Comment on "Tequila, a neurotrypsin ortholog, regulates long-term memory formation in Drosophila"

Didelot et al. (Reports, 11 August 2006, p. 851) claimed that Drosophila Tequila (Teq) and human neurotrypsin are orthologs and concluded that deficient long-term memory after Teq inactivation indicates that neurotrypsin plays its essential role for human cognitive functions through a similar mechanism. Our analyses suggest that Teq and neurotrypsin are not orthologous, leading us to question their equivalent roles in higher brain function.     

Spatiotemporal rescue of memory dysfunction in Drosophila

We have developed a method for temporal and regional gene expression targeting (TARGET) in Drosophila and show the simultaneous spatial and temporal rescue of a memory defect. The transient expression of the rutabaga-encoded adenylyl cyclase in the mushroom bodies of the adult brain was necessary and sufficient to rescue the rutabaga memory deficit, which rules out a developmental brain defect in the etiology of this deficit and demonstrates an acute role for rutabaga in memory formation in these neurons. The TARGET system offers general utility in simultaneously addressing issues of when and where gene products are required.     

Exclusive consolidated memory phases in Drosophila

Two types of consolidated memory have been described in Drosophila, anesthesia-resistant memory (ARM), a shorter-lived form, and stabilized long-term memory (LTM). Until now, it has been thought that ARM and LTM coexist. On the contrary, we show that LTM formation leads to the extinction of ARM. Flies devoid of mushroom body vertical lobes cannot form LTM, but spaced conditioning can still erase their ARM, resulting in a remarkable situation: The more these flies are trained, the less they remember. We propose that ARM acts as a gating mechanism that ensures that LTM is formed only after repetitive and spaced training.     

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.     

Dopamine-mushroom body circuit regulates saliency-based decision-making in Drosophila

Drosophila melanogaster can make appropriate choices among alternative flight options on the basis of the relative salience of competing visual cues. We show that this choice behavior consists of early and late phases; the former requires activation of the dopaminergic system and mushroom bodies, whereas the latter is independent of these activities. Immunohistological analysis showed that mushroom bodies are densely innervated by dopaminergic axons. Thus, the circuit from the dopamine system to mushroom bodies is crucial for choice behavior in Drosophila.     

Localization of a short-term memory in Drosophila

Memories are thought to be due to lasting synaptic modifications in the brain. The search for memory traces has relied predominantly on determining regions that are necessary for the process. However, a more informative approach is to define the smallest sufficient set of brain structures. The rutabaga adenylyl cyclase, an enzyme that is ubiquitously expressed in the Drosophila brain and that mediates synaptic plasticity, is needed exclusively in the Kenyon cells of the mushroom bodies for a component of olfactory short-term memory. This demonstrates that synaptic plasticity in a small brain region can be sufficient for memory formation.     

Truncating neurotrypsin mutation in autosomal recessive nonsyndromic mental retardation

A 4-base pair deletion in the neuronal serine protease neurotrypsin gene was associated with autosomal recessive nonsyndromic mental retardation (MR). In situ hybridization experiments on human fetal brains showed that neurotrypsin was highly expressed in brain structures involved in learning and memory. Immuno-electron microscopy on adult human brain sections revealed that neurotrypsin is located in presynaptic nerve endings, particularly over the presynaptic membrane lining the synaptic cleft. These findings suggest that neurotrypsin-mediated proteolysis is required for normal synaptic function and suggest potential insights into the pathophysiological bases of mental retardation.     

Normalization for sparse encoding of odors by a wide-field interneuron

Sparse coding presents practical advantages for sensory representations and memory storage. In the insect olfactory system, the representation of general odors is dense in the antennal lobes but sparse in the mushroom bodies, only one synapse downstream. In locusts, this transformation relies on the oscillatory structure of antennal lobe output, feed-forward inhibitory circuits, intrinsic properties of mushroom body neurons, and connectivity between antennal lobe and mushroom bodies. Here we show the existence of a normalizing negative-feedback loop within the mushroom body to maintain sparse output over a wide range of input conditions. This loop consists of an identifiable "giant" nonspiking inhibitory interneuron with ubiquitous connectivity and graded release properties.     

Inducing sleep by remote control facilitates memory consolidation in Drosophila

Sleep is believed to play an important role in memory consolidation. We induced sleep on demand by expressing the temperature-gated nonspecific cation channel Transient receptor potential cation channel (UAS-TrpA1) in neurons, including those with projections to the dorsal fan-shaped body (FB). When the temperature was raised to 31°C, flies entered a quiescent state that meets the criteria for identifying sleep. When sleep was induced for 4 hours after a massed-training protocol for courtship conditioning that is not capable of inducing long-term memory (LTM) by itself, flies develop an LTM. Activating the dorsal FB in the absence of sleep did not result in the formation of LTM after massed training.     

