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Eukaryotic development and stem cell control depend on the integration of cell positional sensing with cell cycle control and cell wall positioning, yet few factors that directly link these events are known. The DEFECTIVE KERNEL1 (DEK1) gene encoding the unique plant calpain protein is fundamental for development and growth, being essential to confer and maintain epidermal cell identity that allows development beyond the globular embryo stage. We show that DEK1 expression is highest in the actively dividing cells of seeds, meristems and vasculature. We further show that eliminating Arabidopsis DEK1 function leads to changes in developmental cues from the first zygotic division onward, altered microtubule patterns and misshapen cells, resulting in early embryo abortion. Expression of the embryonic marker genes WOX2, ATML1, PIN4, WUS and STM, related to axis organization, cell identity and meristem functions, is also altered in dek1 embryos. By monitoring cell layerspecific DEK1 down-regulation, we show that L1- and 35Sinduced down-regulation mainly affects stem cell functions, causing severe shoot apical meristem phenotypes. These results are consistent with a requirement for DEK1 to direct layer-specific cellular activities and set downstream developmental cues. Our data suggest that DEK1 may anchor cell wall positions and control cell division and differentiation, thereby balancing the plant's requirement to maintain totipotent stem cell reservoirs while simultaneously directing growth and organ formation. A role for DEK1 in regulating microtubule-orchestrated cell wall orientation during cell division can explain its effects on embryonic development, and suggests a more general function for calpains in microtubule organization in eukaryotic cells. [ABSTRACT FROM AUTHOR]

DEFECTIVE KERNEL1 (DEK1), which consists of a membrane-spanning region (DEK1-MEM) and a calpain-like Cys proteinase region (DEK1-CALP), is essential for aleurone cell formation at the surface of maize (Zea mays) endosperm. Immunolocalization and FM4-64 dye incubation experiments showed that DEK1 and CRINKLY4 (CR4), a receptor kinase implicated in aleurone cell fate specification, colocalized to plasma membrane and endosomes. SUPERNUMERARY ALEURONE LAYER1 (SAL1), a negative regulator of aleurone cell fate encoding a class E vacuolar sorting protein, colocalized with DEK1 and CR4 in endosomes. Immunogold localization, dual-axis electron tomography, and diffusion of fluorescent dye tracers showed that young aleurone cells established symplastic subdomains through plasmodesmata of larger dimensions than those connecting starchy endosperm cells and that CR4 preferentially associated with plasmodesmata between aleurone cells. Genetic complementation experiments showed that DEK1-CALP failed to restore wild-type phenotypes in maize and Arabidopsis thaliana dekl mutants, and DEK1-MEM also failed to restore wild-type phenotypes in Arabidopsis dek1-1 mutants. Instead, ectopic expression of DEK1-MEM under the control of the cauliflower mosaic virus 35S promoter gave a dominant negative phenotype. These data suggest a model for aleurone cell fate specification in which DEK1 perceives and/or transmits a positional signal, CR4 promotes the lateral movement of aleurone signaling molecules between aleurone cells, and SAL1 maintains the proper plasma membrane concentration of DEK1 and CR4 proteins via endosome-mediated recycling/ degradation. [ABSTRACT FROM AUTHOR]

DNA methylation is an epigenetic modification of cytosine that is important for silencing gene transcription and transposons, gene imprinting, development, and seed viability. DNA METHYLTRANSFERASE1 (MET1) is the primary maintenance DNA methyltransferase in Arabidopsis (Arabidopsis thaliana). Reciprocal crosses between antisense MET1 transgenic and wild-type plants show that DNA hypomethylation has a parent-of-origin effect on seed size. However, due to the dominant nature of the antisense MET1 transgene, the parent with a hypomethylated genome, its gametophyte, and both the maternal and paternal genomes of the F1 seed become hypomethylated. Thus, the distinct role played by hypomethylation at each generation is not known. To address this issue, we examined F1 seed from reciprocal crosses using a loss-of-function recessive null allele, met1-6. Crosses between wild-type and homozygous met1-6 parents show that hypomethylated maternal and paternal genomes result in significantly larger and smaller F1 seeds, respectively. Our analysis of crosses between wild-type and heterozygous MET1/ met1-6 parents revealed that hypomethylation in the female or male gametophytic generation was sufficient to influence F1 seed size. A recessive mutation in another gene that dramatically reduces DNA methylation, DECREASE IN DNA METHYLATION1, also causes parent-of-origin effects on F1 seed size. By contrast, recessive mutations in genes that regulate a smaller subset of DNA methylation (CHROMOMETHYLASE3 and DOMAINS REARRANGED METHYLTRANSFERASES1 and 2) had little effect on seed size. Collectively, these results show that maternal and paternal genomes play distinct roles in the regulation of seed size in Arabidopsis. [ABSTRACT FROM AUTHOR]

