Linnaeus's natural and artificial arrangements of plants

Linnaeus's artificial and natural arrangements of plants are examined using a Spearman rank coefficient (which is explained) on his presentations of his own and others' arrangements in the Classes plantarum and elsewhere. There is little alteration in his successive artificial arrangements. In contrast, between 1751 and 1764 his natural arrangements changed considerably, partly in the sequences of genera within orders but mostly by rearrangement of the orders. Comparison with Cesalpino's and Ray's natural arrangements, using the longest-recognized natural groups as signposts, suggests that Linnaeus in his latest natural arrangement (1764) approximated more closely to Ray's. Examination of Linnaeus's successive treatments of certain groups (palms, Zingiberaceae, Hydrocharis-Stratiotes-Vallisneria) and of Giseke's exposition of Linnaeus's lectures on natural groups (1792) shows that Linnaeus was much influenced by habitus and vegetative characters as well as those of the fructification. He recognized orders consisting of a chain of genera linked successively by overall affinity and without any single diagnostic character. Where possible, he preferred characters of the fructification and his ‘secret’ consulting of the habitus is explained as secondary to such characters. It is suggested that in his latest arrangement he approximated more to a scala naturae, as he probably did in zoology about the same time. Within his artificial arrangements Linnaeus kept to sequences of genera as natural as possible. He realized that some groups in his natural arrangements were still artificial, and his aphorism that all genera and species are natural, classes and orders part natural and part artificial, refers to his and others' practice until the natural system could be completed. It is not a statement of the essential natures of these ranks. Linnaeus's distinction in practice between natural and artificial arrangements was less clear-cut than Sachs believed. Linnaeus's rejection of the ancient tree/herb division was empirical, not a reasoned repudiation of an a priori grouping. The tree/herb division could be upheld in his day as obviously natural, not merely accepted on authority.     

Comparison of thermochemistry of aspartame (artificial sweetener) and glucose

We have compared the gas phase thermochemical properties of aspartame (artificial sweetener) and α- and β-glucose. These parameters include metal ion affinities with Li⁺-, Na⁺-, K⁺-, Mg⁺²-, Ca⁺²-, Fe⁺²-, Zn⁺²-ions, and chloride ion affinity by using DFT calculations. For example, for aspartame, the affinity values for the above described metal ions are, respectively, 86.5, 63.2, 44.2, 255.4, 178.4, 235.4, and 300.4, and for β-glucose are 65.2, 47.3 32.9, 212.9, 140.2, 190.1, and 250.0 kcal mol⁻¹, respectively. The study shows differences between the intrinsic chemistry of aspartame and glucose.     

New gene arrangements in natural populations of Drosophila subobscura

Four new gene arrangements were detected in natural populations of Drosophila subobscura near Zürich, Switzerland. Three of them are the result of inversions not recorded before, and one is a new combination of known gene arrangements. Another arrangement, I₃₊₄, was recorded for the first time in Switzerland. It may have been imported or possibly may have arisen de novo. It is suggested that inversion mutations are not so infrequent as so far supposed, if the presence of mobile elements is taken into account in D. subobscura.     

Characteristics of artificial forisomes from plants and yeast

Forisomes are protein bodies found exclusively in the phloem of the Fabaceae (legumes). In response to wounding, the influx of Ca ( 2+) induces a conformational change from a condensed to a dispersed state which plugs the sieve tubes and prevents the loss of photoassimilates. This reversible, ATP-independent reaction can be replicated with purified forisomes in vitro by adding divalent cations or electrically inducing changes in pH, making forisomes ideal components of technical devices. Although native forisomes comprise several subunits, we recently showed that functional homomeric forisomes with distinct properties can be expressed in plants and yeast, providing an abundant supply of forisomes with tailored properties. Forisome subunits MtSEO-F1 and MtSEO-F4 can each assemble into homomeric artificial forisomes, which indicates functional redundancy. However, we provide further evidence that both proteins are subunits of the native heteromeric forisome body in planta. We also show that the properties of artificial forisomes can be modified by immobilization, which is a prerequisite for their incorporation into technical devices.     

