Cloning of the histidine transport genes from salmonella typhimurium and characterization of an analogous transport system in escherichia coli

The genes for the well-characterized high-affinity histidine transport system of S typhimurium have been cloned in λgt4. Genetic and physiological analyses of the analogous transport system of E coli were undertaken in order that available λ vectors, recombinant DNA techniques, and a genetic selection for transport function might be used to isolate the Salmonella genes. The presence of the transport genes on a 12.4 Kb cloned DNA fragment has been confirmed (1) genetically, by complementation studies; (2) physiologically, by the rates of histidine uptake by bacteria containing this DNA; and (3) by demonstrating that the cloned DNA codes for the previously identified transport proteins J and P. The isolated fragment carries the entire transport operon, the argT gene and the ubiX locus, but neither the purF gene nor the ack/pta loci.     

Continuous rearing on Ephestia kuehniella reshaped quality of the parasitoid wasp Trichogramma brassicae (Hymenoptera: Trichogrammatidae)

Continuous mass rearing of Trichogramma brassicae (Bezdenko) at commercial mass-rearing insectaries may affect both quality and performance of natural enemies. In the present study, we studied the quality and performance of a colony of T. brassicae reared for over 45 generations (G) on Ephestia kuehniella Zeller using two-sex life table parameters and parasitism capacity. Our results revealed that although different generations showed no significant difference in terms of female longevity or total life span until G35, G5 and G10 had the highest values of fecundity, gross reproductive rate (GRR), net reproductive rate (R₀), intrinsic rate of natural increase (r), and finite rate of increase (λ). No significant difference in male adult longevity was found among different generations. The longest and shortest mean generation times (T) were found in G10 (13.65 ± 2.31 d) and G45 (13.25 ± 3.37 d), respectively. The finite rate of parasitism (ω) ranged from 0.355 ± 2.332 host/parasitoid/day in G5 to 0.242 ± 0.017 host/parasitoid/day in G45. However, ω did not show any significant difference until G20. These results indicate that T. brassicae wasps held under continuous laboratory rearing declined in quality after 20 generations, and therefore periodical rejuvenation of the colony by adding feral parasitoids is strongly recommended.     

A contribution to the knowledge of Agathidinae (Hymenoptera: Braconidae) from Iran with description of a new species

The subfamily Agathidinae was studied in parts of northern Iran. Six species were collected and identified. Among them, Cremnops desertor (L., 1758) is recorded for the first time from Iran. Lytopylus persicus Farahani & Talebi sp. n. is described and illustrated. A key to the West Palaearctic species of the genus Lytopylus Förster and an updated checklist of Iranian Agathidinae are provided.     

The relation between the genetic architecture of quantitative traits and long-term genetic response

The genetic architecture of a quantitative trait refers to the number of genetic variants, allele frequencies, and effect sizes of variants that affect a trait and their mode of gene action. This study was conducted to investigate the effect of four shapes of allelic frequency distributions (constant, uniform, L-shaped and U-shaped) and different number of trait-affecting loci (50, 100, 200, 500) on allelic frequency changes, long term genetic response, and maintaining genetic variance. To this end, a population of 440 individuals composed of 40 males and 400 females as well as a genome of 200 cM consisting of two chromosomes and with a mutation rate of 2.5?×?10^?5 per locus was simulated. Selection of superior animals was done using best linear unbiased prediction (BLUP) with assumption of infinitesimal model. Selection intensity was constant over 30 generations of selection. The highest genetic progress obtained when the allelic frequency had L-shaped distribution and number of trait-affecting loci was high (500). Although quantitative genetic theories predict the extinction of genetic variance due to artificial selection in long time, our results showed that under L- and U-shapped allelic frequency distributions, the additive genetic variance is persistent after 30 generations of selection. Further, presence or absence of selection limit can be an indication of low (<50) or high (>100) number of trait-affecting loci, respectively. It was concluded that the genetic architecture of complex traits is an important subject which should be considered in studies concerning long-term response to selection.     

