Intra-specific Variation in Virulence and In Vitro Production of Macromolecular Toxins Active Against Locust Among Beauveria bassiana Strains and Effects of In Vivo and In Vitro Passage on These Factors

Strains of Beauveria bassiana isolated from locust or from the soil varied considerably in their virulence and their ability to produce in vitro toxic metabolites against Locusta migratoria. Among the pathogenic isolates, only culture filtrates of 90/2-Dm, 92/11-Dm and 0023-Su were toxic by injection, a result which demonstrates that isolates of B. bassiana can be pathogenic for L. migratoria whether they secrete toxic metabolites in vitro or not. Toxic metabolites secreted by strains 90/2-Dm and 92/11-Dm were macromoleculer as they were retained by dialysis (cutoff of 6./8 kDa for globular proteins), whereas those secreted by 0023-Su were not. The effect of in vitro passage on virulence and on toxicogenic activity of isolate 90/2-Dm was dependent on the mycological media the inoculum was produced on. The virulence of isolate 90/2-Dm was significantly reduced after two passages through Sabouraud Dextrose Agar (SDA&rpar whereas two passages through Malt Agar (MA) increased its virulence and its toxicogenic activity. Nevertheless, the most aggressive conidia and the most toxic macromolecules were obtained after two passages of the isolate 90/2-Dm through the host. The bioactive macromolecules present in the crude filtrate of isolate 90/2-Dm were precipitated by 90% saturation of ammonium sulphate, and the insecticidal activity was exclusively detected in high molecular mass fraction after gel filtration on Sephadex G-25. In addition, the insecticidal effect of the Sephadex G-25 fraction was significantly reduced after exposure for 2 h at 608C and 20 min at 1208C, suggesting that the insecticidal metabolites in the culture filtrates of isolate 90/2-Dm were proteinaceous.     

细胞内的大分子拥挤环境

所有的细胞中都存在着大量的蛋白质、核酸、多糖等各种生物大分子,它们大约占用细胞容积的20%～30%,总浓度高达80～200 g/L,因此任何一种大分子都处于一个充满其他大分子的拥挤环境中. 对源于排斥容积效应的拥挤理论分析表明它对所有大分子之间的反应在热力学和动力学上都有很大的影响. 可是以往人们在体外研究生物大分子的性质和相互作用时几乎都忽略了这样一个细胞大分子拥挤的实际环境. 最近几年建议把大分子拥挤与pH、离子强度和溶液组成等一样作为常规因素来研究生物大分子的呼声很高,在体系中添加大分子拥挤试剂以在体外模拟细胞内环境研究蛋白质折叠已有一些实验报道.     

A meta‐analysis of temperature sensitivity as a microbial trait

Traits‐based approaches in microbial ecology provide a valuable way to abstract organismal interaction with the environment and to generate hypotheses about community function. Using macromolecular rate theory (MMRT), we recently identified that temperature sensitivity can be characterized as a distinct microbial trait. As temperature is fundamental in controlling biological reactions, variation in temperature sensitivity across communities, organisms, and processes has the potential to vastly improve understanding of microbial response to climate change. These microbial temperature sensitivity traits include the heat capacity (), temperature optimum (T_opt), and point of maximum temperature sensitivity (TS_max), each of which provide unique insights about organismal response to changes in temperature. In this meta‐analysis, we analyzed the distribution of these temperature sensitivity traits from bacteria, fungi, and mixed communities across a variety of biological systems (e.g., soils, oceans, foods, wastewater treatment plants) in order to identify commonalities in temperature responses across these diverse organisms and reaction rates. Our analysis of temperature sensitivity traits from over 350 temperature response curves reveals a wide distribution of temperature sensitivity traits, with T_opt and TS_max well within biological relevant temperatures. We find that traits vary significantly depending on organism type, microbial diversity, source environment, and biological process, with higher temperature sensitivity found in fungi than bacteria and in less diverse systems. Carbon dioxide production was found to be less temperature sensitive than denitrification, suggesting that changes in temperature will have a potentially larger impact on nitrogen‐related processes. As climate changes, these results have important implications for basic understanding of the temperature sensitivity of biological reactions and for ecological understanding of species’ trait distributions, as well as for improved treatment of temperature sensitivity in models.     

