Unraveling the function of bacterial-type phosphoenolpyruvate carboxylase in vascular plants

Two distinct phosphoenolpyruvate carboxylase (PEPC) isozymes occur in vascular plants and green algae: plant-type PEPC (PTPC) and bacterial-type PEPC (BTPC). PTPC polypeptides typically form a tightly regulated cytosolic Class-1 PEPC homotetramer. BTPCs, however, appear to be less widely expressed and to exist only as catalytic and regulatory subunits that physically interact with co-expressed PTPC subunits to form hetero-octameric Class-2 PEPC complexes that are highly desensitized to Class-1 PEPC allosteric effectors. Yeast two-hybrid studies indicated that castor plant BTPC (RcPPC4) interacts with all three Arabidopsis thaliana PTPC isozymes, and that it forms stronger interactions with AtPPC2 and AtPPC3, suggesting that specific PTPCs are preferred for Class-2 PEPC formation. In contrast, Arabidopsis BTPC (AtPPC4) appeared to interact very weakly with AtPPC2 and AtPPC3, suggesting that BTPCs from different species may have different physical properties, hypothesized to be due to sequence dissimilarities within their ~10 kDa intrinsically disordered region. Recent RNA-seq and microarray data were analyzed to obtain a better understanding of BTPC expression patterns in different tissues of various monocot and dicot species. High levels of BTPC transcripts, polypeptides and Class-2 PEPC complexes were originally discovered in developing castor seeds, but the analysis revealed a broad range of diverse tissues where abundant BTPC transcripts are also expressed, such as the developing fruits of cucumber, grape, and tomato. Marked BTPC expression correlated well with the presence of ~116 kDa immunoreactive BTPC polypeptides, as well as Class-2 PEPC complexes in the immature fruit of cucumbers and tomatoes. It is therefore hypothesized that in vascular plants BTPC and thus Class-2 PEPC complexes maintain anaplerotic PEP flux in tissues with elevated malate levels that would potently inhibit ‘housekeeping’ Class-1 PEPCs. Elevated levels of malate can be used by biosynthetically active sink tissues such as immature tomatoes and cucumbers for rapid cell expansion, drought or salt stressed roots for osmoregulation, and developing seeds and pollen as a precursor for storage lipid and protein biosynthesis.

Combining histology, stable isotope analysis and ZooMS collagen fingerprinting to investigate the taphonomic history and dietary behaviour of extinct giant tortoises from the Mare aux Songes deposit on Mauritius

Taphonomic research of bones can provide additional insight into a site's formation and development, the burial environment and ongoing post-mortem processes. A total of 30 tortoise (Cylindraspis) femur bone samples from the Mare aux Songes site (Mauritius)were studied histologically, assessing parameters such as presence and type of microbial alteration, inclusions, staining/infiltrations, the degree of microcracking and birefringence. The absence of microbial attack in the 4200 year old Mare aux Songes bones suggests the animals rapidly entered the soil whole-bodied and were sealed anoxically, although they suffered frombiological and chemical degradation (i.e. pyrite formation/oxidation, mineral dissolution and staining) related to changes in the site's hydrology. Additionally, carbon and nitrogen stable isotopeswere analysed to obtain information on the animals' feeding behaviour. The results show narrowly distributed δ13C ratios, indicating a terrestrial C3 plant-based diet, combined with a wide range in δ15N ratios. This is most likely related to the tortoises' drought-adaptive ability to change their metabolic processes, which can affect the δ15N ratios. Furthermore, ZooMS collagen fingerprinting analysis successfully identified two tortoise species (C. triserrata and C. inepta) in the bone assemblage,which,when combined with stable isotope data, revealed significantly different δ15N ratios between the two tortoise species. As climatic changes around this period resulted in increased aridity in the Mascarene Islands, this could explain the extremely elevated δ15N ratio in our dataset. The endemic fauna was able to endure the climatic changes 4200 years ago, although human arrival in the 17th century changed the original habitat to such an extent that it resulted in the extinction of several species. Fortunately we are still able to study these extinct tortoises due to the beneficial conditions of their burial environment, resulting in excellent bone preservation.