Linnaeus's butterflies (Lepidoptera: Papilionoidea and Hesperioidea)

The names of all the species of butterflies described by Linnaeus under "Papilio" are researched. Of the 305 names treated, 243 (c. 80%) are currently valid as specific (241) or subspecific (2), 29 are junior synonyms, 14 are invalid (one of these applying to a fake), and for 13 the identity is unknown or uncertain. Six species of moths misidentified by Linnaeus as butterflies are cited in the study, but details are not included. One hundred and fifty-two lectotypes have been designated, representing about 56% of the sum of the valid names and junior synonyms. Of these, 99 were selected from specimens in the Linnean Society of London, 52 from Queen Ludovica Ulrica's collection, Uppsala, and one lectotype is a Petiver specimen from the collection of Sir Hans Sloane. Linnaeus described at least five species, possibly eight, from the literature alone. All Linnaean material examined is documented, as are 'subsequent' specimens that are associated with Linnaean material. Synonymy and homonymy are discussed and presented, as are the identities of type localities. Care has been taken to achieve a practical balance between Linnaean and current species identities. Linnaean material studied included specimens from The Linnean Society of London, Museum Ludovicae Ulricae (Uppsala University), the Clerck and De Geer collections in the Naturhistoriska Riksmuseet, Stockholm, and the collection of James Petiver, now part of the collection of Sir Hans Sloane housed in The Natural History Museum, London.     

Modelling natural and artificial hands with synergies

We report on recent work in modelling the process of grasping and active touch by natural and artificial hands. Starting from observations made in human hands about the correlation of degrees of freedom in patterns of more frequent use (postural synergies), we consider the implications of a geometrical model accounting for such data, which is applicable to the pre-grasping phase occurring when shaping the hand before actual contact with the grasped object. To extend applicability of the synergy model to study force distribution in the actual grasp, we introduce a modified model including the mechanical compliance of the hand's musculotendinous system. Numerical results obtained by this model indicate that the same principal synergies observed from pre-grasp postural data are also fundamental in achieving proper grasp force distribution. To illustrate the concept of synergies in the dual domain of haptic sensing, we provide a review of models of how the complexity and heterogeneity of sensory information from touch can be harnessed in simplified, tractable abstractions. These abstractions are amenable to fast processing to enable quick reflexes as well as elaboration of high-level percepts. Applications of the synergy model to the design and control of artificial hands and tactile sensors are illustrated.     

Oxomanganese complexes for natural and artificial photosynthesis

The oxygen-evolving complex (OEC) of Photosystem II (PSII) is an oxomanganese complex that catalyzes water-splitting into O2, protons and electrons. Recent breakthroughs in X-ray crystallography have resolved the cuboidal OEC structure at 1.9 ? resolution, stimulating significant interest in studies of structure/function relations. This article summarizes recent advances on studies of the OEC along with studies of synthetic oxomanganese complexes for artificial photosynthesis. Quantum mechanics/molecular mechanics hybrid methods have enabled modeling the S1 state of the OEC, including the ligation proposed by the most recent X-ray data where D170 is bridging Ca and the Mn center outside the CaMn3 core. Molecular dynamics and Monte Carlo simulations have explored the structural/functional roles of chloride, suggesting that it regulates the electrostatic interactions between D61 and K317 that might be critical for proton abstraction. Furthermore, structural studies of synthetic oxomanganese complexes, including the [H2O(terpy)MnIII(μ-O)2MnIV(terpy)OH2]3+ (1, terpy=2,2':6',2″-terpyridine) complex, provided valuable insights on the mechanistic influence of carboxylate moieties in close contact with the Mn catalyst during oxygen evolution. Covalent attachment of 1 to TiO2 has been achieved via direct deposition and by using organic chromophoric linkers. The (III,IV) oxidation state of 1 attached to TiO2 can be advanced to (IV,IV) by visible-light photoexcitation, leading to photoinduced interfacial electron transfer. These studies are particularly relevant to the development of artificial photosynthetic devices based on inexpensive materials.     

