Expression of desmin, laminin and fibronectin during in situ differentiation (decidualization) of rat uterine stromal cells

Immunocytochemical analysis of frozen rat uterine sections containing decidual tissue, formed in response to normal or artificial stimulation of uteri sensitized by endogenous or exogenous hormonal regimens, demonstrated an elevated expression of the intermediate filament protein desmin in decidual cells. Changes in the expression of extracellular matrix (ECM) components were coordinated with the elevated expression of desmin as stromal cells underwent decidualization. In parallel with the pattern of regional decidualization, as determined by elevated desmin expression, laminin accumulated in ECM of decidual cells while an apparent decrease in fibronectin was associated with altered organization at the decidual cell surface. The in situ observations confirm previous results, which indicated that the expression of desmin in decidual cells formed in vivo or in vitro is a valid marker of their differentiation, and resolve questions unanswered in the previous study: (a) desmin (and laminin) appear to be constitutively expressed in non-decidualized stroma at barely detectable levels, (b) desmin is a valid marker of stromal cell differentiation because it is expressed similarly in decidual cells, irrespective of varying experimental protocols for uterine sensitization and stimulation, and (c) desmin expression follows the same regional progression described for the process of decidualization in morphological and histochemical studies.     

Calculations on crystal packing of a flexible molecule, Leu-enkephalin

Crystal packing calculations have been carried out on a substantial number of conformations of Leu-enkephalin; namely, those obtained both from crystal structures and from energy minimizations on isolated molecules, and with and without waters of crystallization. The known crystal structures represent the most energetically stable packings found. The conformations of the enkephalin molecules in the crystal are not the most stable for an isolated molecule; i.e. intermolecular interactions force the isolated molecule to change conformation in order to achieve a small packing volume and an optimal packing energy in the crystal. It is found that the packing energy of an enkephalin molecule is a reasonably smooth function of its molecular volume in the unit cell, if structures with intermolecular hydrogen bonding are excluded, and is substantially independent of other details of the molecular conformation or of the crystal packing. Hydrogen bonding provides additional stabilization of the crystal structure, and would likely permit crystallization of the system if it is sufficiently dense. Solvent molecules further stabilize the structure when they can also provide intermolecular hydrogen bonds.     

Chromosomal localization of three pulmonary surfactant protein genes in the mouse.

Pulmonary surfactant, a protein-phospholipid mixture, maintains surface tension at the lung epithelium/air interface preventing alveolar collapse during respiration. For mammals appropriate developmental production of surfactant is necessary for adaptation to the air breathing environment. Deficiency of pulmonary surfactant results in respiratory distress syndrome (RDS), a leading cause of death in premature infants. Recently, three lung-specific pulmonary surfactant proteins designated SP-A, SP-B, and SP-C have been described. Cloned sequences for the genes that encode each of these proteins have been partially characterized in humans and other species. Analysis of interspecific backcross mice has allowed us to map the chromosomal locations of these three genes in the mouse. The gene encoding SP-A (Sftp-1) and the gene encoding SP-C (Sftp-2) both map to mouse chromosome 14, although at separate locations, while the gene encoding SP-B (Sftp-3) maps to chromosome 6. The mouse map locations determined in this study for the Sftp genes are consistent with the locations of these genes on the human genetic map and the syntenic relationships between the human and the mouse genomes.     

O-ribosyl-phosphate purine as a constant modified nucleotide located at position 64 in cytoplasmic initiator tRNAs(Met) of yeasts.

