Cytogenetic,cross-mating and molecular evidence of four cytological races of Anopheles crawfordi (Diptera: Culicidae) in Thailand and Cambodia

Twenty-nine isolines of Anopheles crawfordi were established from wild-caught females collected from cow-baited traps in Thailand and Cambodia. Three types of X (X₁, X₂, X₃) and four types of Y (Y₁, Y₂, Y₃, and Y₄) chromosomes were identified, according to differing amounts of extra heterochromatin. These sex chromosomes represent four metaphase karyotypes, i.e., Forms A (X₁, X₂, X₃, Y₁), B (X₁, X₂, X₃, Y₂), C (X₂, Y₃) and D (X₂, Y₄). Forms C and D are novel metaphase karyotypes confined to Thailand, whereas forms A and B appear to be common in both Thailand and Cambodia. Cross-mating experiments between the four karyotypic forms indicated genetic compatibility in yielding viable progenies and synaptic salivary gland polytene chromosomes. The results suggest that the forms are conspecific and A. crawfordi comprises four cytological races, which is further supported by very low intraspecific variation (mean genetic distance = 0.000–0.018) of the nucleotide sequences in ribosomal DNA (ITS2) and mitochondrial DNA sequences (COI, COII).     

Die Cytogenetik zweier norddeutscher Populationen von Nosopsyllus fasciatus Bosc (Aphaniptera)

Specimens of the populations Hamburg and Wilhelmshaven of the ratflea N. fasciatus exhibit variation of the chromosome number in the range of 2n=20–23 and 2n=20–27 respectively, resulting from individual differences in the number of supernumerary chromosomes beyond the basic chromosome complement of 2n=20. The supernumerary chromosomes are mostly euchromatic and partly or completely homologous to each other and to the 10. pair of the basic complement. The numerical variation in the population Wilhelmshaven is produced by recurrent mitotic non-disjunction of the supernumerary chromosomes in anaphase II of spermatogenesis. Constant mitotic non-disjunction and preferential segregation of the supernumerary chromosomes towards the pronucleus leads to their accumulation in the population.—A multiple sex-chromosome mechanism of the type X₁ X₂ Y₁ Y₂ (male): X₁ X₁ X₂ X₂ (female) has been demonstrated for the population Wilhelmshaven of N. fasciatus. The X₁ X₂ Y₁ Y₂-chain of four is restricted to the male meiosis, in oogenesis two sex bivalents (X₁ X₁ and X₂ X₂) are formed. — The cytogenetic data presented do not support the concept of a closer phylogenetic relationship between the Aphaniptera and Nematocera, but do not preclude the possibility of a kinship of Aphaniptera and Neomecoptera.     

Cytogenetic,hybridization and molecular evidence of four cytological forms of Anopheles nigerrimus (Hyrcanus Group) in Thailand and Cambodia

Thirteen isoline colonies of Anopheles nigerrimus were established from individual wild‐caught females collected from cow‐baited traps at locations in Thailand and Cambodia. Three types of X (X₁, X₂, X₃) and 4 types of Y (Y₁, Y₂, Y₃, Y₄) chromosomes were recovered, according to differing amounts of extra heterochromatin. Four karyotypic forms were designed depending upon apparently distinct figures of X and Y chromosomes, i.e., Form A (X₁, X₂, X₃, Y₁), B (X₂, X₃, Y₂), C (X₁, Y₃), and D (X₃, Y₄). Forms C and D were new metaphase karyotypes discovered in this study. Form A appeared to be common in both Thailand and Cambodia. Forms B and D were found to be rather specific to southern and northeastern Thailand, respectively, whereas Form C was confined to Cambodia. Hybridization experiments among the eight isoline colonies, which were representative of four karyotypic forms of An. nigerrimus, demonstrated genetic compatibility in giving viable progenies and synaptic salivary gland polytene chromosomes through F₂‐generations. These results elucidated the conspecific relationship, comprising four cytological forms within this taxon. Supportive evidence was confirmed further by very low intraspecific sequence variations (average genetic distance = 0.002–0.007) of the nucleotide sequences in ribosomal DNA [second internal transcribed spacer (ITS2)] and mitochondrial DNA [cytochrome c oxidase subunit I (COI) and subunit II (COII)].     

