Phylogenetic systematics of the nymphaeales

A cladistic analysis was applied to reveal the phylogenetic relationships among the Nymphaeales. Seventeen out of twenty three characters in gross morphology, anatomy and palynology were analyzed, for their evolutionary polarities. From the results of the present analysis, the phylogenetic status of each genus and their relationships were clarified: 1)Nelumbo is a distinct taxon and is presumed to have originated from an ancestral stock of the Nymphaeales; 2)Ceratophyllum has a close phylogenetic relationship withCabomba; and 3) in the Nymphaeaceaesensu stricto, Nuphar and the remaining genral constitute a monophyletic group. A conclusion obtained from the present analysis was that the following three families should be recognized in the Nymphaeales; Nelumbonaceae Nymphaeaceae, and Ceratophyllaceae. The generaBrasenia andCabomba are traditionally classified in the Nymphaeaceae or in the independent family Cabombaceae. However, they should be included in the family Ceratophyllaceae.     

Allozyme diversity and the evolution ofCrepidiastrum (Compositae) on the Bonin (Ogasawara) Islands

The genusCrepidiastrum is distributed in East Asia and includes 7 species. In the Bonin Islands, three species ofCrepidiastrum occur, and all of them are endemic to the islands. For detecting the origin and speciation of these endemic species, electrophoretic studies have been done in three endemic species of the Bonin Islands as well as in the remaining four species ofCrepidiastrum, andYoungia denticulata which is considered to be closely related toCrepidiastrum. A total of 386 individuals were sampled from 14 populations. As a result, 17 loci of 10 enzyme systems were resolved and gene frequencies for each population were calculated. The genetic variability was low in island species, as reported in some oceanic island plants. Four groups were recognized in the dendrogram generated by the UPGMA method. The Bonin endemics were clustered together, suggesting a monophyletic origin.C. ameristophyllum andC. linguaefolium were found to be genetically very similar, and this may suggest recent and rapid speciation within the islands.     

Phylogeny of gymnosperms inferred fromrbcL gene sequences

Partial nucleotide sequences of the large subunit of ribulose-1,5-bisphosphate carboxylase (rubisco) gene (1333 base pairs: about 90% of the gene) from several seed plants were determined. Phylogenetic trees based on amino acid sequences were inferred by using the neighbor joining and maximum likelihood methods. The results indicate (1) monophyly of gnetum group (Ephedra, Gnetum, Welwitschia), (2) monophyly of extant gymnosperms containing gnetum group, which contradicts the results of morphological data.     

Studies in the floral morphology and anatomy of nymphaeales

Floral morphology ofBrasenia schreberi Gmel. andCabomba caroliniana A. Gray was observed chiefly from an anatomical point of view. The receptacle ofB. schreberi is rather flat and a vascular plexus is observable in the mature flower. The vasculature in this plexus is so complex taht it is not easy to trace its structure in detail. by observation on small buds, it can be seen that the receptacular vasculature consists of a girdling bundle in the basal area and usually nine receptacular strands from which traces to the petals and stamens branch off. The vasculature in the receptacle is reconstructed and diagramatically shown as though split longitudinally and spread out in one plane. Floral vasculature inCabomba caroliniana is simpler, and is probably related to the smaller number of stamens and carpels. It also has a girdling bundle at the bottom of receptacle and this vasculature is suggested to be derived by simplification from aBrasenia-type vasculature. Evidence from floral anatomy suggests that these two genera are closely related. InNymphaea, a vascular plexus in the receptacle is also observed (Moseley, 1961; Ito 1983). The plexus ofBrasenia andNymphaea are not the same in their construction. Nevertheless, their fundamental floral vasculature is comparable and it is preferable to place them in the same family or same order.     

PHYLOGENETIC RELATIONSHIPS WITHIN THE COLONIAL VOLVOCALES (CHLOROPHYTA) INFERRED FROM CLADISTIC ANALYSIS BASED ON MORPHOLOGICAL DATA1

A cladistic analysis was used to deduce the phylogenetic relationships within the colonial Volvocales. Forty-one pairs of characters related to gross morphology and ultrastructure of vegetative colonies as well as asexual and sexual reproduction were analyzed based on parsimony, using the PAUP 3.0 computer program, for 25 species belonging to nine volvocacean and goniacean genera of the colonial Volvocales. Chlamydomonas reinhardtii Dangeard was the outgroup. The strict consensus tree indicated the presence of two monophyletic groups, one composed of all the volvocacean species analyzed in this study and the other containing the goniacean species except for the four-celled species Gonium sociale (Dujardin) Warming. In addition, these two groups constitute a large monophyletic group, to which G. sociale is a sister group. A new combination Tetrabaena socialis (Dujardin) Nozaki et Itoh and a new family Tetrabaenaceae Nozaki et Itoh are thus proposed for G. sociale. In addition, the analysis suggests that the volvocacean genera Eudorina and Pleodorina are paraphyletic groups, respectively, and that the monotypic genus Yamagishiella has no autapomorphic characters and represents primitive features of the anisogamous and oogamous genera of the Volvocaceae. Phylogenetic relationships within the Volvocaceae and the Goniaceae, as well as the various modes of sexual reproduction exhibited by these organisms, are discussed on the basis of the analysis.     