DNA methylation (5-methylcytosine) in mammalian genomes predominantly occurs at CpG dinucleotides, is maintained by DNA methyltransferase1 (Dnmt1), and is essential for embryo viability. The plant genome also has 5-methylcytosine at CpG dinucleotides, which is maintained by METHYLTRANSFERASE1 (MET1), a homolog of Dnmt1. In addition, plants have DNA methylation at CpNpG and CpNpN sites, maintained, in part, by the CHROMOMETHYLASE3 (CMT3) DNA methyltransferase. Here, we show that Arabidopsis thaliana embryos with loss-of-function mutations in MET1 and CMT3 develop improperly, display altered planes and numbers of cell division, and have reduced viability. Genes that specify embryo cell identity are misexpressed, and auxin hormone gradients are not properly formed in abnormal met1 embryos. Thus, DNA methylation is critical for the regulation of plant embryogenesis and for seed viability. [ABSTRACT FROM AUTHOR]

A T-DNA insertion in theArabidopsis thaliana DEK1gene, encoding a calpain-like cysteine proteinase with a predicted membrane anchor, causes unorganized embryo development displaying irregular mitotic divisions in the embryo proper and suspensor. Embryo development is arrested at the globular stage, and the embryo proper lacks a defined protoderm. In the endosperm, the aleurone-like peripheral cell layer is partly or completely lacking. TheArabidopsis DEK1wild-type transcript is expressed evenly throughout the endosperm and the embryo in developing seed as determined using in situ hybridization. The conclusion that the observed phenotype is caused by a T-DNA insertion in theArabidopsis DEK1gene is confirmed by complementation with theArabidopisis DEK1genomic sequence, as well as analysis of a second T-DNA insertion allele. Over-expression of theArabidopsis DEK1gene coding sequence under the control of the 35S promoter causes a number of developmental phenotypes, including a global lack of trichomes, leaves exhibiting improper dorsiventral symmetry and aberrant cell organization in flowers. We interpret the data to suggest a role forDEK1in providing cells with positional clues for an appropriate developmental context within plant tissues. [ABSTRACT FROM AUTHOR]

This is the first report on the organization of a quadripolar microtubule system (QMS) in polyplastidic meiosis of a hepatic with polar organizers (POs). Unlike the monoplastidic sporocytes of mosses and hornworts, in which meiotic quadripolarity can be traced to plastid division and migration, sporocytes ofAneura pinguisare polyplastidic and tetrahedrally lobed before the QMS is organized. Whereas the QMS in mosses and hornworts is plastid-based, the QMS ofA. pinguisis focused at four POs where gamma tubulin (?-tubulin) is concentrated. An aster of microtubules emanates from each PO centered in the four cytoplasmic lobes and the opposing radial microtubules interact to form the QMS that envelops the nucleus. A functionally bipolar spindle is gradually formed as the four poles converge in pairs on either side of opposite cleavage furrows. The resulting spindle remains quadripolar. Although ?-tubulin is most concentrated in the deeply concave poles straddling cleavage furrows, it also extends into the spindle itself. Telophase groups of chromosomes curve around the polar cleavage furrows and a phragmoplast that originates in the interzonal region guides a cell plate that extends to the equatorial cleavage furrows. Discrete POs are reformed at opposite tips of the elongated dyad nuclei in prophase II and microtubules radiating from them give rise to the spindles of second meiosis. Spindles remain sharply focused and ?-tubulin extends into distal portions of the spindle. Interzonal phragmoplasts that expand to join with pre-established cleavage furrows mediate cytokinesis resulting in a tetrad of spores. Each young tetrad member has a radial microtubule system emanating from the nucleus. [ABSTRACT FROM AUTHOR]

