(G and J) Associates of the majority class (90%) of germline-clone embryos; (H and I) representatives of the minority class (10%) of germline-clone embryos. Wild-type (ACF) and germline-clone (GCL) embryos were stained with BODIPY FL-phallacidin (green) and propidium iodide (reddish) (ACE and GCK) or with BODIPY FL-phallacidin alone (F and L). (ACD and GCJ) Sagittal optical sections; anterior is to the Defactinib hydrochloride left and dorsal is up. The septins are a family of proteins that were first discovered in but now appear to be ubiquitous in fungi and animals (for review, see Cooper and Kiehart, 1996 ; Longtine (Frazier (Field (Hartwell, 1971 ; Longtine (Neufeld and Rubin, 1994 ) are defective in cytokinesis. In addition, microinjection of antiseptin antibodies can cause cleavage-furrow regression in mammalian cells (Kinoshita and mammals, the septins are also localized in ways that suggest noncytokinesis functions. For example, they are highly concentrated in nondividing neuronal cells (Neufeld and Rubin, 1994 ; Fares mutant embryos, cells of the embryonic central nervous system, which have no detectable Pnut protein (the maternal contribution having been depleted by that time), also have no detectable Sep1 or Sep2 (Fares mutant embryos survive until pupation. This survival seemed likely to result from a maternal contribution of Pnut mRNA and/or protein that was deposited in the oocyte during oogenesis. Thus, we used two different methods to deplete this maternal contribution. Surprisingly, the results suggest that some cell-division events in do not require septin function, that there is functional differentiation among the septins, or both. MATERIALS AND METHODS The wild-type stock used in this study Defactinib hydrochloride was Canton S. Other stocks and genetic crosses used are explained in Table ?Table1. 1. Table 1 stocks used in this study is coding region (Neufeld and Rubin, 1994 ). This lethal mutation is usually recessive to the wild-type allele carried on the was generated by excision of the P element of the coding region (Neufeld and Rubin, 1994 ). coding region under the control of the promoter (Neufeld and Rubin, 1994 ).? d?Mature adults of this genotype were produced by intermittently inducing transcription from your transgene by a 2-h warmth shock (at 37C) once per day.? e?gene and flanking sequences.? To examine living embryos and cuticles, embryos were dechorionated in 50% bleach, washed three times in 0.1% Triton X-100, and submerged in halocarbon oil. Embryos at syncytial blastoderm stage were selected and mounted in defined locations on a Petriperm dish (Bachofer, Reutlingen, Germany) at 23C. The embryos were then photographed at 10- to 15-min intervals for 3 h. After 2 to 3 3 days, the Defactinib hydrochloride coverslip was removed, and cuticles were prepared by washing each embryo individually in 0.1% Triton X-100, mounting on a slide with 1:1 Hoyer’s reagent:lactic acid (Wieschaus and Nsslein-Volhard, 1986 ), and heating at 65C overnight. Embryos and cuticles were observed and photographed with a Nikon Optiphot-2 microscope. For fluorescent staining, embryos were allowed to develop at 25C for 1 to 4 h. They were then dechorionated in 50% bleach, washed three times with 0.1% Triton X-100 in PBS, and fixed wing one of the following protocols. For visualization of F-actin and nuclei by the use of BODIPY FL-phallacidin and propidium iodide (Molecular Probes, Eugene, OR), embryos were resuspended in a vial made up of 1 ml of heptane and 1 ml of 37% formaldehyde and swirled for 5 min. The heptane and formaldehyde were replaced with 0.1% Triton X-100 in PBS, and embryos were devitellinized by hand (Theurkauf, 1992 ) and processed as explained by Defactinib hydrochloride Orsulic and Peifer (1994) . For visualization of Pnut and Sep1 by immunofluorescence, embryos were fixed as explained by Cox (1996) , devitellinized by shaking in 1:1 methanol:heptane, and stained as explained by Peifer (1996) . For visualization of anillin, embryos were fixed as explained above for visualization of F-actin, devitellinized either by hand or in 1:1 methanol:heptane, incubated for 2 h in 1% Triton X-100 in PBS, and stained as explained by Field and Alberts (1995) . For visualization of Pnut, anillin, and tubulin in ovaries, isolated ovaries were fixed for 20 min in 1% formaldehyde in PEM [0.1 M piperazine-LSM 410 confocal microscope. For Western-blot analyses, embryos were dechorionated in 50% bleach, washed three times in 0.1% Triton X-100, crushed in 1.2 Laemmli buffer (Laemmli, Defactinib hydrochloride 1970 ) by the use of a Teflon pestle and microfuge tube, boiled for 5 min, and centrifuged in a microfuge. The supernatants were resolved on 10% SDS-polyacrylamide gels, blotted to a nitrocellulose membrane (Schleicher & Schuel, Keene, NH), and stained with antibody 4C9 (used at 1:30), KEKK (used at 0.0005 mg/ml), or monoclonal anti-Bicaudal D (used at 1:50; Suter and Steward, 1991 ) as explained by Peifer (1993) . Detection was by the ECL chemiluminescence system (Amersham, Arlington Heights, IL). RESULTS Occurrence of Stem-cell and Cystoblast Divisions in the Absence of Pnut Homozygous null mutant embryos survive until the pupal stage (Neufeld and Rubin, 1994 ). To inquire whether such embryos survive early development because of maternally contributed product, and thus to explore septin function during embryogenesis, we used the FLP-DFS system TUBB3 (Chou and Perrimon, 1996 ) to.