Platinum(II) complexes of methyl-substituted xanthines: crystal structures of K[Pt(theobromine)Cl3]·H2O,trans-[ Pt(isocaffeine)2Cl2]·H2O and K(isocaffeinium)[PtCl4]·H2O

The preparations of Pt(theophylline)₂Cl₂, K[Pt- (theophylline)Cl₃], K[Pt(theobromine)Cl₃]·H₂O (1), trans-[Pt(isocaffeine)₂Cl₂]·H₂O (2), and K(isocaffeinium)[PtCl₄]·H₂O (3) are reported.Crystals of 1 are monoclinic P2₁/n with a=7.641- (2), b=11.873(3), c=15.868(4) Å, β=90.80(2)°, Z=4. The structure was refined on 1443 reflections to R=0.028. In the planar [Pt(theobromine)Cl₃]⁻ anion Pt-N(9)=2.016(6) Å, Pt-Cl=2.299(2), 2.289(2), and 2.303(2) Å. The imidazole ring is rotated away from the coordination plane by 79.8°. Symmetry related theobromine units pack parallel to each other with a mean inter-ring separation of 3.27 Å.Crystals of 2 are monoclinic P2₁/a with a=7.345- (2), b=20.021(5), c=8.031(2) Å, β=104.18(2)°, Z=2. The structure was refined on 1132 reflections to R=0.029. The Pt-N(7) distance is 2.003(3) Å and Pt-Cl=2.298(1) Å. The imidazole ring is rotated away from the PtCl₂N₂ plane by 76.8°. In this compound, the isocaffeine units do not stack, but form a staggered arrangement within the unit cell.Crystals of 3 are monoclinic P₁/c with a= 7.382- (1), b=14.014(4), c=15.757(4) », β=92.30(2)°, Z=4. The structure was refined on 2057 reflections to R=0.032. The isocaffeine is protonated at N(7). The Pt-Cl distances in the PtCl₄²⁻ anion range between 2.29–2.31 Å. The protonated isocaffeine cations and the PtCl₄²⁻ anions form a very nearly parallel infinitely stacked arrangement with minimum interlayer atomic separations of 3.37 and 3.44 Å.     

Rheological behaviour of high density continuous cultures of Saccharomyces cerevisiae

By culture of Saccharomyces cerevisiae with cell recycle using tangential microfiltration, high cell concentrations are obtained (in the range of 0 to 345 gl⁻¹ dry-weight). The rheological properties of the cell suspension during the cell growth were studied. Over a wide range of biomass concentration (X<275 gl⁻¹D.W.) the power-law model was found adequate to describe the rheological behaviour of the broth. Pronounced non-Newtonian (pseudoplastic) behaviour occurred for X > 75 gl⁻¹. Experimental correlations for apparent viscosity (n_a, mPa.s) and power-law index vs. biomass concentration (X, gl⁻¹) were established: n_a = (1+0.012X)² suitable over the whole range of concentration up to 275 gl⁻¹ D.W. n_a = 1+0.04X in the low concentration range; X<100 gl⁻¹D.W. Beyond the cell concentration of 275 gl⁻¹ D.W. the viscosity increases suddenly.     

Stability trends and fragmentation patterns of gaseous yttrium oxide clusters studied by fast atom bombardment tandem mass spectrometry

The fragmentation patterns of yttrium oxide cluster species YO⁺, Y₂O₂⁺, Y₂O₃⁺, Y₃O₄⁺, Y₄O₆⁺, Y₅O₇⁺, Y₆O₈⁺ and Y₇O₁₀⁺ were investigated at collision energies 30–110 and 170 eV by fast atom bombardment tandem mass spectrometry. The collision activated dissociation (CAD) spectra obtained revealed higher thermodynamic stability for the clusters of general formula Y_αO_(3α−1)/2⁺, where a is an odd number (e.g. YO⁺, Y₃O₄⁺, Y₅O₇⁺, Y₇O₁₀⁺) which are also the preferred CAD products for all oxide clusters studied. These most stable oxides are constituted by trivalent yttrium only whereas those containing formally tetravalent yttrium Y_aO_3a/2⁺, (where a is even) e.g. Y₂O₃⁺ and Y₄O₆⁺, are extremely unstable. The clusters Y_aO_(3a−2)/2⁺, (where a is even) containing divalent yttrium, e.g. Y₂O₂⁺ and Y₆O₈⁺, have considerable stability but their CAD products are again the thermodynamic products Y_aO_(3a−1)/2⁺. Electronic structures appear to have overriding significance in determining the thermo- dynamic stabilities of the oxide cluster species.     

