Seasonal variations in sterol composition of Delesseria sanguinea (Ceramiales,Rhodophyta)

On Normandy coasts, the red alga Delesseria sanguinea perennates by its stipe; fronds grow in January and disappear in June. Seasonal variations in sterol composition in relation to the biology of D. sanguinea are reported. Sterols in cellular membranes are free or conjugated by esterification with fatty acids, heterosides or lipid complexes like phospholipids. Both kinds of sterols were analyzed by GC-MS. The major sterol (80%) found in fronds was cholesterol whereas in stipes, cholesterol was also the major sterol in spring, but in September, an important reduction in cholesterol yield was noted with proportional increase in sitosterol content. It appears that cholesterol is synthesized in fronds in spring, then transferred to the stipe, which loses an important amount of cholesterol with loss of the blades.     

Vascular endothelial cells: Targets for studying the activity of hair follicle cell-produced VEGF

Fetal bovine aortic endothelial cells (FBAEC) were exposed to purified fractions of conditioned medium from cultures of hair dermal papilla cells (DPC) to determine the existence of any vascular endothelial growth factor (VEGF)-like paracrine activity of the latter. Such fractions were tested for stimulation of growth and migration of cultured FBAEC. In addition, VEGF secretion by DPC was measured by radioassay of VEGF receptors using FBAEC as target cells. The results showed that stimulation of FBAEC proliferation and migration following exposure to purified conditioned medium was dose-dependent. Radioreceptor assays of recombinant VEGF and purified DPC-conditioned medium showed competitive VEGF binding in FBAEC.Abbreviations CM conditioned medium - DMEM Dulbecco's modified eagle's medium - DPC dermal papilla cells - EDTA ethylenediaminetetra-acetic acid - FBAEC fetal bovine aortic endothelial cells - FCS fetal calf serum - VEGF vascular endothelial growth factor     

The influence of cosubstrate and aeration on xylitol formation by recombinantSaccharomyces cerevisiae expressing theXYL1 gene

Xylitol formation by a recombinantSaccharomyces cerevisiae strain containing theXYL1 gene fromPichia stipitis CBS 6054 was investigated under three sets of conditions: (a) with glucose, ethanol, acetate, or glycerol as cosubstrates, (b) with different oxygenation levels, and (c) with different ratios of xylose to cosubstrate. With both glucose and ethanol the conversion yields were close to 1 g xylitol/g consumed xylose. Decreased aeration increased the xylitol yield on the basis of consumed cosubstrate, while the rate of xylitol formation decreased. The xylitol yield based on consumed cosubstrate also increased with increased-xylose:cosubstrate ratios. The transformant utilized the cosubstrate more efficiently than did a reference strain in terms of utilization rate and growth rate, implying that the regeneration of NAD(P)⁺ during xylitol formation by the transformant balanced the intracellular redox potential.     

Effect of ischemia/reperfusion sequence on cytosolic iron status and its release in the coronary effluent in isolated rat hearts

The hypothesis that oxygen-derived free radicals play an important role in myocardial ischemic and reperfusion injury has received a lot of support. In the presence of catalytic amounts of transition metals such as iron, superoxide anions, and hydrogen peroxide can be transformed into a highly reactive hydroxyl radical °OH (Haber-Weiss reaction). In view of this, we have undertaken this study to investigate whether iron is involved in the reperfusion syndrome and therefore could aggravate free radicals injury. Coronary effluent iron concentrations and cardiac cytosolic iron levels were evaluated in rat hearts subjected to an ischemia/reperfusion sequences. In the case of total ischemia, iron concentration in coronary effluents peaked immediately in the first sample collected upon reperfusion. However, in the case of partial ischemia, iron concentration in coronary effluents peaked rather exclusively during ischemia period. Cardiac cytosolic iron level augmented significantly after 30 min of total ischemia and non significantly in the other ischemia protocols compared to perfused control hearts. It also appears that the iron released is not protein-bound, and could therefore have a marked catalytic activity. The results of the present study suggest that in the oxygen paradox, iron plays an important role in inducing alterations during reoxygenation.     

