In many plant species, leaf morphology varies with altitude, an effect that has been attributed to temperature. It remains uncertain whether such a trend applies equally to juvenile and mature trees across altitudinal gradients in semi-arid mountain regions. We examined altitude-related differences in a variety of needle characteristics of juvenile (2-m tall) and mature (5-m tall) alpine spruce (Picea crassifolia Kom.) trees growing at altitudes between 2501 and 3450 m in the Qilian Mountains of northwest China. We found that stable carbon isotope composition (δ13C), area- and mass-based leaf nitrogen concentration (Na, Nm), number of stomata per gram of nitrogen (St/N), number of stomata per unit leaf mass (St/LM), projected leaf area per 100 needles (LA) and leaf mass per unit area (LMA) varied nonlinearly with altitude for both juvenile and mature trees, with a relationship reversal point at about 3100 m. Stomatal density (SD) of juvenile trees remained unchanged with altitude, whereas SD and stomatal number per unit length (SNL) of mature spruce initially increased with altitude, but subsequently decreased. Although several measured indices were generally found to be higher in mature trees than in juvenile trees, Nm, leaf carbon concentration (Cm), leaf water concentration (LWC), St/N, LA and St/LM showed inconsistent differences between trees of different ages along the altitudinal gradient. In both juvenile and mature trees, δ13C correlated significantly with LMA, Nm, Na, SNL, St/LM and St/N. Stomatal density, LWC and LA were only significantly correlated with δ13C in mature trees. These findings suggest that there are distinct ecophysiological differences between the needles of juvenile and mature trees that determine their response to changes in altitude in semi-arid mountainous regions. Variations in the fitness of forests of different ages may have important implications for modeling forest responses to changes in environmental conditions, such as predicted future temperature increases in high altitude areas associated with climate change.
Marine fungal natural products (MFNPs) are a vital source of pharmaceuticals, primarily synthesized by relevant biosynthetic gene clusters (BGCs). However, many of these BGCs remain silent under standard laboratory culture conditions, delaying the development of novel drugs from MFNPs to some extent. This review highlights recent efforts in genome mining and biosynthetic pathways of bioactive natural products from marine fungi, focusing on methods such as bioinformatics analysis, gene knockout, and heterologous expression to identify relevant BGCs and elucidate the biosynthetic pathways and enzyme functions of MFNPs. The research efforts presented in this review provide essential insights for future gene-guided mining and biosynthetic pathway analysis in MFNPs.
Rapid climate change and intensified human activities have resulted in water table lowering (WTL) and enhanced nitrogen (N) deposition in Tibetan alpine wetlands. These changes may alter the magnitude and direction of greenhouse gas (GHG) emissions, affecting the climate impact of these fragile ecosystems. We conducted a mesocosm experiment combined with a metagenomics approach (GeoChip 5.0) to elucidate the effects of WTL (-20 cm relative to control) and N deposition (30 kg N ha-1 yr-1 ) on carbon dioxide (CO2 ), methane (CH4 ) and nitrous oxide (N2 O) fluxes as well as the underlying mechanisms. Our results showed that WTL reduced CH4 emissions by 57.4% averaged over three growing seasons compared with no-WTL plots, but had no significant effect on net CO2 uptake or N2 O flux. N deposition increased net CO2 uptake by 25.2% in comparison with no-N deposition plots and turned the mesocosms from N2 O sinks to N2 O sources, but had little influence on CH4 emissions. The interactions between WTL and N deposition were not detected in all GHG emissions. As a result, WTL and N deposition both reduced the global warming potential (GWP) of growing season GHG budgets on a 100-year time horizon, but via different mechanisms. WTL reduced GWP from 337.3 to -480.1 g CO2 -eq m-2 mostly because of decreased CH4 emissions, while N deposition reduced GWP from 21.0 to -163.8 g CO2 -eq m-2 , mainly owing to increased net CO2 uptake. GeoChip analysis revealed that decreased CH4 production potential, rather than increased CH4 oxidation potential, may lead to the reduction in net CH4 emissions, and decreased nitrification potential and increased denitrification potential affected N2 O fluxes under WTL conditions. Our study highlights the importance of microbial mechanisms in regulating ecosystem-scale GHG responses to environmental changes.
