Comparative studies on leaf epidermal micromorphology and mesophyll structure of Elaeagnus angustifolia L.in two different regions of desert habitat

In order to obtain qualitative and quantitative characteristics of leaf epidermal micromorphology and mesophyll structure to evaluate the responses ofElaeagnus angustifolia L. to different environmental factors, epidermal micromorphology was observed by scanning electron microscopy （SEM）, and mesophyll structure was studied by light microscopy （LM） and transmission electron microscopy （TEM）. Materials were selected from Linze County, Gansu Province （material A） and Qitai County, Xinjiang Uygur Autonomous Region （material B） of China. Results show that lamina thickness was higher in material A, with one layer of epidermal cells in both adaxial and abaxial surfaces, and epidermal cell radial length was significantly longer in the adaxial surface. E. angustifolia leaves are typically bifacial, with a higher ratio of palisade to spongy tissue in material A. The thickness of trichome layer of epidermis was thicker in material A. In contrast, cell wall and cuticular wax of the epidermal cells were thinner in material A than in material B. Chloroplast ultrastructure was different with the approximate spherical chloroplast containing numerous starch grains and osmiophilic granules in ma- terial A, while only the spindly chloroplast contained starch grains in material B. Multiple layers of peltate or stel- late-peltate trichomes occupied both leaf surfaces in material A and the abaxial surface in material B, while the adaxial surface of material B contained few trichomes. Stomata were not observed on the leaf surfaces in materials A and B by SEM because of trichome obstruction. Our results indicate that the leaf structure of E. angustifolia is closely correlated with environmental factors, and the combination of leaf epidermal micromorphology and mesophyll structure afford re- sistance to environmental stress.

Shifts in community structure and function of ammoniaoxidizing archaea in biological soil crusts along a revegetation chronosequence in the Tengger Desert

Metagenomic studies have demonstrated the existence of ammonia-oxidizing archaea(AOA) and revealed they are responsible for ammoxidation in some extreme environments. However, the changes in compositional structure and ammonia-oxidation capacity of AOA communities in biological soil crusts(BSCs) of desert ecosystems remain poorly understood.Here, we utilized Illumina MiSeq sequencing and microbial functional gene array(GeoChip 5.0) to assess the above changes along a 51-year revegetation chronosequence in the Tengger Desert, China. The results showed a significant difference in AOA-community richness between 5-year-old BSCs and older ones. The most dominant phylum during BSC development was Crenarchaeota, and the corresponding species were ammonia-oxidizing_Crenarchaeote and environmental_samples_Crenarchaeota. Network analysis revealed that the positive correlations among dominant taxa increased, and their cooperation was reinforced in AOA communities during BSC succession. Redundancy analysis showed that the dominant factor influencing the change in AOA-community structure was soil texture. GeoChip 5.0 indicated that the amoA gene abundances of AOA and ammonia-oxidizing bacteria(AOB) were basically the same, demonstrating that AOA and AOB played an equally important role during BSCs development. Our study of the long-term succession of BSC demonstrated a persistent response of AOA communities to revegetation development in desert ecosystems.

A real-time artifact reduction algorithm based on precise threshold during short-separation optical probe insertion in neurosurgery

During neurosurgery,an optical probe has been used to guide the micro-electrode,which is punc-tured into the globus pallidus(GP)to create a lesion that can relieve the cardinal symptoms.Accurate target localization is the key factor to afect the treatment.However,considering the scattering nature of the tissue,the“look ahead distance(LAD)”of optical probe makes the boundary between the diferent tissues blurred and difficult to be distinguished,which is defined as artifact.Thus,it is highly desirable to reduce the artifact caused by LAD.In this paper,a real-time algorithm based on precise threshold was proposed to eliminate the artifact.The value of the threshold was determined by the maximum error of the measurement system during the calibration procession automatically.Then,the measured data was processed sequentially only based on the threshold and the former data.Moreover,100μm double-fiber probe and two-layer and multi-layer phantom models were utilized to validate the precision of the algorithm.The error of the algorithm is one puncture step,which was proved in the theory and experiment.It was concluded that the present method could reduce the artifact caused by LAD and make the real boundary sharper and less blurred in real-time.It might be potentially used for the neurosurgery navigation.

