Histone - induced changes in the cellular growth of synchronized chlamydomonas reinhardii are due to histone H1

The cellular growth ofChlamydomonas reinhardii is modified by the addition of a total exogenous histone fraction. These modifications may be related to chloroplast DNA replication; they are different according to the different classes of histones. The H₁ subfraction seems to be responsible for the effect of the total histone fraction.     

Immediate effects of an 8-h advance shift of the rest-activity cycle on 24-h profiles of cortisol

To investigate the adaptation of plasma cortisol profiles to an abrupt phase advance of the rest-activity cycle, eight normal young subjects were submitted in a sleep laboratory to an 8-h advance shift of their sleep-wake and dark-light cycles. The shift was achieved by advancing bedtimes from 2300-0700 to 1500-2300. Blood samples were obtained at 20-min intervals for 68 consecutive hours. The shift resulted within 6-9 h in a 3- to 4-h advance of timings of the nadir of the cortisol profile and of the end of the quiescent period but had no immediate effect on the timing of cortisol acrophase. The quiescent period of cortisol secretion was shortened and fragmented. Thus a major advance shift achieved without enforcing sleep deprivation results in a rapid partial adaptation of the temporal profiles of cortisol but also in a marked disruption of the cortisol quiescent period. Sleep onset was consistently followed by a decrease in cortisol concentrations. Conversely, both sleep-wake and dark-light transitions were consistently associated with cortisol secretory pulses.     

Structure and histone binding properties of the Vps75-Rtt109 chaperone-lysine acetyltransferase complex

The histone chaperone Vps75 presents the remarkable property of stimulating the Rtt109-dependent acetylation of several histone H3 lysine residues within (H3-H4)(2) tetramers. To investigate this activation mechanism, we determined x-ray structures of full-length Vps75 in complex with full-length Rtt109 in two crystal forms. Both structures show similar asymmetric assemblies of a Vps75 dimer bound to an Rtt109 monomer. In the Vps75-Rtt109 complexes, the catalytic site of Rtt109 is confined to an enclosed space that can accommodate the N-terminal tail of histone H3 in (H3-H4)(2). Investigation of Vps75-Rtt109-(H3-H4)(2) and Vps75-(H3-H4)(2) complexes by NMR spectroscopy-probed hydrogen/deuterium exchange suggests that Vps75 guides histone H3 in the catalytic enclosure. These findings clarify the basis for the enhanced acetylation of histone H3 tail residues by Vps75-Rtt109.     

Endothelial cell responses towards low-fouling surfaces bearing RGD in a three-dimensional environment

This study reveals that it is possible to obtain a specific cell response towards low-fouling carboxymethyl dextran (CMD) surfaces bearing the RGD adhesive peptide in fibrin. To avoid cell sedimentation on surfaces observed in traditional cell culture systems, CMD surfaces bearing RGD were vertically embedded in fibrin containing human umbilical vein endothelial cells (HUVEC) and their effect over cells was investigated. Compared to the CMD surfaces and to CMD layers bearing the negative control RGE, RGD coatings promoted cell adhesion, induced focal contact formation indicated by co-localization of vinculin and actin fibers, and presented a significant effect over HUVEC net growth during the first 24 h of the culture, as revealed by Ki67 staining and cell counting. The intracellular localization of caveolin-1 combined with the expression of beta 1 integrins was investigated and the orientation of HUVEC towards and on the RGD surfaces was studied. When compared to the negative controls, HUVEC responded to the RGD surface in fibrin resulting in acceleration of morphological changes. RGD surfaces supported fibrin degradation by HUVEC as revealed by fluorescent fibrin experiments as well as multi-cellular structure formation, vacuolation and lumen formation.     

Seasonal diving behaviour in lactating subantarctic fur seals on Amsterdam Island

Diving behaviour was investigated in female subantarctic fur seals (Arctocephalus tropicalis) breeding on Amsterdam Island, Indian Ocean. Data were collected using electronic Time Depth Recorders on 19 seals during their first foraging trip after parturition in December, foraging trips later in summer, and during winter. Subantarctic fur seals at Amsterdam Island are nocturnal, shallow divers. Ninety-nine percent of recorded dives occurred at night. The diel dive pattern and changes in dive parameters throughout the night suggest that fur seals follow the nycthemeral migrations of their main prey. Seasonal changes in diving behaviour amounted to the fur seals performing progressively deeper and longer dives from their first foraging trip through winter. Dive depth and dive duration increased from the first trip after parturition (16.6 ± 0.5 m and 62.1 ± 1.6 s respectively, n=1000) to summer (19.0 ± 0.4 m and 65 ± 1 s, respectively, n=2000) through winter (29.0 ± 1.0 m and 91.2 ± 2.2 s, respectively, n=800). In summer, subantarctic fur seals increased the proportion of time spent at the bottom during dives of between 10 and 20 m, apparently searching for prey when descending to these depths, which corresponded to the oceanic mixed layer. In winter, fur seals behaved similarly when diving between 20 and 50 m, suggesting that the most profitable depths for feeding moved down during the study period. Most of the dives did not exceed the physiological limits of individuals. Although dive frequency did not vary (10 dives/h of night), the vertical travel distance and the time spent diving increased throughout the study period, while the post-dive interval decreased, indicating that subantarctic fur seals showed a greater diving effort in winter, compared to earlier seasons. Accepted: 1 August 1999     

