Growth of Arabidopsis seedlings on high fungal doses of Piriformospora indica has little effect on plant performance,stress, and defense gene expression in spite of elevated jasmonic acid and jasmonic acid-isoleucine levels in the roots

The endophytic fungus Piriformospora indica colonizes the roots of many plant species including Arabidopsis and promotes their performance, biomass, and seed production as well as resistance against biotic and abiotic stress. Imbalances in the symbiotic interaction such as uncontrolled fungal growth result in the loss of benefits for the plants and activation of defense responses against the microbe. We exposed Arabidopsis seedlings to a dense hyphal lawn of P. indica. The seedlings continue to grow, accumulate normal amounts of chlorophyll, and the photosynthetic parameters demonstrate that they perform well. In spite of high fungal doses around the roots, the fungal material inside the roots was not significantly higher when compared with roots that live in a beneficial symbiosis with P. indica. Fifteen defense- and stress-related genes including PR2, PR3, PAL2, and ERF1 are only moderately upregulated in the roots on the fungal lawn, and the seedlings did not accumulate H₂O₂/radical oxygen species. However, accumulation of anthocyanin in P. indica-exposed seedlings indicates stress symptoms. Furthermore, the jasmonic acid (JA) and jasmonic acid-isoleucine (JA-Ile) levels were increased in the roots, and consequently PDF1.2 and a newly characterized gene for a 2-oxoglurate and Fe²⁺-dependent oxygenase were upregulated more than 7-fold on the dense fungal lawn, in a JAR1- and EIN3-dependent manner. We conclude that growth of A. thaliana seedlings on high fungal doses of P. indica has little effect on the overall performance of the plants although elevated JA and JA-Ile levels in the roots induce a mild stress or defense response.     

Two-component signal transduction systems in eukaryotic microorganisms

Conserved signal transduction pathways that use phosphorelay from histidine kinases through an intermediate transfer protein (H2) to response regulators have been found in a variety of eukaryotic microorganisms. Several of these pathways are linked to mitogen-activated protein kinase cascades. These networks control different physiological responses including osmoregulation, cAMP levels and cellular morphogenesis.     

大鼠杏仁核5-HT_3受体参与免疫调制

实验通过大鼠侧脑室和杏仁核给予 5 HT3受体激动剂 1 phenylbiguanide (PBG) ,用 3H TdR掺入法测定脾细胞丝裂原 (concanavalinA ,ConA和lipopolysaccharide ,LPS)刺激增殖效应 ,用活化脾细胞增殖法测定IL 2生成 ,MTT法测定自然杀伤 (naturalkiller,NK)细胞活性和用放射免疫测定血浆皮质酮水平 ,以探讨大鼠杏仁核 5 HT3受体在免疫调控中的作用。结果表明 :5 HT3受体拮抗剂granisetron (GNT ,0 1～ 0 4mg/kgip)剂量依赖地增强ConA和LPS刺激的脾细胞增殖 ,作用在连续给药 5d最明显 ;双侧脑室给予PBG ( 5 μg/side)可增强ConA和LPS刺激的脾细胞增殖效应 ,作用在连续给药 3d最明显 ;双侧和单侧中央杏仁核给予PBG 0 5 μg均增强ConA刺激的脾细胞增殖和IL 2生成 ;底内侧杏仁核给予同剂量PBG仅增强LPS刺激的脾细胞增殖效应 ,不影响ConA刺激的脾细胞增殖和IL 2生成 ;中央杏仁核给予PBG升高血浆皮质酮的作用较底内侧杏仁核给予等量PBG引起的升高血浆皮质酮作用明显 (P <0 0 1)。侧脑室、中央杏仁核和底内杏仁核给予PBG对丝裂原刺激的脾细胞增殖效应影响不同 ,但均被同时同部位给予GNT所拮抗 ,提示杏仁核中央核和底内侧核的 5 HT3受体可能以不同方式参与ConA或LPS刺激的脾细胞增殖效应的调制     

Functional CD169 on Macrophages Mediates Interaction with Dendritic Cells for CD8+ T Cell Cross-Priming

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西南岩溶地区黄荆和檵木叶片结构对其生态环境的响应

应用常规石蜡切片法对生长于桂林毛村岩溶区和非岩溶区的黄荆(Vitex negundo)和檵木(Loropetalumchinense)的解剖特征进行了比较研究,并对两区的黄荆叶片表皮形态进行了扫描电镜观察.结果显示:(1)两地的黄荆叶片背面均有浓密的绒毛,但致密程度有差异,岩溶区黄荆叶片的气孔深藏于绒毛间隙,这种结构可减少水分蒸发,降低因岩溶干旱带来的水分缺失.(2)岩溶区黄荆和檵木的叶片厚度、上下表皮厚度、栅栏组织的厚度以及栅栏组织的致密程度均大于非岩溶区,这些特征有利于减少水分蒸腾.(3)岩溶区黄荆和檵木叶片的维管组织发达程度高于非岩溶区,有利于在蒸腾减小的情况下促进水分运输和营养元素的迁移,说明2种植物叶片结构特征在不同生境区的改变是其长期在岩溶区干旱环境条件下形成的适应性变化.     

