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1.
Lloyd Demetrius 《Bulletin of mathematical biology》1968,30(1):117-122
In previous studies of (M,R) (Rosen, 1961; Demetrius, 1966), it was assumed that changes in the structure of (M,R) which were induced by environmental alternations occurred without error. Here, the effect of both “genetic” and “metabolic”
malfunctions on the behavior of (M,R) is examined and a subclass of these systems whose behavior is invulnerable to such errors is specified. 相似文献
2.
N. Rashevsky 《Bulletin of mathematical biology》1960,22(1):73-84
The principle of biotopological mapping (Rashevsky, 1954,Bull. Math. Biophysics,16, 317–48) is given a generalized formulation, as the principle of relational epimorphism in biology. The connection between
this principle and Robert Rosen’s representation of organisms by means of categories (1958,Bull. Math. Biophysics,20, 317–41) is studied. Rosen’s theory of (M,R)-systems, (1958,Bull. Math. Biophysics,20, 245–60) is generalized by dropping the assumption that only terminalM
i
components are sending inputs into theR
i
components. It is shown that, if the primordial organism is an (M,R)-system, then the higher organisms, obtained by a construction well discussed previously (1958,Bull. Math. Biophysics,20, 71–93), are also (M,R)-systems. Several theorems about such derived (M,R)-systems are demonstrated.
It is shown that Rosen’s concept of an organism as a set of mappings throws light on phenomena of synesthesia and also leads
to the conclusion that Gestalt phenomena must occur not only in the fields of visual and auditory perception but in perceptions
of any modality. 相似文献
3.
Lloyd A. Demetrius 《Bulletin of mathematical biology》1966,28(2):153-160
Rosen’s identification of abstract biological systems, called (M,R)-systems, with sequential machines is formally characterized. It is then shown that the determination of environmental alterations
of (M,R)-systems from a knowledge of the response sequence and the structure of the system, which we call behavioral reversibility,
can be interpreted as information-losslessness of sequential machines. Applying this relationship, necessary conditions for
behavioral reversibility are derived. It is further shown that, similar to Rosen’s work on structural reversibility, (M,R)-systems are behaviorally reversible only if the number of physically realizable mappings are restricted. 相似文献
4.
Divergent scaling of respiration rates to nitrogen and phosphorus across four woody seedlings between different growing seasons
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Ruirui Fan Jun Sun Fuchun Yang Man Li Yuan Zheng Quanlin Zhong Dongliang Cheng 《Ecology and evolution》2017,7(21):8761-8769
Empirical studies indicate that the exponents governing the scaling of plant respiration rates (R) with respect to biomass (M) numerically vary between three‐fourth for adult plants and 1.0 for seedlings and saplings and are affected by nitrogen (N) and phosphorus (P) content. However, whether the scaling of R with respect to M (or N and P) varies among different phylogenetic groups (e.g., gymnosperms vs. angiosperms) or during the growing and dormant seasons remains unclear. We measured the whole‐plant R and M, and N and P content of the seedlings of four woody species during the growing season (early October) and the dormant season (January). The data show that (i) the scaling exponents of R versus M, R versus N, and R versus P differed significantly among the four species, but (ii), not between the growing and dormant seasons for each of the four species, although (iii) the normalization constants governing the scaling relationships were numerically greater for the growing season compared to the dormant season. In addition, (iv) the scaling exponents of R versus M, R versus N, and R versus P were numerically larger for the two angiosperm species compared to those of the two gymnosperm species, (v) the interspecific scaling exponents for the four species were greater during the growing season than in the dormant season, and (vi), interspecifically, P scaled nearly isometric with N content. Those findings indicate that the metabolic scaling relationships among R, M, N, and P manifest seasonal variation and differ between angiosperm and gymnosperm species, that is, there is no single, canonical scaling exponent for the seedlings of woody species. 相似文献
5.
