Mutations of CEP83 Cause Infantile Nephronophthisis and Intellectual Disability

Ciliopathies are a group of hereditary disorders associated with defects in cilia structure and function. The distal appendages (DAPs) of centrioles are involved in the docking and anchoring of the mother centriole to the cellular membrane during ciliogenesis. The molecular composition of DAPs was recently elucidated and mutations in two genes encoding DAPs components (CEP164/NPHP15, SCLT1) have been associated with human ciliopathies, namely nephronophthisis and orofaciodigital syndrome. To identify additional DAP components defective in ciliopathies, we independently performed targeted exon sequencing of 1,221 genes associated with cilia and 5 known DAP protein-encoding genes in 1,255 individuals with a nephronophthisis-related ciliopathy. We thereby detected biallelic mutations in a key component of DAP-encoding gene, CEP83, in seven families. All affected individuals had early-onset nephronophthisis and four out of eight displayed learning disability and/or hydrocephalus. Fibroblasts and tubular renal cells from affected individuals showed an altered DAP composition and ciliary defects. In summary, we have identified mutations in CEP83, another DAP-component-encoding gene, as a cause of infantile nephronophthisis associated with central nervous system abnormalities in half of the individuals.     

Correlation between body size and fatty acid and essential amino acid composition of round goby (Neogobius melanostomus) and monkey goby (Neogobius fluviatilis) from the Rhine River (Germany)

In this study correlations between body size and muscle fatty and amino acid content of two species of goby, round goby (Neogobius melanostomus) and monkey goby (Neogobius fluviatilis) caught from river Rhine (Germany) were investigated. Among saturated fatty acids (SFAs), mono- (MUFA) and polyunsaturated fatty acids (PUFAs) only SFAs were significantly higher in round goby than monkey goby (P < 0.05). In general, the correlation between body size of both gobies and the content of most of the individual fatty acids was not significant. In monkey goby, the content of palmitic acid (C16:0) and oleic acid (C18:1 n-9) was positively correlated with weight (r = 0.43) and total length (r = ?0.58), respectively, and the content of docosahexaenoic acid (DHA) increased with condition factor (r = 0.50). The content of threonine, arginine, valine, phenylalanine and isoleucine in monkey goby was higher than those of round goby (P < 0.05). In round goby the three essential amino acids arginine, valine and leucine were positively (P < 0.05) correlated with body length, which indicates that longer round gobies are of higher nutritional value.     

Active signals,gradient formation and regional specificity in neural induction

The question of how the vertebrate embryo gives rise to a nervous system is of paramount interest in developmental biology. Neural induction constitutes the earliest step in this process and is tightly connected with development of the embryonic body axes. In the Xenopus embryo, perpendicular gradients of BMP and Wnt signals pattern the dorsoventral and anteroposterior body axes. Both pathways need to be inhibited to allow anterior neural induction to occur. FGF8 and IGF are active neural inducers that together with BMP and Wnt signals are integrated at the level of Smad 1/5/8 phosphorylation. Hedgehog (Hh) also contributes to anterior neural induction. Suppressor-of-fused plays an important role in intertwining the Hh and Wnt pathways. Distinct mechanisms are discussed that establish morphogen gradients and integrate retinoic acid and FGF signals during posterior development. These findings not only improve our understanding of regional specification in neural induction, but have profound implications for mammalian stem cell research and regenerative medicine.     

Bioreactors for plant cells: hardware configuration and internal environment optimization as tools for wider commercialization

Mass production of value-added molecules (including native and heterologous therapeutic proteins and enzymes) by plant cell culture has been demonstrated as an efficient alternative to classical technologies [i.e. natural harvest and chemical (semi)synthesis]. Numerous proof-of-concept studies have demonstrated the feasibility of scaling up plant cell culture-based processes (most notably to produce paclitaxel) and several commercial processes have been established so far. The choice of a suitable bioreactor design (or modification of an existing commercially available reactor) and the optimization of its internal environment have been proven as powerful tools toward successful mass production of desired molecules. This review highlights recent progress (mostly in the last 5 years) in hardware configuration and optimization of bioreactor culture conditions for suspended plant cells.     

The Detection of Inherent Homologous Recombination Between Repeat Sequences in H. pylori 26695 by the PCR-Based Method

Helicobacter pylori infects more than half of the world’s population, making it the most widespread infection of bacteria. It has high genetic diversity and has been considered as one of the most variable bacterial species. In the present study, a PCR-based method was used to detect the presence and the relative frequency of homologous recombination between repeat sequences (>500 bp) in H. pylori 26695. All the recombinant structures have been confirmed by sequencing. The inversion generated between inverted repeats showed distinct features from the recombination for duplication or deletion between direct repeats. Meanwhile, we gave the mathematic reasoning of a general formula for the calculation of relative recombination frequency and indicated the conditions for its application. This formula could be extensively applied to detect the frequency of homologous recombination, site-specific recombination, and other types of predictable recombination. Our results should be helpful for better understanding the genome evolution and adaptation of bacteria.     