Field performance of artificial seed-derived sugarcane plants

This study shows the behaviour of sugarcane plants cv. CP-5243 derived from artificial seed compared with traditional and isolated bud methods. Artificial seed-acclimatised plants were planted in field conditions simultaneously with two-control treatments previously germinated: macropropagated plants derived from stems of three buds and axillary buds isolated from field-grown plants. Plants from artificial seed were taller and had a smaller diameter at 8 months, but these differences disappeared at 12 months. With respect to sugar analysis and yield, no differences in all parameters evaluated were found between artificial seed-derived plants and plants derived from the two other methods.     

Interaction of duramycin with artificial and natural membranes

Duramycin is a polypeptide antibiotic (molecular weight 2012) obtained from culture filtrates of Streptomyces cinnamomeus forma azacoluta. In this work, we show that low concentrations of duramycin induced aggregation of lipid vesicles containing unsaturated phosphatidylethanolamine and unsaturated monogalactosyl diglyceride, and of sarcoplasmic reticulum vesicles from rabbit skeletal muscle. Furthermore, duramycin inhibited the ATP-dependent Ca2+ uptake in sarcoplasmic reticulum vesicles without affecting the hydrolysis of ATP or the permeability of Ca2+. Also, duramycin only inhibited the bacteriorhodopsin proton pump reconstituted into phospholipid vesicles containing phosphatidylethanolamine. We have isolated a duramycin-resistant strain of Bacillus subtilis and have mapped the location of duramycin resistance. In this strain, the secretion of protons and influx of calcium were resistant to duramycin, and its lipid composition was profoundly different from that of the parent strain. No phosphatidylethanolamine was detected in the resistant strain. Our findings are consistent with the idea that duramycin recognizes a particular membrane conformation determined by the presence of phosphatidylethanolamine or monogalactosyl diglyceride.     

Biochemical evaluation and molecular docking assessment of Cymbopogon citratus as a natural source of acetylcholine esterase (AChE)- targeting insecticides

Acetylcholinesterase (AChE) has been an effective target for insecticide development which is a very important aspect of the global fight against insect-borne diseases. The drastic reduction in the sensitivity of insects to AChE-targeting insecticides like organophosphates and carbamates have increased the need for insecticides of natural origin. In this study, we used Drosophila melanogaster as a model to investigate the insecticidal and AChE inhibitory potentials of Cymbopogon citratus and its bioactive compounds. Flies were exposed to 100 and 200 mg/mL C. citratus leaf extract for a 3-h survival assay followed by 45 min exposure for negative geotaxis and biochemical assays. Molecular docking analysis of 45 bioactive compounds of the plant was conducted against Drosophila melanogaster AChE (DmAChE). Exposure to C. citratus significantly reduced the survival rate of flies throughout the exposure period and this was accompanied by a significant decrease in percentage negative geotaxis, AChE activity, catalase activity, total thiol level and a significant increase in glutathione-S-transferase (GST) activity. The bioactive compounds of C. citratus showed varying levels of binding affinities for the enzyme. (+)-Cymbodiacetal scored highest (?9.407 kcal/mol) followed by proximadiol (?8.253 kcal/mol), geranylacetone (?8.177 kcal/mol), and rutin (?8.148 kcal/mol). The four compounds occupied the same binding pocket and interacted with important active site amino acid residues as the co-crystallized ligand (1qon). These compounds could be responsible for the insecticidal and AChE inhibitory potentials of C. citratus and they could be further explored in the development of AChE-targeting insecticides.     

Predicting natural mortality rates of plants and animals

Understanding the factors that control the mortality rates of species in their natural environments is important for understanding the structure and dynamics of populations, communities and ecosystems. Here, we test a model of natural mortality that yields explicit, quantitative predictions based on the constraints of body size and temperature on individual metabolism. Extensive field data from plants, invertebrates, fish, birds and mammals indicate that much of the heterogeneity in rates of natural mortality can be predicted, despite the many extrinsic sources of mortality in natural systems. These results suggest that common 'rule(s)' govern mortality rates in ecological communities for organisms as diverse as plants and animals.     

