No abstract

Iron (Fe) deficiency primarily damages photosystems. A large proportion of the reducing equivalents in mesophyll cells are dependent on the photosynthetic apparatus in the chloroplasts; thus, Fe deficiency profoundly affects nitrogen (N) and sulfur (S) assimilation. Microarray data suggested that nutrient metabolisms concerning the assimilation and re-utilization of essential elements were modulated in barley under Fe-deficient condition. We compared the concentrations of the major essential elements between Fe-deficient barley leaves and Fe-deficient rice leaves. The Fe-deficient barley and rice plants had the same Fe and chlorophyll concentrations, but growth was reduced more in Fe-deficient rice than in Fe-deficient barley. The accumulation of ribulose-1,5-bisphosphate carboxylase/oxygenase protein and nitrite reductase, sulfite reductase, and ferredoxin-dependent glutamate synthase mRNAs was reasonably decreased in the chlorotic young leaves of Fe-deficient barley. NH , and Ca 2þ concentrations were altered to a larger extent in Fe-deficient rice leaves than in Fe-deficient barley leaves, even in the non-chlorotic old leaves. In this paper, we discuss the adaptation of macronutrient metabolism to Fe deficiency in barley leaves.

Post-anoxic denifitrication process can remove nitrogen from wastewater at a lower cost than pre-anoxic denitrification process since the nitrified water is not circulated during this process unless exogenous carbon addition is required. However, the denitrification rate is generally lower than that of a pre-anoxic process because endogenous carbon sources within the denitrifying bacteria are used as electron donors. The objective of this study was to develop a better understanding of this endogenous denitrification rate. A sequencing batch reactor fed with propionate was operated under variable anaerobic-aerobic conditions for 26 days to allow the biomass to accumulate polyhydroxyalkanoate (PHA) and glycogen stores. Sludge samples were collected from the reactor periodically, and nitrate removal rates were measured in the absence of any external carbon sources. Nitrate reduction rates ranged from 1.20 to 2.74 mgN/gMLSS/h. Meanwhile, PHA consumption (1.04 -8.01 mgC/gMLSS/h) and glycogen synthesis (0 -4.74 mgC/gMLSS/h) and consumption (0 -1.54 mgC/gMLSS/h) were observed. The PHA consumption correlated positively with the nitrate reduction rate. Furthermore, glycogen consumption seemed to reduce both PHA consumption and nitrate reduction.