Morphological and molecular data on the origin of angiosperms: on a way to a synthesis

Molecular phylogenetic data have drastically changed the views on the phylogeny of higher plants. All the extant gymnosperms were asserted as a monophyletic group opposed to the highly isolated angiosperms. The 'Anthophyte Theory' was thus rejected. The identification and analysis of gymnosperm orthologues of genes regulating flower development in angiosperms resulted in the formulation of the 'Mostly Male Theory' of the evolutionary origin of flower; this theory does not contradict the concept of monophyly of all the extant gymnosperms. The Mostly Male Theory assumes that the origin of angiosperms was caused by a loss of the Needle family gene that effected ovuliferous (female) organs and the translocation of the ovules onto the adaxial side of some of the (male) leafy microsporangiophores. Having acquired ovules, the former microsporangiophores started evolving into the carpels. The prerequisite bisexual design of the ancestral fructification thus becomes unnecessary. Indeed, this assumption suggests the deriving of Angiosperms from any gymnosperm plant with leafy microsporangiophores. The problem of carpel origin has subsequently changed to some degree into the problem of the origin of the bitegmic anatropous ovule presumably inherent in ancestral Angiosperms. The Mostly Male Theory consideredeither Corystospermataceae (= Umkomasiaceae) or Caytoniaceae to be the forerunners of such an ovule. Yet the capsules of Corystospermataceae distinctly differ from angiosperm ovules in the locations of their adaxial/abaxial sides, while Caytoniaceae had no leafy microsporangiophores. This inconsistency suggests that functions of the Needle family regulatory genes in Gymnosperms should be much better understood to appraise properly both the possibilities and the consequences of their hypothetical loss by the emerging angiosperms. Moreover, the extant gymnosperm groups are actually held as monophyletic and contrasted to Angiosperms on the basis of analysing the unrepresentative scant remnants of these, mostly extinct, taxa. Therefore, traditional botanical and paleobotanical data should not be rejected. In any case, Meyen's idea angiosperms origin from Bennettitales is worth being retained as a hypothesis to be tested with new results of both paleobotany and molecular biology.     

Evolution on oceanic islands: molecular phylogenetic approaches to understanding pattern and process

By their very nature oceanic island ecosystems offer great opportunities for the study of evolution and have for a long time been recognized as natural laboratories for studying evolution owing to their discrete geographical nature and diversity of species and habitats. The development of molecular genetic methods for phylogenetic reconstruction has been a significant advance for evolutionary biologists, providing a tool for answering questions about the diversity among the flora and fauna on such islands. These questions relate to both the origin and causes of species diversity both within an archipelago and on individual islands. Within a phylogenetic framework one can answer fundamental questions such as whether ecologically and/or morphologically similar species on different islands are the result of island colonization or convergent evolution. Testing hypotheses about ages of the individual species groups or entire community assemblages is also possible within a phylogenetic framework. Evolutionary biologists and ecologists are increasingly turning to molecular phylogenetics for studying oceanic island plant and animal communities and it is important to review what has been attempted and achieved so far, with some cautionary notes about interpreting phylogeographical pattern on oceanic islands.     

Diversity in obscurity: fossil flowers and the early history of angiosperms

In the second half of the nineteenth century, pioneering discoveries of rich assemblages of fossil plants from the Cretaceous resulted in considerable interest in the first appearance of angiosperms in the geological record. Darwin''s famous comment, which labelled the ‘rapid development’ of angiosperms an ‘abominable mystery’, dates from this time. Darwin and his contemporaries were puzzled by the relatively late, seemingly sudden and geographically widespread appearance of modern-looking angiosperms in Late Cretaceous floras. Today, the early diversification of angiosperms seems much less ‘rapid’. Angiosperms were clearly present in the Early Cretaceous, 20–30 Myr before they attained the level of ecological dominance reflected in some mid-Cretaceous floras, and angiosperm leaves and pollen show a distinct pattern of steadily increasing diversity and complexity through this interval. Early angiosperm fossil flowers show a similar orderly diversification and also provide detailed insights into the changing reproductive biology and phylogenetic diversity of angiosperms from the Early Cretaceous. In addition, newly discovered fossil flowers indicate considerable, previously unrecognized, cryptic diversity among the earliest angiosperms known from the fossil record. Lineages that today have an herbaceous or shrubby habit were well represented. Monocotyledons, which have previously been difficult to recognize among assemblages of early fossil angiosperms, were also diverse and prominent in many Early Cretaceous ecosystems.     

