Using Trichogramma Westwood (Hymenoptera: Trichogrammatidae) for insect pest biological control in cotton crops: an Australian perspective.

Trichogramma Westwood egg parasitoids alone generally fail to suppress heliothine pests when released in established cotton-growing regions. Factors hindering their success include indiscriminate use of detrimental insecticides, compensation for minimal pest larval hatch due to their activity via reduced larval cannibalism or mortality in general, singly laid heliothine eggs avoiding detection and asynchronous development benefiting host over parasitoid. Yet, despite these limitations, relatively large Trichogramma pretiosum Riley populations pervade and effectively suppress Helicoverpa (Hardwick) pests in Australian Bt (Bacillus thuringiensis Berliner)-transgenic cotton, Gossypium hirsutum L., crops, especially in the Ord River Irrigation Area (ORIA) of tropical northern Australia, where their impact on the potentially resistant pest species, Helicoverpa armigera (Hubner), is considered integral to the local insecticide resistance management (IRM) strategy for continued, sustainable Bt-transgenic cotton production. When devoid of conventional insecticides, relatively warm and stable conditions of the early dry season in winter grown ORIA Bt-transgenic cotton crops are conducive to Trichogramma proliferation and biological control appears effective. Further, there is considerable scope to improve Trichogramma's biological control potential, in both the ORIA and established cotton-growing regions, via habitat manipulation. It is proposed that Trichogramma may prove equally effective in developing agricultural regions of monsoonal northern Australia, and that environmental constraints on Trichogramma survival, and those of other natural enemies, require due consideration prior to their successful application in biological control programs.

Target Cell Topography and Cytoskeletal Reorganization in Natural Killer Cell Activity

The immune system has to recognize and destroy abnormal or infected cells to maintain homeostasis. Natural killer (NK) cells directly recognize and kill transformed or virus-infected cells without prior sensitization. We have studied both virus-infected and tumor cells in order to identify the target structures involved in triggering NK activity. Mouse/human cell hybrids containing various human chromosomes were used as targets. The human chromosome responsible for activating NK cell killing was identified to chromosome number 6. The results suggest that activated NK cells recognize ligands that are encoded on human chromosome 6. We showed that the ligand on the target cell side was intercellular adhesion molecule 2 (ICAM-2). There was no difference in the level of expression of ICAM-2, however, but a drastic difference was seen in the distribution of the molecule: ICAM-2 was evenly distributed on the surface of the NK-resistant cells, but almost totally redistributed to the tip of uropods, bud-like extensions, which were absent from the parental cells. Interestingly, the gene coding for cytoskeletal linker protein ezrin has been localized to human chromosome 6, and there was a colocalization of ezrin and ICAM-2 in the uropods. Furthermore, the transfected human ezrin into NK cell-resistant cells induced uropod formation, ICAM-2 and ezrin redistribution to newly formed uropods, and sensitized target cells to NK cell killing. These data reveal a novel form of NK cell recognition: target structures are already present on normal cells; they become detectable only after abnormal redistribution into hot spots on the target cell membrane. NK cells are central players in the defence against virus infections. They inhibit the spread of infection, allowing time for specific immune responses to develop. The virus-proteins that directly activate human NK cell killing are largely unknown. We studied the sensitivity of virus-specific early proteins of Semliki Forest virus (SFV) to NK killing. The viral non-structural proteins (nsP1-4) translated early in the virus cycle were transfected in NK-resistant cells. Viral early gene nsP1 alone efficiently sensitized target cells to NK activity, and the tight membrane association of nsP1 seems to be critical in the triggering of NK killing. NsP1 protein colocalized with (redistributed) ezrin in filopodia-like structures to which the NK cells were bound. The results suggest that also in viral infections NK cells react to rapid changes in membrane topography. Based on the results of this thesis, a new model of target cell recognition of NK cells can be suggested: reorganization of the cytoskeleton induces alterations in cell surface topography, and this new pattern of surface molecules is recognized as "altered-self".

