Influence of molecular symmetry on strong-field ionization: Studies on ethylene, benzene, fluorobenzene, and chlorofluorobenzene

Using the molecular strong-field approximation we consider the effects of molecular symmetry on the ionization of molecules by a strong, linearly polarized laser pulse. Electron angular distributions and total ionization yields are calculated as a function of the relative orientation between the molecule and the laser polarization. Our studies focus on ethylene (C$_2$H$_4$), benzene (C$_6$H$_6$), fluorobenzene (C$_6$H$_5$F), and ortho chlorofluorobenzene (1,2 C$_6$H$_4$ClF), the molecules representing four different point groups. The results are compared with experiments, when available, and with the molecular tunneling theory appropriately extended to non-linear polyatomic molecules. Our investigations show that the orientational dependence of ionization yields is primarily determined by the nodal surface structure of the molecular orbitals.Comment: 13 pages, 10 figures. Submitted to Physical Review

Novel de novo BRCA2 mutation in a patient with a family history of breast cancer

<p>Abstract</p> <p>Background</p> <p><it>BRCA2 </it>germ-line mutations predispose to breast and ovarian cancer. Mutations are widespread and unclassified splice variants are frequently encountered. We describe the parental origin and functional characterization of a novel <it>de novo BRCA2 </it>splice site mutation found in a patient exhibiting a ductal carcinoma at the age of 40.</p> <p>Methods</p> <p>Variations were identified by denaturing high performance liquid chromatography (dHPLC) and sequencing of the <it>BRCA1 </it>and <it>BRCA2 </it>genes. The effect of the mutation on splicing was examined by exon trapping in COS-7 cells and by RT-PCR on RNA isolated from whole blood. The paternity was determined by single nucleotide polymorphism (SNP) microarray analysis. Parental origin of the <it>de novo </it>mutation was determined by establishing mutation-SNP haplotypes by variant specific PCR, while <it>de novo </it>and mosaic status was investigated by sequencing of DNA from leucocytes and carcinoma tissue.</p> <p>Results</p> <p>A novel <it>BRCA2 </it>variant in the splice donor site of exon 21 (nucleotide 8982+1 G→A/c.8754+1 G→A) was identified. Exon trapping showed that the mutation activates a cryptic splice site 46 base pairs 3' of exon 21, resulting in the inclusion of a premature stop codon and synthesis of a truncated BRCA2 protein. The aberrant splicing was verified by RT-PCR analysis on RNA isolated from whole blood of the affected patient. The mutation was not found in any of the patient's parents or in the mother's carcinoma, showing it is a <it>de novo </it>mutation. Variant specific PCR indicates that the mutation arose in the male germ-line.</p> <p>Conclusion</p> <p>We conclude that the novel <it>BRCA2 </it>splice variant is a <it>de novo </it>mutation introduced in the male spermatozoa that can be classified as a disease causing mutation.</p