中国新记录属——乌菌蚊属及一新种记述（双翅目：扁角菌蚊科）

报道中国扁角菌蚊科1新记录属——乌菌蚊属Urytalpa Edwards,1929,并记述1新种：簇毛乌菌蚊U.bartata Caoet Zhou,sp．nov．,模式标本保存在浙江林学院昆虫标本室。 簇毛乌菌蚊Urytalpa barbata Caoel Zhou,新种（图1～4） 雄：体长4．1mm,翅长3．4mm。 本新种与分布于日本的U.crassicauda Uesugi,2004相似,但新种C脉略超过R5脉端至M1脉端距离之半,而U.crassicauda的C脉仅略超过R5脉端;新种Sc脉未达Rs脉基部,而U.crassicauda的Sc脉远超过Rs脉基部。另外,新种第8腹板端部中央有1卵圆形毛斑及第9背板端两侧各具1伸向腹面的长突起等特征也与该属内其它种有显著差异。 正模：♂,浙江泰顺乌岩岭,2005-V-27,王义平采自马氏诱捕器。副模：1♂,浙江庆元百山祖,1994-Ⅳ-21,吴鸿采;1♂,贵州江口梵净山,1988-Ⅴ-15,王象贤采。词源：新种学名意指其第8腹板端部中间着1簇紧密刚毛。     

典型滨岸草地生态系统碳稳定同位素组成及分布特征

通过测定上海市青浦区东风港百慕大、白花三叶草、高羊茅和白茅等4种典型滨岸草本植物各组织以及不同垂直深度土壤有机质δ¹³C值,对滨岸草地生态系统的植物-土壤碳稳定同位素特征进行了分析.结果表明: 白花三叶草、高羊茅属于C3植物,百慕大、白茅属于C4植物,其茎叶、凋落物和根系各组织间δ¹³C值无显著差异.C3和C4植物样带表层土壤有机质δ¹³C值随着土壤深度递增而呈现截然不同的变化特征,这与样带本底δ¹³C值以及碳稳定同位素分馏效应有关,同时还受植物根系分布深度的影响.植物输入是土壤有机碳(SOC)的最主要来源,植物有机体δ¹³C组成对土壤有机质δ¹³C值有直接影响,植物各组分δ¹³C值与土壤有机质δ¹³C值均存在极显著相关.4种草本植物样带SOC含量与δ¹³C值均呈极显著相关,其中,C3植物样带SOC含量与δ¹³C值呈线性负相关,C4植物样带SOC含量与δ¹³C值呈线性正相关.     

采用稳定碳同位素法分析白羊草在不同干旱胁迫下的水分利用效率

本研究以黄土高原乡土草种白羊草(Bothriochloa ischaemum(L.)Keng.)为研究对象,采用盆栽控制实验,比较白羊草在3个水分处理(CK80%FC、MS60%FC和SS 40%FC)下的生物量积累和分配模式、瞬时水分利用效率(WUE)、不同部位(新叶、老叶、茎、细根、粗根)的稳定碳同位素组成(δ~(13)C)和碳同位素分辨率(Δ~(13)C)及其相互关系,以及干旱胁迫下影响水分利用效率的主导环境因子。结果表明:1)重度干旱胁迫显著降低植物整体生物量,显著增加根冠比和细根生物量比例;2)随着干旱胁迫加剧,白羊草各器官的δ~(13)C均呈上升趋势,Δ~(13)C呈减小趋势,SS处理不同器官δ~(13)C和Δ~(13)C没有显著差异,CK和MS处理的各器官δ~(13)C均值表现分别为细根粗根老叶新叶茎、细根新叶老叶粗根茎,CK和MS处理Δ~(13)C的值总体呈根叶茎。3)新叶的δ~(13)CNL和Δ~(13)CNL与WUE的相关系数均最大,说明利用稳定碳同位素方法测定白羊草水分利用效率具有可行性。4)不同水分处理的WUE的主导影响因子不同,CK、MS、SS水分处理WUE分别受到叶面温度、大气水汽压亏缺和空气温度的影响最大。为采用稳定碳同位素方法指示白羊草水分利用效率可行性及阐明植物的胁迫响应机制提供理论依据。     