Evaluation of the Fermi equation as a model of dose-response curves

 When plotted in linear coordinates, the dose-response curves of microorganisms exposed to a lethal agent, such as radiation or a toxic substance, often have a characteristic sigmoid shape. Irrespective of whether they are very narrow or broad they can be described by the Fermi function, which is a mirror image of the logistic function, i.e. S(X)=1/{1+ exp [(X−X _c)/a]} where S(X) is the fraction of the surviving organisms, X the dose of the lethal agent, X _c a characteristic dose marking the inflection point of S(X), which corresponds to 50% mortality, and a a measure of the steepness of the survival curve around X _c. It is demonstrated that, if the susceptibilities of the individual organisms, expressed in terms of a characteristic lethal dose, have a symmetric unimodal distribution, the dose-response curve of the population has a Fermian sigmoid shape. It is also shown that the mode and variance of the distribution can be estimated from the shape parameters of the Fermian survival curve, X _c and a. Received: 7 November 1995 / Received last revision: 11 April 1996 / Accepted: 29 April 1996     

Synthesis and structure–activity relationships of novel,substituted 5,6-dihydrodibenzo[a,g]quinolizinium P2X7 antagonists

Iminium quaternary protoberberine alkaloids (QPA) have been found to be novel P2X₇ antagonists. To assess their structure–activity relationships, these compounds were modified at their R¹ and R² groups and assayed for their ability to inhibit the 2′(3′)-O-(4-benzoylbenzoyl)-ATP (BzATP)-induced uptake of fluorescent ethidium by HEK-293 cells stably expressing the human P2X₇ receptor, and their ability to inhibit BzATP-induced IL-1β release by differentiated THP-1 cells. Compounds 15a and 15d, with alkyl groups at the R¹ position, and especially compound 19h, with the 2-NO₂-4,5-dimethoxy-benzyl group at the R² position, had potent inhibitory efficacy as P2X₇ antagonists.     

Evaluation of enantioselectivity in lipase-catalyzed acylation of hydroxyalkylphosphine oxides

The lipase-catalyzed optical resolution of 2-, 3-, and 5-hydroxyalkyl phosphorus compounds 1 provided the corresponding optically pure diastereomers in good yields. (S_P, R)- and (R_P, S)-1 were acylated faster than (S_P, S)- and (R_P, R)-1. The stereoselectivity at the phosphorus atom changed with the flexibility of the active sites in the lipases. The stereoselectivity at the phosphorus atom was higher in the reaction of 1a than in the reaction of 1b,c. The reaction rate of ɛ-hydroxyalkylphosphine oxide 1c was faster than that of 1a, although less enantioselectivity was observed at the phosphorus atom.     

The preparation and structure of tris[bis(pyrazolyl)borate]indium(III)

The compound In[(pz)₂BH₂]₃ (pz = 1-pyrazolyl, C₃H₃N₂⁻) was prepared from In(NO³)₃ and K[(pz)₂-BH₂] in water, and characterised by spectroscopic and X-ray methods. Crystals are orthorhombic,Pna2₁,a = 20.279(4),b = 8.884(2),c = 13.411(2)Å;R = 0.0285. Individual molecules contain a near-regular six-coordinate indium atom with In–N (av.) 2.241(5)Å. The pyrazolyl borate ligands are puckered, with dihedral angles between the two rings of each ligand in the range 133–144°.     

