محمدرضا رمضانی

One of the important factors in the sustainability of a region's development is the availability of adequate and suitable water resources for various uses, which, in addition to quantity, should be suitable from a qualitative point of view. Groundwater resources are one of the most reliable sources of water supply, which has suffered in recent years due to increased harvesting. The aim of this study is to evaluate the quality of groundwater in Sari-Neka study area and zoning of this area for agricultural use. In this study, 65 water wells in this area were chemically analyzed in year 1392-93. The samples were examined for the effective parameters in agriculture including chlorine (Cl), electrical conductivity (EC), acidity and alkaline (PH), sodium carbonate (RSC) residue. Finally, the water quality status was evaluated using the Wilcox index and the qualitative zoning map was considered. The results showed that more than 90% of the quality water test samples of wells used for agriculture in the C3-S2 and C3-S1 classes are located.

Botulism, a syndrome caused by food poisoning, results from use of food contaminated with the botulinum toxin, which is very dangerous and deadly. Botulism is caused by the effects of bacterial toxins on the terminals of the motor nerves. Botulinum neurotoxins are among the most potent toxins. The aim of this study was to investigate expression, purification and, evaluation of the immunogenicity of the recombinant BoNT/B-HcC protein as an immunogen candidate in mice.

The C-terminus of the receptor-binding domain of  botulinum neurotoxin type B(BoNT/B-HcC) was selected as the antigen for bioinformatics evaluations. The pET17b-BoNT/B-HcC plasmid was transferred to E. coli BL21(DE3) by heat shock. The recombinant protein was purified and analyzed by SDS-PAGE. After verification of the recombinant protein by western blot, immunization of mice was performed. Antibody titers of recombinant proteins were evaluated by indirect ELISA and the results were compared using t-test.

The codon adaptation index (CAI) of the optimized gene was 0.99. The percentage of codons having high-frequency distribution was improved to 78%. Restriction analysis confirmed the 1119 bp construct gene and the recombinant protein with a molecular weight of 43.8 kDa was expressed in the prokaryotic host. The total yield of purified protein was 23 mg of protein per liter of culture. Immunization of mice induced serum antibody response. Statistical analysis showed that the antibody titer was significantly different compared to that of the control sample.

The designed recombinant antigen showed high antigenicity that could be considered as an immunogen against botulinum type B neurotoxin in future studies.

The implementation of sustainable farming systems is essential for ensuring long-term food supply. One of the most important agricultural products produced in Iran is saffron, which is the main source of income for many villagers in the east of the country. Therefore, attention must be paid to the sustainable saffron cultivation in main saffron production regions. The present study was conducted with the aim of measuring the ecological sustainability of saffron farms in Gonabad county and identifying the socio-economic factors affecting it in 2020. The data collection tool was a questionnaire and 193 questionnaires were completed based on simple random sampling procedure. In order to achieve the research objectives, first, ecological sustainability of farms was evaluated based on 12 criteria and using TOPSIS method. Subsequently, an ordered logit model was carried out to determine the factors affecting farm sustainability. Study findings reveal that perception towards sustainable agriculture, age, income and education, as well as having agricultural insurance and pursuing agriculture as the main job, have positive and significant effect on the probability of saffron farmers to be in more sustainable groups. Training courses, by contrast, has a negative effect on this probability, however, it is not significant at the desired statistical probability level. Therefore, improving farmers' perception towards sustainable agriculture, using the experiences of older farmers, financially supporting saffron growers in order to provide the required inputs, and a fundamental revision of the content of training courses can be considered as strategies to enhance the ecological sustainability of this valuable spice.

