The role of muscle development in the transition to endothermy in nestling bank swallows,Riparia riparia

Summary We examined the transition from ectothermy to endothermy in nestling bank swallows (Riparia riparia) by measuring the peak metabolic response to cold (PMR) in groups of nestlings. Additionally aerobic capacity, as assessed by citrate synthase activity (CS), and contractile function, as assessed by myofibrillar ATPase activity (mATPase) were measured in the pectoralis and mixed leg muscles during development. During the first 65% of their growth (from 2–12 g) bank swallows do not increase their metabolic rate in response to cold (Fig. 1). Between 12 and 16 g the PMR increased from 4 to more than 10 ml O₂ (g·h)^–1. Citrate synthase activity increased throughout development, starting at 20 moles (min·g fresh mass)^–1 in both tissues and increasing to 150 and 50 moles (min·g)^–1 in the pectoralis and leg muscles, respectively (Fig. 5). The augmented aerobic capacity combined with large increases in muscle mass undoubtedly contributes to the improved thermoregulatory abilities of older nestlings. However, muscle mass and aerobic capacity increase continuously and do not show the sharp transition noted in PMR. In the leg muscle mATPase activity is constant throughout growth, but in the pectoralis muscle it undergoes an abrupt increase from 0.5 moles (min·mg myofibrillar protein)^–1 in animals weighing less than 12 g to 0.9 moles (min·mg)^–1 in nestlings weighing more than 15 g (Fig. 6). The similar pattern of development of PMR and mATPase suggests a critical role for muscle development in the transition to endothermy in this species.Abbreviations CS citrate, synthase - mATPase myofibrillar adenosine triphosphatase - PMR peak metabolic rate during cold stress - rate of oxygen consumption     

Distance-constraint approach to higher-order structures of globular proteins with empirically determined distances between amino acid residues

An analysis of higher-order structures of globular proteins by means of a distance-constraint approach is presented. Conformations are generated for each of 21 test proteins of small and medium sizes by optimizing an objective functionf=w _ij(d _ij–d _ij)², whered _ij is a distance between residuesi andj in a calculated conformation, d _ij is an assigned distance to the (ij) pair of residues which is determined based on the statistics of known three-dimensional structures of 14 proteins in the earlier study, andw _ij is a weighting factor. d _ij involves information about hydrophobicity and hydrophilicity of each amino acid residue and about connectivity of a polypeptide chain. In these calculations, only the amino acid sequence is used as input data specific to a calculated protein. With respect to higher-order structures regenerated in the optimized conformations, the following properties are analyzed: (a) N14 of a residue, defined as the number of residues surrounding the residue located within a sphere of radius of 14 Å; (b) root-mean-square differences of the global and local conformations from the corresponding X-ray conformations; (c) distance profiles in the short and medium ranges; and (d) distance maps. The effects of supplementary information about locations of secondary structures and disulfide bonds are also examined to discuss the potential ability of this methodology to predict the three-dimensional structures of globular proteins.     

A self-dual network derived from a single neuronic equation

A model of a neuron with memory was viewed from the realibizability of a given periodic sequence of typeR _n R _n =u ₁ u ₂...u _{n 1 2}... _n(u _j = 0 or 1, _j = 1 –u _j). It is easily shown that the periodic sequenceR _n R _n is always obtained as an output of the model with memory of lengthn. However it is not so easy to decide the realizability of the given sequence in the case of the memory of length less thann. The necessary and sufficient condition for the realizability was given in a practical form. The condition is concerned with the determinant of a matrix associated with the given sequence.     

Relationship between single-cross performance and molecular marker heterozygosity

Summary In studies involving isozymes or restriction fragment length polymorphisms (RFLPs), correlations of parental molecular marker diversity with grain yield of maize (Zea mays L.) single-crosses have been too low to be of any predictive value. The relationship of molecular marker heterozygosity (D_ij) with hybrid performance ( _ij) and combining ability was examined. For a simple genetic model involving uncorrelated parental allele frequencies and complete coverage of quantitative trait loci (QTL) by molecular markers, the correlations between _ij and D_ij were 0.25. _ij and D_ij were partitioned into general and specific effects. The expected correlation between specific combining ability and specific molecular marker heterozygosity is high. Expected correlations between general combining ability and general molecular marker heterozygosity are either positive or negative, depending on allele frequencies in the tester lines. Computer simulation was used to investigate a more complex but more realistic genetic model involving incomplete coverage of QTL by molecular markers. All of the following conditions are necessary for effective prediction of hybrid performance based on molecular marker heterozygosity: (1) dominance effects are strong; (2) allele frequencies at individual loci in the parental inbreds are negatively correlated; (3) trait heritability is high; (4) average parental allele frequencies vary only within a narrow range; (5) at least 30–50% of the QTL are linked to molecular markers; and (6) not more than 20–30% of the molecular markers are randomly dispersed or unlinked to QTL.A contribution from Limagrain Genetics, a Groupe Limagrain company     

