Effects of cuticle structure and crystalline wax coverage on the coloration in young and old males of Calopteryx splendens and Calopteryx virgo

Male secondary sexual characters, such as color patterns, are often investigated at the macroscale level. However, micro- and nanoscale levels of morphological investigations may reveal functional features responsible for a particular coloration, thus providing more information, e.g., about the condition dependence of male sexual characters. The aim of this paper was to investigate cuticle color and its structure in males of two congeneric damselfly species, Calopteryx splendens and Calopteryx virgo, and reveal possible color changes with age. According to spectrometer measurements, C. splendens males were bluer and had a greater saturation of blue in their abdomen than C. virgo males, which were, in turn, greener and had more green saturation. Although the two species differed in the number of structural layers and the spacing of the layers, it seems that intactness of the wax crystals covering the epicuticle was most often the morphological trait which was related to the color parameters measured from males’ cuticles. The effect of the crystalline wax coverage on cuticle color was also confirmed by removing the wax using chloroform: after the treatment, the hue was bluer, the cuticle had a greater brightness and greater blue saturation, but less green saturation. Age differences influencing the color and structure of the cuticle were also observed: older males had more blue and green saturation and had more intact wax coverage than did younger males. Although multilayer reflection should be responsible for the iridescent color of males, our results suggest that wax coverage plays an important role in the color tuning of the male cuticle. This may have a considerable signal function, indicating the males’ viability to competing males or to females.     

The N intermediate of bacteriorhodopsin at low temperatures: stabilization and photoconversion

In aqueous suspensions of purple membranes (pH 10.2, 0.4 M KCl) an intermediate having an absorption maximum at 570-575 nm (at -196 degrees C) was produced by first heating the M intermediate up to -30 degrees C and then stabilizing it by subsequent cooling to -60 degrees C. We suggest that this species is the intermediate N (or P or R) found and characterized earlier near room temperature. Upon illumination at -196 degrees C N is transformed into a bathochromically absorbing species KN which has an absorption maximum near 605 nm and an extinction 1.35 times that of N. This light reaction is photoreversible. The quantum yield ratio for the forward and back reaction is 0.18 +/- 0.02. The maximum photo steady state concentration of KN is about 0.24. The N intermediate was also trapped in water suspensions of purple membranes at neutral pH and low salt concentration by illumination at lambda greater than 620 nm during cooling. In addition to N another intermediate absorbing in the red (maximum at 610-620 nm) was accumulated in smaller amounts. It is not photoactive at -196 degrees C and apparently is the O intermediate or a photoproduct of N.     

Regulation of Nostoc sp. phycobilisome structure by light and temperature.

Nostoc sp. strain MAC cyanobacteria were green in color when grown in white light at 30 degrees C and contained phycobilisomes that had phycoerythrin and phycocyanin in a molar ratio of 1:1. Cells grown for 4 to 5 days in green light at 30 degrees C or white light at 39 degrees C turned brown and contained phycoerythrin and phycocyanin in a molar ratio of greater than 2:1. In addition to the change in pigment composition, phycobilisomes from brown cells were missing a 34.5-kilodalton, rod-associated peptide that was present in green cells. The green light-induced changes were typical of the chromatic adaptation response in cyanobacteria, but the induction of a similar response by growth at 39 degrees C was a new observation. Phycobilisomes isolated in 0.65 M phosphate buffer (pH 7) dissociate when the ionic strength or pH is decreased. Analysis of the dissociation products from Nostoc sp. phycobilisomes suggested that the cells contained two types of rod structures: a phycocyanin-rich structure that contained the 34.5-kilodalton peptide and a larger phycoerythrin-rich complex. Brown Nostoc sp. cells that lacked the 34.5-kilodalton peptide also lacked the phycocyanin-rich rod structures in their phycobilisomes. These changes in phycobilisome structure were indistinguishable between cells cultured at 39 degrees C in white light and those cultured at 30 degrees C in green light. A potential role is discussed for rod heterogeneity in the chromatic adaptation response.     