The unknown modified nucleotide G*, isolated from both Schizosaccharomyces pombe and Torulopsis utilis initiator tRNAs(Met), has been identified as an O-ribosyl-(1"----2')-guanosine-5"-phosphate, called Gr(p), by means of HPLC, UV-absorption, mass spectrometry and periodate oxidation procedures. By comparison with the previously published structure of Ar(p) isolated from Saccharomyces cerevisiae initiator tRNA(Met), the (1"----2')-glycosidic bond in Gr(p) has been postulated to have a beta-spatial conformation. The modified nucleotide Gr(p) is located at position 64 in the tRNA(Met) molecules, i.e. at the same position as Ar(p). Since we have also characterized Gr(p) in Candida albicans initiator tRNA(Met), the phosphoribosylation of purine 64 can be considered as a constant nucleotide modification in the cytoplasmic initiator tRNAs(Met) of all yeast species so far sequenced. Precise evidence for the presence of Gr(p) in initiator tRNAs(Met) of several plants is also reported.     

cDNA, deduced polypeptide structure and chromosomal assignment of human pulmonary surfactant proteolipid, SPL(pVal)

In hyaline membrane disease of premature infants, lack of surfactant leads to pulmonary atelectasis and respiratory distress. Hydrophobic surfactant proteins of Mr = 5,000-14,000 have been isolated from mammalian surfactants which enhance the rate of spreading and the surface tension lowering properties of phospholipids during dynamic compression. We have characterized the amino-terminal amino acid sequence of pulmonary proteolipids from ether/ethanol extracts of bovine, canine, and human surfactant. Two distinct peptides were identified and termed SPL(pVal) and SPL(Phe). An oligonucleotide probe based on the valine-rich amino-terminal amino acid sequence of SPL(pVal) was utilized to isolate cDNA and genomic DNA encoding the human protein, termed surfactant proteolipid SPL(pVal) on the basis of its unique polyvaline domain. The primary structure of a precursor protein of 20,870 daltons, containing the SPL(pVal) peptide, was deduced from the nucleotide sequence of the cDNAs. Hybrid-arrested translation and immunoprecipitation of labeled translation products of human mRNA demonstrated an Mr = 22,000 precursor protein, the active hydrophobic peptide being produced by proteolytic processing to Mr = 5,000-6,000. Two classes of cDNAs encoding SPL(pVal) were identified. mRNA of approximately 900 bases was identified on Northern analysis of fetal and adult RNA. Human SPL(pVal) mRNA was more abundant in the adult than in fetal lung. The SPL(pVal) gene locus was assigned to chromosome 8.     

Modified nucleotides in Bacillus subtilis tRNA(Trp) hyperexpressed in Escherichia coli.

In the present study, modified nucleotides in the B. subtilis tRNA(Trp) cloned and hyperexpressed in E. coli have been identified by TLC and HPLC analyses. The modification patterns of the two isoacceptors of cloned B. subtilis tRNA(Trp) have been compared with those of native tRNA(Trp) from B. subtilis and from E. coli. The modifications of the A73 mutant of B. subtilis tRNA(Trp), which is inactive toward its cognate TrpRS, were also investigated. The results indicate the formation of the modified nucleotides S4U8, Gm18, D20, Cm32, i6A/ms2i6A37, T54 and psi 55 on cloned B. subtilis tRNA(Trp). This modification pattern resembles the pattern of E. coli tRNA(Trp), except that m7G is missing from the cloned tRNA(Trp), probably on account of its short extra loop. In contrast, the pattern departs substantially from that of native B. subtilis tRNA(Trp). Therefore, the cloned B. subtilis tRNA(Trp) has taken on largely the modification pattern of E. coli tRNA(Trp) despite the 26% sequence difference between the two species of tRNA, gaining in particular the Cm32 and Gm18 modifications from the E. coli host. A notable difference between the isoacceptors of the cloned tRNA(Trp) was seen in the extent of modification of A37, which occurred as either the hypomodified i6A or the hypermodified ms2i6A form. Surprisingly, base substitution of guanosine by adenosine at position 73 of the cloned tRNA(Trp) has led to the abolition of the 2'-O-methylation modification of the remote G18 residue.     

Influence of plant domestication on plant-pollinator interactions: Floral attributes and floral visitor communities in wild and cultivated squash plants

Premise

Domestication of plant species results in phenotypic modifications and changes in biotic interactions. Most studies have compared antagonistic plant-herbivore interactions of domesticated plants and their wild relatives, but little attention has been given to how domestication influences plant-pollinator interactions. Floral attributes and interactions of floral visitors were compared between sister taxa of the genus Cucurbita (Cucurbitaceae), the domesticated C. moschata, C. argyrosperma ssp. argyrosperma and its wild progenitor C. argyrosperma ssp. sororia in the place of origin.

