Sesquiterpene lactone-based classification of three Asteraceae tribes: a study based on self-organizing neural networks applied to chemosystematics

This work describes an application of artificial neural networks on a small data set of sesquiterpene lactones (STLs) of three tribes of the family Asteraceae. Structurally different types of representative STLs from seven subtribes of the tribes Eupatorieae, Heliantheae and Vernonieae were selected as input data for self-organizing neural networks. Encoding the 3D molecular structures of STLs and their projection onto Kohonen maps allowed the classification of Asteraceae into tribes and subtribes. This approach allowed the evaluation of structural similarities among different sets of 3D structures of sesquiterpene lactones and their correlation with the current taxonomic classification of the family. Predictions of the occurrence of STLs from a plant species according to the taxa they belong to were also performed by the networks. The methodology used in this work can be applied to chemosystematic or chemotaxonomic studies of Asteraceae.     

TRIBAL INTERRELATIONSHIPS OF THE ASTERACEAE

Abstract— A cladistic analysis involving 27 tribes and subtribes of Asteraceae and 81 characters is presented. The terminal taxa are mainly those of present tribal classification, though some apparently poly- and paraphyletic tribes, notably the Mutisieae and the Inuleae, have been represented by sub-tribal taxa. Characters are assembled from all available sources. Corolla types, styles and stamens have provided many characters. The Lobeliaceae are used as an outgroup and are considered as the most probable sister group of the Asteraceae. There is a basal dichotomy in the family, the Mutisieae-Barnadesiinae being the monophyletic sister group of the remaining major, also monophyletic part of the family. The recent family division into two subfamilies about equal in size, the Cichorioideae and the Asteroideae, neither represents a basal dichotomy nor a sister group relationship within the Asteraceae. The Asteroideae are monophyletic and have their sister group within the paraphyletic Cichorioideae. Interrelationships among the cichorioid tribes are still unclear. The Lactuceae, Eremothamneae, Vernonieae and Liabeae may be one monophyletic group, and the Arctoteae, Carlineae, Echinopsideae and Cardueae another. The Mutisieae are a paraphyletic grade at the base of the family. Within the subfamily Asteroideae tribal interrelationships are also rather unclear. The Anthemideae and the Heliantheae sensu lato (including the Helenieae, Tageteae, Coreopsideae and all helenioid/helianthoid representatives sometimes placed in the Senecioneae) may be sister groups. The Heliantheae appear to be monophyletic and there is little support for the hypothesis that other tribes are derived from or have their sister group within the Heliantheae. The Astereae and the Eupatorieae may be sister groups, though a closer relationship between the Eupatorieae and the Heliantheae is possible. The Inuleae are a paraphyletic grade group at the base of the subfamily Asteroideae in the same way as the Mutiseae are a grade group at the base of the family.     

Chemodiversity of exudate flavonoids in seven tribes of Cichorioideae and Asteroideae (Asteraceae)

Members of several genera of Asteraceae, belonging to the tribes Mutisieae, Cardueae, Lactuceae (all subfamily Cichorioideae), and of Astereae, Senecioneae, Helenieae and Heliantheae (all subfamily Asteroideae) have been analyzed for chemodiversity of their exudate flavonoid profiles. The majority of structures found were flavones and flavonols, sometimes with 6- and/or 8-substitution, and with a varying degree of oxidation and methylation. Flavanones were observed in exudates of some genera, and, in some cases, also flavonol- and flavone glycosides were detected. This was mostly the case when exudates were poor both in yield and chemical complexity. Structurally diverse profiles are found particularly within Astereae and Heliantheae. The tribes in the subfamily Cichorioideae exhibited less complex flavonoid profiles. Current results are compared to literature data, and botanical information is included on the studied taxa.     

A general survey and some taxonomic implications of diterpenes in the Asteraceae

This paper provides a general survey of the occurrence of diterpenes in the Asteraceae. Data on 4351 botanical occurrences were obtained from the literature. These were grouped by skeleton for each genus. Then, the genera were grouped by subtribes, which, in turn, were gathered in tribes, followed by subfamilies. In spite of the low number of species containing diterpenes, it was possible to describe some structural features of these compounds, i.e. the skeletal types in various taxa and the positions in some skeletons that are always oxidized or never undergo oxidation in some genera. Thus, it was verified that: in the subfamily Cichorioideae, only a few of the studied species possess diterpenes, wherein kaurane is the most frequent diterpene skeleton. In the Asteroideae, the presence of diterpenes is much greater than that in the Cichorioideae and Carduoideae. At tribal taxonomic level, for example, the Astereae produce labdanes and clerodanes; Heliantheae and Eupatorieae produce kauranes and labdanes, respectively; and Calenduleae produce pimaranes. Some taxonomic implications are presented.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 147 , 291–308.     

