Reproductive biology of Mystus vittatus (Bloch) (Bagridae: Siluriformes) from Guntur,Andhra Pradesh

Maturation, minimum length at first maturity, spawning season, spawning periodicity, sex-ratio and absolute fecundity of Mystus vittatus, a common bagrid catfish, have been investigated. The observations show that spawning takes place during September and October. Each individual spawns only once in the season as evidenced by the study of the intraovarian ova. Females dominate the catches, and absolute fecundity (F) can be expressed by% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaaiaacaqabeaadaqaaqaaaOabaeqabaGaciiBai% aac+gacaGGNbGaaeiiaiaabAeacaqGGaGaaeypaiaabccacaqGTaGa% ae4maiaab6cacaqGYaGaaeyoaiaabkdacaqGGaGaae4kaiaabccaca% qG0aGaaeOlaiaabgdacaqG3aGaaeymaiaabgdacaqGGaGaaeiBaiaa% b+gacaqGNbGaaeiiaiaabYeaaeaacaqGHbGaaeOBaiaabsgacaqGGa% GaaeOraiaabccacaqG9aGaaeiiaiaab2cacaqGXaGaaeOlaiaabwda% caqG0aGaaeinaiaabwdacaqGGaGaae4kaiaabccacaqGWaGaaeOlai% aabMdacaqG0aGaae4naiaabkdacaqGGaGaae4vaaaaaa!5FCC!\[\begin{gathered} \log {\text{ F = - 3}}{\text{.292 + 4}}{\text{.1711 log L}} \hfill \\ {\text{and F = - 1}}{\text{.5445 + 0}}{\text{.9472 W}} \hfill \\ \end{gathered} \]     

Energy requirements of Adélie penguin (Pygoscelis adeliae) chicks

Summary The energy requirements of Adélie penguin (Pygoscelis adeliae) chicks were analysed with respect to body mass (W, 0.145–3.35 kg, n=36) and various forms of activity (lying, standing, minor activity, locomotion, walking on a treadmill). Direct respirometry was used to measure O₂ consumption ( ) and CO₂ production. Heart rate (HR, bpm) was recorded from the ECG obtained by both externally attached electrodes and implantable HR-transmitters. The parameters measured were not affected by hand-rearing of the chicks or by implanting transmitters. HR measured in the laboratory and in the field were comparable. Oxygen uptake ranged from in lying chicks to at maximal activity, RQ=0.76. Metabolic rate in small wild chicks (0.14–0.38 kg) was not affected by time of day, nor was their feeding frequency in the colony (Dec 20–21). Regressions of HR on were highly significant (p< 0.0001) in transmitter implanted chicks (n=4), and two relationships are proposed for the pooled data, one for minor activities ( ), and one for walking ( ). Oxygen consumption, mass of the chick (2–3 kg), and duration of walking (T, s) were related as , whereas mass-specific O₂ consumption was related to walking speed (S, m·s^-1) as .Abbreviations bpm beats per minute - D distance walked (m) - ECG electrocardiogram - HR heart rate (bpm) - ns number of steps - RQ respiratory quotient - S walking speed (m·s^-1) - T time walked (s) - W body mass (kg)     

The effect of micro-aerobic conditions on continuous ethanol production by Saccharomyces cerevisiae

