Cytotoxic components of Zingiber zerumbet,Curcuma zedoaria and C. domestica

One new and five known compounds, which all showed cytotoxic activity, were isolated from the rhizomes of Zingiber zerumbet. The new compound was 3″,4″-O-diacetylafzelin. The known compounds were zerumbone, zerumbone epoxide, diferuloylmethane, feruloyl-p-coumaroylmethane and di-p-coumaroylmethane. Several substituted cinnamoylmethanes were synthesized and tested for cytotoxic properties. Among these were tricinnamoylmethane and triferuloylmethane. The structures were elucidated mainly by spectroscopic methods and ¹³C NMR data are given.     

Ein flavobacterium (Flavobacterium buchneri n. sp.) als endosymbiont zweier sauginfusorien

Zusammenfassung Die beiden auf verschiedenen Hydrophiliden lebenden Sauginfusorien Discophrya speciosa Lachmann und D. guilcherae Matthes beherbergen in ihrem Endoplasma zahllose Bakterien. Die gram-negativen Keime sind häufig paarweise aneinandergelagert und an ihren freien Enden zumeist zugespitzt. Auf der Oberfläche gallertiger Nährböden wachsen sie als runde, glänzende Kolonien von intensiv gelber Farbe. Auch extreme Schleimbildung tritt auf. Während die aus den Wirten direkt freigesetzten Stäbchen unbeweglich sind, zeigen die kultivierten Keime peritriche Begeißelung und Beweglichkeit. Aus dem reichen Material wurden zwei Stämme ausgewählt (A 1=D. speciosa, A 2=D. guilcherae), die zwar Größendifferenzen zeigen, aber in ihren biochemischen Leistungen (Bunte Reihe) völlig übereinstimmen. Die identischen Keime gehören dem. Genus Flavobacterium an. Wir nennen den neuen Organismus Flavobacterium buchneri n. sp. Der obligate Charakter der Besiedlung zwingt zur Annahme eines symbiontischen Verhältnisses zwischen den Partnern. Die biochemischen Befunde geben leider keinen Hinweis für das Motiv der Symbiose. Es ist wohl im ernährungsphysiologischen Bereich zu suchen. Da D. speciosa und D. guilcherae eng miteinander verwandt sind, darf man annehmen, daß bereits ihre Stammform mit unserem Flavobacterium in Symbiose lebte. Bei deren Erstbesiedlung müssen die Keime mit dem Beuteplasma in das räuberische Sauginfusor gelangt sein. Die Weitergabe der Symbionten an die Nachkommenschaft ist durch den Knospungsmodus zwangsläufig gewährleistet.

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Summary The two infusorian Suctoria Discophrya speciosa Lachmann and D. guilcherae Matthes, which live on various Hydrophilidae, contain numerous bacteria in their endoplasm. The gram-negative bacteria frequently arrange themselves in pairs with their free ends, in the majority of cases, tapered to points. They grow on the surface of the gelatinous culture medium as round shiny colonies which have an intense yellow color. An extreme formation of slime also occurs. The rods which are liberated from the host directly are non-motile while the cultivated bacteria show peritrich flagellation and motility. Two strains were selected from an abundance of material (A 1=D. speciosa and A 2=D. guilcherae) and they showed size differences; however, they were completely identical in their biochemical behavior. The identical bacteria belong to the genus Flavobacterium. We have named the new organism Flavobacterium buchneri n. sp. The obligate character of the infection forces us to assume that a symbiotic relationship exists between the partners. Unfortunately, the biochemical findings give no indication for the motive of the symbiosis. One probably has to look for the reason in the sphere of nutrition physiology. Since D. speciosa and D. guilcherae are closely related one may assume that their primitive ancestor already had a symbiotic relationship with our Flavobacterium. By the preceding we mean that the first infection takes place or occurs when the infusorian Suctoria suck the plasma and bacteria from the prey. The continuation of the symbiosis in the progeny is inevitably guaranted through the method of budding.

     

A new selective phage cloning vector, lambda 2001, with sites for XbaI, BamHI, HindIII, EcoRI, SstI and XhoI

An improved bacteriophage lambda cloning vector, lambda 2001, has been constructed. The phage includes a 34-bp polylinker oligonucleotide which introduces cleavage sites for XbaI, SstI, XhoI, EcoRI, HindIII and BamHI, and can accommodate 10-kb to 23-kb fragments. Inserts that destroy the BamHI or XhoI cloning sites may be recovered by excision at flanking sites in the polylinker sequence. Insertion of foreign DNA into lambda 2001 generates phage with a Spi- phenotype. The recombinant phage are able to grow on P2 lysogens but the parental vector phages are not. In the course of this work, the polylinker sequence was also introduced into M13mp8. This produced a new vector, M13mp12, with cloning sites for EcoRI, SmaI, XbaI, SstI, XhoI, BamHI, and HindIII.     

