5,217 research outputs found
Novel plant bio-protectants based on Trichoderma spp. strains with superior characteristics
No full textGlobal warming caused by the greenhouse effect will alter the geographical distribution of host and pathogen populations, thus affecting the natural physiology of their interaction and reducing the efficacy of chemical and biological control strategies presently used in agriculture. In perspective to this scenario, new management practices will be required. The main task of this thesis was to isolate and characterize new biocontrol agents of the genus Trichoderma originating from Libya, where these fungi are the most applied antagonists in the country’s agriculture. The intention was to obtain microbes having a natural adaptability to function in adverse climate conditions (low rainfall, drought, extreme temperatures, poor soil quality, etc.) and actively control plant pathogens.
Three pure cultures of Libyan isolates, Lib1, Lib2 and Lib3, were isolated and characterized from different agricultural areas in the northwestern part of Libya. An integrated approach to species characterization using morphological, physiological and molecular techniques was used. The Libyan isolates showed an improved mycelia growth on enriched medium (PDA) at 30°C compared to controls. In plate confrontation assays with fungal pathogens, temperature did not affect the antagonistic abilities of Libyan isolates; in fact, both at 25°C and 30°C the the Libyan isolates reduced growth of Rhizoctonia as well as the biocontrol strain T22, but a lower antagonistic effect was registered against Alternaria and Fusarium spp.
The biotechnological use of the isolated strains in bioremediation projects was also be assessed and preliminary results have shown that the isolated microbes can withstand, not only high temperatures, but also toxic compounds like MTBE.
The analysis of the ribosomal DNA ITS sequences, through homology searches in GenBank database, identified the Lib1 and Lib3 isolates as T. longibrachiatum strains, while Lib2 is T. harzianum. Further, the metabolic profile of Libyan isolate Lib1 was similar to that observed in a T. longibrachiatum strain able to produce Trichogin A IV as major compound.
New possible applications of the selected Trichoderma strains as plant growth promoters and inducers of systemic resistance were evaluated. The results varied according to the combination of plant cultivar and the Trichoderma strain tested, but they were comparable to those of the biocontrol strain T. harzianum T22 whose growth promoting activity is well known. This finding may represent the starting point for novel applications of biocontrol in Libya.
A novel bio-pesticide based on the Libyan Lib1 Trichoderma isolate that has demonstrated superior characteristics was developed and analyzed. The bio-formulate contains the living fungus, mycelia and conidia, and a mixture of Trichoderma originating compounds capable of stimulating plant defense response and growth, as well as directly controlling pathogenic microbes. Conditions optimizing both the growth and development of the living organism and the natural substances that the fungus produces were tested, including different substrates, inducing agents, agitation, aeration, preservatives and conservation compounds. The final product was prepared by liquid fermentation in selected inexpensive media, showed sufficient shelf-life, and retained the multiple beneficial effects of the living fungus useful for application in numerous agricultural situations
Selection Line Optimization of Nanoelectromechanical (NEM) Memory Switches for Stress Relief
No full textSelection lines (SLs) of nanoelectromechanical (NEM) memory switches are optimized for stress relief by using finite-element-method (FEM) simulation. According to the simulation results, as the length of SL (L-SL) decreases, pull-in voltage (Vp(I)) increases while the maximum stress (sigma(max) ) concentrated at the anchor of a movable beam decreases. Thus, it is important to determine optimal L-SL, to achieve better reliability while maintaining Vp(I).N
Shoulder posture and median nerve sliding
No full textBackground: Patients with upper limb pain often have a slumped sitting position and poorshoulder posture. Pain could be due to poor posture causing mechanical changes (stretch; localpressure) that in turn affect the function of major limb nerves (e.g. median nerve). This studyexamines (1) whether the individual components of slumped sitting (forward head position, trunkflexion and shoulder protraction) cause median nerve stretch and (2) whether shoulderprotraction restricts normal nerve movements.Methods: Longitudinal nerve movement was measured using frame-by-frame cross-correlationanalysis from high frequency ultrasound images during individual components of slumped sitting.The effects of protraction on nerve movement through the shoulder region were investigated byexamining nerve movement in the arm in response to contralateral neck side flexion.Results: Neither moving the head