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11.
The nucleotide sequence and the 5 flanking region of the rbcL gene coding for the large subunit of ribulose bisphosphate-1,5-carboxylase/oxygenase of Pylaiella littoralis, a brown alga, has been determined and the deduced amino-acid sequence has been compared to those of various photosynthetic and chemoautotrophic Eubacteria, of a red alga and of green plastids (Euglena gracilis, green algae and higher plants). Unlike the rbcL genes of green plastids which are more closely related to those of cyanobacteria the P. littoralis rbcL gene is more closely related to that of a -purple bacterium, as was found for the rbcS gene of another chromophytic alga [Boczar et al., Proc Natl Acad Sci USA 86: 4996–4999, 1989]. Matrix data of homology between the rbcL gene of P. littoralis and the same gene of other organisms are presented. Based on our previous report, the gene coding for the 16S rRNA from P. littoralis is closely related to that of E. gracilis (Markowicz et al., Curr Genet 14: 599–608, 1988). We suggest that the large plastid DNA molecule of P. littoralis is a phylogenetically composite genome which probably resulted from mixed endosymbiosis events, or from a horizontal transfer of DNA. 相似文献
12.
A. A. J. J. L. Rutten B. G. A. G. G. Béquet-Passelecq H. B. W. M. Koëter 《In vitro cellular & developmental biology. Plant》1990,26(4):353-360
Summary A new method was developed for rabbit skin organ culture. In a two-compartment model, skin discs were cultured on a Millicell-HA
insert unit with a microporous membrane which allows transport of culture medium via the dermis into the epidermis, whereas
the epidermal side remains free of direct contact with culture medium. In this relatively simple two-compartment organ culture
model, rabbit skin could be cultured for 7 d in RPMI 1640 medium supplemented with fetal bovine serum, or for 2 d in RPMI
1640 medium supplemented with cofactors. The histomorphology and ultrastructure of 7-d cultured rabbit skin discs was essentially
similar to that of freshly isolated rabbit skin. Keratinocytes in the stratum basale continued to divide during organ culture.
The terminal differentiation of the epidermis continued in vitro as was found by the presence of keratohyalin granules, the
intact stratum corneum, and keratin expression. Furthermore, glucose consumption continued until culture Day 7, but thereafter
it declined rapidly. Concomitantly, degenerative changes were found. At the end of the 7-d culture period the distance between
single dermal collagen fibrils had increased as compared to noncultured skin. This model of skin organ cultures can be used
to study biological processes, dermal toxicity, and penetration and metabolism of xenobiotics in intact skin. Furthermore,
within certain limits, processes responsible for repair and regeneration of damaged skin can also be studied in this model
because the rabbit skin can be cultured for 7 d.
The present study was financially supported by grants of Duphar B. V. (Weesp, Netherlands), the European Community, and the
Dutch animal welfare organizations Samenwerkingsverband van de Nederlandse Vereniging tot Bescherming van Dieren en de Nederlandse
Bond tot Bestrijding van de Vivisectie, Anti-Vivisectie Stichting en Stichting Schoonheid Zonder Wreedheid. 相似文献
13.
C. Sauvain-Dugerdil G. Boëtsch C. Serrano-Sanchez 《International Journal of Anthropology》1996,11(2-4):3-11
this first paper introduces the topic of the volume, outcomes of a symposium organised at the 13th ICAES held in Mexico in
August 1993. It briefly reminds of the convergence between anthropology and demography up to date and stresses on the need
of real transdisciplinary work in this challenging domain. The aim of the symposium was to make a contribution on the central
theme chosen by the congress — the cultural and biological dimensions of global change — while examining the place of demographic
anthropology in the study of change. The papers presented at the symposium have been organised in three parts which form the
present volume: the composition of population, the choice of spouse and mobility, the reproduction and dynamics of populations.
The basic mechanisms of change are considered through examples at the level of local populations. This also leads to question
the definitions of human groups and to make a “declaration” stressing on the importance of individual heterogeneity and the
arbitrariness and reductive nature of any grouping of individuals, stating therefore the misapprehension of the most recent
scientific work inherent to the rationale of programs of “ethnic cleasing”.
Translated from the french by prof. Derek F. Roberts 相似文献
14.
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. 相似文献
15.
Vascular endothelial cells: Targets for studying the activity of hair follicle cell-produced VEGF 总被引:1,自引:0,他引:1
S. Lachgar M. Charvéron Y. Gall J. Plouët J. L. Bonafé 《Cell biology and toxicology》1996,12(4-6):331-334
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 相似文献
16.
J. Hallborn N. Meinander B. Hahn-Hëgerdal M. -F. Gorwa M. Pentillä S. Keränen 《Applied microbiology and biotechnology》1994,42(2-3):326-333
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. 相似文献
17.
18.
Patrice Daniel Erwin de Waele Jean-Noël Hallet 《Applied microbiology and biotechnology》1993,38(5):638-641
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 相似文献
19.
Corine Vernet Joëlle Boretto Marie-Geneviève Mattéi Masahide Takahashi Lucinda J. W. Jack Ian H. Mather Sylvie Rouquier Pierre Pontarotti 《Journal of molecular evolution》1993,37(6):600-612
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 相似文献
20.
D. Daniëlle de Vries Ilse J. de Wijs Gerhard Wolff Uwe-Peter Ketelsen Hans-Hilger Ropers Bernard A. van Oost 《Human genetics》1993,91(1):51-54
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. 相似文献