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We derive the Pfaffian analogues of the equations in the single-component KP hierarchies and the modified KP hierarchies and present an example of a system derived by reduction of some of the equations in these Pfaffianized hierarchies.

Drug discovery is a key part of malaria control and eradication strategies, and could benefit from sensitive and affordable assays to quantify parasite growth and to help identify the targets of potential anti-malarial compounds. Bioluminescence, achieved through expression of exogenous luciferases, is a powerful tool that has been applied in studies of several aspects of parasite biology and high throughput growth assays. We have expressed the new reporter NanoLuc (Nluc) luciferase in Plasmodium falciparum and showed it is at least 100 times brighter than the commonly used firefly luciferase. Nluc brightness was explored as a means to achieve a growth assay with higher sensitivity and lower cost. In addition we attempted to develop other screening assays that may help interrogate libraries of inhibitory compounds for their mechanism of action. To this end parasites were engineered to express Nluc in the cytoplasm, the parasitophorous vacuole that surrounds the intraerythrocytic parasite or exported to the red blood cell cytosol. As proof-of-concept, these parasites were used to develop functional screening assays for quantifying the effects of Brefeldin A, an inhibitor of protein secretion, and Furosemide, an inhibitor of new permeation pathways used by parasites to acquire plasma nutrients.

Synthesis and characterization of new complexes of 6-methylpyridine-2-carbaldehydethiosemicarbazone (Hmpytsc) and 6-methylpyridine-2-carbaldehyde-N(4)-phenylthiosemicarbazone (Hmpyptsc) with [VO2L], [Zn(HL)Cl2], [Ru(PPh3)2L2] and [MLCl] (M(II) = Pd, Pt; HL = Hmpytsc, Hmpyptsc) are reported. Their structures are discussed on the basis of IR, Raman, UV-vis, NMR (1H, 13C and 31P) and mass spectroscopic data, as well as elemental analysis and molar conductivity. In the X-ray crystal structure of the square-planar [Pd(mpyptsc)Cl]·DMSO, mpyptsc- is coordinated to Pd(II) in a tridentate manner through pyridyl N, azomethine N and thiol S, and the fourth coordination site is occupied by a chloride. A theoretical study on [Pd(mpyptsc)Cl]·DMSO was undertaken through DFT conformational analysis. The in vitro cytotoxic activity has been evaluated against human colon cancer (HCT116) and prostate cancer (DU145) cell lines. Hmpyptsc and [Zn(Hmpyptsc)Cl2] were most active with mean IC50 values of 3.32 and 2.60 (HCT116), and 3.60 and 3.10 (DU145) μM, respectively.

We use the procedure of Ohta and Hirota to generate an integrable, coupled system of discrete equations from the discrete KP equation.

In this study we have examined the behavior of the first-shell active site of metallolactamases as a function of water both bound directly as a zinc ligand and hydrogen bonded to protein-residue ligands in the active site and as a function of metal−metal distance. The inherent effective interaction energy of the bimetallic metallolactamase active site is relatively flat between the metal cations. This leaves the metal−metal distance susceptible to both perturbations from environmental interactions and protonation of active-site residues. Although the crystal structure of the active site of the zinc lactamase from Bacteroides fragilis is the initial starting point for the structure optimizations, structures very different from the equilibrium crystal structure as well as details of the water hydrogen-bonding pattern in the active site are obtained. Structures with Zn−Zn distances >4 A, with each metal cation acting as the center of a separate complex, result when only the crystallographic water that is dir...

By using the bilinear technique of soliton theory, a pfaffian version of the SU(2) self-dual Yang-Mills equation and its solution is constructed.

Arabinogalactan proteins (AGPs) are proteoglycans secreted by plant cells that have been implicated in plant growth and development. Most AGPs cloned to date possess highly labile glycosylphosphatidylinositol (GPI) lipid anchors. These anchors transiently attach AGPs to the plasma membrane before they are released into the cell wall following GPI anchor hydrolysis. We have isolated and partially sequenced the protein core of an AGP purified from styles of Nicotiana alata. The protein sequence data were utilised to clone the AGP's gene, NaAGP4. This AGP shares about 78% sequence identity with the tomato AGP LeAGP-1. RNA gel blot analyses of different plant organs indicate that NaAGP4 is expressed in the same tissues and at similar levels as LeAGP-1. Furthermore, NaAGP4 like LeAGP-1 is rapidly suppressed by tissue wounding and by pathogen infection. We believe NaAGP4 and LeAGP-1 are the first described examples of orthologous AGPs from different plant species. In contrast, another AGP from N. alata, NaAGP1, is comparatively unaffected by wounding and pathogen infection, although this AGP is expressed in similar tissues and at similar levels as NaAGP4.

