Host-parasite relationships in mycoparasite /

A mycoparasite, Piptocephalis virginiana ^ shows a resemblance to fungal parasites of higher plants in the fine structure of hyphae and haustoria. The morphology and fine structure of host and parasitic fungi have been described. The mode of penetration of the host cell, Choanephora cucurbitarum , probably involves mechanical forces. Although the presence of cell wall degrading enzyme was not detected by conventional techniques, its role in penetration can't be ruled out. A collar around the haustorial neck is formed as an extension of the host cell wall. No papilla was detected although appressorixim was seen during penetration. The young haustorium is enclosed in highly invaginating plasmalemma of the host cell and n\imerous cisternae of endoplasmic reticulum. Appearance of an electron—dense sheath around the mature haustorium seems to coincide with the disappearance of cisternae of endoplasmic reticulum from the host cystoplasm in the vicinity of the haustorium. The role of host cytoplasm particularly of endoplasmic reticulum in the development of the sheath is discussed. Extensive accumulation of spherosomes-like bodies, containing lipids, is found in haustorium, parasite and host hypha. Electron microscope revealed the parasiticculture spore has more lipid content than the axenic culture spore of P. virginiana . The biochemical and cytochemical tests also support these results. The mature spore of C. cucurbitarum possesses a thick three-layered cell wall, different from the hyphal wall. Its germination is accompanied by the formation of an elastic thin inner layer which surrounds the emerging germ tube and the growing hypha. High resolution autoradiography showed that H N-acetyl-glucosamine , a precursor of chitin, was incorporated preferentially in the thin inner layer of the spore wall and also in the cell wall of the growing hypha. When the label was fed to the infected cells, at different intervals after inoculation, grains were observed on the sheath which developed around the haustorium of P. virginiana , 30 hours after inoculation. The significance of these results in relation to the origin and composition of the sheath is discussed.

Isolation and partial characterization of host cell wall surface glycoproteins: their involvement in agglutination, attachment and appressorium formation by piptocephalis virginiana

Cell surface proteins obtained by alkaline extraction from isolated cell walls of Mortierella pusilla and M. candelabrum, host and nonhost, respectively, to the mycoparasite, Piptocephalis virginiana, were tested for their ability to agglutinate mycoparasite spores. The host cell wall protein extract had a high agglutinating activity (788 a.u. mg- t ) as compared with the nonhost extract (21 a.li. mg- t ). SDS-polyacrylamide gel electrophoresis of the cell wall proteins revealed four protein bands, a, b, c, and d (Mr 117, 100, 85 and 64 kd, respectively) at the host surface, but not at the nonhost surface, except for the faint band c. Deletion of proteins b or c from the host cell wall protein extract significantly reduced its agglutinating activity. Proteins band c, obtained as purified preparations by a series of procedures, were shown to be two glycoproteins. Carbohydrate analysis by gas chromatography demonstrated that glucose and Nacetylglucosamine were the major carbohydrate components of the glycoproteins. It was further shown that the agglutinating activity of the pure preparation containing both band c was 500-850 times that of the single glycoproteins, suggesting the involvement of both glycoproteins in agglutination. The results suggest that the glycoproteins band c are the two subunits of agglutinin present at the host cell surface. The two glycoproteins band c purified from the host cell wall protein extract were further examined after various treatments for their possible role in agglutination, attachment and appressorium formation by the mycoparasite. Results obtained by agglutination and attachment tests showed: (1) the two glycoprotein-s are not only an agglutinin responsible for the mycoparasite spore agglutination, but may also serve as a receptor for the specific recognition, attachment and appressorium formation by the mycoparasite; (2) treatment of the rnycoparasite spores with various sugars revealed that arabinose, glucose and N-acetylglucosamine inhibited the agglutination and attachment activity of the glycoproteins, however, the relative percentage of appressorium formation was not affected by the above sugars; (3) the two glycoproteins are relatively stable with respect to their agglutinin and receptor functions. The present results suggest that the agglutination and attachment may be mediated directly by certain sugars present at the host and mycoparasite cell surfaces while the appressorlum formation may be the response of complementary combinations of both sugar and protein, the two parts of the glycoproteins at the interacting surfaces of two fungi.

