Exploring the learning potential of an artificial life simulation

CULTURE is an Artificial Life simulation that aims to provide primary school children with opportunities to become actively engaged in the high-order thinking processes of problem solving and critical thinking. A preliminary evaluation of CULTURE has found that it offers the freedom for children to take part in process-oriented learning experiences. Through providing children with opportunities to make inferences, validate results, explain discoveries and analyse situations, CULTURE encourages the development of high-order thinking skills. The evaluation found that CULTURE allows users to autonomously explore the important scientific concepts of life and living, and energy and change within a software environment that children find enjoyable and easy to use.

N4WBP5, a potential target for ubiquitination by the Nedd4 family of proteins, is a novel golgi-associated protein

Nedd4 belongs to a family of ubiquitin-protein ligases that is characterized by 2-4 WW domains, a carboxyl-terminal Hect ((h) under bar omologous to (E) under bar6-AP (C) under bar arboxyl (t) under bar erminus)-domain and in most cases an amino-terminal C2 domain. We had previously identified a series of proteins that associates with the WW domains of Nedd4. In this paper, we demonstrate that one of the Nedd4-binding proteins, N4WBP5, belongs to a small group of evolutionarily conserved proteins with three transmembrane domains. N4WBP5 binds Nedd4 WW domains via the two PPXY motifs present in the amino terminus of the protein. In addition to Nedd4, N4WBP5 can interact with the WW domains of a number of Nedd4 family members and is ubiquitinated. Endogenous N4WBP5 localizes to the Golgi complex. Ectopic expression of the protein disrupts the structure of the Golgi, suggesting that N4WBP5 forms part of a family of integral Golgi membrane proteins. Based on previous observations in yeast, we propose that N4WBP5 may act as an adaptor for Nedd4-like proteins and their putative targets to control ubiquitin-dependent protein sorting and trafficking.

Leaf water potential and osmotic adjustment as physiological traits to improve drought tolerance in rice

A sample of recombinant inbred lines (RILs) was derived from a bi-parental cross between Lemont and BK88-BR6, which contrasted in maintenance of leaf water potential (LWP) and expression of osmotic adjustment (OA). Genotypic variation for LWP and OA, and their associations with yield determination under water deficit, was studied in a series of five field experiments. Genotypic variation in the maintenance of high LWP was consistent across water deficit experiments. In the determination of genotypic variation in the maintenance of LWP, rate of water deficit was not an important factor influencing ranking, but degree of water deficit, and phenological development stage were important, particularly around heading. Genotypic variation in expression of OA was also observed under water deficits during both vegetative and flowering stages but ranking was inconsistent across experiments. This was in part because of large experimental errors associated with its measurement, but also because the expression of OA was associated with extent of decline of LWP. The relationship between OA and LWP was demonstrated when data were combined across experiments for vegetative and flowering stages. Under water-limited conditions around flowering, grain yield reduction was mainly due to a increased spikelet sterility. Variation in OA was not related to grain yield nor yield components. There were however, negative phenotypic and genetic correlations between LWP and percentage spikelet sterility measured at flowering stage on panicles at the same development stage during a water deficit treatment. This suggests that traits contributing to the maintenance of high LWP minimized the effects of water deficit on spikelet sterility and consequently grain yield. (C) 2002 Elsevier Science B.V. All rights reserved.

Which aspects of socio-economic status are related to health in mid-aged and older women?

A population-based study was conducted to validate gender- and age-specific indexes of socio-economic status (SES) and to investigate the associations between these indexes and a range of health outcomes in 2 age cohorts of women. Data from 11,637 women aged 45 to 50 and 9,5 10 women aged 70 to 75 were analyzed. Confirmatory factor analysis produced four domains of SES among the mid-aged cohort (employment, family unit, education, and migration) and four domains among the older cohort (family unit, income, education, and migration). Overall, the results supported the factor structures derived from another population-based study (Australian Bureau of Statistics, 1995), reinforcing the argument that SES domains differ across age groups. In general, the findings also supported the hypotheses that women with low SES would have poorer health outcomes than higher SES women, and that the magnitude of these effects would differ according to the specific SES domain and by age group, with fewer and smaller differences observed among older women. The main exception was that in the older cohort, the education domain was significantly associated with specific health conditions. Results suggest that relations between SES and health are highly complex and vary by age, SES domain, and the health outcome under study.

