IRANIAN JOURNAL OF BIOLOGY
Year:2003 | Volume:15 | Issue:3|Papers Count:7

Fagus orientalis Lipsky is one of the most abundant and economically important species of woody plants in North Iran. Izozyme diversity of beech was investigated among 14 Iranian beech populations originating from the major part of distribution range of this tree species in Hyrcanian zone 9Southern coasts of Caspian Sea).Enzyme variation of beech populations was studied using 6 isozyme Loci at 3 systems including Peroxidase (PX), leucine aminopeptidase (LAP) and glutamate oxaloacetate Transaminase (GOT) by starch gel electrophoresis. Among 21 observed alleles, 10 rare alleles (less than 5% of the allelic frequency) and 10 specific area alleles (observed in less than 5 populations) were detected. Results indicated that all specific area alleles are rare ones too. The population of Neka at elevation 900 m from sea level and Kheirud at elevation 600 m showed the highest number of specific area and rare alleles. In spite of important ecological differences among the studies populations (from East far to West far and from lowest to highest limitation of beech forests in Iran) no relation could be found between izozyme electrophoresis pattern and geographical distribution.

This investigation was set out to determine whether mercury at a very low dose (4 ppm) induces testicular damage on murine testis, and if so whether the toxic effects of mercury could be prevented by zinc. One of the following solutions was administered in the drinking water of Balb/C male mice: (1) 4 ppm HgCl2; (2) 800 ppm ZnCl2; (3) 4 ppm HgCl2+800 ppm znCl2; or (4) deionised water; for 12 weeks. At the expiration of the treatment period, animals were sacrificed, testes excised and weighed, and epididymal sperm number taken. The testes were processed for histological examination. Both zinc and mercury significantly (P<0.05) decreased the absolute and relative testicular weights, with mercury producing the highest reduction in weight. Mercury reduced significantly (P<0.05) the epididymal sperm number, while zinc and mercury/zinc produced statistically same effect with control on the sperm number. Histological study showed that mercury at the concentration employed produced remarkable degenerative lesions on the testes, as the zinc-treated group showed a normal morphology. Majority of the animals in the mercury/zinc treated group exhibited complete or partial protection as evidenced by the morphology of the somniferous tubules. Zinc prevents mercury-induced testicular damage in mouse. These findings highlight the risks exposure to inorganic mercury might pose to male reproduction of mice, and suggests possible therapy with zinc.

Osteology of Zagros toothcarp, which is endemic to karum basin head tributaries in Chahar-Mahal-va-Bakhtiari province, for it being endemic and tiny, has not drawn any attention so far. In this study the superfacial skull bones including the skull roof, opercular series, suspensorium, jaws, and circumorbitals were examined. The skull roof consists of the nasals, frontals, sphenoid, pterotics, epiotics, exooccipitals, and supraoccipitals. The opercular series consist of opercles, subopercles, interopercles, and preopercles. The suspensorium consists of hyomandibulae, symplectics, quadrates, ectopterygoids, endopterygoids, and palatines. The upper jaw includes the premaxillae circumorbital bone found in this species is the lachrymal. This study shows that this species bears all the characteristics of the related order, family, and genus and in general it is similar to the other related species and like them lack the parietal and the metapterygoid.

In order to study the diversity and abundance of macroinvertebrates and biological indicators of Zayandeh-rood River, nine sites along the river course in about 230 Km, from Cham-Hydar (below Zayandeh-rood Dam) to Varzaneh were selected. Three samples were taken from each site in four seasons, Autumn and Winter 1998, spring and Summer 1999 (108 samples in total). Sorting and counting of the samples were done in the laboratory and the macroinvertebrates of each sample were identified to the family level using microscope and identification keys. The diversity and abundance of the families of each site were compared and the indicator taxa were specified. BMWP biotic index was calculated for each sample and the statistical differences between sites and seasons were determined using ANOVA.The results of 108 examined samples showed that some families such as; Baetidae and Heptagenidae (Ephemeroptera), Hydropsychidae and Philopotamidae (Trichoptera), and Gammaridae (Crustacea) were realized to be the indicators of upstream sites (1-5) containing relatively unpolluted water. These families were not present in downstream sites 96-9) nor were seen in high abundance. In contrast, the families of Chironomidae (Diptera), Physidae, hydrobiidae and Planorbidae (Gastropoda), and Oligochaeta were realized to be the indicators of downsteam site and they may be present in upstream sites in lower abundance. Furthermore, the calculation of BMWP score showed that the upstream sites in contrast to the downstream sites had higher scores and there were strong significant differences between sites in this regard (P<0.001). The results also confirmed the separation of upstream and downstream sites with regard to the biological indicators. Also, comparison of the pollution indicators of different sites revealed that the biological indicators may confirm the quality of the water of the sites examined.

