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.     

Capitalizing on multi-element interactions through balanced nutrition — A pathway to improve nitrogen use efficiency in China,India and North America

A viable option for increasing nitrogen (N) use efficiency and mitigation of negative impacts of N on the environment is to capitalize on multi-element interactions through implementation of nutrient management programs that provide balanced nutrition. Numerous studies have demonstrated the immediate efficacy of this approach in the developing regions like China and India as well as developed countries in North America. Based on 241 site-years of experiments in these countries, the first-year N recovery efficiency (RE) for the conventional or check treatments averaged 21% while the balanced treatments averaged 54% RE, for an average increase of 33% in RE due to balanced nutrition. Effective policies to promote adoption are most likely those that enable site-specific approaches to nutrient management decisions rather than sweeping, nation-wide incentives supporting one nutrient over another. Local farmers, advisers and officials need to be empowered with tools and information to help them define necessary changes in practices to create more balanced nutrient management.

     

ULTRASTRUCTURE AND ECOLOGY OF AUREOCOCCUS ANOPHAGEFERENS GEN. ET SP. NOV. (CHRYSOPHYCEAE): THE DOMINANT PICOPLANKTER DURING A BLOOM IN NARRAGANSETT BAY,RHODE ISLAND,SUMMER 19851

Observations of a marked cessation of feeding in filter feeding animals maintained in flowing Narragansett Bay seawater in June 1985 drew our attention to a bloom of a golden alga 2 μm in diameter at unprecedented populations of 10⁹ cells. L^?1. This picoplankter lacked morphological features useful in discriminating it from other similar sized forms with either phase contrast or epifluorescence light microscopy. Natural populations of picoplankton, obtained from the height of the bloom until its decline, were examined in thin section with transmission electron microscopy. A cell with a single chloroplast, nucleus, and mitochondrion and an unusual exocellular polysaccharide-like layer was apparently the bloom alga. The ultrastructure of this alga is consistent with that of the Chrysophyceae, and a new genus and species, Aureococcus anophagefferens is described. Attempts to grow this previously unrecognized picoplanktonic alga as an obligate phototroph failed and only yielded cultures of other previously described picoalgae. Facultative and obligate phagotrophic protists with ingested cells of Aureococcus were only observed as the bloom waned and minute diatoms became common. Cells of A. anophagefferens with virus particles typical for picoalgae occurred throughout the bloom. Populations of the usually dominant photosynthetic picoplankter, the cyanobacterium Synechococcus Nägeli, were depressed during the bloom. This could be due in part to selective grazing on Synechococcus rather than Aureococcus by elevated populations of Calycomonas ovalis Wulff which accompanied the algal bloom.     

SECRETORY VESICLE FORMATION IN GLANDULAR TRICHOMES OF CANNABIS SATIVA (CANNABACEAE)

Formation of secretory vesicles in the noncellular secretory cavity of glandular trichomes of Cannabis saliva L. was examined by transmission electron microscopy. Two patterns of vesicle formation occurred during gland morphogenesis. 1) During initial phases of cavity formation small hyaline areas arose in the wall near the plasma membrane of the disc cell. Hyaline areas of elongated shape and different sizes were distributed throughout the wall and adjacent to the secretory cavity. Hyaline areas increased in size, some possibly fusing with others. These hyaline areas, possessing a membrane, moved into the cavity where they formed vesicles. As membraned vesicles they developed a more or less round shape and their contents became electron-dense. 2) During development of the secretory cavity and when abundant secretions were present in the disc cells, these secretions passed through the wall to accumulate as membraned vesicles of different sizes in the cavity. As secretions emerged from the wall, a membrane of wall origin delimited the secretory material from cavity contents. Vesicles released from the wall migrated in the secretory cavity and contacted the sheath where their contents permeated into the subcuticular wall as large or diffused quantities of secretions. In the subcuticular wall these secretions migrated to the wall–cuticle interface where they contributed to structural thickening of the cuticle. This study demonstrates that the secretory process in glands of Cannabis involves not only secretion of materials from the disc cell, but that the disc cell somehow packages these secretions into membraned vesicles outside the cell wall prior to deposition into the secretory cavity for subsequent structural development of the sheath.     

EFFECTS OF SILICON DEFICIENCY ON LIPID COMPOSITION AND METABOLISM IN THE DIATOM CYCLOTELLA CRYPTICA1

The effects of silicon deficiency on the metabolism and composition of lipids in Cyclotella cryptica T13L Reimann, Lewin, and Guillard were examined. Silicon-deficient cells had higher levels of neutral lipids (primarily triacylglycerols) and higher proportions of saturated and monounsaturated fatty acids than silicon-replete cells. After 4 h of silicon deficiency, the percentage of newly assimilated NaH¹⁴CO₃ partitioned into lipids increased from 27.6% to 54.1%, whereas the percentage partitioned into chrysolaminarin decreased from 21.6% to 10.6%. In addition, pulse-chase experiments with NaH¹⁴CO₃ indicated that the amount of ¹⁴C in the total cellular lipid fraction increased by 32% after 12 h of silicon deficiency despite the absence of additional photoassimilable ¹⁴C. Therefore, the accumulation of lipids in response to silicon deficiency appears to be due to two distinct processes: (a) an increase in the proportion of newly assimilated carbon partioned into lipids, and (2) a slow conversion of previously assimilated carbon from non-lipid compounds into lipids