A study of a retention of antimicrobial activity by plasma polymerized terpinen-4-ol thin films

Terpinen-4-ol is the main constituent of Melaleuca alternifolia essential oil known for its biocidal and anti-inflammatory properties. The possibility of fabricating polymer thin films from terpinen-4-ol using radio frequency (RF) plasma polymerisation for the prevention of the growth of Pseudomonas aeruginosa was investigated, and the properties of the resultant films compared against their biologically active precursor. Films fabricated at 10 W prevented bacterial attachment and EPS secretion, whilst polyterpenol films deposited at 25 W demonstrated no biocidal activity against the pathogen.

Engaging in videogame play: An activity-centric analysis of the player experience

This paper focuses on examining play activities in people's favourite videogame experience. Through interviews with 30 videogame players we discovered which types of play activities are most appealing. Our research identifies the level of appeal of a wide range of game play activities. We have established that high levels of engagement for many participants is grounded in play as power and play as strategy, with play as fantasy adding to the experience. Through our study we established that conflict-based activities hold strong appeal. We subsequently investigated the context in which players talked about their experience of conflict within game. By using activities as a categorisation of gameplay we have been able to capture the play experience across a range of games and a range of gaming contexts. By examining players' individual experience we begin to understand why conflict in videogames appears to be a popular choice of activities.

Possible involvement of a calcium-stimulated ATP-hydrolyzing activity associated with mycobacteriophage I3 in the DNA injection process.

Ca2+ ions are necessary for the successful propagation of mycobacteriophage I3. An assay for the phage DNA release in the presence of an isolated cell wall preparation from the host was established, and in this system Ca2+ ions also stimulated the release of DNA. The inhibition of phage DNA injection caused by Tween 80 (polyoxyethylene sorbitan monooleate), a nonionic detergent routinely used in mycobacterial cultures, was reversed by Ca2+. The presence of a phage-associated ATP-hydrolyzing activity was demonstrated. This enzyme was stimulated by Ca2+ ions and inhibited by Tween 80. From this and the behavior of the two agents at the level of DNA injection, as well as the fact that phage I3 has a contractile tail structure, we conclude that the phage-associated ATPase is involved in the DNA injection process.

Studies on follicular atresia: role of tropic hormone and steroids in regulating cathepsin-D activity of preantral follicles of the immature rat

The ovary of the immature female rat is comprised of primary and medium-sized preantral follicles. Upon stimulation with FSH or PMSG, the cathepsin-D activity, a representative lysosomal enzyme of granulosa cells, is reduced by 50% (P < 0.01). 17β-Estradiol at the doses tried was unable to mimic this effect. Blockade of steroidogenesis with cyanoketone also had no effect on the cathepsin-D activity of isolated granulosa cells. Dihydrotestosterone (DHT), however, at a dose of 1 mg/rat was able to inhibit PMSG's tropic action. It brought about an increase in cathepsin-D activity and reduction in steroidogenic activity of isolated granulosa cells. The atretogenic activity of DHT could be relieved by supplementation with exogenous FSH. DHT was observed to significantly reduce (P < 0.01) endogenous FSH and LH levels within 12–18 h of its injection suggesting that its atretic effect was due to its action at the pituitary rather than the gonad. In addition to the above the ability of 15 IU of PMSG to reduce cathepsin-D activity of granulosa cells was also significantly reduced (P < 0.01) if endogenous FSH was neutralized by a specific FSH antiserum. The present study suggests that as far as small and medium-sized primary and preantral follicles are concerned, FSH lack is the essential signal for onset of atresia.

Fluorescent alamethicin fragments A study of membrane activity and aqueous phase aggregation

The linear polypeptide antibiotic alamethicin is known to form channels in artificial lipid membranes. Synthetic 13- and 17-residue alamethicin fragments, labelled with a fluorescent dansyl group at the N-terminus, have been shown to translocate divalent cations across phospholipid membranes and to uncouple oxidative phosphorylation in rat liver mitochondria, in a manner analogous to the parent peptides. From studies of the aqueous phase aggregation behavior of the peptides, as well as their interaction with rat liver mitochondria, it is concluded that the interaction of the peptides with membranes is a complex process, probably involving both aqueous and membrane phase aggregation.

