Measurement of bubble size distribution in protein foam fractionation column using capillary probe with photoelectric sensors

Bubble size is a key variable for predicting the ability to separate and concentrate proteins in a foam fractionation process. It is used to characterize not only the bubble-specific interfacial area but also coalescence of bubbles in the foam phase. This article describes the development of a photoelectric method for measuring the bubble size distribution in both bubble and foam columns for concentrating proteins. The method uses a vacuum to withdraw a stream of gas-liquid dispersion from the bubble or foam column through a capillary tube with a funnel-shaped inlet. The resulting sample bubble cylinders are detected, and their lengths are calculated by using two pairs of infrared photoelectric sensors that are connected with a high-speed data acquisition system controlled by a microcomputer. The bubble size distributions in the bubble column 12 and 1 cm below the interface and in the foam phase 1 cm above the interface are obtained in a continuous foam fractionation process for concentrating ovalbumin. The effects of certain operating conditions such as the feed protein concentration, superficial gas velocity, liquid flow rate, and solution pH are investigated. The results may prove to be helpful in understanding the mechanisms controlling the foam fractionation of proteins.

Serotonergic genes and suicidality

Several lines of evidence indicate that abnormalities in the functioning of the central serotonergic system are involved in the pathogenesis of depressive illness and suicidal behavior. Studies have shown that the number of brain and platelet serotonin transporter binding sites are reduced in patients with depression and in suicide victims, and that the density of 5-HT2A receptors is increased in brain regions of depressed in suicide victims and in platelets of depressed suicidal patients. Genes that code for proteins, such as tryptophan hydroxylase, 5-HT transporter, and 5-HT2A receptor, involved in regulating serotonergic neurotransmission, have thus been major candidate genes for association studies of suicide and suicidal behavior. Recent studies by our group and by others have shown that genetic variations in the serotonin-system-related genes might be associated with suicidal ideation and completed suicide. We have shown that the 102 C allele in 5-HT2A receptor gene was significantly associated with suicidal ideation (chi2 = 8.5. p < .005) in depressed patients. Patients with a 102 C/C genotype had a significantly higher mean HAMD item #3 score (indication of suicidal ideation) than T/C or T/7 genotype patients. Our results suggest that the 102T/C polymorphism in 5-HT2A receptor gene is primarily associated with suicidal ideation in patients with major depression and not with depression itself. We also found that the 5-HT transporter gene S/L polymorphism was significantly associated with completed suicide. The frequency of the L/L genotype in depressed suicide victims was almost double of that found in control group (48.6% vs. 26.2%). The odds ratio for the L allele was 2.1 (95% CI 1.2-3.7). The association between polymorphism in serotonergic genes and suicidality supports the hypothesis that genetic factors can modulate suicide risk by influencing serotonergic activity.

Cdc42 interacts with the exocyst and regulates polarized secretion

Polarized delivery and incorporation of proteins and lipids to specific domains of the plasma membrane is fundamental to a wide range of biological processes such as neuronal synaptogenesis and epithelial cell polarization. The exocyst complex is specifically localized to sites of active exocytosis and plays essential roles in secretory vesicle targeting and docking at the plasma membrane. Sec3p, a component of the exocyst, is thought to be a spatial landmark for polarized exocytosis. In a search for proteins that regulate the localization of the exocyst in the budding yeast Saccharomyces cerevisiae, we found that certain cdc42 mutants affect the polarized localization of the exocyst proteins. In addition, we found that these mutant cells have a randomized protein secretion pattern on the cell surface. Biochemical experiments indicated that Sec3p directly interacts with Cdc42 in its GTP-bound form. Genetic studies demonstrated synthetically lethal interactions between cdc42 and several exocyst mutants. These results have revealed a role for Cdc42 in exocytosis. We propose that Cdc42 coordinates the vesicle docking machinery and the actin cytoskeleton for polarized secretion.

The biosynthetic gene cluster for the anticancer drug bleomycin from Streptomyces verticillus ATCC15003 as a model for hybrid peptide-polyketide natural product biosynthesis

The hybrid peptide-polyketide backbone of bleomycin (BLM) is assembled by the BLM megasynthetase that consists of both nonribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) modules. BlmIX/BlmVIII/BlmVII constitute a natural hybrid NRPS/PKS/NRPS system, serving as a model for both hybrid NRPS/PKS and PKS/NRPS systems. Sequence analysis and functional comparison of domains and modules of BlmIX/BlmVIII/BlmVII with those of nonhybrid NRPS and PKS systems suggest that (1) the same catalytic sites appear to be conserved in both hybrid NRPS-PKS and nonhybrid NRPS or PKS systems, with the exception of the KS domains in the hybrid NRPS/PKS systems that are unique; (2) specific interpolypeptide linkers may play a critical role in intermodular communication to facilitate transfer of the growing intermediates between the interacting NRPS and/or PKS modules; and (3) posttranslational modification of the BLM megasynthetase has been accomplished by a single PPTase with a broad substrate specificity toward the apo forms of both acyl carrier proteins (ACPs) and peptidyl carrier proteins (PCPs).

Synchronization of separation and determination based on multichannel mode-filtered light detection with capillary electrophoresis

A novel method for the synchronization of separation and determination is described, in which a mode-filtered light detector is used as an online detector in capillary electrophoresis. An instrument is described which has been developed for this purpose. The round capillary used in conventional capillary electrophoresis is replaced by an annular column, which is constructed from a naked optical fibre inserted into a fused-silica capillary. In fact, the annular electrophoresis column itself forms part of the mode-filtered light sensor. Along the side of the annular column are several detection channels for gathering and transmitting the mode-filtered light to a charge-coupled device (CCD). Every channel provides information on the sample from the point at which it is located. Using capillary isotachophoresis incorporating the annular column, the analytes in a sample containing alanine (10.0 mM) and glycine (9.7 mM) were simultaneously separated and determined using multichannel mode-filtered light detection with a detection limit of 1.5 mM.

