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At least 289 records · Page 16Linked to original sources
PubMed2026

Genome-wide identification of HCT gene family in sugarcane (Saccharum spp. hybrid) and characterization of putative cis-elements in gene regulation.

BACKGROUND: Sugarcane (Saccharum spp. hybrid) is a globally important crop, and its bagasse can be converted into bioethanol and other industrial products. Lignin, a core component of sugarcane cell walls, plays a crucial role in bagasse quality and lodging resistance. Shikimic acid hydroxycinnamyl transferase (HCT) is the key enzyme in lignin biosynthesis. However, the HCT gene family in sugarcane and its regulatory roles in sugarcane remain poorly understood. RESULTS: A total of 663 HCT genes (including alleles) were identified in the Saccharum hybrid R570 genome, which were classified into six groups (I-VI) and were unevenly distributed across 77 chromosomes. Bioinformatics analysis revealed that the subgroups of R570HCTs had similar gene structures, suggesting conserved functions. Moreover, the different subgroups presented unique putative cis‑element distribution patterns. Transcriptome data indicated that some R570HCTs exhibited significant spatiotemporal and tissue‑specific expression patterns. Further Pearson correlation analysis between putative cis‑element distribution and normalized expression values at the subgroup level revealed that light-responsive elements (L‑box and GA‑motif) were positively correlated with R570HCT expression, and different subgroups formed a complex regulatory network by integrating hormone response and stress elements. Importantly, this subgroup-level correlation was cross-validated by comparing the cis‑element clustering heatmap with the expression heatmap, revealing consistent enrichment patterns. CONCLUSIONS: The study's findings provide novel insights into the correlation among motifs, putative cis‑elements, and gene expression, and propose a cross-validated framework for understanding regulatory divergence among HCT subfamilies in polyploid sugarcane, serving as a hypothesis generating resource for future research on R570HCT expression.

Saccharum↗
PubMed2004

Chemical composition and in vitro antimicrobial activities of the essential oils from endemic Psiadia species growing in mauritius.

The composition of the leaf oils, obtained by hydrodistillation, of five endemic Psiadia species of the Asteraceae family were studied by GC/MS on both polar and non-polar columns. The analysis showed that the volatile components of the oils were made up essentially of monoterpenes, sesquiterpenes, aliphatics and other shikimic acid derivatives. With respect to the non-volatile components, great variations were observed: P. lithospermifolia contained (E)-isoasarone (51.5%); P. penninervia: eugenol (5.1%); P. terebinthina: eugenyl-acetate (4.0%); P. viscosa: pentyl-4-(1-methylethyl benzoate) (25.8%); P. arguta: isoeugenol (56.5%). In vitro antimicrobial assays using the agar-well diffusion method, revealed that most of the oils were not very active against the tested microorganisms except for that of P. lithospermifolia, which significantly inhibited the growth of Bacillus cereus, Staphylococcus aureus and Pseudomonas aureofaciens, Aspergillus ochraceus, Candida pseudotropicalis, Kluyveromyces lactis and Fusarium moniliforme. This activity has been attributed to the presence of delta-elemene, (E)-farnesene, alpha-curcumene, selina-4,7(11)-diene, (E,Z)-alpha-farnesene, beta-bisabolene some of which have established antimicrobial profiles. Likewise, the fungi toxic action of the oil of P. arguta against Aspergillus ochraceus, Candida pseudotropicalis, and Fusarium moniliforme, may be attributed to the presence of isoeugenol, eugenol being known to be mycotoxic especially against Aspergillus species.

Anti-Bacterial Agents↗
PubMed2004

Synthesis of the epimer of pericosine B from (-)-quinic Acid.

Synthesis of the epimer of pericosine B from (-)-quinic acid was achieved. This synthesis involves some regioselective and stereoselective processes. The desired product showed lower cytotoxic activity in comparison with natural pericosine B against the P388 leukemia cell line. The result implies that the stereocenter of C-6 in natural pericosine B plays an important role in this activity.

Animals↗
PubMed2000

[Transketolase mutation in riboflavin-synthesizing strains of Bacillus subtilis].

Unlike its predecessors B. subtilis rosR and 41, riboflavin producing B. subtilis 24 strain does not utilize pentose and gluconate and poorly assimilates glucose. Simultaneous addition of glutamic and shikimic acid restored its capacity to grow and produce riboflavin in medium with pentose and gluconate. This strain lacks the activity of transketolase, the key enzyme of the pentose phosphate cycle, and possesses normal ribulose-5-phosphate-epimerase and glucose phosphate isomerase activities. Like enterobacteria, B. subtilis has two different transport systems for glucose and mannose. The data are discussed from the viewpoint of increasing riboflavin production by transketolase mutants. Probable consequences of cell wall and cytoplasmatic membrane damage in B. subtilis with this mutation are discussed.

Bacillus subtilis↗
PubMed1983

Co-accumulation of prephenate, L-arogenate, and spiro-arogenate in a mutant of Neurospora.

