Palmitoylation of Plasmodium alveolins promotes cytoskeletal function.

S-palmitoylation is a post-translational lipid modification that is widespread among Plasmodium proteins and essential for parasite development. Little is known about the contribution of palmitoylation to the function of individual parasite molecules and structures. Alveolins are major components of the subpellicular network (SPN), a cortical cytoskeleton primarily involved in providing mechanical strength to the cell. We show here that the alveolin IMC1c is palmitoylated on a conserved cysteine motif, and that non-palmitoylated IMC1c displays normal expression, stability and trafficking. However, mutant parasites exhibit reduced osmotic stress resistance and tensile strength. These findings support the hypothesis that alveolin palmitoylation enhances cytoskeletal function by strengthening the connection between the SPN and the adjoining inner membrane complex via lipid anchoring

Effect of Reaction Pressure and Carrier Gas on Toluene Disproportionation over Molybdenum-ZSM-5 Catalyst.

This study was aimed at evaluating the effects of reaction pressure and temp. on toluene disproportionation using a ZSM-5-based catalyst impregnated with molybdenum. The results of the study showed that both toluene conversion and xylene selectivity were strongly dependent on temp., pressure, and the kind of carrier gas used. Toluene conversion compared at the same temp. and pressure is higher when nitrogen instead of hydrogen was used as the carrier gas. For both carrier gases, toluene conversion increased with both pressure and temp. Also, catalyst deactivation was more rapid and more severe with nitrogen as the carrier gas than with hydrogen

The Plasmodium alveolin IMC1a is stabilised by its terminal cysteine motifs and facilitates sporozoite morphogenesis and infectivity in a dose-dependent manner.

Apicomplexan parasites possess a unique cortical cytoskeleton structure composed of intermediate filaments. Its building blocks are provided by a conserved family of proteins named alveolins. The core alveolin structure is made up of tandem repeat sequences, thought to be responsible for the filamentous properties of these proteins. A subset of alveolins also possess conserved motifs composed of three closely spaced cysteine residues situated near the ends of the polypeptides. The roles of these cysteine motifs and their contribution to alveolin function remains poorly understood. The sporozoite-expressed IMC1a is unique within the Plasmodium alveolin family in having conserved cysteine motifs at both termini. Using transgenic Plasmodium berghei parasites, we show in this structure-function analysis that mutagenesis of the amino- or carboxy-terminal cysteine motif causes marked reductions in IMC1a protein levels in the parasite, which are accompanied by partial losses of sporozoite shape and infectivity. Our findings give new insight into alveolin function, identifying a dose-dependent effect of alveolin depletion on sporozoite size and infectivity, and vital roles of the terminal cysteine motifs in maintaining alveolin stability in the parasite

Catalytic Transformation Of C-7-C9 Methyl Benzenes Over USY-Based FCC Zeolite Catalyst

Catalytic transformation of three methyl benzenes (toluene, m-xylene, and 1,2,4- trimethylbenzene) has been investigated over USY-based FCC zeolite catalyst in a novel Riser Simulator at different operating conditions. The effect of reaction conditions on the variation of isomerization to disproportionation products ratio (I/D), distribution of trimethylbenzene (TMB) isomers (1,3,5-to-1,2,3-) and values of pxylene/ o-xylene (P/O) ratios are reported. The sequence of reactivity of the three alkyl benzenes was found to decrease as the number of methyl group per benzene ring decreases, as follows: 1,2,4-trimethylbenzene > m-xylene > toluene. This is true at all temperatures investigated over the USY zeolite. Toluene was found unreactive in our reaction condition. Effectiveness factor (eta(ss)) of both 1,2,4-TMB and m-xylene have been estimated. While m-xylene's eta(ss) was close to unity at all condition, 1,2,4-TMB's eta(ss) was less than that of m-xylene. The effectiveness factor was estimated from the quasi-steady state approximation modeling of the experimental data involving a decay function based on 'Time on Stream' (TOS). Based on the present study, it was found that the number of methyl groups has the most important role on the reactivity of 1,2,4-TMB, m-xylene and toluene over Y-based catalyst

ANTAGONISTIC EFFECT OF MUSK ON ORGANISMS DIFFERENT TYPES

Objective: This study aims to The research aimed at a comparative study the effect of natural and synthetic musk compared to creams that have an anti-fungal and anti-bacterial effect on the growth of Candida albicans that causes vaginal diseases in women, as well as the growth of the bacteria strains include Staphylococcus aureus, Bacillus subtilis, which would be more effective in inhibiting the growth of these microbes and Achieve the recommendation of the Prophet Muhammad for women to treat the vagina with natural musk, find alternatives to synthetic antibiotics, and reduce their negative effects on human health. Methods: This study investigates the antagonistic effect of Anti fungal and bacterial Cream and different natural type {Musk (N. M), Black Musk (B. M)} and chemical Musk {white Musk (W. M), cream Musk (M. C) } on some microorganisms. The types of yeast Candida albicans HVS and the bacteria strains include Staphylococcus aureus, Bacillus subtilis, were tested by means of disk diffusion, Results: Results indicated that Musk has inhibitory effects on the growth of study microorganisms Musk contains active substances similar to antibiotic, alkaloids and volatile oils present in them as they have the ability to stop the growth of many microorganisms. The effect of natural musk was higher than the effect synthetic musk, And the microbes were the most sensitive to musk is Bacillus subtilis. As for anti-microbial creams, the effect of the anti-bacterial cream was more effective in their suppression compared to all kinds of musk unlike the anti-fungal cream which gave a negative result. Conclusion: This study showed that the different concentrations of natural musk have an effective role in inhibiting some of the microbes of this vaginal pathogen, and it has given a positive opposite result to these microbes, and therefore it can be used as a natural antibiotic that reduces side effects on females and the environment

