U5 small nuclear ribonucleoprotein: RNA structure analysis and ATP-dependent interaction with U4/U6.

To understand how the U5 small nuclear ribonucleoprotein (snRNP) interacts with other spliceosome components, its structure and binding to the U4/U6 snRNP were analyzed. The interaction of the U5 snRNP with the U4/U6 snRNP was studied by separating the snRNPs in HeLa cell nuclear extracts on glycerol gradients. A complex running at 25S and containing U4, U5, and U6 but not U1 or U2 snRNAs was identified. In contrast to results with native gel electrophoresis to separate snRNPs, this U4/U5/U6 snRNP complex requires ATP to assemble from the individual snRNPs. The structure of the U5 RNA within the U5 snRNP and the U4/5/6 snRNP complexes was then compared. Oligonucleotide-targeted RNase H digestion identified one RNA sequence in the U5 snRNP capable of base pairing to other nucleic acid sequences. Chemical modification experiments identified this sequence as well as two other U5 RNA sequences as accessible to modification within the U5 RNP. One of these regions is a large loop in the U5 RNA secondary structure whose sequence is conserved from Saccharomyces cerevisiae to humans. Interestingly, no differences in modification of free U5 snRNP as compared to U5 in the U4/U5/U6 snRNP complex were observed, suggesting that recognition of specific RNA sequences in the U5 snRNP is not required for U4/U5/U6 snRNP assembly.     

Interaction of non-classical detergents with the mitochondrial porin. A new purification procedure and characterization of the pore-forming unit

The effect of different families of detergents on the solubilization and purification of the pore-forming protein (porin) of the mitochondrial outer membrane of bovine heart was investigated in detail. With Tritons, dimethylamine oxides and zwittergents, porin solubilization with respect to total mitochondrial membrane protein was more efficient with the more hydrophobic members of each series. With most detergents the protein eluted as protein-detergent micelles in the void volume of hydroxyapatite/celite columns. In contrast, the protein was bound to the column material and was eluted after the addition of salt to the elution buffer when the detergents octylglucoside, zwittergent Z-314 and lauryl(dimethyl)-amine oxide were used. The protein purified in the presence of the latter detergent had a higher pore-forming activity in lipid bilayer membranes compared to porin isolated in the presence of Triton X-100. The binding of porin to the hydroxyapatite/celite column was used to study the lipid content of the active pore-forming complex. The analysis revealed that the complex contained no phospholipid but rather five molecules of cholesterol/polypeptide chain.     

Glyphosate Induces 3-Deoxy-d-arabino-Heptulosonate 7-Phosphate Synthase in Potato (Solanum tuberosum L.) Cells Grown in Suspension Culture

The activity of the first enzyme of the shikimate pathway, 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase, varies during the growth cycle of Solanum tuberosum L. cv superior cells in suspension culture. Maximum specific enzyme activity was observed midway through the linear phase of growth. When mid-log phase cells are exposed to glyphosate, the specific activity of the enzyme increases severalfold within 24 hours. The glyphosate-induced increase in enzyme activity is due to an increase in the amount of enzyme as determined by immunoblotting. Glyphosate (up to 2 millimolar) has no effect on the enzyme activity in vitro. Dehydroquinate synthase, the second enzyme of the shikimate pathway, is not induced by glyphosate.     

Label-fracture of cell surfaces by replica staining

We introduce replica-staining label-fracture, a method for the cytochemical mapping of membrane surfaces. This method is a corollary of the rationale of label-fracture (Pinto da Silva and Kan, 1984: J Cell Biol 99:1156). After freeze-fracture the exoplasmic halves of the membrane remain attached to the replica. We show that cytochemical labeling of cell surfaces can be performed by direct post-fracture staining of freeze-fracture replicas. This new variant of label-fracture leads to miniaturization of labeling procedures and allows standardization of labeling conditions and simultaneous processing of different specimens.     

Morphology and Taxonomy of <Emphasis Type="Italic">Apristurus longicephahis</Emphasis> (Lamniformes,Seyliorhinidae)

Data on the individual variation and changes with growth in proportions and morphology are presented for the poorly known Apristurus longicephalus, and compared with those of other species. A. longicephalus is concluded to be a distinct species without synonyms, characterized by its long snout, widely separate nostrils, long caudal fin, short abdomen, very sparse teeth, and low number of monospondylous vertebrae. It is a species of small size, maturing at about 42 cm in total length.     

Scale Growth and Squamation Chronology for the Laboratory-Reared Hermaphroditic Fish <Emphasis Type="Italic">Rivulus marmoratus</Emphasis> (Cyprinodontidae)

Scale morphology, growth and the squarnation chronology are described for the hermaphroditic fish Rivulus marmoratus reared in the laboratory. The scales are round or oval shaped cycloid type, and their sizes are about 0.3–1.0 mm in diameter. The number of ridges increases more rapidly relative to the body growth of the fish in early stages, but this increase is proportionate to growth subsequently. Three loci of scale development have been identified. The scales first appeared on the center of the parietal region at 8 days after hatching. The second locus of scale formation was on the lateral line of the posterior end of the caudal peduncle. A third locus was later observed on the lower right corner of the operculum: The final squamation was completed at 6 weeks after hatching.     

DNA analysis of malignant effusions. Comparison with cytologic diagnosis and carcinoembryonic antigen content.

