266 research outputs found

    Differential gene-expression of metallothionein 1M and 1G in response to zinc in sertoli TM4 cells

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    Background: Zinc (Zn) as an important trace element is essential for testicular development and spermatogenesis. Molecular mechanism of Zn action in the reproductive system may be related to metal binding low-molecular weight proteins, metallothioneins (MT). Our objective was to determine the effect of Zn on two important isoforms of MT, MT1M and MT1G genes expression on testicular sertoli cells. Methods: Cultured sertoli TM4 cells were exposed to different concentrations of Zn at different time points. Cellular uptake of Zn was tested using flame atomic absorption spectrometry. The cellular viability and gene expression were assessed by MTT and real-time PCR methods, respectively. Results: The treated cells resulted in higher Zn concentration and cellular viability. The expression of MT1M and MT1G genes in the treated cells were greater than those of the untreated cells (P<0.05). In the high dosage treated group (100 and 500 μM), Zn concentration and expression of MT1M and MT1G genes increased three h after treatment; MT1G gene expression increased more at sixth h. At 18th h of treatment, the expression of both genes especially MT1G, increased dramatically while Zn concentration decreased. Conclusion: Since the increase of MT1G mRNA was coincident with cellular Zn level, it seems that MT1G has a more prominent role than MT1M in the homeostasis of Zn. In addition, Zn at dosage of 50 μM (pharmacologic concentration) may protect cells by increasing the expression of MT genes at longer periods

    External Periodic Driving of Large Systems of Globally Coupled Phase Oscillators

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    Large systems of coupled oscillators subjected to a periodic external drive occur in many situations in physics and biology. Here the simple, paradigmatic case of equal-strength, all-to-all sine-coupling of phase oscillators subject to a sinusoidal external drive is considered. The stationary states and their stability are determined. Using the stability information and numerical experiments, parameter space phase diagrams showing when different types of system behavior apply are constructed, and the bifurcations marking transitions between different types of behavior are delineated. The analysis is supported by results of direct numerical simulation of an ensemble of oscillators

    Sustainable Rangeland Management Using A Multi-Fuzzy Model: How To Deal With Heterogeneous Experts’ Knowledge

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    While fuzzy specialists usually use homogeneous experts’ knowledge to construct fuzzy models, it is much more difficult to deal with knowledge elicited from a heterogeneous group of experts. This issue especially holds in the area of the sustainable rangeland management. One way to deal with the diversity of opinions is to develop a fuzzy system for all experts and to combine all these so-called primary systems into one multi-fuzzy model. To derive each of the primary fuzzy systems using the knowledge of a group of administrative experts, several semi-structured interviews were held in three different areas of the Fars province in Southwest Iran. In order to find the final output of the multi-fuzzy model, we applied different ‘voting’ methods. The first method simply uses the arithmetic average of the primary outputs as the final output of the multifuzzy model. This final output represents an estimation of the Right Rate of Stocking. We also propose other (un)supervised voting methods. Most importantly, by harmonizing the primary outputs such that outliers get less emphasis, we introduce an unsupervised voting method calculating a weighted estimate of the Right Rate of Stocking. This harmonizing method is expected to provide a new useful tool for policymakers in order to deal with heterogenity in experts’ opinions: it is especially useful in cases where little field data is available and one is forced to rely on experts’ knowledge only. By constructing the three fuzzy models based on the elicitation of heterogeneous experts’ knowledge, our study shows the multidimensional vaguenesses that exist in sustainable rangeland management. Finally, by comparing the final Right Rate of Stocking with its medium range, this study proves the existence of overgrazing in pastures of the three regions of the Fars province in Southwest Iran

    Effects of intermittent feeding on compensatory growth, feed intake and body composition in Asian sea bass (Lates calcarifer)

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    This experiment was conducted to investigate the effects of various starvation and refeeding periods on growth, feed utilization and body composition in Asian sea bass (Lates calcarifer) with an average initial weight of 30.26±1.4 g (mean±SE). The fish were exposed to three different regimes: the control group fed twice daily to apparent satiation throughout the experiment (C), the first group starved for 4 days and refed for 16 days, this cycle was repeated two times (T1) and the second group starved for 8 days and refed for 32 days (T2). At the end of experiment, there were not any significant differences in growth and feeding performance among different treatments (p>0.05). Daily feed intake was significantly higher in the deprived fish than in the control fish (p0.05). Starvation had a significant effect on protein content on one sampling date during the experimental period; protein content in T2 on day 8 was significantly lower compared to the control (p<0.05). Sea bass showed complete compensation indicating a high ability of the deprived fish to grow sufficiently to fully compensate for weight loss during starvation. The results suggested that the feeding schedule involving starvation-refeeding cycles could be a promising feed management option for the culture of this species

