995 resultados para 190-1176
Resumo:
The baculovirus expression system using the Autographa californica nuclear polyhedrosis virus (AcNPV) has been extensively utilized for high-level expression of cloned foreign genes, driven by the strong viral promoters of polyhedrin (polh) and p10 encoding genes. A parallel system using Bombyx mori nuclear polyhedrosis virus (BmNPV) is much less exploited because the choice and variety of BmNPV-based transfer vectors are limited. Using a transient expression assay, we have demonstrated here that the heterologous promoters of the very late genes polh and p10 from AcNPV function as efficiently in BmN cells as the BmNPV promoters. The location of the cloned foreign gene with respect to the promoter sequences was critical for achieving the highest levels of expression, following the order +35 > +1 > -3 > -8 nucleotides (nt) with respect to the polh or p10 start codons. We have successfully generated recombinant BmNPV harboring AcNPV promoters by homeologous recombination between AcNPV-based transfer vectors and BmNPV genomic DNA. Infection of BmN cell lines with recombinant BmNPV showed a temporal expression pattern, reaching very high levels in 60-72 h post infection. The recombinant BmNPV harboring the firefly luciferase-encoding gene under the control of AcNPV polh or p10 promoters, on infection of the silkworm larvae led to the synthesis of large quantities of luciferase. Such larvae emanated significant luminiscence instantaneously on administration of the substrate luciferin resulting in 'glowing silkworms'. The virus-infected larvae continued to glow for several hours and revealed the most abundant distribution of virus in the fat bodies. In larval expression also, the highest levels were achieved when the reporter gene was located at +35 nt of the polh.
Resumo:
Sob o rótulo da globalização, as ciências humanas e sociais têm sido forçadas a rever seu pensamento para encontrar novas maneiras de falar sobre as situações de mudança ao nosso redor e para reorientar-se conceitualmente em um aparente ‘mundo sem fronteiras’. Este artigo analisa algumas dessas formas, sugerindo que a pesquisa em currículo transnacional como tarefa, como talvez inclusiva de algo para além dos estudos curriculares como subárea, tem preocupações, pontos de entrada e horizontes de promulgação amplos, inconstantes, imprevisíveis, que levantam uma série de questões e considerações éticas que exigem maior compromisso nos espaços em que as fronteiras percebidas forem transgredidas no ato da investigação. Usando os relatórios sobre os resultados do PISA como disparador intelectual, este artigo discute quatro questões que surgem no ato investigativo em currículo transnacional: a comparação como princípio de produção de conhecimento; as estratégias de agrupamento onto-teo-filosóficas e a delimitação da ética; o retorno do sujeito centrado, humanista, racional e as críticas a esse sujeito inspirado no Iluminismo; as questões relativas à causalidade, ou seja, como os processos de atribuição são forjados e que tipos de ‘legitimação via procedimento’ operam na crítica social. Em vez de sugerir uma nova ordem, este artigo busca um questionamento mais profundo dos repetitivos pressupostos ocidentalistas.
Resumo:
This paper describes a mechanism of coupling periodate-oxidized nucleosides to proteins. Each of the dialdehyde groups of a periodate-oxidized nucleoside is shown to couple to lysine residues on different protein molecules through Schiff bases, thereby cross-linking different protein molecules, forming a polymer. This is in contrast to the previous model in which nucleosides were suggested to couple to proteins through a morpholine structure. The cross-linked structure of the nucleoside-antigen, significantly different when compared to the native protein, may affect the specificity and the efficiency of antibody production.
Resumo:
Conventional thinkin g holds that increased energy consumption is a prerequisite for economic and social development. This belief, together With the prospect of dwindling global petroleum supplies and the high costs of expanding energy supply generally, lead many to believe that it is not feasible to improve living standards substantially in the developing countries. But by shifting to high-quality energy carriers and by exploiting cost-effective opportunities for more efficient energy use, it would be possible to satisfy basic human needs and to provide considerable further improvements in living standards without significantly increasing per-capita energy use above the present level.
Resumo:
Controversy exists in the published literature as to the effect of silicon content and pressure on the dry sliding wear of Al---Si alloys. The present paper attempts to clarify the question by reporting a statistical analysis of data obtained from factorially designed experiments conducted on a pinon-disc machine in the pressure range 0.105–1.733 MPa and speed range 0.19–0.94 m s−1. Under these conditions it was found that, in the range 4–24 wt.% Si, wear of binary unmodified alloys does not significantly differ between the alloys. However, it is significantly less than that corresponding to an alloy containing no silicon. The effect of pressure on wear rate was found to be linear and monotonie and, over the narrow range of speeds used, the wear rate was found to be unaffected by speed. The coefficient of friction was found to be insensitive to variations in silicon content, pressure and speed.
