Presequence Acquisition During Secondary Endocytobiosis and thePossible Role of Introns

Targeting of nucleus-encoded proteins into chloroplasts is mediated by N-terminal presequences. During evolution of plastids from formerly free-living cyanobacteria by endocytobiosis, genes for most plastid proteins have been transferred from the plastid genome to the nucleus and subsequently had to be equipped with such plastid targeting sequences. So far it is unclear how the gene domains coding for presequences and the respective mature proteins may have been assembled. While land plant plastids are supposed to originate from a primary endocytobiosis event (a prokaryotic cyanobacterium was taken up by a eukaryotic cell), organisms with secondary plastids like diatoms experienced a second endocytobiosis step involving a eukaryotic alga taken up by a eukaryotic host cell. In this group of algae, apparently most genes encoding chloroplast proteins have been transferred a second time (from the nucleus of the endosymbiont to the nucleus of the secondary host) and thus must have been equipped with additional targeting signals. We have analyzed cDNAs and the respective genomic DNA fragments of seven plastid preproteins from the diatom Phaeodactylum tricornutum. In all of these genes we found single spliceosomal introns, generally located within the region coding for the N-terminal plastid targeting sequences or shortly downstream of it. The positions of the introns can be related to the putative phylogenetic histories of the respective genes, indicating that the bipartite targeting sequences in these secondary algae might have evolved by recombination events via introns.The nucleotide sequences have been deposited at Genbank under accession numbers AY191862, AY191863, AY191864, AY191865, AY191866, AY191867, and AY191868.     

Septicaemia associated with an Aerococcus viridans infection in immunodeficient mice

This report describes a case series of septicaemia caused by infection with Aerococcus viridans in immunodeficient NOD/LtSz-Prkdc(scid) (NOD/SCID) mice. During a period of 3 weeks more than 40 animals died or became ill with clinical signs of ruffled coat, weight loss, laboured breeding, and distended abdomen. At necropsy it was found that the animals displayed symptoms of sepsis with widespread abscesses in the liver, heart, lungs or pyogenic peritonitis. A Gram-positive coccus was isolated in pure culture from the abscesses or peritoneum from affected animals. According to phenotypic and phylogenetic characterization, the isolate was identified as A. viridans. This is the first report of a spontaneous outbreak of septicaemia caused by A. viridans infection in immunodeficient laboratory mice and we conclude that A. viridans should be considered as a pathogen in immunodeficient mice.     

Antiangiogenic Arming of an Oncolytic Vaccinia Virus Enhances Antitumor Efficacy in Renal Cell Cancer Models

