Chlorogenic acid (CGA) decreases colon cancer-cell proliferation but the combined anti-cancer effects of CGA with its major colonic microbial metabolites, caffeic acid (CA), 3-phenylpropionic acid (3-PPA) and benzoic acid (BA), needs elucidation as they occur together in colonic digesta. Caco-2 cancer cells were treated for 24 h with the four compounds individually (50–1000 µM) and as an equimolar ratio (1:1:1:1; MIX). The effective concentration to decrease cell proliferation by 50% (EC₅₀) was lower for MIX (431 ± 51.84 µM) and CA (460 ± 21.88) versus CGA (758 ± 19.09 µM). The EC₅₀ for cytotoxicity measured by lactate dehydrogenase release in MIX (527 ± 75.34 µM) showed more potency than CA (740 ± 38.68 µM). Cell proliferation was decreased by 3-PPA and BA at 1000 µM with no cytotoxicity. Cell-cycle arrest was induced at the S-phase by CA (100 µM), MIX (100 µM), CGA (250 µM) and 3-PPA (500 µM) with activation of caspase-3 by CGA, CA, MIX (500 and 1000 µM). Mitochondrial DNA content was reduced by 3-PPA (1000 µM). The anti-cancer effects occurred at markedly lower concentrations of each compound within MIX than when provided singly, indicating that they function together to enhance anti-colon cancer activities.

C+G content (GC content or G+C content) is known to be correlated with genome/chromosome size in bacteria but the relationship for other kingdoms remains unclear. This study analyzed genome size, chromosome size, and base composition in most of the available sequenced genomes in various kingdoms. Genome size tends to increase during evolution in plants and animals, and the same is likely true for bacteria. The genomic C+G contents were found to vary greatly in microorganisms but were quite similar within each animal or plant subkingdom. In animals and plants, the C+G contents are ranked as follows: monocot plants>mammals>non-mammalian animals>dicot plants. The variation in C+G content between chromosomes within species is greater in animals than in plants. The correlation between average chromosome C+G content and chromosome length was found to be positive in Proteobacteria, Actinobacteria (but not in other analyzed bacterial phyla), Ascomycota fungi, and likely also in some plants; negative in some animals, insignificant in two protist phyla, and likely very weak in Archaea. Clearly, correlations between C+G content and chromosome size can be positive, negative, or not significant depending on the kingdoms/groups or species. Different phyla or species exhibit different patterns of correlation between chromosome-size and C+G content. Most chromosomes within a species have a similar pattern of variation in C+G content but outliers are common. The data presented in this study suggest that the C+G content is under genetic control by both trans- and cis- factors and that the correlation between C+G content and chromosome length can be positive, negative, or not significant in different phyla.

Solanum is one of the largest genera, including two important crops—potato (Solanum tuberosum) and tomato (Solanum lycopersicum). In this study we compared the chloroplast codon usage bias (CUB) among 12 Solanum species, between photosynthesis-related genes (Photo-genes) and genetic system-related genes (Genet-genes), and between cultivated species and wild relatives. The Photo-genes encode proteins for photosystems, the photosynthetic electron transport chain, and RuBisCO, while the Genet-genes encode proteins for ribosomal subunits, RNA polymerases, and maturases. The following findings about the Solanum chloroplast genome CUB were obtained: (1) the nucleotide composition, gene expression, and selective pressure are identified as the main factors affecting chloroplast CUB; (2) all these 12 chloroplast genomes prefer A/U over G/C and pyrimidines over purines at the third-base of codons; (3) Photo-genes have higher codon adaptation indexes than Genet-genes, indicative of a higher gene expression level and a stronger adaptation of Photo-genes; (4) gene function is the primary factor affecting CUB of Photo-genes but not Genet-genes; (5) Photo-genes prefer pyrimidine over purine, whereas Genet-genes favor purine over pyrimidine, at the third position of codons; (6) Photo-genes are mainly affected by the selective pressure, whereas Genet-genes are under the underlying mutational bias; (7) S. tuberosum is more similar with Solanum commersonii than with Solanum bulbocastanum; (8) S. lycopersicum is greatly different from the analyzed seven wild relatives; (9) the CUB in codons for valine, aspartic acid, and threonine are the same between the two crop species, S. tuberosum and S. lycopersicum. These findings suggest that the chloroplast CUB contributed to the differential requirement of gene expression activity and function between Photo-genes and Genet-genes and to the performance of cultivated potato and tomato.

Climate warming is subjecting plants to heat stress, which can affect their physiological processes thereby impacting their growth, development, and productivity. Potato (Solanum tuberosum L.) is a staple food worldwide, but potato crops are very sensitive to heat stress. We have studied the effects of heat stress on the leaf chlorophyll content, plant growth, and tuber yield of 55 commercial potato cultivars in clonal tests under heat-stress conditions [HS; 35 °C (day), 28 °C (night)] and control (non-stress) conditions [CK; 22 °C (day), 18 °C (night)]. The potato cultivars varied in their response to heat stress. Overall, heat stress reduced leaf size, increased the SPAD index values for leaf chlorophyll by up to 65%, and increased plant height by 64%, but severely reduced (by 93%) the mass of the largest tuber. The HS:CK SPAD ratios positively correlated with the HS:CK plant height ratio, mass of the largest tuber under heat stress, and the HS:CK ratio for mass of the largest tuber. Potato cultivars displayed a correlated response to heat stress for their leaf chlorophyll content, plant height, and tuber mass. We have identified the most heat-tolerant and heat-susceptible cultivars for these traits. Under heat-stress conditions, potato cultivars tend not to show as much reduction in tuber mass if the plants have greater increases in leaf chlorophyll content and plant height.

Development of sweet potato (Ipomoea batatas) storage root coincides with starch accumulation made using cleaved products of imported photoassimilate sucrose. The genes and pathways are predominantly active for sucrose metabolism in developing storage root were unknown. In this study, we used both an expressed sequence tag (EST) approach and a reverse transcription–polymerase chain reaction (RT-PCR) approach to answer this question. Sucrose synthase (SuSy) was found to be significantly more frequent in storage root ESTs than in fibrous root ESTs. SuSy was the most abundant carbohydrate-metabolism gene in the storage-root ESTs. RT-PCR results confirmed this by showing that invertase was active in fibrous roots but rapidly decreased to an undetectable level during storage root development while SuSy became predominant. Invertase expression was also detectable in young immature storage root and shoot tips, suggesting an involvement in cell formation. SuSy expression pattern showed considerable similarity to that of ADP-glucose pyrophosphorylase, an essential enzyme for starch synthesis. The results indicated that (i) SuSy was the most actively expressed enzyme in sucrose metabolism in developing storage root and was correlated with sink strength, and (ii) whereas invertase was active at cell formation stages, SuSy pathway was predominant for sucrose cleavage related to starch-accumulation.