Directed evolution and identification of control regions of ColE1 plasmid replication origins using only nucleotide deletions.

Genes can be mutated by altering DNA content (base changes) or DNA length (insertions or deletions). Most in vitro directed evolution processes utilize nucleotide content changes to produce DNA libraries. We tested whether gain of function mutations could be identified using a mutagenic process that produced only nucleotide deletions. Short nucleotide stretches were deleted in a plasmid encoding lacZ, and screened for increased beta-galactosidase activity. Several mutations were found in the origin of replication that quantitatively and qualitatively altered plasmid behavior in vivo. Some mutations allowed co-residence of ColE1 plasmids in Escherichia coli, and implicate hairpin structures II and III of the ColE1 RNA primer as determinants of plasmid compatibility. Thus, useful and unexpected mutations can be found from libraries containing only deletions.

The BRAF mutation is useful for prediction of clinical recurrence in low-risk patients with conventional papillary thyroid carcinoma.

BACKGROUND: The activating BRAF(V600E) mutation is the most common genetic alteration reported in papillary thyroid carcinoma (PTC). While some reports suggest the BRAF(V600E) mutation is associated with factors predicting a poor prognosis and recurrence, this remains a controversial issue. AIM: To determine whether the presence of the BRAF(V600E) mutation is a prognostic indicator for clinical recurrence in low-risk patients with conventional PTC. PATIENTS AND METHODS: The study involved 203 conventional PTC patients who underwent total or near-total thyroidectomy followed by immediate 131I ablation of the remnants. Patients with antithyroglobulin antibodies and those with extracervical metastases at presentation were excluded. DNA was extracted from paraffin-embedded tumour specimens, and the presence of the BRAF(V600E) mutation was evaluated using PCR amplification and direct sequencing. RESULTS: The BRAF(V600E) mutation was found to be present in 149 (73.4%) of 203 patients. The BRAF(V600E) mutation was correlated with male gender (P = 0.006) and with tumour size (P = 0.005). While there appeared to be an association between the BRAF(V600E) mutation and extrathyroid extension, this did not reach statistical significance (P = 0.062). During follow-up of the 203 patients (median 7.3 years; range 0.7-10.0 years), 36 (18%) patients experienced recurrence. While univariate analysis showed the BRAF(V600E) mutation was associated with tumour recurrence (21% with mutation vs 7% without mutation; P = 0.037), this association was not shown following multivariate analyses adjusting for the clinicopathological prognostic factors of age, gender, tumour size, extrathyroid extension, multifocality and lymph node metastasis. CONCLUSIONS: Although the BRAF(V600E) mutation was found to be associated with a higher clinical recurrence of disease in low-risk conventional PTC patients, it was not an independent predictor.

The BRAF mutation is not associated with poor prognostic factors in Korean patients with conventional papillary thyroid microcarcinoma.

BACKGROUND: The BRAF(V600E) mutation, the most common genetic alteration reported in papillary thyroid carcinoma, has been associated with poor prognostic factors. AIM: To determine whether the presence of the BRAF(V600E) mutation is associated with poor prognosis in Korean patients with conventional papillary thyroid microcarcinoma (micro-PTC). PATIENTS AND METHODS: DNA was extracted from paraffin-embedded thyroid tumour specimens taken from 60 patients with conventional micro-PTC, as well as from nine patients with follicular variant papillary carcinoma, six with nodular hyperplasia, four with follicular carcinoma (including one with Hürthle cell carcinoma), four with follicular adenoma (including two with Hürthle cell adenoma) and one each with medullary carcinoma, poorly differentiated carcinoma and anaplastic carcinoma. The presence of the BRAF(V600E) mutation was determined by polymerase chain reaction (PCR) amplification of exon 15 followed by direct sequencing. RESULTS: The BRAF(V600E) mutation was detected in tumour samples from 31 of 60 conventional micro-PTC patients (52%), but was not detected in patients with other types of thyroid tumours. The age distribution, tumour size, extrathyroid extension, multifocality and staging did not differ significantly between patients with and without the BRAF(V600E) mutation. CONCLUSION: In Korean patients with conventional micro-PTC, the presence of the BRAF(V600E) mutation was not significantly associated with prognostic factors.

