Aleurone layers

As vitamin Bg is mainly located in the germ and aleurone layer in cereal grains polishing for the production of flour removes a substantial portion. White bread is therefore a poor source unless fortified. Some nonedible yeasts contain up to 38 mg/100 g dry weight vitamin B, the highest level of the natural sources (4,27). As a rule, these amounts are too low for cost-effective isolation. 

Aleuron-kom, m. Bot.) aleurone grain -schicht, /. Bot.) aleurone layer. 

Kleberschicht, /. Boi.) aleurone layer. Klebe-stoff, m. adhesive substance, cement adhesive binder, -streifen, m. adhesive tape, -taffet, m. court plaster, -wachs, n. acUiesive wax, sticking wax. -zettel, m. gummed label, sticker, klebfahig, a. adhesive. 

Hanson, A.D. Jacobsen, J.V. (1984). Control of lactate dehydrogenase, lactate glycolysis and a-amylase of O2 deficit in barley aleurone layers. Plant Physiology, 75, 566-72. 

Fig. 4 Graphic showing the structural features of a seed coat and endosperm of a radish seed, according to Vaughan and Whitehouse (1971). e, epidermis p, palisade pi, pigment layer al, aleurone layer hi, hyalin layer. 

Fig. 6 TEM micrographs of seed coat and aleurone cells of radish control seed 18 h after sowing in water e, epidermis pi, pigment layer al, aleurone layer. (A) Bar = 30 pm Particulars of the aleurone cell showing some organelles nucleus (n), plasmodesmata (pd), protein bodies (pb) and lipid droplets (Id). (B, C). Bar = 5 mm. 

The process of infection of lupine nodule cells by Rhizobia was examined by the thin-section electron microscopic technique, as well as the freeze-fracture technique. Different membranes such as infection thread membranes, peribacterioid membranes, plasma membranes, membranes of cytoplasmic vesicles, and membranes of the Golgi bodies and ER were stained with uranium-lead, silver, phosphotungstic acid, and ZIO (31). ZIO stained the membranes of the proximal face of the Golgi bodies and endoplasmic reticulum. ZIO staining has given good contrast in thick sections such as a cotyledon cell, a root cell, and an aleurone layer for ER, dictyosomes cisternae, mitochondria, and nuclear envelopes (17,32-37). 

Aleuritic acid, physical properties of, 5 35t Aleurone layer, 3 567 Alexandrite, color of, 7 331 Ale yeast, 3 580... 

Figure 1. Scanning electron micrograph of the cell wall preparations obtained from the different parts of rice grain (7). Caryopsis coat (upper left), aleuron layer (upper right), germ (lower left) and starchy endosperm (lower right). Bars in the picture indicate 5 /zm.

While the hemicelluloses obtained from the germ, aleuron, and caryopsis coat cell walls all showed a similar monosaccharide composition, this was not the case for the endosperm tissue. Thus, a major difference in the structure of hemicellulosic polysaccharides exists between the preparations obtained from the endosperm cell walls and those from the cell walls of the other parts of the grain, i.e., rice bran. (Rice bran consists of the caryopsis coat, aleuron layer and germ.) Comparison of the detailed structural features of the hemicellulosic polysaccharides of endosperm and bran cell walls will be discussed in the following sections. 

Bi Thiamine Green peas, spinach, aleurone layer of unpolished rice, organ meats, beef, pork Depending on total caloric intake <1 yr 0.2 mg 1-13 yr 0.3-0.8 mg >13 yr 1.1 mg pregnancy 1.4 mg lactating women 1.7 mg... 

A similar time course for translatable mRNA has been reported (lA) in barley aleurone layers, in response to glbberel-lic acid. Total poly(A) RNA was found to Increase dramatically in the first 12 hr after hormone application, followed by a rapid decline to 25% of the maximum at 18 hr. On the other hand, the accumulation of ovalbumin mRNA in response to progesterone in chick oviducts (15) is an example that does not appear to behave in this manner. 