Internal transcribed spacer rDNA can be used to infer the phylogenetic relationships of species within the genus Nematodirus (Nematoda: molineoidea)

Sequences of the first internal transcribed spacer rDNA were characterised for four veterinary important species of gastrointestinal nematodes from the genus Nematodirus. The sequence data were combined with previously published data of the second internal transcribed spacer to determine whether these rDNA regions provided a suitable number of informative characters to determine the phylogenetic relationships of species within the genus. A total of 32 alignment positions of the first internal transcribed spacer data set and 33 characters from the second internal transcribed spacer data set were informative in phylogenetic analyses. Irrespective of whether the data from each spacer were analysed separately or combined, only one most parsimonious tree was produced, with the relationships of the four species fully resolved. In addition, several regions of conservatism in the first internal transcribed spacer sequence among the four Nematodirus species suggests that this rDNA region may also provide phylogenetic information for higher taxonomic levels within the Molineoidea.     

Parasite histories and novel phylogenetic tools: alternative approaches to inferring parasite evolution from molecular markers

Parasitological research is often contingent on the knowledge of the phylogeny/genealogy of the studied group. Although molecular phylogenetics has proved to be a powerful tool in such investigations, its application in the traditional fashion, based on a tree inference from the primary nucleotide sequences may, in many cases, be insufficient or even improper. These limitations are due to a number of factors, such as a scarcity/ambiguity of phylogenetic information in the sequences, an intricacy of gene relationships at low phylogenetic levels, or a lack of criteria when deciding among several competing coevolutionary scenarios. With respect to the importance of a precise and reliable phylogenetic background in many biological studies, attempts are being made to extend molecular phylogenetics with a variety of new data sources and methodologies. In this review, selected approaches potentially applicable to parasitological research are presented and their advantages as well as drawbacks are discussed. These issues include the usage of idiosyncratic markers (unique features with presumably low probability of homoplasy), such as insertion of mobile elements, gene rearrangements and secondary structure features; the problem of ancestral polymorphism and reticulate relationships at low phylogenetic levels; and the utility of a molecular clock to facilitate discrimination among alternative scenarios in host-parasite coevolution.     

Morphological, phylogenetic and biological characteristics of Ectropis obliqua single-nucleocapsid nucleopolyhedrovirus

The tea looper caterpillar, Ectropis obliqua, is one of the major pests of tea bushes. E. obliqua single-nucleocapsid nucleopolyhedrovirus (EcobSNPV) has been used as a commercial pesticide for biocontrol of this insect. However only limited genetic analysis for this important virus has been done up to now. EcobSNPV was characterized in this study. Electron microscopy analysis of the occlusion body showed polyhedra of 0.7 to 1.7 mum in diameter containing a single nucleocapsid per envelope of the virion. A 15.5 kb genomic fragment containing EcoRI-L, EcoRI-N and HindIII-F fragments, was sequenced. Analysis of the sequence revealed that the fragment contained eleven potential open reading frames (ORFs): lef-1, egt, 38.7k, rr1, polyhedrin, orf1629, pk-1, hoar and homologues to Spodoptera exigua multicapsid NPV (SeMNPV) ORFs 15, 28, and 29. Gene arrangement and phylogeny analysis suggest that EcobSNPV is closely related to the previously described Group II NPV. Bioassays on lethal concentration (LC(50) and LC(90)) and lethal time (LT(50) and LT(90)) were conducted to test the susceptibility of E. obliqua larvae to the virus.     

Basal teleosts and the question of elopomorph monophyly. Morphological and molecular approaches

The methodology used by previous authors to resolve the relationships of the elopomorphan taxa is criticized. The morphological characters that have been proposed to support the monophyly of the Elopomorpha are reviewed and it is shown that most of them are weak. A new hypothesis of relationships is proposed on the basis of nucleotidic sequences of ribosomal RNA 18S, 16S and 12S. In order to really test all the possible relationships, the monophyly of the Elopomorpha was not considered a priori. The tree was rooted on Amia calva and Lepisosteus osseus and the ingroup taxa sampling was subsequently increased. The obtained topology shows that the Elopomorpha is a non-monophyletic taxon. Elopiforms, anguilliforms, albuliforms and notacanthiforms are considered here as four monophyletic, incertae sedis taxa among basal teleosts.     

