No abstract

DNA-loaded microtubules (MTs) moving on a kinesin motor protein-coated substrate can selectively hybridize with a target fully matched DNA over single-base mismatched DNA and transport it. This technique is capable of collecting target biomolecules toward one point site to design new methodology of DNA analysis.

BackgroundCongenital adrenal hyperplasia (CAH) cause life-threatening adrenal crisis. It also affects fetal sex development and can result in incorrect sex assignment at birth. In 1989, a newborn screening program for congenital adrenal hyperplasia (CAH) was introduced in Tokyo. Here we present the results of this screening program in order to clarify the efficiency of CAH screening and the incidence of CAH in Japan.MethodFrom 1989 to 2013, a total of 2,105,108 infants were screened for CAH. The cutoff level for diagnosis of CAH was adjusted for gestational age and birth weight.ResultsA total of 410 infants were judged positive, and of these, 106 patients were diagnosed with CAH, indicating a positive predictive value (PPV) of 25.8 %. Of the 106 patients, 94 (88.7 %) were diagnosed with 21-OHD. Of these 94 patients, 73 were diagnosed with the salt wasting form, 14 with the simple virilising form and 7 with the nonclassical form (NC21OHD). The mean birth weight and gestational age were 3192 ± 385 g and 38.9 ± 1.38 weeks. 11 out of 44 female patients were assigned as female according to their screening result.ConclusionsThese data suggest that the newborn screening in Tokyo was effective, especially for sex assignment and preventing fatal adrenal crisis. The incidence of CAH was similar to that measured in previous Japanese screening studies, and it was also similar to that of western countries. The incidence of NC21OHD in Japan in the present study was lower than that in western countries as previous studies reported. The screening program achieved higher PPV than previous CAH screening studies, which might be due to the use of variable cutoffs according to gestational age and birth weight. However, most of the neonates born at 37 weeks or less that were referred to hospital were false-positives. Further changes are needed to reduce the number of false positive preterm neonates.

We have developed a novel mobile bioprobe using a conjugate of a kinesin-driven microtubule (MT) and malachite green (MG) as a platform for capturing MG RNA aptamers. The fluorescence of MG increases when it is bound to an MG aptamer, allowing MT-MG conjugates to work as sensors of RNA transcripts containing the MG aptamer sequence. Kinesin motor proteins provide an effective driving force to create mobile bioprobes without any manipulation. Although the fluorescence of a small number of MG-binding aptamers is low, the self-organization of tubulins into MTs enables the microscopic observation of the bound aptamers by collecting them on MTs. We demonstrate that MT-MG conjugates can select target aptamers from a transcription mixture and transport them without losing their inherent motility. Because the MG aptamer binds MG in a reversible manner, MT-MG conjugates can conditionally load and unload the target aptamers. This is one advantage of this system over the molecular probes developed previously in which reversible unloading is impossible due to high-affinity binding, such as between avidin and biotin. Furthermore, an MT-MG conjugate can be used as a platform for other MG aptameric sensors with recognition regions for various target analytes optimized by further selection procedures. This is the first step to applying living systems to in vitro devices. This technique could provide a new paradigm of mobile bioprobes establishing high-throughput in vitro selection systems using microfluidic devices operating in parallel.