Co-authored with Kathryn Anderson a Nature paper showing dorsal-ventral pattern information is stored as maternal mRNA in the Drosophila embryo.
On 20 September 1984, Nüsslein-Volhard, together with Kathryn V. Anderson, published a pivotal paper in Nature titled "Information for the dorsal-ventral pattern of the Drosophila embryo is stored as maternal mRNA."
This study demonstrated that the polarity distinguishing the future back (dorsal) from the belly (ventral) side of the fly embryo is not determined by the embryo's own genome after fertilization, but is instead pre-programmed by messenger RNA molecules deposited into the egg by the mother during oogenesis. This was a crucial conceptual advance in understanding maternal-effect genes — genes whose products, supplied by the mother, direct the earliest steps of embryonic patterning before the embryo's own genes become active.
The discovery helped establish the broader principle that early development is orchestrated by a hierarchy of maternal and zygotic genetic information, a framework that transformed developmental biology. It also provided essential groundwork for later identification of components of what would become known as the Toll signaling pathway, later found to be conserved in mammalian innate immunity — a discovery that itself earned other scientists a Nobel Prize. Nüsslein-Volhard's meticulous experimental work in this era cemented her reputation as one of the preeminent developmental geneticists of her generation.