[Plant Diversity Changes and Its Driving Factors of Abandoned Land at Different Restoration Stages in the Middle of the Qinling Mountains].

The process of vegetation restoration is often accompanied by significant changes in aboveground plant diversity. To explore the driving mechanism of litter nutrient-soil nutrient-enzyme activity stoichiometry on aboveground vegetation change is of great importance for maintaining regional biodiversity conservation and ecological stability. Taking typical abandoned farmland of different restoration years （1， 8， 16， 31， and 50 a） in the Qinling Mountains as the research object， the variation characteristics of plant community diversity during vegetation restoration were analyzed through field investigation. Litter nutrients， soil nutrients， and the activities of five extracellular enzymes， including ß-1，4-glucosidase （BG）， cellobiohydrolase （CBH）， ß-1，4-N-acetylglucosaminidase （NAG）， leucine aminopeptidase （LAP）， and acid phosphatase （AP）， were determined. The characteristics of litter nutrients， soil nutrients， and enzyme stoichiometric ratios during vegetation restoration and the driving mechanism of plant diversity changes were discussed. The results showed that the plant community diversity index firstly decreased and then increased with the increase in vegetation restoration years， and the minimum was reached at 16 years after restoration. The results of principal component analysis showed that there were significant differences between total plant community diversity index and litter-soil-enzyme stoichiometric characteristics in different years of vegetation restoration. The plant community diversity index had a strong positive correlation with litter C∶P ratio and litter N∶P ratio but had a negative correlation with soil enzyme C∶P ratio （EEA C∶P）. The results of redundancy analysis showed that soil EEA C∶P had the highest explanation rate of plant diversity changes during vegetation restoration （25.93%）， followed by soil TP （5.94%）， which was the key factor regulating plant diversity changes. In conclusion， plant species and quantity increased significantly in abandoned farmland in the middle part of the Qinling Mountains at the late stage of vegetation restoration. Changes in the soil environment affected microbial metabolic activities and thus changed enzyme activities. Litter-soil-soil extracellular enzymes affected the community environment and plant diversity through feedback and regulation. EEA C∶P and TP were the main driving factors of aboveground plant diversity change during vegetation restoration.

[Extracellular Enzyme Stoichiometry and Microbial Metabolism Limitation During Vegetation Restoration Process in the Middle of the Qinling Mountains, China].

Clarifying the characteristics of soil microbial nutrient limitation and its driving mechanisms during vegetation restoration after farmland abandonment has important implications for revealing soil nutrient cycling and maintaining ecosystem stability. To determine the limitation of soil microbial nutrients and its relationship with soil properties along a chronosequence of abandoned farmland in the middle of the Qinling Mountains, the soil physicochemical properties and five enzyme activities (ß-1,4-glucosidase (BG), cellobiohydrolase (CBH), ß-1,4-N-acetylglucosaminidase (NAG), leucine aminopeptidase (LAP), and acid phosphatase (AP)) were measured, and models of extracellular enzymatic activity were applied. The results showed that the activities of BG, CBH, NAG, LAP, and AP were significantly increased following farmland abandonment. With the increasing years of abandonment, the ratios of (BG+CBH)/(NAG+LAP) and (BG+CBH)/AP significantly decreased, whereas the ratio of (NAG+LAP)/AP increased. Correlation analysis showed that most soil physicochemical properties were significantly correlated with extracellular enzyme activities and extracellular enzymatic stoichiometry. The vector length of extracellular enzymatic stoichiometry decreased with the increase in abandonment years, indicating that the limitation of soil microorganisms on carbon (C) was reduced. Moreover, the vector angles (>45°) showed a decreasing trend, indicating that microbial metabolisms were limited by phosphorus (P) and gradually decreased. Regression analysis showed that the C and P limitations were significantly related to total nutrients, available nutrients, nutrient ratio, and soil physical properties. Partial least squares path modeling (PLS-PM) revealed that the C and P limitations were directly regulated by nutrient ratio. PLS-PM further showed that soil total nutrients indirectly affected soil microbial C and P limitations by affecting nutrient ratio, and nutrient ratio affected the soil metabolism limitation via available nutrients and pH. Our study suggests that the characteristics of microbial metabolism during the vegetation restoration process reflect the mechanism of microorganism-mediated soil nutrient cycling, which provides a theoretical basis for revealing the community dynamics and stability during the vegetation restoration process and maintaining the regional ecological environment security in the Qinling Mountains.