Comparing gold nano-particle enhanced radiotherapy with protons, megavoltage photons and kilovoltage photons: a Monte Carlo simulation

Gold nanoparticles (GNPs) have shown potential to be used as a radiosensitizer for radiation therapy. Despite extensive research activity to study GNP radiosensitization using photon beams, only a few studies have been carried out using proton beams. In this work Monte Carlo simulations were used to assess the dose enhancement of GNPs for proton therapy. The enhancement effect was compared between a clinical proton spectrum, a clinical 6 MV photon spectrum, and a kilovoltage photon source similar to those used in many radiobiology lab settings. We showed that the mechanism by which GNPs can lead to dose enhancements in radiation therapy differs when comparing photon and proton radiation. The GNP dose enhancement using protons can be up to 14 and is independent of proton energy, while the dose enhancement is highly dependent on the photon energy used. For the same amount of energy absorbed in the GNP, interactions with protons, kVp photons and MV photons produce similar doses within several nanometers of the GNP surface, and differences are below 15% for the first 10 nm. However, secondary electrons produced by kilovoltage photons have the longest range in water as compared to protons and MV photons, e.g. they cause a dose enhancement 20 times higher than the one caused by protons 10 μm away from the GNP surface. We conclude that GNPs have the potential to enhance radiation therapy depending on the type of radiation source. Proton therapy can be enhanced significantly only if the GNPs are in close proximity to the biological target.

Comparing long-term placements for young children in care: Does type of placement really matter?

This paper presents findings from the third phase of a longitudinal study, entitled Care Pathways and Outcomes, which has been tracking the placements and measuring outcomes for a population of children (n = 374) who were under the age of five and in care in Northern Ireland on the 31st March 2000. It explores how a sub-sample of these children at age nine to 14 years old were getting on in the placements provided for them, in comparative terms across five placement types: adoption; foster care; kinship foster care (with relatives); on Residence Order; and living with birth parents. This specifically focused on the development of attachment and self-concept from the perspective of the children, and behavioural and emotional function, and parenting stress, from the perspective of parents and carers. Findings showed no significant placement effect from the perspective of children, and a statistically weak, but descriptively compelling, effect from the perspective of parents. The findings challenge the notion of adoption as the gold standard in long-term placements, specifically from the perspective of children in terms of their parent/carer attachments and self-concept, and highlight what appears to be the central importance of placement longevity for delivering positive longer-term outcomes for these children, irrespective of placement type.

Laser ablation-based one-step generation and bio-functionalization of gold nanoparticles conjugated with aptamers

Background: Bio-conjugated nanoparticles are important analytical tools with emerging biological and medical applications. In this context, in situ conjugation of nanoparticles with biomolecules via laser ablation in an aqueous media is a highly promising one-step method for the production of functional nanoparticles resulting in highly efficient conjugation. Increased yields are required, particularly considering the conjugation of cost-intensive biomolecules like RNA aptamers. Results: Using a DNA aptamer directed against streptavidin, in situ conjugation results in nanoparticles with diameters of approximately 9 nm exhibiting a high aptamer surface density (98 aptamers per nanoparticle) and a maximal conjugation efficiency of 40.3%. We have demonstrated the functionality of the aptamer-conjugated nanoparticles using three independent analytical methods, including an agglomeration-based colorimetric assay, and solid-phase assays proving high aptamer activity. To demonstrate the general applicability of the in situ conjugation of gold nanoparticles with aptamers, we have transferred the method to an RNA aptamer directed against prostate-specific membrane antigen (PSMA). Successful detection of PSMA in human prostate cancer tissue was achieved utilizing tissue microarrays. Conclusions: In comparison to the conventional generation of bio-conjugated gold nanoparticles using chemical synthesis and subsequent bio-functionalization, the laser-ablation-based in situ conjugation is a rapid, one-step production method. Due to high conjugation efficiency and productivity, in situ conjugation can be easily used for high throughput generation of gold nanoparticles conjugated with valuable biomolecules like aptamers.

