Characterization of mesenchymal stem cells isolated from the human umbilical cord

Numerous papers have reported that mesenchymal stem cells (MSCs) can be isolated from various sources such as bone marrow, adipose tissue and others. Nonetheless it is an open question whether MSCs isolated from different sources represent a single cell lineage or if cells residing in different organs are separate members of a family of MSCs. Subendothelial tissue of the umbilical cord vein has been shown to be a promising source of MSCs. The aim of this study was to isolate and characterize cells derived from the subendothelial layer of umbilical cord veins as regards their clonogenicity and differentiation potential. The results from these experiments show that cells isolated from the umbilical cord vein displayed fibroblast-like morphology and grew into colonies. Immunophenotyping by flow cytometry revealed that the isolated cells were negative for the hematopoietic line markers HLA-DR and CD34 but were positive for CD29, CD90 and CD73. The isolated cells were also positive for survivin, Bcl-2, vimentin and endoglin, as confirmed by RT-PCR and immunofluorescence. These cells can be induced to differentiate into osteogenic and adipogenic cells, but a new finding is that these cells can be induced to differentiate into endothelial cells expressing CD31, vWF and KDR-2, and also form vessel-like structures in Matrigel. The differentiated cells stopped expressing survivin, thus showing a diminished proliferative potential. It can be assumed that the subendothelial layer of the umbilical cord vein contains a population of cells with the overall characteristics of MSCs, with the additional capability to transform into endothelial cells.     

Interactions of neural glycosaminoglycans and proteoglycans with protein ligands: assessment of selectivity, heterogeneity and the participation of core proteins in binding

The method of affinity coelectrophoresis was used to study the binding of nine representative glycosaminoglycan (GAG)-binding proteins, all thought to play roles in nervous system development, to GAGs and proteoglycans isolated from developing rat brain. Binding to heparin and non-neural heparan and chondroitin sulfates was also measured. All nine proteins-laminin-1, fibronectin, thrombospondin-1, NCAM, L1, protease nexin-1, urokinase plasminogen activator, thrombin, and fibroblast growth factor-2-bound brain heparan sulfate less strongly than heparin, but the degree of difference in affinity varied considerably. Protease nexin-1 bound brain heparan sulfate only 1.8- fold less tightly than heparin (Kdvalues of 35 vs. 20 nM, respectively), whereas NCAM and L1 bound heparin well (Kd approximately 140 nM) but failed to bind detectably to brain heparan sulfate (Kd>3 microM). Four proteins bound brain chondroitin sulfate, with affinities equal to or a few fold stronger than the same proteins displayed toward cartilage chondroitin sulfate. Overall, the highest affinities were observed with intact heparan sulfate proteoglycans: laminin-1's affinities for the proteoglycans cerebroglycan (glypican-2), glypican-1 and syndecan-3 were 300- to 1800-fold stronger than its affinity for brain heparan sulfate. In contrast, the affinities of fibroblast growth factor-2 for cerebroglycan and for brain heparan sulfate were similar. Interestingly, partial proteolysis of cerebroglycan resulted in a >400- fold loss of laminin affinity. These data support the views that (1) GAG-binding proteins can be differentially sensitive to variations in GAG structure, and (2) core proteins can have dramatic, ligand-specific influences on protein-proteoglycan interactions.      

Alternative splicing and protein function

Background  

Alternative splicing is a major mechanism of generating protein diversity in higher eukaryotes. Although at least half, and probably more, of mammalian genes are alternatively spliced, it was not clear, whether the frequency of alternative splicing is the same in different functional categories. The problem is obscured by uneven coverage of genes by ESTs and a large number of artifacts in the EST data.     

