982 resultados para DNA CONTENT
Resumo:
Genetic diversity in Cassia brewsteri (F. Muell.) F. Muell. ex Benth. was assessed with Randomly Amplified DNA Fingerprints (RAFs). Thirty accessions of C. brewsteri collected from throughout its natural distribution were analysed with three random decamer primers, along with three accessions of C. tomentella (Benth.) Domin and a single accession of each of C. queenslandica C. T. White and C. marksiana (F. M. Bailey) Domin. The three primers yielded a reproducible amplification profile of 265 scorable polymorphic fragments for the 35 accessions. These molecular markers were used to calculate Nei and Li similarity coefficients between each pair of individuals. A matrix of dissimilarity of each pair of individuals was examined by multidimensional scaling (MDS). The analysis supports the division of C. brewsteri into two subspecies and the suggestion that intergradation of C. brewsteri and C. tomentella can occur where the distributions of these species meet.
Resumo:
The specific status of the head and body lice of humans has been debated for more than 200 yr. To clarify the specific status of head and body lice, we sequenced 524 base pairs (bp) of the cytochrome oxidase I (COI) gene of 28 head and 28 body lice from nine countries. Ten haplotypes that differed by 1-5 bp at II nucleotide positions were identified. A phylogeny of these sequences indicates that these head and body lice are not from reciprocally monophyletic lineages. Indeed, head and body lice share three of the 10 haplotypes we found. F-ST values and exact tests of haplotype frequencies showed significant differences between head and body lice. However, the same tests also showed significant differences among lice from different countries. Indeed, more of the variation in haplotype frequencies was explained by differences among lice from different countries than by differences between head and body lice. Our results indicate the following: (1) bead and body lice do not represent reciprocally monophyletic lineages and are conspecific; (2) gene flow among populations of lice from different countries is limited; and (3) frequencies of COI haplotypes can be used to study maternal gene flow among populations of head and body lice and thus transmission of lice among their human hosts.
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ITS2 sequences are used extensively in molecular taxonomy and population genetics of arthropods and other animals yet little is known about the molecular evolution of ITS2. We studied the secondary structure of ITS2 in species from each of the six main lineages of hard ticks (family Ixodidae). The ITS2 of these ticks varied in length from 679 bp in Ixodes scapularis to 1547 bp in Aponomma concolor. Nucleotide content varied also: the ITS2 of ticks from the Prostriata lineage (Ixodes spp.) had 46-49% GC whereas ITS2 sequences of ticks from the Metastriata lineage (all other hard ticks) had 61-62% GC. Despite variation in nucleotide sequence, the secondary structure of the ITS2 of all of these ticks apparently has five domains. Stems 1, 3, 4 and 5 of this secondary structure were obvious in all of the species studied. However, stem 2 was not always obvious despite the fact that it is flanked by highly conserved sequence motifs in the adjacent stems, stems 1 and 3. The ITS2 of hard ticks has apparently evolved mostly by increases and decreases in length of the nucleotide sequences, which caused increases, and decreases in the length of stems of the secondary structure. This is most obvious when stems of the secondary structures of the Prostriata (Ixodes spp.) are compared to those of the Metastriata (all other hard ticks). Increases in the size of the ITS2 may have been caused by replication slippage which generated large repeats, like those seen in Haemaphysalis humerosa and species from the Rhipicepalinae lineage, and the small repeats found in species from the other lineages of ticks.
Resumo:
Sequence variation in the internal transcribed spacer (ITS-1) ribosomal DNA subunit was examined for sorghum midge obtained from introduced and native hosts in south-eastern and central Queensland. No variation was observed relative to host plant or geographical distance for midges collected from two introduced hosts, grain sorghum (Sorghum bicolor ) and Johnson grass (S. halepense ); however, sequence differences were observed between midges from introduced and native hosts and among midges from a single native host, slender bluegrass (Dichanthium affine ). No evidence was observed of introduced midges on native hosts, or vice versa. These results agree with previously hypothesised host distributions for native and introduced midges in Australia, and expand the sample of introduced hosts to include Johnson grass. They suggest that Stenodiplosis sorghicola , the principal midge infesting grain sorghum, is also the most common species on Johnson grass. This confirms that Johnson grass plays a role in the population dynamics of S. sorghicola and suggests that midges originating from Johnson grass may influence levels of infestation in grain sorghum.