Manipulating the salt and thermal stability of DNA multilayer films via oligonucleotide length

DNA films are promising materials for diverse applications, including sensing, diagnostics, and drug/gene delivery. However, the ability to tune the stability of DNA films remains a crucial aspect for such applications. Herein, we examine the role of oligonucleotide length on the formation, and salt and thermal stability, of DNA multilayer films using oligonucleotides of homopolymeric diblocks (polyAG and polyTC), with each block (A, G, T, or C) ranging from 5 to 30 bases (10-, 20-, 30-, 40-, and 60-mer). Using a combination of quartz crystal microgravimetry, dual polarization interferometry, and flow cytometry, we demonstrate that at least 10 bases per hybridizing block in the DNA diblocks (that is, 20-mer) are required for successful hybridization and, hence, DNA multilayer film formation. Films assembled using longer oligonucleotide blocks were more stable in low salt conditions, with the DNA multilayer films assembled from the 60-mer oligonucleotides remaining intact in solutions of about 25 mM NaCl. A systematic increase in film melting temperature ( T m) was observed for the DNA multilayer films (assembled on colloids) with increasing oligonucleotide length, ranging from 38.5 degrees C for the 20-mer films to 53 degrees C for the 60-mer films. Further, an alternating trend in T m of the DNA multilayer films was observed with layer number (AG or TC); DNA multilayer films terminated with an AG layer exhibited a higher T m (44-49 degrees C) than films with an outermost TC layer (ca. 38 degrees C), suggesting a rearrangement of the film structure upon hybridization of the outermost layer. This work shows that the stability of DNA multilayer films can be tuned by varying the length of the oligonucleotide building blocks, thus providing a versatile means to tailor the salt and thermal stability of DNA films, which is necessary for the application of such films.     

Wing colors based on arrangement of the multilayer structure of wing scales in lycaenid butterflies (Insecta: Lepidoptera)

Male wing colors and wing scale morphology were examined for three species of lycaenid butterflies: Chrysozephyrus ataxus, Favonius cognatus and F. jezoensis. Measurement of spectral reflectance on the wing surface with a spectrophotometer revealed species‐specific reflection spectra, with one or two peaks in the ultraviolet and/or green ranges. Observations of wing scales using an optical microscope revealed that light was reflected from the inter‐ridge regions, where transmission electron microscopy revealed a multilayer structure. Based on the multilayer dimensions obtained, three models were devised and compared to explain the measured reflectance spectrum. The results showed that the best fit is a model in which thicknesses of thin films of the multilayer system are not constant and air spaces between cuticle layers are more or less packed with cuticle spacers. This suggests that the specific wing colors of the species examined are produced by the species‐specific arrangement of the multilayer structure of wing scales.     

Self-aggregation of synthetic zinc chlorophyll derivatives possessing multi-perfluoroalkyl chains in perfluorinated solvents.

Zinc 3(1)-hydroxy-13(1)-oxo-chlorins possessing two, three, four and six perfluorooctyl chains were synthesized from naturally occurring chlorophyll-a. Only the synthetic zinc chlorin possessing six perfluorooctyl chains was directly dissolved in perfluorinated solvents due to its high fluorine content in molecular weight (over 50%). In this solution, visible absorption spectra gave a red-shifted Q(y) band at 723 nm (compared to 648 nm in THF) and showed the formation of well-ordered self-aggregates. No monomeric form was observed in the solution from any fluorescence emission spectra from visible absorption spectra. In the aggregate solution, no precipitation occurred during either standing for a long period or heating at 70 degrees C. This showed that the supramolecular structure was stabilized by F-F interactions on its surface among the perfluorooctyl chains on the 17-position and perfluorinated solvents. The core part of the supramolecular structure was constructed by a special intramolecular bond of Zn ... O3(2)-H ... O=C13(1), which was confirmed from resonance Raman spectral analysis.     

Changes in the spectral properties of a plasma membrane lipid analog during the first seconds of endocytosis in living cells.

