Archives

  • 2018-07
  • 2019-04
  • 2019-05
  • 2019-06
  • 2019-07
  • 2019-08
  • 2019-09
  • 2019-10
  • 2019-11
  • 2019-12
  • 2020-01
  • 2020-02
  • 2020-03
  • 2020-04
  • 2020-05
  • 2020-06
  • 2020-07
  • 2020-08
  • 2020-09
  • 2020-10
  • 2020-11
  • 2020-12
  • 2021-01
  • 2021-02
  • 2021-03
  • 2021-04
  • 2021-05
  • 2021-06
  • 2021-07
  • 2021-08
  • 2021-09
  • 2021-10
  • 2021-11
  • 2021-12
  • 2022-01
  • 2022-02
  • 2022-03
  • 2022-04
  • 2022-05
  • 2022-06
  • 2022-07
  • 2022-08
  • 2022-09
  • 2022-10
  • 2022-11
  • 2022-12
  • 2023-01
  • 2023-02
  • 2023-03
  • 2023-04
  • 2023-05
  • 2023-06
  • 2023-07
  • 2023-08
  • 2023-09
  • 2023-10
  • 2023-11
  • 2023-12
  • 2024-01
  • 2024-02
  • 2024-03
  • In the present study the relative mRNA expression levels

    2021-10-15

    In the present study, the relative mRNA Phenacetin levels of CsLCCH3 and Cs8916 subunits in the egg were the highest, which were consistent with those of LsLCCH3 and Ls8916 from L. striatellus (Wei et al., 2017b) and were also similar to CsRDLs (Sheng et al., 2018; Meng et al., 2018). Overall, the transcript patterns of GABAR subunits in C. suppressalis were in line with those in L. striatellus (Sheng et al., 2018; Wei et al., 2017b; Wei et al., 2015). However, diverse mRNA expression patterns of GABAR subunits were found in Spodoptera litura Fabricius (Zuo et al., 2013), Plutella xylostella Linnaeus (Zhou et al., 2006) and S. exigua Hübner (Shang et al., 2009). In S. litura and S. exigua, the relative mRNA expression levels of SlGABARα2 and SeGABARa2 increased with larval growth (Zuo et al., 2013). In P. xylostella, the relative mRNA expression level of PxGABAa at various developmental stages was not significantly different (Zhou et al., 2006). Taken together, these results indicate that the GABAR subunits possibly have multiple expression patterns in different insect species. Diverse mutations in the RDL subunit, including T6’L, A2’S/N, T345 M, R340Q, and G336 M (ffrench-Constant et al., 1993; Nakao et al., 2011; Nakao, 2016), underlies resistance to several insecticides (Wei et al., 2017a; Sheng et al., 2017; Fujii et al., 2012; Novelli et al., 2016). Fluralaner exhibits high activity on C. suppressalis (Sheng et al., 2017) and acts on a unique site in GABARs (Ozoe et al., 2010) with low toxicity to D. rerio and Pseudokirchneriella subcapitata (Korshikov) F. Hindák, and moderate toxicity to Cyprinus carpio Linnaeus (Jia et al., 2018; MSD Animal Health, 2014). Similarly, chlorantraniliprole is also highly toxic to C. suppressalis acting on the ryanodine receptor (RyR) (Su et al., 2014). Injection of dsRDL1 and dsRDL2 significantly reduced the mRNA expression levels of CsRDL1 and CsRDL2 subunits, respectively, which possibly reduced the binding of fluralaner to the GABAR and therefore mortality of C. suppressalis (Fig. 4). This finding was similar to other studies (Wei et al., 2015; Yang et al., 2014; Wang et al., 2018). For instance, in Sogatella furcifera (Horváth), dietary ingestion of dsRyR1 and dsRyR2 could not only significantly reduce the mRNA expression level of RyR but also greatly decreased chlorantraniliprole-induced mortality (Yang et al., 2014). In L. striatellus, dsRDL injection could reduce mRNA abundance by 27–82% and significantly decreased fipronil-induced mortality of both fipronil susceptible- and resistant-strains of L. striatellus (Wei et al., 2015). Wang et al. (2018) found that silencing of RyR in Mythimna separate Walker could significantly reduce mRNA levels to 40.1% and chlorantraniliprole-induced mortality by 22.3% (Wang et al., 2018). Interestingly, Meng et al. (2018) found that the dietary ingestion of dsRDL1 and dsRDL2 could significantly decrease C. suppressalis larval susceptibility to abamectin (Meng et al., 2018). Unlike dsRDL, dsLCCH3 and ds8916 down-regulated subunit mRNA levels in C. suppressalis but did not affect mortality induced by fluralaner or chlorantraniliprole. Our results demonstrate that the CsRDL genes could encode a functional GABAR that mediates the fluralaner toxicity to C. suppressalis. In conclusion, the primary sequence information and expression profiles of LCCH3 and 8916 subunits in C. suppressalis were investigated and further information about CsRDL interaction with insecticides was provided. These findings are helpful for us to further explore the function of GABARs in C. suppressalis and to enhance our knowledge of insect ionotropic GABARs, possibly facilitating the development of improved insecticides.
    Compared to other CNS regions, such as the cortex, hippocampus or cerebellum, the thalamic GABAergic network may appear at first glance very modest. While for example the morphological, molecular and physiological features of cortical interneurons are so diverse that researchers had to join force to propose a classification of these complex neuronal populations (), the intrathalamic GABAergic neurons come down to two types, the neurons located in the nucleus reticularis thalami and the local interneurons that are present in different thalamic nuclei. However, except in the dorsal lateral geniculate nucleus very few interneurons (less than 5% of the total neuronal population) are present in thalamic nuclei of rodents (, ). Therefore, most of the available data on GABAergic inhibition in rodent primary thalamic nuclei deals with inhibitory mechanisms originating from the NRT (A). Despite this paucity of GABAergic cell types, the thalamic network is one of the most interesting systems where GABA impact on neuronal excitability can be studied. Indeed, both glutamatergic thalamocortical (TC) and GABAergic nucleus reticularis thalami (NRT) neurons present a high expression of T-type voltage-dependent Ca channels whose activation, which generates the so-called rebound low-threshold spike (LTS) and is the bases of the thalamic bursting mode of firing, critically depends upon a preceding hyperpolarisation (B) (, ). T-type voltage-dependent Ca currents activate around 60 mV, are fully inactivated after a few tens of milliseconds and their steady-state inactivation is nearly complete at membrane potentials more depolarized than 60 mV (). Therefore, hyperpolarization allowing some channels to recover from inactivation is required to evoke a substantial T-current (C) creating a strict dependence of the LTS upon a preceding hyperpolarization such as those mediated by the GABA and GABA receptors.