Kinetics of the actomyosin ATPase. Four or six states?

Tesi et al. [(1990) FEBS Lett. 260, 229-232] use a misinterpretation of the four-state controversy as a springboard to this paper. The authors give no data to characterize the proteins, making it impossible to compare the proteins with those from other laboratories. The analysis is flawed by the authors' failure to verify that the steady state rates obtained compare reasonably well with published rates. Although a four-state model may be a satisfactory approximation for certain limited purposes, it is not a sufficient basis for a complete analysis of the actomyosin system.     

The myth of “minima” and “maxima”, the species of Physalis in the Indian Subcontinent

The status of the names, Physalis minima L. and P. maxima Mill. (Solanaceae), and their alleged presence on the Indian subcontinent are discussed. The issues of nativity and identity of Linnaean Physalis minima are long-debated while the use of the name P. maxima Mill. and its report from India are recent. The available evidence indicates that the name \"P. minima L.\" is misapplied to two different elements, viz., P. angulata L. and P. lagascae Roem. & Schult. The name Physalis minima L. may be rejected as nomen confusum, for which the paper provides the primary information. As on today, it is submerged under the synonymy of P. angulata L. The correct name for the widely known P. minima is P. lagascae. The name \"P. maxima Mill.\" applied to the escape and naturalized weed in the Indian subcontinent and elsewhere is to be substituted by P. pruinosa L., a name misapplied to P. grisea (Waterf.) M. Martínez.     

The myth of “minima” and “maxima”, the species of Physalis in the Indian Subcontinent

The status of the names, Physalis minima L. and P. maxima Mill. (Solanaceae), and their alleged presence on the Indian subcontinent are discussed. The issues of nativity and identity of Linnaean Physalis minima are long-debated while the use of the name P. maxima Mill. and its report from India are recent. The available evidence indicates that the name “P. minima L.” is misapplied to two different elements, viz., P. angulata L. and P. lagascae Roem. & Schult. The name Physalis minima L. may be rejected as nomen confusum, for which the paper provides the primary information. As on today, it is submerged under the synonymy of P. angulata L. The correct name for the widely known P. minima is P. lagascae. The name “P. maxima Mill.” applied to the escape and naturalized weed in the Indian subcontinent and elsewhere is to be substituted by P. pruinosa L., a name misapplied to P. grisea (Waterf.) M. Martínez.     

Steric and Electronic Properties of the 3′-spiro Moiety of TSAO-T and Analogues

Abstract

The synthesis and study of geometrical and stereoelectronic properties of the spiro moiety of tof novel TSAO analogues modified at the 3′-spiro moiety is described.     

The “evolutionary argument” and the metaphilosophy of commonsense

Recently in these pages it has been argued that a relatively straightforward version of an old argument based on evolutionary biology and psychology can be employed to support the view that innate ideas are a naturalistic source of metaphysical knowledge. While sympathetic to the view that the “evolutionary argument” is pregnant with philosophical implications, I show in this paper how it needs to be developed and deployed in order to avoid serious philosophical difficulties and unnecessary complications. I sketch a revised version of the evolutionary argument, place it in a new context, and show that this version in this context is not vulnerable to the standard criticisms levelled against arguments of this general type. The philosophical import of this version of the argument lies not in any metaphysical conclusions it sanctions directly, but in the support it lends to the metaphilosophy of commonsense.     

