Screening of Biological Activities of a Series of Chalcone Derivatives against Human Pathogenic Microorganisms

In an effort to develop new antimicrobial agents, a series of chalcone derivatives, 3 – 60 , were prepared by Claisen–Schmidt condensation of appropriate acetophenones and 2‐furyl methyl ketones with appropriate aromatic aldehydes, furfural, and thiophene‐2‐carbaldehyde in an aqueous solution of NaOH and EtOH at room temperature. The synthesized compounds were characterized by means of their IR‐ and NMR‐spectral data, and elemental analysis. All compounds were tested for their antibacterial and antifungal activities by the disc diffusion method. For the most active compounds, also minimum inhibitory concentrations (MICs) were determined.     

Effects of vegetation cover and precipitation on the process of sediment produced by erosion in a small watershed of loess region

With growing concerns over changes of the living environment and ecological environment, more and more scholars have focused their researches on understanding how vegetation covers and atmospheric conditions respond to soil erosion in watersheds. Former studies show that both the natural factors such as precipitation, vegetation, slope of terrain, soil properties and human activities are the main factors to affect the amount of sediment produced by erosion in the watershed, and there are special conditions of climate and soil that are unique to loess areas for water and soil conservations. Thus the relationships between soil erosion and vegetation and precipitation are very complicated and interesting. As a loess area, the Lergou watershed with the area of 12.1 km² lies in west of China. The watershed was a key area of high water and soil erosion forty years ago, but the area of vegetation cover has become larger because of highly effective methods of water and soil conservation. In the factors affecting the amount of sediment produced by erosion in the study area, which is more important for soil erosion: vegetation cover or precipitation? The experts, community has discussed this question for a long time. And the Lergou watershed has become the natural and ideal test watershed. Based on water observation data, climate data and NOAA/AVHRR NDVI images collected from 1982 to 2000 in the Lergou watershed of loess areas, analyses of the correlation and multi-variable regression were used to discuss the relationships among the amount of sediment produced by erosion, water indexes, precipitation factors and vegetation cover. The conclusions showed that with the increase of precipitation indexes and the decrease of plant indexes, and the amount of sediment produced by erosion in the study area would become larger. In order to distinguish the influences of erosion due to human activity and natural factors, the paper introduced multi-variable regression method by standardization data to determine the relative contributing ratio to soil erosions in the study area. The conclusions showed that the contributing ratio of vegetation cover and precipitation changes were 45.7% and 54.3%. It was obvious that the influences of precipitation were larger than those of vegetation for the soil erosion in the study area.     

Characterization of chromatin-condensing proteins during spermiogenesis in a neogastropod mollusc (Murex brandaris)

During the process of chromatin cndensation in the spermiogenesis of the neogastropod mollusc Murex brandaris, the nuclear protein complement undergoes a complex series of changes. These changes lead to the appearance of three small protamines in the ripe sperm nuclei. We have characterized this system electrophoretically and at the compositions with antibodies elicited against a specific spermatozoan protamine. Our results indicate that the complex pattern of chromatin condensation during spermiogenesis in this species (M. brandaris) may be modulated by a series of post-translational (and intranuclear) modifications of DNA-interacting proteins, such as precursors to the sperm protamines. The amino acid composition of each sperm protamine is remarkably simple (lys + arg + gly ≥96 mol%). This system of spermiogenic/spermatozoal proteins in the neogastropod M. brandaris clearly differs from that in patellogastropods and archaeogastropods, and it may be helpful in understanding evolutionary changes in the chromatin condensation pattern during the spermiogenesis of gastropod molluscs. © 1994 Wiley-Liss, Inc.     

One-step synthesis of beta-C-glycolipid derivatives from unprotected sugars

Condensations of nonsymmetrical or symmetrical beta-diketones and unprotected sugars in aq NaHCO3 soln were explored. C-glucosyl and C-maltosyl derivatives bearing lipophilic residue of 8 or 11 carbon atoms were prepared efficiently using this one-step procedure. The amphiphilic properties of these compounds were demonstrated by measuring their CMC.     