Summary The effect of trace amounts of oxygen on the degree of ethanol inhibition in a continuous anaerobic culture of Saccharomyces cerevisiae was studied at the 100 gl ^–1 feed glucose concentration level. Results showed that the use of micro-aerobic conditions (0,5% of saturation) enhanced the utilisation of substrate by increasing the ethanol tolerance of the yeast without any significant decrease in the ethanol yield per unit substrate consumed. When the results were fitted to an equation of the form % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaqcLbyacaqG8o% GaaeypaiqabY7agaqcaiaab6cadaWcaaGcbaqcLbyacaqGdbWaaSba% aSqaaKqzagGaae4CaaWcbeaaaOqaaKqzagGaae4qamaaBaaaleaaju% gGbiaabohaaSqabaqcLbyacqGHRaWkcaqGlbWaaSbaaSqaaKqzagGa% ae4CaaWcbeaaaaqcLbyacaGGUaWaaSaaaOqaaKqzagGaae4samaaBa% aaleaajugGbiaabchaaSqabaaakeaajugGbiaabUeadaWgaaWcbaqc% LbyacaqGWbaaleqaaKqzagGaey4kaSIaaeywamaaBaaaleaajugGbi% aabchacaqGZbaaleqaaKqzagGaaiOlaiaacIcacaqGdbWaaSbaaSqa% aKqzagGaae4CaiaabAgaaSqabaqcLbyacqGHsislcaqGdbWaaSbaaS% qaaKqzagGaae4CaaWcbeaajugGbiaacMcaaaaaaa!6301!\[{\text{\mu = \hat \mu }}{\text{.}}\frac{{{\text{C}}_{\text{s}} }}{{{\text{C}}_{\text{s}} + {\text{K}}_{\text{s}} }}.\frac{{{\text{K}}_{\text{p}} }}{{{\text{K}}_{\text{p}} + {\text{Y}}_{{\text{ps}}} .({\text{C}}_{{\text{sf}}} - {\text{C}}_{\text{s}} )}}\]it was found that the values for % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabeiVdyaaja% aaaa!373F!\[{\text{\hat \mu }}\], K_s and Y_ps were the same as for the non-aerobic case while the ethanol inhibition constant, K_p , had increased from 5,2 to 14,0 gl ^–1.Notation C_sf feed substrate concentration - gl ^–1 - C_s substrate concentration gl ^–1 - C_p product concentration - gl ^–1 - C_x cell concentration - gl ^–1 - D dilution rate - h^-1 - K_s substrate saturation constant - gl ^–1 - K_p product inhibition constant - gl ^–1 - m maintenance coefficient - h^–1 - Y_ps product yield coefficient - g EtOH/g glucose - Y_xs cell yield coefficient - g cells/g glucose - specific growth rate - h^–1 - % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabeiVdyaaja% aaaa!373F!\[{\text{\hat \mu }}\] maximum specific growth rate - h^–1     

Organic matter transformations in soils

Summary The kinetics of carbon and nitrogen mineralization in soils amended with different organic materials was investigated at different periods of incubation lasting for 30 weeks. The data indicated that the decomposition of organic matter in soils is controlled by two simultaneously occurring superimposed first-order kinetic reactions. Based on cumulative C or N mineralization-t^1/2 relationships, the carbon or nitrogen mineralization potentials of the soils amended with different organic materials were derived on the premise that the rate of C or N mineralization is proportional to the amount of potentially mineralizable substrate as defined by the equation: % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamizaiaado% eacaGGVaGaamizaiaadshacqGH9aqpcqGHsislcaWGlbGaam4qaiaa% bccacaqGVbGaaeOCaiaabccacaqGSbGaae4BaiaabEgacaqGGaGaai% ikaiaaboeacaqGVbGaeyOeI0IaaeiiaiaaboeacaqG0bGaaeykaiaa% bccacaqG9aGaaeiiaiaabYgacaqGVbGaae4zaiaabccacaqGdbGaae% 4BaiaabccacqGHsislcaqGGaGaae4saiaab+cacaqGYaGaaeOlaiaa% bodacaqGWaGaae4maiaabccacaqGOaGaamiDaiaacMcaaaa!5C0E!\[dC/dt = - KC{\text{ or log }}({\text{Co}} - {\text{ Ct) = log Co }} - {\text{ K/2}}{\text{.303 (}}t)\]where Co is the C mineralization potential, Ct is the cumulative amount of CO₂ evolved at time t, and K is the mineralization rate constant. The estimates of C or N mineralization potential, mineralization rate constants and half-time for C or N mineralization are reported for the organic matter amended soils. The relative enrichment of conventional humus fractions after a 30 week period of incubation indicated that the soils could be ranked in the following order of encouraging humification of the organic materials: Haplustults>Haplaquents>Calciorthents.re]19751007     

QTL mapping of resistance to Sclerotinia midstalk rot in RIL of sunflower population NDBLOSsel × CM625

