自动识别技术在昆虫分类鉴别研究中的应用

昆虫的自动识别是重要的新兴研究领域,它以直接、快速、方便等优点日益受到人们的青睐。昆虫是世界上最大的生物类群,鉴定工作费时耗力,然而分类专家又在逐渐减少。近年来,昆虫自动识别技术的发展为解决这一矛盾提供了乐观的方案。众多分类学家不断探索自动识别的方法和理论,并开发出了一批识别软件。本文介绍自动识别的原理,分类讨论自动识别的技术和方法,并分析提出面临的困难和应对策略。     

Genetic Determinants of Symptoms on Viral DNA Satellites

Begomovirus-DNA-β disease complexes induce different symptom phenotypes in their hosts. To investigate the genetic determinants of the phenotypic differences, Nicotiana spp. and tomato plants were inoculated with infectious clones of Tobacco curly shoot virus (TbCSV)/TbCSV DNA-β (TbCSB) and Tomato yellow leaf curl China virus (TYLCCNV)/TYLCCNV DNA-β (TYLCCNB) pseudorecombinants and showed that TYLCCNB induced characteristic vein-thickening and enation symptoms, while TbCSB only slightly exacerbated the leaf-curling symptoms, regardless of the helper virus being used. The roles of DNA-β-encoded βC1 and a 430-nucleotide fragment containing the A-rich region and the putative βC1 promoter region of the βC1 gene (referred to as AP) in symptom development were further investigated by constructing hybrid satellites in which the βC1 coding region or AP was exchanged between the two satellite molecules. A TYLCCNB hybrid with TbCSB βC1 lost the ability to elicit the vein-thickening and enation phenotypes. TbCSB hybrids containing the TYLCCNB βC1 or AP fragment failed to induce the characteristic vein thickening and enations. A TYLCCNB hybrid having the TbCSB AP fragment produced the enations, but the number of enations was less and their sizes were reduced. Differently from the phloem-specific pattern of the TYLCCNB promoter, a full-length fragment upstream of the TbCSB βC1 gene confers a constitutive β-glucuronidase expression pattern in transgenic tobacco plants. The above results indicate that the DNA-β-encoded βC1 protein is the symptom determinant, but the promoter of the βC1 gene has influence on symptom production.Geminiviruses are small plant viruses with circular single-stranded DNA (ssDNA) genomes that are encapsidated in unique twinned (geminate) particles. Members of the genus Begomovirus are transmitted by whiteflies (Bemisia tabaci) and infect dicotyledonous plants (42). Begomoviruses have either one or two circular ssDNA genomic components (DNA-A and DNA-B). The DNA-A component is capable of autonomous replication and encapsidation, whereas the DNA-B component encodes two proteins (BC1 and BV1) involved in movement (14). Recently, some monopartite begomoviruses have been found in association with a novel satellite DNA molecule, referred to as DNA-β and now known as a betasatellite (2, 5, 20, 22, 38, 45). DNA-β is approximately half the size of the viral genomic DNA, and apart from a nonanucleotide sequence (TAATATTAC), it has little sequence identity with viral genomic DNA. DNA-β depends on the helper virus for replication and encapsidation and, in turn, is required for the induction of bona fide disease symptoms. DNA-β bears a βC1 open reading frame (ORF) on the complementary-sense strand, which is conserved among distinct betasatellites in terms of position and size. Mutational analyses and constitutive expression have shown that βC1 is a strong pathogenicity/symptom determinant (7, 34, 39).Begomovirus-DNA-β disease complexes are associated with a wide range of plant species and induce different sets of symptom phenotypes in their natural hosts (25). However, the contributions of the helper virus and the satellite molecule to symptom development are not clear. Tomato yellow leaf curl China virus (TYLCCNV) and Tobacco curly shoot virus (TbCSV) are monopartite begomoviruses associated with DNA-β, but they differ in the symptom phenotypes induced in Nicotiana spp. and Solanum lycopersicum (7, 22). In the present work, we report that the symptom differences between TYLCCNV/TYLCCNV DNA-β (TYLCCNB) and TbCSV/TbCSV DNA-β (TbCSB) are determined by DNA-β and the DNA-β-encoded βC1 protein is the symptom determinant, but the promoter of the βC1 gene has influence on symptom production.     

Proteome analysis of up-regulated proteins in the rat spinal cord induced by transection injury

The inability of the CNS to regenerate in adult mammals propels us to reveal associated proteins involved in the injured CNS. In this paper, either thoracic laminectomy (as sham control) or thoracic spinal cord transection was performed on male adult rats. Five days after surgery, the whole spinal cord tissue was dissected and fractionated into water-soluble (dissolved in Tris buffer) and water-insoluble (dissolved in a solution containing chaotropes and surfactants) portions for 2-DE. Protein identification was performed by MS and further confirmed by Western blot. As a result, over 30 protein spots in the injured spinal cord were shown to be up-regulated no less than 1.5-fold. These identified proteins possibly play various roles during the injury and repair process and may be functionally categorized as several different groups, such as stress-responsive and metabolic changes, lipid and protein degeneration, neural survival and regeneration. In particular, over-expression of 11-zinc finger protein and glypican may be responsible for the inhibition of axonal growth and regeneration. Moreover, three unknown proteins with novel sequences were found to be up-regulated by spinal cord injury. Further characterization of these molecules may help us come closer to understanding the mechanisms that underlie the inability of the adult CNS to regenerate.     

