Environmentally induced functional shifts in phytoplankton and their potential consequences for ecosystem functioning

Phytoplanktonic organisms are particularly sensitive to environmental change, and, as they represent a direct link between abiotic and biotic compartments within the marine food web, changes in the functional structure of phytoplankton communities can result in profound impacts on ecosystem functioning. Using a trait-based approach, we examined changes in the functional structure of the southern North Sea phytoplankton over the past five decades in relation to environmental conditions. We identified a shift in functional structure between 1998 and 2004 which coincides with a pronounced increase in diatom and decrease in dinoflagellate abundances, and we provide a mechanistic explanation for this taxonomic change. Early in the 2000s, the phytoplankton functional structure shifted from slow growing, autumn blooming, mixotrophic organisms, towards earlier blooming and faster-growing microalgae. Warming and decreasing dissolved phosphorus concentrations were linked to this rapid reorganization of the functional structure. We identified a potential link between this shift and dissolved nutrient concentrations, and we hypothesise that organisms blooming early and displaying high growth rates efficiently take up nutrients which then are no longer available to late bloomers. Moreover, we identified that the above-mentioned functional change may have bottom-up consequences, through a food quality-driven negative influence on copepod abundances. Overall, our study highlights that, by altering the phytoplankton functional composition, global and regional changes may have profound long-term impacts on coastal ecosystems, impacting both food-web structure and biogeochemical cycles

Modulation of type II TGF-β receptor degradation by integrin-linked kinase

Cutaneous responses to injury, infection, and tumor formation involve the activation of resident dermal fibroblasts and subsequent transition to myofibroblasts. The key for induction of myofibroblast differentiation is the activation of transforming growth factor-β (TGF-β) receptors and stimulation of integrins and their associated proteins, including integrin-linked kinase (ILK). Cross-talk processes between TGF-β and ILK are crucial for myofibroblast formation, as ILK-deficient dermal fibroblasts exhibit impaired responses to TGF-β receptor stimulation. We now show that ILK associates with type II TGF-β receptors (TβRII) in ligand- and receptor kinase activity-independent manners. In cells with targeted Ilk gene inactivation, cellular levels of TβRII are decreased, through mechanisms that involve enhanced ubiquitination and proteasomal degradation. Partitioning of TGF-β receptors into membrane has been linked to proteasome-dependent receptor degradation. We found that interfering with membrane raft formation in ILK-deficient cells restored TβRII levels and signaling. These observations support a model whereby ILK functions in fibroblasts to direct TβRII away from degradative pathways during their differentiation into myofibroblasts

Communicating curriculum reform to students: Advice in hindsight.....

BACKGOUND: In view of the changing health care needs of communities, curriculum reform of traditional curricula is inevitable. In order to allay the apprehension that may accompany such change, curriculum development and implementation should be an inclusive process, with both staff and students being well informed of the planned reform. In 2001, the Nelson R. Mandela School of Medicine implemented Year 1 of a problem-based learning curriculum. During the design phase, students and staff were invited to take part in the development and were kept abreast of developments through meetings and newsletters. METHOD: A survey of Years 1–5 students of the last intake into the traditional curriculum was undertaken a few months prior to the implementation of the new programme. RESULTS: Students were generally well informed about the impending change, having heard about it from fellow students and staff. The more senior the students, the less the perceived impact of the reform. Although most of what students had heard was correct, some, however, had misconceptions that were generally extreme views (e.g. all self-directed learning; no Anatomy) about the new programme. Others expressed valid concerns (e.g. underpreparedness of students from disadvantaged schools; overcrowding in hospitals). CONCLUSIONS: Advice offered to institutions considering curriculum reform include using various methods to inform internal and external affected parties, ensuring that the student representative body and staff is well informed, reiterating the need for the change, confirming that the new programme meets recognised standards and that the students most affected are reassured about their future studies

The attentional blink is related to phonemic decoding, but not sight-word recognition, in typically reading adults