The greatest effect of drought is desertification, which is because of the lack of rain in some regions and mans over-exploitation in semi-arid and arid regions of the world. One approach to control this problem is to grow plants with the ability to withstand drought. Among vascular plants which are desiccation tolerant, there are a group of flowering plants and ferns, which can survive water deficits down to completer air- dryness, and which, when they rehydrate, resume normal physiological function. Such plants are referred to as resurrection plants. By producing transgenic plants if resurrection plants gene with such ability be transferred, we can avoid or reduce the damage of drought by their cultivation in such harsh environments. In this study, N. vellea a resurrection plant in controlled environmental chamber met a period of drougt stress up to complete dehydration and were dehydrated again, which resumed its physiological functions as soon as rehydrate. Non resurrection plant nephrolepsis did not recover and died.By using the method of cell viability tests (Levitt, 1960) dehydrated resurrection plant cells were viable up to 0% RWC. Total protein measurements of non resurrection plants during dehydration showed loss of proteins but the resurrection plants didn't show such a loss. Protein profile studies of both plants were different. In non resurrection plant some bonds were reduced or deleted but in resurrection plant some new bonds we appeared and some were reduced or increased. This might be and indication of enzyme changes in resurrection plants during dehydration up to complete dryness. These proteins, probably are proteins that by synthesis of soluble sugars resume the ability of desiccation tolerance in resurrection plants. Also, the study of soluble sugar contents in protoplasmic drougt tolerant plants, were in accordance with the vitreous state theory of membrane protection.

The genus Festuca. belongs to the tribe Poeae R. Br. (=Festuceae Dumort.) and to the family of Poaceae. Because of their well adaptation to the different environmental conditions and pasturage value especially F. ovina, many botanists have frequently studied these plants. A phenetic analysis of the Iranian species of the Festuca subg. Festuca is presented here, these species concluded that F. ovina L., F. rubra L., F. heterophylla Lam., F. pinifolia (Hack.) bornm. and F. sulcata (Hack.) Beck. The plant materials studied here, in view point morphology and anatomy, were either collected from various regions in Iran, during the Years 1999-2001, or botained from several different herbaria of Iran. About 23 populations of above mentioned species were compared using a total of 21 quaulitative and quaunitative morphological characters, additionally anatomical studies were performed with 15 diagnostic characters on 15 specimens by cross section of leaves. Statistica software was utilized to perform cluster analysis. The results of cluster analysis reveal close relationship between F. sulcata and F. ovina. This confirms the opinion of Parsa in "Flore de L 'Iran" and Biossier in Flora Orientalis who had suggested the F. sulcata to be a subspecies (infraspecific relations) of F. ovina. The morphological similarities among the populations of these two secies further confirm this finding. Tow complexes species f. ovina and F. rubra present morphologic diversity in Iran and contain a lot of subspecies, varieties and cultivars. F. heterophylla are introduced as an independent species and f. pinifolia's position in the cluster analysis, separates it from all other specimens. Finally, our results ere compared and discussed with the results of others authors.

Effect of different salinity treatment of NaCl (0,50,100,200 and 300 Mm) during tillering in two wheat cultivars 9Ghods: salt-sensitive, Boolani: salt-resistant) on relative growth rate (RGR), root water content and shoot water content was studied under greenhouse conditions. In general, in response to salinity treatments: a) the loss in shoot water content was more then that of the other growth parameters, b) root water content showed the least decrease as compared to other growth parameters, c) the decrease in the growth parameters of Ghods was more than that of Boolani. Therefore, on the basis of the present data, we can conclude that Boolani is more resistant to salinity, compared with Ghods.