Search

Summary Nucleotide sequences of chloroplast-encoded small subunit rRNA genes have been determined for three strains of chlorarachniophyte algae.The chlorarachniophyte sequences were added to phylogenies incorporating plastid and bacterial sequences in an attempt to define the evolutionary relationships of the eukaryotic endosymbiont from which chlorarachniophytes acquired photosynthetic capacity.Substitutional bias increasing the AT content of the chlorarachniophyte rRNA genes apparently confounds the inference of plastid phylogenetic relationships using traditional methodology (distance, parsimony, maximum likelihood).However, when the LogDet transformation (a method allowing more accurate tree inference under conditions of varying substitution bias) was used, the chlorarachniophytes were grouped basal to a clade containing euglenophytes, green algae, and the land plants.The LogDet rRNA tree thus places all chlorophyll b-containing plastids in a monophyletic lineage.As an independent test of the LogDet tree, we determined a partial coding sequence for the large subunit of ribulose bisphosphate carboxylase (rbcL) from a chlorarachniophyte.The deduced amino acid sequence was incorporated into a plastid phylogeny which should be less prone to substitutional biases.In perfect agreement with the LogDet rRNA phylogeny, the rbcL tree positions the chlorarachniophyte at the base of a clade containing euglenophytes, green algae, and plants.We therefore believe that chlorarachniophytes contain an endosymbiont derived from an early part of the green algal/plant radiation.Moreover, since the chlorarachniophyte rbcL is more similar to green algae, plant, and cyanobacterial rbcL genes, while the cryptophytes have a 13- proteobacterial-like rbcL gene, cryptophytes and chlorarachniophytes most probably obtained their secondary endosymbionts independently, after the different types of rbcL genes were established in the lineages of primary plastids.

Nascent and melt-crystallized ultrahigh molecular weight polyethylene (PE) have been studied using solid-state 13 C NMR spectroscopy. Significant differences between the two materials are observed in the CPMAS spectra particularly at elevated temperatures. Three separate resonances are observed in nascent samples when the temperature is raised to near the melting point, the third peak being of an intermediate chemical shift between the crystalline and amorphous resonances that are observed in the spectra of melt-crystallized samples. Based on this chemical shift, the third resonance is likely due to polymer chains which undergo conformational averaging which is intermediate between the rigid all-trans crystalline polymer and very mobile amorphous chains. Evidence is reported which shows that this is material that is present in nascent PE below the melting point and is not created during the melting process. These observations are confirmed by the measurement of 2D wide-line separation (WISE) experiments where the 1 H line width of the amorphous component of melt-crystallized PE is much narrower than that of a nascent sample. Numerous nascent PE samples, including those of low molecular weight, display similar spectral features

Southern hybridisation, polymerase chain reaction (PCR), and nucleotide sequence, data indicate that the 5s ribosomal RNA (rRNA) gene is linked to the main rRNA gene repeat in the nuclear genome of four cryptomonad algae (Rhinomonas pauca, Storeatula major, Komma caudata, and isolate Cs 134). The 5s gene is apparently transcribed in the same direction as the large and small subunit rRNA genes. The intergenic spacer between the 5s gene and the large subunit rRNA gene exhibits length and sequence polymorphism among the different species. Cryptomonads contain two different eukaryotic genomes: the host nucleus and the nucleus of a eukaryotic endosymbiont. Mapping experiments with isolated chromosomes of the host and endosymbiont genomes showed that the intergenic spacer between the large subunit and the 5s rRNA gene, which was amplified from total DNA by PCR, was derived from the host nuclear genome.

New molecular data confirm what electron microscopists long suspected - fusion of two different eukaryotic cells into a single more-complex cell created novel groups of protists. By engulfing an algal cell and putting it to work as a solar-powered food factory, heterotrophic protozoans became autotrophic. Drastically reduced, the engulfed cell now exists as an organelle in the host cell. Such blending of lineages was perhaps a driving force in early eukaryotic diversification.

The Raman spectra of the ammonia-borane complex, NH(3)BH(3), have been investigated as a function of pressure up to 40 kbar. Vibrational modes involving the NH(3) group show negative pressure dependences, supporting the existence of the dihydrogen bond, but the vibrations of the BH(3) group have a positive dependence. Two transitions were observed in the solid phase under pressure, in contrast to the temperature behavior, where a single transition occurs. Factor group splitting occurs for the degenerate vibrations, and this allows the correct assignment of the observed vibrations.

