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.     

A molecular orbital study of the metabolic pathway with hydroquinone intermediate from benzene as carcinogen

A possible metabolic activation pathway of benzenein vivo is the nonenzymatic oxidation of hydroquinone producedvia the cytochrome P-450-mediate two-step oxidation of benzene. The mechanism of the further oxidation of hydroquinone and the nature of the most reactive intermediate have not yet been clarified, although it is speculated that the intermediate isp-benzoquinone and/orp-benzosemiquinone. The theoretical result of using molecular orbital calculations (ab initio and CNDO/2 methods) indicates that although the mechanism of the nonenzymatic oxidation of hydroquinone cannot yet be determined, the intermediate is thep-benzosemiquinone anion radical. It is also suggested that active-oxygen species such as hydroxyl radical, which accelerates the nonenzymatic oxidation, play an important role in the metabolic pathway in question.     

Stereoselective total synthesis of ceramide Di-, Tri- and tetrahexosides of wheat flour

The first total synthesis of glycosphingolipids isolated from wheat flour has been achieved in a regio- and stereo-controlled manner.Abbreviations THF tetrahydrofuran - DMF dimethylformamide Part 53 in the series Synthetic Studies on Cell Surface Glycans     

Induction of interdigitating reticulum cell-like differentiation in human monocytic leukemia cells by conditioned medium from IL-2-stimulated helper T-cells

Monocytic leukemia (MoL) cells were obtained from the peripheral blood of a patient in whom the leukemic cells infiltrating various lymphoreticular organs exhibited features intermediate between interdigitating reticulum cells (IDC) and ordinary phagocytic macrophages, whereas the leukemic cells in the peripheral blood were essentially monocytic and lacked such features. Peripheral blood CD4+ T-cells were established as an interleukin-2-dependent T-cell line. When the MoL cells were exposed for a few days to conditioned medium from the T-cell line, they extended several dendritic cytoplasmic projections and became intensely positive for HLA-DR antigen, cytoplasmic S-100β protein, and CD1 antigen. Functionally, the conditioned medium significantly down-regulated Fc-mediated and Fc-independent phagocytic activities, and the levels of lysosomal enzymes such as lysozyme and nonspecific esterase in the MoL cells. Moreover, the conditioned medium significantly up-regulated the accessory cell function of the MoL cells as measured by the primary allogenic mixed leukocyte reaction (MLR). Furthermore, the conditioned medium significantly down-regulated the expression of CD14 antigen. Biochemical analysis indicated that the factor responsible for these changes is a protein which is distinct from known human cytokines and whose molecular weight is approximately 31 kDa. These findings suggest that IDC are closely related the monocytic lineage and that helper T-cells play an important role in constructing the microenvironment of T-lymphoid tissues which is necessary for the differentiation and maturation of IDC.     

Construction of a fusion gene comprising the Taka-amylase A promoter and the Escherichia coli β-glucuronidase gene and analysis of its expression in Aspergillus oryzae

Summary Northern blot analysis of glucose-grown and starch-grown mycelia of Aspergillus oryzae R11340 was conducted using the cloned Taka-amylase A (TAA) gene as a probe. The amount of mRNA homologous to the TAA gene was increased when this fungus was grown with starch as a sole carbon source. In order to analyze the induction mechanism, we inserted the Escherichia coli uidA gene encoding -glucuronidase (GUS) downstream of the TAA promoter and introduced the resultant fusion gene into the A. oryzae genome. Production of a functional GUS protein was induced by starch, but not by glucose. When the effects of various sugars on expression of the fusion gene were examined, the results suggested that the expression of the fusion gene was under control of the TAA gene promoter.     

Flavanol glucosides from rhubarb and Rhaphiolepis umbellata

Investigations of rhubarb and the bark of Rhaphiolepis umbellata led to the isolation of new flavan-3-ol glucosides. Their structures were elucidated on the basis of ¹H and ¹³C NMR analysis hydrolytic studies as (+)-catechin 5-O-β-d-glucopyranoside and (?)-catechin 7-O-β-d-glucopyranoside.     

Ley antigen expression is correlated with apoptosis (programmed cell death)

Apoptosis (programmed cell death) is a basic physiological processwhich determines specific patterns of tissue size and shape,and balance of cell number, during morphogenesis, and seemsto play an integral role in oncogenic progression. Since dramaticchanges of cellular glycosylation pattern are well known tobe closely correlated with differentiation, development andoncogenesis, it is likely that similar specific changes areassociated with apoptosis. However, this possibility has notbeen systematically investigated. We therefore carried out histologicalstudies of many tumours and normal tissues for which a highincidence of apoptosis is believed to occur. Sections were stainedwith monoclonal antibodies (MoAbs) directed to carbohydrateantigens Le^y and Le^x, proliferating cellular nuclear antigen(PCNA) and Fas (previously claimed to be an apoptosis-inducingantigen). Antibody staining patterns were compared with morphologicalcell characteristics as revealed by haematoxylin/eosin staining,and DNA fragmentation patterns (a marker of apoptosis) as revealedby 3'-OH nick-end labelling technique. We found that expressionof Le^y (defined by MoAb BM1) is closely correlated with theprocess of apoptosis, but not with cell proliferation or necrosis.Within Le^y-positive areas of tissue sections, typical apoptoticmorphological changes and DNA fragmentation (as revealed bypositive nick-end labelling) were frequently observed in certainloci, although not all Le^y-positive cells showed such signsof apoptosis. Le^y-positive areas showed consistent negativestaining by MoAb directed to PCNA and negative or weak stainingby MoAb directed to Fas antigen, regardless of tissue source.No such trends were observed for Le^x glycosylation. We concludethat Le^y expression is a useful phenotypic marker predictiveof apoptosis, i.e. some (although not all) Le^y-positive cellssubsequently become apoptotic. apoptosis expression glycosylation patterns Le^y antigen 3'-OH nick-end labelling