Solid-state nuclear magnetic resonance and vibrational spectroscopic studies are reported for bis(pentacarbonylmanganese)diphenyltin(IV) and bis(pentacarbonylmanganese)diphenyllead(IV). The solid-state, CP-MAS, 119 Sn and 207 Pb NMR spectra of these complexes each reveal a single asymmetric undecet due to the 1 J 119 Sn‐ 55 Mn and 207 Pb‐ 55 Mn spin‐spin couplings and second-order quadrupole‐dipole effects. The 1 JSn‐Mn and 1 JPb,-Mn values are 139 ^ 1a nd 228^ 1H z; respectively. The 119 Sn and 207 Pb chemical shift anisotropies have been determined. The crystal structure of the tin compound has been re-examined. q 2001 Elsevier Science B.V. All rights reserved.

We use the bilinear method from soliton theory to produce a Pfaffian version of the Davey–Stewartson equations. The solutions of this new system of equations are Pfaffians.

Of all the proteins involved in prokaryotic cell division FtsZ is one of the earliest acting and most widely distributed, being found in all but a few species. We discuss several recent discoveries of FtsZ in eukaryotic cells and the protein's role in the division of chloroplasts and mitochondria, organelles that are of bacterial origin.

There has been growing interest in materials that exhibit negative thermal expansion properties [1]. The largest magnitudes described so far involve metal cyanide complexes such as Prussian Blue analogues in which metal atoms at the corners of cubes are linked by cyanide groups along the edges [2–4], and the interpenetrating tetrahedral (diamond-like) lattices of zinc, and cadmium cyanides [5–10]. Although the same atomic sequence M–C–N–M occurs in the cyanides of copper, silver, and gold, these compounds do not form a three-dimensional lattice but consist of infinite chains in the solid state [11–14]. Furthermore, the structure of copper cyanide is polymorphic with a low-temperature (LT-CuCN) form that transforms irreversibly to a second form (high-temperature; HT-CuCN) upon heating above 550 K. In LT-CuCN, the infinite chains are not linear and show a wave-like structure, whereas HT-CuCN is linear. The chain structures are disordered with respect to the carbon and nitrogen atom positions [15]. The negative thermal expansion arises from thermally activated transverse vibrations of the M–C–N–M groups, which increase in amplitude with increasing temperature leading to a decrease in the M...M distance. In chain systems, the transverse cyanide vibrational modes would shorten the unit cell in one direction and lengthen it in another, causing an anisotropic thermal expansion. In the case of HT-CuCN, the X-ray diffraction measurements of the trigonal unit cell dimensions as a function of temperature showed that a normal positive increase occurs along the a-axis and there is a small decrease along the c-axis of the unit cell [12]. A property of particular interest for negative thermal expansion materials is the mode Gruneisen parameter, ci, which represents the volume dependence of the mode frequency and can be written as B0d(ln(mi))/dP, where B0 is the bulk modulus. A negative value of a mode Gruneisen parameter is shown by a negative value of the pressure dependence of the vibrational frequency and this provides a method of determining which vibrational modes contribute to the negative thermal expansion.

Symptomatic malaria is caused by the infection of human red blood cells (RBCs) with Plasmodium parasites. The RBC is a peculiar environment for parasites to thrive in as they lack many of the normal cellular processes and resources present in other cells. Because of this, Plasmodium spp. have adapted to extensively remodel the host cell through the export of hundreds of proteins that have a range of functions, the best known of which are virulence-associated. Many exported parasite proteins are themselves involved in generating a novel trafficking system in the RBC that further promotes export. In this review we provide an overview of the parasite synthesized export machinery as well as recent developments in how different classes of exported proteins are recognized by this machinery.

Discrete counterparts to integrable systems such as the KP equation and the three-dimensional three wave interaction equations are obtained from bilinear identities which result from expanding typical solutions which appear in the form of Casorati and multi-Casorati determinants.

Münter et al. (2009) demonstrate that malaria parasite movement is highly complex, involving cycles of fast sprints and slow glides over their substrate. This “stick-and-slip shuffle” is controlled by the parasite's secreted adhesive proteins and their interaction with the dynamic actin cytoskeleton.

