مجله علوم دانشگاه تهران
سال سی و ششم شماره 2 (تابستان 1389)

Effect of boron deficiency on growth, leaf pigments and photosynthesis was studied in turnip (Brassica rapa L.) plants grown under three different light conditions (50, 100 and 150 µmol m-2 s-1) in a hydroponic medium for one month under controlled environmental conditions. Two levels of B treatment including adequate (25 µM) and low (2.5 µM) boron supply were applied. Dry matter production of shoot and root was reduced under low boron supply up to 79% and 82% respectively. Re-supply of deficient plants by boron during the last week of growth period increased significantly plants dry matter production. Higher light conditions increased not only plants growth but also boron uptake. Plants susceptibility to low boron supply was higher under high compared with lower light conditions. Leaf chlorophyll and carotenoids decreased under boron deficiency conditions while leaf anthocyanins and free soluble phenolics in leaf and roots increased in low boron plants.

In this study, patterns of homoplasy for 8 vegetative and 14 reproductive morphological characters were assessed in the phylogenetic context deduced from nrDNA ITS data for 115 species including 109 members of Astragalus senso stricto clade and 6 representatives of related genera as outgroups. Character states information of these selected characters were obtained from available literature and examined specimens and were scored based on numerical unordered scoring. nrDNA ITS phylogeny was reconstructed using Neighbour Joining method as implemented in PAUP* ver. 4.0 b10. The morphological dataset was then mapped onto the nrDNA ITS tree. Based on the results of this study the highest ci (consistency index) and ri (retention index) were 0.50 and 0.96, respectively for the gum ducts (absence/presence).

In the present study, 230 specimens of Capoeta capoeta gracilis (Keyserling, 1861) from Sefidroud River were examined seasonally from Autumn 2008 to Summer 2009. This survey was carried out in two stations including Sangar and Manjil. Four species of parasites were found including, Clinostomum complanatum, Diplostomum spathaceum (Trematoda) and Rhabdochona hellichi, Contracaecum sp. (Nematoda). Ecological indices including Richness, Dominance, Sorrenson quantitative and qualitative Similarity, Evenness and Shannon diversity indices were studied in two stations. Contracaecum sp. was dominant parasite in both study area. There were no significant differences in the prevalence, mean abundance and Shannon diversity index of parasites between Sangar and Manjil. Variations in the prevalence and mean abundance of parasites in different seasons and length groups are discussed.

In the line of widespread studies on sulfonamides, anti-tumoral effects have been reported for this drug family. Appearing of these anti-tumoral effects in sulfonamide drug family has been attributed to some cell and molecular mechanisms such as inhibition of membranous carbonic anhydrase, prevention of the formation of microtubules, arresting of cell cycle and prohibition of angiogenesis. In this research project, sodium sulfabenzamide drug with low inhibitory potency for carbonic anhydrase was selected until its net effect on some cellular processes such as apoptosis and cell cycle arrest to become able to be placed under study. Using MTT test, prevention concentration of drug for 50 percent reduction of the cells viability in the medium was obtained as 10.8 mM which was considered as the basal concentration for treatment of the cells during the whole steps of the work.

The thalassinidean shrimp fauna of Iran is unknown. Specimens of the present study were collected from 11 intertidal localities of the Qeshm Island. In total, seven species belong to four families are recorded including: Upogebiidae (Upogebia carinicuda), Callianassidae (Neocallichirus indicus, Podocallichirus masoomi, Michaelcallianassa indica, Callianassa bouvieri) Gurretiidae (Gourretia coolibah) and Callianideidae (Callianidea typa). All species were new record for the Qeshm Island. The results revealed that these shrimps are dependent to special habitat types. The habitat preference of most species in the intertidal zone was either to sandy or sandy-muddy areas. But, some species were collected from the boulder dominated areas.

Plants take different strategies in response to salt stress. In this investigation, the effect of NaCl on fresh and dry weights, content of proteins, proline, sugars, pigments and phenolic compounds were studied in calli of T.foenum-graecum, T.aphanonoera, T.eliptica and T.tehranica in vitro. Callus tissues were established from surface sterilized, hypocotyl explants of 10 days old seedlings on MS medium supplemented with 0.5 mg l -1 2,4-dichloro-phenoxy acetic acid (2,4-D) and 1 mg l -1 Kinetin (Kin). The calli were subcultured on MS medium suplimented with 0, 50, 75, 100, 150 mM NaCl after 35 days. Fresh and dry weight decreased in calli of all four species. Proline content, phenolic compounds, soluble sugars, oligosaccharids and reducing sugars increased under salinity in calli of all four species whereas protein content and polysaccharids decreased under salt stress in calli of all the species.

There are differences in the opinions of different workers on the exact number of larval stages during the life cycle of Artemia, as well as the sequence of events during these stages. As the previous studies on the larval morphology of A. urmiana and A. parthenogenetica have been using light microscopy techniques, only, we studied the post embryonic development of A. urmiana and A. parthenogenetica by light microscope and scanning electron microscope to increase the resolution of observations and to describe characteristices that are not visible under the light microscope. Cysts of both species were obtained from Artemia Reference Center of Urmia University, and were cultured under similar controlled laboratory conditions. In each larval stage, several organs including antennules, antennae, phyllopod and external genital organs were detached and studied under light microscope equipped with camera Lucida and scanning electron microscope

Salt and drought stresses are among major constraints to rice (Oryza sativa L.) production. In order to find some keys for better understanding of the mechanism of salt tolerance in rice, we compared the impact of salinity and drought on seedlings of three rice cultivars including IR29, FL478 and Gharib, which are salt sensitive, tolerant and moderately tolerant respectively. The two days seedlings were transferred to MS media complemented with iso-osmotic concentrations of NaCl (0, 50, 100 and 150 mM) or mannitol (0, 100, 180 and 275 mM) for 10 days. Both salt and drought stresses resulted in reduction of shoot biomass, alteration of protein content and antioxidant activities in all studied cultivars. However, some isoforms of antioxidant enzymes were induced by drought and suppressed by salinity. Moreover, proline content was considerably increased only under salt treatments.