PMC

Sandflies infected with Leishmania infantum from US foxhounds, showing blocked stomodeal valve. Development of L. infantum (MCAN/US/2001/ FOXYMO1) in laboratory-reared Lutzomyia longipalpis sandflies led to stomodeal valve blockage 10–13 days after infection. A) Dissected gut of infected sandfly, showing stomodeal valve (cardia) obstructed by Leishmania parasites (dashed box). Foregut removed during dissection and parasites entangled by flagella are visible. Original magnification ×10. B) Parasites obstructing stomodeal valve and parasite-secreted plug (dashed box). Original magnification ×40. C) Parasite plug dissected from the stomodeal valve, showing metacyclic promastigote parasites attached to plug (arrow), as well as free-swimming parasites (arrowheads). Original magnification ×100 with oil.

Transcriptional control of stomodeal bra expression. A) Endodermal and stomodeal expression of bra during blastula stage. While endodermal bra can be seen at early blastula, stomodeal bra expression (marked by “*”) starts later and can be observed at 20h early mesenchyme blastula stage. B) Diagram of assay protocol testing for direct nodal targets by temporarily blocking Nodal signaling. Nodal signaling pathway inhibitor SB-431542 (SB) was added to cultures of sea urchin embryos at 24h, and gene expression was analyzed at 28h. C, QPCR assessment of effects of temporary SB treatment at indicated concentrations. This treatment significantly reduced the expression levels of nodal and not, but had small effects on bra levels. D, WMISH observations of effects of treatment with SB. Stomodeal bra expression is wiped out by 4h SB treatment, but endodermal bra expression is not affected; foxa stomodeal expression is diminished and endodermal expression is not affected. E) Effect of ets4 plus sip1 MASO on early bra expression. WMISH shows that ets4 and sip1 are required for proper timing expression of stomodeal bra expression; ets4/sip1 MASOs resulted in abnormal ectodermal bra expression during the early blastula stage. lv—lateral view; av— apical view. * marks stomodeal bra or foxa. All embryos in lateral or vegetal views were shown with the oral ectoderm facing left.

Phase contrast light microscopy showing a mass of promastigotes attached to the stomodeal valve. Bar represents 50 μm.

Development of the stomodeal nervous system in Hypsibius dujardini. Developmental series from earliest (A) to latest (D) embryonic stages. (A-D) CLSM projections showing the stomodeal nervous system (selectively colored in orange). Orientation as in (D′). Anti-acetylated α-tubulin immunolabeling. (A′-D′) Volume rendering of the corresponding structures. (A″-D″) Diagrammatic representation of the stomodeal nervous system in lateral view. Stomodeal commissures are numbered (I to IV). Note that neurons of the third stomodeal commissure (solid arrowheads) arise first (A) and project axons toward cells of the first commissure (hollow arrowheads), which only closes later in development (arrows in (C-C″), (D-D″)). The buccal sensory organs (asterisks in (B-B″), (C-C″), (D-D″)) contribute to the second commissure. Abbreviations: br, brain cells; cb, developing central brain neuropil (arising from a single commissure); D, dorsal; M, median; D, dorsal. Scale bars: (A-D), (A′-D′), 5 μm.