@article {6390, title = {Juvenile hormone and insulin suppress lipolysis between periods of lactation during tsetse fly pregnancy.}, journal = {Molecular and Cellular Endocrinology}, volume = {372}, year = {2013}, month = {2013 Jun 15}, pages = {30-41}, abstract = {

Tsetse flies are viviparous insects that nurture a single intrauterine progeny per gonotrophic cycle. The developing larva is nourished by the lipid-rich, milk-like secretions from a modified female accessory gland (milk gland). An essential feature of the lactation process involves lipid mobilization for incorporation into the milk. In this study, we examined roles for juvenile hormone (JH) and insulin/IGF-like (IIS) signaling pathways during tsetse pregnancy. In particular, we examined the roles for these pathways in regulating lipid homeostasis during transitions between non-lactating (dry) and lactating periods. The dry period occurs over the course of oogenesis and embryogenesis, while the lactation period spans intrauterine larvigenesis. Genes involved in the JH and IIS pathways were upregulated during dry periods, correlating with lipid accumulation between bouts of lactation. RNAi suppression of Forkhead Box Sub Group O (FOXO) expression impaired lipolysis during tsetse lactation and reduced fecundity. Similar reduction of the JH receptor Methoprene tolerant (Met), but not its paralog germ cell expressed (gce), reduced lipid accumulation during dry periods, indicating functional divergence between Met and gce during tsetse reproduction. Reduced lipid levels following Met knockdown led to impaired fecundity due to inadequate fat reserves at the initiation of milk production. Both the application of the JH analog (JHA) methoprene and injection of insulin into lactating females increased stored lipids by suppressing lipolysis and reduced transcripts of lactation-specific genes, leading to elevated rates of larval abortion. To our knowledge, this study is the first to address the molecular physiology of JH and IIS in a viviparous insect, and specifically to provide a role for JH signaling through Met in the regulation of lipid metabolism during insect lactation.

}, issn = {1872-8057}, doi = {10.1016/j.mce.2013.02.019}, author = {Baumann, Aaron A and Benoit, Joshua B and Michalkova, Veronika and Mireji, Paul O and Attardo, Geoffrey M and Moulton, John K and Wilson, Thomas G and Aksoy, Serap} } @article {6391, title = {Evolutionary divergence of the paralogs Methoprene tolerant (Met) and germ cell expressed (gce) within the genus Drosophila.}, journal = {Journal of Insect Physiology}, volume = {56}, year = {2010}, month = {2010 Oct}, pages = {1445-55}, abstract = {

Juvenile hormone (JH) signaling underpins both regulatory and developmental pathways in insects. However, the JH receptor is poorly understood. Methoprene tolerant (Met) and germ cell expressed (gce) have been implicated in JH signaling in Drosophila. We investigated the evolution of Met and gce across 12 Drosophila species and found that these paralogs are conserved across at least 63 million years of dipteran evolution. Distinct patterns of selection found using estimates of dN/dS ratios across Drosophila Met and gce coding sequences, along with their incongruent temporal expression profiles in embryonic Drosophila melanogaster, illustrate avenues through which these genes have diverged within the Diptera. Additionally, we demonstrate that the annotated gene CG15032 is the 5{\textquoteright} terminus of gce. In mosquitoes and beetles, a single Met-like homolog displays structural similarity to both Met and gce, and the intron locations are conserved with those of gce. We found that Tribolium and mosquito Met orthologs are assembled from Met- and gce-specific domains in a modular fashion. Our results suggest that Drosophila Met and gce experienced divergent evolutionary pressures following the duplication of an ancestral gce-like gene found in less derived holometabolous insects.

}, keywords = {Amino Acid Sequence, Animals, Drosophila, Drosophila Proteins, Evolution, Gene Duplication, Methoprene, Molecular, Molecular Sequence Data, Phylogeny, Protein Structure, Sequence Alignment, Tertiary}, issn = {1879-1611}, doi = {10.1016/j.jinsphys.2010.05.001}, author = {Baumann, Aaron and Fujiwara, Yoshihiro and Wilson, Thomas G} } @article {6392, title = {Drosophila melanogaster Methoprene-tolerant (Met) gene homologs from three mosquito species: members of PAS transcriptional factor family.}, journal = {Journal of Insect Physiology}, volume = {53}, year = {2007}, month = {2007 Mar}, pages = {246-53}, abstract = {

The Methoprene-tolerant (Met) gene in Drosophila melanogaster has been shown to function in juvenile hormone (JH) action. Met homologs were isolated from three mosquito species, Culex pipiens, Aedes aegypti and Anopheles gambiae. Sequence similarity was found to be high in bHLH and PAS conserved domains, and the majority of the 7-9 introns in AaMet and AgMet are located in either identical or similar positions, indicating evolutionary relatedness. Sequence comparison with Met and the similar germ-cell expressed (gce) gene in D. melanogaster showed that the mosquito genes are more similar to gce than to Met. Moreover, the multiple introns in AgMet and AaMet are more similar in number with the 7 introns in Dmgce than to the single intron in DmMet; in fact, six intron positions in AaMet and AgMet are similar to those in Dmgce. Efforts to identify a second homologous gene in mosquitoes were unsuccessful, suggesting a single gene in lower Diptera, consistent with the single gene uncovered in genomic sequencing of Ae. aegypti and An. gambiae. These results suggest that a gene duplication occurred during the evolution of higher Diptera, resulting in Met and gce.

}, keywords = {Amino Acid Sequence, Animals, Base Sequence, Basic Helix-Loop-Helix Transcription Factors, Culicidae, DNA, DNA Primers, Drosophila melanogaster, Drosophila Proteins, Evolution, Gene Components, Molecular, Molecular Sequence Data, Phylogeny, Reverse Transcriptase Polymerase Chain Reaction, Sequence Alignment, Sequence Analysis, Sequence Homology, Species Specificity}, issn = {0022-1910}, doi = {10.1016/j.jinsphys.2006.07.011}, author = {Wang, Shaoli and Baumann, Aaron and Wilson, Thomas G} }