ΩqPCR measures telomere length from single-cells in base pair units.

ΩqPCR determines absolute telomere length in kb units from single cells. Accuracy and precision of ΩqPCR were assessed using 800 bp and 1600 bp synthetic telomeres inserted into plasmids, which were measured to be 819 ± 19.6 and 1590 ± 42.3 bp, respectively. This is the first telomere length measuring method verified in this way. The approach uses Ω-probes, a DNA strand containing sequence information that enables: (i) hybridization with the telomere via the 3' and 5' ends that become opposed; (ii) ligation of the hybridized probes to circularize the Ω-probes and (iii) circularized-dependent qPCR due to sequence information for a forward primer, and for a reverse primer binding site, and qPCR hydrolysis probe binding. Read through of the polymerase during qPCR occurs only in circularized Ω-probes, which quantifies their number that is directly proportional to telomere length. When used in concert with information about the cell cycle stage from a single-copy gene, and ploidy, the MTL of single cells measured by ΩqPCR was consistent with that obtained from large sample sizes by TRF.

Padlock probe-mediated qRT-PCR for DNA computing answer determination.

Padlock probe-mediated quantitative real time PCR (PLP-qRT-PCR) was adapted to quantify the abundance of sequential 10mer DNA sequences for use in DNA computing to identify optimal answers of traveling salesman problems. The protocol involves: (i) hybridization of a linear PLP with a target DNA sequence; (ii) PLP circularization through enzymatic ligation; and (iii) qRT-PCR amplification of the circularized PLP after removal of non-circularized templates. The linear PLP was designed to consist of two 10-mer sequence-detection arms at the 5' and 3' ends separated by a core sequence composed of universal PCR primers, and a qRT-PCR reporter binding site. Circularization of each PLP molecule is dependent upon hybridization with target sequence and high-fidelity ligation. Thus, the number of PLP circularized is determined by the abundance of target in solution. The amplification efficiency of the PLP was 98.7% within a 0.2 pg-20 ng linear detection range between thermal cycle threshold (C(t) value) and target content. The C(t) values derived from multiplex qRT-PCR upon three targets did not differ significantly from those obtained with singleplex assays. The protocol provides a highly sensitive and efficient means for the simultaneous quantification of multiple short nucleic acid sequences that has a wide range of applications in biotechnology.

Single-molecule detection of DNA via sequence-specific links between F1-ATPase motors and gold nanorod sensors.

We report the construction of a novel biosensing nanodevice to detect single, sequence-specific target DNA molecules. Nanodevice assembly occurs through the association of an immobilized F1-ATPase molecular motor and a functionalized gold nanorod via a single 3',5'-dibiotinylated DNA molecule. Target-dependent 3',5'-dibiotinylated DNA bridges form by combining ligation and exonucleation reactions (LXR), with a specificity capable of selecting against a single nucleotide polymorphism (SNP). Using dark field microscopy to detect gold nanorods, quantitation of assembled nanodevices is sufficient to distinguish the presence of as few as 1800 DNA bridges from nonspecifically bound nanorods. The rotary mechanism of F1-ATPase can drive gold nanorod rotation when the nanorod is attached via the DNA bridge. Therefore, rotation discriminates fully assembled devices from nonspecifically bound nanorods, resulting in a sensitivity limit of one zeptomole (600 molecules).

The influence of ultraviolet-B radiation on growth, hydroxycinnamic acids and flavonoids of Deschampsia antarctica during Springtime ozone depletion in Antarctica.

We examined the influence of solar ultraviolet-B radiation (UV-B; 280-320 nm) on the growth, biomass production and phenylpropanoid concentrations of Deschampsia antarctica during the springtime ozone depletion season at Palmer Station, along the Antarctic Peninsula. Treatments involved placing filters on frames over potted plants that reduced levels of biologically effective UV-B either by 83% (reduced UV-B) or by 12% (near-ambient UV-B) over the 63 day experiment (7 November 1998-8 January 1999) when ozone depletion averaged 17%. Plants growing under near-ambient UV-B had 41% and 40% lower relative growth rates and net assimilation rates, respectively, than those under reduced UV-B. The former plants produced 50% less total biomass as a result of having 47% less aboveground biomass. The reduction in aboveground biomass was a result of a 29% lower leaf elongation rate resulting in shorter leaves and 59% less total leaf area in plants grown under reduced UV-B. p-Coumaric, caffeic and ferulic acids were the major hydroxycinnamic acids, and luteolin derivatives were the major flavonoids in both insoluble and soluble leaf extracts. Concentrations of insoluble p-coumaric and caffeic acid and soluble ferulic acids were 38%, 48% and 60% higher, respectively, under near-ambient UV-B than under reduced UV-B. There were no UV-B effects on concentrations of insoluble or soluble flavonoids.

[Case-control studies on complex tibial plateau and posterior condylar fractures treated through combined anterior-posterior (small incision or micro-incision) approach].

OBJECTIVE: To study the therapeutic effects of combined anterior-posterior (small incision or micro-incision) approach for complex tibial plateau and posterior condylar fractures. METHODS: From 2000 to 2008, 79 patients (81 limbs) with complex tibial plateau and posterior condylar fractures were reviewed. There were 45 males and 34 females, ranging in age from 19 to 66 years, with an average of 40.6 years. Thirty-nine limbs were treated using small incision through combined anterior-posterior approach, in which 13 limbs were Schatzker type IV, 15 limbs were type V ,and 11 limbs were type VI. Other 42 limbs were treated using micro-incision through combined anterior-posterior approach, in which 18 limbs were Schatzker type IV, 16 limbs were type V, and 8 limbs were type VI. The Rasmussen scores for knee joint and radio scores were used to evaluate therapeutic effects after the treatment. The complications such as cutaneous necrosis and incision infection were observed. RESULTS: All the patients were followed up. According to Rasmussen criterion, in small incision group, 16 limbs got an excellent result, 13 good, 7 fair and 3 bad; in micro-incision group,above data were 19, 11, 8 and 4 respectively. Comparison between the two groups, P = 0.924. Comparison of complications such as cutaneous necrosis and incision infection: in small incision group,10 limbs had the complications, and in micro-incision group were 4 limbs; the occurrence rate of small incision group were higher than that of micro-incision group (P = 0.047). CONCLUSION: There are no significant differences between the two groups in the knee joint function rehabilitation; however, there is smaller rate for cutaneous necrosis and incision infection in micro-incision group.

Solving the fully-connected 15-city TSP using probabilistic DNA computing.

Implementation of DNA computers has lagged behind the theoretical advances due to several technical limitations. These limitations include the amount of DNA required, the efficiency and accuracy of methods to generate and purify answers, and the lack of a reliable method to read the answer. Here we show how to perform calculations using a reasonable amount of DNA with greater efficiency and accuracy and a new readout method that was used to successfully solve a problem with 15 vertices and 210 edges, the largest problem ever solved with DNA. These advances will provide new opportunities for DNA computing to perform practical computations that utilize the massively parallel nature of DNA hybridization.