Eimeria tenella: B-cell epitope mapping following primary and secondary infections

Immunisation against coccidiosis has become more reliable and effective with improved administration techniques for new vaccines. On the other hand, an ideal coccidial vaccine should contain both B- and T-cell immunogenic epitopes. Fine specificity of B-cell epitopes recognised by antibodies prepared following primary and secondary infections with Eimeria tenella were studied using "PepScan" techniques. Mapping of B-cell epitopes within an antigenic sequence from E. tenella showed that four distinct types of epitopes were recognised by the host immune system during the primary and secondary infections with the parasite. These observations demonstrated that new epitopes are also involved in induction of antibody responses following the secondary infection.     

Polymorphism of visual pigment genes in the muriqui (Primates, Atelidae)

Colour vision varies within the family Atelidae (Primates, Platyrrhini), which consists of four genera with the following cladistic relationship: {Alouatta[Ateles (Lagothrix and Brachyteles)]}. Spider monkeys (Ateles) and woolly monkeys (Lagothrix) are characteristic of platyrrhine monkeys in possessing a colour vision polymorphism. The polymorphism results from allelic variation of the single-locus middle-to-long wavelength (M/L) cone opsin gene on the X-chromosome. The presence in the population of alleles coding for different M/L photopigments results in a variety of colour vision phenotypes. Such a polymorphism is absent in howling monkeys (Alouatta), which, alone among platyrrhines, acquired uniform trichromatic vision similar to that of Old World monkeys, apes, and humans through opsin gene duplication. Dietary and morphological similarities between howling monkeys and muriquis (Brachyteles) raise the possibility that the two genera share a similar form of colour vision, uniform trichromacy. Yet parsimony predicts that the colour vision of Brachyteles will resemble the polymorphism present in Lagothrix and Ateles. Here we test this assumption. We obtained DNA from the blood or faeces of 18 muriquis and sequenced exons 3 and 5 of the M/L opsin gene. Our results affirm the existence of a single M/L cone opsin gene in the genus Brachyteles. We detected three alleles with predicted lambdamax values of 530, 550, and 562 nm. Two females were heterozygous and are thus predicted to have different types of M/L cone pigment. We discuss the implication of this result towards understanding the evolutionary ecology of trichromatic vision.     

Site-Specific Keloid Fibroblasts Alter the Behaviour of Normal Skin and Normal Scar Fibroblasts through Paracrine Signalling

Keloid disease (KD) is an abnormal cutaneous fibroproliferative disorder of unknown aetiopathogenesis. Keloid fibroblasts (KF) are implicated as mediators of elevated extracellular matrix deposition. Aberrant secretory behaviour by KF relative to normal skin fibroblasts (NF) may influence the disease state. To date, no previous reports exist on the ability of site-specific KF to induce fibrotic-like phenotypic changes in NF or normal scar fibroblasts (NS) by paracrine mechanisms. Therefore, the aim of this study was to investigate the influence of conditioned media from site-specific KF on the cellular and molecular behaviour of both NF and NS enabled by paracrine mechanisms. Conditioned media was collected from cultured primary fibroblasts during a proliferative log phase of growth including: NF, NS, peri-lesional keloid fibroblasts (PKF) and intra-lesional keloid fibroblasts (IKF). Conditioned media was used to grow NF, NS, PKF and IKF cells over 240 hrs. Cellular behavior was monitored through real time cell analysis (RTCA), proliferation rates and migration in a scratch wound assay. Fibrosis-associated marker expression was determined at both protein and gene level. PKF conditioned media treatment of both NF and NS elicited enhanced cell proliferation, spreading and viability as measured in real time over 240 hrs versus control conditioned media. Following PKF and IKF media treatments up to 240 hrs, both NF and NS showed significantly elevated proliferation rates (p<0.03) and migration in a scratch wound assay (p<0.04). Concomitant up-regulation of collagen I, fibronectin, α-SMA, PAI-1, TGF-β and CTGF (p<0.03) protein expression were also observed. Corresponding qRT-PCR analysis supported these findings (P<0.03). In all cases, conditioned media from growing marginal PKF elicited the strongest effects. In conclusion, primary NF and NS cells treated with PKF or IKF conditioned media exhibit enhanced expression of fibrosis-associated molecular markers and increased cellular activity as a result of keloid fibroblast-derived paracrine factors.     

