A deficiency screen of the 3rd chromosome for dominant modifiers of the Drosophila ER integral membrane protein, Jagunal

The mechanism surrounding chromosome inheritance during cell division has been well documented, however, organelle inheritance during mitosis is less understood. Recently, the endoplasmic reticulum (ER) has been shown to reorganize during mitosis, dividing asymmetrically in proneuronal cells prior to cell fate selection, indicating a programmed mechanism of inheritance. ER asymmetric partitioning in proneural cells relies on the highly conserved ER integral membrane protein, Jagunal (Jagn). Knockdown of Jagn in the compound Drosophila eye displays a pleotropic rough eye phenotype in 48% of the progeny. To identify genes involved in Jagn dependent ER partitioning pathway, we performed a dominant modifier screen of the 3rd chromosome for enhancers and suppressors of this Jagn-RNAi-induced rough eye phenotype. We screened through 181 deficiency lines covering the 3L and 3R chromosomes and identified 12 suppressors and 10 enhancers of the Jagn-RNAi phenotype. Based on the functions of the genes covered by the deficiencies, we identified genes that displayed a suppression or enhancement of the Jagn-RNAi phenotype. These include Division Abnormally Delayed (Dally), a heparan sulfate proteoglycan, the γ-secretase subunit Presenilin, and the ER resident protein Sec63. Based on our understanding of the function of these targets, there is a connection between Jagn and the Notch signaling pathway. Further studies will elucidate the role of Jagn and identified interactors within the mechanisms of ER partitioning during mitosis.

The role of human serum and solution chemistry in fibrinogen peptide-nanoparticle interactions

In living systems, the biomolecules that coat nanoparticles (NPs) alter the NP biological identity and response. Although some biomolecules are more effective in mediating NP stability or biological fate, it is difficult to monitor an individual biomolecule within the complexity of the biota. To understand the dependence of protein-NP interactions on common variations in blood, we have evaluated binding between silica NPs and a model gamma-fibrinogen (GF) peptide. Fibrinogen is commonly identified within the protein corona fingerprint of human serum, but its abundance on the NP varies. To assess the relative importance of human serum and solution conditions, GF peptide and silica NP interactions were evaluated with and without serum across pH, NaCl concentrations, and glucose concentrations. Initial evaluation of the GF peptide and silica NP complexes using circular dichroism and dynamic light scattering show little change in the secondary structure of the peptide and no significant agglomeration of NPs, suggesting peptide-NP complexes are stable across study conditions. Fluorescence anisotropy was used to monitor GF peptide-NP binding. Both with and without serum, binding constants for the gamma-fibrinogen peptide vary significantly upon addition of diluted HS (1:500) and 29 mM sodium chloride. Yet, results indicated that gamma-fibrinogen binding interactions with silica NPs are comparatively insensitive to physiologically relevant pH changes and dramatic increases in glucose concentrations. Results highlight the importance of blood chemistries, which vary across individuals and disease states, in mediating protein corona formation.

Viable bacterial colonization is limited in the human intestine in utero

Mucosal immunity develops in the human fetal intestine by 11–14 weeks gestation, yet whether viable microbes exist in utero and interact with intestinal immunity is unknown. Structures consistent with coccoid bacterial morphology, embedded in fetal meconium were evident before mid-gestation by high-resolution scanning electron microscopy (n=4). Molecular methods indicated extremely low bacterial burden and simple profiles in fetal meconium (n=40 of 50) compared to controls (n=87). A subset of Micrococcaceae-dominated (n=9) meconium associated with proportions of lamina propria PLZF+ CD161+ CD4+ T cells and divergent intestinal epithelial transcriptomes. Fetal Micrococcus luteus was isolated only in the presence of a monocyte feeder cell line. This strain grew on placental hormones, remained viable within fetal antigen presenting cells, exhibited species-specific immunomodulatory capacity and genomic features indicating fetal adaptation. Thus, viable bacteria are highly limited and inconsistently detectable in human fetal meconium at mid-gestation.

Viable bacterial colonization is highly limited in the human intestine in utero

Mucosal immunity develops in the human fetal intestine by 11-14 weeks of gestation, yet whether viable microbes exist in utero and interact with the intestinal immune system is unknown. Bacteria-like morphology was identified in pockets of human fetal meconium at mid-gestation by scanning electron microscopy (n = 4), and a sparse bacterial signal was detected by 16S rRNA sequencing (n = 40 of 50) compared to environmental controls (n = 87). Eighteen taxa were enriched in fetal meconium, with Micrococcaceae (n = 9) and Lactobacillus (n = 6) the most abundant. Fetal intestines dominated by Micrococcaceae exhibited distinct patterns of T cell composition and epithelial transcription. Fetal Micrococcus luteus, isolated only in the presence of monocytes, grew on placental hormones, remained viable within antigen presenting cells, limited inflammation ex vivo and possessed genomic features linked with survival in the fetus. Thus, viable bacteria are highly limited in the fetal intestine at mid-gestation, although strains with immunomodulatory capacity are detected in subsets of specimens.