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In Drosophila, gene transcription on the X chromosome in males doubles to match that of both X chromosomes in females. This involves site-specific histone acetylation by the MSL complex, which requires two noncoding RNAs.
The placement of double-stranded breaks involved in meiotic recombination may be influenced by histone modifications and chromatin remodeling. This may help ensure the transmission of diverse recombinant haplotypes to offspring.
Cells undergoing meiosis are unique in many respects (e.g., suppression of the S phase during the second round of cell division). The molecular mechanisms that underlie these critical events are beginning to be understood.
Bacteria, fungi, plants, and animals use similar mechanisms to gauge and regulate cell size and proliferation. But these mechanisms do not always have the same genomic basis.
Microbes (e.g., Wolbachia) can pass from a female host to her progeny, influencing the fitness of both the host and her offspring. These “reproductive parasites” can generate strong selective pressures (e.g., sex-ratio distortion).
Injury to a partner’s genital tract during mating is widespread. It occurs in at least 40 taxa, ranging from fruit flies to humans, and has implications for the evolution of copulation, sexual conflict, and speciation.
The release of vasoactive factors (including arachidonic acid metabolites) from astrocyte endfeet onto blood vessels in the brain plays a key role in regulating cerebral blood flow.
Most mammals—from rodents to primates—exhibit neurogenesis in the adult hippocampus. In wild mammals, the process appears to be stable and fine-tuned to meet the demands of the niche exploited by each species.
During nonassociative learning, an animal learns about a single stimulus or event. Much progress has been made in understanding the biological basis of nonassociative learning from invertebrates, such as the mollusk Aplysia.
During associative learning, an animal mentally links two discrete stimuli or events. Much has been learned about the neural mechanisms of associative learning from invertebrates, particularly the marine mollusk Aplysia.
Chemokines regulate the movement and positioning of innate immune cells at homeostasis and in response to acute inflammation. They also coordinate interactions between the innate and adaptive immune systems.
Group 2 innate lymphoid cells were originally described in the context of antihelminth immunity, but they have emerged as key players at multiple barrier surfaces, including the upper and lower airways, skin, and gut.
One or more regenerative cell types in the brain—neural stem cells, astrocytes, or oligodendrocyte precursor cells—may serve as cell(s) of origin for gliomas.
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