生化网络中基序的适应性与敏感性

复杂生物系统的适应性和敏感性是许多生物网络中的两个基本特性,改善这两者有着十分重要的意义。然而,要同时改善两者往往有一定的困难。基于生物系统自适应调控的思想,一种能同时改善两者的方法被提出,并用40种典型的生化网络中的基序为例说明此方法的可行性。结果表明此方法对于所有40种基序均有效。此外,还从数值上论证了方法对参数的鲁棒性。     

The Drosophila Hem/Kette/Nap1 protein regulates asymmetric division of neural precursor cells by regulating localization of Inscuteable and Numb

The Hem/Kette/Nap1 protein is involved in many biological processes. We have recently reported that Hem is required for the normal migration of neurons in the Drosophila embryo. In this paper, we report that Hem regulates the asymmetric division of neural precursor cells. We find that a well-studied Hem/Kette mutant allele produces at least two main, but possibly more, phenotypic classes of mutant embryos, and these phenotypes correlate with variable levels of maternal wild type Hem protein in the developing embryo. While the weaker class exhibits weak axon guidance defect and the mis-migration of neurons, the stronger class causes severe axon guidance defects, mis-migration of neurons and symmetric division of ganglion mother cells (GMC) of the RP2/sib lineage. We also show that the basis for the loss of asymmetric division is due to non-localization of Inscuteable and Numb in GMC-1. A non-asymmetric Numb segregates to both daughter cells of GMC-1, which then prevents Notch signaling from specifying a sib fate. This causes both cells to adopt an RP2 fate. Furthermore, loss of function for Abelson tyrosine kinase also causes loss of asymmetric localization of Inscuteable and Numb and symmetric division of GMC-1, the loss of function for WAVE has a very weakly penetrant loss of asymmetry defect. These results define another role for Hem/Kette/Nap1 in a neural precursor cell during neurogenesis.     

褐飞虱、白背飞虱的种内和种间效应

在室内条件下研究了褐飞虱,白背飞虱在3种类型水稻稻苗上的种内密度效应和种间互作效应,结果表明：在6－24头／盆若虫和2－6对／盆成虫的接虫密度范围内,褐飞虱,白背飞虱的种内密度效应均较弱,其中尤以褐飞虱的种内密度效应更弱,种内密度效应与水稻品种有关,在秀水11和协优9308上,白背飞虱的种内密度效应相对较强;褐飞虱在浙852和协优9308上表现一定的密度效应;褐飞虱和白背飞虱共存时种间在互利关系,其中尤以对白背飞虱有利,主要表现为两种飞虱的若虫存活率,成虫短翅率,单雌每天产卵量和后代虫孵化率在混合饲养时比一种飞虱单独饲养时均有不同程度的提高。     

The Hem protein mediates neuronal migration by inhibiting WAVE degradation and functions opposite of Abelson tyrosine kinase

In the nervous system, neurons form in different regions, then they migrate and occupy specific positions. We have previously shown that RP2/sib, a well-studied neuronal pair in the Drosophila ventral nerve cord (VNC), has a complex migration route. Here, we show that the Hem protein, via the WAVE complex, regulates migration of GMC-1 and its progeny RP2 neuron. In Hem or WAVE mutants, RP2 neuron either abnormally migrates, crossing the midline from one hemisegment to the contralateral hemisegment, or does not migrate at al and fail to send out its axon projection. We report that Hem regulates neuronal migration through stabilizing WAVE. Since Hem and WAVE normally form a complex, our data argues that in the absence of Hem, WAVE, which is presumably no longer in a complex, becomes susceptible to degradation. We also find that Abelson tyrosine kinase affects RP2 migration in a similar manner as Hem and WAVE, and appears to operate via WAVE. However, while Abl negatively regulates the levels of WAVE, it regulates migration via regulating the activity of WAVE. Our results also show that during the degradation of WAVE, Hem function is opposite to that of and downstream of Abl.     

