Undergraduate research. Genomics Education Partnership

The Genomics Education Partnership offers an inclusive model for undergraduate research experiences incorporated into the academic year science curriculum, with students pooling their work to contribute to international data bases.

Undergraduate research. Genomics Education Partnership

The Genomics Education Partnership offers an inclusive model for undergraduate research experiences incorporated into the academic year science curriculum, with students pooling their work to contribute to international data bases.

Effects of calcium channel blockers on in vivo cellular immunity in mice

In vitro studies have shown that calcium channel blockers (CCB) inhibit lectin-induced lymphocyte proliferation. However, no in vivo effects have been documented yet. In this study we evaluated the effects of CCB on in vivo cellular immunity by using contact sensitivity to oxazolone in mice. From 15 to 30 twelve-week-old female C3H mice were randomized into: 0.9 NS (sham), ethanol, CsA, dexamethasone (DXM), verapamil, diltiazem, and nifedipine groups. These study agents were given daily from day 1 to day 9 subcutaneously to the shaved abdominal wall. The mice were sensitized with oxazolone to the abdominal wall on day 2 and challenged with oxazolone on the right ear on day 8. Delayed-type hypersensitivity was measured on day 10 and defined as the difference in thickness between the right (challenged) and left (control) ear of each mouse. The mean DTH of each study group was compared with that of the sham, and the statistical significance was determined by a Student's t test. The percentage of change in DTH from the sham was also calculated as: (mean DTH of study drug group-mean DTH of sham group)/mean DTH of sham group x 100%. A negative value meant a suppressive effect on DTH; a positive value, an enhancing one. The CsA, DXM, and nifedipine all had significant suppressive effects on DTH. Verapamil had a significant enhancing effect. Ethanol and diltiazem had no significant effect. More studies employing other antigens with several other cell-mediated response measurements along with DTH quantification should be done in order to determine the specificity of the immunosuppressive effect of CCB as well as the potential of any calcium antagonist as an adjuvant suppressive agent.

Kinetic analysis for optimization of DNA ligation reactions

Kinetic equations describing ligation of DNA to circular recombinant forms were developed and solved for four types of reactions: (a) a homogeneous population of singly restricted DNA fragments, (b) insertion of singly restricted insert into vector, (c) forced directional insertion of doubly restricted insert into vector, and (d) insertion of singly restricted insert into phosphatased vector. The effects of varying vector and insert sizes, starting concentrations, and phosphatase treatment on the yield of circular 1:1 recombinants were analyzed. Selected theoretical predictions were experimentally tested and verified. Our suggestions on optimizing ligation reactions in several cases are at variance with common practice. For example, optimum conditions in case (b) and (d) ligations are best specified as individual insert and vector concentrations rather than as insert/vector molar ratios, except in case (d) ligations involving very small insert size. In case (c) ligations, highest efficiencies are obtained when both vector and insert are at relatively low concentration.

Covalent association of protein with replicative form DNA of parvovirus H-1

The double-stranded replicative form (RF) DNA of the autonomous parvovirus H-1 can be isolated from infected cells in a covalent complex with protein. The protein is present on most or all of the RF DNA, including actively replicating molecules, and is associated with the 5'-terminal endonuclease Hae III fragments of both the viral and complementary strands of RF. The size of the protein is estimated to be 60,000-70,000 daltons from its effect on buoyant density of DNA. DNA with covalently bound protein has not been found in H-1 virions.

Purification and partial characterization of a stimulatory factor for lamb thymus RNA polymerase II

A heat-stable protein (HSF) that stimulates the activity of lamb thymus RNA polymerase II has been purified 2500-fold and partially characterized. This factor stimulates the activity of RNA polymerase II up to 13 times and retains complete activity when heated at 90 degrees C for 5 min. Stimulation is observed only in the presence of RNA polymerase II and requires native DNA as template. The stimulatory factor has a sedimentation coefficient of 2.7 S, a diffusion coefficient of 9.55 x 10(-7) cm2/s, and an isoelectric point of 8.0. Calculated from the sedimentation and diffusion data, the factor has a molecular weight of about 24,000. Electrophoresis of the purified factor on polyacrylamide gels in the presence of sodium dodecyl sulfate results in a single band corresponding to a molecular weight of 25,000. The number-average length of the RNA synthesized by RNA polymerase II is increased in the presence of the factor. Sedimentation velocity and exclusion chromatography experiments suggest that the stimulatory factor interacts with RNA polymerase II. These results suggest that the factor stimulates RNA synthesis through a direct interaction with RNA polymerase II. The stoichiometry of the HSF-RNA polymerase binding appears to be about 1:1. HSF is located in the nucleus, as determined by cell fractionation studies.