Pairing of P1 plasmid partition sites by ParB

The mechanisms by which bacterial plasmids and chromosomes are partitioned are largely obscure, but it has long been assumed that the molecules to be separated are initially paired, as are sister chromatids in mitosis. We offer in vivo evidence that the partition protein ParB encoded by the bacterial plasmid P1 can pair cis-acting partition sites of P1 inserted in a small, multicopy plasmid. ParB was shown previously to be capable of extensive spreading along DNA flanking the partition sites. Experiments in which ParB spreading was constrained by physical roadblocks suggest that extensive spreading is not required for the pairing process.     

4-Deoxyraputindole C induces cell death and cell cycle arrest in tumor cell lines

Several molecules extracted from natural products exhibit different biological activities, such as ion channel modulation, activation of signaling pathways, and anti-inflammatory or antitumor activity. In this study, we tested the antitumor ability of natural compounds extracted from the Raputia praetermissa plant. Among the compounds tested, an alkaloid, here called compound S4 (4-Deoxyraputindole C), showed antitumor effects against human tumor lineages. Compound S4 was the most active against Raji, a lymphoma lineage, promoting cell death with characteristics that including membrane permeabilization, dissipation of the mitochondrial potential, increased superoxide production, and lysosomal membrane permeabilization. The use of cell death inhibitors such as Z-VAD-FMK (caspase inhibitor), necrostatin-1 (receptor-interacting serine/threonine-protein kinase 1 inhibitor), E-64 (cysteine peptidases inhibitor), and N-acetyl- L -cysteine (antioxidant) did not decrease compound S4-dependent cell death. Additionally, we tested the effect of cellular activity on adherent human tumor cells. The highest reduction of cellular activity was observed in A549 cells, a lung carcinoma lineage. In this lineage, the effect on the reduction of the cellular activity was due to cell cycle arrest, without plasma membrane permeabilization, loss of the mitochondrial potential or lysosomal membrane permeabilization. Compound S4 was able to inhibit cathepsin B and L by a nonlinear competitive (negative co-operativity) and simple-linear competitive inhibitions, respectively. The potency of inhibition was higher against cathepsin L. Compound S4 promoted cell cycle arrest at G ₀ and G ₂ phase, and increase the expression of p16 and p21 proteins. In conclusion, compound S4 is an interesting molecule against cancer, promoting cell death in the human lymphoma lineage Raji and cell cycle arrest in the human lung carcinoma lineage A549.     

Lead optimization of 7-benzyloxy 2-(4'-pyridylmethyl)thio isoflavone aromatase inhibitors

Aromatase, the enzyme responsible for estrogen biosynthesis, is a particularly attractive target in the treatment of hormone-dependent breast cancer. The synthesis and biological evaluation of a series of 2-(4'-pyridylmethyl)thio, 7-alkyl- or aryl-substituted isoflavones as potential aromatase inhibitors are described. The isoflavone derivatives demonstrate IC(50) values from 79 to 553 nM and compete with the endogenous substrate, androstenedione. Data supporting the ability of these analogs to suppress aromatase enzyme activity in the SK-BR-3 breast cancer cell line are also presented.     

Disruption of the langerin/CD207 gene abolishes Birbeck granules without a marked loss of Langerhans cell function

Langerin is a C-type lectin expressed by a subset of dendritic leukocytes, the Langerhans cells (LC). Langerin is a cell surface receptor that induces the formation of an LC-specific organelle, the Birbeck granule (BG). We generated a langerin(-/-) mouse on a C57BL/6 background which did not display any macroscopic aberrant development. In the absence of langerin, LC were detected in normal numbers in the epidermis but the cells lacked BG. LC of langerin(-/-) mice did not present other phenotypic alterations compared to wild-type littermates. Functionally, the langerin(-/-) LC were able to capture antigen, to migrate towards skin draining lymph nodes, and to undergo phenotypic maturation. In addition, langerin(-/-) mice were not impaired in their capacity to process native OVA protein for I-A(b)-restricted presentation to CD4(+) T lymphocytes or for H-2K(b)-restricted cross-presentation to CD8(+) T lymphocytes. langerin(-/-) mice inoculated with mannosylated or skin-tropic microorganisms did not display an altered pathogen susceptibility. Finally, chemical mutagenesis resulted in a similar rate of skin tumor development in langerin(-/-) and wild-type mice. Overall, our data indicate that langerin and BG are dispensable for a number of LC functions. The langerin(-/-) C57BL/6 mouse should be a valuable model for further functional exploration of langerin and the role of BG.     