Expression,purification, characterization,and deletion mutations of phosphorylase kinase γ subunit: identification of an inhibitory domain in the γ subunit

A catalytic fragment, _1-298, derived from limited chymotryptic digestion of phosphorylaseb kinase (Harris, W.R.et al., J. Biol. Chem., 265: 11740–11745, 1990), is reported to have about six-fold greater specific activity than does the subunit-calmodulin complex. To test whether there is an inhibitory domain located outside the catalytic core of the subunit, full-length wild-type and seven truncated forms of were expressed inE. coli. Recombinant proteins accumulate in the inclusion bodies and can be isolated, solubilized, renatured, and purified further by ammonium sulfate precipitation and Q-Sepharose column. Four out of seven truncated mutants show similar ( _1-353 and _1-341) or less ( _1-331 and _1-276) specific activity than does the full-length wild-type , _1-386. Three truncated forms, _1-316, _1-300, and _1-290 have molar specific activities approximately twice as great as those of the full-length wild-type and the nonactivated holoenzyme. All recombinant s exhibit similarK _m values for both substrates, i.e., about 18M for phosphorylaseb and about 75 M for MgATP. Three truncated s, _1-316, _1-300, and _1-290, have a 1.9- to 2.5-fold greater catalytic efficiency (V _max/K _m) than that of the full-length wild-type and a 3.5- to 4.5-fold greater efficiency than that of the truncated _1-331. This evidence suggests that there is at least one inhibitory domain in the C-terminal region of , which is located at _301-331· _1-290, but not _1-276, which contains the highly conserved kinase domain, is the minimum sequence required for the subunit to exhibit phosphotransferase activity. Both _1-290 and _1-300 have several properties similar to full-length wild-type , including metal ion responses (activation by free Mg²⁺ and inhibition by free Mn²⁺) pH dependency, and substrate specificities.     

The expression of I-Ed molecules in F1 hybrid mice detected with antigen-specific,I-Ed-restricted cloned T-cell lines

The expression of polymorphic determinants on I-E molecules is largely dependent on allelic variation in the E chain. We have previously analyzed the expression of E ^k and E ^b chains in F₁ hybrid mice by a combination of techniques, and have shown that functional variation detected by the responsiveness of cloned T-cell lines specific for these molecules correlates well with serological determination of E expression. In the present study, we have extended our analysis to E ^d expression in F₁ hybrid mice. We show that E ^d is relatively poorly expressed in three F₁ combinations: H-2 ^d× H-2 ^b, H-2 ^d× H-2 ^s, and H-2 ^d× H-2 ^u. The former two crosses express E chains from the H-2 ^dparent only; when recombinant strains carrying E ^b or E ^s and an active E gene are used, E ^d expression is significantly increased. On the other hand, H-2 ^umice synthesize E chains; the poor expression of E ^d chains in this F₁ hybrid apparently reflects the strong preferential association of E ^u chains with all E molecules thus far analyzed. These results confirm that E chains compete for binding to E chains and that preferential association of different allelic forms of E chains with E chains is a generalized phenomenon. They also illustrate the importance of the rate of biosynthesis of Ia chains for cell-surface expression.     

Waves in a simple,excitable or oscillatory,reaction-diffusion model

A simple one variable caricature for oscillating and excitable reaction-diffusion systems is introduced. It is shown that as a parameter, , varies the system dynamics change from oscillatory ( > ₀) to excitable ( < ₀) and the frequency of the oscillation vanishes as for ₀. When such dynamics are coupled by continuous diffusion in a ring geometry (1-space dimension), propagating wave trains may be found. On an infinite ring excitable devices lead to unique solitary waves which are analogous to pulse waves. A solvable example is presented, illustrating properties of dispersion, excitability, and waves. Finally it is shown that the caricature arises in a natural way from more general excitable/oscillatory systems.     

