Diagnostic value of breast imaging reporting and data system combined with wire-guided localization biopsy for breast microcalcifications in impalpable breast cancer / 肿瘤研究与临床

Objective To explore the diagnosis value of X-ray breast imaging reporting and data system (BI-RADS) combined with wire-guided localization biopsy for breast microcalcifications in impalpable breast cancer.Methods 192 palpation negative patients with 205 microcalcification lesions were detected by mammography.All lesions were classified according to BI-RADS descriptors for calcification and were categorized by the BI-RADS.The patients with BI-RADS category 4a and above underwent X-ray positioning guide wire-guided biopsy and pathological diagnosis.Results In 205 microcalcification lesions,74 (36.1％) were malignant lesions,131 (63.9 ％) were less than benign lesions.The positive predictive value of malignant breast lesions in clustered,segmental,regional linear branching calcifications were higher [83.3 ％ (5/6),100.0 ％ (11/11),100.0 ％ (1/1)],followed by clustered,linear,segmental,regional pleomorphic calcifications [55.9 ％ (38/68),50.0 ％ (1/2),40.0 ％ (8/20) and 33.3 ％ (4/12),respectively].The positive predictive values of malignant in linear branching calcifications and pleomorphic calcifications were significantly higher than those of coarse heterogeneous calcifications,amorphous or indistinct calcifications (x2 values were 34.44,51.87,16.71,29.86,all P ＜ 0.05).The linear branching calcification had the highest possibility.The proportions of malignant lesions in four different types of glands were extremely dense 40.5 ％ (30/74),heterogeneously dense 39.2 ％ (29/74),scattered areas of fibroglandular density 10.8 ％ (8/74) and fat 9.5 ％ (7/74),respectively.Conclusions BI-RADS categorization for breast microcalcification lesions can improve the detection rate of impalpable breast cancer.Linear branching calcification has higher predictive value for malignant lesions.Dense breast is the risk factors of breast cancer,which should be attached great importance.

Development of transgenic maize with anti-rough dwarf virus artificial miRNA vector and their disease resistance / 生物工程学报

Maize is one of the most important food crops. Rice black-streaked dwarf virus is a maize rough dwarf disease pathogen. The occurrence and transmission of maize rough dwarf disease brings great damage to maize production. The technology of using artificial miRNA to build antiviral plant has been proven effective in a variety of plants. However, such trials in maize have not been reported. We designed primers based on the sequence of maize zea-miR159a precursor and sequence of function protein genes and silencing RBSDV coding genes in RBSDV genome. We constructed amiRNA (artificial miRNA) gene for silencing RBSDV coding gene and gene silencing suppressor. We constructed pCAMBIA3301-121-amiRNA plant expression vector for transforming maize inbred lines Z31 by using agrobacterium mediated method. After molecular analysis of transgenic maize, homozygous lines with high miRNA expression were selected by molecular detection for a subsequent natural infection experiment. We studied the severity of maize rough dwarf disease according to a grading standard (grade 0 to 4). The experiment results showed that the disease resistance of transgenic homozygous maize with the anti-rough dwarf virus amiRNA vector was better than that of wild type. Among the transgenic maize, S6-miR159 transgenic maize had high disease resistance. It is feasible to create new maize variety by the use of artificial miRNA.

Development of an activity-directed selection system enabled significant improvement of the carboxylation efficiency of Rubisco

Photosynthetic CO(2) fixation is the ultimate source of organic carbon on earth and thus is essential for crop production and carbon sequestration. Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) catalyzes the first step of photosynthetic CO(2) fixation. However, the extreme low carboxylation efficiency of Rubisco makes it the most attractive target for improving photosynthetic efficiency. Extensive studies have focused on re-engineering a more efficient enzyme, but the effort has been impeded by the limited understanding of its structure-function relationships and the lack of an efficient selection system towards its activity. To address the unsuccessful molecular engineering of Rubisco, we developed an Escherichia coli-based activity-directed selection system which links the growth of host cell solely to the Rubisco activity therein. A Synechococcus sp. PCC7002 Rubisco mutant with E49V and D82G substitutions in the small subunit was selected from a total of 15,000 mutants by one round of evolution. This mutant showed an 85% increase in specific carboxylation activity and a 45% improvement in catalytic efficiency towards CO(2). The small-subunit E49V mutation was speculated to influence holoenzyme catalysis through interaction with the large-subunit Q225. This interaction is conserved among various Rubisco from higher plants and Chlamydomonas reinhardtii. Knowledge of these might provide clues for engineering Rubisco from higher plants, with the potential of increasing the crop yield.