Search

Redox tailoring enzymes play key roles in generating structural complexity and diversity in type II polyketides. In chartreusin biosynthesis, the early 13 C-labeling experiments and bioinformatic analysis suggest the unusual aglycone is originated from a tetracyclic anthracyclic polyketide. Here, we demonstrated that the carbon skeleton rearrangement from a linear anthracyclic polyketide to an angular pentacyclic biosynthetic intermediate requires two redox enzymes. The flavin-dependent monooxygenase ChaZ catalyses a Baeyer-Villiger oxidation on resomycin C to form a seven-membered lactone. Subsequently, a ketoreductase ChaE rearranges the carbon skeleton and affords the α-pyrone containing pentacyclic intermediate in an NADPH-dependent manner via tandem reactions including the reduction of the lactone carbonyl group, Aldol-type reaction, followed by a spontaneous γ-lactone ring formation, oxidation and aromatization. Our work reveals an unprecedented function of a ketoreductase that contributes to generate structural complexity of aromatic polyketide.

As classical MRPs, the toxic effects of furosine, pyralline, and 5‐hydroxymethylfurfural (5‐HMF) in liver tissue are evaluated and the related mechanism is investigated here, and the protective effects of lactoferrin on liver injury caused by Maillard reaction products (MRPs) with furan ring are proved in vitro and in vivo. First, we detect the concentrations of furosine, pyralline, and 5‐HMF in several foods using ultrahigh‐performance liquid chromatography (UHPLC). Then, the effects of the three MRPs on liver cells (HL‐7702) viability, as well as liver tissue, are performed and evaluated. Furthermore, the regulations of three MRPs on necroptosis‐related pathway in liver cells are investigated. Additionally, the effects of lactoferrin in alleviating liver injury, as well as regulating necroptosis pathway, were evaluated. Results elucidate that lactoferrin protects liver injury caused by MRPs with furan ring structure through activating RIPK1/RIPK3/p‐MLKL necroptosis pathway and downstream inflammatory reaction., Lactoferrin protects liver injury caused by MRPs with furan ring structure through activating RIPK1/RIPK3/p‐MLKL necroptosis pathway and downstream inflammatory reaction.

Heterostructure engineering of electrode materials, which is expected to accelerate the ion/electron transport rates driven by a built-in internal electric field at the heterointerface, offers unprecedented promise in improving their cycling stability and rate performance. Herein, carbon nanotubes with Co9 S8 /ZnS heterostructures embedded in a N-doped carbon framework (Co9 S8 /ZnS@NC) have been rationally designed via an in-situ vapor chemical transformation strategy with the aid of thiophene, which not only acted as carbon source for the growth of carbon nanotubes but also as sulfur source for the sulfurization of metal Zn and Co. Density functional theory (DFT) calculation shows an about 3.24 eV electrostatic potential difference between ZnS and Co9 S8 , which results in a strong electrostatic field across the interface that makes electrons transfer from Co9 S8 to the ZnS side. As expected, a stable cycling performance with reversible capacity of 411.2 mAh g-1 at 1000 mA g-1 after 300 cycles, excellent rate capability (324 mAh g-1 at 2000 A g-1 ) and a high percentage of pseudocapacitance contribution (87.5% at 2.2 mv/s) for lithium-ion batteries (LIBs) are achieved. This work provides a possible strategy for designing multicomponent heterostructural materials for application in energy storage and conversion fields.

Petrocodon vietnamensis, a new species from karst cave in north Vietnam is described and illustrated. It is morphologically close to P. bonii, but can be distinguished from the latter by having a green, 3–6 cm long peduncle; green, ca 5 mm long calyx lobes; narrow infundibuliform, a 1.1–1.2 cm long corolla tube; ovate abaxial lip lobes; pink to white, 9.5–10.5 mm long filaments; lateral staminodes adnate to ca 12 mm above the corolla base; densely white glandular‐puberulent pistil; a pink to white, 5.5–7.5 mm long style; a white stigma, and a 2–3 cm long capsule. Information on ecology, phenology, preliminary conservation assessment of the new species and a key for the taxonomic identification of Petrocodon species in Vietnam are also provided.