Cloned T cells recognize Trichinella spiralis antigen in association with an Ek βEk α restriction element

A method is described for the production of T-cell lines and clones specific for solubilized Trichinella spiralis antigens. hese T cells are antigen-specific and do not respond to challenge with a third party antigen (lysozyme). The proliferation responses of the cloned T cells are specifically inhibited by anti-I-E but not by anti I-A subregion monoclonal reagents. The inhibition patterns obtained are consistent with cis-gene complementation in B10.K cells involving the E^k -chain and the E^k -chain of the I-E molecule. Inhibition is obtained with an E^k -specific monoclonal antibody (H9-14.8) but not with an A^k -specific monoclonal antibody (10-2.16). Inhibition was also observed with Ia.7-specific (H40-242) or Ia.22-specific (17-3-3) monoclonal antibodies. The inhibition patterns were confirmed by antigen presentation experiments using recombinant inbred mice. Only B 10.K (E^k E^k spleen cells and not B 10.A(5R) (E^b E^k ) or B10.S(9R) (E^s E^k ) spleen cells could effectively present T. spiralis antigens. The role of hybrid Ia molecules in the immune response to T. spiralis is discussed.     

Betaine or taurine administration prevents fibrosis and lipid peroxidation induced by rat liver by ethanol plus carbon tetrachloride intoxication

Summary. The aim of this study was to investigate the effect of betaine or taurine on liver fibrogenesis and lipid peroxidation in rats. Fibrosis was induced by treatment of rats with drinking water containing 5% ethanol and CCl₄ (2×weekly, 0.2ml/kg, i.p.) for 4 weeks. Ethanol plus CCl₄ treatment caused increased lipid peroxidation and disturbed antioxidant system in the liver. Histopathological findings suggested that the development of liver fibrosis was prevented in rats treated with betaine or taurine (1% v/v in drinking water) together with ethanol plus CCl₄ for 4 weeks. When hepatic taurine content was depleted with -alanine (3% v/v in drinking water), portal-central fibrosis induced by ethanol+CCl₄ treatment was observed to proceed cirrhotic structure. Betaine or taurine was also found to decrease serum transaminase activities and hepatic lipid peroxidation without any change in hepatic antioxidant system in rats with hepatic fibrosis. In conclusion, the administration of betaine or taurine prevented the development of liver fibrosis probably associated with decreased oxidative stress.     

Subtle behavioral variation in wild chimpanzees, with special reference to Imanishi’s concept of kaluchua

Here we consider the concept of kaluchua (a word adopted from the English culture) in group-living animals developed by Imanishi in the 1950s. He distinguished it from bunka (the Japanese equivalent to the English culture) because he thought that bunka had strong connotations of noble and intellectual human-like activities. Although he did not rigidly define kaluchua, his original concept of kaluchua was much broader than bunka and represented non-hereditary, acquired behavior that was acknowledged socially. However, instead of social life, complex feeding skills have often formed the central topic in the current studies of animal culture. In order to provide evidence that more subtle behavioral variations exist among wild chimpanzee (Pan troglodytes) populations, we directly compared the behaviors of two well-habituated chimpanzee groups, at Bossou and Mahale. During a 2-month stay at Bossou, M.N. (the first author) saw several behavioral patterns that were absent or rare at Mahale. Two of them, mutual genital touch and heel tap were probably customary for mature females and for mature males, respectively. Index to palm and sputter are still open to question. These subtle patterns occurred more often than tool use during the study period, suggesting that rarity is not the main reason for their being ignored. Unlike tool use, some cultural behavioral patterns do not seem to require complex skills or intellectual processes, and sometimes it is hard to explain the existence of such behaviors only in terms of function.     

Hb Mobile [α2β2 73(E17)Asp → Val]: A new variant

A new hemoglobin variant found in a mother and her child was characterized by column chromatography of the tryptic hydrolysate of the aminoethylated, glycinamidated -chain, followed by chymotryptic digestion of the abnormal T-9 peptide and amino acid analyses. It was shown to be _{2 2} 73(E17) Asp Val and named Hb Mobile.This work was supported in part by Research Grants AM0780 and AM13173 from the National Institute for Arthritis and Metabolic Disease.     

Purification and characterization of flavone-specific β-glucuronidase from callus cultures of Scutellaria baicalensis Georgi

-Glucuronidase from callus cultures of Scutellaria baicalensis Georgi was purified to apparent homogeneity by fractionated ammonium-sulfate precipitation and chromatography on diethylaminoethyl-cellulose, hydroxylapatite and baicalin-conjugated Sepharose 6B. A 650-fold purification was obtained by this purification system. When subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis the purified protein migrated as a single band with a molecular mass of 55 kDa. We determined that the native enzyme has a molecular mass of 230 kDa using gel-filtration chromatography. These results suggested that the enzyme exists as a homotetramer composed of four identical 55-kDa subunits. The enzyme showed a broad pH optimum between 7.0 and 8.0. The K _m values were 9 M, 10 M, 30 M and 40 M for luteolin 3 -O--d-glucuronide, baicalin, wogonin 7-O--d-glucoronide and oroxlin 7-O--d-glucuronide, respectively. The enzyme was most active with flavone 7-O--d-glucuronides.Abbreviations BA N⁶-benzyladenine - 2,4-D 2,4-dichlorophenoxyacetic acid - pI isoelectric point - R _t retention time     