The FT-Raman spectra and the pressure dependence of the infrared spectra of the hydrated and anhydrous forms of dicalcium phosphate, CaHPO4 · 2H2O and CaHPO4, have been studied. The hydrated salt exhibits a phase transition at 21 kbar (1.0 kbar=0.1 Gpa) but no high pressure transition was observed for anhydrous dicalcium phosphate. The O–H stretching frequencies of the water molecules in CaHPO4 · 2H2O all showed negative pressure dependences and correlate with the O ⋯ O distances. The PO–H stretch increased with increasing pressure, indicating a strong hydrogen bond. The frequencies associated with the phosphate ion showed a normal pressure dependence.

The solid-state CP MAS (29Si, 119Sn, and 207Pb) NMR spectra of the triphenylsilyl-, triphenyltin-, and triphenyllead(pentacarbonyl)manganese(I) complexes, (Ph3E)Mn(CO)5 (E = Si, Sn, Pb), have been analyzed to give the chemical shifts, one-bond spin-spin coupling constants, 1JE-Mn, the "effective-dipolar" coupling constants (D - ΔJ/3), the chemical shift tensors, and the spin-spin anisotropy (ΔJ), where the analysis permits. For the tin and lead compounds, three and four sets of chemical shifts, respectively, were observed, and two different polymorphs occur for the lead complex, depending on the solvent used for recrystallization. The average values of the reduced coupling constants, 1KMn-Si (2.64 × 1020 T2 J-1), 1KSn-Mn (1.25 × 1020 T2 J-1), and 1KPb-Mn (4.18 × 1020 T2 J-1) showed a linear correlation with the s-electron densities at the respective metal nuclei. The principal components of the chemical shift tensors have been determined for the tin and lead compounds.Key words: manganese-group-14 compounds, solid-state 29Si, 119Sn, and 207Pb CP MAS NMR, spin-spin coupling, chemical shift anisotropy, quadrupole coupling.

This study clarifies the relationship between the active-site geometry of the bimetallic enzyme, zinc-β-lactamase, and the electronic spectra of the cobalt-substituted enzyme. Ab initio quantum methods were used to study both the structure and the spectroscopy of the active sites of metallo-β-lactamases. Theoretically optimized structures for the cobalt-substituted enzyme indicate that the coordination number of the two cobalt atoms remains the same as those of the zinc atoms in the crystal structure. Transition energies and intensities for the bimetallic active site were calculated by multiconfiguration self-consistent-field methods and identified with a metal center. The visible spectrum line positions and intensities calculated using correlation energy corrections derived from second-order perturbation calculations on model systems were in good agreement with the experimental data, demonstrating that the first shell of ligands determines the spectra. Visible transition energies are predicted at both me...

The (charged) free fermion formulation of the N -component KP hierarchies is used for the description of quadrilateral lattices in terms of multicomponent KP eigenfunction potentials. Tau functions for these hierarchies are explicitly calculated, giving rise to Grammian and Casorati determinant solutions to the (discretized) Darboux or Laplace equations describing the lattices. An example of localized tau functions and eigenfunction potentials is given.

Three new cage peroxides, 1,6-diaza-3,4,8,9-tetraoxabicyclo[4.4.2]dodecane (3a),1,6-diaza-3,4,8,9-tetraoxa-11-methylbicyclo[4.4.2]dodecane (3b), and 1,6-diaza-3,4,8,9-tetraoxatricyclo[4.4.2.411,12]hexadecane (4), have been prepared by reaction of 1,2-diaminoethane, 1,2-diaminopropane, and trans-1,2-diaminocyclohexane, respectively, with formaldehyde and hydrogen peroxide in aqueous acidic solution. Their structures have been established by X-ray diffraction, and show the bridgehead nitrogen atoms to be predominantly sp2 hybridized. The structures accord with 1H and 13C NMR spectra. Variable temperature NMR studies show that the diperoxide 3a begins to undergo rapid inversion (on the NMR time scale) at about 303 K; up to 370 K the diperoxides 3b and 4 show no conformational change.Key words: cage compounds, formaldehyde, peroxides, amine nitrogen, hybridization.