Selective protection of mitogenically stimulated human lymphocytes but not leukemic cells from cytosine arabinoside-induced apoptosis by LY294002, a phosphoinositol-3 kinase inhibitor

Most malignant tumors have a defect in the Rb pathway that allows them to proliferate autonomously, unrestricted by the availability of mitogens and growth factors. This defect preconditions tumor cells to be less sensitive to inhibitors of growth factor receptors and/or signal transduction pathways that arrest normal cells, predominantly in G0/1. Strategies were proposed, therefore, to combine cytotoxic agents with such inhibitors in order to selectively arrest normal host cells in a relatively resistant part of the cycle and thereby protect them during chemotherapy with agents targeting proliferating cells. The present study was designed to explore whether inhibition of phosphatidylinositol-3 kinase (PI3K), one of the pivotal kinases involved in signal transduction essential for cell proliferation can be considered in these strategies. Indeed, proliferation of phytohemagglutinin stimulated human lymphocytes was prevented at 5 microM concentration of LY294002 (LY), a PI3K inhibitor, whereas several-times higher (> or =20 microM) concentrations of LY were needed to affect proliferation of leukemic HL-60, Molt-4, or Jurkat cells. LY prevented the exit of lymphocytes from G0 concomitant with the suppression of induction of cyclins D2, D3 and E, and phosphorylation of pRb. G0/1 lymphocytes, that were initially stimulated in the absence of LY, were also inhibited from proliferating following exposure to LY. The arrest of lymphocytes by LY was reversible and, after its removal, the cells asynchronously re-entered the cell cycle. LY, at a concentration of 5-20 microM, protected lymphocytes from apoptosis induced by ara-C but offered no protection at all to Jurkat cells treated under identical conditions. The data suggest that inhibitors of PI3K such as LY may be considered in strategies designed to shield normal cells from the cytotoxicity of chemotherapy by transiently arresting them in the cycle. An additional advantage of LY was the suppression of the protein level and activity of PKB/Akt, a kinase that, through the phosphorylation of the proapoptotic molecule BAD, protects cells from apoptosis. Because this LY-induced suppression was stronger in Jurkat cells (>70%) than in lymphocytes (20%), the proapoptotic effects of PKB/Akt down-regulation appear to be selective towards tumor cells.

[Studies on correlation between protonation and tautomerism and luminescence characteristics of quinolone]

The fluorescence characteristics of 8 kinds of quinolone in different pH medium were studied. Rules of wavelength and intensity of the fluorescence in different pH medium were discovered. The correlation between the protonation, tautomerism and luminescence characteristics of quinolone are studied. It is found that in pH 6-8 or 2-4 there are two luminescence species. By this, the new view is represented that the change of luminescence characteristics is arised from the protonation and tautomerism of quinolones in different pH medium and the material point of luminescence developed in equilibrium system of tautomerism. Additionally, the correlation between the protonation, tautomerism and luminescence is further discussed.

CYP83b1 is the oxime-metabolizing enzyme in the glucosinolate pathway in Arabidopsis

CYP83B1 from Arabidopsis thaliana has been identified as the oxime-metabolizing enzyme in the biosynthetic pathway of glucosinolates. Biosynthetically active microsomes isolated from Sinapis alba converted p-hydroxyphenylacetaldoxime and cysteine into S-alkylated p-hydroxyphenylacetothiohydroximate, S-(p-hydroxyphenylacetohydroximoyl)-l-cysteine, the next proposed intermediate in the glucosinolate pathway. The production was shown to be dependent on a cytochrome P450 monooxygenase. We searched the genome of A. thaliana for homologues of CYP71E1 (P450ox), the only known oxime-metabolizing enzyme in the biosynthetic pathway of the evolutionarily related cyanogenic glucosides. By a combined use of bioinformatics, published expression data, and knock-out phenotypes, we identified the cytochrome P450 CYP83B1 as the oxime-metabolizing enzyme in the glucosinolate pathway as evidenced by characterization of the recombinant protein expressed in Escherichia coli. The data are consistent with the hypothesis that the oxime-metabolizing enzyme in the cyanogenic pathway (P450ox) was mutated into a "P450mox" that converted oximes into toxic compounds that the plant detoxified into glucosinolates.

[Characteristics of N2O emissions from vegetal soils on Fildes peninsula, Antarctica]

The N2O fluxes from the vegetal soils were first measured on the Fildes peninsula, Antarctica, and the total N2O emission was also estimated in the summer 2 months. The daily variations of N2O fluxes appeared single-peak trend under the sunshine or rainy weather conditions but they were irregular under the snow weather conditions and inconsistent with the atmospheric temperatures. The seasonal variations of the N2O fluxes were affected by the temperature and rainfall. The conditions during the transitions between dry and wet seasons improved the N2O emission. The total N2O emissions from moss and lichen soils were 3.7152 kg and 2.5344 kg, respectively. It follows that the vegetal soils are the sources for the atmospheric N2O on the Fildes peninsula, Antarctica.

Cloning and characterization of a phosphopantetheinyl transferase from Streptomyces verticillus ATCC15003, the producer of the hybrid peptide-polyketide antitumor drug bleomycin

BACKGROUND

Phosphopantetheinyl transferases (PPTases) catalyze the posttranslational modification of carrier proteins by the covalent attachment of the 4'-phosphopantetheine (P-pant) moiety of coenzyme A to a conserved serine residue, a reaction absolutely required for the biosynthesis of natural products including fatty acids, polyketides, and nonribosomal peptides. PPTases have been classified according to their carrier protein specificity. In organisms containing multiple P-pant-requiring pathways, each pathway has been suggested to have its own PPTase activity. However, sequence analysis of the bleomycin biosynthetic gene cluster in Streptomyces verticillus ATCC15003 failed to reveal an associated PPTase gene.

RESULTS

A general approach for cloning PPTase genes by PCR was developed and applied to the cloning of the svp gene from S. verticillus. The svp gene is mapped to an independent locus not clustered with any of the known NRPS or PKS clusters. The Svp protein was overproduced in Escherichia coli, purified to homogeneity, and shown to be a monomer in solution. Svp is a PPTase capable of modifying both type I and type II acyl carrier proteins (ACPs) and peptidyl carrier proteins (PCPs) from either S. verticillus or other Streptomyces species. As compared to Sfp, the only 'promiscuous' PPTase known previously, Svp displays a similar catalytic efficiency (k(cat)/K(m)) for the BlmI PCP but a 346-fold increase in catalytic efficiency for the TcmM ACP.

CONCLUSIONS

PPTases have recently been re-classified on a structural basis into two subfamilies: ACPS-type and Sfp-type. The development of a PCR method for cloning Sfp-type PPTases from actinomycetes, the recognition of the Sfp-type PPTases to be associated with secondary metabolism with a relaxed carrier protein specificity, and the availability of Svp, in addition to Sfp, should facilitate future endeavors in engineered biosynthesis of peptide, polyketide, and, in particular, hybrid peptide-polyketide natural products.

[Determination of ofloxacin in urine by synchronous-derivative fluorimetry]

The internal hormones in human urine emit strong fluorescence and interfere with the determination of trace ofloxacin. However, the experiments indicate that synchronous-first order derivative fluorimetry can be applied to the determination of trace ofloxacin without interference. The linear range is 0.36-3.6 micrograms.mL-1, detection limit is 0.3 microgram.mL-1, RSD is less than 2.5% and the recovery is within the range of 101%-103%.

