Chloroplast DNA variation and phylogeny of theRanunculaceae

Restriction site mapping of chloroplast DNA from 31 species representing 26 genera of theRanunculaceae was performed using eleven restriction endonucleases. The chloroplast genome varies in length from approximately 152 to 160 kb. Length variants are frequent in theRanunculaceae and range from usually less than 300 bp to rarely 1.5 kb. The inverted repeat is extended into the large single copy (LSC) region by 4–4.5 kb inAnemone, Clematis, Clematopsis, Hepatica, Knowltonia, andPulsatilla. Several inversions are present in the LSC-region of the cpDNA in all these genera and inAdonis. The frequency of restriction site mutations varies within the chloroplast genome in theRanunculaceae between 4 and 32 mutations per kilobase, and is lowest in the inverted repeat and the regions containing the ATPase-genes and the genespsaA, psaB, psbA, rpoB, andrbcL. A total of 547 phylogenetically informative restriction sites was utilized in cladistic analyses of the family using Wagner, Dollo, and weighted parsimony. These three parsimony analyses result in different tree topologies. Four, six, and one equally most parsimonious trees were obtained with Wagner, Dollo, and weighted parsimony, respectively. The amount of support for the monophyletic groups was evaluated using bootstrapping and decay analysis. All three parsimony methods suggest thatHydrastis is the sister group to the remainder of theRanunculaceae, and that theAnemone-Clematis group, which shares several derived cpDNA rearrangements, is monophyletic. Only a few of the traditional groups in theRanunculaceae are supported by cpDNA restriction side data. Only Dollo parsimony provides support for the hypothesis thatThalictroideae andRanunculoideae are monophyletic.     

Ribosomal DNA variation and its phylogenetic implication in the genusBrachypodium (Poaceae)

The structure of ribosomal DNA ofBrachypodium and several other grass species was investigated using a heterologous rDNA probe from wheat. Several different rDNA families were present among perennial and annual species within the genus. In contrast to the annual species the perennial species exhibited a very low degree of repeat length variation. An extra Eco RI site and a Hin dIII site were observed in the IGS, which distinguishedBrachypodium from other grass genera. The restriction fragment length polymorphism and length variation of the repeat units have taxonomic value withinBrachypodium and are correlated with the classification ofBrachypodium derived from other data.     

The effect of salinity on the reproduction of coastal submerged macrophytes in experimental communities

The effects of salinity on the reproduction of coastal submerged macrophyte species were studied on samples of communities from six seasonal marshes in two outdoor experiments performed in autumn and in spring. The submerged macrophyte communities were submitted to five different salinity levels (0, 1, 2, 4 and 6 g/1 Cl^?1). In a companion paper (Grillas, van Wijck & Bonis 1993) three groups of species were distinguished on the basis of their biomass production over the salinity range 0 to 6 g/1 Cl^?1: (1) glycophytes (non-salt-tolerant species), (2) salt-tolerant species and (3) halo-phytes. This part of the study describes the impact of salinity on the reproduction of the individual species during the two experiments. The species differ in their capacity to reproduce in the autumn; only Zannichelliapedunculata and Tolypella hispánica were able to produce fruits in that season. For all species reproduction was greater in spring and strongly correlated with biomass, except for Chara canescens. Differences in reproductive effort over the salinity range amplified the halophytic nature of Ruppia marítima and Chara canescens and the intolerance of Callitriche truncata and Chara contraria. For the other species, reproductive effort did not differ significantly over the salinity range. Regarding the effect of salinity on biomass and reproductive effort of individual species, there were large differences in the total weight of propagules produced at the community level and in the relative contribution of individual species. The resulting quantitative changes in the species composition of the seed bank could affect the structure of the communities by their effects on the establishment and survival of species populations.     

