Between beanbag genetics and natural selection

The encounter between the Darwinian theory of evolution and Mendelism could be resolved only when reductionist tools could be applied to the analysis of complex systems. The instrumental reductionist interpretation of the hereditary basis of continuously varying traits provided mathematical tools which eventually allowed the construction of the Modern Synthesis of the theory of evolution.When genotypic as well as environmental variance allow the isolation of parts of the system, it is possible to apply Mendelian reductionism, that is , to treat the phenotypic trait as if ti causally determined by discrete genes for the trait. howeverm such a beanbag genetics approach obscures the system's eye-view. The concept of heritability, defined as the proportion of the total phenotypic variance due to (additive) hereditary variation, asserts that genetic elements have discrete effects; but by relating to the genotypic variance, it avoids the trap of reffering to genes for characters.     

Preliminary studies on the genetic variability of six Hungarian common carp strains using microsatellite DNA markers

Genetic variation in six Hungarian common carp (Cyprinus carpio L.) strains was evaluated using 12 microsatellite loci. The domesticated (Tatai, Biharugrai and Szarvasi) strains were derived from fish farms. Two of wild strains (Tiszai and Dunai) were sampled from brood stocks maintained at fish farms for breeding, and Kis-Balatoni wild carp were sampled from the Small Balaton Lake. Pairwise Fst-values (0.013–0.161) were highly significant (p0.0001), demonstrating differentiation among strains. The mean number of alleles ranged between 3.9 and 8.2. Overall mean observed heterozygosity was lower (0.557) than the mean expected heterozygosity (0.700). By strain, the only exception to this trend was the Dunai (Danubian), which showed higher mean observed heterozygosity (0.764) than expected (0.602). For five loci the Dunai strain showed extremely high levels of heterozygosity (1.00). Two wild strains exhibited a number of loci (Tiszai, 4; Dunai, 6) that were not in Hardy–Weinberg equilibrium. A relatively high number of private alleles overall (n=26), as well as differences in allele frequencies supported our ability to assign most individual fish (over 90%) to each strain.     

Regulation of cellular Gsα levels and basal adenylyl cyclase activity by expression of the β2-adrenoceptor in neuroblastoma cell lines

Mouse neuroblastoma x rat glioma hybrid NG108-15 and mouse neuroblastoma x embryonic hamster brain NCB20 cells were transfected with a construct containing a human 2 adrenoceptor cDNA under the control of the actin promoter. Clones were selected on the basis of resistance to geneticin sulphate and those expressing a range of levels of the receptor expanded for further study. Membranes from a clone of NG108-15 cells expressing high levels of the receptor (N22) but not one expressing only low levels of the receptor (N17) exhibited a markedly elevated adenylyl cyclase activity when measured in the presence of Mg²⁺ compared to wild type cells. This was not due to elevated levels of the adenylyl cyclase catalytic moiety however as there was no difference in these membranes when the adenylyl cyclase activity was measured in the presence of Mn²⁺. The elevated basal activity was partially reversed by addition of the -adrenoceptor antagonist propranolol. Agonist activation of N22 but not N17 cells led to a large selective down-regulation of cellular G_s levels which was independent of the generation of cyclic AMP. Isoprenaline stimulation of adenylyl cyclase activity and of the specific high affinity binding of [³H] forskolin was achieved with substantially greater potency (some 30 fold) in N22 cell membranes than in N17. By contrast agonist activation of the endogenously expressed IP prostanoid receptor caused stimulation of adenylyl cyclase and stimulation of high affinity [³H] forskolin binding which was equipotent in each of N22, N17 and wild type NG108-15 cells. Agonist activation of the IP prostanoid receptor caused an equivalent degree of G_s down-regulation in each cell type. Expression of an epitope tagged variant of G_s in NG108-15 cells resulted in prostanoid agonist-induced down-regulation of this polypeptide in a manner indistinguishable from that of wild type G_s. Isolation of clones of NCB20 cells expressing high levels of the 2 adrenoceptor also resulted in a specific agonist-induced down-regulation of G_s.     

Uptake of sewage derived nitrogen by Ulva rigida (Chlorophyceae) in Bahía Nueva (Golfo Nuevo, Patagonia, Argentine)

Uptake kinetics of nitrogen derived from sewage–seawater mixtures (2.5–20% v/v effluent) were determined in the laboratory for Ulva rigida (Chlorophyceae) native from Bahía Nueva (Golfo Nuevo, Patagonia, Argentine). In terms of nitrogen concentration, experimental enrichment levels varied between 53.7 and 362.3M of ammonium and between 0.77 and 6.21M of nitrate+nitrite. Uptake rates were fitted to the Michaelis–Menten equation, with the following kinetic parameters: ammonium: V_max = 591.2molg^–1h^–1, K _s=262.3M, nitrate+nitrite: V _max=12.9molg^–1h^–1, K _s=3.5M). Both nutrients were taken up simultaneously, but ammonium incorporation was faster in all cases. The results show a high capability of Ulva rigida to remove sewage-derived nitrogen from culture media. In the field, most of the nitrogen provided by the effluent would be tied up in algal biomass, supporting low nitrogen levels found at a short distance away from the source.     