A mutant strain of Neurospora crassa blocked in each of the initial steps of tryptophan, tyrosine, and phenylalanine biosynthesis was previously shown to accumulate and secrete prephenate and L-arogenate (Jensen, R.A., Zamir, L.O., St. Pierre, M., Patel, N., and Pierson, D.L. (1977) J. Bacteriol. 132, 896-903). We now report the co-accumulation of yet another compound which was identified (Zamir, L.O., Tiberio, R., Jung, E., and Jensen, R.A. (1982) J. Biol. Chem. (1983) 258, 6486-6491) as the lactam derivative of L-arogenate. This structure, spiro-arogenate, undergoes a facile acid-catalyzed conversion to L-phenylalanine (as does L-arogenate). Since L-arogenate is conveniently quantitated as 5-dimethylaminonapthalene-1-sulfonyl (dansyl)-phenylalanine following acidification and dansylation, the unknown presence of spiro-arogenate may easily lead to overestimation of L-arogenate present in mixtures. Reliable quantitative assays for both L-arogenate and spiro-arogenate in mixtures were designed utilizing [3H]dansyl-chloride and exploiting the inability of the spiro-arogenate molecule to be dansylated in contrast to L-arogenate. The initial appearance of spiro-arogenate during accumulation lagged behind prephenate and L-arogenate, and spiro-arogenate accumulation leveled off after 5 days while prephenate and L-arogenate accumulations continued. It seems likely that spiro-arogenate is derived directly from L-arogenate. Prephenate, L-arogenate, and spiro-arogenate comprised about 70, 15, and 15% fractions of the total accumulation in a representative accumulation experiment designed to maximize spiro-arogenate yields. Modest variations in co-metabolite ratios were obtained under nutritional conditions where carbon source, growth temperature, duration of incubation time, and amino acid additions were experimental variables.

Amino Acids↗
PubMed1980

The functional unit of polyenzymes. Determination by radiation inactivation.

Recently, target analysis has been re-evaluated as a technique for the determination of molecular sizes (Kempner, E. S. & Schlegel, W. (1979) Anal. Biochem. 92, 2-10). The technique yields the size of the functional unit, i.e. the minimal assembly of structures necessary for a given function such as an enzymatic activity. Using this method, we have not determined the sizes of the functional units for different enzymatic activities on the "arom" conjugate from Euglena, a polyenzyme catalyzing five sequential reactions in the shikimic acid pathway, and on two conjugates from Escherichia coli carrying both aspartokinase and homoserine dehydrogenase activities. In each conjugate, the size for different enzymatic activities was measured and found to be the same. When compared to the molecular weight obtained with other techniques, the target size matched either the entire conjugate (aspartokinase-homoserine dehydrogenase conjugates I and II) or half the unit ("arom" conjugate). The information was obtained with minimal perturbation of the complexes and sparing laborious purification and reconstitution experiments. Tryptophan synthase was irradiated both as an intact conjugate and also as isolated subunits. In both structural forms, beta 2 was identified as the functional unit for the conversion of indole and serine to tryptophan. The results of this study give insight into the structural assembly of these polyenzymes.

Animals↗
PubMed1990

Shikimate kinase from spinach chloroplasts : purification, characterization, and regulatory function in aromatic amino Acid biosynthesis.

Shikimate kinase was purified to near homogenity from spinach Spinacia oleracea L. chloroplasts and found to consist of a single 31 kilodalton polypeptide. The purified enzyme was unstable, but could be stabilized by a variety of added proteins, including oxidized and reduced thioredoxins. Whereas the isolated enzyme was stimulated by mono- and dithiol reagents, the enzyme in intact chloroplasts was unaffected by added thiols and showed only minor response to dark/light transitions. These results indicate that the previously reported stimulation of shikimate kinase activity by reduced thioredoxins is due to enzyme stabilization rather than to activation. In the current study, the purified enzyme was inhibited by added ADP and showed a strong response to energy charge. When intact chloroplasts were incubated in the dark in presence of shikimate, phosphoenolpyruvate and a source of ATP (dihydroxyacetone phosphate or ATP itself under appropriate conditions), aromatic amino acids were formed: phenylalanine and tyrosine. The data indicate that energy charge plays a role in regulating shikimate kinase, thereby controlling the shikimate pathway. An unidentified enzyme of the latter part of the pathway, leading from shikimate-3-phosphate to phenylalanine, appears to be activated by light.

Journal Article↗
PubMed1998

The thiobarbituric acid (TBA) reaction in foods: a review.

The wide diffusion of 2-thiobarbituric acid (TBA) in the scientific literature is due to the TBA assay, or TBA test, which has been employed in the determination of autoxidative alterations of fats and oils. Two processes occur in autoxidation, generally: the free radical and the photo-oxidation mechanisms. The better studied is the free radical mechanism. The hydroperoxiepidioxides and bicycloendoperoxides are malonaldehyde (MDA) precursors. The absorption spectrum obtained with oxidized fatty foods is like the spectrum obtained when TBA and MDA react. However, during the secondary phase of the autoxidation process other aldehydes (alkanals, 2-alkenals, dienals) are formed which react with TBA, and they are responsible for off-flavors. Three kinds of pigments (yellow, orange, red adducts) are involved. Also, aromatic aldehydes, which constitute the flavor profile of diverse fruits and essential oils, form with TBA the characteristic arylidene-2-TBA acids. Other substances, such as ketones, ketosteroids, acids, esters, sugars, imides and amides, amino acids, oxidized proteins, pyridines, pyrimidines, and vitamins can react with TBA; they are named TBARS (substances that react with TBA), and form principally in meats and meat derivatives. Several organic or bio-organic acids, as shikimic and sorbic acids, react photometrically with TBA if a Malaprade reaction takes place before. A structural study of the red adduct TBA-MDA has been carried out.

Aldehydes↗