在中国应用垂直波束雷达监测褐飞虱和其他水稻害虫迁飞的可行性

近年来,可用于昆虫迁飞研究且可自动运行的垂直波束雷达(vertical-looking radar,VLR)的发展使得对迁飞性害虫的周年长期自动监测成为可能。本文提供了我们对能否将这种雷达应用于中国的褐飞虱和其他水稻害虫的监测与预测体系以改善其综合治理的可行性研究结果。以往的研究已经表明,这些害虫一般在300—2000m高度迁飞;而我们根据褐飞虱的雷达和射有效截面的计算结果表明,目前使用的3．2cm波长的VLR对褐飞虱个体目标的最大可检测高度仅约240m;虽然建造一部8．8mm波长的VLR即可覆盖褐飞虱迁飞高度的绝大部分,但其造价和维护费用均过于昂贵。为此,一个更可行的解决方案是,以3．2cm波长的VLR作为包括大多数水稻害虫在内的个体较大的迁飞性害虫的监测工具。     

Mapping the lithic colonization at the boundaries of life in Northern Victoria Land,Antarctica

The endolithic microbial communities of the Antarctic represent a borderline lifestyle in the most hostile ice-free areas of the continent. The extreme adaptation of microbes in these communities renders them very sensitive to environmental changes. To date, the actual distribution of these communities has never been investigated; yet, this information would define the geographic limits for life at present and supply a useful tool for monitoring any possible future variation related to climate change. In this study, most of the outcrops of Northern and of one site in Southern Victoria Land were recorded by altitudinal and sea distance gradients. The presence of endolithic life was determined by in situ observation, by microscopic observation of rock fragments in the laboratory, and, for doubtful samples, by culture experiment. Colonizers were present in more than 87 % of the visited sites. The presence of lithic life in Victoria Land appears to be wider than that reported 14 years earlier. The colonization trend follows climatic variation, with epiliths prevailing in coastal sites and decreasing towards the interior, while chasmoendoliths and cryptoendoliths increase and become predominant from the coast towards the inland sites. Typical cryptoendolithic colonization was exclusive on porous rocks as sandstone, chasmoendolithic colonization occurred even in less porous but translucent rocks as granite and quartz. Multivariate analysis of the combined results clearly indicates the pivotal role of the rock type in the colonization of endolithic micro-organisms; sandstone allows lithobionts to push themselves towards areas characterized by harsher conditions.     

Antimicrobial screening involving Helicobacter pylori of nano-therapeutic compounds based on the amoxicillin antibiotic drug

Nano-structure Cu(II) complex [Cu(AMAB)₂]Cl₂ with Schiff base (AMAB) derived from the condensation between 4-(dimethylamino)benzaldehyde and amoxicillin trihydrate was prepared. (AMAB) Schiff base and its Cu(II) complex were identified and confirmed by different physicochemical techniques. The Schiff base (AMAB) was coordinated to copper ion through carbonyl oxygen and imine nitrogen donor sites. X-ray powder diffraction shows a cubic crystal system of the Cu(II) complex. The density functional theory was used to optimize the structure geometries of the investigated compounds. The molecular docking of the active amino acids of the investigated proteins' interactions with the tested compounds was evaluated. The bactericidal or bacteriostatic effect of the compounds was screened against some bacterial strains. The activity of Cu-chelate against Gram-negative bacteria was mainly more effective than its (AMAB) ligand and vice versa in the case of Gram-positive bacteria. The biological activity of the prepared compounds with biomolecules calf thymus DNA (CT-DNA) was determined by electronic absorption spectra and DNA gel electrophoresis technique. All studies revealed that the Cu-chelate derivative exhibited better binding affinity to both CT-DNA than the AMAB and amoxicillin itself. The anti-inflammatory effect of the designed compounds was determined by testing their protein denaturation inhibitory activity spectrophotometrically. All obtained data supported that the designed nano-Cu(II) complex with Schiff base (AMAB) is a potent bactericide against H. pylori, and exhibits anti-inflammatory activity. The dual inhibition effects of the designed compound represent a modern therapeutic approach with extended spectrum of action. Therefore, it can act as good drug target in antimicrobial and anti-inflammtory therapies. Finally, H. pylori resistance to amoxicillin is absent or rare in many countries, thus amoxicillin nanoparticles may be beneficial for countries where amoxicillin resistance is reported.     

Cloning and sequencing of the metallothioprotein beta-lactamase II gene of Bacillus cereus 569/H in Escherichia coli

The structural gene for beta-lactamase II (EC 3.5.2.6), a metallothioenzyme, from Bacillus cereus 569/H (constitutive for high production of the enzyme) was cloned in Escherichia coli, and the nucleotide sequence was determined. This is the first class B beta-lactamase whose primary structure has been reported. The amino acid sequence of the exoenzyme form, deduced from the DNA, indicates that beta-lactamase II, like other secreted proteins, is synthesized as a precursor with a 30-amino acid N-terminal signal peptide. The pre-beta-lactamase II (Mr, 28,060) is processed in E. coli and in B. cereus to a single mature protein (Mr, 24,932) which is totally secreted by B. cereus but in E. coli remains intracellular, probably in the periplasm. The expression of the gene in E. coli RR1 on the multicopy plasmid pRWHO12 was comparable to that in B. cereus, where it is presumably present as a single copy. The three histidine residues that are involved (along with the sole cysteine of the mature protein) in Zn(II) binding and hence in enzymatic activity against beta-lactams were identified. These findings will help to define the secondary structure, mechanism of action, and evolutionary lineage of B. cereus beta-lactamase II and other class B beta-lactamases.     