The vibrational spectra (Raman, photoacoustic and Fourier transform infrared and inelastic neutron scattering) of the calcium, strontium and europium salts of hexahydrido- and hexadeuteridoruthenate(II) have been analyzed. All observed fundamental modes and overtone and combination bands are assigned. Density functional theory calculations of the vibrational frequencies assist in the analysis.

Arabinogalactan-proteins are a class of hydroxyproline-rich proteoglycans implicated in plant growth and development. A major challenge is to establish how this structurally complex family of cell surface molecules regulates processes such as cell proliferation and somatic embryogenesis. The recent report that two `classical' arabinogalactan-proteins have a glycosylphosphatidylinositol-(GPI-)membrane anchor, offers a new framework for considering their mode of action. Drawing on knowledge from other eukaryotic systems (animals, yeast and parasitic protozoa), we suggest potential mechanisms for the involvement of GPI-membrane anchored arabinogalactan-proteins in signal transduction pathways.

Oxanorbornane (7-oxabicyclo[2.2.1]heptane, C6H10O) resembles other bicycloheptane-like molecules by exhibiting order-disorder transitions in the solid state. Differential scanning calorimetric studies show that five different phases may occur, with hysteresis in the transition temperatures. The vibrational spectra have been examined, and a factor group analysis of the vibrational splittings indicates that the crystal structure of the ordered phase has D2d symmetry. Activation energies for molecular motions were derived from proton spin-lattice relaxation time measurements.Key words: oxanorbornane, order-disorder, phase transitions.

The FT-infrared spectra of monocalcium monohydrate, Ca(H 2 PO 4 ) 2 ·H 2 O, have been measured as a function of pressure up to 50 kbar. A phase transition occurs at 18 kbar. The Lippincott–Schroeder model for the hydrogen bond has been used to explain the pressure dependence of the vibrational frequencies.

The 31P chemical shift tensor components and anisotropies of the trimethyl- and triphenylphosphine complexes of the group 6 metal pentacarbonyls, M(CO)5PR3 (M = Cr, Mo, W and R = Me, Ph), have been measured using solid-state CP-MAS 31P NMR spectroscopy. For the trimethylphosphine derivatives, the chemical shift tensors have near axial symmetry and the shift tensor components are in reasonable agreement with the calculated values for the chromium and molybdenum complexes. In the triphenylphosphine complexes, the tensors are asymmetric due to the different torsion angles of the phenyl rings. The trend to higher shielding of the isotropic 31P chemical shifts on descending group 6 arises from changes in the perpendicular components of the shift tensor. The one-bond coupling constants, 1J(95/97Mo-31P), for the trimethyl- and triphenylphosphine complexes are 129 and 133 Hz, respectively.Key words: chemical shift anisotropy, phosphines, chromium, molybdenum, tungsten.

The absorption spectrum of aqueous Co++ is reinterpreted in light of ab initio calculations. CAS-MCSCF and MCQDPT calculations yield the spectral states and their oscillator strengths, as well as the spin−orbit coupling between the quartet and doublet states of four-, five-, and six-coordinate Co++−water complexes. Spectral states and oscillator strengths are also computed for these complexes with one water replaced by a hydroxide ion. The results of the calculations are compared with measured spectra obtained from room temperature and high temperature Co++ solutions. A completely symmetric six-coordinate octahedral metal−water complex will have zero oscillator strength because of its symmetry. We find, moreover, that the calculated oscillator strength remains very small (≤10-6) even when the symmetry of this species is allowed to relax or when we distort the molecule asymmetrically. Therefore, the calculations suggest that the six-coordinate species can contribute little to the observed spectrum, even th...

We consider the three-dimensional three-wave resonance equation using a bilinear approach to investigate a broad class of solutions. Solutions are obtained in a Grammian form, and their relationship to Kaup's solutions examined.

The infrared spectrum of iron(II)-meso-tetraphenylporphyrinate (FeTPP(NO)) has been measured as a function of pressure up to 3.1 GPa. The N–O stretching frequency decreases with increasing pressure, as expected for the bonding model for nitric oxide bound to iron in porphyrin complexes. Other peaks in the spectrum show positive pressure dependence.

SUMMARY Chlorarachniophytes are amoeboid/flagellate eukaryotes that harbor reduced green algal endosymbionts. The carbohydrate stores of chlorarachniophyte algae have been investigated using methylation analysis to determine monosaccharide composition. An appreciable quantity of long chain β-1,3 glucan occurs in these algae. Immunogold electron microscopy using an antibody specific for (β-1,3 glucans localized (β-1,3 glucans within a vacuole in the host cell cytoplasm. The results suggest that photosynthate produced by the endosymbiont is stored by the host. Implications of the data for endosymbiosis are discussed.