Cellular iron homeostasis mediated by the Mrs4–Ccc1–Smf3 pathway is essential for mitochondrial function,morphogenesis and virulence in Candida albicans

Iron bioavailability is crucial for mitochondrial metabolism and biosynthesis. Dysregulation of cellular iron homeostasis affects multiple aspects of mitochondrial physiology and cellular processes. However, the intracellular iron trafficking pathway in Candida albicans remains unclear. In this study, we characterized the Mrs4–Ccc1–Smf3 pathway, and demonstrated its important role in maintaining cellular iron levels. Double deletion of vacuolar iron exporter SMF3 and mitochondrial iron transporter MRS4 further elevated cellular iron levels in comparison with the single MRS4 deletion. However, deletion of vacuolar iron importer CCC1 in the mrs4?/? mutant restored cellular iron homeostasis to normal wild-type levels, and also normalized most of the defective phenotypes in response to various environmental stresses. Our results also suggested that both Mrs4 and Ccc1 contributed to the maintenance of mitochondrial function. The mrs4?/? and mrs4?/?smf3?/? mutants exhibited an obvious decrease in aconitase activities and mitochondrial membrane potential, whereas deletion of CCC1 in the mrs4?/? mutant effectively rescued these defects. Furthermore, we also found that the Mrs4–Ccc1–Smf3 pathway was indispensable for cell-wall stability, antifungal drug tolerance, filamentous growth and virulence, supporting the novel viewpoint that mitochondria might be the promising target for better antifungal therapies. Interestingly, the addition of exogenous iron failed to rescue the defects on non-fermentable carbon sources or hyphae-inducing medium, indicating that the defects in mitochondrial respiration and filamentous development might result from the disturbance of cellular iron homeostasis rather than environmental iron deprivation. Taken together, our results propose the Mrs4–Ccc1–Smf3 pathway as a potentially attractive target for antifungal drug development.     

Microglial activation mediates host neuronal survival induced by neural stem cells

The rational of neural stem cells (NSCs) in the therapy of neurological disease is either to replace dead neurons or to improve host neuronal survival, the latter of which has got less attention and the underlying mechanism is as yet little known. Using a transwell co‐culture system, we reported that, in organotypic brain slice cultures, NSCs significantly improved host neuronal viability. Interestingly, this beneficial effect of NSCs was abrogated by a microglial inhibitor minocycline, while it was mimicked by a microglial agonist, Toll‐like receptor 9 (TLR9) ligand CpG‐ODN, which supports the pro‐vital mediation by microglia on this NSCs‐improved neuronal survival. Moreover, we showed that NSCs significantly induced host microglial movement and higher expression of a microglial marker IBA‐1, the latter of which was positively correlated with TLR9 or extracellular‐regulated protein kinases 1/2 (ERK1/2) activation. Real‐time PCR revealed that NSCs inhibited the expression of pro‐inflammatory molecules, but significantly increased the expression of molecules associated with a neuroprotective phenotype such as CX3CR1, triggering receptor expressed on myeloid cells‐2 (TREM2) and insulin growth factor 1 (IGF‐1). Similarly, in the microglia cells, NSCs induced the same microglial response as that in the slices. Further treatment with TLR9 ligand CpG‐ODN, TLR9 inhibitor chloroquine (CQ) or ERK1/2 inhibitor U0126 demonstrated that TLR9‐ERK1/2 pathway was involved in the NSCs‐induced microglial activation. Collectively, this study indicated that NSCs improve host neuronal survival by switching microglia from a detrimental to a neuroprotective phenotype in adult mouse brain, and the microglial TLR9‐ERK1/2 pathway seems to participate in this NSCs‐mediated rescue action.     

Influence of pulsed electromagnetic field with different pulse duty cycles on neurite outgrowth in PC12 rat pheochromocytoma cells

The influence of low frequency (50 Hz repetition rate) pulsed electromagnetic field (EMF) on PC12 cell neurite outgrowth in vitro was investigated in this study. We studied the percentage of neurite bearing cells, average length of neurites, and directivity of neurite outgrowth in PC12 cells cultured for 96 h in the presence of nerve growth factor (NGF). PC12 cells were exposed in one incubator to pulsed EMF at 1.36 mT (peak value) generated by a pair of Helmholtz coils, and the control samples were placed in another identical incubator. We found that the pulse duty cycle had significant effect on neurite outgrowth. Low (10%) pulse on-time significantly inhibited the percentage of neurite bearing cells, but at the same time increased the average length of neurites, while 100% on-time (DC) had exactly the opposite effects. Furthermore, we found that neurites were prone to extend along the direction of pulsed EMF with 10% pulse on-time. Our studies show that neurite outgrowth in PC12 cells is sensitive to the pulse duty and this sensitivity was associated with NGF concentration.     

