Calcium control and InsP4

WGCNA based identification of hub genes associated with cold response and development in Apis mellifera metamorphic pupae

Honeybee is a crucial pollinator in nature, and plays an indispensable role in both agricultural production and scientific research. In recent decades, honeybee was challenged with health problems by biotic and abiotic stresses. As a key ecological factor, temperature has been proved to have an impact on the survival and production efficiency of honeybees. Previous studies have demonstrated that low temperature stress can affect honeybee pupation and shorten adult longevity. However, the molecular mechanism underlying the effects of low temperatures on honeybee growth and development during their developmental period remain poorly understood. In this paper, the weighted gene co-expression analysis (WGCNA) was employed to explore the molecular mechanisms underpinnings of honeybees' respond to low temperatures (20°C) during four distinct developmental stages: large-larvae, prepupae, early-pupae and mid-pupae. Through an extensive transcriptome analysis, thirteen gene co-expression modules were identified and analyzed in relation to honeybee development and stress responses. The darkorange module was found to be associated with low temperature stress, with its genes primarily involved in autophagy-animal, endocytosis and MAPK signaling pathways. Four hub genes were identified within this module, namely, loc726497, loc409791, loc410923, and loc550857, which may contribute to honeybee resistance to low temperature and provide insight into the underlying mechanism. The gene expression patterns of grey60 and black modules were found to correspond to the developmental stages of prepupae and early-pupae, respectively, with the hub genes loc409494, loc725756, loc552457, loc726158, Ip3k and Lcch3 in grey60 module likely involved in brain development, and the hub genes loc410555 in black module potentially related to exoskeleton development. The brown module genes exhibited a distinct pattern of overexpression in mid-pupae specimens, with genes primarily enriched in oxidative phosphorylation, citrate cycle and other pathways, which may be related to the formation of bee flying muscle. No related gene expression module was found for mature larvae stage. These findings provide valuable insights into the developmental process of honeybees at molecular level during the capped brood stage.

Hydrothermal Synthesis of Nanostructured Vanadium Oxides

A wide range of vanadium oxides have been obtained via the hydrothermal treatment of aqueous V(V) solutions. They exhibit a large variety of nanostructures ranging from molecular clusters to 1D and 2D layered compounds. Nanotubes are obtained via a self-rolling process while amazing morphologies such as nano-spheres, nano-flowers and even nano-urchins are formed via the self-assembling of nano-particles. This paper provides some correlation between the molecular structure of precursors in the solution and the nanostructure of the solid phases obtained by hydrothermal treatment.

Effect of inositol 1,3,4,5-tetrakisphosphate on inositol trisphosphate-activated Ca2+ signaling in mouse lacrimal acinar cells

In mouse lacrimal acinar cells, microinjection of the metabolically stable analog of inositol 1,4,5-trisphosphate, inositol 2,4,5-trisphosphate ((2,4,5)IP3), stimulated both intracellular Ca2+ mobilization and Ca2+ entry. Microinjection of inositol 1,3,4,5-tetrakisphosphate ((1,3,4,5)IP4), the inositol 1,4,5-trisphosphate-3-kinase product, was ineffective at mobilizing intracellular Ca2+ or activating Ca2+ entry. In lacrimal cells previously microinjected with submaximal levels of (2,4,5)IP3, the subsequent microinjection of low to moderate concentrations of (1,3,4,5)IP4 did not result in additional release of intracellular Ca2+, nor did it potentiate the Ca2+ entry phase attributable to (2,4,5)IP3. However, as previously demonstrated (Bird, G. S. J., Rossier, M. F., Hughes, A. R., Shears, S. B., Armstrong, D. L., and Putney, J. W., Jr. (1991) Nature 352, 162-165), additional injections of (2,4,5)IP3 induced further mobilization of intracellular Ca2+ and increased the elevated and sustained Ca2+ entry phase. Introduction of high concentrations of (1,3,4,5)IP4 appeared to inhibit or block the (2,4,5)IP3-induced Ca2+ entry phase. These results were consistent with the observed effect of (1,3,4,5)IP4 in permeabilized lacrimal cells, where (1,3,4,5)IP4 did not release cellular 45Ca2+ but at high concentrations inhibited the ability of submaximal concentrations of (2,4,5)IP3 to release 45Ca2+. Likewise, injection of a high concentration of (1,3,4,5)IP4 prior to injection of (2,4,5)IP3 blocked both release and influx of Ca2+. The inhibitory action of (1,3,4,5)IP4 on Ca2+ signaling observed in intact cells occurred at concentrations that might be obtained in agonist-stimulated cells. However, in permeabilized cells, (1,3,4,5)IP4 inhibited Ca2+ mobilization at concentrations exceeding those likely to occur in agonist-stimulated cells. These results suggest that physiologically relevant levels of (1,3,4,5)IP4 in the cell cytoplasm do not release Ca2+, nor do they potentiate inositol trisphosphate-induced Ca2+ entry across the plasma membrane. Rather, the possibility is raised that (1,3,4,5)IP4 or one of its metabolites could function as a negative feedback on Ca2+ mobilization by inhibiting inositol 1,4,5-trisphosphate-induced Ca2+ release.

InsP3 and Ins(1,3,4,5)P4 act in synergy to stimulate influx of extracellular Ca2+ in Xenopus oocytes

To investigate the role of D-myo-inositol 1,3,4,5-tetrakisphosphate [Ins(1,3,4,5)P4] in the regulation of Ca2+ influx, we injected inositol phosphates into Xenopus oocytes and measured Ca(2+)-gated Cl- current to assay intracellular free Ca2+ concentration ([Ca2+]i). To assess Ca2+ influx, we removed extracellular Ca2+ or added the inorganic Ca2+ channel blocker Mn2+ to the extracellular bath and measured the resulting change in Cl- current. Ins(1,3,4,5)P4 did not cause Ca2+ influx when injected alone or when preceded by an injection of Ca2+. In contrast, Ins(1,3,4,5)P4 stimulated Ca2+ influx when injected after the poorly metabolized inositol trisphosphate (InsP3) analogues D-myo-inositol 1,4,5-trisphosphorothioate [Ins(1,4,5)P3S3] or D-myo-inositol 2,4,5-trisphosphate [Ins(2,4,5)P3]. These results indicate that Ins(1,3,4,5)P4 is not sufficient to stimulate Ca2+ influx but acts in synergy with InsP3s to cause Ca2+ influx. We also studied the effect of Ca2+ influx on the immediate metabolism of D-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] in single oocytes. Ca2+ influx shunted the metabolism of Ins(1,4,5)P3 toward the formation of Ins(1,3,4,5)P4 and away from D-myo-inositol 1,4-bisphosphate [Ins(1,4)P2]. These results suggest that there is a positive feedback regulatory mechanism in which Ca2+ influx stimulates Ins(1,3,4,5)P4 production and Ins(1,3,4,5)P4 stimulates further Ca2+ influx.

Inositol lipids in cell signalling

In the past year, major advances have been made in our understanding of the regulation of phosphoinositidase C, and of the action of the inositol trisphosphate receptor and how it may generate 'quantal' Ca2+ release. The functions of inositol tetrakisphosphate and of the 3-phosphorylated inositol lipids continue to generate controversy, but both may be well on the way towards some clarification. Finally, we may have to extend our concept of the inositide cycle to include an intranuclear signalling function.