Background: Most vascular flowering plants have the capacity to form symbiotic associations with arbuscular mycorrhizal (AM) fungi. The symbiosis develops in the roots where AM fungi colonize the root cortex and form arbuscules within the cortical cells. Arbuscules are enveloped in a novel plant membrane and their establishment requires the coordinated cellular activities of both symbiotic partners. The arbuscule-cortical cell interface is the primary functional interface of the symbiosis and is of central importance in nutrient exchange. To determine the molecular events the underlie arbuscule development and function, it is first necessary to identify genes that may play a role in this process. Toward this goal we used the Affymetrix GeneChip ® Medicago Genome Array to document the M. truncatula transcript profiles associated with AM symbiosis, and then developed laser microdissection (LM) of M. truncatula root cortical cells to enable analyses of gene expression in individual cell types by RT-PCR.

BackgroundNo commercially licensed vaccine or treatment is available for dengue fever, a potentially lethal infection that impacts millions of lives annually. New tools that target mosquito control may reduce vector populations and break the cycle of dengue transmission. Male mosquito seminal fluid proteins (Sfps) are one such target since these proteins, in aggregate, modulate the reproduction and feeding patterns of the dengue vector, Aedes aegypti. As an initial step in identifying new targets for dengue vector control, we sought to identify the suite of proteins that comprise the Ae. aegypti ejaculate and determine which are transferred to females during mating.Methodology and Principal FindingsUsing a stable-isotope labeling method coupled with proteomics to distinguish male- and female-derived proteins, we identified Sfps and sperm proteins transferred from males to females. Sfps were distinguished from sperm proteins by comparing the transferred proteins to sperm-enriched samples derived from testes and seminal vesicles. We identified 93 male-derived Sfps and 52 predicted sperm proteins that are transferred to females during mating. The Sfp protein classes we detected suggest roles in protein activation/inactivation, sperm utilization, and ecdysteroidogenesis. We also discovered that several predicted membrane-bound and intracellular proteins are transferred to females in the seminal fluids, supporting the hypothesis that Ae. aegypti Sfps are released from the accessory gland cells through apocrine secretion, as occurs in mammals. Many of the Ae. aegypti predicted sperm proteins were homologous to Drosophila melanogaster sperm proteins, suggesting conservation of their sperm-related function across Diptera.Conclusion and SignificanceThis is the first study to directly identify Sfps transferred from male Ae. aegypti to females. Our data lay the groundwork for future functional analyses to identify individual seminal proteins that may trigger female post-mating changes (e.g., in feeding patterns and egg production). Therefore, identification of these proteins may lead to new approaches for manipulating the reproductive output and vectorial capacity of Ae. aegypti.

The maize (Zea mays) transposable element Dissociation (Ds) was mobilized for large-scale genome mutagenesis and to study its endogenous biology. Starting from a single donor locus on chromosome 10, over 1500 elements were distributed throughout the genome and positioned on the maize physical map. Genetic strategies to enrich for both local and unlinked insertions were used to distribute Ds insertions. Global, regional, and local insertion site trends were examined. We show that Ds transposed to both linked and unlinked sites and displayed a nonuniform distribution on the genetic map around the donor r1-sc:m3 locus. Comparison of Ds and Mutator insertions reveals distinct target preferences, which provide functional complementarity of the two elements for gene tagging in maize. In particular, Ds displays a stronger preference for insertions within exons and introns, whereas Mutator insertions are more enriched in promoters and 59-untranslated regions. Ds has no strong target site consensus sequence, but we identified properties of the DNA molecule inherent to its local structure that may influence Ds target site selection. We discuss the utility of Ds for forward and reverse genetics in maize and provide evidence that genes within a 2-to 3-centimorgan region flanking Ds insertions will serve as optimal targets for regional mutagenesis.