Optimization of transverse alternating field electrophoresis for strain identification of Leuconostoc oenos

Genomic DNA of several strains oof oenological lactic bacteria belonging to the species Lactobacillus plantarum, Leuconostoc oenos and Pediococcus pentosaceus was digested by the rare-cutting endonucleases ApaI and SmaI. The restriction products were separated by transverse alternating field electrophoresis (TAFE). The size of the genome of L. oenos estimated by adding the molecular size of the ApaI fragments was on average 1320 kb. A strong polymorphism was observed between the strains, which could be easily differentiated except for two industrial strains of L. oenos. A simple modification of the TAFE apparatus is proposed to improve the separation of the DNA fragments. Correspondence to: J.-N. Hallet     

Evolutionary study of multigenic families mapping close to the human MHC class I region

Summary During a search for novel coding sequences within the human MHC class I region (chromosome 6p21.3), we found an exon (named B30-2) coding for a 166-amino-acid peptide which is very similar to the C-terminal domain of several coding sequences: human 52-kD Sjögren's syndrome nuclear antigen A/Ro (SS-A/Ro) and ret finger protein (RFP), Xenopus nuclear factor 7 (XNF7), and bovine butyrophilin. The first three of these proteins share similarities over the whole length of the molecule whereas butyrophilin is similar in the C-terminal domain. The N-terminal domain of butyrophilin is similar to rat myelin/oligodendrocyte glycoprotein (MOG) and chicken B blood group system (B-G) protein. These domains are components of a new subfamily of the immunoglobulin superfamily (IgSF). Butyrophilin is thus a mosaic protein composed of the MOG/B-G Ig-like domain and the C-terminal domain of 52-kD SS-A/Ro, RFP, and XNF7 (1330-2-like domain). Moreover, in situ hybridization shows that RFP, butyrophilin, and MOG map to the human chromosome 6p2l.3-6p22 region and are thus close to the MHC class I genes. It is therefore possible that the butyrophilin gene is the product of an exon shuffling event which occurred between ancestors of the RFP and MOG genes. To our knowledge, this is the first example of the colocalization of a chimeric gene and its putative progenitors. Finally, regulatory protein T-lymphocyte 1 (Rpt-1) shares similarities with the N-terminal halves of RFP, 52-kD SS-A/Ro, and XNF7, but not with the B30-2-like domain. We show that the ancestral Rpt-l gene evolved by overprinting. Correspondence to: P. Pontarotti     

X-linked myoclonus epilepsy explained as a maternally inherited mitochondrial disorder

A family with myoclonus epilepsy has been described previously as suffering from an X-linked disorder, because at least four males were affected, and only mild and variable symptoms were seen in some female carriers. In this family, we have now identified a mitochondrial AG (8344) heteroplasmic point mutation. This point mutation has been described in families with maternally inherited myoclonus epilepsy and ragged red fibers. The degree of severity of the disorder in the different family members was reflected in the relative quantity of mutated mitochondrial DNA. It is concluded that the mode of inheritance in this family is not X-linked but maternal.     

Non-linear loss of suitable wine regions over Europe in response to increasing global warming

Evaluating the potential climatic suitability for premium wine production is crucial for adaptation planning in Europe. While new wine regions may emerge out of the traditional boundaries, most of the present-day renowned winemaking regions may be threatened by climate change. Here, we analyse the future evolution of the geography of wine production over Europe, through the definition of a novel climatic suitability indicator, which is calculated over the projected grapevine phenological phases to account for their possible contractions under global warming. Our approach consists in coupling six different de-biased downscaled climate projections under two different scenarios of global warming with four phenological models for different grapevine varieties. The resulting suitability indicator is based on fuzzy logic and is calculated over three main components measuring (i) the timing of the fruit physiological maturity, (ii) the risk of water stress and (iii) the risk of pests and diseases. The results demonstrate that the level of global warming largely determines the distribution of future wine regions. For a global temperature increase limited to 2°C above the pre-industrial level, the suitable areas over the traditional regions are reduced by about 4%/°C rise, while for higher levels of global warming, the rate of this loss increases up to 17%/°C. This is compensated by a gradual emergence of new wine regions out of the traditional boundaries. Moreover, we show that reallocating better-suited grapevine varieties to warmer conditions may be a viable adaptation measure to cope with the projected suitability loss over the traditional regions. However, the effectiveness of this strategy appears to decrease as the level of global warming increases. Overall, these findings suggest the existence of a safe limit below 2°C of global warming for the European winemaking sector, while adaptation might become far more challenging beyond this threshold.