Long Range Force between Pre-Replication Complexes (Pre-RC) in DNA Controls Replication and Cell Cycle Progression

A nonstationary interaction, that controls DNA replication and the cell cycle, is derived from a manybody physics model in a chemically open T cell. The model predicts a long range force F()=-(/2) (1-)(2-) between the pre-replication complexes (pre-RCs) bound by DNA, =/N being the relative displacement of preRCs, the number of pre-RCs, N the threshold for initiation, and the compressibility modulus in thelattice of pre-RCs which behaves like an elastically braced string. Initiation of DNA replication is induced by a switch of sign of F(), from attraction (-)and assembly in the G ₁ phase (0 < < N), to repulsion (+) and partialdisassembly in the S phase (N < < 2N), with release of licensing factors from the pre-RCs, thus explaining prevention of re-replication. Replication is terminated by a switch of sign of F at = 2N, when all primed replicons are duplicated once, and F(0)=0 corresponds to a resting cell in absence of driving force at = 0. The switch of sign of force at = N also explains the dynamic instability in growing microtubules (MTs), as well as switch in the interleukin-2 (IL2) interaction with its receptor in late G ₁, at the restriction point. Shape, slope and scale of the response curves derived agree well with experimental data from dividing T cells and polymerizing MTs, the variable length of which is due to anonlinear dependence of the growth amplitude on the initial concentrations of tubulin dimers and guanosine-tri-phosphate (GTP).     

UV-Sehfarbstoff bei Insekten

Summary From insect eyes, an u.v.-visual pigment A (_max 345 nm) was extracted by 2% aqueous digitonin (pH 5.2). Upon prolonged u. v. irradiation, A is converted to a stable product B (_max 480 nm), which reconverts completely to A when illuminated with light of longer wavelengths. When the pH of B is raised to 9.3, B is converted to C and absorbs at 375 nm. Experiments with NH₂OH lead us to the assumption that retinal is the prosthetic group of this pigment.

---

---

Die Arbeit wurde durch jugoslawische SBK- und SFNR-Fonds gefördert. K. Hamdorf und J. Schwemer danken der Deutschen Forschungsgemeinschaft für großzügige Unterstützung.     

Laser kinetic spectroscopy studies of the bimolecular oxygenation of alpha- and beta-subunits within the R-state of human hemoglobin

Bimolecular oxygenation of tri-liganded R-state human hemoglobin (HbA) is described by bi-exponential kinetics with association rate constants k = 27.2 ± 1.3 (M·sec)^-1 and k = 62.9 ± 1.6 (M·sec)^-1. Both the observed processes have been assigned to the bimolecular oxygenation of - and -subunits of the native tetrameric protein by molecular oxygen. The quantum yields of photodissociation within the completely oxygenated R-state HbA are = 0.0120 ± 0.0017 and = 0.044 ± 0.005 for - and -subunits, respectively. The oxygenation reactions of isolated ^PCMB- and ^PCMB-hemoglobin chains are described by mono-exponential kinetics with the association rate constants k = 44 ± 2 (M·sec)^-1 and k = 51 ± 1 (M·sec)^-1, respectively. The quantum yields of photodissociation of isolated ^PCMB- and ^PCMB-chains (0.056 ± 0.006 and 0.065 ± 0.006, respectively) are greater than that observed for appropriate subunits within the R-state of oxygenated HbA.     

Metabolism of a phenylcoumaran substructure lignin model compound in ligninolytic cultures of Phanerochaete chrysosporium

The degradation of the phenylcoumaran substructure model compound methyl dehydrodiconiferyl alcohol by the white-rot wood decay fungus Phanerochaete chrysosporium was investigated using culture conditions optimized for lignin oxidation. Initial attack was in the cinnamyl alcohol side chain, which was oxidized to a glycerol structure. This was subsequently converted by loss of the two terminal carbon atoms, C and C, to yield a C-aldehyde structure, which was further oxidized to the C-acid compound. The next detected intermediate, a phenylcoumarone, was produced by double bond formation between C and C, and oxidation of the C-alcohol to an aldehyde group. Further oxidation of C to an acid yielded the next intermediate. The final identified degradation product was veratric acid. No products from the 5-substituted aromatic ring, and no phenolic products, were found. The initial glycerol-containing intermediate was a mixture of the threo and erythro forms, and no optical activity could be found, suggesting that its formation might have involved nonstereospecific C-C epoxidation followed by non-enzymatic hydrolysis of the epoxide.Abbreviations TLC thin layer chromatography - LDA lithium diisopropyl amide - DDQ 2,3-dichloro-5,6-dicyanobenzoquinone - MS mass spectrometry - UV ultraviolet spectroscopy     

