The defective seed5 (des5) mutant: effects on barley seed development and HvDek1, HvCr4, and HvSal1 gene regulation.

Barley, one of the major small grain crops, is especially important in climatically demanding agricultural areas of the world, with multiple uses within food, feed, and beverage. The barley endosperm is further of special scientific interest due to its three aleurone cell layers, with the potential of bringing forward the molecular understanding of seed development and cell specification from Arabidopsis and maize. Work done in Arabidopsis and maize indicate the presence of conserved seed developmental pathways where Crinkly4 (Cr4), Defective kernel1 (Dek1), and Supernumerary aleurone layer1 (Sal1) are key players. With the use of microscopy, a comprehensive phenotypic characterization of the barley defective seed5 (des5) mutant is presented here. The analysis further extends to molecular quantification of gene expression changes in the des5 mutant by qRT-PCR. Moreover, full-length genomic sequences of the barley orthologues were generated and these were annotated as HvDek1, HvCr4, and HvSal1. The most striking results in this study are the patchy reduction in number of aleurone cells, rudimentary anticlinal aleurone cell walls, and the specific change of HvCr4 expression compared to HvDek1 and HvSal1. The data presented support the involvement of Hvdes5 in establishing aleurone cells. Finally, how these results might affect the current model of aleurone and epidermal cell identity and development is discussed with a speculation regarding a possible role of Des5 in regulating cell division/ secondary cell wall building.

Pattern of cell death after in vitro exposure to GDMA, TEGDMA, HEMA and two compomer extracts.

OBJECTIVES: In vitro exposure to chemical compounds in dental materials may cause cell death by apoptosis, necrosis or a combination of both. The aim of this paper was to evaluate aqueous extracts of freshly cured compomers Freedom (SDI) and F2000 (3M ESPE), and constituents identified in the extracts, GDMA (glycerol dimethacrylate), TEGDMA (triethylene glycol dimethacrylate) and HEMA (2-hydroxyethyl methacrylate) for their ability to induce necrosis and apoptosis in primary rat alveolar macrophages and the J744A1 macrophage cell line. METHODS: The cells were exposed to either extracts of freshly cured samples of the products or to one of the constituents identified in the extracts. Cytotoxicity and necrosis were assayed by MTT test and fluorescence microscopy, respectively. Apoptosis was assayed by fluorescence microscopy and flow cytometry. RESULTS: Concentration-related apoptosis and necrosis were found in both cell types after exposure to extracts from Freedom and F2000. GDMA appeared to be the most cytotoxic of the tested constituents in the J744A1 cell line as evaluated by the MTT test. TEGDMA was more cytotoxic than HEMA using the MTT test and fluorescence microscopy, whereas HEMA caused a greater accumulation of apoptotic cells seen by fluorescence microscopy and flow cytometry. For various concentrations of HEMA and TEGDMA, the extent of apoptosis appeared inversely related to the cytotoxicity evaluated by the MTT test. SIGNIFICANCE: As an apoptotic response elicits less inflammatory response in the surrounding tissues than a necrotic process, the role of cell death pattern could be important for the evaluation of the biocompatibility of dental materials.

Irritation and cytotoxic potential of denture adhesives.

OBJECTIVE: The present study aimed to examine the in vitro biocompatibility of denture adhesives. BACKGROUND: Denture adhesives absorb water to become viscous and sticky, and by this process, other constituents like colouring, flavouring, wetting and preserving agents may be released. Some of these constituents may induce adverse reactions among users of denture adhesives. MATERIALS AND METHODS: Five commercially available denture adhesives; three different creams, a powder, and a cushion were included in the study. The irritation and cytotoxic potential was evaluated using the Hen's Egg Test Chorioallantoic Membrane (HET-CAM) method and three cell culture methods; filter diffusion, dimethylthiazol diphenyltetrazolium bromide (MTT) assay and agar diffusion. RESULTS: None of the tested denture adhesives showed a noteworthy acute irritation as evaluated by the HET-CAM method. None of the tested denture adhesives induced cytotoxicity in the filter diffusion test. One of the denture adhesives induced a severe cytotoxic reaction in both the MTT and agar diffusion assays. These tests employ longer exposure times than in both the filter diffusion and the HET-CAM test. CONCLUSION: Denture adhesives are commonly used throughout the day, and our results raise the concern that denture adhesives may contribute to mucosal inflammation in denture wearers.

The maize disorganized aleurone layer 1 and 2 ( dil1, dil2) mutants lack control of the mitotic division plane in the aleurone layer of developing endosperm.

The maize ( Zea mays L.) endosperm consists of an epidermal like layer of isodiametric aleurone cells surrounding a central body of starchy endosperm cells. In disorgal1 ( dil1) and disorgal2 ( dil2) mutants the control of the mitotic division plane is relaxed or missing, resulting in mature grains with disorganized aleurone layers. In addition to orientation of the division plane, both the shape and size of the aleurone cells are affected, and often more than one layer of aleurone cells is present. Homozygous dil1 and dil2 grains are shrunken due to reduced accumulation of starchy endosperm and premature developmental arrest of the embryo, and mature mutant grains germinate at a very low rate and fail to develop into plants. However, homozygous mutant plants can be obtained through embryo rescue, revealing that both mutants have an irregular leaf epidermis as well as roots with a strongly reduced number of root hairs and aberrant root hair morphology. Our results suggest the presence of common regulatory mechanisms for the control of cell division orientation in the aleurone and plant epidermis.