No abstract

We have developed a family of high-performance capillary DNA sequencing instruments based on a novel multicolor fluorescent detection technology. This technology is based on two technical innovations: the multilaser excitation of fluorescence of labeled DNA fragments and the "color-blind" single-photon detection of modulated fluorescence. Our machines employ modern digital and broadband techniques that are essential for achieving superior instrument performance. We discuss the design and testing results for several versions of the automated single lane DNA sequencers, as well as our approach to scaling up to multilane instruments.

With the aging of the baby boomers, it is predicted that the US population over age 65 will grow from its 1999 level of 34.6 million persons to approximately 82 million in 2050, a 137% increase. The most rapid surge in our senior population will take place between 2011 and 2030. During this 19-year interval, seniors will expand from 13% of our population to 22% of our population. In this project, our goal is to design a wireless sensor system, the Health Tracker 2000, that can monitors users' vital signs and notifies relatives and medical personnel of their location during life threatening situations. The Health Tracker 2000 combines wireless sensor networks, existing RFID (Radio Frequency Identification) and Vital Sign Monitoring technology to simultaneously monitor vital signs while keeping track of the users' location. The use of wireless technology makes it possible to install the system in all types of homes and facilities. Radio frequency waves can travel through walls and fabric, sending the vital sign and location information to a central monitoring computer via a miniature transmitter network. Such information can easily be accessed from any location over the Internet.

We have studied the formation of a resistive region in the capillary during DNA separation. This effect is caused by an unequal change in the mobilities of cations and anions at the interface between the running buffer solution and the capillary. We studied the motion of the resistive region boundary by sequential removal of portions of the affected capillary end. We found that in the process of developing the resistive region the distribution of the electric fields in the capillary changes from uniform to extremely nonuniform, with a very high field (above 1 MV/cm) in the resistive region and a reduced field (80 V/cm) in the rest of the capillary. Though theoretically a resistive region may appear either at the anode (detection) or the cathode (injection) end of the capillary, all previous publications report the formation of the resistive region at the cathode side. In our experiments, however, the anomalous region is formed at the anode. Thus, the separated DNA peaks move towards the slowly progressing resistive region. Our results indicate that the DNA is stopped at the boundary and does not enter the region. When the resistive region is clipped off the peak motion resumes. This suggests that there exists a potential barrier at the resistive layer boundary that prevents the drift of the peaks towards the anode. The formation of the resistive region interferes with a normal separation process causing a gradual decrease of the capillary current and the deceleration and eventual quenching of the peak motion. For the ABI chemistry, we experimented with adding polymers to the electrode buffer to equate the transference numbers for anions and cations, and found the conditions at which this effect is completely eliminated.