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.     

Acid-mediated mutagenicity of tobacco snuff: its possible mechanism

Polar solvent extracts of tobacco snuff under acidic conditions were mutagenic in Salmonella typhimurium. Using the Griess reagent test, nitrite ranging from approximately 1.8 to 5.4 mg/g of snuff was found in the polar fraction of extracts. After acid treatment, nitroso compounds in the amount corresponding to the nitrite concentration were detected. The mutagenic potency of the acid-treated extracts was consistent with the content of nitroso compounds generated. Formation of nitroso compounds and the mutagenic activity under acidic conditions was inhibited by ascorbic acid. The results indicate that a nitrosation process was involved in snuff extracts during acid treatment. Studies related to the source of nitrite in tobacco snuff demonstrated that snuff contained bacteria which were able to reduce nitrate to nitrite and that the amount of nitrite in snuff extracts could be further increased by incubation of the extracts with the bacteria. Since snuff contains a considerable amount of nitrate, it seems that reduction of nitrate in snuff to nitrite by bacteria, and nitrosation of certain constituents in snuff by nitrite under acidic conditions to form mutagenic nitroso compounds are possible mechanisms responsible for the acid-mediated mutagenicity of snuff extracts.     

Immunocytochemical studies on prolactin cells in the adenohypophysis of the golden hamster

Mammotrophs or prolactin (PRL) cells were identified in the adenohypophysis of adult golden hamsters by immunocytochemical techniques with a polyclonal anti-PRL, that was proved to be specific to PRL by the dot immunoblotting test. Postembedding immunostaining was performed on Araldite thin sections by immunoperoxidase and immunogold methods. PRL cells were classified into three types according to the different size of the secretory granules. The Type A cells were usually small and angular or oval in shape, and had secretory granules ranging in diameter from 100-230 nm, and showed poorly developed organelles. The Type B and C cells were larger and round or ovoid in shape, contained larger granules, 230-280 nm and 280-570 nm, respectively, and displayed well developed organelles. Immunoreactive PRL cells in the male pituitaries were far less numerous than in the nonpregnant female glands, and were mostly of the Type A and B, whereas in the female the Type C and B cells predominated. In pregnant females, Type C cells became activated and increased in number, while the other two types decreased in proportion. In lactating females, Type A and B cells significantly increased in number at the expense of the Type C cells; meanwhile, the exocytosis of secretory granules was frequently found in all types of PRL cells. The present findings suggest that Type C and B PRL cells, especially the former, are potent in producing and releasing PRL and highly responsive to various physiological stimuli, while Type A cells are probably relatively inert in synthetic activity.     

Characterization of the Erwinia carotovora pelB gene and its product pectate lyase.

The pelB gene encodes pectate lyase B, one of three pectate lyases identified in Erwinia carotovora EC. Pectate lyase B was purified from Escherichia coli containing the pelB gene on a recombinant plasmid. The activity of the protein was optimal at a pH of 8.3. The amino acid composition, N-terminal amino acid sequence, and C-terminal peptide sequence were determined and compared with the polypeptide sequence deduced from the DNA sequence of pelB. Purified pectate lyase B started at amino acid 23 of the predicted sequence, suggesting that a 22-amino-acid leader peptide had been removed. Pectate lyase B of E. carotovora EC and pectate lyase B of E. chrysanthemi EC16 contain 352 and 353 amino acids, respectively (N. T. Keen, S. Tanaki, W. Belser, D. Dahlbeck, and B. Staskawicz, J. Bacteriol. 168:595-606, 1986). The two proteins are 72% homologous on the basis of DNA sequence data, and 75% of the amino acids are identical.     

Cross-linking study of the quaternary fine structure of mitochondrial F1-ATPase

A method has been developed for exploring the quaternary fine structure of oligomeric proteins by crosslinking studies and applied to bovine heart mitochondrial F1-ATPase. The F1 was first labeled with 1-fluoro-2,4-dinitro-[14C]benzene, subsequently reduced with sodium hydrosulfite, and finally cross-linked with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide. Gel electrophoresis in the chemically modified protein in the presence of sodium dodecyl sulfate and mercaptoethanol showed the existence of a 105-115-kilodalton molecular species in addition to the five monomeric subunits of F1. This cross-linked species could be alpha 2, alpha beta, or beta 2. Isolation of the cross-linked species and titration with 5,5'-dithiobis-(2-nitrobenzoic acid) showed the absence of sulfhydryl group. Therefore, the cross-linked species must be the dimer beta 2. After digestion of the purified beta 2 with pepsin, a single radioactive peptide was isolated. Determination of the amino acid sequence of this peptide and comparison of its radioactivity with the total radioactivity on beta-subunits show that it was formed exclusively by cross-linking Lys162 of one beta-subunit with Glu199 of another beta-subunit. The observation that two beta-subunits can be cross-linked by a rigid phenylenediamine bridge of 5.7- or 4.3-A length is difficult to reconcile with the widely assumed structure of F1 with the alpha- and beta-subunits occupying alternate corners of a planar hexagon, but is consistent with the structure in which a triangular set of three beta-subunits sits above a triangular set of three alpha-subunits in a staggered conformation.