\4 integrin expression onin vitro andin vivo metastatic variants of lewis lung carcinoma

The expression of 4, 6, and 1 integrin subunits has been investigated on somein vitro andin vivo murine metastatic variants derived from Lewis lung carcinoma (3LL). By the use of monoclonal antibodies which recognizes different epitopes of 6, 1, and 4 subunits we demonstrate that 6 and 1 subunits are expressed in all metastatic variants of 3LL irrespective of their metastatic potential, whereas 4 subunit is expressed only in highly metastasizing cells of 3LL. Northern blots of different metastatic variants probed with 1 and 4 subunits demonstrate thata) significant amounts of 1 mRNA were detected in all metastatic variants of 3LL;b) mRNA corresponding to the described entire coding sequence of 4 subunit is expressed only on highly metastasizing cells of 3LL. We conclude that 4 subunit is specifically expressed in highly metastasizig cells of 3LL while is undetectable in lower metastasizing ones.     

The gross and amino acid compositions of batch and semi-continuous cultures ofIsochrysis sp. (clone T.ISO),Pavlova lutheri andNannochloropsis oculata

Three species of microalgae commonly used in mariculture —Isochrysis sp. (clone T.ISO) Parke,Pavlova lutheri (Droop) Green andNannochloropsis oculata (Droop) Green — were grown in batch and semicontinuous modes to compare their biochemical composition and production rates.In batch mode, logarithmic-phase cultures of all species had high levels of protein (25.2 to 41.1) and low levels of carbohydrate (7.1 to 10.3) and lipid (8.8 to 14.9). At stationary phase, cultures ofIsochrysis sp. (clone T.ISO) andN. oculata contained significantly less protein (21.8 and 20.3, respectively), all species contained more carbohydrate (14.8 to 30.6), andP. lutheri contained more lipid (16.6). In semi-continuous mode, cultures maintained at late logarithmic-phase contained more carbohydrate,Isochrysis sp. (clone T.ISO) contained less protein, andP. lutheri more lipid than logarithmic-phase batch cultures of the same species. Neither growth phase nor harvest regime affected the amino acid composition of the microalgae significantly. However, the concentration of proline inN. oculata was higher in batch cultures in logarithmic phase (9.4), than in either semi-continuous cultures in logarithmic phase (5.8 to 7.9) or batch cultures in stationary phase (5.6 to 5.9).The production rates from batch and semi-continuous logarithmic-phase cultures were not significantly different for any of the species, and there were only minor differences in the production rates of the species (range 12.4 to 17.1 mg algae dry weight 1^–1 d^–1). The different culture and harvest regimes produced significant differences in the proportions of protein and carbohydrate in the microalgae. Which regime is chosen for culturing these microalgae as food will depend on the nutritional requirements of the animal species being fed.     

Vanadium and molybdenum requirement for the fixation of molecular nitrogen by two Methanosarcina strains

Nitrogen fixation of the Methanosarcina barkeri strains Fusaro (DSM 804) and 227 (DSM 1538) was found to be dependent on the presence of vanadium or molybdenum whereby molybdenum (added as Na₂-molybdate) was preferred to vanadium (added as VCl₃). Strain 227 showed less pronounced effects on diazotrophic growth with respect to vanadium and molybdenum. Rhenium (ReCl₃) or tungsten (Na₂-tungstate) could not replace vanadium or molybdenum. The optimum concentrations were found to be 2M for vanadium and 5M for molybdenum (strain Fusaro). This Mo optimum of methanogenesis was 10-fold higher with N₂ than with NH₄Cl as nitrogen source. A vanadium requirement with NH₄Cl could not be detected. No interferences were observed if molybdenum and vanadium were added simultaneously under diazotrophic conditions. Growth yields were smallest for strain 227 grown diazotrophically ( =0.6g dw/mol in the presence of vanadium and =0.9g dw/mol in the presence of molybdenum), obviously higher for strain Fusaro grown diazotrophically ( =1.15g dw/mol in the presence of V and =1.4g dw/mol with Mo) and highest if M. barkeri was grown on NH₄Cl as N-source ( =3.4g dw/mol with Mo, strain Fusaro).     

