Expended range of Gomphonema firmum (Bacillariophyceae), once considered a Lake Baikal endemic, with notes on the identity of G. lanceolatum var. maximum

This note describes a new record of Gomphonema firmum Skvortzow, which expanded both morphological and distributional ranges of the species. This conspicuous diatom was previously unknown outside of Lake Baikal, where it inhabits deep-water areas. The newly discovered locality belongs to a small stream at a distance of 180 km west from Lake Baikal, where the species was found in a relatively high abundance that enabled to trace a size diminution series including specimens shorter than previously described. In addition, G. lanceolatum var. maximum Poretzky, a name for a diatom from Lake Teletskoe, was included in a synonymy of G. firmum that further expanded the species distribution. In the light of the presented data, the species appears to be a rare diatom with current distribution limited to a few scattered localities in southern Siberia.

Potent antibacterial action of phycosynthesized selenium nanoparticles using Spirulina platensis extract

Selenium nanoparticles (SeNPs) are reinforced safe forms of the essential micronutrient selenium (Se) which take a lead in countless biotechnological and biomedical applications. The phycosynthesis of SeNPs was successfully investigated using cell-free extract of the microalgae, Spirulina platensis. The phycosynthesized S. platensis-SeNPs (SpSeNPs) were characterized using several characterization techniques such as UV-Visible, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and energy dispersive X-ray. They were effectually achieved using different concentration from sodium selenite (Na2SeO3) (1, 5, and 10 mM) to give size means of 12.64, 8.61, and 5.93 nm, respectively, with spherical shapes and highly negative zeta potentialities. The infrared analyses revealed the involvement of many phycochemials in SpSeNPs production. The antibacterial properties of SpSeNPs were confirmed, qualitatively and quantitatively, against foodborne microorganisms (Staphylococcus aureus and Salmonella typhimurium); the antibacterial activity was correlated and increased with SeNPs’ size diminution. The scanning micrographs of S. typhimurium cells treated with SpSeNPs indicated the severe action of nanoparticles to destroy bacterial cells in time-dependent manners. The innovative facile phycosynthesis of SeNPs using S. platensis is recommended to generate effectual bioactive agents to control hazardous bacterial species.

The pollen metamorphosis phenomenon in Panax ginseng, Aralia elata and Oplopanax elatus; an addition to discussion concerning the Panax affinity in Araliaceae

SummaryTo find more morphological characteristics useful for discussion on aralian or non-aralian Panax affinity, pollen morphological diversity was comparatively analysed in P. ginseng, Aralia elata and Oplopanax elatus collected during their pollination periods. In the anthers of both the buds and open flowers, the pollen average diameter varied between some species-specific maximum and minimal measurement. However, the larger pollen grains were typically found in the buds whereas the smaller pollen prevailed in the open flowers, testifying to the pollen size diminution during anther maturation. Based on this finding, the subsequent examination of pollen according to size decrease was put into operation as a method of pollen modification for the study. The structural mechanisms of pollen metamorphosis were identified as not being species specific but rather universal. These mechanisms are suggested to be the shrinkage of the pollen vegetative cytoplasm, the intine enlargement, the deepening of three colporate apertures provided by exine sunken into enlarged intine areas, the aperture accretion as well as the transformation of the exine from thick/sculptured into thin/less sculptured. During ‘size-reducing metamorphosis’, the pollen grains changed dramatically, going through a species-specific set of intermediate morphs to the final species-specific morphotype. In P. ginseng this morphotype is round (diameter is about 16 μm), in A. elata it is round with a single projection (diameter is about 15 μm) and in O. elatus it is ovoid with a single projection (average diameter is about 18 μm). In addition, every species is peculiar in having the unique vegetative cytoplasm inclusions and individual construction of the largest pollen exine. From a phylogenetic perspective, these findings presumably add support to the option of equal remoteness of P. ginseng from A. elata and O. elatus. The characteristics found seem to be suitable for examination of Panax affinity, by the subsequent study of more Araliaceae representatives.

Influence of grinding on graphite crystallinity from experimental and natural data: implications for graphite thermometry and sample preparation

This paper examines the effects of shear stress on the structural parameters that define the ‘crystallinity’ of graphite. The results show that highly crystalline graphite samples ground for up to 120 min do not undergo detectable changes in the three-dimensional arrangement of carbon layers but crystallite sizes (Lc and La) decrease consistently with increasing grinding time. Grinding also involves particle-size diminution that results in lower temperatures for the beginning of combustion and exothermic maxima in the differential thermal analysis curves. These changes in the structural and thermal characteristics of graphite upon grinding must be taken into account when such data are used for geothermometric estimations.Tectonic shear stress also induces reduction of the particle size and the Lc and La values of highly crystalline graphite. Thus, the temperature of formation of graphite according to structural as well as thermal data is underestimated by up to 100°C in samples that underwent the most intense shear stress. Therefore, application of graphite geothermometry to fluid-deposited veins where graphite is the only mineral found should take into consideration the effect of tectonic shearing, or the estimated temperatures must be considered as minimum temperatures of formation only.

COMPARISON OF 13C CPMAS NMR AND CHEMICAL TECHNIQUES FOR MEASURING THE DEGREE OF DECOMPOSITION IN VIRGIN AND CULTIVATED PEAT PROFILES

Solid-state 13C CPMAS NMR was used to examine organic soils from virgin, 5-yr and 15-yr cultivated sites. In agreement with previous studies using other techniques, the chemical effects of cultivation were essentially confined to the plough layer. Cultivated sites had less carbohydrate, and increased lipid and methoxyl carbon; these changes were similar to those found with depth, due to natural decomposition. Changes in aromatic and phenolic carbon with depth or years of cultivation were small. When the NMR data were compared with other indicators of decomposition, there were no correlations between the pyrophosphate index and NMR parameters. Rubbed fiber correlated positively with carbohydrate, and negatively with lipid. This study supports the use of rubbed fiber as a routine indicator of the degree of decomposition, and the use of 13C CPMAS NMR for elucidating chemical changes in organic soils. It also illustrates the need to separate more clearly chemical changes occurring during decomposition or cultivation, from purely physical changes due to drying, compaction, and particle size diminution. Key words: 13C NMR, degree of composition, peat profile, organic soils

Bromocriptine therapy as pre-operative adjunct of non-functional pituitary macroadenomas

Although bromocriptine administration produces reduction in size of prolactinomas, its effect upon non-functional pituitary adenomas is still uncertain. Nine patients with macroadenomas, 2 of them with prolactinomas and 7 with non-functional tumours, received bromocriptine prior to transsphenoidal surgery. Size reduction of tumour mass was assessed by computerized tomography and by visual field examination before and following bromocriptine treatment. There were no signs of size diminution or pathological changes in the nonfunctional adenomas treated pharmacologically during 15 to 360 days. Both patients with prolactinomas had radiological evidence of size reduction and morphological changes on microscopic examination. These 2 patients had tumours with prolactin granules (immunocytochemistry) and adenoma cells showed reduced cytoplasmatic, nuclear and nucleolar areas. Neither vascular damage, cell necrosis, nor infarction was observed by electron microscopy. Patients with non-functional tumours as determined by immunocytochemistry and hormone production did not benefit from bromocriptine. The suggestion that bromocriptine can be used as primary treatment for non-functional pituitary tumours is not supported by the present study. Conversely, in cases of macroprolactinoma, bromocriptine is a useful pre-operative adjunct when surgery is planned and for those patients in whom a surgical cure is considered difficult owing to the tumour size.