Overcoating of Toxoplasma Parasitophorous Vacuoles with Host Cell Vimentin Type Intermediate Filaments

The interaction between the Toxoplasma parasitophorous vacuole and vimentin-type intermediate filaments in Vero cells was investigated via immunofluorescence microscopy. A significant rearrangement of host cell vimentin around the Toxoplasma parasitophorous vacuoles occurs throughout the course of infection. Host cell vimentin associates with the parasitophorous vacuoles within an hour after invasion. This vimentin overcoating of the vacuole is initiated at the host cell nuclear surface. During parasite multiplication, vimentin retains a closely defined association with the cytosolic surface of the parasitophorous vacuole. In addition, the vimentin intermediate filaments originating from the host cell nuclear surface are progressively rearranged around the enlarging parasitophorous compartment. During infections, the order of vimentin cytoskeleton is normal throughout the cell and appears redefined only at the vicinity of the parasitophorous vacuole. Depolymerization of the intermediate filaments was achieved with the phosphatase inhibitors okadaic acid and calyculin A. Disruption of the intermediate filament networks resulted in displacement of the parasitophorous vacuoles from the host cell nuclear surface. The data indicate that host cell vimentin binds to the Toxoplasma parasitophorous vacuoles and that the host intermediate filament network serves to dock the parasite compartment to the host cell nuclear surface.     

Microsporidian Spore Discharge and the Transfer of Polaroplast Organelle Membrane into Plasma Membrane

Electron microscopic examinations of Glugea hertwigi and Spraguea lophii spores indicated the presence of a single plasma membrane; however, this membrane remained in the spore during the discharge of the sporoplasm from the spore. Although discharged spores retained the old plasma membrane, the extruded sporoplasms acquired a new plasma membrane. In order to determine where the new plasma membrane came from, we used two fluorescent probes with membrane affinities. The markers were tested on unfired and discharged spores. The probe, N-phenyl-1-naphthylamine (NPN), labeled the polaroplast membrane in addition to the apolar groups in the posterior vacuoles of unfired spores. After spore discharge, NPN label disappeared from the spore ghosts except for a slight fluorescence on residual plasma membranes. Much of the NPN-labeled membrane reappeared after spore discharge on the outer envelope of discharged sporoplasms. The probe chlorotetracycline (CTC) labeled calcium-associated membranes of spore polaroplasts. During spore discharge, the CTC fluorescence shifted from the polaroplast organelle of unfired spores to the outer envelope of discharged sporoplasms. These results indicate that the polaroplast organelle may provide the new plasma membrane for discharged microsporidian sporoplasms.     

A correlation between BCL-2 modifying factor,p53 and livin gene expressions in cancer colon patients

Accumulating evidence has revealed that livin gene and BCL-2 modifying factor (BMF) gene are closely associated with the initiation and progression of colon carcinoma by activating or suppressing multiple malignant processes. Those genes that can detect colon - cancer are a promising approach for cancer screening and diagnosis. This study aimed to evaluate correlation between livin, BMF and p53 genes expression in colon cancer tissues of patients included in the study, and their relationship with clinicopathological features and survival outcome in those patients. In this study, 50 pathologically diagnosed early cancer colon patients included and their tissue biopsy with 50 matched adjacent normal tissue, and 50 adenoma tissue specimens were analyzed for livin gene and BMF gene expressions using real time PCR. The relationship of those genes expressions with clinicopathological features, tumor markers, Time to Progression and overall survival for those patients were correlated in cancer colon group. In this study, there was a significant a reciprocal relationship between over expression of livin gene and down regulation of BMF and p53 genes in colon cancer cells. Livin mRNA was significantly higher, while BMF and p53 mRNA were significantly lower in colorectal cancer tissue compared to benign and normal colon tissue specimens (P < 0.001), however, this finding was absent between colon adenomas and normal mucosa. There was a significant association between up regulation of livin and down regulation of BMF and p53 expressions with more aggressive tumor (advanced TNM stage), rapid progression with metastasis and decreased overall survival in cancer colon patients, hence these genes can serve as significant prognostic markers of poor outcome in colon cancer patients. This work highlights the role of livin, BMF and p53 genes in colorectal tumorigenesis and the applicability of using those genes as a diagnostic and prognostic markers in patients with colon carcinoma and as a good target for cancer colon treatment in the future.     