Identification of a Sphingolipid α-Glucuronosyltransferase That Is Essential for Pollen Function in Arabidopsis

Glycosyl inositol phosphorylceramide (GIPC) sphingolipids are a major class of lipids in fungi, protozoans, and plants. GIPCs are abundant in the plasma membrane in plants, comprising around a quarter of the total lipids in these membranes. Plant GIPCs contain unique glycan decorations that include a conserved glucuronic acid (GlcA) residue and various additional sugars; however, no proteins responsible for glycosylating GIPCs have been identified to date. Here, we show that the Arabidopsis thaliana protein INOSITOL PHOSPHORYLCERAMIDE GLUCURONOSYLTRANSFERASE1 (IPUT1) transfers GlcA from UDP-GlcA to GIPCs. To demonstrate IPUT1 activity, we introduced the IPUT1 gene together with genes for a UDP-glucose dehydrogenase from Arabidopsis and a human UDP-GlcA transporter into a yeast mutant deficient in the endogenous inositol phosphorylceramide (IPC) mannosyltransferase. In this engineered yeast strain, IPUT1 transferred GlcA to IPC. Overexpression or silencing of IPUT1 in Nicotiana benthamiana resulted in an increase or a decrease, respectively, in IPC glucuronosyltransferase activity in vitro. Plants in which IPUT1 was silenced accumulated IPC, the immediate precursor, as well as ceramides and glucosylceramides. Plants overexpressing IPUT1 showed an increased content of GIPCs. Mutations in IPUT1 are not transmitted through pollen, indicating that these sphingolipids are essential in plants.     

Glucose and glutamine metabolism control by APC and SCF during the G1-to-S phase transition of the cell cycle

Recent studies have given us a clue as to how modulations of both metabolic pathways and cyclins by the ubiquitin system influence cell cycle progression. Among these metabolic modulations, an aerobic glycolysis and glutaminolysis represent an initial step for metabolic machinery adaptation. The enzymes 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) and glutaminase-1 (GLS1) maintain a high abundance in glycolytic intermediates (for synthesis of non-essential amino acids, the use of ribose for the synthesis of nucleotides and hexosamine biosynthesis), as well as tricarboxylic acid cycle intermediates (replenishing the loss of mitochondrial citrate), respectively. On the one hand, regulation of these key metabolic enzymes by ubiquitin ligases anaphase-promoting complex/cyclosome (APC/C) and Skp1/cullin/F-box (SCF) has revealed the importance of anaplerosis by both glycolysis and glutaminolysis to overcome the restriction point of the G1 phase by maintaining high levels of glycolytic and glutaminolytic intermediates. On the other hand, only glutaminolytic intermediates are necessary to drive cell growth through the S and G2 phases of the cell cycle. It is interesting to appreciate how this reorganization of the metabolic machinery, which has been observed beyond cellular proliferation, is a crucial determinant of a cell’s decision to proliferate. Here, we explore a unifying view of interactions between the ubiquitin system, metabolic activity, and cyclin-dependent kinase complexes activity during the cell cycle.     

Hrs‐ and CD63‐Dependent Competing Mechanisms Make Different Sized Endosomal Intraluminal Vesicles

Multivesicular endosomes/bodies (MVBs) contain intraluminal vesicles (ILVs) that bud away from the cytoplasm. Multiple mechanisms of ILV formation have been identified, but the relationship between different populations of ILVs and MVBs remains unclear. Here, we show in HeLa cells that different ILV subpopulations can be distinguished by size. EGF stimulation promotes the formation of large ESCRT‐dependent ILVs, whereas depletion of the ESCRT‐0 component, Hrs, promotes the formation of a uniformly sized population of small ILVs, the formation of which requires CD63. CD63 has previously been implicated in ESCRT‐independent sorting of PMEL in MVBs and transfected PMEL is present on the small ILVs that form on Hrs depletion. Upregulation of CD63‐dependent ILV formation by Hrs depletion indicates that Hrs and CD63 regulate competing machineries required for the generation of distinct ILV subpopulations. Taken together our results indicate that ILV size is influenced by their cargo and mechanism of formation and suggest a competitive relationship between ESCRT‐dependent and ‐independent mechanisms of ILV formation within single MVBs.