Biological clocks help reduce the physiological conflicts in avian migrants

We present evidence from experiments on overwintering populations of two Palearctic-Indian latitudinal migratory birds, the black-headed bunting (Emberiza melanocephala) and the red-headed bunting (E. bruniceps), that the bird’s clock in interaction with day length regulates seasonal rhythms of migration and reproduction such that physiological conflict between them is reduced. Initiation and termination of the body mass and testicular cycles are separately regulated photoperiodic events. For example, under stimulatory photoperiods the response curve of body mass does not overlap with that of the testicular growth. A response-specific photoperiodism is adaptive, since gain in body mass, critical to spring migration, precedes gonadal recrudescence. Finally, migration as indicated by the night-time migratory restlessness under experimental situations (e.g., intense locomotion under caged condition-called Zugunruhe) appears to be regulated by a separate circadian oscillator.     

Holistic process development to mitigate proteolysis of a subunit rotavirus vaccine candidate produced in Pichia pastoris by means of an acid pH pulse during fed-batch fermentation

To meet the challenges of global health, vaccine design and development must be reconsidered to achieve cost of goods as low as 15¢ per dose. A new recombinant protein-based rotavirus vaccine candidate derived from non-replicative viral subunits fused to a P2 tetanus toxoid CD4(+) T cell epitope is currently under clinical development. We have sought to simplify the existing manufacturing process to meet these aims. To this end, we have taken a holistic process development approach to reduce process complexity and costs while producing a product with the required characteristics. We have changed expression system from Escherichia coli to Pichia pastoris, to produce a secreted product, thereby reducing the number of purification steps. However, the presence of proteases poses challenges to product quality. To understand the effect of fermentation parameters on product quality small-scale fermentations were carried out. Media pH and fermentation duration had the greatest impact on the proportion of full-length product. A novel acidic pH pulse strategy was used to minimize proteolysis, and this combined with an early harvest time significantly increased the proportion of full-length material (60–75%). An improved downstream process using a combination of CIEX and AIEX to further reduce proteases, resulted in maintaining product quality (95% yield).