QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online 6 October 2004
doi: 10.1242/dev.01423

This Article Summary Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Sasson, I. E. Articles by Stern, M. J. Search for Related Content PubMed PubMed Citation Articles by Sasson, I. E. Articles by Stern, M. J. Social Bookmarking                         What's this?

FGF and PI3 kinase signaling pathways antagonistically modulate sex muscle differentiation in C. elegans

Yale University School of Medicine, Department of Genetics, I-354 SHM, PO Box 208005, New Haven, CT 06520-8005, USA

View larger version (98K): [in a new window]   Fig. 1. Phenotypic effects of hyperactivated EGL-15. (A,B) ccIs4251 [Pmyo-3::GFP]; soc-2(n1774) animals are egg-laying proficient, and animals display a normal number of embryos in the uterus. (C,D) soc-2(n1774); ayIs15 [egl-15(neu*); Pmyo-3::GFP] animals display a severe Egl phenotype, with an increased number of eggs retained in the uterus. (E,F) soc-2 + / + mIs11; ayIs15/+. EGL-15 remains hyperactivated in these integrated lines as indicated by the dominant Clr phenotype revealed when the recessive soc-2 suppressing mutation is heterozygous. ccIs4251/+; soc-2 + / + mIs11 animals do not display a Clr phenotype (data not shown). mIs11 [Pmyo-2::GFP] was used to identify heterozygous cross progeny. All animals were photographed 30 hours after late L4. Scale bar: 100 µm in A,C,E; 50 µm in B,D,E. *, eggs. Arrow indicates clear fluid in the pseudocoelomic space.

View larger version (27K): [in a new window]   Fig. 2. Egg-laying index is an indicator of sex muscle functionality. The egg-laying index=(number of laid eggs)/(number of laid eggs + number of unlaid eggs). Mean and standard error for 30 animals are displayed.

View larger version (47K): [in a new window]   Fig. 3. Absence of sex muscles in soc-2; ayIs15 [egl-15(neu*)] animals. Muscle cells are visualized with rhodamine-phalloidin and muscle nuclei with a Pmyo-3::GFP reporter. Broad bands of body wall muscles can be seen just below the focal plane. Sex muscles are labeled in A. The control strains, ccIs4251 [Pmyo-3::GFP] (A) and ccIs4251; soc-2(n1774) (B), have wild-type sex muscles and body wall muscles. (C) soc-2(n1774); ayIs15 [egl-15(neu*); Pmyo-3::GFP]. SM descendants in these animals do not stain with rhodamine-phalloidin and fail to express Pmyo-3::GFP. The rhodamine-phalloidin staining and the pattern of Pmyo-3::GFP expression remains unchanged in the surrounding body wall musculature. (D) soc-2(n1774) ayIs18 [egl-15(5B*)]; (E) soc-2(n1774); ayIs27 [egl-15(5A*)]. All animals are positioned in a ventrolateral view with the head oriented towards the left. A broken line in A represents the position of the vulva. um1, uterine muscles 1; vm1, vulval muscles 1; vm2, vulval muscles 2. The um2s are very broad and contain loosely organized actin filaments. Using ccIs4656 [P16Nde::GFP], which can also be used to visualize both vms and ums in the absence of ayIs15, there are no observable sex muscles in an ayIs15 background. The vulval musculature was scored because of the poor reproducibility of um visualization by either technique. Scale bar: 10 µm.

View larger version (77K): [in a new window]   Fig. 4. Visualization of sex muscles with -EGL-15 antibodies. (A,B) ccIs4251; ayIs29 [egl-15(+)] animals display wild-type sex muscle morphology and positions. EGL-15 expression is restricted to the vm1s in differentiated hermaphrodite sex muscles. (C,D) SM descendants in soc-2; ayIs15 animals. Red, -EGL-15 immunoreactivity; green, muscle nuclei visualized using Pmyo-3::GFP transgenic arrays. A,B, ventral view; C,D, lateral view. All animals are positioned with the tail oriented towards the right. Arrowheads indicate the position of the vulva. Scale bar: 50 µm in A,C; 10 µm B,D.

View larger version (19K): [in a new window]   Fig. 6. Hyperactivation of EGL-15 results in multiple M lineage defects. (A) The cell lineage of the M mesoblast. M divides along the dorsoventral axis; the two M.x daughters divide along the left/right axis. The remaining divisions in the lineage are oriented along the anteroposterior axis. d, dorsal; v, ventral; l, left; r, right; a, anterior; p, posterior; bm, body wall muscle; dcc, dorsal coelomocyte; SM, sex myoblast (adapted from Sulston and Horvitz, 1977). (B) The effect of EGL-15 hyperactivation on SM positioning, presence of dorsal coelomocytes and orientation defects in early M lineage cell divisions. SM positions are scored with respect to the hypodermal Pn.p cell metric. SMs in wild-type animals are centered at P6.p, indicated by the arrow; the blue rectangle represents the positions of normal SMs. Each full SM distribution is represented by a box-and-whisker plot, where the box extends over the distribution of the central 50% of the SMs and the line within the box is at the median position. Whiskers extend anteriorly and posteriorly to data points up to 75% of the length of the box. SMs that fall outside the box and whiskers are represented by an individual hash mark (see Material and methods). Red circles indicate dorsally positioned SMs. ayIs16 was used in place of ayIs15 for technical strain construction considerations. A similar survey of SMs in ayIs15 hermaphrodites gave a distribution consistent with that seen for ayIs16. At least 30 SMs were scored for each SM distribution and at least 30 animals were scored for dorsal coelomocyte and M-lineage cell-division defects.

View larger version (29K): [in a new window]   Fig. 5. Expression of egl-15(neu*) in muscle precursor cells inhibits muscle development. (A) hlh-1(cc450) homozygote; (B) Phlh-1::egl-15(neu*) transgenic animal displaying a lumpy-dumpy phenotype; (C) Phlh-1::egl-15(neu*K-A) kinase defective control transgenic animal. Transgenic EGL-15 expression was confirmed in all strains by immunohistochemical analysis (data not shown). All animals are photographed 14 hours after hatching. Scale bar: 50 µm.

View larger version (114K): [in a new window]   Fig. 7. Suppression of the EGL-15(neu*)-induced sex muscle differentiation defect by activating the PI3 kinase signaling pathway. (A) ccIs4251; soc-2(n1774). (B) soc-2(n1774); ayIs15. (C) daf-18(nr2037lf) soc-2(n1774); ayIs15. (D) soc-2(n1774); pdk-1(mg142gf) ayIs15. (E) soc-2(n1774); akt-1(mg144gf); ayIs15. (F) daf-16(mg54lf); soc-2(n1774); ayIs15. All animals are positioned in a ventrolateral view with the head oriented to the left. Red, rhodamine-phalloidin staining; green, Pmyo-3::GFP expression. Scale bar: 10 µm.

View larger version (14K): [in a new window]   Fig. 8. Model for EGL-15 and PI3 kinase signaling pathways in muscle differentiation.

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati

Twitter