Midstalk rot caused by Sclerotinia sclerotiorum is an important disease of sunflower in its main areas of cultivation. The objectives of this study were to (1) verify quantitative trait loci (QTL) for midstalk-rot resistance found in F₃ families of the NDBLOS_sel × CM625 population in recombinant inbred lines (RIL) derived from the same cross; (2) re-estimate their position and genetic effects; (3) draw inferences about the predictive quality of QTL for midstalk-rot resistance identified in the F₃ families as compared to those in the RIL. Phenotypic data for three resistance (leaf lesion, stem lesion, and speed of fungal growth) and two morphological traits (leaf length and leaf length with petiole) were obtained from 317 RIL following artificial infection in field experiments across two environments. For genotyping the 248 RIL, we selected 41 simple sequence repeat (SSR) markers based on their association with QTL for Sclerotinia midstalk-rot resistance in an earlier study. The resistance traits showed intermediate to high heritabilities and were significantly correlated with each other Genotypic correlations between F₃ families and the RIL were highly significant and ranged between 0.50 for leaf length and 0.64 for stem lesion. For stem lesion, two genomic regions on linkage group (LG) 8 and LG16 explaining 26.5% of the genotypic variance for Sclerotinia midstalk-rot resistance were consistent across generations. For this trait, the genotypic correlation between the observed performance and its prediction based on QTL positions and effects in F₃ families was surprisingly high The genetic effects and predictive quality of these two QTL are promising for application in marker-assisted selection to Sclerotinia midstalk-rot resistance.     

Manganese toxicity: The significance of magnesium for the sensitivity of wheat plants

The tolerance of wheat to manganese was investigated in soil and solution culture. Although no critical toxicity concentration could be identified, growth was reduced when the ratio of magnesium to manganese in the shoots (R_p) fell below 20:1 (mgg^–1/mgg^–1). In soil, plant growth relative to unstressed plants (Y) could be described by the empirical equation: % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaeywaiabg2% da9iaaicdacaGGUaGaaGyoaiaaiwdacqGHsislcaaIWaGaaiOlaiaa% iMdacaaI1aGaaeyzaiaabIhacaqGWbGaaiikaiabgkHiTiaaicdaca% GGUaGaaGymaiaaiodacaaI5aGaaeOuamaaBaaaleaacaqGWbaabeaa% kiaacMcaaaa!4959!\[{\text{Y}} = 0.95 - 0.95{\text{exp}}( - 0.139{\text{R}}_{\text{p}} )\]In solution culture the value of R_p was related to the ratio of the two ions in the nutrient solution (R_s) according to the expression: % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaeysaiaab6% gacaqGGaGaaeOuamaaBaaaleaacaqGWbaabeaakiabg2da9iaaicda% caGGUaGaaGinaiaaikdacqGHRaWkcaaIWaGaaiOlaiaaisdacaaI4a% GaaeiiaiaabMeacaqGUbGaaeiiaiaabkfadaWgaaWcbaGaae4Caaqa% baGccaGGPaaaaa!47B6!\[{\text{In R}}_{\text{p}} = 0.42 + 0.48{\text{ In R}}_{\text{s}}\]The magnesium concentration in the nutrient solution for optimum growth at a given concentration of manganese was given by: % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaeysaiaab6% gacaqGGaGaae4waiaab2eacaqGNbGaaeyxaiabg2da9iaaikdacaGG% UaGaaGioaiaaiMdacqGHRaWkcaaIWaGaaiOlaiaaiwdacaaI0aGaae% iiaiaabMeacaqGUbGaaeiiaiaabUfacaqGnbGaaeOBaiaab2faaaa!4A0B!\[{\text{In [Mg]}} = 2.89 + 0.54{\text{ In [Mn]}}\]Magnesium increased the tolerance of plants to high concentrations of manganese in shoot tissue and also increased the ability of the plant to discriminate against manganese ions in translocation of nutrients from roots to shoots.     

Physiology and kinetics of autotrophic denitrification by Thiobacillus denitrificans

Summary A strain of Thiobacillus denitrificans was isolated after enrichment under anaerobic conditions by the continuous culture technique using thiosulfate as energy source and nitrate as electron acceptor and nitrogen source. The isolate was an active denitrifyer, the optimal conditions being 30°C and pH 7.5–8.0. Denitrification was inhibited by sulfate (the reaction product) above 5 g SO ₄ ⁼ /l, whereas high concentrations of the substrates nitrate and thiosulfate were less harmful; nitrite affected denitrification above 0.2 g NO ₂ ^– /l. During the time course of denitrification in a batch culture growth and substrate consumption slowed down already after only half the substrate was utilized due to product inhibition. The following parameters were determined in continuous culture under nitrate limitation: _max=0.11 h^–1, K _S=0.2 mg NO ₃ ^– /l, maximum denitrification rate=0.78 g NO ₃ ^– /g cells·h, g cells/g NO ₃ ^– , g cells/g S₂O ₃ ⁼ . Nitrite did not accumulate during steady state denitrification; the denitrification gas was almost pure N₂. The concentrations of N₂O and NO were below 1 ppm.     