FINE STRUCTURE OF PETROBINAE (COMPOSITAE-HELIANTHEAE) POLLEN WALLS

Pollen of the subtribe Petrobinae (Compositae-Heliantheae) was examined by light and electron microscopy. Surface morphology and fine structure of all species examined were identical; these characters also were similar to pollen of other Heliantheae subtribes examined in previous studies.     

HENRICKSONIA (ASTERACEAE-COREOPSIDINAE), A NEWLY DISCOVERED GENUS WITH A PALEACEOUS PAPPUS FROM NORTH-CENTRAL MEXICO

A new genus, Henricksonia, containing the single species H. mexicana, has been described from a locality in north-central Mexico. It is unique among the genera of the subtribe Coreopsidinae in possessing a pappus of well-developed scales such as frequently occurs in other subtribes of the Heliantheae. The discovery of four, previously uncollected, monotypic genera among several tribes of the Asteraceae from this region over the past several years suggests that the area is a primary center of diversification for this large family.     

Pollen Morphology in Tribe Lactuceae (Compositae)

The Lactuceae contain two basic pollen types, echinolophate and echinate. Most taxa have echinolophate, tricolporate pollen. Internally, most ektexines are composed of a perforate spiny tectum, several levels of columellae, a cavus, and a foot layer. In lacunae, the columellae are reduced to a single level and the cavus is often absent. Highly modified echinolophate pollen grains are found in Scolymus, Scorzonera and Tragopogon. Scolymus, Catananche, Scorzonera, and Tolpis have distinctive exine stratification patterns. Exines of Catananche and, to a lesser extent, those of Tragopogon contain internal foramina like those found in the Heliantheae. Echinate pollen is found in all subtribes and is probably ancestral. However, some echinate grains are probably derived.     

Tympanal and atympanal 'mouth-ears' in hawkmoths (Sphingidae).

The labral pilifers and the labial palps form ultrasound-sensitive hearing organs in species of two distantly related hawkmoth subtribes, the Choerocampina and the Acherontiina. Biomechanical examination now reveals that their ears represent different types of hearing organs. In hearing species of both subtribes, the labral pilifer picks up vibrations from specialized sound-receiving structures of the labial palp that are absent in non-hearing species. In Choerocampina, a thin area of cuticle serves as an auditory tympanum, whereas overlapping scales functionally replace a tympanum in Acherontiina that can hear. The tympanum of Choerocampina and the scale-plate of Acherontiina both vibrate maximally in response to ultrasonic, behaviourally relevant sounds, with the vibrations of the tympanum exceeding those of the scale plate by ca. 15 dB. This amplitude difference, however, is not reflected in the vibrations of the pilifers and the neural auditory sensitivity is similar in hearing species of both subtribes. Accordingly, morphologically different - tympanal and atympanal - but functionally equivalent hearing organs evolved independently and in parallel within a single family of moths.     

Evolutionary relationships in the showy mistletoe family (Loranthaceae)

Loranthaceae (73 genera and ca. 900 species) comprise mostly aerial hemiparasitic plants. Three monotypic genera considered relicts are root parasites. The family is diverse in tropical areas, but representatives are also found in temperate habitats. Previous classifications were based on floral and inflorescence morphology, karyological information, and biogeography. The family has been divided into three tribes: Nuytsiae, Elytrantheae (subtribes Elytranthinae and Gaiadendrinae), and Lorantheae (subtribes Loranthinae and Psittacanthinae). Nuytsiae and Elytrantheae are characterized by a base chromosome number of x = 12, whereas subtribes Loranthinae (x = 9) and Psittacanthinae (x = 8) numbers are derived via aneuploid reduction. To elucidate the phylogeny of the family, we analyzed sequences from five genes (nuclear small and large subunit rDNA and the chloroplast genes rbcL, matK, and trnL-F) representing most genera using parsimony, likelihood, and Bayesian inference. The three root parasites, Nuytsia, Atkinsonia, and Gaiadendron, are supported as successive sister taxa to the remaining genera, resulting in a monophyletic group of aerial parasites. Three major clades are resolved each corresponding to a subtribe. However, two South American genera (Tristerix and Notanthera) and the New Zealand genus Tupeia, which were previously classified in subtribe Elytranthinae, are weakly supported as part of a clade representing the South American subtribe Psittacanthinae.     

