Allorecognition maturation in the broadcast-spawning coral Acropora millepora

Many sessile marine invertebrates discriminate self from non-self with great precision, but maturation of allorecognition generally takes months to develop in juveniles. Here, we compare the development of allorecognition in full-sibling, half-sibling and non-sibling contact reactions between newly settled juveniles of the broadcast-spawning coral Acropora millepora on the Great Barrier Reef (Australia). Absence of a rejection response showed that A. millepora lacks a mature allorecognition system in the first 2 months post-settlement. From thereon, incompatibilities were observed between juveniles, their level of relatedness (i.e. full-, half- and non-sibling status) governing the rate of allorecognition maturation. All contact reactions between non-siblings resulted in rejections by 3 months post-settlement, whereas the expression of allorecognition took at least 5 months between half-siblings and longer than 13 months for some full-siblings. Approximately 74 % of fused full-siblings (n = 19) persisted as chimeras at 11 months, thus maturation of allorecognition in this spawning coral appeared to be slower (>13 months) than in brooding corals (∼4 months). We hypothesize that late maturation of allorecognition may contribute to flexibility in Symbiodinium uptake in corals with horizontal transmission, and could allow fusions and chimera formation in early ontogeny, which potentially enable rapid size increase through fusion

The Correspondence between Sophie Germain and Carl Friedrich Gauss

Published and discussed here is the correspondence between Sophie Germain and Carl Friedrich Gauss. The mathematical notes enclosed in her letters are published for the first time. These notes in which she submitted some of her results, proofs and conjectures to Gauss for his evaluation, were inspired to her by the study of the Disquisitiones Arithmeticae. The interpretation of these mathematical notes, not only shows how she went deeply into Gauss's treatise and mastered it long before any other mathematician, but also, more importantly, that she got interesting results in the theory of power residues that had never previously been attributed to her