Effect of dilution rate on eicosapentaenoic acid productivity ofPhaeodactylum tricornutum utex 640 in outdoor chemostat culture

Summary Eicosapentaenoic acid (EPA) volumetric productivity from an outdoor chemostat culture ofPhaeodactylum tricornutum UTEX 640 in a 50-l tubular photobioreactor varies with dilution rate, reaching a maximum of 47.8 mg l^–1 d^–1 at D=0.36 d^–1. Continuous culture at high dilution rates' is proposed as the most adequate operating mode to maximize polyunsaturated fatty acid production.     

Phenotype modulation in primary cultures of arterial smooth-muscle cells. Dual effect of prostaglandin E1

The effects of prostaglandin E1 (PGE1) on the phenotypic state of enzymatically isolated arterial smooth-muscle cells in primary culture were studied by transmission electron microscopy, thymidine autoradiography, and cell counting. Early in culture (day 0-2), PGE1 stimulated conversion of the cells from contractile (less euchromatic nucleus and cytoplasm dominated by myofilament bundles) to synthetic state (more euchromatic nucleus and cytoplasm dominated by cisternae of rough endoplasmic reticulum and a large Golgi complex). The rate of entrance of the cells into DNA synthesis and mitosis was also increased at this time. Later on (day 3-6), when the majority of the cells had entered synthetic state, PGE1 inhibited DNA synthesis and cellular proliferation. These observations indicate that the effect of prostaglandins on arterial smooth muscle is dual in nature and dependent on the state of differentiation of the cells.     

Responses in pigmentation and anti-oxidant expression in Arctic Daphnia along gradients of DOC and UV exposure

Responses in carapace melanization and expression of the majoranti-oxidant catalase (CAT) and glutathione transferase (GST)in Arctic Daphnia were assessed in enclosures along a gradientof dissolved organic carbon (DOC). This gradient was createdby adding freeze-dried humic matter to 2 m³ UV-transparent enclosures,yielding final nominal concentrations of 1, 2.5, 5 and 10 mgC l^-1. The UV attenuation was strongly affected by additionsof DOC, and attenuation coefficients at 320 nm increased from3.0 in the control to approximately 3.5 and 11.0 m^-1 in the1 and 10 mg DOC treatments respectively. Most Daphnia showedpronounced carapace melanization, and the absorbance of short-waveradiation through the carapace was strongly related to the degreeof melanization. Nevertheless, the different UV climate in theenclosures did not cause any short-term adaptation in Daphniapigmentation over a 3 week period. The levels of CAT and GSTwere assessed over time in the control and at 10 mg DOC. Theseenzymes displayed opposite patterns, with somewhat lower activitiesof CAT at low DOC (control) relative to 10 mg DOC, while theopposite was found for GST. There was also a significant negativecorrelation between CAT and solar irradiation for GST in bothbags, while no effects were found for GST.     

The influence of alkyl pyridinium sponge toxins on membrane properties, cytotoxicity, transfection and protein expression in mammalian cells

The ability of two alkyl pyridinium sponge toxin preparations (poly-APS and halitoxin) to form transient pores/lesions in cell membranes and allow transfection of plasmid cDNA have been investigated using HEK 293 cells. Poly-APS and halitoxin preparations caused a collapse in membrane potential, reductions in input resistance and increased Ca²⁺ permeability. At least partial recovery was observed after poly-APS application but recovery was more rarely seen with halitoxin. The transfection with plasmid cDNAs for an enhanced green fluorescent protein (EGFP) and human tumour necrosis factor receptor 2 (TNFR2) was assessed for both toxin preparations and compared with lipofectamine. Stable transfection was achieved with poly-APS although it was less efficient than lipofectamine. These results show that viable cells transfected with alien cDNA can be obtained using novel transient pore-forming alkyl pyridinium sponge toxins and a simple pre-incubation protocol. This provides the first proof of principle that pore-forming alkyl pyridinium compounds can be used to deliver cDNA to the intracellular environment without permanently compromising the plasma membrane.     

In vivo protein synthesis from 14C-substrates in porcine tissues during the transition to postnatal development

[2-14C] leucine, [1-14C] alanine, [1-14C] glucose, [1-14C] lactate and [1-14C] pyruvate utilization in the protein synthesis has been studied in vivo at early stages of postnatal development of piglets. It has been established, that during the first 24 hours after birth the protein synthesis intensity, judging by [2-14C] leucine incorporation, in liver, skeletal muscle, duodenal wall and subcutaneous tissue of piglets increases 5, 7, 6.5 and 2.1 times respectively. At the age of 1-2 h the radioactive carbon incorporation from [1-14C] glucose into the brain proteins is more pronounced than into the proteins of liver and skeletal muscle. During the first days of life the intensity of the label incorporation from [1-14C] glucose into liver and skeletal muscle proteins of piglets is enhanced, whereas in brain it remains at the same level. The degree of 14C carbon incorporation from [1-14C]-alanine, [1-14C] pyruvate and [1-14C] lactate into the liver and skeletal muscle proteins of 5-days-old piglets is approximately the same, 14C substrates of protein synthesis in brain and subcutaneous adipose tissue having some peculiarities.     

Effect of some antidiuretic agents on the polyuria-polydipsia provoked by alcohol]

The authors have studied in the dog--normal or diabetic insipidus after hypothalamic lesion--submitted to oral ingestion of ethanol the effects of a few antidiuretic drug: chlorpropamid, atromid-S, carbamazepin and carisoprodol. The carisoprodol only can reduce the diuresis and the drinking provoked by ethanol.     

The effect of storage on the frequency of dominant lethals in Drosophila melanogaster

Summary Ethylenimine, ethyl methanesulfonate and formaldehyde have been shown to produce a storage effect in dominant lethality in Drosophila melanogaster.     

Effect of different disintegration techniques and media on yield and appearance of isolated nuclei

Cell nuclei have been released from various plant tissues (barley leaves, roots and embryos, tobacco leaves and tissue cultures,Vicia faba roots,Arabidopsis thaliana leaves) by several homogenization methods and the optimal method was established for each tissue. The effect of the composition of isolation medium on the yield and appearance of isolated nuclei was also studied. Longer incubation withn-octanol increases the yield considerably in most cases. Low concentrations of osmoticum increase the yield and their adverse effect on the integrity of nuclei is of little significance. Gum arabic has a favourable effect on nuclei isolation from roots only.