Optimizing control of a continuous stirred tank fermenter using a neural network

Feedforward neural networks are a general class of nonlinear models that can be used advantageously to model dynamic processes. In this investigation, a neural network was used to model the dynamic behaviour of a continuous stirred tank fermenter in view of using this model for predictive control. In this system, the control setpoint is not known explicitly but it is calculated in such a way to optimize an objective criterion. The results presented show that neural networks can model very accurately the dynamics of a continuous stirred tank fermenter and, the neural model, when used recursively, can predict the state variables over a long prediction horizon with sufficient accuracy. In addition, neural networks can adapt rapidly to changes in fermentation dynamics.List of Symbols F Dimensionless flow rate (F/ V₀) - F m³/h Flow rate - F ₀ m³/h Inlet flow rate - J Objective cost function - K _i Dimensionless constant in Eq. (3) (k _i /s₀) - k _i kg/m³ Substrate inhibition constant in Haldane model - k _m Dimensionless constant in Eq. (3) (k _s /s₀) - k _m kg/m³ Substrate inhibition constant in Haldane model - n prediction horizon - S Dimensionless substrate concentration (s/s₀) - s kg/m³ Substrate concentration - t h Time - v Dimensionless volume (V/V₀) - V m³ Liquid volume in fermenter - W _ij , W _jk Weight matrices in neural network - X Dimensionless biomass concentration - x kg/m³ Biomass concentration - Y Biomass/substrate yield coefficient - Weighting factor in Eq. (4) - Dimensionless specific growth rate (/ ) - 1/h Maximum specific growth rate - 1/h Specific growth rate - Dimensionless time ( t)     

Purification and characterization of aspartate aminotransferase from developing embryos of the camel tick Hyalomma dromedarii

Aspartate transaminase (AST) activity in the camel tick Hyalomma dromedarii was followed throughout embryogenesis. During purification of AST to homogeneity, ion exchange chromatography lead to four separate forms (termed I, II, III and IV). AST II with the highest specific activity was pure after chromatography on Sephacryl S-300. The molecular mass of AST II was 52KDa for the native enzyme, composed of one subunit of 50KDa. AST II had a Km value of 0.67mM for -ketoglutarate and 15.1mM for aspartate. AST II had a pH optimum of 7.5 with heat stability up to 50°C for 15min. The enzyme was activated by MnCl₂, and inhibited by CaCl₂, MgCl₂, NiCl₂, and ZnCl₂.     

Oxygen isotope fractionation during respiration for different temperatures ofT. utilis andE. coli K12

Summary The temperature dependence of the oxygen isotope fractionation factor during respiration has been examined for two different microorganisms, namelyTorulopsis utilis andEscherichia coli K12 representing a yeast and a bacterium, respectively. The investigation covered a temperature range of 18° C, that is from 16° C to 34° C forT. utilis and from 19° C to 37° C forE. coli K12. Within this temperature range the fractionation factor ofT. utilis increases by 0.18; an insignificant change ( _{10° C} = 0.063;r = 0.067), whereas withE. coli K 12 an increase of 1.12; has been observed ( _{10° C} = 0.6;r = 0.55).     

Uncoupling and isotope effects in γ-butyrobetaine hydroxylation

Replacement of unlabeled -butyrobetaine with -[2,3,4-²H₆]butyrobetaine has a profound effect on the stoichiometry between decarboxylation of 2-oxoglutarate and hydroxylation in the reaction catalyzed by human -butyrobetaine hydroxylase. The ratios between decarboxylation and hydroxylation are 1.16 with Unlabeled and 7.48 with deuterated -butyrobetaine as substrate. From these ratios an internal isotope effect of 41 has been calculated. DV in the overall reaction measured as 2- oxoglutarate decarboxylation is 2.5 and D_V/K is 1.0. For -butyrobetaine hydroxylase fromPseudomonas sp. AK 1, 2-oxoglutarate decarboxylation exceeds hydroxylation with 10% when deuterated -butyrobetaine is used. No excess was found with unlabeled substrate and no internal isotope effect could be calculated. D_V for the bacterial enzyme is 6.