Resumo:
In order to study the effect of arsenic on DNA damage, Sprague-Dawley rats were dosed with sodium arsenite (10 mg/kg) with or without 800 mug of benzo(a)pyrene (BP) by intramammilary injection. The animals were sacrificed on day 1, 3, 5, 10 and 27 and the mammary gland tissues were collected for DNA adduct measurement using a P-32 post-labeling assay. Animals dosed with arsenic alone did not show any DNA adducts. DNA adduct levels in rats dosed with BP alone reached a maximum level by day 5, reducing to 13% of this level by day 27. Adduct levels in rats dosed with arsenic and BP also reached a maximum by day 5 but only 80% of the level observed in the BP group. However, 84% of this amount still remained by day 27. The First Nucleotide Change (FNC) technique was used for the screening of 115 samples of various tissues from mice that had been chronically exposed to sodium arsenate for over 2 years revealed that inorganic arsenic did not attack the two putative hotspots (codons 131 and 154) of the hOGG1 gene. These results support the hypothesis that arsenic exerts its biological activity through DNA repair inhibition. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.
Resumo:
The use of electrotransfer for DNA delivery to prokaryotic cells, and eukaryotic cells in vitro, has been well known and widely used for many years. However, it is only recently that electric fields have been used to enhance DNA transfer to animal cells in vivo, and this is known as DNA electrotransfer or in vivo DNA electroporation. Some of the advantages of this method of somatic cell gene transfer are that it is a simple method that can be used to transfer almost any DNA construct to animal cells and tissues in vivo; multiple constructs can be co-transfected; it is equally applicable to dividing and nondividing cells; the DNA of interest does not need to be subeloned into a specific viral transfer vector and there is no need for the production of high titre viral stocks; and, as no viral genes are expressed there is less chance of an adverse immunologic reaction to vector sequences. The ease with which efficient in vivo gene transfer can be achieved with in vivo DNA electrotransfer is now allowing genetic analysis to be applied to a number of classic animal model systems where transgenic and embryonic stem cell techniques are not well developed, but for which a wealth of detailed descriptive embryological information is available, or surgical manipulation is much more feasible. As well as exciting applications in developmental biology, in vivo DNA electrotransfer is also being used to transfer genes to skeletal muscle and drive expression of therapeutically active proteins, and to examine exogenous gene and protein function in normal adult cells situated within the complex environment of a tissue and organ system in vivo. Thus, in effect providing the in vivo equivalent of the in vitro transient transfection assay. As the widespread use of in vivo electroporation has really only just begun, it is likely that the future will hold many more applications for this technology in basic research, biotechnology and clinical research areas.
Resumo:
This present study was undertaken to assess potential effects of cadmium on CYP4A11 apoprotein in human liver and kidney as detected by Western blotting using a highly specific anti-peptide antibody. Liver and kidney cortex samples were autopsy specimens of 37 individuals (26 mates and I I females) whose ages ranged from 3 to 89 years. All were Caucasians who had not been exposed to cadmium in the workplace. Reduced CYP4A11 apoprotein levels were found in chronic hepatitis samples and in liver samples showing fatty changes. In contrast, increased CYP4A11 apoprotein levels were found in liver samples having higher cadmium content compared to the lower cadmium content samples. Increased CYP4A11 levels were also found in liver samples from female donors, compared to male donors; the difference being attributable to higher female liver cadmium burden. In distinction to liver, lowered CYP4A11 levels were seen in the kidney cortex samples which have high cadmium content, It is proposed here that the difference between the absolute cadmium burden of the liver and kidney samples may be responsible for the different patterns of expression of CYP4A11 in these two tissues. Further, since cadmium exposure may be associated with derangement in blood pressure control, it is interesting to note the possible relationship between altered CYP4A11-dependent production of arachidonic acid hydroxy and epoxy metabolites in kidney cortex and altered control of blood pressure. Our findings provide a possible link between these observations. (C) 2002 Elsevier Science Inc. All rights reserved.