Raisin is one of the most important agricultural export products of Iran, which has always been an export advantage. However, Iran's raisin export to the EU as the largest raisin importer in the world is very low. Therefore, this study aimed to evaluate the effective factors with emphasis on the role of import market structure on Iran’s raisin exports to EU during period of 2001-2016. To achieve the objective of this study, gravity model was carried out based on unbalanced panel data. Findings indicate that per-capita income of the EU countries has a positive and significant effect on Iran's exports while the effect of economic difference between Iran and its partners and the economic crisis turned out to be negative and significant. Also, import market structure of trading partners has no significant effect on Iran’s raisin export. As a result import market structure is not a serious limiting factor. Accordingly, it is recommended that raisin exporters penetrate into the EU market as one of the most important and profitable destination markets in future export programs.

One of the most important and main components of ecosystems is net primary production, which is an important index for assessing the ecosystems performance in the face of environmental changes. To this end, with regards to the importance of the subject, in this study, to quantify the climate change impacts on ecosystems, NPP values in Jiroft plain was simulated in two periods (2001- 2015and 2016-2030) using the BIOME-BGC model. To assess change in climatic parameters in future, LARS-WG 6 downscaling model was used. After ensuring the capability of the LARS-WG model to create climatic data, climatic variables were simulated in 2016-2030 under the RCP 4.5 scenario. NPP values in 2001-2015 were simulated using the BIOME-BGC model and validated with NPP data derived from Modis images (MOD17A3) that the results showed high accuracy of the model to simulate NPP. After ensuring the model accuracy, NPP was simulated under precipitation and temperature data in future (2016-2030). The results indicate an increase in precipitation, minimum and maximum temperature in the future period (2016-2030) compared with the baseline period (2001-2015). Also, according to the results, NPP value in future has increased in all biomes that this increase is due to increase in precipitation. There is the highest NPP value in the northern and western parts of the region that is related to biome 4 (with agricultural vegetation), biome 5 and 2 (with rangeland vegetation), respectively, and the lowest NPP value is related to the southern parts of the study area.

Preparation of scaffolds with special characters for growing of different cells is considered as an important goal of tissue engineering. In this study, polyacrylonitrile (PAN) and its composites with different percentages of Fe (III) metal-organic frameworks (PAN/x%Fe-MOF) were treated with oxygen plasma. The surface chemistry of these compounds was studied using FT-IR spectroscopy. The morphology stability of the nanofibers after cell-scaffold adhesion was investigated by scanning electron microscopy (SEM). Metabolic activity and survival of endothelial cells cultured on scaffolds were evaluated by MTT method. In conclusion, the results of this study showed that PAN/x%Fe-MOF scaffolds, in particular oxygen plasma treated scaffolds, provide a suitable support for binding and proliferation of endothelial cells due to their high biocompatibility.

Being an essentially open system, cages are usually characterized by a high degree of interaction with environment and cage systems are highly likely to produce large bulk of wastes that are released directly into the aquatic ecosystem if optimal use of inputs, especially fish food, is not available. Nevertheless, measurement of side effects of fish cage culture, along with providing solutions for the optimal use of fish food, can be used as an effective tool to reduce the side effects of this system. So the purpose of this study is to quantify nutrient loadings in rainbow trout (Oncorhynchus mykiss) marine cage farms as the most important nutrients released to the marine and near-shore ecosystem and to make suggestions for reducing the emissions of these nutrients in Mazandaran province. In the production cycle of 2017-18, there were 9 active fish cage farms which the nutrient loadings from each farm were calculated based on an indirect method. According to the results, the environmental loss amounted to 73.979 kg N t-1, 13.893 kg P t-1, and 488.353 kg C t-1 of fish produced. Feed conversion ratio (FCR = feed supplied/ body weight gained) varied between 0.897- 4 with an average of 1.249 representing severe inefficiencies of feeding. Based on study findings, weak technical knowledge of farmers, especially in choosing the right time for start and the end of production cycles, and feeding mismanagement will increase the amount of nutrients released into the environment.

