IRANIAN JOURNAL OF BIOLOGY
Year:2007 | Volume:20 | Issue:1|Papers Count:19

The genus Aspergillus (Anamorph) belongs to Deutromycets and has several species. Some of the species infected human, animal, plants and nuts.  Most of these species have ability to degrade plant components by production of pectinase enzyme. The species of Aspergillus flavus and Aspergillus niger are the most popular species of this genus. Although these species could be identified using morphological characters, the interspecific and intraspecific variation could not be evaluated.  Regarding pectic enzyme serection by the species, pectic zymogram technique was used as a simple and usefull method to identify the species and to detect inter and intraspecific variation. Initially the collected samples were transferred to the laboratory and after preparation were transferred on the appropriate media. The pure cultures were obtained for the sample with Aspergillus characteristics. Then Aspergillus fungi were identified microscopically based on morphological characters.  As a result, 40 isolates of A. niger and 30 isolates of A. flavus were recognized.  Then pured sampeles were transferred to liquid media contaning citrus pectin as a sole carbon source to induce the secretion of extracellular pectinase enzymes. After incubation for an optimised period the secreted pectinase enzymes was extracted and concentrated by Cephadex G150 and then loaded on the polyacrilamide horizontal gel and electerophoresed. There were 18 zymogram patterns for A. niger and 8 for A. flavus. The results based on the comparison of the zymogram patterns showed that there is inter and intraspecific variation for studied Aspergillus species.  It seems this technique could be used not only for the species identification, but also use to study of epidemiology of the fungs.

Brucellosis has always high incidence in Iran, especially we are facing a new outbreak of the disease since 2002. Bakhtiiari tribe sheep enter to the central region of Iran from Iraq border, and therefore can easily introduce new species and/or biotypes of Brucella SPP to these regions. The aim of this study was to determine the species and biotypes of Brucellae that are present in the central region of Iran. We studied 150 Brucella isolates from aborted fetuses of sheep and cow. After identification of species of the bacteria, DNA was extracted and then parts of omp2a and omp2b genes of the bacteria were PCR amplified. The PCR products were digested by PstI restriction enzyme and the produced patterns of RFLP were analysed. Molecular technique of RFLP results demonstrated that only 135 samples were infected with Brucella melitensis biotype I and 15 samples demonstrated RFLP pattern similar to B. abortus (uncharacterized biotypes) or B. melitensis SPP (biotypes other than biotype 1). Our results demonstrated that although B. melitensis biotype I is the main Brucella in central region of Iran but about 10% of the aborted fetuses were infected with different biotypes of either B. abortus or B. melitensis. We are going to further characterize these biotypes in our next study.

Bacterial resistance to antibiotics and other physical and chemical antimicrobial agents generally results from extra-chromosomal DNA (such as plasmids), which usually carry several genes that are responsible for the resistance. In this research 100 strains of E. coli isolated from clinical samples were tested for resistance to antimicrobial agents, such as the antibiotics, heavy metals and UV ray and their MIC and MBC were determined, Then 10 strains with high multiresistance were chosen. For determination of genetical origin of resistance in these bacteria the plasmid profile of them were studied. After the plasmid profile detection (in number and size), ethidium bromide was used for plasmid curing, after plasmid elimination, rate of resistance was detected and original strain and cured bacteria were compared, which indicated that the resistance decreased dramatically following plasmid curing. Thus, genetical origin of resistance can be attributed to plasmids. To confirm these results another experiment was designed by transformation of these plasmids into sensitive plasmid-free recipient bacterium (E. coli HB101). The results showed that in most strains, antibiotics, heavy metals and UV resistances were plasmid-mediated.