Some examples of our recent research work on the effects of high external pressures on the infrared and Raman microspectra of inorganic molecular crystals are described. These high-pressure studies were performed with the aid of commercial diamondanvil cells. They have proved particularly useful in detecting pressure-induced structural changes in a variety of solid transitionmetal coordination and organometallic compounds, and in correctly assigning disputed vibrational modes.

Chlorarachniophytes are amoeboflagellate, marine protists that have acquired photosynthetic capacity by engulfing and retaining a green alga. These green algal endosymbionts are severely reduced, retaining only the chloroplast, nucleus, cytoplasm and plasma membrane. The vestigial nucleus of the endosymbiont, called the nucleomorph, contains only three small linear chromosomes and has a haploid genome size of just 380 kb--the smallest eukaryotic genome known. Initial characterisation of nucleomorph DNA has revealed that all chromosomes are capped with inverted repeats comprising a telomere and a single ribosomal RNA operon. The nucleomorph genome is the quintessence of compactness; average space between genes is a mere 65 bp,- some genes overlap, others are cotranscribed. Intense reductive pressures upon nucleomorph genes have apparently squeezed their spliceosomal-type introns down to only 18, 19 or 20 bases in length. Studies to date indicate the nucleomorph--essentially a stripped-down eukaryotic genome--encodes principally genetic housekeeping functions such as translation, transcription and sing.

A series of tertiary phosphine substituted alkyl- and acyltetracarbonylmanganese(I) complexes has been studied by cross-polarization and magic-angle-spinning (CP-MAS), 31P solid-state NMR spectrosc...

Although 2-hydroxyethylmethacrylate (HEMA) is commonly used for adhesive bonding to dentin, its role in promoting adhesion is not completely understood. Here, we use FT-Raman spectroscopy to elucidate further the nature of the interaction of HEMA with dentin. Ground dentin was exposed to 2.5% (w/w) nitric acid, washed, dried in air, and treated with HEMA. The samples were then sequentially washed with distilled water, with FT-Raman spectra being obtained after different wash times. Hydroxyapatite and bovine type I collagen were similarly treated with HEMA except for the acid exposure. The FT-Raman spectra of these samples were also recorded. The spectra of HEMA-treated, water-washed dentin and collagen revealed the following changes: (1) The band intensities of HEMA absorbed on dentin and collagen decreased with increasing wash times; (2) the v(C=O) and v(CCO) modes of HEMA at 1718 and 607 cm -1, respectively, either disappeared or decreased after extensive washing; (3) the v(C=C) (1640 cm-1) and δ(=CH2) (1403 cm -1) bands exhibited minor variations in band position and relative intensity. These results demonstrate that HEMA interacts with dentin both physically and chemically. The chemical interaction can be interpreted by either hydrogen bonding or the formation of a new bond to the ester group of HEMA.

The 31P chemical shift anisotropies have been measured at 293 K for the triphenylphosphine ligands in solid pentacarbonyl(triphenylphosphine)chromium(0), Cr(CO)5(PPh3) (1), and cis- and trans-tetra...

Malaria parasites are principally intracellular pathogens of erythrocytes and hepatocytes. For the parasites to grow rapidly and to avoid host immunity they must extensively modify their host cells by exporting hundreds of proteins into them. These exported proteins specifically help permeabilise the host cell so additional nutrients can be obtained and to avoid splenic clearance, the exported proteins modify the erythrocyte surface to promote cytoadherance within the microvasculature. Since erythrocytes lack many of the protein trafficking systems present in normal cells, parasites export their own. Many exported proteins help transport, traffic and refold other exported proteins into functional complexes once they reach their final destinations in the host. Exported trafficking systems and their cargoes are best understood in the most deadly human malaria pathogen Plasmodium falciparum, because it can be cultured in the laboratory. Trafficking and refolding require protein chaperone ATPases and we will present the latest data on exported chaperones. In particular, we will discuss the role of HSP101 in the protein translocon that provides a portal for protein export into the host compartment. Plasmodium species also export a few Hsp40s that probably function co-operatively with host Hsp70s. P. falciparum is however unique in that it exports also many additional Hsp40s as well as its own Hsp70-x and the roles of these will also be discussed.

