Mosaic development

Duffy I.B., Harrison D.A. and Perrimon N. 1998. Identifying loci required for follicular patterning using directed mosaics. Development 125 2263-2271. 

Hurst (19) discusses the similarity in action of the pyrethrins and of DDT as indicated by a dispersant action on the lipids of insect cuticle and internal tissue. He has developed an elaborate theory of contact insecticidal action but provides no experimental data. Hurst believes that the susceptibility to insecticides depends partially on the cuticular permeability, but more fundamentally on the effects on internal tissue receptors which control oxidative metabolism or oxidative enzyme systems. The access of pyrethrins to insects, for example, is facilitated by adsorption and storage in the lipophilic layers of the epicuticle. The epicuticle is to be regarded as a lipoprotein mosaic consisting of alternating patches of lipid and protein receptors which are sites of oxidase activity. Such a condition exists in both the hydrophilic type of cuticle found in larvae of Calliphora and Phormia and in the waxy cuticle of Tenebrio larvae. Hurst explains pyrethrinization as a preliminary narcosis or knockdown phase in which oxidase action is blocked by adsorption of the insecticide on the lipoprotein tissue components, followed by death when further dispersant action of the insecticide results in an irreversible increase in the phenoloxidase activity as a result of the displacement of protective lipids. This increase in phenoloxidase activity is accompanied by the accumulation of toxic quinoid metabolites in the blood and tissues—for example, O-quinones which would block substrate access to normal enzyme systems. The varying degrees of susceptibility shown by different insect species to an insecticide may be explainable not only in terms of differences in cuticle make-up but also as internal factors associated with the stability of oxidase systems. 

Whenham, R.J., Fraser, R.S.S., Brown, L.P. Payne, J.A. (1986). Tobacco-mosaic-virus-induced increase in abscisic-acid concentration in tobacco leaves Intracellular location in light and dark-green areas, and relationship to symptom development. Planta, 168, 592-8. 

The development of high-magnification microscopy made it possible to create images of biological materials at the molecular level. Many of these images show structures that have liquid crystalline aspects. Shown here are aligned mosaic virus molecules and protein molecules in voluntary muscles. In addition, all cell walls are picket fences of rod-shaped molecules in regular yet fluid arra. ... 

Porter, S. )., and Meyer, C. J. (1994). A distal tyrosinase upstream element stimulates gene expression in neural-crest-derived melanocytes of transgenic mice position-independent and mosaic expression. Development 120 2103-2111. 

The first hurdle encountered during the development of alfalfa as a recombinant protein production system was the relative inefficiency of the available expression cassettes. A study in which a tomato proteinase inhibitor I transgene was expressed in tobacco and alfalfa under the control of the cauliflower mosaic virus (CaMV) 35S promoter showed that 3-4 times more protein accumulated in tobacco leaves compared to alfalfa leaves [5]. Despite the low efficiency of the CaMV 35S promoter in alfalfa, bio-pharmaceutical production using this system has been reported in the scientific literature. Such reports include expression of the foot and mouth disease virus antigen [6], an enzyme to improve phosphorus utilization [7] and the anti-human IgG C5-1 [8]. In this last work, the C5-1 antibody accumulated to 1% total soluble protein [8]. 

As indicated in Table 2.1, most of the promoters used in plant tissue culture have been based on the constitutive cauliflower mosaic virus (CaMV) 35S promoter. In contrast, inducible promoters have the advantage of allowing foreign proteins to be expressed at a time that is most conducive to protein accumulation and stability. Although a considerable number of inducible promoters has been developed and used in plant culture applications, e.g. [32-37], the only one to be applied thus far for the production of biopharmaceutical proteins is the rice a-amylase promoter. This promoter controls the production of an a-amylase isozyme that is one of the most abundant proteins secreted from cultured rice cells after sucrose starvation. The rice a-amylase promoter has been used for expression of hGM-CSF [10], aranti-trypsin [12, 29, 38, 39] and human lysozyme [30]. 

The majority of viruses that infect plants have single-stranded, positive-sense RNA genomes. It has therefore been necessary to use infectious cDNA clones for the in vitro manipulation of RNA viruses, allowing them to be developed as effective tools for the commercial production of target proteins in plants. This approach has also been used to study the genetic and metabolic profiles of both viruses and their host plants. Siegel [14] conceptualized the potential use of RNA viruses as expression vectors. Brome mosaic virus (BMV) and Tobacco mosaic vims (TMV) were the first two RNA viruses to be converted into expression vectors. These vectors have since been pro-... 

Canine parvovirus (CPV) VP2 epitope Epitope display on cowpea mosaic virus in cowpea leaf Immunogenic in mice when delivered parenter-ally or nasally. Dogs developed 3L17- and VP2-specific IgG sera neutralized CPV in vitro. Protective against lethal challenge in dogs immunized parenterally. 76, 77... 

Murine hepatitis virus Tobacco mosaic virus Mice developed serum IgG and IgA specific for Protective in mice immunized parenterally 105... 

Mutations may also occur in a single cell within an early embryo. As all the cells divide during growth and development, the individual will have some cells with the mutation and some cells without the genetic change. This situation is called mosaicism. 

Symptoms These vary from plant to plant. In cucurbits, the virus causes mottling or mosaic patterns (see p.89) and distortion on the leaves. Flowering is reduced plants are stunted and may die. Fruits will be small, dark, and pitted, and may develop bright yellow blotches. 

There are reports that plant virus inhibitors occur naturally in plants, and they could be proteins, glycoprote -ins, polysaccharides, phenols etc(7 5). Extracts of mosses, especially Sphagnum(76), algae(77) and Cassia of the family Leguminosae(7S) are effective in inhibiting tobacco mosaic virus(TMV), but much more work is needed to develop virici-des that may be sprayed safely and economically on crop plants in the field. 

In somatic mosaicism, mutation of a gene occurs in a non-germline (somatic) cell at some point during early development of the person, and all cells de-scendent from that progenitor are genetically distinct. 

All females are technically mosaic for the genes of their X chromosomes due to inactivation of one or the other X chromosomes early in development, a phenomenon termed the Lyon hypothesis or lyonization. 

According to the above developed considerations, surfaces can be described as a mosaic-like structure of which individual elements contribute locally and specifically to their residual binding capacity and their electrical potential. The individual characteristics of these elements and their microtopography determine, via a first series of interactions with water molecules and small solutes, which plasma... 

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