Impact of precursors and plant growth regulators on <Emphasis Type="Italic">in vitro</Emphasis> growth,bioactive lignans,and antioxidant content of <Emphasis Type="Italic">Phyllanthus</Emphasis> species

The production of specific secondary metabolites in vitro can be improved through medium supplementation with secondary metabolite precursors, plant growth regulators (PGRs), and abiotic and biotic elicitors. In the present study, node and internode explants of Phyllanthus amarus and P. urinaria collected from Karkala region, Udupi District, Karnataka, India, were inoculated aseptically onto Murashige and Skoog (MS) medium for callus induction. Uniform calluses were inoculated onto MS medium fortified with one of two precursor’s cinnamic acid (CA) or phenylalanine (PA), or with naphthalene acetic acid (NAA). After 30 d of treatment, calluses from treatment and control groups were harvested and quantitatively analyzed for three lignans (phyllanthin, hypophyllanthin and niranthin) and an antioxidant (ellagic acid). Increased amounts of the lignans and ellagic acid were obtained through supplementation with CA, PA, and NAA, and higher ellagic acid was present at higher amounts than the three lignans. These results demonstrated that the Phyllanthus species collected from Karkala region (designated “Accessions3”) show substantial response to CA, PA, and NAA treatment and represent a potential source of donor plants with higher amounts of lignans and antioxidants. These plants can be cultivated on a large scale both in vitro and in vivo for production of important bioactive compounds. Production of these compounds can be further enhanced through induction of somaclonal variant plants with higher amounts of bioactive molecule production and through production of transgenic plants overexpressing genes related to lignan- and phenolic-compound biosynthesis.     

Local and systemic alterations in cyclic 3′,5′ AMP phosphodiesterase activity in relation to tail regeneration under hypothyroidism and T4 replacement in the lizard,Mabuya carinata

To establish the relationship between thyroid hormone and cyclic Adenosine monophosphate (cAMP) during lacertilian tail regeneration, cAMP phosphodiesterase, the hydrolytic enzyme of cAMP, was assayed in the tail regenerate, liver, and skeletal muscle of control (group A), chemically thyroidectomized (group B), and thyroidectomized and T₄-replaced (group C) animals during various periods of tail regeneration. Enzyme activity was elevated in all three tissues of group B animals. Animals of group C showed an intermediate level of enzyme activity between controls (group A) and experimental animals (group B). These observations suggest a possible regulatory role of thyroxine in maintaining optimum levels of phosphodiesterase. The retardation in regeneration observable in the hypothyroid group of animals may be correlated with low levels of tissue cAMP. However, the operation of other influencing factors on phosphodiesterase during regeneration can be surmised from the observed tendency to exhibit similar patterns of phase-specific modulations in enzyme activity. Our observations are discussed in terms of phase-specific involvement of cAMP in regeneration, as well as its role in other metabolic aspects and the possible mode of indirect control exerted by thyroxine on lacertilian tail regeneration. © 1996 Wiley-Liss, Inc.     

Modified miniprep method for the rapid recovery of episomes from transfected breast epithelial cells

Episomal vectors such as pCEP4 are useful in expression cloning because they can replicate in both prokaryotes and eukaryotic cells. We have found a rapid and efficient means of extracting them from transfected MCF-10A nonmalignant human breast epithelial cells. We show that a plasmid miniprep protocol, modified by the addition of an extraction that eliminates a DNase activity, can consistently harvest pCEP4 episomes from the transfected cells (516 +/- 112 pg/harvest, mean +/- standard deviation; n = 11). The quality of the episomal DNA obtained in this manner was verified by PCR, Southern blot and the retransformation of Escherichia coli. This simple method enables the efficient recovery of episomes and is applicable in the expression cloning of potential oncogenes using host MCF-10A cells.     

