“Action Research into Pre-sessional Students' Differentiation of Assessments: Using Findings to Improve Courses”

Conference proceedings papaer in Whong, M. (Ed.), Proceedings of the 2007 BALEAP conference: English in a globalising world: English as an academic lingua franca,. Bern: Peter Lang.

Differentiation in populations of the apple scab fungus Venturia inaequalis on cultivars in a mixed orchard remains over time

The ascomycete Venturia inaequalis causes annual epidemics of apple scab worldwide. Scab development is reduced in mixed cultivar orchards compared with monocultures. To use mixtures in commercial production, we need to understand how the population of scab changes in a mixed orchard and how likely a super race, with virulence factors overcoming multiple resistance factors in the mixed orchard, is to emerge and become dominant. We used short sequence repeat (SSR) markers to investigate the temporal change of scab populations in two mixed cultivar orchards in the UK to infer the likelihood of emergence of a scab super race. There were no significant differences between the populations at the two sampling times (six or seven years apart) in either of the two mixed orchards. In one of the orchards apple scab populations on different cultivars were significantly different and the differences did not diminish over time. These results suggest that it is not inevitable that a super race of V. inaequalis will become dominant during the lifetime of a commercial apple orchard.

Differentiation of neotropical ecosystems by modern soil phytolith assemblages and its implications for palaeoenvironmental and archaeological reconstructions II: Southwestern Amazonian forests

Accurate archaeological and palaeoenvironmental reconstructions using phytoliths relies on the study of modern reference material. In eastern Acre, Brazil, we examined whether the five most common forest types present today were able to be differentiated by their soil phytolith assemblages, and thus provide analogues with which to compare palaeoecological assemblages from pre-Columbian earthwork sites in the region. Surface soils and vegetation from dense humid evergreen forest, dense humid evergreen forest with high palm abundance, palm forest, bamboo forest and fluvial forest were sampled and their phytoliths analysed. Relative phytolith frequencies were statistically compared using Principal Components Analyses (PCAs). We found the major differences in species composition to be well-represented by the phytolith assemblages as all forest types, apart from the two sub-types of dense humid evergreen forest, could be differentiated. Larger phytoliths from the sand fraction were found to be more ecologically diagnostic than those from the silt fraction. The surface soil phytolith assemblages we analysed can therefore be used as analogues to improve the accuracy of archaeological and palaeoecological reconstructions in the region.

Investigating typographic differentiation: italics are more subtle than bold for emphasis

Text designers are likely to benefit from guidance on how to use typographic differentiation for emphasis. Three experiments use purposely-designed fonts to explore the size and nature of differences in the stylistic characteristics of fonts (weight, width, contrast, italic) which affect letter identification. Results indicate that words set in bold and expanded fonts, when alternated with words set in a Neutral test font, may impair performance, whereas changing to italic does not. Possible explanations are explored through measuring the physical and perceptual similarities of the test fonts.

Calcium Hydroxide Promotes Cementogenesis and Induces Cementoblastic Differentiation of Mesenchymal Periodontal Ligament Cells in a CEMP1-and ERK-Dependent Manner

Periodontal tissue engineering is a complex process requiring the regeneration of bone, cementum, and periodontal ligament (PDL). Since cementum regeneration is poorly understood, we used a dog model of dental pulpal necrosis and in vitro cellular wounding and mineralization assays to determine the mechanism of action of calcium hydroxide, Ca(OH)(2), in cementogenesis. Laser capture microdissection (LCM) followed by qRT-PCR were used to assay responses of periapical tissues to Ca(OH)(2) treatment. Additionally, viability, proliferation, migration, and mineralization responses of human mesenchymal PDL cells to Ca(OH)(2) were assayed. Finally, biochemical inhibitors and siRNA were used to investigate Ca(OH)(2)-mediated signaling in PDL cell differentiation. In vivo, Ca(OH)(2)-treated teeth formed a neocementum in a STRO-1- and cementum protein-1 (CEMP1)-positive cellular environment. LCM-harvested tissues adjacent to the neocementum exhibited higher mRNA levels for CEMP1, integrin-binding sialoprotein, and Runx2 than central PDL cells. In vitro, Ca(OH)(2) and CEMP1 promoted STRO-1-positive cell proliferation, migration, and wound closure. Ca(OH)(2) stimulated expression of the cementum-specific proteins CEMP1 and PTPLA/CAP in an ERK-dependent manner. Lastly, Ca(OH)(2) stimulated mineralization by CEMP1-positive cells. Blocking CEMP1 and ERK function abolished Ca(OH)(2)-induced mineralization, confirming a role for CEMP1 and ERK in the process. Ca(OH)(2) promotes cementogenesis and recruits STRO-1-positive mesenchymal PDL cells to undergo cementoblastic differentiation and mineralization via a CEMP1- and ERK-dependent pathway.