Malaria parasites modify their host cell, the mature human erythrocyte. We are interested in the molecules mediating these processes, and have recently described a family of parasite-encoded heat shock proteins (PfHsp40s) that are targeted to the host cell, and implicated in host cell modification. Hsp40s generally function as co-chaperones of members of the Hsp70 family, and until now it was thought that human Hsp70 acts as the PfHsp40 interaction partner within the host cell. Here we revise this hypothesis, and identify and characterize an exported parasite-encoded Hsp70, referred to as PfHsp70-x. PfHsp70-x is exported to the host erythrocyte where it forms a complex with PfHsp40s in structures known as J-dots, and is closely associated with PfEMP1. Interestingly, Hsp70-x is encoded only by parasite species that export the major virulence factor EMP1, implying a possible role for Hsp70-x in EMP1 presentation at the surface of the infected erythrocyte. Our data strongly support the presence of parasite-encoded chaperone/co-chaperone complexes within the host erythrocyte, which are involved in protein traffic through the host cell. The host-pathogen interaction within the infected erythrocyte is more complex than previously thought, and is driven notonly by parasite co-chaperones, but also by the parasite-encoded chaperone Hsp70-x itself.

The resonance Raman spectrum of ultramarine has been studied as a function of pressure up to 5 GPa. The overtone progressions of the ν1 fundamental and the combination bands of S 3 - and the ν1 band of S 2 - were measured and the pressure dependences were determined. The symmetric stretching mode of S 3 - is nearly harmonic. No phase transition was observed over the measured pressure range.

The wavenumbers of the ν3 metal—hydrogen stretching mode in the IR spectra of [MnH6]5-, [FeH6]4-, [RuH6]4-, [OsH6]4-, [IrH6]3-, and [PtH6]2- linearly depend on the ionization energies of the counterions (alkali metal, alkaline earth, lanthanoid) with a separate line for each metal.

The wavenumbers of the ν(3) metal-hydrogen stretching mode (T(1u)) in the IR spectra of both ternary and quaternary hexahydrido salts of transition metals from groups 7 to 10 ([Mn(I)H(6)](5-), [Fe(II)H(6)](4-), [Ru(II)H(6)](4-), [Os(II)H(6)](4-), [Ir(III)H(6)](3-), and [Pt(IV)H(6)](2-)) depend linearly upon the ionization energies of the counterions (alkali metal, alkaline earth, and lanthanide) with a separate line for each metal. This relationship provides quantitative support for the charge-transfer mechanism for explaining the stabilities of these compounds.

To survive within its host erythrocyte, Plasmodium falciparum must export hundreds of proteins across both its parasite plasma membrane and surrounding parasitophorous vacuole membrane, most of which are likely to use a protein complex known as PTEX (Plasmodium translocon of exported proteins). PTEX is a putative protein trafficking machinery responsible for the export of hundreds of proteins across the parasitophorous vacuole membrane and into the human host cell. Five proteins are known to comprise the PTEX complex, and in this study, three of the major stoichiometric components are investigated including HSP101 (a AAA+ ATPase), a protein of no known function termed PTEX150, and the apparent membrane component EXP2. We show that these proteins are synthesized in the preceding schizont stage (PTEX150 and HSP101) or even earlier in the life cycle (EXP2), and before invasion these components reside within the dense granules of invasive merozoites. From these apical organelles, the protein complex is released into the host cell where it resides with little turnover in the parasitophorous vacuole membrane for most of the remainder of the following cell cycle. At this membrane, PTEX is arranged in a stable macromolecular complex of >1230 kDa that includes an ∼600-kDa apparently homo-oligomeric complex of EXP2 that can be separated from the remainder of the PTEX complex using non-ionic detergents. Two different biochemical methods undertaken here suggest that PTEX components associate as EXP2-PTEX150-HSP101, with EXP2 associating with the vacuolar membrane. Collectively, these data support the hypothesis that EXP2 oligomerizes and potentially forms the putative membrane-spanning pore to which the remainder of the PTEX complex is attached.

