CORRESPONDENCE BETWEEN PHYLOGENY AND MORPHOLOGY OF SNOWELLA SPP. AND WORONICHINIA NAEGELIANA,CYANOBACTERIA COMMONLY OCCURRING IN LAKES1

In this study, the first reported isolates of the genera Snowella and Woronichinia were characterized by 16S rRNA gene sequencing and morphological analysis. Phylogenetic studies and sequences for these genera were not available previously. By botanical criteria, the five isolated strains were identified as Snowella litoralis (Häyrén) Komárek et Hindák Snowella rosea (Snow) Elenkin and Woronichinia naegeliana (Unger) Elenkin. This study underlines the identification of freshly isolated cultures, since the Snowella strains lost the colony structure and were not identifiable after extended laboratory cultivation. In the 16S rRNA gene analysis, the Snowella strains formed a monophyletic cluster, which was most closely related to the Woronichinia strain. Thus, our results show that the morphology of the genera Snowella and Woronichinia was in congruence with their phylogeny, and their phylogeny seems to support the traditional botanical classification of these genera. Furthermore, the genera Snowella and Woronichinia occurred commonly and might occasionally be the most abundant cyanobacterial taxa in mainly oligotrophic and mesotrophic Finnish lakes. Woronichinia occurred frequently and also formed blooms in eutrophic Czech reservoirs.     

Reaction mechanism of surfactant‐sensitized chemiluminescence of bis(2,4,6‐trichlorophyenyl) oxalate and hydrogen peroxide induced by gold nanoparticles

The chemiluminescence (CL) of bis(2,4,6‐trichlorophyenyl) oxalate with hydrogen peroxide in the present of cationic surfactant and gold nanoparticles was studied. The CL emission was obviously enhanced in the presence of surfactant at a suitable concentration, with a synergetic catalysis effect exhibited. Different sizes of gold nanoparticles (15 and 50 nm) showed different effects on CL intensity. Mechanisms of the CL reaction and sensitization effect are discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

Pre‐copulation intervals,copulation frequencies,and initial progeny sex ratios in two biotypes of whitefly,Bemisia tabaci

The whitefly Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) is a species complex, and its systematic classification requires controlled crossing experiments among its genetic groups. Accurate information on pre‐copulation intervals, copulation frequencies, and initial frequency of egg fertilization of newly emerged adults is critical for designing procedures for collecting the virgin adults necessary for these experiments. In the literature, considerable variation is reported between B. tabaci populations, with respect to the length of the pre‐copulation interval and the initial frequency of egg fertilization. Here, we used a video‐recording method to observe continuously the copulation behaviour of the Mediterranean/Asia Minor/Africa (B biotype) and the Asia II (ZHJ1 biotype) groups of B. tabaci. We also recorded the initial frequency of egg fertilization, as determined by the sex of the progeny. When adults were caged in female–male pairs on leaves of cotton plants, the earliest copulation events occurred 2–6 h after emergence; at 12 h after emergence 56–84% of the females had copulated at least once, and nearly all (92–100%) had copulated at least once by 36 h after emergence. Both females and males copulated repeatedly. Approximately 80 and 20% of copulation events occurred during the photophase and scotophase, respectively. By 72 h post‐emergence, the females of the B and ZHJ1 biotypes had copulated on average 6.1 and 3.9 times, respectively. When adults were caged in groups on plants 1–13 h after emergence, 30–35% of the eggs deposited during this period were fertilized, and approximately 90% of females were fertilized by the end of the 13 h. Although timing of copulation differed in detail between the two genetic groups, the results demonstrate that B. tabaci adults can start to copulate as early as 2–6 h post‐emergence and the majority of females can become fertilized on the day that they emerge.     

Cell and molecular biology of bryophytes: ultimate limits to the resolution of phylogenetic problems

Ultrastructure, biochemistry and 5S rRNA sequences link tracheophytes, bryophytes and charalean green algae, but the precise interrelationships between these groups remain unclear. Further major clarification now awaits primary sequence data. These are also needed to determine directionality in possible evolutionary trends within the bryophytes, but are unlikely to overturn current schemes of classification or phylogeny. Comparative ultrastructural studies of spermatogenesis, sporogenesis, the cytoskeleton and plastids reinforce biochemical and morphogenetic evidence for the wide phyletic discontinuities between mosses, hepatics and hornworts, and also rule out direct lines of descent between them. Direct ancestral lineages from charalean algae to bryophytes and to tracheophytes are also unlikely. EM studies of gametophyte/sporophyte junctions, plus immunological investigations of bryophyte cytoskeletons, are likely to accentuate the differences between mosses, hepatirs and hornworts. Other priorities for systematics include elucidation of oil body ultrastructure, analysis of the changes in nuclear proteins during spermatogenesis and a detailed comparison of bryophyte and charalean plastids. The combined evidence from ultrastrueture, biochemistry, morphology and morphogenesis warrants general acceptance of the polyphyletic origin of the bryophytes. Ultrastructural attributes should be more widely used in bryophyte systematics.     

Euplotes Cytoskeleton: Tubulin and Microtubular Systems in Interphase1,2

The Euplotes cytoskeleton obtained by treatment with Triton X-100 in a microtubule-stabilizing buffer has been studied by electron microscopy and SDS-polyacrylamide electrophoresis. An antiserum has been prepared using the tubulin band from preparative gels of Euplotes cytoskeletons as an antigen. This antiserum reacts with the tubulin from different ciliated protozoa but fails to recognize the vertebrate tubulin by immunoblotting. Immunoblotting studies have demonstrated a slower electrophoretic mobility for the α-tubulin of Euplotes and Oxytricha than that of Paramecium and Tetrahymena. A cytoplasmic microtubular network in Euplotes has been revealed by indirect immunoftuorescence using both an anti-α-tubulin monoclonal antibody directed against chick brain tubulin and an antiserum raised against the tubulin of Euplotes.     

Changes in soil microflora associated with control of Sclerotium Rolfsii by Furfuraldehyde

The efficacy of 2‐furfuraldehyde for control of Sclerotium rolfsii was studied in laboratory and greenhouse experiments. Mycelial growth of the fungus was reduced proportionally with concentrations of 0.1–0.5 ml furfuraldehyde l^‐1 agar medium, and viability of sclerotia diminished on exposure to 2‐furfuraldehyde vapours. Detectable populations of bacteria and fungi, including Trichoderma spp., were reduced significantly (9=0.05) when furfuraldehyde was added to the agar used for soil dilution plates of untreated soil. Repeated treatments of natural soil with the fumigant significantly increased populations of Trichoderma spp. and bacteria, but diminished numbers of actinomycetes. Increasing dosages applied to soil artificially infested with S. rolfsii caused a reduction of disease on lentil, Lens culinaris. Results indicate that the compound, when applied to field soil, changes the composition of soil microflora and has potential for integrated control of S. rolfsii.