Increasing factor productivity in the agricultural sector is essential, and with the growing population, the need to invent more productive systems is highlighted. However, agronomic activities have always been accompanied by environmental impacts. Therefore, the two categories of productivity and agricultural sustainability should be considered simultaneously. The present study aimed at identifying factors affecting the total factor productivity of saffron farms in Gonabad County with an emphasis on the role of attitude towards sustainable agriculture. In order to achieve the research objectives, 110 questionnaires were completed and after calculating the total factor productivity using the Tornqvist-Theil index, an Ordered-logit model was used to identify factors affecting productivity. The results indicate that attitudes toward sustainable agriculture and income have positive and significant effects on farmers' access to higher levels of productivity, while variable of participation in training courses significantly reduces the probability of achieving higher levels of productivity. Variables of sown area, agricultural insurance and main job do not have significant effects on the probability of achieving different levels of productivity. Undertaking policies which improve attitude of saffron producers towards sustainable agricultural activities and informing them about the effects of unsustainable farming, a fundamental revision of the content of training courses, financial support of farmers for provision of agricultural inputs and reforming the structure of the agricultural insurance system are effective ways to improve productivity of saffron production.

Feeding Frequency can affect various commercially important features such as increased biomass, growth and decreased ratio of foods, increased body weight, increased relative size, and improved tissue composition. Experiments were carried out in 100-liter fiberglass tanks containing 25 grams of 1.2 gram Rutilus kutum with a density of 0.5 g / L. The fish were divided into four treatments including 1, 2, 3, and 4 of Feeding Frequency. Each treatment was repeated 3 times. According to the Tukey test, there was a significant statistical difference between 2 treatment with 3 and 4 treatments, and also treatment 1 Feeding Frequency (P<0.05), considering food conversion rate (FCR), special growth rate (SGR), and weight gain (WG). The results showed that the maximum and minimum amount of weight gain has occurred in treatment3 (mean= 99.09±10.93) .and 1 (mean= 47.12±10.53), respectively. The minimum of the special growth rate (0.64±0.12) was observed treatment 1 and the maximum of that (1.15±0.09) was measured in treatment3. The minimum average of FCR (2.42±0.23) was referred to as treatment3 and the maximum of that (4.76 ±1.03) was referred to as thetreatment1 Feeding Frequency. Overall results showed that feeding three a day, the most appropriate method for growth Rutilus kutum,Fingerling

Developing countries try to attend in trade agreements to achieve safer target markets and reduce trade barriers. Iran also is in trade agreements such as economic cooperation organization (ECO) and global system of trade preferences (GSTP). While there is generally believed that presence in trade agreements generally has positive effect on countries trade flows, there is no any guarantee for positive effect on all countries and products. So, due to the importance of saffron exports for Iran, the aim of this paper is to answer the question of whether Iran’s membership in trade agreements has led to increase the saffron exports to member importing countries. For the purpose, gravity model and saffron exports data in the period of 2001-2014 are used. The results showed that income and population of saffron importers has positive and significant effects, while geographical distance and economic crisis has negative and significant effects on saffron exports. Based on the results, Iran’s membership in trade agreements has significantly negative effect (-3.475) on Iran’s saffron exports. In other words, membership in trade agreements cannot lead to increase Iran’s saffron exports to member trading countries in agreements. Therefore, it is suggested that exporting companies of saffron use the opportunities provided by participating in these trade agreements to take appropriate marketing policies and strategies in order to increase Iran's saffron exports to member trading partners in the agreement.

Fish cage culture is one of the systems of fish farming which has been considered in many countries including Iran, due to its high advantages. Purpose of any economic activities is to maximize profits. Considering the facilities and constraints in the agricultural sector of Iran's economy, the most appropriate way to increase the production and income of farmers is to use of optimal and proper level of production factors. The aim of this study is to evaluate the total factor productivity and efficiency of fish cage farms in Mazandaran province. Required data were collected through interviews and a detailed questionnaire. Based on the results, the total factor productivity index of 4 out of 9 farms was less than 1 and the average of this index was 0.998. On the other hand, the averages of technical, allocative and economic efficiency were 0.884, 0.725 and 0.645, respectively. The results showed that technical efficiencies of three farms were equal to one, and the allocative and economic efficiency of just 1 out of 9 farms was equal to one. Inefficiencies of farms in use of inputs were too drastic that if the cost minimizing input quantities had been used and the proper management had been applied, they would have been able to achieve the current level of their productions at 40% less cost. Given the emergence of fish cage culture in Iran, it is suggested that successful farms be encouraged by incentive policies to transfer their experiences to other farms in order to improve productivity and efficiency. This can be done through training courses using well trained instructors and successful farmers.