Targeted regulation of protein levels is an important tool to gain insights into the role of proteins essential to cell function and development. In recent years, a method based on mutated forms of the human FKBP12 has been established and used to great effect in various cell types to explore protein function. The mutated FKBP protein, referred to as destabilization domain (DD) tag when fused with a native protein at the N- or C-terminus targets the protein for proteosomal degradation. Regulated expression is achieved via addition of a compound, Shld-1, that stabilizes the protein and prevents degradation. A limited number of studies have used this system to provide powerful insight into protein function in the human malaria parasite Plasmodium falciparum. In order to better understand the DD inducible system in P. falciparum, we studied the effect of Shld-1 on parasite growth, demonstrating that although development is not impaired, it is delayed, requiring the appropriate controls for phenotype interpretation. We explored the quantified regulation of reporter Green Fluorescent Protein (GFP) and luciferase constructs fused to three DD variants in parasite cells either via transient or stable transfection. The regulation obtained with the original FKBP derived DD domain was compared to two triple mutants DD24 and DD29, which had been described to provide better regulation for C-terminal tagging in other cell types. When cloned to the C-terminal of reporter proteins, DD24 provided the strongest regulation allowing reporter activity to be reduced to lower levels than DD and to restore the activity of stabilised proteins to higher levels than DD29. Importantly, DD24 has not previously been applied to regulate proteins in P. falciparum. The possibility of regulating an exported protein was addressed by targeting the Ring-Infected Erythrocyte Surface Antigen (RESA) at its C-terminus. The tagged protein demonstrated an important modulation of its expression.

Variable-temperature and -pressure effects on the solid phases of 2-thiopyridone and 2-pyridone have been studied using infrared and Raman spectroscopy. At ambient pressure, no temperature-induced phase transitions were found to take place in either solid over a temperature range from about 50 to 295 K. At pressures above 17 kbar the relative intensity of the NH stretch band in the spectra of 2-thiopyridone decreases significantly, and a number of other bands showed changes in the pressure dependence of their frequencies. Similar changes occur in the relative intensity of the NH and O ⋯ H stretching regions for 2-pyridone at 9 kbar. The lattice modes showed large changes in the pressure dependence of their frequencies.

The nucleotide sequence of the polymerase chain reaction (PCR)-amplified small subunit ribosomal RNA gene of Goniomonas truncata was determined. Addition of the Goniomonas sequence to the eukaryotic phylogenetic tree revealed this heterotrophic flagellate to be the sister taxon of photosynthetic cryptomonads. The molecular phylogeny supports morphological data suggesting that Goniomonas diverted from the cryptomonad lineage prior to their acquisition of a plastid through endosymbiosis of a eukaryote. Goniomonas, which is phagotrophic, may thus represent an extant relative of the host component of cryptomonad algae.

The 31 P chemical shift anisotropies have been measured for solid triphenyl phosphite, P(OPh) 3 (at 128 K), and the complex with the tricarbonyl(thiocarbonyl)chromium(b) moiety, mer,trans-Cr(CO) 3 (CS) [P(OPh) 3 ] 2 (at 298 K). The shift tensor is axially symmetric in the phosphite ligand, and the major change upon complexation occurs for the components of the shift tensor perpendicular to the bond direction. The crystal structure of the chromium complex has been determined by single-crystal X-ray diffraction at 291 K. The complex crystallizes in the centric P2 1 /n (No. 14) space group with cell constants (at 20 o C) R=8.166(1) A, b=11.530(2) A, c=20.183(2) A, β=96.41(1) o , and Z=2

Cryptomonad algae contain a photosynthetic, eukaryotic endosymbiont. The endosymbiont is much reduced but retains a small nucleus. DNA from this endosymbiont nucleus encodes rRNAs, and it is presumed that these rRNAs are incorporated into ribosomes. Surrounding the endosymbiont nucleus is a small volume of cytoplasm proposed to be the vestigial cytoplasm of the endosymbiont. If this compartment is indeed the endosymbiont's cytoplasm, it would be expected to contain ribosomes with components encoded by the endosymbiont nucleus. In this paper, we used in situ hybridization to localize rRNAs encoded by the endosymbiont nucleus of the cryptomonad alga, Cryptomonas phi. Transcripts of the endosymbiont rRNA gene were observed within the endosymbiont nucleus, and in the compartment thought to represent the endosymbiont's cytoplasm. These results indicate that the endosymbiont produces its own set of cytoplasmic translation machinery. We also localized transcripts of the host nucleus rRNA gene. These transcripts were found in the nucleolus of the host nucleus, and throughout the host cytoplasm, but never in the endosymbiont compartment. Our rRNA localizations indicate that the cryptomonad cell produces two different of sets of cytoplasmic-type ribosomes in two separate subcellular compartments. The results suggest that there is no exchange of rRNAs between these compartments. We also used the probe specific for the endosymbiont rRNA gene to identify chromosomes from the endosymbiont nucleus in pulsed field gel electrophoresis. Like other cryptomonads, the endosymbiont nucleus of Cryptomonas phi contains three small chromosomes.

