23 research outputs found
Recombinase technology: applications and possibilities
The use of recombinases for genomic engineering is no longer a new technology. In fact, this technology has entered its third decade since the initial discovery that recombinases function in heterologous systems (Sauer in Mol Cell Biol 7(6):2087–2096, 1987). The random insertion of a transgene into a plant genome by traditional methods generates unpredictable expression patterns. This feature of transgenesis makes screening for functional lines with predictable expression labor intensive and time consuming. Furthermore, an antibiotic resistance gene is often left in the final product and the potential escape of such resistance markers into the environment and their potential consumption raises consumer concern. The use of site-specific recombination technology in plant genome manipulation has been demonstrated to effectively resolve complex transgene insertions to single copy, remove unwanted DNA, and precisely insert DNA into known genomic target sites. Recombinases have also been demonstrated capable of site-specific recombination within non-nuclear targets, such as the plastid genome of tobacco. Here, we review multiple uses of site-specific recombination and their application toward plant genomic engineering. We also provide alternative strategies for the combined use of multiple site-specific recombinase systems for genome engineering to precisely insert transgenes into a pre-determined locus, and removal of unwanted selectable marker genes
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Self pregnancy testing in an urban family planning clinic: promising results for a new approach to contraceptive follow-up
Immediate initiation of depo-medroxyprogesterone acetate (DMPA) increases continuation and decreases pregnancies compared to conventional (next menstrual period) initiation. A drawback is the need to return in 4 weeks for a repeat pregnancy test to identify any pregnancy that was too early to diagnose on the day of injection. If women can perform home pregnancy tests (HPTs) to detect human chorionic gonadotropin (hCG) in urine, the need for this follow-up visit may be eliminated. This study assesses whether women can perform their own HPT.
This is a single-visit observational trial of an HPT kit. Subjects recruited from a waiting room in an urban family planning clinic received an HPT kit with standard instructions to use immediately. Subjects and a research assistant each interpreted the test. Their results were then compared to a standard cassette type test for detection of hCG performed by clinic staff. kappa was calculated to assess the level of agreement.
Three hundred ten subjects enrolled. They were young (mean age, 25.2 years), mostly Hispanic (91%) women. A change in the font and explicitness of the instructions decreased the incidence of invalid tests from 12.7% to 4.8%. The subject and research assistant's interpretation of the test had a high level of agreement, kappa=0.95 [95% confidence interval (CI), 0.92-0.99]. There was also a high level of agreement between the subjects' results and the standard test, kappa=0.88 (95% CI, 0.82-0.95).
Women presenting for pregnancy testing at an urban clinic are able to perform HPTs with a high level of accuracy. The appearance of the instructions influenced the incidence of false-negative and invalid tests. Home pregnancy tests may be useful in follow-up protocols when immediate initiation of DMPA is employed
Magnetic fields and differential rotation on the pre-main sequence - III. The early-G star HD 106506
We present the photometry and spectropolarimetry of the pre-main-sequence star HD 106506. A photometric rotational period of ∾1.416 ± 0.133 d has been derived using observations at Mount Kent Observatory (MKO). Spectropolarimetric data obtained with the 3.9-m Anglo-Australian Telescope (AAT) were used to derive spot occupancy and magnetic maps of the star through the technique of Zeeman Doppler imaging (ZDI). The resulting brightness maps indicate that HD 106506 displays photospheric spots at all latitudes including a predominant polar spot. Azimuthal and radial magnetic images of this star have been derived, and a significant azimuthal magnetic field is indicated, in line with other active young stars. A solar-like differential rotation law was incorporated into the imaging process. Using Stokes I information the equatorial rotation rate, Ωeq, was found to be 4.54 ± 0.01 rad d-1, with a photospheric shear δΩ of 0.21+0.02-0.03 rad d-1. This equates to an equatorial rotation period of ˜1.39 ± 0.01 d, with the equatorial region lapping the poles every ˜ 30+5-3 d. Using the magnetic features, the equatorial rotation rate, Ωeq, was found to be 4.51 ± 0.01 rad d-1, with a photospheric shear δΩ of 0.24 ± 0.03 rad d-1. This differential rotation is approximately four times that observed on the Sun