Physiological parameters correlated with Tomato Mosaic Virus inducing defensive response in Datura metel

Programed cell death resembles a real nature active defense in Datura metel against TMV after three days of virus infection. This adaptive plant immune response was quantitatively assessed against Tomato Mosaic Virus infection by the following physiological markers; Chlorophyll-a (mg/g), Chlorophyll-b (mg/g), total protein (mg/g), hydrogen peroxide H₂O₂ (μmol/100 mg), DNA (μg/100 mg), RNA (μg/100 mg), Salicylic acid (μg/g), and Comet Assays. Parameters were assessed for asymptomatic healthy and symptomatic infected detached leaves. The results indicated H₂O₂ and Chlorophyll-a as the most potential parameters. Chlorophyll-a was considered the only significant predictor variant for the H₂O₂ dependent variant with a P value of 0.001 and R-square of 0.900. The plant immune response was measured within three days of virus infection using the cutoff value of H₂O₂ (⩽1.095 μmol/100 mg) and (⩽3.201 units) for the tail moment in the Comet Assay. Their percentage changes were 255.12% and 522.40% respectively which reflects the stress of virus infection in the plant. Moreover, H₂O₂ showed 100% specificity and sensitivity in the symptomatic infected group using the receiver-operating characteristic (ROC). All tested parameters in the symptomatic infected group had significant correlations with twenty-five positive and thirty-one negative correlations where the P value was <0.05 and 0.01. Chlorophyll-a parameter had a crucial role of highly significant correlation between total protein and salicylic acid. Contrarily, this correlation with tail moment unit was (r = −0.930, P < 0.01) where the P value was <0.01. The strongest significant negative correlation was between Chlorophyll-a and H₂O₂ at P < 0.01, while moderate negative significant correlation was seen for Chlorophyll-b where the P value < 0.05. The present study discloses the secret of the three days of rapid transient production of activated oxygen species (AOS) that was enough for having potential quantitative physiological parameters for defensive plant response toward the virus.     

The effects of maturation on self-induced dynamic body sway frequencies of girls performing acrobatics or classical dance

We investigated the effects of maturation on the dynamic body sways of healthy girls. Prepubertal and postpubertal girls practising professional physical activities requiring a good ability to maintain equilibrium (acrobats and dancers) were asked to stand on a free seesaw platform and the results compared to those for untrained age-matched girls. This platform (stabilometer) allows self-induced body sways. Stabilograms were obtained by a double integration of the angular acceleration from the recordings of the platform sways made with an accelerometer. Fast Fourier transform processing of stabilograms allowed spectral frequency analysis. The total spectrum energy and the energies of three frequency bands (0–0.5 Hz, 0.5–2 Hz, 2–20 Hz) were determined. ANOVA showed that, for all groups of different equilibrium activity and independent of visual input, prepubertal girls had higher energy values than postpubertal girls in the 0- to 0.5-Hz band whereas the opposite was true for 0.5- to 2-Hz band. Ballet dancers were more dependent than acrobats on visual inputs for the regulation of their postural control but were less dependent than untrained girls at both ages. Maturation seemed to shift body sways towards higher frequencies and the utilization of the cues of postural control was different according to the type of equilibrium activity practised by the subjects. Accepted: 7 February 1997     

Three-dimensional perfused cell culture

Compelling evidence suggests the limitation and shortcomings of the current and well established cell culture method using multi-well plates, flasks and Petri dishes. These are particularly important when cell functions are sensitive to the local microenvironment, cell–cell and cell–extracellular matrix interactions. There is a clear need for advanced cell culture systems which mimic in vivo and more physiological conditions. This review summarises and analyses recent progress in three dimensional (3D) cell culture with perfusion as the next generation cell culture tools, while excluding engineered tissue culture where three dimensional scaffold has to be used for structural support and perfusion for overcoming mass transfer control. Apart from research activities in academic community, product development in industry is also included in this review.     

The Growth,physiological and biochemical response of foxtail millet to atrazine herbicide

Foxtail millet (Pennisetum glaucum L.) is a vital crop that is planted as food and fodder crop around the globe. There is only limited information is present for abiotic stresses on the physiological responses to atrazine. A field experiment was conducted to investigate the effects of different atrazine dosages on the growth, fluorescence and physiological parameters i.e., malonaldehyde (MDA) and reactive oxygen species (ROS) (H₂O₂ and O₂) in the leaves to know the extent of atrazine on oxidative damage of foxtail millet. Our experiment consisted of 0, 2.5, 12.5, 22.5 and 32.5 (mg/kg) of labeled atrazine doses on 2 foxtaill millet varieties. High doses of atrazine significantly enhanced ROS and MDA synthesis in the plant leaves. Enzymes activities like ascorbate peroxidase (APX) and peroxidase (POD) activities enhanced, while catalase (CAD) and superoxide dismutase (SOD) activities reduced with increasing atrazine concentrations. Finally atrazine doses at 32.5 mg/kg reduced chlorophyll contents, while chlorophyll (a/b) ratio also enhanced. Biomass, plant height, chlorophyll fluorescence parameters, minimal and maximal fluorescence (Fo, Fm), maximum and actual quantum yield, photochemical quenching coefficient, and electron transport rate are decreased with increasing atrazine doses.     

Notes on compositional diversity

This paper tries to show some ways and means of simple (binary) modelling, whereby diversity can be interconnected with other attributes of a community. A new type of scaling (called characteristic scaling) is introduced for further use.     

