Elevated hypothalamic beacon gene expression in Psammomys obesus prone to develop obesity and type 2 diabetes

Objective: To investigate hypothalamic beacon gene expression at various developmental stages in genetically selected diabetes-resistant and diabetes-prone Psammomys obesus. In addition, effects of dietary energy composition on beacon gene expression were investigated in diabetes-prone P. obesus. Methods: Hypothalamic beacon gene expression was measured using TaqmanÔ fluorogenic PCR in 4-, 8- and 16-week-old animals from each genetically selected line. Results: Expression of beacon was elevated in the diabetes-prone compared with diabetes-resistant P. obesus at 4 weeks of age despite no difference in body weight between the groups. At 8 weeks of age, hypothalamic beacon gene expression was elevated in diabetes-prone animals fed a high-energy diet, and was correlated with serum insulin concentration. Conclusion: P. obesus with a genetic predisposition for the development of obesity and type 2 diabetes have elevated hypothalamic beacon gene expression at an early age. Overexpression of beacon may contribute to the development of obesity and insulin resistance in these animals.

Identification of hypothalamic genes implicated in the development of obesity in Psammomys obesus using differential display PCR

The hypothalamus is a key central controller of energy homeostasis and is the source and/or site of action of many neuropeptides involved in this process. The aim of this study was to isolate hypothalamic genes differentially expressed between lean and obese Psammomys obesus, a polygenic animal model of obesity and type 2 diabetes. Differential display PCR was used to compare hypothalamic gene expression profiles of lean and healthy, obese and hyperinsulinemic, and obese, diabetic P. obesus in both the fed and fasted states. We conducted differential display with 180 separate primer combinations to amplify approximately 9000 expressed transcripts. Sixty differentially expressed bands were excised. Taqman PCR was performed on 36 of these transcripts to confirm differential gene expression in a larger sample population. Of these 36 transcripts, 9 showed homology to known genes, and 27 were considered to be novel sequences. Gene expression profiles for two of these genes are presented here. In conclusion, differential display PCR was successfully used to isolate several transcripts that may be involved in the central regulation of energy balance. We are currently conducting numerous studies to further investigate the role of these genes in the development of obesity in P. obesus.

Identification of novel genes expressed during rhabdomyosarcoma differentiation using cDNA microarrays

Rhabdomyosarcomas (RMS) are highly aggressive tumors that are thought to arise as a consequence of the regulatory disruption of the growth and differentiation of skeletal muscle progenitor cells. Normal myogenesis is characterized by the expression of the myogenic regulatory factor gene family but, despite their expression in RMS, these tumor cells fail to complete the latter stages of myogenesis. The RMS cell line RD-A was treated with 12-O-tetradecanoylphorbol-13-acetate to induce differentiation and cultured for 10 days. RNA was extracted on days 1, 3, 6, 8 and 10. A human skeletal muscle cDNA microarray was developed and used to analyze the global gene expression of RMS tumors over the time-course of differentiation. As a comparison, the genes identified were subsequently examined during the differentiated primary human skeletal muscle cultures. Prothymosin alpha (PTMA), and translocase of inner mitochondrial membrane 10 (Tim10), two genes not previously implicated in RMS, showed reduced expression during differentiation. Marked differences in the expression of PTMA and Tim10 were observed during the differentiation of human primary skeletal muscle cells. These results identify several new genes with potential roles in the myogenic arrest present in rhabdomyosarcoma. PTMA expression in RMS biopsy samples might prove to be an effective diagnostic marker for this disease.

Musical arts education in Africa : differentiation, integration and disassociation

By discussing the future challenges to musical arts education in Africa in which local cultural practices are valued, the differences of those historically marginalised by virtue of gender, race, ethnicity, and class, are celebrated. In Africa, musical arts education and culture are regarded as an integral part of our life, which not only embraces the spiritual, material and intellectual aspects of our society, but also contributes greatly toward our emotional development. This affirms the integrity and importance of various forms of 'Art' including literature, technology, design, dance, drama, music, visual art, media and communication.