Resumo:
Following treatment with bracken fern (Pteridium aquilinum) extract and bracken spores a number of DNA adducts were detected by P-32-postlabeling. Three of these adducts have been described previously (Povey et al., Br. J. Cancer (1996) 74, 1342-1348) and in this study, using a slightly different protocol, four new adducts, with higher chromatographic mobility, were detected at levels ranging from 50 to 230% of those previously described, When DNA was treated in vitro with activated ptaquiloside (APT) and analysed by butanol extraction or nuclease P1 treatment, only one adduct was detected by P-32-postlabeling, This adduct was not present in the DNA from mice treated with bracken fern or spores, suggesting either that bracken contains genotoxins other than ptaquiloside or that the metabolism of ptaquiloside produces genotoxins not reflected by activated ptaquiloside. However, as the ATP-derived adduct has been detected previously in ileal DNA of bracken-fed calves, species-specific differences in the metabolism of bracken genotoxins may exist, thereby leading to differences in their biological outcomes. (C) 2001 Academic Press.
Resumo:
The aim of this study was to review the published literature values for the selenium content of Australian foods. A secondary aim was to compare the results for Australian foods with food composition data from international sources to investigate the extent of geographical variation. Published food composition data sources for the selenium content in Australian foods were identified and assessed for data quality using established criteria. The selenium content is available for 148 individual food items. The highest values found are for fish (12.0-63.2 mug/100 g), meats (4.75-37.9 mug/100 g) and eggs (9.00-41.4 mug/100 g), followed by cereals (1.00-20.3 mug/100 g). Moderate levels are seen in dairy products (2.00-7.89 mug/100 g) while most fruits and vegetables have low levels (trace-3.27 mug/100 g). High selenium foods show the greatest level of geographical variation, with foods from the United States generally having higher selenium levels than Australian foods and foods from the United Kingdom and New Zealand having lower levels. This is the first attempt to review the available literature for selenium composition of Australian foods. These data serve as an interim measure for the assessment of selenium intake for use in epidemiological studies of diet-disease relationships. (C) 2002 Published by Elsevier Science Ltd.
Resumo:
Tamoxifen is a major drug used for adjuvant chemotherapy of breast cancer; however, its use has been associated with a small but significant increase in risk of endometrial cancer. In rats, tamoxifen is a hepatocarcinogen, and DNA adducts have been observed in both rat and human tissues. Tamoxifen has been shown previously to be metabolized to reactive products that have the potential to form protein and DNA adducts. Previous studies have suggested a role for P450 3A4 in protein adduct formation in human liver microsomes, via a catechol intermediate; however, no clear correlation was seen between P450 3A4 content of human liver microsomes and adduct formation. In the present study, we investigated the P450 forms responsible for covalent drug-protein adduct formation and the possibility that covalent adduct formation might occur via alternative pathways to catechol formation. Recombinant P450 3A4 catalyzed adduct formation, and this correlated with the level of uncoupling in the P450 incubation, consistent with a role of reactive oxygen species in potentiating adduct formation after enzymatic formation of the catechol metabolite. Whereas P450s 1AI, 2D6, and 3A5 generated catechol metabolite, no covalent adduct formation was observed with these forms. By contrast, P450 2136, 2C19, and rat liver microsomes catalyzed drug-protein adduct formation but not catechol formation. Drug protein adducts formed specifically with P450 3A4 in incubations using membranes isolated from bacteria expressing P450 3A4 and reductase, as well as in reconstitutions of purified 3A4, suggesting that the electrophilic species reacted preferentially with the P450 enzymes concerned.
