In situ patterns of intracellular photosynthate allocation by sea ice algae in the Canadian high arctic

Summary A novel sampling/incubating device was used to determine the in situ patterns of intracellular photosynthate allocation by algae living in the bottom of annual sea ice in the Canadian arctic. During the seasonal decline of the bloom in late May and June, the average allocation pattern after 24 h incubation in the bottom 1 cm of ice (where the bulk of the algae are found) was 30.5% to low molecular weight materials, 10.6% to lipid, 48.8% to polysaccharide and 8.8% to protein. Allocation patterns were vertically stratified and light-dependent within the bottom ice community, with higher allocation to lipid in the upper, better-illuminated, strata. Chlorophyll-specific photosynthesis rates were extremely low (<0.031 gC·g Chl a ^–1·h^–1). Short incubations (ca. 1h) gave similar results to the 24 h incubations. The in situ allocation patterns were atypical of those normally expected for light-limited microalgae, but were consistent with a physiological response to inorganic nutrient limitation in the late stages of the bloom.     

Genetic mapping on the mouse X chromosome of human cDNA clones for the fragile X and Hunter syndromes.

Murine X-linked genes corresponding to the human Fragile X (FMR1) and Hunter syndrome (IDS) loci have been mapped in an interspecific backcross between B6CBA-Aw-J/A-Bpa and Mus spretus using human cDNA clones. Pedigree analysis of recombinants from a total of 248 backcross progeny favors a gene order of (Cf-9, Mcf-2)-(Fmr-1)-Ids-Gabra3-Rsvp. Gene order is conserved between the species, although no fragile site has been detected in the mouse in this region of the murine X chromosome.     

Synthesis of Glial Fibrillary Acidic Protein in Rat C6 Glioma in Chemically Defined Medium: Cyclic AMP-Dependent Transcriptional and Translational Regulation

Glial fibrillary acidic protein (GFA) expression was induced in rat C6 glioma in chemically defined medium by the addition of N6, O2'-dibutyryl cyclic AMP (dbcAMP). Induction was dependent on the increase in intracellular cyclic AMP (cAMP), which was linearly correlated with added dbcAMP. Contrary to GFA mRNA synthesis, which can be obtained by cAMP-dependent and -independent pathways, translation of mRNA into GFA was observed only above a cellular cAMP concentration of approximately 0.2 fmol/cell. dbcAMP stimulation did not affect the vimentin concentration, which remained at a low level, but changed the cellular morphology from a bipolar to a stellate shape. A similar morphological change was observed after stimulation of C6 with lipopolysaccharide (LPS). However, LPS did not significantly increase the intracellular concentration of cAMP and the LPS-induced mRNA was not translated into GFA. Our results indicate that GFA synthesis is regulated at the mRNA level and at the translational level and that a cAMP-dependent mechanism determines the ultimate synthesis of GFA by a yet unknown mechanism.     

Characterization of Palo Podrido, a Natural Process of Delignification in Wood

Chemical and morphological changes of incipient to advanced stages of palo podrido, an extensively delignified wood, and other types of white rot decay found in the temperate forests of southern Chile were investigated. Palo podrido is a general term for white rot decay that is either selective or nonselective for the removal of lignin, whereas palo blanco describes the white decayed wood that has advanced stages of delignification. Selective delignification occurs mainly in trunks of Eucryphia cordifolia and Nothofagus dombeyi, which have the lowest lignin content and whose lignins have the largest amount of β-aryl ether bonds and the highest syringyl/guaiacyl ratio of all the native woods included in this study. A Ganoderma species was the main white rot fungus associated with the decay. The structural changes in lignin during the white rot degradation were examined by thioacidolysis, which revealed that the β-aryl ether-linked syringyl units were more specifically degraded than the guaiacyl ones, particularly in the case of selective delignification. Ultrastructural studies showed that the delignification process was diffuse throughout the cell wall. Lignin was first removed from the secondary wall nearest the lumen and then throughout the secondary wall toward the middle lamella. The middle lamella and cell corners were the last areas to be degraded. Black manganese deposits were found in some, but not all, selectively delignified samples. In advanced stages of delignification, almost pure cellulose could be found, although with a reduced degree of polymerization. Cellulolytic enzymes appeared to be responsible for depolymerization. A high brightness and an easy refining capacity were found in an unbleached pulp made from selectively delignified N. dombeyi wood. Its low viscosity, however, resulted in poor resistance properties of the pulp. The last stage of degradation (i.e., decomposition of cellulose-rich secondary wall layers) resulted in a gelatinlike substance. Ultrastructural and chemical analyses of this substance showed the matrix to have no microfibrillar structure characteristic of woody cell walls but to still be rich in glucan.     