Competitive relationships in natural and artificial algal communities

Modern data on competitive relationships and their role in the succession of natural and artificial algal communities are reviewed. The mechanisms of macroalgae competition and the factors that affect the competitive outcomes are considered. The conception of competitive interactions between seaweeds in the field and culture is suggested. (1) Competitive relationships are possible only between seaweeds which live together and are able to exchange signals. (2) Success in the competition for light is the basis for wins in the competition for space. (3) The competition for nutrients never results directly in the exclusion of the competitor from the community. It inhibits the competitor and allows the winner to overgrow, shade, act allelopathically, and to displace the inferior competitor in the community. (4) People, creating an artificial monodominant community, either increase the competitive potential of cultivated species by selection of growth conditions or exclude the competitors.     

天然丝的形成及人工纺丝的研究进展

蜘蛛丝和蚕丝是性能优异的天然丝类材料,具有极高的力学性能、良好的生物相容性和生物可降解性,可广泛应用于纺织、光学、电子、生物医学和环境工程等领域。迄今为止,已经有湿法纺丝、干法纺丝和静电纺丝等多种在实验室规模下进行人工纺丝的方法。然而,现阶段大部分的人工丝纤维性能仍比不上天然丝纤维。处理好人工丝纤维层级结构和力学性能之间的关系,是人工纺丝领域亟待解决的问题。文中围绕天然丝纤维的形成、丝纤维力学性能与层级结构的关系、人工纺丝领域的研究进展和丝纤维的应用等方面进行了介绍。     

A comparison of fens in natural and artificial landscapes

Fens depend on inputs of groundwater or surface water. In Western Europe especially soligenous fens, receiving groundwater, are threatened by human hydrological intervention. We demonstrate the impact of artificial versus natural hydrologies on such fens by comparing 3 case areas: the Biebrza valley (reference) and the Gorecht and Vecht river plains (both reclaimed and drained). The patterns found in the fairly undisturbed Biebrza area suggest local water quality is governed by a strong regional groundwater flow emerging in the fen near the valley margins and seeping through it down to the river. Hence water quality gradients are smooth: there is little variation in water type over large distances. The pattern is determined by the natural geomorphology. In the reclaimed Vecht and Gorecht river plains large differences exist at short distance. Regional water flow from the adjacent ridges into the plains is weak here and governed primarily by water management (polders and pumping wells). However, the relations between specific water types and fen species and communities in this artificial pattern are quite similar to those found in the natural landscape. Low-productive rich fens are fed by calcium-rich and base-rich, nutrient-poor groundwater in both cases. While conservation of such rich fens is served best by maintaining the natural groundwater flow, some opportunities for restoration with an artificial hydrology are discussed.     

Effects of cycloartenol and lanosterol on artificial and natural membranes

Cycloartenol, a 9,19-cyclopropane sterol which is isomeric with lanosterol, showed an ability intermediate between lanosterol and cholesterol to increase the microviscosity of lecithin vesicles, to serve as a growth factor for the sterol auxotroph $\text{Mycoplasma capricolum}$, and to increase the microviscosity of $\text{M. capricolum}$ membranes. The corresponding membrane effects of cyclolaudenol which contains a methyl group added to C-24 of the isooctenyl side chain of cycloartenol are more like those shown by lanosterol. We propose that the enhanced effectiveness of cycloartenol over lanosterol is due to a more favorable spatial disposition of the angular 14α-methyl group on the α-face of the molecule promoting more effective van der Waals contacts between the phospholipid fatty acyl chains and the sterol α-face. Side chain alkylation appears to perturb such contacts, reducing the effectiveness of cyclolaudenol for competent membrane function in $\text{M. capricolum}$.     

Linkage disequilibria between mtDNA haplotypes and chromosomal arrangements in a natural population of Drosophila subobscura

The association between mtDNA haplotypes and chromosomal arrangements in a natural population of Drosophila subobscura from Calvia (Balearic Islands, Spain) was studied in order to search for linkage disequilibria, in an attempt to explain the populational dynamics of the mtDNA haplotypes of this species in nature. The presence of Wolbachia was not detected. Two main haplotypes (I and II) were found, as well as a series of less common ones. The Tajima D-test seemed to indicate some kind of seasonal population bottleneck. An analysis of linkage disequilibrium and factorial analysis of correspondences detected an association between haplotype I and the J(ST) inversion and haplotype II and the J(1) inversion.