Clinical findings and cytogenetic analysis of small supernumerary ring chromosomes 7: report of two new cases

Two new patients, mosaic for a small supernumerary ring chromosome 7 are described. There are only seven published reported concerning supernumerary ring chromosome 7 and we reviewed the previously reported cases in an attempt to establish genotype-phenotype correlations, which are particularly important for genetic counselling and clinical genetics. Our first case was a 20 months old girl who was referred for a mild motor developmental delay, an asymmetric facial appearance, a plagiocephaly and a short nose with anteverted nostrils. Our second case was a 9 years old boy who was referred for a IQ at the lower end of the normal range (? 80), obesity, hyperactivity and some dysmorphic features including hypertelorism and down slanting palpebral fissures. In both cases, chromosome analysis after G and R banding and FISH showed a small ring chromosome 7 in respectively 76% and 50% of consecutively scored metaphases. Both ring chromosomes were labelled by FISH using the Williams Syndrome locus probe (Elastin Gene D7S486). Comparison between these two cases and previously published cases allowed to delineate frequent clinical findings. A mild mental retardation was found in the majority of patients. which is an important data for genetic counselling.     

Measurements of plasma membrane potential changes in Saccharomyces cerevisiae cells reveal the importance of the Tok1 channel in membrane potential maintenance

K+ is one of the cations (besides protons) whose transport across the plasma membrane is believed to contribute to the maintenance of membrane potential. To ensure K+ transport, Saccharomyces cerevisiae cells possess several types of active and passive transporters mediating the K+ influx and efflux, respectively. A diS-C3(3) assay was used to compare the contributions of various potassium transporters to the membrane potential changes of S. cerevisiae cells in the exponential growth phase. Altogether, the contributions of six K+ transporters to the maintenance of a stable membrane potential were tested. As confirmed by the observed hyperpolarization of trk1 trk2 deletion strains, the diS-C3(3) assay is a suitable method for comparative studies of the membrane potential of yeast strains differing in the presence/absence of one or more cation transporters. We have shown that the presence of the Tok1 channel strongly influences membrane potential: deletion of the TOK1 gene results in significant plasma membrane depolarization, whereas strains overexpressing the TOK1 gene are hyperpolarized. We have also proved that plasma membrane potential is not the only parameter determining the hygromycin B sensitivity of yeast cells, and that the role of intracellular transporters in protecting against its toxic effects must also be considered.     

Assessment of adenyl residue reactivity within model nucleic acids by surface enhanced Raman spectroscopy

We rank the reactivity of the adenyl residues (A) of model DNA and RNA molecules with electropositive subnano size [Ag]n+ sites as a function of nucleic acid primary sequences and secondary structures and in the presence of biological amounts of Cl- and Na+ or Mg2+ ions. In these conditions A is markedly more reactive than any other nucleic acid bases. A reactivity is higher in ribo (r) than in deoxyribo (d) species [pA>pdA and (pA)n>(pdA)n]. Base pairing decreases A reactivity in corresponding duplexes but much less in r than in d. In linear single and paired dCAG or dGAC loci, base stacking inhibits A reactivity even if A is bulged or mispaired (A.A). dA tracts are highly reactive only when dilution prevents self-association and duplex structures. In d hairpins the solvent-exposed A residues are reactive in CAG and GAC triloops and even more in ATC loops. Among the eight rG1N2R3A4 loops, those bearing a single A (A4) are the least reactive. The solvent-exposed A2 is reactive, but synergistic structural transitions make the initially stacked A residues of any rGNAA loop much more reactive. Mg2+ cross-bridging single strands via phosphates may screen A reactivity. In contrast d duplexes cross-bridging enables "A flipping" much more in rA.U pairs than in dA.T. Mg2+ promotes A reactivity in unpaired strands. For hairpins Mg2+ binding stabilizes the stems, but according to A position in the loops, A reactivity may be abolished, reduced, or enhanced. It is emphasized that not only accessibility but also local flexibility, concerted docking, and cation and anion binding control A reactivity.     