北京灵山野生侧耳的分离鉴定与人工驯化

【目的】从北京市门头沟区的灵山采集野生浅黄白色侧耳子实体,开展分离鉴定、人工驯化和产酶特性研究,以获得具有商品价值的平菇新品种。【方法】采用组织分离法获得菌株纯培养,编号F1636。采用形态和分子系统学鉴定手段,确定其分类学地位;进一步以78%棉花壳、20%麦麸、1%葡萄糖、1%石灰为栽培培养基进行出菇试验;测定子实体蛋白酶、漆酶、锰过氧化物酶和木素过氧化物酶活性。【结果】结果表明,F1635菌株为肺形侧耳(Pleurotus pulmonarius),能够在以棉籽壳为主要基质的培养基上出菇,子实体菌盖灰白色,并且在夏季高温季节(28~30℃)出菇,菇形整齐。子实体具有较高的产漆酶和蛋白酶活性,粗提液中酶活分别为(332.1±7.5)U/mL和(3 931.0±427.2)U/mL。本研究分离并驯化一株灰白色肺形侧耳菌株,具有潜在商品开发前景。     

Molecular Cloning and Expression of Polyphenoloxidase Genes from the Mushroom,Agaricus bisporus

The polyphenoloxidase(PPO)is the key enzyme considered to be responsible for mushroom browning.By using homology cloning and rapid amplification of cDNA ends (RACE),two new PPO genes and the corresponding cDNA were identified from the fruit bodies of Agaricus bisporus(AbPPO3 and AbPPO4,GenBank accession nos.GU936494 and GU936493,respectively).The genomic DNA sequences of AbPPO3 and AbPPO4 are 2 080 and 2 189 bp in length,respectively,encoding putative polypeptides of approximately 66 and 68 kDa.The deduced amino acid sequences show characteristic features of two copper-binding domains conserved in the type Ⅲ copper proteins including fungal polyphenol oxidases.Sequence comparisons indicate that AbPPO3 and AbPPO4 present 55.3%similarity to each other f48%identity).We also obtained more than 1.5-kb long sequences upstream of the start codon of the AbPPO3 and AbPPO4 and recognized them as their respective putative promoters.Analyses of the two PPO promoter regions show that they contain abundant cis-acting elements which are probably responsible for anaerobic induction,light,wound,stress,and auxin response.Semi-quantitative RT-PCR results indicate that AbPPO3 and AbPPO4 were highly expressed in the mature fruit bodies and up-regulated after 2-d storage of mushroom.These results suggest that AbPPO3 and AbPPO4 may play roles in A.bisporus browning and pigmentation during development and postharvest storage and the elements in promoters may act as regulatory elements for the inducible expression of AbPPO3 and AbPPO4.The successful cloning and expression analysis of AbPPO3 and AbPPO4 warrant a further investigation on the structure and function of A.bisporus PPO which points to the possible targets for genetic manipulation.     

大豆秸秆栽培香菇研究

利用大豆秸秆设置不同培养基替代木屑和麸皮栽培香菇,分析各培养基对香菇子实体产量、经济性状、氨基酸含量、经济成本的影响。结果表明:培养基中大豆秸秆含量15%左右代替木屑栽培香菇效果较好,同时替代麸皮时培养基中大豆秸秆含量可达35%;大豆秸秆可以完全替代麸皮栽培香菇,并能提高鲜菇商品性,丰富子实体氨基酸含量;生产10 000袋香菇可降低生产成本达4 250元。研究结果可为有效利用大豆秸秆高效栽培香菇提供参考。     

Chaperone suppression of alpha-synuclein toxicity in a Drosophila model for Parkinson's disease

Parkinson's disease is a movement disorder characterized by degeneration of dopaminergic neurons in the substantia nigra pars compacta. Dopaminergic neuronal loss also occurs in Drosophila melanogaster upon directed expression of alpha-synuclein, a protein implicated in the pathogenesis of Parkinson's disease and a major component of proteinaceous Lewy bodies. We report that directed expression of the molecular chaperone Hsp70 prevented dopaminergic neuronal loss associated with alpha-synuclein in Drosophila and that interference with endogenous chaperone activity accelerated alpha-synuclein toxicity. Furthermore, Lewy bodies in human postmortem tissue immunostained for molecular chaperones, also suggesting that chaperones may play a role in Parkinson's disease progression.     