Abstract. A new method for the isolation of total RNA from plant tissues is described. This method is designed to circumvent problems resulting from endogenous materials that typically gel during isolation when previously published methods are used. This method is suitable for the isolation of total RNA from plant tissues that contain large amounts of oligosaccharide compounds, and has been used to produce high-quality total RNA from the inner epidermal tissue of onion bulb scale. Using 10 grams of epidermis, it is possible to isolate 0.6 mg of total RNA. This RNA can be directly used in mRNA purification, in vitro translation, and reverse transcription-polymerase chain reaction (RT-PCR). The procedure is simple and takes less than one day. [ABSTRACT FROM AUTHOR]

The article presents legal developments in marking relating to the regulation of product characteristics. Regarding packaging and labeling, the case Federal Trade Commission v. Bonnie & Co. Fashions, Inc. is discussed, in which the textiles Care Labeling Rule of the United States Federal Trade Commission (FTC) was upheld. Regarding credit terms and conditions of sale, a case involving an extension of the FTC's Consumer Mail Order Protection to telephone sales is discussed, in which mail order merchandise trade regulation rules were extended to cover purchases made over the telephone.

The article presents information on legal developments in marketing relative to the regulation of product characteristics. In regard to credit terms and conditions of sale, the article discusses Great Clips, Inc. v. Robert Levine, et al., where the court decided that the requirement by a franchisor to charge one even-dollar price for a haircut was not a restraint of trade. The article explains that Great Clips, in an effort to abandon a discounter image and establish clear prices, required franchisees to charge one-even dollar price for all haircuts, while still allowing individual franchisees to offer specials and odd-dollar prices for discounts.

The article presents information on legal developments in marketing relative to the regulation of product characteristics. In regard to credit terms and conditions of sale, the article discusses Mr. Furniture Warehouse, Inc., et al. v. Barclay's American Commercial, Inc., et al.. The Court of Appeals for the Eleventh Circuit found that a company denied credit where no other credit sources are available has not suffered an antitrust injury under Sections 1 and 2 of the Sherman Act. The article discusses the details and implications of the decision.

The article presents information on legal developments in marketing relative to the regulation of product characteristics. In regard to product quality and safety standards, the article notes the U.S. Federal Trade Commission's requirement of The Perrier Group of America, Inc. to cease and desist misrepresentation of its product. The article explains the promotional language and the issues taken with the misrepresentation. In terms of credit terms and conditions of sale, the article addresses Swensen's Ice Cream Co. v. Corsair Corp., et al. where Swensen pursued action against franchisees who had begun to operate independently and were using names other than the franchisor. The article discusses the details of the action and the implications for marketers.

The article presents information on legal developments in marketing relative to the regulation of product characteristics. The article discusses U.S. Federal Trade Commission (FTC) action in regard to The Vons Companies and implications in their product literature that their product is "free" of harmful pesticides when they were not. The company agreed to comply with the order and will not misrepresent the presence of pesticides in its products and will make no representation concerning health effects without legitimate scientific evidence.

This is the first report on the organization of a quadripolar microtubule system (QMS) in polyplastidic meiosis of a hepatic with polar organizers (POs). Unlike the monoplastidic sporocytes of mosses and hornworts, in which meiotic quadripolarity can be traced to plastid division and migration, sporocytes of Aneura pinguis are polyplastidic and tetrahedrally lobed before the QMS is organized. Whereas the QMS in mosses and hornworts is plastid-based, the QMS of A. pinguis is focused at four POs where gamma tubulin (gamma-tubulin) is concentrated. An aster of microtubules emanates from each PO centered in the four cytoplasmic lobes and the opposing radial microtubules interact to form the QMS that envelops the nucleus. A functionally bipolar spindle is gradually formed as the four poles converge in pairs on either side of opposite cleavage furrows. The resulting spindle remains quadripolar. Although gamma-tubulin is most concentrated in the deeply concave poles straddling cleavage furrows, it also extends into the spindle itself. Telophase groups of chromosomes curve around the polar cleavage furrows and a phragmoplast that originates in the interzonal region guides a cell plate that extends to the equatorial cleavage furrows. Discrete POs are reformed at opposite tips of the elongated dyad nuclei in prophase II and microtubules radiating from them give rise to the spindles of second meiosis. Spindles remain sharply focused and gamma-tubulin extends into distal portions of the spindle. Interzonal phragmoplasts that expand to join with pre-established cleavage furrows mediate cytokinesis resulting in a tetrad of spores. Each young tetrad member has a radial microtubule system emanating from the nucleus.