Differentiation of 1-O-alk-1′-enyl-2-acyl and 1-O-alkyl-2-acyl Glycerophospholipids by Multiple-Stage Linear Ion-Trap Mass Spectrometry with Electrospray Ionization

We described linear ion-trap mass spectrometric approaches applying MS3 and MS4 toward to the structural characterization of 1-O-alk-1′-enyl-2-acyl-, 1-O-alkyl-2-acyl-, and diacyl-glycerophospholipids (GPL) as the [M – H]− ions desorbed by ESI in negative-ion mode. Further dissociation of the [lM – H – R2CO2H – polar head group]− ions from the [M – H]− ions of GPL that have undergone the consecutive losses of the fatty acid substituent at sn-2 and the polar head group readily gives the structural information of the radyl group at sn-1, resulting in structural differentiation among the 1-O-alk-1′-enyl-2-acyl-, 1-O-alkyl-2-acyl, and diacyl-glycerolphospholipid molecules. The distinction between a 1-O-alk-1′-enyl-2-acyl- and a 1-O-alkyl-2-acyl-GPL is based on the findings that the MS3 (or MS4) spectrum of the [M – H – R2CO2H – polar head group]− ion from the former compound is dominated by the alkenoxide anion that represents the radyl moiety at sn-1, while the spectrum from the latter compound is dominated by the ion at m/z 135 arising from further loss of the 1-O-alkyl group as an alcohol. Another important notion is that the optimal collision energy required for acquiring the former spectrum is significantly lower than that required for obtaining the latter spectrum. Using the approaches, we are able to reveal the structures of several isobaric isomers in GPL mixtures of biological origin. Because the [M – H]− ions are readily formed by various GPL classes (except glycerophosphocholine) in the negative-ion mode, these mass spectrometric approaches should have broad application in the structural identification of GPLs

Elucidation of the Double-Bond Position of Long-Chain Unsaturated Fatty Acids by Multiple-Stage Linear Ion-Trap Mass Spectrometry with Electrospray Ionization

Linear ion-trap (LIT) MS2 mass spectrometric approach toward locating the position of double bond(s) of unsaturated long-chain fatty acids and toward discerning among isomeric unsaturated fatty acids as dilithiated adduct ([M − H + 2Li]+) ions are described in this report. Upon resonance excitation in a LIT instrument, charge-remote fragmentation that involves β-cleavage with γ-H shift (McLafferty rearrangement) is the predominant fragmentation pathway seen for the [M − H + 2Li]+ ions of monoenoic long-chain fatty acids. The fragmentation process results in a dilithiated product ion of terminally unsaturated fatty acid, which undergoes consecutive McLafferty rearrangement to eliminate a propylene residue, and gives rise to another dilithiated adduct ion of terminally unsaturated fatty acid. In addition to the above-cited fragmentation process, the [M − H + 2Li]+ ions of homoconjugated dienoic long-chain fatty acids also undergo α-cleavage(s) with shift of the allylic hydrogen situated between the homoconjugated double bonds to the unsaturated site. These fragmentation pathways lead to two types of CC bond cleavages that are allylic (α-cleavage) or vinylic, respectively, to the proximal CC double bond, resulting in two distinct sets of ion series, in which each ion series is separated by a CH2CHCH (40 Da) residue. These latter fragmentations are the predominant processes seen for the polyunsaturated long-chain fatty acids. The spectrum feature dependent on the position of unsaturated double bond(s) affords unambiguous assignment of the position of double bond(s) of long-chain unsaturated fatty acids

Taekwondo training speeds up the development of balance and sensory functions in young adolescents

Objectives: This study aimed (1) to identify the developmental status of balance and sensory functions in young adolescents as compared to adults and, (2) to explore the effect of Taekwondo (TKD) training on the development of balance and sensory systems in young adolescents. Design: Cross-sectional controlled trial. Methods: Sixty-six participants including 42 adolescents (21 TKD practitioners, 21 non-TKD practitioners) and 24 adults were tested. The sway velocity of centre of gravity was recorded during standing on the non-dominant leg on a Smart Equitest ® system. The somatosensory, vestibular and visual ratios were also measured with the machine. Results: Adult participants swayed slower than both TKD and non-TKD adolescent groups during single leg stance with eyes open (p=0.007 and p< 0.001, respectively). The TKD adolescent group, in turn, swayed slower than the non-TKD adolescent group (p< 0.001). Adult participants had better visual ratio than both TKD and non-TKD adolescents (p=0.001 and p< 0.001, respectively) while there was no difference between the TKD and non-TKD adolescents (p=0.164). For the vestibular ratio, there was no significant difference between adult participants and TKD adolescents (p=0.432). Adolescents who did not practice TKD showed significantly lower vestibular ratio than TKD adolescents and adults (p=0.003 and p<0.001, respectively). In addition, there was no significant difference in the somatosensory ratio among the 3 participant groups (p=0.711). Conclusions: Participation in TKD appears to speed up the development of postural control and vestibular function in adolescents. Clinicians might advocate TKD exercise as a therapeutic intervention for young people with balance or vestibular dysfunctions. © 2011 Sports Medicine Australia.postprin

The Inner Compass of Spindle Positioning and Orientation

Polarized cortical cues are known to guide spindle movements to dictate division axis and cleavage site during asymmetric cell division. In a recent issue of Nature Cell Biology, Kiyomitsu and Cheeseman (2012) report two novel spindle-intrinsic signals that regulate spindle orientation and position in symmetrically dividing human cells

Anionic lipids enriched at the ExPortal of Streptococcus pyogenes

The ExPortal of Streptococcus pyogenes is a membrane microdomain dedicated to the secretion and folding of proteins. We investigated the lipid composition of the ExPortal by examining the distribution of anionic membrane phospholipids. Staining with 10-N-nonyl-acridine orange revealed a single microdomain enriched with an anionic phospholipid whose staining characteristics and behavior in a cardiolipin-deficient mutant were characteristic of phosphatidylglycerol. Furthermore, the location of the microdomain corresponded to the site of active protein secretion at the ExPortal. These results indicate that the ExPortal is an asymmetric lipid microdomain, whose enriched content of anionic phospholipids may play an important role in ExPortal organization and protein trafficking