The Origin and Dispersal of the “Lower” Hamamelidae

The “lower” Hamamelidae sensu Endress (1989a) comprises seven families: Trochodendraceae, Tetracentraceae, Cercidiphyllaceae, Myrothamnaceae,Eupteleaceae, Platanaceae and Hamamelidaceae. In the present paper, the systematic position, modern distribution pattern and fossil history of each family are analyzed, and the origin and dispersal of them are discussed according to the principle of the unity between the phylogeny and distribution of plants. The paper consists of three parts. The conclusions are as follows: 1. The center of distribution According to Takhtajan's (1986) regionalization of the world flora, there are13 distribution types in the “lower” Hamamelidae (Table 1 ). Eastern Asiatic Region, with five families, 19 genera and 73 species, ranks the first based on thenumbers of species, genera and families. Four families: Trochodendraceae,Tetracentraceae, Cercidiphyllaceae and Eupteleaceae which were considered as moreprimitive in the “lower” Hamamelidae and three genera: Disanthus,Exbucklandia and Rhodoleia, primitive in the Hamamelidaceae, are all found inEastern Asiatic Region. In addition, the groups at different evolutionary stages inthe “lower” Hamamelidae survive in this region. Indochinese Region, with twofamilies, 15 genera and 32 species, ranks the second. It was shown that southernEastern Asiatic region and northern Indochinese Region are the distribution centerof the “lower”Hamamelidae based on further analysis (see Table 2). 2. The place and time of the origin The fossil records of the “lower” Hamamelidae are abundant in angiosperms.Nordenskioldia, supposed as the extinct ancestral group of Trochodendraceae andTetracentraceae, was widely distributed during the latest Cretaceous and the earlyTertiary in the Northern Hemisphere; Trochodendroides appeared during theCretaceous in North America, former USSR and Japan; the ancestral group ofCercidiphyllaceae, the Joffrea-Nyssidum complex, also occurred during theCretaceous in the middle and higher latitude area of the Norhern Hemisphere. Inaddition, the earliest fossil records of the Eupteleaceae, Platanaceae andHamamelidaceae appeared in North America, Europe and Asia of the NorthernHemisphere respectively. Therefore, the Laurasian origin of the “lower”Hamamelidae is supported by fossil evidence. On the other hand, the fossil dataare still insufficient to determine the place of the origin, especially because the fossil records are rather poor in Asia. For this reason, the analyses of birthplaceshould combine with the information from the distribution of the primitive groupsor outgroup of the “lower” Hamamelidae. Based on the statistics of distribution types, there are four primitive families inthe “lower” Hamamelidae and three primitive genera in the Hamamelidaceae insouthern Eastern Asiatic Region and northern Indochinese Region. Platanuskerrii Gagnep. of the Platanaceae, distributed in northern Vietnam, is consideredas one of the most primitive species which has survived in modern times in thisfamily because of its pistillate inflorescence comprising 10-12 heads. TheMagnoliaceae was selected as an outgroup in our other paper “A phylogeneticanalysis of families in the Hamamelidae” (Lu et al. 1991 ). All its 13 genera andmost species occur from East to Southeast Asia, but in North America only threegenera are found. Takhtajan (1969) considered that it was plants of theMagnoliaceae that were dispersed from East Asia to North America. Because theprimitive groups of the “lower” Hamamelidae and its outgroup almost occur inthe same area, their ancestor also appeared most probably in this area accordingto the principle of common origin. It was inferred that the area from southernEastern Asiatic Region to northern Indochinese Region is the birthplace ofthe “lower\"” Hamamelidae. The differentiation of the “lower” Hamamelidae took place rather early inangiosperms. The origin of them may be traced at least back to the Barremian ofthe early Cretaceous according to pollen fossil records. From more unequivocal fossil evidence, Platanoid plants appeared during the late Albian of the earlyCretaceous, and the Trochodendraceae, Tetracentraceae, Cercidiphyllaceae andHamamelidaceae diverged from their ancestral groups respectively no later than thelate Cretaceous (Fig. 6). 3. The causes for the formation of the modern distribution pattern The “lower” Hamamelidae is a. rather old group. It is one of the mostabundant and widespread components of fossil floras in the Northern Hemisphereduring the late Cretaceous-middle Tertiary, the interval, when the global temperature was warm, although the extant Trochodendraceae, Tetracentraceae,Cercidiphyllaceae and Eupteleaceae which are now confined to East Asia aremonotypical or oligotypical families. This distribution pattern indicates that mostplants became extinct in Europe, northern Asia and North America because of theclimatic changes during the late Tertiary, and especially the Quaternary glaciation,but East Asia, usually called “plant refuge”during the glacial period, became thesurvival place of many plants. From the viewpoint of evolution, these four families might be “living fossil plants” preserved from the Tertiary. The distribution of Hamamelidaceae is disjunct, but the causes leading to thispattern are not the same in different genera. The disjunction among Europe,North America, Australia and southern Africa is due to the tectonic movements ofthe earth; , and that between southeastern Europe-northern West Asia andsoutheastern Asia is developed as a result of the Quaternary glaciation. Fothergilla found from Carolina to Alabama in the United States andHamamelis disjunct between East Asia and North America were widely distributedduring the Tertiary in the Northern Hemisphere (Hu & Chaney 1940). The formation of their distribution patterns is a synthetic process owing to the tectonicmovements and the Quaternary glaciation. Parrotia and Parrotiopsis, endemic to Iran and the WestHimalayas respectively, are very similar in morphology. They might have a common ancestor, and the latter is more primitive than the former. It seems that several groups in the Hamamelidaceae were dispersed from east to west in Eurasia. Of the five genera in the Southern Hemisphere, Dicoryphe and Trichocladusare Madagascarian and southern African, and Ostrearia, Neostrearia andNoahdendron occur in northeastern Australia. They are usually considered as rather isolated groups, but Hufford and Endress (1989) found that they are closely related. The African genera might be dispersed from Asia via India, Sri Lanka andLemuria continent; the Australian Hamamelidaceae also from Asia, but via the islands distributed in the Pacific Ocean. The Myrothamnaceae, comprising 2 species distributed in Madagascar andsouthern Africa, is closely related to the Hamamelidaceae. Based on morphologicalanalyses, an evolutionary series exists among Myrothamnus, Dicoryphe andTrichocladus in which the distribution patterns are the same, and Myrothamnusis more specialized than the two genera of the Hamamelidaceae. 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Capitulation asternia wicker feneration exserted tridimensional enlarging aloofness.     