    ٍEfficiency of mating disruption for controlling the leopard moth, Zeuzera pyrina L. (Lep.: Cossidae), in walnut orchards

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    Leopard moth, Zeuzera pyrina L. (Lep.: Cossidae), is a key pest of walnut in Iran. The efficiency of mating disruption by two commercial products including Isonet® Z and Zeumat Universe® was evaluated in 2011 in East Azerbaijan and Kerman provinces. In each hectar, 300-600 pheromone dispensers for mating disruption were attached to the trees before the emergence of adults. Three pheromone traps were also installed in each plot to evaluate the orientation disruption before the adults' emergence. The pheromone traps did not capture any adult in the plots where mating disruption was performed during the experiment in both provinces while the traps caught the adults in the control plots. This result confirmed the efficiency of the used number of products for orientation disruption of the males. The averages of the number of larval entrances on the branches of plots where mating disruption was conducted by Isonet® Z, Zeumat Universe® and control were respectively 0.18 ± 0.03, 0.13 ± 0.02 and 0.45 ± 0.04 in Kerman province, 0.18 ± 0.03, 0.33 ± 0.04 and 0.63 ± 0.07 in East Azarbaiejan province and 0.18 ± 0.02, 0.2 ± 0.02 and 0.52 ± 0.04 (average ± S. E.) for the pooled data of both regions. There was a significant difference among the averages (P < 0.01).The results showed the efficiency of mating disruption technique by both products for reducing the damage of the pest even after one year. The number of larval entrances on the branches of the trees in mating disruption plots was 60-70% less than control plots. The results confirmed that the mating disruption with 300 pheromone dispensers of each product is efficient for reducing the damage of the pest in the walnut orchards

    A Study on Effects of Chemical Fertilizer and Organic Manures on Kiwifruit (Actinidia deliciosa, cv. Hayward) Quality during Cold Storage

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    Introduction  Consumers demand for organic products is increasing due to their awareness of health and nutritional quality. Organic manures maintain soil health and ecological balance of the region. Organic agriculture, as an alternative agricultural system to protect human health and the environment can improve the quality and storability of the product. Kiwifruit is one of the most important agricultural products in north of Iran, which plays an effective role in trade and employment of the people. Fertilization is one of the main factors affecting the yield and quality of kiwifruit. Growers use organic manures and chemical fertilizers in their orchard to achieve higher yields. It is necessary to study the effect of various organic manures available in the region on the nutrition of kiwifruit vines due to increase chemical fertilizer prices and the formation of the market for organic fruits. Therefore, the aim of this study was to compare the effect of using five types of organic manures and chemical fertilizer on the quality of Hayward kiwi fruit during cold storage.   Materials and Methods  This research was conducted as randomized complete block design consisting six treatments (including complete chemical fertilizer, sheep manure, cow manure, chicken manure, vermicompost and azolla) on Hayward kiwifruit vines in orchard and factorial experiment with three replicates in cold storage during four years. The fruits were harvested at TSS: 6.5 (approximately mid-November) and then stored at 0.5 ° C and 90% RH for three months. Sampling was performed every month and physicochemical characteristics, including flesh color parameters (L*, C*, h◦), total soluble solids, titratable acidity, firmness and weight loss of fruit were measured. Sensory evaluation of fruits was also performed at the end of three months cold storage. Analysis of variance of the data was done using SAS 9.1 software. The significance of differences between the mean of treatments was determined by using Duncan’s test.   Results and Discussion  The results showed the interaction between year, type of nutrition and cold storage period affected color indices, lightness and chroma. Lightness and chroma value didn’t show significant differences between organic and chemical fertilizer treatments. In addition, their value decreased during cold storage period, significantly. The chroma value indicates the degree of saturation of the green color and is associated with fruit firmness. The hue value was also influenced by the interaction between year and cold storage period and the simple effect of the nutrition type. The highest hue value was observed in chicken manure (108.63) and the lowest in vermicompost (107.66). The hue value decreased significantly after 90 days cold storage. According to the results, a decrease in fruit firmness, TA and an increase in TSS and TSS/TA were observed during cold storage irrespective of treatments. After 90 days, total soluble solids content was higher when organic fertilizers were applied. During the storage of kiwifruit, total soluble solids content increased, significantly. The titratable acidity value in organic fertilizer treatments was higher than chemical fertilizer after 90 days cold storage, significantly. Moreover, titratable acidity value decreased at the end of the cold storage period, significantly. The highest flesh fruit firmness was obtained in cow manure (8.74 kg/cm2) in forth year and chemical fertilizer treatment had the lowest flesh firmness (3.2 kg/cm2) in third year. Fruit lost firmness gradually during the cold storage period. However, no significant difference was found in maturity index (TSS/TA) between treatments. The TSS:TA ratio is highly increased after 90 days. Based on the results of the last two years, azolla, cow and chicken manures showed less weight loss percentage than chemical fertilizer treatment. Moreover, weight loss increased significantly during cold storage period in all treatments and years. Also the results of sensory analysis showed that fruits treated with vermicompost had a higher overall acceptance than other treatments.   Conclusion  Generally, organic nutrition plays an important role in increasing the nutritional value and shelf life of kiwifruit cv.Hayward. Organically produced fruits had higher firmness than conventionally grown fruits during storage. Application of cow manure and vermicompost showed favorable effects on important properties of kiwi fruit such as firmness, weight loss, TSS, TA and sensory quality. Therefore, organic fruits will have better quality in the cold storage. As a result, it seems that by reducing the use of chemical fertilizers in the current orchards, kiwi production will be close to the standards defined for organic fruit

