Characterization of the Arabidopsis TU8 Glucosinolate Mutation,an Allele of TERMINAL FLOWER2

Glucosinolates are a group of defense-related secondary metabolites found in Arabidopsis and other cruciferous plants. Levels of leaf glucosinolates are regulated during plant development and increase in response to mechanical damage or insect feeding. The Arabidopsis TU8 mutant has a developmentally altered leaf glucosinolate profile: aliphatic glucosinolate levels drop off more rapidly, consistent with the early senescence of the mutant, and the levels of two indole glucosinolates are uniformly low. In TU8 seeds, four long-chain aliphatic glucosinolates have significantly increased levels, whereas the indolyl-3-methyl glucosinolate level is significantly reduced relative to wild type. Genetic mapping and DNA sequencing identified the TU8 mutation as tfl2-6, a new allele of TERMINAL FLOWER2 (TFL2), the only Arabidopsis homolog of animal HETEROCHROMATIN PROTEIN1 (HP1). TU8 (tfl2-6) has other previously identified tfl2 phenotypes, including an early transition to flowering, altered meristem structure, and stunted leaves. Analysis of two additional alleles, tfl2-1 and tfl2-2, showed glucosinolate profiles similar to those of line TU8 (tfl2-6).     

Biotechnology and the popular press: hype and the selling of science

The popular media has emerged as an important source of scientific information. It has been suggested that the portrayal of genetics by the media is often inaccurate--a phenomenon branded 'genohype'--and, as a result, is having an adverse impact on public understanding and policy development. However, emerging data suggest that, in some circumstances, the media reporting of science is surprisingly accurate and portrays a message created by the scientific community. As such, there are reasons to believe that the hyping of research results might be part of a more systemic problem associated with the increasingly commercial nature of the research environment.     

Factors influencing the ability to detect motion reversals in rotation simulations

Five experiments probed the conditions under which observers fail to report instantaneous reversals in the direction of motion of pixels that define the rotation of a transparent sphere or plane. Our results showed that the extent to which rotation reversals were not reported depended upon whether observers used strict or lax criteria to make their judgments, the degree of perspective present in the rotation simulations, and the percentage of pixels that actually reversed direction. Furthermore, we found failures to report rotation reversals both with stimuli whose pixels were confined to smooth surfaces and scattered within volumes. Reversal detection with planar stimuli, unlike sphere stimuli, depended upon the orientation of the stimulus at the moment of reversal. Treue et al. (1995) postulated a surface-interpolation process as the explanation for the apparent insensitivity of observers to such reversals. However, we suggest that other stages of processing (e.g. a structure-from-motion process) are required to account for these results.     

Active involvement of PKC for insulin-mediated rates of muscle protein synthesis in Zucker rats

A recent report from our group demonstrated that insulin facilitates muscle protein synthesis in obese Zucker rats. The purpose of this study was to determine whether PKC, a probable modulator of insulin signal transduction and/or mRNA translation, has a role in this insulin-mediated anabolic response. In the first portion of the study, gastrocnemius muscles of lean and obese Zucker rats (n = 5-7 for each phenotype) were bilaterally perfused with or without insulin to assess cytosolic and membrane PKC activity. Limbs perfused with insulin demonstrated greater PKC activity in both lean and obese Zucker rats (P < 0.05) compared with no insulin, but overall activity was greater in obese animals (by approximately 27% compared with lean, P < 0.05). To determine whether PKC plays a role in muscle protein synthesis, hindlimbs (n = 6-8 for each phenotype) were bilaterally perfused with or without insulin and/or GF-109203X (GF; a PKC inhibitor). The presence of GF did not influence the rates of insulin-mediated protein synthesis in gastrocnemius muscle of lean Zucker rats. However, when obese rats were perfused with GF (P < 0.05), the effect of insulin on elevating rates of protein synthesis was not observed. We also used phorbol 12-myristate 13-acetate (TPA, a PKC activator; n = 5-7 for each phenotype) with and without insulin to determine the effect of PKC activation on muscle protein synthesis. TPA alone did not elevate muscle protein synthesis in lean or obese rats. However, TPA plus insulin resulted in elevated rates of protein synthesis in both phenotypes that were similar to rates of insulin alone of obese rats. These results suggest that PKC is a modulator and is necessary, but not sufficient, for insulin-mediated protein anabolic responses in skeletal muscle.     

