Three new α-pyrone derivatives from the plant endophytic fungus Penicillium ochrochloronthe and their antibacterial, antifungal, and cytotoxic activities.

Three new 3,4,6-trisubstituted α-pyrone derivatives, namely 6-(2'R-hydroxy-3'E,5'E-diene-1'-heptyl)-4-hydroxy-3-methyl-2H-pyran-2-one (1), 6-(2'S-hydroxy-5'E-ene-1'-heptyl)-4-hydroxy-3-methyl-2H-pyran-2-one (2), and 6-(2'S-hydroxy-1'-heptyl)-4 -hydroxy-3-methyl-2H-pyran-2-one (3), together with one known compound trichodermic acid (4), were isolated from the solid-substrate fermentation culture of Penicillium ochrochloronthe associated the roots of Taxus media. Compounds 1-4 displayed the antimicrobial activity selectively against tested fungal and bacterial strains with minimum inhibitory concentration (MIC) values ranging from 12.5 to 100 µg/ml. Furthermore, we found that only compound 4 exhibited moderate cytotoxicity against five human cancer cells (A549, LN229, MGC, LOVO, and MDA231) with IC50 values of 51.45, 23.43, 39.16, 46.97, and 42.85 µg/ml, respectively.

Warming neutralizes host-specific competitive advantages between a native and invasive herbivore.

Although native-invasive species interactions have become a common mechanism shaping ecosystems, whether these interactions shift under warming remains unclear. To investigate how warming may affect native and invasive species separately and together (intraspecific and interspecific competition, respectively) and whether any warming impact is resource dependent, we examined the performance of two competing herbivores (native Pieris canidia and invasive P. rapae) on two common host plants under three temperature settings (control, 3 °C, and 6 °C warming using environmental chambers). The results revealed that warming benefited the development and growth of both Pieris under intraspecific competition, but the benefits were host-plant dependent. Notably, the native or invasive Pieris gained an advantage from interspecific competition (host-plant dependent), but warming neutralized the competitive advantages of either Pieris species. These findings raise the possibility that warming-induced shifts in competitive status may become a crucial mechanism shaping ecosystems worldwide, because most ecosystems are challenged by species invasion and warming. Moreover, this study revealed a discrepancy in species thermal performance between intra- and interspecific competition. Therefore, to predict native-invasive species competition under warming, current thermal performance applications should use species performance curves derived from interspecific rather than intraspecific competition studies (although the latter is more readily available).

[An efficient approach to the synthesis of a high-quality random peptide repertoire].

During the construction of a random peptide repertoire using degenerate models, unexpected amino acids or stop codons are almost unavoidable. To conquer this shortcoming, a new split-mix-split method of oligonucleotide synthesis was developed. A 13-amino acids random peptide library had been constructed by using this method. The sequencing results of 16 clones indicated that neither stop codon nor codon for cysteine appeared as designed. The occurrence rations of 19 amino acids were also calculated and no obvious amino acid bias had been observed. By using this method, the type and quantity of amino acid at certain position of a peptide could be controlled well, so this split-mix-split method, combined with degenerate could meet the needs of a high diversity random peptide library.