Allometric scaling relationship between above‐ and below‐ground biomass within and across five woody seedlings
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Allometric biomass allocation theory predicts that leaf biomass (ML) scaled isometrically with stem (MS) and root (MR) biomass, and thus above‐ground biomass (leaf and stem) (MA) and root (MR) scaled nearly isometrically with below‐ground biomass (root) for tree seedlings across a wide diversity of taxa. Furthermore, prior studies also imply that scaling constant should vary with species. However, litter is known about whether such invariant isometric scaling exponents hold for intraspecific biomass allocation, and how variation in scaling constants influences the interspecific scaling relationship between above‐ and below‐ground biomass. Biomass data of seedlings from five evergreen species were examined to test scaling relationships among biomass components across and within species. Model Type II regression was used to compare the numerical values of scaling exponents and constants among leaf, stem, root, and above‐ to below‐ground biomass. The results indicated that ML and MS scaled in an isometric or a nearly isometric manner with MR, as well as MA to MR for five woody species. Significant variation was observed in the Y‐intercepts of the biomass scaling curves, resulting in the divergence for intraspecific scaling and interspecific scaling relationships for ML versus MS and ML versus MR, but not for MS versus MR and MA versus MR. We conclude, therefore, that a nearly isometric scaling relationship of MA versus MR holds true within each of the studied woody species and across them irrespective the negative scaling relationship between leaf and stem. 相似文献
6.
Based on a Cambridge Structural Database (CSD) search, a meta‐analysis of 116 structures of alanine H3NCαH(CH3)C′(O)O and its derivatives H3NCαH(CH3)C′(O)O(H/R/M), protonated, esterified, or coordinated at the carboxylic group, shows that in the first step of a chirality chain, the L configuration at Cα induces (M) and (P) conformations with respect to rotation around the central C′─Cα bond. In the second step, the (M) and (P) conformations selectively distort the planar carboxylic group CαC'(Ocis)Otrans to asymmetric flat (R) and (S) tetrahedra. High diastereoselectivities are caused by the two players attraction N…Ocis and repulsion Otrans…CMe, which work together in (L,M,R) configurations but against each other in (L,P,S) configurations. 相似文献
7.
Axially chiral biphenyls such as (M,S)‐ 3k have been conveniently obtained by crystallization of their diastereomeric mixtures, which were synthesized from racemic 4,4′‐dimethoxy‐5,6,5′,6′‐bis(methylenedioxy)‐2‐carboxylester‐2′‐carboxyl‐biphenyls 4 and chiral amino alcohols (R)‐alaninol, (S)‐alaninol, (S)‐valinol, and (S)‐phenylalaninol. A crystallization‐induced configuration transformation of the biphenyls was thus achieved. It was found that amide formation of an (S)‐valinol or (S)‐phenylalaninol at the 2′‐position of the biphenyl usually induced the deposition of crystals with the (M)‐configuration from ethanol in yields higher than 50%. The absolute configurations (ACs) of two crystalline biphenyls have been determined by X‐ray crystallographic analysis. The ACs of nine biphenyls have been assigned based on their CD spectra. Further, stability investigation of these axially chiral biphenyls revealed that the ACs could revert upon redissolution. The energy barrier to epimerization between (P,R)‐ 3b and (M,R)‐ 3b was measured as ΔG# = 21.45 kcal/mol and the half‐life in ethanol at 301 K was 17.1 h. Chirality, 2010. © 2010 Wiley‐Liss, Inc. 相似文献
8.
