一株重金属镉耐受小球藻的分离鉴定及其生长条件优化

以龙江河镉污染水体预留样本为实验材料,从中筛选得到一株重金属镉耐受藻株,经形态和分子生物学鉴定为小球藻属,命名为Chlorella sp.LQQ-1。实验从温度、pH、Cd²⁺、有机碳源及有机氮源等方面对该藻株生长条件进行优化,并考察其在最佳生长条件下对水体中Cd²⁺的去除效果。结果表明:该小球藻最适宜生长温度为30℃,最适宜pH为7.0左右。Cd²⁺在低浓度下能促进小球藻的生长,当Cd²⁺浓度超过30μmol·L^-1时,小球藻的生长受到抑制。适宜该小球藻生长的最佳葡萄糖添加浓度为10g·L^-1,最佳尿素添加浓度为1g·L^-1。在最佳生长条件下,该小球藻对水体中Cd²⁺的去除率达89.7%。     

Differential responses of litter decomposition to warming,elevated CO2, and changed precipitation regime

Plant and Soil - This study was performed to determine if the contribution of biological N2 fixation (BNF) associated with Brazilian sugarcane cultivars could be increased by the inoculation with...     

Evaluation of the Reliability of Six Commercial SERS Substrates

Plasmonics - Based on high sensitivity, specific fingerprinting spectra and real-time detection, surface-enhanced Raman spectroscopy (SERS) is a powerful tool for the observation, the detection and...     

精酮合剂对小鼠的抗疲劳作用

通过观察小鼠负重力竭游泳时间探讨精氨酸-酮戊二酸盐(精酮合剂,AAKG)对小鼠的抗疲劳作用,分别测定小鼠游泳前后血清尿素含量、肝糖原含量、全血乳酸含量等指标以探讨AAKG抗疲劳机制。结果表明,经AAKG处理过的小鼠负重游泳时间(4.71±1.36min)比对照组小鼠(3.01±0.46min)明显延长(P<0.05),AAKG组小鼠血清尿素氮含量(177.94±17.7mg/L)明显低于对照组(202.38±8.95mg/L)(P<0.05),AAKG组小鼠乳酸曲线下面积(85.88±9.74mmol/L)也显著低于对照组(112.82±17.10mmol/L)(P<0.05),而AAKG组小鼠肝糖原含量(11.95±0.35mg/g)显著性高于对照组小鼠(8.42±0.97mg/g)(P<0.05)。本实验结果表明AAKG具有较好的抗疲劳作用,推测与其能够提高小鼠代谢能力和增强应激能力有关。     

Lignin Degradation in Foliar Litter of Two Shrub Species from the Gap Center to the Closed Canopy in an Alpine Fir Forest

To understand the effects of forest gaps on lignin degradation during shrub foliar litter decomposition, a field litterbag experiment was conducted in an alpine fir (Abies faxoniana) forest of the eastern Tibet Plateau. Dwarf bamboo (Fargesia nitida) and willow (Salix paraplesia) foliar litterbags were placed on the forest floor from the gap center to the closed canopy. The litterbags were sampled during snow formation, snow coverage, snow melting and the growing season from October 2010 to October 2012. The lignin concentrations and loss in the litter were measured. Over 2 years, lignin loss was lower in the bamboo litter (34.64–43.89%) than in the willow litter (38.91–55.10%). In the bamboo litter, lignin loss mainly occurred during the first decomposition year, whereas it occurred during the second decomposition year in the willow litter. Both bamboo and willow litter lignin loss decreased from the gap center to the closed canopy during the first year and over the entire 2-year decomposition period. Compared with the closed canopy, the gap center showed higher lignin loss for both bamboo and willow litter during the two winters, but lower lignin loss during the early growing period. Additionally, the dynamics of microbial biomass carbon during litter decomposition followed the same trend as litter lignin loss during the two winters and growing period. These results indicated that alpine forest gaps had significant effects on shrub litter lignin loss and that reduced snow cover during winter warming would inhibit shrub lignin degradation in this alpine forest.     