Chloroplast DNA phylogeny of Asian Bamboos (Bambusoideae,Poaceae) and its systematic implication

The bamboo is usually classified as a subfamily Bambusoideae of Poaceae, and includes approximately 20 genera and 300 species. To estimate phylogenetic relationships among these genera, we examined restriction site mutations of cpDNA for 16 Asian genera. In the cladogram obtained, the Bambosoideae was divided into two major lineages, one includingPleioblastus, Pseudosasa, Semiarundinaria, Shibataea, Phyllostachys, Sasa, Sinobambusa, Chimonobambusa, Arthrostylidium, andYushania, and the other consisting ofBambusa, Gigantochloa, Dendrocalamus, Thyrostachys, Melocanna, andSchizostachyum. Monophylly of each clade was supported by 83% and 98% bootstrap probability, respectively. The present result supports monophylly of Arundinarieae of Potztal's (1964) classical system, but does not support his treatment to recognize Dendrocalameae.     

Comparison of the DNA content of megakaryocytes identified immunologically with that identified morphologically

 We devised a new microfluorometric method for determining the ploidy of megakaryocytes identified immunologically in bone marrow smears. The smears were immunostained by incubation with mouse monoclonal anti-glycoproteins (GP) IIb antibodies, followed by fluorescein isothiocyanate-conjugated goat anti-mouse IgG antibodies. They were then stained with 4′,6-diamidino-2-phenylindole (DAPI). Megakaryocytes were identified by their GPIIb immunofluorescence using a microfluorometer and, after the filters were changed, their DNA content was assayed by measuring the intensity of DAPI fluorescence. This intensity was shown to be proportional to the DNA content when the aperture of the objective lens was reduced. We compared these results with those obtained when megakaryocytes were identified morphologically, using DAPI staining after Wright-Giemsa destaining. In all 12 normal controls, the ploidy peaks were shown to be 16N by both methods, and the mean ploidy detected by the immunological method was only reduced 0.961 times relative to the estimate from the morphological method. In contrast, in eight myelodysplastic syndrome (MDS) patients, the ploidy peaks were either 8N or 4N and the mean was reduced by 0.906 times (P=0.018). Thus we could immunologically identify small megakaryocytes which we could not identify morphologically. Therefore, this method is useful for measuring megakaryocytic ploidy, especially in the pathological megakaryocytes of MDS patients. Accepted: 29 April 1997     

Sonic hedgehog is involved in osteoblast differentiation by cooperating with BMP-2

The roles of Sonic hedgehog (Shh) and Bone morphogenetic protein-2 (Bmp-2) in osteoblast differentiation were investigated using in vitro cell systems. Recombinant amino-terminal portion of SHH (rSHH-N) dose dependently stimulated ALP activity in C3H10T1/2 and MC3T3-E1 cells. rSHH-N induced expression of Osteocalcin mRNA in C3H10T1/2 cells. A soluble form of the receptor for type IA BMP receptor antagonized rSHH-N-induced ALP activity in C3H10T1/2 and MC3T3-E1 cells, indicating that BMPs are involved in SHH-induced osteoblast differentiation. Simultaneous supplement with rSHH-N and BMP-2 synergistically induced ALP activity and expression of Osteocalcin mRNA in C3H10T1/2 cells. Pretreatment with rSHH-N for 6 h enhanced the response to BMP-2 by increasing ALP activity in C3H10T1/2 and MC3T3-E1 cells. Stimulatory effects of rSHH-N and additive effects with rSHH-N and BMP-2 on ALP activity were also observed in mouse primary osteoblastic cells. Transplantation of BMP-2 (1 microg) into muscle of mice induced formation of ectopic bone, whereas transplantation of r-SHH-N (1-5 microg) failed to generate it. These results indicate that Shh plays important roles in osteoblast differentiation by cooperating with BMP.     

Characterization of the Selaginella remotifolia MADS-box gene

Recent progress in plant molecular genetics has revealed that floral organ development is regulated by several homeotic selector genes, most of which belong to the MADS-box gene family. Here we report on SrMADS1,a MIKC(c)-type MADS-box gene from Selaginella, a spikemoss belonging to the lycophytes. SrMADS1 phylogenetically forms a monophyletic clade with genes of the LAMB2 group, which are MIKC(c) genes of the clubmoss Lycopodium, and is expressed in whole sporophytic tissues except roots and rhizophores. Our results and the previous report on Lycopodium MIKC(c) genes suggest that the ancestral MIKC(c )gene of primitive dichotomous plants in the early Devonian was involved in the development of basic sporophytic tissues such as shoot, stem, and sporangium.