Alpha- 1-Antitrypsin (AAT) is a member of a superfamily of serine proteinase inhibitors, and consists of 394 -helices (A-I) and amino acids, which form three b-sheets (A-C), nine reactive center loop. Point mutation and environmental factors can destabilize b-Sheet A and distort the structure of the protein to allow a unique protein-protein interaction residues of one serpin molecule to be inserted into the b-sheet A of another, that loop-sheet polymerization will be formed. These polymers accumulate within the endoplasmic reticulum of the hepatocyte fromed inclusion bodies which cause a range of diseases such as: neonatal hepatits, Juvenil cirrhosis and adult hepatocellular carcinoma, emphysema, and thrombosis. In this work it has been studied the conformational factors (Temperature, concentration and incubation time) on AAT polymerization. Using spectrofluremetery, turbidometery, circular dichroism, and flourometeric methods. The results of nondenaturing polyacrylamid gel electrophoresis confirmed several steps in polymerization, in presence of above mentioned environmental factors. Accordingly native of AAT migrated as a monomeric band where formed multimeric species of loop-sheet polymer seen. In conclusion it has been established that incubation temprature, concentration can cause essential variation in the structure of AAT, and leads to its di,tri,oligo and polymerization. In addition, the polymerization occures with different rate and this structural changs accounts the activity of AAT.

The knowledge of the effective factors to maintain, revive and exploit herbal covering regions in which the soil is facing water and nutritional shortage, or even the kinds of plants suffering from salinity and water shortage is of essential importance. In soils suffering from insufficient nutritional elements, the continuation of plant life depends on presence of microorganism such as mycorrhizal fungi. Mycorrhizal fungi are useful symbionts for plants, and helps plants to absorb water and nutrients such as phosphorus, nitrogen, potassium and other minerals. The use of mycorrhizal fungi could also help remove some fundamental problems of stabilizing jungles and green spaces. In this study two regional parks, (Taleghani park and Cheetgar park), which are different in regards of stability and growth of Tehran pinus species (Pinus eldarica) and in case of (Robina pseudo acacia) had been selected and were studied and compared from view of pedology. On the other hand in regard of biological factors, mycorrhizal colonization, root phosphorus and root proline of the selected trees were examined. The soil of whole regions was sandy loam, the pH was the same in whole regions, the amounts of Na, Cl and EC were more in soil of Taleghani park. Pinus trees of Taleghani park which have better growth comparing to pinus trees of Cheetgar park region, had significantly (P£ 0.05) more root symbiosis than pinus trees in Cheetgar Park region. Acacia trees in both regions had rather similar growth and there was not a significant difference between the two regions. There was no significant difference in the average of spore numbers for pinus rhizospher between two regions, where the number of spores in rhizospher of acacia trees in Taleghani Park comparing to the station 2 of Cheetgar Park was significantly (P≤0.05) more. Proline content in root of pinus and acacia in Taleghani Park was significantly more than that in Cheetgar Park. Root phosphorus concentration for pinus and acacia was significantly higher in station 3 of Cheetgar park than other stations. There was no significant difference for phosphorus in root of acacia between different stations. Taleghani Park could be considered as a limiting factor for growth of pinus trees in this region. Generally, mycorrhizal fungi are aboundant in soils with low plant nutrients. In contrast, we found lower mycorrhizal colonization in Cheetgar Park and it could be considered as another growth limiting factor for pinus trees in this region.

Panmictic equilibria between generations do not occur in natural populations. Gene conservation programs in beech will preferably use seed material for the regeneration of resources. Therefore, knowledge of processes changing structures and amounts of genetic variation during generative stand reproduction becomes very important. In this study, at 10 beech population along the Hyrcanian forests, genetic composition of mother trees (at least 40 trees per population) and their progenies (7 seeds of each of the 10 mother trees) were determined by means of microsatellite markers. The allelic structure of mother trees and seeds indicated that all loci showed high polymorphism in all populations. Allelic multiplicity in the seed generation is generally higher than in mother trees, which indicate effective gene flow from neighbor stands. Number of frequent alleles (> 5%) dose not vary significantly, however, number of locally common alleles (£ 25%) in seed generation was higher than mother trees. What is important that any regular deviations from the Hardy-Weinberg structures were not observed? In comparison with mother trees, we have detected a slightly reduction in genetic diversity, probably due to an inappropriate seed collection strategy limited to a few trees. These data suggesting an increasing the number of mother trees would be a guarantee for conservation of genetic diversity of beech.