Embracing a new paradigm for temperature sensitivity of soil microbes

The temperature sensitivity of soil processes is of major interest, especially in light of climate change. Originally formulated to explain the temperature dependence of chemical reactions, the Arrhenius equation, and related Q₁₀ temperature coefficient, has a long history of application to soil biological processes. However, empirical data indicate that Q₁₀ and Arrhenius model are often poor metrics of temperature sensitivity in soils. In this opinion piece, we aim to (a) review alternative approaches for characterizing temperature sensitivity, focusing on macromolecular rate theory (MMRT); (b) provide strategies and tools for implementing a new temperature sensitivity framework; (c) develop thermal adaptation hypotheses for the MMRT framework; and (d) explore new questions and opportunities stemming from this paradigm shift. Microbial ecologists should consider developing and adopting MMRT as the basis for predicting biological rates as a function of temperature. Improved understanding of temperature sensitivity in soils is particularly pertinent as microbial response to temperature has a large impact on global climate feedbacks.     

Role of solvent properties of aqueous media in macromolecular crowding effects

Analysis of the macromolecular crowding effects in polymer solutions show that the excluded volume effect is not the only factor affecting the behavior of biomolecules in a crowded environment. The observed inconsistencies are commonly explained by the so-called soft interactions, such as electrostatic, hydrophobic, and van der Waals interactions, between the crowding agent and the protein, in addition to the hard nonspecific steric interactions. We suggest that the changes in the solvent properties of aqueous media induced by the crowding agents may be the root of these “soft” interactions. To check this hypothesis, the solvatochromic comparison method was used to determine the solvent dipolarity/polarizability, hydrogen-bond donor acidity, and hydrogen-bond acceptor basicity of aqueous solutions of different polymers (dextran, poly(ethylene glycol), Ficoll, Ucon, and polyvinylpyrrolidone) with the polymer concentration up to 40% typically used as crowding agents. Polymer-induced changes in these features were found to be polymer type and concentration specific, and, in case of polyethylene glycol (PEG), molecular mass specific. Similarly sized polymers PEG and Ucon producing different changes in the solvent properties of water in their solutions induced morphologically different α-synuclein aggregates. It is shown that the crowding effects of some polymers on protein refolding and stability reported in the literature can be quantitatively described in terms of the established solvent features of the media in these polymers solutions. These results indicate that the crowding agents do induce changes in solvent properties of aqueous media in crowded environment. Therefore, these changes should be taken into account for crowding effect analysis.     

Mechanism of action of carboxin and the development of resistance in yeast

Carboxin prevents the growth of yeast by inhibiting protein synthesis; the resumption of growth in the presence of this chemical appears to be primarily due to a cellular alteration affecting carboxin entry into the cells.     

Macromolecular interactions with cadmium and the effects of zinc,copper, lead,and mercury ions

Interactions of cadmium (Cd) ions with bovine serum albumin (BSA), bovine hepatic metallothionein (MT), calf thymus histone and deoxyribonucleic acid (DNA), and bovine hepatic chromatins were studied in the presence and absence of divalent zinc (Zn), copper (Cu), mercury (Hg), or lead (Pb) ions, using equilibrium dialysis at pH 7 and at 37°C. The BSA had 3.5 Cd-binding sites with an apparent affinity constant of 1×10⁵. The other metal ions inhibited the binding by reducing the affinity constant and the number of Cd-binding sites in BSA. There were 6 high affinity and 13 low affinity Cd-binding sites in the MT. Zinc ions had poor efficacy in reducing the binding of Cd to the MT. However, the Cu²⁺ and Hg²⁺ ions inhibited the Cd binding to a considerable extent, the former ions being more potent in this respect. Histone did not bind Cd. There were two kinds of Cd-binding sites in DNA: One mole of Cd per four moles DNA-phosphorus at low affinity sites, and one mole of Cd per 6.7 moles DNA-phosphorus at high affinity sites. Their apparent association constants were 8.3×10⁵ and 4.4×10⁶ M, respectively. The other metal ions had inhibitory effects on the binding of Cd to DNA. Histone reduced the Cd-DNA interactions to only a minor extent. The other metal ions reduced the binding of Cd to DNA-histone complex to a small extent. Cadmium binds to the euchromatin (Euch), heterochromatin (Het), and Euch-Het mixture almost equally. The other metal ions reduced the binding maximally in Euch-Het followed next in order by Het and Euch. Cupric ions were the most potent inhibitors of the interactions of Cd with the nuclear materials.     

