Assimilates acquisition

It is well known that chemical compo.sition of rhizosphere solution can affect plant growth. Particularly, uptake of nutrients may be considerably influenced by the ionic concentration of the rhizosphere solution (40). Despite the difficulty of defining the exact concentration of ions in the rhizosphere surrounding each root (or even root portion), it has been unequivocally demonstrated that plants have evolved mechanisms to cope with the uneven distribution of ions in the root surrounding in order to provide adequate supply of each essential nutrient (41). These mechanisms include expression of transporter genes in specific root zones or cells and synthesis of enzymes involved in the uptake and assimilation of nutrients (40,43). Interestingly, it has been shown that specific isoforms of the H -ATPase are expressed in the plasma membrane of cell roots it has been proposed that the expression of specific isoforms in specific tissues is relevant to nutrient (nitrate) acquisition (44) and salt tolerance (45). 

The acquisition and assimilation of bioelements are the most fundamental processes in an organism s struggle for life. It is therefore obvious that in complex natural systems the competition between thousands of species for limited quantities of a small number of elements is a major evolutionary factor. However, the individual contributions of the physical and biochemical aspects of nutrition to the fitness of an organism are widely unknown. The frequent observation that biodegradation processes, e.g. in soil remediation, are limited by physical obstacles to substrate acquisition, rather than by biochemical incapacities, points at the importance of substrate mobilisation strategies. 

How well will UPS integrate employees assimilated from its recent acquisitions into its culture and mission ... 

Nevertheless, bigger is not always better. In recent years, these largest companies have been very active as they vie with each other for market share, and a phenomenal growth in acquisitions and mergers has been observed. And it has to be said that, in the inevitable assimilation process, there has been some general concern in the overall marketplace with the quality of technical sales and services provided to end-user customers having suffered somewhat in the process. 

In the water treatment industry, the low entry-barriers and fragmentation and assimilation market forces (small, breakaway companies are regularly formed by ex-employees of large corporations, and some survive and flourish to eventually become targets for future acquisition by other large corporations) permit potentially large numbers of companies to compete within the various market sectors on a seemingly equal basis. 

The assimilation and integration of detailed information into the 5-year plan is therefore critical for decision-making regarding capital expenditure, human resource planning and promotional costs. It will also determine the need for product acquisitions, and, on a grander scale, company mergers and acquisitions. 

Molybdenum is essential to the formation and activity of assimila-tory nitrate reductases. Cells must assimilate molybdate from the environment, metabolize molybdenum in some manner to form active molybdenum cofactor, and then incorporate it into a large molecular weight protein so that it can perform a reversible redox reaction with nitrate. Investigations on the aqueous Mo (III) model systems for nitrate reduction and the coordination of molybdate by naturally produced phenolates will hopefully lead to an understanding of the complex process of molybdenum acquisitions by and molybdenum function in nitrate reductases. 

The second main class of Fem-specific sequestering agents (siderophores) responsible for the acquisition and assimilation of iron employ hydroxamate ligating groups (34).157158 186 Two important subclasses are the ferrioxamines and the ferrichromes (Figure 5). Examples are ferrioxamine B, a linear trihydroxamic acid and ferrichrome A, a cyclic hexapeptide carrying three hydroxamate-containing side chains. 

Pahnska, K. A., Laloui, W., Bedu, S., Loiseaux-de Goer, S., Castets, A. M., Rippka, R., and Tandeau de Marsac, N. (2002). The signal transducer Pn and bicarbonate acquisition in Prochlorocoaus marinus PCC 9511, a marine cyanobacterium naturally deficient in nitrate and nitrite assimilation. Microbiology. 148, 2405-2412. 

Siderophores are highly specific Fe(III) ligands (formation constants often > 10 ) and are excreted by a wide variety of fungi and bacteria to aid iron assimilation because of the low solubility of Fe + at pH values where most life exists. Siderophores are the most common means of acquisition of iron by bacteria and fungi (Crichton, 1991), and in soil, many different species, including plants, will compete for Fe. Although produced primarily as a means of obtaining iron. 

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