All cells depend on correctly folded proteins for optimal function. A central question in cellular biology is how such folded structures are formed and maintained, a process that is now recognized to rely heavily on a group of proteins called molecular chaperones. Molecular chaperones constitute distinct families of proteins that are ubiquitous and highly conserved from bacteria to humans. They appear to bind nonnative conformations of most, if not all, proteins, thereby preventing their aggregation and subsequent inactivation. The chaperones not only protect newly synthesized proteins during transport and folding, but also serve to maintain the cell in a healthy state during exposure to a multitude of stress conditions. Accordingly, chaperones are expressed constitutively, but their synthesis is further enhanced during stress conditions. Detailed insights into the role of molecular chaperones have come from studies of mitochondrial protein biogenesis, a process in which chaperones act as unfoldases, pulling devices, and foldases. In this review we summarize these developments and further discuss the potential role of chaperones in mitochondrial DNA metabolism and human mitochondrial disease states.
The accumulation of copper over 2 h by normal lymphoid cells and those from Menkes'-disease patients (Menkes' cells) was found to be biphasic, with an initial phase of rapid uptake, an approach to steady state at around 40-60 min, followed by a further accumulation phase. The accumulation of copper was not diminished by the addition of a variety of metabolic inhibitors, suggesting that copper uptake is not an active process. The presence of carbonyl cyanide m-chlorophenylhydrazone in the culture medium stimulated the uptake and accumulation of copper in both normal and Menkes' cells to the same absolute level. This effect appeared to be specific for copper, since the accumulation of Zn and Cd was unaffected. Menkes' cells did not differ from normal in their initial rate of copper uptake. Analysis of the uptake curve suggested that the membrane transport of copper involves both passive and facilitated diffusion. Initial rate of efflux from the cells was approximated by two methods. Menkes' cells did not appear to be affected in this function. It seems likely that the basic defect in Menkes' disease involves a step in intracellular copper transport rather than the membrane transport of copper.
We have developed a short program of problem-based learning (PBL) sessions for third year nutrition science, integrated within a traditional lecture and practical format. This course was designed to develop additional generic skills without losing the benefits of the existing course. The inherent flexibility of problem-based sessions allows the time to both reinforce and expand the original course material. PBL has proved popular with our students, and we have measured a high degree of satisfaction with the format. Many students have requested an extension of the PBL program throughout the year.Keywords: Problem-based learning, course design, integrated courses.The introduction of new teaching philosophies and methodologies often requires considerable curriculum development, staff training, and organization of timetables and facilities [1]. Such a commitment of resources may deter tertiary teachers from developing innovative programs especially where the new course requires co-operation and co-ordination of staff across university departments and faculties. We have developed a small scale approach to problem-based learning that allows incorporation of PBL 1 within a single traditional science subject. Our experience suggests that even small scale programs of PBL are rewarding for both staff and students.Problem-based learning courses offer an alternative mode of teaching that emphasizes development of a different range of skills than is seen in the traditional mix of lectures, practicals, and examinations. Students in traditional university science courses often use a "surface" approach to learning where they concentrate on a superficial understanding of the subject and the memorization of definitions and examples to pass an examination [2]. Despite this, university teachers want their graduates to be independent, creative, and deep thinkers and to develop generic skills common to all disciplines such as analytical thinking, research skills, communication skills, and the ability to work productively in a team. A transfer to "deep" approaches to learning is rewarding for the student and improves general satisfaction with the university experience for both staff and students.However, there are benefits in the traditional teaching model [3]. Staff and students usually have clear expectations of this teaching mode, and teaching resources can be gradually expanded from the existing materials. We have designed a final year multidisciplinary science subject that replaces part of the lecture program with PBL sessions but retains the remainder of the lectures and the existing practical course. Our program is modular allowing staff to gradually join the PBL program as they develop their own components of the course.A MULTIDISCIPLINARY SUBJECT At La Trobe University, the degree of Bachelor of Biological Science (Nutrition) offers two nutrition subjects at final year level that look at aspects of nutrition from a broad range of science disciplines including biochemistry, physiology, pathology, genetics, microbiology, psycho...
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