Chlorotris(2,4,6-trimethylphenyl)tin(IV), crystallizes from ethanol as solvent-free needles, [Sn(C(9)H(11))(3)Cl], (I), and as the hemisolvate, [Sn(C(9)H(11))(3)Cl].0.5C(2)H(6)O, (II). The asymmetric unit in (I) has three independent molecules, whereas in (II), there are two [Sn(C(9)H(11))(3)Cl] molecules together with one ethanol molecule. In the unit cell of (II), the ethanol molecules lie in channels between stacks of (Mes)(3)SnCl molecules (Mes is 2,4,6-trimethylphenyl) and each ethanol molecule is disordered (0.50:0.50) over two positions. A comparison of the structures of the title compounds and other (Mes)(3)SnX (X = F, Br or I) systems with those of the triphenyltin analogues shows that the steric requirements of the o-CH(3) groups are met by a flattening of the SnC(3) skeleton and increases in the average Sn-X and Sn-C values. Comparing Sn-X data for (Mes)(3)SnX (X = F, Cl, Br or I) systems with values for the tris(o-methoxyphenyl)tin analogues suggests that the Sn-F distance of 1.961 A in (Mes)(3)SnF may well be characteristic of sterically unhindered four-coordinate Ar(3)SnF systems.

The title compound, [MnSn(C(7)H(7)O(2)S)(3)(CO)(5)], is asymmetric but crystallizes in the highly symmetric tetragonal space group I-4. This is achieved without the need for any disorder, either around the Sn atom or in any of the methylsulfonyl groups. The environment around the Sn atom has the following geometry: Sn-Mn = 2.6564 (7) A, mean Sn-C = 2.175 (5) A, mean C-Sn-C = 103 (2) degrees and mean C-Sn-Mn = 115 (6) degrees. The crystal packing is assisted by weak Sn.O interactions between adjacent columns of molecules, with the resulting geometry at Sn approaching highly distorted trigonal-bipyramidal.

Current British HIV Association (BHIVA) guidelines recommend that all patients with a CD4 count350 cells/μL are offered highly active antiretroviral therapy (HAART). We identified risk factors for delayed initiation of HAART following a CD4 count350 cells/μL.All adults under follow-up in 2008 who had a first confirmed CD4 count350 cells/μL from 2004 to 2008, who had not initiated treatment and who had6 months of follow-up were included in the study. Characteristics at the time of the low CD4 cell count and over follow-up were compared to identify factors associated with delayed HAART uptake. Analyses used proportional hazards regression with fixed (sex/risk group, age, ethnicity, AIDS, baseline CD4 cell count and calendar year) and time-updated (frequency of CD4 cell count measurement, proportion of CD4 counts350 cells/μL, latest CD4 cell count, CD4 percentage and viral load) covariates.Of 4871 patients with a confirmed low CD4 cell count, 436 (8.9%) remained untreated. In multivariable analyses, those starting HAART were older [adjusted relative hazard (aRH)/10 years 1.15], were more likely to be female heterosexual (aRH 1.13), were more likely to have had AIDS (aRH 1.14), had a greater number of CD4 measurements 350 cells/μL (aRH/additional count 1.18), had a lower CD4 count over follow-up (aRH/50 cells/μL higher 0.57), had a lower CD4 percentage (aRH/5% higher 0.90) and had a higher viral load (aRH/log(10) HIV-1 RNA copies/ml higher 1.06). Injecting drug users (aRH 0.53), women infected with HIV via nonsexual or injecting drug use routes (aRH 0.75) and those of unknown ethnicity (aRH 0.69) were less likely to commence HAART.A substantial minority of patients with a CD4 count 350 cells/μL remain untreated despite its indication.

Objectives: To estimate the loss of quality of life and cost of treatment associated with genital warts seen in sexual health clinics.\ud \ud Methods: A cross-sectional questionnaire study and case note review of individuals with genital warts, carried out in eight sexual health clinics in England and Northern Ireland. Individuals with genital warts attending the participating clinics were invited to take part in the questionnaire study. 895 participants were recruited. A separate sample of 370 participants who had attended a participating clinic with a first visit for a first or recurrent episode of genital warts between April and June 2007 was included in the case note review. Quality of life was measured using the EQ-5D questionnaire and the cost of an episode of care was derived from the case note review.\ud \ud Results: The weighted mean EQ-5D index score was 0.87 (95% CI 0.85 to 0.89). The weighted mean disutility was 0.056 (95% CI 0.038 to 0.074). The estimated mean loss of quality-adjusted life-years associated with an episode of genital warts was 0.018 (95% CI 0.0079 to 0.031), equivalent to 6.6 days of healthy life lost per episode. The weighted mean cost per episode of care was £94 (95% CI £84 to £104), not including the cost of a sexually transmitted infection screen.\ud \ud Conclusions: Genital warts have a substantial impact on the health service and the individual. This information can be utilised for economic evaluation of human papillomavirus vaccination.\ud