Interplay between activator-inhibitor coupling and cell-matrix adhesion in a cellular automaton model for chondrogenic patterning

We present a stochastic cellular automaton model for the behavior of limb bud precartilage mesenchymal cells undergoing chondrogenic patterning. This "agent-oriented" model represents cells by points on a lattice that obey rules motivated by experimental findings. The "cells" follow these rules as autonomous agents, interacting with other cells and with the microenvironments cell activities produce. The rules include random cell motion, production and lateral deposition of a substrate adhesion molecule (SAM, corresponding to fibronectin), production and release of a diffusible growth factor ("activator," corresponding to TGF-beta) that stimulates production of the SAM, and another diffusible factor ("inhibitor") that suppresses the activity of the activator. We implemented the cellular automaton on a two-dimensional (2D) square lattice to emulate the quasi-2D micromass culture extensively used to study patterning in avian limb bud precartilage cells. We identified parameters that produce nodular patterns that resemble, in size and distribution, cell condensations in leg-cell cultures, thus establishing a correspondence between in vitro and in silico results. We then studied the in vitro and in silico micromass cultures experimentally. We altered the standard in vitro micromass culture by diluting the initial cell density, transiently exposing it to exogenous activator, suppressing the inhibitor, and constitutively activating fibronectin production. We altered the standard in silico micromass culture in each case by changing the corresponding parameter. In vitro and in silico experiments agreed well. We also used the model to test hypotheses for differences in the in vitro patterns of cells derived from chick embryo forelimb and hindlimb. We discuss the applicability of this model to limb development in vivo and to other organ development.     

The condensin complex is required for proper spindle assembly and chromosome segregation in Xenopus egg extracts

Chromosome condensation is required for the physical resolution and segregation of sister chromatids during cell division, but the precise role of higher order chromatin structure in mitotic chromosome functions is unclear. Here, we address the role of the major condensation machinery, the condensin complex, in spindle assembly and function in Xenopus laevis egg extracts. Immunodepletion of condensin inhibited microtubule growth and organization around chromosomes, reducing the percentage of sperm nuclei capable of forming spindles, and causing dramatic defects in anaphase chromosome segregation. Although the motor CENP-E was recruited to kinetochores pulled poleward during anaphase, the disorganized chromosome mass was not resolved. Inhibition of condensin function during anaphase also inhibited chromosome segregation, indicating its continuous requirement. Spindle assembly around DNA-coated beads in the absence of kinetochores was also impaired upon condensin inhibition. These results support an important role for condensin in establishing chromosomal architecture necessary for proper spindle assembly and chromosome segregation.     

饮茶摄氟量的探讨

饮茶摄氟量取决于三个要素：饮茶方式、茶氟富集量与氟浸出率,其中茶氟富集量是首要因素。茶水含氟量以一泡茶水最高,二泡茶水次之,三泡及其以后的茶水含氟量急剧下降。茶叶中富集的氟,基本上是水溶性化合物。饮茶过程中约有４２％～８６％的氟溶于茶汤被人体摄入。饮茶摄氟量关系到饮茶与人体健康,摄氟量过高,会造成氟中毒。     

Mutations disturbing the condensation of plastid nucleoids inChlamydomonas reinhardtii

Summary To study the mechanism of condensation of dispersed plastid (pt) nucleoids into a single pt nucleoid with aging of the cells ofChlamydomonas reinhardtii, two mutants, designated cond-1 and cond-2, were isolated. A plastid of a wild type cell, 6.5 m in diameter, contained ten dispersed spherical pt nucleoids within one week of culture on an agar plate. At about one week of culture, the cell number was saturated and pt nucleoids began to associate with each other, condensing into a single pt nucleoid at three weeks of culture. In contrast, cond-1 and cond-2 cells, which had about 20 and 45 pt nucleoids and whose cell diameters were 7.8 and 9.5 m at one week of culture respectively, still had about 10 and 20 pt nucleoids at even 7 weeks of culture. Doubling times of the three cell types were similar. From genetic analysis, each of the two mutants had one gene mutation. The two mutations are probably linked. The measurement of O₂ evolution showed that the two mutations did not affect the photosynthetic system. Lipid contents of the two mutant cells were clearly higher than that of wild type cells. The role of a higher number of pt nucleoids is probably to increase the activity of lipid and/or membrane synthesis for lipid storage.