银杏叶提取物对去卵巢大鼠学习记忆功能的影响

利用水迷宫法研究了银杏叶提取物(EG b)对去卵巢大鼠学习记忆功能的影响,同时利用免疫组织化学SP法检测了大鼠海马中乙酰胆碱转移酶(ChAT)和神经元型一氧化氮合酶(NO S1)的表达情况。结果表明,去卵巢后大鼠学习记忆功能明显下降,海马中ChAT阳性神经元的表达明显减弱(P<0.05),NO S1阳性神经元(除CA 2区)的表达明显增强(P<0.01);EG b对雌激素缺乏所致的学习记忆功能下降具有明显的改善作用,其作用是通过增强海马中ChAT阳性神经元的表达和抑制NO S1阳性神经元的表达而实现的。     

平菇中3种球形病毒的鉴定及其特性研究

在韩国的平菇(Pleurotus ostreatus )商品化种植基地发现了真菌病毒的自然流行为害的现象。这些病害经常伴随着一些球形病毒粒体的出现。采用Tris-EDTA缓冲液提取,PEG-NaCl沉淀和CsCl梯度离心,依据不同的比重,获得了3种病毒粒体,其中1种病毒粒体直径为27nm,另外2种的粒体为27nm,并推定这些病毒共同感染栽培的平菇。其中1种27nm的球形病毒,其比重较34nm的病毒大,称为平菇球形病毒(OMSV),该病毒含有2条大小分别为6．00kb和1．25kb的ssRNA片段。直径为34nm的病毒有两种比重小的粒体,其中1种常与OMSV共感染平菇,称为平菇等面体病毒-I(oystermushroom isometric virus-I ,OMIV-1),该病毒含有12条dsRNA片段,它们的大小分别是2.65,2．45,2．40,2．20,2．15,2．10,2．05,2．00,1．90,1．80,1．00和O．80kb。另外一种称之为平菇等面体病毒-II(oyster mushroom isometric virus-II, OMIV-II),．含有3条dsRNA片段,大小分别是2．25,2．15和2．05kb。经聚丙烯酰胺凝胶(12％)电泳、考马斯量兰染色表明OMSV,OMIV-I和OMIV-II病毒粒体的外壳蛋白的分子量大小分别是29kDa、71kDa和62kDa。这些结果表明在平菇中至少存在3种不同的ssRNA和dsRNA病毒。     

菌渣培养料对双孢蘑菇子实体蛋白质营养价值的影响

测定以稻草、杏鲍菇菌渣、金针菇菌渣为主培养料的3种不同配方栽培双孢蘑菇子实体的营养成分和氨基酸含量,采用国际通用的蛋白质营养评价的方法,对其子实体的营养价值进行评价分析。结果表明,稻草配方的蘑菇粗蛋白含量(40.00%)和粗脂肪含量(3.20%)较菌渣配方高,其蛋白质品质评价指标均优于菌渣配方栽培的蘑菇;氨基酸比值系数法表明杏鲍菇菌渣配方氨基酸组成最优,菌渣配方均好于稻草配方;借助模式识别得出杏鲍菇菌渣配方、稻草配方栽培蘑菇与全鸡蛋蛋白质的贴近度为0.88,高于金针菇菌渣配方;杏鲍菇菌渣与金针菇菌渣配方栽培的蘑菇,其风味氨基酸含量高于稻草配方;结果说明菌渣配方需进一步优化,以提高蘑菇子实体蛋白质营养价值。     

松乳菇子实体两个发育时期的转录组分析

以松乳菇子实体为研究材料,采用de novo测序对松乳菇子实体进行测序与生物信息学分析,探究松乳菇子实体生长发育过程中幼菇期(LDG-1)和成熟期(LDG-2)基因表达的差异,并探寻影响松乳菇生长发育相关的主要基因和代谢通路。测序结果显示,共获得7.44G(LDG-1)和7.21G(LDG-2)的分析数据(clean reads)。KOG功能注释结果显示,松乳菇在幼菇期(LDG-1)和成熟期(LDG-2)具有全面而复杂的基因功能类别。GO富集结果提示,松乳菇在不同生长阶段(LDG-1和LDG-2)的生物代谢功能存在一定的差异。基因表达水平与聚类分析显示,ATP酶、多功能伴侣蛋白等家族基因为LDG-1和LDG-2主要高表达基因,在能量代谢与参与调控细胞周期中起重要作用。分析差异表达基因发现,相较于LDG-1期,LDG-2期有16 789个差异表达基因,其中7 635个基因上调,9 154个基因下调。差异表达基因KEGG富集通路分析结果显示,氧化磷酸化途径是松乳菇幼菇期生长发育过程中能量代谢的关键途径。进一步分析显示,MAPK信号通路是影响松乳菇子实体发育的关键信号通路,在促进松乳菇子实体进行有性生殖和调控菌丝体的极性生长中起重要作用。     

Rescue of photoreceptor degeneration in rhodopsin-null Drosophila mutants by activated Rac1

Rhodopsin is essential for photoreceptor morphogenesis; photoreceptors lacking rhodopsin degenerate in humans, mice, and Drosophila. Here we report that transgenic expression of a dominant-active Drosophila Rho guanosine triphosphatase, Drac1, rescued photoreceptor morphogenesis in rhodopsin-null mutants; expression of dominant-negative Drac1 resulted in a phenotype similar to that seen in rhodopsin-null mutants. Drac1 was localized in a specialization of the photoreceptor cortical actin cytoskeleton, which was lost in rhodopsin-null mutants. Thus, rhodopsin appears to organize the actin cytoskeleton through Drac1, contributing a structural support essential for photoreceptor morphogenesis.