Background Antibodies targeting blood stage antigens are important in protection against malaria, but the key targets and mechanisms of immunity are not well understood. Merozoite surface protein 1 (MSP1) is an abundant and essential protein. The C-terminal 19 kDa region (MSP1-19) is regarded as a promising vaccine candidate and may also be an important target of immunity. Methodology/Findings Growth inhibitory antibodies against asexual-stage parasites and IgG to recombinant MSP1-19 were measured in plasma samples from a longitudinal cohort of 206 children in Papua New Guinea. Differential inhibition by samples of mutant P. falciparum lines that expressed either the P. falciparum or P. chabaudi form of MSP1-19 were used to quantify MSP1-19 specific growth-inhibitory antibodies. The great majority of children had detectable IgG to MSP1-19, and high levels of IgG were significantly associated with a reduced risk of symptomatic P. falciparum malaria during the 6-month follow-up period. However, there was little evidence of PfMSP1-19 specific growth inhibition by plasma samples from children. Similar results were found when testing non-dialysed or dialysed plasma, or purified antibodies, or when measuring growth inhibition in flow cytometry or microscopy-based assays. Rabbit antisera generated by immunization with recombinant MSP1-19 demonstrated strong MSP1-19 specific growth-inhibitory activity, which appeared to be due to much higher antibody levels than human samples; antibody avidity was similar between rabbit antisera and human plasma. Conclusions/Significance These data suggest that MSP1-19 is not a major target of growth inhibitory antibodies and that the protective effects of antibodies to MSP1-19 are not due to growth inhibitory activity, but may instead be mediated by other mechanisms. Alternatively, antibodies to MSP1-19 may act as a marker of protective immunity.

The order–disorder behaviour of 1-chloroadamantane (1-C10H15Cl) has been investigated by differential scanning calorimetry, and variable-temperature vibrational and 13C NMR spectroscopy. The factor group splittings in the vibrational spectra are in accord with the known crystal structures of the two phases. The 13C spin-lattice relaxation times and dipolar dephasing measurements have been analysed to give the barriers to rotation in both phases and to determine the nature of the rotations in each phase. In the ordered phase, the motion is limited to rotation about the molecular axis. In the disordered phase, additional motions occur about axes through the tertiary carbon atoms.

An integrable generalization to 2+1 dimensions of the shallow water wave equation of Ablowitz, Kaup, Newell and Segur [Stud. Appl. Math. 53 (1974) 249] is sought through the bilinear approach. This equation is shown to belong to the KP hierarchy and a broad class of solutions including the N-soliton solution is obtained.

The Raman spectrum of gaseous CdI 2 shows a strong polarized band at 153 cm −1 which is the symmetric stretching vibration (ν 1 ) of this molecule. No detectable change could be found in the presence of CsI even at 1030°C and a total pressure of the order of five atmospheres.

Variable-temperature Raman and infrared spectroscopic methods have been used to examine the order-disorder phase transition in cyclohexanone. A factor group analysis predicts that the low-temperature phase has an orthorhombic unit cell wit C 2υ symmetry with two molecules per unit cell. Deuterium NMR line-shape studies show that, on heating, motional narrowing commences well below the phase-transition temperature of 235 K, and isotropic rotation occurs in the high-temperature phase

Deuterium quadrupole echo spectroscopy has been used to probe the orientational behaviour and dynamics of CDCl3 molecules in ethylcellulose/chloroform chiral nematic phases. The 2H spectra of both left-handed and right-handed mesophases, formed by ethylcellulose with degrees of substitution of 2·3 and 3·0 respectively, were examined as functions of temperature and concentration. The observed quadrupolar splittings are relatively large and the magnitudes of the order parameters of the solvent molecules show little correlation with the handedness of the chiral phases. However, the 2H line shapes of these two types of chiral phase exhibit rather different temperature dependences. Spectral simulations show that the observed line shapes and their temperature variations are mainly determined by diffusion of CDCl3 molecules along the pitch axis. The effects of centrifugation on the 2H spectra are also described.