The Caenorhabditis elegans FancD2 ortholog is required for survival following DNA damage

Fanconi anemia (FA) is an autosomal recessive disease characterized by bone-marrow failure, congenital abnormalities, and cancer susceptibility. There are 11 FA complementation groups in human where 8 genes have been identified. We found that FancD2 is conserved in evolution and present in the genome of the nematode Caenorhabditis elegans. The gene Y41E3.9 (CeFancD2) encodes a structural ortholog of human FANCD2 and is composed of 10 predicted exons. Our analysis showed that exons 6 and 7 were absent from a CeFancD2 EST suggesting the presence of a splice variant. In an attempt to characterize its role in DNA damage, we depleted worms of CeFANCD2 using RNAi. When the CeFANCD2(RNAi) worms were treated with a crosslinking agent, a significant drop in the progeny survival was noted. These worms were also sensitive, although to a lesser extent, to ionizing radiation (IR). Therefore, these data support an important role for CeFANCD2 in DNA damage response as for its human counterpart. The data also support the usefulness of C. elegans to study the Fanconi anemia pathway, and emphasize the biological importance of FANCD2 in DNA damage response throughout evolution.     

Intrinsic and environmental response pathways that regulate root system architecture

Root system development is an important agronomic trait. The right architecture in a given environment allows plants to survive periods of water of nutrient deficit, and compete effectively for resources. Root systems also provide an optimal system for studying developmental plasticity, a characteristic feature of plant growth. This review proposes a framework for describing the pathways regulating the development of complex structures such as root systems: intrinsic pathways determine the characteristic architecture of the root system in a given plant species, and define the limits for plasticity in that species. Response pathways co-ordinate environmental cues with development by modulating intrinsic pathways. The current literature describing the regulation of root system development is summarized here within this framework. Regulatory pathways are also organized based on their specific developmental effect in the root system. All the pathways affect lateral root formation, but some specifically target initiation of the lateral root, while others target the development and activation of the lateral root primordium, or the elongation of the lateral root. Finally, we discuss emerging approaches for understanding the regulation of root system architecture.     

Antibody responses of mice exposed to low-power microwaves under combined, pulse-and-amplitude modulation

Irradiation by pulsed microwaves (9.4 GHz, 1 microsecond pulses at 1,000/s), both with and without concurrent amplitude modulation (AM) by a sinusoid at discrete frequencies between 14 and 41 MHz, was assessed for effects on the immune system of Balb/C mice. The mice were immunized either by sheep red blood cells (SRBC) or by glutaric-anhydride conjugated bovine serum albumin (GA-BSA), then exposed to the microwaves at a low rms power density (30 microW/cm2; whole-body-averaged SAR approximately 0.015 W/kg). Sham exposure or microwave irradiation took place during each of five contiguous days, 10 h/day. The antibody response was evaluated by the plaque-forming cell assay (SRBC experiment) or by the titration of IgM and IgG antibodies (GA-BSA experiment). In the absence of AM, the pulsed field did not greatly alter immune responsiveness. In contrast, exposure to the field under the combined-modulation condition resulted in significant, AM-frequency-dependent augmentation or weakening of immune responses.     

An Integrated Approach for Analysis of the DNA Damage Response in Mammalian Cells: NUCLEOTIDE EXCISION REPAIR,DNA DAMAGE CHECKPOINT,AND APOPTOSIS*

DNA damage by UV and UV-mimetic agents elicits a set of inter-related responses in mammalian cells, including DNA repair, DNA damage checkpoints, and apoptosis. Conventionally, these responses are analyzed separately using different methodologies. Here we describe a unified approach that is capable of quantifying all three responses in parallel using lysates from the same population of cells. We show that a highly sensitive in vivo excision repair assay is capable of detecting nucleotide excision repair of a wide spectrum of DNA lesions (UV damage, chemical carcinogens, and chemotherapeutic drugs) within minutes of damage induction. This method therefore allows for a real-time measure of nucleotide excision repair activity that can be monitored in conjunction with other components of the DNA damage response, including DNA damage checkpoint and apoptotic signaling. This approach therefore provides a convenient and reliable platform for simultaneously examining multiple aspects of the DNA damage response in a single population of cells that can be applied for a diverse array of carcinogenic and chemotherapeutic agents.