Rapid identification of streptomycetes by artificial neural network analysis of pyrolysis mass spectra

Abstract An artificial neural network was trained to distinguish between three putatively novel species of Streptomyces using normalised, scaled pyrolysis mass spectra from three representative strains of each of the taxa, each sampled in triplicate. Once trained, the artificial neural network was challenged with spectral data from the original organisms, the 'training set', from additional members of the putative novel taxa and from over a hundred strains representing six other actinomycete genera. All of the streptomycetes were correctly identified but many of the other actinomycetes were mis-identified. A modified network topology was developed to recognise the mass spectral patterns of the non-streptomycete strains. The resultant neural network correctly identified the streptomycetes, whereas all of the remaining actinomycetes were recognised as unknown organisms. The improved artificial neural network provides a rapid, reliable and cost-effective method of identifying members of the three target streptomycete taxa.     

Evaluating the performance of artificial neural networks for the classification of freshwater benthic macroinvertebrates

Macroinvertebrates form an important functional component of aquatic ecosystems. Their ability to indicate various types of anthropogenic stressors is widely recognized which has made them an integral component of freshwater biomonitoring. The use of macroinvertebrates in biomonitoring is dependent on manual taxa identification which is currently a time-consuming and cost-intensive process conducted by highly trained taxonomical experts. Automated taxa identification of macroinvertebrates is a relatively recent research development. Previous studies have displayed great potential for solutions to this demanding data mining application. In this research we have a collection of 1350 images from eight different macroinvertebrate taxa and the aim is to examine the suitability of artificial neural networks (ANNs) for automated taxa identification of macroinvertebrates. More specifically, the focus is drawn on different training algorithms of Multi-Layer Perceptron (MLP), probabilistic neural network (PNN) and Radial Basis Function network (RBFN). We performed thorough experimental tests and we tested altogether 13 training algorithms for MLPs. The best classification accuracy of MLPs, 95.3%, was obtained by two conjugate gradient backpropagation variations and scaled conjugate gradient backpropagation. For PNN 92.8% and for RBFN 95.7% accuracies were achieved. The results show how important a proper choice of ANN is in order to obtain high accuracy in the automated taxa identification of macroinvertebrates and the obtained model can outperform the level of identification which is made by a taxonomist.     

Chromosome numbers in the tribe Anthemideae (Asteraceae) from north-east Anatolia

Twenty-two chromosome counts of 19 taxa in the tribe Anthemideae of the family Asteraceae are reported from north-east Anatolia, Turkey. The taxa belong to the subtribes Achilleinae (four Achillea taxa), Anthemidinae (five Anthemis taxa), Artemisiinae (two Artemisia species), Leucantheminae (one Lecanthemum species), Matricariinae (two Tripleurospermum species) and Tanacetinae (five Tanacetum taxa). Six counts are new reports, seven are not consistent with previous counts, and the remainder are confirmations of very limited previous data. Most of the populations of Anthemideae studied have the basic number x  = 9, with ploidy levels ranging from 2 x to 7 to 8 x , but dysploidy is also present, with one diploid species, Artemisia austriaca , having x  = 8.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 153 , 203–211.     

Molecular phylogenetics of Erebidae (Lepidoptera,Noctuoidea)

