Structure of 7S seed globulin from Phaseolus vulgaris L. in solution

The structure of the 7S globulin from Phaseoulus vulgaris L in dilatue solutions has been studied by small angle X-ray scattering (SAXS), by quasi-elastic light scattering (Q ELS), by circular dichroism spectroscopy (c.d.), and by precise density measurements. The molar mass, the radius of gyration, the volume, the maximum dimension and the diffusion coefficient were determined as M = 1.45 × 10⁵ g mol⁻¹, R_G = 4.05 nm, V = 300- nm³, L = 13.0 nm and D_20,w⁰ = 4.5 × 10⁻⁷ cm² s⁻¹, respectively. The molecule has an asymmetrical shape with the dimensions 12.5 × 12.5 × 3.75 nm. The secondary structure of the 7S globulin is characterized by a small portion of -helical structure (14%) and a marked content of β-structure (18%).     

Molecular cloning of pea mRNAs encoding a shoot-specific polypeptide and light-induced polypeptides

Summary The molecular cloning of cDNA corresponds to pea seedling mRNA sequences encoding a shoot-specific polypeptide, the small subunit of the ribulose 1,5 biphosphate carboxylase and a component of the light-harvesting chlorophyll a/b complex is described. cDNA prepared from polysomal poly(A)RNA of light-grown shoots was enriched for shoot-specific and light-induced sequences by heterologous liquid hybridization with mercurated polysomal poly(A)RNA of dark-grown roots, followed by sulfhydryl chromatography. Cloned shoot-specific sequences were identified by 2D electrophoretic analysis of hybrid release translation products. The cloned shoot-specific sequence corresponded to a mRNA of 850 nt present both in light-and dark-grown shoots, and produced anin vitro translation product of M_r27 500 and isoelectric point of 4.7.     

Macrofaunal community types in ponds and small lakes (Overijssel,The Netherlands)

A survey was carried out at 157 sites, situated in pools and small lakes in the province of Overijssel (The Netherlands), to describe the macro-invertebrate community and their environment. A total of 61 environmental viriables was measured at each sampling site. The main aim was to described a regional ecological typology of ponds and small lakes. Multivariate analysis techniques are appropriate in data analysis for typological purposes. Different multivariate analysis techniques (FLEXCLUS, NODES, DCCA, PCA) were used in combination with ecological information on individual taxa to derive and describe site groups in terms of taxon composition and mean environmental conditions. The resulting site groups were termed cenotypes. Nine cenotypes were distinguished among the ponds and small lakes. The main differences between the cenotypes were related to duration of drought, acidity, morphology and nutrient load. In particular, the four cenotypes within the group of stagnant, pH-neutral ponds/lakes showed an overlap in taxon composition. These cenotypes represent a web-shaped continuum dominated by dimensions (relation of width to depth), nutrient load, and bottom composition (especially mesotrophic peat). The most important anthropogenic processes are acidification, eutrophication, and changes in the original hydrology.     

Storage of embryonically transcribed poly(A) RNA and its utilization during metamorphosis of the hydroidHydractinia echinata

Summary The formation of tentacles and stolons during metamorphosis is severely disturbed if inhibitors of mRNA metabolism are applied during certain phases of development. The periods of sensitivity to -amanitin are late gastrulation and the disk stage of metamorphosis. A cordycepin sensitive phase exists during the first hour of metamorphosis. In all drug sensitive phases an enhanced poly(A) synthesis is found indicating increased mRNA metabolism in these stages. Pulse-chase experiments show that planula larvae store a poly(A)-rich RNA population sedimenting between 28–18s. These long living molecules are of embryonic origin, are located in RNP particles and are degraded during metamorphosis. The particles in question appear to be stored mainly in interstitial cells. In early metamorphosis no uridine is incorporated but labelled poly(A) is added to preexisting molecules.     