Different oligosaccharides accumulate in the brain and urine of a cat with α-mannosidosis: structure determination of five brain-derived and seventeen urinary oligosaccharides

Five brain-derived and 17 urinary oligomannose-type oligosaccharides were isolated by ion-exchange chromatography on Mono Q or Dowex, followed by HPLC on Lichrosorb-NH₂ from a Persian cat suffering from -mannosidosis. The structures ofthe carbohydrate chains were determined by 500- or 600-MHz¹H-NMR spectroscopy. Different oligosaccharide patterns were found in brain and urine. 99% of the urinary oligosaccharides possess an (1-6)-linked mannose residue attached to -mannose, whereas only 5% of the brain-derived oligosaccharides contain such a residue. Furthermore, of the urinary carbohydrate chains 71% end with Man1-4GlcNAc1-4GlcNAc and 29% end with Man1-4GlcNAc, whereas the corresponding amounts are 23% and 77%, respectively, for the brain-derived oligosaccharides.Abbreviations MLEV-17 composite pulse devised by M. Levitt - HOHAHA homonuclear Hartman-Hahn spectroscopy - TPPI time-proportional phase incrementation - 2D two dimensional - GlcNAc N-acetylglucosamine - Man mannose - Fuc fucose     

Plant defense in response to chewing insects: proteome analysis of Arabidopsis thaliana damaged by Plutella xylostella

The interactions between Arabidopsis thaliana and Plutella xylostella have been considered as a model system to unravel the responses of plants to herbivorous insects. Here, we use a 2-DE proteome approach to detect protein expression changes in the leaves of Arabidopsis plants exposed to P. xylostella larval infestation at 27°C within 8?h. Approximately 450 protein spots were reproducibly detected on gels. Of these, comparing healthy and infested leaves, we identified 18 differentially expressed protein spots. Thirteen proteins were successfully identified by MALDI-TOF/MS and LC-ESI-MS/MS. Functional classification analysis indicated that the differentially identified proteins were associated with amino acid, carbohydrate, energy, lipid metabolism, and photosynthesis. In addition, their relative abundances were assessed according to larval pest feeding on Arabidopsis leaves. These data provide valuable new insights for further works in plant-biotic and environmental stress interaction.     

Secular trends in anthropometrical measurements observed in three to 11-year-old French children between 1953 and 2005

This study covers a fifty-year period between 1953 and 2005 and looks at secular trends in stature, weight and sitting height sizes among French boys and girls between the ages of 3 and 11. A special modelling in function to the age and variable for each child was established so that a comparison could be made in the kinetic growth patterns over these same two periods. Statistical analysis shows a significant increase in growth, of 0.8cm per decade in stature, characterised by a certain increase in the lower limbs and the weight (0.8kg per decade) together with a proportional increase on the body mass index. Positive secular trends of this anthropometric nature are generally thanks to improved eating and sanitary habits and this study enables us to build and elaborate new standards in growth patterns essential for monitoring auxological development in 3 to 11-year-old children in the years 2000 and onwards.     

Differential expression of sarcoplasmic proteins in four heterogeneous ovine skeletal muscles

Fiber-type distribution is known to vary widely within and between muscles according to differences in muscle functions. 2-DE and MALDI-MS were used to investigate the molecular basis of muscle fiber type-related variability. We compared four lamb skeletal muscles with heterogeneous fiber-type composition that are relatively rich in fast-twitch fiber types, i.e., the semimembranosus, vastus medialis, longissimus dorsi, and tensor fasciae latae (TL). Our results clearly showed that none of the glycolytic metabolism enzymes detected, including TL which was most strongly glycolytic, made intermuscular differentiation possible. Muscle differentiation was based on the differential expression of proteins involved in oxidative metabolism, including not only citric acid cycle enzymes but also other classes of proteins with functions related to oxidative metabolism, oxidative stress, and probably to higher protein turnover. Detected proteins were involved in transport (carbonate dehydratase, myoglobin, fatty acid-binding protein), repair of misfolding damage (heat shock protein (HSP) 60 kDa, HSP-27 kDa, alpha-crystallin beta subunit, DJ1, stress-induced phosphoprotein), detoxification or degradation of impaired proteins (GST-Pi, aldehyde dehydrogenase, peroxiredoxin, ubiquitin), and protein synthesis (tRNA-synthetase). The fractionating method led to the detection of proteins involved in different functions related to oxidative metabolism that have not previously been shown concomitancy.