Curcumin treatment prevents increased proteasome and apoptosome activities in rat skeletal muscle during reloading and improves subsequent recovery

Immobilization is characterized by activation of the ubiquitin (Ub)-proteasome-dependent proteolytic system (UPS) and of the mitochondrial apoptotic pathway. Increased oxidative stress and inflammatory response occur in immobilized skeletal muscles. Curcumin exhibits antioxidant and anti-inflammatory properties, blocked proteasome activation in intact animals, and may favor skeletal muscle regeneration. We therefore measured the effects of curcumin on immobilization-induced muscle atrophy and subsequent recovery. Rats were subjected to hindlimb immobilization for 8 days (I8) and allowed to recover for 10 days (R10). Fifty percent of the rats were injected daily with either curcumin or vehicle. Proteolytic and apoptotic pathways were studied in gastrocnemius muscles. Curcumin treatment prevented the enhanced proteasome chymotrypsin-like activity and the trend toward increased caspase-9-associated apoptosome activity at I8 in immobilized muscles. By contrast, the increase of these two activities was blunted by curcumin at R10. Curcumin did not reduce muscle atrophy at I8 but improved muscle recovery at R10 and the cross-sectional area of muscle fibers of immobilized muscles. Curcumin reduced the increased protein levels of Smac/DIABLO induced by immobilization and enhanced the elevation of X-linked inhibitory apoptotic protein levels at R10. Ub-conjugate levels and caspase-3 activity increased at I8 and were normalized at R10 without being affected by curcumin treatment. Altogether, the data show that curcumin treatment improved recovery during reloading. The effect of curcumin during the atrophic phase on proteasome activities may facilitate the initiation of muscle recovery after reloading. These data also suggest that this compound may favor the initial steps of muscle regeneration.     

Performance of ¿VIKIA Malaria Ag Pf/Pan¿ (IMACCESS®), a new malaria rapid diagnostic test for detection of symptomatic malaria infections

ABSTRACT: BACKGROUND: Recently, IMACCESS[REGISTERED SIGN] developed a new malaria test (VIKIA Malaria Ag Pf/Pan[TRADE MARK SIGN]), based on the detection of falciparum malaria (HRP-2) and non-falciparum malaria (aldolase). METHODS: The performance of this new malaria rapid diagnostic test (RDT) was assessed using 1,000 febrile patients seeking malaria treatment in four health centres in Cambodia from August to December 2011. The results of the VIKIA Malaria Ag Pf/Pan were compared with those obtained by microscopy, the CareStart Malaria[TRADE MARK SIGN] RDT (AccessBio[REGISTERED SIGN]) which is currently used in Cambodia, and real-time PCR (as "gold standard"). RESULTS: The best performances of the VIKIA Malaria Ag Pf/Pan[TRADE MARK SIGN] test for detection of both Plasmodium falciparum and non-P. falciparum were with 20--30 min reading times (sensitivity of 93.4% for P. falciparum and 82.8% for non-P. falciparum and specificity of 98.6% for P. falciparum and 98.9% for non-P. falciparum) and were similar to those for the CareStart Malaria[TRADE MARK SIGN] test. CONCLUSIONS: This new RDT performs similarly well as other commercially available tests (especially the CareStart Malaria[TRADE MARK SIGN] test, used as comparator), and conforms to the World Health Organization's recommendations for RDT performance. It is a good alternative tool for the diagnosis of malaria in endemic areas.     

Acyl chains of phospholipase d transphosphatidylation products in Arabidopsis cells: a study using multiple reaction monitoring mass spectrometry

Background

Phospholipases D (PLD) are major components of signalling pathways in plant responses to some stresses and hormones. The product of PLD activity is phosphatidic acid (PA). PAs with different acyl chains do not have the same protein targets, so to understand the signalling role of PLD it is essential to analyze the composition of its PA products in the presence and absence of an elicitor.

Methodology/Principal findings

Potential PLD substrates and products were studied in Arabidopsis thaliana suspension cells treated with or without the hormone salicylic acid (SA). As PA can be produced by enzymes other than PLD, we analyzed phosphatidylbutanol (PBut), which is specifically produced by PLD in the presence of n-butanol. The acyl chain compositions of PBut and the major glycerophospholipids were determined by multiple reaction monitoring (MRM) mass spectrometry. PBut profiles of untreated cells or cells treated with SA show an over-representation of 160/18∶2- and 16∶0/18∶3-species compared to those of phosphatidylcholine and phosphatidylethanolamine either from bulk lipid extracts or from purified membrane fractions. When microsomal PLDs were used in in vitro assays, the resulting PBut profile matched exactly that of the substrate provided. Therefore there is a mismatch between the acyl chain compositions of putative substrates and the in vivo products of PLDs that is unlikely to reflect any selectivity of PLDs for the acyl chains of substrates.

Conclusions

MRM mass spectrometry is a reliable technique to analyze PLD products. Our results suggest that PLD action in response to SA is not due to the production of a stress-specific molecular species, but that the level of PLD products per se is important. The over-representation of 160/18∶2- and 16∶0/18∶3-species in PLD products when compared to putative substrates might be related to a regulatory role of the heterogeneous distribution of glycerophospholipids in membrane sub-domains.     

