Strong Cell Wall Research Articles

Optimization of culturing condition and medium composition for the production of alginate lyase by a marine Vibrio sp. YKW-34

Carbohydrases secreted by marine Vibrio sp. YKW-34 with strong Laminaria cell wall degrading ability were screened, and among them alginate lyase was found to be dominant. The effects of medium composition and culturing condition on the production of alginate lyase by marine Vibrio sp. YKW-34 in flask were investigated in this study. In the culture medium of marine broth, no alginate lyase was produced. The activity of the alginate lyase, after being induced, reached 5 UmL−1. The best inoculum volume and inoculum age were 10% and 12 h, respectively. The optimal temperature for alginate lyase production was 25°C. The fermentation medium was composed of 0.5% of Laminaria powder and 0.2% of KNO3 with an initial acidity of pH 8.0. Alginate could induce alginate lyase production but not as efficiently as Laminaria powder did. The addition of fucoidan, cellulose and glucose had negative effect on the alginate lyase production. Other kinds of nitrogen sources, such as yeast extract, beef extract and peptone, had positive effect on the growth of the microorganism and negative effect on alginate lyase production. In addition, the time course of alginate lyase production under the optimized condition was described. The optimal harvest time was 48 h.

Mechanism based QSAR studies of N-phenylbenzamides as antimicrobial agents

N-Phenyl benzamides are potent antibacterial agents. They are active against both Gram-positive and Gram-negative bacteria. The Gram-positive bacteria have strong and thick cell wall while the Gram-negative bacterial have thin and permeable cell wall. The DFT based QSAR reveals that molecular weight and total energy significantly contribute to activity against both kinds of target. The electrophilicity index involved in QSAR models derived with anti-Gram-positive activity indicates the dominance of electrostatic interaction. The molar refractivity and log P is involved in QSAR model derived with anti-Gram-negative activity shows steric and hydrophobic interaction. The CoMFA and CoMSIA results also indicate that anti-Gram-positive bacterial activity is a function of electrostatic field effect but the anti-Gram-negative activity depends on hydrophobicity and steric field effect. The CoMFA and CoMSIA contour maps give an indication, the electropositive group around benzene “X” and an electronegative group around carbonyl oxygen is desirable for better anti-Gram-positive bacterial activity. A hydrophobic group around meta position of ring “X” with bulky group at ortho position and a small group at para position are desirable for better activity against Gram-negative target. The findings are reasonable and the mechanism might be different due to difference in composition of cell wall. The cell wall of Gram-positive target does not allow the permeability and only external electrostatic interaction is possible while the cell wall of Gram-negative target allows the permeability of molecules inside the cell for possible hydrophobic and steric bulk interaction.

Antifungal properties of ethanolic extract and its active compounds from Calocedrus macrolepis var. formosana (Florin) heartwood

The ethanolic extract of Calocedrus macrolepis var. formosana heartwood was screened for antifungal compounds by agar dilution assay and liquid chromatography. Two compounds, β-thujaplicin and γ-thujaplicin, responsible for the antifungal property of C. macrolepis var. formosana heartwood were isolated by high performance liquid chromatography (HPLC), and identified by 1H NMR and 13C NMR. The antifungal activities of these two compounds were further evaluated against total 15 fungi, including wood decay fungi, tree pathogenic fungi and molds. The hexane soluble fraction showed the strongest antifungal activities among all fractions. β-Thujaplicin and γ-thujaplicin exhibited not only very strong antifungal activity, but also broad antifungal spectrum. The MIC values of β-thujaplicin and γ-thujaplicin were in the range of 5.0–50.0 μg/ml. In addition, scanning electron microscopy (SEM) was carried out to study the structural change of fungal hyphae induced by β-thujaplicin. Strong cell wall shrinkage indicated the fungicidal effect could be attributed to the combined actions of metal chelating and cytoplasm leakage. It also suggests that the role of metal chelating is indispensable in the design of environmental-friendly fungicides.

QTLs for shelf life in lettuce co-locate with those for leaf biophysical properties but not with those for leaf developmental traits.

