Differences in erythropoiesis in normal chicken and quail embryos

Summary Using antibodies against the fetal and adult forms of - and -globin, it has been shown that erythropoiesis in the para-aortic foci (PAF) constitutes a major species-specific difference between chicken and quail embryos. In quail embryos, para-aortic foci are rare, small and rather heterogeneous with regard to their erythropoietic and haemopoietic cell composition. In contrast, the PAFs in chicken embryos are abundant and consist of large numbers of erythropoietic cells.In both species a time difference (approximately 1 day) is observed between the first expression of the fetal - and -globin and the adult - and -globin in erythropoietic cells. Adult erythropoiesis in both species can be detected first in the stalk of the yolk sac; this is similar to the situation in mammalian and amphibian species. From this time onward the number of circulating adult erythrocytes increases steadily. Whereas in chicken, large intraembryonic foci that can serve as sources for these adult cells arise concomitantly, no such foci can be detected in quail embryos, suggesting that the quail yolk sac is a major source for these adult red blood cells.     

19F Nuclear Magnetic Resonance as a Tool To Investigate Microbial Degradation of Fluorophenols to Fluorocatechols and Fluoromuconates

A method was developed to study the biodegradation and oxidative biodehalogenation of fluorinated phenols by ¹⁹F nuclear magnetic resonance (NMR). Characterization of the ¹⁹F NMR spectra of metabolite profiles of a series of fluorophenols, converted by purified phenol hydroxylase, catechol 1,2-dioxygenase, and/or by the yeast-like fungus Exophiala jeanselmei, provided possibilities for identification of the ¹⁹F NMR chemical shift values of fluorinated catechol and muconate metabolites. As an example, the ¹⁹F NMR method thus defined was used to characterize the time-dependent metabolite profiles of various halophenols in either cell extracts or in incubations with whole cells of E. jeanselmei. The results obtained for these two systems are similar, except for the level of muconates observed. Altogether, the results of the present study describe a ¹⁹F NMR method which provides an efficient tool for elucidating the metabolic pathways for conversion of fluorine-containing phenols by microorganisms, with special emphasis on possibilities for biodehalogenation and detection of the type of fluorocatechols and fluoromuconates involved. In addition, the method provides possibilities for studying metabolic pathways in vivo in whole cells.     

Sialylation of Campylobacter jejuni lipo-oligosaccharides: impact on phagocytosis and cytokine production in mice

Background

Guillain-Barré syndrome (GBS) is a post-infectious polyradiculoneuropathy, frequently associated with antecedent Campylobacter jejuni (C. jejuni) infection. The presence of sialic acid on C. jejuni lipo-oligosaccharide (LOS) is considered a risk factor for development of GBS as it crucially determines the structural homology between LOS and gangliosides, explaining the induction of cross-reactive neurotoxic antibodies. Sialylated C. jejuni are recognised by TLR4 and sialoadhesin; however, the functional implications of these interactions in vivo are unknown.

Methodology/Principal Findings

In this study we investigated the effects of bacterial sialylation on phagocytosis and cytokine secretion by mouse myeloid cells in vitro and in vivo. Using fluorescently labelled GM1a/GD1a ganglioside-mimicking C. jejuni strains and corresponding (Cst-II-mutant) control strains lacking sialic acid, we show that sialylated C. jejuni was more efficiently phagocytosed in vitro by BM-MΦ, but not by BM-DC. In addition, LOS sialylation increased the production of IL-10, IL-6 and IFN-β by both BM-MΦ and BM-DC. Subsequent in vivo experiments revealed that sialylation augmented the deposition of fluorescent bacteria in splenic DC, but not macrophages. In addition, sialylation significantly amplified the production of type I interferons, which was independent of pDC.

Conclusions/Significance

These results identify novel immune stimulatory effects of C. jejuni sialylation, which may be important in inducing cross-reactive humoral responses that cause GBS.     

CDKL5 regulates flagellar length and localizes to the base of the flagella in Chlamydomonas

The length of Chlamydomonas flagella is tightly regulated. Mutations in four genes—LF1, LF2, LF3, and LF4—cause cells to assemble flagella up to three times wild-type length. LF2 and LF4 encode protein kinases. Here we describe a new gene, LF5, in which null mutations cause cells to assemble flagella of excess length. The LF5 gene encodes a protein kinase very similar in sequence to the protein kinase CDKL5. In humans, mutations in this kinase cause a severe form of juvenile epilepsy. The LF5 protein localizes to a unique location: the proximal 1 μm of the flagella. The proximal localization of the LF5 protein is lost when genes that make up the proteins in the cytoplasmic length regulatory complex (LRC)—LF1, LF2, and LF3—are mutated. In these mutants LF5p becomes localized either at the distal tip of the flagella or along the flagellar length, indicating that length regulation involves, at least in part, control of LF5p localization by the LRC.     