Indole-3-acetic acid transport in apical dominance: a quantitative approach. Influence of endogenous and exogenous IAA apical source on inhibitory power of IAA transport

The relationship between the amount of indole-3-acetic acid transported (IAA transport) through the second node of 7-day-old pea seedlings and the degree of inhibition of axillary bud outgrowth at the same node was studied. For both the endogenous apical IAA source (leaves of apical bud) and the exogenous one (lanolin paste containing 0.25–1.0 mg mL^–1 IAA) the slope of linear dependence between inhibition and IAA transport was similar. However, the same IAA transport induced different inhibitions, which were higher for the endogenous source. Moreover, the apical bud induced higher inhibition at the same level of IAA transport when the 4th leaf was present than when it was absent. Apparently, the source of IAA also may regulate the inhibitory power of IAA transported from it. IAA transport appears to consists of active and slightly active one moving along different pathways.Abbreviations a and b coefficients of linear regression of the type y = a+bx; - confidence level of t-test - ELISA enzyme linked immunosorbent assay - GR_1,2 ^e/d growth rate of the lateral bud of experimental/decapitated (control) pea plants at the first and second days after treatment or decapitation - I degree of inhibition of lateral bud outgrowth - IAA indole-3-acetic acid - L_1,2,3 the lengths of lateral bud at 1, 2 or 3rd day after treatment or decapitation of pea plants - n data number - r correlation coefficient - T amount of IAA transported through the second node of pea plant for 3 hours - TIBA 2, 3, 5-triiodobenzoic acid - t-test statistical test used here to compare slopes of linear regressions (y = a+bx) calculated as % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaeiDaiaabc% cacaqG9aGaaeiiaiaadkgadaWgaaWcbaGaaGymaaqabaGccaqGGaGa% aeylaiaabccacaWGIbWaaSbaaSqaaiaaikdaaeqaaOGaaeiiaiaab+% cacaqGGaWaaOaaaeaacaqGBbaaleqaaOGaaeikaiaabohacaqGLbGa% aeiiaiaadkgadaWgaaWcbaGaaGymaaqabaGccaqGPaWaaWbaaSqabe% aacaqGYaaaaOGaaeiiaiaabUcacaqGGaGaaeikaiaabohacaqGLbGa% aeiiaiaadkgadaWgaaWcbaGaaGOmaaqabaGccaqGPaWaaWbaaSqabe% aacaqGYaaaaOGaaeyxaiaab6caaaa!524A!\[{\text{t = }}b_1 {\text{ - }}b_2 {\text{ / }}\sqrt {\text{[}} {\text{(se }}b_1 {\text{)}}^{\text{2}} {\text{ + (se }}b_2 {\text{)}}^{\text{2}} {\text{]}}{\text{.}}\]     

Plant regeneration from explant and protoplast derived calluses of Medicago littoralis

Plant regeneration from explant and protoplast derived callus has been achieved in Medicago littoralis cv. Harbinger 1886, an annual legume resistant to the fungus Pseudopeziza medicaginis. Callus was induced from different tissue explants and the fastest growth rate was observed for hypocotyls in B5 medium with 2 mg l^–1 2,4-dichlorophenoxyacetic acid and 0.5 mg l^–1 N⁶-benzyladenine. Protoplasts were isolated from cotyledons and leaves of sterile plants and from callus; the first two kinds of protoplasts showed a plating efficiency of 5.6% and 5%, respectively, when embedded in agarose. Plant regeneration occurred on media containing % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9qq-f0-yqaqVeLsFr0-vr% 0-vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaqGobWaaW% baaSqabeaacaqG2aaaaOGaaeOVfiaabs5adaahaaWcbeqaaiaaikda% aaGccaqG+waaaa!3F97!\[{\text{N}}^{\text{6}} {\text{\Delta }}^2 {\text{}}\]isopentenyl-adenine combined with indole-3-acetic acid or 1,2-benzisoxazole-3-acetic acid, and on media with N⁶-benzyladenine plus -naphtaleneacetic acid; a cytokinin/auxin ratio higher than 1 induced embryos while a ratio around 1 stimulated shoot formation. Embryo development and rooting of shoots were performed in RL medium without growth regulators.Abbreviations NAA -naphthaleneacetic acid - BA N⁶-benzyladenine - 2,4-D 2,4-dichlorophenoxyacetic acid - 2iP % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9qq-f0-yqaqVeLsFr0-vr% 0-vr0db8meaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaqGobWaaW% baaSqabeaacaqG2aaaaOGaaeOVfiaabs5adaahaaWcbeqaaiaaikda% aaGccaqG+waaaa!3F97!\[{\text{N}}^{\text{6}} {\text{\Delta }}^2 {\text{}}\]isopentenyl-adenine - IAA indole-3-acetic acid - BOA 1,2-benzisoxazole-3-acetic acid - KIN kinetin - MS Murashige & Skoog (1962) - GRFMS growth regulator free MS medium - B5 Gamborg et al. (1968) - RL Phillips & Collins (1979) - KM8 KM8P Kao & Michayluk (1975) - CPW Frearson et al. (1973) - f. wt fresh weight - FDA fluorescoin diacetate     