The “averaging fallacy” and the levels of selection

This paper compares two well-known arguments in the units of selection literature, one due to , the other due to . Both arguments concern the legitimacy of averaging fitness values across contexts and making inferences about the level of selection on that basis. The first three sections of the paper shows that the two arguments are incompatible if taken at face value, their apparent similarity notwithstanding. If we accept Sober and Lewontin's criterion for when averaging genic fitnesses across diploid genotypes is illegitmate, we cannot accept Sober and Wilson's criterion for when averaging individual fitnesses across groups is illegitimate, and vice versa. The final section suggests a possible way of reconciling the two arguments, by invoking an ambiguity in the concept of genic selection.     

The “balance” argument and the evolution of sex

The “balance” argument suggests that if sex were maladaptive at the individual level, it would be quickly lost from species with asexual/sexual alternation. Williams has suggested an “Aphid-Rotifer” model for such species. It has the following characteristics (a) parthenogenesis is favoured when the environment is stable (b) when the environment changes qualitatively, sex generates offspring with an increased fitness variance compared to parthenogenetic progeny (c) if selection is intense and sib competition occurs then sex is favoured. It is argued here that condition (b) is not essential to the model. An increased fitness variance may be generated by the recombination of unfavourable mutations when one or more of the following occur; (1) founder effects (2) inbreeding (3) haplo-diploidy (4) intra-male competition. Parthenogenesis sustains an advantage when selection is relaxed and the possession of mutations is not reflected in differences in fitness. Sex is favoured when selection is intense and fitness reflects the possession of unfavourable mutations.     

Structure–activity relationships of the antimicrobial peptide gramicidin S and its analogs: Aqueous solubility,self-association,conformation, antimicrobial activity and interaction with model lipid membranes

GS10 [cyclo-(VKLdYPVKLdYP)] is a synthetic analog of the naturally occurring antimicrobial peptide gramicidin (GS) in which the two positively charged ornithine (Orn) residues are replaced by two positively charged lysine (Lys) residues and the two less polar aromatic phenylalanine (Phe) residues are replaced by the more polar tyrosine (Tyr) residues. In this study, we examine the effects of these seemingly conservative modifications to the parent GS molecule on the physical properties of the peptide, and on its interactions with lipid bilayer model and biological membranes, by a variety of biophysical techniques. We show that although GS10 retains the largely β-sheet conformation characteristic of GS, it is less structured in both water and membrane-mimetic solvents. GS10 is also more water soluble and less hydrophobic than GS, as predicted, and also exhibits a reduced tendency for self-association in aqueous solution. Surprisingly, GS10 associates more strongly with zwitterionic and anionic phospholipid bilayer model membranes than does GS, despite its greater water solubility, and the presence of anionic phospholipids and cholesterol (Chol) modestly reduces the association of both GS10 and GS to these model membranes. The strong partitioning of both peptides into lipid bilayers is driven by a large favorable entropy change opposed by a much smaller unfavorable enthalpy change. However, GS10 is also less potent than GS at inducing inverted cubic phases in phospholipid bilayer model membranes and at inhibiting the growth of the cell wall-less bacterium Acholeplasma laidlawii B. These results are discussed in terms of the comparative antibiotic and hemolytic activities of these peptides.     

