Priming effects of nZVI on carbon sequestration and iron uptake are positively mediated by AM fungus in semiarid agricultural soils

We investigated the priming effect of nanoscale zero-valent iron (nZVI) on carbon sink and iron uptake, and the possible mediation by AMF (arbuscular mycorrhizal fungi, Funneliformis mosseae) in semiarid agricultural soils. Maize seed dressings comprised of three nZVI concentrations of 0, 1, 2 g·kg^-1 and was tested with and without AMF inoculation under high and low soil moistures, respectively. The ICP-OES observations indicated that both low dose of nZVI (1 g·kg^-1) and high dose of nZVI (2 g·kg^-1) significantly increased the iron concentrations in roots (L: 54.5-109.8 %; H: 119.1-245.4 %) and shoots (L: 40.8-78.9 %; H: 81.1-99.4 %). Importantly, the absorption and translocation rate of iron were substantially improved by AMF inoculation under the low-dose nZVI. Yet, the excess nanoparticles as a stress were efficiently relieved by rhizosphere hyphae, and the iron concentration in leaves and stems can maintain as high as about 300 mg·kg^-1 while the iron translocation efficiency was reduced. Moreover, next-generation sequencing confirmed that appropriate amount of nZVI clearly improved the rhizosphere colonization of Funneliformis mosseae (p < 0.001) and the development of soil fungal community. Soil observations further showed that the hyphae development and GRSP (glomalin-related soil protein) secretion were significantly promoted (p < 0.05), with the increased R_0.25 (< 0.25 mm) by 35.97-41.16 %. As a return, AMF and host plant turned to input more organic matter into soils for microbial growth and Fe uptake, and such interactions became more pronounced under drought stress. In contrast, high dose of nZVI (2 g·kg^-1) tended to agglomerate on the surface of hyphae and spores, causing severe deformation and inactivation of AMF symbionts. Therefore, the priming effects of nZVI on carbon sequestration and Fe uptake in agricultural soils were positively mediated by AMF via the feedback loop of the plant-soil-microbe system for enhanced adaptation to global climate change.

Rhizosphere effect of nanoscale zero-valent iron on mycorrhiza-dependent maize assimilation

Rhizosphere effect of nanoscale zero-valent iron (nZVI) is crucial but little reported. Maize seeds were dressed with four nZVI concentrations (0, 1.0, 1.5, 2 g kg^-1 ) and inoculated with arbuscular mycorrhizal fungus (AMF) (Funneliformis mosseae). The SEM images illuminated that excessive nZVI particles (2 g kg^-1 ) were agglomerated on the surface of hyphae and spore, causing severe deformation and inactivation of AMF symbionts and thereafter inhibiting water uptake in maize seedlings. This restrained the scavenging effects of enzymatic (superoxide dismutase, peroxidase) and non-enzymatic compounds (proline & malondialdehyde) on ROS, and leaf photoreduction activity and gas exchange ability (p < 0.05). Interestingly, the inoculation with AMF effectively alleviated above negative effects. In contrast, appropriate dose of nZVI, that is, ≤1.5 g kg^-1 , can be evenly distributed on the hyphae surface and form the ordered symbionts with AMF. This help massively to enhance hyphae growth and water and nutrient uptake. The enhanced mycorrhizal infection turned to promote rhizosphere symbiont activity and leaf Rubisco and Rubisco activase activity. Light compensation point was massively lowered, which increased photosynthetic carbon supply for AMF symbionts. Particularly, such priming effects were evidently enhanced by drought stress. Our findings provided a novel insight into functional role of nZVI in agriculture and AMF-led green production.

Dual effects of nZVI on maize growth and water use are positively mediated by arbuscular mycorrhizal fungi via rhizosphere interactions

