Cuticle membrane

The resistant membranes in the CMC originate particularly from intracellular-membrane-associated regions, which form an envelope lining of cortical and cuticle cells [16]. An important difference between resistant membranes in cuticle and cortical cells is the presence of citrulline and ornithine in the cuticle membranes [166]. Some of the common features in the... 

Figure 8.1. Generalized scheme for the structure of the plant cuticle membrane. ...

Shafer and Bukovac examined sorption of Triton X-100 by isolated tomato cuticles and concluded that orientation of absorbed surfactant molecules on the surface of the cuticle membrane (CM) may be important. If the OP surfactant molecules formed a monolayer on the CM, the hydrophilic moiety would be oriented farthest away from the CM, thus imparting a relatively more polar chemical environment. If multiple layers of surfactant molecules were adsorbed by the CM, then the overall surface chemistry would depend on complex solution-sorbed molecule-CM interactions. This would influence the sorption and subsequent penetration of an a.i. through the cuticle. 

In fine wool such as that obtained from merino sheep, the cuticle is normally one cell thick (20 x 30 x 0.5 mm, approximate dimensions) and usually constitutes about 10% by weight of the total fiber. Sections of cuticle cells show an internal series of laminations (Figs. 1 and 2) comprising outer sulfur-rich bands known as the exocuticle and inner regions of lower sulfur content called the endocuticle (13). On the exposed surface of cuticle cells, a membrane-like proteinaceous band (epicuticle) and a unique hpid component form a hydrophobic resistant barrier (14). These hpid and protein components are the functional moieties of the fiber surface and are important in fiber protection and textile processing (15). 

The egg shell is 94% calcium carbonate [471-34-17, CaCO, 1% calcium phosphate [7758-23-8] and a small amount of magnesium carbonate [546-93-0]. A water-insoluble keratin-type protein is found within the shell and in the outer cuticle coating. The pores of the shell allow carbon dioxide and water to escape during storage. The shell is separated from the egg contents by two protein membranes. The air cell formed by separation of these membranes increases in size because of water loss. The air cell originally forms because of the contraction of the Hquid within the egg shell when the temperature changes from the body temperature of the hen at 41.6°C to a storage temperature of the egg at 7.2°C. 

Late lethargus is characterized by the formation of the new cuticle, which arises externally to the cell membrane of the hypodermis, and thus represents a true extracellular matrix. The epicuticular and cortical layers are the first to be formed and these layers are enriched in the highly... 

The major function of cutin is to serve as the structural component of the outer barrier of plants. As the major component of the cuticle it plays a major role in the interaction of the plant with its environment. Development of the cuticle is thought to be responsible for the ability of plants to move onto land where the cuticle limits diffusion of moisture and thus prevents desiccation [141]. The plant cuticle controls the exchange of matter between leaf and atmosphere. The transport properties of the cuticle strongly influences the loss of water and solutes from the leaf interior as well as uptake of nonvolatile chemicals from the atmosphere to the leaf surface. In the absence of stomata the cuticle controls gas exchange. The cuticle as a transport-limiting barrier is important in its physiological and ecological functions. The diffusion across plant cuticle follows basic laws of passive diffusion across lipophylic membranes [142]. Isolated cuticular membranes have been used to study this permeability and the results obtained appear to be valid... 

The ability of these chemicals to penetrate the cuticle, the cell membrane, move into the protoplast and distribute in the plant is to a large measure dependent upon the hydrophilic/ lipophilic balance, the steric configuration and its stalaility in or on the plant. Similarly, these same chemical and physical factors are critical for toxicity of the chemical to the fungus. 

The hydrophobic waxy cuticle of plants can inhibit the movement and accessibility of nutrients to bacterial cells. However, biosurfactants produced by the majority of epiphytic Pseudomonas spp. decreases the water tension, enabling relatively free movement across the leaf surface to nutrient sources and natural openings such as stomata. Pseudomonas are also known to release a toxin called syringomycin that can produce holes in the plant cell membrane allowing access to intracellular nutrients without necessarily resulting in disease symptoms (Cao et al.r 2005). 

Wedral, E., Vadehra, D. V., Baker, R. C. Chemical composition of the cuticle, and the inner and outer shell membranes from eggs of Callusgallus. Comp. Biochem. Physiol. 47B, 631 (1974)... 

A particularly large dataset has come from the study of cuticle-water partition coefficients determined using batch experiments with isolated cuticles (Kerler and Schonherr, 1988). The cuticle, a lipophilic membrane covering all leaves, is an important storage compartment for lipophilic organic compounds in vegetation. 

In contrast, the hydrocarbon contact sex pheromone of the German cockroach is synthesized in Class II oenocytes associated with the abdominal stemites (Young et al., 1999 Fan et al., 2002). These large oenocytes, ranging up to 50 p in in diameter in B. germanica, have abundant mitochondria and extensive smooth endoplasmic reticulum (Fan et al., 2002). Although the oenocytes are associated with abdominal stemites, the hydrocarbons are released into the hemolymph and loaded, probably across a plasma membrane reticular system, into high-density lipophorin. The lipophorin then likely transports the hydrocarbon to epidermal cells for release onto the cuticle (Fan et al., 2002). 

Both the cuticle and cortical cells are bounded by cell membranes that, together with the intercellular material, are known as the cell membrane complex (Marshall, Orwin, and Gillespie 1991). This consists of the (Mayers, protein-lipid complexes (-5 nm thick) on either side of the 6-layer, and an intercellular cement (-15 nm thick) (Baden 1990) rich in amino and carboxyl... 

Foliar uptake of elements is believed to consist of two phases non-metabolic cuticular absorption which is generally considered to be the major route of entry and metabolic mechanisms which account for element accumulation against a concentration gradient. Passsage through the cuticle is possible only by diffusion (Ziegler, 1988 Reiderer, 1991). The second process is responsible for transporting ions across the plasma membrane and into the cell protoplast. 

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