N-[5-(5, 7-dimethyl Bodipy)-1-pentanoyl]-D-erythro-sphingosylphosphorylcholine (C5-DMB-SM), a fluorescent analog of sphingomyelin, has been used in a study of the formation of very early endosomes in human skin fibroblasts. This lipid exhibits a shift in its fluorescence emission maximum from green (approximately 515 nm) to red (approximately 620 nm) wavelengths with increasing concentrations in membranes. When cells were incubated with 5 microM C5-DMB-SM at 4 degrees C and washed, only plasma membrane fluorescence (yellow-green) was observed. When these cells were briefly (< or = 1 min) warmed to 37 degrees C to allow internalization to occur, and then incubated with defatted bovine serum albumin (back-exchanged) at 11 degrees C to remove fluorescent lipids from the plasma membrane, C5-DMB-SM was distributed in a punctate pattern throughout the cytoplasm. Interestingly, within the same cell some endosomes exhibited green fluorescence, whereas others emitted red-orange fluorescence. Furthermore, the red-orange endosomes were usually seen at the periphery of the cell, while the green endosomes were more uniformly distributed throughout the cytoplasm. This mixed population of endosomes was seen after internalization times as short as 7 s and was also seen over a wide range of C5-DMB-SM concentrations (1-25 microM). Control experiments established that the variously colored endosomes were not induced by changes in pH, membrane potential, vesicle size, or temperature. Quantitative fluorescence microscopy demonstrated that the apparent concentration of the lipid analog in the red-orange endosomes was severalfold higher than its initial concentration at the plasma membrane, suggesting selective internalization (sorting) of the lipid into a subset of early endosomes. Colocalization studies using C5-DMB-SM and either anti-transferrin receptor antibodies or fluorescently labeled low-density lipoprotein further demonstrated that this subpopulation of endosomes resulted from receptor-mediated endocytosis. We conclude that the spectral properties of C5-DMB-SM can be used to distinguish unique populations of early endosomes from one another and to record dynamic changes in their number and distribution within living cells.     

瓜实蝇对虚拟波长下不同颜色的趋性（英文）

利用害虫对不同颜色的趋性进行害虫防治, 如利用黄板对实蝇的监测和防治已有很长的历史, 然而尚未见把颜色量化进行实蝇对颜色偏嗜性研究的报道。为探明对瓜实蝇Bactrocera cucurbitae最具吸引力的颜色及其虚拟波长, 本试验应用Dan Bruton的虚拟波长与RGB值的函数关系, 把RGB值转换为虚拟波长; 选择RGB值［(0, 213, 255), (0, 255, 146), (54, 255, 0), (129, 255, 0), (195, 255, 0), (255, 255, 0), (255, 190, 0)和 (255, 119, 0)］的颜色进行打印, 这些颜色对应的虚拟波长分别是480, 500, 520, 540, 560, 580, 560和600 nm; 在八面体内进行瓜实蝇对8种颜色的偏嗜性试验。结果表明： 波长在520~560 nm 之间对应的颜色对瓜实蝇的吸引率高于其他虚拟波长对应的颜色, 而540 nm (黄绿色, RGB值为 129, 255, 0)对应的颜色纸对瓜实蝇的吸引率最大。此外田间颜色偏嗜性试验也证实了黄绿色对瓜实蝇有最强的引诱作用。结果说明, 黄绿色（虚拟波长540 nm）是吸引瓜实蝇的关键颜色, 黄绿色粘虫板可作为监测与防治瓜实蝇的一种有效方法。     

Effect of heat on the adsorption capacity of an activated carbon for decolorizing/deodorizing yellow zein

The Freundlich model was evaluated for use to assess the effect of heat on the adsorption capacity of an activated carbon for decolorizing/deodorizing corn zein. Because zein protein and its color/odor components are all adsorbed by activated carbon, a method to monitor their removal was needed. Yellow color is due to xanthophylls; a contributor to off-odor is diferuloylputrescine. The off-odor component absorbs ultraviolet (UV) light at about 325 nm and its removal coincides with removal of yellow color. A spectrophotometric method based on UV absorbances 280 nm for protein and 325 nm for the off-odor component was used to monitor their adsorptions onto activated carbon. Equilibrium studies were performed over temperature range from 25 to 60 degrees C for zein dissolved in 70% aqueous ethanol. Runs made at 55 degrees C adsorbed significantly more of the color/odor components than the protein.     

