The Caulobacter crescentus phage phiCbK: genomics of a canonical phage.

BACKGROUND: The bacterium Caulobacter crescentus is a popular model for the study of cell cycle regulation and senescence. The large prolate siphophage phiCbK has been an important tool in C. crescentus biology, and has been studied in its own right as a model for viral morphogenesis. Although a system of some interest, to date little genomic information is available on phiCbK or its relatives. RESULTS: Five novel phiCbK-like C. crescentus bacteriophages, CcrMagneto, CcrSwift, CcrKarma, CcrRogue and CcrColossus, were isolated from the environment. The genomes of phage phiCbK and these five environmental phage isolates were obtained by 454 pyrosequencing. The phiCbK-like phage genomes range in size from 205 kb encoding 318 proteins (phiCbK) to 280 kb encoding 448 proteins (CcrColossus), and were found to contain nonpermuted terminal redundancies of 10 to 17 kb. A novel method of terminal ligation was developed to map genomic termini, which confirmed termini predicted by coverage analysis. This suggests that sequence coverage discontinuities may be useable as predictors of genomic termini in phage genomes. Genomic modules encoding virion morphogenesis, lysis and DNA replication proteins were identified. The phiCbK-like phages were also found to encode a number of intriguing proteins; all contain a clearly T7-like DNA polymerase, and five of the six encode a possible homolog of the C. crescentus cell cycle regulator GcrA, which may allow the phage to alter the host cell's replicative state. The structural proteome of phage phiCbK was determined, identifying the portal, major and minor capsid proteins, the tail tape measure and possible tail fiber proteins. All six phage genomes are clearly related; phiCbK, CcrMagneto, CcrSwift, CcrKarma and CcrRogue form a group related at the DNA level, while CcrColossus is more diverged but retains significant similarity at the protein level. CONCLUSIONS: Due to their lack of any apparent relationship to other described phages, this group is proposed as the founding cohort of a new phage type, the phiCbK-like phages. This work will serve as a foundation for future studies on morphogenesis, infection and phage-host interactions in C. crescentus.

Position Statement. Violence and injury in ice hockey.

Ice hockey is a sport enjoyed by many men and women at the spectator and participant level. It is played with high intensity and often involves body contact. Although the women's games is far from injury free, it is the men's game that has drawn criticism for excessive violence. Much attention has been drawn to the serious injuries that have occurred in ice hockey, specifically spinal injuries, concussions, and eye injuries. Many such injuries are the result of illegal and violent acts such as checking from behind or a deliberate high stick. Because of this, some medical organizations have called for changes in the sport, such as minimum age requirements for body-checking. As a practical matter such changes are unlikely to be accepted by hockey governing boards. Many of those involved in the sport consider body-checking a fundamental component of the game. Furthermore, a distinction needs to be made between any kind of injury and a serious, catastrophic injury. For example, although a recent study found that body-checking accounted for up to 38% of ice hockey injuries, none were of the catastrophic type. With respect to catastrophic injuries such as spinal cord trauma or a blinded eye, legal body-checking accounts for significantly less than illegal body-checking (e.g., checking from behind) or violent stick work. To reduce serious injury in ice hockey, we offer 10 recommendations, key among them automatic game suspensions for certain rules violations, and recognition of the coach as the most important figure in promoting a clean, safe game.