The cost-effectiveness of the MobileMums intervention to increase physical activity among mothers with young children: A Markov model informed by a randomised controlled trial

Objectives: To determine the cost-effectiveness of the MobileMums intervention. MobileMums is a 12-week programme which assists mothers with young children to be more physically active, primarily through the use of personalised SMS text-messages. Design: A cost-effectiveness analysis using a Markov model to estimate and compare the costs and consequences of MobileMums and usual care. Setting: This study considers the cost-effectiveness of MobileMums in Queensland, Australia. Participants: A hypothetical cohort of over 36 000 women with a child under 1 year old is considered. These women are expected to be eligible and willing to participate in the intervention in Queensland, Australia. Data sources: The model was informed by the effectiveness results from a 9-month two-arm community-based randomised controlled trial undertaken in 2011 and registered retrospectively with the Australian Clinical Trials Registry (ACTRN12611000481976). Baseline characteristics for the model cohort, treatment effects and resource utilisation were all informed by this trial. Main outcome measures: The incremental cost per quality-adjusted life year (QALY) of MobileMums compared with usual care. Results: The intervention is estimated to lead to an increase of 131 QALYs for an additional cost to the health system of 1.1 million Australian dollars (AUD). The expected incremental cost-effectiveness ratio for MobileMums is 8608 AUD per QALY gained. MobileMums has a 98% probability of being cost-effective at a cost-effectiveness threshold of 64 000 AUD. Varying modelling assumptions has little effect on this result. Conclusions: At a cost-effectiveness threshold of 64 000 AUD, MobileMums would likely be a cost-effective use of healthcare resources in Queensland, Australia. Trial registration number: Australian Clinical Trials Registry; ACTRN12611000481976.

Theoretical studies on Beta-lactam antibiotics VI: Conformational analysis and structure-activity relationships of penicillin sulfoxides and cephalosporins

Conformational energy calculations were carried out on penicillin α-and Β-sulfoxides and δ2- and δ3-cephalosporins, in order to identify the structural features governing their biological activity. Results on penicillin Β-sulfoxide indicated that in its favoured conformation, the orientation of the aminoacyl group was different from the one required for biological activity. Penicillin α sulfoxide, like penicillin sulfide, favoured two conformations of nearly equal energies, but separated by a much higher energy barrier. The reduced activity of the sulfoxides despite the nonplanarity of their lactam peptide indicated that the orientations of the aminoacyl and carboxyl groups might also govern biological activity. δ3-cephalosporins favoured two conformations of nearly equal energies, whereas δ2-cephalosporins favoured only one conformation. The lactam peptide was moderately nonplanÄr in the former, but nearly planar in the latter. The differences in the.preferred orientations of the carboxyl group between penicillins and cephalosporins were correlated with the resistance of cephalosporins to penicillinases.

Isolation and Culture of a Thermophilic Fungus, Melanocarpus albomyces, and Factors Influencing the Production and Activity of Xylanase

Summary: An uncommon thermophilic fungus, Melanocarpus albomyces, was isolated from soil and compost by incubating samples in a glucose/sorbose/asparagine liquid medium, followed by enrichment culture in medium containing sugarcane bagasse as carbon source. The culture filtrate protein of the fungus grown in the presence of bagasse or xylose hydrolysed xylan and some other polysaccharides but cellulose was not hydrolysed. High extracellular xylanase (EC 3.2.1.8) activity was produced by cultures grown on xylose or hemicellulosic materials. The enzyme was induced in glucose-grown washed mycelia in response to addition of xylose or xylan but not by alkyl or aryl β-D-xylosides. Cultures produced higher enzyme yields in shaken flasks than in a fermenter. Gel-filtration chromatography of culture filtrate protein showed the presence of two isoenzymes of xylanase, whose relative proportions varied with the carbon source used for growth. The extent of hydrolysis of heteroxylans or the hemicellulosic fraction of bagasse by culture filtrate protein preparations was greater when the cultures had been grown on bagasse rather than xylose as the inducing substrate. The activity of xylanase preparations was increased when an exogenous β-glucosidase was added.