Monte Carlo and phantom study in the brain edema models

Because the brain edema has a crucial impact on morbidity and mortality,it is important to develop a noninvasive method to monitor the process of the brain edema effectively.When the brain edema occurs,the optical properties of the brain will change.The goal of this study is to access the feasibility and reliability of using noninvasive near-infrared spectroscopy(NIRS)monitoring method to measure the brain edema.Specifically,three models,including the water content changes in the cerebrospinal fuid(CSF),gray matter and white matter,were explored.Moreover,these models were numerically simulated by the Monte Carlo studies.Then,the phantom experiments were performed to investigate the light intensity which was measured at different detecting radius on the tissue surface.The results indicated that the light intensity correlated well with the conditions of the brain edema and the detecting radius.Briefly,at the detect ing radius of 3.0 cm and 4.0 cm,the light intensity has a high response to the change of tissue parameters and optical properties.Thus,it is possible to monitor the brain edema noninvasively by NIRS method and the light intensity is a reliable and simple parameter to assess the brain edema.

The adaptive significance of differences of root morphology, anatomy and physiology from three ecotypes of reed(Phragmites communis Trin.)

Reeds are widely distributed in drought and high salt conditions of northwestern China. Leaf epidermal micromorphology, anatomy, chloroplast ultrastructure and physio-chemical characteristics due to long-term adaptation in the natural habitats of common reed （Phragmites communis Trin.） contrasted considerably among three different ecotypes： dune reed （DR）, Gobi salt reed （GSR） and swamp reed （SR）. The main objective of the present study is to determine the adapting characteristics of morphology, anatomy and physiological responses of thin roots in DR, GSR and SR. The results show that root length density was higher in SR and few root hairs were observed in DR. Cross-section anatomical features show that each ecotype has an endodermis and exodermis, while cortex thickness and proportion of root cortical aerenchyma and stele in root structure varied among the three ecotypes. The stele and xylem share a larger area in DR compared to GSR and SR. GSR has a large proportion of the cortex with radialized distribution of aerenchyma cells spacing, and the cortex has a peripheral, mechanically stiff ring in the exodermis. SEM and TEM microscope images show that GSR has a scle- renchyma ring with high lignification in the exodermis. The physio-chemical parameters show that GSR had a higher level of stress tolerance than DR. These findings indicate that developed water-absorbing tissues were largely distributed in the root structure of DR, and a main framework with supporting function spacing with aerenchyma was dominant in GSR in the long term adaptation to their natural habitats, respectively.

Involvement of anti-oxidative enzymes, photosynthetic pigments and flavonoid metabolism in the adaptation of Reaumuria soongorica to salt stress

Reaumuria soongorica is a short woody shrub widely found in semi-arid areas of China. It can survive severe environ- mental stress including high salinity in its natural habitat. Thus, we investigated the involvement of anti-oxidative enzymes, photosynthetic pigments and flavonoid metabolism in the adaptation of R. soongorica to saline environments. R. soon- gorica was treated with 0, 100, 200 and 400 mM NaC1 solutions for 14 days. Soil salt content increased significantly by watering with high content of NaC1 solution, and no variation between 8 and 14 days during treatment. The levels ofpe- roxidation of lipid membranes （measured by malondialdehyde content） and the activities of three antioxidant enzymes （superoxide dismutase （SOD）, peroxidase （POD） and ascorbate peroxidase （APX）） increased under salt stress. Chlorophyll and carotenoid content decreased with increasing salt content. The ratio of Chl a/Chl b and carotenoid/Chl exhibited sig- nificant increase under 400 mM NaC1. However, total flavonoid and anthocyanin contents and key enzyme activities in the flavonoid pathway including phenylalanine ammonialyase （PAL） and Chalcone isomerase （CHI） decreased under salt stress. These findings possibly suggest that R. soongorica has an adaptation protection mechanism against salt-induced oxidative damage by inducin~ the activity of antioxidant enzymes and maintaining a steady level of carotenoid/Chl.

