Effects of seasonal precipitation change on soil respiration processes in a seasonally dry tropical forest

Precipitation is projected to change intensity and seasonal regime under current global projections. However, little is known about how seasonal precipitation changes will affect soil respiration, especially in seasonally dry tropical forests. In a seasonally dry tropical forest in South China, we conducted a precipitation manipulation experiment to simulate a delayed wet season (DW) and a wetter wet season (WW) over a three‐year period. In DW, we reduced 60% throughfall in April and May to delay the onset of the wet season and irrigated the same amount water into the plots in October and November to extend the end of the wet season. In WW, we irrigated 25% annual precipitation into plots in July and August. A control treatment (CT) receiving ambient precipitation was also established. Compared with CT, DW significantly increased soil moisture by 54% during October to November, and by 30% during December to April. The treatment of WW did not significantly affect monthly measured soil moisture. In 2015, DW significantly increased leaf area index and soil microbial biomass but decreased fine root biomass. In contrast, WW significantly decreased fine root biomass and forest floor litter stocks. Soil respiration was not affected by DW, which could be attributed to the increased microbial biomass offsetting the decrease in fine root biomass. In contrast, WW significantly increased soil respiration from 3.40 to 3.90 μmol m^?2 s^?1 in the third year, mainly due to the increased litter decomposition and soil pH (from 4.48 to 4.68). The present study suggests that both a delayed wet season and a wetter wet season will have significant impacts on soil respiration‐associated ecosystem components. However, the ecosystem components can respond in different directions to the same change in precipitation, which ultimately affected soil respiration.     

Expression of ALS‐linked TDP‐43 mutant in astrocytes causes non‐cell‐autonomous motor neuron death in rats

Mutation of Tar DNA‐binding protein 43 (TDP‐43) is linked to amyotrophic lateral sclerosis. Although astrocytes have important roles in neuron function and survival, their potential contribution to TDP‐43 pathogenesis is unclear. Here, we created novel lines of transgenic rats that express a mutant form of human TDP‐43 (M337V substitution) restricted to astrocytes. Selective expression of mutant TDP‐43 in astrocytes caused a progressive loss of motor neurons and the denervation atrophy of skeletal muscles, resulting in progressive paralysis. The spinal cord of transgenic rats also exhibited a progressive depletion of the astroglial glutamate transporters GLT‐1 and GLAST. Astrocytic expression of mutant TDP‐43 led to activation of astrocytes and microglia, with an induction of the neurotoxic factor Lcn2 in reactive astrocytes that was independent of TDP‐43 expression. These results indicate that mutant TDP‐43 in astrocytes is sufficient to cause non‐cell‐autonomous death of motor neurons. This motor neuron death likely involves deficiency in neuroprotective genes and induction of neurotoxic genes in astrocytes.     

桂花抗冻种质的筛选及抗冻机理初探

采用田间调查及人工模拟冰冻鉴定的方法,比较测定了4个桂花品种的抗冻性,其抗冻性强弱顺序为金桂（Osmanthusfragransvar．thunbergii）＞银桂（O．fragransvar.latifolius）＞丹桂（O．fragransvar．aurantiacus）＞四季桂（O．fragransvar.semperflorens）。筛选出5株抗冻性最强的单株,它们的致死温度都在－26℃左右。桂花叶片膜脂脂肪酸组成随季节呈周期性变化,随着气温下降亚麻酸（18∶3）含量增加而亚油酸（18∶2）含量降低。不同品种均表现出一致的变化趋势,抗性强的品种这种变化则更为显著。在自然脱锻炼过程中,叶面喷施脱落酸（200ppm）能使亚麻酸含量保持稳定,延缓桂花的脱锻炼。     

气候变暖可能对东北三省农业生态环境的影响及其对策

随着未来气候变暖,我国东北三省农业生态环境可能发生较大的变化,其变化趋势为,热量条件变好,作物生育期延长,冷害频率降低,积雪期缩短,湿润条件变差,干旱频率增大,蒸发量增加。未来气候变暖,若平均气温升高2℃,那时东北三省粮食产量可增加36%左右,农业地带将大幅度地向北推移,并且提出相应的农业对策。     

应用PCR重组技术构建大肠杆菌分泌型表达载体

应用ＰＣＲ重组技术,对大肠杆菌分泌型表达载体ｐＩＮ－ⅢｏｍｐＡ进行改建,除去原载体的ＨｉｎｄⅢ位点,将信号肽序列末端两个密码子ＣＡＧＧＣＣ改为ＣＡＡＧＣＴ,从而引入一个新的ＨｉｎｄⅢ位点,并在其下游接上一段多克隆位点序列。改建后的载体可用于直接插入外源ＤＮＡ编码序列,表达产物在分泌过程中被切除信号肽而成为天然有活性的蛋白质,操作十分简便。     

