The Tribe as a Unit of Subsistence: Nomadic Pastoralism in the Middle East

Among Middle Eastern pastoral nomads some "tribes" can best be described as "units of subsistence": they exploit an area providing multiannual subsistence. Tribesmen sometimes control this area; more usually they control part of it and share the rest with other nomads and with settled people. Small corporate groups afford the tribesman security and, through genealogical links, mediate his formal membership of the tribe. The unit of subsistence is articulated mainly by networks of institutionalized relationships. Corporate groups join forces only for defense, and then their alliances cut across tribal lines. Under external pressure the unit of subsistence may develop formal leadership and a small standing militia. This administrative setup is in the literature often associated with the corporate groups and called "tribe." While coexisting with a unit of subsistence, this "tribe" is not necessarily identical with it in area or population . [ecology, genealogies, Middle East, pastoral nomads, tribe]     

Species concepts and the determination of historic gene flow patterns in the Eulemur fulvus (Brown Lemur) complex

Eulmur fulvus , a complex comprising six subspecies, is a classic example of species status conferred through evolutionary taxonomy. We used the phylogcnctic species concept as an alternative method to the biological species concept for determining historic patterns of gene flow between the various E. julvus subspecies and for conferring species status. In this paper, we used population aggregation analysis to determine the proper species partitions and cladistic analysis to reconstruct the evolutionary relationships of the different populations in the Eulemur fulvus complex. We sequenced three mtDNA gene regions (d-loop, 12S, and cyt-b) and one nuclear region, casein kinase, for a total of 1247 bases. Through population aggregation analysis, we determined that the E. fulvus complex should be split into three units; one unit supported by six diagnostic sites comprising E.f. albocollans , one unit supported by three diagnostic sites comprising E.f. collaris , and one unit supported by two diagnostic sites comprising the four other subspecies. Although all six subspecies in the E. julvus complex share a common ancestor, we found in our cladistic analysis that E. J. collaris and E. j. albocollans share a common ancestor that more recently split off from the common ancestor of the four other E. fulvus subspecies.     

Use of variable simple sequence motifs as genetic markers: application to study of myotonic dystrophy

Summary Among the many classes of repetitive elements present in the human genome, the ubiquitous simple sequence motifs (SSMs) composed of [A]n, [TG]n, [AG]n or codon-tandem repeats form a major source of genetic variation. Here we report a detailed molecular-genetic study of a variable simple sequence motif (VSSM) in the apolipoprotein C2 (apoC2) gene, which maps to the 19q13.2 region in the vicinity of the myotonic dystrophy (DM) locus. By combining in vitro DNA-amplification using the polymerase chain reaction and high-resolution gel electrophoresis, we could demonstrate a high degree of allelic variation with at least ten alleles, which differ in the number of repeated [TG] or [AG] dinucleotide units. Similar results were found for the somatostatin I gene locus. To evaluate the usefulness of SSM-length polymorphisms as genetic markers, the apoC2-VSSM was employed for linkage analysis in DM families. Our results establish that the orientation of the apolipoprotein gene cluster on 19q is cenapoE-apoC2-ter and indicate that the many thousands of structurally similar VSSMs in the human genome represent a rich source of highly informative genetic and diagnostic markers.     

Multi-algebra duplication

This paper was inspired by [5]. First, we define a new kind of duplication which differs from the usual one in that we have different multiplication tables for male and female gametes. [5] deals with the special case where the tables correspond to different recombination rates for males and females for two linked loci. Furthermore, we use the factoring and multilinear technique discussed in [2] and [3] to simplify the proofs in [5].     

A diversity of beta diversities: straightening up a concept gone awry. Part 2. Quantifying beta diversity and related phenomena

The present two-part review aims to put the different phenomena that have been called "beta diversity" over the years into a common conceptual framework and to explain what each of them measures. The first part (Tuomisto 2010) discussed basic definitions of "beta diversity". Each arises from a different way of combining a definition of "diversity" with a definition of its alpha component and with a mathematical relationship between the alpha and gamma components. This second part assumes that an appropriate basic definition of a beta component (which may or may not be true beta diversity) has been chosen, and the focus here will be on how to quantify it for a given dataset. About twenty different approaches have been used for this purpose. It turns out that only two of these approaches accurately quantify the selected beta component: one does so for the entire dataset, and the other for two sampling units at a time. The other approaches actually quantify other phenomena, such as mean species turnover between sampling units, compositional gradient length (with or without reference to an external gradient), distinctness of a focal sampling unit, rate of species accumulation with increasing sampling effort, rate of compositional turnover along an external gradient, or the rate of decay in compositional similarity with increasing geographical distance. Although most of these phenomena can be expressed as a function of a beta component of diversity, they do not equal a beta component of diversity. Many of these derived variables are not even numerically correlated with the beta component on which they are based, which needs to be taken into account when interpreting the results. The effects of sampling decisions when results are extrapolated beyond the available data will also be discussed.     