Oncolytic vaccinia viruses have shown compelling results in preclinical cancer models and promising preliminary safety and antitumor activity in early clinical trials. However, to facilitate systemic application it would be useful to improve tumor targeting and antitumor efficacy further. Here we report the generation of vvdd-VEGFR-1-Ig, a targeted and armed oncolytic vaccinia virus. Tumor targeting was achieved by deletion of genes for thymidine kinase and vaccinia virus growth factor, which are necessary for replication in normal but not in cancer cells. Given the high vascularization typical of kidney cancers, we armed the virus with the soluble vascular endothelial growth factor (VEGF) receptor 1 protein for an antiangiogenic effect. Systemic application of high doses of vvdd-VEGFR-1-Ig resulted in cytokine induction in an immunocompromised mouse model. Upon histopathological analysis, splenic extramedullary hematopoiesis was seen in all virus-injected mice and was more pronounced in the vvdd-VEGFR-1-Ig group. Analysis of the innate immune response after intravenous virus injection revealed high transient and dose-dependent cytokine elevations. When medium and low doses were used for intratumoral or intravenous injection, vvdd-VEGFR-1-Ig exhibited a stronger antitumor effect than the unarmed control. Furthermore, expression of VEGFR-1-Ig was confirmed, and a concurrent antiangiogenic effect was seen. In an immunocompetent model, systemic vvdd-VEGFR-1-Ig exhibited superior antitumor efficacy compared to the unarmed control virus. In conclusion, the targeted and armed vvdd-VEGFR-1-Ig has promising anticancer activity in renal cell cancer models. Extramedullary hematopoiesis may be a sensitive indicator of vaccinia virus effects in mice.In 2002 renal cell cancer accounted for more than 200,000 cases and 100,000 deaths worldwide (33). Unfortunately, chemotherapy, radiotherapy, and immunotherapy yield low response rates (9, 17) in this cancer type. Thus, prognosis for patients is poor, especially when the disease is metastatic, as median survival is only 8 months (19). Although recently approved drugs, such as sorafenib, sunitinib, temsirolimus, and bevacizumab, have provided additional tools for treatment of renal cell cancer (7), they are usually not curative, and thus new treatment approaches are needed.Oncolytic vaccinia viruses are promising agents for cancer treatment and have shown compelling results in preclinical tumor models (40, 42, 45). Moreover, good safety and preliminary evidence of antitumor efficacy were seen in phase 1 clinical trials (22, 26, 32). Vaccinia virus has a strong oncolytic effect due to its fast replication cycle (45) and a high innate tropism to cancer tissue (34). Tumor targeting can be further improved by deleting vaccinia virus genes that are necessary for replication in normal cells but not in cancer cells. For example, deletions of either thymidine kinase (TK) or vaccinia virus growth factor (VGF) or both have been shown to reduce pathogenicity compared to wild-type virus (3, 5, 27). To enhance antitumor potency, oncolytic vaccinia viruses can be armed with therapeutic transgenes, such as immunostimulatory factors (26) or suicide genes (14, 16, 35). With regard to kidney cancer, an arming approach with antiangiogenenic molecules seems logical, considering the high vascularization characteristic of renal tumors (20).Vascular endothelial growth factor (VEGF) is a major player in tumor angiogenesis and is highly expressed in renal cell cancers (29). VEGF binds to the fms-like-tyrosine kinase receptor (flt-1 or VEGFR-1) and kinase domain region receptor (KDR or VEGFR-2) with high affinity (13). The soluble vascular endothelial growth factor receptor 1-Ig fusion protein (VEGFR-1-Ig) used in this study is derived from the membrane-bound VEGFR-1 and binds human and murine VEGF without inducing vascular endothelial cell mitogenesis (31). Blocking VEGF with this or closely related molecules has been shown to inhibit tumor growth in several cancer models (18, 21, 25, 39).Although tumor cell selective replication can be enhanced by deletion of TK and/or VGF to reduce pathogenicity (3, 5, 27), high doses of attenuated vaccinia virus may increase serum cytokine concentrations which parallel the onset of toxic events, as seen with other viral vectors (2, 38). The potential “early” toxicity associated with oncolytic vaccinia viruses has not been completely elucidated heretofore (36, 46).Given the high vascularization of renal cell cancers and the pressing need to generate new antitumor agents with increased safety and efficacy, we hypothesized that an oncolytic vaccinia virus targeted by TK and VGF deletions and armed with VEGFR-1-Ig would exhibit enhanced antitumor efficacy due to its antiangiogenic properties in renal cell cancer models compared to a nonarmed control virus, allowing reduction of the treatment dose.     

Does enteral nutrition of dietary polyunsaturated fatty acids promote oxidative stress and tumour growth in ductal pancreatic cancer?: Experimental trial in Syrian Hamster