Modes of intercellular transcription factor movement in the Arabidopsis apex.

A recent and intriguing discovery in plant biology has been that some transcription factors can move between cells. In Arabidopsis thaliana, the floral identity protein LEAFY has strong non-autonomous effects when expressed in the epidermis, mediated by its movement into underlying tissue layers. By contrast, a structurally unrelated floral identity protein, APETALA1, has only limited non-autonomous effects. Using GFP fusions to monitor protein movement in the shoot apical meristem and in floral primordia of Arabidopsis, we found a strong correlation between cytoplasmic localization of proteins and their ability to move to adjacent cells. The graded distribution of several GFP fusions with their highest levels in the cells where they are produced is compatible with the notion that this movement is driven by diffusion. We also present evidence that protein movement is more restricted laterally within layers than it is from L1 into underlying layers of the Arabidopsis apex. Based on these observations, we propose that intercellular movement of transcription factors can occur in a non-targeted fashion as a result of simple diffusion. This hypothesis raises the possibility that diffusion is the default state for many macromolecules in the Arabidopsis apex, unless they are specifically retained.

The Relationship among Eating Traits, Personality Characteristics, and Other Psychopathology in the Korean General Population / 신경정신의학

OBJECTIVE: The purposes of this study were to clarify the roles of personality characteristics and general psychopathology, including depression and hypochondriasis, in individuals with eating disorders, and to test a continuum hypothesis of eating disorders. METHODS: Using a multi-stage questionnaire sampling method including area sampling, proportionated stratified sampling, and quota sampling, we surveyed 3,062 subjects(1249 males and 1813 females) from a target of 4,400 Korean adults over the age of 18 in a nationwide area(9 ku's, 10 middle or small cities, and 17 kun's). We used the questionnaire which consisted of three parts:general information, scales for eating traits, and scales for personality characteristics and other general psychopathology. RESULTS: Psychoticism was the only personality characteristics which had a significant relationship with various eating traits including 'eating habits'(r=-0.3195), 'the Eating Attitudes Test'(EAT, r=0.3657), and 'preference for vegetables and fish, and dislike for sweet,tasting foods'(r=-0.2740). Lie scale also had a significant relationship with 'preference for snacks and instant foods'(r=-0.2117). These results were consistent in examining the relationships across genders. In female, there was a significant relationship between 'preference for the traditional Korean foods' and 'psychoticism'(r=-0.2103) in addtion to above relationships. However, there were no significant relationships between any of the eating traits and other psychopathology. Relative to the relationship between personality characteristics and general psychopathology, there were significant correlations between 'depression' and 'interoversion-extraversion'(r=-0.2174), 'depression' and 'neuroticism'(r=0.4510>, and 'hypochondriasis' and 'neuroticism'(r=0.3432). These correlations in female was the same as those of the total group, while among males, 'depression' was significantly correlated with all four personality characteristics, and 'hypochondriasis' was significantly correlated with 'interoversion-extraversion'(r=-0.2265) and 'neuroticism'(r=0.3762). CONCLUSION: These results suggest that psychoticism is the only personaltiy characteristics related to eating-specific psychopathology, while general psychopathology, such as depression and hypochondriasis is not related to eating pathology but may influence eating disorders by their interaction with other personality characteristics, such as interoversion-extraversion and neuroticism. Considering the results of previous studies in the patients with eating disorders and high risk groups, which are similar with our results in the general population, our results support a continuum hypothesis of eating disorders. Our results also suggest that gender differences in the pathology of eating disorders are the result not of difference in eating-specific pathology itself but through difference in influences of concurrent general psychopathology, such as depression and hypochondriasis.