Antioxidant and immunological activities of water-soluble polysaccharides from Aconitum kusnezoffii Reichb

Aconitum kusnezoffii Reichb., one of the earliest recorded toxic species of genus Aconitum, has been used as traditional Chinese medicine and medicinal diet over the last 2500 years to treat heart failure congestion, neuralgia, rheumatism and gout, etc. In the present paper, four water-soluble polysaccharide fractions isolated from the tubers of A. kusnezoffii Reichb. were studied the antioxidant and immunological activities for the first time. In vitro antioxidant assays indicated that fraction WKCP-A had noticeable scavenging activities on DPPH radical, hydroxyl radical, superoxide anion, H₂O₂ and self-oxidation of 1,2,3-phentriol, ferrous ion-chelating ability and reducing power. Moreover, the in vivo immunological assay exhibited that fractions WKCP-A and WKHP could more significantly enhance splenic lymphocyte proliferation and macrophage phagocytosis than other fractions. Therefore, the water-soluble polysaccharides from A. kusnezoffii Reichb., especially WKCP-A, have the potential to be explored as novel natural antioxidants and immunostimulating agents for using in functional foods or medicine.     

Utilization of dry distiller’s grain and solubles as nutrient supplement in the simultaneous saccharification and ethanol fermentation at high solids loading of corn stover

Dry distiller’s grain and solubles (DDGS) is a major by-product of corn-based ethanol production and is usually used as animal feed. Here, it was added to the simultaneous saccharification and ethanol fermentation (SSF) carried out at high solids loading of steam explosion pretreated corn stover using a mutant strain Saccharomyces cerevisiae DQ1. The performance of SSF process with DDGS was comparable to those using the expensive yeast extract supplementation. With 30% (w/w) solids plus the addition of cellulase and 1 g DDGS l⁻¹, the final ethanol reached 55 g l⁻¹ (7% v/v). The results indicated that the expensive supplement of yeast extract could be replaced by DDGS.     

胃饥饿素对小鼠急性肺损伤的保护作用及其机制研究

目的 探讨胃饥饿素对小鼠急性肺损伤的保护作用和机制.方法 将60只小鼠采用随机数字表法分为6组:对照组、模型组、胃饥饿素低、中、高剂量组和地塞米松组.对照组和模型组腹腔注射0.2 mL生理盐水,胃饥饿素各组分别注射400、200、100 μg/kg溶液,地塞米松组注射2 mg/kg.给药后1h,对照组滴注等体积生理盐水...     

LAMTOR1 inhibition of TRPML1‐dependent lysosomal calcium release regulates dendritic lysosome trafficking and hippocampal neuronal function

Lysosomes function not only as degradatory compartments but also as dynamic intracellular calcium ion stores. The transient receptor potential mucolipin 1 (TRPML1) channel mediates lysosomal Ca²⁺ release, thereby participating in multiple cellular functions. The pentameric Ragulator complex, which plays a critical role in the activation of mTORC1, is also involved in lysosomal trafficking and is anchored to lysosomes through its LAMTOR1 subunit. Here, we report that the Ragulator restricts lysosomal trafficking in dendrites of hippocampal neurons via LAMTOR1‐mediated tonic inhibition of TRPML1 activity, independently of mTORC1. LAMTOR1 directly interacts with TRPML1 through its N‐terminal domain. Eliminating this inhibition in hippocampal neurons by LAMTOR1 deletion or by disrupting LAMTOR1‐TRPML1 binding increases TRPML1‐mediated Ca²⁺ release and facilitates dendritic lysosomal trafficking powered by dynein. LAMTOR1 deletion in the hippocampal CA1 region of adult mice results in alterations in synaptic plasticity, and in impaired object‐recognition memory and contextual fear conditioning, due to TRPML1 activation. Mechanistically, changes in synaptic plasticity are associated with increased GluA1 dephosphorylation by calcineurin and lysosomal degradation. Thus, LAMTOR1‐mediated inhibition of TRPML1 is critical for regulating dendritic lysosomal motility, synaptic plasticity, and learning.     

硒对心肌质膜(Ca~(2+)·Mg~(2+))-ATPase和肌浆网Ca~(2+)-ATPase活力的影响

本文以豚鼠和大白鼠心肌肌浆网膜(SR)Ca~(2+)-ATPase的活力,心肌质膜(SL)(Ca~(2+)Mg~(2+))-ATPase的活力和电子显微镜的方法探索克山病病区粮中低硒与心肌细胞钙转运调控的共系,实验结果为硒对克山病有预防作用的观点提供了新的理论依据,并进一步支持了“克山病是一种心肌线粒体病”的观点。