Biological and molecular characterisation of Prunus necrotic ringspot virus isolates and possible approaches to their phylogenetic typing

Seven isolates of Prunus necrotic ringspot virus (PNRSV) originating from Slovakia were subjected to biological tests under glasshouse conditions. Mainly mild symptoms were observed on chip‐budded test cherry rootstocks. The complete sequence for the capsid protein (CP) gene of four isolates was determined. All sequences were 675 nucleotides long and clustered in the largest of four groups delineated by phylogenetic analyses of all so far known PNRSV CP sequences. A set of restriction endonucleases was suggested to differentiate four isolate clusters by restriction enzyme digestion of CP sequences.     

Morphological and molecular identification of Leptosphaeria maculans in canola seeds and flowers collected from the North Iran

Blackleg disease, caused by Leptosphaeria maculans, is one of the most important diseases of rapeseed Brassica napus in Iran as in other regions of the world. The samples including canola petals and seeds were collected during 2014–2015 from canola field in North Iran. Isolates characteristics of fungus were assessed based on the colony growth rate and pycnidia in Potato Dextrose Agar. The pycnidia of the fungus were black, globose to subglobose in shape, the single-celled conidia, hyaline and fusiform with diameters of 4–5 × 1.5–2 μm. Most of the isolates were produced pigment in the liquid culture in variable color brown to black. Thirteen isolates were then separated into pathogenicity groups based on the interactions on B. napus differential cultivars. For the direct detection of seed contamination with L. maculans, PCR was developed using specific primers pair (LmacF, LmacR) which can amplify ITS1 and ITS2 along with the 5.8S rRNA region of L. maculans genome. Based on the followed information and sequence analysis, the fungal isolates from these samples were identified as L. maculans. The findings of this research showed that the disease was aggressive and highly distributed from infested seeds to oilseed rape fields.     

Morphological variation of intervessel pit membranes and implications to xylem function in angiosperms

Pit membranes between xylem vessels have been suggested to have functional adaptive traits because of their influence on hydraulic resistance and vulnerability to embolism in plants. Observations of intervessel pit membranes in 26 hardwood species using electron microscopy showed significant variation in their structure, with a more than 25-fold difference in thickness (70-1892 nm) and observed maximum pore diameter (10-225 nm). In some SEM images, pit membrane porosity was affected by sample preparation, although pores were resolvable in intact pit membranes of many species. A significant relationship (r(2) = 0.7, P = 0.002) was found between pit membrane thickness and maximum pore diameter, indicating that the thinner membranes are usually more porous. In a subset of nine species, maximum pore diameter determined from SEM was correlated with pore diameter calculated from air-seeding thresholds (r(2) = 0.8, P < 0.001). Our data suggest that SEM images of intact pit membranes underestimate the porosity of pit membranes in situ. Pit membrane porosity based on SEM offers a relative estimate of air-seeding thresholds, but absolute pore diameters must be treated with caution. The implications of variation in pit membrane thickness and porosity to plant function are discussed.     

牦牛海马的形态特征及成体神经发生的初探

采用传统H.E 染色和Golgi-Cox 染色方法观察成年牦牛海马结构的形态和细胞构筑,并通过DCX - DAB免疫组化染色和DCX/ NeuN、GFAP / NeuN 双重免疫荧光标记等技术观察齿状回颗粒下层中的新生神经元和放射状胶质细胞。结果表明,牦牛海马结构主要包括齿状回和海马本部,二者分层清晰。海马的主要细胞为颗粒细胞、苔藓细胞和锥体细胞。CA3 区的锥体细胞胞体较CA1 区的大,但其顶树突的平均长度较短。CA1 区的锥体细胞明显分为两层,而CA3 区的则为一层。DCX 阳性细胞的胞体主要集中在齿状回颗粒下层靠近门区处,沿颗粒层内侧单个或少数聚集分布。沿齿状回颗粒下层分布着一层GFAP 阳性的放射状胶质细胞样细胞,其胞质和单极性的细长突起均呈GFAP 阳性,而胞核为阴性。在整个海马结构中均有大量星形GFAP 阳性细胞散在分布,特别是海马分子层和门区内靠近颗粒层部分的密度较其它部位大。牦牛海马的形态结构与绵羊的相似,而与大鼠、小鼠、家猫、兔子等小型哺乳动物有一定差别。两种DCX 免疫组化实验结果表明在牦牛海马中存在着新生神经元。GFAP 免疫荧光标记表明,牦牛海马结构中分布有星形胶质细胞;特别是放射状胶质细胞。     