QCD thermal phase transition in the presence of a small chemical potential

We propose a new method to investigate the thermal properties of QCD with a small quark chemical potential mu. Derivatives of quark and gluonic observables with respect to mu are computed at mu=0 for two flavors of p4 improved staggered fermions with ma=0.1,0.2 on a 16(3)x4 lattice, and used to calculate the leading order Taylor expansion in mu of the location of the pseudocritical point about mu=0. This expansion should be well behaved for the small values of mu(q)/T(c)similar to0.1 relevant for BNL RHIC phenomenology, and predicts a critical curve T-c(mu) in reasonable agreement with estimates obtained using exact reweighting. In addition, we contrast the case of isoscalar and isovector chemical potentials, quantify the effect of munot equal0 on the equation of state, and comment on the complex phase of the fermion determinant in QCD with munot equal0.

Carpogenic germination of Sclerotinia minor and potential distribution in Australia

This study confirms that Australian isolates of Sclerotinia minor can produce fertile apothecia and further demonstrates that ascospores collected from these apothecia are pathogenic to sunflower (Helianthus annuus). Sunflower is a known host of the related fungus Sclerotinia sclerotiorum and is grown in some regions where S. minor is known to occur. Head rot symptoms were produced following inoculation with S. minor ascospores. Predictive modeling using CLIMEX software suggested that conditions suitable for carpogenic germination of S. minor probably occur in Australia particularly in southern regions. Carpogenic germination is probably a rare event in northern regions and, if it does occur, probably does not coincide with anthesis in sunflower crops, therefore allowing disease escape.

Practical and economic advantages of choice feeding systems for laying poultry

Poultry can be managed under different feeding systems, depending on the husbandry skills and the feed available. These systems include the following: (1) a complete dry feed offered as a mash ad libitum; (2) the same feed offered as pellets or crumbles ad libitum; (3) a complete feed with added whole grain; (4) a complete wet feed given once or twice a day; (5) a complete feed offered on a restricted basis; (6) choice feeding. Of all these, an interesting alternative to offering complete diets is choice feeding which can be applied on both a small or large commercial scale. Under choice feeding or free-choice feeding birds are usually offered a choice between three types of feedstuffs: (a) an energy source (e.g. maize, rice bran, sorghum or wheat); (b) a protein source (e.g. soyabean meal, meat meal, fish meal or coconut meal) plus vitamins and minerals and (c), in the case of laying hens, calcium in granular form (i.e. oyster-shell grit). This system differs from the modern commercial practice of offering a complete diet comprising energy and protein sources, ground and mixed together. Under the complete diet system, birds are mainly only able to exercise their appetite for energy. When the environmental temperature varies, the birds either over- or under-consume protein and calcium. The basic principle behind practising choice feeding with laying hens is that individual hens are able to select from the various feed ingredients on offer and compose their own diet, according to their actual needs and production capacity. A choice-feeding system is of particular importance to small poultry producers in developing countries, such as Indonesia, because it can substantially reduce the cost of feed. The system is flexible and can be constructed in such a way that the various needs of a flock of different breeds, including village chickens, under different climates can be met. The system also offers a more effective way to use home-produced grain, such as maize, and by-products, such as rice bran, in developing countries. Because oyster-shell grit is readily available in developing countries at lower cost than limestone, the use of cheaper oyster-shell grit can further benefit small-holders in these countries. These benefits apart, simpler equipment suffices when designing and building a feed mixer on the farm, and transport costs are lower. If whole (unground) grain is used, the intake of which is accompanied by increased efficiency of feed utilisation, the costs of grinding, mixing and many of the handling procedures associated with mash and pellet preparation are eliminated. The choice feedstuffs can all be offered in the current feed distribution systems, either by mixing the ingredients first or by using a bulk bin divided into three compartments.

Conserved modularity and potential for alternate splicing in mouse and human Slit genes

The vertebrate Slit gene family currently consists of three members;Slit1,Slit2 and Slit3. Each gene encodes a protein containing multiple epidermal growth factor and leucine rich repeat motifs, which are likely to have importance in cell-cell interactions. In this study, we sought to fully define and characterise the vertebrate Slit gene family. Using long distance PCR coupled with in silico mapping, we determined the genomic structure of all three Slit genes in mouse and man. Analysis of EST and genomic databases revealed no evidence of further Slit family members in either organism. All three Slit genes were encoded by 36 (Slit3) or 37 (Slit1 and Slit2) exons covering at least 143 kb or 183 kb of mouse or human genomic DNA respectively. Two additional potential leucine-rich repeat encoding exons were identified within intron 12 of Slit2. These could be inserted in frame, suggesting that alternate splicing may occur in Slit2 A search for STS sequences within human Slit3 anchored this gene to D5S2075 at the 5' end (exon 4) and SGC32449 within the 3' UTR, suggesting that Slit3 may cover greater than 693 kb. The genomic structure of all Slit genes demonstrated considerable modularity in the placement of exon-intron boundaries such that individual leucine-rich repeat motifs were encoded by individual 72 by exons. This further implies the potential generation of multiple Slit protein isoforms varying in their number of repeat units. cDNA library screening and EST database searching verified that such alternate splicing does occur.

