The chemotaxonomic significance of two bioactive caffeic acid esters,nepetoidins A and B,in the Lamiaceae

A survey of leaf surface constituents in the family Lamiaceae using HPLC with diode array detection revealed the presence of two characteristic phenolic compounds in many species. The distribution of these phenolics in the Lamiaceae was found to be of taxonomic significance, as they were present in the great majority of species investigated for the subfamily Nepetoideae, including representatives of the well-known genera of culinary herbs, mint, rosemary, sage, thyme and basil. In contrast, they were absent from species of the other subfamilies of Lamiaceae studied and from the related families Verbenaceae, Scrophulariaceae, Acanthaceae and Buddlejaceae. The compounds were isolated from Plectranthus crassus and identified by NMR spectroscopy as the known caffeic acid esters (Z,E)-[2-(3,5-dihydroxyphenyl)ethenyl] 3-(3,4-dihydroxyphenyl)-2-propenoate and (Z,E)-[2-(3,4-dihydroxyphenyl)ethenyl] 3-(3,4-dihydroxyphenyl)-2-propenoate, for which the trivial names nepetoidins A and B are proposed. The presence of this pair of caffeic acid esters adds another character to the chemical, palynological and embryological features distinguishing the Nepetoideae from the other subfamilies of Lamiaceae and related families, and supports the view that the Nepetoideae are a specialised and monophyletic group within the family. Nepetoidin B was shown to have a greater antioxidant activity than gallic, rosmarinic and caffeic acids, and showed activity as an insect phagostimulant. Both compounds were antifungal.     

A computer-assisted personalized approach in an undergraduate plant physiology class

We used Computer-Assisted Personalized Approach (CAPA), a networked teaching and learning tool that generates computer individualized homework problem sets, in our large-enrollment introductory plant physiology course. We saw significant improvement in student examination performance with regular homework assignments, with CAPA being an effective and efficient substitute for hand-graded homework. Using CAPA, each student received a printed set of similar but individualized problems of a conceptual (qualitative) and/or quantitative nature with quality graphics. Because each set of problems is unique, students were encouraged to work together to clarify concepts but were required to do their own work for credit. Students could enter answers multiple times without penalty, and they were able to obtain immediate feedback and hints until the due date. These features increased student time on task, allowing higher course standards and student achievement in a diverse student population. CAPA handles routine tasks such as grading, recording, summarizing, and posting grades. In anonymous surveys, students indicated an overwhelming preference for homework in CAPA format, citing several features such as immediate feedback, multiple tries, and on-line accessibility as reasons for their preference. We wrote and used more than 170 problems on 17 topics in introductory plant physiology, cataloging them in a computer library for general access. Representative problems are compared and discussed.     

A chemotaxonomic study of mucilages in American Zamiaceae

Abstract

Methylrhamnose, fucose, rhamnose, mannose, arabinose, galactose, and glucuronolactone are the monosaccharides identified in hydrolysed mucilages collected from 37 species belonging to the five American cycad genera (Ceratozamia, Chigua, Dioon, Microcycas and Zamia). The patterns of monosaccharide distribution in the mucilages resulted to be typical at the generic level, with the exception of Chigua and Zamia the patterns of which were similar. No differences appeared among species within single genera, with the exception of Zamia in which minor differences were observed at the intrageneric level. Differences and similarities among patterns at both intergeneric and intrageneric levels are discussed for their systematic implications.     

Phycoerythrins as chemotaxonomic markers in red algae: A survey

A simple general procedure is described for the purification of high molecular weight phycoerythrin from red algae. Protein of purity adequate for precise spectroscopic characterization was obtained from as little as 0.2 g wet wt of fresh algal tissue. The absorption, excitation and fluorescence emission spectra of over a hundred phycoerythrins from representatives of all of the orders of the Bangiophyceae and Florideophyceae were determined. On the basis of visible absorption spectra, the phycoerythrins were subdivided into five groups: B-phycoerythrin Type I [542 > 567 > 502(s)], B-phycoerythrin Type II [566 ? 528 > 500(s)], R-phycoerythrin Type I (565 > 543 > 497), R-phycoerythrin Type II [566 > 551(s) > 496], and R-phycoerythrin Type III (567 > 539 < 496), where the numbers in parentheses specify the absorption maxima in nm and (s) denotes shoulder. Phycoerythrins do not appear to be useful at familial, ordinal and class levels in taxonomic studies. However, they do appear to be of limited value in discriminating taxonomic groupings at the generic and specific level. Audouinella (Acrochaetiales) can be separated into two groups of species, B-PE and R-PE types, but this is not correlated with cytological, morphological or life-history patterns. Rhodophysema can be removed from the Cryptonemiales and placed in the Acrochaetiales on the basis of its B-PE content, morphology and life history.     