Microtubule‐organizing centers of Aspergillus nidulans are anchored at septa by a disordered protein

Microtubule‐organizing centers (MTOCs) are large, multi‐subunit protein complexes. Schizosaccharomyces pombe harbors MTOCs at spindle pole bodies, transient MTOCs in the division plane (eMTOCs) and nuclear‐envelope associated MTOCs in interphase cells (iMTOCs). In the filamentous fungus Aspergillus nidulans SPBs and septum‐associated MTOCs were described. Although comparable to S. pombe eMTOCs, A. nidulans sMTOCS are permanent septum‐associated structures. The composition of sMTOCs is poorly understood and how they are targeted to septa was unknown. Here, we show that in A. nidulans several SPB outer plaque proteins also locate to sMTOCs while other SPB proteins do not, including SfiA, a protein required for SPB duplication in Saccharomyces cerevisiae and S. pombe and PcpA, the anchor for γ‐TuSCs at the SPB inner plaque. The A. nidulans disordered protein Spa18^Mto2 and the centrosomin‐domain containing protein ApsB^Mto1 were required for recruiting the γ‐TuRC component GcpC to sMTOCs and for seeding MT formation from septa. Testing different septum‐associated proteins for a role in sMTOC function, Spa10 was identified. It forms a septal pore disc structure, recruits Spa18 and ApsB to septa and is required for sMTOC activity. This is the first evidence for a septum‐specific protein, Spa10, as anchor for a specific class of MTOCs.     

Importance of mixotrophic bacterivory can be predicted by light and loss rates

Recent observational studies form oligotrophic waters provide ample evidence that mixotrophic flagellates often account for the bulk of bacterivory. However, we lack a general framework that allows a mechanistic understanding of success of mixotrophs in the competition with heterotrophic bacterivores. This is especially needed for integrating mixotrophy in models of the microbial loop. Based on general tradeoffs linked to the combined resource use in mixotrophs (generalist versus specialist), we propose a concept where mixotrophs are favored by conditions of high light – low losses, corresponding to the situation found in the surface waters of oligotrophic oceans. Under such conditions, they can achieve positive net growth at very low resource levels, allowing simultaneous competition with specialized protists. Conversely, heterotrophic bacterivores and photoautotrophs should be especially favored in more productive and low‐light conditions. We show experimentally that the combined effect of light and loss rates (dilution) predicts the success of mixotrophic bacterivorous flagellates. Moreover, our results suggest that total bacterivory, contrary as seen in the traditional microbial loop concept, has a more intricate coupling to light.     

Teruelia diezii gen. et sp. nov.: an early polysporangiophyte from the Lower Devonian of the Iberian Peninsula

A new basal land plant, Teruelia diezii gen. et sp. nov., is described from the shallow‐water marine deposits of the Lower Devonian (Lochkovian–Pragian) Nogueras Formation of the Iberian Peninsula (north Gondwana palaeocontinent). Teruelia is preserved as a compression fossil and consists of isotomously branched, robust stems terminated in large, fusiform, twisted sporangia. This morphology suggests that Teruelia is very probably equivalent to Aglaophyton, a permineralized early polysporangiophyte known up to now only from the Lower Devonian (early Pragian to ?earliest Emsian) Rhynie Chert in Scotland (Laurussia palaeocontinent), which represents an early terrestrial hot‐spring ecosystem. Accepted phylogenies identify Aglaophyton as sister to vascular plants. Our phylogeny‐based results identify the Aglaophyton/Teruelia biological entity (i.e. Aglaophyton anatomical characters plus Teruelia external morphology) as the most direct vascular plant precursor. It shows that at least one Rhynie Chert type plant had a much wider distribution than previously known and suggests that Aglaophyton was not restricted to hydrothermal environments, unlike other Rhynie Chert plants.     