Objectives We investigated whether age modified associations between markers of HIV progression, CD4 T lymphocyte count and HIV RNA viral load (VL), and the following markers of metabolic function: albumin, haemoglobin, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and total cholesterol (TC). Methods A retrospective analysis of data from the United Kingdom Collaborative HIV Cohort was carried out. Analyses were limited to antiretroviral-naïve subjects to focus on the impact of HIV disease itself. A total of 16670 subjects were included in the analysis. Multilevel linear regression models assessed associations between CD4 count/VL and each of the outcomes. Statistical tests for interactions assessed whether associations differed among age groups. Results After adjustment for gender and ethnicity, there was evidence that lower CD4 count and higher VL were associated with lower TC, LDL-C, haemoglobin and albumin concentrations but higher triglyceride concentrations. Age modified associations between CD4 count and albumin (P 50 years, a 50 cells/μL lower CD4 count correlated with a 2.4 [95% confidence interval (CI) 1.7–3.0], 3.6 (95% CI 3.2–4.0) and 5.1 (95% CI 4.0–6.1) g/L lower haemoglobin concentration and a 0.09 (95% CI 0.07–0.11), 0.12 (95% CI 0.11–0.13) and 0.16 (95% CI 0.13–0.19) g/L lower albumin concentration, respectively. Conclusions We present evidence that age modifies associations between CD4 count and plasma albumin and haemoglobin levels. A given reduction in CD4 count was associated with a greater reduction in haemoglobin and albumin concentrations among older people living with HIV. These findings increase our understanding of how the metabolic impact of HIV is influenced by age.

Plasmodium parasites remodel their vertebrate host cells by translocating hundreds of proteins across an encasing membrane into the host cell cytosol via a putative export machinery termed PTEX. Previously PTEX150, HSP101 and EXP2 have been shown to be bona fide members of PTEX. Here we validate that PTEX88 and TRX2 are also genuine members of PTEX and provide evidence that expression of PTEX components are also expressed in early gametocytes, mosquito and liver stages, consistent with observations that protein export is not restricted to asexual stages. Although amenable to genetic tagging, HSP101, PTEX150, EXP2 and PTEX88 could not be genetically deleted in Plasmodium berghei, in keeping with the obligatory role this complex is postulated to have in maintaining normal blood-stage growth. In contrast, the putative thioredoxin-like protein TRX2 could be deleted, with knockout parasites displaying reduced grow-rates, both in vivo and in vitro, and reduced capacity to cause severe disease in a cerebral malaria model. Thus, while not essential for parasite survival, TRX2 may help to optimize PTEX activity. Importantly, the generation of TRX2 knockout parasites that display altered phenotypes provides a much-needed tool to dissect PTEX function.

Export of proteins into the infected erythrocyte is critical for malaria parasite survival. The majority of effector proteins are thought to export via a proteinaceous translocon, resident in the parasitophorous vacuole membrane surrounding the parasite. Identification of the Plasmodium translocon of exported proteins and its biochemical association with exported proteins suggests it performs this role. Direct evidence for this, however, is lacking. Here using viable purified Plasmodium falciparum merozoites and three-dimensional structured illumination microscopy, we investigate remodelling events immediately following parasite invasion. We show that multiple complexes of the Plasmodium translocon of exported proteins localize together in foci that dynamically change in clustering behaviour. Furthermore, we provide conclusive evidence of spatial association between exported proteins and exported protein 2, a core component of the Plasmodium translocon of exported proteins, during native conditions and upon generation of translocation intermediates. These data provide the most direct cellular evidence to date that protein export occurs at regions of the parasitophorous vacuole membrane housing the Plasmodium translocon of exported proteins complex., During red blood cell infection, malaria parasites export hundreds of proteins that remodel the host cell surface. Cowman and colleagues identify a putative protein translocator complex spatially associated with exported proteins, revealing the cellular domains involved in protein export.

Nuclear and nucleomorph 18S ribosomal RNA genes from six cryptomonads were amplified by the polymerase chain reaction and sequenced. Phylogenetic trees were constructed by distance, parsimony, and maximum likelihood methods for all available cryptomonad nuclear and nucleomorph 18S rRNA sequences. Nuclear and nucleomorph trees are largely congruent and clearly disprove the idea of polyphyletic origins for cryptomonad chloroplasts. Both show the leucoplast-containing Chilomonas as the sister to all photosynthetic cryptomonads. Using 11 cryptomonad nucleomorph sequences gives more convincing evidence than before that cryptomonad nucleomorphs originated from a red alga and are not specifically related to Chlorarachnion nucleomorphs. Both trees show as a clade the genera with nucleomorphs embedded in a chloroplast-envelope invagination into the pyrenoid (Storeatula, Rhinomonas, Rhodomonas). This monophyly of embedded nucleomorphs supports the recent creation of the order Pyrenomonadales for such cryptomonads. ...