T. Suzuki N. Kasai R. Yamamoto N. Minamiura 《Applied microbiology and biotechnology》1994,42(2-3):270-279
The mechanism of the novel enzymatic dehalogenating action of (R)-3-chloro-1,2-propanediol [monochlorohydrin (MCH)] was investigated. The (R)-MCH-dechlorinating enzyme system ofAlcaligenes sp. DS-S-7G, which stereoselectively assimilated (R)-MCH from the racemate, was composed of two components (Enzyme 1 and Enzyme 2). Enzyme 1 was a flavoprotein with a relative molecular mass (M
r) of 70,000 and was composed of two kinds of polypeptides (58,000 and 16,000). The enzyme exhibited activity for converting (R)-MCH to hydroxyacetone with the liberation of chloride ions under aerobic conditions. On the other hand, Enzyme 2 with anM
r of 86,000, which was also composed of two kinds of polypeptides (33,000 and 53,000), showed no dechlorinating activity for (R)-MCH. However, in the presence of NAD+, when Enzyme 1 was conjugated with Enzyme 2 in the (R)-MCH-dechlorinating reaction, the co-operative dechlorinating activity was four to five times higher than that by Enzyme 1 alone. (R)-MCH was finally degraded to acetic acid and formic acid by the joint action of the two enzymes. These facts indicate that (R)-MCH is oxidatively dechlorinated by the two enzymes in the presence of NAD+ inAlcaligenes sp. DS-S-7G. 相似文献
9.
This study provides the first measurements of the standard respiration rate (RS) and growth dynamics of European sardine Sardina pilchardus larvae reared in the laboratory. At 15° C, the relationship between RS (µl O2 individual?1 h?1) and larval dry mass (MD, µg) was equal to: RS = 0·0057(±0·0007, ± s.e.)·MD0·8835(±0·0268), (8–11% MD day?1). Interindividual differences in RS were not related to interindividual differences in growth rate or somatic (Fulton's condition factor) or biochemical‐based condition (RNA:DNA). 相似文献
10.
Given a sequenceA and regular expressionR, theapproximate regular expression matching problem is to find a sequence matchingR whose optimal alignment withA is the highest scoring of all such sequences. This paper develops an algorithm to solve the problem in timeO(MN), whereM andN are the lengths ofA andR. Thus, the time requirement is asymptotically no worse than for the simpler problem of aligning two fixed sequences. Our
method is superior to an earlier algorithm by Wagner and Seiferas in several ways. First, it treats real-valued costs, in
addition to integer costs, with no loss of asymptotic efficiency. Second, it requires onlyO(N) space to deliver just the score of the best alignment. Finally, its structure permits implementation techniques that make
it extremely fast in practice. We extend the method to accommodate gap penalties, as required for typical applications in
molecular biology, and further refine it to search for substrings ofA that strongly align with a sequence inR, as required for typical data base searches. We also show how to deliver an optimal alignment betweenA andR in onlyO(N+logM) space usingO(MN logM) time. Finally, anO(MN(M+N)+N
2logN) time algorithm is presented for alignment scoring schemes where the cost of a gap is an arbitrary increasing function of
its length. 相似文献
11.
Himadri B. Bohidar 《Biopolymers》1998,45(1):1-8
Aggregation behavior and hydrodynamic parameters of insulin have been determined from static and dynamic light scattering experiments and intrinsic viscosity measurements carried out at pH 4.0, 7.5, and 9.0 in the temperature range 20–40°C in aqueous solutions. The protein aggregated extensively at elevated temperatures in the acidic solutions. Intermolecular interactions were found to be attractive and to increase with temperature. The measured intrinsic viscosity [η], diffusion coefficient D0, molecular weight M, and radius of gyration Rg exhibited the universal behavior: M[η] = (2.4 ± 02) × 10−27 (Re,η/Re,D)3(D0η/T)−3 and (D0√n)−1 ≃ (√6 πη0ζβ/kBT) [1 + 0.201)(v/β3)√n], where n is the number of segments in the polypeptide. The effective hydrodynamic radii deduced from [η], (Re, η) and the same deduced from D0, (Re,D) showed a constant ratio, (Re,η/Re,D = 1.1 ± 0.1). Re,D/Rg = ξ was found to be (0.76 ± 0.07). From the known solvent viscosity η0, the segment length β was deduced to be (10 ± 1) Å. The excluded volume was deduced to be (5 Å)3 regardless of pH. The Flory-Huggins interaction parameter was found to be χ = 0.45 ± 0.04, independent of pH and temperature. © 1998 John Wiley & Sons, Inc. Biopoly 45: 1–8, 1998 相似文献
12.
