نشریه یافته های نوین در علوم زیستی
سال چهارم شماره 4 (پیاپی 14، زمستان 1396)

Alpha-amylases are the most important amylases used in industry. Among them, thermophilic alpha-amylases are of particular importance, which is due to their activity and stability in high temperatures. These enzymes produced by thermophile micro-organisms including bacteria. These thermophilic alpha-amylases are used in various industries such as processing of starch as well as production of detergents and biofuels. In this research, the bacteria which produce the thermophilic alpha-amylases were isolated and characterized in hot springs of Gorooh village in Kerman province. According to the results of screening on the specific liquid and solid media, AT59 was selected as the best strain. Morphological and biochemical characterization of the isolated strain indicated that it belonged to Bacillus sp. and was gram-positive, catalase positive, casein hydrolyzing and acid producing from lactose and sucrose. The results obtained from the optimization of the enzyme production medium showed that among the carbon, nitrogen and ion sources investigated, starch (1 gr/l), gelatin (2 g/l) and magnesium sulfate (1 g/l) had the most increasing effect on the production of AT59 alpha-amylase. Moreover, the highest enzyme production was obtained at pH 5. This enzyme also demonstrated the highest degree of activity and stability in 80 and 70 ℃, respectively. These findings suggested that this enzyme has a considerable potential for use in starch industry.

Phenolic compounds, especially those with plant origin, constitute an essential part of the human diet due to their antioxidant properties. Antioxidants protect biological systems (nucleic acids, proteins, lipids, lipoproteins) against free radicals and reactive oxygen species. Some medicinal plants contain so high amounts of antioxidants that their use can be considerably effective for human health. The aim of this study was to evaluate the effect of flooding extraction method on phenolic compounds, flavonoids and the level of free radical scavenging properties of medicinal plants including Thyme, Hamadani Yarrow, Shirazi mountain thyme, Yarrow, Chamomile, Saffron corm hyssop Sagebrush, wormwood, Artemisia and Ziziphora clinopodioiedes, in four extraction solvents including water, methanol, acetone and ethanol. The results showed that methanol and water solvents had the highest and the lowest total phenolic, flavonoid and antioxidant activity, respectively. The results also showed that methanol extraction of Shirazi thyme and water extraction of Wormwood plant had the highest and the lowest phenol and flavonoids contents, respectively. The results of trapping the free radicals of DPPH indicated that the methanol extract of Shirazi thyme and aqueous extract of wormwood had the highest and the lowest inhibition activities, respectively. Therefore, the selection of solvent type can affect the rate of the extraction of phenolic compounds, flavonoids and antioxidant activity.

This study aimed to recycle sawdust and blood powder using Eisenia foetida earthworm and investigate some biochemical changes of these waste materials during vermicomposting. Blood powder was mixed with sawdust in proportions of 0, 5 and 10% and the mixture was allowed to pass through earthworm guts for four months. At intervals of 1, 2, 3, 4, 6, 8, 12 and 16 weeks, the biological activity (i.e. basal respiration), pH, EC, total organic carbon, total nitrogen and C:N ratio were determined. The results showed that the period of time, the concentration of blood powder and the interaction between these two significantly affected all parameters. As the incubation time increases, the cumulative amount of mineralized carbon, the total nitrogen and EC increase in all vermicompost treatments whereas organic carbon, C:N ratio and pH decreased. Adding blood powder to sawdust bed resulted in an increase in carbon mineralization rate, EC and total nitrogen while pH, organic carbon and C: N ratio decreased. At the end of incubation time, the treatment of sawdust with 10 % blood powder resulted in the highest amount of released CO2 (142.1 µg C g-1), EC (3.7 dS m-1) and total nitrogen (2.24 %) and the lowest amount of pH (6.6), organic carbon (22.5 %) and C: N ratio (12.4). According to the results, the process of vermicomposting can be used as a safe method for the disposal of sawdust and blood powder.

The genus Crataegus L. has a wide distribution in Iran. Induviduals of Crataegus meyeri Pojark. show morphological variations in different regions. In this research, the effects of climatic variations on morphological traits of C. meyeri were studied. Seventy five specimens collected from nine provinces of Iran were measured in two sets of quantitative and qualitative traits. Statistical analysis of climatic data and morphological traits showed that wind and temperature were the most effective factors affecting the variety of morphological traits including leaf blade of short shoot and flowering shoot, indumentum of fruit surface and fruit shape. Relative humidity has also been correlated with the shape of the fruit base. Quantitative traits of leaf blade of short shoots and flowering shoots showed the highest correlation and leaf blade of elongate shoots with the least statistical correlation with climatic data.

