The Genomic Basis of Color Pattern Polymorphism in the Harlequin Ladybird

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Exposure to polychlorinated biphenyls causes endothelial cell dysfunction

Environmental chemicals, such as polychlorinated biphenyls (PCBs), may be atherogenic by disrupting normal functions of the vascular endothelium. To investigate this hypothesis, porcine pulmonary artery-derived endothelial cells were exposed to 3,3′,4,4′-tetrachlorobiphenyl (PCB 77), 2,3,4,4′,5-pentachlorobiphenyl (PCB 114), or 2,2′,4,4′,5,5′-hexachlorobiphenyl (PCB 153) for up to 24 hours. These PCBs were selected for their varying binding avidities with the aryl hydrocarbon (Ah) receptor and differences in their induction of cytochrome P450. PCB 77 and PCB 114 significantly disrupted, in a dose-dependent manner, endothelial barrier function by allowing an increase in albumin transfer across endothelial monolayers. These PCBs also contributed markedly to cellular oxidative stress, as measured by 2,7-dichlorofluorescin (DCF) fluorescence and lipid hydroperoxides, and caused a significant increase in intracellular calcium ([Ca²⁺]_i) levels. Enhanced oxidative stress and [Ca²⁺]_i in PCB 77- and PCB 114-treated cells were accompanied by increased activity and content of cytochrome P450 1A and by a decrease in the vitamin E content in the culture medium. In contrast to the effects of PCB 77 and PCB 114, cell exposure to PCB 153 had no effect on cellular oxidation, [Ca²⁺]_i, or endothelial barrier function. These results suggest that certain PCBs may play a role in the development of atherosclerosis by causing endothelial cell dysfunction and a decrease in the barrier function of the vascular endothelium. It is possible that interaction of PCBs with the Ah receptor and activation of the cytochrome P450 1A subfamily are involved in this pathology. © 1995 John Wiley & Sons, Inc.     

Dietary linolenic acid-mediated increase in vascular prostacyclin formation

To define vascular effects of an enhanced dietary -linolenic acid intake, 28 spontaneously hypertensive rats were fed a 3% sunflowerseed oil (44% linoleic acid) diet; in 3 groups (7 rats each), the diet was supplemented with 1, 2.5 or 5% linseed oil containing 62% -linolenic acid. -Linolenic acid was incorporated up to 12% in the aorta of the 5% linseed oil group. The eicosapentaenoic acid content was not significantly increased. The content of arachidonic acid and docosatetraenoic acid was moderately reduced in rats fed 5% linseed oil. The generation of 6-keto-PGF₁ (degradation product of prostacyclin) assessed by HPLC/electrochemical detection was, however, markedly increased (p < 0.05) in rats fed 2.5 and 5% linseed oil. The minor prostanoids TXB₂, PGE₂ and PGF₂ were not significantly altered. The high systolic and diastolic blood pressure of SHR monitored by radio telemetry was more effectively reduced (p < 0.05) in the light, i.e. sleep, cycle. An increased prostacyclin formation and lowered vascular arachidonic acid content associated with enhanced dietary -linolenic acid intake would thus be expected to prove beneficial in the prevention of vascular disorders.     

MiL-FISH: Multilabeled Oligonucleotides for Fluorescence In Situ Hybridization Improve Visualization of Bacterial Cells

Fluorescence in situ hybridization (FISH) has become a vital tool for environmental and medical microbiology and is commonly used for the identification, localization, and isolation of defined microbial taxa. However, fluorescence signal strength is often a limiting factor for targeting all members in a microbial community. Here, we present the application of a multilabeled FISH approach (MiL-FISH) that (i) enables the simultaneous targeting of up to seven microbial groups using combinatorial labeling of a single oligonucleotide probe, (ii) is applicable for the isolation of unfixed environmental microorganisms via fluorescence-activated cell sorting (FACS), and (iii) improves signal and imaging quality of tissue sections in acrylic resin for precise localization of individual microbial cells. We show the ability of MiL-FISH to distinguish between seven microbial groups using a mock community of marine organisms and its applicability for the localization of bacteria associated with animal tissue and their isolation from host tissues using FACS. To further increase the number of potential target organisms, a streamlined combinatorial labeling and spectral imaging-FISH (CLASI-FISH) concept with MiL-FISH probes is presented here. Through the combination of increased probe signal, the possibility of targeting hard-to-detect taxa and isolating these from an environmental sample, the identification and precise localization of microbiota in host tissues, and the simultaneous multilabeling of up to seven microbial groups, we show here that MiL-FISH is a multifaceted alternative to standard monolabeled FISH that can be used for a wide range of biological and medical applications.     