Structural changes in FeOx/γ-Al2O3 catalysts during ethylbenzene dehydrogenation

The structural changes that occur in a FeOx/γ-Al2O3 catalyst during the dehydrogenation of ethylbenzene in a fluidized CREC Riser Simulator have been investigated. Chemical and morphological changes are observed to take place as a result of reaction. Electron microscopy reveals the formation of needle-like alumina structures apparently enclosing iron oxide particles. The formation of such structures at relatively low temperatures is unexpected and has not previously been reported. Additionally, X-ray diffraction and Mössbauer spectroscopy confirmed the reduction of the oxidation state of iron, from Fe2O3 (haematite) to Fe3O4 (magnetite). Iron carbides, Fe3C and ɛ-Fe2C, were detected by electron microscopy through electron diffraction and lattice fringes analysis. Carbon deposition (coking) on the catalyst surface also occurs. The observed structural changes are likely to be closely correlated with the catalytic properties of the materials, in particular with catalyst deactivation, and thereby provide important avenues for future study of this industrially important reaction. Fe2O3/Al2O3 catalyst undergoes chemical and morphological changes during ethylbenzene dehydrogenation forming Al2O3 needles which appear to contain reduced Fe3O4 particles. Fe3C also forms during reaction

Catalytic mechanism of the dehydrogenation of ethylbenzene over Fe-Co/Mg(Al)O derived from hydrotalcites

Catalytic mechanism of ethylbenzene dehydrogenation over Fe-Co/Mg(Al)O derived from hydrotalcites has been studied based on the XAFS and XPS catalyst characterization and the FTIR measurements of adsorbed species. Fe-Co/Mg(Al)O showed synergy, whereas Fe-Ni/Mg(Al)O showed no synergy, in the dehydrogenation of ethylbenzene. Ni species were stably incorporated as Ni(2+) in the regular sites in periclase and spinel structure in the Fe-Ni/Mg(Al)O. Contrarily, Co species exists as a mixture of Co(3+)/Co(2+) in the Fe-Co/Mg(Al)O and was partially isolated from the regular sites in the structures with increasing the Co content. Co addition enhanced Lewis acidity of Fe(3+) active sites by forming Fe(3+)-O-Co(3+/2+)(1/1) bond, resulting in an increase in the activity. FTIR of ethylbenzene adsorbed on the Fe-Co/Mg(Al)O clearly showed formations of C-O bond and pi-adsorbed aromatic ring. This suggests that ethylbenzene was strongly adsorbed on the Fe(3+) acid sites via pi-bonding and the dehydrogenation was initiated by alpha-H(+) abstraction from ethyl group on Mg(2+)-O(2-) basic sites, followed by C-O-Mg bond formation. The alpha-H(+) abstraction by O(2-)(-Mg(2+)) was likely followed by beta-H abstraction, leading to the formations of styrene and H(2). Such catalytic mechanism by the Fe(3+) acid-O(2-)(-Mg(2+)) base couple and the Fe(3+)/Fe(2+) reduction-oxidation cycle was further assisted by Co(3+)/Co(2+), leading to a good catalytic activity for the dehydrogenation of ethylbenzene

SAS6-like protein in Plasmodium indicates that conoid-associated apical complex proteins persist in invasive stages within the mosquito vector

The SAS6-like (SAS6L) protein, a truncated paralogue of the ubiquitous basal body/centriole protein SAS6, has been characterised recently as a flagellum protein in trypanosomatids, but associated with the conoid in apicomplexan Toxoplasma. The conoid has been suggested to derive from flagella parts, but is thought to have been lost from some apicomplexans including the malaria-causing genus Plasmodium. Presence of SAS6L in Plasmodium, therefore, suggested a possible role in flagella assembly in male gametes, the only flagellated stage. Here, we have studied the expression and role of SAS6L throughout the Plasmodium life cycle using the rodent malaria model P. berghei. Contrary to a hypothesised role in flagella, SAS6L was absent during gamete flagellum formation. Instead, SAS6L was restricted to the apical complex in ookinetes and sporozoites, the extracellular invasive stages that develop within the mosquito vector. In these stages SAS6L forms an apical ring, as we show is also the case in Toxoplasma tachyzoites. The SAS6L ring was not apparent in blood-stage invasive merozoites, indicating that the apical complex is differentiated between the different invasive forms. Overall this study indicates that a conoid-associated apical complex protein and ring structure is persistent in Plasmodium in a stage-specific manner