Tryptophan hydroxylase gene 218A/C polymorphism is associated with somatic anxiety in major depressive disorder

BACKGROUND

Abnormalities in functioning of the central serotonergic system have been implicated in the pathogenesis of depressive illness and suicidal behavior. Tryptophan hydroxylase (TPH) is the rate-limiting enzyme in the biosynthesis of serotonin, therefore, it may play an important role in regulation or control of serotonin functions. The aim of the present investigation was to determine whether there is an association between TPH gene polymorphism and major depression. particularly in patients with suicidal ideation.

METHODS

A total of 135 unrelated patients suffering from major depressive disorder and 196 normal unrelated controls were included in the study. All controls and patients were Caucasian. A biallelic polymorphism at the tryptophan hydroxylase locus was genotyped.

RESULTS

No significant difference between controls and depressed subjects in TPH gene polymorphism was detected. There was no association between TPH gene polymorphism and suicidal ideation. Total HAMD scores were not different between the genotypes or alleles in patients. However, among the HAMD clusters, somatic anxiety was significantly associated with TPH genotypes and alleles in that patients with 218A/A genotype had a significantly higher somatic anxiety scores compared to other genotypes.

LIMITATION

Potential confounding effect of population stratification can not be excluded. The functional relevance of the TPH gene 218A/C polymorphism is, at present, uncertain.

CONCLUSION

The polymorphism in serotonergic system related genes may be associated with depressive symptoms in major depressive disorder. The results suggest that analysis of clusters that narrow down the phenotype may be more suitable in genetic studies of major depressive illness.

The therapeutic effects of Sheng Jing Zhong Zi Tang in treating male infertility

Eight-seven cases of male infertility due to spermatopathy were treated with Sheng Jing Zhong Zi Tang (SJZZT [symbol: see text]) for 1-3 courses. The total effective rate was 95.40% (83/87). 56.32% (49/87) of their spouses got pregnant and the semen quality was markedly improved (P < 0.01). The results showed that the decoction could dual-directionally regulate the levels of follicle-stimulating hormone (FSH), prolan B luteinizing hormone (LH), testosterone (T), and cortisol (C).

[An epidemiological and clinical study of primary gout]

OBJECTIVE

To evaluate the prevalence of primary gout in Shantou and Beijing area, and understand it's clinical features.

METHODS

Three epidemiological studies in Chenghai downtown, and the one of study in Beijing were studied. Clinical, laboratory and radiology data were collected and analyzed.

RESULT

The prevalence of primary gout in Chenghai surveys was 0.17%, 0.15% and 0.26% respectively; no case of primary gout was found in Beijing survey. Among the patients, male to female ratio was 21:1; average onset age of females was significantly higher than that of males. The numbers of patient in the recent 10 years was increasing. At the first attack, the first metatarsophalangeal joint was involved among 79.7% of all cases; no fourth metatarsophalangeal joint involvement had been found. Hyperlipemia was the most common accompanying abnormal laboratory test (57.1%). Radiographic bone erosion was found in 49.4% patients, most of them, the duration of disease was over 5 years.

CONCLUSION

The prevalence of primary gout was higher in Shantou area than that in Beijing, and it was increasing in the recent 10 years in Shantou area. The difference of geography, climate, food and lifestyle could be responsible for the different prevalence in different area.

Detection of caspases activation by fluorochrome-labeled inhibitors: Multiparameter analysis by laser scanning cytometry

BACKGROUND

The fluorochrome-labeled inhibitors of caspases (FLICA) were recently used as markers of activation of these enzymes in live cells during apoptosis (Bedner et al.: Exp Cell Res 259:308-313, 2000). The aims of this study were to (a) explore if FLICA can be used to study intracellular localization of caspases; (b) combine the detection of caspase activation with analysis of the changes with cell morphology detected by microscopy and laser scanning cytometry (LSC); and (c) adapt the assay to fixed cells that would enable correlation, by multiparameter analysis, of caspase activation with the cell attributes that require cell permeabilization in order to be measured.

METHODS

Apoptosis of human MCF-7, U-937, or HL-60 cells was induced by camptothecin (CPT) or tumor necrosis factor-alpha (TNF-alpha) combined with cycloheximide (CHX). Binding of FLICA to apoptotic versus nonapoptotic cells was studied in live cells as well as following their fixation and counterstaining of DNA. Intensity of cell labeling with FLICA and DNA-specific fluorochromes was measured by LSC.

RESULTS

Exposure of live cells to FLICA led to selective labeling of cells that had morphological changes characteristic of apoptosis. The FLICA labeling withstood cell fixation and permeabilization, which made it possible to stain DNA and measure its content for identification of the cell cycle position of labeled cells. When fixed cells were treated with FLICA, both apoptotic and nonapoptotic cells became strongly labeled and the labeling pattern was consistent with the localization of caspases as reported in the literature. A translocation of the FLICA binding targets from mitochondria to cytosol was seen in the MCF-7 cells treated with CPT. FLICA binding was largely (> 90%) prevented by the substrates of the caspases or by the unlabeled caspase inhibitors having the same peptide moiety as the respective FLICA.

CONCLUSIONS

The detection of caspase activation combined with cell permeabilization requires exposure of live cells to FLICA followed by their fixation. Cell reactivity with the respective FLICA, under these conditions, identifies the activated caspases and makes it possible to correlate their activation with the cell cycle position and other cell attributes that can be measured only after cell fixation/permeabilization. FLICA can also be used to study intracellular localization of caspases, including their translocation.

[The influence of acetylcholine on the proliferation of cultured human pituitary tumour cells]

AIM

To study the influence of acetylcholine on the proliferation, DNA synthesis and cell cycle of cultured human pituitary tumour cells.

METHODS

MTT method, 3H-TdR incorporation and cell cycle analysis were used to examine the changes of proliferation and DNA synthesis of human pituitary tumour cells.

RESULTS

Ach at 10(-7) mol/L - 10(-5) mol/L could decrease the 3H-TdR incorporation and the MTT A value in a dose dependent manner (P < 0.01), and the ratio of G1 phase of pituitary tumour cells increased markedly (P < 0.01). The effect of acetylcholine on the proliferation of cultured human pituitary tumour cells could be inhibited by atropine.

CONCLUSION

Ach inhibited the proliferation, DNA synthesis and cell cycle of cultured human pituitary tumour cells, and the inhibitory effect was mediated by acetylcholine receptor.