This paper will discuss the future of African musical arts education programmes through the dynamic cycle of differentiation, integration and disassociation. The authors will consider the concept of ‘differentiation’, ‘integration’ and ‘disassociation’ within musical arts practice. An analysis of selected international arts education programmes provides a globally differentiated perspective through a discipline-based approach. In the African context, arts education programmes are located within an integrated approach. The structure of a Music Action Research Team (MAT cell) in Southern African Developing Community (SADC) countries will be highlighted as a means to address disassociation through the active engagement of professional development programmes offered by the Centre for Indigenous African Instrumental Music and Dance (CIIMDA).

Tyrosine residues of the granulocyte colony-stimulating factor transmit proliferation and differentiation signals in murine bone marrow cells

Granulocyte colony-stimulating factor (G-CSF) is the major regulator of granulopoiesis and acts through binding to its specific receptor (G-CSF-R) on neutrophilic granulocytes. Previous studies of signaling from the 4 G-CSF-R cytoplasmic tyrosine residues used model cell lines that may have idiosyncratic, nonphysiological responses. This study aimed to identify specific signals transmitted by the receptor tyrosine residues in primary myeloid cells. To bypass the presence of endogenous G-CSF-R, a chimeric receptor containing the extracellular domain of the epidermal growth factor receptor in place of the entire extracellular domain of the G-CSF-R was used. A series of chimeric receptors containing tyrosine mutations to phenylalanine, either individually or collectively, was constructed and expressed in primary bone marrow cells from G-CSF-deficient mice. Proliferation and differentiation responses of receptor-expressing bone marrow cells stimulated by epidermal growth factor were measured. An increased 50% effective concentration to stimulus of the receptor Ynull mutant indicated that specific signals from tyrosine residues were required for cell proliferation, particularly at low concentrations of stimulus. Impaired responses by mutant receptors implicated G-CSF-R Y764 in cell proliferation and Y729 in granulocyte differentiation signaling. In addition, different sensitivities to ligand stimulation between mutant receptors indicated that G-CSF-R Y744 and possibly Y729 have an inhibitory role in cell proliferation. STAT activation was not affected by tyrosine mutations, whereas ERK activation appeared to depend, at least in part, on Y764. These observations have suggested novel roles for the G-CSF-R tyrosine residues in primary cells that were not observed previously in studies in cell lines.

Species-specific cell-matrix interactions are essential for differentiation of alveoli like structures and milk gene expression in primary mammary cells of the Cape fur seal (Arctocephalus pusillus pusillus)

Few models are in place for analysis of extreme lactation patterns such as that of the fur seals which are capable of extended down regulation of milk production in the absence of involution. During a 10–12 month lactation period, female fur seals suckle pups on shore for 2–3 days, and then undertake long foraging trips at sea for up to 28 days, resulting in the longest intersuckling bouts recorded. During this time the mammary gland down regulates milk production. We have induced Cape fur seal (Arctocephalus pusillus pusillus) mammary cells in vitro to form mammospheres up to 900 μm in diameter, larger than any of their mammalian counterparts. Mammosphere lumens were shown to form via apoptosis and cells comprising the cellular boundary stained vimentin positive. The Cape fur seal GAPDH gene was cloned and used in RT-PCR as a normalization tool to examine comparative expression of milk protein genes (αS2-casein, β-lactoglobulin and lysozyme C) which were prolactin responsive. Cape fur seal mammary cells were found to be unique; they did not require Matrigel for rapid mammosphere formation and instead deposited their own matrix within 2 days of culture. When grown on Matrigel, cells exhibited branching/stellate morphogenesis highlighting the species-specific nature of cell–matrix interactions during morphological differentiation. Matrix produced in vitro by cells did not support formation of human breast cancer cell line, PMC42 mammospheres. This novel model system will help define the molecular pathways controlling the regulation of milk protein expression and species specific requirements of the extracellular matrix in the cape fur seal.

Differentiation from first principles using spreadsheets

The article demonstrates the ability of spreadsheets to fit a polynomial to a set of discrete points. It is noted that such an ability enables students to not just evaluate a gradient at a single point, but at a whole family of points, which generates the analytical global gradient function of secants without doing any algebraic manipulations. One of the advantages of such an approach is that it enables the class to focus on the concepts being taught, rather than being hindered by the mechanics of trying to factorise a cubic polynomial.