Early endotoxin tolerance is associated with alterations in bone marrow-derived macrophage precursor pools

Early endotoxin tolerance has been defined as the transient period after an initial sublethal exposure to LPS during which a normally responsive individual is rendered hyporesponsive. Little is known about the cellular mechanisms that underlie this phenomenon. In this study, an early tolerance system was established by the injection of mice with 25 micrograms of E. coli K235 LPS. Maximal hyporesponsiveness in response to a challenge injection was observed 3 to 4 days after the initial injection, and normal responsiveness returned by 8 days after the initial exposure to LPS. Further experiments described herein demonstrate that the acquisition and maintenance of the tolerant state coincides temporally with an increase in the number of macrophage progenitor cells in the bone marrow. Cell-sizing profiles of the bone marrow cells from tolerized mice indicate an enrichment for a population of cells that are significantly larger than in bone marrow preparations from control mice. By density gradient sedimentation, it was shown that the denser population of cells from tolerized mice contained the increased numbers of progenitor cells, which, by cytology, were immature monocytic cell types. The increased numbers of macrophage progenitors was sustained after a second (challenge) injection of LPS. These results indicate that early endotoxin tolerance is associated with an increase in a population of bone marrow cells that is enriched for macrophage progenitors and suggests the possibility that the lack of responsiveness observed during the hyporesponsive period is related to a failure of these immature cell types to respond to LPS.     

Functional changes in human leukemic cell line HL-60. A model for myeloid differentiation

Polar solvents induce terminal differentiation in the human promyelocytic leukemia cell line HL-60. The present studies describe the functional changes that accompany the morphologic progression from promyelocytes to bands and poly-morphonuclear leukocytes (PMN) over 9 d of culture in 1.3 percent dimethylsulfoxide (DMSO). As the HL-60 cells mature, the rate of O(2-) production increase 18-fold, with a progressive shortening of the lag time required for activation. Hexosemonophosphate shunt activity rises concomitantly. Ingestin of paraffin oil droplets opsonized with complement or Ig increases 10-fold over 9 d in DMSO. Latex ingestion per cell by each morphologic type does not change significantly, but total latex ingestion by groups of cells increases with the rise in the proportion of mature cells with greater ingestion capacities. Degranulation, as measured by release of β-glucuronidase, lysozyme, and peroxidase, reaches maximum after 3-6 d in DMSO, then declines. HL-60 cells contain no detectable lactoferrin, suggesting that their secondary granules are absent or defective. However, they kill staphylococci by day 6 in DMSO. Morphologically immature cells (days 1-3 in DMSO) are capable of O(2-) generation, hexosemonophosphate shunt activity, ingestion, degranulation, and bacterial killing. Maximal performance of each function by cells incubated in DMSO for longer periods of time is 50-100 percent that of normal PMN. DMSO- induced differentiation of HL-60 cells is a promising model for myeloid development.     

Attention and the detectability of weak taste stimuli

Subjects detected weak solutions of sucrose or citric acid under conditions in which attention was directed toward one of the tastants or the other. Detection thresholds were measured using an adaptive, forced-choice procedure, with a three-down one-up rule, which computer simulations suggest should be more reliable than the popular two-down one-up rule. The thresholds were modestly but systematically lower for attended tastants than for unattended ones. Similar results have been reported in other sense modalities, including vision (greater sensitivity to stimuli presented to attended versus unattended spatial locations) and hearing (greater sensitivity to stimuli presented at attended versus unattended sound frequencies). Taken together, the findings are consistent with a general hypothesis regarding attention in sensory systems: gains or losses in detectability occur when a central attentional mechanism (or, conceivably, a preattentive mechanism) selectively and preferentially monitors signals arising from particular subsets of peripheral neural inputs.      

CONFIDENCE ELLIPSES APPLIED TO THE COMPARISON OF SENSORY PROFILES

Our experiment involved seven panels and six chocolates – five dark chocolates and one milk chocolate. The aim of the study was to compare the sensory profiles of the chocolates. A natural question to ask is “Did the panelists detect any differences among the five dark chocolates or did they systematically contrast them with the milk chocolate?” The scatter plot of the chocolates obtained by principal component analysis was useless to answer that question, because of the proximity of the points. To overcome that, we used confidence ellipses calculated using bootstrap. The originality of the study lies in the fact that we applied those ellipses to hierarchical multiple factor analysis (HMFA): among the seven panels, six were composed of trained professionals and the last one was composed of untrained students, and through that method, we managed to compare the two types of panels and balance the role of each trained panel. HMFA provides in a single scatter plot a representation of the six chocolates for each panel, the trained panels and all the panels. Confidence ellipses around each chocolate show that the combined panels – the six trained panels and also the untrained panel – differentiate the five dark chocolates. They also show how much larger the untrained panel's variability is than that of the trained panels, and how comparable are the trained panels' variability to each other.