Cooperation in a deep helical energy well

In contrast to random coil polymers, polyisocyanates maintain a highly extended helical conformation in solution. This structural characteristic causes unusually large chiral optical properties to arise from copolymerization of tiny proportions of optically active monomer isocyanates with achiral isocyanates or even from stereospecific placement of deuterium in the side chain of poly(n-hexyl isocyanate). These effects can be understood as phenomenologically related to the optical activity amplification properties of vinyl polymers studied by Pino and his co-workers and ascribed to breaking the energetic degeneracy of the otherwise equally populated left- and right-handed helical states of the backbone. Statistical thermodynamic calculations, based on this model, and analogous to those carried out earlier on the vinyl polymers, allow matching the temperature and molecular weight dependence of the optical activity in poly((R)-1-deuterio-1-hexyl isocyanate) to the approximate responsible energy terms.     

Effect of some enzymes, chemicals and insecticides on the macromolecular structure of the froth of the spittlebug, the cercopid Deois sp.

The action of trypsin, collagenase, testicular hyaluronidase, sodium dodecyl sulphate (SDS), urea, guanidinium-chloride (GnCl), n-butanol, dioxane, malathion, alkylphenolpolyglycol ether and iso-octylphenoxy-polyethoxy ethanol/dioctyl sodium sulphocyanate (v/v) on the macromolecular structure of the froth which covers the nymphs of Deois sp., a pest of pasture and agriculture, was studied using polarization microscopy. SDS, n-butanol, GnCl and iso-octyl-phenoxy-polyethoxy ethanol/dioctyl sodium sulphocyanate were the most efficient compounds at promoting disorganization and bursting of the froth bubbles at a relatively fast rate. Disorganization of the froth macromolecules could be visualized through attenuation or abolishment of the birefringence attributable to the high macromolecular orientation of structural proteins and proteoglycans in the wall of the froth bubbles.

---

Résumé L'action de la trypsine, de la colagénase, de l'hyaluronidase testiculaire, du docécil sulphate de sodium (SDS), de l'urée, du chlorite de guanidine (GnCl), du n-butanol, de la dioxane, de l'iso-octilphenoxy-polyetoxy etanol/dioctyl sulphocyanate de sodium (v/v), de l'éther d'alkylphenolpolyglycol et du malathion sur la structure macromoléculaire de l'abri spumeux qui recouvre les nymphes de Deois sp., plaie des pâturages et de l'agriculture, a été observée en microscopie polarisée. Il s'est avéré que le SDS, le n-butanol, le GnCl et l'iso-octil-phenoxypolyetoxy etanol/dioctyl sulphocyanate de sodium sont les agents les plus efficaces de désorganisation et rupture des bulles de mousse, à vitesse assez grande. La désorganisation des macromolécules de la mousse est misse en évidence par la diminution et éventuelle disparition de la biréfringence qui est due à la forte orientation macromoléculaire des protéines structurales et des proteoglycans qui forment la paroi des bulles.

     

Membrane abnormalities of Huntington's chorea fibroblasts in culture.

Huntington's Chorea is an autosomal dominant disease of the nervous system. Proliferating fibroblasts of one such case express metabolic and morphological abnormalities in addition to delayed adhesion to plastic substratum when compared to age, sex and passage number matched human fibroblasts when grown in a minimal essential medium supplemented with glycine or serine and the macromolecular fraction of fetal calf serum. The abnormalities expressed by Huntington's Chorea fibroblasts are fully corrected when the fibroblasts are grown in whole non-filtered fetal calf serum or when 10^?3 M glucosamine is added to the culture medium.