Deoxyribonucleic acid reassociation in the taxonomy of the genus Chlorella

DNA hybridization techniques showed Chlorella fusca var. vacuolata and C. kessleri to be homogeneous species with DNA homologies of 90–100% C. fusca var. fusca and var. rubescens, however, have only about 15% DNA homology with C. fusca var. vacuolata and should no longer be regarded as varieties. A good correlation was found so far between biochemical and physiological characters used in the taxonomy of Chlorella and DNA relatedness. Mutant strains of Chlorella were tested for DNA homologies to prove the reliability of the taxonomical interpretation.     

Upper limits of temperature for growth inChlorella (Chlorophyceae)

The upper limit of temperature for growth is a species-specific character in the genusChlorella. The limits of 14Chlorella species range from 26–30°C (C. saccharophila) to 38–42°C (C. sorokiniana), withC. fusca var.vacuolata (34°C) andC. kessleri (34–36°C) assuming an intermediate position. Thus, there is no wide gap in the temperature limits between the normal (“low-temperature”) species ofChlorella and the “high-temperature” species,C. sorokiniana.     

Physiological and biochemical contributions to the taxonomy of the genus Chlorella

Starch hydrolysis, i.e., the production of extracellular amylolytic enzymes, was found to be a specific character for most species of the genus Chlorella. C. fusca var. vacuolata, C. spec. 211-30, and C. spec. 211-11r hydrolyse starch, whereas C. vulgaris, C. fusca var. rubescens, C. zofingiensis, C. fusca var. fusca, C. minutissima, C. homosphaera, C. kessleri, C. luteoviridis, and C. protothecoides are unable to hydrolyse starch. Only C. sorokiniana and C. saccharophila appear heterogenous; within C. sorokiniana, 7 strains hydrolyse starch and 9 do not; and within C. saccharophila, 6 strains exhibit amylolytic activity and 2 do not. — A key for the identification, according to 9 easily determined physiological and biochemical characters, of the Chlorella species is presented.     

Species-specific ability ofChlorella strains (Chlorophyceae) to form stable symbioses withHydra viridis

46 strains ofChlorella, identified by physiological and biochemical characters, were examined for their ability to form stable symbioses with aposymbioticHydra viridis. It was found to be a species-specific characteristic. Among the 15 taxa studied, onlyC. saccharophila var.ellipsoidea, C. saccharophila var.saccharophila, C. fusca var.vacuolata, C. kessleri, C. luteoviridis, andC. protothecoides formed stable symbioses withHydra viridis. Among the 11 known physiological and biochemical characters of theseChlorella species, only acid tolerance seems to be correlated with symbiosis: All symbiotic species are capable of growing at or below pH 4.0.     

Notes onConocybe (Bolbitiaceae)

The mycological exploration of the Viennese nature preserve Lobau, resulted in the discovery of several new species ofBasidiomycetes; of special interest is the genusConocybe of which the authors present two new taxa:C. lobauensis andC. leporina var.tetraspora. FurthermoreC. neoantipus, C. striatipes andC. caespitosa are discussed, and the new varietiesC. neoantipus var.tucumana and var.carinthiaca as well asC. striatipes var.sejuncta are proposed.     

Biotransformation of mercury in pH-stat cultures of eukaryotic freshwater algae

Eukaryotic algae were studied to determine their ability to biotransform Hg^II under aerated and pH controlled conditions. All algae converted Hg^II into β-HgS and Hg⁰ to varying degrees. When Hg^II was administered as HgCl₂ to the algae, biotransformation by species of Chlorophyceae (Selenastrum minutum and Chlorella fusca var. fusca) was initiated with β-HgS synthesis (K _1/2 of hours) and concomitant Hg° evolution occurred in the first hour. Hg° synthesis was impeded by the formation of β-HgS and this inhibition was released in C. fusca var. fusca when cellular thiols were oxidized by the addition of dimethylfumarate (DMF). The diatom, Navicula pelliculosa (Bacillariophyceae), converted a substantially greater proportion of the applied Hg^II into Hg⁰, whereas the thermophilic alga, Galdieria sulphuraria (Cyanidiophyceae), rapidly biotransformed as much as 90% of applied Hg^II into β-HgS (K _1/2 ≈ 20 min). This thermophile was also able to generate Hg⁰ even after all exogenously applied HgCl₂ had been biotransformed. The results suggest that β-HgS may be the major dietary mercurial for grazers of contaminated eukaryotic algae.     