Die thermischen Eigenschaften der faserig strukturierten Gebilde des tierischen Bewegungsapparates

Ohne Zusammenfassung     

The Role of Topoisomerase II in Meiotic Chromosome Condensation and Segregation in Schizosaccharomyces pombe

Topoisomerase II is able to break and rejoin double-strand DNA. It controls the topological state and forms and resolves knots and catenanes. Not much is known about the relation between the chromosome segregation and condensation defects as found in yeast top2 mutants and the role of topoisomerase II in meiosis. We studied meiosis in a heat-sensitive top2 mutant of Schizosaccharomyces pombe. Topoisomerase II is not required until shortly before meiosis I. The enzyme is necessary for condensation shortly before the first meiotic division but not for early meiotic prophase condensation. DNA replication, prophase morphology, and dynamics of the linear elements are normal in the top2 mutant. The top2 cells are not able to perform meiosis I. Arrested cells have four spindle pole bodies and two spindles but only one nucleus, suggesting that the arrest is nonregulatory. Finally, we show that the arrest is partly solved in a top2 rec7 double mutant, indicating that topoisomerase II functions in the segregation of recombined chromosomes. We suggest that the inability to decatenate the replicated DNA is the primary defect in top2. This leads to a loss of chromatin condensation shortly before meiosis I, failure of sister chromatid separation, and a nonregulatory arrest.     

SATCHMO: sequence alignment and tree construction using hidden Markov models

MOTIVATION:Aligning multiple proteins based on sequence information alone is challenging if sequence identity is low or there is a significant degree of structural divergence. We present a novel algorithm (SATCHMO) that is designed to address this challenge. SATCHMO simultaneously constructs a tree and a set of multiple sequence alignments, one for each internal node of the tree. The alignment at a given node contains all sequences within its sub-tree, and predicts which positions in those sequences are alignable and which are not. Aligned regions therefore typically get shorter on a path from a leaf to the root as sequences diverge in structure. Current methods either regard all positions as alignable (e.g. ClustalW), or align only those positions believed to be homologous across all sequences (e.g. profile HMM methods); by contrast SATCHMO makes different predictions of alignable regions in different subgroups. SATCHMO generates profile hidden Markov models at each node; these are used to determine branching order, to align sequences and to predict structurally alignable regions. RESULTS: In experiments on the BAliBASE benchmark alignment database, SATCHMO is shown to perform comparably to ClustalW and the UCSC SAM HMM software. Results using SATCHMO to identify protein domains are demonstrated on potassium channels, with implications for the mechanism by which tumor necrosis factor alpha affects potassium current. AVAILABILITY: The software is available for download from http://www.drive5.com/lobster/index.htm     

Stereotactic Body Radiation Therapy for Primary and Metastatic Liver Tumors

OBJECTIVES: The full potential of stereotactic body radiation therapy (SBRT), in the treatment of unresectable intrahepatic malignancies, has yet to be realized as our experience is still limited. Thus, we evaluated SBRT outcomes for primary and metastatic liver tumors, with the goal of identifying factors that may aid in optimization of therapy. METHODS: From2005 to 2010, 62 patients with 106 primary and metastatic liver tumors were treated with SBRT to a median biologic effective dose (BED) of 100 Gy (42.6-180). The majority of patients received either three (47%) or five fractions (48%). Median gross tumor volume (GTV) was 8.8 cm³ (0.2-222.4). RESULTS: With a median followup of 18 months (0.46-46.8), freedom from local progression (FFLP) was observed in 97 of 106 treated tumors, with 1- and 2-year FFLP rates of 93% and 82%. Median overall survival (OS) for all patients was 25.2 months, with 1- and 2-year OS of 81%and 52%. Neither BED nor GTV significantly predicted for FFLP. Local failure was associated with a higher risk of death [hazard ratio (HR) = 5.1, P = .0007]. One Child-Pugh Class B patient developed radiationinduced liver disease. There were no other significant toxicities. CONCLUSIONS: SBRT provides excellent local control for both primary and metastatic liver lesions with minimal toxicity. Future studies should focus on appropriate selection of patients and on careful assessment of liver function to maximize both the safety and efficacy of treatment.     

Pinealectomy blocks modulation of active avoidance by central vasopressin application in rats

The inter-relationship between central vasopressin and the pineal gland in the modulation of active avoidance behavior was investigated. In sham-operated (SO) rats, intracerebroventricular (i.c.v) application of 10 ng arginine vasopressin (AVP) after both the last acquisition and the first extinction trials prolonged the extinction of the active avoidance response; application of 50 ng of the V1 antagonist, d(CH2)5Tyr(Me)AVP (AAVP) was without effect in both experiments. In contrast to the SO in pinealectomized (PX) rats neither AVP nor AAVP influenced the extinction of the avoidance response. Intraseptal infusion of 200 pg AVP or 5 ng AAVP either after the last acquisition or the first extinction trial was without effect in both SO and PX rats. Comparison of the acquisition trials revealed no differences between SO and PX rats.