Genetic manipulation, a feasible tool to enhance unique characteristic of Chlorella vulgaris as a feedstock for biodiesel production

Developing a reliable technique to transform unicellular green algae, Chlorella vulgaris, could boost potentials of using microalgae feedstock in variety of applications such as biodiesel production. Volumetric lipid productivity (VLP) is a suitable variable for evaluating potential of algal species. In the present study, the highest VLP level was recorded for C. vulgaris (79.08 mg l^?1 day^?1) followed by 3 other strains studied; C. emersonii, C. protothecoides, and C. salina by 54.41, 45 and 18.22 mg l^?1day^?1, respectively. Having considered the high productivity of C. vulgaris, it was selected for the preliminary transformation experiment through micro-particle bombardment. Plasmid pBI 121, bearing the reporter gene under the control of CaMV 35S promoter and the kanamycin marker gene, was used in cells bombardment. Primary selection was done on a medium supplemented by 50 mg l^?1 kanamycin. After several passages, the survived cells were PCR-tested to confirm the stability of transformation and then were found to exhibit β-glucuronidase (GUS) activity in comparison with the control cells. Southern hybridization of npt II probe with genomic DNA revealed stable integration of the cassette in three different positions in the genome. The whole process was successfully implemented as a pre-step to transform the algal cells by genes involved in lipid production pathway which will be carried out in our future studies.     

Relationship between susceptibility to neonicotinoids and population dynamics of cotton aphid,Aphis gossypii Glover (Hemiptera: Aphididae)

Efficiency of imidacloprid and thiametoxam on population growth parameters of Aphis gossypii Glover (Hemiptera: Aphididae) was assessed using three bioassay methods including; residual, starvation and FAO dip methods. Aphids were assayed under laboratory conditions at 23 ± 2°C, photoperiod of 16:8 (L:D) and 70% relative humidity. Aphids were transferred to sprayed leaves and Petri dishes in residual and starvation methods, respectively. There was no feeding for the aphids in starvation method. In FAO dip method, insects were dipped for 5 s in pesticide solutions and then transferred to fresh leaves. Results revealed that LC₅₀ values calculated with the starvation and residual methods were respectively 15 and 11% more than FAO dip method (for imidacloprid) and 22 and 18% (for thiametoxam). The LC₅₀ value in starvation method was 3% more than the residual method. Calculated LC₅₀ in starvation and residual methods with imidacloprid respectively caused 160 and 34% increase in intrinsic rates of increase (r _m) and net reproductive rate (R ₀) in comparison with FAO dip method. Generation time (T) and doubling time (DT) were respectively 59 and 62% less than those in FAO dip method. In contrast, thiametoxam (LC₅₀ concentration) in starvation and residual method lead to 9 and 67% increase in r _m and R ₀ parameters compared to FAO dip method. However T and DT were respectively 65 and 92% less than mentioned parameters in FAO dip method. There was not any significant difference between life table parameters calculated by residual and starvation bioassay methods.     

Assessment of genetic diversity among and within Carthamus species using sequence-related amplified polymorphism (SRAP) markers

Due to precise evaluation of genetic diversity of Carthamus species, sixty-two genotypes consisting fifty-two from five wild (C. oxyacanthus M. Bieb, C. lanatus L., C. dentatus Vahl, C. boissieri Halácsy, C. glaucus M.B.) and ten from cultivated species (C. tinctorius L.) were selected for evaluation of the genetic diversity in Carthamus species. A total of 238 (81.2 %) polymorphic bands were detected by 12 SRAP primer combinations with an average of 22 bands per combination. Me4-Em1 and Me5-Em2 primer combinations were known as the most informative SRAP markers based on the PIC values (0.34) where they distinguished all studied Carthamus species. Cluster analysis classified all accessions into five main groups among which clusters containing cultivated individuals were distinctly separated from those containing wilds. The most and the least genetic variation based on analysis of molecular variance, were detected within (76.90 %) and among (22.84 %) groups, respectively. The obtained results suggested that C. dentatus, C. glaucus and C. boissieri species may be classified in one section including C. dentatus in one and C. glaucus and C. boissieri in another subsection. The results also revealed high genetic similarity between C. oxyacanthus and C. tinctorius despite their different morphological characteristics.