Synthesis, X-ray crystal structure, antimicrobial activity and photodynamic effects of some thiabendazole complexes

An interesting series of metal complexes of thiabendazole (tbz) is synthesized and characterized by elemental analyses and spectroscopic studies. The crystal structure of the hydrogen bonded one dimensional Co(II) complex, namely [Co(tbz)(2)(NO(3))(H(2)O)](NO(3)) is solved by single crystal X-ray diffraction. The complex crystallizes in monoclinic space group P2(1)/a with unit cell parameters, a=14.366(2), b=11.459(4), c=15.942(3) A, beta=113.78(3) degrees and z=4. The unit cell packing reveals an extensive hydrogen bonding involving a water molecule, nitrate ligands and the protonated nitrogen atoms of the tbz ligands, resulting in a one dimensional hydrogen bonding pattern. The antimicrobial activity of the complexes against selected bacteria (Escherichia coli and Bacillus subtilis) and yeast (Aspergillus flavues) is estimated. The relationship between the enzymatic production of ROS and antimicrobial activity of the complexes is examined, and a good correlation between two factors is found. Photodynamic quantum yields of singlet oxygen production (RNO bleaching assay) and rate of superoxide generation (SOD inhibitable ferricytochrome c reduction assay and EPR spin trapping experiments using 5,5-dimethyl-1-pyrroline-N-oxide as spin trap) by the metal complexes have been studied.     

The development of potent non-peptidic PTP-1B inhibitors

The SAR from our peptide libraries was exploited to design a series of potent deoxybenzoin PTP-1B inhibitors. The introduction of an ortho bromo substituent next to the difluoromethylphosphonate warhead gave up to 20-fold increase in potency compared to the desbromo analogues. In addition, these compounds were orally bioavailable and active in the animal models of non-insulin dependent diabetes mellitus (NIDDM).     

Autonomic responses of autistic children to people and objects

Several recent lines of inquiry have pointed to the amygdala as a potential lesion site in autism. Because one function of the amygdala may be to produce autonomic arousal at the sight of a significant face, we compared the responses of autistic children to their mothers' face and to a plain paper cup. Unlike normals, the autistic children as a whole did not show a larger response to the person than to the cup. We also monitored sympathetic activity in autistic children as they engaged in a wide range of everyday behaviours. The children tended to use self-stimulation activities in order to calm hyper-responsive activity of the sympathetic ('fight or flight') branch of the autonomic nervous system. A small percentage of our autistic subjects had hyporesponsive sympathetic activity, with essentially no electrodermal responses except to self-injurious behaviour. We sketch a hypothesis about autism according to which autistic children use overt behaviour in order to control a malfunctioning autonomic nervous system and suggest that they have learned to avoid using certain processing areas in the temporal lobes.     

ADF proteins are involved in the control of flowering and regulate F-actin organization, cell expansion, and organ growth in Arabidopsis

Based mostly on the results of in vitro experiments, ADF (actin-depolymerizing factor) proteins are thought to be key modulators of the dynamic organization of the actin cytoskeleton. The few studies concerned with the in vivo function of ADF proteins that have been reported to date were performed almost exclusively using single-cell systems and have failed to produce consistent results. To investigate ADF functions in vivo and during the development of multicellular organs, we generated transgenic Arabidopsis plants that express a cDNA encoding an ADF protein (AtADF1) in the sense or the antisense orientation under the control of a strong constitutively active promoter. Selected lines with significantly altered levels of AtADF protein expression were characterized phenotypically. Overexpression of AtADF1 resulted in the disappearance of thick actin cables in different cell types, caused irregular cellular and tissue morphogenesis, and reduced the growth of cells and organs. In contrast, reduced AtADF expression promoted the formation of actin cables, resulted in a delay in flowering, and stimulated cell expansion as well as organ growth. These results are consistent with the molecular functions of ADF as predicted by in vitro studies, support the global roles of ADF proteins during the development of a multicellular organism, and demonstrate that these proteins are key regulators of F-actin organization, flowering, and cell and organ expansion in Arabidopsis.