Biosynthesis of hybrid peptide-polyketide natural products

The structural and catalytic similarities between non-ribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) support the idea of combining individual NRPS and PKS modules for combinatorial biosynthesis. Recent advances in cloning and characterization of biosynthetic gene clusters for naturally occurring hybrid polyketide-peptide metabolites have provided direct evidence for the existence of hybrid NRPS-PKS systems, thus setting the stage to investigate the molecular basis for intermodular communication between NRPS and PKS modules. Reviewed in this article are biosynthetic data pertinent to hybrid peptide-polyketide biosynthesis published up to late 2000. Hybrid peptide-polyketide natural products can be divided into two classes: (i) those whose biosyntheses do not involve functional interaction between NRPS and PKS modules; and (ii) those whose biosyntheses are catalyzed by hybrid NRPS-PKS systems involving direct interactions between NRPS and PKS modules. It is the latter systems that are most likely amenable to combinatorial biosynthesis. The same catalytic sites appear to be conserved in both hybrid NRPS-PKS and normal NRPS or PKS systems, with the exception of the ketoacyl synthase domains in hybrid NRPS-PKS systems which are unique. Specific linkers may play a critical role in communication, facilitating the transfer of the growing intermediates between the interacting NRPS and/or PKS modules. In addition, phosphopantetheinyl transferases with broad carrier protein specificity are essential for the production of functional hybrid NRPS-PKS megasynthetases. These findings should now be taken into consideration in engineered biosynthesis of hybrid peptide-polyketide natural products for drug discovery and development.

[A quantitative pathological study on angiogenesis, vascular endothelial growth factor and inducible nitric oxide synthase in astrocytomas]

OBJECTIVE

To investigate whether the expression of vascular endothelial growth factor (VEGF) and inducible nitric oxide synthase (iNOS) are associated with angiogenesis and malignancy of astrocytomas.

METHODS

Immunohistochemistry, semiquantitation and image analysis were used to study the expression features of VEGF and iNOS in 61 cases of astrocytomas having follow-up data. Factor VIII related antigen (FVIII RAg) was also analysed in reflecting the epithelial cell amount and the microvessel density.

RESULTS

Microvessels in astrocytomas could be divided into seven types. The positive reaction areas and IA values of FVIIIRAg expression in the endothelium were significantly increased with the increase of tumor grade (P < 0.001) and VEGF labeling index (LI) (P < 0.05). The patients with high VEGF LIs (LI >or= 25%) had a poor prognosis. VEGF expression was significantly related to that of iNOS (P < 0.001), i.e., VEGF level was reduced along with the decrease of iNOS reaction.

CONCLUSION

Detection of FVIIIRAg could reflect the angiogenesis activities in astrocytomas. VEGF and iNOS could up-regulate each other to promote angiogenesis and are of importance in determining the malignancy degree of astrocytomas.

[Simultaneous determination of hydride forming and non-hydride forming elements in human hair by hydride generation-inductively coupled plasma atomic emission spectrometry]

A method for simultaneous determination of both hydride forming and non-hydride forming elements in human hair has also been successful. The influence of HCl concentration, NaBH4 concentration, carrier gas flow rate and rinse time on hydride forming elements intensity, and the effect of between nebulization and hydride-nebulization system on non-hydride forming elements have been studied. The optimum experimental conditions are selected. This method has been applied to the analysis of standard human hair with satisfactory results.

Caffeine dissociates complexes between DNA and intercalating dyes: application for bleaching fluorochrome-stained cells for their subsequent restaining and analysis by laser scanning cytometry

BACKGROUND

Removal of the nucleic acid-bound fluorochrome is desirable when stained cells have to be reanalyzed using other fluorochromes. It is also often desirable to remove DNA-bound antitumor drugs from drug-treated cells, to improve cell staining. We have previously observed that in aqueous solutions, the methylxanthine caffeine (CFN) decreases interactions between planar aromatic molecules such as intercalating dyes or antitumor drugs and nucleic acids. The aim of this study was to explore whether this property of CFN can be utilized to remove the DNA-bound intercalating dyes propidium iodide (PI) or 7-aminoactinomycin D (7-AAD) from the cells and whether the bleached cells can be restained and reanalyzed.

METHODS

HL-60 cells were fixed in 70% ethanol and their DNA was stained with PI or 7-AAD. The cells were then rinsed with a 0.05 M solution of CFN in phosphate-buffered saline (PBS) or with PBS alone. The decrease in intensity of cell fluorescence during rinsing was measured by laser scanning cytometry (LSC) to obtain the bleaching kinetics of individual cells. The bleached cells were then restained with PI, 7-AAD, or the protein-specific fluorochrome sulforhodamine 101(S101). Their fluorescence was measured again by LSC. In addition, free DNA was subjected to gel electrophoresis, DNA bands in the gels were stained with ethidium bromide (EB), and the gels were rinsed with a solution of CFN or PBS to bleach the DNA band's fluorescence.

RESULTS

Rinsing the PI or 7-AAD-stained cells with solutions of CFN led to nearly complete removal of PI and a more than 75% decrease in 7-AAD fluorescence after 10 min. The rinse with PBS decreased the PI cell fluorescence intensity by less than 30% and the 7-AAD fluorescence by about 50%. The differences in kinetics of PI or 7-AAD removal by CFN from G2/M versus G1 cells suggest that these intercalators bind more strongly to DNA in chromatin of G2/M than G1 cells. The CFN-bleached cells were then successfully stained with S101 and again with PI or 7-AAD. The bivariate analysis of the LSC merged files of the cells sequentially stained with PI and S101 revealed typical DNA/protein distributions. The fluorescence of EB-stained DNA bands in gels was also nearly completely removed by rinsing gels in 0.05 M CFN; PBS alone had a distinctly lesser effect.

CONCLUSION

Solutions of CFN can dissociate the DNA-bound PI, 7-AAD, EB, and possibly other intercalating fluorochromes. The bleached cells can be restained and reanalyzed by LSC. This approach can also be used to remove such fluorochromes from nucleic acids immobilized in gels and perhaps in other solid matrices. Analysis of the kinetics of fluorochrome removal from cells can possibly be used to study their binding affinities to nucleic acids in situ.

Hybrid peptide-polyketide natural products: biosynthesis and prospects toward engineering novel molecules

The structural and catalytic similarities between modular nonribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) inspired us to search for hybrid NRPS-PKS systems. By examining the biochemical and genetic data known to date for the biosynthesis of hybrid peptide-polyketide natural products, we show (1) that the same catalytic sites are conserved between the hybrid NRPS-PKS and normal NRPS or PKS systems, although the ketoacyl synthase domain in NRPS/PKS hybrids is unique, and (2) that specific interpolypeptide linkers exist at both the C- and N-termini of the NRPS and PKS proteins, which presumably play a critical role in facilitating the transfer of the growing peptide or polyketide intermediate between NRPS and PKS modules in hybrid NRPS-PKS systems. These findings provide new insights for intermodular communications in hybrid NRPS-PKS systems and should now be taken into consideration in engineering hybrid peptide-polyketide biosynthetic pathways for making novel "unnatural" natural products.