J. M. Lawson S. J. Foster A. C. O. Lim V. C. Chong A. C. J. Vincent 《Journal of fish biology》2015,86(1):1-15
Life‐history variables for three incidentally captured species of seahorse (Kellogg's seahorse Hippocampus kelloggi, the hedgehog seahorse Hippocampus spinosissimus and the three‐spot seahorse Hippocampus trimaculatus) were established using specimens obtained from 33 fisheries landing sites in Peninsular Malaysia. When samples were pooled by species across the peninsula, sex ratios were not significantly different from unity, and height and mass relationships were significant for all species. For two of these species, height at physical maturity (HM) was smaller than the height at which reproductive activity (HR) commenced: H. spinosissimus (HM = 99·6 mm, HR = 123·2 mm) and H. trimaculatus (HM = 90·5 mm, HR = 121·8 mm). For H. kelloggi, HM could not be estimated as all individuals were physically mature, while HR = 167·4 mm. It appears that all three Hippocampus spp. were, on average, caught before reproducing; height at 50% capture (HC) was ≥HM but ≤HR. The results from this study probe the effectiveness of assessment techniques for data‐poor fisheries that rely heavily on estimates of length at maturity, especially if maturity is poorly defined. Findings also question the sustainability of H. trimaculatus catches in the south‐west region of Peninsular Malaysia, where landed specimens had a notably smaller mean height (86·2 mm) and markedly skewed sex ratio (6% males) compared with samples from the south‐east and north‐west of the peninsula. 相似文献
13.
Vincent Mutel Geo Adam Sylvie Chaboz John A. Kemp Agnés Klingelschmidt Jürg Messer Jürgen Wichmann Thomas Woltering John Grayson Richards 《Journal of neurochemistry》1998,71(6):2558-2564
Abstract: [(2S,2′R,3′R)-2-(2′,3′-[3H]Dicarboxycyclopropyl)glycine ([3H]DCG IV) binding was characterized in vitro in rat brain cortex homogenates and rat brain sections. In cortex homogenates, the binding was saturable and the saturation isotherm indicated the presence of a single binding site with a KD value of 180 ± 33 nM and a Bmax of 780 ± 70 fmol/mg of protein. The nonspecific binding, measured using 100 µM LY354740, was <30%. NMDA, AMPA, kainate, l (?)-threo-3-hydroxyaspartic acid, and (S)-3,5-dihydroxyphenylglycine were all inactive in [3H]DCG IV binding up to 1 mM. However, several compounds inhibited [3H]DCG IV binding in a concentration-dependent manner with the following rank order of potency: LY341495 = LY354740 > DCG IV = (2S,1′S,2′S)-2-(2-carboxycyclopropyl)glycine > (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid > (2S,1′S,2′S)-2-methyl-2-(2-carboxycyclopropyl)glycine > l -glutamate = ibotenate > quisqualate > (RS)-α-methyl-4-phosphonophenylglycine = l (+)-2-amino-3-phosphonopropionic acid > (S)-α-methyl-4-carboxyphenylglycine > (2S)-α-ethylglutamic acid > l (+)-2-amino-4-phosphonobutyric acid. N-Acetyl-l -aspartyl-l -glutamic acid inhibited the binding in a biphasic manner with an IC50 of 0.2 µM for the high-affinity component. The binding was also affected by GTPγS, reducing agents, and CdCl2. In parasagittal sections of rat brain, a high density of specific binding was observed in the accessory olfactory bulb, cortical regions (layers 1, 3, and 4 > 2, 5, and 6), caudate putamen, molecular layers of the hippocampus and dentate gyrus, subiculum, presubiculum, retrosplenial cortex, anteroventral thalamic nuclei, and cerebellar granular layer, reflecting its preferential (perhaps not exclusive) affinity for pre- and postsynaptic metabotropic glutamate mGlu2 receptors. Thus, the pharmacology, tissue distribution, and sensitivity to GTPγS show that [3H]DCG IV binding is probably to group II metabotropic glutamate receptors in rat brain. 相似文献
14.