We investigated whether adverse responses to highly active antiretroviral therapy (HAART) associated with late HIV presentation are secondary to low CD4 cell count per se or other confounding factors.A longitudinal analysis of the UK Collaborative HIV Cohort (CHIC) Study of individuals starting HAART in 1998-2007 was carried out, comparing late presenters (presenting/starting HAART at a CD4 count200 cells/μL) with late starters (presenting at a CD4 count350 cells/μL; starting HAART at a CD4 count200 cells/μL), using 'ideal starters' (presenting at a CD4 count350 cells/μL; starting HAART at a CD4 count of 200-350 cells/μL) as a comparator. Virological, immunological and clinical (new AIDS event/death) outcomes at 48 and 96 weeks were analysed, with the analysis being limited to those remaining on HAART for3 months.A total of 4978 of 9095 individuals starting first-line HAART with HIV RNA500 HIV-1 RNA copies/mL were included in the analysis: 2741 late presenters, 947 late starters and 1290 ideal starters. Late presenters were more commonly female, heterosexual and Black African. Most started nonnucleoside reverse transcriptase inhibitors (NNRTIs); 48-week virological suppression was similar in late presenters and starters (and marginally lower than in ideal starters); by week 96 differences were reduced and nonsignificant. The median CD4 cell count increase in late presenters was significantly lower than that in late starters (weeks 48 and 96). During year 1, new clinical events were more frequent for late presenters [odds ratio (OR) 2.04; 95% confidence interval (CI) 1.19-3.51; P=0.01]; by year 2, event rates were similar in all groups.Amongst patients who initiate, and remain on, HAART, late presentation is associated with lower rates of virological suppression, blunted CD4 cell count increases and more clinical events compared with late starters in year 1, but similar clinical and immunological outcomes by year 2 to those of both late and ideal starters. Differences between late presenters and late starters suggest that factors other than CD4 cell count alone may be driving adverse treatment outcomes in late-presenting individuals.

The crystal structure of adamantanecarboxylic acid, tricyclo[3.3.1.13,7] decan-1-carboxylic acid C10H15COOH, has been determined by X-ray diffraction at two temperatures, 173 and 280 K. At both tem...

The variable-temperature and -pressure vibrational spectra of the solid phases of quadricyclane have been measured. Factor group analysis has been used to predict possible space group symmetries of the ordered low-temperature phase, and the pressure dependences of the frequencies have been employed to make partial assignments of the vibrational modes. The order-disorder transition occurs at 9.3±0.5 kbar on compression and at about 7.0 kbar on decompression. The differences observed in the transition temperature, pressure, and entropy change for quadricyclane are compared with the data obtained for several other molecules with cycloheptyl skeletons

The Raman and infrared spectra of gas phase Re2O7 are reported. The experimental vibrational spectra of molecular Tc2O7 and Re2O7 are compared with calculated spectra. The results of these studies agree with a nonlinear M−O−M bridge for Tc2O7 and Re2O7. For infrared intensity calculations, the point charge approximation is used, while for the Raman calculations a combination of bond and atom polarizabilities is adopted. Pure Re2O7 was prepared from rhenium wire, but attempts to prepare it from rhenium powder and oxygen always led to infrared spectra showing serious contamination from a species containing an −OH linkage. Detailed experiments identified this molecule as HReO4, a unique transition metal analogue of the perhalic acids, and a partial infrared spectrum of this molecule is reported.

During erythrocyte invasion, Plasmodium falciparum merozoites use multiple receptor-ligand interactions in a series of coordinated events, but current knowledge of these interactions is limited. Using real-time imaging of invasion, we established that heparin-like molecules block early, and essential, events in erythrocyte invasion by merozoites. All P falciparum isolates tested, and parasites using different invasion pathways were inhibited to comparable levels. Furthermore, it was not possible to select for heparin-resistant parasites. Heparin-like molecules occur naturally on the surface of human erythrocytes, where they may act as receptors for binding of merozoite surface proteins. Consistent with this, we demonstrated that MSP1-42, a processed form of merozoite surface protein 1 (MSP1) involved in invasion, bound heparin in a specific manner; furthermore, binding was observed with the secondary processing fragment MSP1-33, but not MSP1-19. We defined key structural requirements of heparin-like molecules for invasion inhibition and interactions with MSP1-42. Optimal activity required a degree of sulfation more than or equal to 2, disulfation of the N-acetylglucosamine or hexuronic acid residue, and a minimum chain length of 6 monosaccharides. These findings have significant implications for understanding P falciparum invasion of erythrocytes and the development of novel therapeutics and vaccines.