Identification of genes encoding receptor-like protein kinases as possible targets of pathogen- and salicylic acid-induced WRKY DNA-binding proteins in Arabidopsis

To understand how plant host genes are regulated during the activation of plant defence responses, we are studying a group of pathogen- and salicylic acid (SA)-induced DNA-binding proteins containing the novel WRKY domain. To identify downstream target genes of these WRKY proteins, we have searched the Arabidopsis genome and identified four closely linked genes on chromosome IV that contain an unusually large number of the W-box sequences [(T)TGAC(C/T)] recognized by WRKY proteins within a few hundred base pairs upstream of their coding regions. All four genes encode proteins characteristic of receptor-like protein kinases (RLK), each consisting of an N-terminal signal sequence, an extracellular receptor domain, a single transmembrane domain and a C-terminal cytoplasmic serine/threonine protein kinase domain. All four RLK genes were induced by treatment with SA or infection by a bacterial pathogen. Studies with one of the RLK genes (RLK4) indicated that a cluster of W-box elements in its promoter region were recognized by both purified WRKY proteins and SA-induced W-box binding activities from SA-treated Arabidopsis plants. Further analysis using the RLK4 gene promoter fused to a reporter gene in transgenic Arabidopsis indicated that the consensus WRKY protein-binding sites in the RLK4 gene promoter were important for the inducible expression of the reporter gene. These results indicate that pathogen- and SA-induced W-box binding proteins regulate not only genes encoding defence proteins with direct or indirect anti-microbial activities, but also genes encoding proteins with regulatory functions.

Gender differences in association between serotonin transporter gene polymorphism and personality traits

Since Lesch and colleagues reported an association between anxiety-related traits (Neuroticism) and a functional polymorphism in the serotonin transporter gene regulatory region (5-HTTLPR), there have been several reports on 5-HTTLPR and personality traits with both positive and negative results. The present study was a further attempt to replicate the original findings of Lesch et al. in a population of well-defined normal healthy subjects. In addition, a variable number tandem repeat polymorphism in the second intron was included in this study because it has recently been shown to act as a transcriptional regulator. Personality traits were evaluated in 186 unrelated normal subjects by the NEO Five Factor Inventory. The most important and novel finding of this study was a significant association of mean Neuroticism scores with the short allele of 5-HTTLPR in male subjects (t = 2.4, P = 0.018). We were thus able to replicate the finding of Lesch et al. of an association between serotonin transporter gene polymorphism (5-HTTLPR) and Neuroticism, but only in a male population. We also found a significant effect of gender on mean scores of Neuroticism [F = 3.9, degrees of freedom (df) = 1, 180, P = 0.05] and Agreeableness (F = 6.8, df = 1, 180, P = 0.01), but no significant effect of 5-HTTLPR genotype on Neuroticism (F = 0.87, df= 2, 180, P = 0.42) or Agreeableness (F = 0.35, df = 2, 180, P = 0.7). These findings suggest that gender differences exist in contribution of genetic factors to behavioural phenotypes. They may also explain the inconsistencies in previous reports on association of Neuroticism with 5-HTTLPR from studies using different proportions of male and female subjects.

Modulation of mitogen-activated protein kinases and phosphorylation of Bcl-2 by vinblastine represent persistent forms of normal fluctuations at G2-M1

Microtubule inhibitors, widely used in cancer chemotherapy, induce G2-M arrest and apoptosis and have in common the ability to stimulate Raf-1/Bcl-2 phosphorylation and activate c-Jun NH2-terminal protein kinase (JNK). These signal transduction pathways are thought to be activated in response to microtubule damage to promote apoptosis. However, Bcl-2 phosphorylation has been reported to occur at G2-M in nonapoptotic cells, raising the possibility that this and perhaps other signaling pathways altered by microtubule inhibitors reflect perturbations of normal mitotic events. In this study, we sought to test this hypothesis. We show that Bcl-2 phosphorylation and JNK activation, as well as extracellular response kinase and p38 inactivation, occur not only in response to vinblastine but also as discrete transient events at G2-M phase in untreated synchronized KB-3 cells. Thus, modulation of these pathways is not a response to microtubule damage; rather they occur normally at G2-M, and it is the extent, duration, and/or irreversible nature of the signals that distinguish a preapoptotic cell from one destined to divide. These findings provide novel insight into the relationship between mitotic and apoptotic signaling and the mechanism of action of antimitotic drugs.

Systemic infusion of naloxone reduces degeneration of rat substantia nigral dopaminergic neurons induced by intranigral injection of lipopolysaccharide

A massive degeneration of dopamine-containing neurons in the substantia nigra (SN) in the midbrain is characteristic of Parkinson's disease. Inflammation in the brain has long been speculated to play a role in the pathogenesis of this neurological disorder. Recently, we reported that treatment of primary rat mesencephalic mixed neuron-glia cultures with lipopolysaccharide (LPS) led to the activation of microglia, resident immune cells of the brain, and subsequent death of dopaminergic neurons. The LPS-induced degeneration of dopaminergic neurons was significantly attenuated by the opiate receptor antagonist (-)-naloxone and its inactive isomer (+)-naloxone, with equal potency, through an inhibition of microglial activation and their production of neurotoxic factors. In this study, injection of LPS into the rat SN led to the activation of microglia and degeneration of dopaminergic neurons: microglial activation was observed as early as 6 h and loss of dopaminergic neurons was detected 3 days after the LPS injection. Furthermore, the LPS-induced loss of dopaminergic neurons in the SN was time- and LPS concentration-dependent. Systemic infusion of either (-)-naloxone or (+)-naloxone inhibited the LPS-induced activation of microglia and significantly reduced the LPS-induced loss of dopaminergic neurons in the SN. These in vivo results combined with our cell culture observations confirmed that naloxone protects dopaminergic neurons against inflammation-mediated degeneration through inhibition of microglial activation and suggest that naloxone would have therapeutic efficacy in the treatment of inflammation-related neurological disorders. In addition, the inflammation-mediated degeneration of dopaminergic neurons in the rat SN resulting from the targeted injection of LPS may serve as a useful model to gain further insights into the pathogenesis of Parkinson's disease.