Impacts of fire severity and post-fire reforestation on carbon pools in boreal larch forests in Northeast China

Aims Boreal larch (Larix gmelinii) forests in Northeast China have been widely disturbed since the 1987 conflagration; however, its long-term effects on the forest carbon (C) cycling have not been explored. The objective of this study thus was to quantify the effects of fire severity and post-fire reforestation on C pools and the changes of these forests.Methods Sixteen permanent plots have been set in two types of larch stands (L. gmelinii -grass, LG; and L. gmelinii-Rhododendron dahurica, LR) with three levels of fire severity (unburned, low-severity and high-severity but replanted), at 1987 burned sites in Daxing'anling, northeastern China, to repeatedly measure ecosystem C pools in 1998 and 2014. C components were partitioned into vegetation (foliage, branch, stem and roots), soil and detritus (standing and fallen woody debris and litter). The fire effects on post-fire C dynamics were examined by comparing the differences of C pools and changes between the two field investigations caused by fire severity.Important findings During the study period, unburned mature stands were C sinks (105g C m ?2 year^-1 for LG, and 190g C m ?2 year^-1 for LR), whereas the low-severity stands were C-neutral (?4 and 15g C m ?2 year^-1 for LG and LR, respectively). The high-severity burned but reforested stands were C sinks, among which, however, magnitudes (88 and 16g C m ?2 year^-1 for LG and LR, respectively) were smaller than those of the two unburned stands. Detritus C pools decreased significantly (with a loss ranging from 26 to 38g C m ?2 year^-1) in the burned stands during recent restoration. Soil organic C pools increased slightly in the unmanaged stands (unburned and low-severity, with accumulation rates ranging from 4 to 35g C m ?2 year^-1), but decreased for the high-severity replanted stands (loss rates of 28 and 36g C m ?2 year^-1 for LG and LR, respectively). These results indicate that fire severity has a dynamic post-fire effect on both C pools and distributions of the boreal larch forests, and that effective reforestation practice accelerates forest C sequestration.     

冬季雪被对青藏高原东缘高海拔森林凋落叶P元素释放的影响

雪被是影响高海拔森林凋落物分解的重要生态因子,其是否影响到生长季节与非生长季节凋落物中的P元素释放,尚未量化。为了量化季节性雪被对高海拔森林凋落物分解过程中P元素释放的影响,于2010年10月至2012年10月间,在青藏高原东缘川西高海拔森林不同厚度冬季雪被斑块下,设置凋落物分解袋实验。检测该地区代表性树种岷江冷杉(Abies faxoniana)、红桦(Betula albo-sinensis)、四川红杉(Larix mastersiana)和方枝柏(Sabina saltuaria)凋落叶在雪被覆盖不同关键时期(雪被形成前期、完全覆盖期和消融期)以及生长季节的P元素动态。结果表明,凋落物质量与雪被厚度均显著影响了P元素的释放过程。雪被覆盖时期凋落物P元素释放率表现为有雪被覆盖大于无雪被覆盖,而生长季节中除岷江冷杉外的其他3种凋落物P元素释放率均为无雪被覆盖下最大。相对于无雪被覆盖斑块,冬季雪被的存在提供了保护绝缘层,促进凋落物P元素释放,提高了各物种冬季P元素释放贡献率。这些结果表明,全球变化情景下的雪被减少可能减缓高海拔森林凋落物P元素的释放过程,改变森林土壤P元素水平。所以在研究高寒、高海拔地区全球气候变化下生态系统功能的工作中,应注重雪被这一异质性环境因子对生态系统功能的影响。     

