Vegetative diversification and radiation in subtribeDendrobiinae (Orchidaceae): Evidence from chloroplast DNA phylogeny and anatomical characters

The data derived from a chloroplast DNA restriction site analysis of subtribeDendrobiinae (Orchidaceae) indicate that extreme vegetative diversification is concentrated in two limited parts of this group. Overlaying the vegetative character states onto the chloroplast DNA cladogram suggests that several xeromorphic, vegetative characters evolved in the lines leading to the above-mentioned clades. Several anatomical characters are also associated with xeromorphy. These vegetative and anatomical characters facilitated the establishment of this group in various dry habitats. On the other hand, the modifications of size and number of parenchymatous cells substantially contributed to the vegetative diversification. This fact implies that a simple structural adjustment can result in a major modification of growth habits in theDendrobiinae.     

Cloning and nucleotide sequence of fosfomycin biosynthetic genes of Streptomyces wedmorensis

The biosynthetic pathway for production of the antibiotic fosfomycin by Streptomyces wedmorensis consists of four steps including the formation of a C-P bond and an epoxide. Fosfomycin production genes were cloned from genomic DNA using S. wedmorensis mutants blocked at different steps of the biosynthetic pathway. Four genes corresponding to each of the biosynthetic steps were found to be clustered in a DNA fragment of about 5 kb. Nucleotide sequencing of a large fragment revealed the presence of ten open reading frames, including the four biosynthetic genes and six genes with unknown functions.     

Germitorosone and methylgermitorosone,two hydroanthracene derivatives from seedlings of Cassia torosa

Two new yellow pigments, germitosone and methylgermitorosone, were isolated from the seedling of Cassia torosa. The structures of these substances were established as 3,7 dimethyl - 6 - methoxy - 1 - oxo - 2,3,8,9 - tetrahydroxy - 1,2,3,4 - tetrahydroanthracene and 6,9 dimethoxy - 3,7 - dimethyl - 1 - oxo - 2,3,8 - trihydroxy - 1,2,3,4 - tetrahydroanthracene respectively.     

Induction of differentiation of HL-60 cells by protein kinase C inhibitor, K252a

To clarify the role of protein kinase C and protein kinase A in cell proliferation and differentiation, the effects of K252a and its derivatives (K252b, KT5720), which have different inhibitory activity to these protein kinases, on the proliferation and differentiation of HL-60 cells were investigated. The proliferation and DNA synthesis of the HL-60 cells were inhibited by K252a in a dose dependent manner. However, K252b and KT5720 which are more specific inhibitors of protein kinase C or protein kinase A, respectively, had no observable effect on cell proliferation. K252a (40nM) enhanced the differentiation of HL-60 cells induced by 1,25(OH)2D3, retinoic acid and DMSO. K252b and KT5720 did not affect 1,25(OH)2D3-induced differentiation. K252a significantly inhibited the differentiation induced by PMA. These results demonstrate that K252a but not its derivatives can function as an antitumor drug and enhancer of the differentiation induced by various inducers.     

Biochemical characterization ofSerratia liquefaciens sensu stricto,Serratia proteamaculans,andSerratia grimesii sp. nov.

Seven biochemical groups were found among strains previously labeledSerratia liquefaciens (groups C1ab, C1c, C1d, EB, RB, RQ, and Adc). Comparison of biochemical data with DNA relatedness data allowed the definition (or redefinition) of threeSerratia species:Serratia liquefaciens sensu stricto (group C1ab),Serratia proteamaculans (groups C1c, EB, RB, and RQ), andSerratia grimesii sp. nov. (groups C1d and Adc). Biochemical group RQ, which is genomically related toS. proteamaculans at the borderline of species level, is proposed as a new subspecies ofS. proteamaculans (Serratia proteamaculans subsp.quinovora). Group Adc (3 strains) is also ambiguously related toS. grimesii, but no other proposal is made pending additional studies. The type strains of the newly named taxa,S. grimesii andS. proteamaculans subsp.quinovora, are respectively ATCC 14460 and strain 4364 (= CIP 8195 = ATCC 33765).     

Scanning electron-microscopy of starch granules, with or without amylase attack

Scanning electron-microscopy (SEM) revealed that, for starch granules relatively susceptible to amylase, numerous pin holes could be observed on the surfaces of granules attacked by amylase. We also observed that the pores penetrated into the inner layers of granules during the enzyme action and some of the granules exhibited a terraced or step-shaped apperance in their inner portions. These internal characteristics are most probably indicative of layered internal structures of the granules. The other characteristic observations by SEM were striated structures on the surfaces of starch granules of banana, lily, and lotus attacked by pancreatin.     

Mycobiont diversity and first evidence of mixotrophy associated with Psathyrellaceae fungi in the chlorophyllous orchid Cremastra variabilis

Mixotrophy (MX, also called partial mycoheterotrophy) in plants is characterized by isotopic abundances that differ from those of autotrophs. Previous studies have evaluated mycoheterotrophy in MX plants associated with fungi of similar ecological characteristics, but little is known about the differences in the relative abundances of ¹³C and ¹⁵N in an orchid species that associates with several different mycobionts species. Since the chlorophyllous orchid Cremastra variabilis Nakai associates with various fungi with different ecologies, we hypothesized that it may change its relative abundances of ¹³C and ¹⁵N depending on the associated mycobionts. We investigated mycobiont diversity in the chlorophyllous orchid C. variabilis together with the relative abundance of ¹³C and ¹⁵N and morphological underground differentiation (presence or absence of a mycorhizome with fungal colonization). Rhizoctonias (Tulasnellaceae, Ceratobasidiaceae, Sebacinales) were detected as the main mycobionts. High differences in δ¹³C values (– 34.7? to?– 27.4 ‰) among individuals were found, in which the individuals associated with specific Psathyrellaceae showed significantly high relative abundance of ¹³C. In addition, Psathyrellaceae fungi were always detected on individuals with mycorhizomes. In the present study, MX orchid association with non-rhizoctonia saprobic fungi was confirmed, and the influence of mycobionts on morphological development and on relative abundance of ¹³C and ¹⁵N was discovered. Cremastra variabilis may increase opportunities to gain nutrients from diverse partners, in a bet-hedging plasticity that allows colonization of various environmental conditions.

     

New Strategies for the Chemical Synthesis of Biologically Important Nucleic Acid Derivatives

Abstract

This paper describes general methods for the synthesis of N-phosphorylated ribonucleosides and oligonucleotides containing a 2′-O-phosphorylated or 2′-O-thiophosphorylated ribonucleoside. The NMR-based conformational analysis and computational molecular dynamics simulation of the 2′-O-phosphorylated ribonucleoside residue in such modified oligonucleotides suggested that the ribose residue existed preferentially in a C2′-endo conformation. It was also found that simple heating of 2′-O-phosphorylated oligonucleotides resulted in rapid dethiophosphorylation.