Progress in the molecular genetic research of multinodular goiter

Multinodular goiter is a worldwide-distributed disease, but yet its pathology and genetic etiology are not clear. At present, most researches have been restrained to traditional epidemiological survey and the disease has been rarely studied at the level of molecular genetics. The pathogenesis of multinodular goiter, as is generally accepted by most researchers, can be attributed to many factors such as hormones, growth factors and the inherent functional heterogeneity of thyroid follicles. Since hormone and iodine metabolization are widely recognized as a major mechanism in determining the formation of multinodular goiter, some reports in literature are mainly focused on such genes that are responsible for hormone synthesis and iodine metabolization. Mapping experimental data were available to support location of multinodular goiter gene(s) onto chromosome 14q by whole genome scanning in a large pedigree analysis. Additional data, particularly those extracted from large scaled marker-assisted mapping experiments, are important so as to confirm the gene location, to improve resolution of the location, and finally to dissect the genes underlying the disease at molecular level.

Modeling a protein foam fractionation process

A simple staged model for the protein foam fractionation process is proposed in this article. This simplified model does not detail the complex foam structure and gas-liquid hydrodynamics in the foam phase but, rather, is built on the conventional theoretical stage concept considering upward bubbles with entrained liquid and downward liquid (drainage) as counter-current flows. To simulate the protein concentration distribution in the liquid along the column by the model, the bubble size and liquid hold-up with respect to the position must be known, as well as the adsorption isotherm of the protein being considered. The model is evaluated for one stage by data from the semibatch foam fractionation of egg albumin and data from the continuous foam fractionation of bovine serum albumin. The effect of two significant variables (superficial gas velocity and feed protein concentration) on enrichment is well predicted by the model, especially for continuous operation and semibatch operation when initial concentration is high.

Effect of protein denaturation on void fraction in foam separation column

Foam fractionation is a cost-effective process that uses air to extract protein from a liquid (in this case "crude" dilute egg-albumin solution). This article deals with how the void fraction (fraction of air in the aerated solution) of foam is affected by heat denaturation of the protein. A 2-mm glass tube was used to sample the foam-liquid interface fluid in a 35-mm-diameter column in order to detect small changes in void fraction and foam production, which are not easily detected directly from the bulk foam. The main control variable in this study was the protein solution preheating time. As the preheating time increased, the initial void fraction in the column decreased. The initial void fraction of the undenatured solution ranged from about 0.73 to 0.80, and the void fraction for significant preheating times of 5 min ranged from approx 0.68 to 0.72. Furthermore, the period of foam production increased from 5 to 7 min for undenatured proteins in solution to as long 15 min for 5-min preheated solutions. Side-port sampling through a small capillary tube has the potential to be used as a rapid and inexpensive way to determine the level of protein denaturation by directly determining the void fraction and then estimating the effect of denaturation from a protein denaturation calibration curve of the void fraction.

Association of polymorphism of serotonin 2A receptor gene with suicidal ideation in major depressive disorder

There is evidence indicating that density of 5-HT2A receptors is altered in brain regions of depressed suicide victims and in platelets of suicidal subjects with major depression or schizophrenia. Recent studies have also shown an association between the allele C of 102T/C polymorphism in the 5-HT2A receptor gene and schizophrenia. The present investigation tested the hypothesis that the observed changes in 5-HT2A receptor density in platelets of patients with major depression are a trait rather than state phenomenon and are associated with the 102 C allele in 5-HT2A receptor gene in a sample of 120 patients with major depression and a group of 131 control subjects comparable with respect to age, sex, and ethnic background. The allele and genotype frequencies of 102T/C polymorphism in 5-HT2A receptor gene were compared between patients and control subjects and between suicidal and non-suicidal patient groups. The major finding of this study was a significant association between the 102 C allele in 5-HT2A receptor gene and major depression, chi(2) = 4.5, df = 1, P = 0.03, particularly in patients with suicidal ideation, chi(2) = 8.5, df = 1, P < 0.005. Furthermore, we found that patients with a 102 C/C genotype had a significantly higher mean HAMD item 3 score (indication of suicidal ideation) than T/C or T/T genotype patients. Our results suggest that the 102T/C polymorphism in 5-HT2A receptor gene is primarily associated with suicidal ideation in patients with major depression. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:56-60, 2000.

An oxidation domain in the BlmIII non-ribosomal peptide synthetase probably catalyzing thiazole formation in the biosynthesis of the anti-tumor drug bleomycin in Streptomyces verticillus ATCC15003

We have previously proposed that the BlmIV and BlmIII non-ribosomal peptide synthetases are involved in the formation of the bithiazole moiety of the anti-tumor drug bleomycin in Streptomyces verticillus ATCC15003. We report here the identification and characterization of an oxidation domain in BlmIII. The oxidation domain shows local homology to a family of oxidoreductases and is present in all thiazole-forming non-ribosomal peptide synthetase modules known to date. Both the blmIII-Ox domain and blmIII gene were expressed in Escherichia coli, and the resulting BlmIII-Ox and BlmIII proteins were purified to homogeneity. The oxidation domain contains one molar equivalent of non-covalently bound FMN as a prosthetic group. These results provide experimental evidence for an oxidation domain within non-ribosomal peptide synthetases, suggesting that BlmIII-Ox probably catalyzes the thiazoline to thiazole oxidation in bleomycin biosynthesis.

The biosynthetic gene cluster for the antitumor drug bleomycin from Streptomyces verticillus ATCC15003 supporting functional interactions between nonribosomal peptide synthetases and a polyketide synthase

BACKGROUND

The structural and catalytic similarities between modular nonribosomal peptide synthetases (NRPSs) and polyketide synthases (PKSs) inspired us to search for a hybrid NRPS-PKS system. The antitumor drug bleomycin (BLM) is a natural hybrid peptide-polyketide metabolite, the biosynthesis of which provides an excellent opportunity to investigate intermodular communication between NRPS and PKS modules. Here, we report the cloning, sequencing, and characterization of the BLM biosynthetic gene cluster from Streptomyces verticillus ATCC15003.

RESULTS

A set of 30 genes clustered with the previously characterized blmAB resistance genes were defined by sequencing a 85-kb contiguous region of DNA from S. verticillus ATCC15003. The sequenced gene cluster consists of 10 NRPS genes encoding nine NRPS modules, a PKS gene encoding one PKS module, five sugar biosynthesis genes, as well as genes encoding other biosynthesis, resistance, and regulatory proteins. The substrate specificities of individual NRPS and PKS modules were predicted based on sequence analysis, and the amino acid specificities of two NRPS modules were confirmed biochemically in vitro. The involvement of the cloned genes in BLM biosynthesis was demonstrated by bioconversion of the BLM aglycones into BLMs in Streptomyces lividans expressing a part of the gene cluster.

