Z → B transition in poly[d(G-m5C)2] induced by interaction with 4′,6-diamidino-2-phenylindole

The Z form of poly[d(G-m⁵C)₂], in presence of Mg²⁺ ion, is found to be transformed into B form upon interaction with 4′,6-diamidino-2-phenylindole (DAPI). The Z → B transformation is complete at a mixing ratio of about 0.07 DAPI per DNA base pairs, i.e., each DAPI molecule may be related to the conversion of 6–7 base pairs. An interaction between DAPI and poly[d(G-m⁵C)₂] in its Z form at low drug: DNA ratios is suggested from optical dichroism and time-resolved luminescence anisotropy results. The spectroscopic behaviour of DAPI indicates that the Z conformation of DNA does not provide normal binding sites for DAPI, such as groove or intercalation sites, but that the initial association may be of external nature. © 1993 John Wiley & Sons, Inc.     

ANNUAL DIFFERENCES IN FEMALE REPRODUCTIVE SUCCESS AFFECT SPATIAL AND COHORT-SPECIFIC GENOTYPIC HETEROGENEITY IN PAINTED TURTLES

Long-term ecological data were used to evaluate the relative importance of movements, breeding structure, and reproductive ecological factors to the degree of spatial and age-specific variation in genetic characteristics of painted turtles (Chrysemys picta) on the E. S. George Reserve in southeastern Michigan. Estimates of the degree of spatial genetic structuring were based on the proportion of total genotypic variance partitioned within and between subpopulations (inferred from hierarchical F-statistics based on variation at 18 protein loci), and in terms of gene correlations (co-ancestry among individuals derived from reproductive data on full-sib families of females nesting at specific nesting areas). Little variation in allele frequency was observed among turtles from different marshes (F_mt = 0.003), though significant variation was observed among turtles from different nesting areas associated with each marsh (F_nm = 0.046). Gene correlations among individuals within nesting areas varied greatly over years (0.032-0.171; mean = 0.069) and were negatively correlated to the proportion of females that successfully nested during each year. General concordance between independent estimates of genotypic correlations (i.e., F_nm derived from protein electrophoretic variation vs. mean co-ancestry) suggests that allozyme data, when collected over spatial scales consistent with species behavioral characteristics and reproductive ecology, may accurately reflect the apportionment of gene diversity within and among subpopulations. The magnitude and patterning of allelic variation among nesting areas and individuals appears to be primarily a function of gametic correlations among members of full-sib families, irrespective of the degree of gene flow or female nesting-site fidelity. Comparisons of genetic characteristics among 11 cohorts (1974-1984) revealed that heterozygosity (H) and inbreeding coefficients (F) varied greatly. Cohort estimates of H and F were correlated to female nesting success and to estimates of co-ancestry for the same years. Results clearly reflect the concomitant importance of ecological factors (principally the proportion of the female population that successfully produce offspring during each year) in determining the magnitude and patterning of gene correlations within and among groups, and to the genotypic composition of offspring born during each year.     

Cytological and molecular characterization of a chromosome interchange and addition lines in Cadet involving chromosome 5B of wheat and 6Ag of Lophopyrum ponticum

Efforts to transfer wheat curl mite (Eriophyes tulipae Keifer) resistance from Lophopyrum ponticum 10X (Podb.) Love to bread wheat (Triticum aestivum L.) have resulted in the production of a number of cytogenetic stocks, including an addition line of 6Ag, a ditelo addition line, and a wheat-Lophopyrum translocation line. Characterization of these lines with C-banding, in situ hybridization with a Lophopyrum species-specific repetitive DNA probe (pLeUCD2), and Southern blotting with pLeUCD2 and a 5S ribosomal DNA probe (pScT7) confirmed that the distal portion of the short arm of 6Ag was translocated onto the distal portion of 5BS (5BL. 5BS-6AgS). It was also determined that the ditelo addition was an acrocentric chromosome of 6AgS.     

Epidermal growth factor stimulates vascular endothelial growth factor production by human malignant glioma cells: a model of glioblastoma multiforme pathophysiology.

Hypervascularity, focal necrosis, persistent cerebral edema, and rapid cellular proliferation are key histopathologic features of glioblastoma multiforme (GBM), the most common and malignant of human brain tumors. By immunoperoxidase and immunofluorescence, we definitively have demonstrated the presence of vascular endothelial growth factor (VEGF) and epidermal growth factor receptor (EGFr) in five out of five human glioma cell lines (U-251MG, U-105MG, D-65MG, D-54MG, and CH-235MG) and in eight human GBM tumor surgical specimens. In vitro experiments with glioma cell lines revealed a consistent and reliable relation between EGFr activation and VEGF production; namely, EGF (1-20 ng/ml) stimulation of glioma cells resulted in a 25-125% increase in secretion of bioactive VEGF. Conditioned media (CM) prepared from EGF-stimulated glioma cell lines produced significant increases in cytosolic free intracellular concentrations of Ca2+ ([Ca2+]i) in human umbilical vein endothelial cells (HUVECs). Neither EGF alone or CM from glioma cultures prepared in the absence of EGF induced [Ca2+]i increases in HUVECs. Preincubation of glioma CM with A4.6.1, a monoclonal antibody to VEGF, completely abolished VEGF-mediated [Ca2+]i transients in HUVECs. Likewise, induction by glioma-derived CM of von Willebrand factor release from HUVECs was completely blocked by A4.6.1 pretreatment. These observations provide a key link in understanding the basic cellular pathophysiology of GBM tumor angiogenesis, increased vascular permeability, and cellular proliferation. Specifically, EGF activation of EGFr expressed on glioma cells leads to enhanced secretion of VEGF by glioma cells. VEGF released by glioma cells in situ most likely accounts for pathognomonic histopathologic and clinical features of GBM tumors in patients, including striking tumor angiogenesis, increased cerebral edema and hypercoagulability manifesting as focal tumor necrosis, deep vein thrombosis, or pulmonary embolism.     