Awake craniotomy for auditory brainstem implant in patients with neurofibromatosis type 2: Four case reports.

BACKGROUND: The auditory brainstem implant (ABI) is a significant treatment to restore hearing sensations for neurofibromatosis type 2 (NF2) patients. However, there is no ideal method in assisting the placement of ABIs. In this case series, intraoperative cochlear nucleus mapping was performed in awake craniotomy to help guide the placement of the electrode array. CASE SUMMARY: We applied the asleep-awake-asleep technique for awake craniotomy and hearing test via the retrosigmoid approach for acoustic neuroma resections and ABIs, using mechanical ventilation with a laryngeal mask during the asleep phases, utilizing a ropivacaine-based regional anesthesia, and sevoflurane combined with propofol/remifentanil as the sedative/analgesic agents in four NF2 patients. ABI electrode arrays were placed in the awake phase with successful intraoperative hearing tests in three patients. There was one uncooperative patient whose awake hearing test needed to be aborted. In all cases, tumor resection and ABI were performed safely. Satisfactory electrode effectiveness was achieved in awake ABI placement. CONCLUSION: This case series suggests that awake craniotomy with an intraoperative hearing test for ABI placement is safe and well tolerated. Awake craniotomy is beneficial for improving the accuracy of ABI electrode placement and meanwhile reduces non-auditory side effects.

[Impact of habitats on rodent-mediated seed fates of Quercus aliena var. acuteserrata.] / ç”Ÿå¢ƒå¯¹å•®é½¿åŠ¨ç‰©ä»‹å¯¼ä¸‹é”é½¿æ§²æ Žç§å­å‘½è¿çš„å½±å“.

Disturbance is the driving force of forest succession, which can change forest structure and surface vegetation. Disturbance also affects rodent-mediated seed dispersal. In this study, numbered plastic tags were used to examine the responses of rodent dispersal behavior to the fates of Quercus aliena var. acuteserrata acorns at three habitats formed by different artificial disturbances in pine-oak mixed forests in the Qinling Mountains, i.e., unlogged stand, stand in the third year after tending thinning, and bare land. The results showed that seed removal rate from stands in the third year after tending was significantly higher than that in the other two habitats. The proportion of predation in bare land was significantly lower than that in the unlogged stand (25.0%) and in the stand in the third year after tending thinning (36.3%). In the third year after tending thinning, the seed predation rate after seed moving was significantly higher than those in the unlogged stand (17.3%) and bare land (5.0%). Moreover, the proportion of scatter hoarding after removal was also highest in the stand in the third year after tending thinning (4.3%). The longest average dispersal distance (26 m) occurred in the stand in the third year after tending thinning, which was significantly longer than those at the other two habitats. Therefore, the different habitat types significantly influenced the initial seed dispersal process by rodents, with consequences on the rates of seedling establishment. Habitat types affected the foraging strategies of rodents, thereby leading to different seed dispersal modes and natural regeneration patterns in the forest.

Spirometric Reference Equations for Elderly Chinese in Jinan Aged 60-84 Years.

BACKGROUND: The interpretation of spirometry varies on different reference values. Older people are usually underrepresented in published predictive values. This study aimed at developing spirometric reference equations for elderly Chinese in Jinan aged 60-84 years and to compare them to previous equations. METHODS: The project covered all of Jinan city, and the recruitment period lasted 9 months from January 1, 2017 to September 30, 2017, 434 healthy people aged 60-84 years who had never smoked (226 females and 208 males) were recruited to undergo spirometry. Vital capacity (VC), forced VC (FVC), forced expiratory volume in 1 s (FEV1), FEV1/FVC, FEV1/VC, FEV6, peak expiratory flow, and forced expiratory flow at 25%, 50%, 75%, and 25-75% of FVC exhaled (FEF25%, FEF50%, FEF75%, and FEF25-75%) were analyzed. Reference equations for mean and the lower limit of normal (LLN) were derived using the lambda-mu-sigma method. Comparisons between new and previous equations were performed by paired t-test. RESULTS: New reference equations were developed from the sample. The LLN of FEV1/FVC, FEF25-75%computed using the 2012-Global Lung Function Initiative (GLI) and 2006-Hong Kong equations were both lower than the new equations. The biggest degree of difference for FEV1/FVC was 19% (70.46% vs. 59.29%, t = 33.954, P < 0.01) and for maximal midexpiratory flow (MMEF, equals to FEF25-75%) was 22% (0.82 vs. 0.67, t = 21.303, P < 0.01). The 1990-North China and 2009-North China equations predicted higher mean values of FEV1/FVC and FEF25-75%than the present model. The biggest degrees of difference were -4% (78.31% vs. 81.27%, t = -85.359, P < 0.01) and -60% (2.11 vs. 4.68, t = -170.287, P < 0.01), respectively. CONCLUSIONS: The newly developed spirometric reference equations are applicable to elderly Chinese in Jinan. The 2012-GLI and 2006-Hong Kong equations may lead to missed diagnoses of obstructive ventilatory defects and the small airway dysfunction, while traditional linear equations for all ages may lead to overdiagnosis.