Correlation between scaffold in vivo biocompatibility and in vitro cell compatibility using mesenchymal and mononuclear cell cultures

The aim of this study was to compare the cell compatibility of silk and polyglycolic acid (PGA) scaffolds cultured in vitro with mesenchymal stem cells (MSCs) and peripheral blood mononuclear cells (PBMCs) to their biocompatibility in vivo following implantation. Scaffolds were knitted with silk or PGA thread and the average efficiency of cell attachment was 35 ± 4% and 17 ± 2% in the PGA and silk scaffold groups. Thus, the initial attachment of the MSC cells to the PGA scaffold was superior to the initial attachment of the cells on the silk scaffold. After 21 days in culture, the average cell density on the silk scaffold was \text5\text.8 ±\text0\text.5 ×\text10^\text5 {\text{5}}{\text{.8}} \pm {\text{0}}{\text{.5}} \times {\text{10}}^{\text{5}} cells, and the average cell density of the PGA scaffolds was \text6\text.34 ±\text0\text.5 ×\text10^\text5 {\text{6}}{\text{.34}} \pm {\text{0}}{\text{.5}} \times {\text{10}}^{\text{5}} cells. In addition, there was no cell cytoxicity observed with either scaffold. However, the immune response of in vitro cultured PBMCs was significantly higher with the PGA scaffold than with the silk scaffold. The proliferation of the PBMCs cultured on the PGA scaffold was two times greater than that of those cultured on the silk scaffold after 3 days of culture. In addition, the secretion of IL-1 by the PBMCs cultured on the PGA scaffold was superior to that of the PBMCs cultured on the silk scaffold. The secretion of IL-1β and IFN-γ was increased by about 50% when the PBMCs were cultured with the PGA scaffold. Silk and PGA scaffolds were also implanted subcutaneous in rats. Histological evaluation of the scaffold explants revealed the presence of monocytes and macrophages in PGA scaffold. The inflammatory tissue reaction was more conspicuous on the PGA scaffold than on the silk scaffold. These results suggest that the results of in vitro PBMC cultures were more closely related to the in vivo results of implantation than the results of in vitro MSC cultures.     

Secondary production,calcification and CO<Subscript>2</Subscript> fluxes in the cirripedes <Emphasis Type="Italic">Chthamalus montagui</Emphasis> and <Emphasis Type="Italic">Elminius modestus</Emphasis>

Calcification, a process common to numerous marine taxa, has traditionally been considered to be a significant source of CO₂ in tropical waters only. A number of relatively recent studies, however, have shown that significant amounts of CO₂ are also produced in temperate waters, although none of these studies was carried out on rocky shores, which are considered to be very productive systems. We compared the CO₂ fluxes due to respiration and calcification in two temperate species, the cirripedes Chthamalus montagui and Elminius modestus. The population dynamics of both species were estimated at two sites during a 1-year experimental period in order to establish mean organic (ash-free dry weight) and CaCO₃ (dry shell weight) production. Based on these parameters, we estimated the CO₂ fluxes due to respiration and calcification. CaCO₃ production was estimated to be 481.0 and at each site, representing 3.4 and respectively, of released CO₂. These fluxes represent each 47% of the CO₂ released as a result of respiration and calcification. The production of CaCO₃ at the high-density site was: (1) among the highest values obtained for temperate organisms, and (2) comparable to the estimated CO₂ fluxes for coral reefs. As calcifying organisms are well represented in temperate ecosystems in terms of both density and biomass, our results provide clear evidence that calcification of temperate organisms should not be underestimated. Additional studies on other rocky shore taxa are needed before the relative importance of calcification in rocky intertidal carbon budgets can be generalized.     

