Hepatic effects of <Emphasis Type="Italic">Cimicifuga racemosa</Emphasis> extract <Emphasis Type="Italic">in vivo</Emphasis> and <Emphasis Type="Italic">in vitro</Emphasis>

Extracts of Cimicifuga racemosa are used frequently for menopausal complaints. Cimicifuga is well tolerated but can occasionally cause liver injury. To assess hepatotoxicity of cimicifuga in more detail, ethanolic C. racemosa extract was administered orally to rats, and liver sections were analyzed by electron microscopy. Tests for cytotoxicity, mitochondrial toxicity and apoptosis/necrosis were performed using HepG2 cells. Mitochondrial toxicity was studied using isolated rat liver mitochondria. Microvesicular steatosis was found in rats treated with > 1,000 mg/kg [DOSAGE ERROR CORRECTED] body weight cimicifuga extract. In vitro, cytotoxicity was apparent at concentrations > or =75 microg/mL, and mitochondrial beta-oxidation was impaired at concentrations > or =10 microg/mL. The mitochondrial membrane potential was decreased at concentrations > or =100 microg/mL, and oxidative phosphorylation was impaired at concenq trations > or =300 microg/mL. The mechanism of cell death was predominantly apoptosis. C. racemosa exerts toxicity in vivo and in vitro, eventually resulting in apoptotic cell death. The results are compatible with idiosyncratic hepatotoxicity as observed in patients treated with cimicifuga extracts.     

Redundant and unique roles of coronin proteins in <Emphasis Type="Italic">Dictyostelium</Emphasis>

Dictyostelium discoideum harbors a short (CRN12) and a long coronin (CRN7) composed of one and two beta-propellers, respectively. They are primarily present in the cell cortex and cells lacking CRN12 (corA ⁻) or CRN7 (corB ⁻) have defects in actin driven processes. We compared the characteristics of a mutant cell line (corA ⁻ /corB ⁻) lacking CRN12 and CRN7 with the single mutants focusing on cytokinesis, phagocytosis, chemotaxis and development. Cytokinesis, uptake of small particles, and developmental defects were not enhanced in the corA ⁻ /corB ⁻ strain as compared to the single mutants, whereas motility and phagocytosis of yeast particles were more severely impaired. It appears that although both proteins affect the same processes they do not act in a redundant manner. Rather, they often act antagonistically, which is in accordance with their proposed roles in the actin cytoskeleton where CRN12 acts in actin disassembly whereas CRN7 stabilizes actin filaments and protects them from disassembly.     

Molecular neurophysiology of taste in <Emphasis Type="Italic">Drosophila</Emphasis>

The recent identification of candidate receptor genes for sweet, umami and bitter taste in mammals has opened a door to elucidate the molecular and neuronal mechanisms of taste. Drosophila provides a suitable system to study the molecular, physiological and behavioral aspects of taste, as sophisticated molecular genetic techniques can be applied. A gene family for putative gustatory receptors has been found in the Drosophila genome. We discuss here current knowledge of the gustatory physiology of Drosophila. Taste cells in insects are primary sensory neurons whereupon each receptor neuron responds to either sugar, salt or water. We found that particular tarsal gustatory sensilla respond to bitter compounds. Electrophysiological studies indicate that gustatory sensilla on the labellum and tarsi are heterogeneous in terms of their taste sensitivity. Determination of the molecular bases for this heterogeneity could lead to an understanding of how the sensory information is processed in the brain and how this in turn is linked to behavior.Received 12 May 2003; received after revision 9 June 2003; accepted 13 June 2003     

Cellulase genes from the parabasalian symbiont <Emphasis Type="Italic">Pseudotrichonympha grassii</Emphasis> in the hindgut of the wood-feeding termite <Emphasis Type="Italic">Coptotermes formosanus</Emphasis>

Cellulase genes of Pseudotrichonympha grassii (Hypermastigida: Eucomonymphidae), the symbiotic flagellate in the hindgut of the wood-feeding termite Coptotermes formosanus, were isolated and characterized. The nucleotide sequences of the major cellulase component in the hindgut of C. formosanus were determined based on its N-terminal amino acid sequence. The five isolated nucleotide sequences (PgCBH-homos) had an open reading frame of 1350 bp showing similarity to catalytic domains of glycoside hydrolase family (GHF) 7 members, and primary structure comparison with GHF7 members whose tertiary structures are well-characterized revealed the overall similarity between PgCBH-homo and the catalytic domain of a processive cellulase Cel7A (formerly CBHI) from the aerobic fungus Trichoderma reesei. Functional expression of PgCBH-homos in Escherichia coli, using the carboxymethylcellulose-Congo red assay, demonstrated the actual cellulolytic activity of PgCBH-homo. RT-PCR showed that PgCBH-homos were expressed, from the three flagellates in the hindgut, specifically in P. grassii. Received 10 July 2002; accepted 26 July 2002 RID="*" ID="*"Corresponding author.     

