Synthesis and DNA interaction of a Sm(III) complex of a Schiff base derived from vanillin and L-tryptophan

The interaction between the Sm(III) complex of an ionic Schiff base [HL]-, derived from vanillin and L-tryptophan, and herring sperm DNA at physiological pH (7.40) has been studied by UV-Vis absorption, fluorescence and viscosity methods. The binding ratios nSm(III) : nK[HL] = 1:1 and nSm(III)L: nDNA = 5:1 were confirmed by a mole ratio method. The calculated binding constants of [Sm(III)L]+ with DNA at 25 and 37 oC were 1.19 × 105 M-1 and 3.96 × 104 M-1, respectively. The thermodynamic parameters demonstrate that the interaction between [Sm(III)L]+ and DNA is driven mainly by enthalpy. Fluorimetric studies show that [Sm(III)L]+ is able to displace intercalated acridine orange. Combined with Scatchard methods, circular dichroism spectroscopy and viscosity measurements, the results indicate that the interaction between [Sm(III)L]+ and herring sperm DNA is mainly by intercalation with some groove binding.KEY WORDS: Vanillin, L-Tryptophan, Sm(III) complex of Schiff base, Herring sperm DNA, Interaction Bull. Chem. Soc. Ethiop. 2011, 25(2), 197-207

Major Miocene geological events in southern Tibet and eastern Asia induced by the subduction of the Ninetyeast Ridge

Cenozoic adakitic rocks in the Gangdese changed from barren continental melts to ore-forming slab melts at ~ 23 Ma. The distribution and chemical characteristics of the ore-forming adakites point to an association with the Ninetyeast Ridge. The subduction of the thick, rigid Ninetyeast Ridge changed the geometry and rheology of the eastern Tibetan Plateau lithosphere and asthenosphere, restrained the eastward escape of asthenospheric mantle as well as continental fragments, and promoted the uplift and building of the Tibetan Plateau, which consequently changed the tectonic and climatic regimes in eastern Asia.This study was supported by NSFC 91328204 to W.D.S. and Strategic Priority Research Program (B) of the Chinese Academy of Sciences (XDB18020102) to W.D.S. and X.L.S

Bid activates multiple mitochondrial apoptotic mechanisms in primary hepatocytes after death receptor engagement

: Activation of Fas or tumor necrosis factor receptor 1 (TNF-R1) on hepatocytes leads to apoptosis, which requires mitochondria activation. The pro-death Bcl-2 family protein, Bid, mediates this pathway by inducing mitochondrial releases of cytochrome c and other apoptotic factors. How Bid activates mitochondria has been studied in vitro with isolated mitochondria. We intended to study the mechanisms in intact hepatocytes so that findings could be made in a proper cellular context and would be more physiologically relevant. : Hepatocytes were isolated from wild-type and bid-deficient mice and treated with anti-Fas or TNF-α. Mechanisms of mitochondria activation were dissected with genetic, biochemical, and morphologic approaches. :bid-deficient hepatocytes were much more resistant to apoptosis. Bid was required for permeability transition and mitochondria depolarization in addition to the previously defined release of cytochrome c. Permeability transition inhibitors cyclosporin A and aristolochic acid could inhibit mitochondria activation effectively, but not as much as the deletion of the bid gene, and they could not inhibit Bak oligomerization. In addition, mitochondria depolarization also could be induced by caspases, whose activation was mainly dependent on Bid. : Bid may activate mitochondria by 2 mechanisms, one is related to permeability transition and the other is related to Bak oligomerization. Bid can further affect mitochondria potentials by indirectly regulating caspase activity. This in vivo study provides novel findings not previously disclosed by in vitro studies, and indicates the importance of several mechanisms in contributing Bid-mediated mitochondria dysfunction that could be potential cellular targets of intervention

Effects of Electroacupuncture of Different Frequencies on the Release Profile of Endogenous Opioid Peptides in the Central Nerve System of Goats

To investigate the release profile of met-enkephalin, β-endorphin, and dynorphin-A in ruminants’ CNS, goats were stimulated by electroacupuncture of 0, 2, 40, 60, 80, or 100 Hz for 30 min. The pain threshold was measured using potassium iontophoresis. The peptide levels were determined with SABC immunohistochemisty. The results showed that 60 Hz increased pain threshold by 91%; its increasing rate was higher (P<0.01) than any other frequency did. 2 Hz and 100 Hz increased met-enkephalin immunoactivities (P<0.05) in nucleus accumbens, septal area, caudate nucleus, amygdala, paraventricular nucleus of hypothalamus, periaqueductal gray, dorsal raphe nucleus, and locus ceruleus. The two frequencies elicited β-endorphin release (P<0.05) in nucleus accumbens, septal area, supraoptic nucleus, ventromedial nucleus of hypothalamus, periaqueductal gray, dorsal raphe nucleus, locus ceruleus, solitary nucleus and amygdala. 60 Hz increased (P<0.05) met-enkephalin or β-endorphin immunoactivities in the nuclei and areas mentioned above, and habenular nucleus, substantia nigra, parabrachial nucleus, and nucleus raphe magnus. High frequencies increased dynorphin-A release (P<0.05) in spinal cord dorsal horn and most analgesia-related nuclei. It suggested that 60 Hz induced the simultaneous release of the three peptides in extensive analgesia-related nuclei and areas of the CNS, which may be contributive to optimal analgesic effects and species variation