Dynamic optimization of odor representations by slow temporal patterning of mitral cell activity

Mitral cells (MCs) in the olfactory bulb (OB) respond to odors with slow temporal firing patterns. The representation of each odor by activity patterns across the MC population thus changes continuously throughout a stimulus, in an odor-specific manner. In the zebrafish OB, we found that this distributed temporal patterning progressively reduced the similarity between ensemble representations of related odors, thereby making each odor's representation more specific over time. The tuning of individual MCs was not sharpened during this process. Hence, the individual responses of MCs did not become more specific, but the odor-coding MC assemblies changed such that their overlap decreased. This optimization of ensemble representations did not occur among olfactory afferents but resulted from OB circuit dynamics. Time can therefore gradually optimize stimulus representations in a sensory network.     

The role of Drosophila mushroom body signaling in olfactory memory

The mushroom bodies of the Drosophila brain are important for olfactory learning and memory. To investigate the requirement for mushroom body signaling during the different phases of memory processing, we transiently inactivated neurotransmission through this region of the brain by expressing a temperature-sensitive allele of the shibire dynamin guanosine triphosphatase, which is required for synaptic transmission. Inactivation of mushroom body signaling through alpha/beta neurons during different phases of memory processing revealed a requirement for mushroom body signaling during memory retrieval, but not during acquisition or consolidation.     

外界环境对香菇菌丝体生长的影响

试验表明,香菇菌丝体在多种培养基上均能正常生长,其中尤以在玉米-棉子壳综合培养基或马铃薯综合培养基上生长较优;最佳生长温度为25℃,最适pH值为5.5～6.5;适宜碳源为麦芽糖或甘露醇;适宜氮源为牛肉膏或蛋白胨.     

白蜡多年卧孔菌生物学特性及驯化栽培

白蜡多年卧孔菌生于白蜡树、檫木、杨树、柳树等阔叶腐木上,造成白色腐朽,药用具有抑肿瘤功效。该菌在山东省广泛分布。对采自山东省的子实体进行组织分离获取菌株作为实验材料对其生物学特性和驯化栽培进行研究,得出最佳的菌丝生长条件和子实体出菇培养条件。生物学特性研究中,首先对温度、pH值、碳源、氮源4个因素进行单因素实验。温度组选取15、20、25、30、35℃ 5个梯度,pH值组选取pH值4、5、6、7、8等5个梯度,碳源组选取葡萄糖、蔗糖、麦芽糖、可溶性淀粉、乳糖、果糖6种,氮源组选取酵母膏、蛋白胨、硫酸铵、牛肉膏、黄豆粉、亚硝酸钠6种,进行单因素实验。根据菌丝在培养皿中的日均生长速度和生长势综合比较,分别选取4个因素中最优的3个,温度组选取20℃、25℃、30℃ 3个;pH值组选取pH值 5、6、7等3个;碳源组选取麦芽糖、可溶性淀粉、果糖3个;氮源组选取酵母膏、蛋白胨、牛肉膏3个。然后通过四因素三水平的正交试验,得出如下结论:4种因子对白蜡多年卧孔菌的影响程度为:温度>pH值>碳源>氮源,各因素之间呈极显著差异,最终得出该菌菌丝生长的最佳培养条件为温度30℃,pH值为6,碳源为麦芽糖,氮源为酵母膏。出菇试验中,对驯化栽培过程按二级种制作、栽培袋制作、发菌、催蕾、出菇期管理、采收6个步骤进行实验。二级种选用液体菌种,其配方:每1000 mL 的培养基成分为葡萄糖20 g、蛋白胨6 g、酵母膏5 g、 MgSO₄ 1 g、KH₂PO₄ 2 g。培养条件温度25℃、摇床转速150 r/min,待培养6 d后使用。出菇栽培采用棉籽壳、麸皮、石灰为主要原料,按棉籽壳79%、麦麸20%、石灰粉1%的配比进行出菇实验,每袋接种量5 mL。发菌阶段需要在清洁的环境中进行,以防止杂菌的污染。白蜡多年卧孔菌菌丝最佳培养温度为30℃,需要通风、避光。出菇时需要14-16℃的低温刺激。子实体生长温度为21-27℃,空气湿度80%-90%。需要一定的散射光光照。当出现乳白色子实层且子实体不再生长时可以进行采收,子实体形态和野生形态相同。     

金针菇栽培原料与菌渣中营养成分的变化分析

对金针菇栽培原料及菌渣中的主要营养成分进行检测,以充分再利用菌渣。结果显示,与栽培原料相比,金针菇菌渣中仅粗脂肪含量变化不显著;粗纤维、有机C和木质素含量均不同程度下降,其中木质素下降43.24%,差异达到极显著水平;而粗蛋白、总N、灰分、P含量明显升高,其中灰分增加幅度最大,为41.33%。金针菇菌渣C/N为28.75∶1,仍适合部分食用菌的二次栽培;粗蛋白与总N、有机C与粗纤维的相关系数分别为1.000和0.945,为极显著或显著相关。根据该相关关系,通过测定粗蛋白、粗纤维含量,即可估算总N和有机C含量,进而估算菌渣C/N。     

Cleptoparasitism and odor mimetism in bees: do nomada males imitate the odor of andrena females?