Morphological differentiation between S. mutans and S. sobrinus on modified SB-20 culture medium

Due to the major role of Streptococcus mutans and Streptococcus sobrinus in the etiology of dental caries, it is important to use culture media that allow for differentiating these bacterial species. The aim of this study was to evaluate the suitability of a modified SB-20 culture medium (SB-20M) for the isolation and morphological differentiation of S. mutans and S. sobrinus, compared to biochemical identification (biotyping). Saliva samples were collected using the spatula method from 145 children, seeded on plates containing the SB-20M, in which sucrose was replaced by coarse granular cane sugar, and incubated in microaerophilia at 37 degrees C during 72 h. Identification of the microorganisms was performed under stereomicroscopy based on colony morphology of 4904 colonies. The morphological identification was examined by biochemical tests of 94 randomly selected colonies with the macroscopic characteristic of S. mutans and S. sobrinus using sugar fermentation, resistance to bacitracin and production of hydrogen peroxide. There was no statistically significant difference (p> 0.05) between morphological identification in the SB-20M medium and biochemical identification (biotyping). Biotyping confirmed that S. mutans and S. sobrinus colonies were correctly characterized in the SB-20M in 95.8% and 95.5% of the cases, respectively. Of the mutans streptococci detected in the children 98% were S. mutans and 2% S. sobrinus. The SB-20M medium is reliable for detection and direct morphological identification of S. mutans and S. sobrinus. (C) 2010 Elsevier GmbH. All rights reserved.

East-West cranial differentiation in pre-Columbian populations from Central and North America

In a recent study we found that crania from South Amerindian populations on each side of the Andes differ significantly in terms of craniofacial shape. Western populations formed one morphological group, distributed continuously over 14,000 km from the Fuegian archipelago (southern Chile) to the Zulia region (northwestern Venezuela). Easterners formed another group, distributed from the Atlantic Coast up to the eastern foothills of the Andes. This differentiation is further supported by several genetic studies, and indirectly by ecological and archaeological studies. Some authors suggest that this dual biological pattern is consistent with differential rates of gene flow and genetic drift operating on both sides of the Cordillera due to historical reasons. Here we show that such East-West patterning is also observable in North America. We suggest that the ""ecological zones model"" proposed by Dixon, explaining the spread of the early Americans along a Pacific dispersal corridor, combined with the evolution of different population dynamics in both regions, is the most parsimonious mechanism to explain the observed patterns of within- and between-group craniofacial variability. (c) 2007 Elsevier Ltd. All rights reserved.

Maintenance and differentiation of neural stem cells

The adult mammalian brain contains self-renewable, multipotent neural stem cells (NSCs) that are responsible for neurogenesis and plasticity in specific regions of the adult brain. Extracellular matrix, vasculature, glial cells, and other neurons are components of the niche where NSCs are located. This surrounding environment is the source of extrinsic signals that instruct NSCs to either self-renew or differentiate. Additionally, factors such as the intracellular epigenetics state and retrotransposition events can influence the decision of NSC`s fate into neurons or glia. Extrinsic and intrinsic factors form an intricate signaling network, which is not completely understood. These factors altogether reflect a few of the key players characterized so far in the new field of NSC research and are covered in this review. (C) 2010 John Wiley & Sons, Inc. WIREs Syst Biol Med 2011 3 107-114 DOI:10.1002/wsbm:100

Isolation, Characterization, and Differentiation Potential of Canine Adipose-Derived Stem Cells

Adipose tissue may represent a potential source of adult stem cells for tissue engineering applications in veterinary medicine. It can be obtained in large quantities, under local anesthesia, and with minimal discomfort. In this study, canine adipose tissue was obtained by biopsy from subcutaneous adipose tissue or by suction-assisted lipectomy (i.e., liposuction). Adipose tissue was processed to obtain a fibroblast-like population of cells similar to human adipose-derived stem cells (hASCs). These canine adipose-derived stem cells (cASCs) can be maintained in vitro for extended periods with stable population doubling and low levels of senescence. Immunofluorescence and flow cytometry show that the majority of cASCs are of mesodermal or mesenchymal origin. cASCs are able to differentiate in vitro into adipogenic, chondrogenic, myogenic, and osteogenic cells in the presence of lineage-specific induction factors. In conclusion, like human lipoaspirate, canine adipose tissue may also contain multipotent cells and represent an important stem cell source both for veterinary cell therapy as well as preclinical studies.

Male and female odors induce Fos expression in chemically defined neuronal population