Hyperbaric and normobaric reoxygenation of hypoxic rat brain slices--impact on purine nucleotides and cell viability

Hyperbaric oxygen treatment has been suggested as able to reduce hypoxia induced neuronal damage. The aim of the study was to compare the impact of different reoxygenation strategies on early metabolical (purine nucleotide content determined by HPLC) and morphological changes (index of cell injury after celestine blue/acid fuchsin staining) of hypoxically damaged rat neocortical brain slices. For this purpose slices (300 μm and 900 μm) were subjected to either 5 or 30 min of hypoxia by gassing the incubation medium with nitrogen. During the following reoxygenation period treatment groups were administered either 100% oxygen (O) or room air (A) at normobaric (1 atm absolute, NB-O; NB-A) or hyperbaric (2.5 atm absolute, HB-O; HB-A) conditions. After 5 min of hypoxia, both HB-O and NB-O led to a complete nucleotide status restoration (ATP/ADP; GTP/GDP) in 300 μm slices. However, reoxygenation after 30 min of hypoxia was less effective, irrespective of the oxygen pressure. Furthermore, administering hyperbaric room air resulted in no significant posthypoxic nucleotide recovery. In 900 μm slices, both control incubation as well as 30 min of hypoxia resulted in significantly lower trinucleotide and higher dinucleotide levels compared to 300 μm slices. While there was no significant difference between HB-O and NB-O on the nucleotide status, morphological evaluation revealed a better recovery of the index of cell injury (profoundly injured/intact cell-ratio) in the HB-O group. Conclusively, the posthypoxic recovery of metabolical characteristics was dependent on the duration of hypoxia and slice thickness, but not on the reoxygenation pressure. A clear restorative effect on purine nucleotides was found only in early-administered HB-O as well as NB-O in contrast to room air treated slices. However, these pressure independent metabolic changes were morphologically accompanied by a significantly improved index of cell injury, indicating a possible neuroprotective role of HB-O in early posthypoxic reoxygenation.     

Developing chick embryos express a protein which shares homology with the nuclear pore complex protein Nup88 present in human tumors

Nup88 is a nuclear pore complex protein which is overexpressed in a variety of human tumors of the stomach, colon, liver, pancreas, breast, lung, ovary, uterus, prostate and kidney. A monoclonal antibody crossreacting with the yeast Candida albicans and Nup88 was used to investigate the expression of cross-reactive antigens in chick embryos, in an attempt to identify an experimental model for studying the role played by Nup88 during cell development and differentiation. All cells in the trilaminar embryo were labeled with the antibody, but as development advanced and organogenesis was completed, expression of the corresponding antigen became more restricted. Thus, some structures continued to be intensely labeled (skin epithelium, oropharyngeal endothelium, perichondral mesenchymal tissue), whereas others ( muscular tissue, vascular endothelium, respiratory endothelium, digestive tract mucosa, peripheral nerves, medullary white matter and the retinal axons) were more moderately stained. No immunoreactivity was observed in the medullary grey matter or cartilage. A specific band of 53 kDa observed by Western blotting of chick embryo extracts suggested that the chicken antigen recognized by the monoclonal antibody is the homologue of human Nup88, which is associated with the high proliferation and low differentiation of tumor cells. The present results indicate that the role of Nup88 in cell differentiation and organ development could be fruitfully investigated using the developing chick embryo as an experimental model.     

Novel non-peptidic neuropeptide Y Y2 receptor antagonists

Through SAR studies of a piperidinylindoline cinnamide HTS lead, the first potent, non-peptide, low molecular weight selective Neuropeptide Y Y2 (NPY Y2) antagonists have been synthesized. The SAR studies around the piperidinyl, the indolinyl, and the cinnamyl moieties are discussed.     

A novel series of 2-pyridyl-containing compounds as lysophosphatidic acid receptor antagonists: development of a nonhydrolyzable LPA3 receptor-selective antagonist

A recently reported dual LPA(1)/LPA(3) receptor antagonist (1) has been modified so as to modulate the basicity, sterics, and dipole moment of the 2-pyridyl moiety. Additionally, the implications of installing nonhydrolyzable phosphate head group isosteres with regard to antagonist potency and selectivity at LPA receptors is described. This study has resulted in the development of the first nonhydrolyzable and presumably phosphatase-resistant LPA(3)-selective antagonist reported to date.     

A new class of potent non-imidazole H(3) antagonists: 2-aminoethylbenzofurans

2-aminoethylbenzofurans constitute a new class of H(3) antagonists that are more rotationally constrained than most previously reported H(3) antagonists. They retain high potency at human and rat receptors, with efficient CNS penetration observed in 35. The SAR of the basic amine moiety was compared in three different series of analogues. The greatest potency was found in analogues bearing a 2-methylpyrrolidine, a 2,5-dimethylpyrrolidine, or a 2,6-dimethylpiperidine.     

New fatty acid oxidation inhibitors with increased potency lacking adverse metabolic and electrophysiological properties

New inhibitors of palmitoylCoA oxidation were synthesized based on a structurally novel lead, CVT-3501 (1). Investigation of structure-activity relationships was conducted with respect to potency of inhibition of cardiac mitochondrial palmitoylCoA oxidation and metabolic stability. Potent and metabolically stable analogues 33, 42, and 43 were evaluated in vitro for cytochrome P450 inhibition and potentially adverse electrophysiological effects. Compound 33 was also found to have favorable pharmacokinetic properties in rat.