Nutlet sculpturing inScutellaria sect.Resinosa (Lamiaceae) and its taxonomic utility

Nutlet sculpturing of 22 taxa ofScutellaria sect.Resinosa, representing 18 of its 19 species, and the monotypic genusSalazaria was studied by scanning electron microscopy (SEM). The nutlets of sect.Resinosa, while remarkably variable among themselves, differed from hypothetically closely related sections in lacking circumferential banding and sessile glands. Species could be grouped by surface sculpturing into seemingly meaningful phenetic clusters.Scutellaria potosina var.platyphylla was sufficiently distinct micromorphically so as to be elevated to specific status asScutellaria platyphylla comb. and stat. nov. The significance of nutlet microcharacters within sect.Resinosa is discussed, especially as compared to closely related sections. The genusSalazaria had nutlet sculpturing quite different from all taxa belonging to sect.Resinosa.     

Sero-systematics ofCytisus sect.Trianthocytisus (Fabaceae)

The serological reaction of seed proteins provides evidence for a partly new systematic arrangement ofCytisus sect.Trianthocytisus and ofCytisus s.l. Proposed modifications agree with recent advances in morphological taxonomy. Sect.Trianthocytisus includes only two species,C. villosus andC. aeolicus. Its position is central within the genus, and this fact agrees with the proposed retypification ofCytisus (type species:C. villosus).C. emeriflorus, formerly included in the same section, constitutes the monospecific sect.Emeroides, which is intermediate towards the genusLembotropis. This is serologically isolated and includes onlyL. nigricans. It is confirmed thatC. sessilifolius should be removed from the genusCytisus as a monospecific genus:Cytisophyllum Lang which is closely allied toHesperolaburnum and toPodocytisus, the most primitive genera ofGenisteae.     

Candida shehatae — Genetic diversity and phylogenetic relationships with other xylose-fermenting yeasts

The xylose-fermenting yeasts Candida shehatae and Pichia stipitis were compared from extent of nuclear DNA complementarity and ribosomal RNA sequence similarity. Low levels of DNA relatedness confirmed that the two taxa are distinct biological species, but the similarity of rRNA sequences suggests that they only recently diverged. C. shehatae is comprised of three genetically divergent (ca. 50% DNA relatedness) subgroups that were accorded varietal status: C. shehatae var. shehatae, var. Lignosa and var. insectosa. Estimates of phylogenetic distance from rRNA sequence similarity show C. shehatae and P. stipitis to be more closely related to Pachysolen tannophilus than to Saccharomyces cerevisiae, and that all of these budding yeasts are well separated from Schizosaccharomyces pombe.     

Responses of four arid zone grass species from varying habitats to drought stress

The effects of 4 or 8 drought cycles on four grass species,Cenchrus pennisetiformis, Leptochloa fusca, Panicum turgidum, andPennisetum divisum were assessed in a pot experiment. There were significant differences between the species in biomass production under water stress.C. pennisetiformis andP. turgidum produced significantly greater fresh and dry matter thanP. divisum and especially thanL. fusca. L. fusca had the lowest andP. divisum highest osmotic potentials compared with the other species after the completion of 4 or 8 drought cycles. Osmotic adjustment (difference between osmotic potential of droughted/rehydrated plants and control plants) was highest inL. fusca. The stomatal conductance was significantly decreased with increased drought stress inC. pennisetiformis. The elasticity ofC. pennisetiformis, P. turgidum andP. divisum increased with increase in number of drought cycles, whereas that ofL. fusca remained unchanged.L. fusca andP. turgidum had the lowest leaf hydration of all species after 8 drought cycles. The chlorophyllsa andb in all species remained unaffected by drought treatments. The proline content ofC. pennisetiformis andL. fusca increased significantly with increased drought stress, whereas that ofP. turgidum remained unaffected after 4 or 8 drought cycles.L. fusca synthesized great amount of leaf soluble proteins during 8 drought cycles, whereasP. divisum had low protein content after 4 drought cycles. The protein contents ofC. pennisetiformis andP. turgidum remained unaffected after 8 drought cycles. The leaf epicuticular wax ofL. fusca increased consistently with increased drought stress, but leaf wax ofP. divisum increased only at the highest drought stress and that ofC. pennisetiformis andP. turgidum increased after 4 drought cycles. On the basis of these results it was established thatC. pennisetiformis andP. turgidum were the most tolerant,P. divisum intermediate, andL. fusca the most sensitive to drought stress. The osmotic adjustment did not positively correlate with the degree of drought resistance.     

Chloroplast DNA restriction site mapping and the phylogeny ofRanunculus (Ranunculaceae)

A chloroplast DNA restriction site map forRanunculus sceleratus (Ranunculaceae) was constructed using 14 restriction endonucleases. The total size of the chloroplast genome is 152.4kb. No inversions were detected relative to the tobacco chloroplast DNA. Cladistic analyses of chloroplast DNA restriction site polymorphism were employed in order to elucidate the phylogeny among 76 species of the genusRanunculus in a wide sense and one species ofTrautvetteria. A total of 341 informative restriction site changes were detected. Parsimony jackknifing, bootstrapping and decay analysis were undertaken in order to evaluate the amount of support for the monophyletic groups. The results suggest that the analysed species ofRanunculus are divisible into two main clades. Only few of the traditional sections and subgenera ofRanunculus are monophyletic. The genusTrautvetteria is nested within a clade comprising, e.g.Ranunculus cymbalaria, R. andersonii, R. lapponicus andR. ficaria. SubgenusBatrachium lies within a larger clade containing, e.g.R. sceleratus andR. hyperboreus. Contractions of the inverted repeat due to parallel deletions of 200–300 bp close to the J_SB have occurred in many clades and the phylogenetic distribution of this size reduction was mapped among the species.     