Aluminum-induced secretion of both citrate and malate in rye

Aluminum (Al)-resistant mechanisms responsible for Al-induced secretion of organic acids are poorly understood. In this study, we characterized the Al-induced secretion of both citrate and malate from rye (Secale cereale L. cv. King). Secretion of organic acids increased with increasing concentration (10, 30 and 50 M) and duration of Al treatments. Neither phosphorous (P) deficiency up to 15 days nor addition of 50M lanthanum, 50 M lead, 10 M cadmium, or 200 M manganese caused secretion of organic acids, suggesting that this secretion was a specific response to Al stress. Aluminum activated citrate synthase, the main enzyme for the synthesis of citrate, but its activation occurred only in the root tip. The elongation of roots of an Al-sensitive cultivar of wheat (Tritium aestivum L. cv. Scout 66) was not inhibited by 50 M Al in the presence of externally applied 50 M citrate or 400 M malate. The secretion of citrate and malate from intact rye roots exposed to 50 M Al corresponded to 31.3 ± 1.7 M and 11.5 ± 2.5 M, respectively, in the rhizosphere based on an assumption of a 2 mm thick unstirred layer around root tips. This result indicated that Al-resistance in rye was achieved by the Al-induced synthesis of citrate in root apices followed by Al-induced specific secretion of citrate from root tips.     

Microbial biomass and abundance after forest fire in pine forests in Japan

Microbial characteristics of soil are being evaluated increasingly as sensitive indicators of soil health because of the clear relationship between microbial diversity, soil and plant quality and ecosystem sustainability. This study aimed to determine microbial carbon biomass and microbial abundance after fire to estimate the degree of damage, including the rate of recovery of micro-organisms, in each area. The study also aimed to establish relationships between microbial biomass and microbial abundance and the physico-chemical properties of the soil. The study was conducted in three different study areas in Hiroshima prefecture, one unburned area and two burnt areas (one immediately after and one 2years after fire). anova showed a significant difference in microbial carbon biomass and microbial abundance among the study areas. Microbial carbon biomass and microbial abundance were highest in the unburned area, followed by the area burnt 2years ago and lastly by the area studied immediately after fire. Carbon biomass was highly correlated with microbial abundance (r²=0.950). Carbon biomass and microbial abundance were shown to be significantly correlated to the soils physico-chemical properties, such as pH, moisture content, water-holding capacity and carbon:nitrogen (C:N) ratio. However, the C:N ratio was closely correlated to both carbon biomass and microbial abundance with r²=0.705 (P<0.01) and r²=0.560 (P<0.01), respectively.     

Plant regeneration via somatic embryogenesis in Styrian pumpkin: cytological and biochemical investigations

Somatic embryo formation was induced from cotyledon explants of Styrian pumpkin (Cucurbita pepo L. subsp. pepo var. styriaca Greb.) by using a solid MS medium supplemented with 16.11M NAA and 4.44M BA or 26.85M NAA and 13.32M BA. The callus proliferation was more efficient on medium supplemented with 26.85M NAA and 13.32M BA. In contrast, the embryogenic response was higher on medium with lower concentrations of growth regulators (16.11M NAA and 4.44M BA). The time needed for embryo induction did not depend on medium composition. Embryos in globular stage were transferred to three different maturation media, containing 2.89M GA₃ in combination with 0.54M NAA, 11.42M IAA and growth regulator-free medium. The germination rate was the highest when embryos were cultured on medium with 11.42M IAA. Plantlets grown on this medium achieved maturity suitable for transplantation into soil within 9 to 10weeks. The regenerated plants were successfully transferred into field and developed fertile flowers and set fruits. Biochemical analysis showed significant lower total glutathione levels among in vitro grown plantlets compared to seedlings grown in soil. When the plantlets were transferred into soil, they reached a normal size within a month and the glutathione concentration was comparable to seed-derived plants at the same developmental stage. Transmission electron microscopy was used to investigate possible differences in the ultrastructure of cells from callus cultures, and leaf cells of regenerated and seed-derived plants. Differences in the ultrastructure were found within chloroplasts which contained only single thylakoids, large starch grains and small plastoglobuli in callus cells in comparison to leaf cells, which possessed a well developed thylakoid system, small starch grains and large plastoglobuli.     

The effects of pyridine nucleotides on the activity of a calcium-activated nonselective cation channel in the rat insulinoma cell line,CRI-G1

The activity of a calcium-activated nonselective (Ca-NS⁺) channel in a rat insulinoma cell line (CRI-G1) is inhibited by pyridine nucleotides in excised patches. The effects of all four pyridine nucleotides tested, -NAD⁺, -NADH, -NADP⁺ and -NADPH were very similar when tested at 0.1 mm, and at 1 mm the phosphorylated forms, -NADP⁺ and -NADPH, appeared to be slightly more potent than -NAD⁺ and -NADH. All the pyridine nucleotides tested reduced both the open state probability of the channel and the number of functional channels observed in a single patch.The application of -NAD⁺, but not of the other nucleotides tested, to the cytoplasmic surface of isolated inside-out patches from CRI-G1 cells opened a novel nonselective cation channel (the -NAD⁺-NS⁺ channel). The activity of this new channel is calcium sensitive and may also be inhibited by AMP.