神农架地区常绿落叶阔叶混交林树种更新研究

神农架山区山体的中部,选取代表性的常绿落叶阎叶混交林样地,总面积为２．４ｈｍ＾２。在样地中对出现的林窗斑块以及相邻的对照的非林窗宙样方进行群落学调查。记录乔木树种的种类、胸径和高度以及它的幼苗和幼树的高度、数量。按照树种在林宙内外重要值的位序差值将群落出现的乔木层树种划分为４类生态种组,其中,对林窗强烈正更新反应的树种有６种,强烈负更新反应的树种９种,中等更新反应的９种,不明显更新反应的１０种。林窗内外乔木树种生态种组的组成明显不同。不同生态种组树种的幼苗在林宙与非林窗斑块中的更新表现出显著的差别。对神农架地区常绿落叶阎叶混交林树种更新的反应和过程的研究结果支持了林窗—分享假说的观点。     

Different fates of deposited and in a temperate forest in northeast China: a 15N tracer study

Increasing atmospheric reactive nitrogen (N) deposition due to human activities could change N cycling in terrestrial ecosystems. However, the differences between the fates of deposited and are still not fully understood. Here, we investigated the fates of deposited and , respectively, via the application of ¹⁵NH₄NO₃ and NH₄¹⁵NO₃ in a temperate forest ecosystem. Results showed that at 410 days after tracer application, most was immobilized in litter layer (50 ± 2%), while a considerable amount of penetrated into 0–5 cm mineral soil (42 ± 2%), indicating that litter layer and 0–5 cm mineral soil were the major N sinks of and , respectively. Broad‐leaved trees assimilated more ¹⁵N under NH₄¹⁵NO₃ treatment compared to under ¹⁵NH₄NO₃ treatment, indicating their preference for –N. At 410 days after tracer application, 16 ± 4% added ¹⁵N was found in aboveground biomass under treatment, which was twice more than that under treatment (6 ± 1%). At the same time, approximately 80% added ¹⁵N was recovered in soil and plants under both treatments, which suggested that this forest had high potential for retention of deposited N. These results provided evidence that there were great differences between the fates of deposited and , which could help us better understand the mechanisms and capability of forest ecosystems as a sink of reactive nitrogen.     

沈抚灌区广宿主石油烃代谢质粒的分离及鉴定

本研究采用“三亲配对外源分离法”,从沈抚灌区土壤、底泥和水样中共计分离得到8个广宿主（BHR）石油烃代谢质粒,并通过对其进行抗生素抗性检测和抗性遗传标记,将其转移至大肠杆菌(Escherichia coli)EC100宿主中进行操作.不相容性群分析结果表明: pS3-2C、pS4-6G为Inc P质粒;pS3-2G、pW22-3G、pA15-7G为Inc N质粒;pS7-2G 为Inc W质粒;pA23-1G和 pA10-1C为Inc Q质粒.采用PCR扩增已报道的石油烃污染物降解基因的方法初步分析其石油烃代谢功能,质粒pS3-2G、pS7-2G、pA23-1G、pW22-3G和pA10-1C上含有编码芳香环羟化双加氧酶基因(phdA)和甲苯单加氧酶基因(touA)的片段;pA15-7G含有编码甲苯双加氧酶和甲苯单加氧酶基因片段;pS3-2C含有编码芳香环羟化双加氧酶、苯双加氧酶和甲苯双加氧酶基因片段;pS4-6G仅含有编码芳香环羟化双加氧酶基因片段.通过宿主范围检测,除质粒pS3-2C外,其余7个质粒均可在变形菌纲(Proteobacteria)α-、β-、γ-亚纲的代表性菌株根瘤农杆菌(Agrobacterium tumefaciens)C58、钩虫贪铜菌(Cupriavidus necator)JMP228、大肠杆菌EC100间进行转移并稳定传代.     