棘冠海星暴发及其对珊瑚礁的生态影响研究进展

棘冠海星的反复暴发是导致印度-太平洋区域珊瑚礁生态系统退化的最主要原因之一。然而，我国对棘冠海星的研究非常有限。本文综述了国内外关于棘冠海星及其暴发的生态影响和应对策略的研究进展，得出以下主要结论：1）雌性棘冠海星个体每年产卵数量高达50万-2亿个，环境因素变化只要导致幼虫和幼体存活率的轻微提高，成体就将得到大量补充；2）棘冠海星暴发的阈值为1000-1500个/km²，暴发周期为10-27 a，每次暴发持续1-10 a，最终可能以"种群集体感染疾病而崩溃"结束；3）棘冠海星暴发对印度洋及太平洋东部和北部珊瑚礁的破坏性非常小，却直接导致太平洋的西部和南部珊瑚礁90%以上的珊瑚死亡，并通过改变珊瑚群落组成、减少珊瑚和鱼类多样性而对珊瑚礁产生间接影响；4）关于棘冠海星暴发原因的假说中"陆地营养物质输入假说"和"捕食者过度捕捞假说"得到了最普遍的认可，但都不能解释所有的暴发事件；5）应对棘冠海星暴发的主要策略有改善水质、设立保护区、投放天敌和人工清理等，其中人工清理是最直接有效的策略，但迄今并没有发现可长期抑制棘冠海星暴发的方法。因此，急需加强对棘冠海星的深入研究，探查其暴发的根本原因和对策。     

A Novel Three-dimensional Flow Chamber Device to Study Chemokine-directed Extravasation of Cells Circulating under Physiological Flow Conditions

Extravasation of circulating cells from the bloodstream plays a central role in many physiological and pathophysiological processes, including stem cell homing and tumor metastasis. The three-dimensional flow chamber device (hereafter the 3D device) is a novel in vitro technology that recreates physiological shear stress and allows each step of the cell extravasation cascade to be quantified. The 3D device consists of an upper compartment in which the cells of interest circulate under shear stress, and a lower compartment of static wells that contain the chemoattractants of interest. The two compartments are separated by porous inserts coated with a monolayer of endothelial cells (EC). An optional second insert with microenvironmental cells of interest can be placed immediately beneath the EC layer. A gas exchange unit allows the optimal CO₂ tension to be maintained and provides an access point to add or withdraw cells or compounds during the experiment. The test cells circulate in the upper compartment at the desired shear stress (flow rate) controlled by a peristaltic pump. At the end of the experiment, the circulating and migrated cells are collected for further analyses. The 3D device can be used to examine cell rolling on and adhesion to EC under shear stress, transmigration in response to chemokine gradients, resistance to shear stress, cluster formation, and cell survival. In addition, the optional second insert allows the effects of crosstalk between EC and microenvironmental cells to be examined. The translational applications of the 3D device include testing of drug candidates that target cell migration and predicting the in vivo behavior of cells after intravenous injection. Thus, the novel 3D device is a versatile and inexpensive tool to study the molecular mechanisms that mediate cellular extravasation.     

Construction and Comparison of Two Receiver Operating Characteristic Curves Derived from the Same Samples

Receiver operating characteristic (ROC) curves are used to describe the performance of diagnostic procedures. This paper proposes a simple method for the statistical comparison of two ROC curves derived from the same set of patients and the same set of healthy subjects. Generalization to studies involving more than two screening factors is straightforward. This method does not require the calculation of variances of the areas or difference of areas under the curves.     

Spectrum structures and biological functions of 8-mers in the human genome

The spectra of k-mer frequencies can reveal the structures and evolution of genome sequences. We confirmed that the trimodal spectrum of 8-mers in human genome sequences is distinguished only by CG2, CG1 and CG0 8-mer sets, containing 2,1 or 0 CpG, respectively. This phenomenon is called independent selection law. The three types of CG 8-mers were considered as different functional elements. We conjectured that (1) nucleosome binding motifs are mainly characterized by CG1 8-mers and (2) the core structural units of CpG island sequences are predominantly characterized by CG2 8-mers. To validate our conjectures, nucleosome occupied sequences and CGI sequences were extracted, then the sequence parameters were constructed through the information of the three CG 8-mer sets respectively. ROC analysis showed that CG1 8-mers are more preference in nucleosome occupied segments (AUC > 0.7) and CG2 8-mers are more preference in CGI sequences (AUC > 0.99). This validates our conjecture in principle.     

Characterization and preliminary crystallographic data on the VL-related fragment of the human kI Bence Jones protein Wat

A “naturally occurring” human κI V_L dimer, designated Wat, has been isolated and crystallized. Protein Wat consists of two non-covalently bound monomers, each having a molecular weight of ~ 11,500. The monomer subunit is composed of an entire variable region light chain (V_L) domain closely homologous to that of the κI Bence Jones protein Roy (Hilschmann &; Craig, 1965) as evidenced from amino acid composition, tryptic peptide map, and sequence analysis. Immunochemical studies substantiated that protein Wat is of the κ chain subgroup κI and lacks the isotypic and allotypic antigenic determinants associated with the κ constant region light chain domain. Two types of crystals of V_L dimer Wat were obtained from ammonium sulfate or polyethylene glycol solutions. The type I crystals have unit cell dimensions of $\text{a = b = 82.6}\text{A}\text{?}\text{, c = 60.3}\text{A}\text{?}$, and the space group is hexagonal P6₂ or P6₄. The asymmetric unit consists of one V_L dimer; the fractional volume of unit cell occupied by solvent is 0.51. The unit cell dimensions of the type II crystals are $\text{a = b = 1,08.3}\text{A}\text{?}\text{, c = 108.8}\text{A}\text{?}$; the space group is hexagonal P6₁22 or P6₅22. Three variable domains constitute the asymmetric unit of the type II crystals; the fractional value of the solvent (0.52) is compatible with the value obtained for the type I crystals.