The effect of certain neurotransmitters on the analgesic action of enkephalinamide

The effect of noradrenaline, dopamine, acetylcholine and 5-hydroxytryptamine on the analgesic action of enkephalinamide was studied and it was demonstrated that catecholamines and acetylcholine potentiated the analgesic action of enkephalinamide, while the effect of serotonin varied depending on the dose used. These results suggest that catecholamines, acetylcholine and 5-hydroxytryptamine can modulate the analgesic action of enkephalins.     

Oxygen availability for bacterial growth with a flow microcalorimeter

Summary The enthalpy change associated with aerobic growth of E. coli K₁₂ on minimal media with succinic acid as sole carbon and energy source, determined by flow microcalorimetry (with aerobic mixing cell) was 733.01±15.32 kJ·mol^–1. Molar growth yield was 39.6±1.2 g·mol^–1. When the microcalorimetric growth was limited by oxygen supply, the power-time curve was altered and the total heat evolved was less than the enthalpy change. The maximum thermal output corresponding to a fully aerobic growth in the calorimetric cell was 1.89×10^–3 W·ml^–1. Thus, the oxygen uptake rate was about 0.39 ml O₂·h^–1·ml^–1.     

Effects of hexamethylene bisacetamide onα-fetoprotein,albumin, and transferrin production by two rat hepatoma cell lines

Summary α-Fetoprotein (AFP), albumin, and transferrin production by two rat hepatoma cell lines, McA-RH 7777 (7777) and McA-RH 8994 (8994), was determined after treatment with hexamethylene bisacetamide (HMBA, 2 to 6 mM). Radioimmunoassays were used to determine the levels of both secreted and intracellular AFP, albumin, and transferrin. Line 7777 normally produces large quantities of AFP and small quantities of albumin, thus resembling the less differentiated fetal liver with respect to the synthesis of these two proteins. Line 8994 normally produces small quantities of AFP and relatively larger amounts of albumin, thus resembling hepatic functions characteristic of a more differentiated state. After treatment with HMBA for a period of 28 to 96 h a threefold increase in AFP secretion by 7777 and a dose related increase in AFP, albumin, and transferrin secretion by 8994 were observed. In contrast, the secretion of albumin and transferrin in 7777 was inhibited by 60 and 40%, respectively, following treatment with HMBA. The intracellular concentrations of AFP in 7777 and AFP, albumin, and transferrin in 8994 were increased by treatment with HMBA indicating that HMBA is able to stimulate the synthesis of these proteins. The intracellular concentration of AFP, albumin, and transferrin in 7777, when expressed as a percentage of the extracellular concentration of these proteins, did not change significantly during HMBA treatment, indicating that the observed decrease in secreted albumin and transferrin by 7777 is due to decreased synthesis. Similarly, in Line 8994, when the intracellular concentration of the three proteins was expressed as percentage of the extracellular concentration, the only significant change observed was an increase in AFP after 72 h of HMBA (5 mM) treatment. The observed changes in the synthesis of AFP, albumin, and transferrin in both 7777 and 8994 after HMBA treatment were reversible, as judged by the return to control values upon removal of HMBA from the culture medium. Thus, HMBA stimulates synthesis of the oncofetal protein AFP, a result that appears to be independent of the stage of differentiation of the cell. However, its effect on the synthesis of albumin and transferrin are opposite in the two cell lines, suggesting that the regulation of the synthesis of these two proteins is controlled by factors or conditions that are dependent upon the stage of differentiation of the hepatoma cell lines.     

