A cysteine-clamp gene drives embryo polarity in the midge Chironomus

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Science  29 May 2015:
Vol. 348, Issue 6238, pp. 1040-1042
DOI: 10.1126/science.aaa7105
  • Fig. 1 Bicoid in dipteran families.

    Indicated instances of missing bicoid orthologs are based on genome sequences; tree is based on molecular phylogeny [see (22) and species list (23)], and cyclorrhapha clade, with bicoid, is indicated (light blue). Ma, millions of years ago.

  • Fig. 2 Panish mRNA is enriched in the anterior embryo and encodes a C-clamp protein.

    (A) Differential expression of transcripts based on RNA sequencing data from anterior and posterior embryo halves. Red, score > |2.5| and P < 0.05; blue, putative germ cell or germ plasm components. (B) RNA in situ hybridizations of early embryos for panish. Anterior is to the left; scale bar, 10 μm. (C) C-clamp region of panish aligned with Pangolin sequences from C. riparius (Cri), D. melanogaster (Dme), Anopheles gambiae (Aga), and Tribolium castaneum (Tca). Gray numbers, residues not shown; red, conserved cysteine residues; blue, residue similarity. Amino acid abbreviations: A, Ala; C, Cys; D, Asp; E, Glu; F, Phe; G, Gly; H, His; I, Ile; K, Lys; L, Leu; M, Met; N, Asn; P, Pro; Q, Gln; R, Arg; S, Ser; T, Thr; W, Trp; Y, Tyr. (D) The panish locus. Homology is based on reciprocal-best-BLAST between C. riparius transcripts and D. melanogaster genes. Longest ORFs (shaded) and orientation (arrowheads) are indicated.

  • Fig. 3 Panish is required to establish AP polarity in C. riparius.

    (A) Inverted dark-field image of wild-type first-instar larval cuticle. A, abdominal segment; T, thoracic segment. (B) Panish RNAi cuticle of symmetrical double-abdomen larva. Scale bars, 30 μm. (C) Comparison of panish and Cri-zap3 RNAi phenotypes and rescue of the panish RNAi phenotype by anterior injection of panish mRNA. *Note: In the third column, “wild type” includes 13 partial rescues (deformed head structures; fig. S6, B to D). N.S., P > 0.05; Eba-bcd from (6).

  • Fig. 4 Cri-cad and Cri-tll are regulated by panish, and Cri-tll is required to establish AP polarity.

    (A to D) Staining for Cri-cad [(A) and (C)] and Cri-tll [(B) and (D)] with RNA in situ hybridization in wild-type and panish RNAi embryos. Black arrowheads indicate posterior pole cells. (E) Eye spots indicated on live wild-type and Cri-tll RNAi embryos. (F and G) Cuticle preparations of a wild-type larval head (F) and a Cri-tll RNAi larva (G). Dashed lines indicate approximate plane of symmetry. Anterior is to the left in all panels; scale bars, 10 μm [except (G), 30 μm].

Supplementary Materials

  • A cysteine-clamp gene drives embryo polarity in the midge Chironomus

    Jeff Klomp, Derek Athy, Chun Wai Kwan, Natasha I. Bloch, Thomas Sandmann, Steffen Lemke, Urs Schmidt-Ott

    Materials/Methods, Supplementary Text, Tables, Figures, and/or References

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    • Materials and Methods
    • Figs. S1 to S10
    • References
    Table S1
    Table S2

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