Trichoderma species have been famous for production of cellulases with relatively high enzymatic activity. However, attempts to use their cellulolytic enzymes in the bioconversion of cellulosic wastes have not been successful because of high cost of production and low enzymatic yields. This study aimed to obtain gamma-induced mutants of T. viride with enhanced extracellular cellulase production. Spore suspensions were exposed to γ-rays at 250 Gy as optimum dose. After irradiation, all germinated spores were grown onto PDA plates and mutant strains with better sporulation were selected and subcultured five times to test their stability. Cellulase activity was tested using Whatman No. 1 filter paper, carboxymethyl cellulose, avicel, bacterial cellulose and walseth cellulose according to the IUPAC recommendation. Extracellular proteins profiles of mutant strains were studied via SDS-PAGE. The maximum activity of total cellulase and avicelase were observed in the isolate of M21 (92.43 and 74.40 U/mg, respectively) and maximum endo-glucanase activity was observed in M18 mutant. The results of this study showed that the application of gamma ray led to a significant increase in Cellulose activity of 38 percent of mutant strains. Thus, this method could be used as a simple and efficient way to achieve strains with the ability to produce high levels of enzymes and other biological metabolites.

Ferula stenocarpa from Apiaceae family is a perennial plant with about 2 meters height, which grows in the high temperature of sudanian regions. This research was aimed to investigate the autecology of an endemic plant to Iran, Ferula stenocarpa, in Khuzestan province. Initially, the habitat map was prepared and characteristics of the species habitat including topography, climate, soil properties, companion species, palynology, anatomical studies were determined. In addition, the phenology stage and root system was investigated. The results show that this species is distributed in the altitudes ranging from 159 to 850 m.a.s.l., with the mean annual precipitation of 112.4 to 482.9 millimeters and mean annual temperature of 24.47 to 25.93 ºC. This plant species is found in habitats with different topographic aspects and no slope limitations with slopes 40-60% as preferred slopes. Soil texture was loam, clay loam and silty loam, weak alkaline, and poor in phosphorus and nitrogen. Electrical Conductivity is 1-0.72 ds/m and soil pH of 7.47-7.85. The vegetative growth of this species starts from mid-March. The flowers appear in April and seeds ripen in late on May. The plant propagates only by seeds. Pollen is prolate, elliptic and tricolporate. The destruction of natural habitats of this plant due to overgrazing causes that we find this plant as individual and scattered spots in their natural habitat.

This study aimed to investigate the protective effect of Arctium lappa (AL) on gentamicin (GM)-induced nephrotoxicity in rats. Twenty-four Wistar rats were divided into four groups including: control group; GM group (intrapritoneal injection, IP, of 100 mg/kg GM B.W.); GM group (received IP injection of 100 mg/kg GM and 500 mg/kg AL orally) and AL group (received 500 mg/kg AL orally). The experimental period lasted for 10 days. Nephrotoxicity was biochemically and histologically evaluated. The concentrations of creatinine, urea, malondialdehyde (MDA), superoxide dismutase (SOD) and peroxide hydrogen (H2O2) in the serum samples were determined. Moreover, histological examinations were performed. The animals treated with gentamicin showed significantly higher serum urea, creatinine, MDA and H2O2 levels and lower SOD activity. However, co-administration of AL produced amelioration in biochemical indices of nephrotoxicity in serum. Histomorphological examination showed necrosis and desquamation of tubular epithelial cells in the renal cortex in animals treated with gentamicin whereas simultaneous administration of AL and GM reduced histological damages. The data obtained suggest that treatment with AL extract can help to reduce gentamicin-induced nephrotoxicity.

Wild grapevine, Vitis vinifera subsp. sylvestris is considered as a rare species in Europe and Iran and possesses restricted distribution due to threatening factors. Natural populations of wild grapevine in the north of Iran were evaluated in three wild areas of coastal and plains areas of Miankaleh, submontane areas of Amol and the forest patches of Kojour and a cultivated sample of crop grapevine, V. v. subsp. vinifera in Babolsar. A total of 41 anatomical traits and important ecological factors such as soil and climatic variables were investigated and included in further analyses. Anatomical characteristics of leaf blade and petiole had the most important impact on the separation of wild and the cultivated taxon. All the soil and climatic factors, particularly altitude and annual rainfall were significant between studied stations. Mean temperature of the warmest month along with soil clay and calcareous percentage had the highest effect and relationship with the anatomical traits. Based on the current result, anatomical characters can be used for separation between wild and cultivated populations. They are also effective in separation of different populations of wild grapevine. Quantitative anatomical changes in the studied populations are reflection of the different soil and climatic conditions of their habitat.

Gastrointestinal ontogenetic studies constitute one of the basic and important investigations related to the nutrition of aquatic animals. In this investigation, specimens of the western white shrimp (Litopenaeus vannamei) at different developmental stages (from nauplius 1 to postlarvae 120) were assayed for the activities of digestive enzymes. According to the results, at all developmental stages, trypsin, amylase, and lipase enzymes were found to be active. In addition, the peak activities of all enzymes were revealed to occur during the late zoea larval stages (Z3). On the other hand, minimum activities were observed to occur at metamorphosis. During the postlarval developmental stages, amylase and lipase activities increased steadily, whereas the trypsin activity was more or less constant up to the eighteenth week. In conclusion, ontogenetic change in digestive enzyme activity may reflect either a developmentally cued change in enzyme synthesis or a secondary effect of change in the function and relative size of the midgut during its differentiation.