A comparative calorimetric study of the effects of cholesterol and the plant sterols campesterol and brassicasterol on the thermotropic phase behavior of dipalmitoylphosphatidylcholine bilayer membranes

We present a comparative differential scanning calorimetric study of the effects of the animal sterol cholesterol (Chol) and the plant sterols campesterol (Camp) and brassicasterol (Bras) on the thermotropic phase behavior of dipalmitoylphosphatidylcholine (DPPC) bilayers. Camp and Bras differ from Chol in having a C24 methyl group and, additionally for Bras, a C22 trans-double bond. Camp and especially Bras decrease the temperature, cooperativity and enthalpy of the DPPC pretransition more than Chol, although these effects are attenuated at higher sterol levels. This indicates that they destabilize gel-state DPPC bilayers to a greater extent, but are less soluble, than Chol. Not surprisingly, all three sterols have similar effects on the sterol-poor sharp component of the DPPC main phase transition. However, Camp and especially Bras less effectively increase the temperature and decrease the cooperativity and enthalpy of the broad component of the main transition than Chol. This indicates that at higher sterol concentrations, Camp and Bras are less miscible and less effective than Chol at ordering the hydrocarbon chains of the sterol-enriched fluid DPPC bilayers. Overall, these alkyl side chain modifications generally reduce the ability of Chol to produce its characteristic effects on DPPC bilayer physical properties. These differences are likely due to the less extended and more bent conformations of the alkyl side chains of Camp and Bras, producing sterols with a greater effective cross-sectional area and reduced length than Chol. Hence, the structure of Chol is likely optimized for maximum solubility in, as opposed to maximum ordering of, phospholipid bilayers.     

Biosynthesis of 3,4-dihydroxyphenylalanine in Vicia faba

Radioactive shikimic acid and l-tyrosine were shown to be efficient precursors of 3,4-dihydroxyphenylalanine (DOPA) in Vicia faba. [1-¹⁴C]Acetate and l[U-¹⁴C]phenylalanine were not incorporated into tyrosine or DOPA. Thus the synthesis of DOPA occurs via the shikimic acid pathway and tyrosine or a very closely related metabolise. Phenolase was present in etiolated plants in much larger quantities after a brief light exposure whereas DOPA concentration was relatively constant during all stages of plant growth. Partially purified phenolase did not catalyze the conversion of tyrosine to DOPA and does not appear to have a role in DOPA synthesis.     

Exogenous application of liquid diet,previously fed upon by pea aphids Acyrthosiphon pisum (Harris), to broad bean leaves induces volatiles attractive to the specialist parasitic wasp Aphidius ervi (Haliday)

Proof of the existence of aphid-derived molecules that induce emission of volatile organic compounds as indirect defensive responses in plants (hereafter called elicitors) has not yet been obtained. We showed here the presence and some aspects of the chemical nature of these elicitors. Exogenous application of the fed diet (liquid diet previously fed on by the Pea aphid, Acyrthosiphon pisum) on the damaged part of leaves of broad bean plants, made the plants more attractive to a parasitic wasp, Aphidius ervi, than application of the unfed diet. This result suggested that elicitors existed in the fed diet. Chemical characterization using ultrafiltration and subsequent bioassay revealed that the responsible factor was larger than 3 kDa. Heating of the fed diet did not inactivate its ability to induce attractive volatiles, which suggested thermotolerance of the elicitor. These results contribute to the mechanistic understanding of plant defenses against aphids.     

天童国家森林公园植被碳储量估算

以典型木荷-栲树群落、含苦槠的木荷-栲树群落、含杨梅叶蚊母树的木荷-栲树群落、披针叶茴香-南酸枣群落、枫香-马尾松群落、黄毛耳草-毛竹群落6种群落类型样地实测数据为基础,结合文献资料汇总,采用生物量相对生长方程法,研究了天童国家森林公园森林生态系统的植被碳储量、碳密度及其组分和空间分布特征.结果表明：野外调查的6种群落类型中,含苦槠的木荷-栲树群落碳储量（12113.92 Mg C）和碳密度（165.03 Mg C·hm^-2）均最高,披针叶茴香 南酸枣群落碳储量最低（680.95 Mg C）,其碳密度为101.26 Mg C·hm^-2.各群落类型中,常绿树种的碳储量均显著高于落叶树种,其碳密度范围分别为76.08～144.95和0.16～20.62 Mg C·hm^-2.各群落类型的乔木层各组分中,植株干的碳储量均最高.各林分类型中,常绿阔叶林碳储量最高,为23092.39 Mg C,占天童林区森林生态系统碳储量的81.7%,碳密度为126.17 Mg C·hm^-2.天童国家森林公园植被总碳储量为28254.22 Mg C,碳密度为96.73 Mg C·hm^-2.     