The pressure dependence of the infrared spectra (600–1800, 2500–3600 cm −1 ) has been measured for 1,4-benzoquinone(2,5-cyclohexadiene-1,4-dione) and fluoranil (2,3,5,6-tetrafluoro-2,5-cyclohexadiene-1,4-dione). No phase changes occur in either compound over the pressure range from ambient pressure to 50 kbar in benzoquinone and to 40 kbar in fluoranil. The pressure dependence of the C-H stretching frequencies in benzoquinone appear to be normal but the CC and CO stretching modes show a much higher dependence on pressure in fluoranil than in benzoquinone.

A generic formula is presented which relates the Hirota D-operators to simple combinatorics. Particular classes of partition polynomials (Bell-polynomials and generalizations) are found to play an important role in the characterization of bilinearizable equations. As a consequence it is shown that bilinear Backlund transformations for single-field bilinearizable equations linearize systematically into corresponding Laxpairs.

Infrared and Raman spectra of the principal mineral component of human hard tissue, calcium hydroxyapatite, Ca10(PO4)6(OH)2, or HAP, and the analogous calcium fluoroapatite, Ca10(PO4)6F2, or FAP, have been recorded, using a diamond-anvil cell, at pressures ranging from ambient to 30 kbar. For FAP, the absence of any discontinuities in the slopes of the nu (cm-1) versus P (kbar) plots for the observed bands indicates that no pressure-induced structural transition occurs in this material throughout the pressure range investigated. For the internal vibrational modes of HAP, however, there are distinct breaks at approximately 20 kbar in the nu versus P plots, suggesting the occurrence of a structural change at this pressure. The OH stretching mode of HAP shifts to higher wave numbers with increasing pressure while the associated OH librational mode shifts in the opposite direction. The pressure-induced structural transition in HAP is reversible and occurs at approximately 22 kbar upon decompression. Further evidence for a structural change taking place at approximately 20 kbar was provided by a parallel pressure-tuning Raman study. Hydrogen bonding does not occur, or is very weak, in HAP.

Variable-temperature and variable-pressure effects on the vibrational spectra of solid tropolone (C 7 H 6 O 2 ) have been studied using infrared and Raman spectroscopy. At ambient pressure, no temperature-induced phase transitions were found to take place over a temperature range from about 50 to 295 K. Application of external pressure favours the formation of a new hydrogen bond, as a new O-H stretching band appears in the spectrum above a pressure of 6 kbar and increases in intensity with further increase in pressure.

New compounds, based on the interpenetrating double layers found in oxo-vanadium (IV) formate monohydrate, VO(HCO2)2 · H2O, have been synthesized. Ligand water is replaced by formic acid in VO(HCO2)2 · HCO2H, or by interlayer bridging fluoride with additional (NH4 or K) cations in [VO(HCO2)2]2 · NH4F · NH4OH, [VO(HCO2)2]2 · KF · NH4OH, and [VO(HCO2)2]2 · KF · 1 2 KOH. Indexed XRPD for the layer compounds and vibrational (IR and Raman) data including those for the related chain polymer K2VO(HCO2)2 are given. Parallels are drawn with the lamellar phase vanadyl phosphates and arsenates.

A class of fully nonlinear third-order partial differential equations (PDES) is considered. This class contains several examples which have recently appeared in the literature and for which rather unusual travelling-wave solutions have been given. These solutions consist essentially of sums of exponentials; we trace the occurrence of these exponentials back to the existence of a linear subequation which appears as a factor in the travelling-wave reduction. In addition, we consider the Painleve analysis of this set of equations, both for the original PDE and also for reductions to ordinary differential equations (ODES). No equation in the class considered survives the combination of PDE and ODE tests. Also, an equation in the class considered which is known to be integrable is shown to possess only the weak Painleve property. Our analysis, therefore, confirms the limitations of the Painleve test as a test for complete integrability when applied to fully nonlinear PDES.