As described in Nature Neuroscience, researchers at the Allen Institute for Brain Science have created a detailed taxonomy of cells in the mouse visual cortex based on single-cell gene expression and identified 49 distinct cell types in the largest collection of individual adult cortical neurons characterized by gene expression published to date.

“Studying any system requires knowing what the system is made of,” says Bosiljka Tasic, Ph.D., assistant investigator at the Allen Institute for Brain Science. “There are many ways to define the brain’s cellular building blocks. Our approach was to look at all the genes that are expressed in individual cells in the mouse visual cortex and use that information to classify the cells.”

The researchers isolated single cells from the adult mouse brain and obtained genome-wide gene expression data from these individual cells. Each cell expresses thousands of genes, making the cell classification problem an enormous computational task.

“Initially, the problem of classifying cells is like sorting Skittles in the dark,” says Vilas Menon, scientist II at the Allen Institute for Brain Science. “With single-cell gene expression data, we get the equivalent of color, or type, information, but we still have to extract it from the large-scale data set. Ultimately, we wanted to figure out how many types there were in an unbiased, data-driven way.”

The researchers used computational dimension reduction techniques, which collapse genes with similar expression patterns into gene sets. When single cells were analyzed by clustering in this lower-dimensional space, 49 distinct groups appeared based on unique combinations of genes they express, including 42 neuronal cell types and 7 non-neuronal types.

“Having this kind of objective analysis of cell types in this region of the brain is a basic piece of understanding we need, and provides a baseline for looking at other regions of the mouse brain and also at the human brain,” says Christof Koch, Ph.D., President and Chief Scientific Officer at the Allen Institute for Brain Science.

“Categorizing the cells in visual cortex into these distinct types that are marked by specific genes will enable us to begin to understand what these cells and types do in the brain,” says Hongkui Zeng, Ph.D., Investigator of Cell and Circuit Genetics at the Allen Institute for Brain Science. “Next, we can investigate how gene expression correlates with the anatomical, physiological and functional properties of the cells, how these cell types are connected with each other, and how they work together to process and make sense of the visual information the brain receives from the outside world. This will ultimately shed light on the inner workings of the brain.”

Humans—as well as animals and other species—have always had an on-again/off-again relationship with lipids and fats. Cholesterol, for example, is essential for health, but too much of it, can lead to death. New research from Brown University reinforces how this might be true.
While working on nematodes and mice, researchers discovered a naturally occurring protein that moves fats such as cholesterol around the body also compromises essential functions in cells that extends life.

However, the study also shows that nematodes lived up to 40 percent longer when Brown University researchers genetically blocked production of the worms’ yolk lipoprotein, known as vitellogenin (VIT).

“Protein [known as apolipoprotein B (apoB)], which has an ortholog [genes inherited from ancestors] in humans, is a major decider of what happens to fat inside intestinal cells,” said Louis Lapierre, assistant professor of molecular biology, cell biology and biochemistry at Brown University and senior author of the study in the journal Autophagy. “If you reduce the production of these lipoproteins, you allow the fat to be reused in different ways.”

The human gut has over 100 trillion microorganisms, and, according to a recent study published in Immunology and Cell Biology, exercising at a young age can change this microbial community to promote a healthier brain and metabolic activity over a person’s lifetime.

The research, conducted by the University of Colorado Boulder, shows that a window of opportunity exists during early human development to improve health over the long term.
Science Daily published the following quote from Monika Fleshner, the senior author of the new study and a professor in CU-Boulder’s Department of Integrative Physiology: “Exercise affects many aspects of health, both metabolic and mental, and people are only now starting to look at the plasticity of these gut microbes. That is one of the novel aspects of this research.”

A recent study, published in the online version of The Journal of Neurophysiology, has unveiled the first complete model that details the role of serotonin in brain development and structure. The goal for researchers at the Case Western Reserve University School of Medicine was to close the existing knowledge gap on role of serotonin in the brain cortex—especially as it pertains to brain circuitry, electrical activity and function.

“For the first time, we can provide a complete description of an animal model from genes to behavior—including at the level of neuronal network activity, which has been ignored in most studies to date,” said Roberto Fernández Galán, PhD, Assistant Professor in the Department of Neurosciences at Case Western Reserve University School of Medicine.

Serotonin, also known as 5-hydroxytryptamine [5-HT], is a vital neuromodulator of brain development as well as the structure and function of neuronal (nerve cell) circuits.