The variable-temperature and -pressure vibrational spectra of the solid phases of quadricyclane have been measured. Factor group analysis has been used to predict possible space group symmetries of the ordered low-temperature phase, and the pressure dependences of the frequencies have been employed to make partial assignments of the vibrational modes. The order-disorder transition occurs at 9.3±0.5 kbar on compression and at about 7.0 kbar on decompression. The differences observed in the transition temperature, pressure, and entropy change for quadricyclane are compared with the data obtained for several other molecules with cycloheptyl skeletons

Variable-temperature and -pressure infrared and Raman spectra have been used to study the order-disorder phase transitions in norbornane (bicyclo[3.3.1]heptane, C 7 H 12 ). Three phases were observed, with the high entropy transition (phase II to phase III) occurring at 130 K and a smaller transition (between phases I and II) at 305 K on heating and 313 K on cooling. Under pressure the phase II to phase III transition occurred at 16 kbar

Infrared and Raman spectra of cyclooctanone (C 8 H 14 O) have been examined as a function of temperature. The presence of three solid phases was confirmed. The disordered phase (phase I) was found to supercool, but it did not form a «glassy crystal». The bands in the spectra of this phase were broad and featureless, indicating the existence of extensive disorder

The three solid phases of bicyclo [2.2.2] oct-2-ene were characterized by vibrational spectroscopy at low temperatures and high pressures. Bicyclooctene undergoes a phase transition at 176 K on cooling (phase I phase II) and then another at ca 95 K (phase II phase III). On compression at room temperature, these same transitions occur at 7.9 ± 1.0 kbar and ca. 15 kbar. The low-frequency Raman spectra show that phase I is isotropically disordered, whereas phase II is anisotropically disordered. The crystal structure of phase II is, however, similar to that of phase III, and is suggested to be tetragonal.

We examined the prevalence of hepatitis C virus (HCV) infection among HIV-positive individuals in the UK, trends in HCV testing and the impact of HCV on HIV treatment outcomes. Trends over time in HCV prevalence were calculated using each patient's most recent HCV status at the end of each calendar year. Logistic regression was used to identify factors associated with having a HCV antibody test, and Cox regression was used to determine whether HCV status was associated with the time to experiencing an immunological response to highly active antiretroviral treatment (HAART), time to virological response and viral rebound. Of the 31,765 HIV-positive individuals seen for care between January 1996 and September 2007, 20,365 (64.1%) individuals were tested for HCV, and 1807 (8.9%) had detectable HCV antibody. The proportion of patients in follow-up ever tested for HCV increased over time, from 782/8505 (9.2%) in 1996 to 14,280/17,872 (79.9%) in 2007. Nine thousand six hundred and sixty-nine individuals started HAART for the first time in or after January 2000, of whom, 396 (4.1%) were HCV positive. Presence of HCV infection did not affect initial virological response, virological rebound or immunological response. The cumulative prevalence of HCV in the UK CHIC Study is 8.9%. Despite UK guidelines, over 20% of HIV-positive individuals have not had their HCV status determined by 2007. HCV infection had no impact on HIV virological outcomes or immunological response to HIV treatment. The long-term impact on morbidity and mortality remain to be determined.

Apicomplexan parasites are responsible for a wide range of diseases in animals, including humans, in whom Plasmodium species cause the devastating disease malaria. Several recent discoveries now indicate that these intracellular parasites may use a conserved mechanism to infect their host cells by using parasite-encoded proteins as both parasite ligands and receptors anchored to the host cells.

The life cycle of the malaria parasite Plasmodium falciparum involves dramatic morphological and molecular changes required for infection of insect and mammalian hosts. Stage-specific gene expression is crucial, yet few nuclear factors, including potential epigenetic regulators, have been identified. Epigenetic mechanisms play an important role in the switched expression of members of species-specific gene families, which encode proteins exported into the cytoplasm and onto the surface of infected erythrocytes. This includes the large virulence-associated var gene family, in which monoallelic transcription of a single member and switching to other var genes leads to a display of different surface ligands with distinct antigenic and adhesive properties. Using a bio-informatic approach we identified 24 putative nuclear proteins. Tagging with sequences encoding GFP or haemagglutinin (HA) epitopes allowed for identification and localisation analysis of 12 nuclear proteins that are potential regulators of P. falciparum gene expression. These proteins specifically localise to distinct areas of the nucleus, reaching from the centre towards the nuclear envelope, giving new insights into the apicomplexan nuclear architecture. Proteins presenting a punctate distribution in the perinuclear sub-compartments are potential virulence gene regulators as silenced and active var genes reside at the nuclear periphery either clustered or in small expression sites, respectively. These analyses demonstrated an ordered compartmentalisation, indicating a complex sub-nuclear organisation that contributes to the complexity of transcriptional regulation in P. falciparum.