forward or trunk flexion caused significant movement of themedian nerve. In contrast, 4.3 mm of movement, adding 0.7% strain, occurred in the forearm duringshoulder protraction. A delay in movement at the start of protraction and straightening of thenerve trunk provided evidence of unloading with the shoulder flexed and elbow extended and thescapulothoracic joint in neutral. There was a 60% reduction in nerve movement in the arm duringcontralateral neck side flexion when the shoulder was protracted compared to scapulothoracicneutral.Conclusion: Slumped sitting is unlikely to increase nerve strain sufficient to cause changes tonerve function. However, shoulder protraction may place the median nerve at risk of injury, sincenerve movement is reduced through the shoulder region when the shoulder is protracted andother joints are moved. Both altered nerve dynamics in response to moving other joints and localchanges to blood supply may adversely affect nerve function and increase the risk of developingupper quadrant pain
Induction of systemic resistance: a main Mechanism of action of biopesticides based on Antagonistic fungi
No full textNumerous biocontrol agents, such as Trichoderma spp. fungal antagonists, have
beneficial effects on plants because they can not only directly inhibit the pathogens,
but also colonize root surfaces, exchange compounds that affect plant metabolism,
enhance plant growth and development, increase nutrient availahility, improve crop
production and induce disease resistanc
Early events in the molecular interaction between the biocontrol agent Trichoderma harzianum and soybean cells
No full textComparison of the stress between rapid thermal annealed and excimer laser annealed polycrystalline silicon thin films
No full textCharacteristics of polycrystalline silicon films with large substrate such as 50 mm x 50 mm, crystallized by using furnace annealing (FA), multi-step rapid thermal annealing (MSRTA) and excimer laser annealing (ELA) methods, have been investigated. In order to characterize the residual stress in crystalline silicon on coming 7059 glass, polarized Raman spectroscopy were measured for those various annealing methods and at various substrate temperatures. We observed that the polycrystalline Si films, crystallized by ELA, have a high crystalline volume fraction, residual stress and equiaxial crystal growth. On the other hand, silicon films crystallized by FA and MSRTA have a low compressive stress and dendritic structure, which are due to thermal relaxation. These Si films have a broad hump around 480 cm(-1) which indicates the existence of amorphous phase silicon. The magnitudes of stresses of FA and MSRTA are 4.07 x 10(9) and 4.46 x 10(9) dyne cm(-2), respectively and the magnitude stress of laser annealing decreases from 1.35 x 10(10) to 8.58 x 10(9) dyne cm(-2) with increasing the substrate temperature from room temperature to 400 degrees C. (C) 1998 Elsevier Science Ltd
CR1 Knops blood group alleles are not associated with severe malaria in the Gambia
No full textThe Knops blood group antigen erythrocyte polymorphisms have been associated with reduced falciparum malaria-based in vitro rosette formation (putative malaria virulence factor). Having previously identified single-nucleotide polymorphisms (SNPs) in the human complement receptor 1 (CR1/CD35) gene underlying the Knops antithetical antigens Sl1/Sl2 and McC(a)/McC(b), we have now performed genotype comparisons to test associations between these two molecular variants and severe malaria in West African children living in the Gambia. While SNPs associated with Sl:2 and McC(b+) were equally distributed among malaria-infected children with severe malaria and control children not infected with malaria parasites, high allele frequencies for Sl 2 (0.800, 1,365/1,706) and McC(b) (0.385, 658/1706) were observed. Further, when compared to the Sl 1/McC(a) allele observed in all populations, the African Sl 2/McC(b) allele appears to have evolved as a result of positive selection (modified Nei-Gojobori test Ka-Ks/s.e.=1.77, P-valu
Characterization of trichoderma species associated with the production of pleurotus ostreatus in Italy
No full textTrichoderma spp. infestations of Pleurotus production are relatively recent
to Italy in comparison with noted problems to Agaricus with T. aggressivum f.
europeaum (Europe) and T. a. f. aggressivum (North America)
Attività de meccanismo d’azione di un estratto d’alga (Ascophyllum nodosum) nei confronti del nematode galligeno Meloidogyne incognita
No full textQuantum and its irreducible representations
No full textWe define for real a unital -algebra
quantizing the universal enveloping
-algebra of . The -algebra
is realized as a -subalgebra of the
Drinfeld double of and its dual Hopf -algebra
, generated by the equatorial Podle\'s sphere coideal
-subalgebra of and
its associated orthogonal coideal -subalgebra . We then classify all the irreducible
-representations of .Comment: 22 pages; author accepted manuscrip
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