6种温带森林凋落量年际及年内动态

森林凋落物量及其组分因生态系统结构特征和环境变化而表现出明显的时间动态,从而影响森林生态系统物质循环和生态服务功能。连续6年观测帽儿山地区6种温带森林凋落物量及组份的时间动态、温度和降雨量等气象因子,旨在深入了解该地区森林生态系统的物质循环过程及调控因子。结果表明:6种森林的年落凋落量差异显著,平均值依次为:蒙古栎林(4.60 t/hm~2)﹥杂木林(4.21 t/hm~2)﹥硬阔叶林(4.03 t/hm~2)﹥红松林(3.95 t/hm~2)﹥杨桦林(3.89 t/hm~2)﹥落叶松林(3.85 t/hm~2)。各森林年凋落量的年际变化表现为"升高-降低"交替波动模式,但总体上呈上升趋势。凋落物各组份的年际变化不同,枝凋落量变化较为稳定;叶凋落量与凋落总量一致,升高-降低波动明显;繁殖器官及其他凋落量随林龄增加而增加。各森林凋落物量的年内变化呈单峰曲线波动,最大值出现时间因林型而异。枝凋落量在年内表现为双峰曲线模式波动;叶凋落量年内呈单峰曲线模式波动,并与凋落总量年内动态一致;繁殖器官与其他凋落量年内动态波动平缓,无明显凋落峰值。降雨量显著影响年凋落物量(P0.05),分别解释了凋落总量、叶凋落量90%、87%变化。平均温度、积温和总降雨量显著影响凋落量年内动态,总降雨量的影响作用最为突出。因此,除林分自身的生物学特性外,降雨是影响该温带森林凋落量年内、年际动态的重要因素。     

不同经营模式茶园土壤微生物熵对台风干扰的响应

台风干扰可能显著影响我国东南沿海山地茶园土壤有机碳稳定性和矿化过程,而土壤微生物熵（qMB）是指示土壤有机碳稳定性和矿化潜力的敏感指标。因此,研究不同经营模式茶园土壤微生物熵对台风干扰的响应,可为山地茶园土壤碳库管理提供重要科学依据。为此,以浙江省台州市天台县苍山顶传统化肥经营的纯茶园（M0）、林茶间作（M1）、茶园养鸡（M2）、施用微生物肥料的纯茶园（M3）四种经营模式茶园为研究对象,在2021年7月28日台风"烟花"（第6号台风）来临前一天（T1）、台风过境后一天（T2）和台风过境后7天（T3）,按照表层土壤（0-10 cm）和亚表层土壤（10-30 cm）采集四种经营模式的茶园土样,同步测定土壤有机碳（SOC）含量、微生物生物量碳（MBC）和可溶性有机碳（DOC）含量。结果表明：（1）台风干扰对M2和M3的土壤有机碳影响更显著,而且不同经营模式茶园中表层和亚表层的土壤有机碳含量对台风干扰的响应存在差异;（2）台风干扰对M2的土壤微生物熵影响更显著,对表层土壤的微生物熵影响更显著,说明台风干扰对M2土壤有机碳稳定性和矿化影响显著,M2的土壤微生物熵对台风干扰的响应显著;（3）台风干扰对M2的土壤微生物生物量碳影响最显著,对M0和M1的影响最弱,且不同经营模式茶园中不同土层的土壤微生物生物量碳对台风干扰的响应存在差异;（4）台风干扰对M0的土壤可溶性有机碳含量影响更显著,M1和M3次之,对M2的影响最弱。而且不同经营模式茶园中表层和亚表层土壤的可溶性有机碳含量对台风干扰的响应存在差异。综上,台风干扰会对不同经营模式茶园土壤微生物熵影响程度不同,说明台风干扰对不同经营模式茶园土壤有机碳稳定性具有不同程度的影响,其中M2的土壤有机碳是响应台风干扰最敏感的经营模式茶园。     

Influence of the Aptamer Grafting on its Conformation and its Interaction with Targeted Protein

Plasmonics - Aptamers are functional small single-strand oligonucleotides (DNA) that show high affinity to their target molecules such as proteins or small analytes through the formation of...