Biology subjects

Pohl, D.

Publications and source records attributed to Pohl, D..

3 recordsLinked to original sources

bioRxiv2024

Longhorn Beetles form Structural Colour Using Calcium Phosphate Biominerals

Brilliant structural colors originating from diverse photonic crystals are found across many phyla, including the striking iridescent colors of beetles and butterflies, produced by three-dimensional photonic crystal structures in the specialized cuticular scales. However, the precise composition of these structures remains largely unknown, although it is key to unravelling colour production mechanisms and morphogenesis. The longhorn beetle Doliops similis displays vibrant green patterns on its otherwise dark elytra. These patterns are formed by arrays of minute scales that encompass a three-dimensional photonic crystal made of orderly packed nanospheres. We found that these nanospheres are composed of carbonated amorphous calcium phosphate biomineral. By accurately parameterizing the structure and calculating the refractive index deduced from the relative fractions of the organic and inorganic phases, we derived reflection wavelengths that match the observed green hue, demonstrating the biominerals role in colour production. Our study further reveals that biomineralization is widespread in the Lamiinae subfamily, with colour diversity achieved through variations in nanosphere size, packing, and composition. This study opens new avenues for developing bioinspired mineral-based optical devices with high refractive indices and defect-resistance, overcoming the shortcomings of current polymer-based designs.

molecular biology↗

bioRxiv2023

Knockdown of Atg1 or Atg18 in adult adipocytes impairs lipophagy and reduces lifespan of fruit flies (Drosophila melanogaster)

Autophagy, a lysosome-based eukaryotic cellular degradation system, has previously been implicated in lifespan regulation in different animal models. In this report, we show that expression of the RNAi transgenes targeting the transcripts of the key autophagy genes such as Atg1 or Atg18 in adult fly muscle or glia does not affect the overall levels of autophagosomes in those tissues and does not change the lifespan of the tested flies, but lifespan reduction phenotype has become apparent when Atg1 RNAi or Atg18 RNAi is expressed in a non-tissue-specific manner through a Tub-Gal4 in adult flies or after lipophagy is eradicated through the knockdown of Atg1 or Atg18 in adult fly adipocytes. Lifespan reduction was also observed when Atg1 or Atg18 was knocked down in adult fly enteroblasts and middle gut stem cells. Over-expression of wildtype Atg1 in adult fly muscle or adipocytes reduces lifespan. High levels of ubiquitinated protein aggregates could be the culprit of the reduced lifespan of Atg1 over-expression flies. Our research data presented here have highlighted the important functions of the key autophagy genes in adult fly adipocytes, enteroblasts, and midgut stem cells for lifespan regulation and their undetermined functions in adult fly muscle and glia. SummaryIn this research, we have demonstrated that the key autophagy genes play important roles in fly lifespan regulation through adult adipose tissues, enteroblasts, and middle gut stem cells.

genetics↗

bioRxiv2018

Microbiota stability in healthy individuals after single-dose lactulose challenge - a randomized controlled study

Background and aimsLactulose is a common food ingredient and widely used as a treatment for constipation or hepatic encephalopathy and a substrate for hydrogen breath tests. Lactulose is fermented by the colon microbiota resulting in the production of hydrogen (H2). H2 is a substrate for enteropathogens including Salmonella Typhimurium (S. Typhimurium) and increased H2 production upon lactulose ingestion might favor the growth of H2-consuming enteropathogens. We aimed to analyze effects of single-dose lactulose ingestion on the growth of intrinsic Escherichia coli (E. coli), which can be efficiently quantified by plating and which share most metabolic requirements with S. Typhimurium.\n\nMethods32 healthy volunteers (18 females, 14 males) were recruited. Participants were randomized for single-dose ingestion of 50 g lactulose or 50 g sucrose (controls). After ingestion, H2 in expiratory air and symptoms were recorded. Stool samples were acquired at days -1, 1 and 14. We analyzed 16S microbiota composition and abundance and characteristics of E. coli isolates.\n\nResultsLactulose ingestion resulted in diarrhea in 14/17 individuals. In 14/17 individuals, H2-levels in expiratory air increased by [≥]20 ppm within 3 hours after lactulose challenge. H2-levels correlated with the number of defecations within 6 hours. E. coli was detectable in feces of all subjects (2 x 102 - 109 CFU/g). However, the number of E. coli colony forming units (CFU) on selective media did not differ between any time point before or after challenge with sucrose or lactulose. The microbiota composition also remained stable upon lactulose exposure.\n\nConclusionIngestion of a single dose of 50 g lactulose does not significantly alter E. coli density in stool samples of healthy volunteers. 50 g lactulose therefore seems unlikely to sufficiently alter growth conditions in the intestine for a significant predisposition to infection with H2-consuming enteropathogens such as S. Typhimurium (www.clinicaltrials.gov NCT02397512).

microbiology↗