Searching beneath the shelf in macaque monkeys: Evidence for a gravity bias or a foraging bias?

The reasons underpinning search biases in 2 species of macaque monkeys (Macaca mulatta and Macaca arctoides) were explored over the course of 3 experiments requiring monkeys to search for a hidden food reward. The results reveal that monkeys are adept at exploiting perceptual cues to locate a food reward but are unable to use physical constraints such as solidity as cues to the reward's location. Monkeys prefer to search for a food reward beneath a solid shelf, not because they have an expectation that the reward should be there, but rather because, in the absence of usable cues, this bias emerges as a default search option. It is hypothesized that this bias may have its roots in a history of competition for food resources. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social evaluation and the empathy–altruism hypothesis.

Tested the claim of R. L. Archer et al (see record 1982-05783-001) that empathy leads to increased helping only under socially evaluative circumstances. In Exp I, 22 female undergraduates were led to believe that no one (including the person in need) would ever know if they declined to help. In this situation, which was designed to be devoid of the potential for negative social evaluation for not helping, there was still a positive relationship between self-reported empathic emotion and offering help. In Exp II, empathy (low vs high) and social evaluation (low vs high) were manipulated with 32 Ss. Once again there was a positive relationship between empathy and offering help when the potential for social evaluation was low as well as high. Results of both studies suggest that the motivation to help evoked by empathy is not egoistic motivation to avoid negative social evaluation. Instead, the observed pattern was what would be expected if empathy evokes altruistic motivation to reduce the victim's need. (23 ref) (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Determination of trimethylamine in milk using an MS based electronic Nose

A simple, rapid, reliable and highly automated analytical method has been developed to determine trimethylamine (TMA) in milk using an MS based electronic nose (SMart Nose). A set of Swedish milk samples with and without naturally occurring TMA was used to compare this new method with sensory analysis and dynamic headspace (DHS) gas chromatography with flame ionisation detection (GC-FID). The results show good agreement between these three analytical methods. A lower detection limit (0.5 mg kg^-1) and better repeatability were achieved with this new method compared to both sensory and DHS GC-FID analyses (1-2 mg kg^-1). The user-friendly multivariate analysis software provided with the SMart Nose system was used for TMA determination via a numerical PCA. Using Excel, peak intensity, correlated with TMA concentration via a second order equation, gave similar results. Thus, this is an up to date method of choice for the quantitative determination of TMA in milk. It is also able to give further qualitative information on the milk analysed using the PCA analysis supplied with this equipment.     

Protein Engineering of the Antitumor Enzyme PpADI for Improved Thermal Resistance

Arginine deiminase (ADI, EC 3.5.3.6) is a potential antitumor drug for the treatment of arginine‐auxotrophic tumors such as hepatocellular carcinomas (HCCs) and melanomas. Studies in human lymphatic leukemia cell lines have confirmed the anti‐angiogenic activity of ADI. Activity and thermal resistance limit the efficacy of ADI in treatment of auxotrophic tumors. Previously, we reengineered ADI from Pseudomonas plecoglossicida (PpADI) for improved activity under physiological conditions (37 °C, PBS buffer, pH 7.4) by two rounds of directed evolution and combination of beneficial substitutions through site‐directed mutagenesis. The best variant, PpADI M6 (K5T/D38H/D44E/A128T/E296K/H404R), showed a 64.7‐fold improvement in k_cat value and a 37.6 % decreased S_0.5 value under physiological conditions. However, M6 lost rapidly its activity (half‐life of ～2 days at 37 °C). Here we report the re‐engineering of PpADI M6 for improved thermal resistance by directed evolution in order to increase its half‐life under physiological conditions. Directed evolution and recombination of the two most beneficial positions yielded variant PpADI M9 (K5T/D38H/D44E/A128T/V140L/E296K/F325L/H404R), for which the T_m value increased from 47 (M6) to 54 °C (M9); this corresponds to an increased half‐life from ～2 days (M6) to ～3.5 days (M9) under physiological conditions. Structure analysis of the homology model of M9 showed that the beneficial substitutions V140L and F325L likely promote the formation of tetrameric PpADI, which has greater thermal resistance than dimeric PpADI.     