Pigment orientation changes detected by low temperature linear dichroism spectroscopy: cold-hardening transition in phycobilisome-containing organisms

Low temperature (77K) linear dichroism spectroscopy was used to characterize pigment orientation changes accompanying the light state transition in the cyanobacterium, Synechococcus sp. pee 6301, and cold-hardening in winter rye (Secale cereale L. cv. Puma). Samples were oriented for spectroscopy using the gel squeezing method (Abdourakhmanov et aI., 1979) and brought to 77K in liquid nitrogen. The linear dichroism (LD) spectra of Synechococcus 6301 phycobilisome/thylakoid membrane fragments cross-linked in light state 1 and light state 2 with glutaraldehyde showed differences in both chlorophyll a and phycobilin orientation. A decrease in the relative amplitude of the 681nm chlorophyll a positive LD peak was observed in membrane fragments in state 2. Reorientation of the phycobilisome (PBS) during the transition to state 2 resulted in an increase in core allophycocyanin absorption parallel to the membrane, and a decrease in rod phycocyanin parallel absorption. This result supports the "spillover" and "PBS detachment" models of the light state transition in PBS-containing organisms, but not the "mobile PBS" model. A model was proposed for PBS reorientation upon transition to state 2, consisting of a tilt in the antenna complex with respect to the membrane plane. Linear dichroism spectra of PBS/thylakoid fragments from the red alga, Porphyridium cruentum, grown in green light (containing relatively more PSI) and red light (containing relatively more PSll) were compared to identify chlorophyll a absorption bands associated with each photosystem. Spectra from red light - grown samples had a larger positive LD signal on the short wavelength side of the 686nm chlorophyll a peak than those from green light - grown fragments. These results support the identification of the difference in linear dichroism seen at 681nm in Synechococcus spectra as a reorientation of PSll chromophores. Linear dichroism spectra were taken of thylakoid membranes isolated from winter rye grown at 20°C (non-hardened) and 5°C (cold-hardened). Differences were seen in the orientation of chlorophyll b relative to chlorophyll a. An increase in parallel absorption was identified at the long-wavelength chlorophyll a absorption peak, along with a decrease in parallel absorption from chlorophyll b chromophores. The same changes in relative pigment orientation were seen in the LD of isolated hardened and non-hardened light-harvesting antenna complexes (LHCII). It was concluded that orientational differences in LHCII pigments were responsible for thylakoid LD differences. Changes in pigment orientation, along with differences observed in long-wavelength absorption and in the overall magnitude of LD in hardened and non-hardened complexes, could be explained by the higher LHCII monomer:oligomer ratio in hardened rye (Huner et ai., 1987) if differences in this ratio affect differential light scattering properties, or fluctuation of chromophore orientation in the isolated LHCII sample.

Patterns in space : a regional study of motif in Minoan wall painting

This thesis consists of a quantitative analysis of the regional prevalence of certain artistic motifs as they appear in Minoan wall painting of the Neopalatial period. This will help to establish the relative degree of artistic autonomy exercised by each of the sites included in this study. The results show that the argument for itinerant artists during this time period is a strong one, but the assumption that these travelling artists were being controlled by any one palace-centre is erroneous. Rather, the similarities and differences seen suggest that the choices were predicated either by the specific patrons, or by the function of the associated building or room. Thus, the motifs found within this study should be understood as constituting a cultural identity, with greater or lesser degrees of regional homogeneity, which act as one facet of a number of cultural indicators that can be used to better understand the role of artists and regional dynamics on the island during the Bronze Age.

Cell wall degrading enzymes and interaction between Trichoderma Aggressivum and Agaricus Bisporus