Golden bananas in the field: elevated fruit pro‐vitamin A from the expression of a single banana transgene

Vitamin A deficiency remains one of the world's major public health problems despite food fortification and supplements strategies. Biofortification of staple crops with enhanced levels of pro‐vitamin A (PVA) offers a sustainable alternative strategy to both food fortification and supplementation. As a proof of concept, PVA‐biofortified transgenic Cavendish bananas were generated and field trialed in Australia with the aim of achieving a target level of 20 μg/g of dry weight (dw) β‐carotene equivalent (β‐CE) in the fruit. Expression of a Fe'i banana‐derived phytoene synthase 2a (MtPsy2a) gene resulted in the generation of lines with PVA levels exceeding the target level with one line reaching 55 μg/g dw β‐CE . Expression of the maize phytoene synthase 1 (ZmPsy1) gene, used to develop ‘Golden Rice 2’, also resulted in increased fruit PVA levels although many lines displayed undesirable phenotypes. Constitutive expression of either transgene with the maize polyubiquitin promoter increased PVA accumulation from the earliest stage of fruit development. In contrast, PVA accumulation was restricted to the late stages of fruit development when either the banana 1‐aminocyclopropane‐1‐carboxylate oxidase or the expansin 1 promoters were used to drive the same transgenes. Wild‐type plants with the longest fruit development time had also the highest fruit PVA concentrations. The results from this study suggest that early activation of the rate‐limiting enzyme in the carotenoid biosynthetic pathway and extended fruit maturation time are essential factors to achieve optimal PVA concentrations in banana fruit.     

Physiological and molecular mechanisms underlying the integration of light and temperature cues in Arabidopsis thaliana seeds

The relief of dormancy and the promotion of seed germination are of extreme importance for a successful seedling establishment. Although alternating temperatures and light are signals promoting the relief of seed dormancy, the underlying mechanisms of their interaction in seeds are scarcely known. By exposing imbibed Arabidopsis thaliana dormant seeds to two‐day temperature cycles previous of a red light pulse, we demonstrate that the germination mediated by phytochrome B requires the presence of functional PSEUDO‐RESPONSE REGULATOR 7 (PRR7) and TIMING OF CAB EXPRESSION 1 (TOC1) alleles. In addition, daily cycles of alternating temperatures in darkness reduce the protein levels of DELAY OF GERMINATION 1 (DOG1), allowing the expression of TOC1 to induce seed germination. Our results suggest a functional role for some components of the circadian clock related with the action of DOG1 for the integration of alternating temperatures and light signals in the relief of seed dormancy. The synchronization of germination by the synergic action of light and temperature through the activity of circadian clock might have ecological and adaptive consequences.     

Restoration of cutaneous pigmentation by transplantation to mice of isogeneic human melanocytes in dermal–epidermal engineered skin substitutes

Autologous engineered skin substitutes (ESS) containing melanocytes (hM) may restore pigmentation and photoprotection after grafting to full‐thickness skin wounds. In this study, normal hM were isolated from discard skin, propagated with or without tyrosinase inhibitors, cryopreserved, recovered into culture, and added to ESS (ESS‐P) before transplantation. ESS‐P were incubated in either UCMC160/161 or UCDM1 medium, scored for hM densities, and grafted to mice. The results showed that sufficient hM can be propagated to expand donor tissue by 100‐fold; incubation of hM in tyrosinase inhibitors reduced pigment levels but did not change hM recovery after cryopreservation; hM densities in ESS‐P were greater after incubation in UCDM1 than UCMC160 medium; hM were localized to the dermal–epidermal junction of ESS‐P; and UCDM1 medium promoted earlier pigment distribution and density. These results indicate that hM can be incorporated into ESS‐P efficiently to restore cutaneous pigmentation and UV photoprotection after full‐thickness skin loss conditions.