Multiple copies of eukaryotic translation initiation factors in Brassica rapa facilitate redundancy,enabling diversification through variation in splicing and broad‐spectrum virus resistance

Recessive strain‐specific resistance to a number of plant viruses in the Potyvirus genus has been found to be based on mutations in the eukaryotic translation initiation factor 4E (eIF4E) and its isoform, eIF(iso)4E. We identified three copies of eIF(iso)4E in a number of Brassica rapa lines. Here we report broad‐spectrum resistance to the potyvirus Turnip mosaic virus (TuMV) due to a natural mechanism based on the mis‐splicing of the eIF(iso)4E allele in some TuMV‐resistant B. rapa var. pekinensis lines. Of the splice variants, the most common results in a stop codon in intron 1 and a much truncated, non‐functional protein. The existence of multiple copies has enabled redundancy in the host plant's translational machinery, resulting in diversification and emergence of the resistance. Deployment of the resistance is complicated by the presence of multiple copies of the gene. Our data suggest that in the B. rapa subspecies trilocularis, TuMV appears to be able to use copies of eIF(iso)4E at two loci. Transformation of different copies of eIF(iso)4E from a resistant B. rapa line into an eIF(iso)4E knockout line of Arabidopsis thaliana proved misleading because it showed that, when expressed ectopically, TuMV could use multiple copies which was not the case in the resistant B. rapa line. The inability of TuMV to access multiple copies of eIF(iso)4E in B. rapa and the broad spectrum of the resistance suggest it may be durable.     

台风对小兴安岭阔叶红松林的影响

台风对森林造成强烈干扰,改变森林生态系统的结构与功能。分析了2020年台风对小兴安岭地区阔叶红松(Pinus koraiensis)林中不同径级、功能群(耐阴性、生活型、针阔叶)树木破坏程度的影响和地形(海拔、坡向、坡度、凹凸度)在其中的作用。结果表明:台风对不同径级以及不同功能群树种的受损数量的影响具有显著差异,具体表现为径级Ⅰ(胸径<10 cm)>径级Ⅱ(10 cm≤胸径<50 cm)>径级Ⅲ(胸径≥50 cm),耐阴性强>耐阴性弱、乔木>灌木、阔叶树种>针叶树种;而其受损率则表现为径级Ⅱ>径级Ⅲ>径级Ⅰ,耐阴性弱>耐阴性强、乔木>灌木、针叶树种>阔叶树种;损坏程度很大程度上取决于坡向与海拔位置,处于阴坡与低海拔的受损木数量较高,阔叶树种、灌木与耐阴性强的受损木表现出在阳坡与海拔较高位置出现的可能性更大,针叶树种、乔木与耐阴性弱的受损木表现出在阴坡与海拔较低位置出现的可能性更大,阴坡和较低海拔处拔根倒的受损数量显著高于干基折和干中折的受损数量;地形对受损木的风倒方向具有显著影响。总体而言,台风对森林的破坏受到多种环境因素和生物因素共同作用的影响,处于不同地形的不同径级、功能群的树木,其对台风的抵抗能力有所不同,且大径级树木、耐阴性弱的树种、乔木和针叶树种对台风的抵抗能力相对较弱,迎风坡与阴坡的树木对台风的抵抗能力相对较弱,这为理解极端天气事件对森林动态的影响以及恢复提供理论依据与参考。     

传统豆瓣酱微生物群落发酵演替规律及其功能分析

[目的]解析中国传统豆瓣酱发酵过程中的微生物群落演替规律和理化代谢物质变化,探讨不同发酵阶段影响豆瓣酱风味的核心功能微生物.[方法]采用高通量测序解析豆瓣酱发酵过程中的微生物群落结构和演替,并跟踪检测发酵过程中的理化代谢物质,然后分析微生物群落和理化代谢物质变化之间的相关性,最后在体外分离核心微生物并对其功能特性进行验...