Sequence-directed nucleosome-depletion is sufficient to activate transcription from a yeast core promoter in vivo.

Nucleosome-depleted regions (NDRs) (also called nucleosome-free regions or NFRs) are often found in the promoter regions of many yeast genes, and are formed by multiple mechanisms, including the binding of activators and enhancers, the actions of chromatin remodeling complexes, and the specific DNA sequences themselves. However, it remains unclear whether NDR formation per se is essential for transcriptional activation. Here, we examined the relationship between nucleosome organization and gene expression using a defined yeast reporter system, consisting of the CYC1 minimal core promoter and the lacZ gene. We introduced simple repeated sequences that should be either incorporated in nucleosomes or excluded from nucleosomes in the site upstream of the TATA boxes. The (CTG)12, (GAA)12 and (TGTAGG)6 inserts were incorporated into a positioned nucleosome in the core promoter region, and did not affect the reporter gene expression. In contrast, the insertion of (CGG)12, (TTAGGG)6, (A)34 or (CG)8 induced lacZ expression by 10-20 fold. Nucleosome mapping analyses revealed that the inserts that induced the reporter gene expression prevented nucleosome formation, and created an NDR upstream of the TATA boxes. Thus, our results demonstrated that NDR formation dictated by DNA sequences is sufficient for transcriptional activation from the core promoter in vivo.

[Combined General and Spinal-Epidural Anesthesia under Spontaneous Breathing in a Patient with a Giant Bulla].

This paper reports the successful perioperative management of a patient with a giant bulla, who underwent radical prostatectomy under general anesthesia performed under combinet spinal-epidural anesthesia while maintaining spontaneous respiration. A 61-year-old man was scheduled for radical prostatectomy. He had undergone conservative treatment using a drainage tube for right-sided pneumothorax at the age of 23. Preoperative chest CT revealed the presence of a giant bulla in the left upper lobe, multiple bullae in the entire right lung, and emphysematous alterations in both lungs. On respiratory function testing, mild obstructive impairment was observed. In the operating room, an epidural catheter was inserted at T11-12, and spinal anesthesia was performed at L3-4. Under anesthesia with propofol and fentanyl, i-gel® was inserted. During anesthesia, spontaneous respiration was managed at oxygen concentration 40% and sevoflurane 1.5%, while continuing the epidural administration of levobupivacaine. The circulatory and respiratory conditions were stable during surgery. The durations of surgical and anesthetic procedures were 2 hours and 16 minutes and 3 hours and 33 minutes, respectively. In the absence of respiratory complications, the patient was discharged 8 days after surgery.

Large four-wave mixing of spatially extended excitonic states in thin GaAs layers.

We study the size dependence of the nonlinear response of weakly confined excitons for the size region beyond the long wavelength approximation regime. The observed degenerate-four-wave mixing signal of GaAs thin layers exhibits an anomalous size dependence, where the signal is resonantly enhanced at a particular thickness region. The theoretical analysis elucidates that this enhancement is due to the size-resonant enhancement of the internal field with a spatial structure relevant to the nondipole-type excitonic state. These results establish the formerly proposed new type of size dependence of nonlinear response due to the nonlocality induced double resonance.

Effects of triplet repeat sequences on nucleosome positioning and gene expression in yeast minichromosomes.

Triplet repeat sequences that cause human hereditary diseases can form a variety of DNA conformations. Since DNA structures act as determinants of chromatin structure, chromatin may be involved in mechanisms of these diseases. To address this issue, we examined effects of triplet repeat sequences on chromatin structure and gene expression in Saccharomyces cerevisiae. We show here that (1) (CTG)12 promotes nucleosome formation, (2) (CGG)12 disrupts an array of positioned nucleosomes, and (3) (GAA)12 has little effect on nucleosome formation. Also, we show that insertion of (CGG)12 increases gene expression of a UAS-less promoter about 10-fold, while (CTG)12 and (GAA)12 have no effect. Thus, expansion of triplet repeat sequences may cause improper expression of disease related genes, through their effects on chromatin structure.