Influence of selenium on toxicity of some heavy metals in the green algaScenedesmus obliquus

The green alga Scenedesmus obliquus was incubated with heavy metals (Cd2+, Zn2+, Mn2+, Ni2+) with and without selenium. S. obliquus exhibited higher rates of growth and some metabolic activities in cultures containing 0.1 mmol/L Se than those only containing the heavy metals. The positive effect of Se was found with all metals but was negligible with Mn2+.     

Effects of the inoculation of cyanobacteria on the microstructure and the structural stability of a tropical soil

Cyanobacteria are widespread photosynthetic microorganisms among which some are able to fix atmospheric nitrogen. We investigated the impact of indigenous cyanobacteria strains (Nostoc) inoculation on physical characteristics of poorly aggregated soils from Guquka (Eastern Cape, South Africa). The soil aggregates (3–5 mm) were arranged into a layer of 10–20 mm thick, and sprayed with cyanobacteria solution. Subsequently the inoculated and un-inoculated samples were incubated (30°C, 80% humidity, continuous illumination at 100 μmol m⁻² s⁻¹). Their micromorphological characteristics and aggregate stability were investigated, after 1, 2, 3, 4 and 6 weeks of incubation, by using high resolution Cryo-SEM and aggregate breakdown tests. Micromorphological investigations revealed that the surface of un-inoculated samples remained uncovered, while the inoculated samples were partially covered by cyanobacteria material after one week of incubation. A dense superficial network of cyanobacterial filaments and extracellular polymer secretions (EPS) covered their surface after 4 and 6 weeks of incubation. Organo-mineral aggregates comprising cyanobacterial filaments and EPS were observed after 6 weeks of incubation. The results of aggregate breakdown tests showed no significant difference between un-inoculated samples after 1, 2, 3, 4 or 6 weeks, while they revealed improvement of aggregate stability for inoculated samples. The improvement of aggregate stability appeared in a short while following inoculation and increased gradually with time and cyanobacteria growth. The increase in aggregate stability is likely related to the changes induced in micromorphological characteristics by cyanobacterial filaments and EPS. It reflects the effect of coating, enmeshment, binding and gluing of aggregates and isolated mineral particles by cyanobacteria material. Our study presents new data demonstrating the improvement of soil physical quality in a few weeks after cyanobacteria inoculation. The interaction of the inocula and other biotic components is worthy of study before field application of cyanobacteria.     

Isolation and Characterization of Polycyclic Aromatic Hydrocarbon–Degrading Mycobacterium Isolates from Soil

Bioremediation of soils contaminated with wood preservatives containing polycyclic aromatic hydrocarbons (PAHs) is desired because of their toxic, mutagenic, and carcinogenic properties. Creosote wood preservative–contaminated soils at the Champion International Superfund Site in Libby, Montana currently undergo bioremediation in a prepared-bed land treatment unit (LTU) process. Microbes isolated from these LTU soils rapidly mineralized the ¹⁴C-labeled PAH pyrene in the LTU soil. Gram staining, electron microscopy, and 16S rDNA-sequencing revealed that three of these bacteria, JLS, KMS, and MCS, were Mycobacterium strains. The phylogeny of the 16S rDNA showed that they were distinct from other Mycobacterium isolates with PAH-degrading activities. Catalase and superoxide dismutase (SOD) isozyme profiles confirmed that each isolate was distinct from each other and from the PAH-degrading mycobacterium, Mycobacterium vanbaalenii sp. nov, isolated from a petroleum-contaminated soil. We find that dioxygenase genes nidA and nidB are present in each of the Libby Mycobacterium isolates and are adjacent to each other in the sequence nidB-nidA, an order that is unique to the PAH-degrading mycobacteria.This revised version was published online in November 2004 with corrections to Volume 48.     

Covalent trimers of the internal N-terminal trimeric coiled-coil of gp41 and antibodies directed against them are potent inhibitors of HIV envelope-mediated cell fusion

