Relationship of Nitrogen Deficiency-Induced Leaf Senescence with ROS Generation and ABA Concentration in Rice Flag Leaves

Nitrogen (N) deficiency is one of the critical environmental factors that induce leaf senescence, and its occurrence may cause the shorten leaf photosynthetic period and markedly lowered grain yield. However, the physiological metabolism underlying N deficiency-induced leaf senescence and its relationship with the abscisic acid (ABA) concentration and reactive oxygen species (ROS) burst in leaf tissues are not well understood. In this paper, the effect of N supply on several senescence-related physiological parameters and its relation to the temporal patterns of ABA concentration and ROS accumulation during leaf senescence were investigated using the premature senescence of flag leaf mutant rice (psf) and its wild type under three N treatments. The results showed that N deficiency hastened the initiation and progression of leaf senescence, and this occurrence was closely associated with the upregulated expression of 9-cis-epoxycarotenoiddioxygenase genes (NCEDs) and with the downregulated expression of two ABA 8′-hydroxylase isoform genes (ABA8ox2 and ABA8ox3) under LN treatment. Contrarily, HN supply delayed the initiation and progression of leaf senescence, concurrently with the suppressed ABA biosynthesis and relatively lower level of ABA concentration in leaf tissues. Exogenous ABA incubation enhanced ROS generation and MDA accumulation in a dose-dependent manner, but it decreased the activities of glutamine synthetase (GS) and glutamate dehydrogenase (GDH) in detached leaf. These results suggested that the participation of ABA in the regulation of ROS generation and N assimilating/remobilizing metabolism in rice leaves was strongly responsible for induction of leaf senescence by N deficiency.

     

Clue to a New Deafness Gene: A Large Chinese Nonsyndromic Hearing Loss Family Linked to DFNA4

Hereditary hearing loss is one of the most common neurosensory defects in humans.Approximately 70％ of cases are nonsyndromic and could be inherited in autosomal dominant,autosomal recessive,mitochondrial,X-linked,and Y-linked manners (Wang et al.,2004;Alford,2011).The autosomal dominant type,comprising 15％-20％ of nonsyndromic hearing loss,is monogenic and genetically heterogeneous.Since the first dominant deafness locus (DFNA1) was identified in 1992,a total of 64 DFNA loci have been mapped (DFNA1-DFNA64),and 27 corresponding genes have been identified (http://hereditaryhearingloss.org).Previous studies have revealed that one deafness locus can be linked to more than one gene (Bayazit and Yilmaz,2006),and the question "one locus,how many genes?" was first raised about a decade ago (Van-Hauwe et al.,1999).So far,several loci,including DFNA2 and DFNA3,have been shown to be related to one or more genes,showing high genetic heterogeneity in hereditary hearing loss (Grifa et al.,1999;Goldstein and Lalwani,2002;Yan et al.,2011).     

Association between BMP15 Gene Polymorphism and Reproduction Traits and Its Tissues Expression Characteristics in Chicken

BMP15 (Bone morphogenetic protein 15) is an oocyte-secreted growth factor required for ovarian follicle development and ovulation in mammals, but its effects on reproduction in chickens are unclear. In this study, the association between BMP15 polymorphisms and reproduction traits were analyzed, and its expression characteristics in different tissues were explored in LaiWu Black chickens. Three single nucleotide polymorphisms (SNPs) were identified in four hundred LaiWu Black chickens. One SNP (NC_006091.3:g.1773T>C) located in exon 2 which was significantly associated with egg weight at first egg (EWFE) (P = 0.0389), was novel. Diplotypes based on the three SNPs were found to be significantly associated with egg weight at age of 43W (EW43) (P = 0.0058). The chickens with H3H3 diplotype had their first egg 0.57 days later than chickens with H5H5 diplotype and 1.21 days-3.96 days earlier than the other five diplotype chickens. The egg production at age of 43W (E43), egg production at age of 46W (E46) and egg production at age of 48W (E48) for chickens with H3H3 diplotype were the highest among all the chickens, and the E48 of chickens with H3H3 diplotype had 11.83 eggs higher than chickens with H1H5 diplotype. RT-qPCR results showed that the expression level of BMP15 gene in ovarian follicle was in the order of 4 mm>6 mm -8 mm> 15 mm -19 mm> 23 mm -29 mm > 33 mm -34 mm in diameter. The mRNA level in follicles of 4 mm and 6–8 mm in diameter were significantly higher than that in the other follicles (P<0.01). In the same week, the highest mRNA level was found in the ovary, and it was significantly different from that found in the liver and oviduct (P<0.01). Our results indicate that BMP15 plays a vital role in the development of ovary and follicles, especially in the development of primary follicles. H3H3 may be an potential advantageous molecular marker for improving reproduction traits in chickens.     