This research investigated the relationship between the attentional blink (AB) and reading in typical adults. The AB is a deficit in the processing of the second of two rapidly presented targets when it occurs in close temporal proximity to the first target. Specifically, this experiment examined whether the AB was related to both phonological and sight-word reading abilities, and whether the relationship was mediated by accuracy on a single-target rapid serial visual processing task (single-target accuracy). Undergraduate university students completed a battery of tests measuring reading ability, non-verbal intelligence, and rapid automatised naming, in addition to rapid serial visual presentation tasks in which they were required to identify either two (AB task) or one (single target task) target/s (outlined shapes: circle, square, diamond, cross, and triangle) in a stream of random-dot distractors. The duration of the AB was related to phonological reading (n=41, ß=-0.43): participants who exhibited longer ABs had poorer phonemic decoding skills. The AB was not related to sight-word reading. Single-target accuracy did not mediate the relationship between the AB and reading, but was significantly related to AB depth (non-linear fit, R2 = .50): depth reflects the maximal cost in T2 reporting accuracy in the AB. The differential relationship between the AB and phonological versus sight-word reading implicates common resources used for phonemic decoding and target consolidation, which may be involved in cognitive control. The relationship between single-target accuracy and the AB is discussed in terms of cognitive preparation

Introducing a reward system in assessment in histology: A comment on the learning strategies it might engender

BACKGROUND: Assessment, as an inextricable component of the curriculum, is an important factor influencing student approaches to learning. If assessment is to drive learning, then it must assess the desired outcomes. In an effort to alleviate some of the anxiety associated with a traditional discipline-based second year of medical studies, a bonus system was introduced into the Histology assessment. Students obtaining a year mark of 70% were rewarded with full marks for some tests, resulting in many requiring only a few percentage points in the final examination to pass Histology. METHODS: In order to ascertain whether this bonus system might be impacting positively on student learning, thirty-two second year medical students (non-randomly selected, representing four academic groups based on their mid-year results) were interviewed in 1997 and, in 1999, the entire second year class completed a questionnaire (n = 189). Both groups were asked their opinions of the bonus system. RESULTS: Both groups overwhelming voted in favour of the bonus system, despite less than 45% of students failing to achieve it. Students commented that it relieved some of the stress of the year-end examinations, and was generally motivating with regard to their work commitment. CONCLUSIONS: Being satisfied with how and what we assess in Histology, we are of the opinion that this reward system may contribute to engendering appropriate learning approaches (i.e. for understanding) in students. As a result of its apparent positive influence on learning and attitudes towards learning, this bonus system will continue to operate until the traditional programme is phased out. It is hoped that other educators, believing that their assessment is a reflection of the intended outcomes, might recognise merit in rewarding students for consistent achievement

The Benchmark Ultracool Subdwarf HD 114762B: A Test of Low-Metallicity Atmospheric and Evolutionary Models

We present a near-infrared spectroscopic study of HD 114762B, the latest-type metal-poor companion discovered to date and the only ultracool subdwarf with a known metallicity, inferred from the primary star to be [Fe/H] = -0.7. We obtained a medium-resolution Keck/OSIRIS J-band spectrum and a low-resolution IRTF/SpeX 0.8-2.4 um spectrum of HD 114762B. HD 114762B exhibits spectral features common to both late-type dwarfs and subdwarfs, and we assign it a spectral type of d/sdM9 +/- 1. We use a Monte Carlo technique to fit PHOENIX/GAIA synthetic spectra to the observations, accounting for the coarsely-gridded nature of the models. Fits to the entire OSIRIS J-band and to the metal-sensitive J-band atomic absorption features (Fe I, K I, and Al I lines) yield model parameters that are most consistent with the metallicity of the primary star and the high surface gravity expected of old late-type objects. The effective temperatures and radii inferred from the model atmosphere fitting broadly agree with those predicted by the evolutionary models of Chabrier & Baraffe, and the model color-absolute magnitude relations accurately predict the metallicity of HD 114762B. We conclude that current low-mass, mildly metal-poor atmospheric and evolutionary models are mutually consistent for spectral fits to medium-resolution J-band spectra of HD 114762B, but are inconsistent for fits to low-resolution near-infrared spectra of mild subdwarfs. Finally, we develop a technique for estimating distances to ultracool subdwarfs based on a single near-infrared spectrum. We show that this "spectroscopic parallax" method enables distance estimates accurate to < 10% of parallactic distances for ultracool subdwarfs near the hydrogen burning minimum mass. (abridged)Comment: Accepted by ApJ; 23 pages, 20 figure