Glycogen debranching enzyme activity in the muscles of meat producing animals

Muscle glycogen exists in two forms: low molecular weight pro-glycogen and high molecular weight macro-glycogen. The degradation of glycogen to glucose 1 phosphate and free glucose is catalysed by glycogen phosphorylase together with glycogen debranching enzyme (GDE). The process in which glycogen is broken down via anaerobic pathways to lactate, results in the acidification of the muscles and has a great influence on meat quality. Thus, the overall aim of this thesis was to characterise the post mortem action of GDE in muscles of meat production animals (pigs, cattle and chickens). Interest was focused on the differences in GDE activity between fast twitch glycolytic muscles and slow twitch oxidative muscles. The effects of pH, temperature, RN genotype (PRKAG3 gene), and of time post mortem on GDE activity were also investigated. This thesis showed that there are differences in GDE activity between animal species and between different muscles of an animal. It was shown that in pigs and cattle, higher GDE activity and phosphorylase activity exists in the fast twitch glycolytic muscles than in slow twitch oxidative muscles of the same animal. Thus, the high activity of these enzymes enables a faster rate of glycogenolysis in glycolytic M. longissimus dorsi compared to oxidative M. masseter. In chicken muscles, the GDE activity was low compared to pig or cattle muscles. Furthermore, the GDE activity in the glycolytic M. pectoralis superficialis was lower than in more oxidative M. quadriceps femoris despite the high phosphorylase activity in the former. The relative ratios between phosphorylase and GDE activity were higher in fast twitch glycolytic muscles than in slow twitch oxidative muscles of all studied animals. This suggests that the relatively low GDE activity compared to the phosphorylase activity in fast twitch glycolytic muscles may be a protection mechanism in living muscle against a very fast pH decrease. Chilling significantly decreased GDE activity and below 15 C porcine GDE was almost inactive. The effect of pH on GDE activity was only minor at the range normally found in post mortem muscles (pH 7.4 to 5.0). The GDE activity remained level for several hours after slaughter. During the first hours post mortem, GDE activity was similar in RN- carrier pigs and in wild type pigs. However, the GDE activity declined faster in M. longissimus dorsi from wild type pigs than in the RN carrier pigs, the difference between genotypes was significant after 24 h post mortem. Pro-glycogen and macro-glycogen contents were higher, pH decrease was faster and ultimate pH was lower in RN- carrier pigs than in wild type pigs. In the RN- carriers, the prolonged high GDE activity level may enable an extended pH decrease and lower ultimate pH in their muscles. In conclusion, GDE is not the main factor determining the rate or the extent of post mortem glycogenolysis, but under certain conditions, such as in very fast chilling, the inhibition of GDE activity in meat may reduce the rate of pH decrease and result in higher ultimate pH. The rate and extent of pH decrease affects several meat quality traits.

Extraction methods in soil phosphorus characterisation : Limitations and applications

The quantification and characterisation of soil phosphorus (P) is of agricultural and environmental importance and different extraction methods are widely used to asses the bioavailability of P and to characterize soil P reserves. However, the large variety of extractants, pre-treatments and sample preparation procedures complicate the comparison of published results. In order to improve our understanding of the behaviour and cycling of P in soil, it is crucial to know the scientific relevance of the methods used for various purposes. The knowledge of the factors affecting the analytical outcome is a prerequisite for justified interpretation of the results. The aim of this thesis was to study the effects of sample preparation procedures on soil P and to determine the dependence of the recovered P pool on the chemical nature of extractants. Sampling is a critical step in soil testing and sampling strategy is dependent on the land-use history and the purpose of sampling. This study revealed that pre-treatments changed soil properties and air-drying was found to affect soil P, particularly extractable organic P, by disrupting organic matter. This was evidenced by an increase in the water-extractable small-sized (<0.2 µm) P that, at least partly, took place at the expense of the large-sized (>0.2 µm) P. However, freezing induced only insignificant changes and thus, freezing can be taken to be a suitable method for storing soils from the boreal zone that naturally undergo periodic freezing. The results demonstrated that chemical nature of the extractant affects its sensitivity to detect changes in soil P solubility. Buffered extractants obscured the alterations in P solubility induced by pH changes; however, water extraction, though sensitive to physicochemical changes, can be used to reveal short term changes in soil P solubility. As for the organic P, the analysis was found to be sensitive to the sample preparation procedures: filtering may leave a large proportion of extractable organic P undetected, whereas the outcome of centrifugation was found to be affected by the ionic strength of the extractant. Widely used sequential fractionation procedures proved to be able to detect land-use -derived differences in the distribution of P among fractions of different solubilities. However, interpretation of the results from extraction experiments requires better understanding of the biogeochemical function of the recovered P fraction in the P cycle in differently managed soils under dissimilar climatic conditions.