Division of labour within flowers: heteranthery,a floral strategy to reconcile contrasting pollen fates

In many nectarless flowering plants, pollen serves as both the carrier of male gametes and as food for pollinators. This can generate an evolutionary conflict if the use of pollen as food by pollinators reduces the number of gametes available for cross‐fertilization. Heteranthery, the production of two or more stamen types by individual flowers reduces this conflict by allowing different stamens to specialize in ‘pollinating’ and ‘feeding’ functions. We used experimental studies of Solanum rostratum (Solanaceae) and theoretical models to investigate this ‘division of labour’ hypothesis. Flight cage experiments with pollinating bumble bees (Bombus impatiens) demonstrated that although feeding anthers are preferentially manipulated by bees, pollinating anthers export more pollen to other flowers. Evolutionary stability analysis of a model of pollination by pollen consumers indicated that heteranthery evolves when bees consume more pollen than should optimally be exchanged for visitation services, particularly when pollinators adjust their visitation according to the amount of pollen collected.     

Comparison of whole chloroplast genome sequences to choose noncoding regions for phylogenetic studies in angiosperms: the tortoise and the hare III

Although the chloroplast genome contains many noncoding regions, relatively few have been exploited for interspecific phylogenetic and intraspecific phylogeographic studies. In our recent evaluation of the phylogenetic utility of 21 noncoding chloroplast regions, we found the most widely used noncoding regions are among the least variable, but the more variable regions have rarely been employed. That study led us to conclude that there may be unexplored regions of the chloroplast genome that have even higher relative levels of variability. To explore the potential variability of previously unexplored regions, we compared three pairs of single-copy chloroplast genome sequences in three disparate angiosperm lineages: Atropa vs. Nicotiana (asterids); Lotus vs. Medicago (rosids); and Saccharum vs. Oryza (monocots). These three separate sequence alignments highlighted 13 mutational hotspots that may be more variable than the best regions of our former study. These 13 regions were then selected for a more detailed analysis. Here we show that nine of these newly explored regions (rpl32-trnL((UAG)), trnQ((UUG))-5'rps16, 3'trnV((UAC))-ndhC, ndhF-rpl32, psbD-trnT((GGU)), psbJ-petA, 3'rps16-5'trnK((UUU)), atpI-atpH, and petL-psbE) offer levels of variation better than the best regions identified in our earlier study and are therefore likely to be the best choices for molecular studies at low taxonomic levels.     

The age of the angiosperms: a molecular timescale without a clock

The age of the angiosperms has long been of interest to botanists and evolutionary biologists. Many early efforts to date the age of the angiosperms and evolutionary divergences within the angiosperm clade using a molecular clock have yielded age estimates that are grossly inconsistent with the fossil record. We investigated the age of angiosperms using Bayesian relaxed clock (BRC) and penalized likelihood (PL) approaches. Both of these methods allow the incorporation of multiple fossil constraints into the optimization procedure. The BRC method allows a range of values for among-lineage rate of substitution, from a nearly clocklike behavior to a condition in which each branch is allowed an optimal substitution rate, and also accounts for variation in molecular evolution across multiple genes. A topology derived from an analysis of genes from all three plant genomes for 71 taxa was used as a backbone. The effects on age estimates of different genes, single-gene versus concatenated datasets, and the inclusion and assumptions of fossils as age constraints were examined. In addition, the influence of prior distributions on estimates of divergence times was also explored. These results indicate that widely divergent age estimates can result from the different methods (198-139 million years ago), different sources of data (275-122 million years ago), and the inclusion of temporal constraints to topologies. Most dates, however, are between 180-140 million years ago, suggesting a Middle Jurassic-Early Cretaceous origin of flowering plants, predating the oldest unequivocal fossil angiosperms by about 45-5 million years. Nonetheless, these dates are consistent with other recent studies that have used methods that relax the assumption of a strict molecular clock and also agree with the hypothesis that the angiosperms may be somewhat older than the fossil record indicates.     