On the use of measures of structure and diversity in applied diatom ecology

Water managers ask for simple ecological indices as a tool for measuring the effectiveness of their activities. Diversity indices are often used as such tools. The concept of diversity is closely related to the nature of species-abundance distributions. There is empirical and theoretical evidence that diatom-assemblages have a species-abundance distribution of log-series type. Then the most appropriate diversity index is the dominance,i.e. the relative abundance of the commonest species. The number of species in a sample of fixed size of the assemblage is a useful additional index. It appears from some examples that these indices have no consistent relationships with the degree of water pollution. This in contrast to the species composition of the assemblages. (Complete paper published in: HAKANSSON, H. and J.GERLOFF, Eds., (1982). Festschrift Niels Foged. Diatomaceae III. Beiheft zur Nova Hedwigia     

Radiation-Sensitive Mutants of CAENORHABDITIS ELEGANS

Nine rad (for abnormal radiation sensitivity) mutants hypersensitive to ultraviolet light were isolated in the small nematode Caenorhabditis elegans. The mutations are recessive to their wild-type alleles, map to four of the six linkage groups in C. elegans and define nine new games named rad-1 through rad-9. Two of the mutants—rad-1 and rad-2—are very hypersensitive to X rays, and three—rad-2, rad-3 and rad-4—are hypersensitive to methyl methanesulfonate under particular conditions of exposure. The hypersensitivity of these mutants to more than one DNA-damaging agent suggests that they may be abnormal in DNA repair. One mutant—rad-5, a temperature-sensitive sterile mutant—shows an elevated frequency of spontaneous mutation at more than one locus; rad-4, which shows a cold-sensitive embryogenesis, reduces meiotic X-chromosome nondisjunction tenfold and partially suppresses some but not all mutations that increase meiotic X-chromosome nondisjunction; the viability of rad-6 hermaphrodites is half that of rad-6 males at 25°; and newly mature (but not older) rad-8 hermaphrodites produce many inviable embryo progeny. Meiotic recombination frequencies were measured for seven rad mutants and found to be close to normal.     

Quantitation of l-glycero-d-manno-heptose and 3-deoxy-d-manno-octulosonic acid in rough core lipopolysaccharides by partition chromatography

A partition chromatographic procedure utilizing a cationic exchange resin column in the Li⁺ form and 90% ethanol as the mobile phase was employed to quantify 3-deoxy-d-manno-octulosonic acid (KDO) and l-glycero-d-manno-heptose in the lipopolysaccharides (LPS) of R_e and R_dP^? rough mutants of Salmonella minnesota. In a standard mixture of monosaccharides, KDO eluted shortly after the void volume and heptose eluted after the neutral hexoses. Mild acid treatment of either the R_e or R_dP^? LPS with 0.16 n methanesulfonic acid in the presence of Dowex 50-X8 resin (H⁺ form) released more than 80% of the KDO residues within 15 min. The heptose of the R_dP^? LPS, first detected after 90 min of hydrolysis, increased gradually to a maximum level at 12 h. A secondary gradual increase in KDO became apparent during the heptose release. The weight contents of these two monosaccharides based upon aheir maximum values detected during hydrolysis were 20.3 ± 0.6% KDO, for the R_e LPS, and 13.8 ± 0.4% KDO and 12.0 ± 0.4% heptose, for the R_dP^? LPS. The relationship between the kinetics of release of KDO and heptose and the nature of the linkages involving these two monosaccharides are discussed.