Isolation and diversity of natural product biosynthetic genes of cultivable bacteria associated with marine sponge Mycale sp. from the coast of Fujian, China.

The marine sponge Mycale sp., a potential source of natural bioactive products, is widely distributed along the coast of Fujian, China. The cultivable bacterial community associated with Mycale sp., the antibacterial activities, and the PKS (polyketide synthase) and NRPS (nonribosomal peptide synthetase) gene diversity of these bacteria were investigated. Phylogenetic analysis of the 16S rRNA gene showed that the 51 isolates from Mycale sp. belonged to Actinobacteria, Bacteroidetes, Gammaproteobacteria, Alphaproteobacteria, and Firmicutes. Among them, some bacteria were first isolated from marine sponge. The 20 isolates with antimicrobial activities were primarily clustered within the groups Actinobacteria, Gammaproteobacteria, and Bacillus. Strain HNS054, which showed 99% similarity to Streptomyces labedae, exhibited the strongest antimicrobial activity against Gram-positive bacteria (Staphylococcus aureus MTCC 1430, Bacillus subtilis MTCC 441) and Vibrio species. The screening of natural product biosynthetic genes revealed that 8 Actinobacteria species with antimicrobial activities possessed PKS-KS (ketosynthase) or NRPS-A domains, and the Nocardiopsis species contained a hybrid or mixed PKS-NRPS system. The phylogenetic analysis of the amino acid sequences indicated that the identified KS domains clustered with those from diverse bacterial groups, including Actinobacteria, Alphaproteobacteria, Cyanobacteria, and Firmicutes. Most KS domain sequences had high homology (>80%) to type I KSs, but the KS domain of Nocardiopsis sp. strain HNS048 had 77% similarity to the type II KS domain of Burkholderia gladioli. The NRPS-A domains of the 8 isolates were grouped into the Gammaproteobacteria, Actinobacteria, and Firmicutes groups. The NRPS-A gene of strain HNS052, identified as Nocardiopsis cyriacigeorgica, showed only 54% similarity to Rhodococcus opacus. All results suggested that Mycale sp. harboured diverse bacteria that could contribute to the production of novel bioactive substances in the future.

[Effects of relative abundance of Quercus mongolica acorns on five tree species seed dispersal in Xiaoxing' an Mountains, Northeast China].

An investigation was conducted in a forest farm in the Xiaoxing' an Mountains in autumn, 2009 and 2010 to study the effects of Quercus mongolica acorn quantity and rodent density on the seed dispersal of five tree species (Juglans mandshurica, Pinus koraiensis, Corylus mandshurica, Corylus heterophylla, and Q. mongolica). In the farm, there was an annual change in rodent density. The total capture rate of small rodents in 2009 (31.0%) was significantly higher than that in 2010 (16.7%). The acorn quantity and relative seed abundance (per capita rodent) of Quercus mongolica in 2009 (6.2 +/- 2.1 acorns x m(-2) and 20.0, respectively) were significantly lower than those in 2010 (26.7 +/- 10.2 acorns x m(-2) and 160.0, respectively). In 2009, all the seeds of the five tree species except J. mandshurica were dispersed or eaten in situ, among which, the acorns of Q. mongolica were scatter-hoarded most, and their average dispersal distance was the furthest. In 2010, the seeds of J. mandshurica were scatter-hoarded most, and their average dispersal distance was the furthest. The relative seed abundance of Q. mongolica could be the key factor determining the seed dispersal of the other tree species in the study area.

[Regeneration characteristics and related affecting factors of Pinus tabulaeformis secondary forests in Qinling Mountains].