Bombesin production by human small cell carcinoma of the lung

A series of continuous cell lines of human small cell carcinoma of the lung (SCCL) have been evaluated for the production of bombesin (BN). In early established cultures BN was detected in the medium of 9 out of 11 cell lines and in 6 out of 7 cell homogenates examined. Levels in the medium were frequently higher in cultures of later passages compared to earlier passages of the same line and low levels developed in the two previously negative cell lines. Plasma concentrations were greater than 80 pmol/l in 2 out of 27 (7%) randomly selected patients with SCCL. A culture (DMS 406) established from the tumor of a patient with the highest plasma level (1240 pmol/l) was the highest producer in vitro. The results indicate that BN, which has been demonstrated immunocytochemically to be present in normal bronchial mucosal cells, is frequently produced by SCCL in vitro but elevated plasma levels are infrequently found in patients with this neoplasm.     

Pseudouridine residues in the 5′-terminus of uridine-rich nuclear RNA I (U1 RNA)

The primary nucleotide sequence was reported earlier for U1 RNA (Reddy et al, (1974) J. Biol. Chem. $\text{249}$, 6486–6494), an snRNA implicated in splicing of HnRNAs. In view of the presence of homologous pseudouridine (ψ) residues in 5′-ends of several highly conserved U-snRNAs and the recent report of modified bases in the U1 RNA structure (Branlant et al, (1980) Nucleic Acids Res. $\text{8}$, 4143–4154) a study was made for the presence of ψ and other modified nucleotides in the 5′-end of the U1 RNA. Identification of ψ residues at positions 6 and 7, shows the 5′-sequence of U1 RNA is: m₃², 2,7 GpppAm-Um-A-C-ψ-ψ-A-C-C-U-G-G-C-A-G-G-G-G-A-G-A-U-A-C. The ψ residues in place of U at positions 6 and 7 may affect the binding of U1 RNA at intron-exon splice junctions.     

The relation between cell proliferation,differentiation and ultrastructural development in rat intestinal epithelium

Summary The ultrastructural development of the principal cells in rat small intestine was studied by morphometric analyses in relation to the exact cell position along crypt and villus. From the bottom to the tip of the crypt, a gradual increase occurred in absolute size of the total cell, the cytoplasm, the terminal web and of nearly all cell organelles. Also, the relative size of the cytoplasm, mitochondria, microvilli and endoplasmic reticulum increased during crypt cell differentiation. No sudden changes in ultrastructure were observed in the so-called critical decision zone, normally located halfway up the crypt where the proliferative activity ceases. At the crypt-villous junction a 1.4–3 fold increase in cell size, cytoplasm, terminal web and of most organelles was noted. Expansion of the proliferative cell compartment over the total length of the crypt as occurs during recovery after a low X-irradiation dose (72 h after 400 R) does not affect the normal development of cellular ultrastructure. These findings are discussed in relation to biochemical and cell kinetic data.     

Crystal Structures of α-Crystallin Domain Dimers of αB-Crystallin and Hsp20

Small heat shock proteins (sHsps) are a family of large and dynamic oligomers highly expressed in long-lived cells of muscle, lens and brain. Several family members are upregulated during stress, and some are strongly cytoprotective. Their polydispersity has hindered high-resolution structure analyses, particularly for vertebrate sHsps. Here, crystal structures of excised α-crystallin domain from rat Hsp20 and that from human αB-crystallin show that they form homodimers with a shared groove at the interface by extending a β sheet. However, the two dimers differ in the register of their interfaces. The dimers have empty pockets that in large assemblies will likely be filled by hydrophobic sequence motifs from partner chains. In the Hsp20 dimer, the shared groove is partially filled by peptide in polyproline II conformation. Structural homology with other sHsp crystal structures indicates that in full-length chains the groove is likely filled by an N-terminal extension. Inside the groove is a symmetry-related functionally important arginine that is mutated, or its equivalent, in family members in a range of neuromuscular diseases and cataract. Analyses of residues within the groove of the αB-crystallin interface show that it has a high density of positive charges. The disease mutant R120G α-crystallin domain dimer was found to be more stable at acidic pH, suggesting that the mutation affects the normal dynamics of sHsp assembly. The structures provide a starting point for modelling higher assembly by defining the spatial locations of grooves and pockets in a basic dimeric assembly unit. The structures provide a high-resolution view of a candidate functional state of an sHsp that could bind non-native client proteins or specific components from cytoprotective pathways. The empty pockets and groove provide a starting model for designing drugs to inhibit those sHsps that have a negative effect on cancer treatment.