Carbon gold rush and carbon cowboys: a new chapter in green mythology?

Individual and collective efforts to mitigate climate change in the form of carbon offsetting and emissions trading schemes have recently become the focus of much media attention. In this paper we explore a subset of the UK national press coverage centered on such schemes. The articles, selected from general as well as specialized business and finance newspapers, make use of gold rush, Wild West and cowboy imagery which is rooted in deeply entrenched myths and metaphors and allows readers to make sense of very complex environmental, political, ethical, and financial issues associated with carbon mitigation. They make what appears complicated and unfamiliar, namely carbon trading and offsetting, seem less complex and more familiar. A critical discussion of this type of imagery is necessary in order to uncover and question tacit assumptions and connotations which are built into it and which might otherwise go unnoticed and unchallenged in environmental communication.

Unraveling the function of bacterial-type phosphoenolpyruvate carboxylase in vascular plants

Thesis (Master, Biology) -- Queen's University, 2016-09-29 20:09:46.997

Gold Science Ghost Drawing #1

Mixed media. 78" x 56", Gold Science Ghost Drawings Series.

Gold Science Ghost Drawing #2

Mixed media. 67" x 50", Gold Science Ghost Drawings Series.

Gold Science Ghost Drawing #5

Mixed media. 105½" x 42", Gold Science Ghost Drawings Series. Private Collection

Vibrational spectroscopy of phthalocyanine and naphthalocyanine in sandwich-type (na)phthalocyaninato and porphyrinato rare earth complexes : (Part 10) The infrared and Raman characteristics of phthalocyanine in heteroleptic bis(phthalocyaninato) rare earth complexes with decreased molecular symmetry

The infrared (IR) spectroscopic data for a series of eleven heteroleptic bis(phthalocyaninato) rare earth complexes MIII(Pc)[Pc(α-OC5H11)4] (M = Sm–Lu, Y) [H2Pc = unsubstituted phthalocyanine, H2Pc(α-OC5H11)4 = 1,8,15,22-tetrakis(3-pentyloxy)phthalocyanine] have been collected with 2 cm−1 resolution. Raman spectroscopic properties in the range of 500–1800 cm−1 for these double-decker molecules have also been comparatively studied using laser excitation sources emitting at 632.8 and 785 nm. Both the IR and Raman spectra for M(Pc)[Pc(α-OC5H11)4] are more complicated than those of homoleptic bis(phthalocyaninato) rare earth analogues due to the decreased molecular symmetry of these double-decker compounds, namely C4. For this series, the IR Pc√− marker band appears as an intense absorption at 1309–1317 cm−1, attributed to the pyrrole stretching. With laser excitation at 632.8 nm, Raman vibrations derived from isoindole ring and aza stretchings in the range of 1300–1600 cm−1 are selectively intensified. In contrast, when excited with laser radiation of 785 nm, the ring radial vibrations of isoindole moieties and dihedral plane deformations between 500 and 1000 cm−1 for M(Pc)[Pc(α-OC5H11)4] intensify to become the strongest scatterings. Both techniques reveal that the frequencies of pyrrole stretching, isoindole breathing, isoindole stretchings, aza stretchings and coupling of pyrrole and aza stretchings depend on the rare earth ionic size, shifting to higher energy along with the lanthanide contraction due to the increased ring-ring interaction across the series. The assignments of the vibrational bands for these compounds have been made and discussed in relation to other unsubstituted and substituted bis(phthalocyaninato) rare earth analogues, such as M(Pc)2 and M(OOPc)2 [H2OOPc = 2,3,9,10,16,17,23,24-octakis(octyloxy)phthalocyanine].