Therapeutic Effect of Intravenous Infusion of Perfluorocarbon Emulsion on LPS-Induced Acute Lung Injury in Rats

Acute lung injury (ALI) and its more severe form, acute respiratory distress syndrome (ARDS) are the leading causes of death in critical care. Despite extensive efforts in research and clinical medicine, mortality remains high in these diseases. Perfluorocarbon (PFC), a chemical compound known as liquid ventilation medium, is capable of dissolving large amounts of physiologically important gases (mainly oxygen and carbon dioxide). In this study we aimed to investigate the effect of intravenous infusion of PFC emulsion on lipopolysaccharide (LPS) induced ALI in rats and elucidate its mechanism of action. Forty two Wistar rats were randomly divided into three groups: 6 rats were treated with saline solution by intratracheal instillation (control group), 18 rats were treated with LPS by intratracheal instillation (LPS group) and the other 18 rats received PFC through femoral vein prior to LPS instillation (LPS+PFC group). The rats in the control group were sacrificed 6 hours later after saline instillation. At 2, 4 and 6 hours of exposure to LPS, 6 rats in the LPS group and 6 rats in LPS+PFC group were sacrificed at each time point. By analyzing pulmonary pathology, partial pressure of oxygen in the blood (PaO2) and lung wet-dry weight ratio (W/D) of each rat, we found that intravenous infusion of PFC significantly alleviated acute lung injury induced by LPS. Moreover, we showed that the expression of pulmonary myeloperoxidase (MPO), intercellular adhesion molecule-1 (ICAM-1) of endothelial cells and CD11b of polymorphonuclear neutrophils (PMN) induced by LPS were significantly decreased by PFC treatment in vivo. Our results indicate that intravenous infusion of PFC inhibits the infiltration of PMNs into lung tissue, which has been shown as the core pathogenesis of ALI/ARDS. Thus, our study provides a theoretical foundation for using intravenous infusion of PFC to prevent and treat ALI/ARDS in clinical practice.     

Cognitive Decline in Patients with Alzheimer’s Disease and Its Related Factors in a Memory Clinic Setting,Shanghai, China

Objectives

Progressive cognitive decline is a characteristic hallmark of AD. It is important to identify prognostic markers to improve patient care and long-term planning. We aimed to identify the characteristics of disease progression in AD patients, focusing on cognitive decline and its related factors.

Methods

Clinically diagnosed AD patients in a memory clinic were followed. The mini–mental state examination (MMSE) and a battery of other neuropsychological tests were performed to assess the rate of cognitive decline and to analyze the related factors.

Results

A total of 165 AD patients were analyzed for cognitive changes. The MMSE scores declined at a rate of 1.52 points per year. Most neuropsychological test scores deteriorated significantly over time. Younger and early-onset AD patients deteriorated more rapidly than older and late-onset patients in global cognition and executive function. Men declined faster in memory but slower in attention than women. Higher education was associated with more rapid deterioration in visuo-spatial ability. Family history, hypertension and cerebral vascular disease were also associated with disease progression.

Conclusion

Attention, executive and visuo-spatial functions deteriorate at faster rates than other cognitive functions in AD patients. Age and age at onset were the main factors that associated with deterioration.     

水稻双受精过程的细胞形态学及时间进程的观察

应用常规石蜡切片和荧光显微镜观察水稻(Oryz a sativa)受精过程中雌雄性细胞融合时的形态特征及时间进程, 确定合子期, 为花粉管通道转基因技术的实施提供理论依据。结果表明: 授粉后, 花粉随即萌发, 花粉管进入羽毛状柱头分支结构的细胞间隙, 继续生长于花柱至子房顶部的引导组织的细胞间隙中, 而后进入子房, 在子房壁与外珠被之间的缝隙中向珠孔方向生长, 花粉与花粉管均具有明显的绿色荧光。花粉管经珠孔及珠心表皮细胞间隙进入一个助细胞, 释放精子。精子释放前, 两极核移向卵细胞的合点端; 两精子释放于卵细胞与中央细胞的间隙后, 先后脱去细胞质, 然后分别移向卵核和极核, 移向卵核的精核快于移向极核的精核; 精核与两极核在向反足细胞团方向移动的过程中完成雌雄核融合。大量图片显示了雌雄性核融合的详细过程以及多精受精现象。水稻受精过程经历的时间表如下: 授粉后, 花粉在柱头萌发; 花粉萌发至花粉管进入珠孔大约需要0.5小时; 授粉后0.5小时左右, 花粉管进入一个助细胞, 释放精子; 授粉后0.5-2.5小时, 精卵融合形成合子; 授粉后约10.0小时, 合子第1次分裂, 合子期为授粉后2.5-10.0小时; 授粉后1.0-3.0小时, 精核与两极核融合; 授粉后约5.0小时, 初生胚乳核分裂。