Introduction: A multimodal approach in operable early-stage oesophago-gastric (OG) cancer has evolved in the last decade, leading to improvement in overall outcomes.Areas covered: A review of the published literature and conference abstracts was undertaken on the topic of optimal adjunctive chemotherapy or chemoradiotherapy in early-stage OG cancers. This review article focuses on the current evidence pertaining to neoadjuvant and perioperative strategies in curable OG cancers including the evolving landscape of immunotherapy and targeted drugs in this setting.Expert commentary: Adjunctive therapies in the form of preoperative chemo-radiotherapy (CRT) or chemotherapy and perioperative chemotherapy over surgery alone improve outcomes in patients with operable OG cancer. Although there are variations in practice around the world, a multi-disciplinary approach to patient care is of paramount importance. Immunotherapy and on treatment functional imaging are two examples of emerging strategies to improve the outcome for early-stage patients. A better understanding of the molecular biology of this disease may help overcome the problem of tumor heterogeneity and enable more rationally designed and targeted therapeutic interventions in the future.
Morphological changes of a single human mesenchymal stem cell by trypsin-EDTA were measured via digital holographic microscopy. Cell contact area decreased, the maximum height increased and volume fluctuated as cell changed from flat to stereoscopic.
Across a growing season in 2017, we measured 21 leaf physiochemical traits, and also spectral reflectance of eight temperate broadleaf deciduous trees at Madingley wood (52°13′2.16″N, 0°2′55″E), and adjacent area on the outskirts of Cambridge in the UK.
Abstract High soil organic carbon content, extensive root biomass, and low nutrient availability make alpine grasslands an important ecosystem for assessing the influence of nutrient enrichment on soil respiration (SR). We conducted a four-year (2009–2012) field experiment in an alpine grassland on the Qinghai-Tibetan Plateau to examine the individual and combined effects of nitrogen (N, 100 kg ha −1 year −1 ) and phosphorus (P, 50 kg ha −1 year −1 ) addition on SR. We found that both N and P addition did not affect the overall growing-season SR but effects varied by year: with N addition SR increased in the first year but decreased during the last two years. However, while P addition did not affect SR during the first two years, SR increased during the last two years. No interactive effects of N and P addition were observed, and both N addition and P addition reduced heterotrophic respiration during the last year of the experiment. N and P addition affected SR via different processes: N mainly affected heterotrophic respiration, whereas P largely influenced autotrophic respiration. Our results highlight the divergent effects of N and P addition on SR and address the important potential of P enrichment for regulating SR and the carbon balance in alpine grasslands.
Abstract The vast wetlands on the Tibetan Plateau are expected to be an important natural source of methane (CH 4 ) to the atmosphere. The magnitude, patterns and environmental controls of CH 4 emissions on different timescales, especially during the nongrowing season, remain poorly understood, because of technical limitations and the harsh environments. We conducted the first study on year‐round CH 4 fluxes in an alpine wetland using the newly developed LI‐COR LI‐7700 open‐path gas analyzer. We found that the total annual CH 4 emissions were 26.4 and 33.8 g CH 4 m −2 in 2012 and 2013, respectively, and the nongrowing season CH 4 emissions accounted for 43.2–46.1% of the annual emissions, highlighting an indispensable contribution that was often overlooked by previous studies. A two‐peak seasonal variation in CH 4 fluxes was observed, with a small peak in the spring thawing period and a large one in the peak growing season. We detected a significant difference in the diurnal variation of CH 4 fluxes between the two seasons, with two peaks in the growing season and one peak in the nongrowing season. We found that the CH 4 fluxes during the growing season were well correlated with soil temperature, water table depth and gross primary production, whereas the CH 4 fluxes during the nongrowing season were highly correlated with soil temperature. Our results suggested that the CH 4 emission during the nongrowing season cannot be ignored and the vast wetlands on the Tibetan plateau will have the potential to exert a positive feedback on climate considering the increasing warming, particularly in the nongrowing season in this region.
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