Correction to: Diversity and symbiotic divergence of endophytic and non-endophytic rhizobia of Medicago sativa

The authors wish to clarify that the right Fund No. of National Natural Science Foundation of China (NSFC) is 31560666. The Fund No. in the original article was wrong. The authors apologise for this error.     

Chemical composition and antidiabetic activity of Opuntia Milpa Alta extracts

Three new compounds, 1 – 3 , and 20 known compounds were isolated from the AcOEt and BuOH extract of edible Opuntia Milpa Alta. The petroleum ether extract was examined by GC and MS. A total of 26 compounds were identified, representing 95.6% of the total extract, phytosterol (36.03%) being the most abundant component, and polyunsaturated fatty acids (18.57%) represented the second largest group, followed by phytol (12.28%), palmitic acid, palmitate (13.54%), vitamin E (4.51%), and other compounds (7.47%). The effects of various extracts from edible Opuntia Milpa Alta (petroleum ether extract, AcOEt extract, BuOH extract, aqueous extract, H₂O parts) and the positive control (received dimethylbiguanide) were tested on streptozotocin (STZ)‐induced diabetic mice. The results indicated that all the treatment groups could significantly decrease blood glucose levels in STZ‐induced diabetic mice compared to the model control group (P<0.01), except the aqueous extract group (P<0.05). Especially, the petroleum ether extract group and the positive control group showed remarkable decrease of blood glucose levels. Taken together, the results indicate that the petroleum ether extract is the major hypoglycemic part in edible Opuntia Milpa Alta, which may be developed to a potential natural hypoglycemic functional ingredient.     

Glucose biosensor based on electrodeposited platinum nanoparticles and three-dimensional porous chitosan membranes

The chitosan with three-dimensional porous structure greatly increased the effective electrode surface for loading of platinum nanoparticles and promoted efficient electron transfer. The resulting biosensor had a response time (within 5 s) and a linear response from 6 μM to 4.2 mM glucose with a detection limit of 2 μM (S/N = 3). Moreover, the methodology can be applied for the immobilization of other enzymes.     

An in vitro comparative study on the reactivation of nerve agent-inhibited guinea pig and human acetylcholinesterases by oximes

The reactivation of nerve agent-inhibited acetylcholinesterase (AChE) by oxime is the most important step in the treatment of nerve agent poisoning. Since the evaluation of nerve agent antidotes cannot be conducted in humans, results from animal experiments are extrapolated to humans. Guinea pig is one of the animal models that is frequently used for conducting nerve agent antidote evaluations. Several investigations have demonstrated that the efficacy of an oxime primarily depends on its ability to reactivate nerve agent-inhibited AChE. If the in vitro oxime reactivation of nerve agent-inhibited animal AChE is similar to that of human AChE, it is likely that the results of an in vivo animal study will reliably extrapolate to humans. Therefore, the goal of this study was to compare the reactivation of guinea pig and human AChEs inhibited by six different G and V type nerve agents. Reactivation kinetic studies with five mono- and bis-pyridinium oximes showed that oxime reactivation of nerve agent-inhibited human AChE in most cases was faster than guinea pig AChE. The most significant enhancement was observed in the reactivation of human AChE inhibited by nerve agents containing bulky side chains GF, GD, and VR, by H-series oximes HLo-7, HI-6, and ICD-585. In these cases, species-related differences observed between the two AChEs, based on the second-order reactivation rate constants, were 90- to over 400-fold. On the other hand, less than 3-fold differences were observed in the rates of aging of nerve agent-inhibited guinea pig and human AChEs. These results suggest that the remarkable species-related differences observed in the reactivation of nerve agent-inhibited guinea pig and human AChEs were not due to differences in the rates of aging. These results also suggest that guinea pig may not be an appropriate animal model for the in vivo evaluation of oxime therapy.     

Efficacy of the entomopathogenic nematode, Steinernema feltiae, against sweetpotato whitefly Bemisia tabaci (Homoptera: Aleyrodidae) under laboratory and glasshouse conditions

The potential of using the entomopathogenic nematode Steinernema feltiae to control the sweetpotato whitefly Bemisia tabaci (Gennadius) has been established in previous laboratory studies. However, laboratory studies can overestimate the level of control achieved by biocontrol agents in the glasshouse. Glasshouse trials are therefore required to confirm laboratory results before full-scale commercial development is considered. Under both controlled laboratory and glasshouse conditions high mortality of second instar B. tabaci (>90% and >80%, respectively) was recorded after application of S. feltiae. The efficacy of the biocontrol agent at various application rates was also investigated, where halving the rate of S. feltiae application caused no significant reduction in B. tabaci mortality on tomato foliage. Steinernema feltiae has shown much potential for incorporation into integrated pest management strategies for the control of B. tabaci.     

Panicle Water Potential, a Physiological Trait to Identify Drought Tolerance in Rice

Two upland rice varieties （IRAT109, IAPAR9） and one lowland rice variety （Zhenshan 97B） were planted in summer and treated with both normal （full water） and drought stress in the reproductive stage. Panicle water potential （PWP） and leaf water potential （LWP） were measured every 1.0-1.5 h over 24 h on sunny days. Both PWP and LWP of upland varieties started to decrease later, maintained a higher level and recovered more quickly than that of the lowland variety. The results show that PWP can be used as an indicator of plant water status based on the parallel daily changes, and the high correlation between PWP and LWP. Similar correlations were also observed between PWP, LWP and eight traits related to plant growth and grain yield formation. PWP seemed to be more effective for distinguishing the upland rice varieties with different drought-tolerant ability. Differences in PWP and LWP between upland and lowland rice varieties were also observed at noon even under normal water conditions, implying the incorporation of the drought-tolerant mechanism to improve the photosynthesis and yield of traditional paddy rice.     

Cloning, purification, and characterization of thermostable hypoxanthine-guanine phosphoribosyltransferase from Thermoanaerobacter tengcongensis

Hypoxanthine-guanine phosphoribosyltransferase (HGPRT, EC 2.4.2.8) from a newly characterized thermophile Thermoanaerobacter tengcongensis was expressed in Escherichia coli and purified. Analytical gel filtration suggested that the enzyme exist as a homotetramer in solution. The optimal pH for the forward reaction was found to be 8.0 and the optimal temperature 70 degrees C. The steady-state kinetic characteristics suggest that hypoxanthine is the most effective substrate. This enzyme showed a half-life of 75min at 50 degrees C and no apparent loss of activity after 3 months at 4 degrees C.