The major mechanism for generating diversity of neuronal connections beyond their genetic determination is the activity-dependent stabilization and selective elimination of the initially overproduced synapses [Changeux JP, Danchin A (1976) Nature 264:705-712]. The largest number of supranumerary synapses has been recorded in the cerebral cortex of human and nonhuman primates. It is generally accepted that synaptic pruning in the cerebral cortex, including prefrontal areas, occurs at puberty and is completed during early adolescence [Huttenlocher PR, et al. (1979) Brain Res 163:195-205]. In the present study we analyzed synaptic spine density on the dendrites of layer IIIC cortico-cortical and layer V cortico-subcortical projecting pyramidal neurons in a large sample of human prefrontal cortices in subjects ranging in age from newborn to 91 y. We confirm that dendritic spine density in childhood exceeds adult values by two- to threefold and begins to decrease during puberty. However, we also obtained evidence that overproduction and developmental remodeling, including substantial elimination of synaptic spines, continues beyond adolescence and throughout the third decade of life before stabilizing at the adult level. Such an extraordinarily long phase of developmental reorganization of cortical neuronal circuitry has implications for understanding the effect of environmental impact on the development of human cognitive and emotional capacities as well as the late onset of human-specific neuropsychiatric disorders.

https://www.pnas.org/content/pnas/108/32/13281.full.pdf

Extraordinary neoteny of synaptic spines in the human prefrontal cortex

Thematic review series: adipocyte biology. The perilipin family of structural lipid droplet proteins: stabilization of lipid droplets and control of lipolysis.

Yarrowia lipolytica as a model for bio-oil production

Adipose triglyceride lipase and the lipolytic catabolism of cellular fat stores

A genomic comparison of Yarrowia lipolytica and Saccharomyces cerevisiae indicates that the metabolism of Y. lipolytica is oriented toward the glycerol pathway. To redirect carbon flux toward lipid synthesis, the GUT2 gene, which codes for the glycerol-3-phosphate dehydrogenase isomer, was deleted in Y. lipolytica in this study. This Δgut2 mutant strain demonstrated a threefold increase in lipid accumulation compared to the wild-type strain. However, mobilization of lipid reserves occurred after the exit from the exponential phase due to β-oxidation. Y. lipolytica contains six acyl-coenzyme A oxidases (Aox), encoded by the POX1 to POX6 genes, that catalyze the limiting step of peroxisomal β-oxidation. Additional deletion of the POX1 to POX6 genes in the Δgut2 strain led to a fourfold increase in lipid content. The lipid composition of all of the strains tested demonstrated high proportions of FFA. The size and number of the lipid bodies in these strains were shown to be dependent on the lipid composition and accumulation ratio.

Control of Lipid Accumulation in the Yeast Yarrowia lipolytica

Lipid droplets, long-ignored globules inside cells, are earning recognition as possible organelles involved in cholesterol synthesis and much more. (Read more.)

https://science.sciencemag.org/content/sci/311/5765/1232.full.pdf

Great Balls of Fat

This fall, the U.S. Supreme Court will consider whether capital crimes by teenagers under 18 should get the death sentence; the case for leniency is based in part on brain studies.

https://science.sciencemag.org/content/sci/305/5684/596.full.pdf

Crime, Culpability, and the Adolescent Brain

Watching cells as they grow within an organism is changing the way developmental biologists think about life9s earliest events. Advances in imaging over the last few years have researchers eager to tackle what used to be arduous experiments.

https://science.sciencemag.org/content/sci/300/5616/76.full.pdf

Play-by-Play Imaging Rewrites Cells' Rules

PHEROMONE RECEPTIONResearch published online by Science this week ([www.sciencexpress.org][1]) suggests that the default social interaction for mice is to mate; only a scent-based cue from another male inhibits a male's urge to mate and spurs him to fight. The number of genes that control this behavior is precisely one; it encodes the protein TRP2 that sits on the surface of certain olfactory nerves that detect pheromones. The work opens the way for genetic analysis of a number of behaviors that are influenced by pheromones.

 [1]: http://www.sciencexpress.org

Pheromone reception. When in doubt, mice mate rather than hate.

NEUROBIOLOGYNew research in mice suggests that targeting one of the two molecular aggregates gumming up brains with Alzheimer's disease also rids tissue of the other, as long as treatment starts early enough.

Mary Beckman

Papers

Great Balls of Fat

Crime, Culpability, and the Adolescent Brain

Play-by-Play Imaging Rewrites Cells' Rules

Pheromone reception. When in doubt, mice mate rather than hate.

Untangling Alzheimer's by Paring Plaques Bolsters Amyloid Theory