As a step towards understanding the higher‐level phylogeny and evolutionary affinities of quadrifid noctuoid moths, we have undertaken the first large‐scale molecular phylogenetic analysis of the moth family Erebidae, including almost all subfamilies, as well as most tribes and subtribes. DNA sequence data for one mitochondrial gene (COI) and seven nuclear genes (EF‐1α, wingless, RpS5, IDH, MDH, GAPDH and CAD) were analysed for a total of 237 taxa, principally type genera of higher taxa. Data matrices (6407 bp in total) were analysed by parsimony with equal weighting and model‐based evolutionary methods (maximum likelihood), which revealed a well‐resolved skeleton phylogenetic hypothesis with 18 major lineages, which we treat here as subfamilies of Erebidae. We thus present a new phylogeny for Erebidae consisting of 18 moderate to strongly supported subfamilies: Scoliopteryginae, Rivulinae, Anobinae, Hypeninae, Lymantriinae, Pangraptinae, Herminiinae, Aganainae, Arctiinae, Calpinae, Hypocalinae, Eulepidotinae, Toxocampinae, Tinoliinae, Scolecocampinae, Hypenodinae, Boletobiinae and Erebinae. Where possible, each monophyletic lineage is diagnosed by autapomorphic morphological character states, and within each subfamily, monophyletic tribes and subtribes can be circumscribed, most of which can also be diagnosed by morphological apomorphies. All additional taxa sampled fell within one of the four previously recognized quadrifid families (mostly into Erebidae), which are now found to include two unusual monobasic taxa from New Guinea: Cocytiinae (now in Erebidae: Erebinae) and Eucocytiinae (now in Noctuidae: Pantheinae).     

Sesquiterpene lactones as taxonomic characters in the asteraceae

The Asteraceae is characterized by structurally diverse sesquiterpene lactones and furanosesquiterpenes. In this review the tribal, subtribal and generic distribution of sesquiterpene lactones is examined and the compounds’ utility as taxonomic characters discussed. Sesquiterpene lactones fulfill the major requirements for good analytic and synthetic characters. Studies of infraspecific sesquiterpene lactone variation indicate that different elements within complex taxa are often defined by distinct chemistries, termed chemotypes. Chemotypes have been identified within many of the thoroughly investigated taxa:Ambrosia camphorata, A. chamissonis, A. confertiflora, theA. cumanensis-A. psilostachya-A. artemisiifolia complex,A. dumosa, Artemisia tridentata, Gaillardia pulchella andMelampodium leucanthum. Such an analytic usage is mostly restricted to the infraspecific level. Synthetic usage at the interspecific level and above profits from the application of a biogenetically based methodology for sorting out the complex molecules’ carbon-skeletal and substitutional features into unit characters. Cladistics or Hennigian phylogenetic systematics provides a useful framework for such an analysis. Preliminary surveys indicate that sesquiterpene lactones are especially good characters for differentiating subtribes within several major tribes: the Vernonieae, Heliantheae and Mutisieae. As yet, too few data are available for other tribes to discern such patterns. Species surveys inVernonia, Ambrosia, Iva, Parthenium,Tetragonotheca andArtemisia demonstrate that sesquiterpene lactones are useful in discerning infrageneric groups. The biogenetic cladistic analysis of the interspecific sesquiterpene lactone variation inIva shows the efficacy of this analytical methodology. At present, such biogenetically based approaches are impeded by limited biosynthetic evidence and the erratic distribution of sesquiterpene lactones within the family. Instances of apparent displacement of sesquiterpene lactones by other terpenoids (i.e. sesquiterpene furans, alcohols and acids, diterpenes, diterpene acids, etc.) at various taxonomic levels suggest that ultimately sesquiterpene lactones must be interpreted as taxonomic characters in the context of the family’s total terpene chemistry. All taxa from which sesquiterpene lactones have been reported are listed together with the compound names, major structural features and the literature cited. A less-complete listing is provided for taxa producing furanosesquiterpenes. Structures for all reported compounds are included. Two appendices listing alphabetically taxa and compounds and relevant text page numbers permit cross-indexing of plants and compounds.     

Insecticide mixtures for mosquito net impregnation against malaria vectors

Insecticides belonging to the pyrethroid family are the only compounds currently available for the treatment of mosquito nets. Unfortunately, some malaria vector species have developed resistance to pyrethroids and the lack of alternative chemical categories is a great concern. One strategy for resistance management would be to treat mosquito nets with a mixture associating two insecticides having different modes of action. This study presents the results obtained with insecticide mixtures containing several proportions of bifenthrin (a pyrethroid insecticide) and carbosulfan (a carbamate insecticide). The mixtures were sprayed on mosquito net samples and their efficacy were tested against a susceptible strain of Anopheles gambiae, the major malaria vector in Africa. A significant synergism was observed with a mixture containing 25 mg/m2 of bifenthrin (half the recommended dosage for treated nets) and 6.25 mg/m2 of carbosulfan (about 2% of the recommended dosage). The observed mortality was significantly more than expected in the absence of any interaction (80% vs 41%) and the knock-down effect was maintained, providing an effective barrier against susceptible mosquitoes.     