Bakers' yeast cultivation on by-products and wastes of potato and wheat starch production on a laboratory and pilot-plant scale

Saccharomyces cerevisiae was cultivated in a 10 litre laboratory stirred tank, an 80 litre laboratory airlift tower loop and a 4 m³ pilot-plant airlift tower loop reactor using by-products and wastes of potato and wheat starch production in batch and continuous cultures. Potato protein liquor, potato liquor retentate, potato liquor residue, and wheat process water were used as nutrients and glucose from the enzymatic conversion of potato starch as energy source. Besides the performance of the cultivation (cell concentrations, specific growth rates in the first (glucose) and second (ethanol) growth phases, productivities, yield coefficients), the qualities of the effluents (concentrations of phosphate, dissolved organic carbon, dissolved organic nitrogen, and chemical oxygen demand) were also determined in the different reactors as functions of the operational parameters. The optimal conditions were evaluated with regard to cultivation performance and effluent quality. These performances do not vary with the scale of the reactors. The performance of continuous cultures is considerably better than that of batch cultures.     

The Anti-Diabetic Drug Metformin Reduces BACE1 Protein Level by Interfering with the MID1 Complex

Alzheimer’s disease (AD), the most common form of dementia in the elderly, is characterized by two neuropathological hallmarks: senile plaques, which are composed of Aβ peptides, and neurofibrillary tangles, which are composed of hyperphosphorylated TAU protein. Diabetic patients with dysregulated insulin signalling are at increased risk of developing AD. Further, several animal models of diabetes show increased Aβ expression and hyperphosphorylated tau. As we have shown recently, the anti-diabetic drug metformin is capable of dephosphorylating tau at AD-relevant phospho-sites. Here, we investigated the effect of metformin on the main amyloidogenic enzyme BACE1 and, thus, on the production of Aβ peptides, the second pathological hallmark of AD. We find similar results in cultures of primary neurons, a human cell line model of AD and in vivo in mice. We show that treatment with metformin decreases BACE1 protein expression by interfering with an mRNA-protein complex that contains the ubiquitin ligase MID1, thereby reducing BACE1 activity. Together with our previous findings these results indicate that metformin may target both pathological hallmarks of AD and may be of therapeutic value for treating and/or preventing AD.     

Structural and biophysical determinants of single CaV3.1 and CaV3.2 T-type calcium channel inhibition by N2O

We investigated the biophysical mechanism of inhibition of recombinant T-type calcium channels Ca_V3.1 and Ca_V3.2 by nitrous oxide (N₂O). To identify functionally important channel structures, chimeras with reciprocal exchange of the N-terminal domains I and II and C-terminal domains III and IV were examined. In whole-cell recordings N₂O significantly inhibited Ca_V3.2, and – less pronounced – Ca_V3.1. A Ca_V3.2-prevalent inhibition of peak currents was also detected in cell-attached multi-channel patches. In cell-attached patches containing ≤3 channels N₂O reduced average peak current of Ca_V3.2 by decreasing open probability and open time duration. Effects on Ca_V3.1 were smaller and mediated by a reduced fraction of sweeps containing channel activity. Without drug, single Ca_V3.1 channels were significantly less active than Ca_V3.2. Chimeras revealed that domains III and IV control basal gating properties. Domains I and II, in particular a histidine residue within Ca_V3.2 (H191), are responsible for the subtype-prevalent N₂O inhibition. Our study demonstrates the biophysical (open times, open probability) and structural (domains I and II) basis of action of N₂O on Ca_V3.2. Such a fingerprint of single channels can help identifying the molecular nature of native channels. This is exemplified by a characterization of single channels expressed in human hMTC cells as functional homologues of recombinant Ca_V3.1.     

Using the ratio of means as the effect size measure in combining results of microarray experiments

Background  

Development of efficient analytic methodologies for combining microarray results is a major challenge in gene expression analysis. The widely used effect size models are thought to provide an efficient modeling framework for this purpose, where the measures of association for each study and each gene are combined, weighted by the standard errors. A significant disadvantage of this strategy is that the quality of different data sets may be highly variable, but this information is usually neglected during the integration. Moreover, it is widely known that the estimated standard deviations are probably unstable in the commonly used effect size measures (such as standardized mean difference) when sample sizes in each group are small.     

Heat acclimation does not alter rat mesenteric artery response to norepinephrine

Previous studieshave shown that heat acclimation raises the temperature threshold forheat-induced splanchnic vasoconstriction in the rat (W. Haddad and M. Horowitz. Thermal Balance in Health and Disease,Advances in Pharmacological Sciences. Basel:Birkhauser, 1994, p. 203-208; M. Shochina, W. Haddad, U. Meiri,and M. Horo-witz. J. Therm. Biol.21: 289-295, 1996). We tested the hypothesis that heat acclimationalters splanchnic resistance artery sensitivity to norepinephrine (NE).Male Sprague-Dawley rats (n = 5) were acclimated to 35°C ambient temperature for 5-8 wk. Controlrats (n = 5) were maintained at22-23°C ambient temperature for 5-7 wk. Small mesentericartery segments (2- to 3-mm length, 100- to 340-µm ID) were isolated,cannulated at both ends, and pressurized to 50 mmHg. Artery luminaldiameter was measured in response to cumulative doses of NE(10⁹ to10⁵ M) by using videomicroscopy. NE dose response was measured at 37 and 43°C bathtemperatures. There were no differences in constriction responses to NEbetween acclimated and control rat arteries at either 37 or 43°C.We conclude that acclimation does not alter rat mesenteric arterysensitivity to NE.