Developmental and biophysical leaf characteristics that influence post-harvest shelf life in lettuce, an important leafy crop, have been examined. The traits were studied using 60 informative F9 recombinant inbed lines (RILs) derived from a cross between cultivated lettuce (Lactuca sativa cv. Salinas) and wild lettuce (L. serriola acc. UC96US23). Quantitative trait loci (QTLs) for shelf life co-located most closely with those for leaf biophysical properties such as plasticity, elasticity, and breakstrength, suggesting that these are appropriate targets for molecular breeding for improved shelf life. Significant correlations were found between shelf life and leaf size, leaf weight, leaf chlorophyll content, leaf stomatal index, and epidermal cell number per leaf, indicating that these pre-harvest leaf development traits confer post-harvest properties. By studying the population in two contrasting environments in northern and southern Europe, the genotype by environment interaction effects of the QTLs relevant to leaf development and shelf life were assessed. In total, 107 QTLs, distributed on all nine linkage groups, were detected from the 29 traits. Only five QTLs were common in both environments. Several areas where many QTLs co-located (hotspots) on the genome were identified, with relatively little overlap between developmental hotspots and those relating to shelf life. However, QTLs for leaf biophysical properties (breakstrength, plasticity, and elasticity) and cell area correlated well with shelf life, confirming that the ideal ideotype lettuce should have small cells with strong cell walls. The identification of QTLs for leaf development, strength, and longevity will lead to a better understanding of processability at a genetic and cellular level, and allow the improvement of salad leaf quality through marker-assisted breeding.

General morphogenetic events and regulatory genes expresion in flower development

The main genetics of development conception is differential genes expression for different types of cells in developed organisms. That is correct for higher plants, too. Otherwise, all the higher plants, in comparing to animals, are characterized by some unique traits. The main of them is a strong cell wall leading to the immobility of organism, so plants chose principally different life strategy, connecting to the adaptation. Sequencing of several plant genomes revealed that there are much more genes involved in plant morphogenesis than in animal are. The main of plant morphogenesis genes are MADS-genes, the place and the level of expression of them define unique features of morphogenesis. Some data confirmed that expression of some transcription factors is under epigenetic control. It means that RNA plays a key role in the regulation of the main genes in development. So, the absence of homeosis gene AP2 expression in inner мутовках of develop flower is a result of active miRNA172 gene expression in that regions. The genetic, molecular and biochemical basis of the action of the MADS domain proteins in the plant life cycle are reviewed here. Moreover, in this reviewer, we focus on examples of signaling and gene regulation, where striking progress has been made in recent years.

The galactose residues of xyloglucan are essential to maintain mechanical strength of the primary cell walls in Arabidopsis during growth.

In land plants, xyloglucans (XyGs) tether cellulose microfibrils into a strong but extensible cell wall. The MUR2 and MUR3 genes of Arabidopsis encode XyG-specific fucosyl and galactosyl transferases, respectively. Mutations of these genes give precisely altered XyG structures missing one or both of these subtending sugar residues. Tensile strength measurements of etiolated hypocotyls revealed that galactosylation rather than fucosylation of the side chains is essential for maintenance of wall strength. Symptomatic of this loss of tensile strength is an abnormal swelling of the cells at the base of fully grown hypocotyls as well as bulging and marked increase in the diameter of the epidermal and underlying cortical cells. The presence of subtending galactosyl residues markedly enhance the activities of XyG endotransglucosylases and the accessibility of XyG to their action, indicating a role for this enzyme activity in XyG cleavage and religation in the wall during growth for maintenance of tensile strength. Although a shortening of XyGs that normally accompanies cell elongation appears to be slightly reduced, galactosylation of the XyGs is not strictly required for cell elongation, for lengthening the polymers that occurs in the wall upon secretion, or for binding of the XyGs to cellulose.