The results show that saffron yield in Iran have decreased up to 44% during 1971-2017 which one of its reasons is unsustainable management of the cultivation. Therefore, the present study aimed at identifying sustainable and unsustainable agricultural practices in saffron cultivation in Gonabad township, enhancing the management and providing guidelines on future studies in the field of assessing sustainability status of saffron production. To achieve the objectives, a questionnaire was distributed among 101 experienced saffron farmers in Gonabad.After identifying important practices, the impact of these activities on the ecosystem sustainability was investigated. Afterwards, considering the necessity of avoiding unsustainable farming activities, the importance coefficient of these activities was calculated based on experts’ opinions (Delphi method) and Pairwise Comparison Matrix. Based on the results, five farming operations including manure application, agronomic diversity provided by intercropping and multi-cropping systems, use of micronutrient solutions and fertilizers, application of minimum tillage and organic fertilizers were categorized as sustainable operations. Also, seven activities including high use of chemical fertilizers, high-density planting, herbicides and chemical pesticides, flood irrigation, grazing on farms, human urine and feces and burning saffron residuals were categorized as unsustainable farming activities. From the viewpoint of the experts, the use of chemical fertilizers and high-density planting are recognized as the most unsustainable farming activities in saffron cultivation and the rest are in the next priorities. Therefore, undertaking appropriate policies in order to boost farmers’ attitudes towards sustainable agricultural practices and increasing the awareness of farmers about the negative and long-term effects of unsustainable farming practices, especially high use of chemical fertilizers and high-density of corm in saffron cultivation are essential to provide sustainability in the crop cultivation.

The use of chemical inputs seriously threaten the sustainability of crop production due to the erosion and destruction of soil health, in such a way that it has been always put into question and concerns for it have been growing. The current study was conducted to investigate the factors influensing the application of chemical fertilizers in saffron farms in Gonabad County. To this end, the descriptive-correlation research method was used. The study statistical population consisted of all saffron farmers in Gonabad. Proportional random sampling procedure was used in which 105 saffron farmers were selected. The data collection tool was a questionnaire that its. Face validity  was confirmed by the professors of agricultural economics. Also, the reliability of questions related to attitude towards sustainable agriculture was evaluated by conducting a pilot study in which the Cronbach’s alpha was calculated as 0.698. Afterwards, a two-stage Heckman model was carried out to investigate factors affecting the use of chemical fertilizers. Based on the results, the coefficient of attitude towards sustainable agriculture in both stages was negative and significant, which represents that improvement of farmers' attitude effectively reduces the use of chemical fertilizers. While the coefficients of variables of farmers' income, age, education level, and agricultural insurance are positive and significant in both stages and increase the probability and amount of using fertilizers by farmers. Based on the findings, adopting appropriate strategies for familiarizing saffron farmers with sustainable agricultural practices, luding trust of reliable and experienced farmers to reduce the use of chemical fertilizers, and reforming the structure of agricultural insurance system plays a decisive role in improving the farmers’ consumption pattern of chemical fertilizers.

