The physiology of plant seed aging: a review / 生物工程学报

Seed quality plays an important role in the agricultural and animal husbandry production, the effective utilization of genetic resources, the conservation of biodiversity and the restoration and reconstruction of plant communities. Seed aging is a common physiological phenomenon during storage. It is a natural irreversible process that occurs and develops along with the extension of seed storage time. It is not only related to the growth, yield and quality of seed and seedling establishment, but also has an important effect on the conservation, utilization and development of plant germplasm resources. The physiological mechanisms of seed aging are complex and diverse. Most studies focus on conventional physiological characterization, while systematic and comprehensive in-depth studies are lacking. Here we review the recent advances in understanding the physiology of seed aging process, including the methods of seed aging, the effect of aging on seed germination, and the physiological and molecular mechanisms of seed aging. The change of multiple physiological parameters, including seed vigor, electrical conductivity, malondialdehyde content and storage material in the seed, antioxidant enzyme activity and mitochondrial structure, were summarized. Moreover, insights into the mechanism of seed aging from the aspects of transcriptome, proteome and aging related gene function were summarized. This study may facilitate the research of seed biology and the conservation and utilization of germplasm resources.

Advances in the physiological functions of plant lipids in response to stresses / 生物工程学报

Lipids are important components of living organisms that participate in and regulate a variety of life activities. Lipids in plants also play important physiological functions in response to a variety of abiotic stresses (e.g. salt stress, drought stress, temperature stress). However, most research on lipids focused on animal cells and medical fields, while the functions of lipids in plants were overlooked. With the rapid development of "omics" technologies and biotechnology, the lipidomics has received much attention in recent years because it can reveal the composition and function of lipids in a deep and comprehensive way. This review summarizes the recent advances in the functions and classification of lipids, the development of lipidomics technology, and the responses of plant lipids against drought stress, salt stress and temperature stress. In addition, challenges and prospects were proposed for future lipidomics research and further exploration of the physiological functions of lipids in plant stress resistance.

Study on antibiotic resistance and resistance genes of methicillin-resistant Staphylococcus aureus in children / 中华传染病杂志

Objective The aim of this study was to study the antibiotic resistance and resistance genes of methicillin-resistant Staphylococcus aureus (MRSA) in children from Shanghai area,and to determine the relationship between phenotypic and genotypic resistance profiles.Methods In this study,a total of 37 MRSA strains isolated from clinical specimens of hospitalized patients in Children's Hospital of Fudan University from March 2009 to November 2011 were collected.The mecA,ermA,ermB,ermC,aac (6') /aph (2),aph (3')-Ⅲ,ant (4',4),and qacA genes were detected by polymerase chain reaction (PCR).Resistance to antibiotics was detected by agar dilution tests.The data analysis was done by chi square test.Results Among the 37 MRSA isolates,all (100.0 ％) were mecA gene positive,9 (24.3％) were ermB gene positive,none was ermA/C gene positive,21 (56.8％) were aac (6')/aph (2) gene positive,10 (27.0％) were aph (3')-Ⅲ gene positive,6 (16.2％) were ant(4',4) gene positive,and 9 were qacA gene positive (24.3％).The positive rate of aac(6')/aph(2) in hospital acquired methicillin-resistant Staphylococcus aureus (HA-MRSA) was significantly higher than that of community acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) (85.7％ vs18.8％,x2=60.340,P=0.000).Among the 37 MRSAisolates,37 (100.0％) were resistant to penicillin,ampicillin-sulbactam,cefazolin,cefoxitin and cefuroxime.The 37 isolates were all susceptible to teicoplanin,vancomycin,and linezolid.The resistant rates to gentamicin,erythromycin,clindamycin,sulfamethoxazole,fosfomycin,rifampicin,and levofloxacin were 51.4％ (19/37),81.1％ (30/37),51.4％ (19/37),16.2％ (6/37),27.0％ (10/37),37.8％ (14/37) and 54.0％ (20/37),respectively.Compared with CA-MRSA,HAMRSA isolates had significantly higher resistance rates to gentamicin (12.5％ vs 81.0％; x2 =17.033,P=0.000),levofloxacin (31.2％ vs 71.4％; x2 =5.903,P=0.017),and rifampin (6.2％ vs 61.9％; x2=11.959,P=0.001).The rate of gentamicin resistance in aac(6')/aph(2) gene carrying strains was significantly higher than strains not carrying the gene (x2 =29.757,P=0.000).Conclusions MRSA in children carry a variety of drug-resistant genes,showed multi-drug resistance.HA-MRSA carries more resistance genes,and has higher rates resistance to antimicrobials than CA-MRSA.

Distribution of camptothecin and its metabolism-related enzymes in Camptotheca acuminata seedlings / 中草药

Objective To investigate the distribution of camptothecin(CPT),tryptophan synthase(TSB),and tryptophan decarboxylase(TDC) in Camptotheca acuminata seedlings.Methods The CPT content,TSB and TDC activities in different organs of C.acuminata seedlings subjected to different nitrogen forms treatments by sand culture in greenhouse were determined by HPLC.Results The CPT content in the young leaves of C.acuminata seedlings with different N-forms was significantly higher than that in other organs(P