Brassica napus (Canola) with mosaic symptoms from Varamin (Khaveh), was fixed on B. rapa in green house. The samples were collected and tested against TuMV by D.A.Sandwich ELISA using specific antibody (DSMZ, Braunschwieg, Germany). Mechanical inoculation of ELISA positive samples caused necrotic local lesions on Nicotiana tabacum L cv. White Burley and Chenopodium amaranticolor Coste & Reyn, systemic mosaic on- Petunia hybridia Vilm , Nicotiana glutinosa L., Brassica pepo L., Brassica rapa L., Zinnia elegans L. Purified sample of virus revealed in the sucrose density gradient. Using spectrophotometery at wave lengths of 260 nm and 280 nm the purified virus Varamin of isolate had an absorbance ratio of 1.4. Antiserum was produced by injection of purified virus to New Zealand white rabbit. Electron micrographs of negatively stained row suspension of infected plants and purified virus preparations revealed flexuous, filamentous particles. Iranian isolate virus was transmitted from TuMV– infected plants to healthy plants by Brevicorye brassica in a non– persistant manner.

In this paper effects of mistletoe on 4 primary macronutrients, Nitrogen, Phosphorus, Potassium and Calcium in two the most prevalent mistletoe’s hosts in Hyrcanian forests namely Hornbeam and Ironwood trees was studied by leaf analysis technique. Leaf samples collected from infected and uninfected branches of infected to mistletoe individuals and from completely healthy trees (without any mistletoe) with approximately similar DBH, height, appearance and physiological conditions near to each other. The samples moved promptly to the laboratory and oven dried for 48 h. at 60 oC before being ground to a powder, then digested and analyzed for Nitrogen, Phosphorus, Potassium and Calcium. The results showed that the amount of potassium has increased in the infected branches relative to perfectly healthy trees’ branches in each two host species. The amount of total nitrogen decreased in infected branches leaves relative to uninfected trees’ leaves. Whereas the other nutrient did not show the significant differences among groups.

Mycorrhizal and non- mycorrhizal bean plants (phaseulus vulgaris) were treated with 100 ml solution containing 20 and 40 mM NaCl at three days interval in a pot culture experiment. The results showed decline in root infection by VAM as salinity accumulates. Sugar and protein content in mycorrhizal plants were significantly higher than those in treatments. Prolin and chlorophyll b content were not affected by salinity and mycorrhiza. At low and medium level of salinity K, Ca and P concentration were higher and Na concentration was lower in mycorrhizal plants. Results are discussed with respect to the role of VAM on diminishing the salinityeffects on plants.

Heterocystous cyanobacteria play a significant contribution in maintaining soil fertility. Despite the occurrence of paddy fields, wheat fields and woodland in north Iran, less attention has been paid to the role of cyanobacteria in these ecosystems. In this study an attempt was made to growing soil inoculums on BG-11 medium. Their incidence with N, P, K, C, pH and EC of soils was also determined. Totally twenty species were identified in paddy fields, twelve in wheat fields and three in woodland. The results showed that species of Nostoc and Anabaena are ubiquitous in all sites except one of paddy field stands, where its EC was the highest and Calothrix stagnalis was the only species found in the stand. It is suggested that this strain is probably resistance to salinity. This is supported by statistical analysis of species and colonies number with EC that showed negative correlation. The forest had higher percentage of N, P, K, and C than other regions differed mainly in number of species and also there isn’t any branching species in this region. The scarcity of cyanobacteria in forest can be probably limited by low pH and EC. However soil analysis showed that phosphorous amount has a highly positive correlation with the frequency of cyanobacteria in all of stands.

Vitex agnus castus is a well known plant in herbal medicine from centuries ago e.g. some people used its leaves and fruits for milk increasing. In present research the effects of V.a.c leaf extract on serum concentration of prolactin hormone has been investigated. Selective dosages of V.a.c were orally administrated to the female rats during the days of pregnancy. In the control group of rats the above procedure was applied, but distilled water was administrated instead of V.a.c extract. In order to blood sampling from each rat, at each stage (7rd and 15rd day of pregnancy) the animal was anaesthetized by inhalation of ether and the fresh blood sample was taken off from its heart and followed by the animal was sacrified. The serum was separated from each sample by centrifugation. These serums were used for measurement of prolactin hormone by RIA (Radio Immuno Assay) method. The data were analyzed by SPSS, ANOVA, MANOVA and LSD test at p<0.05. It is concluded that oral administration of 2, 10 and 70 mg/kg/day of V.a.c leaf extract in 7 day of pregnancy, significantly increased serum prolactin with compared to the control group of rats but not in 15 day. So altogether we concluded that: 1) the effect of V.a.c., is probably dependent on serum prolactin level before administration and dosage of V.a.c. extract and all of dosages had not the same effect. 2) The increase of prolactin level in seven day rats probably is the luteotrophic effect of V. a. c. leaf extract.

