Juvenile hormone (JH) regulates reproductive maturation in insects; therefore interruption of

Juvenile hormone (JH) regulates reproductive maturation in insects; therefore interruption of JH biosynthesis has been considered as a strategy for the development of target-specific insecticides. that regulates CA activity. Trichostatin-A (TSA) Principal component (PC) analyses validated that both pathways (MVAP and JH-branch) are transcriptionally co-regulated as a single unit and catalytic activities for the enzymes of the MVAP and JH-branch also changed in a coordinate fashion. Metabolite studies showed that global fluctuations in the intermediate pool sizes in the MVAP and JH-branch were often inversely related. PC analyses suggest that in female mosquitoes there are at least 4 developmental switches that alter JH synthesis by modulating the flux at distinctive points in both pathways. (CA) interfaces between the brain and reproductive tissues producing JH at rates proportional to female nutrient reserves (Clifton and Noriega 2011 Clifton and Noriega 2012 Perez-Hedo et al. 2014 In mosquitoes four stages can be defined in the development of the ovaries: females emerge with 40 μm immature previtellogenic follicles that grow into 100 μm mature previtellogenic oocytes in the next 24-48 h. Oocytes remain in a dynamic “state of arrest” and will enter vitellogenesis after a blood meal (Hagedorn 1974 Klowden 1997 (Fig. 1). JH directly controls nutrient allocation into the ovaries in the previtellogenic phases and indirectly influences the fate of vitellogenic follicles after a blood meal (Clifton and Noriega 2011 Clifton and Noriega 2012 Noriega 2004 Fig. 1 JH biosynthesis and ovarian development in female mosquitoes JH is synthesized through the mevalonate pathway (MVAP) an ancient metabolic pathway present in the three domains of life (Lombard and Moreira 2010 responsible for the synthesis of many essential molecules required for cell signaling membrane integrity energy homeostasis protein prenylation and glycosylation (Goldstein and Brown 1990 Holstein and Hohl 2004 McTaggart 2006 Vranova et al. 2013 The MVAP consists of Trichostatin-A (TSA) a main trunk followed by sub-branches that generate a diverse range of biomolecules. Insects lack the cholesterol-synthetic branch present in vertebrates (Belles et al. 2005 but in the CA the MVAP branches into the synthesis of JH. The main trunk of the MVAP consists of multiple enzymatic steps through Trichostatin-A (TSA) which acetyl-CoA is gradually transformed into the 5-carbon compound isopentenyl-pyrophosphate (IPP) and later on to the 15-carbon molecule farnesyl-pyrophosphate (FPP) (Klowden 1997 In the CA of Trichostatin-A (TSA) mosquitoes FPP is sequentially transformed to farnesol (FOL) farnesal (FAL) farnesoic acid (FA) methyl farnesoate (MF) and JH III GADD45B (hereafter JH) (Nouzova et al. 2011 (Fig. 2). Fig. 2 Mevalonic pathway and JH synthesis branch metabolites and enzymes Regulation of CA activity occurs at three different levels (Applebaum et al. 1991 Unnithan and Feyereisen 1995 developmental maturation to synthesize JH which normally proceeds in conjunction with developmental changes such as the transition from pupa to adult (Goodman and Cusson 2012 long-term modulation such as variations in enzyme levels during cycles of CA activity (Applebaum et al. 1991 Nouzova et al. 2011 and short term responses such as the inhibition of JH synthesis by allatostatins (Unnithan and Feyereisen 1995 Li et al. 2003 In all these instances the rate of JH biosynthesis is controlled by the rate of flux of isoprenoids in the pathway which is the outcome of a complex interplay of changes in precursor pools enzyme levels and external regulators (Li et al. 2004 Li et Trichostatin-A (TSA) al. 2003 2003 Li et al. 2006 Nouzova et al. 2011 Nyati et al. 2013 Rivera-Perez et al. 2013 A coordinated expression of most JH biosynthetic Trichostatin-A (TSA) enzymes has been previously described in mosquitoes and silkworm (Kinjoh et al. 2007 Nouzova et al. 2011 Ueda et al. 2009 Increases or decreases in transcript levels for all the enzymes are generally concurrent with increases or decreases in JH synthesis (Kinjoh et al. 2007 Nouzova et al. 2011 Rivera-Perez et al. 2013 Ueda et al. 2009 Previous studies have proposed that regulation of JH synthesis occurs upstream of the acetyl-CoA pool (Sutherland and Feyereisen 1996 as well as by rate limiting bottlenecks at different enzymatic steps in the pathway including the activities of HMG-CoA reductase (Kramer and Law 1980 Monger and Law 1982 farnesol dehydrogenase (Mayoral et al. 2009 farnesal dehydrogenase (Rivera-Perez et al. 2013 or juvenile hormone acid methyltransferase.