The effect of isoniazid,carbutamide, propamidine and pentamidine on the activity and synthesis of β-galactosidase,and the synthesis of transaminases in Escherichia coli,strain 15, mutant M2

• 1.1. The amount of valine/glutamic acid and aspartic acid/glutamic acid transaminases in resting cells of Escherichia coli, 15, M₂, is not affected by growing the cultures in 10⁻³M isoniazid, 10⁻⁴M carbutamide, 5·10⁻⁵M pentamidine or 10⁻⁵M propamidine.
• 2.2. The amount of β-galactosidase formed in resting cells of E. coli, 15, M₂, is not affected when cultures are grown in 10⁻³M isoniazid, 10⁻⁴M carbutamide or 10⁻⁵M pentamidine. The amount of this enzyme formed in the logarithmic phase of growth is lower in carbutamide and pentamidine grown cells than in control cultures.
• 3.3. The β-galactosidase activity of cell-free extracts of E. coli, 15, M₂, is 75% and 99% inhibited by 3.3·10⁻³M propamidine and pentamidine respectively. The inhibition is competitive. Isoniazid and carbutamide at the same concentration are without effect on the activity of β-galactosidase.
     

The discovery of aniline and the origin of the term “aniline dye”

An historical background is provided for the term, “aniline dye,” which is still widely used as a synonym for “synthetic dye.” The discovery of aniline and the role of Hofmann in clarifying it are described. The subsequent discovery of mauveine (mauve) by a student of Hofmann's, William Perkin, and his difficulties in transforming an academic synthesis into a commercial product also are discussed. The key role of Scottish dyers, the Pullars of Perth and Thomas Keith in London, in this technology transfer is described. The subsequent ascendancy of the German dyestuff industry over British manufacturers is noted.     

The history of the homology concept and the “Phylogenetisches Symposium”

The homology concept has had a long and varied history, starting out as a geometrical term in ancient Greece. Here we describe briefly how a typological use of homology to designate organs and body parts in the same position anatomically in different organisms was changed by Darwin’s theory of evolution into a phylogenetic concept. We try to indicate the diversity of opinions on how to define and test for homology that has prevailed historically, before the important books by Hennig (1950. Grundzüge einer Theorie der Phylogenetischen Systematik. Deutscher Zentralverlag, Berlin) and Remane (1952. Die Grundlagen des Natürlichen Systems, der Vergleichenden Anatomie und der Phylogenetik. Geest & Portig, Leipzig) brought more rigor into both the debate on homology and into the usage of the term homology among systematists. Homology as a theme has recurred repeatedly throughout the history of the “Phylogenetisches Symposium” and we give a very brief overview of the different aspects of homology that have been discussed at specific symposia over the last 48 years. We also honour the fact that the 2004 symposium was held in Jena by pointing to the roles played by biologists active in Jena, such as Ernst Haeckel and Carl Gegenbaur, in starting the development towards a homology concept concordant with an evolutionary world view. As historians of biology, we emphasize the importance of major treatises on homology and its history that may be little read by systematists active today, and have sometimes also received less attention by historians of biology than they deserve. Prominent among these are the works of Dietrich Starck, who also happened to be both a student, and later a benefactor, of systematics at Jena University.     

Physical and functional interaction between the α- and γ-secretases: A new model of regulated intramembrane proteolysis

Many single-transmembrane proteins are sequentially cleaved by ectodomain-shedding α-secretases and the γ-secretase complex, a process called regulated intramembrane proteolysis (RIP). These cleavages are thought to be spatially and temporally separate. In contrast, we provide evidence for a hitherto unrecognized multiprotease complex containing both α- and γ-secretase. ADAM10 (A10), the principal neuronal α-secretase, interacted and cofractionated with γ-secretase endogenously in cells and mouse brain. A10 immunoprecipitation yielded γ-secretase proteolytic activity and vice versa. In agreement, superresolution microscopy showed that portions of A10 and γ-secretase colocalize. Moreover, multiple γ-secretase inhibitors significantly increased α-secretase processing (r = −0.86) and decreased β-secretase processing of β-amyloid precursor protein. Select members of the tetraspanin web were important both in the association between A10 and γ-secretase and the γ→α feedback mechanism. Portions of endogenous BACE1 coimmunoprecipitated with γ-secretase but not A10, suggesting that β- and α-secretases can form distinct complexes with γ-secretase. Thus, cells possess large multiprotease complexes capable of sequentially and efficiently processing transmembrane substrates through a spatially coordinated RIP mechanism.