(H)NCAHA and (H)CANNH experiments for the determination of vicinal coupling constants related to the ϕ-torsion angle

Summary A set of three-dimensional triple-resonance experiments is described which provide , , and coupling constants. The pulse sequences generate E.COSY-like multiplet patterns and comprise a magnetization transfer from the amide proton to the α-proton or vice versa via the directly bound heteronuclei. For residues with the ¹H^α spin resonating close to the H₂O signal, a modified HNCA experiment can be employed to measure the vicinal ¹H^N,¹H^α couplings. Ambiguities associated with the conversion of values into ϕ-angle constraints for protein structure determination can be resolved with the knowledge of the heteronuclear ³J-couplings. In favourable cases, stereospecific assignments of glycine α-protons can be obtained by employing the experiments described here in combination with NOE data. The methods are applied to flavodoxin from Desulfovibrio vulgaris.     

A quantitative appraisal of the ambivalent metal ion binding properties of cytidine in aqueous solution and an estimation of the<Emphasis Type="Italic"> anti</Emphasis>–<Emphasis Type="Italic">syn</Emphasis> energy barrier of cytidine derivatives

The recently defined versus straight-line plots for L = pyridine-type (PyN) and ortho-aminopyridine-type (oPyN) ligands now allow the evaluation in a quantitative manner of the stability of the 1:1 complexes formed between cytidine (Cyd) and Ca²⁺, Mg²⁺, Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺ or Cd²⁺ (M²⁺); the corresponding stability constants, , including the acidity constant, , for the deprotonation of the (N3)H⁺ site had been determined previously under exactly the same conditions as the mentioned plots. Since the stabilities of the M(PyN)²⁺ and M(oPyN)²⁺ complexes of Ca²⁺ and Mg²⁺ are practically identical, it is concluded that complex formation occurs in an outer-sphere manner, and this is in accord with the fact that in the pK_a range 3–7 metal ion binding is independent of or . Ca(Cyd)²⁺ and Mg(Cyd)²⁺ are more stable than the corresponding (outer-sphere) M(PyN)²⁺ complexes and this means that the C2 carbonyl group of Cyd must participate, next to N3 which is most likely outer-sphere, in metal ion binding, leading thus to chelates; these have formation degrees of about 50% and 35%, respectively. Co(Cyd)²⁺ and Ni(Cyd)²⁺ show no increased stability based on the hence, the (C2)O group does not participate in metal ion binding, but the inner-sphere coordination to N3 is strongly inhibited by the (C4)NH₂ group. In the M(Cyd)²⁺ complexes of Mn²⁺, Cu²⁺, Zn²⁺ and Cd²⁺, this inhibiting effect on M²⁺ binding at N3 is partially compensated by participation of the (C2)O group in complex formation and the corresponding chelates have formation degrees between about 30% (Zn²⁺) and 83% (Cu²⁺). The different structures of the mentioned chelates are discussed in relation to available crystal structure analyses. (1) There is evidence (crystal structure studies: Cu²⁺, Zn²⁺, Cd²⁺) that four-membered rings form, i.e. there is a strong M²⁺ bond to N3 and a weak one to (C2)O. (2) By hydrogen bond formation to (C2)O of a metal ion-bound water molecule, six-membered rings, so-called semichelates, may form. (3) For Ca²⁺ and Mg²⁺, and possibly Mn²⁺, and their Cyd complexes, six-membered chelates are also likely with (C2)O being inner-sphere (crystal structure) and N3 outer-sphere. (4) Finally, for these metal ions also complexes with a sole outer-sphere interaction may occur. All these types of chelates are expected to be in equilibrium with each other in solution, but, depending on the metal ion, either the one or the other form will dominate. Clearly, the cytidine residue is an ambivalent binding site which adjusts well to the requirements of the metal ion to be bound and this observation is of relevance for single-stranded nucleic acids and their interactions with metal ions. In addition, the anti–syn energy barrier has been estimated as being in the order of 6–7.5 kJ/mol for cytidine derivatives in aqueous solution at 25 °C.Abbreviations ADP^3– adenosine 5-diphosphate - AMP^2– adenosine 5-monophosphate - ATP^4– adenosine 5-triphosphate - CDP^3– cytidine 5-diphosphate - cl closed - CMP^2– cytidine 5-monophosphate - 3-CMP^2– cytidine 3-monophosphate - CTP^4– cytidine 5-triphosphate - Cyd cytidine - DNA deoxyribonucleic acid - I ionic strength - K_a acidity constant - K_I intramolecular equilibrium constant - L general ligand - M²⁺ general divalent metal ion - NTP^4– nucleoside 5-triphosphate - op open - oPyN ortho-aminopyridine-type ligand - PyN pyridine-type ligand - t-RNA transfer ribonucleic acid - Tu tubercidin (7-deazaadenosine)In honor of Professor Liang-Nian Ji on the occasion of his 70th birthday in friendship and with best wishes.     

