A UNIQUELY CALCIFIED BROWN ALGA FROM HAWAII: NEWHOUSIA IMBRICATA GEN. ET SP. NOV. (DICTYOTALES,PHAEOPHYCEAE)1

An encrusting brown alga from subtidal habitats around the island of Oahu (Hawaiian Islands) represents only the second genus of the class Phaeophyceae to form calcium carbonate, which it deposits primarily as both extracellular and intracellular aragonite, admixed with small (3.3%) amounts of calcite. Plants form expanses 15–100+ cm in extent consisting of horizontally aligned imbricating tiers of distromatic blades 1–4 mm in diameter that are separated from one another by cementing layers of extracellular aragonite, the tiers forming stacks of dozens of laminae and anchored to coral substrata by a basement layer that adheres tightly without haptera or rhizoids. The hypodermal layer of each blade consists of lightly pigmented rectilinear cells bearing either one or two smaller deeply pigmented epidermal cells in cross‐sectional profiles and three or four in long‐sectional profiles, the cells of both layers becoming encased in rigid carbonate skeletons laid down in their outer wall matrices. The successive tiers become stacked by either overgrowing marginal proliferations or new blade primordia that arise from the hypodermal layer of surface laminae and initially spread centrifugally by means of continuous marginal meristems. Neither plurilocular nor unilocular reproductive structures are known. The alga is described as the new genus and species Newhousia imbricata Kraft, G.W. Saunders, Abbott et Haroun and is assigned on the basis of small subunit rDNA gene sequence analyses to the order Dictyotales, family Dictyotaceae, within a strongly supported monophyletic clade that includes Distromium, Lobophora, and Zonaria.     

Gracilaria species (Gracilariaceae, Rhodophyta) from southeastern Australia, including a new species, Gracilaria perplexa sp. nov.: Morphology, molecular relationships and agar content

Select species of the agarophyte Gracilaria were studied from southeastern Australia. The morphology and anatomy of species is described and molecular relations are inferred based on plastid and mitochon‐drial DNA sequence data. Agar yields and qualities are determined for each species. Gracilaria chilensis, found in Tasmania and Victoria, is morphologically and molecularly similar to G. chilensis from New Zealand and Chile and has low agar yields of 11–16%. Gracilaria cliftonii from Victoria, has high crude agar yield (52%) and is molecularly uniform. Gracilaria perplexa sp. nov., known only from Botany Bay, New South Wales, has an agar yield of 39%. The agar of G. perplexa is unusual in requiring the addition of 0.1 mol L^?1 NaCl for alcohol precipitation and is cold‐water (25°C) soluble because of the very high sulfate ester content. Molecular phylogeny shows that G. perplexa is closely related to Gracilaria preissiana from western Australia, but differs from the latter in its reduced branching and narrower more terete axes.     

Differential antibacterial activity of nitric oxide from the immunological isozyme of nitric oxide synthase transduced into endothelial cells.

Primary cultures of endothelial cells, grown on the three-dimensional matrix Gelfoam where they take on the morphology of these cells in vivo, were found to phagocytose Staphylococcus aureus and two strains of Escherichia coli. The phagocytosis was independent of opsonization, although once opsonized, these bacteria were phagocytosed by endothelial cells. As cytochalsin D inhibited the internationalization of S. aureus and E. coli, the phagocytosis by endothelial cells appears to be actin-dependent. Transducing the gene for nitric oxide synthase (NOS) II into endothelial cells allowed us to determine the importance of NO(*) in host immunity against these bacteria. While the growth of S. aureus was impeded by NOS II endothelial cells, two strains of E. coli were killed by an NO(*)-dependent pathway. We conclude that endothelial cells have microbicidal mechanisms that are selective for the type of pathogen encountered.     

Synthesis and X-ray crystal structure determination of two pseudopolymorphic forms of μ-[1,2-bis(diphenylphosphino)ethane] bis [chlorogold(I)]: a digold(I) DNA binder

An improved synthetic route to the linearly coordinated digold(I) complex, μ-[1,2-bis(diphenylphosphino)ethane]bis[chlorogold(I)], is reported. This complex crystallizes in two pseudopolymorphic forms from a chloroform/methylene chloride solution; the crystal and molecular structures of both are discussed and compared. In both crystal forms the potentially chelating diphenylphosphinoethane (dppe) ligand instead coordinates to two separate gold atoms. The coordination environment of each gold atom is linear in both pseudopolymorphs and the structures display normal goldchloride and goldphosphorus bond distances. On the molecular level, the pseudopolymorphs differ fundamentally by a twist about one of the gold phosphorous bonds with the phosphorous atoms of the dppe ligand adopting a transoid orientation relative to one another in both polymorphs. These conformations thus place the intramolecular gold atoms 6 Å apart and preclude intramolecular AuAu bonding interactions. As has been observed for related gold(I) complexes there are short intermolecular AuAu contacts of the order of 3.2 Å present in both structures. The conformational flexibility of the gold complex relative to its observed biological activity as a DNA binder is discussed.     

THE MORPHOLOGY AND DEVELOPMENT OF SOME PROMINENTLY STALKED SOUTHERN AUSTRALIAN HALYMENIACEAE (CRYPTONEMIALES,RHODOPHYTA). II. THE SPONGE-ASSOCIATED GENERA THAMNOCLONIUM KUETZING AND CODIOPHYLLUM GRAY1

Three members of the red algal family Halymeniaceae (Thamnoclonium dichotomum (J. Ag.) J. Ag., Codiophyllum flabelliforme (Sond.) Schmitz, and C. decipiens (J. Ag.) Schmitz) are investigated. All are endemic to southern and southwestern Australia, possess basal stalks of substantial size and firmness, and are consistently associated with specific sponge taxa. In each case, the sponges are bonded by collagen-like fibrils to the host cuticle without modifying the algal tissue at the ultrastructural level. Secondary cortication and prominent growth rings occur in the stalks of all three species, and in each the pit plugs between cells become wider, more convoluted and less electron dense with increasing distance from the surface. Such pit plugs are apparently a unique attribute of the stalked Halymeniaceae. The three species share pit plug, sponge association and stalk morphological features but are not otherwise closely related, as they actually represent three distinct genera.