Manufacturing of a Secretoneurin Drug Delivery System with Self-Assembled Protamine Nanoparticles by Titration

Since therapeutic peptides and oligonucleotides are gathering interests as active pharmaceutical ingredients (APIs), nanoparticulate drug delivery systems are becoming of great importance. Thereby, the possibility to design drug delivery systems according to the therapeutic needs of APIs enhances clinical implementation. Over the last years, the focus of our group was laid on protamine-oligonucleotide-nanoparticles (so called proticles), however, the possibility to modify the size, zeta potential or loading efficiencies was limited. Therefore, at the present study we integrated a stepwise addition of protamine (titration) into the formation process of proticles loaded with the angiogenic neuropeptide secretoneurin (SN). A particle size around 130 nm was determined when proticles were assembled by the commonly used protamine addition at once. Through application of the protamine titration process it was possible to modify and adjust the particle size between approx. 120 and 1200 nm (dependent on mass ratio) without influencing the SN loading capacity. Dynamic light scattering pointed out that the difference in particle size was most probably the result of a secondary aggregation. Initially-formed particles of early stages in the titration process aggregated towards bigger assemblies. Atomic-force-microscopy images also revealed differences in morphology along with different particle size. In contrast, the SN loading was only influenced by the applied mass ratio, where a slight saturation effect was observable. Up to 65% of deployed SN could be imbedded into the proticle matrix. An in-vivo biodistribution study (i.m.) showed a retarded distribution of SN from the site of injection after the application of a SN-proticle formulation. Further, it was demonstrated that SN loaded proticles can be successfully freeze-dried and resuspended afterwards. To conclude, the integration of the protamine titration process offers new possibilities for the formulation of proticles in order to address key parameters of drug delivery systems as size, API loading or modified drug release.     

Perceptual spatial frequency — Orientation surface: Psychophysics and line element theory

We have investigated the discriminability of gratings which simultaneously vary in spatial frequency and orientation. Thirteen and nine reference gratings were used with two observers, and bivariate discrimination probability surfaces were determined around each grating. These data were then fitted to a general bivariate Gaussian function. The results clearly demonstrate local separability in this log frequency and orientation discrimination domain. Our results also show that the factor contributing most to the non-Euclidean nature of such frequency/orientation discrimination is orientation anisotropia, although we also find some evidence for smaller changes in the associated Riemannian line-element at different frequency ranges. These results cast doubt upon claims for a pseudo line-element for frequency discrimination based upon the nonlinear outputs of a fixed set of detectors.Study supported by Fraunhofer Gesellschaft Grant INSAN I 0784-V-6385 and Guest Professorship Mu 93/103-1 for TC by Deutsche Forschungsgemeinschaft     

The phosphoenolpyruvate carboxylase gene of Corynebacterium glutamicum: molecular cloning, nucleotide sequence, and expression

Summary The ppc gene of Corynebacterium glutamicum encoding phosphoenolpyruvate (PEP) carboxylase was isolated by complementation of a ppc mutant of Escherichia coli using a cosmid gene bank of chromosomal c. glutamicum DNA. By subsequent subcloning into the plasmid pUC8 and deletion analysis, the ppc gene could be located on a 3.3 kb SalI fragment. This fragment was able to complement the E. coli ppc mutant and conferred PEP carboxylase activity to the mutant. The complete nucleotide sequence of the ppc gene including 5 and 3 flanking regions has been determined and the primary structure of PEP carboxylase was deduced. The sequence predicts a 919 residue protein product (molecular weight of 103154) which shows 34% similarity with the respective E. coli enzyme. Present address: Institut für Biotechnologie 1 der Kernforschungsanlage, Postfach 1913, D-5170 Jülich, Federal Republic of Germany     

A vector system with temperature-sensitive replication for gene disruption and mutational cloning in streptomycetes

Summary Replication of the Streptomyces ghanaensis plasmid pSG5 was shown to be temperature sensitive. The pSG5 replicon is stably inherited at temperatures below 34° C, but is lost at incubation temperatures above this. A family of cloning vectors was constructed using the pSG5 minimal replicon and different marker genes. The vectors obtained are small in size, have an intermediate copy number, possess a broad host range and are compatible with some other streptomycete vector systems. By increasing the incubation temperature, these vectors can be eliminated from their host cells very efficiently. The suitability of the pSG5 vector family for mutating chromosomal genes by gene disruption was demonstrated: pBN10, a pSG5 derivative containing an internal fragment of the phosphinothricyl-alanyl-alanine (PTT) resistance gene pat, was integrated into the chromosomal pat gene of the PTT-producer Streptomyces viridochromogenes thus inactivating PTT resistance. The integrated pBN10 plasmid was rescued from the chromosome, together with an adjacent fragment carrying DNA of the PTT biosynthetic cluster.