BACKGROUND More than 30 million children worldwide suffer from moderate acute malnutrition (MAM). Current treatments have limited effectiveness and much remains unknown about pathogenesis. Children with MAM exhibit perturbed development of their gut microbiota. METHODS Slum-dwelling Bangladeshi children, aged 12 to 18 months, with moderate acute malnutrition (n=124) received a microbiota-directed complementary food (MDCF-2) or an existing ready-to-use supplementary food (RUSF), twice daily for three months followed by a 1-month period of monitoring. We obtained weight-for-length, weight-for-age, and length-for-age Z-scores and mid-upper arm circumference at baseline and fortnightly, through four months. We compared the rate of change of these related phenotypes between baseline and three months, and between baseline and four months. We also measured levels of 4,977 proteins in plasma plus 209 bacterial taxa in fecal samples. RESULTS 118 children completed the intervention (n=59/arm). The rate of change in weight-for-length Z-score (β-WLZ), weight-for-age Z-score, and mid upper arm circumference is consistent with a benefit of MDCF-2 on growth over the course of the study including the one-month follow-up. Receipt of MDCF-2 was linked to the magnitude of change in levels of 70 β-WLZ-positively correlated plasma proteins including mediators of bone growth, neurodevelopment and inflammation (gene set enrichment analysis [GSEA];p<0.001) and the abundances of 23 WLZ-associated bacterial taxa (GSEA;p<0.001). CONCLUSIONS These findings provide support for further clinical investigation of MDCF-2 as a dietary supplement for young children with MAM and provide insight into mechanisms by which this targeted manipulation of microbiota components may be linked to growth. (Supported by the Bill and Melinda Gates Foundation and the NIH; ClinicalTrials.gov identifier: NCT04015999 )
Each individual perceives the world in a unique way, but little is known about the genetic basis of variation in sensory perception. In the fly eye, the random mosaic of color-detecting R7 photoreceptor subtypes is determined by stochastic on/off expression of the transcription factor Spineless (Ss). In a genome-wide association study, we identified a naturally occurring insertion in a regulatory DNA element in ss that lowers the ratio of SsON to SsOFF cells. This change in photoreceptor fates shifts the innate color preference of flies from green to blue. The genetic variant increases the binding affinity for Klumpfuss (Klu), a zinc finger transcriptional repressor that regulates ss expression. Klu is expressed at intermediate levels to determine the normal ratio of SsON to SsOFF cells. Thus, binding site affinity and transcription factor levels are finely tuned to regulate stochastic expression, setting the ratio of alternative fates and ultimately determining color preference.
Purpose One of the interesting features of amyloid tracer Pittsburgh compound B (PiB) is that it generates a signal in the white matter (WM) in both healthy subjects and cognitively impaired individuals. This characteristic gave rise to the possibility that PiB can be used to trace WM pathology. In a group of cognitively healthy elderly, we examined PiB retention in normal-appearing WM (NAWM) and white matter lesions (WML), one of the most common brain pathologies in aging. Methods We segmented WML and NAWM from fluid attenuation inversion recovery (FLAIR) images of 73 subjects (age 61.9±10.0, 71% women). PET-PiB images were corrected for partial volume effects and coregistered to FLAIR images and WM masks. WML and NAWM PiB signals were then extracted. Results PiB retention within WML was lower than in NAWM (p<.001, 14.6% reduction). This was true both for periventricular WML (p<.001, 17.8% reduction) and deep WML (p=.001, 7.5% reduction). Conclusions PiB binding in WM is influenced by the presence of WML, which lower the signal. Our findings add to the growing evidence that PiB can depict WM pathology and prompt further investigations into PiB binding targets in WM.
The Hippo pathway is crucial for not only normal growth and apoptosis but also cell fate specification during development. What controls Hippo pathway activity during cell fate specification is incompletely understood. In this article, we identify the insulator protein BEAF-32 as a regulator of Hippo pathway activity in Drosophila photoreceptor differentiation. Though morphologically uniform, the fly eye is composed of two subtypes of R8 photoreceptor neurons defined by expression of light-detecting Rhodopsin proteins. In one R8 subtype, active Hippo signaling induces Rhodopsin 6 (Rh6) and represses Rhodopsin 5 (Rh5), whereas in the other subtype, inactive Hippo signaling induces Rh5 and represses Rh6. The activity state of the Hippo pathway in R8 cells is determined by the expression of warts, a core pathway kinase, which interacts with the growth regulator melted in a doublenegative feedback loop. We show that BEAF-32 is required for expression of warts and repression of melted. Furthermore, BEAF-32 plays a second role downstream of Warts to induce Rh6 and prevent Rh5 fate. BEAF-32 is dispensable for Warts feedback, indicating that BEAF-32 differentially regulates warts and Rhodopsins. Loss of BEAF-32 does not noticeably impair the functions of the Hippo pathway in eye growth regulation. Our study identifies a context-specific regulator of Hippo pathway activity in post-mitotic neuronal fate, and reveals a developmentally specific role for a broadly expressed insulator protein.
Photoreceptors in the crystalline eye are recruited by receptor tyrosine kinase (RTK)/Ras signaling mediated by Epidermal growth factor receptor (EGFR) and the Sevenless (Sev) receptor. Analyses of an allelic deletion series of the locus, along with a panel of modified genomic rescue transgenes, show that eye patterning depends on both miRNAs. Transcriptional reporter and activity sensor transgenes reveal expression and function of miR-279/996 in non-neural cells of the developing eye. Moreover, mutants exhibit substantial numbers of ectopic photoreceptors, particularly of R7, and cone cell loss. These miRNAs restrict RTK signaling in the eye, since nulls are dominantly suppressed by positive components of the EGFR pathway and enhanced by heterozygosity for an EGFR repressor. miR-279/996 limit photoreceptor recruitment by targeting multiple positive RTK/Ras signaling components that promote photoreceptor/R7 specification. Strikingly, deletion of sufficiently derepresses RTK/Ras signaling so as to rescue a population of R7 cells in R7-specific RTK null mutants and, which otherwise completely lack this cell fate. Altogether, we reveal a rare setting of developmental cell specification that involves substantial miRNA control.
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