Green hemoprotein of erythrocytes: methemoglobin superoxide transferase

Influences of base (pH 10), heat (50 degrees C), microwave radiation (2450 MHz, 103 +/- 4 W/kg), and hydrogen peroxide (5.6 mM) generated by glucose oxidase on oxidation of human oxyhemoglobin to methemoglobin were examined. Conversion of oxyhemoglobin to methemoglobin was followed by the difference in absorbancy of 540 or 542 nm and 576 nm wavelength light versus time. Fresh basic hemolysates auto-oxidized on heating with a zero order rate constant, implying that hemoglobin or another protein saturated with oxyhemoglobin catalyzed the oxidation. Simultaneous microwave irradiation inhibited thermally induced auto-oxidation on the average by 28.6%. However, there was great variability among samples and a decrease in auto-oxidation with aging of individual samples. The auto-oxidation rate was independent of initial oxyhemoglobin concentration. Oxidation of partially purified oxyhemoglobin by hydrogen peroxide was not influenced by microwave irradiation. Adding green hemoprotein isolated from human erythrocytes to the oxyhemoglobin/glucose oxidase reaction mixture yielded absorption spectra (500-600 nm) that were a combination of oxyhemoglobin, deoxyhemoglobin, and methemoglobin spectra. Green hemoprotein was labile in hemolysates but stable in a partially purified ferric form. These results imply that thermally unstable reduced green hemoprotein can reverse oxidation of oxyhemoglobin by hydrogen peroxide and could mediate the thermally induced and microwave inhibited auto-oxidation of oxyhemoglobin.     

Thermal-induced changes in the secondary conformation of superoxide dismutase containing different metal ions

The thermal stability of three superoxide dismutases (SODs) with different metal ions (Mn, Cu/Zn, Fe) in the solid state was studied by a Fourier transform infrared (FT-IR) microspectroscopy combined with thermal analyzer. The IR spectra showed a maximum peak at 1652 cm(-1) for all the native SODs in the amide I band, suggesting a predominant random coil with less alpha-helix structures. By heating each sample, a shoulder at 1631 cm(-1) in the amide I band gradually appeared from 45 degrees C for Fe SOD and from 50 degrees C for Mn SOD but another shoulder at 1639 cm(-1) appeared from 50 degrees C for Cu/Zn SOD. The peak at 1631 cm(-1) is due to the intermolecular beta-sheet structure, but the peak at 1639 cm(-1) corresponds to the major intramolecular beta-sheet with less random coil structure. This reveals that in the first heating process the transformation from random coil/alpha-helix structure to beta-sheet structure initiated from around 45-50 degrees C. There was about 16-22% compositional change resulting from that transformation. However, both additional shoulders stood there and did not restore to their original spectra even with cooling to room temperature, suggesting the denaturation and irreversible properties of the solid SODs after heating. The thermal-dependent denaturation and irreversibility of Mn SOD, Cu/Zn SOD and Fe SOD were clearly evidenced by the increase in intramolecular and intermolecular beta-sheet structure.     

Species‐dependent microarchitectural traits of iridescent scales in the triad taxa of Ornithoptera birdwing butterflies

Ornithoptera birdwing butterflies have blue, green, or orange iridescent scales in different species or subspecies. To understand the species‐ or subspecies‐dependent scale color differences, we performed comparative morphometric analyses of iridescent scales from three closely related taxa: O. priamus priamus (green), O. priamus urvillianus (blue), and O. croesus (orange). The three types of Ornithoptera wings exhibited reversible color changes to longer wavelengths with different kinetics upon immersion in methanol, suggesting that their color differences are at least partly based on differences in the size of air cavities made by nanostructures. Cover scales of all three color types were visually semi‐transparent glass scales that exhibited color when placed on a dark background. The dorsoventral differences in coloration were observed in single scales, suggesting the optical importance of scale surfaces. Scanning electron microscopy of cover scales in cross section revealed that all color types exhibited finely sculpted tapered ridges and thick, irregular basal multilayers containing tandemly clustered granular objects and air cavities. Scale thickness, ridge height, and multilayer thickness were significantly different among the three color types, and granular object size was significantly different between orange scales and blue and green scales. We conclude that each of the three taxa of Ornithoptera butterflies possesses unique quantitative size values on tapered ridges and irregular multilayers with granular objects and air cavities to express unique structural color. These species‐ or subspecies‐dependent structural colors might have evolved via quantitative shifts in these microarchitectural traits rather than via changes in the basic developmental or architectural plan for color expression.     

