Hossein Alizadeh

Effect of Incremental Driving Motion on a Vision-Based Path Planning of a Spherical Robot

Path planning of spherical robots is usually carried out based on a continuous motion. However, actuators such as stepping motors are driven by discrete input signals that generate motion in rotational steps. The results would therefore be different from the continuous path planned for the spherical robot. The spherical robot under study incorporates two stepping motors, which generate the rotation increments. This incremental rotation inputs cause error and deviate the robot from the desired path. The result of such discretization of actuating input is studied here. The robot path is simulated using the inverse kinematics relations. As the angular steps decrease with better resolution of motors, the motion approaches the path expected for continuous motion.

Conidiogenic effects of mannose-binding lectins isolated from cotyledons of red kidney bean (Phaseolus vulgaris) on Alternaria alternata

Effect of proteinaceous extracts from red kidney bean cotyledons on mycelium of Alternaria alternata growing on potato dextrose agar (PDA) plates was investigated. Unexpectedly, conidia formation was induced in response to applied crude extracts. A PDA disc method was developed to quantify conidia formed. A purified fraction retaining conidiation inducing effect (CIE) was obtained following several protein purification procedures including the last step of eluting bound proteins from an Affi-gel blue gel column. Based on MALDI (matrix assisted laser desorption/ionization) mass spectrometric analysis, a previously identified mannose-binding lectin (MBL) called PvFRIL (Phaseolus vulgaris fetal liver tyrosine kinase 3-receptor interacting lectin) was present in this conidiation inducing fraction. The PvFRIL was subsequently purified using a single step mannose-agarose affinity column chromatography. When the lectin was applied exogenously to A. alternata, increased conidiation resulted. The conidia produced in response to the MBL were similar to those induced by other methods and their germ tubes were longer after 12 h growth than those induced under white light. To our knowledge this is the first report of exogenous application of a PvFRIL or another purified protein from a plant inducing conidia formation in a fungus.

Biochemical characteristics of Trichoderma atroviride associated with conidium fitness for biological control

ABSTRACT Effects of abiotic factors during production (temperature, nutrients, water activity, pH) on conidium fitness (quantity and quality) of Trichoderma atroviride LU132 (a key biocontrol agent) were studied. Conidia from the culturing regimes which resulted in greatest and least bioactivity against Rhizoctonia solani in dual culture assays were selected to assess effects of storage conditions on conidial fitness over time. Further studies assessed interaction effects of temperatures (20°C or 30°C) and sugars (dextrose or sucrose) on conidium germination and bioactivity as fresh conidia, or after 6 months of storage. Biochemical analyses of sugars and fatty acids were carried out to determine relationships between quality variations and cellular characteristics for conidia produced in different culturing conditions. Low trehalose content in conidia (e.g. at 20°C) was associated with the least conidium fitness, although high trehalose content did not necessarily support conidium fitness. High proportions of total fatty acids in conidia were mostly associated with the least conidium fitness. When Trichoderma was grown at high carbon to nitrogen ratio (e.g. at C:N 160:1), the total conidium fatty acids content increased. This study also indicated that the monosaccharide dextrose is metabolically optimal for T. atroviride LU132 at 20°C while the disaccharide sucrose is optimal at 30°C. These studies indicate that physical growth conditions and nutritional requirements attribute in conidium fitness of T. atroviride LU132, and provide important knowledge supporting optimum production of biocontrol agents based on T. atroviride, and possibly other similar biocontrol agents.

Methods for the Evaluation of the Bioactivity and Biocontrol Potential of Species of Trichoderma.

Members of the genus Trichoderma comprise the majority of commercial fungal biocontrol agents of plant diseases. As such, there is a wealth of information available on the analysis of their biocontrol potential and the mechanisms behind their superior abilities. This chapter aims to summarize the most common methods utilized within a Trichoderma biocontrol program for assessing the biological properties of individual strains.

Improved rapid detection of trypsin isoinhibitors using non‐denaturing polyacrylamide gels with immobilised azoalbumin

INTRODUCTION Proteinaceous inhibitors of animal trypsin occur naturally as isoforms in seeds and some are of interest as antinutritional or anti-pest agents. OBJECTIVE To establish a simplified electrophorectic, in-gel method for rapid and direct detection of trypsin isoinhibitors present in crude plant extracts that are particularly suitable for many studies including rapid evaluation of cultivars. METHODOLOGY Azoalbumin (3%, w/v) is immobilised in 7.5% polyacrylamide gels before electrophoresis under non-denaturing conditions. RESULTS This improved method eliminates the need for both time-consuming and labourious staining and destaining or renaturation steps. CONCLUSION Immobilised azoalbumin in polyacrylamide gels, run under non-denaturing electrophoresis conditions, can be used to assist rapid evaluation of trypsin isoinhibitors in numerous crude plant extracts.

Concurrent occurrence of α-amylase inhibitor and stimulator in red kidney bean seed: physiological implications.

It is hypothesized that since protein α-amylase inhibitor (α-AI) and stimulator might be present together in red kidney bean (Phaseolus vulgaris L.) seeds, their in vitro interactions might influence their detection and quantification. Assay of α-AI using extracts from the embryonic axes revealed an unexpected finding in that the extracts stimulated rather than inhibited α-amylase activity. The cotyledon extracts exhibited inhibitory or enhancement effect on α-amylase activity depending on whether prior to the α-amylase assay they had been boiled for 10 min or not. Phytohemagglutinin (PHA-L in particular) is implicated in the present study as a stimulator of α-amylase activity co-extracted with α-AI from red kidney bean cotyledons. The importance of these findings is discussed in relation to the possible widespread occurrence of protein α-amylase stimulator in seeds and other plant parts.