Iranian Journal of Biotechnology
Volume:5 Issue: 3, Summer 2007

The objective of this research is to identify Arabidopsis thaliana genes encoding acid phosphatases induced by phosphate starvation. Multiple alignments of eukaryotic acid phosphatase amino acid sequences led to the classification of these proteins into four groups including purple acid phosphatases (PAPs). Specific primers were degenerated and designed based on conserved sequences of PAPs isolated from plants, fungi and animals. RNA profiles of Pi-fed and Pi-starved A. thaliana roots were compared with two methods established for gene-family-directed differential display of pap genes. Having analyzed the differentially displayed fragments, seven pap encoding cDNA clones were isolated. One of the clones was a transsplicing product of two genes that encodes an acid phosphatase carrying a zinc-finger domain. Six other clones were predicted to encode secretory phosphatases. Reverse-northern blotting and semi-quantitative RT-PCR revealed distinct expression patterns for each gene under diverse environmental conditions such as Pi starvation, high-salt concentration, cold shock, nitrogen and sulfur deprivation. The presented data can provide some clues for dissecting the possible roles of PAPs in Pi acquisition.

This study involves in vitro androgenesis of Zea mays L. via anther culture. Combination of two embryo induction media (IMSS & YPm) in presence of different colchicine concentrations (0, 100, 200, 250, 300 and 400 mg/l) in the pretreatment medium (IML) and pretreatment duration (0, 3, 6 and 9 days) in two genotypes (DH5DH7 and ETH-M82) were tested. After colchicine pretreatment, anthers were transferred to the induction media without colchicine to induce of embryo like structures (ELSs). The ELSs were then transferred to plant regeneration medium (YPNAS). It was found that in the genotype DH5DH7, colchicine at a concentration of 100 mg/l significantly induced the number of ELSs (19.6). The control (without colchicine) and 400 mg/l of colchicine resulted in lower levels of ELSs (5.8, 5.7, respectively). In this genotype, colchicine pretreatment for 3 days produced highest number of ELSs (16.83) and a large increase in the ELS yield was observed in the YPm medium (14.4). In ETH-M82 genotype, 6 days of pretreatment with 300 mgl-1 with colchicine, produced highest frequency of ELSs (25). Also, in this genotype, a large increase in ELS yield was observed in the YPm induction medium (22.3). The frequency of spontaneous chromosome doubling in control group was very low for both genotypes (7%), but these genotypes were able to produce doubled haploid plantlets from the ELSs (63% doubled haploid) using a low concentration of colchicine in the pretreatment medium (250 mgl-1 for 6 days). At high concentrations of colchicine (300 and 400 mg/l), more morphological and chromosomal aberrations were observed.

The genetic diversity of a large number of pistachio genotypes grown in Iran is not exactly known. Most of the studies on genetic diversity of Iranian pistachio varieties are based on morphological characteristics or isozyme markers. In the present study, the genetic diversity of selected pistachio cultivars along with some wild species were evaluated by Amplified Fragment Length Polymorphism (AFLP) markers. 13 AFLP primers were used for evaluation of 45 pistachiogenotypes. Totally, 506 polymorphic bands with an average polymorphism of 95.2% were detected. Cluster analysis assigned pistachio genotypes into 4 groups. All commercially cultivated pistachios were clustered in group I and II. The wild pistachio genotypes were separated from the cultivated ones. These data demonstrate that AFLP is a reliable tool for analyzing pistachio genetic diversity.

