<i>C. elegans</i> gonad, F-series prostaglandin structures, and PUFA metabolism pathways.

<p>(A) The <i>C. elegans</i> hermaphrodite reproductive tract. A differential interference contrast (DIC) image of an adult hermaphrodite is shown above with a diagram of half the uterus below. Males inject sperm through the vulva (V) into the uterus. Sperm become motile by extending a pseudopod and crawl around fertilized embryos (E) toward the spermatheca (S, yellow outline). Oocytes (O) enter the spermatheca during oocyte maturation and ovulation. The uterus is divided into 3 zones for quantification of sperm distribution. Scale bar, 0.1 mm. (B) Human F-series prostaglandin structures showing carbon numbering and important energy-induced cleavage sites characteristic of F-series prostaglandins. z1 cleavage causes loss of 44 Da from the parent ion and z2 cleavage, together with methyl terminal loss, generates the product ion <i>m/z 193</i>. Prostaglandin precursors for each class are shown in parentheses. (C) Diagram of <i>C. elegans</i> PUFA synthesis pathways. <b>Δ</b>9 and <b>Δ</b>12 desaturase activities generate substrates for the n3 desaturase FAT-1, the <b>Δ</b>6 desaturase FAT-3, and the <b>Δ</b>5 desaturase FAT-4 <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003271#pgen.1003271-Watts1" target="_blank">[31]</a>. Fatty acids are abbreviated as in 20:4n6, which has 20 carbons with four double bonds, the first occurring at the n6 position. LA, linoleic acid; ALA, linolenic acid; GLA, <b>γ</b>-linolenic acid; STA, stearidonic acid; DGLA, dihomo-<b>γ</b>-linolenic acid; O3AA, omega-3 arachidonic acid; AA, arachidonic acid; EPA, eicosapentaenoic acid.