Met receptor tyrosine kinase signaling induces secretion of the angiogenic chemokine interleukin-8/CXCL8 in pancreatic cancer

At diagnosis, the majority of pancreatic cancer patients present with advanced disease when curative resection is no longer feasible and current therapeutic treatments are largely ineffective. An improved understanding of molecular targets for effective intervention of pancreatic cancer is thus urgent. The Met receptor tyrosine kinase is one candidate implicated in pancreatic cancer. Notably, Met is over expressed in up to 80% of invasive pancreatic cancers but not in normal ductal cells correlating with poor overall patient survival and increased recurrence rates following surgical resection. However the functional role of Met signaling in pancreatic cancer remains poorly understood. Here we used RNA interference to directly examine the pathobiological importance of increased Met signaling for pancreatic cancer. We show that Met knockdown in pancreatic tumor cells results in decreased cell survival, cell invasion, and migration on collagen I in vitro. Using an orthotopic model for pancreatic cancer, we provide in vivo evidence that Met knockdown reduced tumor burden correlating with decreased cell survival and tumor angiogenesis, with minimal effect on cell growth. Notably, we report that Met signaling regulates the secretion of the pro-angiogenic chemokine interleukin-8/CXCL8. Our data showing that the interleukin-8 receptors CXCR1 and CXCR2 are not expressed on pancreatic tumor cells, suggests a paracrine mechanism by which Met signaling regulates interleukin-8 secretion to remodel the tumor microenvironment, a novel finding that could have important clinical implications for improving the effectiveness of treatments for pancreatic cancer.     

Can Soil Seed Banks Serve as Genetic Memory? A Study of Three Species with Contrasting Life History Strategies

We attempted to confirm that seed banks can be viewed as an important genetic reservoir by testing the hypothesis that standing (aboveground) plants represent a nonrandom sample of the seed bank. We sampled multilocus allozyme genotypes from three species with different life history strategies: Amaranthus retroflexus, Carduus acanthoides, Pastinaca sativa. In four populations of each species we analysed the extent to which allele and genotype frequencies vary in consecutive life history stages including the summer seed bank, which has been overlooked up to now. We compared the winter seed bank (i.e., seeds collected before the spring germination peak), seedlings, rosettes, the summer seed bank (i.e., seeds collected after the spring germination peak) and fruiting plants. We found that: (1) All three species partitioned most of their genetic diversity within life history stages and less among stages within populations and among populations. (2) All genetic diversity parameters, except for allele frequencies, were similar among all life history stages across all populations in different species. (3) There were differences in allele frequencies among life history stages at all localities in Amaranthus retroflexus and at three localities in both Carduus acanthoides and Pastinaca sativa. (4) Allele frequencies did not differ between the winter and summer seed bank in most Carduus acanthoides and Pastinaca sativa populations, but there was a marked difference in Amaranthus retroflexus. In conclusion, we have shown that the summer seed bank is not genetically depleted by spring germination and that a majority of genetic diversity remains in the soil through summer. We suggest that seed banks in the species investigated play an important role by maintaining genetic diversity sufficient for recovery rather than by accumulating new genetic diversity at each locality.     

The notochordal sheath in amphioxus--an ultrastructural and histochemical study

The notochord and notochordal sheath of 10 adult amphioxus were investigated ultrastructurally and histochemically. The notochord in amphioxus consists of parallel notochordal cells (plates) and each plate consists of parallel thicker and thinner fibrils and numerous profiles of smooth endoplasmic reticulum situated just beneath the cell membrane. Histochemical staining shows that the notochordal plates resemble neither the connective tissue notochordal sheath nor the typical muscular structure myotomes. The notochordal sheath has a complex three-layered organization with the outer, middle and inner layer The outer and middle layer are composed of collagen fibers of different thickness and course, that correspond to collagen type I and collagen type III in vertebrates, respectively, and the inner layer is amorphous, resembles basal lamina, and is closely attached to the notochord by hemidesmosome junctions. These results confirm the presence of collagen fibers and absence of elastic fibers in amphioxus.     