Model-based control of feed rate and illuminance in a photosynthetic fed-batch reactor for H2S removal

Traditional application of computer to fermentation processes has focused on the measurement and control of parameters such as temperature, pH, vessel pressure, sparge rate, dissolved oxygen, substrate concentration, and product concentration. In a fed-batch reactor with the photosynthetic green sulfur bacterium Chlorobium thiosulfatophilum which converts hydrogen sulfide to elementary sulfur or sulfate, separate measurement of cell mass concentration and sulfur particle concentration turbidimetrically was difficult due to their combined contributions to the total turbidity. Instead of on-line measurement of many process variables, a model-based control of feed rate and illuminance was designed. Optimal operation condition relating feed rate vs. light intensity was obtained to suppress the accumulation of sulfate and sulfide, and to save light energy in a 4-1 photosynthetic fed-batch reactor. This relation was correlated with the inreasing cell mass concentration. A model which describes the cell growth by considering the light attenuation effects due to scattering and absorption, and to crowding effect of the cells, was established beforehand with the results from the experiments. Based on these optimal operating conditions and the cell growth model, automatic controls of feed rate and illuminance were carried out alternatively to the traditional application of computer to fermentation with on-line measurement, realtime response and adjustment of process variables.List of Symbols F ml/min Flow rate of gas mixture - hV lux Average illuminance - Q mmol/(l h) Removal rate of hydrogen sulfide - X mg protein/l Cell mass concentration as protein - X ₀ mg protein/l Initial cell mass concentration - X _m mg protein/l Maximum cell mass concentration - _a h^–1 Apparent specific growth rate     

Crevice-forming mutants in the rigid core of bovine pancreatic trypsin inhibitor: crystal structures of F22A, Y23A, N43G, and F45A.

Crystal structures of four mutants of bovine pancreatic trypsin inhibitor (F22A, Y23A, N43G, and F45A), engineered to alter their stability properties, have been determined. The mutated residues, which are highly conserved among Kunitz-type inhibitors, are located in the rigid core of the molecule. Replacement of the partially buried bulky residues of the wild-type protein with smaller residues resulted in crevices open to the exterior of the molecule. The overall three-dimensional structure of these mutants is very similar to that of the wild-type protein and only small rearrangements are observed among the atoms lining the crevices.     

Crystal structure of human annexin I at 2.5 A resolution.

cDNA coding for N-terminally truncated human annexin I, a member of the family of Ca(2+)-dependent phospholipid binding proteins, has been cloned and expressed in Escherichia coli. The expressed protein is biologically active, and has been purified and crystallized in space group P2(1)2(1)2(1) with cell dimensions a = 139.36 A, b = 67.50 A, and c = 42.11 A. The crystal structure has been determined by molecular replacement at 3.0 A resolution using the annexin V core structure as the search model. The average backbone deviation between these two structures is 2.34 A. The structure has been refined to an R-factor of 17.7% at 2.5 A resolution. Six calcium sites have been identified in the annexin I structure. Each is located in the loop region of the helix-loop-helix motif. Two of the six calcium sites in annexin I are not occupied in the annexin V structure. The superpositions of the corresponding loop regions in the four domains show that the calcium binding loops in annexin I can be divided into two classes: type II and type III. Both classes are different from the well-known EF-hand motif (type I).     

Lectin-induced apoptosis of tumour cells

The mechanisms of cytotoxic activity of Griffonia simplicifolia1-B₄ (GS1B₄) and wheat germ agglutinin (WGA) lectins againstvarious murine tumour cell lines were studied. Tumour cellsthat lack lectin-binding carbohydrates were resistant to lysisby these lectins. However, YAC-1 cells that expressed GS1B⁴lectin-binding sites showed low sensitivity to lysis. To furtheranalyse the relative importance of cell surface carbohydratesin lectin cytotoxicity, BL6–8 melanoma cells, which donot express the     

The mouse Dlx-2 (Tes-1) gene is expressed in spatially restricted domains of the forebrain, face and limbs in midgestation mouse embryos

The pattern of RNA expression of the murine Dlx-2 (Tes-1) homeobox gene is described in embryos ranging in age from E8.5 through E11.5. Dlx-2 is a vertebrate homologue of the Drosophila Distal-less (Dll) gene. Dll expression in the Drosophila embryo is principally limited to the primordia of the brain, head and limbs. Dlx-2 is also expressed principally in the primordia of the forebrain, head and limbs. Within these regions it is expressed in spatially restricted domains. These include two discontinuous regions of the forebrain (basal telencephalon and ventral diencephalon), the branchial arches, facial ectoderm, cranial ganglia and limb ectoderm. Several mouse and human disorders have phenotypes which potentially are the result of mutations in the Dlx genes.