Tiger mosquito control: new approaches to the issue in local context

Until recently, the control of mosquitoes has primarily focused on them as a nuisance due to their biting behaviour. This has now evolved into a significant health problem. To deal with this serious issue, a rational approach to vector control should be adopted, with clear, technically sound guidelines enforceable by legislation. The extensive outbreak of Chikungunya in the Indian Ocean during 2005-6 and the subsequent outbreak in the Emilia Romagna region of Italy in August 2007, should prompt a number of actions which must occur without delay in order to prevent any future recurrence of outbreaks. An International Symposium on Chikungunya was held in Alessandria, Italy on February 27th 2008. A number of experts from various disciplines were in attendance, the sole aim to assess the risk of this disease and other mosquito borne diseases occurring in Europe. The meeting culminated in the signing of a declaration called the "Alessandria Resolution" by the experts in attendance and members of several local authorities (see www.zanzare.eu). This act signified joint commitment of an national and international standing, to tackle the spread of the Asian Tiger mosquito and raise awareness among the general public. This paper will share the experiences of the mosquito control programmes in the Italian regions and in Alessandria and Piedmont emphasising key lessons learned.     

Nanobiotechnology: the promise and reality of new approaches to molecular recognition

Nanobiotechnology is the convergence of engineering and molecular biology that is leading to a new class of multifunctional devices and systems for biological and chemical analysis with better sensitivity and specificity and a higher rate of recognition. Nano-objects with important analytical applications include nanotubes, nanochannels, nanoparticles, nanopores and nanocapacitors. Here, we take a critical look at the subset of recent developments in this area relevant to molecular recognition. Potential benefits of using nano-objects (nanotubes, quantum dots, nanorods and nanoprisms) and nanodevices (nanocapacitors, nanopores and nanocantilevers) leading to an expanded range of label multiplexing are described along with potential applications in future diagnostics. We also speculate on further pathways in nanotechnology development and the emergence of order in this somewhat chaotic, yet promising, new field.     

Molecular evolution and phylogenetic utility of the petD group II intron: a case study in basal angiosperms

Sequences of spacers and group I introns in plant chloroplast genomes have recently been shown to be very effective in phylogenetic reconstruction at higher taxonomic levels and not only for inferring relationships among species. Group II introns, being more frequent in those genomes than group I introns, may be further promising markers. Because group II introns are structurally constrained, we assumed that sequences of a group II intron should be alignable across seed plants. We designed universal amplification primers for the petD intron and sequenced this intron in a representative selection of 47 angiosperms and three gymnosperms. Our sampling of taxa is the most representative of major seed plant lineages to date for group II introns. Through differential analysis of structural partitions, we studied patterns of molecular evolution and their contribution to phylogenetic signal. Nonpairing stretches (loops, bulges, and interhelical nucleotides) were considerably more variable in both substitutions and indels than in helical elements. Differences among the domains are basically a function of their structural composition. After the exclusion of four mutational hotspots accounting for less than 18% of sequence length, which are located in loops of domains I and IV, all sequences could be aligned unambiguously across seed plants. Microstructural changes predominantly occurred in loop regions and are mostly simple sequence repeats. An indel matrix comprising 241 characters revealed microstructural changes to be of lower homoplasy than are substitutions. In showing Amborella first branching and providing support for a magnoliid clade through a synapomorphic indel, the petD data set proved effective in testing between alternative hypotheses on the basal nodes of the angiosperm tree. Within angiosperms, group II introns offer phylogenetic signal that is intermediate in information content between that of spacers and group I introns on the one hand and coding sequences on the other.     

Morphological character evolution and molecular trees in sepiids (Mollusca: Cephalopoda): is the cuttlebone a robust phylogenetic marker?

The sepiids are characterized by their cuttlebone or sepion, an internal shell resulting from secondary mineralization of a chitinous 'gladius'. The various species are identified using a combination of shell criteria and 'soft-part' characters. Using mitochondrial genes, we established phylogenetic relationships of sepiids including the three accepted genera ( Sepia , Sepiella , Metasepia ) and a species complex of uncertain status ( Doratosepion ). We showed the Sepia genus to be paraphyletic and found no direct correlation between geographical distribution and systematics. We mapped, on the molecular tree, shell characteristics commonly used as reliable diagnostic criteria for taxonomy. Due to the plasticity of the shell, these characters did not appear phylogenetically informative. In an attempt to define systematic categories related to phylogenetic relationships, new clear synapomorphies need to be established for each genus, necessitating a revision of the genus Sepia .  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 89 , 139–150.