Endocytosis by Numb breaks Notch symmetry at cytokinesis

Cell-fate diversity can be generated by the unequal segregation of the Notch regulator Numb at mitosis in both vertebrates and invertebrates. Whereas the mechanisms underlying unequal inheritance of Numb are understood, how Numb antagonizes Notch has remained unsolved. Live imaging of Notch in sensory organ precursor cells revealed that nuclear Notch is detected at cytokinesis in the daughter cell that does not inherit Numb. Numb and Sanpodo act together to regulate Notch trafficking and establish directional Notch signalling at cytokinesis. We propose that unequal segregation of Numb results in increased endocytosis in one daughter cell, hence asymmetry of Notch at the cytokinetic furrow, directional signalling and binary fate choice.     

BICARBONATE STIMULATION OF CALCIFICATION AND PHOTOSYNTHESIS IN TWO HERMATYPIC CORALS1

A wide range of bicarbonate concentrations was used to monitor the kinetics of bicarbonate (HCO₃^?) use in both photosynthesis and calcification in two reef‐building corals, Porites porites and Acropora sp. Experiments carried out close to the P. porites collection site in Barbados showed that additions of NaHCO₃ to synthetic seawater proportionally increased the calcification rate of this coral until the concentration exceeded three times that of seawater (6 mM). Photosynthetic rates were also stimulated by HCO₃^? addition, but these became saturated at a lower concentration (4 mM). Similar experiments on aquarium‐acclimated colonies of Indo‐Pacific Acropora sp. showed that calcification and photosynthesis in this coral were enhanced to an even greater extent than P. porites, with calcification continuing to increase above 8 mM HCO₃^?, and photosynthesis saturating at 6 mM. Calcification rates of Acropora sp. were also monitored in the dark, and, although these were lower than in the light for a given HCO₃^? concentration, they still increased dramatically with HCO₃^? addition, showing that calcification in this coral is light stimulated but not light dependent.     

The ubiquitin-proteasome and the mitochondria-associated apoptotic pathways are sequentially downregulated during recovery after immobilization-induced muscle atrophy

Immobilization produces morphological, physiological, and biochemical alterations in skeletal muscle leading to muscle atrophy and long periods of recovery. Muscle atrophy during disuse results from an imbalance between protein synthesis and proteolysis but also between apoptosis and regeneration processes. This work aimed to characterize the mechanisms underlying muscle atrophy and recovery following immobilization by studying the regulation of the mitochondria-associated apoptotic and the ubiquitin-proteasome-dependent proteolytic pathways. Animals were subjected to hindlimb immobilization for 4-8 days (I4 to I8) and allowed to recover after cast removal for 10-40 days (R10 to R40). Soleus and gastrocnemius muscles atrophied from I4 to I8 to a greater extent than extensor digitorum longus and tibialis anterior muscles. Gastrocnemius muscle atrophy was first stabilized at R10 before being progressively reduced until R40. Polyubiquitinated proteins accumulated from I4, whereas the increased ubiquitination rates and chymotrypsin-like activity of the proteasome were detectable from I6 to I8. Apoptosome and caspase-3 or -9 activities increased at I6 and I8, respectively. The ubiquitin-proteasome-dependent pathway was normalized early when muscle stops to atrophy (R10). By contrast, the mitochondria-associated apoptotic pathway was first downregulated below basal levels when muscle started to recover at R15 and completely normalized at R20. Myf 5 protein levels decreased from I4 to I8 and were normalized at R10. Altogether, our results suggest a two-stage process in which the ubiquitin-proteasome pathway is rapidly up- and downregulated when muscle atrophies and recovers, respectively, whereas apoptotic processes may be involved in the late stages of atrophy and recovery.     

Alpha-tocopheryl acetate is absorbed and hydrolyzed by Caco-2 cells comparative studies with alpha-tocopherol

Caco-2 cells were used as a model for investigating and comparing the absorption of alpha-tocopherol (Tol) and alpha-tocopheryl acetate (Tac) solubilized in micelles based on a mixture of sodium taurocholate (NaTC) and oleic acid. Surprisingly, the uptake of Tac was found to be similar to that of Tol, and in both cases, the dose-response plots suggest that protein-mediated transport processes were involved. Moreover Tol or Tac were also secreted into the basolateral medium of Caco-2 cells but Tac was mainly hydrolyzed either prior to absorption or intracellularly. The solubilization of Tol or Tac by NaTC on the apical side of the cell monolayer is a prerequisite for the uptake process, although larger amounts of the bile salt are necessary to solubilize Tac than Tol. Caco-2 cells showed hydrolytic activity on Tac, and additional cholesterol esterase may be taken up by the cells, thus increasing the rates of intracellular hydrolysis of Tac. Based on our findings, a scheme is suggested accounting for the absorption of alpha-tocopheryl acetate by enterocytes.