IRANIAN JOURNAL OF BIOLOGY
Year:2004 | Volume:17 | Issue:3|Papers Count:6

Actinidin is a thiol protease rich in Kiwifiuit. This enzyme shows high degree of homology with other plant thiol proteases like papain. In this project actinidin was purified from Hayward cultivar of kiwi and characterized using SDS-PAGE, Isoelectric focusing (IEF) and Two-dimensional gel electrophoresis (2DE).The enzyme was purified by salt fractionation and ion exchange chromatography and assayed upon casein hydrolysis method. SDS-PAGE was preformed in reducing and non-reducing conditions. IEF preformed in rehydrated gel using ampholine with pH range of 3.5-5 and 2DE carried out in slab gels in the two dimensions.Molecular mass of the purified enzymes were estimated 21, 26-27 or 29 KDa in different situations of SDS-PAGE. These results showed that treatment of enzyme with heat and reducing agent is necessary for complete unfolding and saturation with SDS. In IEF at least 6 isoenzymes with pI in range of 3.8-4.03 and one with pI of 3.5 were distinguished. Difference of these results with other similar studies can be resulting from differences of Kiwifiuit cultivars and/or experimental methods. 2DE pattern of the purified enzyme showed considerable molecular mass differences between the isoenzymes. In conclusion, the information addressed in this project can help to better characterize actinidin isoenzymes and find their applications.

Chitin, a linear polymer of N-acetylglucosamine residues, has been the most abundant polymer in nature after cellulose. It plays a major role in fungal cell walls. Chitinase enzymes degrade the polymer into its component residues by breaking the β-1,4 glycosidic bonds. As a producer of a variety of chitinase enzymes, the filamentous fungus, Trichoderma, has become an important means of biological control for fungal diseases.In this work, after optimizing the chitinolytic conditions for enzyme production (pH=5, culture duration=48h., temperature=25°C, with shaking), for three randomly selected isolates the chitinolytic activities of 30 Trichoderma isolates were assayed, leading to selection of the most and least active isolates(Trichoderma harzianum with 35 U/mg, Trichodermasp. T26 with 5 U/mg respectively). In order to illustrate the chitinase gene expression in the selected active isolate, T. harzianum8, the SDS-PAGE patterns of the secretory proteins were compared in cultures on different carbon sources and the approximate bands were characterized. Three specific primers were designed for the three chitinase genes, chit31, chit33 and chit42, and specific PCR was performed using genomic DNA of T. harzianum8. The PCR products were confirmed by their restriction pattern using appropriate restriction endonucleases. The results of this stage, proves the presence of all three endochitinase genes in the selected isolate, T.harzianum8.The results of this study performed on T.harzianum8, shows that this isolate can be used for further studies in biological control of fungal diseases.

Aquatic invertebrates have been identified in most parts of the world, but in Asia, especially Iran, such detailed studies have not been done. In the present study we are trying to identify the macroinvertebrates genera in Marbor River and to study the effect of season and sampling sites on their abundance and distribution. Sampling has been carried out in 5 sites along the Marbor River in summer, autumn and winter 2002 and spring 2003. The samples were sorted in laboratory and the larvae and nymphs and adults of some orders were identified to the order, family and genus levels. Also, the physical characteristics of each site have been measured and recorded during the sampling. The results include the identificatin of 7 classes, 12 orders, 34 families and 37 genera as following: Seven genera of Coleoptera, ten genera of Ephemeroptera, one genus of Hemiptera, three genera of Odonata, five genera of Plecoptera, four genera of Trichoptera, four genera of Bassomatophora, one genus of Amphipoda, one genus of Veneroida, one genus of Pharyngobdellida, orders of Diptera and Tricladida to family level and Oligochaeta to class level were identified. The effects of site and season upon the larva abundance were also studied using the two way ANOVA. The results revealed that the number of larvae were significantly different in different sites and seasons.

Lecithin and Vit A have been showed to have a role in process of memory and learning. In this study the effect of co administration diets lecithin(Lc) and vitamin A (RA) on spatial learning of 84 adults male (250 gr/Bw) NMRI rats were investigated. All rats were controlled and trained in T-maze during 9 days. The rats were divided into 12 groups as follow: group 1-3 (Lc, 120, 240 480 mg/Kg) by oral administration for 9 days, group 4-7 (VitA, 40000, 80000,120000, 160000 Iu/Kg) by oral administration for 5 days, group 8-9 (water gavaged for 9 or 5 days), group 10 (have no administration) group 11 (Lc 120 & VitA 80000), group 12 (Lc120 & VitA 120000) administration by gavage (0.1 ml/Kg). All administrations were done 1 hour before every experiment. Statistic analysis showed that Lc and VitA (alone or together) have significant role in spatial learning . It seems that RA caused an increase in acetyl choline transferase activity. As a result of this action, synthesis of acetyl choline from Lc happens, and also the increase in acytyl choline, release causes improvement in spatial learning.

Caspian shad is a commercial fish of Clupeidae in Caspian Sea and biological characteristics of the fish has not been studied before. In the study, 180 specimens of the fish were collected from Southeast coasts of the Caspian Sea quarterly from November 2001 until June 2003 and beach seine and gill nets were used to catch them. Main purpose for the study was determining food items and feeding changes in fish age, sex, station and le season after invasion of ctenophore (Mnemiopsis leidyi) in Caspian Sea. The fish had Fork length, weight and age, 103-232 (158.8±24.4) mm, 16-130 (52.2±20.6) g and 2-5 (2.64±0.7) years old respectively , If and Vacuity Index, Intestinal Relative Length and Index of Fullness of them were determined 12.8%,0.51 ±0.02 and 168.7±192.1 respectively. The study showed Alosa caspia caspia feeds on numerous food items and phytoplanktons (Rhizosolenia and Spirogyra) comprised about 4.5%, Zooplanktons (Foraminifera, Copepoda, Cirripedia, Bivalvia larvae etc.) comprised 95.0% benthic animals (such as Gammaridae) and bony fishes (larvae and eggs) about 0.5% of food abundance in its digestive tract. This study showed these zooplanktons are increase of Mnemiopsis leidyi in Caspian Sea, so Index of Fullness (IF) and growth the fish is reduced.

Birdsfoot trefoil (Lotus corniculatus L.) is one of the legumes that are important as a food source for domestic animals. There are some problems about spring or fall cultivation of this plant species in cold and semi-cold regions that, seeds need delay in germination after fall cultivation, until temperature became suitable for them. In this study, by using of some allelopathic compounds that do not have negative effect on percentage germination and seedlings growth, the time of starting germination delayed. The effects of caffeine, ephedrine, vanillin, ABA, Eucalyptus (Eucalyptus camaldulensis) and Walnut (Juglans regia) leaf extracts and Onobrychis (sativa Onbrychis) seed extract using soaking and non-soaking methods were studied on different germination indicators in Lotus comiculatus. Among tested inhibitors, although 700 and 1000µM concentration of ABA (using soaking method) decreased the percentage germination but in both methods ABA in comparison with other inhibitors delayed starting germination with no negative effect on seedlings growth.