Morphometric discrimination between syndromic (Gorlin) and nonsyndromic keratocysts.

OBJECTIVE: To search for morphologic nuclear features in the epithelial lining of odontogenic keratocysts to differentiate simple from Gorlin syndrome cysts. STUDY DESIGN: Five cases of syndrome-associated keratocysts and five of simple ones were studied. Thirty nuclei from the epithelial basal layer for each case were analyzed by the shape analytical morphometry (SAM) software system to quantitatively evaluate nuclear dimensions (area, perimeter, diameter), contour irregularities and nuclear shape asymmetries. Results were subjected to Student's t test and cluster analysis. RESULTS: Values of nuclear dimensions were very close in both groups of keratocysts, without any significant statistical differences. The variables related to nuclear profile irregularities, as well as those describing nuclear asymmetry, showed significantly higher values (P < .001) in syndromic cysts. Cluster analysis produced two different clusters by using variables related to nuclear contour irregularities. CONCLUSION: Preliminary results indicate the existence of nuclear morphologic differences between simple and syndromic cysts.     

Drosophila mediopunctata P elements: a new example of horizontal transfer.

Sequences homologous to the P element of Drosophila melanogaster were previously identified in Drosophila mediopunctata, a member of the tripunctata group, subgenus Drosophila. We report here that the P element is present in about three to five copies in the D. mediopunctata genome. While one of the insertion sites appears to be fixed, others may be polymorphic, indicating relatively recent P element activity. Phylogenetic analysis revealed that the D. mediopunctata element belongs to the canonical subfamily of P elements and that divergence of the D. mediopunctata element from other members of this subfamily ranges from 2% to 5% at the nucleotide level. This is the first report of a canonical P element outside the subgenus Sophophora. Based primarily on the striking incongruence between P element and host species phylogenies, the presence of a canonical P element in D. mediopunctata is most likely explained by horizontal transfer between species.     

Synthesis, characterization and hybridization studies of new nucleo-gamma-peptides based on diaminobutyric acid.

In the present work, we report the synthesis and the characterization of a new chiral nucleoaminoacid, in which a diaminobutyric moiety is connected to the DNA nucleobase by an amidic bond, and its oligomerization to give the corresponding nucleo-gamma-peptide. The ability of this synthetic polymer to bind complementary DNA was studied in order to explore its possible use in antigene/antisense or diagnostic applications. Our interest in the presented DNA analogue was also supported by the importance of gamma-aminoacid-containing compounds in natural products of biological activity and by the known stability of gamma-peptides to enzymatic degradation. Furthermore, our work could contribute to the study of the role of nucleopeptides as prebiotic material in a PNA world that could successively lead to the actual DNA/RNA/protein world, as recently assumed.     

Study of the effect of the peptide loading and solvent system in SPPS by HRMAS-NMR.

The SPPS methodology has continuously been investigated as a valuable model to monitor the solvation properties of polymeric materials. In this connection, the present work applied HRMAS-NMR spectroscopy to examine the dynamics of an aggregating peptide sequence attached to a resin core with varying peptide loading (up to 80%) and solvent system. Low and high substituted BHAR were used for assembling the VQAAIDYING sequence and some of its minor fragments. The HRMAS-NMR results were in agreement with the swelling of each resin, i.e. there was an improved resolution of resonance peaks in the better solvated conditions. Moreover, the peptide loading and the attached peptide sequence also affected the spectra. Strong peptide chain aggregation was observed mainly in highly peptide loaded resins when solvated in CDCl3. Conversely, due to the better swelling of these highly loaded resins in DMSO, improved NMR spectra were acquired in this polar aprotic solvent, thus enabling the detection of relevant sequence-dependent conformational alterations. The more prominent aggregation was displayed by the VQAAIDYING segment and not by any of its intermediary fragments and these findings were also corroborated by EPR studies of these peptide-resins labelled properly with an amino acid-type spin probe.     

The conduction of protons in different stereoisomers of dioxolane-linked gramicidin A channels

Two different stereoisomers of the dioxolane-linked gramicidin A (gA) channels were individually synthesized (the SS and RR dimers;. Science. 244:813-817). The structural differences between these dimers arise from different chiralities within the dioxolane linker. The SS dimer mimics the helicity and the inter- and intramolecular hydrogen bonding of the monomer-monomer association of gA's. In contrast, there is a significant disruption of the helicity and hydrogen bonding pattern of the ion channel in the RR dimer. Single ion channels formed by the SS and RR dimers in planar lipid bilayers have different proton transport properties. The lipid environment in which the different dimers are reconstituted also has significant effects on single-channel proton conductance (g(H)). g(H) in the SS dimer is about 2-4 times as large as in the RR. In phospholipid bilayers with 1 M [H(+)](bulk), the current-voltage (I-V) relationship of the SS dimer is sublinear. Under identical experimental conditions, the I-V plot of the RR dimer is supralinear (S-shaped). In glycerylmonooleate bilayers with 1 M [H(+)](bulk), both the SS and RR dimers have a supralinear I-V plot. Consistent with results previously published (. Biophys. J. 73:2489-2502), the SS dimer is stable in lipid bilayers and has fast closures. In contrast, the open state of the RR channel has closed states that can last a few seconds, and the channel eventually inactivates into a closed state in either phospholipid or glycerylmonooleate bilayers. It is concluded that the water dynamics inside the pore as related to proton wire transfer is significantly different in the RR and SS dimers. Different physical mechanisms that could account for this hypothesis are discussed. The gating of the synthetic gA dimers seems to depend on the conformation of the dioxolane link between gA's. The experimental results provide an important framework for a detailed investigation at the atomic level of proton conduction in different and relatively simple ion channel structures.     