Saffron is one of the most important agricultural and export products whose production is the main source of income in many rural areas in east of the country. However, the yield of saffron farms decreased by almost 36% during 1971-2015. The Gonabad county in the Khorasan Razavi province as one of the largest saffron producers in Iran also faces this problem. Evidences suggest that the high use of chemical inputs, especially chemical fertilizers, can be considered as one of the main causes of yield decrease. Therefore, this study aims to investigate the effective factors on use of chemical fertilizers with an emphasis on the role of attitude and awareness of saffron producers. In order to achieve the research objectives, 105 questionnaires were completed based on proportional random sampling and an ordered logit model was carried out. The results showed that two variables of farmers’ attitude towards sustainable agriculture and awareness about yield-reducing factors have negative and significant effects on the probability of chemical fertilizer use. While the variables of farmers’ income, age, education and agricultural insurance have positive and significant effect on the probability of chemical fertilizer use. Therefore, undertaking appropriate policies in order to boost farmers’ attitude towards sustainable agricultural practices and increase the awareness of farmers about the negative and long-term effects of excessive use of chemical fertilizers, encouraging trusted and experienced farmers to reduce the use of fertilizers and reconsidering the content of training courses have a decisive role in enhancing the pattern of chemical fertilizers use.

The present study was conducted to assess the environmental efficiency of cage culture fish farming system and to make suggestions for reducing the pollutants emissions into the aquatic ecosystem in Mazandaran province. In the production cycle of 2017-18, there were 9 active fish cage farms which the pollutants loadings from each farm were calculated based on an indirect method. According to the results, per ton of produced fish, an average of 73.979 kg of nitrogen, 13.893 kg of phosphorus and 488.353 kg of carbon were released into the environment. Furthermore, feed conversion ratio (FCR = feed supplied/ body weight gained) varied between 0.897-4 with an average of 1.249 which indicates severe inefficiencies of feeding. Subsequently, the environmental efficiency scores of farms were evaluated based on an SBM-DEA model. The average environmental efficiency of farms was 0.599, indicating that there is a high potential for reducing pollutants emissions and improving environmental efficiency. Based on study findings, weak technical knowledge of farmers, especially in choosing the right time for start and the end of production cycles, and feeding mismanagements will lead to an increase in the amount of pollutants released into the aquatic environment. Thus, it is suggested that successful farms be encouraged by incentive policies to transfer their experiences to other farms in order to improve the environmental efficiency of cage culture system. This can be done through training courses using well trained instructors and successful farmers.

Gonabad township in the Khorasan Razavi province is one of the largest saffron producers in Iran. Unfortunately, the yield of saffron farms in Gonabad has decreased drastically in recent years. Evidence and the opinions of agricultural engineers suggest that high-density planting can be considered as one of the main reasons of yield decrease. With high-density planting, the operation period of saffron farms will start sooner. However, it will decrease the length of operation period tremendously. Furthermore, the farm will not be suitable for saffron cultivation for a long time. Therefore, the present study was conducted with the aim of investigating the effect of high-density planting on yield of saffron farms and determining the socio-economic factors affecting unsustainable system of high-density planting. Data of the first 6-years of farms (2011-2016) were collected and in order to analyze the data, a two-stage Heckman model which include a Probit model and a linear regression model was used. Our study findings show that farmers' age, awareness towards factors that reduce yield of saffron farms, and attending training courses are three factors that have a negative and significant impact on planting density. In other words, these three factors could prevent planting of saffron in high density. Farmers' income and their level of education are two factors which are considered to have a positive and significant impact on planting density. Finally, crop insurance does not have a significant impact in either one of the two models. Therefore, we strongly recommend that farmers should be warned of factors that cause yield decreases throughout training courses. Also, we recommend using of the experience of old and experienced farmers in order to prevent planting saffron in high densities.

The present study was conducted to evaluate the efficiency of saffron farms in Gonabad county and provide solutions for improving the using method of production factors. In order to achieve the research objectives, a sample of 110 saffron farms was studied in 2017.Considering variable return to scale, the average of technical, allocative and economic efficiency were 0.922, 0.593 and 0.556 respectively, indicating that the saffron farms, despite having high technical efficiency, do not have a decent allocative efficiency and they have not succeeded in achieving the cost minimizing input quantities. Subsequently, by assessing the cost minimizing input quantities, it was found that if saffron growers managed resources properly, they would be able to achieve the current amount of yields despite a considerable reduction in the amounts of four inputs of bulks, manure, chemical fertilizer and water, and only a slight increase in the input of labor. In this way, the operating cost per kilogram of saffron flower would reduce by about 44% on average. Considering there is evidence that the saffron growers of the study area have a tendency to use high-input cultivation systems, it is suggested that appropriate policies be developed to improve the knowledge of farmers and change their attitudes towards cultivation of saffron, so that they will be aware of the adverse effects of these systems.