Enhanced antioxidant formula based on a selenium-supplemented carotenoid-producing yeast biomass

Carotenoid-producing yeast species such as Rhodotorula glutinis and Sporobolomyces roseus efficiently accumulated selenium from the growth medium. It was observed that incorporation of selenium into yeast cells during the growth inhibited production of beta-carotenoid and other carotenoid precursors (torularhodin and torulene). The yeasts with high content of the carotenoid pigments and selenium may be used for the preparation of a new type of antioxidant formula that could be directly applied for various human and animal diets. We have demonstrated that such a formula can only be produced by separate processes of the cultivation of red yeasts and a subsequent sorption of selenium into the cells.     

Impact of abscisic acid in overcoming the problem of albinism in horse chestnut androgenic embryos

Horse chestnut (Aesculus hyppocastanum L., Hyppocastanacea) is a relict species with a slow and complex reproductive cycle considered to have horticultural and medical importance. The cycle maybe circumvented via in vitro androgenesis. Androgenesis of horse chestnut was induced in microspores and anther culture on MS media. Some of the horse chestnut androgenic embryos were albinos. Addition of abscisic acid in media (in concentrations of 0.01, 0.1, 0.5, 1, 2, 5, 10, and 20 mg l^?1) with horse chestnut androgenic embryos has circumvented the reproduction cycle barriers. The best results were achieved on medium with the lowest abscisic acid concentration (0.01 mg l^?1) in microspore culture. The microspore culture proved to be a better model system for embryo production and albino embryo reduction than anther culture. Flow cytometry analysis after maturation treatments induced by ABA showed that 88 % of green embryos originating from microspore culture were haploid. However, 50 % of green embryos from anther culture were haploid. The remaining analyzed androgenic embryos, from both types of cultures were diploid.     

Impact of Protein Domains on PE_PGRS30 Polar Localization in Mycobacteria

PE_PGRS proteins are unique to the Mycobacterium tuberculosis complex and a number of other pathogenic mycobacteria. PE_PGRS30, which is required for the full virulence of M. tuberculosis (Mtb), has three main domains, i.e. an N-terminal PE domain, repetitive PGRS domain and the unique C-terminal domain. To investigate the role of these domains, we expressed a GFP-tagged PE_PGRS30 protein and a series of its functional deletion mutants in different mycobacterial species (Mtb, Mycobacterium bovis BCG and Mycobacterium smegmatis) and analysed protein localization by confocal microscopy. We show that PE_PGRS30 localizes at the mycobacterial cell poles in Mtb and M. bovis BCG but not in M. smegmatis and that the PGRS domain of the protein strongly contributes to protein cellular localization in Mtb. Immunofluorescence studies further showed that the unique C-terminal domain of PE_PGRS30 is not available on the surface, except when the PGRS domain is missing. Immunoblot demonstrated that the PGRS domain is required to maintain the protein strongly associated with the non-soluble cellular fraction. These results suggest that the repetitive GGA-GGN repeats of the PGRS domain contain specific sequences that contribute to protein cellular localization and that polar localization might be a key step in the PE_PGRS30-dependent virulence mechanism.     

Molecular variants of human papilloma viruses type 16 and 6 in women with different cytological results detected by RFLP analysis

HPV infections are common and the presence of the same high-risk type in cervical specimens can be due to reinfection or persistence. Persistent infection is the most important predictor for development of cervical carcinoma. The aim of this study was to validate PCR-RFLP with two sets of primers: MY09/MY11 that amplify a fragment of L1 and P1/P2 that amplify a fragment of E1 ORF. PCR product of MY09/MY11 was digested with a set of 6 restriction enzymes (RE) and PCR product of P1/P2 with a set of 12 RE. Cervical samples from 110 women patients of the University Gynecologic Clinic CHC Zagreb were analyzed. There were 98 (89.1%) PCR positive samples detected with P1/P2 primers, and 94 (85.5%) PCR positive samples detected with MY09/MY11 primers. Seven HPV types were detected with P1/P2-RFLP technique and 17 with MY09/MY11-RFLP PCR positive samples amplified with both primer pairs agreed with each other in 82 samples; 16 samples were only positive with P1/P2 and 12 samples were only positive by MY09/MY11. HPV 16 was detected in 39 samples with MY09/11-RFLP, out of these two variants (two different patterns) were found with P1/P2 using Dde I, Hae III and Eco I. HPV 6 was detected in 9 samples with MY09/11-RFLP, out of these two variants were found with P1/P2 using HinfI. Combining these two PCR-RFLP methods subtypes of HPV 16 and HPV 6 were detected.