It is now supposed that gibberellic acid stimulates the hormonal production of a-amylase (and, probably, of /9-amylase and others) in the aleurone layer surrounding the endosperm starch-reserve. Gibberellic acid released 400 mg. equivalents of D-glucose per g. in 90 hours in wheat grains, with a maximum hydrolytic activity after 60 hours. The effect on /9-amylase was thought to be a release (to the extent of 85%) from the protein-bound, insoluble form.876... 

In the germination of cereal seeds, it was long known by brewers that if the embryo was excised (or dead) the endosperm would not be hydrolyzed and sugars would not be released. In 1960, Paleg showed that amylolytic activity in the embryo-less half could be fully restored in the presence of gibberellin. In other words, the substance that passed from the embryo to the endosperm (or rather, to the living cells of the aleurone layer that encloses the dead endosperm) induces there the synthesis of a-amylase which is responsible for hydrolysis of the stored starch reserves held in the endosperm. The extent to which the a-amylase was induced became another bioassay for gibberellin. 

Phenolic acids, and especially ferulic acid, which is abundantly present in cereals, is found esterified to the polysaccharides present in primary and secondary cell walls of plants. Ferulic acid is the major phenolic acid occurring in the cell walls of monocotyledons and appears as cis and the more abundant trans isomers (reviewed in [Klepacka and Forna, 2006]). Ferulic acid is found in wheat, maize, rye, barley [Sun et al., 2001], oats, spinach, sugar beet, and water chesnuts [Clifford, 1999], generally esterified, and rarely as free form, such as in barley [Yu et al., 2001]. It is esterified in primary cell walls to arabinoxylans (Fig. 2.4) in the aleurone layer and pericarp [Clifford, 1999], as in spinach [Fry, 1982] or in wheat bran [Smith and Hartley, 1983], Ferulic acid can also be found esterified to other hydroxycinnamic acids such as in Mongolian medicinal plants where it is found as feruloylpodospermic acid, which is... 

Fig. 3. Translation products of barley aleurone layer mRNAs. Lanes 1-4, total products from layers treated in water (control), 1 jxm ABA, 1 pM GA3, or both hormones, respectively. The rab 6 protein is marked with an arrow. Lanes 5-8, immunoprecipitation of a-amylase (upper bands) and the a-amylase/subtilisin inhibitor (lower bands) from the translation products shown in lanes 1-4. mRNA extraction, translation and immunoprecipitation were performed as previously described (Mundy etal., 1986).

Hong, B., Uknes, S.J. Ho, T.-H.D. (1988). Cloning and characterization of a cDNA encoding mRNA rapidly induced by ABA in barley aleurone layers. Plant Molecular Biology 11, 495-506. 

Roles of Metabolites of Abscisic Acid. Nothing is known about the physiological role of PA and DPA in plants, although these two metabolites of ABA have been tested in several bioassays recently. In the cotton explant abscission assay PA had one-tenth of the activity of ABA (19). PA and DPA were equally effective in inhibiting a-amylase secretion by barley aleurone layers treated with glbberellin A3 DPA had approximately one-tenth of the activity of ABA in this system (74). The effect of PA on growth of bean embryos was negligible (75). 

Ho, D. T. Response of barley aleurone layers to abscisic acid. Plant Physiol., 1976, 57, 175-178. 

Jacobsen, J. V. Varner, J. E. Gibberellic acid-induced synthesis of protease by isolated aleurone layers of barley. Plant Physiol., 1967, 42, 1596-1600. 

Jacobsen, J. V. Know, R. B. The proteins released by isolated barley aleurone layers before and after gibberellic-acid treatment. Planta, 1974, 115, 193-206. 

Jacobsen, J. V. Zwar, J. A. Gibberellic acid and RNA synthesis in barley aleurone layers metabolism of rRNA and tRNA and of RNA containing polyadenylic acid sequences. 

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