CONCLUSION

The blm gene cluster is characterized by a hybrid NRPS-PKS system, supporting the wisdom of combining individual NRPS and PKS modules for combinatorial biosynthesis. The availability of the blm gene cluster has set the stage for engineering novel BLM analogs by genetic manipulation of genes governing BLM biosynthesis and for investigating the molecular basis for intermodular communication between NRPS and PKS in the biosynthesis of hybrid peptide-polyketide metabolites.

Reduction by naloxone of lipopolysaccharide-induced neurotoxicity in mouse cortical neuron-glia co-cultures

An inflammatory response in the CNS mediated by activation of microglia is a key event in the early stages of the development of neurodegenerative diseases. Using mouse cortical mixed glia cultures, we have previously demonstrated that the bacterial endotoxin lipopolysaccharide induces the activation of microglia and the production of proinflammatory factors. Naloxone, an opioid receptor antagonist, inhibits the lipopolysaccharide-induced activation of microglia and the production of proinflammatory factors. Using neuron-glia co-cultures, we extended our study to determine if naloxone has a neuroprotective effect against lipopolysaccharide-induced neuronal damage and analysed the underlying mechanism of action for its potential neuroprotective effect. Pretreatment of cultures with naloxone (1 microM) followed by treatment with lipopolysaccharide significantly inhibited the lipopolysaccharide-induced production of nitric oxide and the release of tumor necrosis factor-alpha, and significantly reduced the lipopolysaccharide-induced damage to neurons. More importantly, both naloxone and its opioid-receptor ineffective enantiomer (+)-naloxone were equally effective in inhibiting the lipopolysaccharide-induced generation of proinflammatory factors and the activation of microglia, as well as in the protection of neurons. These results indicate that the neuroprotective effect of naloxone is mediated by its inhibition of microglial activity and may be unrelated to its binding to the classical opioid receptors.

[Study on the effect of several antioxidants on the stability of oils]

The stability of oils is very important for ensuring the sanitation and quality of oils and the foods containing oils and fats. In this study, BHT, TBHQ and micro-capsule antioxidants (mixed antioxidants) were tested for their properties of antioxidation in oils under different temperatures. The results showed that the mixed antioxidant used in oils was more effective than the single antioxidant, especially under high temperature. It was concluded that microcapsule antioxidant was effective, economical and relatively safe when it was used in oils for frying foods.

During apoptosis of HL-60 and U-937 cells caspases are activated independently of dissipation of mitochondrial electrochemical potential

Collapse of the mitochondrial potential (DeltaPsi(m)) during apoptosis has been linked with a release of cytochrome c and apoptosis-inducing factor (AIF) and activation of caspases. Using a laser scanning cytometer (LSC), an instrument that allows one to measure the same cells twice, first when they are alive and subsequently after their permeabilization, we explored whether dissipation of DeltaPsi(m) (measured supravitally) is a prerequisite for the activation of caspases (detected after cell fixation). Apoptosis of HL-60 cells was induced either by TNF-alpha combined with cycloheximide (CHX) or by the DNA topoisomerase I inhibitor camptothecin (CPT) and of U-937 cells by CPT, and DeltaPsi(m) was measured using the carbocyanine fluorochrome DiIC(1) (5). The marker of caspase activation was specific cleavage of poly(ADP) ribose polymerase (PARP) detected immunocytochemically. After 30 or 60 min treatment with TNF-alpha + CHX or 60 or 120 min with CPT a considerable proportion of cells (20-40%) demonstrated PARP cleavage with no evidence of DeltaPsi(m) collapse. Also present in these cultures (3-20%) were cells with collapsed DeltaPsi(m) whose PARP was not cleaved. The results provide direct evidence that in HL-60 and U-937 cells treated with TNF-alpha + CHX or CPT the dissipation of DeltaPsi(m) is not required for activation of caspases and these two events are independent of each other.

[Abdominal aortic aneurysm treated by endovascular stent-graft and conventional surgical repair: a comparison]

OBJECTIVE

To evaluate the feasibility of abdominal aortic aneurysm (AAA) treated by endovascular stent-graft.

METHODS

The clinical data of 52 patients with AAA treated by endovascular stent-graft (n = 20) and conventional surgical repair (n = 32) were analysed retrospectively. Patients conditions, operative hours, blood loss, function recovery and complications were compared.

RESULTS

No significant difference was observed in sex, age, other disease, anesthesia risk category, aneurysm type, aneurysm diameter, technical success rate, and mortality rate between the groups (P > 0.05). The patients who underwent intraluminal treatment had significant reductions in operative time, blood loss, intensive care unit and hospitalization. But there was a high complication rate in the endovascular stent-graft group. All complications were connected with the interventional technique; endo-leak was the chief complication after operation.

CONCLUSIONS

Endovascular treatment has marked merits such as reduced trauma, short hospitalization stays, and early functional recovery. It is suitable for the patients who can't undergo open surgical repair. But the complications caused by this technique needs further study.

Naloxone protects rat dopaminergic neurons against inflammatory damage through inhibition of microglia activation and superoxide generation

Degeneration of dopaminergicrgic neurons in the substantia nigra of the brain is a hallmark of Parkinson's disease and inflammation and oxidative stress are closely associated with the pathogenesis of degenerative neurological disorders. Treatment of rat mesencephalic mixed neuron-glia cultures with lipopolysaccharide (LPS)-activated microglia, resident immune cells of the brain, to release proinflammatory and neurotoxic factors tumor necrosis factor-alpha, interleukin-1beta, nitric oxide, and superoxide and subsequently caused damage to midbrain neurons, including dopaminergic neurons. The LPS-induced degeneration of the midbrain neurons was significantly reduced by cotreatment with naloxone, an opioid receptor antagonist. This study focused on understanding the mechanism of action for the protective effect of naloxone on dopaminergic neurons because of relevance to Parkinson's disease. Both naloxone and its opioid receptor inactive stereoisomer (+)-naloxone protected the dopaminergic neurons with equal potency. Naloxone inhibited LPS-induced activation of microglia and release of proinflammatory factors, and inhibition of microglia generation of superoxide free radical best correlated with the neuroprotective effect of naloxone isomers. To further delineate the site of action, naloxone was found to partially inhibit the binding of [(3)H]LPS to cell membranes, whereas it failed to prevent damage to dopaminergic neurons by peroxynitrite, a product of nitric oxide and superoxide. These results suggest that naloxone at least in part interferes with the binding of LPS to cell membranes to inhibit microglia activation and protect dopaminergic neurons as well as other neurons in the midbrain cultures from inflammatory damage.