    Study on daily and reproduction activity of melon weevil, Acythopeus curvirostris persicus (Col.: Curculionidae), in Birjand, Iran

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    Melon weevil, Acytopeus curvirostris persicus Thompson, is one of the most important pests of melons that is spread in the Middle East countries. In this study, diurnal and seasonal locomotor and flight activity of melon weevil were investigated under field condition using bucket traps (baited with conspecifics male and cucumber fruit) and also mating behavior pattern and its effect on fecundity (under semifield conditions) and fertility (under laboratory conditions). The results showed that both males and females of melon weevil have distinct daily activity. Two activity peaks were observed at 7:00-9:00 am and 17:00-19:00 pm. Maximum flight activity was observed in the afternoon (14:00 hours) in field condition. Both sexes emerged in early cultivation season (late June) simultaneously and the number of captured weevil was the highest in early October (6.1 ± 2.6 weevils per week). Emerged adults from pupal cocoon mated after about eight days. Peak of mating occurred during 14:30-16:30 pm. Number of mating during lifetime of males (18.3 ± 3.4) was nearly two times greater than females (9.6 ± 2.2). The mean number of eggs laid during reproduction period in single and multiple mating were 29.2 ± 3.5 and 52.4 ± 6.2 eggs per female, respectively. Oviposition was maximum on 12 and 36 days after mating. Hatching rates of eggs in single and multiple mating were 85 ± 7% and 82.5 ± 9%, respectively. Multiple mating had no significant effect on fecundity and fertility. There was no relationship between mating frequency and temperature

    Last-male sperm precedence in Rhynchophorus ferrugineus (Olivier): observations in laboratory mating experiments with irradiated males

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    The Red PalmWeevil (RPW)Rhynchophorus ferrugineus(Olivier 1790) is an invasive pest from southeastern Asia and Melanesia that in the last 30 years has spread widely in the Middle East and Mediterranean Basin. Its stem-boring larvae cause great damage to several palm species of the Arecaceae family, many of which are economically important for agricultural and ornamental purposes. Therefore, great attention has recently been focused in studying this species to identify sustainable and effective eradication strategies, such as sterile insect technique (SIT). The rapid spread of RPW is associated with its high reproductive success. To evaluate the suitability of a SIT strategy, particular physiological and behavioral aspects of RPW reproduction, such as the presence of polyandry and post-copulatory sperm selection mechanisms, were investigated. To determine paternity of progeny from multiply mated females, double-crossing experiments were carried out confining individual females with either a wild-type male or a γ-irradiated male (Co-60). Fecundity and fertility of females were scored to evaluate post-copulatory sperm selection. Results showed that progeny were almost exclusively produced by the sperm of the second male, suggesting that a last-male sperm precedence is expressed at high levels in this species, and providing interesting insights for an area-wide RPW management strategy such as the SIT
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