Ardebil province in north western of Iran has extensive a great number of nature lakes. Freshwater Lakes are very important water bodies in point of view of agriculture, drinking waters and aquaculture. Sampling of biotic and abiotic factors at station 4 in Moghan Lake was done in August and September 2006. The survey showed, 3 groups and 13 genera of zooplankton identified which consisted of Rotatoria (7 genus), Protozoa (5 genus), and Arthropoda (1 genus). The benthic organisms, were comprised Chironomidae, Oligochaeta, Odonata, Sphaerium and Hydropsychidae. The Oligochaeta constitute the most abundance in all stations. The average biomass of benthos measured 18.7 g.m2 in the Moghan Lake. Twelve species of fish were identified in Moghan Lake. The 9 species belongs to Cyprinidae family and other species belongs to Siluridae, Percidae and Gobiidae. Abramis brama and Hemiculter leucisculus had the highest abundance with the genus of 35.6 and 23.4 % and the lowest of fish abundance belong to Silver Carp and Gobiidae with the value of 0.2 %. This survey showed the structure of aquatic invertebrate and fish communities. For potential estimation and sustainable development of the lake have to continue more study in the ecosystem.

Salinity is one of the most important limitation factors in development of agricultural products. Cotton has a relative tolerance to salinity; however, salinity reduces its growth during germination and seedling stages. In this research, split-factorial design of time based on randomized complete block design with 3 replications was used. The real-time PCR results for, root, stem, and leaves of 14-day cotton seedlings of tolerant (Sepid) and sensitive (Thermus14) cotton cultivars with salinity levels from 0 to 16 ds.m-1 were analyzed at three time points, namely 0, 7 and 14 days after salinity stress. Selected genes for Real Time PCR reaction in current study were selected using Cytoscape 3.3.0 software. Results showed that the selected genes GhERF2, GhMPK2, GhCIPK6, GbRLK, GhNHX1, GhGST, GhTPS1 and Gh14-3-3 have positively responded to salinity stress and their expression in the root was higher than in stem and leaf. Moreover, the expression of tolerant genotype (Sepid) was higher than the sensitive cultivar (Thermus 14) one, however, a slight increase in sensitive genotypes was observed in a number of genes (GhERF2 and GhGST) 14 days after starting the stress treatment.

