Area and the rapid radiation of Hawaiian Bidens (Asteraceae)

Aim To estimate the rate of adaptive radiation of endemic Hawaiian Bidens and to compare their diversification rates with those of other plants in Hawaii and elsewhere with rapid rates of radiation. Location Hawaii. Methods Fifty‐nine samples representing all 19 Hawaiian species, six Hawaiian subspecies, two Hawaiian hybrids and an additional two Central American and two African Bidens species had their DNA extracted, amplified by polymerase chain reaction and sequenced for four chloroplast and two nuclear loci, resulting in a total of approximately 5400 base pairs per individual. Internal transcribed spacer sequences for additional outgroup taxa, including 13 non‐Hawaiian Bidens, were obtained from GenBank. Phylogenetic relationships were assessed by maximum likelihood and Bayesian inference. The age of the most recent common ancestor and diversification rates of Hawaiian Bidens were estimated using the methods of previously published studies to allow for direct comparison with other studies. Calculations were made on a per‐unit‐area basis. Results We estimate the age of the Hawaiian clade to be 1.3–3.1 million years old, with an estimated diversification rate of 0.3–2.3 species/million years and 4.8 × 10^?5 to 1.3 × 10^?4 species Myr^?1 km^?2. Bidens species are found in Europe, Africa, Asia and North and South America, but the Hawaiian species have greater diversity of growth form, floral morphology, dispersal mode and habitat type than observed in the rest of the genus world‐wide. Despite this diversity, we found little genetic differentiation among the Hawaiian species. This is similar to the results from other molecular studies on Hawaiian plant taxa, including others with great morphological variability (e.g. silverswords, lobeliads and mints). Main conclusions On a per‐unit‐area basis, Hawaiian Bidens have among the highest rates of speciation for plant radiations documented to date. The rapid diversification within such a small area was probably facilitated by the habitat diversity of the Hawaiian Islands and the adaptive loss of dispersal potential. Our findings point to the need to consider the spatial context of diversification – specifically, the relative scale of habitable area, environmental heterogeneity and dispersal ability – to understand the rate and extent of adaptive radiation.     

Utilization of phosphate diester by the marine diatom Chaetoceros ceratosporus

Utilization of phosphate diester (PDE) and phosphodiesterase(PDEase) production by five marine phytoplankton species wereexamined in the laboratory to evaluate the contribution of PDEto the growth of phytoplankton. Among the five marine phytoplanktonspecies tested, only Chaetoceros ceratosporus was able to usethe PDE compound, bis(p-nitrophenyl) phosphate (bis-NPP), effectivelyas a sole phosphorus source. In addition, C. ceratosporus simultaneouslyproduced both PDEase and alkaline phosphatase (APase) at almostequal activity levels under the phosphate-deficient condition.These results suggest that PDE compounds presumably play animportant role as a phosphorus source for PDEase-producing phytoplanktonin coastal environments.     

Localization of the regulatory subunit of cAMP-dependent protein kinase in Saccharomyces cerevisiae

The subcellular distribution of the regulatory subunit of cAMP-dependent protein kinase in Saccharomyces cerevisiae cells was determined by subcellular fractionation and indirect immunofluorescence microscopy using the bcy1 mutant deficient in the regulatory subunit as control. The regulatory subunit of cAMP-dependent protein kinase showing cAMP-binding activity was identified as a single protein of 50 kDa by photoaffinity labeling and immunoblotting. The regulatory subunit was concentrated in a nuclear fraction in addition to a cytoplasmic fraction. By comparison of the regulatory subunit distribution with the DNA localization, the area detected by the indirect immunofluorescence was identified as the nucleus.     

Lipopolysaccharides of Escherichia coli K12 Strains That Express Cloned Genes for the Ogawa and Inaba Antigens of Vibrio cholerae O1: Identification of O-Antigenic Factors

Structural and serological studies were performed with the lipopolysaccharide (LPS) expressed by Escherichia coli K12 strains No. 30 and No. 64, into which cosmid clones derived from Vibrio cholerae O1 NIH 41 (Ogawa) and NIH 35A3 (Inaba) had been introduced, respectively. The two recombinant strains, No. 30 (Ogawa) and No. 64 (Inaba), produced LPS that included, in common, the O-polysaccharide chain composed of an α(1 → 2)-linked N-(3-deoxy-L -glycero-tetronyl)-D -perosamine (4-amino-4,6-dideoxy-D -manno-pyranose) homopolymer attached to the core oligosaccharide of the LPS of E. coli K12. Structural analysis revealed the presence of N-(3-deoxy-L -glycero-tetronyl)-2-O-methyl-D -perosamine at the non-reducing terminus of the O-polysaccharide chain of LPS from No. 30 (Ogawa) but not from No. 64 (Inaba). Serological analysis revealed that No. 30 (Ogawa) and No. 64 (Inaba) LPS were found to share the group antigen factor A of V. cholerae O1. They were distinguished by presence of the Ogawa antigen factor B [co-existing with relatively small amounts of the Inaba antigen factor (c)] in the former LPS and the Inaba antigen factor C in the latter LPS. It appears, therefore, that No. 30 (Ogawa) and No. 64 (Inaba) have O-antigenic structures that are fully consistent with the AB(c) structure for the Ogawa and the AC structure for the Inaba O-forms of V. cholerae O1, respectively. Thus, the present study clearly confirmed our previous finding that the Ogawa antigenic factor B is substantially related to the 2-O-methyl group at the non-reducing terminus of the α(1 → 2)-linked N-(3-deoxy-L -glycero-tetronyl)-D -perosamine homopolymer that forms the O-polysaccharide chain of LPS of V. cholerae O1 (Ogawa).     