Twenty-three consecutive malignant effusions from 19 patients submitted for cytologic examination were analyzed for carcinoembryonic antigen (CEA) content and for DNA analysis by flow cytometry. The study was undertaken to determine if the addition of DNA analysis would improve the sensitivity of cytologic diagnosis and CEA assay. CEA examination was performed on Papanicolaou-stained smears and hematoxylin-and-eosin-stained cell blocks. Final diagnoses were correlated with histologic examination (four patients), clinical and radiologic studies, and follow-up. The malignant effusions in 19 patients were secondary to carcinoma of the breast (5), lung (5), ovary (1), endometrium (1), mucinous carcinoma of the colon (1), unknown primary (1), extraovarian papillary carcinoma (1), mesothelioma (2) and large cell lymphoma (2). The sensitivity of cytologic diagnosis was 100% and specificity 100%. DNA aneuploidy, defined as the presence of two separate peaks in the histogram, was present in 7 of 23 fluids (sensitivity, 30%). Four fluids had insufficient cells for analysis, and one histogram showed debris (following chemotherapy). DNA aneuploidy was detected in effusions secondary to carcinoma of the breast (4), lung (1) and lymphoma (2). Using 5 ng/mL as the cutoff, the sensitivity of CEA was 68%. DNA analysis of cells in malignant effusions is less sensitive than cytologic diagnosis, and CEA assay and is not recommended for routine use in the diagnosis of malignant effusions.     

Nutrient budgets in a dry heathland watershed in northeastern Spain

Dissolved nutrient inputs in bulk precipitation and outputs in streamwater were measured during 3 years of contrasting hydrological conditions in a 6.3-ha, grazed heathland watershed on schists in the Montseny mountains (NE Spain), drained by an intermittent stream. On average, 39% of the precipitation became streamflow. Bulk precipitation delivered positive net alkalinity (mean 0.22 keq/ha/yr), sulphate input was moderate (9.0 kg SO₄-S/ha/yr), and the mean input of inorganic N was not exceptionally high (6.6 kg/ha/yr). Ion concentrations were relatively low in streamwater; SO₄ ^2- was the dominant anion. Most concentrations in streamwater varied seasonally, with maxima in late summer or early autumn and minima in spring. This pattern probably resulted from increased availability of ions for leaching due to decomposition of organic matter and chemical weathering during the warm period. Nitrate concentrations were relatively high in winter and dropped sharply in early spring, probably because of biological uptake. Annual element outputs in streamwater varied between years and seemed to be controlled by both the amount of annual streamflow and its seasonal distribution. Annual inputs exceeded outputs for dissolved inorganic N. The watershed accumulated H⁺ and Ca²⁺, had net losses of Na⁺ and Mg²⁺, and was close to steady state for K⁺, SO₄ ^2-, Cl^- and alkalinity. The chloride budgets gave no evidence of substantial dry deposition in this system. The cationic denudation rate was negative (-0.14 keq/ha/yr) because Ca²⁺ retention was higher than net exports of Na⁺ and Mg²⁺ from silicate weathering. Low nutrient export and little production of alkalinity suggest that this watershed has a low buffering capacity.     

Cultural characteristics and zearalenone production by strains of<Emphasis Type="Underline">Fusarium</Emphasis> from wheat

Conidia of the speciesFusarium culmorum /W.G.Sm./ Sacc. andFusarium graminearum Schwabe are characterized by variability in zearalenone production and dimensions depending on the substrate. The sporulation of isolates from some wheat eultivars have been deprived in vivo and in vitro in the first passage, but not their pathogenicity and toxic metabolites production. Nonsporulating strains produced lower quantités of zearalenone than sporulating ones. Liquid filtrates of such nonsporulating strains had a high phytotoxic effect on wheat caryopses. The crystalline toxin DAS /0,25 ug/ml/ had low phytotoxic effect on wheat caryopses.     

Cumulation of mycotoxins in maize cobs infected with<Emphasis Type="Italic">Fusarium gramihearum</Emphasis>

Maize cobs withFusarium ear rot were collected at 1986 season and five infected byFusarium graminearum were analyzed for presence of triohothecenes and zearalenone. Collected material was subsampled forFusarium damaged kernels and corresponding axial stems and healthy looking kernels. All investigated cobs contained deoxynivalenol (DON) (range 18.0–131.5 mg/kg) and zearalenone (ZEA) (range 0.38–2.17 mg/kg), in four cobs 15-acetyl-deoxynivalenol (15-AcDON) (range 5.2–6.2 mg/kg) was present and two cobs besides three all metabolites contained 3-acetyl-deoxynivalenol (3-AcD0N) (range 0.5–0.8 mg/kg).The average of individual toxins amount in axial stems: in mg/kg was equal to: DON — 110.36, ZEA — 4.57, 15-AcD0N — 16.66, and 3-AcD0N — 1.32.Fusarium damaged kernels contained in average the following amount (mg/kg) of: DON 77.00, ZEA 0.98, 15-AcD0N 3.78 and 3-AcD0N 0.06. Healthy looking kernels contained DON 1.96 mg/kg and ZEA 0.07 mg/kg only. Cooccurrence of 3-AcDON and 15-AcDON in two samples was an interesting finding. The amount of DON in total cob was highly correlated (r = 0.94) with percentage ofFusarium damaged kernels in given ear.