ABSTRACT
Guanosine-5'-triphosphate (GTP) plays a key role in many important biological processes of cells. It is not only a primer for DNA replication and one of the four essential nucleoside triphosphates for mRNA synthesis, but also an energy source for translation and other important cellular processes. It can be converted to adenine nucleoside triphosphate (ATP), and the intracellular GTP level is closely related to the specific pathological state, so it is crucial to establish a simple and accurate method for the detection of GTP. Deoxyribozymes have unique catalytic and structural properties. One of the deoxyribozymes which is named DK2 with self-phosphorylation ability can transfer a phosphate from GTP to the 5' end in the presence of manganese(ii), while lambda exonuclease (λexo) catalyzes the gradual hydrolysis of double-stranded DNA molecules phosphorylated at the 5'-end from 5' to 3', but cannot cleave the 5'-OH end. The fluorescent dye SYBR Green I (SG I) can bind to dsDNA and produce significant fluorescence, but it can only give out weak fluorescence when it is mixed with a single strand. Here, we present a novel unlabeled fluorescence assay for GTP based on the self-phosphorylation of deoxyribozyme DK2 and the specific hydrolysis of λexo. Owing to the advantages of simple operation, high sensitivity, good specificity, low cost and without fluorophore (quenching group) labeling, this method has great potential in biological applications.
Subject(s)
DNA, Catalytic , Fluorescent Dyes , Guanosine , Guanosine Triphosphate , PolyphosphatesABSTRACT
The biology of the weevil Hylobitelus xiaoi Zhang was studied in both field and laboratory in Shangyou, Jiangxi Province, China. This species required 2 yr to complete one generation with overwintering by adults in pupal chambers and larvae in galleries in the bark of host trees. Adults emerged from early March to early April and fed on the inner bark of branches of the trees. Adults fly little. Adults exhibited a diel periodicity, climbing up the trees around sunset and returning to the tree base the next morning. The mean preovipostion period was 46 d. Oviposition commenced in early May and ended in late August. The average fecundity per female was 36 eggs. Overwintered adult females and males lived 208 and 227 d, respectively. At 25 degrees C, the mean egg incubation period was 13 d. In the field, egg hatch occurred in 12-15 d with 83% survival. There were five to seven instars. At 25 degrees C, duration of the larval stage averaged 129 d. Pupation commenced in late August. At 25 degrees C, pupation averaged 20 d. In the field, pupation required 20-26 d. Transformation to adults occurred from late September to October. New adults remained in the pupal chambers until the next year. Infection by Beauveria bassiana Vuill. occurred in 0.8% of the pupae and 8.8% of the overwintered adults.