Nutrient requirements Manganese

In chemical oceanography, it has been demonstrated that some nutrients required for the survival of microorganisms in seawater contain zinc, iron and manganese as enzyme cofactors. 

Nutrients required by crops can be divided up into major elements and micro (trace) elements (Table 4.2). Micro (trace) elements include boron, copper, iron, manganese, molybdenum, zinc and cobalt, some of which are dealt with later in this chapter. 

It is clear from the data in Table 3 that depletion can be a significant factor which affects the ability of mineral soils to meet the nutrient requirements of plants with respect to molybdenum, boron and copper and that when the total soil levels of these elements are low, crop requirements can only be met for limited periods. For example, an acre of soil containing only 1 ppm boron cannot possibly produce more than 100 tons of crop dry matter with a content of 10 ppm boron. In practice, the boron content is likely to be around 40 ppm in the dry matter and this would limit the total possible yield on such a soil to 25 tons of crop dry matter. Deficiency conditions involving these elements are therefore inevitable within decades on cultivated land, if no steps are taken to replace cropping losses. Deficiency problems involving manganese and cobalt, on the other hand, are more likely to be due to a reduction of availability in the soil than to depletion of the total soil reserves. 

PREVENTION OF NUTRITIONAL DEFICIENCIES IN DIABETICS. It was mentioned earlier that diabetes may be brought on and/or aggravated by deficiencies of the essential nutrients chromium, manganese, potassium, pyri-doxine (vitamin B-6), or zinc. This is not to say that the basic nutrient requirements of diabetics are significantly different from nondiabetics it is only to note that (1) a few people may show diabetic tendencies due to deficiencies... 

The carbohydrate (again often molasses, 15 - 25%) and added nutrients are pH-adjusted to below 4.0 and, for Otis process, have to be sterilised. It is necessary to add potassium hexacyanoferrate but greater care is required in this process compared to surface culture. The A. niger seems to be more sensitive to and more easily inhibited by hexacyanoferrate in submerged culture. It is essential however to lower the ferrous and manganese concentrations, probably below 200 and 5 pg l1 respectively, to optimise the performance of A. niger. 

We have described the initial functions of calcium outside cells in Section 5.5. Here we draw attention again to its later function in association with manganese in 02 production, described in the previous section (see Figure 5.9). We have also left out of this chapter any reference to vanadium as the first functional use of it known to us is in nitrogenase which was probably not required in the earliest organisms (see Section 6.5). The sodium gradient was utilised to cotransport nutrients into cells and this function remains a major use of the Na+ ion in later organisms. 

Manganese is a cofactor of enzymes involved in energy metabolism and is required for hemoglobin synthesis, thiamin utilization and tendon and bone formation. Unlike nutrients that fulfil unique func-... 

The essentiality of manganese (Mn) for animals was established in 1931 by Orent and McCollum (1) who reported that this element is required for normal reproduction in the rat, and Kemmerer and colleagues (2) who showed that it was necessary for normal growth and reproduction in the mouse. Since then several investigators have verified the critical need of this nutrient for normal development (3). Manifestations of perinatal Mn deficiency in experimental animals include neonatal death, impaired growth, skeletal abnormalities, depressed reproductive function, congenital ataxia, and defects in protein, carbohydrate and lipid metabolism. 

When 7-day diet composites were collected during the four seasons of the year, Patterson et al. (37) found a mean intake of 3.0 mg Mn/day and a nutrient density of 1.6 mg Mn/1000 kcal. Based on this figure, a consumption of 1560 kcal would be adequate to meet the lower limit of the suggested safe and adequate range (63). However, in Fig. 1 the theoretical point of equilibrium is 3.55 mg and it appears that approximately 5 mg is needed to consistently maintain positive balance. These would require a daily consumption of 2250 and 3125 Kcal, respectively. Thus, it seems plausible that some individuals may be at risk for being in negative manganese balance. 

The plants that were the precursors of the coal required a range of elements as nutrients or for stmctural support. Elements essential to plant metabolism include phosphoms, potassium, sulfur, calcium, and magnesium. Some plants also require boron, chlorine, copper, iron, manganese, molybdenum, and zinc (Severson and Shacklette, 1988). Plants may contribute inorganic constituents... 

Studies in humans indicate that manganese is an essential element (Doisy 1973 Friedman et al. 1987). However, a Recommended Dietary Allowance (RDA) has not been established for manganese because data have been insufficient to determine nutrient needs of healthy persons (NRC 1989). However, the Food and Nutrition Board of the National Research Council establishes ESADDI levels for an essential nutrient when information is sufficient to establish a range of requirements but insufficient for establishing an RDA. 

There are thirteen mineral nutrients that plants obtain from the soil, and these are divided into the categories of macronutrients and micronutrients. The primary macronutrients include nitrogen, phosphorus, and potassium. Plants require these primary macronutrients in relatively large quantities and deplete them from the soil more rapidly than others. The secondary macronutrients include calcium, magnesium, and sulfur. Micronutrients are required in smaller quantities than the macronutrients, and these include boron, copper, iron, chloride, molybdenum, manganese, and zinc. 

An Estimated Average Requirement (EAR) is the average daily nutrient intake level estimated to meet the requirements of half of the healthy individuals in a group. EARs have not been established for vitamin K, pantothenic acid, biotin, choline, chromium, fluoride, manganese, or other nutrients not yet evaluated via the DRI [cocess... 

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