The study with sampling plot method showed that in Pinus tabulaeformis secondary forests in Qinling Mountains, there were 36 tree species in regeneration layer, occupying 51.4% of the total. The dominant species were Quercus glandulifera, Quercus aliena var. acuteserrata, and Corylus heterophylla. The seedling bank was abundant, and with lower height class and age class. The main regeneration type was seedling, showing the forest being at its middle succession period. Stand density had significant effects on sapling and seedling densities (P<0.01). The sapling and seedling densities increased when the stand density increased from 580 trees x hm(-2) up to 1500 trees x hm(-2), but decreased with the further increase of stand density. Slope aspect also had significant effects on the seedling and sapling densities (P<0.05). The sapling density decreased gradually when the slope aspect changed from SW10 degrees to SW40 degrees, but increased with the slope aspect changed to shady slope (NE10 degrees). The forest regeneration characteristics differed at different slope positions, with the sapling and seedling densities being relatively higher in flat stand. From foot to top, the seedling density decreased, while the sapling density increased. The sapling density increased from the altitude 1159 m up to 1449 m but decreased from 1449 m up to 1658 m, while the seedling density all along had an increasing trend from lower altitude to higher altitude. It was suggested that the medium stand density on shady slope had the best natural regeneration. To rationally regulate stand density could be an effective way to accelerate the regeneration process of P. tabulaeformis forest.

[Regeneration characteristics of woody plant seedlings in typical secondary forests in Qinling Mountains].

By using sampling plot method, an investigation was conducted on the regeneration characteristics of woody plant seedlings in five kinds of typical secondary forests (Pinus tabulaeformis, Quercus valiena var. acuteserrata, Betula albo-sinensis, Picea asperata, and Pinus armandii) in Qinling Mountains. There was an obvious species differentiation of woody plant seedlings and saplings in the forests. Except for Q. valiena var. acuteserrata and P. armandii forests, the similarity coefficient of the seedlings and saplings species in the forests was lower. The seedlings and saplings quantity, species richness index, Simpson dominance index, and evenness index were higher in P. tabulaeformis and Q. valiena var. acuteserrata forests, the lowest in B. albo-sinensis forest, and basically the same in P. asperata and P. armandii forests. The percentages of the seedlings and saplings in the five forests had significant differences (P < 0.05). Except in B. albo-sinensis forest where the percentage of the saplings was higher, the percentage of the seedlings in the other stands was larger, and in the order of P. asperata forest > P. tabulaeformis forest > Q. valiena var. acuteserrata forest > P. armandii forest, respectively. The sprouting percentage of the seedlings in different forests had significant difference (P < 0.05), and was in the sequence of P. armandii forest > P. asperata forest > B. albo-sinensis forest > Q. valiena var. acuteserrata forest > P. tabulaeformis forest. In Q. valiena var. acuteserrata and P. tabulaeformis forests, the percentage of tree seedlings was the highest, occupying 68% and 51.4% of the total number of woody seedlings, respectively, and their communities were in the medium succession period, with a stronger persistent regeneration capability; in P. asperata and P. armandii forests, the percentage of tree seedlings was 40% and 15%, respectively, and their communities were in the late succession period, with a rather poor regeneration capability; while in B. albo-sinensis forest, the seedlings were difficult to develop into saplings, and thus, its continuous persistent regeneration capability was lack.

[Species composition and point pattern analysis of standing trees in secondary Betula albosinensis forest in Xiaolongshan of west Qinling Mountains].

An investigation was conducted on the species composition and population diameter-class structure of a typical secondary Betula albo-sinensis forest in Xiaolongshan of west Qinling Mountains, and the spatial distribution pattern and interspecific correlations of the main populations were analyzed at multiple scales by the O-ring functions of single variable and double variables. In the test forest, B. albo-sinensis was obviously dominant, but from the analysis of DBH class distribution, the B. albo-sinensis seedlings were short of, and the natural regeneration was very poor. O the contrary, the regeneration of Abies fargesii and Populus davidianas was fine. B. albo-sinensis and Salix matsudana had a random distribution at almost all scales, while A. fargesii and P. davidianas were significantly clumped at small scale. B. albo-sinensis had positive correlations with A. fargesii and P. davidianas at medium scale, whereas S. matsudana had negative correlations with B. albo-sinensis, A. fargesii, and P. davidianas at small scale. No significant correlations were observed between other species. The findings suggested that the spatial distribution patterns of the tree species depended on their biological characteristics at small scale, but on the environmental heterogeneity at larger scales. In a period of future time, B. albo-sinensis would still be dominant, but from a long-term view, it was necessary to take some artificial measures to improve the regeneratio of B. albo-sinensis.