To mutate the Ice Nucleation Active (INA) gene in Erwinia herbicola strains, Tn-5 transposon carried by Psup2021 plasmid was used. This plasmid was transferred to the bacterial cells by electroporation. Electrotransformation was carried out for 2.5 ms at 1800 v and 1 mm distance between the electrodes. Polymerase chain reaction was used for determination of presence or loss of INA gene, using a pair of primers designed for inaZ gene. The ice nucleation activity was tested by the freezing assay technique. The ice- phenotype of the putative mutants were assayed through spraying sunflower seedlings, grown under aseptic condition, with 107 to 108 colony forming units per milliliter of the parent and transformant strains. The treated seedlings were kept at -8C to -10C for 8-10 hours and then transferred back to ambient (laboratory) condition for recovery or expression of freezing damage syndrome. Three out of ten electroporated strains yielded ice- mutants that failed to freeze water droplets at -8C and produce no freezing injury on sunflower seedlings.

A total of 125 Russian Red Pied cows were genotyped for the prolactim-related gene. The PRL-RsaI genotypes were analysed using the Polymerase chain reaction -restriction fragment length polymorphism (PCRRFLP) method. In this breed, the frequencies of alleles were as follows; A= 0.794 and B= 0.206. The frequencies of AA, AB and BB genotypes were 0.598, 0.392 and 0.01; respectively. Results showed that: BB genotype had higher milk yield than AA and AB individuals (P < 0.05). BB genotype showed higher milk fat yield than AA and AB individuals (P < 0.05). With respect to milk fat content (%), the AB genotype had higher levels than the AA and BB individuals (P < 0.05). No differences between the cows of different PRL-RsaI genotypes were found in terms of milk fat yield and milk protein concentration. The results showed that the highest milk and milk fat yields were obtained by cows with the genotype PRL-RsaI BB. The results presented here demonstrate that the prolactin gene may be considered as a marker for dairy traits in cattle.

Human granulocyte-colony stimulating factor (hGCSF) cDNA was expressed in the methylotrophic yeast Pichia pastoris under the control of the alcohol oxidase (AOX1) promoter. An expression vector for hG-CSF secretion was constructed using pPIC9 vector. Higher levels of hG-CSF was obtained using a P. pastoris Mut+ (methanol utilization fast) phenotype. The effects of environmental factors such as, temperature and pH on the P. pastoris cell growth and hGCSF production during fermentation were investigated. Cell growth and hG-CSF production were found to be optimal at 28C and pH 6.0. A fed-batch fermentation process was also developed to obtain high cell density and higher levels of protein expression. Using a high cell density cultivation method, cell dry weight and hGCSF concentration reached 100 g/l and 35 mg/l, respectively. Keywords

The effect of the operating conditions (temperature, time, pH, enzyme level and pulp consistency) used in the enzymatic step of a XP (Cartazyme-hydrogen peroxide) sequence for bleaching Kraft pulp from bagasse on various properties of the resulting pulp and paper sheet products was studied. The quality of bagasse used, was examined by its yield, brightness,viscosity and the Kappa number. Finally, the quality of paper sheets produced were examined by their brightness, breaking length, burst index and tear index. The total number of experiments required for five independent variables was calculated from N=2k+2k+1 equation, in which k is the number of independent variables. The results of 43 experiments performed, were processed using the MINITAB software suite which provided equations that reproduced the values of the dependent variables with less error. The application of the steepest ascent method has been carefully inserted in the experimental design section the identification of themost suitable conditions for optimizing the values of the dependent variables. Based on the results, using enzyme level 6 (IU/g), temperature 35C, pH 5 and pulp consistency 12% for 2 hrs. in the enzymatic step provided paper sheets of acceptable quality.

Twenty six Rhizobium strains were isolated from root nodules of Sesbania sesban (L.) Merr. collected from different regions of Andhra Pradesh. All the 26 Rhizobium strains produced indole acetic acid (IAA), but maximum amount was produced by only five strains in yeast extract mannitol (YEM) medium supplemented with L-tryptophan. The strains were found to elaborate maximum IAA when fed with 2.5 mg/ml Ltryptophan. Cultural requirements were optimized for maximum growth and IAA production. The strains differ in their growth and production of IAA on different carbon and nitrogen sources. Addition of cell wall affecting agents increased the IAA production over controls. The compound was extracted, purified and structurally confirmed as IAA