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Cnox-2 is a HOM/HOX homeobox gene that we have identified in the simple metazoan Hydra vulgaris (Cnidaria: Hydrozoa). Cnox-2 is most closely related to anterior members of the Antennapedia gene complex from Drosophila, with the greatest similarity to Deformed. The Cnox-2 protein is expressed in the epithelial cells of adult hydra polyps in a region-specific pattern along the body axis, at a low level in the head and at a high level in the body column and the foot. The expression pattern of Cnox-2 is consistent with a role in axial pattern formation. Alteration of hydra axial patterning by treatment with diacylglycerol (DAG) results in an increase of head activation down the body column and in a coordinate reduction of Cnox-2 expression in epithelial cells in 'head-like' regions. These results suggest that Cnox-2 expression is negatively regulated by a signaling pathway acting through protein kinase C (PKC), and that the varying levels of expression of Cnox-2 along the body axis have the potential to result in differential gene expression which is important for hydra pattern formation.

Abstract:  A gene encoding a receptor protein-tyrosine kinase closely related to the vertebrate insulin receptor has been identified in the Cnidarian Hydra vulgaris. The gene is expressed in both epithelial layers of the adult polyp. A particularly high level of expression is seen in the ectoderm of the proximal portions of the tentacles and in a ring of ectodermal cells at the border between the foot basal disk and body column. The expression pattern of the gene in asexual buds is dynamic; expression is high throughout the newly emerging bud but the area of high expression becomes restricted to the apex as the bud lengthens. When the bud begins hypostome and tentacle formation, a high level of expression appears at the bases of the emerging tentacles. Finally, a ring of high expression appears just above the foot of the bud, completing the pattern seen in the adult polyp. The presence of this receptor and its pattern of expression suggested that an endogenous molecule related to insulin plays a role in regulating cell division in the body column and in differentiation of the tentacle and foot cells in Hydra, with the switch between the two being determined by the level of the receptor. Treatment of Hydra polyps with mammalian insulin caused an increase in the number of ectodermal and endodermal cells undergoing DNA synthesis.

Humid tropical regions of Costa Rica have ideal environmental conditions for vigorous weed growth. Vegetation management before and after planting requires more time and resources than any other activity in small-scale maize (Zea mays L.) production. No-tillage vegetation management systems tested were superior to traditional no-tillage or mechanised systems. Insect damage to maize from Diabrotica balteata Leconte, Spodoptera frugiperda (J. E. Smith), Cyrtomenus bergi Froeschner and Phyllophaga spp. was significantly less with no-tillage in contrast to ploughed systems.