Revealing the Roles of Subdomains in the Catalytic Behavior of Lipases/Acyltransferases Homologous to CpLIP2 through Rational Design of Chimeric Enzymes

The lipases/acyltransferases homologous to CpLIP2 of Candida parapsilosis efficiently catalyze acyltransfer reactions in lipid/water media with high water activity (a_W>0.9). Two new enzymes of this family, CduLAc from Candida dubliniensis and CalLAc8 from Candida albicans, were characterized. Despite 82 % sequence identity, the two enzymes have significant differences in their catalytic behaviors. In order to understand the roles played by the different subdomains of these proteins (main core, cap and C‐terminal flap), chimeric enzymes were designed by rational exchange of cap and C‐terminal flap, between CduLAc and CalLAc8. The results show that the cap region plays a significant role in substrate specificity; the main core was found to be the most important part of the protein for acyltransfer ability. Similar exchanges were made with CAL‐A from Candida antarctica, but only the C‐terminal exchange was successful. Yet, the role of this domain was not clearly elucidated, other than that it is essential for activity.     

Learning by Failing (and Fixing)

Unfortunately, students can graduate with a software engineering degree without learning anything about building secure systems. However, for the past two years at the Norwegian University of Science and Technology, a software security course has been giving students the theoretical foundation and practical experience necessary to start comprehending software security issues.     

Memory for Contextual Details: Effects of Emotion and Aging.

When individuals are confronted with a complex visual scene that includes some emotional element, memory for the emotional component often is enhanced, whereas memory for peripheral (nonemotional) details is reduced. The present study examined the effects of age and encoding instructions on this effect. With incidental encoding instructions, young and older adults showed this pattern of results, indicating that both groups focused attention on the emotional aspects of the scene. With intentional encoding instructions, young adults no longer showed the effect: They were just as likely to remember peripheral details of negative images as of neutral images. The older adults, in contrast, did not overcome the attentional bias: They continued to show reduced memory for the peripheral elements of the emotional compared with the neutral scenes, even with the intentional encoding instructions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of a Family Literacy Program on Low-Literate Children and Their Parents: Findings From an Evaluation of the Even Start Family Literacy Program.

A randomized experiment was conducted to test the effectiveness of Even Start, a federally supported family literacy program providing early childhood education, adult education, parenting education, and joint parent-child literacy activities to children and parents from low-literate families. The evaluation of 18 Even Start projects followed 463 families for 2 years and found no statistically significant or educationally important impacts on Even Start families when they were compared with control families on child literacy outcomes, parent literacy outcomes, or parent-child interactions. The study concludes that Even Start projects were able to properly implement family literacy programs, and the observed lack of effectiveness is attributed to a combination of 2 factors: (a) a lack of full participation on the part of families and (b) instructional services that may be ineffective because of the curriculum content or the instructional approach. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A mass spectrometric investigation into microenvironmental effects in solid-supported radical chemistry

Deuterated N-ethylpiperidine hypophosphite (d-EPHP) and tributyltin deuteride (TBTD) have been used to explore potential microenvironmental effects in resin-bound radical propagation. A deuterium labelling mass spectrometric method was used to show that efficiency of radical chain propagation on resin can be influenced by the choice of solid-support when using the slow radical chain carrier, EPHP.     

Use of the 15?N gas flux method to measure the source and level of N2O and N2 emissions from grazed grassland

Understanding the contribution of nitrification and denitrification to production of nitrous oxide (N₂O), a potent greenhouse gas, is important in devising effective mitigation strategies to reduce emissions. In this study the ¹⁵N gas flux method was used to investigate N₂O and N₂ emissions following an application of ¹⁵N labelled ammonium nitrate (0.71?mol?N?m^?2) to intensive grassland swards (grazed at 2.74 or 2.05 livestock units ha^?1 year^?1) at a site in Southern Ireland. The ¹⁵N labelled fertiliser (NO₃ moiety ¹⁵N labelled at 60 at. %) was applied to designated soil areas in the field, enclosed by static chambers, in June 2009, September 2009 and March 2010. Fluxes of N₂O and N₂ were determined over 12?days on each occasion. N₂O and N₂ emissions were significantly (P?<?0.001) lower in March 2010 than in June or September 2009. There was little difference between the two swards grazed at different stocking rates on N₂O or N₂ emissions. Mean cumulative N₂O emissions over 103?h were 212.9, 279.5 and 62.06?mg?m^?2 for June 2009, September 2009 and March 2010, respectively. Mean cumulative N₂ emissions for the three time periods were 818.8, 893.8 and 87?mg?m^?2, respectively. The N₂O mole fraction averaged 0.21 and 0.23 in June 2009 and September 2009, respectively, but increased to 0.41 in March 2010 which may have been due to changes in denitrifier community composition or due to N₂O reductase being sensitive to low soil temperatures. The results point to denitrification of nitrate as the major source of N₂O at this site which may have implications for choice of fertiliser in moist temperate climates.     