Hsp85 conformational change within the heat shock temperature range.

One of the major mammalian heat shock proteins, hsp85, aggregates extensively when heated in the presence of non-ionic detergents (J Cell. Physiol. 140: 601-607, 1989). The present study used intrinsic fluorescence and susceptibility to tryptic proteolysis to probe hsp85 conformation within the physiological and heat shock temperature ranges. Fluorescence intensity decreased and the emission spectrum was red-shifted (2.5 nm) as hsp85 was heated from 15 degrees to 50 degrees C. Upon heating in the absence of detergent, the red shift, monitored by the ratio of fluorescence emission at 330 nm to that at 350 nm, began at 38 degrees-45 degrees C with a transition midpoint at 45 degrees-50 degrees C, depending on the rate of temperature increase. This transition was masked by 1% n-octyl-O-glucoside - a detergent previously shown to promote aggregation. The spectral changes were not reversible upon cooling to 15 degrees C. Susceptibility to proteolysis in the absence of detergent, measured by the degradation of characteristic large fragments, increased sharply between 40 degrees C and 45 degrees C. These findings suggest that hsp85 undergoes a major conformational change within the range of temperatures known to induce hsp synthesis. This change is consistent with partial unfolding which exposes additional sites to the aqueous environment and influences detergent binding.     

Influence of the sporulation temperature upon the heat resistance of Bacillus subtilis.

The influence of different sporulation temperatures (30, 37, 44 and 52 degrees C) upon heat resistance of Bacillus subtilis was investigated. Heat resistance was greater after higher sporulation temperatures. Relation of heat resistance and temperature of sporulation was not linear over all the range of temperatures tested. Heat resistance increased about tenfold in the range of 30-44 degrees C. Sporulation at 52 degrees C did not show any further increase in heat resistance. This effect was constant over all the range of heating temperatures tested (100-120 degrees C). z value remained constant (z = 9 degrees C). Greater heat resistances at higher temperatures of sporulation were not due to selection of more heat resistant cells by a higher sporulation temperature. Spores obtained from cells incubated at 32 or 52 degrees C always possessed heat resistances that corresponded to the sporulation temperature regardless of the incubation temperature of their vegetative cells.     

Exposure to pretreatment hypothermia as a determinant of heat killing

When Chinese hamster ovary (CHO) cells were exposed to 22 degrees C for 2 hr prior to 42.4 degrees C hyperthermia, neither the shoulder region of the survival curve nor the characteristic development of thermotolerance after 3-4 hr of heating were observed. Absolute cell survival after 4 hr at 42.4 degrees C was decreased by a factor of between 10 and 100 (depending on the rate of heating of nonprecooled controls). Conditioning at 30 degrees C for 2 hr, 26 degrees C for 2 hr, or 22 degrees C for 20 min followed by heating to 42.4 degrees C over 30 min did not result in sensitization. Prolonged (16 hr) conditioning at 30 degrees C, however, increased the cytotoxicity of immediate exposure to 41.4 or 45 degrees C with maximum sensitization to 45 degrees C occurring after 6 hr at 30 degrees C. Both 3- and 18-hr pretreatments at 30 degrees C similarly increased the cytotoxicity of 45-41.5 degrees C step-down heating (D0 = 28 min in precooled versus 40 min in nonprecooled cells).     