A method for the destruction and analysis of biogenic silicon in two Antarctic diatom species:<Emphasis Type="Italic"> Thalassiosira</Emphasis> sp. and<Emphasis Type="Italic"> Chaetoceros brevis</Emphasis>

Diatoms in the Southern Ocean are limited by iron and light, and therefore produce little biomass. Sufficient biomass for analysis under these conditions requires large sample volumes, and diatom samples are therefore often pre-concentrated on a filter. A method for the digestion of diatom cells on polycarbonate filters, that is also suitable for trace metal analysis, is described here. Additional analysis by inductively coupled plasma-optical emission spectroscopy (ICP-OES) is used for the determination of biogenic silicon. Although several procedures were tested, the method of Hauptkorn et al., which uses tetramethylammonium hydroxide for the destruction of silicon is adapted here [Hauptkorn et al. (2001) Fres J Anal Chem 370:246–250]. Additional nitric acid is added to destroy the polycarbonate filters. The described method results in clear digests and a good correlation between cell numbers and silicon content. Using this procedure, the cellular silicon content for Chaetoceros brevis was determined as 86 ± 4 fmol cell⁻¹. For Thalassiosira sp. a sensitivity effect was observed, and silicon content was determined as . The obtained cellular silicon contents are in good agreement with values presented in the literature.     

Energetics of the growth of Methanobacterium thermoautotrophicum and Methanococcus thermolithotrophicus on ammonium chloride and dinitrogen

Methanobacterium thermoautotrophicum was grown in continuous culture in a fermenter gassed with H₂ and CO₂ as sole carbon and energy sources, and in a medium which contained either NH₄Cl or gaseous N₂ as nitrogen source. Growth was possible with N₂. Steady states were obtained at various gas flow rates with NH₄Cl and with and the maintenance coefficient varied with the gas input and with the nitrogen source. Growth of Methanococcus thermolithotrophicus in continuous culture in a fermenter gassed with H₂, CO₂ as nitrogen, carbon and energy sources was also examined.Abbreviations molecular growth yield (g dry weight of cells per mol of CH₄ evolved) - growth rate (h^-1) - D dilution rate (h^-1) - rate (h_-1); relation of Neijssel and Tempest and of Stouthamer and Bettenhaussen - energy     

A linkage group with FRA16B (the fragile site at 16q22.1)

Summary Polymorphic DNA markers located in bands 16q13, 16q21 and 16q22 were examined for recombination with FRA16B, the fragile site at 16q22.100. A tight linkage cluster D16S10-FRA16B-D16S4-HP was established. There were no recombinants between D16S10 and D16S4, which flank FRA16B. The markers D16S10 and D16S4 are in close proximity on the genetic map and delineate a small chromosomal segment, which contains the distamycin A-inducible fragile site.     

Dynamics of electron transfer within and between PS II reaction center complexes indicated by the light-saturation curve of in vivo variable chlorophyll fluorescence emission

