SummaryTo investigate promoter strength and the tissue-specific patterns of expression, chimeric promoters incorporating subdomains of mannopine synthese (mas2') and octopine synthase (ocs) promoter and activator regions were affixed to a ~-glucuronidase reporter gene and the constructions introduced into tobacco plants. Addition of a trimer of the ocs upstream activating sequence (UAS) to a mas promoter/activator region resulted in highly elevated levels of GUS activity in ell tissues examined. In leaf tissue, this chimeric promoter is approximately 156-fold and 26-fold stronger than are the CaMV 35S and the "enhanced" double CaMV 35S promoters, respectively. Expression of GUS activity directed by the mas and ors promoters/ activators is limited to specific cell types. Addition of the ocs or mas UAS to the mas or ocs promoter/activator regions modulated these expression patterns. The addition of a trimer of the ocs UAS to the mas promoter/activator region resulted in e transcriptional control element that directed GUS expression in most cell types. In addition to the strong expression in trensgenic tobacco plants, this novel promoter directed higher levels of GUS expression than did the CaMV 35S promoter in transiently transformed tobacco leaf discs end suspension culture cells, as well as in cassava and cowpea explants. It is proposed that the strong promoter containing a trimer of the ocs UAS affixed to the mas promoter/activator will be useful for the very high level constitutive expression of linked genes in a wide variety of plant species.

We examined the mechanism of synthesis in vitro of (133),(134)␤-D-glucan (␤-glucan), a growth-specific cell wall polysaccharide found in grasses and cereals. ␤-Glucan is composed primarily of cellotriosyl and cellotetraosyl units linked by single (133)␤-linkages. The ratio of cellotriosyl and cellotetraosyl units in the native polymer is strictly controlled at between 2 and 3 in all grasses, whereas the ratios of these units in ␤-glucan formed in vitro vary from 1.5 with 5 M UDP-glucose (Glc) to over 11 with 30 mM substrate. These results support a model in which three sites of glycosyl transfer occur within the synthase complex to produce the cellobiosyl-(133)-D-glucosyl units. We propose that failure to fill one of the sites results in the iterative addition of one or more cellobiosyl units to produce the longer cellodextrin units in the polymer. Variations in the UDP-Glc concentration in excised maize (Zea mays) coleoptiles did not result in wide variations in the ratios of cellotriosyl and cellotetraosyl units in ␤-glucan synthesized in vivo, indicating that other factors control delivery of UDP-Glc to the synthase. In maize sucrose synthase is enriched in Golgi membranes and plasma membranes and may be involved in the control of substrate delivery to ␤-glucan synthase and cellulose synthase.The mixed-linked (133),(134)␤-d-glucan (hereafter referred to as simply ␤-glucan) is a cell wall polysaccharide found only in grasses and cereals (Carpita, 1996). The ␤-glucan is not synthesized in dividing cells but accumulates specifically during cell enlargement (Carpita and Gibeaut, 1993). The ␤-glucan also accumulates in the walls of the endosperm of the developing grains and their surrounding maternal tissues (Fincher and Stone, 1986; Brown et al., 1997).The ␤-glucan structure was established by use of a sequence-dependent Bacillus subtilis endoglucanase (lichenase) that cleaves (134)␤-d-glucosyl units only if preceded by (133)␤-units and yields primarily a diagnostic trisaccharide, cellobiosyl-(133)-d-Glc, and a tetrasaccharide, cellotriosyl-(133)-d-Glc (Anderson and Stone, 1975). It is an unbranched glucan and over 90% of the polymer consists of these cellotriosyl and cellotetraosyl units in ratios ranging from 2 to 3 in grasses, each connected by a single (133)␤-linkage (Wood et al., 1991(Wood et al., , 1994. The remainder of the polymer consists of longer runs of the cellodextrin interspersed within the polymer and connected by single (133)␤-linkages (Staudte et al., 1985; Wood et al., 1994). The ratio of the odd cellodextrin oligomers is generally about 2-fold greater in abundance than the next-higher even-numbered oligomer in the series (Wood et al., 1991(Wood et al., , 1994. Although not found in any other angiosperms, a similar mixed-linkage ␤-glucan is found in the lichen Cetraria islandica (Wood et al., 1994). In the lichen ␤-glucan, the cellotriosyl units comprise 86% of the polysaccharide.Synthesis of ␤-glucan with cellular membranes was shown by digestion of the radioactive products with several e...

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Avocado oil has generated growing interest among consumers due to its nutritional and technological characteristics, which is evidenced by an increase in the number of scientific articles that have been published on it. The purpose of the present research was to discuss the extraction methods, chemical composition, and various applications of avocado oil in the food and medicine industries. Our research was carried out through a systematic search in scientific databases. Even though there are no international regulations concerning the quality of avocado oil, some authors refer to the parameters used for olive oil, as stated by the Codex Alimentarius or the International Olive Oil Council. They indicate that the quality of avocado oil will depend on the quality and maturity of the fruit and the extraction technique in relation to temperature, solvents, and conservation. While the avocado fruit has been widely studied, there is a lack of knowledge about avocado oil and the potential health effects of consuming it. On the basis of the available data, avocado oil has established itself as an oil that has a very good nutritional value at low and high temperatures, with multiple technological applications that can be exploited for the benefit of its producers.

A family of Golgi-localised molecules was recently described in animals and fungi possessing extensive coiled regions and a short (approximately 40 residues) conserved C-terminal domain, called the GRIP domain, which is responsible for their location to this organelle. Using the model plant Arabidopsis thaliana, we identified a gene (AtGRIP) encoding a putative GRIP protein. We demonstrated that the C-terminal domain from AtGRIP functions as a Golgi-targeting sequence in plant cells. Localisation studies in living cells expressing the AtGRIP fused to a DsRed2 fluorescent probe, showed extensive co-location with the Golgi marker alpha-mannosidase I in transformed tobacco protoplasts. GRIP-like sequences were also found in genomic databases of rice, maize, wheat and alfalfa, suggesting that this domain may be a useful Golgi marker for immunolocalisation studies. Despite low sequence identity amongst GRIP domains, the plant GRIP sequence was able to target to the Golgi of mammalian cells. Taken together, these data indicate that GRIP domain proteins might be implicated in a targeting mechanism that is conserved amongst eukaryotes.