OBJECTIVE To compare the psychometric properties of different short versions of the Geriatric Depression Scale (GDS) among community-dwelling widowed older people. METHODS A cross-sectional design was conducted between February 2018 and August 2019 in southern Taiwan (n = 330). The GDS short versions included Hoyl et al's 5-item version, Molloy et al's 5-item version and van Marwijk et al's 4-item version. RESULTS All GDS short versions had satisfactory internal consistency (α = 0.83-0.90), with strong item loading embedded in the same construct of depression (0.43-0.72). The activity of daily living (ADL) scores had strong associations with van Marwijk et al's 4-item version (absolute standardised coefficient [|β|] = 0.15-0.59), Hoyl et al's 5-item version (|β| = 0.16-0.45) and Molloy et al's 4-item version (|β| = 0.09-0.40). CONCLUSIONS Hoyl et al's 5-item version was found to be more suitable than the other two versions of the GDS to assess the precise construct of depression. Meanwhile, van Marwijk et al's 4-item version can be used when the focus is on ADL performance. However, the conclusion should be interpreted with caution since the results were derived only from a widowed population in Taiwan. More research on this topic among other populations is thus needed to corroborate our conclusion.

Subterranean predatory mites are important biological control agents of pests in soil. In order to understand the population characteristics of two predatory mites, Macrocheles glaber Muller and Stratiolaelaps scimitus Womersley, we studied their development, survival and fecundity data under laboratory conditions using Coboldia fuscipes Meigen as a food source and analyzed them with the age-stage, two-sex life table. Macrocheles glaber had a significantly shorter developmental time, oviposition period, longevity and lower fecundity than those of S. scimitus. The intrinsic rate of increase (r), finite rate of increase (λ), net reproductive rate (R0 ), net predation rate (C0 ), and finite predation rate (ω) of M. glaber were significantly lower than those of S. scimitus. Both population parameters and computer simulation implied that S. scimitus is a potential powerful biocontrol agent compared to M. glaber.

Limestone karsts across southern China to southeastern Asia are renowned biodiversity hotspots. The karst are characterized by exposed calcareous rocks, seasonal droughts and thin soils that are deficient in N and P but with high Ca and Mg content. The stressful habitat may result in high biodiversity through mechanisms such as niche differentiation, hybridization, polyploidy and apomixis. The genus Elatostema (Urticaceae) has particularily high species diversity in this area and can be used a model genus to explore the mechanisms of speciation. We conducted cytological studies on 11 species of Elatostema from 12 populations in Guangxi, China. We found five populations to be diploid (2n = 26), and seven triploid populations (2n = 39). We infer x = 13 as the basic chromosome number of Elatostema. The chromosome numbers 2n = 26 and 2n = 39 were both found in populations of E. longistipulum, indicating that this species comprise both diploids and triploids. Both male and female plants of Elatostema were found to be diploid. In contrast, the triploids found were all female plants, and these produce seeds, presumably by apomixis. We found no clear relationship between ploidy level or reproductive pathway and endemism in Elatostema which might be because Elatostema species are wind-pollinated and independent of biotic pollinators. However, a random sample of 11 karst species revealed that ca 2/3 appeared to be apomictic, suggesting that it is a widespread reproductive strategy of Elatostema in the limestone karsts of Guangxi. Apomixis enables plants to reproduce and disperse from a single individual, allowing ‘hopeful monsters’ adapted to a new habitat to form stable populations.

Primulina maciejewskii F. Wen, R.L. Zhang & A.Q. Dong, a new species of Primulina (Gesneriaceae) from Guangdong, China, is described and illustrated. It is similar to P. lobulata and P. danxiaensis in leaf and flower shape, but can be distinguished by bract shape, peduncle, pedicel, and bract size, filament and anther indumentum, and number of bracts, staminodes and stigma.

A new species of Gesneriaceae, Primulina melanofilamenta Ying Liu & F. Wen from Guangxi, China, is illustrated and described. It is morphologically distinct from the most similar species P. eburnea and P. atroglandulosa by the color of the corolla, dark purplish black filaments, anthers backed with a beard of white hairs, the length of staminodes and the hairs of styles. The somatic chromosome number of P. melanofilamenta is also reported as 2n = 36.

A new species of Primulina, P. moi, from Guangdong, China, is described and illustrated. It is similar to P. lijiangensis in leaf shape, but can be distinguished by several characters, such as base of corolla tube constricted, lobes of adaxial lip ovate, abaxial lip 3-lobed from base, lobes elliptic or oblong elliptic with cuspidate apex, yellow corolla and filaments, two non-adhesive anthers when corolla is open, adnate only before anthesis and 2 stamnoides.