A chemotaxonomic method to quantify phytoplankton groups in freshwater lentic mesocosms: an approach including chlorophyll a breakdown products

The use of HPLC methods to determine and quantify phytoplankton population composition, is sometimes less time-consuming than microscopic identification. However, its general application poses problems since high discrepancies between chlorophyll a calculated using chemotaxonomic methods and direct measurements were noticed. For instance, chemotaxonomic protocols generally employed can lead to a poor estimation of total and relative abundance when high amounts of chlorophyll a breakdown products are present. Therefore, we propose a new approach to calculate relative abundance of algal groups in a phytoplankton population, based on integration of these degradation products in the chemotaxonomic assessment in lentic and shallow freshwater ecosystems.     

Flavonoids as chemotaxonomic markers for Erythroxylum australe

Methanolic leaf extracts of Erythroxylum australe F. Muell. produced eight O-conjugated flavonoids. Six of the flavonoid aglycones were dihydroisoflavones (all dihydro-orobol derivatives), one a flavanone, eriodictyol, and one a flavonol, quercetin. The major glycosides of the flavonoids included mono-glucosyl-rhamnosyls and dirhamnosyl-glucosides with either 3, 5, 7 or 3', 4' linkage or a combination thereof The array of flavonoids present in E. australe suggests kinship to E. ulei and linkage to the four cultivated alkaloid-bearing Erythroxylum, especially the ancestral E. coca var. coca. Because of the uniqueness of the flavonoids present in leaf tissue of E. australe they are unambiguously useful as chemotaxonomic markers for the taxon.     

A chemotaxonomic survey of flavonoids in leaves of the Oleaceae

Leaves of 97 taxa representing all the genera at present recognized in the family Oleaceae were surveyed for flavonoids. Four flavonol glycosides were found to be common, the 3-glucmides and 3-rutinosides of quercetin and kaempferol, as were four flavone glycosides, namely the 7-glurosides arid 7-rutinosides of luteolin and apigenin. Among rarer constituents detected were luteolin 4'-glucoside, eriodictyol 7-glucoside, chrysoeriol 7-glucoside, an apigenin-di-C-glycoside and several higher glycosides of quercetin. The species and genera surveyed fell into two groups: those with flavonol glycosides alone; and those with both flavonol and flavone glycosides. The most striking correlation was with chromosome number (and subfamily division) since almost all taxa with a basic number of 11, 13 and 14 had only flavonol glycosides, whereas most taxa with x = 23 had both types of flavonoid. Evolutionary advancement in the family appears to involve the gradual replacement of flavonol by flavone glycosides. Indeed, a few tam, notably Nestegis apelala, Picconia excelsa and Tesserandra fluminense , lacked flavonol glycosides in the leaves completely. At the lower levels of classification, the distribution of flavonoids is of less interest. However, the patterns in Linociera and Chionanthus , two taxa recently made congeneric, are sufficiently different to suggest that this decision might have to be reconsidered when more is known of their chemistry. Otherwise leaf patterns generally fit in with the existing generic classification in the family.     

A computer-assisted technique for long-term gastric pH monitoring

A computer-assisted technique for prolonged gastric pH monitoring has been developed using a personal computer. Segments of signal from several studies performed in controls and on patients with duodenal ulcers were chosen for comparison between manual and digital pH readings; no significant difference was detected. In clinical practice this system might provide an additional tool in the diagnostic and therapeutic treatment of peptic ulcer disease.     

Do-it-yourself statistics: A computer-assisted likelihood approach to analysis of data from genetic crosses

Graduate school programs in genetics have become so full that courses in statistics have often been eliminated. In addition, typical introductory statistics courses for the "statistics user" rather than the nascent statistician are laden with methods for analysis of measured variables while genetic data are most often discrete numbers. These courses are often seen by students and genetics professors alike as largely irrelevant cookbook courses. The powerful methods of likelihood analysis, although commonly employed in human genetics, are much less often used in other areas of genetics, even though current computational tools make this approach readily accessible. This article introduces the MLIKELY.PAS computer program and the logic of do-it-yourself maximum-likelihood statistics. The program itself, course materials, and expanded discussions of some examples that are only summarized here are available at http://www.unisi. it/ricerca/dip/bio_evol/sitomlikely/mlikely.h tml.     