The novel retinoid AHPN/CD437 induces a rapid but incomplete apoptotic response in human myeloma cells

The synthetic retinoid 6-[3-(1-adamantyl)-4-hydroxyphenyl]-2-naphthalene carboxylic acid (AHPN/CD437) appears to possess an apoptotic activity superior to classical retinoids in vitro as in vivo. Numerous studies have shown that CD437-induced apoptosis is independent of its nuclear receptor activity, suggesting that CD437 might have a unique mechanism of action. The purpose of this study was to compare CD437- and all-trans retinoic acid (atRA)-induced cell death. CD437 provoked a rapid apoptotic phenotype immediately followed by secondary necrosis in RPMI 8226, U266 and L363 human myeloma cell lines. Nuclear apoptotic features were observed upon both CD437 and atRA treatments. In contrast, membrane blebbing and the subsequent formation of apoptotic bodies, a classical apoptotic event, was only observed upon atRA treatment. In addition, CD437, contrary to atRA, was unable to induce tissue transglutaminase (tTG), an intracellular enzyme involved in the formation of cross-linked protein polymers contributing to apoptotic morphological changes. Taken together, these data suggest that CD437 induces rapid but incomplete apoptotic phenotype in human myeloma cells.     

Introducing fluorescence resonance energy transfer‐based biosensors for the analysis of cAMP‐PKA signalling in the fungal pathogen Candida glabrata

The cyclic adenosine monophosphate‐protein kinase A (cAMP‐PKA) pathway is central to signal transduction in many organisms. In pathogenic fungi such as Candida albicans, this signalling cascade has proven to be involved in several processes, such as virulence, indicating its potential importance in antifungal drug discovery. Candida glabrata is an upcoming pathogen of the same species, yet information regarding the role of cAMP‐PKA signalling in virulence is largely lacking. To enable efficient monitoring of cAMP‐PKA activity in this pathogen, we here present the usage of two FRET‐based biosensors. Both variations in the activity of PKA and the quantity of cAMP can be detected in a time‐resolved manner, as we exemplify by glucose‐induced activation of the pathway. We also present information on how to adequately process and analyse the data in a mathematically correct and physiologically relevant manner. These sensors will be of great benefit for scientists interested in linking the cAMP‐PKA signalling cascade to downstream processes, such as virulence, possibly in a host environment.     

Brown adipose tissue functions in humans

Human adults have functionally active BAT. The metabolic function can be reliably measured in vivo using modern imaging modalities (namely PET/CT). Cold seems to be one of the most potent stimulators of BAT metabolic activity but other stimulators (for example insulin) are actively studied. Obesity is related to lower metabolic activity of BAT but it may be reversed after successful weight reduction such as after bariatric surgery. This article is part of a Special Issue entitled Brown and White Fat: From Signaling to Disease.     

Genetical metabolomics of flavonoid biosynthesis in Populus: a case study

Genetical metabolomics [metabolite profiling combined with quantitative trait locus (QTL) analysis] has been proposed as a new tool to identify loci that control metabolite abundances. This concept was evaluated in a case study with the model tree Populus. Using HPLC, the peak abundances were analyzed of 15 closely related flavonoids present in apical tissues of two full-sib poplar families, Populus deltoides cv. S9-2 x P. nigra cv. Ghoy and P. deltoides cv. S9-2 x P. trichocarpa cv. V24, and correlation and QTL analysis were used to detect flux control points in flavonoid biosynthesis. Four robust metabolite quantitative trait loci (mQTL), associated with rate-limiting steps in flavonoid biosynthesis, were mapped. Each mQTL was involved in the flux control to one or two flavonoids. Based on the identities of the affected metabolites and the flavonoid pathway structure, a tentative function was assigned to three of these mQTL, and the corresponding candidate genes were mapped. The data indicate that the combination of metabolite profiling with QTL analysis is a valuable tool to identify control points in a complex metabolic pathway of closely related compounds.