The Exoskeleton of Bacterial Cells (the Sacculus): Still a Highly Attractive Target for Antibacterial Agents That Will Last For a Long Time

Most bacteria are entirely surrounded by a strong cell wall held together by covalent bonds of strength similar to those holding the atoms in a diamond together. This exoskeleton is a coat of armor or corset and is usually called a sacculus. It protects the bacterium from the stresses resulting from the higher osmotic pressure of the cytoplasm when compared with its environment. This strategy of constructing an external mechanical support has the weakness that the wall barrier has to be cleaved and new wall material inserted outside of the cell proper in order for the bacterium to grow and divide.Because of the unique chemistry and the necessity of selectively cleaving old stress-bearing wall for growth, the wall of the bacterial cell has been a key target for chemotherapeutic treatment of bacterial diseases. Currently, many infectious organisms are becoming resistant to overused antibiotics. Still the wall is a good target, and there could possibly be several entirely new classes of antibiotics targeted toward other parts of wall metabolism and function. The essential autoly sins may be a particularly relevant target. To find chemotherapeutic agents we must use and extend our present understanding of the structural mechanics of bacterial wall and their biophysics, biochemistry, and physiology. Moreover, if we use our knowledge of biophysics/genetics and of the evolution of antibiotic resistance mutations that occurred millions of years ago, as well as our knowledge of ones that have arisen recently, quite novel antibiotics may be designed.

Nested amplification protocol for the detection of Mycobacterium tuberculosis.

Several methods for rapid diagnosis of tuberculosis have been devised through DNA amplification. However, the chemically strong cell wall of the species, the presumptively low numbers of organisms and their uneven distribution in clinical samples, and the lack of a "gold standard" for diagnosing tuberculosis, have hindered the routine clinical use of this method. In a pediatric patient group, these factors are more perplexing. To circumvent these problems, we made use of nested amplification and developed a standard protocol for extracting DNA from various forms of clinical samples which were suitable to our clinical laboratory. It is our impression that the overall sensitivity, including technical bias accompanying this method, is equal to, or at least greater than, that of culture. Most notably, the rapidity in obtaining results and the simplicity in handling, storage and transfer of samples are the principal advantages of this method.

Mechanical properties of FeAlZrB2 alloys prepared by rapid solidification

Alloys based on FeAl containing various amounts of ZrB2 have been prepared by rapid solidification and the mechanical properties of these materials related to the distribution of the dispersoid additions. Following rapid solidification the ZrB2 is present in a cellular configuration which leads to considerable strengthening. The composite material obtained consists of strong cell walls which limit deformation to one small region at a time, leading to a redistribution of applied stresses on mechanical testing which can result in improved ductilities.

Production of Thermostable Clostridium thermohydrosulfuricum Xylose Isomerase in Bacillus brevis.

The xylose isomerase gene from the thermophile Clostridium thermohydrosulfuricum has been cloned into Bacillus brevis. Under control of the strong cell wall protein promoter, the gene was efficiently expressed during the early stationary phase of growth, when cell densities were high. The expressed gene product was a soluble cytoplasmic protein and made up more than 20% of the total cellular protein. A simple heat treatment at 85°C for 10 min gave a virtually pure enzyme. Final isomerase yields were about 0.5 g isomerase per liter culture. The purified isomerase has an optimum temperature at 85°C, and an optimum pH around 7. The isomerase is stable at 85°C for several hours, opening possibilities for new uses.

Invasive aspergillosis diagnosed by immunohistochemistry with monoclonal and polyclonal reagents

Therapies differ for invasive infection due to the various filamentous fungi. However, histopathologic identification of Aspergillus, Pseudallescheria, Fusarium, Trichosporon, dematiacious Hyphomycetes, Candida, and Zygomycetes may be confused, and microbiologic isolation is often delayed. To improve diagnosis, we examined the utility of polyclonal and monoclonal antibodies to identify Aspergillus organisms by peroxidase immunohistochemical techniques. Tissues obtained from 68 infected patients were examined. Fungal antigen was detected in all 26 cases of aspergillosis by the monoclonal immunohistochemical test. Hyphae of Aspergillus organisms exhibited strong intracellular and cell wall staining, and extracellular localization was also observed. In contrast, negative tests were observed in tissues from five cases of infection with Pseudallescheria boydii, three with Trichosporon, three with Zygomycetes, six with Candida species, and one with Curvularia, from as well as 20 cases of nonfungal pneumonia. However, cross-reactivity to Coccidioides immitis spherules was noted in three cases. Staining of Candida was observed with the polyclonal antibody but not the monoclonal reagent. This is the first immunohistochemical demonstration of aspergillus antigen with a monoclonal reagent. The study indicates that the monoclonal immunohistochemical technique can distinguish Aspergillus species from other filamentous fungi and may facilitate the clinical diagnosis of invasive aspergillosis.

