*Nemerteans (ribbon worms) and phoronids (horseshoe worms) are closely related lophotrochozoans-a group of animals including leeches, snails and other invertebrates. Lophotrochozoans represent a superphylum that is crucial to our understanding of bilaterian evolution. However, given the inconsistency of molecular and morphological data for these groups, their origins have been unclear. Here, we present draft genomes of the nemertean Notospermus geniculatus and the phoronid Phoronis australis, together with transcriptomes along the adult bodies. Our genome-based phylogenetic analyses place Nemertea sister to the group containing Phoronida and Brachiopoda. We show that lophotrochozoans share many gene families with deuterostomes, suggesting that these two groups retain a core bilaterian gene repertoire that ecdysozoans (for example, flies and nematodes) and platyzoans (for example, flatworms and rotifers) do not. Comparative transcriptomics demonstrates that lophophores of phoronids and brachiopods are similar not only morphologically, but also at the molecular level. Despite dissimilar head structures, lophophores express vertebrate head and neuronal marker genes. This finding suggests a common origin of bilaterian head patterning, although different heads evolved independently in each lineage. Furthermore, we observe lineagespecific expansions of innate immunity and toxin-related genes. Together, our study reveals a dual nature of lophotrochozoans, where conserved and lineage-specific features shape their evolution. Articles NaTure eCOLOgy & evOLuTiONphoronids, ectoprocts and brachiopods, although the position of ectoprocts is questionable under a sensitivity analysis. Our results clearly show that lophotrochozoans have a different evolutionary history than other spiralians (or platyzoans), such as flatworms and rotifers. In particular, lophotrochozoans retain a basic bilaterian gene repertoire, which is probably lost in ecdysozoans and other spiralian lineages. Unexpectedly, genes specifically expressed in lophophores of phoronids and brachiopods are strikingly similar to those employed in vertebrate head formation, although novel genes, expanded gene families and redeployment of developmental genes also contribute to the unique molecular identity of lophophores. Furthermore, we provide examples of lineage-specific genomic features in lophotrochozoans, such as the expansion of innate immunity and toxin-related genes. Taken together, our study reveals the dual nature of lophotrochozoan genomes, showing both conservative and innovative characteristics during their evolution.

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A type of nondiffracting narrow light beam that propagates across a long range with a narrow beamwidth is presented. This beam is formed by a distorted concave spherical wave front that can be generated by a Galilean transmitting telescope with an eyepiece that has a spherical aberration. We observed an unusual image with a striped pattern in the laser beam's atmospheric backscatter that provided an opportunity to examine this effect. We demonstrate the mechanism of the generation and the characteristics of the long-range nondiffracting beam. The results show that a nondiffracting core beam with a width of the order of millimeters with a propagation distance of the order of a kilometer is generated by a 10-cm-diameter laser beam.

The life history of the cumacean Nippoleucon hinumensis was investigated in the Seto Inland Sea of Japan from August 1998 to February 2002. The population produced 1 generation per year and recruitment of offspring occurred in April. The post-marsupial period consisted of 8 instars in males and 9 (plus generally 2 repeated instars) in females. Post-marsupial development up to the 4th instar (2nd juvenile stage) was characterized by periodic molting at intervals of 10 d, slow growth rate, and suppression of sexual dimorphism. Thereafter, the juveniles entered a long-term summer diapause from mid-May to early December, during which the ambient seawater temperature ranged from 15 to 28°C. Ninety-nine % of the population during the diapause were at the 2nd juvenile stage, and 1% were at the 1st juvenile stage. In December, the cumaceans resumed growth, characterized by a fortnightly molt cycle, until the females began to incubate the first brood in late February. Each molting was highly synchronized among individuals and phased with the lunar cycles. After the end of the summer diapause, sexual dimorphism became apparent, with ovigerous females becoming about 1.2 times larger than adult males. After release of manca larvae in early April, most females incubated a second brood in late April, and then rapidly disappeared due to mortality probably caused by high water temperature. Clutch size was 57.9 ± 9.4 for the first brood and 42.4 ± 7.3 for the second.

The emergence of an intertial midge was investigated at a site on the coast of the Inland Sea of Japan. The population emerging at this site was drawn from a single species of the genus Clunio, probably C. tsushimensis. Emergence was not synchronized with the day-night cycle, but with the tidal cycle. Moreover, the pattern of synchrony changed with season. A bimodal phase appeared in midwinter; but the pattern of synchrony shifted gradually, during January and February, from morning low tides to afternoon low tides, and a unimodal phase appeared in March. This pattern--i.e., synchrony with afternoon low tides--lasted until early October. In mid-October, the synchrony shifted to the morning low tides. Only a brief bimodal phase appeared in autumn. The phase modality was clearly correlated with the height of tides; i.e., when the low waters in a day were very different in height, emergence was synchronized only with the lower one (April to December). During January and February, the higher low tide, as well as the lower low tide, recedes considerably. The exposure of the larval habitat at the higher low tide may stimulate emergence, resulting in bimodal phases in midwinter. But the unimodal pattern in March cannot be accounted for by a simple synchrony with lower low tide, or with exposure of the larval habitat to the air; the day-night cycle not only would be one of the zeitgebers of the tidal rhythm in every season, but also must participate in the expression of the unimodal phase in spring. Furthermore, the number of midges that emerged each day fluctuated with a semilunar cycle with the season. The phase of this rhythm would be shifted by water temperature.