Active movements of the chromosomes may be needed in the process, where homologous chromosomes find each other during the meiotic pairing. Because the components of the cytoskeleton are generally believed to be responsible for all movements in living nonmuscle cells, we have analyzed the regulation of the movements of zygotene chromosomes in the male rat by using specific inhibitors of the assembly of the various components of the cytoskeleton. --Colcemid, an inhibitor of microtubule formation, completely inhibited the chromosome movements in vitro at a concentration of 1 microgram/ml. This was associated with a damage of the nuclear envelope revealed by the electron microscopic analysis. Another inhibitor of microtubule formation, vinblastine, was ineffective below the level of general toxicity (100 microgram/ml). A specific microfilament inhibitor, cytochalasin B was similarly ineffective. --The findings suggest the presence of a specific colcemid-sensitive mechanism in the nuclear envelope of the zygotene spermatocytes, which regulates the movements of the chromosomes during meiotic pairing.
Tensions between the well-being of present humans, future humans, and nonhuman nature manifest in social protests and political and academic debates over the future of Earth. The increasing consumption of natural resources no longer increases, let alone equalises, human well-being, but has led to the current ecological crisis. While the crisis has been acknowledged, it is often approached in human-centred terms, with framings that limit the moral worth of nonhuman nature to its contribution to human well-being. We derive and propose the concept of planetary well-being to recognise the moral considerability of both human and nonhuman well-being, and to promote transdisciplinary, cross-cultural discourse for addressing ecological and social crises and for promoting societal and cultural transformation. Conceptually, we shift focus in well-being from individuals to Earth system and ecosystem processes that underlie all well-being. Planetary well-being is a state where the integrity of Earth system and ecosystem processes remains unimpaired to a degree that species and populations can persist to the future and organisms have the opportunity to achieve well-being. After grounding and introducing planetary well-being, we shortly discuss how it can be measured and reflect upon its potential as a bridging concept between different worldviews.
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