Phylogenetic characterization of microbial mats and streamers from a Japanese alkaline hot spring with a thermal gradient

Dense microbial mats and streamers of various colors developed in an alkaline-hot spring water at 48-76 degrees C and ~0.077 mm sulfide in Nakabusa, Japan. The microbial community structures with a thermal gradient were compared by denaturing gradient gel electrophoresis (DGGE) analysis of the PCR-amplified 16S ribosomal RNA gene fragments. The sequence analysis revealed that a predominant cyanobacterial DGGE band phylogenetically related to Synechococcus elongatus was detected only from green mats at 48 degrees C. Four DGGE bands were detected commonly from green mats at 48 degrees C, orange mats at 58 degrees C and brown mats at 60 degrees C. The sequence analysis revealed that these were phylogenetically related to Chloroflexaceae group, Rhodothermus group, a candidate division OP10, and an unclassified bacterium. On the other hand, Aquificae-, Thermodesulfobacteria-, Thermus group-, and Crenarchaeota-like sequences were detected as a predominant component of DGGE profiling from the streamers only at temperatures over 66 degrees C, but no phototrophic bacterial bands were detected. Thus, the microbial community structure above 60 degrees C was drastically different from that at the lower temperatures. After the addition of hydrogen into in vitro gray streamers with in situ spring water, sulfide production markedly occurred in the presence of ambient sulfate at 66 degrees C. This result suggests that in situ sulfide is partly produced by Thermodesulfobacteria-like sulfate-reducing bacteria in the streamers.     

橙色荧光蛋白——绿色荧光蛋白GFPxm的改造

最近报道了从大型多管水母中分离出新的gfp基因。经大肠杆菌表达并纯化出的绿色荧光蛋白 (GFPxm)具有 4 76nm的激发峰和 4 96nm的发射峰 ,但是只能在低温下成熟的缺点限制了它的应用。这里进一步报道GFPxm的 12种突变型。在大肠杆菌中的表达结果表明 ,有 7种突变型在 37℃条件下产生高的荧光强度。在 2 5、32和 37℃条件下表达 6h ,GFPxm16、GFPxm18和GFPxm19的相对荧光强度均高于增强型绿色荧光蛋白 (EGFP) ,而GFPxm16和GFPxm16 3在 4 2℃高温表达时仍能保持高的荧光强度。这 7种突变型中的 4种在哺乳动物细胞中已获得良好表达。此外 ,有 6种突变型的荧光光谱红移 ,目前所达到的最长激发峰为 5 14nm、最长发射峰为 5 2 5nm。另外有 3种突变型具有包括紫外在内的两个激发峰 ,1种突变型只有单一的紫外激发峰。首次报道具有橙色荧光的突变型OFPxm ,它的激发峰为 5 0 9nm、发射峰为 5 2 3nm。 5 2 3nm属于黄绿色 ,但肉眼看到的蛋白为橙色。OFPxm在高温下可得到高水平表达且很好地成熟 ,但是因为低的量子产率而荧光强度相对较低。     

不同颜色光对野菊花色素溶液稳定性及类胡萝卜素含量的影响

在黑暗（对照）、红光、绿光、蓝光、黄光和白光条件下,对来源于野菊[Dendranthema indicum（Linn．）Des．Moul．]头状花序乙醚提取物的色素溶液中类胡萝卜素含量及色价和色差的变化进行了研究,并对色价和色差与贮藏时间的相关性进行了分析。结果表明：在不同颜色光照条件下,随贮藏时间（0—50d）的延长,溶液中类胡萝卜素含量及412、436和468nm特征波长下溶液的色价均呈逐渐下降的趋势,溶液的色彩参数（L＊、n＊和b＊）则呈现不同的变化规律。贮藏前后类胡萝卜素含量差异极显著（P〈0．01）且与贮藏时间呈显著负相关;在贮藏至50d时,在红光、蓝光、白光、黄光、绿光和黑暗条件下类胡萝卜素含量降幅依次为98．97％、98．33％、95．10％、92．30％、80．38％和17．02％。贮藏10—50d溶液色价均显著小于起始色价（P〈0．05）,其中,在黑暗条件下色价的变化均最小且显著高于其他处理组,而在红光照射下色价降幅最大。在黑暗条件下,溶液亮度增加、色彩变化不明显;而在其他颜色光照条件下,色素溶液均由绿转红、由黄向蓝转变,且与对照相比a＊值显著增大、b＊值显著降低（P〈0．05）,但溶液亮度总体上无显著差异（P〉O．05）。在0—50d的贮藏期内,溶液的色价和色差与储藏时间均呈线形关系,溶液的褪色规律均符合一次降解曲线。研究结果显示：野菊花所含的类胡萝卜素类色素对红光、绿光、蓝光、黄光和白光均较敏感,光照时间越长分解越激烈;在实际应用过程中这类色素应避光保存。     

