Anna J. Podhajska

Genotyping of bacteria belonging to the former Erwinia genus by PCR-RFLP analysis of a recA gene fragment.

Genotypic characterization, based on the analysis of restriction fragment length polymorphism of the recA gene fragment PCR product (recA PCR-RFLP), was performed on members of the former Erwinia genus. PCR primers deduced from published recA gene sequences of Erwinia carotovora allowed the amplification of an approximately 730 bp DNA fragment from each of the 19 Erwinia species tested. Amplified recA fragments were compared using RFLP analysis with four endonucleases (AluI, HinfI, TasI and Tru1I), allowing the detection of characteristic patterns of RFLP products for most of the Erwinia species. Between one and three specific RFLP groups were identified among most of the species tested (Erwinia amylovora, Erwinia ananas, Erwinia cacticida, Erwinia cypripedii, Erwinia herbicola, Erwinia mallotivora, Erwinia milletiae, Erwinia nigrifluens, Erwinia persicina, Erwinia psidii, Erwinia quercina, Erwinia rhapontici, Erwinia rubrifaciens, Erwinia salicis, Erwinia stewartii, Erwinia tracheiphila, Erwinia uredovora, Erwinia carotovora subsp. atroseptica, Erwinia carotovora subsp. betavasculorum, Erwinia carotovora subsp. odorifera and Erwinia carotovora subsp. wasabiae). However, in two cases, Erwinia chrysanthemi and Erwinia carotovora subsp. carotovora, 15 and 18 specific RFLP groups were detected, respectively. The variability of genetic patterns within these bacteria could be explained in terms of their geographic origin and/or wide host-range. The results indicated that PCR-RFLP analysis of the recA gene fragment is a useful tool for identification of species and subspecies belonging to the former Erwinia genus, as well as for differentiation of strains within E. carotovora subsp. carotovora and E. chrysanthemi.

Amplification of erbB-4 oncogene occurs less frequently than that of erbB-2 in primary human breast cancer.

ErbB-4 protein is a recently discovered member of the ErbB family. The role of ErbB-4 protein in mammary-gland tissue has not been definitively established. To date, the expression of erbB-4 in breast tissue has been determined in only a few cases and, to the best of our knowledge, its amplification has not been examined. We therefore used the double differential polymerase chain reaction (ddPCR) for determination of the amplification profile of erbB-4 and erbB-2, another gene from the ErbB family, in human primary breast cancer specimens. We examined the amplification of the genes in 20 normal breasts and 176 invasive breast cancer samples. Amplification of erbB-2 was detected in 19% and erbB-4 in 13% of the samples studied. Co-amplification of the two oncogenes was found in only five out of 176 samples. Human breast cancer-derived cell lines in most cases overexpress both erbB-2 and erbB-4 (Beerli et al., 1995. Mol. Cell Biol. 15, 6496-6505; Han et al., 1995. Proc. Natl. Acad. Sci. USA 92, 9747-9751), but data on separate erbB-2 overexpression, without overexpression of erbB-4, were also reported (Wosikowski et al., 1997. Clin. Cancer Res. 3, 2405-2414). At the gene level, we found that co-amplification of the genes in the case of human breast cancer is rare. Moreover, an inverse association of the erbB-4 amplification with estrogen receptor activity and direct correlation with the tumor size were found. Due to these correlations, erbB-4 oncogene amplification can be assumed to be of prognostic or predictive value in the diagnosis of breast cancer.

Protoporphyrin IX Interacts with Wild-type p53 Protein in Vitro and Induces Cell Death of Human Colon Cancer Cells in a p53-dependent and -independent Manner

Photodynamic therapy (PDT) of cancer is an alternative treatment for tumors resistant to chemo- and radiotherapy. It induces cancer cell death mainly through generation of reactive oxygen species by a laser light-activated photosensitizer. It has been suggested that the p53 tumor suppressor protein sensitizes some human cancer cells to PDT. However, there is still no direct evidence for this. We have demonstrated here for the first time that the photosensitizer protoporphyrin IX (PpIX) binds to p53 and disrupts the interaction between p53 tumor suppressor protein and its negative regulator HDM2 in vitro and in cells. Moreover, HCT116 colon cancer cells exhibited a p53-dependent sensitivity to PpIX in a dose-dependent manner, as was demonstrated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and fluorescence-activated cell sorter (FACS) analysis of cell cycle profiles. We have also observed induction of p53 target pro-apoptotic genes, e.g. puma (p53-up-regulated modulator of apoptosis), and bak in PpIX-treated cells. In addition, p53-independent growth suppression by PpIX was detected in p53-negative cells. PDT treatment (2 J/cm2) of HCT116 cells induced p53-dependent activation of pro-apoptotic gene expression followed by growth suppression and induction of apoptosis.

Hepatitis G virus: molecular organization, methods of detection, prevalence, and disease association.

This article reviews data on hepatitis G virus (HGV) prevalence and possible disease associations in various groups of patients. An important fraction of acute or chronic hepatitis cases probably have a viral etiology and are not attributable to known hepatitis viruses. Therefore, researchers continually are looking for new hepatitis viruses. Among the agents found are members of GB hepatitis viruses, including GB-C virus, or HGV. This review presents the history of the discovery of HGV, its molecular biology and some methods of detection; results of clinical and molecular studies of HGV infection also are discussed.

Identification of a DNA restriction-modification system in Pectobacterium carotovorum strains isolated from Poland

Aims:  Polish isolates of pectinolytic bacteria from the species Pectobacterium carotovorum were screened for the presence of a DNA restriction–modification (R–M) system.