|In This Issue – 50.1|
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Establishment of a cell line from the ash and privet borer beetle Tylonotus bimaculatus Haldeman and assessment of its sensitivity to diacylhydrazine insecticides
Many wood-boring insects and beetles in particular, represent serious threats to the health of forests. Consequently significant research efforts are devoted to understand their basic physiology and molecular biology, with the ultimate goal of developing better management practices. Wood boring beetles can be costly and impractical to rear in the lab. Likewise, collecting insect material from the field can be challenging for a variety of reasons. Established insect cell lines are therefore particularly valuable for the study of basic molecular processes, such as those involved in the metabolism of synthetic insecticides or plant-derived compounds. Our paper describes the establishment of a new cell line (NRCAN-Tb-521) from the ash and privet borer, and its response to three synthetic compounds of the diacylhydrazine family, namely tebufenozide, methoxyfenozide and halofenozide. All these compounds share the same mode of action, which is to mimic the effects of the insect hormone 20-hydroxyecdysone (20E), but halofenozide is the only one displaying efficacy against beetles. We set out to determine the effect of each compound, along with 20E, on NRCAN-Tb-521 cell morphology, viability and on the activation of the 20E-induced gene expression cascade. All compounds affected cell morphology and reduced viability in a dose-dependent manner without any obvious differences between them. However, 20E-dependent expression of the HR3 gene appears slightly earlier in halofenozide-treated cells than in cells treated with the natural hormone or with tebufenozide or methoxyfenozide. While more quantitative data on halofenozide-induced gene expression and in vivo efficacy in T. bimaculatus would be required to validate the results, the NRCAN-Tb-521 cell line is valuable to study insecticide action in longhorned beetles.
Fayuan Wen, Guido Caputo, Sharon Hooey, Susan Bowman, Kristine Pinkney, Peter J. Krell, Basil Arif, Daniel Doucet. Establishment of a cell line from the ash and privet borer beetle Tylonotus bimaculatus Haldeman and assessment of its sensitivity to diacylhydrazine insecticides. In Vitro Cellular & Developmental Biology-Animal 51:905-914, 2015.
The hopping stops? Exploration of Frog virus 3 (FV3) host shift potential in rainbow trout cell cultures
Host shifting ability of viruses have often led to emerging infectious diseases in the new hosts. This ability may be one of the reasons why viruses have been implicated as important players in directing the course of biological evolution. Often, RNA viruses are most capable of host shift due to their higher mutation rates and possibly lower dependency on host cells transcriptional machinery. However, DNA viruses are also capable of host shift; prominent examples are Ranaviruses. Ranaviruses host range includes fish, amphibians and reptiles. An important ranavirus of ecological importance is frog virus 3 (FV3) as it may play a role in the declining amphibian population. While at the population level, FV3 is commonly endemic in amphibians, at the cellular level, it is commonly grown on fish fathead minnow cell lines such as FHM and EPC. Therefore, in this report, the ability of the Ranavirus, FV3 to infect and replicate in rainbow trout cell lines derived from multiple tissues and organs were examined to assess its potential ability to infect and remain endemic in rainbow trout fish. At the very basic level, the ability of any virus to be endemic in new hosts is dependent on virus replication within cells. The following conclusions can be made based on FV3 infection of six rainbow trout cell lines, gill (RTgill-W1), intestine (RTgut-GC), liver (RTL-W1), gonads (RTG-2), skin (RTHDF), and spleen (RTS11), and primary peripheral blood and head kidney leukocyte cultures. FV3 was capable of infecting and inducing cytopathic effect (CPE) in all cell lines; however, virus replication in them was either not detectable or very poor. The CPE appeared as non-apoptotic cell death in all cell lines except the macrophage cell line, RTS11, which underwent apoptosis in response to FV3. Similarly, macrophage-like fractions of head kidney leukocyte underwent significant apoptosis compared to lymphocyte-like fractions suggesting a general preference for FV3 to induce apoptosis in fish macrophages. While FV3 was shown to infect and kill rainbow trout cells, its poor ability to replicate and produce high titres in them suggests that the risk of FV3 causing disease in rainbow trout appears to be low.
P. H. Pham, Y. J. Huang, D. D. Mosser, N. C. Bols. Use of cell lines and primary cultures to explore the capacity of rainbow trout to be a host for frog virus 3 (FV3). In Vitro Cellular & Developmental Biology – Animal 51:894-904, 2015.