Reduction of lipopolysaccharide-induced neurotoxicity in mouse mixed cortical neuron/glia cultures by ultralow concentrations of dynorphins

Previously we reported that ultralow concentrations of dynorphins (10(-16) to 10(-12) M) inhibited lipopolysaccharide (LPS)-induced production of nitric oxide (NO) and proinflammatory cytokines in mouse glia without the participation of kappa-opioid receptors. In the current study using mouse cortical neuron-glia cocultures, we examined the possibility that inhibition of glia inflammatory response by dynorphins might be neuroprotective for neurons. LPS, in a concentration-dependent manner, markedly increased the release of lactate dehydrogenase (LDH), an indicator of cellular injury. Ultralow concentrations (10(-14) to 10(-12) M) of dynorphin (dyn) A-(1-8) significantly prevented the LPS-induced release of LDH, loss of neurons, and changes in cell morphology, in addition to inhibition of LPS-induced nitrite production. Meanwhile, ultralow concentrations (10(-15) to 10(-13) M) of des-[Tyr(1)]-dyn A-(2-17), a nonopioid peptide which does not bind to kappa-opioid receptors, exhibited the same inhibitory effect as dyn A-(1-17). These results suggest that dynorphins at ultralow concentrations are capable of reducing LPS-induced neuronal injury and these neuroprotective effects of dynorphins are not mediated by classical opioid receptors.

[Endoluminal stent-graft repair of aortic aneurysms]

OBJECTIVE

To study the clinical value of the treatment of aortic aneurysms with endovascular stent-graft prosthesis.

METHODS

After a unilateral surgical arteriotomy, Talent, Vanguard and Chinese stent-graft were advanced through the femoral arteries and placed in the proper position of the aneurysm sac under X-ray fluoroscopic guidance.

RESULTS

Four patients with descending aneurysm, 1 patient with abdominal aortic aneurysm (AAA) involving the renal artery, superior mesenteric artery and celiac artery, and 1 patient with right common iliac artery aneurysm received straight stent-grafts. Five patients with infrarenal AAA received bifurcated stent-grafts. CT and MRA were performed during a follow-up of 3 - 19 months. Aortic aneurysms were completely excluded from the circulation. Five patients prolonged fever was noted and 1 patient was found to have a leakage 3 months later, and hemiplegia in 1 after procedure.

CONCLUSIONS

Endovascular treatment of aortic aneurysm is technically feasible and can effectively exclude aortic aneurysms from the circulation. Endoluminal repair may serve as an interventional strategy to treat aneurysm, especially in patients at high surgical risk, but long term effect needs further study.

Association of polymorphism of serotonin 2A receptor gene with suicidal ideation in major depressive disorder

There is evidence indicating that density of 5-HT2A receptors is altered in brain regions of depressed suicide victims and in platelets of suicidal subjects with major depression or schizophrenia. Recent studies have also shown an association between the allele C of 102T/C polymorphism in the 5-HT2A receptor gene and schizophrenia. The present investigation tested the hypothesis that the observed changes in 5-HT2A receptor density in platelets of patients with major depression are a trait rather than state phenomenon and are associated with the 102 C allele in 5-HT2A receptor gene in a sample of 120 patients with major depression and a group of 131 control subjects comparable with respect to age, sex, and ethnic background. The allele and genotype frequencies of 102T/C polymorphism in 5-HT2A receptor gene were compared between patients and control subjects and between suicidal and non-suicidal patient groups. The major finding of this study was a significant association between the 102 C allele in 5-HT2A receptor gene and major depression, chi(2) = 4.5, df = 1, P = 0.03, particularly in patients with suicidal ideation, chi(2) = 8.5, df = 1, P < 0.005. Furthermore, we found that patients with a 102 C/C genotype had a significantly higher mean HAMD item 3 score (indication of suicidal ideation) than T/C or T/T genotype patients. Our results suggest that the 102T/C polymorphism in 5-HT2A receptor gene is primarily associated with suicidal ideation in patients with major depression. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:56-60, 2000.

Adherence of Porphyromonas gingivalis to gingival epithelial cells: modulation of bacterial protein expression

The protein profiles of Porphyromonas gingivalis (ATCC 33277 and W83) bound to KB gingival epithelial cells were analyzed by SDS-PAGE and immunoblotting. We found that a 51-kDa component was formed in bacteria that adhered to the KB cells, whereas 26- to 29-kDa bands were less intensive, in contrast to the protein profile of free bacteria. P. gingivalis ATCC 33277 incubated with protease-treated KB cells retained the profile of free bacteria. These results demonstrate the specificity of bacterial recognition of eukaryotic membrane components.

Familiarity leads to female mate preference for novel males in the guppy, Poecilia reticulata

Guppies are a model vertebrate for studies of sexual selection and life history evolution. None the less, there have been few investigations of the factors responsible for maintaining extreme within-population genetic variation in male coloration. In a laboratory study, we tested the hypothesis that frequency-dependent mate choice contributes to the maintenance of this variation. We attempted to avoid biases inherent in earlier studies of the 'rare male effect' by familiarizing females to males bearing a particular colour pattern and later presenting them with alternate male types, in equal numbers. Females were significantly more likely to mate with males having novel colour patterns than with males having a colour pattern with which they were familiar. This result is consistent with the hypothesis that mate choice is frequency dependent. Other factors such as male and female size were unrelated to mate preference. Implications of the results for theories of sexual selection and the maintenance of variation are discussed. Copyright 1999 The Association for the Study of Animal Behaviour.

Personality correlates of auditory augmenting response to clicks repeated around 2Hz

Eighty-three subjects (47 women and 36 men) were submitted to Plutchik-van Praag's (PVP) depression inventory, Zuckerman's sensation seeking scales and Zuckerman-Kuhlman's personality inventory, and underwent auditory evoked potential studies using clicks at 4 different intensities of 70, 80, 90 and 100 dB. The clicks were delivered at an interstimulus interval varying randomly around 0.5s, which can elicit an obligatory subcomponent of N1. The P2 latency was significantly prolonged at the highest intensity. The intensity dependence of peak-to-peak N1-P2 and of baseline-to-peak N1 and P2 components was pronounced and the majority of subjects were augmenters. The N1 latency elicited at 70 dB was positively correlated with the thrill and adventure seeking, which then correlated the activity. The correlation suggests that a lower level of arousal, as indicated by prolonged N1 latency, would lead one to seek higher stimulation, such as the augmented response, the increased desire of physical thrill and adventure and elevated activity. This study, therefore, supports Zuckerman's theory that a sensation seeking personality is related to cortical arousal level.