BACKGROUND: Storage of red blood cells (RBCs) is necessary for an adequate blood supply. However, reports have identified potential negative sequelae of transfusing stored RBCs. An animal model would be useful to investigate the pathophysiology of transfusing stored RBCs. However, it has been reported that storage of rat RBCs in CPDA-1 resulted in an unexpected sudden decline in posttransfusion survival. A mouse model of RBC storage and transfusion was developed to assess survival kinetics of mouse RBCs. STUDY DESIGN AND METHODS: RBCs expressing green fluorescent protein were collected in CPDA-1, filter leukoreduced, adjusted to a 75% hematocrit, and stored at 4°C. At weekly intervals, stored RBCs were transfused into C57BL/6 recipients. RBC survival was measured by flow cytometry and chromium-51 labeling. Phosphatidylserine externalization and CD47 expression was also evaluated. RESULTS: Mean 24-hour survivals of transfused RBCs were 99, 91, 64, 54, 30, and 18% after 0, 7, 14, 21, 28, and 35 days of storage, respectively. Stored RBCs showed an initial rapid clearance with subsequent extended survival. Increased surface phosphatidylserine and decreased CD47 expression were also observed. CONCLUSIONS: Mouse RBCs showed a progressive decline in survival, as a function of storage time, unlike the precipitous loss of viability reported for rat RBCs. Moreover, changes in the measured surface markers were analogous to trends reported for human RBCs. Together, these findings provide an initial characterization of a novel mouse model of RBC storage with the potential to serve as an experimental platform for studying the pathophysiologic consequences of transfusing stored RBCs.

Several hundred malaria parasite proteins are exported beyond an encasing vacuole and into the cytosol of the host erythrocyte, a process that is central to the virulence and viability of the causative Plasmodium species. The trafficking machinery responsible for this export is unknown. Here we identify in Plasmodium falciparum a translocon of exported proteins (PTEX), which is located in the vacuole membrane. The PTEX complex is ATP-powered, and comprises heat shock protein 101 (HSP101; a ClpA/B-like ATPase from the AAA+ superfamily, of a type commonly associated with protein translocons), a novel protein termed PTEX150 and a known parasite protein, exported protein 2 (EXP2). EXP2 is the potential channel, as it is the membrane-associated component of the core PTEX complex. Two other proteins, a new protein PTEX88 and thioredoxin 2 (TRX2), were also identified as PTEX components. As a common portal for numerous crucial processes, this translocon offers a new avenue for therapeutic intervention.

The introduction of plastids into different heterotrophic protists created lineages of algae that diversified explosively, proliferated in marine and freshwater environments, and radically altered the biosphere. The origins of these secondary plastids are usually inferred from the presence of additional plastid membranes. However, two examples provide unique snapshots of secondary-endosymbiosis-in-action, because they retain a vestige of the endosymbiont nucleus known as the nucleomorph. These are chlorarachniophytes and cryptomonads, which acquired their plastids from a green and red alga respectively. To allow comparisons between them, we have sequenced the nucleomorph genome from the chlorarachniophyte Bigelowiella natans : at a mere 373,000 bp and with only 331 genes, the smallest nuclear genome known and a model for extreme reduction. The genome is eukaryotic in nature, with three linear chromosomes containing densely packed genes with numerous overlaps. The genome is replete with 852 introns, but these are the smallest introns known, being only 18, 19, 20, or 21 nt in length. These pygmy introns are shown to be miniaturized versions of normal-sized introns present in the endosymbiont at the time of capture. Seventeen nucleomorph genes encode proteins that function in the plastid. The other nucleomorph genes are housekeeping entities, presumably underpinning maintenance and expression of these plastid proteins. Chlorarachniophyte plastids are thus serviced by three different genomes (plastid, nucleomorph, and host nucleus) requiring remarkable coordination and targeting. Although originating by two independent endosymbioses, chlorarachniophyte and cryptomonad nucleomorph genomes have converged upon remarkably similar architectures but differ in many molecular details that reflect two distinct trajectories to hypercompaction and reduction.

We consider a noncommutative version of the Davey-Stewartson equations and derive two families of quasideterminant solution via Darboux and binary Darboux transformations. These solutions can be verified by direct substitution. We then calculate the dromion solutions of the equations and obtain computer plots in a noncommutative setting., 23 pages, 6 figures