Olfactory information modulates innate and social behaviors in rodents and other species. Studies have shown that the medial nucleus of the amygdala (MEA) and the ventral premammillary, nucleus (PMV) are recruited by conspecific odor stimulation. However, the chemical identity of these neurons is not determined. We exposed sexually inexperienced male rats to female or male odors and assessed Fos immunoreactivity (Fos-ir) in neurons expressing NADPH diaphorase activity (NADPHd, a nitric oxide synthase), neuropeptide Urocortin 3, or glutamic acid decarboxylase rnRNA (GAD-67, a GABA-synthesizing enzyme) in the MEA and PMV. Male and female odors elicited Fos-ir in the MEA and PMV neurons, but the number of Fos-immunoreactive neurons was higher following female odor exposure, in both nuclei. We found no difference in odor induced Fos-ir ill the MEA and PMV comparing fed and fasted animals. Ill the MEA, NADPHd neurons colocalized Fos-ir only in response to female odors. In addition, Urocortin 3 neurons comprise a distinct population and they do not express Fos-ir after conspecific odor stimulation. We found that 80% of neurons activated by male odors coexpressed GAD-67 mRNA. Following female odor, 50% of Fos neurons coexpressed GAD-67 rnRNA. The PMV expresses very little GAD-67, and virtually no colocalization with Fos was observed. We found intense NADPHd activity in PMV neurons, some of which coexpressed Fos-ir after exposure to both odors. The majority of the PMV neurons expressing NADPHd colocalized cocaine-and amphetamine-regulated transcript (CART). Our findings suggest that female and male odors engage distinct neuronal populations in the MEA, thereby inducing contextualized behavioral responses according to olfactory cues. In the PMV, NADPHd/CART neurons respond to male and female odors, suggesting a role in neuroendocrine regulation in response to olfactory cues. (C) 2009 Elsevier Inc. All rights reserved.

Prolonged consumption of soy or fish-oil-enriched diets differentially affects the pattern of hypothalamic neuronal activation induced by refeeding in rats

We used c-Fos immunoreactivity to estimate neuronal activation in hypothalamic feeding-regulatory areas of 3-month-old rats fed control or oil-enriched diets (soy or fish) since weaning. While no diet effect was observed in c-Fos immunoreactivity of 24-h fasted animals, the acute response to refeeding was modified by both hyperlipidic diets but with different patterns. Upon refeeding, control-diet rats had significantly increased c-Fos immunoreactivity only in the paraventricular hypothalamic nucleus (PVH, 142%). In soy-diet rats, refeeding with the soy diet increased c-Fos immunoreactivity in dorsomedial hypothalamic nucleus (DMH, 271%) and lateral hypothalamic area (LH, 303%). Refeeding fish-diet rats with the fish diet increased c-Fos immunoreactivity in PVH (161%), DMH (177%), VMH (81%), and ARC (127%). Compared to the fish-diet, c-Fos immunoreactivity was increased in LH by the soy-diet while it was decreased in ventromedial hypothalamic nucleus (VMH) and arcuate hypothalamic nucleus (ARC). Based on the known roles of the activated nuclei, it is suggested that, unlike the fish-diet, the soy-diet induced a potentially obesogenic profile, with high LH and low VMH/PVH activation after refeeding.

Insights on eukaryotic translation initiation factor 5A (eIF5A) in the brain and aging

Long-term memory, a persistent form of synaptic plasticity, requires translation of a subset of mRNA present in neuronal dendrites during a short and critical period through a mechanism not yet fully elucidated. Western blotting analysis revealed a high content of eukaryotic translation initiation factor 5A (eIF5A) in the brain of neonatal rats, a period of intense neurogenesis rate, differentiation and synaptic establishment, when compared to adult rats. Immunohistochemistry analysis revealed that eIF5A is present in the whole brain of adult rats showing a variable content among the cells from different areas (e.g. cortex, hippocampus and cerebellum). A high content of eIF5A in the soma and dendrites of Purkinje cells, key neurons in the control of motor long-term memory in the cerebellum, was observed. Detection of high eIF5A content was revealed in dendritic varicosities of Purkinje cells. Evidence is presented herein that a reduction of eIF5A content is associated to brain aging. (C) 2008 Elsevier B.V. All rights reserved.

Transdural motor cortex stimulation reverses neuropathic pain in rats: A profile of neuronal activation

Motor cortex stimulation (MCS) has been used to treat patients with neuropathic pain resistant to other therapeutic approaches; however, the mechanisms of pain control by MCS are still not clearly understood. We have demonstrated that MCS increases the nociceptive threshold of naive conscious rats, with opioid participation. In the present study, the effect of transdural MCS on neuropathic pain in rats subjected to chronic constriction injury of the sciatic nerve was investigated. In addition, the pattern of neuronal activation, evaluated by Fos and Zif268 immunolabel, was performed in the spinal cord and brain sites associated with the modulation of persistent pain. MCS reversed the mechanical hyperalgesia and allodynia induced by peripheral neuropathy. After stimulation, Fos immunoreactivity (Fos-IR) decreased in the dorsal horn of the spinal cord and in the ventral posterior lateral and medial nuclei of the thalamus, when compared to animals with neuropathic pain. Furthermore, the MCS increased the Fos-IR in the periaqueductal gray, the anterior cingulate cortex and the central and basolateral amygdaloid nuclei. Zif268 results were similar to those obtained for Fos, although no changes were observed for Zif268 in the anterior cingulate cortex and the central amygdaloid nucleus after MCS. The present findings suggest that MCS reverts neuropathic pain phenomena in rats, mimicking the effect observed in humans, through activation of the limbic and descending pain inhibitory systems. Further investigation of the mechanisms involved in this effect may contribute to the improvement of the clinical treatment of persistent pain. (c) 2010 European Federation of International Association for the Study of Pain Chapters. Published by Elsevier Ltd. All rights reserved.