冬水田典型生境类型节肢动物群落多样性及生物量特征

为了掌握休耕季节不同生境冬水田节肢动物群落多样性及生物量特征,于2017年2—4月在重庆市璧山区通过陷阱法对3类冬水田耕作区及期9个小区生境进行了定点调查,分别为水稻和蔬菜及荒地耕作区、水稻和蔬菜耕作区及水稻和林地耕作区。共捕获节肢动物108367只,隶属于3纲119科(种)。Berger-Parker优势度指数表明,冬水田节肢动物群落以罕见或稀少种(类群)数量最多以及优势类群数量稀少且突出为最基本特征,圆科和长角科是最主要的优势类群。节肢动物密度和生物量的百分比分析表明,腐食者和捕食者是节肢动物群落的主要功能团;弹尾虫以及不同种类蜘蛛和天敌昆虫类群分别构成了腐食者和捕食者中的主要类群(种)。3类冬水田及其小区节肢动物群落主要功能团密度和生物量以及群落Shannon-Wiener多样性指数(H′)、Margalef丰富度指数(D)、Pielou均匀度指数(J)和Simpson优势集中性指数(C)均有明显的规律变化,且出现了显著性差异(P0.05);节肢动物群落及其主要功能团腐食者和植食者分别在密度和生物量间,以及捕食者与其猎物腐食者和植食者在生物量上都具显著的相关性(P0.05)。群落相似性及相关性分析显示,3类冬水田及其小区节肢动物群落组成总体上差异明显,显然受到了稻田生境及耕作/管理等非生物因素的影响;其中生境类型(FH)作用最大,其次是蓄水量(EWQ)、稻桩生物(BR)、种植模式(PP)和收割方式(HM);它们与节肢动物群落密度及参数H′、D和C,以及腐食者密度和生物量、捕食者密度等显著正相关或负相关(P0.05)。主成分及聚类分析结果进一步指出,3类冬水田的生境异质性差异较大,这与它们小区在节肢动物群落密度(AI)、腐食者密度(DI)及FH等生物和非生物因素上的较大不同有关。总之,3类冬水田主要营养链“水稻秸秆-腐食者-捕食者”中存在不同程度的级联效应;弹尾虫作为该效应中腐食者的代表承担着冬水田“关键或中心”节肢动物类群具有的双重生态功能;不同冬水田及其小区节肢动物群落多样性及生物量特征差异明显,这与FH、EWQ、BR、PP和HM等非生物因素密切相关。     

Neural fate decisions mediated by combinatorial regulation of Hes1 and miR-9

In the nervous system, Hes1 shows an oscillatory manner in neural progenitors but a persistent one in neurons. Many models involving Hes1 have been provided for the study of neural differentiation but few of them take the role of microRNA into account. It is known that a microRNA, miR-9, plays crucial roles in modulating Hes1 oscillations. However, the roles of miR-9 in controlling Hes1 oscillations and inducing transition between different cell fates still need to be further explored. Here we provide a mathematical model to show the interaction between miR-9 and Hes1, with the aim of understanding how the Hes1 oscillations are produced, how they are controlled, and further, how they are terminated. Based on the experimental findings, the model demonstrates the essential roles of Hes1 and miR-9 in regulating the dynamics of the system. In particular, the model suggests that the balance between miR-9 and Hes1 plays important roles in the choice between progenitor maintenance and neural differentiation. In addition, the synergistic (or antagonistic) effects of several important regulations are investigated so as to elucidate the effects of combinatorial regulation in neural decision-making. Our model provides a qualitative mechanism for understanding the process in neural fate decisions regulated by Hes1 and miR-9.     

Functional analysis of rice NPR1-like genes reveals that OsNPR1/NH1 is the rice orthologue conferring disease resistance with enhanced herbivore susceptibility

The key regulator of salicylic acid (SA)-mediated resistance, NPR1, is functionally conserved in diverse plant species, including rice (Oryza sativa L.). Investigation in depth is needed to provide an understanding of NPR1-mediated resistance and a practical strategy for the improvement of disease resistance in the model crop rice. The rice genome contains five NPR1-like genes. In our study, three rice homologous genes, OsNPR1/NH1, OsNPR2/NH2 and OsNPR3, were found to be induced by rice bacterial blight Xanthomonas oryzae pv. oryzae and rice blast Magnaporthe grisea, and the defence molecules benzothiadiazole, methyl jasmonate and ethylene. We confirmed that OsNPR1 is the rice orthologue by complementing the Arabidopsis npr1 mutant. Over-expression of OsNPR1 conferred disease resistance to bacterial blight, but also enhanced herbivore susceptibility in transgenic plants. The OsNPR1-green fluorescent protein (GFP) fusion protein was localized in the cytoplasm and moved into the nucleus after redox change. Mutations in its conserved cysteine residues led to the constitutive localization of OsNPR1(2CA)-GFP in the nucleus and also abolished herbivore hypersensitivity in transgenic rice. Different subcellular localizations of OsNPR1 antagonistically regulated SA- and jasmonic acid (JA)-responsive genes, but not SA and JA levels, indicating that OsNPR1 might mediate antagonistic cross-talk between the SA- and JA-dependent pathways in rice. This study demonstrates that rice has evolved an SA-mediated systemic acquired resistance similar to that in Arabidopsis, and also provides a practical approach for the improvement of disease resistance without the penalty of decreased herbivore resistance in rice.