventilatory types are associated with three spiracular states. Together, these account for unidirectional tracheal ventilation during the burst of gas exchange, and tracheal content mixing during the interburst.
The interaction between levels of respiratory gases in triggering DGC phases led us to further study the effect of O2 and CO2 on ventilatory output of central pattern generators (CPGs) using isolated ganglia (Talal et al., 2019). We demonstrated the existence of central receptors for O2 and CO2, higher sensitivity to elevated tracheal CO2 (compared with low O2), and the interaction between tracheal levels of the two gases on fictive ventilation rate. We also showed that saline oxygenation level affects the response to tracheal gas levels, indicating an effect for the chemical composition of the hemolymph on ventilatory control.
The interaction between levels of respiratory gases in triggering DGC phases led us to further study the effect of O2 and CO2 on ventilatory output of central pattern generators (CPGs) using isolated ganglia (Talal et al., 2019). We demonstrated the existence of central receptors for O2 and CO2, higher sensitivity to elevated tracheal CO2 (compared with low O2), and the interaction between tracheal levels of the two gases on fictive ventilation rate. We also showed that saline oxygenation level affects the response to tracheal gas levels, indicating an effect for the chemical composition of the hemolymph on ventilatory control.
Gas exchange patterns in insects- Insects exchange respiratory gases with their environment in a variety of patterns, often categorized into continuous, cyclic and discontinuous gas-exchange cycles (DGCs). We are interested in the mechanistic basis and the adaptive value of DGCs.
We both employ a comparative approach and use phase-polyphenism in locusts in order to test predictions of the existing adaptive hypotheses for the evolution of DGCs. Recent findings in our lab suggests that DGCs help conserve water in some grasshopper species, but not in others (Huang et al., 2015). We also selected locusts for desiccation resistance, and showed that DGCs did not contribute to body water conservation in the more resistant selected locusts.
Additionally, we found neural plasticity of ventilatory control, where DGCs require neural output from head ganglia in solitarious, but not gregarious Schistocerca gregaria (Berman et al., 2013).
We both employ a comparative approach and use phase-polyphenism in locusts in order to test predictions of the existing adaptive hypotheses for the evolution of DGCs. Recent findings in our lab suggests that DGCs help conserve water in some grasshopper species, but not in others (Huang et al., 2015). We also selected locusts for desiccation resistance, and showed that DGCs did not contribute to body water conservation in the more resistant selected locusts.
Additionally, we found neural plasticity of ventilatory control, where DGCs require neural output from head ganglia in solitarious, but not gregarious Schistocerca gregaria (Berman et al., 2013).
Genetic diversity of scorpion populations in Israel- Molecular analyses carried out in the lab confirm previous suspicions that the two Israeli subspecies of the scorpion Scorpio maurus (Scorpionidae) are distinct species, genetically distinct from the Moroccan subspecies, S. m. mogadorensis, and revealed unexpected genetic diversity in S. m. palmatus. In a study comprising specimens from 40 localities across Israel, we identified seven clades based on mitochondrial and nuclear genes. Despite close geographical proximity, samples of fuscus from Nahal Bohu and palmatus from Nahal Sharsheret in the semi-arid Western Negev area, only 6 km apart, respectively grouped with the other samples of fuscus and palmatus collected as far as 150km away. Samples of palmatus from the Dead Sea area were genetically divergent from other Israeli palmatus samples, suggesting that palmatus may be a species complex. Interestingly, Golan Heights samples were represented by separate branches, which included both yellow and dark morphs. Our recently published data (Talal et al., 2015) indicate at least four Scorpio species in Israel.
We are currently further studying the diversity, origins and affinities of the Israeli scorpion fauna in a collaborative project with Prof. Lorenzo Prendini of the American Museum of Natural History.
We are currently further studying the diversity, origins and affinities of the Israeli scorpion fauna in a collaborative project with Prof. Lorenzo Prendini of the American Museum of Natural History.