Smad gene expression in pulmonary fibroblasts: indications for defective ECM repair in COPD

Background: Chronic Obstructive Pulmonary Disease ( COPD) is characterized by defective extracellular matrix (ECM) turnover as a result of prolonged cigarette smoking. Fibroblasts have a central role in ECM turnover. The TGF beta induced Smad pathway provides intracellular signals to regulate ECM production. We address the following hypothesis: fibroblasts have abnormal expression of genes in the Smad pathway in COPD, resulting in abnormal proteoglycan modulation, the ground substance of ECM. Methods: We compared gene expression of the Smad pathway at different time points after stimulation with TGF beta, TNF or cigarette smoke extract (CSE) in pulmonary fibroblasts of GOLD stage II and IV COPD patients, and controls. Results: Without stimulation, all genes were similarly expressed in control and COPD fibroblasts. TGF beta stimulation: downregulation of Smad3 and upregulation of Smad7 occurred in COPD and control fibroblasts, indicating a negative feedback loop upon TGF beta stimulation. CSE hardly influenced gene expression of the TGF beta-Smad pathway in control fibroblasts, whereas it reduced Smad3 and enhanced Smad7 gene expression in COPD fibroblasts. Furthermore, decorin gene expression decreased by all stimulations in COPD but not in control fibroblasts. Conclusion: Fibroblasts of COPD patients and controls differ in their regulation of the Smad pathway, the contrast being most pronounced under CSE exposure. This aberrant responsiveness of COPD fibroblasts to CSE might result in an impaired tissue repair capability and is likely important with regard to the question why only a subset of smokers demonstrates an excess ECM destruction under influence of cigarette smoking

The macroeconomic effects of Government asset purchases: evidence from postwar US housing credit policy

We document the portfolio activity of federal housing agencies and provide evidence on its impact on mortgage markets and the economy. Through a narrative analysis, we identify historical policy changes leading to expansions or contractions in agency mortgage holdings. Based on those regulatory events that we classify as unrelated to short-run cyclical or credit market shocks, we find that an increase in mortgage purchases by the agencies boosts mortgage lending and lowers mortgage rates. Agency purchases influence prices in other asset markets and stimulate residential investment. Using information in GSE stock prices to construct an alternative instrument for agency purchasing activity yields very similar results as our benchmark narrative identification approach

Identification of multiple transcription initiation, polyadenylation, and splice sites in the Drosophila melanogaster TART family of telomeric retrotransposons

The Drosophila non-long terminal repeat (non-LTR) retrotransposons TART and HeT-A specifically retrotranspose to chromosome ends to maintain Drosophila telomeric DNA. Relatively little is known, though, about the regulation of their expression and their retrotransposition to telomeres. We have used rapid amplification of cDNA ends (RACE) to identify multiple transcription initiation and polyadenylation sites for sense and antisense transcripts of three subfamilies of TART elements in Drosophila melanogaster. These results are consistent with the production of an array of TART transcripts. In contrast to other Drosophila non-LTR elements, a major initiation site for sense transcripts was mapped near the 3′ end of the TART 5′-untranslated region (5′-UTR), rather than at the start of the 5′-UTR. A sequence overlapping this sense start site contains a good match to an initiator consensus for the transcription start sites of Drosophila LTR retrotransposons. Interestingly, analysis of 5′ RACE products for antisense transcripts and the GenBank EST database revealed that TART antisense transcripts contain multiple introns. Our results highlight differences between transcription of TART and of other Drosophila non-LTR elements and they provide a foundation for testing the relationship between exceptional aspects of TART transcription and TART's specialized role at telomeres

Early and reversible changes to the hippocampal proteome in mice on a high-fat diet

Funding LMW, FMC, CG, ACM and C-DM were funded by the Scottish Government’s Rural and Environment Science and Analytical Services Division (RESAS). FHM was supported by an EASTBIO DTP BBSRC studentship. DS was supported by a SULSA studentship.Peer reviewedPublisher PD