Effects of shell morphological traits on the weight trait of the orange strain of the Manila clam

A new strain of Manila clam with orange shell color was produced after selection within a full-sib family for two generations. In the present study, the shell length, height, and width, and the live body weight of the orange strain were measured, and their correlation coefficients were calculated. The shell morphological traits were used as independent variables, and the live body weight was used as the dependent variable for calculating the path coefficients, correlation index, and determination coefficients. The results showed that the correlation coefficients between each shell morphological trait and the live body weight were all highly significant (P < 0.01). The correlation indices (R²) of morphological traits against the live body weight of clams were larger than 0.85, indicating that the morphology traits were the main factors affecting the body weight. Multiple regression equations were obtained to estimate shell length X₁ (cm), shell height X₂ (cm), and shell width X₃ (cm) against live body weight Y (g): Y = ? 2.62 + 0.34 X₁ + 0.145 X₂, (X₁ < 0.05, X₂ < 0.05). The results suggest that the shell length could be used as the main trait for selective breeding and could indirectly make a large improvement in the weight trait.     

Backscattering of gyrotron radiation and short-wavelength turbulence during electron cyclotron resonance plasma heating in the L-2M stellarator

Backscattering of gyrotron radiation (θ = π) by short-wavelength density fluctuations (k _⊥ = 30 cm^?1) in the plasma of the L-2M stellarator was studied under conditions of electron cyclotron resonance (ECR) plasma heating at the second harmonic of the electron gyrofrequency (75 GHz). The scattering of the O-wave emerging due to the splitting of the linearly polarized gyrotron radiation into the X- and O-waves was analyzed. The signal obtained after homodyne detection of scattered radiation is a result of interference of the reference signal, the quasi-steady component, and the fast oscillating component. The coefficients of reflection of the quasi-steady component, R ₌ ² (Y), and fast oscillating component, R _～ ² (Y), of scattered radiation are estimated. The growth of the R _～ ² (Y) coefficient from 3.7 × 10^?4 to 5.2 × 10^?4 with increasing ECR heating power from 190 to 430 kW is found to correlate with the decrease in the energy lifetime from 1.9 to 1.46 ms. The relative density of short-wavelength fluctuations is estimated to be 〈n _～ ² 〉/〈n _e ² 〉 = 3 × 10^?7. It is shown that the frequencies of short-wavelength fluctuations are in the range 10–150 kHz. The recorded short-wavelength fluctuations can be interpreted as structural turbulence, the energy of which comprises ～10% of the total fluctuations energy. Simulations of transport processes show that neoclassical heat fluxes are much smaller than anomalous ones. It is suggested that short-wavelength turbulence plays a decisive role in the anomalous heat transport.     

Heme-heme interaction in cytochrome c oxidase: the cooperativity of the hemes of cytochrome c oxidase as evidenced in the reaction with CO

Isolated and purified cytochrome c oxidase from beef heart muscle mitochondria (Kuboyama et al. (1972) J. Biol. Chem.247, 6375–6383) is shown to be very similar to the hemoprotein in situ with respect to its EPR absorption properties and the half-reduction potentials of the hemes and copper. The half-reduction potentials of cytochromes a and a₃ in the purified cytochrome c oxidase are 205 mV and 360 mV, respectively, and these values are the same in the presence and absence of cytochrome c.Low-temperature EPR spectra show that the binding of CO to reduced cytochrome a₃ changes the oxidized cytochrome a from high spin (g 6) to low spin (g 3). In samples at 5–8 °K the photodissociation of the reduced cytochrome a₃CO compound shifts the spectrum of the oxidized low-spin cytochrome a to a lower g value and converts approximately 5% of the low-spin form to a high-spin form. The heme-heme interaction demonstrated in this reaction is very fast as evidenced by the fact that even at 5 °K the measured change in oxidized cytochrome is complete within 5 msec.     