A program for computer-assisted scoring of Southern blots

SCORE, a program for computer-assisted scoring of Southern blots of clone DNA, retains the use of expert human judgment while taking over much of the drudgery of the scoring task. The primary functions of the program are to help make an aligned overlay of the fluorescence gel image and the autoradiogram blot image, to keep track of band and lane locations and to store the resulting data directly into a database. Use of SCORE has resulted in greatly increased efficiency and accuracy.     

A system for the automated chemotaxonomic determination of salmonellae and other pathogenic bacteria

On the basis of the data of the gas-chromatographic analysis of the fatty acids of 208 bacterial strains, representatives of 16 different microbial genera, the algorithm of decision taking, necessary for the program provision of investigations, was worked out. In working out the algorithm the characteristics of 30 fatty acids were used, making it possible to classify bacteria with their genera and in some cases their species. The groups of fatty acids with the number of carbon atoms in their molecules ranging from 10 to 25, their melting temperatures and the dependence of relative characteristics of binding from the number of carbon atoms in the molecule of the acid, its chemical composition and the presence of double bonds were taken into consideration. To indicate salmonellae by their fatty acid profiles, a chromatographic system on the basis of a type Crystal 2000 M gas chromatograph is proposed. In addition, the complex method for the determination of bacteria, combining the determination of salmonellae by changes in the medium resistance (impedance) with the use of an electrochemical analyzer and the subsequent identification of the infective agent by its fatty acid profile in the common system of gas-chromatographic investigation, is proposed.     

A chemotaxonomic study of some moderately halophilic Gram-positive isolates

A chemotaxonomic study was carried out on some moderately halophilic Gram-positive motile cocci, previously isolated from the Salar de Atacama (Chile) and grouped in two phenons (A and B) by numerical taxonomic analysis. Strains included in phenon A had a DNA base composition ranging between 42.0 and 44.0 mol%, while that of phenon B ranged from 48.0 to 48.8 mol%. The results of DNA-DNA hybridization studies on representative strains from phenons A and B, indicated that the strains assigned to phenon A comprise a genomically homogeneous group, with a high degree of homology (80%) to the type strain of Marinococcus albus. Similarly, phenon B constituted a homogeneous group and the representative strain studied showed a DNA-DNA homology of 70% with the type strain of Marinococcus halophilus. Representative strains studied from each phenon had meso-diaminopimelic acid in the cell wall and menaquinone systems with seven isoprene units (MK-7) as a major component. All these results, together with those previously reported, indicate that strains included in phenons A and B constitute additional strains of the species Marinococcus albus and Marinococcus halophilus , respectively.     

Volatile organic compounds from arctic bacteria of the Cytophaga-Flavobacterium-Bacteroides group: a retrobiosynthetic approach in chemotaxonomic investigations

Volatile organic compounds emitted by different marine arctic strains of the Cytophaga-Flavobacterium-Bacteroides group were investigated by using a modified closed-loop stripping apparatus (CLSA). Seven of nine strains emitted volatiles, dominated by methyl ketones, in specific patterns. The methyl ketones were aliphatic saturated, or unsaturated, and comprised 12 to 18 C-atoms, sometimes with terminal Me branches. They were identified by GC/MS, retention-index calculations, derivatization with dimethyl disulfide for C=C bond location, and GC/FTIR to elucidate their uniform (Z)-configuration. The proposed structures of all methyl ketones were subsequently confirmed by synthesis, while the absolute configuration of chiral volatiles was elucidated by stereoselective synthesis. From retrobiosynthetic considerations, it was found that strain ARK10267 uses mainly valine, and strain ARK10063 mainly isoleucine for formation of starters for the ketone biosynthesis, which is correlated to fatty acid biosynthesis. Four strains (ARK10223, ARK10044, ARK10141, and ARK10146) use leucine. These separations are supported by phylogenetic affiliations based on 16S rRNA. Strain ARK10255b, in the course of this study found to be not a member of the Cytophaga-Flavobacterium-Bacteroides phylum, did not emit aliphatic ketones of medium chain length, but methionine-derived 4-(methylsulfanyl)butan-2-one and corresponding 4-(methylsulfanyl)butan-2-ol. Most of the compounds described have not been reported previously from nature.     

