Metabolic Costs of Feeding Predictively Alter the Spatial Distribution of Individuals in Fish Schools

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Three AtCesA6‐like members enhance biomass production by distinctively promoting cell growth in Arabidopsis

Cellulose is an abundant biopolymer and a prominent constituent of plant cell walls. Cellulose is also a central component to plant morphogenesis and contributes the bulk of a plant's biomass. While cellulose synthase (CesA) genes were identified over two decades ago, genetic manipulation of this family to enhance cellulose production has remained difficult. In this study, we show that increasing the expression levels of the three primary cell wall AtCesA6‐like genes (AtCesA2, AtCesA5, AtCesA6), but not AtCesA3, AtCesA9 or secondary cell wall AtCesA7, can promote the expression of major primary wall CesA genes to accelerate primary wall CesA complex (cellulose synthase complexes, CSCs) particle movement for acquiring long microfibrils and consequently increasing cellulose production in Arabidopsis transgenic lines, as compared with wild‐type. The overexpression transgenic lines displayed changes in expression of genes related to cell growth and proliferation, perhaps explaining the enhanced growth of the transgenic seedlings. Notably, overexpression of the three AtCesA6‐like genes also enhanced secondary cell wall deposition that led to improved mechanical strength and higher biomass production in transgenic mature plants. Hence, we propose that overexpression of certain AtCesA genes can provide a biotechnological approach to increase cellulose synthesis and biomass accumulation in transgenic plants.     

Entry of adenovirus 2 into HeLa cells

Adenovirus 2 (Ad2) uncoating was analyzed as the destabilization of virions which renders the parental genome sensitive to DNase treatment. This event demonstrated a strong temperature dependence, and an Arrhenius plot of initial uncoating rates revealed an inflection point at around 16 degrees C. Activation energies of 331 kJ/mol below and 88 kJ/mol above this temperature were obtained for the uncoating process. Penetration of Ad2 through the plasma membrane was completely inhibited by sodium azide, whereas uncoating was only slightly influenced. This indicated that uncoating had already taken place at the outside of the plasma membrane. Incubations of Ad2 with isolated plasma membranes and cell homogenates showed that intact and metabolizing cells were required for uncoating. We further suggest, based on the inhibitory patterns of EDTA, EGTA, dansylcadaverine, and dithiothreitol, that this destabilization of virions follows upon reorganization in the plasma membrane. In the electron microscope the involvement of coated vesicles was shown for the initial uptake of virions, possibly followed by the engagement of acidic vesicles as judged from the effects of lysosomotropic agents on gene expression. The vectorial transport of virions from the plasma membrane to the nucleus was not affected by reagents interfering with the cytoskeletal system. Consequently, we propose that Ad2 virions are internalized by adsorptive endocytosis.     

Enchytraeids, lumbricids and soil arthropods in a northern deciduous woodland – a quantitative study

Soil/litter inhabiting annelids and arthropods were studied for one year in a mesic deciduous woodland, Andersby ängsbackar, one of the most northerly areas in Sweden to possess unbroken oak/hazel vegetation. Lumbricidae, Enchytraeidae, Collembola, Acari, Coleoptera, Diptera and Araneae were important faunal groups with regard to abundance, biomass and respiratory metabolism. Annual mean biomass (8 g dw m⁻²) and respiration (450 kJ m ⁻² yr⁻¹) of the joint annelid and arthropod community were dominated by lumbricids (76 and 50%, respectively). The biomass and respiration of the annelids and arthropods at Andersby were lower than in some other oak forests in northwestern Europe, probably because of lower soil temperature, lower litter supply and because some lumbricid and diplopod species were at their northern border of distribution.
Of the annual respiration, saprovores, fungivores, carnivores and root-feeders contributed 65, 19, 14 and 1.5%, respectively. The saprovore percentage was lower at Andersby than at other mull sites compared, probably as an effect of the northern climate, which might favour microbial saprovory. The fungivore and carnivore percentages were higher, which might be due to the presence of a litter layer throughout the year.     

Muddy odour: a problem associated with extreme eutrophication

The results of a 4-year study in a hypereutrophic bay, Kaupunginselkä Bay at Porvoo on the south coast of Finland, indicated a significant correlation between muddy odour in bream (Abramis brama) and the amount of the blue-green alga Oscillatoria agardhii in the phytoplankton. This algal strain has previously been shown to produce the muddy-smelling compound geosmin. The numbers of muddy-smelling actinomycetes in the water and sediments of the study area were not clearly related to muddy odour in fish, nor to phytoplankton biomass. In the hypereutrophic L. Tuusulanjärvi, muddy odour in bream and pikeperch (Stizostedion lucioperca) was also related to the amounts of blue-green algae in the phytoplankton.     