Biocides formulation of essential oils having antimicrobial activity

Essential oils of fennel, peppermint, caraway, eucalyptus, geranium and lemon were tested for their antimicrobial activities against some plant pathogenic micro-organisms (Fusarium oxysporum, Alternaria alternate, Penicilium italicum Penicilium digitatum and Botyritus cinerea). Essential oils of fennel, peppermint, caraway were selected as an active ingredient for the formulation of biocides due to their efficiency in controlling the tested micro-organisms. Successful emulsifiable concentrates (biocides) were prepared from these oils using different emulsifiers (Emulgator B.L.M. Tween20 and Tween80) and different fixed oils (sesame, olive, cotton and soybean oils). Physico-chemical properties of the formulated biocide (spontaneous emulsification, emulsion stability test, cold stability and heat stability tests as well as viscosity, surface tension and pH) were measured. The prepared biocides were ready to be tested for application in a future work as a safe pesticide against different pathogens.     

Metagenomic insights into strategies of carbon conservation and unusual sulfur biogeochemistry in a hypersaline Antarctic lake

Organic Lake is a shallow, marine-derived hypersaline lake in the Vestfold Hills, Antarctica that has the highest reported concentration of dimethylsulfide (DMS) in a natural body of water. To determine the composition and functional potential of the microbial community and learn about the unusual sulfur chemistry in Organic Lake, shotgun metagenomics was performed on size-fractionated samples collected along a depth profile. Eucaryal phytoflagellates were the main photosynthetic organisms. Bacteria were dominated by the globally distributed heterotrophic taxa Marinobacter, Roseovarius and Psychroflexus. The dominance of heterotrophic degradation, coupled with low fixation potential, indicates possible net carbon loss. However, abundant marker genes for aerobic anoxygenic phototrophy, sulfur oxidation, rhodopsins and CO oxidation were also linked to the dominant heterotrophic bacteria, and indicate the use of photo- and lithoheterotrophy as mechanisms for conserving organic carbon. Similarly, a high genetic potential for the recycling of nitrogen compounds likely functions to retain fixed nitrogen in the lake. Dimethylsulfoniopropionate (DMSP) lyase genes were abundant, indicating that DMSP is a significant carbon and energy source. Unlike marine environments, DMSP demethylases were less abundant, indicating that DMSP cleavage is the likely source of high DMS concentration. DMSP cleavage, carbon mixotrophy (photoheterotrophy and lithoheterotrophy) and nitrogen remineralization by dominant Organic Lake bacteria are potentially important adaptations to nutrient constraints. In particular, carbon mixotrophy relieves the extent of carbon oxidation for energy production, allowing more carbon to be used for biosynthetic processes. The study sheds light on how the microbial community has adapted to this unique Antarctic lake environment.     

Post-Pleistocene evolution of Bornean shrews Crocidura foetida (Mammalia, Soricidae)

Fossil mandibles of the Bornean shrew Crocidura foetida recovered from excavations at the west mouth of Niah cave, Sarawak, Malaysia, show that the late Pleistocene population at this lowland location was comparable in size with the large subspecies Crocidura foetida doriae , presently occurring at inland, upland locations. Two Holocene specimens fall in the size range of the smaller lowland subspecies C. f. foetida . Comparable post-Pleistocene size-reduction is known among other mammals of Borneo, but this is the first instance of dated examples. The evolutionary trend conforms with Bergmann's 'rule' but, other than climate change, no selective agent is apparent.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 413–419.