Resumo:
Estimates of microbial crude protein (MCP) production by ruminants, using a method based on the excretion of purine derivatives in urine, require an estimate of the excretion of endogenous purine derivatives (PD) by the animal. Current methods allocate a single value to all cattle. An experiment was carried out to compare the endogenous PD excretion in Bos taurus and high-content B. indicus (hereafter, B. indicus) cattle. Five Holstein–Friesian (B. taurus) and 5 Brahman (> 75% B. indicus) steers (mean liveweight 326 ± 3.0 kg) were used in a fasting study. Steers were fed a low-quality buffel grass (Cenchrus ciliaris; 59.4 g crude protein/kg dry matter) hay at estimated maintenance requirements for 19 days, after which hay intake was incrementally reduced for 2 days and the steers were fasted for 7 days. The excretion of PD in urine was measured daily for the last 6 days of the fasting period and the mean represented the daily endogenous PD excretion. Excretion of endogenous PD in the urine of B. indicus steers was less than half that of the B. taurus steers (190 µmol/kg W0.75.day v. 414 µmol/kg W0.75.day; combined s.e. 37.2 µmol/kg W0.75.day; P < 0.001). It was concluded that the use of a single value for endogenous PD excretion is inappropriate for use in MCP estimations and that subspecies-specific values would improve precision.
Effect of Temperature Variation on Sister Chromatid Exchange Frequency in Cultured Human Lymphocytes
Resumo:
The effect of temperature variation on sister chromatid exchange (SCE) frequencies in human lymphocytes was studied. An increase as well as decrease in incubation temperature of cells leads to a higher frequency of sister chromatid exchanges than in cultures grown at 37°C. In addition, it was observed that mitotic: index and cell cycle duration were affected by low temperature.
Resumo:
1. The European red fox Vulpes vulpes represents a continuing threat to both livestock and native vertebrates in Australia, and is commonly managed by setting ground-level baits impregnated with 1080 (sodium fluoroacetate) poison. However, the long-term effectiveness of such control campaigns is likely to be limited due to the ability of foxes to disperse over considerable distances and to swiftly recolonize areas from where they had been removed. 2. To investigate the effectiveness of fox baiting in a production landscape, we assessed the potential for foxes to reinvade baited farm property areas within the jurisdiction of the Molong Rural Lands Protection Board (RLPB), an area of 815 000 ha on the central tablelands of New South Wales, Australia. The spatial distribution and timing of fox baiting campaigns between 1998 and 2002 was estimated from RLPB records and mapped using Geographical Information System software. The effectiveness of the control campaign was assessed on the basis of the likely immigration of foxes from non-baited farms using immigration distances calculated from published relationships between dispersal distance and home range size. 3. Few landholders undertook baiting campaigns in any given year, and the area baited was always so small that no baited property would have been sufficiently far from an unbaited property to have been immune from immigrating individuals. It is likely, therefore, that immigration onto farms negated any long-term effects of baiting operations. This study highlights some of the key deficiencies in current baiting practices in south-eastern Australia and suggests that pest management programmes should be monitored using such methods to ensure they achieve their goals.
Resumo:
Internal browning disorders, including brown fleck (BF), in potato (Solanum tuberosum) tubers greatly reduce tuber quality, but the causes are not well understood. This is due, in part, to the highly variable data provided by visual value-based rating systems. A digital imaging technique was developed to quantify accurately the incidence of internal browning in potato tubers. Images of tuber sections were scanned using a flatbed scanner and digitally enhanced to highlight tuber BF lesions, and the area of affected tissue calculated using pixel quantification software. Digital imaging allowed for the determination of previously unused indices of the incidence and severity of internal browning in potato tubers. Statistical analysis of the comparison between digitally derived and visual-rating BF data from a glasshouse experiment showed that digital data greatly improved the delineation of treatment effects. The F-test probability was further improved through square root or logarithmic data transformations of the digital data, but not of the visual-rating data. Data from a field experiment showed that the area of tuber affected by BF and the number of small BF lesions increased with time and with increase in tuber size. The results from this study indicate that digital imaging of internal browning disorders of potato tubers holds much promise in determining their causes that heretofore have proved elusive.