Differentiation between bronchodilation and universal adenosine antagonism among xanthine derivatives

Relaxant effects and adenosine-antagonism of 3-propyl-xanthine (enprofylline) and 10 different methyl-xanthines were examined in isolated guinea-pig tracheas. The chemical structural requirements for tracheal relaxation were found to be different from those for adenosine antagonism by the xanthine derivatives. All xanthines produced relaxation: Enprofylline was about 5 times more potent than theophylline. However, only xanthines with a methyl in the 1-position consistently antagonized the relaxant effect of adenosine. --Theophylline over a wide range of concentrations (30-900 microM) produced a concentration dependent and surmountable antagonism at nervous adenosine receptors (isolated guinea-pig myenteric-plexus preparations). The same concentrations of enprofylline were almost devoid of antagonism at these adenosine receptors. In mice theophylline (6-24 mg/kg given intraperitoneally) dose-dependently increased locomotor activity while enprofylline (2-48 mg/Kg) was without effect on behaviour. "Non-blocking" xanthines such as enprofylline may be potent bronchodilators but lack many theophylline-like actions. We, therefore, forward the hypothesis that universal adenosine antagonism is both unnecessary and undesirable with xanthine antiasthmatics.     

Total cortisol and L/S-ratio in amniotic fluid in late pregnancies complicated by diabetes mellitus

68 samples of amniotic fluid from 47 women with varying severity of diabetes mellitus and 48 samples from 43 normal women were obtained in the 31st to 40th week of pregnancy before onset of labour. The concentration of total cortisol and the L/S-ratio in amniotic flud were determined and related to gestational age. There was a continous rise of total cortisol with advancing gestational age in the diabetic pregnancies similar to that found in normal pregnancy. Diabetic pregnancies were associated with slightly lower amniotic fluid cortisol levels without significant difference to values found in normal pregnancy. The severity of the disease did not affect the cortisol levels in amniotic fluid. There was no correlation between total cortisol levels and L/S-ratios in amniotic fluid. Determination of total cortisol in amniotic fluid can thus not replace measurements of L/S-ratios to predict fetal lung maturation.     

Purification and characterization of an early protein (E14K) from adenovirus type 2-infected cells.

One adenovirus type 2 (Ad2) early protein, with an apparent molecular weight of 14,000 in sodium dodecyl sulfate-polyacrylamide gels (E14K), was purified to homogeneity. Purification involved fractionation of cytoplasmic extracts, precipitation at low pH, and DEAE-cellulose, phosphocellulose, and hydroxylapatite chromatography. The yield was around 12 microgram of purified protein per 10(9) HeLa cells. The two Ad2 DNA binding proteins with molecular weights of 75,000 and 45,000 (E75K and E45K) were purified by the same procedure. Tryptic peptide analyses indicated that the E14K protein is unrelated to the DNA binding proteins. The purified E14K protein has a high content of basic amino acids and a sedimentation coefficient of 5.5S in the native state, corresponding to a molecular weight of around 95,000. Pulse-chase experiments suggest that the E14K polypeptide is a primary translation product. Immunoprecipitation with a monospecific antiserum against the E14K protein revealed that it is exclusively localized in the cytoplasm of infected cells. E14K started to be synthesized at 2 hpostinfection, with a maximal rate of synthesis at 4 to 6 h postinfection. Immunoprecipitation of cell extracts from four different Ad2-transformed hamster embryo cell lines revealed that only one (Ad2HE4) of them expresses this protein. The adenovirus-simian virus 40 hybrid virus (Ad2ND1) does not express this protein, suggesting that the gene for the E14K protein is located in the part of the Ad2 genome which is deleted in this hybrid virus.     

Isoelectric points of spinach thylakoid membrane surfaces as determined by cross partition

The isoelectric points of unbroken chloroplast lamellae and various subchloroplast fractions, including a preparation of inside-out thylakoids, have been determined using aqueous two-phase systems containing dextran and charged polyethylene glycol. When the amounts of material in the top phase in a phase system with the positively charged trimethylamino polyethylene glycol are plotted against pH the curve intersects the corresponding curve obtained from phase systems with the negatively charged polyethylene glycol sulfonate. This cross-point can be correlated with the isoelectric point of the material.The cross-point for unbroken chloroplast lamellae was found to be around pH 4.7. Mechanical disintegration lowered the cross-point to around pH 4.4, probably because of exposure of new membrane surfaces. The disintegrated chloroplasts were fractionated by differential centrifugation to separate the grana and stroma lamellae. The stroma lamellae vesicles showed the same isoelectric point as the unbroken lamellae, while a cross-point at pH 4.3 was obtained for the grana-enriched fraction. For thylakoid membranes destacked under low salt conditions the cross-point was 0.3 pH unit lower than for membranes originating exclusively from the stroma lamellae. The most acidic cross-point (pH 4.1) was observed for the fraction enriched in inside-out grana thylakoids. It is suggested that the differences in isoelectric point between various subchloroplast fractions reflect a heterogeneous arrangement of surface charge along and across the thylakoid membrane.     

Interrelations between cyclic AMP, cyclic GMP and contraction in guinea pig gallbladder stimulated by cholecystokinin.

The changes in isometric tension and in concentrations of cyclic AMP and cyclic GMP in guinea pig gallbladder muscle induced by the C-terminal octapeptide of cholecystokinin (C8-CCK) were studied before and after the addition of indomethacin 3 × 10^?6 g/ml. The contractile response to the hormone was not affected by indomethacin, nor was the associated decrease in cyclic AMP concentration. However, indomethacin completely prevented the increase in cyclic GMP following addition of C8-CCK. The results suggest that in isolated guinea pig gallbladder, cyclic GMP is not essential for the C8-CCK-induced decrease in cyclic AMP concentration, and that the contractile response induced by the hormone is independent of this nucleotide.