Morphogenesis and significance of hyphal coiling by nematode-trapping fungi in mycoparasitic relationships

The mycoparasitic behaviour of some nematode-trapping fungi was investigated. These organisms interacted with other soil fungi by hyphal coiling around the host hyphae. A detailed study with Arthrobotrys oligospora revealed that different fungi, representing all taxonomic groups, were attacked. In dual cultures, the interaction between A. oligospora and Rhizoctonia solani occurred soon after hyphal contact, irrespective of the nutrient level of the medium. Coiling was also observed when the two organisms were grown in sterilized soil. The coils possessed a high metabolic activity compared to the surrounding hyphae, as was indicated by fluorescence microscopy of fluorescein diacetate (FDA)-stained preparations. On the ultrastructural level, developing coils showed an abundance of membranous vesicles which developed from tubular-shaped endoplasmic reticulum. At the site of coiling, a strong cell wall proliferation was observed in the Rhizoctonia cells. The cytoplasm of these cells subsequently disintegrated. The death of the cells was confirmed in vital staining experiments. Penetration of intact Rhizoctonia cells was not observed. The interaction between A. oligospora and R. solani is interpreted in terms of competition for nutrients.

Morphogenesis and significance of hyphal coiling by nematode-trapping fungi in mycoparasitic relationships

The mycoparasitic behaviour of some nematode-trapping fungi was investigated. These organisms interacted with other soil fungi by hyphal coiling around the host hyphae. A detailed study with Arthrobotrys oligospora revealed that different fungi, representing all taxonomic groups, were attacked. In dual cultures, the interaction between A. oligospora and Rhizoctonia solani occurred soon after hyphal contact, irrespective of the nutrient level of the medium. Coiling was also observed when the two organisms were grown in sterilized soil. The coils possessed a high metabolic activity compared to the surrounding hyphae, as was indicated by fluorescence microscopy of fluorescein diacetate (FDA)-stained preparations. On the ultrastructural level, developing coils showed an abundance of membranous vesicles which developed from tubular-shaped endoplasmic reticulum. At the site of coiling, a strong cell wall proliferation was observed in the Rhizoctonia cells. The cytoplasm of these cells subsequently disintegrated. The death of the cells was confirmed in vital staining experiments. Penetration of intact Rhizoctonia cells was not observed. The interaction between A. oligospora and R. solani is interpreted in terms of competition for nutrients.

Mechanical Disruption of Leaf Tissues and Cells in Some Bloat‐Causing and Bloat‐Safe Forage Legumes1

Whole leaves and isolated mesophyll cells from three bloat‐causing and three bloat‐safe legumes were mechanically damaged to identify characteristics which might contribute in resisting cell and tissue rupture during chewing and hence reduce bloat potential. Whole leaves were subjected to sonication, homogenizing with a ground glass tissue grinder, and shaking with glass beads. Isolated cells were exposed only to rupture by sonication. In the bloat‐safe legumes, birdsfoot trefoil (Lotus corniculatus L.) had strong cell walls alone, while sainfoin (Onobrychis viciifolia Scop.) and cicer milkvetch (Astragalus cicer L.) revealed moderately strong cell walls combined with a high degree of tissue strength. The bloat‐causing legumes, alfalfa (Medicago sativa L.) and white clover (Trifolium repens L.) showed weak cell walls with low tissue strength while red clover (T. pratense L.) had moderately strong cell walls and low tissue strength. Cell wall strength alone or combined with tissue strength appears to be a factor in determining cell rupture.