Resumo:
During bacterial infections, the balance between resolution of infection and development of sepsis is dependent upon the macrophage response to bacterial products. We show that priming of murine bone marrow-derived macrophages (BMMs) with CSF-1 differentially regulates the response to two such stimuli, LPS and immunostimulatory (CpG) DNA. CSF-1 pretreatment enhanced IL-6, IL-12, and TNF-alpha production in response to LPS but suppressed the same response to CpG DNA. CSF-1 also regulated cytokine gene expression in response to CpG DNA and LPS; CpG DNA-induced IL-12 p40, IL-12 p35, and TNF-alpha mRNAs were all suppressed by CSF-1 pretreatment. CSF-1 pretreatment enhanced LPS-induced IL-12 p40 mRNA but not TNF-alpha and IL-12 p35 mRNAs, suggesting that part of the priming effect is posttranscriptional. CSF-1 pretreatment also suppressed CpG DNA-induced nuclear translocation of NF-kappaB and phosphorylation of the mitogen-activated protein kinases p38 and extracellular signal-related kinases-1/2 in BMMs, indicating that early events in CpG DNA signaling were regulated by CSF-1. Expression of Toll-like receptor (TLR)9, which is necessary for responses to CpG DNA, was markedly suppressed by CSF-1 in both BMMs and thioglycolate-elicited peritoneal macrophages. CSF-1 also down-regulated expression of TLR1, TLR2, and TLR6, but not the LPS receptor, TLR4, or TLR5. Hence, CSF-1 may regulate host responses to pathogens through modulation of TLR expression. Furthermore, these results suggest that CSF-1 and CSF-1R antagonists may enhance the efficacy of CpG DNA in vivo.
Resumo:
A radiation of five species of giant tortoises (Cylindraspis ) existed in the southwest Indian Ocean, on the Mascarene islands, and another (of Aldabrachelys ) has been postulated on small islands north of Madagascar, from where at least eight nominal species have been named and up to five have been recently recognized. Of 37 specimens of Madagascan and small-island Aldabrachelys investigated by us, 23 yielded significant portions of a 428-base-pair (bp) fragment of mitochondrial (cytochrome b and tRNA-Glu), including type material of seven nominal species (A. arnoldi, A. dussumieri, A. hololissa, A. daudinii, A. sumierei, A. ponderosa and A. gouffei ). These and nearly all the remaining specimens, including 15 additional captive individuals sequenced previously, show little variation. Thirty-three exhibit no differences and the remainder diverge by only 1-4 bp (0.23-0.93%). This contrasts with more widely accepted tortoise species which show much greater inter- and intraspecific differences. The non-Madagascan material examined may therefore only represent a single species and all specimens may come from Aldabra where the common haplotype is known to occur. The present study provides no evidence against the Madagascan origin for Aldabra tortoises suggested by a previous molecular phylogenetic analysis, the direction of marine currents and phylogeography of other reptiles in the area. Ancient mitochondrial DNA from the extinct subfossil A. grandidieri of Madagascar differs at 25 sites (5.8%) from all other Aldabrachelys samples examined here.
Resumo:
Quantification of calcium in the cuticle of the fly larva Exeretonevra angustifrons was undertaken at the micron scale using wavelength dispersive X-ray microanalysis, analytical standards, and a full matrix correction. Calcium and phosphorus were found to be present in the exoskeleton in a ratio that indicates amorphous calcium phosphate. This was confirmed through electron diffraction of the calcium-containing tissue. Due to the pragmatic difficulties of measuring light elements, it is not uncommon in the field of entomology to neglect the use of matrix corrections when performing microanalysis of bulk insect specimens. To determine, firstly, whether such a strategy affects the outcome and secondly, which matrix correction is preferable, phi-rho (z) and ZAF matrix corrections were contrasted with each other and without matrix correction. The best estimate of the mineral phase was found to be given by using the phi-rho (z) correction. When no correction was made, the ratio of Ca to P fell outside the range for amorphous calcium phosphate, possibly leading to flawed interpretation of the mineral form when used on its own.