In this study,

we investigated endosperm development in interspecific crosses between diploid Oryza species. In a cross between female O. sativa and male O. punctata, we found that the hybrid endosperm was reduced in size and this cross was associated with precocious developmental transition. By contrast, the cross between O. sativa and O. longistaminata generated enlarged hybrid endosperm at the mid-point of seed development and this cross was associated with delayed developmental transition. Subsequently, the hybrid endosperm displayed a shriveled appearance selleck at the seed maturation stage. We found that the accumulation of storage products and the expression patterns of several marker genes were also altered in the hybrid endosperm. By contrast, the rate of Adavosertib nmr syncytial mitotic nuclear divisions was not significantly affected. The gene OsMADS87 showed a maternal origin-specific expression pattern in rice endosperm, in contrast to its Arabidopsis homologue PHERES1, which shows paternal origin-specific expression.

OsMADS87 expression was decreased or increased depending on the type of developmental transition change in the hybrid rice endosperm. Our results indicate that one of the interspecies hybridization barriers in Oryza endosperm is mediated by precocious or delayed developmental alterations and de-regulation of OsMADS87, without change to the rate of syncytial mitotic nuclear division in the hybrid endosperm.”
“In aerobic process oxygen must be continuously supplied in order to achieve acceptable productivities. Since the role of oxygen in microorganism growth and its metabolism is of vital importance, both the oxygen consumption by the cell and the oxygen transfer rate (OTR)

into the system have to be understood.

The main function of a properly designed bioreactor is to provide a controlled environment and a concentration of nutrients (dissolved oxygen, mainly) sufficient to achieve optimal growth and/or optimal Selleck GSK461364 product formation in a particular bioprocess. Dissolved oxygen in the broths is the result of a balance of its consumption rate in the cells, and the rate of oxygen transfer from the gas to the liquid phase. Monitoring dissolved oxygen in the broth is mandatory because often oxygen becomes the factor governing the metabolic pathways in microbial cells.

In this work the oxygen uptake rate (OUR) in different fermentation broths is examined. Experimental techniques have been compiled from the literature and their applicability to microbial processes reviewed. The reciprocal influence of OUR and OTR is presented and an analysis of rate-limiting variables is carried out.

Mathematical models are a fundamental tool in bioprocess design, optimisation, scale-up, operation and control at large-scale fermentation. Kinetic models describing aerobic bioprocesses have to include an oxygen balance taking into account OTR and OUR.