Methods

We conducted univariate and multivariate analyses to compare floral morphological traits and analyzed floral reward (nectar and pollen) quantity and quality between flowers of wild and domesticated Cucurbita taxa. Staminate and pistillate flowers of all three taxa were video recorded, and visitation and behavior of floral visitors were registered and analyzed.

Results

Most floral morphological characteristics of flowers of domesticated taxa were larger in both staminate and pistillate flowers. Staminate and pistillate flowers presented distinct correlations between floral traits and integration indices between domesticated and wild species. Additionally, pollen quantity and protein to lipid ratio were greater in domesticated species. Cucurbit pollen specialists, Eucera spp., had the highest probability of visit for all Cucurbita taxa.

Conclusions

We provide evidence that floral traits of domesticated and wild Cucurbita species experienced different selection pressures. Domesticated Cucurbita species may have more resources invested towards floral traits, thereby increasing attractiveness to pollinators and potentially plant reproductive success. Wild ancestor plant populations should be conserved in their centers of origin to preserve plant-pollinator interactions.     

Purification, characterization and ion binding properties of human brain S100b protein

Human brain S100b (beta beta) protein was purified using zinc-dependent affinity chromatography on phenyl-Sepharose. The calcium- and zinc-binding properties of the protein were studied by flow dialysis technique and the protein conformation both in the metal-free form and in the presence of Ca2+ or Zn2+ was investigated with ultraviolet spectroscopy, sulfhydryl reactivity and interaction with a hydrophobic fluorescence probe 6-(p-toluidino)naphthalene-2-sulfonic acid (TNS). Flow dialysis measurements of Ca2+ binding to human brain S100b (beta beta) protein revealed six Ca2+-binding sites which we assumed to represent three for each beta monomer, characterized by the macroscopic association constants K1 = 0.44 X 10(5) M-1; K2 = 0.1 X 10(5) M-1 and K3 = 0.08 X 10(5) M-1. In the presence of 120 mM KCl, the affinity of the protein for calcium is drastically reduced. Zinc-binding studies on human S100b protein showed that the protein bound two zinc ions per beta monomer, with macroscopic constants K1 = 4.47 X 10(7) M-1 and K2 = 0.1 X 10(7) M-1. Most of the Zn2+-induced conformational changes occurred after the binding of two zinc ions per mole of S100b protein. These results differ significantly from those for bovine protein and cast doubt on the conservation of the S100 structure during evolution. When calcium binding was studied in the presence of zinc, we noted an increase in the affinity of the protein for calcium, K1 = 4.4 X 10(5) M-1; K2 = 0.57 X 10(5) M-1; K3 = 0.023 X 10(5) M-1. These results indicated that the Ca2+- and Zn2+-binding sites on S100b protein are different and suggest that Zn2+ may regulate Ca2+ binding by increasing the affinity of the protein for calcium.     

Hippocampal Hypertrophy and Sleep Apnea: A Role for the Ischemic Preconditioning?

The full impact of multisystem disease such as obstructive sleep apnoea (OSA) on regions of the central nervous system is debated, as the subsequent neurocognitive sequelae are unclear. Several preclinical studies suggest that its purported major culprits, intermittent hypoxia and sleep fragmentation, can differentially affect adult hippocampal neurogenesis. Although the prospective biphasic nature of chronic intermittent hypoxia in animal models of OSA has been acknowledged, so far the evidence for increased ‘compensatory’ neurogenesis in humans is uncertain. In a cross-sectional study of 32 patients with mixed severity OSA and 32 non-apnoeic matched controls inferential analysis showed bilateral enlargement of hippocampi in the OSA group. Conversely, a trend for smaller thalami in the OSA group was noted. Furthermore, aberrant connectivity between the hippocampus and the cerebellum in the OSA group was also suggested by the correlation analysis. The role for the ischemia/hypoxia preconditioning in the neuropathology of OSA is herein indicated, with possible further reaching clinical implications.