Comparison of tetrachromic VOF stain to other histochemical staining techniques for characterizing stromal soft and hard tissue components

The components of hard tissues including dentin, enamel, cementum, bone and other calcified deposits, and mature and immature collagen pose problems for identification in routine hematoxylin and eosin (H & E) stained sections. Use of combinations of stains can demonstrate the components of hard tissues and soft tissues distinctly. We assessed the efficacy of the Verde Luz-orange G-acid fuchsin (VOF) stain for differentiating hard and soft connective tissues and compared results with other histochemical staining techniques. Eighty tissue sections comprising developing tooth (30), ossifying fibroma (30) and miscellaneous pathologies (20) expected to contain varying types of calcified tissues were stained with H & E, VOF, and Masson's trichrome (MT). In developing tooth, VOF demonstrated better differentiation of hard tissues, while it was comparable to MT for ossifying fibroma and miscellaneous pathologies. The intensity of staining was greater with VOF than with the other stains studied. VOF stains hard tissue components distinctly and gives good contrast with the surrounding connective tissue. VOF is comparable to MT, but has added advantages including single step staining, rapid and easy procedures, and it distinguishes the maturity of the tissues.     

Repair of radiation induced DNA damages in unicellular green algae

Two cell repair systems--photoreactivation and repair of single-strand DNA breaks have been studied using unicellular green algae as a test-system. Effects of the genotype and the intensity of pico/second UV-laser irradiation on the degree of the photoreactivation have been investigated. It has been shown that the lower intensity (I = 8.10(6) W/cm2) effects less the inactivation of living cells comparing with I = 30.10(6) W/cm2, regardless of the genotype. The clearly expressed higher potentials of strains LARG-1 and 260 to produce and repair alterations of the cyclobutane-pyrimidine dimers type have been established. An analysis of DNA degradation during gamma rays irradiation and after incubation has been carried out for investigation the relationship between strains radioresistance and repair of single-strand break. It has been shown that high efficiency of the repair system is characteristic of the resistant strain obtained from chronically irradiated population.     

Changes inChlorella vulgaris B. populations after chronic influence with chemical and physical mutagenic factors

The resistance of differentChlorella vulgaris B. strains obtained as a result of chronic influence with chemical and physical factors have been studied. The aim of our work was to establish the relation between the resistance ofChlorella vulgaris populations with ultrastructural cell organization and the level of endogenic thiols. It was established that destructive processes in the cell are reduced to minimum in the more resistant strains and are of a definite recovering character. The higher resistance is accompanied by higher content of endogenic thiols, enlarging of cell pyrenoid and multilayered cell-covering membrane. From the results obtained it may be supposed that one of the probable mechanisms determining the resistance of theChlorella vulgaris strains obtained by the influence of physical and chemical factors and investigated by us, is connected with the changes which took place in the genetic systems controlling the level of the natural protectors in the cell and is accompanied by structural changes affecting mainly the size and number of cell pyrenoid as well as the thickness of the cell-covering membrane.     

Size and mortality rates of Glossina pallidipes in the semi-arid zone of southwestern Kenya

Seasonal changes in the mean size of tsetse, Glossina pallidipes Austen, as indicated by wing vein length, were monitored during 1983-86 at Nguruman, southwestern Kenya. Changes in size of nulliparous females and wing fray category 1 males were shown to be correlated with the relative humidity 2 months before they were captured. Soil temperature when flies were in the pupal stage had much less effect. Size dependent mortality was demonstrated, with the mean size of flies emerging from pupae significantly less than that of field-caught flies. This mortality must occur at emergence, since there was no evidence of size-dependent mortality once the flies became available to the trap. Size was correlated with density-independent mortality acting on the parent population 2 months previously. It might therefore be possible to use size as an index of the intensity of such mortality. This could be useful when assessing the level of additional mortality required to suppress tsetse populations.     

Nuclear DNA sequences from late Pleistocene megafauna

We report the retrieval and characterization of multi- and single-copy nuclear DNA sequences from Alaskan and Siberian mammoths (Mammuthus primigenius). In addition, a nuclear copy of a mitochondrial gene was recovered. Furthermore, a 13,000-year-old ground sloth and a 33,000- year-old cave bear yielded multicopy nuclear DNA sequences. Thus, multicopy and single-copy genes can be analyzed from Pleistocene faunal remains. The results also show that under some circumstances, nucleotide sequence differences between alleles found within one individual can be distinguished from DNA sequence variation caused by postmortem DNA damage. The nuclear sequences retrieved from the mammoths suggest that mammoths were more similar to Asian elephants than to African elephants.