A chemotaxonomic analysis of cannabinoid variation in Cannabis (Cannabaceae)

Cannabinoids are important chemotaxonomic markers unique to Cannabis. Previous studies show that a plant's dry-weight ratio of Δ(9)-tetrahydrocannabinol (THC) to cannabidiol (CBD) can be assigned to one of three chemotypes and that alleles B(D) and B(T) encode alloenzymes that catalyze the conversion of cannabigerol to CBD and THC, respectively. In the present study, the frequencies of B(D) and B(T) in sample populations of 157 Cannabis accessions were determined from CBD and THC banding patterns, visualized by starch gel electrophoresis. Gas chromatography was used to quantify cannabinoid levels in 96 of the same accessions. The data were interpreted with respect to previous analyses of genetic and morphological variation in the same germplasm collection. Two biotypes (infraspecific taxa of unassigned rank) of C. sativa and four biotypes of C. indica were recognized. Mean THC levels and the frequency of B(T) were significantly higher in C. indica than C. sativa. The proportion of high THC/CBD chemotype plants in most accessions assigned to C. sativa was <25% and in most accessions assigned to C. indica was >25%. Plants with relatively high levels of tetrahydrocannabivarin (THCV) and/or cannabidivarin (CBDV) were common only in C. indica. This study supports a two-species concept of Cannabis.     

A two-step computer-assisted method for deriving steady-state rate equations

Solid tumors commonly contain regions with glucose-starved and hypoxic conditions. Tumor cells under the adverse conditions can survive through the stress response, such as cell cycle arrest. In this study, we found that the stress conditions stimulated nuclear accumulation of proteasomes, large multicatalytic protease complexes, in human colon cancer HT-29 cells. The nuclear proteasome levels both in amount and in activity were increased approximately 4 and 2 times by glucose starvation and hypoxia, respectively. No changes were detected in the total expression levels of proteasome. The nuclear proteasome accumulation was also observed in ovarian cancer A2780 cells under glucose starvation, suggesting that this response was regardless of the origin of cancer cells. Our results indicate that the nuclear proteasome distribution is enhanced by glucose starvation and hypoxia, and suggest that the proteolysis by proteasome in the nucleus may play roles in the stress response of solid tumor cells.     

Calystegines as chemotaxonomic markers in the Convolvulaceae

An extended GC-MS study of 129 convolvulaceous species belonging to 29 genera (all 12 tribes) including the results of a previous survey (65 spp.) revealed the occurrence of one to six polyhydroxy alkaloids of the nortropane type (calystegines) in 62 species belonging to 22 genera of all tribes except the unique parasitic Cuscuteae. The large genus Ipomoea turned out to comprise calystegine-positive species in at least eight out of ten sections checked. The number of the calystegines used as reference compounds has been increased from seven (previous survey) to 11 (present study). Furthermore, the results concerning these additional four alkaloids could also be completed for all species of the previous survey. The plant material (epigeal vegetative parts and/or roots, flowers, fruits/seeds) was obtained from collections in the wild from a wide range of tropical, subtropical, and temperate locations of all continents as well as from cultivation in the greenhouse. All plant organs turned out to be potential locations for the occurrence of these metabolites though they are detectable often only in certain organs of a given species. Three genera (Cuscuta, Operculina, Polymeria) might have lost the ability to synthesize these plesiomorphic characters in the course of the evolution since the examination of several different organs and/or provenances of five species each failed to show calystegines as constituents. Nevertheless, the present data clearly demonstrate that the occurrence of calystegines is an almost consistent trait in the Convolvulaceae in principle, from basal to most advanced tribes.     

Variabilin, a chemotaxonomic marker for the family Irciniidae

The furanosesterterpene variabilin was isolated from the sponge Sarcotragus. From a chemical point of view, the family Irciniidae has been the source of furanosesterterpenes, and especially variabilin is an important chemotaxonomic marker for the family Irciniidae.     

A computer-assisted cell identification system

A computer and optical microscope image processing system for the acquisition, editing and analysis of quantitative, multivariate, cell nuclear data is described. The experimental equipment and methods are discussed, the mathematics used are presented, and the additions, modifications and deletions to the TICAS 11/45 set of computer programs for the analysis of the data are outlined.