Identical chemical compounds are present in the Dufour gland secretion of female Andrena bees and in the cephalic secretion of many male Nomada bees. Females of Nomada parasitize the nests of Andrena. Many Nomada species confine their attacks to a single host species. In two such host-parasite pairs, Andrena haemorrhoa-Nomada bifida and Andrena carantonica-Nomada marshamella, all-trans farnesyl hexanoate was found to be the totally dominant component in respective secretions. In two other pairs, Andrena helvola-Nomada panzeri and Andrena clarkella-Nomada leucophthalma, geranyl octanoate is the major component. This pairwise odor correspondence is discussed in relation to critical points of contact in the life cycles of host and parasite, male and female.     

凤眼莲栽培草菇平菇试验

南方水域特别是珠江三角洲地区历来都是凤眼莲爆发的重灾区,如何使得凤眼莲变废为宝袁合理资源化利用成为目前解决凤眼莲爆发后的重要问题。试验以经过机械破碎处理并晒干后的凤眼莲为原料,按一定比例加入培养料中分别栽培草菇、平菇。试验结果表明,凤眼莲添加量为48%和35.59%栽培的草菇、平菇子实体生长正常,生物转化率分别为14.4%、76.3%,其产品主要重金属含量均符合国家食用菌卫生标准,可用于食用菌生产栽培。     

双孢蘑菇基质中的线虫在菌丝上的数量扩增及对菌丝生长的影响

研究双孢蘑菇生产基质中的线虫优势类群在木耳和双孢蘑菇菌丝上的数量扩增及对菌丝生长的影响.结果表明:1)从浙江苍南县双孢蘑菇基质中分离出的线虫隶属于19个属,其中拟丽突属(Acrobeloides sp.)、中杆属(Mesorhabditis sp.)和滑刃属(堆肥滑刃线虫Aphelenchoides composticola Franklin)线虫为优势线虫.2)分别在长满木耳和双孢蘑菇菌丝的试管中接种3种线虫150条,1周内,菌丝未见明显变化,线虫数量增加幅度在4.5倍以下(双孢蘑菇菌丝上的中杆属线虫除外,其增幅近接种量的27倍);2周以后,菌丝有不同程度的过早变褐、萎缩.3)在木耳菌丝上,接种3种线虫2～3周后,数量增幅一般为10倍左右.在双孢蘑菇菌丝上,接种2周后,拟丽突属、中杆属和滑刃属线虫的数量增幅分别为19.4,42.3和11.1倍;接种后3周,拟丽突属和中杆属线虫的增幅近60倍,滑刃属线虫的数量增幅近10倍.由此初步认为:基质中拟丽突、中杆和堆肥滑刃线虫的密度在10条·cm-2以下时,1周内,生长的木耳和双孢蘑菇菌丝无感官异常,2周后,对2种食用菌菌丝生长有危害.     

昆虫向化学气味源定向的机制

昆虫向气味源定向机制的研究有助于深入理解环境中化学气味对昆虫的引诱过程,央化学生态学研究及高效诱捕器的设计和利用上有重要意文。本文介绍有关的研究进展情况，包括视动趋风性、CNS偏转发生器、飞行不精确模型、化趋性模型、相位补偿模型等内容。     

利用作物副产品栽培杏鲍菇试验初报

用棉籽壳、稻草、玉米芯、葵花壳等几种作物副产品为原料,均辅以糠、菜园土、石灰、复合肥进行杏鲍菇栽培试验。结果表明,培养料不同对杏鲍菇的产量及质量影响较大,各培养原料之间产量差异显著。其中棉籽壳和玉米芯是较为理想的培养料,生物转化率可达90%,而稻草和葵花壳原料生物转化率低,其配方有待改进。     

基因组改组及其在食用菌育种上的应用前景

介绍了基因组改组技术的发展历程、技术特点及应用情况,分析限制该技术广泛运用的因素,同时对该技术在食用菌育种上的可行性进行初步探讨,展望该技术在食用菌育种上的应用前景。     

Overtones of Free Oscillations and the Structure of the Earth's Interior

Identification of 82 percent of all possible spheroidal overtones with greater than 300 seconds increases the resolving power of the set of gross searth data. Results of inversion indicate a change of composition in the deepest 500 kilometers of the mantle. The assumption that the inner core is rigid is required to satisfy simultaneously the data on free oscillations and travel times.     

Source and possible nature of the odor trail of fire ants

Experimental evidence shows that the odor trail of the fire ant Solenopsis saevissima (Fr. Smith) is produced as a secretion of the accessory gland of the poison apparatus and released through the extruded sting. Preliminary studies suggest that this substance may be chemically allied to or even identical with the toxic principle of the venom.     

柚果皮油特征香气成分的分析

采用溶剂萃取法提取柚果的精油，并用硅胶柱将精油分成碳氢化合物和含氧化合物两大部分。利用各成分的香气值对具有柚果皮特征香气的含氧化合物部分进行了分析，结果表明沉香醇、(E)—2—癸烯醛、(E，E)-2，4—癸二烯醛、(E)—2—十二烯醛、百里香以及一些饱和脂肪族醛等14种成分是形成柚果皮香气的重要香气成分。     

秀珍菇栽培管理技术

为推进基层农技推广体系改革与建设示范县项目进程．宁河县紧紧围绕优势农产品和特色产业发展需要,依托试验示范基地,积极引进食用茵新品种——秀珍菇,并在潘庄镇齐心蔬菜种植园区示范成功,填补了天津市特种食用菌规模化生产的空白。文章主要介绍了秀珍菇的生长特性及栽培技术。