Regulation of the G2/M Transition in Rodent Oocytes

Regulation of maturation in meiotically competent mammalian oocytes is a complex process involving the carefully coordinated exchange of signals between the somatic and germ cell compartments of the ovarian follicle via paracrine and cell–cell coupling pathways. This review highlights recent advances in our understanding of how such signaling controls both meiotic arrest and gonadotropin-triggered meiotic resumption in competent oocytes and relates them to the historical context. Emphasis will be on rodent systems, where many of these new findings have taken place. A regulatory scheme is then proposed that integrates this information into an overall framework for meiotic regulation that demonstrates the complex interplay between different follicular compartments

Playing in a virtual bedroom: youth leisure in the Facebook generation

The rapidly changing uses of online social networking sites (SNS) have led to moral panics, most notably framed in terms of 'stranger danger'. However, the risks to young people from access to un-mediated content available via SNS, and most particularly to user-generated content is not generally seen as being dangerous. However, adults would not generally consider many of the activities engaged in via SNS as safe were they conducted in the real world. This paper explores the ways in which young people use SNS to mediate complex issues of social identity in a virtual environment

Face of the Future

Paul Oh, robotics visionary, believes Nevada is poised to become the nation’s premier destination for all manner of “unmanned systems,” those technological marvels that are rapidly redrawing the boundaries between man and machine

Mouse versus Rat: Profound Differences in Meiotic Regulation at the Level of the Isolated Oocyte

Cumulus cell-enclosed oocytes (CEO), denuded oocytes (DO), or dissected follicles were obtained 44–48 hr after priming immature mice (20–23 days old) with 5 IU or immature rats (25–27 days old) with 12.5 IU of equine chorionic gonadotropin, and exposed to a variety of culture conditions. Mouse oocytes were more effectively maintained in meiotic arrest by hypoxanthine, dbcAMP, IBMX, milrinone, and 8-Br-cGMP. Atrial natriuretic peptide, a guanylate cyclase activator, suppressed maturation in CEO from both species, but mycophenolic acid reversed IBMX-maintained meiotic arrest in mouse CEO with little activity in rat CEO. IBMX-arrested mouse, but not rat, CEO were induced to undergo germinal vesicle breakdown (GVB) by follicle-stimulating hormone (FSH) and amphiregulin, while human chorionic gonadotropin (hCG) was ineffective in both species. Nevertheless, FSH and amphiregulin stimulated cumulus expansion in both species. FSH and hCG were both effective inducers of GVB in cultured mouse and rat follicles while amphiregulin was stimulatory only in mouse follicles. Changing the culture medium or altering macromolecular supplementation had no effect on FSH-induced maturation in rat CEO. The AMP-activated protein kinase (AMPK) activator, AICAR, was a potent stimulator of maturation in mouse CEO and DO, but only marginally stimulatory in rat CEO and ineffective in rat DO. The AMPK inhibitor, compound C, blocked meiotic induction more effectively in hCG-treated mouse follicles and heat-treated mouse CEO. Both agents produced contrasting results on polar body formation in cultured CEO in the two species. Active AMPK was detected in germinal vesicles of immature mouse, but not rat, oocytes prior to hCG-induced maturation in vivo; it colocalized with chromatin after GVB in rat and mouse oocytes, but did not appear at the spindle poles in rat oocytes as it did in mouse oocytes. Finally, cultured mouse and rat CEO displayed disparate maturation responses to energy substrate manipulation. These data highlight significant differences in meiotic regulation between the two species, and demonstrate a greater potential in mice for control at the level of the cumulus CEO

Classics in Science

In common with most readers, excepting the fanatical culture seekers, the concept of a list of "great books, " which every educated man or woman must read, strikes me as dreary and dull. Despite Robert Hutchins 1 and Clifton Fadiman's exhortations, nothing could induce me to wade through such sleep-producers as a majority of the titles urged upon us in The Lifetime Reading Plan and the Great Books Foundation list. Far more rewarding, significant, and exciting, in my view, is to try to single out those books that over the centuries have made the most profound impact on the history, economics, culture, civilization, and science of our time. Admittedly, some works of prime importance are intangible in their influence. That is especially true in such fields as literature, philosophy, and religion. Most measurable in their effect are certain seminal works in sciencethe trail-blazers, creating new frontiers, often dramatically extending man's knowledge of the visible and invisible universe around him. Often these books represent the culmination of the efforts of many minds. William Harvey on blood circulation built upon the researches of sixteenthcentury anatomists and physiologists; Linneaus came at the end of two centuries of systems of classifying plants. Sir Isaac Newton, after acknowledging his indebtedness to Copernicus, Kepler, Galileo, and other predecessors, remarked, "If I have seen further than other men, it is by standing on the shoulders of giants."published or submitted for publicatio