cDNA Cloning and Expression of the Plastidic Copper/Zinc-Superoxide Dismutase from Spinach (Spinacia oleracea L.) Leaves

A cDNA clone for copper/zinc-superoxide dismutase (Cu/Zn-SOD)was isolated from spinach (Spinacia oleracea L.) leaves. Itsnucleotide sequence showed that it codes for a precursor polypeptideof 222 amino acids, including the NH₂-terminal 68-residue extensionwhich corresponds to a plastidic transit peptide. Northern hybridization,using plastidic and cytosolic Cu/Zn-SOD cDNAs as the probes,revealed that these two genes are differentially expressed inthe roots and leaves of spinach. ¹Present address: Department of Biochemistry and Microbiology,Cook College, Rutgers University New Brunswick, NJ 08903-0231,U.S.A.     

Lipopolysaccharide Isolated from a New O-Antigenic Form (O13) of Vibrio parahaemolyticus

The chemical properties of a lipopolysaccharide (LPS) isolated from a new O-antigenic form (O13) of Vibrio parahaemolyticus were investigated. The LPS contained glucose, galactose, L -glycero-D -manno-heptose and glucosamine. 2-Keto-3-deoxy-octonate (KDO) was not detected in the LPS by the periodate-thiobarbituric acid test (Weissbach's reaction) under conventional hydrolysis conditions. Instead, phosphorylated KDO (X1 and X2) was found in its strong-acid hydrolysate. This sugar composition was identical to that of V. parahaemolyticus O3, O5 and O11 LPS, indicating that, based on the sugar composition, O13 LPS belongs to Chemotype III to which O3, O5 and O11 belong. In addition, structural study demonstrated the presence of KDO 4-phosphate in its inner-core region.     

Stimulative and inhibitory effects of bacteria on the growth of microalgae

Several examples of stimulative and inhibitoryeffects of bacteria on microalgal growth areintroduced, and the importance of bacteria in algalmass culture is investigated. Diatoms are often usedas live food for planktonic larvae of sea urchin andbivalves. Monodispersed Chaetoceros ceratosporum hasbeen cultivated by using clean, high nutrient content,deep seawater (DSW). However, the growth rate and cellyield of diatoms fluctuated, to relatively largeextent, with the season that DSW was collected. Whensome bacterial strains isolated from DSW were added tothe culture, diatom growth was often stimulated and arelatively constant cell yield was obtained. Anotherdiatom species, C. gracilis, was also stimulated byadding some bacterial strains to cultures. Thepositive effect of bacteria on diatoms was observednot only for planktonic species, but also on attachedspecies. A benthic diatom, Nitzschia sp., wasstimulated by a bacterial film of Alcaligenes on thesurface of the substratum. On the other hand, a strainof Flavobacterium sp. isolated from natural seawaterduring the decline period of an algal bloom had a strongalgicidal effect on the red tide plankton,Gymnodinium mikimotoi. Recent reports demonstratethat many bacterial strains have significantalgicidal effects on many species of red tideplankton. These results indicate that bacterialeffects should be taken into account to obtain stablemass culture of food microalgae.     

Continuous culture with deep seawater of a benthic food diatom Nitzschia sp.

A continuous culture system for a benthic food diatom Nitzschia sp. wasestablished by using properties of high nutrient and clean of deep seawater(DSW). DSW collected from 320 m depth in Muroto City, Japan, was introducedinto a glass-pipe bioreactor (14 cm length, 3 cm diam.) containing glassbeads of 0.5 cm diam. as substrata for the alga, and it was incubated at18°C · 80Em^–2sec^–1 · L:D=14:10. The chlorophyll a yield of benthicdiatoms in a reactor as a unit of surface area of the substratum was only0.001–0.003 g cm^–2 when the flow rate of DSW was 0(batch culture conditions). However, when DSW was supplied continuously to areactor, the yield increased to 1.4 g-chl.a cm^–2 alongwith the increase in flow rate of DSW. Moreover, amounts of chl.a washed outof the system were negligible, 0.0014 to 0.0045%, even though theflow rate of DSW was as much as 25 times h^–1, suggesting thatsloughing of benthic diatoms from the substratum was minimized. Although theyield of diatoms fluctuated significantly at the time that the DSW wascollected, the variation could be minimized by increasing the flow rate ofDSW. These results indicate that the continuous culturing system with DSWsupports the stable and effective mass culture of benthic food diatom.