Nanoscale zero-valent iron (nZVI) might generate positive and negative effects on plant growth, since it acts as either hazardous or growth-promotion role. It is still unclear whether such dual roles can be mediated by arbuscular mycorrhizal fungi (AMF) in plant-AMF symbiosis. We first identified that in 1.5 g kg^-1 nZVI (≤1.5 g kg^-1 positively), maize biomass was increased by 15.83%; yet in 2.0 g kg^-1 nZVI, it turned to be declined by 6.83%, relative to non-nZVI condition (CK, p < 0.05), showing a negative effect. Interestingly, the inoculation of AMF massively improved biomass by 45.18% in 1.5 g kg^-1 nZVI, and relieved the growth inhibition by 2.0 g kg^-1 nZVI. The event of water use efficiency followed similar trend as that of biomass. We found that proper concentration of nZVI can positively interact with rhizosphere AMF carrier, enabling more plant photosynthetic carbon to be remobilized to mycorrhiza. The scanning of transmission electron microscopy showed that excessive nZVI can infiltrate into root cortical cells and disrupt cellular homeostasis mechanism, significantly increasing iron content in roots by 76.01% (p < 0.05). Simultaneously, the images of scanning electron microscopy showed that nZVI were attached on root surface to form an insoluble iron ion (Fe³⁺) layer, hindering water absorption. However, they were efficiently immobilized and in situ intercepted by extraradical hyphae in mycorrhizal-nZVI symbiosis, lowering iron translocation efficiency by 6.07% (p < 0.05). Herein, the optimized structure remarkably diminished aperture blockage at root surface and improved root activities by 30.06% (p < 0.05). Particularly, next-generation sequencing demonstrated that appropriate amount of nZVI promoted the colonization and development of Funneliformis mosseae as dominant species in rhizosphere, confirming the positive interaction between AMF and nZVI, and its regulatory mechanism. Therefore, dual effects of nZVI can be actively mediated by AMF via rhizosphere interactions. The findings provided new insights into the safe and efficient application of nanomaterials in agriculture.

Transition in plant-plant facilitation in response to soil water and phosphorus availability in a legume-cereal intercropping system

BACKGROUND

The tradeoff between negative and positive interactions of facilitated species and facilitators may depend on the degree of resource availability in agroecosystems. However, the rhizospheric mechanisms driving trade-offs that occur along phosphorus (P) and water availability gradients have not yet been systematically clarified. We established three types of root isolation conditions (no barrier, nylon barrier and solid barrier) at different P and water addition levels to address the above issue in a maize-grass pea intercropping system.

RESULTS

The total yield and biomass net effect (NE) and the relative interaction index (RII) were significantly higher than 0 under all environmental conditions, demonstrating that plant-plant interactions generated positive effects in the intercropping system. The maize yield and biomass RII were 0.029-0.095 and 0.018-0.066, respectively, which indicated that maize growth was constantly facilitated. However, the RII for grass pea yield and biomass exhibited a different trend in comparison with maize. It was higher than 0 (as the facilitated species) under low soil P and moisture conditions and transitioned to values lower than 0 (facilitator species) under high P and moisture conditions, which showed that the type and intensity of plant-plant interactions steadily shifted with the applied stressors. Direct interactions decreased the maize rhizospheric soil pH by 1.5% and 1.9% under Low-P conditions. Notably, the rhizospheric soil acid and alkaline phosphatase secretions of maize and grass pea increased by 17.4-27.4% and 15.3-27.7%, respectively, in P-deficient soils. These results show that plant-plant interactions can effectively relieve P stress by mineralizing organophosphorus in P-deficient soils. Furthermore, the above tendency became more pronounced under drought-stressed conditions. The nylon barrier partially restricted the exchange and utilization of available nutrients and decreased the total yield and biomass by 1.8-7.8% and 1.1-7.8%, respectively. The presence of a solid barrier completely restricted interspecific rhizospheric interactions and decreased the total yield and biomass by 2.1-13.8% and 1.6-15.7%, respectively. Phytate and KH₂PO₄ addition intensified asymmetric interspecific competition, and grass pea was consistently subjected to competitive pressures.

CONCLUSION

Briefly, the tradeoff between facilitation and competition was driven by rhizospheric interactions, and the transition in the intensity and type of interaction was highly dependent on resource availability in a biologically diverse system.

[Clinical analysis of 10 patients of chronic subdural hematoma associated with arachnoid cyst]

Objective: To investigate the clinical characteristics, pathogenesis and surgical strategy for the chronic subdural hematoma associated with arachnoid cyst (AC). Method: Ten patients of chronic subdural hematoma associated with AC were retrospectively enrolled from the Neurosurgery Department of Tianjin Medical University General Hospital from January 2012 to September 2015, with a mean age of 27.5±5.6 years (range, 18-37 years). All patients simply performed a burr hole drainage of hematoma and left the AC intact, then followed up for 12 to 18 months after discharge respectively. Results: In this study, the AC in 8 of 10 cases occurs in the middle cranial fossa, and the other 2 cases root in the cerebral hemisphere.The AC of 10 patients all locate near the hematoma cavity.Nine patients had a full recovery, and only one patient had a recurrent subdural hematoma with a secondary operation, then recovery in 3 months postoperation.All patients lived completely free of neurological symptom and showed no recurrence in the follow-up period with a Barthel index more than 90. Conclusion: Simply burr hole drainage of hematoma and leave intact AC achieves satisfied outcome and provides a reliable therapy strategy for chronic subdural hematoma associated with arachnoid cyst.

