Chromophore-assisted light inactivation and self-organization of microtubules and motors.

Chromophore-assisted light inactivation (CALI) offers the only method capable of modulating specific protein activities in localized regions and at particular times. Here, we generalize CALI so that it can be applied to a wider range of tasks. Specifically, we show that CALI can work with a genetically inserted epitope tag; we investigate the effectiveness of alternative dyes, especially fluorescein, comparing them with the standard CALI dye, malachite green; and we study the relative efficiencies of pulsed and continuous-wave illumination. We then use fluorescein-labeled hemagglutinin antibody fragments, together with relatively low-power continuous-wave illumination to examine the effectiveness of CALI targeted to kinesin. We show that CALI can destroy kinesin activity in at least two ways: it can either result in the apparent loss of motor activity, or it can cause irreversible attachment of the kinesin enzyme to its microtubule substrate. Finally, we apply this implementation of CALI to an in vitro system of motor proteins and microtubules that is capable of self-organized aster formation. In this system, CALI can effectively perturb local structure formation by blocking or reducing the degree of aster formation in chosen regions of the sample, without influencing structure formation elsewhere.

[Increase in the agglutination activity of rat blood serum following total body irradiation with supralethal doses]. / Usilenie aggliutinatsionnoi aktivnosti syvorotki krovi krys posle total'nogo oblucheniia v sverkhletal'noi doze.

Irradiation of immunized (during the decrease in the immune response, i.e. on the 14th day following the immunization with sheep erythrocytes) and nonimmunized rats leads to a considerable increase in the level of immune and normal antimicrobial antibodies 3 and 24 h following irradiation. Irradiation on the 7th day of the immune response does not cause the increase in the level of antibodies.