Probability density functions for axial ratios of sectioning profiles of anisotropically arranged elliptical microvessels

The article theoretically regards probability density functions (PDFs) for axial ratio (X/Y) of sectioning profiles of elliptical microvessels (MVs) arranged with anisotropy in a biological tissue volume. A technique for the PDF_X/Y calculations in anisotropy of the elliptical MVs is described. The essence of this technique is introducing anisotropy in PDF(α,φ), i.e. the function of the joint distribution of the polar and planar angles α and φ, which define mutual orientation of the elliptical MVs and sectioning planes. With the aid of this technique, the anisotropy cases are studied with PDF(α,φ) given by pair combinations of the following distributions: (i) a uniform distribution of the angles α and/or φ, (ii) the angle α distribution with , and (iii) Gaussian distributions of the α or φ values. Specifically, PDF_X/Y curves are obtained for MVs with the true, or three-dimensional, axial ratio X₀/Y₀=2.0, and the anisotropy effects on the X/Y expected frequencies are analysed. Conclusions of this analysis, the PDF_X/Y calculation technique, and the PDF_X/Y curves obtained are useful for stereological reconstruction of anisotropically organised microcirculatory networks, with an ellipticity of their MVs being taken into consideration.     

Drug-like property-driven optimization of 4-substituted 1,5-diarylanilines as potent HIV-1 non-nucleoside reverse transcriptase inhibitors against rilpivirine-resistant mutant virus

On the basis of our prior structure-activity relationship (SAR) results, our current lead optimization of 1,5-diarylanilines (DAANs) focused on the 4-substituent (R¹) on the central phenyl ring as a modifiable position related simultaneously to improved drug resistance profiles and drug-like properties. Newly synthesized p-cyanovinyl-DAANs (8a–8g) with different R¹ side chains plus prior active p-cyanoethyl-DAANs (4a–4c) were evaluated not only for anti-HIV potency against both wild-type HIV virus and rilpivirine-resistant (E138K, E138K+M184I) viral replication, but also for multiple drug-like properties, including aqueous solubility, lipophilicity, and metabolic stability in human liver microsomes and human plasma. This study revealed that both ester and amide R¹ substituents led to low nanomolar anti-HIV potency against wild-type and rilpivirine-resistant viral strains (E138K-resistance fold changes < 3). The N-substituted amide-R¹ side chains were superior to ester-R¹ likely due to improved aqueous solubility, lipophilicity, and higher metabolic stability in vitro. Thus, three amide-DAANs 8e, 4a, and 4b were identified with high potency against wild-type and rilpivirine-resistant viral strains and multiple desirable drug-like properties.     

Binuclear copper(II) complexes of tetradentate (Ne) diazine ligands. Crystal structures of [μ-1,4-Bis(4,6-dimethyl-2-pyridylamino)phthalazine-N,μ-N3,μN3,N]-(μ-Dichloro)dichlorodicopper(II), [μ-3,6-Bis(2-pyridylthio)pyridazine-N,μ-N1,μ-N2,N] (μ-dichloro)dichlorodicopper(II) ethanol,and 3,6-Bis(2-pyridylthio)-pyridazine

The X-ray structures of two binuclear copper(II) chloride complexes of the tetradentate ligands 1,4- bis(4,6-dimethyl-2-pyridylamino)phthalazine (PAP46Me) and 3,6-bis(2-pyridylthio)pyridazine are reported. [Cu₂(PAP46Me)Cl₄] (1) and [Cu₂(PTP)Cl₄]· CH₃CH₂OH (2) contain triply bridged binuclear centres involving a diazine (NN) and two chlorobridges with copper-copper separations in the fange 3.19–3.25 Å and distorted square pyramidal copper stereochemistry. The reduced room temperature magnetic moments indicate antiferromagnetically coupled binuclear copper(II) centres.Complex 1 forms green crystals with a= 15.795(3), b=10.661(3), c=16.155(4) Å, β= 113.82(3)°, C2/c, Z = 4, R_f=0.031. Complex (2) forms green crystals with a=33.9022(8), b= 9.1626(5), c= 15.7885(5) Å,β= 114.853(2)°, C2/c, Z=8, R_f=0.047. The structure of the ligand PTP is also reported and compared with that of 2.     