Novelties in spermacoceae (Rubiaceae) from Bolivia and Paraguay

One new Bolivian species (Borreria pazensis) and three new varieties (Borreria densiflora var.minima, Richardia, scabra var.chacoensis andStaelia virgata var.killeenii) are described and illustrated. The genusDiodella, with three species (D. apiculata comb. nov., D. radula comb. nov., andD. teres), is reported for the first time.Borreria limae, B. wunschmannii, B. scabiosoides var.scabiosoides, andB. scabiosoides var.anderssonii are also reported as new to Bolivia.     

Duration of diapause in the stem borers, Busseola fusca and Chilo partellus

The duration of diapause in the stem borers Busseola fusca (Fuller) and Chilo partellus (Swinhoe) was studied in South Africa by collecting diapausing larvae from the field throughout winter (April–August). B. fusca larvae emerged as moth around the middle of October regardless of the date of collection and the length of time they were kept in the laboratory under constant 21 °C. C. partellus larvae collected in April–June emerged in November, those collected in July emerged in October, and those collected in August emerged in September. Regardless of the collection date C. partellus started to emerge from diapause earlier and moth emergence lasted up to twice as long as in B. fusca. Under laboratory conditions at 60% RH both borer larvae lost about 50% of their body mass during diapause. When provided with water B. fusca larvae lost about 30% of their body mass and adults emerged 20 days earlier than when kept dry. C. partellus, on the other hand, lost only 13% of their body weight and emerged 34 days earlier. The differences between the two species are discussed in light of different types of diapause; i.e., obligatory diapause in B. fusca and facultative diapause in C. partellus.     

Chloroplast DNA restriction site variation in theVernonieae (Asteraceae), an initial appraisal of the relationship of New and Old World taxa and the monophyly ofVernonia

Chloroplast DNA restriction site variation was examined for 35 taxa in theVernonieae and four outgroup tribes, using 17 restriction enzymes mapped for ca. 900 restriction sites per species; 139 mutations were found to be phylogenetically informative. Phylogenetic trees were constructed using Wagner and weighted parsimony, and evaluated by bootstrap and decay analyses. Relationships of Old and New World taxa indicate complex geographical relationships; there was no clear geographic separation by hemisphere. The relationships between Old and New World Vernonias found here support prior morphological analyses. The sister group to all New and most Old World taxa was composed of a small group of Old World species including yellow-flowered, trinervate-leaved species previously postulated to be basal in the tribe. The majority of both New and Old World taxa are derived from a lineage beginning with the monotypic genusStokesia, an endemic of the southeastern United States. The genusVernonia was also found to be paraphyletic within both the New and Old World. Available data do not support either the separation ofVernonia or the tribeVernonieae into geographically distinct lineages. The pattern of relationships within theVernonieae for taxa from North America, Asia, Africa, Central and South America is most similar to that of several other groups of both plants and animals with a boreotropical origin, rather than an origin in Gondwanaland. Such a pattern of distribution suggests more ancient vicariant events than are routinely postulated for theAsteraceae.     

A new species of Laboulbeniales (Ascomycetes) onDiplocheila (Coleoptera, Carabidae) from Japan

A new species of the genusLaboulbenia, L. diplocheilae, has been established for specimens on the host genusDiplocheila (Coleoptera, Carabidae, Licinini).Laboulbenia diplocheilae is easily distinguished fromL. proliferans var.divaricata onChlaenius by the absence of a black constriction on the outermost branch of the outer appendage and by the simple stalks subtending grouped antheridia borne on appendage branches in the middle of the appendage system.     