We have engineered two soluble, covalently linked, trimeric polypeptides, N35CCG-N13 and N34CCG comprising only the internal trimeric coiled-coil of the ectodomain of HIV-1 gp41. Both trimers inhibit human immunodeficiency virus, type 1 (HIV-1) envelope (Env)-mediated cell fusion at nanomolar concentrations by targeting the exposed C-terminal region of the gp41 ectodomain in the prehairpin intermediate state. The IC50 values for N35CCG-N13 and N34CCG are approximately 15 and approximately 95 nM, respectively, in a quantitative vaccinia virus-based reporter gene assay for HIV-1 Env-mediated cell fusion using Env from the T cell tropic strain LAV. Polyclonal antibodies were raised against N35CCG-N13 and a tightly binding fraction of anti-N35CCG-N13 inhibits T cell and macrophage tropic HIV-1 Env-mediated cell fusion with respective IC50 values of approximately 0.5 and approximately 1.5 microg/ml at 37 degrees C. The tightly binding anti-N35CCG-N13 antibody fraction targets the exposed internal trimeric coiled-coil in the prehairpin intermediate state of gp41 in a manner analogous to peptides derived from the C region of the gp41 ectodomain. The potency of the tightly binding anti-N35CCG-N13 antibody fraction in the fusion assay is comparable with that of the broadly neutralizing monoclonal antibody 2G12. These results indicate that N35CCG-N13 is a potential anti-HIV therapeutic agent and represents a suitable immunogen for the generation of neutralizing monoclonal antibodies targeted to the internal trimeric coiled-coil of gp41. The data on the tightly binding anti-N35CCG-N13 antibody fraction demonstrate that the internal trimeric coiled-coil of gp41 in the prehairpin intermediate state is accessible to antibodies and that access is not restricted by either antibody size or the presence of a kinetic barrier.     

The effect of willow leaf extracts on human leukemic cells in vitro

The young developing leaves of willow (Salix safsaf, Salicaceae) trees have antileukemic activity. After a 24-h incubation in vitro, the crude water extracts of the leaves killed a majority of the blasts of acute myeloid leukemia (AML, 73.8%).     

Population genetic structure of North Atlantic, Mediterranean Sea and Sea of Cortez fin whales, Balaenoptera physalus (Linnaeus 1758): analysis of mitochondrial and nuclear loci

Samples were collected from 407 fin whales, Balaenoptera physalus , at four North Atlantic and one Mediterranean Sea summer feeding area as well as the Sea of Cortez in the Pacific Ocean. For each sample, the sex, the sequence of the first 288 nucleotides of the mitochondrial (mt) control region and the genotype at six microsatellite loci were determined. A significant degree of divergence was detected at all nuclear and mt loci between North Atlantic/Mediterranean Sea and the Sea of Cortez. However, the divergence time estimated from the mt sequences was substantially lower than the time elapsed since the rise of the Panama Isthmus, suggesting occasional gene flow between the North Pacific and North Atlantic ocean after the separation of the two oceans. Within the North Atlantic and Mediterranean Sea, significant levels of heterogeneity were observed in the mtDNA between the Mediterranean Sea, the eastern (Spain) and the western (the Gulf of Maine and the Gulf of St Lawrence) North Atlantic. Samples collected off West Greenland and Iceland could not be unequivocally assigned to either of the two areas. The homogeneity tests performed using the nuclear data revealed significant levels of divergence only between the Mediterranean Sea and the Gulf of St Lawrence or West Greenland. In conclusion, our results suggest the existence of several recently diverged populations in the North Atlantic and Mediterranean Sea, possibly with some limited gene flow between adjacent populations, a population structure which is consistent with earlier population models proposed by Kellogg, Ingebrigtsen, and Sergeant.     

Fine Needle Aspiration Cytodiagnosis of Subacute (De Quervain's) Thyroiditis In an Endemic Goitre Area

Between 1977 and 1989 252 fine needle aspirates (FNAs) of the thyroid from patients with a clinical suspicion of subacute granulomatous (de Quervain's) thyroiditis were examined in the Department of Pathology of the University of Innsbruck, Austria. In the same period 31 cases with preoperative FNA were diagnosed histologically as subacute thyroiditis. Only in three of these cases were the cytological features of de Quervain's thyroiditis found in the preoperative FNA. However, in 13 of these 31 cases a cytological suspicion of malignancy was obtained. Subsequent histological examination revealed an acute phase inflammation of de Quervain's thyroiditis in most of these cases. We conclude that an accurate FNA diagnosis of de Quervain's thyroiditis, particularly in the acute stage, may cause difficulties due to a lack of typical features and the appearance of atypical thyroid follicular cells. For the cytopathologist, accurate clinical information relating to the possibility of de Quervain's thyroiditis is essential if unnecessary surgery is to be avoided.     

Amyloidosis and periodic peritonitis (familial mediterranean Fever)

Some reports indicate that amyloidosis is a rare occurrence in persons with periodic peritonitis (familial Mediterranean fever), while others seem to show it occurs relatively frequently. Two cases were seen among 80 patients in Iraq. Twenty-one consecutive rectal biopsies were negative for amyloidosis. The variation in reported incidence is partly real and partly apparent. Amyloidosis occurs frequently in certain ethnic groups, and it is possible that there are two traits, one for periodic peritonitis and the other for amyloidosis.