BACKGROUND: Type and composition of dietary fat intake is supposed to play an important role in carcinogenesis. Thus we investigated the effects of n-3, n-6 and n-9 polyunsaturated fatty acids (PUFA) on oxidative stress (lipidperoxidation) and tumour growth in ductal pancreatic cancer. METHODS: Ninety male hamsters were randomized into 6 groups (gr.) (n=15) and allocated to 3 main dietary categories: gr. 1 and 2 received a standard high fat diet (SHF, rich in n-6 PUFA), while gr. 3 and 4 were fed with a diet containing a mixture of n-3, n-6 and n-9 PUFA (SMOF) and gr. 5 and 6 had free access to a diet rich in n-3 PUFA (FISH-OIL). Gr. 1, 3 and 5 received weekly subcutaneous (s.c.) injections of 10 mg N-nitrosobis-2-oxypropylamine (BOP)/kg body weight in order to induce ductal pancreatic adenocarcinoma. Healthy control gr. 2, 4 and 6 were treated with 0.5 ml 0.9% sodium chloride s.c. After 32 weeks all animals were sacrificed. Removed pancreata were weighed and analysed histologically and biochemically. Activities of glutathionperoxidase (GSH-Px), superoxiddismutase (SOD) and levels of lipidperoxidation were measured in samples of pancreatic carcinoma as well as in tumour-free pancreatic tissue. RESULTS: While different diets did not significantly alter the overall incidence of histologically proven pancreatic adenocarcinoma, the number of macroscopically visible tumours was decreased in the FISH-OIL-gr. CONCLUSION: Different diets did not significantly influence the incidence of histologically proven pancreatic adenocarcinoma. However, administration of a diet rich in n-3 PUFA (FISH-OIL) resulted in a decrease of macroscopically visible tumours, thus indicating its beneficial effects in respect to attenuation of tumour growth.     

The biological activity of the histidine-containing diketopiperazines cyclo(His-Ala) and cyclo(His-Gly)

Two cyclic dipeptides, cyclo(His-Ala) and cyclo(His-Gly,) were synthesized from their linear counterparts and their structures elucidated using standard elucidation techniques. Molecular modeling and predictive NMR results indicated that the majority of energetically favourable conformers adopted a boat conformation with respect to the diketopiperazine ring. Cyclo(His-Ala), at concentrations of 100 microM inhibited the growth, in vitro, of various cancer cell lines, including HT-29, MCF-7 and HeLa carcinoma cells while cyclo(His-Gly) inhibited the growth of MCF-7 cells. While the antibacterial potential of these two compounds was limited, both cyclic dipeptides significantly inhibited the growth of C. albicans. Both compounds at a concentration of 100 microM resulted in a decrease in heart rate, coronary flow rate and left ventricular systolic pressure in the isolated rat heart. Inhibition of thrombin, amounting to a 63.3% and 36.7% reduction in the rate of fibrin formation, was noted for cyclo(His-Ala) and cyclo(His-Gly), respectively. While cyclo(His-Ala) showed no notable effects on platelet aggregation, cyclo(His-Gly) significantly inhibited both pathways tested with greatest effects on thrombin-induced platelet aggregation, yielding an IC(50) of 0.0662 mM (R(2)=0.989). The results of the anticancer and hematological studies indicate that histidine-containing diketopiperazines have potential as a novel group of cytotoxic agents with antithrombotic effects.     

A biophysical approach to the optimisation of dendritic-tumour cell electrofusion

Electrofusion of tumour and dendritic cells (DCs) is a promising approach for production of DC-based anti-tumour vaccines. Although human DCs are well characterised immunologically, little is known about their biophysical properties, including dielectric and osmotic parameters, both of which are essential for the development of efficient electrofusion protocols. In the present study, human DCs from the peripheral blood along with a tumour cell line used as a model fusion partner were examined by means of time-resolved cell volumetry and electrorotation. Based on the biophysical cell data, the electrofusion protocol could be rapidly optimised with respect to the sugar composition of the fusion medium, duration of hypotonic treatment, frequency range for stable cell alignment, and field strengths of breakdown pulses triggering membrane fusion. The hypotonic electrofusion consistently gave a tumour-DC hybrid rate of up to 19%, as determined by counting dually labelled fluorescent hybrids in a microscope. This fusion rate is nearly twice as high as that usually reported in the literature for isotonic media. The experimental findings and biophysical approach presented here are generally useful for the development of efficient electrofusion protocols, especially for rare and valuable human cells.     