The dynamics of light-induced closure of the PS II reaction centers was studied in intact, dark-adapted leaves by measuring the light-irradiance (I) dependence of the relative variable chlorophyll fluorescence V which is the ratio between the amplitude of the variable fluorescence induced by a pulse of actinic light and the maximal variable fluorescence amplitude obtained with an intense, supersaturating light pulse. It is shown that the light-saturation curve of V is a hyperbola of order n. The experimental values of n ranged from around 0.75 to around 2, depending on the plant material and the environmental conditions. A simple theoretical analysis confirmed this hyperbolic relationship between V and I and suggested that n could represent the apparent number of photons necessary to close one reaction center. Thus, experimental conditions leading to n values higher than 1 could indicate that, from a macroscopic viewpoint, more than one photon is necessary to close one PS II center, possibly due to changes in the relative concentrations of the different redox states of the PS II reaction center complexes at the quasi-steady state induced by the actinic light. On the other hand, the existence of environmental conditions resulting in n noticeably lower than 1 suggests the possibility of an electron flow between PS II reaction center complexes.Abbreviations F₀ and F_m minimal and maximal levels of chlorophyll fluorescence emission, respectively - F_p peak fluorescence induced by a pulse of actinic light - I incident light irradiance (in W m^-2) - PS II Photosystem II - P₆₈₀ PS II reaction center - Q_A and Q_B primary and secondary (stable) electron acceptors of PS II - V relative variable chlorophyll fluorescence % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0Jf9crFfpeea0xh9v8qiW7rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaiikaiaadA% facqGH9aqpcaGGOaGaaeOramaaBaaaleaacaqGWbaabeaakiabgkHi% TiaabAeadaWgaaWcbaGaaeimaaqabaGccaGGPaGaai4laiaacIcaca% qGgbWaaSbaaSqaaiaab2gaaeqaaOGaeyOeI0IaaeOramaaBaaaleaa% caqGWaaabeaakiaacMcacaGGPaaaaa!47BD!\[(V = ({\text{F}}_{\text{p}} - {\text{F}}_{\text{0}} )/({\text{F}}_{\text{m}} - {\text{F}}_{\text{0}} ))\]     

Variation in outcrossing rate and population genetic structure of Clarkia tembloriensis (Onagraceae)

Summary Outcrossing rate estimates for eight accessions of Clarkia tembloriensis indicate that this annual plant species has a wide interpopulational range of outcrossing rate ( ). Populations' t estimates were significantly correlated with observed heterozygosity and mean number of alleles per locus. Estimated fixation indices, , for most populations were very close to their expected values, F_eq, for a given Nei's gene diversity statistics showed that the group of outcrossing populations have more total genetic variation and less differentiation among populations than does the group of selfing populations. These results indicate that the breeding system of C. tembloriensis has had a strong influence on the amount and distribution of genetic variation within and among its populations.     

Measurement of amount of nitrogen fixed by a legume crop

Summary The amount of nitrogen fixed by a legume crop can be calculated from the relationship % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGceaqabeaacaqGbb% GaaeyBaiaab+gacaqG1bGaaeOBaiaabshacaqGGaGaae4BaiaabAga% caqGGaGaaeOzaiaabMgacaqG4bGaaeyzaiaabsgacaqGGaGaaeOtai% aabccacaqG9aaabaGaaeypaiaabccadaqadaqaaiaaigdacqGHsisl% daWcaaqaaiGacggacaGG0bGaai4Baiaac2gacaGGGaGaaiyjaiaacc% cacaGGobGaaiylaiaacgdacaGG1aGaaiiiaiaacwgacaGG4bGaai4y% aiaacwgacaGGZbGaai4CaiaacccacaGGPbGaaiOBaiaacccacaGGSb% GaaiyzaiaacEgacaGG1bGaaiyBaiaacwgacaGGGaGaai4yaiaackha% caGGVbGaaiiCaaqaaiGacggacaGG0bGaai4Baiaac2gacaGGGaGaai% yjaiaacccacaGGobGaaiylaiaacgdacaGG1aGaaiiiaiaacwgacaGG% 4bGaai4yaiaacwgacaGGZbGaai4CaiaacccacaGGPbGaaiOBaiaacc% cacaqGYbGaaeyzaiaabAgacaqGLbGaaeOCaiaabwgacaqGUbGaae4y% aiaabwgacaGGGaGaai4yaiaackhacaGGVbGaaiiCaaaaaiaawIcaca% GLPaaacaqI4bGaaKiiaiaabshacaqGVbGaaeiDaiaabggacaqGSbGa% aeiiaiaab6eacaqGGaGaaeyAaiaab6gacaqGGaGaaeiBaiaabwgaca% qGNbGaaeyDaiaab2gacaqGLbGaaeiiaiaabogacaqGYbGaae4Baiaa% bchaaaaa!9A78!\[\begin{gathered} {\text{Amount of fixed N = }} \hfill \\ {\text{ = }}\left( {1 - \frac{{\operatorname{atom} \% N - 15 excess in legume crop}}{{\operatorname{atom} \% N - 15 excess in {\text{reference}} crop}}} \right)\user1{x }{\text{total N in legume crop}} \hfill \\ \end{gathered} \]when a suitable reference crop is chosen. The implications and interpretation of this method of measurement are described.