Distribution of unsaturated aliphatic acid amides in japanese Zanthoxylum species

Seven species and two varieties of Zanthoxylum in Japan were investigated for unsaturated aliphatic acid amides. In addition to the known amides α-sanshoöl, γ-sanshoöl and hydroxy-γ-sanshoöl, a new compound, hydroxy-α-sanshoöl, was isolated and established by chemical and spectroscopic evidence. The compounds, corresponding to hydroxyl derivatives of the amides in the barks, commonly existed in the pericarps of all collected materials. Japanese Zanthoxylum species were divided chemotaxonomically into two taxa. These taxa ditter from the two assigned on the basis of botanical classification.     

A preliminary molecular phylogenetic assessment of the lichen moths (Lepidoptera: Erebidae: Arctiinae: Lithosiini) with comments on palatability and chemical sequestration

The lichen moth tribe Lithosiini is best known for its hypothesized larval feeding behaviour, lichenivory. The larvae of some species have been found to be capable of sequestering polyphenolics, and the adults of some species are unpalatable to vertebrate predators. However, the chemical basis for the defence is unknown. Here we reconstruct a phylogenetic hypothesis using likelihood methods (maximum likelihood, Bayesian inference) for 65 species of Lithosiini representing 37 genera and seven outgroup species using 2806 bp of sequence data obtained from two mitochondrial gene fragments (COI barcoding region, CytB), and two nuclear gene fragments (RpS5 and ribosomal gene region 28S). Lithosiine species representing four of the seven subtribes and unplaced taxa are included in the analysis. The deeper relationships within the tribe are not strongly supported, and the monophyly of three of the four subtribes is not supported. The placement of the fourth subtribe, Acsalina, is weakly supported. We also conduct a survey of the secondary metabolites present within adults of five species. The species are examined for the presence of lichen polyphenolics and plant secondary metabolites sequestered by arctiines. Seven lichen polyphenolics are identified in the taxa examined, but no plant secondary metabolites are found using either analytical method. The results of this study and prior reports in the literature of chemical sequestration and unpalatability are plotted onto the resulting Bayesian inference phylogeny to examine the evolution of chemical defence within Lithosiini. Species that sequester lichen polyphenolics and unpalatable species occur in each of the major clades recovered in the analysis.     

Towards the development of a macroinvertebrate sampling technique for palustrine wetlands in South Africa: a pilot investigation in the KwaZuluNatal midlands

A study was undertaken in November 2003 to derive a suitable sampling technique for collecting a representative sample of aquatic macroinvertebrates from a selected emergent vegetation biotope in a palustrine wetland, Melmoth Vlei, KwaZulu-Natal, South Africa. The aim was to undertake a preliminary investigation on the development and testing of a macroinvertebrate sampling technique for use in emergent sedge-dominated palustrine wetlands (sensu Cowardin et al. 1979), which could contribute to the development of a South African wetland health biomonitoring programme. Sweep nets and activity traps were evaluated for their effectiveness in terms of macroinvertebrate collection. Sweep net sampling was tested over a range of sweep intensities to determine the minimum number of sweeps required to collect a representative sample. Sampling efficiency of activity traps placed at four depths was tested, and taxon diversity and composition of sweep net and activity trap samples were compared to determine whether activity traps are required to supplement sweep net data. A total of 32 taxa (identified mainly to family level) were identified in the samples collected. Taxon diversity and composition did not differ in the activity traps placed at the four depth locations. Taxon diversity did not differ significantly between different sweep intensities. This may be a result of high variability of macroinvertebrate distribution within a wetland. There is evidence, however, to suggest that this result is due to an inadequate sample size. There was a significant difference in taxon composition between the different sweep intensities (P < 0.05) and between activity trap and sweep net samples (P < 0.05). Sixty-eight percent of taxa appeared more frequently in sweep net sampling than in activity trap sampling. Two taxa were found exclusively in activity traps, although the numbers of these taxa collected were not significant, and they do not represent any unique trophic group. Based on these findings, it was concluded that activity traps are not required to supplement sweep net data, and a technique using a sweep net with a sweep intensity of five would be suitable for collecting a representative sample of macroinvertebrates from a palustrine wetland.