Research on the relationship between reduced scattering coefficient and intracranial pressure in brain edema model

Intracranial hypertension is a serious threat to the health of neurosurgical patients.At present,there is a lack of a safe and e®ective technology to monitor intracranial pressure(ICP)accurately and nondestructively.In this paper,based on near infrared technology,the continuous nonde-structive monitoring of ICP change caused by brain edema was studied.The rat brain edema models were constructed by lipopolysaccharide.The ICP monitor and the self-made near infrared tissue parameter measuring instrument were used to monitor the invasive intracranial pressure and the reduced scattering coe±cient of brain tissue during the brain edema development.The results showed that there was a negative correlation between the reduced scattering coe±cient(690nm and 834nm)and ICP,and then the mathematical model was established.The experimental results promoted the development of nondestructive ICP monitoring based on near infrared technology.

Salt stress induced apoptotic-like changes in Thellungiella halophila

With a view of studying programmed cell death （PCD） in a halophytic plant at the molecular level, we report here that apop-totic-like changes are induced by NaCl stress in Thellungiella halophila. The dose of 300 mM NaCl induced some apoptotic-like features in Thellungiella halophila cells, including the retraction of the plasma membrane from the cell wall, nuclear condensation, DNA laddering and the release of cytochrome c accompanying the increase of caspase 3-like protease activity. This process re-sulted in ultrastructural changes of mitochondria and Golgi bodies, and the appearance of autophagic vacuoles. This suggests that T. halophila suspension cell culture is an ideal system for studying severe salt stress-induced plant PCD. The results indicate that 300 mM NaCl stress-induced programmed cell death in T. halophila cells is similar to apoptosis and mitochondria play an impor-tant role in the early stage of plant PCD.

Covalently tethering disulfonic acid moieties onto polyoxometalate boosts acid strength and catalytic performance for hydroxyalkylation/alkylation reaction

Solid acid catalysts are widely used in the production of various high-value added and industrially important chemicals.Although the use of organosilicon compounds to modify the vacancy site has been extensively studied,the covalent tethering-SO_(3)H functionalized organosilicon modified polyoxometalates(POMs)has been rarely reported.In this work,two catalysts(TBA_(4)[SiW_(11)O_(39)(O(SiC_(3)H_(6)SO_(3)H)_(2))](compound 2)and TBA_(4)[SiW_(11)O_(39)(O(SiC_(8)H_(8)SO_(3)H)_(2))](compound 3))were synthesized successfully through covalently grafting different sulfonic acid(-SO_(3)H)groups onto[SiW_(11)O_(39)]^(8−)cluster,respectively.Compound 2 was achieved by surface grafting and in situ oxidation(3-mercaptopropyl)-trimethoxysilane,while compound 3 was achieved by surface grafting of 2-(4-chlorosulfonylphenyl)ethyltrimethoxysilane.Strong Brønsted acid strength of compounds 2 and 3 can be demonstrated by different methods including potentiometric titration,pyridine adsorption studies,and the ^(31)P trimethylphosphine oxides(TMPO)nuclear magnetic resonance(NMR).The systematic investigation of the relationship among POM structures,acid strength,and electron density was carried out based on density functional theory(DFT)calculation and experimental results,which revealed that covalent modification of compounds 2 and 3 decreased the electron density of the O-H bond,and promoted the release of H^(+).When applied in hydroxyalkylation/alkylation(HAA)reaction of 2-methylfuran(2-MF)with cyclohexanone,compound 2 exhibited better catalytic performance with conversion of ~93%,monocyclic fuel precursors(1a)yield of 79.9% and selectivity of 85.7% than compound 3,which can be attributed to strong Brønsted acid and the intramolecular hydrogen-bonding interactions between the neighboring -SO_(3)H moieties in compound 2.Finally,compound 2 also showed excellent catalytic activity in the HAA reaction of 2-MF with several different aldehydes and ketones(e.g.,furfuraldehyde,5-methylfurfuraldehyde,acetone,butyraldehyde and 4-methoxybenzaldehyde).This result opens a new pathway for design and fabrication of novel solid acid catalysts.

Efficient silencing of the multicopy DUX4 gene by ABE-mediated start codon mutation in human embryos

The Dux gene plays an important role in mouse embryo development(De Iaco et al.,2017;Hendrickson et al.,2017;Whiddon et al.,2017).It participates in the maternal-to-zygotic transition(MTZ),which mainly includes maternal transcript degradation and zygotic genome activation(ZGA)and is the key process for embryonic development.Approximately 11-100 copies of the DUX4 gene form a tandem cluster in the human genome(Snider et al.,2009,2010).