Only little information on a particular class of myoviruses, the SPO1-like bacteriophages infecting low-G؉C-content, gram-positive host bacteria (Firmicutes), is available. We present the genome analysis and molecular characterization of the large, virulent, broad-host-range Listeria phage A511. A511 contains a unit (informational) genome of 134,494 bp, encompassing 190 putative open reading frames (ORFs) and 16 tRNA genes, organized in a modular fashion common among the Caudovirales. Electron microscopy, enzymatic fragmentation analyses, and sequencing revealed that the A511 DNA molecule contains linear terminal repeats of a total of 3,125 bp, encompassing nine small putative ORFs. This particular genome structure explains why A511 is unable to perform general transduction. A511 features significant sequence homologies to Listeria phage P100 and other morphologically related phages infecting Firmicutes such as Staphylococcus phage K and Lactobacillus phage LP65. Equivalent but more-extensive terminal repeats also exist in phages P100 (ϳ6 kb) and K (ϳ20 kb). High-resolution electron microscopy revealed, for the first time, the presence of long tail fibers organized in a sixfold symmetry in these viruses. Mass spectrometry-based peptide fingerprinting permitted assignment of individual proteins to A511 structural components. On the basis of the data available for A511 and relatives, we propose that SPO1-like myoviruses are characterized by (i) their infection of gram-positive, low-G؉C-content bacteria; (ii) a wide host range within the host bacterial genus and a strictly virulent lifestyle; (iii) similar morphology, sequence relatedness, and collinearity of the phage genome organization; and (iv) large double-stranded DNA genomes featuring nonpermuted terminal repeats of various sizes.Listeria monocytogenes is a gram-positive, opportunistic pathogen that can cause a wide spectrum of diseases, such as meningitis, septicemia, abortion, and gastroenteritis, associated with mortality rates as high as 25 to 30% (17, 62). Listeria bacteria are ubiquitously found in nature and can enter the food chain at many points (26, 66). They are able to proliferate over a wide range of external conditions, including low temperatures and high salt concentrations, thus posing severe problems to the food industry (2,22,15,48).Almost all of the Listeria bacteriophages described to date are temperate (38); only very little is known about virulent phages infecting this host. Listeria phages are valuable sources of biological information and useful tools for the study, differentiation, manipulation, and control of these bacteria (6,33,41). Phage A511 and some of its components have been particularly useful in phage typing schemes (35, 61), as reporter phage (39), with respect to their endolysins (16), and also for the control of Listeria contamination of foods (7; S. Guenther, D. Huwyler, S. Richard, and M. J. Loessner, submitted for publication). In contrast to temperate Listeria phages A118 and PSA (36, 71), A511 is a virulent (i.e., s...

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Excited states inRa were studied by means of the Pb( C, 3n) reaction at 65 MeV. The investigation was made with 12 Compton-suppressed Ge detectors and a multicopnter array. Transitions in Ra were selected by requiring appropriate conditions on fold and sum energy. The proposed level scheme shows two sidebands with alternating parity structure decaying to the ground-state band. It is consistent with a recent description of Ra in the framework of the reflection-asymmetric meanfield approach, which predicts a K = z ground-state band and two low-lying bands with quantum numbers K =and K = -. 2 2' PACS number(s): 25.70.z, 23.20.Lv, 27.80.+w