[Application of hybrid operating room in the treatment of spinal dural arteriovenous fistulas]

Objective: To explore the experience in the treatment of spinal dural arteriovenous fistulas with application of hybrid operating room. Method: A retrospective analysis was performed among 22 patients with spinal dural arteriovenous fistulas admitted to Department of Neurosurgery of Tianjin Medical University General Hospital who received operation in the hybrid operating room from March 2011 to February 2016. Modified Aminoff-Logue scores (ALS) for myelopathy was used to evaluate the spinal function.All the 22 patients were followed up 6-12 months after the operation. Result: All the patients were diagnosed by spinal digital subtraction angiography (DSA). The modified ALS pre-operation and post-operation 6 months were (4.7±1.8) and (2.0±1.5), respectively, with significant difference (P<0.01). There were 15 cases with mild dysfunction, 6 cases with moderate dysfunction, severe dysfunction in 1 case before operation.Fifteen cases were cured, 4 cases improved, 1 case had no change after 6 months follow-up.The improvement rate was 95.45%. Conclusion: The application of hybrid operating room in the treatment of spinal dural arteriovenous fistulas achieves good outcome and provides a convenient and effective approach, which embodies the idea of precision medicine.

Human papillomavirus type 16 E7 peptide(38-61) linked with an immunoglobulin G fragment provides protective immunity in mice

OBJECTIVE

To explore whether the recombinant protein (Human papillomavirus (HPV) type16 E7 peptide(38-61) linked with an immunoglobulin G fragment) will generate protective immunity in mouse model.

METHODS

In our study, we combined the HPV16 E7 peptide(38-61) with a murine IgG heavy chain constant region to construct a chimeric protein compound, which was highly expressed as inclusion bodies in a bacterial expression system with Escherichia coli. The purified chimeric protein was injected into C57BL/6 mice and the efficiency of the chimeric vaccine candidate was evaluated by antibody response assay, T cell proliferation assay, CTL assay, tumor challenge assay and therapeutic experiment.

RESULTS

The chimeric vaccine candidate was able to induce anti-HPV antibodies as well as to elicit HPV16 E7-specific CTLs and T cell proliferation in a pre-clinical mouse model. It was also able to effectively protect mice against the challenge of HPV16-positive tumor cells, and to eradicate HPV16-expressing tumors in mice.

CONCLUSIONS

The chimeric protein vaccine can induce E7-specific immune responses and protect mice against challenge of HPV16-positive tumor, even eradicate developed tumor. The results indicated a possibility to use the chimeric protein vaccine to protect human against HPV infection.

Increased interleukin-1beta converting enzyme expression and activity in Alzheimer disease

Increased expression of interleukin-1 in Alzheimer disease (AD) has been implicated as a driving force in neurodegenerative cascades that underlie the formation of neuritic plaques and neurofibrillary tangles, the spread of these neuropathological lesions across cerebral cortical regions, and the accompanying neuronal cell injury and loss. The beta isoform of interleukin-1 is generated from an inactive, 33-kDa precursor through the action of a specific interleukin-1beta converting enzyme (ICE), also known as caspase-1. We used mesial temporal tissue (hippocampus and parahippocampal cortex) obtained postmortem from Alzheimer and control patients for determinations of endogenous tissue ICE activity and for Western immunoblot analysis of tissue ICE concentrations. ICE activity in Alzheimer tissue was elevated 50-100% (p < 0.002, or better, at incubation times of 30 min to 10 h), and ICE protein level was elevated 180% (p = 0.01). Parahippocampal cortex of Alzheimer patients showed increased numbers of neurons with in situ evidence of DNA damage. Increased DNA degradation was also evident upon electrophoresis of isolated DNA. Overexpression and increased activity of ICE may contribute to neurodegeneration in AD through generation of biologically active interleukin-1, with consequent activation of interleukin-1-driven neurodegenerative cascades.

[Porencephaly. A report of 45 cases]

In 45 cases of porencephaly 35 were male and 10 female. Their age ranged from 80 days to 58 years (mean 14 years). In this series, symptoms were observed 80 days to 22 years before diagnosis. twenty-four cases were premature delivery, difficult labour or birth trauma. 14 cases had a history of head injury. 36 cases had congenital porencephalic cyst and 9 had post-traumatic porencephaly. The main symptoms and signs of porencephaly were dementia, speech defect, intracranial hypertension, hydrocephalus, epilepsy, ataxia or paralysis. etc. It is suggested that CT scan is very useful in the diagnosis of porencephaly, and section of cerebral cortex, opening of cyst, continuous drainage or shunting operation should be done as soon as the diagnosis was made.