Celastrol prevents cadmium‐induced neuronal cell death via targeting JNK and PTEN‐Akt/mTOR network

Cadmium (Cd), a toxic environmental contaminant, induces neurodegenerative diseases. Celastrol, a plant‐derived triterpene, has shown neuroprotective effects in various disease models. However, little is known regarding the effect of celastrol on Cd‐induced neurotoxicity. Here, we show that celastrol protected against Cd‐induced apoptotic cell death in neuronal cells. This is supported by the findings that celastrol strikingly attenuated Cd‐induced viability reduction, morphological change, nuclear fragmentation, and condensation, as well as activation of caspase‐3 in neuronal cells. Concurrently, celastrol remarkably blocked Cd‐induced phosphorylation of c‐Jun N‐terminal kinase (JNK), but not extracellular signal‐regulated kinases 1/2 and p38, in neuronal cells. Inhibition of JNK by SP600125 or over‐expression of dominant negative c‐Jun potentiated celastrol protection against Cd‐induced cell death. Furthermore, pre‐treatment with celastrol prevented Cd down‐regulation of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and activation of phosphoinositide 3′‐kinase/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling in neuronal cells. Over‐expression of wild‐type PTEN enhanced celastrol inhibition of Cd‐activated Akt/mTOR signaling and cell death in neuronal cells. The findings indicate that celastrol prevents Cd‐induced neuronal cell death via targeting JNK and PTEN‐Akt/mTOR network. Our results strongly suggest that celastrol may be exploited for the prevention of Cd‐induced neurodegenerative disorders.

     

Alleviation of the detrimental effect of water deficit on wheat (Triticum aestivum L.) growth by an indole acetic acid-producing endophytic fungus

Plant and Soil - Endophytic fungi colonization is an eco-friendly strategy to respond to environmental stresses and confer tolerance to the host plant. Here, the responses of wheat plant inoculated...     

双钩巢粉虱产卵分泌物的化学成分

双钩巢粉虱Paraleyrodes pseudonaranjae Martin原产于南美洲,现已分布于美国的佛罗里达、夏威夷和中国的香港、广东、广西、海南等地.这种粉虱的产卵方式与螺旋粉虱Aleurodicus disperses Russell等相似,卵粒以白色的分泌物覆盖.本文采用气相色谱/质谱联用技术研究了双钩巢...     

Borrelia burgdorferi-induced monocyte chemoattractant protein-1 production in vivo and in vitro

Matrix metalloproteinase 9 (MMP-9) is selectively upregulated in erythema migrans (EM) lesions with acute Lyme disease. This study explored whether upregulation of MMP-9 was associated with monocyte chemoattractant protein 1 (MCP-1) production, and Borrelia burgdorferi (B. burgdorferi) could induce MCP-1 production in vivo and in vitro. The results indicated that expression of MCP-1 was significantly increased in U937 cells by B. burgdorferi. The activity of MMP-9 could be elevated by recombinant MCP-1 (rMCP-1) in U937 cells. MMP-9 was not upregulated by B. burgdorferi in fibroblasts. However, the expression of MCP-1 was significantly increased in the presence of B. burgdorferi in fibroblasts. The level of MCP-1 in EM lesions and in serum of patients with acute Lyme disease was also significantly elevated compared to that for healthy controls. The secreted MCP-1 may affect the production of MMP-9 in fibroblasts and/or macrophages.     

水稻大粒种质资源和遗传分析

谷粒重量是构成产量的三要素之一,对提高水稻产量具有重要意义.本文概述了国内外水稻大粒种质资源的现状,同时对粒重基因遗传分析的研究进展进行了综述.粒重是一个受多基因控制的数量性状,目前定位的粒重数量性状位点至少达89个、精细定位1个粒重基因gw3.1和1个长粒基因Lk-4（t）以及克隆1个粒重基因GS3,并在此基础上讨论了粒重在育种上的应用.