Chemosystematic Investigation of the Annual Species of Helianthus (Asteraceae)

A total of 43 HPLC peaks tentatively considered to be sesquiterpene lactones was detected from a survey of the 18 taxa (eleven species and seven subspecies) of Helianthus sect. Helianthus using a recently developed microtechnique. All but one of the taxa showed characteristic sesquiterpene lactone patterns with between six and 15 compounds each. H. paradoxus appears to be the only species in the genus in which these compounds are not detectable. Comparison with available reference compounds allowed assignment of structures to 21 of the compounds. Known compounds can be classified into five major structural subtypes, the systematic distribution of which divides the section into three well-defined subgroups. The sesquiterpene lactone profiles of the other two annual species of the genus, H. agrestis and H. porteri, exhibit significant differences relative to any species of sect. Helianthus, which supports their exclusion from the section.     

Localization of a portion of extranuclear ATM to peroxisomes

The gene mutated in the human genetic disorder ataxia-telangiectasia codes for a protein, ATM, the known functions of which include response to DNA damage, cell cycle control, and meiotic recombination. Consistent with these functions, ATM is predominantly present in the nucleus of proliferating cells; however, a significant proportion of the protein has also been detected outside the nucleus in cytoplasmic vesicles. To understand the possible role of extra-nuclear ATM, we initially investigated the nature of these vesicles. In this report we demonstrate that a portion of ATM co-localizes with catalase, that ATM is present in purified mouse peroxisomes, and that there are reduced levels of ATM in the post-mitochondrial membrane fraction of cells from a patient with a peroxisome biogenesis disorder. Furthermore the use of the yeast two-hybrid system demonstrated that ATM interacts directly with a protein involved in the import of proteins into the peroxisome matrix. Because peroxisomes are major sites of oxidative metabolism, we investigated catalase activity and lipid hydroperoxide levels in normal and A-T fibroblasts. Significantly decreased catalase activity and increased lipid peroxidation was observed in several A-T cell lines. The localization of ATM to peroxisomes may contribute to the pleiotropic nature of A-T.     

Cytological and Physiological Reasons for the Latent Type of Infection in Sunflower Caused by Plasmopara halstedii

Lightmicroscopy was used to investigate cytological and physiological reasons for the latent type of infection of sunflowers with Plasmopara halstedii. Sections of the hypocotyl of inoculated, but healthy looking plants of compatible and incompatible host-pathotype combinations revealed vital hyphae and oospores, thus indicating an uninterrupted life cycle of the pathogen. Plants with latent infections showed enhanced cell division activities which restricted the pathogen to the cortical parenchyma. Additionally, hypersensitive reactions inhibited further growth in the pith parenchyma. In contrast, for systemic infection a successful invasion by the pathogen of the pith parenchyma of the hypocotyl and a growth of the hyphae faster than the hypersensitive reactions of the host tissue are needed.     

Anti-inflammatory activity of two diterpenes of Hyptis suaveolens from El Salvador

Separation and isolation of the two main compounds suaveolol and methyl suaveolate from leaves of chichinguaste (Hyptis suaveolens Poit., Lamiaceae) could be achieved by means of repeated column chromatography and repeated preparative thin layer chromatography. Their chemical structures were approved by MS, 1H NMR, 13C NMR and 2D-NMR experiments. The anti-inflammatory activity of the two compounds was tested for the first time as inhibition of croton oil-induced dermatitis of the mouse ear. Suaveolol and methyl suaveolate showed nearly the same dose-dependent topical anti-inflammatory activity, only two to three times lower than that of the reference drug indomethacin. The anti-inflammatory properties of these compounds could contribute to the antiphlogistic activity of extracts of Hyptis species and confirm the rational use of Hyptis suaveolens extracts in dermatological diseases.     

2-Methoxycyclopentyl analogues of a Pseudomonas aeruginosa quorum sensing modulator

Diastereomeric 2-methoxycyclopentyl analogues of a natural quorum sensing signaling molecule from Pseudomonas aeruginosa were synthesized and screened in pigment production assays with P. aeruginosa and Serratia strain ATCC39006.     

Cytological development and sesquiterpene lactone secretion in capitate glandular trichomes of sunflower

The secretion of sesquiterpene lactones (STL) in capitate glandular trichomes from the anther appendages of Helianthus annuus L. (Asteraceae) was observed by light and fluorescence microscopy and HPLC analysis. Disk flowers within the sunflower capitulum showed the known ontogenetic progression from the centre to the margin. During development of the florets, the trichomes in the anther appendages secreted their metabolites into the subcuticular secretion storage space in front of the two apical cells. All stages of forming the cuticular globe, from the pre-secretory to the post-secretory phase, could be observed microscopically and secretory activity was simultaneously monitored. Six germacrolides and heliangolides of known structure were selected for quantitative analysis. The increase in STL content during extension of the subcuticular space was monitored by HPLC analysis. Thereby, the start and termination of STL biosynthesis was defined in relation to other developmental stages of floret ontogenesis, particularly, the pollen formation. Part of the secreted material showed autofluorescence which could be attributed to a hydroxy-trimethoxy-flavone, as determined by NMR and mass spectroscopy. The anther trichomes were cytologically and chemically similar to foliar glandular trichomes of sunflower and represent the multicellular capitate glandular trichome type common to many Asteraceae. The ease with which anther trichomes of H. annuus can be harvested and analyzed suggests that they can provide a valuable model system for investigation of STL and flavonoid metabolism in Asteraceae.     

Isolation of tannin-degrading bacteria isolated from feces of the Japanese large wood mouse, Apodemus speciosus, feeding on tannin-rich acorns

Bacteria with tannase activity were isolated from the feces of the Japanese large wood mouse, Apodemus speciosus. They were largely classified into two groups: Gram-positive cocci and Gram-positive bacilli. Genotypic analysis using a species-specific PCR assay as well as biochemical tests identified all cocci as Streptococcus gallolyticus. A PCR assay targeting a genus-specific sequence in the 16S/23S rDNA spacer region and additional 16S rDNA sequencing indicated that the bacilli belong to the genus Lactobacillus, with L. animalis and L. murinus being closely related taxa. Subsequent estimation of guanine-plus-cytosine content, amplified ribosomal DNA restriction analysis, and DNA/ DNA hybridization assay confirmed that the bacilli are homologous to each other but different from L. animalis or L. murinus. Consequently, a novel species of the genus Lactobacillus may be proposed. To date, this study is the first to report on the isolation of tannase-positive bacteria from the feces of a rodent species. These bacteria may play an essential role for the host organism in digesting tannin-rich acorns available in their natural habitats, thereby endowing them with a greater ecological advantage.