Conservation genetics of rare trees restricted to subtropical montane cloud forests in southern China: a case study from <Emphasis Type="Italic">Quercus arbutifolia</Emphasis> (Fagaceae)

Montane cloud forests (MCFs), with their isolated nature, offer excellent opportunities to study the long-term effects of habitat fragmentation and the impacts of climate change. Quercus arbutifolia is a rare oak in MCFs of southern China and Vietnam. Its isolated populations, small population size and unique ecological niche make this species vulnerable to climate change and habitat loss. In this study, we used chloroplast (cpDNA) and nuclear (ITS) DNA sequences to investigate genetic divergence patterns and demographic history of five of the six known populations of Q. arbutifolia. Considering its small population size and fragmentation, Q. arbutifolia has unexpectedly high genetic diversity. The time since the most recent common ancestor of all cpDNA haplotypes was c. 10.25 Ma, and the rapid diversification of haplotypes occurred during the Quaternary. The maximum clade credibility chronogram of cpDNA haplotypes suggests that the DM population (Daming Mountain, Guangxi province) diverged early and rapidly became isolated from other populations. The Pearl River drainage system may have been the main geographic barrier between DM and other populations since the late Miocene. ITS data suggests that population expansion occurred during the last interglacial of the Quaternary. The combined effects of pre-Quaternary and Quaternary climatic and geological changes were the main drivers to the current genetic diversity and distribution pattern of Q. arbutifolia. Because of the high between-population genetic differentiation and high within-population genetic diversity of Q. arbutifolia, conservation efforts should be implemented for all populations, but if conservation resources are limited, populations DM, YZ (Mang Mountain, Hunan province) and ZZ (Daqin Mountain, Fujian province) should have priority.     

Possible target‐related proteins and signal network of bufalin in A549 cells suggested by both iTRAQ‐based and label‐free proteomic analysis

Bufalin (BF) exhibited antiproliferation and antimigration effects on human A549 lung cancer cells. To search its target‐related proteins, protein expression profiles of BF‐treated and control cells were compared using two quantitative proteomic methods, iTRAQ‐based and label‐free proteomic analysis. A total of 5428 proteins were identified in iTRAQ‐based analysis while 6632 proteins were identified in label‐free analysis. The number of common identified proteins of both methods was 4799 proteins. By application of 1.20‐fold for upregulated and 0.83‐fold for downregulated cutoff values, 273 and 802 differentially expressed proteins were found in iTRAQ‐based and label‐free analysis, respectively. The number of common differentially expressed proteins of both methods was 45 proteins. Results of bioinformational analysis using Metacore^TM showed that the two proteomic methods were complementary and both suggested the involvement of oxidative stress and regulation of gene expression in the effects of BF, and fibronectin‐related pathway was suggested to be an important pathway affected by BF. Western blotting assay results confirmed BF‐induced change in levels of fibronectin and other related proteins. Overexpression of fibronectin by plasmid transfection ameliorated antimigration effects of BF. Results of the present study provided information about possible target‐related proteins and signal network of BF.     

Improved extracellular expression and high-cell-density fed-batch fermentation of chitosanase from <Emphasis Type="Italic">Aspergillus Fumigatus</Emphasis> in <Emphasis Type="Italic">Escherichia coli</Emphasis>

Chitosanase (CSN) from Aspergillus fumigatus has good thermal stability, wide pH range duration, and effective hydrolysis for chitosan. Inhere, CSN was successfully expressed in Escherichia coli followed by extracellular secretion under the guidance of an N-terminal signal peptide PelB, which effectively prompted its secretion out of E. coli cells. To facilitate its later purification, N-terminal or C-terminal 6xHis epitope tag was added to the PelB-CSN protein complex. Our results indicated that PelB-CSN without 6xHis-tag (PelB-CSN) or with N-terminal 6xHis-tag (PelB-CSN-N) can both be effectively secreted into the medium, while CSN with 6xHis-tag anchored at C-terminus was expressed as inclusion bodies. Process optimization strategies were further developed to improve the secretion efficiency of recombinant PelB-CSN-N in E. coli. Under the induction of 10 g/L lactose in shake-flask culture, the extracellular activity of CSN reached 6015 U/mL at 25 °C in TB medium containing 1 % glycine. Moreover, a fed-batch fermentation strategy for high-cell-density cultivation was applied in a 5-L fermenter, increasing the extracellular CSN activity to 14,000 U/mL in 2-day fermentation with the optimal addition of lactose and glycine.     

Optimal harvesting strategies for timber and non-timber forest products in tropical ecosystems

Harvesting wild plants for non-timber forest products (NTFPs) can be ecologically sustainable–without long-term consequences to the dynamics of targeted and associated species–but it may not be economically satisfying because it fails to provide enough revenues for local people over time. In several cases, the same species can be harvested for NTFP and also logged for timber. Three decades of studies on the sustainability of NTFP harvest for local people’s livelihood have failed to successfully integrate these socio-economic and ecological factors. We apply optimal control theory to investigate optimal strategies for the combinations of non-lethal (e.g., NTFP) and lethal (e.g., timber) harvest that minimize the cost of harvesting while maximizing the benefits (revenue) that accrue to harvesters and the conservation value of harvested ecosystems. Optimal harvesting strategies include starting with non-lethal NTFP harvest and postponing lethal timber harvesting to begin after a few years. We clearly demonstrate that slow growth species have lower optimal harvesting rates, objective functional values and profits than fast growth species. However, contrary to expectation, the effect of species lifespan on optimal harvesting rates was weak suggesting that life history is a better indicator of species resilience to harvest than lifespan. Overall, lethal or nonlethal harvest rates must be <40 % to ensure optimality. This optimal rate is lower than commonly reported sustainable harvest rates for non-timber forest products.