Agaricus bisporus is the most commonly cultivated mushroom in North America and has a great economic value. Green mould is a serious disease of A. bisporus and causes major reductions in mushroom crop production. The causative agent of green mould disease in North America was identified as Trichoderma aggressivum f. aggressivum. Variations in the disease resistance have been shown in the different commercial mushroom strains. The purpose of this study is to continue investigations of the interactions between T. aggressivum and A. bisporus during the development of green mould disease. The main focus of the research was to study the roles of cell wall degrading enzymes in green mould disease resistance and pathogenesis. First, we tried to isolate and sequence the N-acetylglucosaminidase from A. bisporus to understand the defensive mechanism of mushroom against the disease. However, the lack of genomic and proteomic information of A. bisporus limited our efforts. Next, T. aggressivum cell wall degrading enzymes that are thought to attack Agaricus and mediate the disease development were examined. The three cell wall degrading enzymes genes, encoding endochitinase (ech42), glucanase (fJ-1,3 glucanase) and protease (prb 1), were isolated and sequenced from T. aggressivum f. aggressivum. The sequence data showed significant homology with the corresponding genes from other fungi including Trichoderma species. The transcription levels of the three T. aggressivum cell wall degrading enzymes were studied during the in vitro co-cultivation with A. bisporus using R T -qPCR. The transcription levels of the three genes were significantly upregulated compared to the solitary culture levels but were upregulated to a lesser extent in co-cultivation with a resistant strain of A. bisporus than with a sensitive strain. An Agrobacterium tumefaciens transformation system was developed for T. aggressivum and was used to transform three silencing plasmids to construct three new T. aggressivum phenotypes, each with a silenced cell wall degrading enzyme. The silencing efficiency was determined by RT-qPCR during the individual in vitro cocultivation of each of the new phenotypes with A. bisporus. The results showed that the expression of the three enzymes was significantly decreased during the in vitro cocultivation when compared with the wild type. The phenotypes were co-cultivated with A. bisporus on compost with monitoring the green mould disease progression. The data indicated that prbi and ech42 genes is more important in disease progression than the p- 1,3 glucanase gene. Finally, the present study emphasises the role of the three cell wall degrading enzymes in green mould disease infection and may provide a promising tool for disease management.

Mode of action of FMRFamide-like peptide on drosophila body wall muscle conractions

Neuropeptides are the largest group of signalling chemicals that can convey the information from the brain to the cells of all tissues. DPKQDFMRFamide, a member of one of the largest families of neuropeptides, FMRFamide-like peptides, has modulatory effects on nerve-evoked contractions of Drosophila body wall muscles (Hewes et aI.,1998) which are at least in part mediated by the ability of the peptide to enhance neurotransmitter release from the presynaptic terminal (Hewes et aI., 1998, Dunn & Mercier., 2005). However, DPKQDFMRFamide is also able to act directly on Drosophila body wall muscles by inducing contractions which require the influx of extracellular Ca 2+ (Clark et aI., 2008). The present study was aimed at identifying which proteins, including the membrane-bound receptor and second messenger molecules, are involved in mechanisms mediating this myotropic effect of the peptide. DPKQDFMRFamide induced contractions were reduced by 70% and 90%, respectively, in larvae in which FMRFamide G-protein coupled receptor gene (CG2114) was silenced either ubiquitously or specifically in muscle tissue, when compared to the response of the control larvae in which the expression of the same gene was not manipulated. Using an enzyme immunoassay (EIA) method, it was determined that at concentrations of 1 ~M- 0.01 ~M, the peptide failed to increase cAMP and cGMP levels in Drosophila body wall muscles. In addition, the physiological effect of DPKQDFMRFamide at a threshold dose was not potentiated by 3-lsobutyl-1-methylxanthine, a phosphodiesterase inhibitor, nor was the response to 1 ~M peptide blocked or reduced by inhibitors of cAMP-dependent or cGMP-dependent protein kinases. The response to DPKQDFMRFamide was not affected in the mutants of the phosholipase C-~ (PLC~) gene (norpA larvae) or IP3 receptor mutants, which suggested that the PLC-IP3 pathway is not involved in mediat ing the peptide's effects. Alatransgenic flies lacking activity of calcium/calmodul in-dependent protein kinase (CamKII showed an increase in muscle tonus following the application of 1 JlM DPKQDFMRFamide similar to the control larvae. Heat shock treatment potentiated the response to DPKQDFMRFamide in both ala1 and control flies by approximately 150 and 100 % from a non heat-shocked larvae, respectively. Furthermore, a CaMKII inhibitor, KN-93, did not affect the ability of peptide to increase muscle tonus. Thus, al though DPKQDFMRFamide acts through a G-protein coupled FMRFamide receptor, it does not appear to act via cAMP, cGMP, IP3, PLC or CaMKl1. The mechanism through which the FMRFamide receptor acts remains to be determined.