Naegleria: A Research Partner For Cell and Developmental Biology1

ABSTRACT. Organisms in the genus Naegleria offer special opportunities for research in contemporary biology. the dramatic cell differentiation from amebae to flagellates is unique among eukaryotes in the rapidity, synchrony, reproducibility, homogeneity, and accessibility of a major phenotypic change. Environmental signals initiate a progressive signal transduction pathway in which genes are turned on, including those for several calcium-binding proteins, and newly synthesized proteins become localized in newly assembled organelles, including the centriole-like basal bodies, with the overall consequence that the cell changes its shape, motility, and behavior. This essay reviews research opportunities for which Naegleria excels, as well as interesting aspects of its biology that provide challenges for future investigations. Because these organisms alternate between two major eukaryotic motility forms, their phylogenetic position is also provocative. Although there are hints that Naegleria is capable of sexual reproduction in nature, mating has not yet been observed in the laboratory. In order to fully exploit the opportunities offered by this wonderful experimental system we are working to develop means to do genetic manipulation, in particular via DNA-mediated transformation.     

New branched Porolithon species (Corallinales,Rhodophyta) from the Great Barrier Reef,Coral Sea,and Lord Howe Island

Porolithon is one of the most ecologically important genera of tropical and subtropical crustose (non-geniculate) coralline algae growing abundantly along the shallow margins of coral reefs and functioning to cement reef frameworks. Thalli of branched, fruticose Porolithon specimens from the Indo-Pacific Ocean traditionally have been called P. gardineri, while massive, columnar forms have been called P. craspedium. Sequence comparisons of the rbcL gene both from type specimens of P. gardineri and P. craspedium and from field-collected specimens demonstrate that neither species is present in east Australia and instead resolve into four unique genetic lineages. Porolithon howensis sp. nov. forms columnar protuberances and loosely attached margins and occurs predominantly at Lord Howe Island; P. lobulatum sp. nov. has fruticose to clavate forms and free margins that are lobed and occurs in the Coral Sea and on the Great Barrier Reef (GBR); P. parvulum sp. nov. has short (<2 cm), unbranched protuberances and attached margins and is restricted to the central and southern GBR; and P. pinnaculum sp. nov. has a mountain-like, columnar morphology and occurs on oceanic Coral Sea reefs. A rbcL gene sequence of the isotype of P. castellum demonstrates it is a different species from other columnar species. In addition to the diagnostic rbcL and psbA marker sequences, the four new species may be distinguished by a combination of features including thallus growth form, margin shape (attached or unattached), and medullary system (coaxial or plumose). Porolithon species, because of their ecological importance and sensitivity to ocean acidification, need urgent documentation of their taxonomic diversity.     

Hidden diversity in high-latitude Southern Hemisphere environments: Reinstatement of the genus Rama and description of Vandenhoekia gen. nov. (Cladophoraceae,Ulvophyceae, Chlorophyta), two highly variable genera

The continental coasts and remote islands in the high-latitude Southern Hemisphere, including the subantarctic region, are characterized by many endemic species, high abundance of taxa, and intermediate levels of biodiversity. The macroalgal flora of these locations has received relatively little attention. Filamentous green algae are prolific in the intertidal of southern islands, but the taxonomy, distribution, and evolutionary history of these taxa are yet to be fully explored, mostly due to the difficulty of access to some of these locations. In this study, we examined specimens of the order Cladophorales from various locations in the high-latitude Southern Hemisphere including the subantarctic (the Auckland Islands, Bounty Islands, Campbell Island, Macquarie Island, and Kerguelen Islands), as well as mainland New Zealand, the Chatham Islands, Chile, and Tasmania. The analyses of the rDNA sequences of the samples revealed the existence of two new clades in a phylogeny of the Cladophoraceae. One of these clades is described as the novel genus Vandenhoekia gen. nov., which contains three species that are branched or unbranched. The amended genus Rama is reinstated to accommodate the other clade, and contains four species, including the Northern Hemisphere “Cladophora rupestris.” In Rama both branched and unbranched morphologies are found. It is remarkable that gross morphology is not a predictor for generic affiliations in these algae. This study illustrates that much can still be learned about diversity in the Cladophorales and highlights the importance of new collections, especially in novel locations.     