Sergent D Wang Q Sasaki NA Ouazzani J 《Bioorganic & medicinal chemistry letters》2008,18(15):4332-4335
The first synthesis of an optically pure (2R,3R,4S)-hydantoin 2, analogue of (2S,3R,4S)-4-hydroxyisoleucine, was achieved in two steps in un-optimized 35% overall yield from previously reported aldehyde synthon 1. (2R,3R,4S)-Hydantoin is stable at acidic pH. This solves the major drawback of (2S,3R,4S)-4-hydroxyisoleucine that easily cyclizes into inactive lactone. Furthermore, (2R,3R,4S)-hydantoin stimulates the insulin secretion by 150% at 25 μM compared with 4-hydroxyisoleucine and insulin secretagogue drug repaglinide. In view of its stability and biological activity, (2R,3R,4S)-hydantoin represents a good candidate for type-2 diabetes management and control. 相似文献
15.
In the present study, dry mass (MD, μg) and routine respiration rate (RR) (μl O2 ind?1 h?1) were measured for larval cod, Gadus morhua (L.) that were reared and tested at 5.0, 7.5, and 10.0°C. Bi‐hourly measurements of RR were made on groups of larvae using a closed‐circuit respirometer over a 24‐h period (14L : 10D light regime) to test temperature and body size effects and whether unfed larvae exhibited diel differences in metabolism. At 10°C, the relationship between mean RR and mean MD was: ln RR = 1.16·lnMD ? 6.57 (n = 31, r2 = 0.883, P < 0.001). The exponential increase in RR with temperature was described by a Q10 of 3.00. Diel differences in unfed larvae were only apparent in groups of the largest larvae. A comparison of Q10 estimates from this and other studies suggest a linear decrease in the effect of temperature on cod RR with increasing log MD for sizes encompassing larvae to large juveniles. The trend may explain, in part, observations of cod juveniles exploiting a wider range of in situ temperatures than larvae. Finally, the two most comprehensive data sets on larval cod RR compare poorly (approximately five‐fold differences) and our results support the assertion that daily metabolic energy loss in many larval cod individual‐based models were based upon measurements that over‐estimated hourly metabolic rates by a factor of approximately four. 相似文献
16.
Antje Bodensieck Walter M.F. Fabian Olaf Kunert Ferdinand Belaj Sajid Jahangir Wolfgang Schühly Rudolf Bauer 《Chirality》2010,22(3):308-319
In‐depth conformational analyses of 10 known eremophilane (= (1S,4aR,7R,8aR)‐decahydro‐1,8a‐dimethyl‐7‐(1‐methylethyl)napththalene) sesquiterpenes, 1 – 10 , from Petasites hybridus were performed with molecular mechanics as well as density functional theory methods. Electronic transition energies and rotational strengths of these eight eremophilane lactones and two petasins were calculated by time‐dependent density functional theory (B3PW91/TZVP). The absolute configurations of the constituents could be assigned by comparison of their simulated and experimental circular dichroism (CD) spectra in methanol as (4S,5R,8S,10R) ( 1 , 2 ), (2R,4S,5R,8S,10R) ( 3 , 4 , 5 ), (2R,4S,5R,8R,9R,10R) ( 6 ), (2R,4S,5R,8R,10R) ( 7 , 8 ), and (3R,4R,5R) ( 9 , 10 ). Single‐crystal X‐ray diffraction data of 8β‐hydroxyeremophilanolide ((8S)‐8‐hydroxyeremophil‐7(11)‐en‐12,8‐olide) ( 1 ) served as starting point for the theoretical conformational calculations of the 8β‐epimers of the eremophilane lactones. Experimental CD spectra as well as 1H NMR spectra of compound 1 in methanol were considerably dependent on sample concentration. Chirality, 2010. © 2009 Wiley‐Liss, Inc. 相似文献
17.