<Emphasis Type="Italic">LAPTM4A</Emphasis> interacts with <Emphasis Type="Italic">hOCT2</Emphasis> and regulates its endocytotic recruitment

Human organic cation transporter 2 (hOCT2) is involved in the transport of endogenous and exogenous organic cations mainly in cells of the kidney and the brain. Here, we focus on the regulation of hOCT2 by direct protein–protein interaction. Screening within a mating-based split-ubiquitin-yeast-two-hybrid system (mBSUS) revealed the lysosomal-associated protein transmembrane 4 alpha (LAPTM4A) as a potential interacting protein. Interaction of LAPTM4A and hOCT2 was confirmed by pulldown assays, FRET microscopy analysis and immunofluorescence microscopy. Functionally, overexpression of LAPTM4A significantly decreased ASP⁺ uptake in HEK293 cells stably transfected with hOCT2, suggesting a negative regulation of hOCT2-mediated transport. Furthermore, overexpression of LAPTM4A leads to a significantly decreased hOCT2 plasma membrane expression in surface biotinylation experiments. In addition, significant expression of LAPTM4A in human kidney was demonstrated by immunoblotting and immunofluorescence.     

Fatty acid metabolism in <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis>

Peroxisomes are essential subcellular organelles involved in a variety of metabolic processes. Their importance is underlined by the identification of a large group of inherited diseases in humans in which one or more of the peroxisomal functions are impaired. The yeast Saccharomyces cerevisiae has been used as a model organism to study the functions of peroxisomes. Efficient oxidation of fatty acids does not only require the participation of peroxisomal enzymes but also the active involvement of other gene products. One group of important gene products in this respect includes peroxisomal membrane proteins involved in metabolite transport. This overview discusses the various aspects of fatty acid -oxidation in S. cerevisiae. Addressed are the various enzymes and their particular functions as well as the various transport mechanisms to take up fatty acids into peroxisomes or to export the -oxidation products out of the peroxisome to mitochondria for full oxidation to CO₂ and H₂O.Received 19 February 2003; received after revision 27 March 2003; accepted 27 March 2003     

High affinity recognition of a <Emphasis Type="Italic">Phytophthora</Emphasis> protein by <Emphasis Type="Italic">Arabidopsis</Emphasis> via an RGD motif

The RGD tripeptide sequence, a cell adhesion motif present in several extracellular matrix proteins of mammalians, is involved in numerous plant processes. In plant-pathogen interactions, the RGD motif is believed to reduce plant defence responses by disrupting adhesions between the cell wall and plasma membrane. Photoaffinity cross-linking of [¹²⁵I]-azido-RGD heptapeptide in the presence of purified plasma membrane vesicles of Arabidopsis thaliana led to label incorporation into a single protein with an apparent molecular mass of 80 kDa. Incorporation could be prevented by excess RGD peptides, but also by the IPI-O protein, an RGD-containing protein secreted by the oomycete plant pathogen Phytophthora infestans. Hydrophobic cluster analysis revealed that the RGD motif of IPI-O (positions 53–56) is readily accessible for interactions. Single amino acid mutations in the RGD motif in IPI-O (of Asp⁵⁶ into Glu or Ala) resulted in the loss of protection of the 80-kDa protein from labelling. Thus, the interaction between the two proteins is mediated through RGD recognition and the 80-kDa RGD-binding protein has the characteristics of a receptor for IPI-O. The IPI-O protein also disrupted cell wall-plasma membrane adhesions in plasmolysed A. thaliana cells, whereas IPI-O proteins mutated in the RGD motif (D56A and D56E) did not.Received 23 October 2003; received after revision 5 December 2003; accepted 12 December 2003     

Comparing peripheral glial cell differentiation in <Emphasis Type="Italic">Drosophila</Emphasis> and vertebrates

In all complex organisms, the peripheral nerves ensure the portage of information from the periphery to central computing and back again. Axons are in part amazingly long and are accompanied by several different glial cell types. These peripheral glial cells ensure electrical conductance, most likely nuture the long axon, and establish and maintain a barrier towards extracellular body fluids. Recent work has revealed a surprisingly similar organization of peripheral nerves of vertebrates and Drosophila. Thus, the genetic dissection of glial differentiation in Drosophila may also advance our understanding of basic principles underlying the development of peripheral nerves in vertebrates.     