[Effects of forest gap on herbaceous plant diversity in mixed birch-fir forest of Taibai Mountain].

To better understand the effects of forest gap on the herbaceous species community in a mixed birch-fir forest of Taibai Mountain in Qinling, CCA ordination and random permutation test were employed to analyze the distribution pattern of the species composition across a gradient of gap size, and the relationships between the distribution of 55 herbaceous species with > or = 5 individuals and the habitat variables (convexity, slope, and soil total N, total P, available N, available P, pH, and organic matter). In this forest, gap area occupied 19.8% of the total land area, gap density was 20.7 per hm2, and gap size varied from 25.6 to 279.1 m2, with a mean of 93.7 m2. The species richness in herbaceous layer in gaps was significantly positively correlated with gap size, but of the 69 herbaceous species identified in the gaps, most species were found across all gap sizes, and only eight species were found in larger gaps (>120 m2). No successional change was observed in the herbaceous species distribution with gap size. The CCA ordination and random permutation test also showed that 27.3% of the 55 species with abundance > or = 5 had significant association with the eight habitat variables. It was concluded that gap size contributed to the species richness, but determined the diversity constitution in random.

Highly efficient and enantioselective biotransformations of racemic azetidine-2-carbonitriles and their synthetic applications.

Catalyzed by the Rhodococcus erythropolis AJ270 whole cell catalyst in neutral aqueous buffer at 30 degrees C, a number of racemic 1-benzylazetidine-2-carbonitriles, trans-1-benzyl-4-methylazetidine-2-carbonitrile, and 1-benzyl-2-methylazetidine-2-carbonitrile and their amide substrates underwent efficient and enantioselective biotransformations to afford the corresponding azetidine-2-carboxylic acids and their amide derivatives in excellent yields with ee up to >99.5%. The overall excellent enantioselectivity of the biocatalytic reactions stemmed from a combined effect of a very active but virtually nonenantioselective nitrile hydratase and a high R-enantioselective amidase involved in microbial whole cells. The synthetic applications have been demonstrated by the nucleophilic ring-opening reactions of azetidiniums of the resulting chiral azetidine-2-carbox amide derivatives for the preparation of alpha,gamma-diamino, alpha-phenoxy-gamma-amino, and alpha-cyano-gamma-amino carboxamides. The intramolecular CuI-catalyzed cross-coupling reaction for the synthesis of azetidine-fused 1,4-benzodiazepin-2-one derivative was also presented.

Isolation and characterization of microsatellite loci in Babylonia areolata and cross-species amplification in Babylonia formosae habei.

Nine novel microsatellite primer pairs were presented for Babylonia areolata, representing the first microsatellite markers available for this genus. Levels of polymorphism were variable with 2 to 11 alleles per locus and expected heterozygosities ranging from 0.073 to 0.907 in 27 individuals of the population from which the loci were isolated. We found significant heterozygote deficit at one locus that might be attributable to null alleles. We were successful at cross-amplifying six loci in the congeneric B. formosae habei. These markers are therefore potentially useful for conservation studies, population structure assessment, ecological analyses and linkage map construction.

A new strategy for the synthesis of 1,4-benzodiazepine derivatives based on the tandem N-alkylation-ring opening-cyclization reactions of methyl 1-arylaziridine-2-carboxylates with N-[2-bromomethyl(phenyl)]trifluoroacetamides.

A new method for the synthesis of novel 1,4-benzodiazepine derivatives has been established from a one-pot reaction of methyl 1-arylaziridine-2-carboxylates with N-[2-bromomethyl(aryl)]trifluoroacetamides. The reaction proceeds through the N-benzylation and highly regioselective ring-opening reaction of aziridine by bromide anion followed by Et3N-mediated intramolecular nucleophilic displacement of the bromide by the amide nitrogen. The easy availability of starting materials, simple and convenient synthetic procedure, and formation of functionalized 1,4-benzodiazepine scaffold ready for further chemical manipulations render this strategy useful in synthetic and medicinal chemistry.