Mitochondrial genome phylogeny reveals the deep-time origin of Gomphomastacinae (Orthoptera: Eumastacidae) and its alpine genera in China

Gomphomastacinae is a grasshopper subfamily in Eumastacidae, with a morphology and distribution distinct from other subfamilies. The alpine genera of Gomphomastacinae that inhabit the Qinghai–Tibet Plateau in China show unique characteristics adapted to high-altitude life. However, their phylogenetic position and biogeographic history remain controversial. Thus, to determine the diversification history of these alpine genera and the origin of the subfamily, we obtained mitochondrial genome sequences from all seven Gomphomastacinae genera distributed in China. The reconstructed phylogeny was well supported and confirmed the phylogenetic position of Gomphomastacinae within Eumastacidae. Time calibration revealed a deep-time origin of the subfamily dating back to the Cretaceous period, and the diversification among alpine genera was also an ancient pre-Miocene event (30–50 Ma). Based on phylogeny and time estimates, the most likely biogeographic scenario is that Gomphomastacinae originated from an ancestral lineage that lived in East Gondwana and dispersed to Central and Western Asia through India. Subsequently, the alpine genera likely diverged along with the uplift of the Qinghai–Tibet Plateau and survived drastic climate change by in situ adaptation to high-altitude dwellings.     

Systematics of Mukdenia and Oresitrophe (Saxifragaceae): Insights from genome skimming data

Oresitrophe and Mukdenia (Saxifragaceae) are epilithic sister genera used in traditional Chinese medicine. The taxonomy of Mukdenia, especially of M. acanthifolia, has been controversial. To address this, we produced plastid and mitochondrial data using genome skimming for Mukdenia acanthifolia and Mukdenia rossii, including three individuals of each species. We assembled complete plastomes, mitochondrial CDS and nuclear ribosomal ETS/ITS sequences using these data. Comparative analysis shows that the plastomes of Mukdenia and Oresitrophe are relatively conservative in terms of genome size, structure, gene content, RNA editing sites and codon usage. Five plastid regions that represent hotspots of change (trnH-psbA, psbC-trnS, trnM-atpE, petA-psbJ and ccsA-ndhD) are identified within Mukdenia, and six regions (trnH-psbA, petN-psbM, trnM-atpE, rps16-trnQ, ycf1 and ndhF) contain a higher number of species-specific parsimony-informative sites that may serve as potential DNA barcodes for species identification. To infer phylogenetic relationships between Mukdenia and Oresitrophe, we combined our data with published data based on three different datasets. The monophyly of each species (Oresitrophe rupifraga, M. acanthifolia and M. rossii) and the inferred topology ((M. rossii, M. acanthifolia), O. rupifraga) are well supported in trees reconstructed using the complete plastome sequences, but M. acanthifolia and M. rossii did not form a separate clade in the trees based on ETS + ITS data, while the mitochondrial CDS trees are not well-resolved. We found low recovery of genes in the Angiosperms353 target enrichment panel from our unenriched genome skimming data. Hybridization or incomplete lineage sorting may be the cause of discordance between trees reconstructed from organellar and nuclear data. Considering its morphological distinctiveness and our molecular phylogenetic results, we strongly recommend that M. acanthifolia be treated as a distinct species.     

THE FLAGELLAR APPARATUS OF HYMENOMONAS CORONATA (PRYMNESIOPHYTA)1

The ultrastructure of Hymenomonas coronata Mills was reinvestigated to determine the microarchitecture of the flagellar apparatus. Cell morphology and flagellar apparatus structure are very similar to those of Pleurochrysis. Some important variations occur. First, a crystalline root (= compound root) is absent on microtubular root 1. Second, a two-stranded microtubular root emanates at a right angle from microtubular root 2. Third, a fibrous root emanates from the dorsal region between the basal bodies and extends to the cell's right, paralleling microtubular root 3. These similarities and variations in flagellar apparatus characters are discussed in reference to known variations in the Prymnesiophyta.