A new lysozyme from the eastern oyster (<Emphasis Type="Italic">Crassostrea virginica</Emphasis>) indicates adaptive evolution of <Emphasis Type="Italic">i</Emphasis>-type lysozymes

A new lysozyme (cv-lysozyme 2) with a MALDI molecular mass of 12 984.6 Da was purified from crystalline styles and digestive glands of eastern oysters (Crassostrea virginica) and its cDNA sequenced. Quantitative real time RT-PCR detected cv-lysozyme 2 gene expression primarily in digestive gland tissues, and in situ hybridization located cv-lysozyme 2 gene expression in basophil cells of digestive tubules. Cv-lysozyme 2 showed high amino acid sequence similarity to other bivalve mollusk lysozymes, including cv-lysozyme 1, a lysozyme recently purified from C. virginica plasma. Differences between cv-lysozyme 2 and cv-lysozyme 1 molecular characteristics, enzymatic properties, antibacterial activities, distribution in the oyster body and site of gene expression indicate that the main role of cv-lysozyme 2 is in digestion. While showing that a bivalve mollusk employs different lysozymes for different functions, findings in this study suggest adaptive evolution of i type lysozymes for nutrition. Received 30 August 2006; received after revision 14 October 2006; accepted 6 November 2006     

Cellular microbiology of intracellular <Emphasis Type="Italic">Salmonella enterica</Emphasis>: functions of the type III secretion system encoded by <Emphasis Type="Italic">Salmonella</Emphasis> pathogenicity island 2

The facultative intracellular pathogen Salmonella enterica resides in a special membrane compartment of the host cell and modifies its host to achieve intracellular survival and proliferation. The type III secretion system encoded by Salmonella pathogenicity island 2 (SPI2) has a central role in the interference of intracellular Salmonella with host cell functions. SPI2 function affects antimicrobial defense mechanisms of the host, intracellular transport processes, integrity and function of the cytoskeleton and host cell death. These modifications are mediated by translocation of a large number of effector proteins by the SPI2 system. In this review, we summarize recent work on the cellular phenotypes related to SPI2 function and contribution of SPI2 effector proteins to these manipulations. These studies reveal a complex set of pathogenic interferences between intracellular Salmonella and its host cells.Received 11 June 2004; received after revision 8 July 2004; accepted 12 July 2004     

The role of the <Emphasis Type="Italic">trans</Emphasis>-Golgi network in varicella zoster virus biology

The task of assembling nascent virions presents a formidable challenge to large, enveloped DNA viruses such as varicella zoster virus (VZV). After parasitising the host cells compartmentalised biosynthetic machinery, viral constituents must be brought together in appropriate proportions for packaging and export. Recent evidence places the trans-Golgi network (TGN) in an orchestrating role with respect to the assembly, envelopment and egress of herpesviruses. This role accords with known functions of the TGN in the uninfected cell. The targeting of viral glycoproteins to the TGN appears to provide a crucial platform for viral assembly. Tegument proteins, interacting with the cytoplasmic domains of glycoproteins, in turn recruit nucleocapsids to the developing supramolecular array. Molecular studies are continually refining understanding of these processes, building upon elegant electron microscopic data. Knowledge of VZVs use of endogenous trafficking pathways from the TGN sheds light on important aspects of viral behaviour in vitro and in vivo.Received 22 June 2004; received after revision 22 August 2004; accepted 25 August 2004     

Neuroprotective effects of <Emphasis Type="Italic">Ginkgo biloba</Emphasis> extract

Ginkgo biloba extract has been therapeutically used for several decades to increase peripheral and cerebral blood flow as well as for the treatment of dementia. The extract contains multiple compounds such as flavonoids and terpenoids that are thought to contribute to its neuroprotective and vasotropic effects. In this review, we summarize the experimental results on the mechanism of neuroprotection induced by standardized extract of Ginkgo biloba leaves (EGb 761) and its constituents. The effects described mostly in animals include those on cerebral blood flow, neurotransmitter systems, cellular redox state and nitric oxide level. Furthermore, we discuss the current status of clinical trials as well as undesired side effects of EGb 761.Received 21 November 2002; received after revision 8 March 2003; accepted 17 March 2003     

The role of conjugative transposons in the <Emphasis Type="Italic">Enterobacteriaceae</Emphasis>

Although widely studied in Gram-positive Streptococci and in the Gram-negative Bacteroides, there is a scarcity of information on the occurrence and nature of conjugative transposon-like elements in the well-studied Enterobacteriaceae. In fact, some of the major reviews on conjugative transposons prior to 1996 failed to mention their occurrence in this group. Recently, their presence has been reported in Salmonella, Vibrio and Proteus species, and in some cases such as the SXT element in Vibrio and the IncJ group element CTnR391, there has been some molecular characterization. The elements thus far examined appear to be larger than the common Gram-positive conjugative transposons and to be mosaic in structure, with genes derived from several sources. Recent evidence suggests that in the Enterobacteriaceae the elements may be related to enteric pathogenicity islands. The evolution, distribution and role of these elements in the Enterobacteriaceae is discussed.     