This study was performed in order to determine morphology and morphometry of Gerbillinae subfamily in Geno Biosphere Reserve, Hormozgan Province. In this order we used live trapping method for the sampling of rodents. In total, 70 rodent specimens were collected. The specimens were studied in respect to their morphological, cranial and external characteristics and a few proportions. These specimens included three genus and four species: Persian Jird (Meriones persicus Blanford, 1875), Libyan Jird (Meriones libycus Lichtenstein, 1823), Baluchistan Gerbil (Gerbillus nanus Blanford, 1875) and Indian Gerbil (Tatera indica Hardwicke, 1807).

Epinephelus coioides (family serranidae) is protogynous. This species is one of the most important fishes in Persian Gulf. Protogynous hermaphroditism, or female-to-male sex change, is known for many reef fishes including orange spotted Epinephelus coioides (family serranidae). Gonads at all stages of development in this species were examined in the persian Gulf from may 2001 to September 2002. Demographic data and gonad histology show that E.coioides is a protogynous hermaphrodite that follows a monandric pathway in sexual development. Females exhibited synchronous ovarian development. The sexual transition was found to occure in individuals of 51.2- 105 cm in standard length (SL) and then maturation of the testis tissue begins. Sex reversal to 3 different stages was classified. Transitional E.coioides gonads were characterized by the concurrent degeneration of all oocytes and the proliferation of spermatocysts. The results indicated that female and male tissues are not separated by connective tissue and the two tissue types are intermixed during the course of sex reversal. Regarding to the results of this research, it seems that the period of spawning in Epinephelus coioides is in May- June and sex reversal begins in the transitional after spawning in the functional females.

Many vertebrates have L-gulonolactone oxidase (GLO) in liver or kidney, the enzyme catalyzing the last step in ascorbic acid biosynthesis; they can synthesize this vitamin as de novo, which is necessary for growth, health, bone formation, and reproduction. Due to this fact, 3 species of acipenserids were considered for effects of different levels of vitamin C. Results showed that in juvenile Siberian sturgeon, there were no significant differences in final weight after 16 weeks treated by 0 or 300 mg kg-1 ascorbic acid (P³0.05). Also, there were no significant differences in growth and survival among groups of lake sturgeon after 38 days supplemented with 0, 50, 250, and 1250 mg kg-1 ascorbic acid (P ³0.05). Supplemented diets with 0, 100, 200, 400, 800, and 1600 mg kg-1 of ascorbic acid in great sturgeon also showed no significant differences in growth rate and final weight, however, survival showed enhancement in some treatments. Results obtained from this study showed that due to presence of GLO in this specimens, acipenserids do not require this vitamin in normal conditions, since rearing conditions such as high density, stressors, and pathogens, the need for this vitamin might increase in these fish, and it seems that, it is reasonable to use this vitamin in sturgeon diet in artificial rearing condition. In addition to tissue concentration, vitamin C can play a role as a peroxidant against free radicals.

Isolation of pure lines that had superior and high productive potency and had also resistant, is one of the best breeding strategy at sericulture. It is studied heterosis, GCA and SCA for cocoon characters in the five local groups and two breeded pure lines of silkworm Bombyx mori L. and their hybrids. From obtained results, shell cocoon percentage, shell cocoon weight and cocoon weight are affected by genetical groups (P<0.05). Average of these traits at five local groups were %18.698, 0.2918gr and 1.5970gr respectively and at two breeded pure lines were %20.280, 0.2614gr and 1.2959gr respectively. Heterosis comparisons showed Khorasan-lemon ×110 hybrid had superior performance significantly (P<0.05). GCA for above traits at local groups and SCA and heterosis at their hybrids including pure lines with local groups had high amounts. Therefore local groups should be noticed for breeding and cross-breeding programs at sericulture.