Contribution to the knowledge of the species composition of summer phytoplankton of Lake Hubsugul,Mongolia

The summer phytoplankton of ultraoligotrophic Lake Hubsugul, Mongolia, was studied in 1985–1989. 24 taxa, mostly belonging to the chlorococcal algae, are illustrated and their main diagnostic features discussed. Two new combinations,Monoraphidium pseudomirabile (Kor?.) Hind. etZagor., andOocystella mongolia (Antip.) Hind. etZagor, are created.     

Diversity of cyanobacteria and algae of urban gravel pit lakes in Bratislava,Slovakia: a survey

Hydrobiologia - This paper presents data on the diversity of cyanobacteria and algae of nine gravel pit lakes situated within the city boundaries of Bratislava, W Slovakia. During more than 30...     

Zygospore formation between homothallic and heterothallic strains of Closterium

Zygospore formation in different strains of the Closterium peracerosum-strigosum-littorale complex was examined in this unicellular isogamous charophycean alga to shed light on gametic mating strains in this taxon, which is believed to share a close phylogenetic relationship with land plants. Zygospores typically form as a result of conjugation between mating-type plus (mt⁺) and mating-type minus (mt⁻) cells during sexual reproduction in the heterothallic strain, similar to Chlamydomonas. However, within clonal cells, zygospores are formed within homothallic strains, and the majority of these zygospores originate as a result of conjugation of two recently divided sister gametangial cells derived from one vegetative cell. In this study, we analyzed conjugation of homothallic cells in the presence of phylogenetically closely related heterothallic cells to characterize the reproductive function of homothallic sister gametangial cells. The relative ratio of non-sister zygospores to sister zygospores increased in the presence of heterothallic mt⁺ cells, compared with that in the homothallic strain alone and in a coculture with mt⁻ cells. Heterothallic cells were surface labeled with calcofluor white, permitting fusions with homothallic cells to be identified and confirming the formation of hybrid zygospores between the homothallic cells and heterothallic mt⁺ cells. These results show that at least some of the homothallic gametangial cells possess heterothallic mt⁻-like characters. This finding supports speculation that division of one vegetative cell into two sister gametangial cells is a segregative process capable of producing complementary mating types.     

Planktic coccal and trichal green algae of Lake Volvi,Greece

In the course of three years' investigations (1983–1986) of Lake Volvi, N Greece, 62 species and varieties of chlorococcal algae and 6 species of ulotrichal algae (Chlorophyceae) were found. Although chlorophytes form the largest group of the phytoplankton assemblages of the lake, their biomass is relatively small or even negligeable in some periods of the year in comparison with domination cyanophytes, diatoms and cryptophytes. Morphological variation of diagnostic features is described and documented by original drawings in 53 taxa.     

Blocking neddylation elicits antiviral effect against hepatitis B virus replication

Molecular Biology Reports - Hepatitis B Virus (HBV) is the most common cause of chronic liver disease worldwide. The mechanisms that regulate HBV viral replication remain poorly defined. Here, we...     

Vernonia longicuspis (Compositae: Vernonieae), a new combination from Bolivia

A new combination is provided in Vernonia (Compositae: Vernoniae), V. longicuspis (Dematt.) D. J. N. Hind, based on Lessingianthus longicuspis Dematt., recently described from Bolivia (Santa Cruz) and Brazil (Mato Grosso and Mato Grosso do Sul).     

Microsomal and cytosolic cytochrome P450 mediated benzo(a)pyrene hydroxylation in Pleurotus pulmonarius

Summary Microsomal and soluble fractions of Pleurotus pulmonarius exhibited a reduced carbon monoxide difference spectrum with P450 maxima at 448nm and 450–452nm respectively. Substrate induced Type I spectra were observed on addition of benzo(a)pyrene to both fractions. Benzo(a)pyrene hydroxylation was measured using the aryl hydrocarbon hydroxylase assay and was observed to be P450 dependent as indicated by carbon monoxide inhibition together with the substrate binding characteristics. The activity of the fractions were observed to give K_m of 200mM and 660mM and V_max of 1.25 nmol/min/nmol P450 and 0.57 nmol/min/nmol P450 for the microsomal and cytosolic fractions respectively.     

Protective effect of l-carnitine against acrylamide-induced DNA damage in somatic and germ cells of mice

Recent findings of acrylamide (AA) in many common foods have sparked renewed interest in assessing human health hazards. AA was evaluated by the International Agency for Research on Cancer as probably carcinogenic to humans. For this reason, the aim of this study is to evaluate the potential genotoxic effect of AA using chromosomal aberration analysis and micronucleus (MN) test in mouse bone-marrow cells and morphological sperm abnormalities. The result of the present work indicated that treatment with a single dose of 10, 20, or 30 mg/kg b.wt. of AA for 24 h and the repeated dose of 10 mg/kg b.wt. for 1and 2 weeks induced a statistically significant increase in the percentage of chromosomal aberrations and micronuclei in bone- marrow cells. These percentages reduced significantly in all groups treated with AA and the protective agent l-carnitine. Also the results indicated that the dose 10, 20 and 30 mg/kg b.wt. of AA induced a statistically significant percentage of morphological sperm abnormalities compared with the control group. Such effect reached its maximum (7.24 ± 0.61) with the highest tested dose which reduced to (4.02 ± 0.58) in the group treated with the same dose of AA and l-carnitine. In conclusion, the results confirm the protective role of LC against the mutagenicity of AA.