Three 2,3‐dihydro‐1H‐isoindol‐1‐ones structurally related with piracetam (=2‐oxopyrrolidine‐1‐acetamide) have been synthesized and tested for their nootropic effects in the passive avoidance test in mice. Compounds (RS)‐ 2 , (R,R)‐ 3 , and (R,S)‐ 3 were obtained in good yields in only two steps starting from methyl dl ‐phthaloylalanine. Compound (RS)‐ 2 exhibited nootropic activity at lower doses than piracetam, used as reference drug, but it showed lower efficacy. Whereas diastereoisomers (R,R)‐ 3 and (R,S)‐ 3 were as potent as piracetam to revert amnesia induced by scopolamine, (R,S)‐ 3 showed lower efficacy than (R,R)‐ 3 . Only (R,R)‐ 3 showed myorelaxant effect at doses of 10 and 30 mg/kg; other compounds did not exhibit any anticonvulsant, sedative, myorelaxant, or impaired motor‐coordination effect in mice. These synthesized 2,3‐dihydro‐1H‐isoindol‐1‐one derivatives constitute a new kind of nootropic compounds. 相似文献
18.
J. Lucas A. Schouman L. Lyphout X. Cousin C. Lefrancois 《Journal of fish biology》2014,84(4):1171-1178
The relationship between body mass (M) and metabolic rate was investigated through the assessment of active (RA) and standard (RS) metabolic rate at different life stages in zebrafish Danio rerio (5 day‐old larvae, 2 month‐old juveniles and 6 month‐old adults). Scaling exponents and constants were assessed for standard (RS = 0·273M0·965 in mgO2 g?1 h?1) and active metabolic rate (RA = 0·799M0·926 in mgO2 g?1 h?1). These data provide the basis for further experiments regarding the effects of environmental factors on aerobic metabolism throughout the life cycle of this species. 相似文献
19.
Lloyd Demetrius 《Bulletin of mathematical biology》1968,30(1):105-116
The definition of an (M,R) is formulated in a way that emphasizes its mathematical properties. Neglecting interactions between the components, it is shown that:
- An (M,R) contains only one non-reestablishable component.
- If an (M,R) contains only one non-reestablishable component, then that component is central.
20.
Gwon-Soo Kim Si-Hyung Park Yung-Jin Chang Yoong-Ho Lim Soo-Un Kim 《Biotechnology letters》2002,24(19):1553-1556
(+)-Isopiperitenone (100 mg l–1) was converted into (4S,6R)-6-hydroxy- and (4S,8R)-8,9-epoxyisopiperitenone, aside from the already known (+)-7-hydroxyisopiperitenone, by suspension cell culture of Mentha piperita. As (–)-isopiperitenone was hydroxylated similarly, this implies that the hydroxylating enzyme(s) have a broad substrate stereospecificity in regards to the stereochemistry at C4. (–)-(4R)-Carvone was reduced by the Mentha cells both at carbonyl and C1-C6 double bond to give (1R,2S,4R)-neodihydrocarveol and (1R,2R,4R)-dihydrocarveol with the former being the major product. (+)-(4S)-Carvone had a similar reduction pattern, producing (1S,2R,4S)-neodihydrocarveol and (1S,4S)-dihydrocarvone. Formation of these compounds indicates that the peppermint cell culture cannot only hydroxylate the allylic position but also reduce the ,-unsaturated carbonyl system. 相似文献