The elusive engine in <Emphasis Type="Italic">Myxococcus xanthus</Emphasis> gliding motility

Bacterial motility is essential for chemotaxis, virulence and complex social interactions leading to biofilm and fruiting body formation. Although bacterial swimming in liquids with a flagellum is well understood, little is known regarding bacterial movements across solid surfaces. Gliding motility, one such mode of locomotion, has remained largely mysterious because cells move smoothly along their long axis in the absence of any visible organelle. In this review, I discuss recent evidence that focal adhesion systems mediate gliding motility in the social bacterium Myxococcus xanthus and combine this evidence with previous work to suggest a new working hypothesis inspired from knowledge in apicomplexan parasites. I then propose experimental directions to test the model and compare it to other pre-existing models. Finally, evidence on gliding mechanisms of selected organisms are presented to ask whether some features of the model have precedents in other bacteria and whether this complex biological process could be explained by a single mechanism or involves multiple distinct mechanisms. Received 12 April 2007; received after revision 8 June 2007; accepted 27 June 2007     

<Emphasis Type="Italic">The Art of War:</Emphasis> Innate and adaptive immune responses

Research over the last several years has greatly advanced our understanding of the mechanisms by which the immune system functions. There exist two main branches of immunity, termed innate and adaptive immunity. Innate immunity uses the genetic memory of germline-encoded receptors to recognize the molecular patterns of common pathogens. Adaptive immunity, akin to somatic memory, is a complex system by which the body learns to recognize a pathogens unique antigens and builds an antigen specific response to destroy it. The effective development of the overall immune response depends on careful interplay and regulation between innate and adaptive immunity. Here we review our current understanding of how these integrated systems distinguish targets against which a response is appropriate and neutralize potentially pathogenic challenges.Received 8 May 2003; accepted 2 June 2003     

The DnaK/ClpB chaperone system from <Emphasis Type="Italic">Thermus thermophilus</Emphasis>

Proteins of thermophilic organisms are adapted to remain well structured and functional at elevated temperatures. Nevertheless like their 'cousins' that reside at medium temperatures, they require the assistance of molecular chaperones to fold properly and prevent aggregation. This review compares structural and functional properties of the DnaK/ClpB systems of Thermus thermophilus and, mainly, Escherichia coli (Dnak_Tth and Dnak_Eco). Many elemental properties of these systems remain conserved. However, in addition to a general increase of the thermal stability of its components, the Dnak_Tth system shows profound differences in its regulation, and genetic as well as oligomeric organization. Whether these differences are unique or represent general strategies of adaptation to life at elevated temperatures remains to be clarified. RID="*" ID="*"Corresponding author.     

A small chimerically bifunctional monomeric protein: <Emphasis Type="Italic">Tapes japonica</Emphasis> lysozyme

The lysozyme of the marine bilave Tapes japonica (13.8 kDa) is a novel protein. The protein has 46% homology with the destabilase from medicinal leech that has isopeptidase activity. Based on these data, we confirmed hydrolysis activity of T. japonica lysozyme against three substrates: L--Glu-pNA, D--Glu-pNA, and -(-Glu)-L-Lys. The optimal pH of chitinase and isopeptidase activity was 5.0 and 7.0, respectively. The isopeptidase activity was inhibited with serine protease inhibitor, but the lytic and chitinase activities were not. Moreover, only isopeptidase activity is decreased by lyophilization, but lytic and chitinase activities were not. We conclude that T. japonica lysozyme expresses isopeptidase and chitinase activity at different active sites.Received 25 February 2003; received after revision 29 May 2003; accepted 12 June 2003     

Sex-peptides: seminal peptides of the <Emphasis Type="Italic">Drosophila</Emphasis> male

Mating affects the reproductive behaviour of insect females: the egg-laying rate increases and courting males are rejected. These post-mating responses are induced mainly by seminal fluid. In Drosophila melanogaster, males transfer two peptides (sex-peptides, = Sps) that reduce receptivity and elicit increased egg laying in their mating partners. Similarities in the open reading frames of the genes suggest that they have arisen by gene duplication. In females, Sps bind to specific sites in the central and peripheral nervous system, and to the genital tract. The binding proteins of the nervous system and genital tract are membrane proteins, but they differ molecularly. The former protein is proposed to be a receptor located at the top of a signalling cascade leading to the two post-mating responses, whereas the latter is a carrier protein moving Sps from the genital tract into the haemolymph. Sps bind to sperm. Together with sperm they are responsible for the persistence of the two post-mating responses. But Sps are the molecular basis of the sperm effect; sperm is merely the carrier.Received 10 February 2003; received after revision 25 April 2003; accepted 1 May 2003This article is dedicated to the 85th birthday of the discover of the sex-peptide, Prof. Dr. Pei Shen Chen, Zoological Institute, University of Zürich, Switzerland. P. S. Chen has served on the Editorial Board of Experientia (now CMLS) from 1974 to 1988.