A prostaglandin F2a Analog induces suppressors of the cytokine signalling-3 expression n the corpus luteum of the pregnant rat: A potential new mechanism in luteolysis

PRL and placental lactogen (PL) play key roles in maintaining the rodent corpus luteum through pregnancy. Suppressors of cytokine signaling (SOCS) have been shown to decrease cell sensitivity to cytokines, including PRL, and so here we have addressed the issue of whether luteolysis induced by prostaglandin F-2alpha (PGF(2alpha)) might up-regulate SOCS proteins to inhibit PRL signaling. In d 19 pregnant rats, cloprostenol, a PGF(2alpha) analog, rapidly induced transcripts for SOCS-3 and, to a lesser extent, SOCS-1. We also found increased SOCS-3 protein in the ovary by immunoblot and in the corpus luteum by immunohistochemistry. Increased SOCS-3 expression was preceded by an increase in STAT3 tyrosine phosphorylation 10 min after cloprostenol injection and was maintained for 4 h, as determined by gel shift and immunohistochemistry. Induction of SOCS-3 was accompanied by a sharp decrease in active STAT5, as determined by gel-shift assay and by loss of nuclear localized STAT5. Four hours after cloprostenol administration, the corpus luteum was refractory to stimulation of STAT5 by PRL administration, and this was not due to down-regulation of PRL receptor. Therefore, induction of SOCS-3 by PGF(2alpha) may be an important element in the initiation of luteolysis via rapid suppression of luteotropic support from PL.

The therapeutic potential of dopamine modulators on the cardiovascular and renal systems

In the periphery, physiological dopamine increases renal blood flow, decreases renal resistance and acts on the kidney tubule to enhance natriuresis and diuresis. The loss of dopamine function may be involoved in the deterioration in kidney function associated with ageing and may have a role in the pathogenesis of hypertension and diabetes. Intravenous dopamine is used as a positive inotrope in the treatment of acute heart failure and cardiogenic shock and as a diuretic in renal failure. The clinical uses of dopamine are limited, as it must be given intravenously, and also has widespread effects. The levels of peripheral dopamine can be increased by the administration of L-dopa to increase synthesis, prodrugs to release dopamine (docarpamine, glu-dopa) or by inhibiting the breakdown of dopamine (nitecapone). Preliminary clinical trials suggest that docarpamine may be useful in patients with low cardiac output syndrome after cardiac surgery and in refractory cirrhotic ascites. Ibopamine is an agonist at dopamine D1 and D2 receptors, which may retard the progression of chronic renal failure. Gludopa is selective for the kidney thus avoiding widespread side effects. The early clinical studies with ibopamine as a diuretic in heart failure were favourable but the subsequent large mortality study showed that ibopamine increased mortality. Fenoldopam is a selective dopamine D1 receptor agonist. Intravenous fenoldopam may be useful in the treatment of hypertension associated with coronary artery bypass surgery or in hypertensive emergencies. Although our understanding of physiological and pathological roles of peripheral dopamine has been increasing rapidly in recent times, we still need more information to allow the design of clinically useful drugs that modify these roles. One priority is an orally-active selective dopamine D1 receptor agonist.

Therapeutic potential of selective superoxide dismutase mimetics

Selective superoxide dismutase (SOD) mimetics are potentially useful in pathological conditions in which there is an overproduction of the superoxide anion O-2.(-). These pathological conditions include inflammation, ischemia/reperfusion, shock, various cardiovascular disorders, amyotrophic lateral sclerosis (ALS) and other neurodegenerative disorders. A major step forward in this field was the development of small-molecule selective SOD mimetics that penetrate cell membranes, These selective SOD mimetics catalytically remove O-2.(-) without interfering with nitric oxide (NO), peroxynitrite (ONOO-) or other radicals such as hydroxyl radical or hydrogen peroxide (H2O2). These selective SOD mimetics (SC-52608, SC-55858, M-40403 and M-40401) have been shown to have benefits in animal models of inflammation, ischemia/reperfusion, shock, thrombosis and diabetes. The next challenge with selective SOD mimetics is to develop therapeutic potential into therapeutic agents.