Comparison of Energy and Growth Yields for Desulfitobacterium dehalogenans during Utilization of Chlorophenol and Various Traditional Electron Acceptors

Desulfitobacterium dehalogenans grew with formate as the electron donor and 3-chloro-4-hydroxyphenylacetate (3-Cl-4-OHPA) as the electron acceptor, yielding Y_X/formate, Y_X/2e⁻, and Y_X/ATP ranging from 3.2 to 11.3 g of biomass (dry weight)/mol, thus indicating that energy was conserved through reductive dechlorination. Pyruvate was utilized as the electron donor and acceptor, yielding stoichiometric amounts of acetate and lactate, respectively, and a Y_{X/reduced acceptor} of 13.0 g of biomass (dry weight)/mol. The supplementation of pyruvate-containing medium with additional electron acceptors, such as 3-Cl-4-OHPA, nitrate, fumarate, or sulfite, caused pyruvate to be replaced as the electron acceptor and nearly doubled the Y_X/ATP (Y_{X/acetate formed}). A comparison of the yields for 3-Cl-4-OHPA with those for other traditional electron acceptors indicates that the dehalogenation reaction led to the formation of similar amounts of energy equivalents. The various electron acceptors were used concomitantly with 3-Cl-4-OHPA in nonacclimated cultures, but the utilization rates and amounts utilized differed.     

Advantages of fungal enzyme production in solid state over liquid fermentation systems

The present paper attempts to explain why enzyme production in solid-state fermentation (SSF) is higher than in submerged fermentation (SmF). Recent work done in our laboratory [Biotechnol. Lett. 22 (2000) 1255; J. Ind. Microbiol. Biotechnol. 26 (5) (2001) 271; J. Ind. Microbiol. Biotechnol. 26 (5) (2001) 296] related to the production of invertase, pectinases and tannases, by Aspergillus niger grown by SSF and SmF is reviewed. To do such a comparative study, logistic and Luedeking–Piret equations are used in order to estimate the values of the following coefficients: maximal specific growth rate (μ_M), maximal biomass level (X_M), enzyme/biomass yield (Y_P/X) and secondary rate of production, or breakdown (k). It is shown that enzyme productivity is proportional to group, μ_MY_P/XX_M, corrected by a function of ν=k/Y_P/Xμ_M. In all three cases of enzyme production studied, productivity using a SSF system was higher than in SmF. Studies with invertase resulted in higher values of μ_MX_M. Studies with pectinases resulted in higher values of Y_P/XX_M. Studies with tannases resulted in higher Y_P/X and less negative values of k. Finally, a reaction–diffusion model is presented to try to explain such differences based on micrographic measurements of mycelial aggregates for each kind of fermentation system.     

New structure–activity relationship studies in a series of N,N-bis(cyclohexanol)amine aryl esters as potent reversers of P-glycoprotein-mediated multidrug resistance (MDR)

As a continuation of previous research on a new series of potent and efficacious P-gp-dependent multidrug resistant (MDR) reversers with a N,N-bis(cyclohexanol)amine scaffold, we have designed and synthesized several analogs by modulation of the two aromatic moieties linked through ester functions to the N,N-bis(cyclohexanol)amine, aiming to optimize activity and to extend structure–activity relationships (SAR) within the series. This scaffold, when esterified with two different aromatic carboxylic acids, gives origin to four geometric isomers (cis/trans, trans/trans, cis/cis and trans/cis).The new compounds were tested on doxorubicin-resistant erythroleukemia K562 cells (K562/DOX) in the pirarubicin uptake assay. Most of them resulted in being potent modulators of the extrusion pump P-gp, showing potency values ([I]_0.5) in the submicromolar and nanomolar range. Of these, compounds 2b, 2c, 3d, 5a–d and 6d, showed excellent efficacy with a α_max close to 1. Selected compounds (2d, 3a, 3b, 5a–d) were further studied to evaluate their doxorubicin cytotoxicity potentiation (RF) on doxorubicin-resistant erythroleukemia K562 cells and were found able to enhance significantly doxorubicin cytotoxicity on K562/DOX cells.The results of both pirarubicin uptake and the cytotoxicity assay, indicate that the new compounds of the series are potent P-gp-mediated MDR reversers. They present a structure with a mix of flexible and rigid moieties, a property that seems critical to allow the molecules to choose the most productive of the several binding modes possible in the transporter recognition site.In particular, compounds 5c and 5d, similar to the already reported analogous isomers 1c and 1d,²⁹ are potent and efficacious modulators of P-gp-dependent MDR and may be promising leads for the development of MDR-reversal drugs.