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notochord, a dorsal hollow nerve cord and pharyngeal slits.
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The C. elegans embryo is a powerful model system for studying the mechanics of metazoan cell division. Its primary advantage is that the architecture of the syncytial gonad makes it possible to use RNAi to generate oocytes whose cytoplasm is reproducibly (typically >95%) depleted of targeted essential gene products via a process that does not depend exclusively on intrinsic protein turnover. The depleted oocytes can then be analyzed as they attempt their first mitotic division following fertilization. Here we outline the characteristics that contribute to the usefulness of the C. elegans embryo for cell division studies. We provide a timeline for the first embryonic mitosis and highlight some of its key features. We also summarize some of the recent discoveries made using this system, particularly in the areas of nuclear envelope assembly/ dissassembly, centrosome dynamics, formation of the mitotic spindle, kinetochore assembly, chromosome segregation, and cytokinesis.
1. The C. elegans embryo as a system to study cell division
The C. elegans embryo is a powerful model system for studying the mechanics of metazoan cell division. Its primary advantage is that the syncytial gonad makes it possible to use RNA interference (RNAi) to generate oocytes whose cytoplasm is reproducibly (>95%) depleted of targeted essential gene products. Introduction of dsRNA rapidly catalyzes the destruction of the corresponding mRNA in many different systems. However, depletion of pre-existing protein is generally a slow process that depends on the half-life of the targeted protein. In contrast, in the C. elegans gonad, the protein present when the dsRNA is introduced is depleted by the continual packaging of maternal cytoplasm into oocytes (Figure 1). Since depletion relies on the rate of embryo production instead of protein half-life, the kinetics tend to be similar for different targets. By 36-48 hours after introduction of the dsRNA, newly formed oocytes are typically >95% depleted of the target protein.
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Farmers utilize pesticides to help control the thousands of weed species, harmful insects, and plant diseases that can afflict crops, period. ... Pesticides don't only affect food crops though; production of certain fibers and oils would also be affected, as crops like cotton are highly susceptible to pests and disease.
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Both (b) and (c)
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Fats, steroids and waxes are some of the most common types of lipids. Lipids are non-polar hydrocarbons because of the presence of non-polar carbon-carbon and carbon-hydrogen bonds in there structure.
Generally, polar molecules are soluble in water while non-polar molecules are insoluble in water, hence, lipids do not dissolve in water. There non-polarity also makes them a suitable component in the selectively permeable biological cell membrane.
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There are more earthquakes on the West coast of the United States, because the boundaries of the North American, Pacific, and Juan de Fuca tectonic plates are located there. As the edges of the plates slide past or are forced under each other, the movement creates earthquakes