IntroductionToday salinity stress and salinization of soil is one of the most important environmental stress. As the amount of salt increases the plant growth rate decreases. Salinity cause imbalance in soil nutrient content. At this condition we have to use suitable nutrients to achieve appropriate yield. This experiment was conducted to evaluate the effect of salinity and zinc and iron application on yield and some morphological traits and quality of ajowan.
Material and methodsA split plots based on randomized complete block design with three replications was used in Khezri, South Khorasan in 2010. Salinity levels of irrigation water (970, 3500 and 7700 µs.cm-1) andfoliar application of micronutrients (control, Fe, Zn and Fe Zn) were as main plot and sub plot, respectively. Each plot consisted six rows. The length of rows was 4 m. Distance between rows and plants on the rows was 40 and 20 cm, respectively. Data analysis was conducted by MSTATC and SPSS software and means were compared by Duncan’s multiple range tests at 5 % probability level.
Result and DiscussionSeed yield significantly affected by salt stress and its interaction with foliar application treatment. The highest (258.11 g.m-2) and the lowest (171.56 g.m-2) seed yield respectively was related to treatments low salinity iron and high salinity (iron츩). In high salinity conditions, which showed a significant reduction in seed yield than low and common salinity, there was no significant difference between the levels of foliar application with control. In fact, iron foliar application in low salinity (control) significantly increased seed yield, but iron zinc spray application did not significantly change seed yield in comparison with control (without foliar application). On the other hand, in common salinity stress, foliar application treatments did not increase the yield, but in high salinity, the treatments increased seed yield.
In low salt stress conditions foliar application of iron increased significantly seed yield, however foliar application of iron츩 could not affect seed yield. On the other hand, in the common salt stress conditions, foliar application treatments could not increase seed yield, but under severe salt stress these treatments enhanced the yield. In general, under low, common and high salinity stress, the highest seed yield respectively was related to foliar application treatments iron, control and zinc. Seed yield reduction under salinity stress is related to its impact on shoot growth. In this experiment seed yield reduction was related to the decline of umbel number per plant. Correlation coefficient between seed yield and umbel number per plant also was positively significant. Like seed yield, salinity stress reduced different growth parameters such as plant height and branch number per plant. Effect of foliar application on seed essential oil percent and yield was not significant. However, in sever salinity stress, like seed yield, essential oil yield also declined. Although in high and common salt stress, foliar application had not any significant effect on essential oil yield, but under low salt stress, iron foliar application significantly increased essential oil yield. The results of this experiment show that the response of plant height and branch number per plant to irrigation treatments are opposite to each other. Considering that in all foliar application treatments, plant height increased, it can be concluded that the stimulus effect of these treatments on stem longitudinal growth causes the competition of the main stem with lateral branches. Therefore the number of branch per plant in iron and zinc foliar application treatments has declined. It has been reported that zinc deficiency can reduce plant height and yield due to adverse effects on biosynthesis of auxin.
ConclusionTotally, the results of this experiment showed that, due to the significant interaction between salinity and foliar application, microelements should be used with care and after further studies in this plant. Possibly, some plant responses to foliar application and salinity interactions can be related to the presence of different compounds in water used in salinity treatments. Also, the lack of response of some growth parameters such as yield and plant height to the foliar application can be due to complicated plant nutrition relationships with soil conditions such as pH and other soil nutrient concentrations.

The study of the molecular dynamics of proteins based on internal motions is crucial for understanding the mechanism of protein function. Internal movements of proteins play an important role in both protein folding processes and the mechanism of action of enzyme. Knowledge about these movements will help us in understanding these processes correctly. Osmolites are small organic molecules which are utilized by the cells of all organisms, except hallobacteria. Osmolites are produced under extreme stressful conditions in order to help in stabilizing macro-molecules and retaining their biological function. They interact directly with macromolecules, but they exert their effect only when the characteristics or conditions of the solvent present around the cell change. Therefore, their presence affects the stability of the protein indirectly.
In this work we studied the effect(s) of the osmolite Sorbitol on the dynamics of Hen Egg White Lysozyme, and through our study we used NMR Hydrogen-Deuterium Exchange to characterize the effect(s). We performed spectrometery in two different conditions, in the absence and presence of sorbitol. The extent of peptide hydrogen exchange was assigned as a function time and in a decreasing manner in the intensity of the peak corresponding to amino acids. The resulting TOCSY spectra were assigned using SPARKY software, as well as we integrated the peaks using this software.
The speed of hydrogen exchange, hydrogen atoms of the peptide bond, will give us information about the local structural oscillations where the exchange is taking place. The rate of hydrogen exchange varies from one amino acid to another, and the intensity of the peak of these hydrogen decreases as time passes by.
We found that the presence of sorbitol causes a decrease in proton exchange rate, and since there is no noticeable chemical shifts in the peaks of the spectra, in the presence or absence of sorbitol, we can conclude that sorbitol did not cause any change in the three dimensional structure. It seems that the decrease in the rate of exchange is a representative of a decrease in the accessible surface area or to strengthening of hydrogen bonds, and sorbitol caused one of these two possibilities.