Hyaluronate receptor CD44 is expressed by astrocytes in the adult chicken and in astrocyte cell precursors in early development of the chick spinal cord.

The role of the hyaluronate receptor, CD44, is well known in adult mammal astrocytes where it modulates neuron-glia interactions. However, no data exist regarding its expression in other vertebrates during their development. In order to detect the expression of CD44 in the chicken and its possible involvement in glial precursor migratory patterns during spinal cord development, a monoclonal antibody (MoAb) against the mammalian standard isoform, CD44-H, was used in immunohistochemical and immunoblot assays. With these methods, CD44 hyaluronate receptors were found on mature astrocyte membranes of adult chicken spinal cord. Astrocytes were identified using a MoAb against GFAP. During development, small clusters of CD44 labelled cells were seen lining the central canal starting from embryonic stage E10. These labelled cells were dispersed in the dorsal, lateral and ventral funiculi of the spinal cord in the subsequent stages. After stage E15, the CD44 labelled cells were identified as astrocytes because of their GFAP immunoreactivity. We conclude that CD44 receptors on immature astrocyte precursors should be considered as early astrocyte markers which have a possible role during cell migratory dispersal.     

Growth stimulation of colorectal carcinoma cells via the c-kit receptor is inhibited by TGF-β1

Activation of the receptor tyrosine kinase c-kit by the kit-ligand, also known as stem cell factor (SCF), is essential to melanocyte and germ cell development and during the early stages of hematopoiesis. Deregulated expression of c-kit has been reported in malignancies affecting these lineages, i.e., myeloid leukemias, melanomas, and germ cell tumors. In addition, c-kit and SCF are coexpressed in some breast and colorectal cancer (CRC) cells, raising the question of whether c-kit serves an autocrine role in normal or malignant epithelial tissues. In this study, we demonstrate that human colorectal carcinomas, but not normal colorectal mucosa cells, coexpress SCF and c-kit in situ. Expression of c-kit was also observed in mucosa adjacent to colorectal tumor tissue. Consistent with a growth-regulatory role of SCF in CRC cells, exogenous SCF stimulated anchorage-dependent and anchorage-independent growth in four out of five CRC cell lines. Exogenous transforming growth factor (TGF)-β1 added at nanomolar concentrations to HT-29 CRC cells, which express the type I, II, and III TGF-β receptors, downregulated c-kit expression to background levels and inhibited c-kit–dependent proliferation. Similarly, TGF-β1 inhibited SCF-dependent proliferation of three first-passage CRC cell lines. In summary, expression of the potential autocrine SCF/c-kit axis is a tumor-associated phenomenon in colorectal cancer that can be suppressed by TGF-β1 in TGF-β–responsive CRC cells. J. Cell. Physiol. 172:1–11, 1997. © 1997 Wiley-Liss, Inc.     

Environmental yeast communities in vineyards in the mountains of Santa Catarina State,Brazil

Yeasts were isolated from three vineyards located in the South Region of Brazil. A cross evaluation was carried out at the oldest vineyard of the study in Pinheiro Preto. Samples of grape berries, grapevine leaves and the soil, along with samples of the winery equipment and effluent, were collected. In the Serra do Marari and Campos Novos vineyards only samples of grape clusters were obtained. The 106 yeast isolates were identified by sequencing the D1/D2 domain of LSU rDNA or ITS1-5.8S-ITS2 region in 22 species. The values for the richness indices varied between the vineyards. A comparison of the taxonomic diversity of the yeasts from these regions using the reciprocal Simpson index showed a significant difference between the Serra do Marari and Campos Novos vineyards (5.72?±?0.36 and 2.92?±?0.36, respectively, p?<?0.0001). The functional diversity was assessed in relation to the use of carbon and nitrogen sources by the yeasts isolated from each location. In general, we observed that the Pinheiro Preto and Campos Novos vineyards differed consistently from the Serra do Marari vineyard according to these indices (FAD2, FDc and Rao, p?<?0.0001). The possible spreading of Saccharomyces cerevisiae from the winery to the vineyard in Pinheiro Preto was observed.