Distribution and dynamic changes of Huanglongbing pathogen in its insect vector Diaphorina citri.

The Asian citrus psyllid (ACP) Diaphorina citri Kuwayama is the leading vector of Candidatus Liberibacter asiaticus (CLas), the causative agent of citrus Huanglongbing (HLB) disease. The distribution and dynamics of CLas within ACP are critical to understanding how the transmission, spread and infection of CLas occurs within its host vector in nature. In this study, the distribution and titer changes of CLas in various tissues of ACP 5th instar nymphs and adults were examined by fluorescence in situ hybridization (FISH) and real-time quantitative PCR (qPCR) techniques. Results demonstrated that 100% of ACP 5th instar nymphs and adults were infected with CLas following feeding on infected plants, and that CLas had widespread distribution in most of the tissues of ACP. The titers of CLas within the midgut, salivary glands and hemolymph tissues were the highest in both 5th instar nymphs and adults. When compared with adults, the titers of CLas in these three tissues of 5th instar nymphs were significantly higher, while in the mycetome, ovary and testes they were significantly lower than those of adults. FISH visualization further confirmed these findings. Dynamic analysis of CLas demonstrated that it was present across all the developmental ages of ACP adults. There was a discernible upward trend in the presence of CLas with advancing age in most tissues of ACP adults, including the midgut, hemolymph, salivary glands, foot, head, cuticula and muscle. Our findings have significant implications for the comprehensive understanding of the transmission, dissemination and infestation of CLas, which is of much importance for developing novel strategies to halt the spread of CLas, and therefore contribute to the efficient prevention and control of HLB.

A new anti-inflammatory thujane monoterpenoid glycoside ester from Pittosporum heterophyllum Franch.

Phytochemical investigation of EtOH extract of Pittosporum heterophyllum led to one new esterified thujane monoterpenoid glycoside, pitheteroside A (1), together with one eudesmane sesquiterpenoid (2) and twelve lignans (3－14). Their structures were elucidated by extensive spectroscopic analysis, including 1D and 2D NMR, ECD calculation and HRESIMS spectra. Pitheteroside A is an unreported and highly esterified monoterpenoid glycoside. All isolates were evaluated for their nitric oxide production inhibition against LPS-induced BV-2 microglial cells. Among them, compounds 1, 6 and 8 showed significant activities with IC50 values less than 10 µM. The results indicated the metabolisms from P. heterophyllum possess potential anti-inflammatory effects.

ATP dynamic regeneration strategy for enhancing co-production of glutathione and S-adenosylmethionine in Escherichia coli.

OBJECTIVES: In general, a sufficient supply of ATP can promote the synthesis of ATP-driven metabolites, but excessive ATP will lead to the inhibition of cell growth. For enhancing the co-production of glutathione(GSH) and S-adenosylmethionine(SAM), a dynamic ATP regeneration strategy was developed. RESULTS: The novel ATP regeneration strategy consisting of ATP-sensing riboswitch ydaO motif, polyphosphate kinase (PPK), and Vitreoscilla hemoglobin (VHb) was successfully applied in Escherichia coli. The intracellular ATP level was always around 0.60 mg/g dry cell weight during the fermentation process, resulting in significantly enhanced co-production of GSH and SAM. The GSH titer and SAM titer in the strain CGS-2 increased by 137.40% and 82.18% after fermentation for 24 h, compared with the control strain. CONCLUSIONS: The ATP regulation strategy is expected to be a favorable tool to improve the efficiency of microbial cell factories. The proposed ATP dynamic regeneration approach may be applicable for cost-effective, high-yield production of ATP-driven metabolites.