Construction of a Fuzzy and Boolean Logic Gates Based on DNA

Logic gates are devices that can perform logical operations by transforming a set of inputs into a predictable single detectable output. The hybridization properties, structure, and function of nucleic acids can be used to make DNA‐based logic gates. These devices are important modules in molecular computing and biosensing. The ideal logic gate system should provide a wide selection of logical operations, and be integrable in multiple copies into more complex structures. Here we show the successful construction of a small DNA‐based logic gate complex that produces fluorescent outputs corresponding to the operation of the six Boolean logic gates AND, NAND, OR, NOR, XOR, and XNOR. The logic gate complex is shown to work also when implemented in a three‐dimensional DNA origami box structure, where it controlled the position of the lid in a closed or open position. Implementation of multiple microRNA sensitive DNA locks on one DNA origami box structure enabled fuzzy logical operation that allows biosensing of complex molecular signals. Integrating logic gates with DNA origami systems opens a vast avenue to applications in the fields of nanomedicine for diagnostics and therapeutics.     

A survey of total hydrocyanic acid content in ready-to-eat cassava-based chips obtained in the Australian market in 2008

Cassava (Manihot esculenta Crantz) is a widely consumed food in the tropics that naturally contains cyanogenic glycosides (cyanogens, mainly composed of linamarin, acetone cyanohydrin, and hydrocyanic acid). If cassava is not adequately processed to reduce the level of cyanogens prior to consumption, these compounds can lead to the formation of hydrocyanic acid in the gut. Exposure to hydrocyanic acid can cause symptoms ranging from vomiting and abdominal pain to coma and death. In 2008, a survey of ready-to-eat (RTE) cassava-based snack foods was undertaken to determine levels of cyanogens measured as total hydrocyanic acid. This survey was undertaken in response to the New South Wales Food Authority being alerted to the detection of elevated levels of cyanogens in an RTE cassava-based snack food. This survey took 374 samples of RTE cassava chips available in the Australian marketplace. Significant variation in the levels of total hydrocyanic acid were observed in the 317 samples testing positive for cyanogens, with levels ranging from 13 to 165 mg of HCN equivalents per kg (mean value, 64.2 mg of HCN eq/kg for positive samples). The results from this survey serve as a timely warning for manufacturers of RTE cassava chips and other cassava-based snack foods to ensure there is tight control over the levels of cyanogens in the cassava ingredient. Evidence from this survey contributed to an amendment to the Australia New Zealand Food Standards Code, which now prescribes a maximum level for hydrocyanic acid in RTE cassava chips of 10 mg of HCN eq/kg, which aligns with the Codex Alimentarius Commission international standard for edible cassava flour.     

Development and use of polyethylene passive samplers to detect triclosans and alkylphenols in an urban estuary

To be able to use polyethylene passive samplers (PE) in the field, the partitioning constants between PE and water (K(PEw)) of the compounds examined must be known. The K(PEw)s of triclosan (TCS), methyl-triclosan (MTCS), n-nonylphenol (n-NP), nonylphenol-technical mix (NP-tech), n-octylphenol (n-OP), and t-octylphenol (t-OP) were measured as a function of pH, temperature, and salinity, and a salt effect was calculated for TCS, n-OP, and t-OP. Log K(PEw)s used for calculating dissolved concentrations were taken from 20 °C studies taking salt into account: 3.42 (TCS), 4.53 (MTCS), 4.20 (n-NP), 3.69 (n-OP), and 2.87 (t-OP). The K(PEw) of hydroxyl-group containing compounds were strongly affected by pH, whereas MTCS with its methoxy-group was not. Measured K(PEw)s could not be estimated from octanol-water partitioning constants due to the semipolar makeup of the compounds investigated. Instead, a good correlation (K(PEw) = 0.679 × K(hdw) + 1.033, r(2) = 0.984, p = 0.001) was obtained with hexadecane-water partitioning constants (K(hdw)) predicted from COSMOtherm. During deployments in Narragansett Bay (RI) in the fall of 2009, concentrations of MTCS and t-OP in surface and bottom waters ranged from 40-225 pg L(-1) and 3.5-11 ng L(-1), respectively. These concentrations are far below EC(50) values for rainbow trout. Surface/bottom and bottom/porewater activity ratios were calculated. These indicated surface waters as the main source of MTCS, while surface water as well as sediments were sources of t-OP.     

Thermal, microstructural and textural characterisation of gelatinised corn, cassava and yam starch blends

The functional properties of mixtures of maize, cassava and yam starches and their relationships with microstructural characteristics were investigated. Experiments were performed following the simplex‐centroid design with internal points and restrictions (upper limit) for yam starch proportion. The statistical model used (Scheffé canonical equation) was a powerful tool to predict the pastes behaviour within the limits of the experimental area. Polynomials with second level interactions were applied to obtain the surface response. Viscoelastic attributes of mixtures differed from those of individual starches. As shown by differential scanning calorimetry and microscopical observations, physical properties of the mixtures depended on the type of networks obtained. These networks varied upon yam, corn and cassava starch proportions as each one has a particular characteristic: gelatinisation temperature, granule size, swelling capacity and amylose/amylopectin ratio among others.