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The detailed studies of the mechanism by which resistance mutations decrease sensitivity to enfuvirtide (ENF), the first human immunodeficiency virus type 1 (HIV 1) fusion inhibitor peptides and alter six-helix bundle structure are reported. The data obtained for a framework to understand the impact of resistance mutations on viral fitness and pathogenesis and provide a pathway for the development of new fusion inhibitor peptides.

The zinc finger proteins Mig1 and Mig2 play important roles in glucose repression of Saccharomyces cerevisiae. To investigate whether the alleviation of glucose effect would result in an increase in aerobic succinate production, MIG1 and/or MIG2 were disrupted in a succinate dehydrogenase (SDH)-negative S. cerevisiae strain. Moreover, their impacts on physiology of the SDH-negative S. cerevisiae strain were studied under fully aerobic conditions when glucose was the sole carbon source. Our results showed that the succinate production for the SDH-negative S. cerevisiae was very low even under fully aerobic conditions. Furthermore, deletion of MIG1 and/or MIG2 did not result in an increase in succinate production in the SDH-negative S. cerevisiae strain. However, the synthesis of acetate was significantly affected by MIG1 deletion or in combination with MIG2 deletion. The acetate production for the mig1/ mig2 double mutant BS2M was reduced by 69.72% compared to the parent strain B2S. In addition, the amount of ethanol produced by BS2M was slightly decreased. With the mig2 mutant BSM2, the concentrations of pyruvate and glycerol were increased by 26.23% and 15.28%, respectively, compared to the parent strain B2S. [ABSTRACT FROM AUTHOR]

Oligochitosan is a potent plant defense elicitor. In this paper, a novel Brassica napus mitogen-activated protein kinase (MAPK) gene induced by oligochitosan was isolated by rapid amplification of cDNA ends technique and designated as BnOIPK (oligochitosan-induced protein kinase (OIPK)). BnOIPK, with high sequence similarity to previously reported plant MAPK genes, encodes a 373-amino acid protein and belongs to the B subgroup of plant MAPK. Bioinformatics analysis showed BnOIPK contains one phosphorylation motif (TEY) and a conserved common docking domain in its C-terminal extension. With a constitutive expression in seedling leaves, BnOIPK is further upregulated upon treatment with plant hormone jasmonic acid (JA), but did not markedly respond to salicylic acid and abscisic acid. Activation of BnOIPK transcripts induced by oligochitosan depending on nitric oxide (NO) and hydrogen peroxide (H2O2) was identified by using NO, H2O2, and their scavenger, respectively. Polyclonal antibody BOK was prepared by using a 69-kD GST-BnOIPK fusion protein which was produced from pGEX-4T-1 vector. Western-blot assays showed BnOIPK could be induced by oligochitosan and JA at a short time. All these results suggest that BnOIPK might be a key node of JA-mediated defense signaling and act on the downstream of NO and H2O2. [ABSTRACT FROM AUTHOR]

Abstract  Four oligosaccharides (penta-, hexa-, hepta- and octa-saccharide) derived from Paris polyphylla var. yunnanensis have been synthesized efficiently using a convergent glycosylation strategy. The tobacco (Nicotiana tabacum L.) growth bioactivities of the synthesized oligosaccharides were examined, using tissue-cultured seedlings grown on solid MS medium. After 2 or 3 weeks, all four oligosaccharides had stimulated tobacco seedling growth at 1.0 ppm and the pentasaccharide showed the most significant stimulus effects. Further experiments showed that the effects of pentasaccharide on tobacco growth had an obvious concentration-dependent relationship in the range of 0.1–1.0 ppm. This stimulus effect showed some decrease when the pentasaccharide concentration was higher than 1.0 ppm. At 1.0 ppm, pentasaccharide had the most significant effects, which caused a 520% fresh weight increase of tobacco. The bioactivity of these synthesized oligosaccharides suggested that they may be good prospects for the application in the control of plant growth and development. [ABSTRACT FROM AUTHOR]

Abstract??Oligochitosan has a variety of biological activities. To understand its mechanism, DDRT-PCR, reverse Northern blot and quantitative relative RT-PCR were used to identify and isolate genes whose transcription were altered in culturedNicotiana tabacum(var. Samsun NN) plants that were treated with oligochitosan. Three genes whose mRNA levels significantly changed in response to oligochitosan were isolated and identified. One gene is up-regulated, and two genes are down-regulated. These genes encode a DNAJ heat shock N-terminal domain-containing protein, a histone H1 gene and a hypothetical protein, whose function is unknown. The results suggest that the usefulness of mRNA differential display technique for the detection of plant metabolic pathways affected by oligochitosan. [ABSTRACT FROM AUTHOR]