Polymer-supported ferrocenyl oxazolines for the catalyzed highly enantioselective phenyl transfer to aldehydes

A new chiral MeO-PEG-supported ferrocenyl oxazoline was synthesized and successfully employed in the enantioselective phenyl transfer to aldehydes. The products were obtained in high yields and with excellent enantioselectivities (up to 97% ee). Furthermore, the recovery of the ferrocene was facile, and catalyst efficiency was maintained in subsequent reactions.     

CRISPR/cas loci of type II Propionibacterium acnes confer immunity against acquisition of mobile elements present in type I P. acnes

Propionibacterium acnes is a skin commensal that occasionally acts as an opportunistic pathogen. The population structure of this species shows three main lineages (I-III). While type I strains are mainly associated with sebaceous follicles of human skin and inflammatory acne, types II and III strains are more often associated with deep tissue infections. We investigated the occurrence and distribution of the clustered regularly interspaced short palindromic repeats (CRISPR) in P. acnes, assessed their immunological memory, and addressed the question if such a system could account for type-specific properties of the species. A collection of 108 clinical isolates covering all known phylotypes of P. acnes was screened for the existence of CRISPR/cas loci. We found that CRISPR loci are restricted to type II P. acnes strains. Sequence analyses of the CRISPR spacers revealed that the system confers immunity to P. acnes-specific phages and to two mobile genetic elements. These elements are found almost exclusively in type I P. acnes strains. Genome sequencing of a type I P. acnes isolate revealed that one element, 54 kb in size, encodes a putative secretion/tight adherence (TAD) system. Thus, CRISPR/cas loci in P. acnes recorded the exposure of type II strains to mobile genetic elements of type I strains. The CRISPR/cas locus is deleted in type I strains, which conceivably accounts for their ability to horizontally acquire fitness or virulence traits and might indicate that type I strains constitute a younger subpopulation of P. acnes.     

Diversity array technology markers: genetic diversity analyses and linkage map construction in rapeseed (Brassica napus L.)

We developed Diversity Array Technology (DArT) markers for application in genetic studies of Brassica napus and other Brassica species with A or C genomes. Genomic representation from 107 diverse genotypes of B. napus L. var. oleifera (rapeseed, AACC genomes) and B. rapa (AA genome) was used to develop a DArT array comprising 11 520 clones generated using PstI/BanII and PstI/BstN1 complexity reduction methods. In total, 1547 polymorphic DArT markers of high technical quality were identified and used to assess molecular diversity among 89 accessions of B. napus, B. rapa, B. juncea, and B. carinata collected from different parts of the world. Hierarchical cluster and principal component analyses based on genetic distance matrices identified distinct populations clustering mainly according to their origin/pedigrees. DArT markers were also mapped in a new doubled haploid population comprising 131 lines from a cross between spring rapeseed lines 'Lynx-037DH' and 'Monty-028DH'. Linkage groups were assigned on the basis of previously mapped simple sequence repeat (SSRs), intron polymorphism (IP), and gene-based markers. The map consisted of 437 DArT, 135 SSR, 6 IP, and 6 gene-based markers and spanned 2288 cM. Our results demonstrate that DArT markers are suitable for genetic diversity analysis and linkage map construction in rapeseed.     

A multiparent advanced generation inter-cross population for genetic analysis in wheat

We present the first results from a novel multiparent advanced generation inter-cross (MAGIC) population derived from four elite wheat cultivars. The large size of this MAGIC population (1579 progeny), its diverse genetic composition and high levels of recombination all contribute to its value as a genetic resource. Applications of this resource include interrogation of the wheat genome and the analysis of gene-trait association in agronomically important wheat phenotypes. Here, we report the utilization of a MAGIC population for the first time for linkage map construction. We have constructed a linkage map with 1162 DArT, single nucleotide polymorphism and simple sequence repeat markers distributed across all 21 chromosomes. We benchmark this map against a high-density DArT consensus map created by integrating more than 100 biparental populations. The linkage map forms the basis for further exploration of the genetic architecture within the population, including characterization of linkage disequilibrium, founder contribution and inclusion of an alien introgression into the genetic map. Finally, we demonstrate the application of the resource for quantitative trait loci mapping using the complex traits plant height and hectolitre weight as a proof of principle.