Transpirationally cooled heat ablation system Patent

Transpirationally cooled heat ablation system for interplanetary spacecraft reentry shieldin

Improving teaching and learning for chemical equilibrium and acids and bases in Year 12 chemistry : a thesis submitted in partial fulfilment of the requirements for the degree of MAster of Education at Massey University, Palmerston North, New Zealand

The aims of this action research study were to develop, implement, and test the efficacy of four strategies designed to improve the teaching and learning of chemical equilibrium and acids and bases in year 12 chemistry. The study took place in a New Zealand secondary school, with two year 12 chemistry teachers and fifteen randomly selected students taking part. Semi-structured interviews used to elicit students' pre-teaching mental models of concepts within chemical equilibrium and acids and bases revealed a range of misconceptions and a limited ability to represent the sub-microscopic level of chemistry concepts. Teachers then used information from the interviews to inform the planning of lessons for each topic. The new teaching strategies employed by the teachers centred around Johnstone's three levels of chemistry; using a macroscopic, sub-microscopic, symbolic sequence during teacher explanations of concepts. Particular emphasis was placed on modelling the sub-microscopic level of each concept with magnetic cardboard dots and student role plays. The action research process allows teachers to improve their own understandings and teaching practices through cycles of planning, action, observation and reflection. Although the action research methodology used here was new to both teachers at the start of the study, it provided a useful structure in which to trial the new strategies. Reflection in action research is an opportunity for teachers to reflect on, and evaluate, the effects of their action. This study demonstrates that understanding of concepts within chemical equilibrium and acids and bases is significantly improved if the sub-microscopic level of concepts is represented. For the students in this study, the preferred method of representing the sub-microscopic level was with cardboard dots rather than student role plays. Ideally, students themselves need to practise representing the sub-microscopic level with cardboard dots or other concrete models if they are to gain better understanding of the sub-microscopic level

Perturbing Microtubule Integrity Blocks AMP-Activated Protein Kinase-Induced Meiotic Resumption in Cultured Mouse Oocytes

The oocyte meiotic spindle is comprised of microtubules (MT) that bind chromatin and regulate both metaphase plate formation and karyokinesis during meiotic maturation; however, little information is known about their role in meiosis reinitiation. This study was conducted to determine if microtubule integrity is required for meiotic induction and to ascertain how it affects activation of AMP-activated protein kinase (AMPK), an important participant in the meiotic induction process. Treatment with microtubule-disrupting agents nocodazole and vinblastine suppressed meiotic resumption in a dose-dependent manner in both arrested cumulus cell-enclosed oocytes (CEO) stimulated with follicle-stimulating hormone (FSH) and arrested denuded oocytes (DO) stimulated with the AMPK activator, 5-aminoimidazole-4-carboxamide-1-beta-4-ribofuranoside (AICAR). This effect coincided with suppression of AMPK activation as determined by western blotting and germinal vesicle immunostaining. Treatment with the MT stabilizer paclitaxel also suppressed meiotic induction. Targeting actin filament polymerization had only a marginal effect on meiotic induction. Immunolocalization experiments revealed that active I and II stages, while it localized at the spindle midzone during anaphase. This discrete localization pattern was dependent on MT integrity. Treatment with nocodazole led to disruption of proper spindle pole localization of active AMPK, while paclitaxel induced excessive polymerization of spindle MT and formation of ectopic asters with accentuated AMPK colocalization. Although stimulation of AMPK increased the rate of germinal vesicle breakdown (GVB), spindle formation and polar body (PB) extrusion, the kinase had no effect on peripheral movement of the spindle. These data suggest that themeiosis-inducing action and localization of AMPK are regulated byMT spindle integrity during mouse oocyte maturation