Spatial separation between replisome- and template-induced replication stress signaling.

Polymerase-blocking DNA lesions are thought to elicit a checkpoint response via accumulation of single-stranded DNA at stalled replication forks. However, as an alternative to persistent fork stalling, re-priming downstream of lesions can give rise to daughter-strand gaps behind replication forks. We show here that the processing of such structures by an exonuclease, Exo1, is required for timely checkpoint activation, which in turn prevents further gap erosion in S phase. This Rad9-dependent mechanism of damage signaling is distinct from the Mrc1-dependent, fork-associated response to replication stress induced by conditions such as nucleotide depletion or replisome-inherent problems, but reminiscent of replication-independent checkpoint activation by single-stranded DNA Our results indicate that while replisome stalling triggers a checkpoint response directly at the stalled replication fork, the response to replication stress elicited by polymerase-blocking lesions mainly emanates from Exo1-processed, postreplicative daughter-strand gaps, thus offering a mechanistic explanation for the dichotomy between replisome- versus template-induced checkpoint signaling.

An expanded tool kit for the auxin-inducible degron system in budding yeast.

Fusion of inducible degradation signals, so-called degrons, to cellular proteins is an elegant method of controlling protein levels in vivo. Recently, a degron system relying on the plant hormone auxin has been described for use in yeast and vertebrate cells. We now report the construction of a series of vectors that significantly enhance the versatility of this auxin-inducible degron (AID) system in Saccharomyces cerevisiae. We have minimized the size of the degron and appended a series of additional epitope tags, allowing detection by commercial antibodies or fluorescence microscopy. The vectors are compatible with PCR-based genomic tagging strategies, allow for C- or N-terminal fusion of the degron, and provide a range of selection markers. Application to a series of yeast proteins, including essential replication factors, provides evidence for a general usefulness of the system.

[Functional assessment in girls with Turner syndrome--preliminary results]. / Problemy funkcjonalne pacjentek z zespolem Turnera--doniesienie wstepne.

INTRODUCTION: About 10% of Turner's syndrome (TS) patients complain on persistent knee pain, and seek the orthopaedic help because of it. AIM OF STUDY: To evaluate the gait pattern of girls with TS. MATERIAL AND METHODS: Gait analysis was performed using VICON 460 system in 15 patients aged 7 to 20 years. The maximal isometric flexion and extension moments of the knee joints were measured. The knees were examined with X-ray and USG for possible anatomical or degenerative changes. RESULTS: All spatio-temporal parameters of the gait were within normal values. Only 3 patients had proper pelvic tilt, all the others had decreased tilt (from 2 to 9). Only 40% had proper knee flexion at initial contact, 1 patient had knee hyperextension, all the others increased knee flexion. In 50% of the patients the decreased knee range of motion together with decreased maximum knee flexion in swing phase was observed. In 30% there was a decreased hip range of motion. Clinical evaluation of body posture revealed that nearly all patients had trunk asymmetry, and various deformities of knees and feet. DISCUSSION: Nearly all TS patients had decreased pelvic tilt, which could be sign of the weakness of the muscles responsible for the pelvis orientation. The abnormalities of upper and lower body found during clinical evaluation of body posture also suggested decreased muscular strength. It is known that girls with TS have poorer motor development, which could result in decreased muscular strength and our findings support this thesis. Decreased muscular strength could also negatively influence the locomotor abilities.