大叶九里香,芸香科新等级组合及生物学特征补述

为理清芸香科(Rutaceae)九里香属(Murraya)中大叶九里香[M. kwangsiensis (C. C. Huang)C. C. Huang var. macrophylla C. C. Huang]与其原变种广西九里香[M. kwangsiensis(C. C. Huang)C. C. Huang var. kwangsiensis]间的系统关系及其分类学地位,采用综合文献查阅、标本鉴定、野外实地调查、栽培观察及显微解剖等多种方法对九里香属植物数个种类进行分类学相关研究。结果发现:大叶九里香在叶片、花、果实等形态特征方面与广西九里香间的差异极大,故将其处理为一个独立的种,并提出新等级组合Murraya macrophylla (C. C. Huang)F. J. Mou; 首次对大叶九里香的形态特征及分布进行详尽描述; 该物种的羽状复叶及小叶均为九里香属中最大者,更接近仅分布于越南的光叶九里香[M. glabra (Guillaumin)Swingle],但其较大的小叶、叶面叶脉下凹且叶片皱缩等特征使其明显不同于九里香属其他种类。大叶九里香是一个独立种而非广西九里香的变种,此关于大叶九里香分类地位的新观点有助于整个九里香属的系统发育关系重建及种间系统关系的深入探索。     

Pollination of sevenPlectranthus spp. (Lamiaceae) in southern Natal, South Africa

The genusPlectranthus (Lamiaceae) shows remarkable radiation on the sandstones of southern Natal and northern Transkei in South Africa, where six endemic species occur. Two of these endemic species,P. hilliardiae andP. oribiensis, are included in this study, as well asP. reflexus, for which only limited data are available. The other species that were studied areP. ambiguus, P. ciliatus, P. ecklonii, P. madagascariensis andP. zuluensis. Four of these taxa,P. ambiguus, P. hilliardiae, P. reflexus andP. saccatus var.longitubus, have uniquely long corolla-tubes (20–30mm) and this is related to pollination by nemestrinid flies of the genusStenobasipteron that have proboscides of similar length. Other nemestrinid species of the genusProsoeca have shorter proboscides and pollinate two species ofPlectranthus with shorter corolla-tube lengths (6–15mm). Acrocerid flies, tabanid flies and anthophorid bees are also important visitors to these species. This study on the pollination of seven species of varying corolla-tube lengths shows a correlation between floral tube length and proboscis length of insect visitors, many of which are recorded for the first time as pollinators ofPlectranthus.     

Correlations between 2C DNA values and habit inCassia (Leguminosae:Caesalpinioideae)

Ten species of the genusCassia show a range of 2C DNA amounts from 1.30 to 2.54 pg at the same ploidy level. Remarkably, a distinct 2-fold increase is depicted by an arboreal speciesC. excelsa while the rest comprising of herbs, trees and shrubs have a range from 1.30 to 1.47 pg. These form a natural grouping with respect to mean DNA amounts which differ by 0.05 pg in the herbs, trees and shrubs respectively.     

Ribosomal DNA distribution in somatic chromosomes of Stangeria eriopus (Stangeriaceae, Cycadales) and molecular-cytotaxonomic relationships to some other cycad genera

Somatic chromosomes ofStangeria eriopus (Stangeriaceae, Cycadales) were investigated by fluorescentin situ hybridization (FISH) using an 18S ribosomal DNA (rDNA) probe.Stangeria eriopus showed a chromosome number of 2n=16 with a karyotype of 12 median-, 2 subterminal-, and 2 terminal-centromeric chromosomes. FISH study ofS. eriopus revealed 16 signals made up of rDNA sites located on the terminal regions of the long arms of the 7 median- and 2 subterminal-centromeric chromosomes, on terminal region of the short arm of the 1 median-centromeric chromosome, on the terminal regions of the long and the short arms of 1 median- and 2 terminal-centromeric chromosomes. This result suggests that, not only karyomorphologically but also molecular-cytologically, the genusStangeria may be more closely related to the genusCeratozamia than the genusBowenia or the genusMicrocycas previously hypothesized.     

Physiological,Biochemical, and Molecular Characters for the Taxonomy of the Subgenera of Scenedesmus (Chlorococcales,Chlorophyta)

Biochemical and physiological properties of 16 Scenedesmus species representing the three subgenera Scenedesmus, Acutodesmus, and Desmodesmus are not suitable for species differentiation. All Scenedesmus species studied thus far produce secondary carotenoids, e.g. astaxanthin and canthaxanthin, under nitrogen-deficient conditions. In addition, with the exception of one strain, hydrogenase activity under anaerobic conditions is generally present. Sequence analyses of ribosomal 18S RNAs indicate that the subgenus Desmodesmus is phylogenetically well separated from the other subgenera, whereas the separation of Scenedesmus and Acutodesmus appears less convincing and is dismissed in favour of a single subgenus, Scenedesmus. Three taxa formerly assigned to the genus Chlorella are shown to be unicellular species of the genus Scenedesmus. “Chlorella” fusca var. vacuolata and “C.” fusca var. rubescens, which is closely related to S. obliquus, belong to the Scenedesmus/‘Acutodesmus group. “C.” fusca var. fusca is closely related to S. communis and thus belongs to the subgenus Desmodesmus. Inclusion of Kermatia pupukensis into the genus Scenedesmus is also strongly supported by the RNA data which furthermore indicate a relationship with the subgenus Desmodesmus.