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A 300-strong Angus-Brahman cattle herd near Springsure, central Queensland, was being fed Acacia shirleyi (lancewood) browse during drought and crossed a 5-hectare, previously burnt area with an almost pure growth of Dysphania glomulifera subspecies glomulifera (red crumbweed) on their way to drinking water. Forty cows died of cyanide poisoning over 2 days before further access to the plant was prevented. A digital image of a plant specimen made on a flat-bed scanner and transmitted by email was used to identify D glomulifera. Specific advice on the plant's poisonous properties and management of the case was then provided by email within 2 hours of an initial telephone call by the field veterinarian to the laboratory some 600 km away. The conventional method using physical transport of a pressed dried plant specimen to confirm the identification took 5 days. D glomulifera was identified in the rumen of one of two cows necropsied. The cyanogenic potential of D glomulifera measured 4 days after collection from the site of cattle deaths was 18,600 mg HCN/kg in dry matter. The lethal dose of D glomulifera for a 420 kg cow was estimated as 150 to 190 g wet weight. The plant also contained 4.8% KNO3 equivalent in dry matter, but nitrate-nitrite poisoning was not involved in the deaths.
Resumo:
An enzyme catalysing the synthesis of sym-homospermidine from putrescine and NAD+ with concomitant liberation of NH3 was purified 100-fold from Lathyrus sativus (grass pea) seedlings by affinity chromatography on Blue Sepharose. This thiol enzyme had an apparent mol.wt. of 75000 and exhibited Michelis-Menten kinetics with Km 3.0mM for putrescine. The same enzyme activity could also be demonstrated in the crude extracts of sandal (Santalum album) leaves, but with a specific activity 15-fold greater than that in L. sativus seedlings.
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Usage of new smart materials in retrofitting of structures has become popular within last decade. Carbon fiber reinforced polymer (CFRP) has been widely used in retrofitting and strengthening of concrete structures and its usage in metallic structures is still in the developing stage. The variation of mechanical properties of CFRP and the consequent effects on strengthening and retrofitting CFRP systems are yet to be investigated under different loading and environmental conditions. This paper presents the results of CFRP strengthened and retrofitted corroded steel plate double strap joints under tension. An accelerated corrosion cell has been developed to accelerate the corrosion of the steel samples and CFRP strengthened samples. The results show a direct comparison of bond characteristics of CFRP strengthened and retrofitted steel double strap joints.
Resumo:
Resistance against synthetic pyrethroid (SP) products for the control of cattle ticks in Australia was detected in the field in 1984, within a very short time of commercial introduction. We have identified a mutation in the domain II S4-5 linker of the para-sodium channel that is associated with resistance to SPs in the cattle tick Rhipicephalus (Boophilus) microplus from Australia. The cytosine to adenine mutation at position 190 in the R. microplus sequence AF134216, results in an amino acid substitution from leucine in the susceptible strain to isoleucine in the resistant strain. A similar mutation has been shown to confer SP resistance in the whitefly, Bemisia tabaci, but has not been described previously in ticks. A diagnostic quantitative PCR assay has been developed using allele-specific Taqman® minor groove-binding (MGB) probes. Using the assay to screen field and laboratory populations of ticks showed that homozygote allelic frequencies correlated highly with the survival percentage at the discriminating concentration of cypermethrin.
Resumo:
We discovered a significant bias for wild dog scent station spoor (scats and scratches) to be positioned on the north-easterly side of roads and intersections. Counts of this spoor, 50 metres in each direction of north-south and east-west intersections were made in state forests near Roma in southwest Queensland, Cecil Plains on the Darling Downs and Maryborough on the coast during mating season in April/May 2007. While 51% of 190 and 83% of 120 scent station spoor were located on the north-eastern sector of the intersections at Cecil Plains and Roma respectively, spoor were more evenly distributed across all four sectors at Maryborough (n=47).
Resumo:
Whole cells, homogenates and mitochondrial obtained from the livers of albino rats which were starved for 6 days or more showed a 50% decrease in oxidative activity. The decrease could be corrected by the addition of cytochrome c in vitro. The phosphorylative activity of mitochondria remained unaffected. The decrease in oxidative rate was not observed when starving animals were given the anti-hypercholesterolaemic drug clofibrate. The total cellular concentration of cytochrome c was not affected by starvation. However, the concentration of the pigment in hepatic mitochondria isolated from starving animals was less than half that in normal mitochondria. Clofibrate-treated animals did not show a decreased concentration of cytochrome c in hepatic mitochondria. Mitochondria isolated from starving animals, though deficient in cytochrome c, did not show any decrease in succinate dehydrogenase activity or in the rate of substrate-dependent reduction of potassium ferricyanide or attendant phosphorylation. In coupled mitochondria, ferricyanide may not accept electrons from the cytochrome c in the respiratory chain. Starvation decreases the concentration of high-affinity binding sites for cytochrome c on the mitochondrial membrane. The dissociation constant increases in magnitude.