Cell-type-specific responses to the microbiota across all tissues of the larval zebrafish.

Animal development proceeds in the presence of intimate microbial associations, but the extent to which different host cells across the body respond to resident microbes remains to be fully explored. Using the vertebrate model organism, the larval zebrafish, we assessed transcriptional responses to the microbiota across the entire body at single-cell resolution. We find that cell types across the body, not limited to tissues at host-microbe interfaces, respond to the microbiota.

The microbiota promotes social behavior by modulating microglial remodeling of forebrain neurons.

Host-associated microbiotas guide the trajectory of developmental programs, and altered microbiota composition is linked to neurodevelopmental conditions such as autism spectrum disorder. Recent work suggests that microbiotas modulate behavioral phenotypes associated with these disorders. We discovered that the zebrafish microbiota is required for normal social behavior and reveal a molecular pathway linking the microbiota, microglial remodeling of neural circuits, and social behavior in this experimentally tractable model vertebrate.

BefA, a microbiota-secreted membrane disrupter, disseminates to the pancreas and increases β cell mass.

Microbiome dysbiosis is a feature of diabetes, but how microbial products influence insulin production is poorly understood. We report the mechanism of BefA, a microbiome-derived protein that increases proliferation of insulin-producing β cells during development in gnotobiotic zebrafish and mice. BefA disseminates systemically by multiple anatomic routes to act directly on pancreatic islets.

The SARS-CoV-2 receptor and other key components of the Renin-Angiotensin-Aldosterone System related to COVID-19 are expressed in enterocytes in larval zebrafish.

People with underlying conditions, including hypertension, obesity, and diabetes, are especially susceptible to negative outcomes after infection with coronavirus SARS-CoV-2, which causes COVID-19. Hypertension and respiratory inflammation are exacerbated by the Renin-Angiotensin-Aldosterone System (RAAS), which normally protects from rapidly dropping blood pressure via Angiotensin II (Ang II) produced by the enzyme Ace. The Ace paralog Ace2 degrades Ang II, counteracting its chronic effects, and serves as the SARS-CoV-2 receptor.

Gait Deficits and Loss of Striatal Tyrosine Hydroxlase/Trk-B are Restored Following 7,8-Dihydroxyflavone Treatment in a Progressive MPTP Mouse Model of Parkinson's Disease.

Parkinson's disease (PD) is caused by neurodegeneration of nigrostriatal neurons, resulting in dopamine (DA) stimulated motor deficits. Like brain derived neurotrophic factor (BDNF), 7,8-dihydroxyflavone (DHF) is an agonist of the tropomyosin receptor kinase-B (TrkB) and stimulates the same secondary cascades that promote neuronal growth, survival and differentiation. We used our progressive mouse model of PD by administering increasing doses of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) over 4 weeks (5 days/week), and then treated mice with DHF for 4 weeks after the cessation of the toxin injections (i.

Packing in the Proteins.

In this issue of Developmental Cell, Park et al. (2019) demonstrate that specialized enterocytes of the developing vertebrate intestine are equipped with a broad-spectrum protein absorption machinery to meet animals' nutritional needs through intracellular protein digestion while simultaneously allowing important immune and developmental proteins to traverse the lumen unscathed.

Evolving in a Microbial Soup: You Are What They Eat.

Animal and plant developmental programs are genetically encoded but shaped by evolutionary histories with microbes. Recently published work demonstrates how variation in host iron and glucose levels alters interactions with an enteric pathogen from deadly to benign, highlighting how bacteria impose constraints on tissue properties and their developmental trajectories.