1,297 research outputs found
Transcriptional activity of male gamete-specific histone gcH3 promoter in sperm cells of Lilium longiflorum
No full textHistones are essential for packaging of eukaryotic genomic DNA in nucleosomes, and histone gene expression is normally coupled with DNA synthesis. Some of the flowering plant histone genes show strictly male gamete-specific expression. However, mechanisms underlying their male gamete-specific expression have not been elucidated so far. Here we report the isolation of the male gamete-specific histone gcH3 promoter from Lilium longiflorum and its activity in the male gametic cell of the flowering plant. The OCT motif, which is well conserved in plant histone promoters regulating S phase-specific expression, is not conserved in the gcH3 promoter. Instead sequence motifs identical to GC box 1 and GC box 2, the transcriptional activator and suppressor for mammalian testis-specific histone H1t, are present in the gcH3 promoter, suggesting that plants and animals share the mechanism which governs the specificity of gene expression in male gametic cells. Male gamete-specific activation of the gcH3 promoter has been confirmed by microprojectile bombardment in lily pollen. The sperm cell carrying gold particles showed reporter gene expression, while green fluorescent protein (GFP) was absent in the other sperm cell which had no particles, confirming that the gcH3 promoter is activated in the male gametic cell, and sperm cells have transcriptional and translational machinery that is independent of the vegetative cell of pollen.Takashi Okada, Prem L. Bhalla and Mohan B. Sing
Silver sheaves; gathered through clouds and sunshine. In two parts. Part 1st: Civil and military life of the author. Part 2d: Miscellaneous collection of prose and poetry.
No full text2d ed.2 p.l., [9]-360 p
Expressed sequence tag analysis of Lilium longiflorum generative cells
No full textThe generative cell, the male gametic cell progenitor in flowering plants, undergoes mitotic division to produce two sperm cells. We have examined the gene expression profile of the Lilium longiflorum (lily) generative cell by sequencing expressed sequence tags (ESTs). A total of 886 ESTs derived from the generative cell cDNA library were clustered into 637 unique ESTs comprising 123 cluster ESTs and 514 singleton ESTs. Thirty-nine percent of non-redundant ESTs showing similarity to Arabidopsis genes with known function were thus assigned putative functions. Genes related to the ubiquitin system were abundant, suggesting the key role of ubiquitin-dependent proteolysis in gametogenesis. A total of 168 and 129 non-redundant lily generative cell ESTs showed significant similarity to maize sperm cell ESTs and Arabidopsis male gametophyte-specific transcripts, respectively. Fifty-five ESTs appeared to have significant similarities to both maize sperm cell ESTs and Arabidopsis male gametophyte-specific genes, indicating conservation of male gamete-expressed genes across different plant genera. Thus our data provide a handle to identify Arabidopsis gamete-expressed genes and to investigate their function. Several of these genes are potential candidates for analyzing the molecular basis of fertilization and for investigating mechanisms of gamete-specific transcriptional regulation in Arabidopsis through bioinformatics-based approaches.Takashi Okada, Prem L. Bhalla and Mohan B. Sing
Steady-state kinetics of the tungsten containing aldehyde: Ferredoxin oxidoreductases from the hyperthermophilic archaeon Pyrococcus furiosus
No full textThe tungsten containing Aldehyde:ferredoxin oxidoreductases (AOR) offer interesting opportunities for biocatalytic approaches towards aldehyde oxidation and carboxylic acid reduction. The hyperthermophilic archaeon Pyrococcus furiosus encodes five different AOR family members: glyceraldehyde-3-phosphate oxidoreductase (GAPOR), aldehyde oxidoreductase (AOR), and formaldehyde oxidoreductase (FOR), WOR4 and WOR5. GAPOR functions as a glycolytic enzyme and is highly specific for the substrate glyceraldehyde-3-phosphate (GAP). AOR, FOR and WOR5 have a broad substrate spectrum, and for WOR4 no substrate has been identified to date. As ambiguous kinetic parameters have been reported for different AOR family enzymes the steady state kinetics under different physiologically relevant conditions was explored. The GAPOR substrate GAP was found to degrade at 60 °C by non-enzymatic elimination of the phosphate group to methylglyoxal with a half-life t1/2 = 6.5 min. Methylglyoxal is not a substrate or inhibitor of GAPOR. D-GAP was identified as the only substrate oxidized by GAPOR, and the kinetics of the enzyme was unaffected by the presence of L-GAP, which makes GAPOR the first enantioselective enzyme of the AOR family. The steady-state kinetics of GAPOR showed partial substrate inhibition, which assumes the GAP inhibited form of the enzyme retains some activity. This inhibition was found to be alleviated completely by a 1 M NaCl resulting in increased enzyme activity at high substrate concentrations. GAPOR activity was strongly pH dependent, with the optimum at pH 9. At pH 9, the substrate is a divalent anion and, therefore, positively charged amino acid residues are likely to be involved in the binding of the substrate. FOR exhibited a significant primary kinetic isotope effect of the apparent Vmax for the deuterated substrate, formaldehyde-d2, which shows that the rate-determining step involves a C[sbnd]H bond break from the aldehyde. The implications of these results for the reaction mechanism of tungsten-containing AORs, are discussed.Accepted Author ManuscriptBT/Biocatalysi
Legislative amendments, 1996
No full textAn annotated copy of Senate Bill No. 349: an Act concerning the regulation of hazardous substances, amending P.L.1983. c383, and amending and supplementing P.L.1983, c.315
The English hermit; or, Unparalleled sufferings and surprising adventures of Mr. Philip Quarll, who was lately discovered on an uninhabited island in the South sea; where he had lived about fifty years without any human assistance.
No full textAn issue of the 1727 edition in the British museum has the initials P.L. in the title and a dedication, in which the writer claims the authorship of the work, signed Peter Longueville. In the preface (signed P.L.) he denounces the bookseller for having substituted Edward Dorrington's name for his own. For a discussion of the authorship of A. Esdaile's "Author and publisher in 1727: The English hermit", in the Library, 4th ser., v. 2, p. 185-192. Ascribed by some authorities to Alexander Bicknell.Signed: Edward Dorrington.Running title: The English hermit.Mode of access: Internet
Historic old Rhinebeck, echoes of two centuries; a Hudson River and post road colonial town.
No full text[1st ed.]4 p.l., 448 p
- …