Lighting recommendations for the Ryan Electric Scintillator and Fireworks Program for the official dedication Niagara Falls illumination, 1925

Walter D’Arcy Ryan was born in 1870 in Kentville, Nova Scotia. He became the chief of the department of illumination at the General Electric Company of Schenectady, New York. He was a founder in the field of electrical illumination. He built the electric steam scintillator which had numerous nozzles and valves. The operator would release steam through the valves. The nozzles all had names which included: Niagara, fan, snake, plume, column, pinwheel and sunburst. The steam scintillator was combined with projectors, prismatic reflectors, flashers and filters to produce the desired effects. In 1920 a group of businessmen from Niagara Falls, New York formed a group who called themselves the “generators’. They lobbied the American and Canadian governments to improve the illumination of the Falls. They were able to raise $58, 000 for the purchase and installation of 24 arc lights to illuminate the Falls. On February 24th, 1925 the Niagara Falls Illumination Board was formed. Initially, the board had a budget of $28,000 for management, operation and maintenance of the lights. The power was supplied free by the Ontario Power Company. They had 24 lights installed in a row on the Ontario Power Company surge tank which was next to the Refectory in Victoria Park on the Canadian side. The official opening ceremony took place on June 8th, 1925 and included a light parade in Niagara Falls, New York and an international ceremony held in the middle of the Upper Steel Arch Bridge. Walter D’Arcy Ryan was the illuminating engineer and A.D. Dickerson who was his New York field assistant directed the scintillator. with information from American Technological Sublime by David E. Nye and the Niagara Falls info website Location: Brock University Archives Source Information: Subject Headings: Added Entries: 100 Ryan, W. D’A. |q (Walter D’Arcy), |d 1870-1934 610 General Electric Company 650 Lighting, Architectural and decorative 650 Lighting |z New York (State) |z Niagara Falls 700 Dickerson, A.F. 700 Schaffer, J.W. Related material held at other repositories: The Niagara Falls Museum in Niagara Falls, Ontario has a program (pamphlet) dedicating new lighting in 1958 and it has postcards depicting the illumination of the Falls. Some of Ryan’s accomplishments can be seen at The Virtual Museum of the City of San Francisco. Described by: Anne Adams Date: Sept 26,Upper Steel Arch Bridge. Walter D’Arcy Ryan was the illuminating engineer and A.D. Dickerson who was his New York field assistant directed the scintillator. with information from American Technological Sublime by David E. Nye and the Niagara Falls info website

Letter from J.E.A. Masters to Josiah Masters, November 11, 1812

Transcription: Encampment Plattsburgh My Dear Uncle Nov. 11th 1812 We are making every possible preparation to invade Canada. I have no doubt but we march in six days. From the best information I can get it is not contemplated to attack the Isle aux Noix – We shall take into the field 2500 infantry between 3 & 4 hundred cavalry 25 light artillery & 150 artillerists; of the malitia I have no accurate knowledge there is more than 1000 of them, the number of regular troops is mentioned you may rely on as being nearly correct I cannot state to a man as I have not had an opportunity of being the consolidated returns of the different corps. It is said that a [corps formed?] of volunteers are to join us from Vermont. I think it doubtful I believe that we shall have no great difficulty in going to Montreal as to the ultimate policy of the [act it is?] not my duty to judge. Confidential our troops are raw particularly in loading and firing they are much deficient. The 6th and 15th will be able to act with some considerable ... of precision and accuracy the remaining infantry—badly disciplined. Should any thing [occur?] with me my fate be unfortunate the [little?] property willed me by my grandfather will secure you the amount I owe you. General Dearborn I understand is at Burlington on his way here. Some of the prisoners that were taken at Queenstown have [arrived?] at Montreal probably. [Ensign Rich?] is among them. Several officers here became acquainted with him soon after he received his [two illegible words] & speak highly of him. [Always?] affectionately yours J. E. A. Masters P.S. I shall write you again before we march excuse this [scrawl?] my hand are too cold to write a fair hand we shall have here near [400?] sick that are not able to march J. E. A. Masters The [Hon.?] Josiah Masters [Schaghticoke?] N.Y. N. B. Nov. 13th We have orders to be prepared to march on the 15th at 12 oclock. Our baggage will be contained as much as possible. The officers carry no baggage except what they carry in their knapsacks. I am in fine health and am able [Hand?] most any [illegible word] My love to all affectionately Your nephew J. E. A. Masters