Preliminary crystallographic analysis of deshexapeptide (B25-B30) insulin

Satisfactory single crystals of deshexapeptide (B25-B30) insulin for X-ray crystal structure analysis have been grown in citrate buffer by the method of hanging-drop gas phase diffusion. The crystal belongs to the monoclinic system with space group C2. The unit cell constants are a = 42.6 A, b = 37.9 A, c = 27.2 A, beta = 125.4 degrees and there is only one molecule of deshexapeptide insulin in an asymmetric unit.

Lamotrigine protects against kainate but not ibotenate lesions in rat striatum

Pretreatment of rats with 8-16 mg/kg of lamotrigine 1 h before intrastriatal injections of 2 nm of kainic acid significantly attenuated the neurotoxicity as evidenced by measurements of striatal choline acetyltransferase and glutamate decarboxylase activities. No significant effect was seen on the toxicity of intrastriatal injections of quinolinic acid or ibotenic acid. These differential effects are further evidence that these neurotoxins act at different excitatory amino acid receptors and that the neurotoxicity of kainate is uniquely dependent on neuronally released glutamate.

Immunostaining of human brain capillaries by antibodies to very late antigens

Normal and neurologically diseased brain tissue was stained with antibodies directed against very late antigens (VLAs) 1, 2, 3, 5, 6, their common beta 1-subunit, and three extracellular proteins: collagen type IV, laminin and fibronectin. Strong staining of capillaries was obtained in both normal and pathological tissue with antibodies to collagen type IV and its putative receptor VLA-1; laminin and its putative receptor VLA-6; and the common VLA beta 1-subunit. Only residual plasma in vessels was stained with the antibody to fibronectin. Negative staining was obtained with antibodies to the fibronectin receptor VLA-5 and VLA-3. Trace staining was obtained with the antibody to VLA-2.

gamma-Glutamyltransferase activity is unchanged in acutely quinolinate-lesioned rat neostriatum but is elevated in Huntington's disease caudate

gamma-Glutamyltransferase (GGT; gamma-glutamyl transpeptidase) was measured in the neostriata of rats 5-7 days after local injections of 0-150 nmol of quinolinic acid. In contrast to the high levels seen in studies on the caudate in a few Huntington's disease cases, GGT activity showed no significant relation to the amount of quinolinic acid injected or to the extent of neuronal loss, as indicated by assays of choline acetyltransferase and glutamate decarboxylase on the same striatal homogenates. The chronicity of the degenerative disease, contrasted with the acuteness of the lesion, may explain the difference.

Effect of MK-801, kynurenate, glycine, dextrorphan and 4-acetylpyridine on striatal toxicity of quinolinate

Measurements of striatal choline acetyltransferase (ChAT) and glutamic acid decarboxylase (GAD) activities indicated that systemic administration of 4-8 mg/kg of MK-801 to rats completely blocked neuronal damage due to intrastriatal injections of 75-150 nmol of quinolinic acid. Similar experiments with 0-2 mg/kg MK-801 suggested the ED50 might be between 1 and 1.5 mg/kg for protection against 50 nmol of intrastriatal quinolinic acid, and between 2 and 3 mg/kg for 75 nmol. Repeated pretreatment with kynurenate (3 x 300 mg/kg) gave significant but not complete protection against similar doses of quinolinic acid, with the protective effect being greater for GAD than for ChAT. Glycine appeared to potentiate the effect of high doses of quinolinic acid on ChAT and the other pretreatments tested (dextrorphan, dextromethorphan, 4-acetylpyridine) had no significant effect.

Gene amplification in Tetrahymena thermophila: formation of extrachromosomal palindromic genes coding for rRNA

Tetrahymena thermophila contains in the macronucleus multiple copies of extrachromosomal palindromic genes coding for rRNA (rDNA) which are generated from a single chromosomal copy during development. In this study we isolated the chromosomal copy of rDNA and determined the structure and developmental fate of the sequence surrounding its 5' junction. The result indicates that specific chromosomal breakage occurs at or near the 5' junction of rDNA during development. The breakage event is associated with DNA elimination and telomeric sequence addition. Similar results were also found previously for the 3' junction of this gene. These results could explain how the extrachromosomal rDNA is first generated. Near both junctions of the chromosomal rDNA, a pair of 20-nucleotide repeats was found. These sequences might serve as signals for site-specific breakage. In addition, we found a pair of perfect inverted repeats at the 5' junction of this gene. The repeats are 42 nucleotides long and are separated by 28 nucleotides. The existence of this structure provides a simple explanation for the formation of the palindromic rDNA.