Poly(dG)-poly(dC) DNA appears shorter than poly(dA)-poly(dT) and possibly adopts an A-related conformation on a mica surface under ambient conditions

Three types of DNA: approximately 2700 bp polydeoxyguanylic olydeoxycytidylic acid [poly(dG)-poly(dC)], approximately 2700 bp polydeoxyadenylic polydeoxythymidylic acid [poly(dA)-poly(dT)] and 2686 bp linear plasmid pUC19 were deposited on a mica surface and imaged by atomic force microscopy. Contour length measurements show that the average length of poly(dG)-poly(dC) is approximately 30% shorter than that of poly(dA)-poly(dT) and the plasmid. This led us to suggest that individual poly(dG)-poly(dC) molecules are immobilized on mica under ambient conditions in a form which is likely related to the A-form of DNA in contrast to poly(dA)-poly(dT) and random sequence DNA which are immobilized in a form that is related to the DNA B-form.     

PPARgamma activation primes human monocytes into alternative M2 macrophages with anti-inflammatory properties

Th1 cytokines promote monocyte differentiation into proatherogenic M1 macrophages, while Th2 cytokines lead to an "alternative" anti-inflammatory M2 macrophage phenotype. Here we show that in human atherosclerotic lesions, the expression of M2 markers and PPARgamma, a nuclear receptor controlling macrophage inflammation, correlate positively. Moreover, PPARgamma activation primes primary human monocytes into M2 differentiation, resulting in a more pronounced anti-inflammatory activity in M1 macrophages. However, PPARgamma activation does not influence M2 marker expression in resting or M1 macrophages, nor does PPARgamma agonist treatment influence the expression of M2 markers in atherosclerotic lesions, indicating that only native monocytes can be primed by PPARgamma activation to an enhanced M2 phenotype. Furthermore, PPARgamma activation significantly increases expression of the M2 marker MR in circulating peripheral blood mononuclear cells. These data demonstrate that PPARgamma activation skews human monocytes toward an anti-inflammatory M2 phenotype.     

Regulation of MicroRNA Machinery and Development by Interspecies S-Nitrosylation

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Morphological Characteristics and Gene Mapping of Purple Apiculus Formation in Rice

Plant Molecular Biology Reporter - Apiculus color of grain is an important trait which is used as a morphological marker in rice (Oryza sativa. L). In the present study, the purple apiculus mutant...     

Taxonomic Significance of Sclerenchyma Distribution in the Secondary Phloem of Some Indian Tropical Trees

Analysis of the relative amount and distribution pattern of phloem sclerenchyma in some 29 tropical trees of India was carried out with systematic considerations. Both the features exhibited considerable diversity among the species analyzed. The extent of area occupied by sclerenchyma in transections of the bark of these species varied from zero to 35% and 3 to 49% in the conducting and non-conducting phloem zones respectively, the overall amount constituting about 3 to 45% of the secondary phloem as a whole. The sclerenchyma cells differentiated either as isolated elements or in the form of bands or fascicles of diverse shape and size showing various distribution patterns.     

Effect of steroids and the estrous cycle on uterine neuromedin U receptor expression

We investigated the role of estrogen and progesterone on rat uterine NmU receptor expression in both intact and ovariectomized animals and examined receptor expression through the estrous cycle. Chronic administration of beta-estradiol 3-benzoate (E2) or progesterone in intact animals was devoid of any effect. RU486 caused a 2-fold up-regulation in NmU receptor density. Ovariectomy caused a 60% decrease in receptor density, but chronic E2 administration to ovariectomized rats significantly increased NmU receptor density. The estrous cycle had no significant effect on NmU receptor density. These results suggest that NmU receptor expression is estrogen-dependent, whereas progesterone or a progestin-induced factor is involved in the modulation of this expression.     

Biosynthesis of very-long-chain polyunsaturated fatty acids in transgenic oilseeds: constraints on their accumulation

Omega6- and omega3-polyunsaturated C20 fatty acids represent important components of the human diet. A more regular consumption and an accordingly sustainable source of these compounds are highly desirable. In contrast with the very high levels to which industrial fatty acids have to be enriched in plant oils for competitive use as chemical feedstocks, much lower percentages of very-long-chain polyunsaturated fatty acids (VLCPUFA) in edible plant oils would satisfy nutritional requirements. Seed-specific expression in transgenic tobacco (Nicotiana tabacum) and linseed (Linum usitatissimum) of cDNAs encoding fatty acyl-desaturases and elongases, absent from all agronomically important plants, resulted in the very high accumulation of Delta6-desaturated C18 fatty acids and up to 5% of C20 polyunsaturated fatty acids, including arachidonic and eicosapentaenoic acid. Detailed lipid analyses of developing seeds from transgenic plants were interpretated as indicating that, after desaturation on phosphatidylcholine, Delta6-desaturated products are immediately channeled to the triacylglycerols and effectively bypass the acyl-CoA pool. Thus, the lack of available Delta6-desaturated acyl-CoA substrates in the acyl-CoA pool limits the synthesis of elongated C20 fatty acids and disrupts the alternating sequence of lipid-linked desaturations and acyl-CoA dependent elongations. As well as the successful production of VLCPUFA in transgenic oilseeds and the identification of constraints on their accumulation, our results indicate alternative strategies to circumvent this bottleneck.     

Poloxamer 407-induced atherosclerosis in mice appears to be due to lipid derangements and not due to its direct effects on endothelial cells and macrophages

Coronary heart disease secondary to atherosclerosis is still the leading cause of death in the US. Animal models used for elucidating the pathogenesis of this disease primarily involve rabbits and pigs. Previous studies from this laboratory have demonstrated intraperitoneal injections of poloxamer 407 (P-407) in both male and female mice will lead to hyperlipidemia and atherosclerosis, suggesting the use of this polymer to develop a mouse model of atherosclerosis. In order to understand the mechanism of P-407-induced hyperlipidemia and vascular lesion formation, we evaluated the direct effects of P-407 on endothelial cell and macrophage functions in vitro, and its in vivo effects on the oxidation of circulating lipids following long-term (4 month) administration. Our results demonstrated that incubation of P-407 with human umbilical vein endothelial cells in culture did not influence either cell proliferation or interleukin-6 and interleukin-8 production over a concentration range of 0-40 microM. In addition, nitric oxide production by macrophages was not affected by P-407 over a concentration range of 0-20 microM. Finally, we demonstrated that while P-407 could not induce the oxidation of LDL-C in vitro, long-term (4 month) administration of P-407 in mice resulted in elevated levels of oxidized lipids in the plasma. Thus, it is suggested that the formation of atherosclerotic lesions in this mouse model of atherosclerosis does not result from either direct stimulation of endothelial cells or macrophage activation by P-407. Instead, these data would support the premise that oxidation of lipids (perhaps low-density lipoprotein cholesterol) by an indirect mechanism following injection of P-407 may represent one of the mechanisms responsible for atheroma formation.