Phytase Activity from Lactobacillus spp. in Calcium-Fortified Soymilk

Abstract: The presence of phytate in calcium-fortified soymilk may interfere with mineral absorption. Certain lactic acid bacteria (LAB) produce the enzyme phytase that degrades phytates and therefore may potentially improve mineral bioavailability and absorption. This study investigates the phytase activity and phytate degradation potential of 7 strains of LAB including: Lactobacillus acidophilus ATCC4962, ATCC33200, ATCC4356, ATCC4161, L. casei ASCC290, L. plantarum ASCC276, and L. fermentum VRI-003. Activity of these bacteria was examined both in screening media and in calcium-fortified soymilk supplemented with potassium phytate. Most strains produced phytase under both conditions with L. acidophilus ATCC4161 showing the highest activity. Phytase activity in fortified soymilk fermented with L. acidophilus ATCC4962 and L. acidophilus ATCC4161 increased by 85% and 91%, respectively, between 12 h and 24 h of fermentation. All strains expressed peak phytase activity at approximately pH 5. However, no phytate degradation could be observed.     

Lipid-Bilayer-Supported 3D Printing of Human Cerebral Cortex Cells Reveals Developmental Interactions

Current understanding of human brain development is rudimentary due to suboptimal in vitro and animal models. In particular, how initial cell positions impact subsequent human cortical development is unclear because experimental spatial control of cortical cell arrangement is technically challenging. 3D cell printing provides a rapid customized approach for patterning. However, it has relied on materials that do not represent the extracellular matrix (ECM) of brain tissue. Therefore, in the present work, a lipid-bilayer-supported printing technique is developed to 3D print human cortical cells in the soft, biocompatible ECM, Matrigel. Printed human neural stem cells (hNSCs) show high viability, neural differentiation, and the formation of functional, stimulus-responsive neural networks. By using prepatterned arrangements of neurons and astrocytes, it is found that hNSC process outgrowth and migration into cell-free matrix and into astrocyte-containing matrix are similar in extent. However, astrocytes enhance the later developmental event of axon bundling. Both young and mature neurons migrate into compartments containing astrocytes; in contrast, astrocytes do not migrate into neuronal domains signifying nonreciprocal chemorepulsion. Therefore, precise prepatterning by 3D printing allows the construction of natural and unnatural patterns that yield important insights into human cerebral cortex development.     

The Collagen Suprafamily: From Biosynthesis to Advanced Biomaterial Development

Collagen is the oldest and most abundant extracellular matrix protein that has found many applications in food, cosmetic, pharmaceutical, and biomedical industries. First, an overview of the family of collagens and their respective structures, conformation, and biosynthesis is provided. The advances and shortfalls of various collagen preparations (e.g., mammalian/marine extracted collagen, cell‐produced collagens, recombinant collagens, and collagen‐like peptides) and crosslinking technologies (e.g., chemical, physical, and biological) are then critically discussed. Subsequently, an array of structural, thermal, mechanical, biochemical, and biological assays is examined, which are developed to analyze and characterize collagenous structures. Lastly, a comprehensive review is provided on how advances in engineering, chemistry, and biology have enabled the development of bioactive, 3D structures (e.g., tissue grafts, biomaterials, cell‐assembled tissue equivalents) that closely imitate native supramolecular assemblies and have the capacity to deliver in a localized and sustained manner viable cell populations and/or bioactive/therapeutic molecules. Clearly, collagens have a long history in both evolution and biotechnology and continue to offer both challenges and exciting opportunities in regenerative medicine as nature's biomaterial of choice.     

Analysis of a new type of high pressure homogeniser. A study of the flow pattern

High-pressure homogenisation is a key unit operation used to disrupt fat globules or cells containing intracellular bioproducts (AIChE J. 43(4) (1997) 1100). Modelling and optimisation of a small homogenising unit are often restrained by a lack of information on the flow conditions within the homogeniser valve. A numerical investigation of the flow within such a new homogenising valve, capable to reach pressure as high as (Stansted Fluid Power Ltd, UK) is presented. Results are obtained using the finite-volume technique and a RNG k-ε turbulence model with low Reynolds number near wall treatment conditions. An experimental measurement of the size of the valve gap is presented in order to validate mathematical relations that give valve gap sizes versus homogenising pressure. The modelling results give detailed information on the mechanical stresses and the high shear rates in small disruption valves, and also reveal other phenomena that could not be easily determined experimentally.