Nodule formation

In some cases pectinolytic enzymes have been associated with virulence and it is generally accepted that pectinolysis by these bacteria facilitates their entry and spread in plant tissue. In Rhizohium, these enzymes may play a role in the root infection process that precedes nodule formation (Hubbell et al 1978). A. irakense has never been reported to be pathogenic on plants. It can therefore be speculated that moderate and strictly regulated pectinolysis of A. irakense facilitates entry in the outer cortex of plants roots, since A. irakense has been isolated from surface-sterilized roots. It is likely that breakdown of plant polysaccharides by root colonizing bacteria can provide them with extra carbon source. 

The hydrogenous mode of nodule formation involves the direct precipitation of solutes from seawater via the following reactions ... 

Example 2 Certain plant root exudates contain factors stimulating soybean root growth as well as nodule formation. These stimulating factors contain protein as well as several other chemical components. This research is still at a very early stage, and it will take additional effort to characterize these factors and enormous developmental work before they can be commercialized. It may become too expensive for a company to develop this type of minor special-use product. 

FIGURE 8.7 Model for the role of Rhizobium- nd xwhite clover. (Redrawn from Mathesius, U., J. Exp. Bot., 52, 419, 2001. With permission of Oxford University Press.)... 

Limonene and perillic acid remarkably reduced the lung metatastatic tumour nodule formation by 65 and 67%, respectively however, perillyl alcohol was considerably more potent than limonene against breast cancer [284, 302], rat mammary cancer and pancreatic tumours [288]. Phase 1 studies of d-limo-nene [303, 304] and phase I and phase II [305-311] studies of perillyl alcohol revealed dose-limiting toxicities nausea, vomiting, anorexia, unpleasant taste and eructation, and thus a maximum tolerated dose for perillyl alcohol was determined [305]. 

Mathesius U, Schlaman FIRM, Spaink PIP, Sautter C, Rolfe BG, Djordjevic MA. 1998. Auxin transport inhibition precedes root nodule formation in white clover roots and is regulated by flavonoids and derivatives of chitin oligosaccharides. Plant J 14 23-34. 

Wasson AP, Pellerone FI, Mathesius U. 2006. Silencing the flavonoid pathway in Medicago truncatula inhibits root nodule formation and prevents auxin transport regulation by rhizobia. Plant Cell 18 1617-1629. 

Once an appropriate Rhizobium species infects the host plant roots, the plant responds by sequentially turning on a set of specific genes which are required for nodule formation and function. A number of nodule-specific... 

Strittmatter, G., Chia, T.-F., Trinh, T.H., Katagiri, F., Kuhlemeier, C. Chua, N.-H., (1989). Characterization of nodule-specific cDNA clones from Sesbania rostrata and expression of the corresponding genes during the initial stages of stem nodules and root nodules formation. Molecular Plant-Microbe Interactions 2, 122-7. 

The same study shows that mice orally administered microcystin-LR at higher dose showed no evidence of liver injury or nodule formation. 

Giovanoli R. and Arrhenius G. (1988) Structural chemistry of marine manganese and iron minerals and synthetic model compounds. In The Manganese Nodule Belt of the Pacific Ocean Geological Environment, Nodule Formation, and Mining Aspects (ed. P. Halbach). Eerdinand Enke Verlag, pp. 20-37. 

Some of the antipsychotics are available as intramuscular injections for patients who are imable or unwilling to swallow tablets (as is common in psychosis or severe behavioural disturbance). Halo-peridol is most often used for these indications on psychiatric inpatient wards (chlorpromazine i.m. being restricted due to hypotension and skin nodule formation). Olanzapine may be given i.m. 

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