Effect of cycloheximide or puromycin on induction of thermotolerance by sodium arsenite in Chinese hamster ovary cells: involvement of heat shock proteins

After sodium arsenite (100 microM) treatment, the synthesis of three major heat shock protein families (HSPs; Mr = 110,000, 87,000, and 70,000), as studied with one-dimensional gels, was enhanced twofold relative to that of unheated cells. The increase of unique HSPs, if studied with two-dimensional gels, would probably be much greater. In parallel, thermotolerance was observed as a 100,000-fold increase in survival from 10(-6) to 10(-1) after 4 hr at 43 degrees C, and as a thermotolerance ratio (TTR) of 2-3 at 10(-3) isosurvival for heating at 45.5 degrees C. Cycloheximide (CHM: 10 micrograms/ml) or puromycin (PUR: 100 micrograms/ml), which inhibited total protein synthesis and HSP synthesis by 95%, completely suppressed the development of thermotolerance when either drug was added after sodium arsenite treatment and removed prior to the subsequent heat treatment. Therefore, thermotolerance induced by arsenite treatment correlated with an increase in newly synthesized HSPs. However, with or without arsenite treatment, CHM or PUR added 2-6 hr before heating and left on during heating caused a 10,000-100,000-fold enhancement of survival when cells were heated at 43 degrees C for 4 hr, even though very little synthesis of heat shock proteins occurred. Moreover, these cells manifesting resistance to heating at 43 degrees C after CHM treatment were much different than those manifesting resistance to 43 degrees C after arsenite treatment. Arsenite-treated cells showed a great deal of thermotolerance (TTR of about 10) when they were heated at 45 degrees C after 5 hr of heating at 43 degrees C, compared with less thermotolerance (TTR of about 2) for the CHM-treated cells heated at 45 degrees C after 5 hr of heating at 43 degrees C. Therefore, there are two different phenomena. The first is thermotolerance after arsenite treatment (observed at 43 degrees C or 45.5 degrees C) that apparently requires synthesis of HSPs. The second is resistance to heat after CHM or PUR treatment before and during heating (observed at 43 degrees C with little resistance at 45.5 degrees C) that apparently does not require synthesis of HSPs. This phenomenon not requiring the synthesis of HSPs also was observed by the large increase in thermotolerance to 45 degrees C caused by heating at 43 degrees C, with or without CHM, after cells were incubated for 6 hr following arsenite pretreatment. For both phenomena, a model based on synthesis and redistribution of HSPs is presented.     

In situ observation of crystal growth for poly[(S)-lactide] by temperature-controlled atomic force microscopy

The crystallization behavior and crystalline morphologies of poly[(S)-lactide] (P[(S)-LA]) in thin films crystallized isothermally at over 160 degrees C were characterized by transmission electron microscopy and atomic force microscopy (AFM). The dendritic crystal and hexagonal crystal were formed in thin film with thicknesses below 30 nm or over 50 nm, respectively. The crystal structures of dendritic and hexagonal crystals were identical, suggesting that the crystalline morphology of P[(S)-LA] is strongly dependent upon the film thickness. In situ observation of the crystal growth in the P[(S)-LA] thin film at 165 degrees C from the melt was carried out by using temperature-controlled AFM equipped with a heating stage. The initial stage of crystallization and development of lamellae were successfully observed during isothermal crystallization at 165 degrees C. The first forming crystal showed the edge-on orientation, and grew to S-shaped edge-on lamellae. Dendritic flat-on crystals were developed from the S-shaped edge-on lamellae. The growth rates of flat-on and edge-on lamellae were almost identical.