Signalling by protein kinase C isoforms in the heart

Understanding transmembrane signalling process is one of the major challenge of the decade. In most tissues, since Fisher and Krebs's discovery in the 1950's, protein phosphorylation has been widely recognized as a key event of this cellular function. Indeed, binding of hormones or neurotransmitters to specific membrane receptors leads to the generation of cytosoluble second messengers which in turn activate a specific protein kinase. Numerous protein kinases have been so far identified and roughly classified into two groups, namely serine/threonine and tyrosine kinases on the basis of the target amino acid although some more recently discovered kinases like MEK (or MAP kinase kinase) phosphorylate both serine and tyrosine residues.Protein kinase C is a serine/threonine kinase that was first described by Takai et al. [1] as a Ca- and phospholipid-dependent protein kinase. Later on, Kuo et al. [2] found that PKC was expressed in most tissues including the heart. The field of investigation became more complicated when it was found that the kinase is not a single molecular entity and that several isoforms exist. At present, 12 PKC isoforms and other PKC-related kinases [3] were identified in mammalian tissues. These are classified into three groups. (1) the Ca-activated -, -,and -PKCs which display a Ca-binding site (C2); (2) the Ca-insensitive -, -, -, -, and -PKCs. The kinases that belong to both of these groups display two cystein-rich domains (C1) which bind phorbol esters (for recent review on PKC structure, see [4]). (3) The third group was named atypical PKCs and include , , and -PKCs that lack both the C2 and one cystein-rich domain. Consequently, these isoforms are Ca-insensitive and cannot be activated by phorbol esters [5]. In the heart. evidence that multiple PKC isoforms exist was first provided by Kosaka et al. [6] who identified by chromatography at least two PKC-related isoenzymes. Numerous studies were thus devoted to the biochemical characterization of these isoenzymes (see [7] for review on cardiac PKCs) as well as to the identification of their substrates.This overview aims at updating the present knowledge on the expression, activation and functions of PKC isoforms in cardiac cells. (Mol Cell Biochem 157: 65–72, 1996)     

Evolutionary implications for interactions between multiple strains of host and parasite

The interaction between multiple parasite strains within different host types may influence the evolutionary trajectories of parasites. In this article, we formulate a deterministic model with two strains of parasites and two host types in order to investigate how heterogeneities in parasite virulence and host life-history may affect the persistence and spread of diseases in natural systems. We compute the reproductive number of strain i (R(i)) independently, as well as the (conditional) "invasion" reproductive number for strains i (R(i)(j), j not equal i) when strain j is at a positive equilibrium. We show that the disease-free equilibrium is locally asymptotically stable if R(i)<1 for both strains and is unstable if R(i)>1 for one stain. We establish the criterion R(i)(j)>1 for strain i to invade strain j. Subthreshold coexistence driven by coinfection is possible even when R(i) of one strain is below 1. We identify conditions that determine the evolution of parasite specialism or generalism based on the life-history strategies employed by hosts, and investigate how host strains may influence parasite persistence.     

Alternative formulations of multilevel selection

Hierarchical expansions of the theory of natural selection exist in two distinct bodies of thought in evolutionary biology, the group selection and the species selection traditions. Both traditions share the point of view that the principles of natural selection apply at levels of biological organization above the level of the individual organism. This leads them both to considermultilevel selection situations, where selection is occurring simultaneously at more than one level. Impeding unification of the theoretical approaches of the multilevel selection traditions are the different goals of investigators in the different subdisciplines and the different types of data potentially available for analysis. We identify two alternative approaches to multilevel situations, which we termmultilevel selection [1] andmultilevel selection [2]. Of interest in the former case are the effects of group membership onindividual fitnesses, and in the latter the tendencies for the groups themselves to go extinct or to found new groups (i.e., group fitnesses). We argue that: neither represents the entire multilevel selection process; both are aspects of any multilevel selection situation; and both are legitimate approaches, suitable for answering different questions. Using this formalism, we show that: multilevel selection [2] does not require emergent group properties in order to provide an explanatory mechanism of evolutionary change; multilevel selection [1] is usually more appropriate for neontological group selection studies; and species selection is most fruitfully considered from the point of view of multilevel selection [2]. Finally we argue that the effect hypothesis of macroevolution, requiring, in selection among species, both the absence of group effects on organismic fitness (multilevel selection [1]), and the direct determination of species fitnesses by those of organisms, is untestable with paleontological data. Furthermore, the conditions for the effect hypothesis to hold are extremely restrictive and unlikely to apply to the vast majority of situations encountered in nature.     

Further studies on the biosynthesis of the avermectins

Summary The biosynthesis of avermectins was studied further inStreptomyces avermitilis MA5502 by feeding experiments with labeled precursors.¹³C-NMR analysis of the compounds biosynthesized from [2-¹³C]acetate, [1,2-¹³C₂]acetate, [3-¹³C]propionate and [2,3-¹³C₂]propionate confirmed that the aglycone of avermectins is made from seven intact acetate and five propionate units. Feeding experiments with [1-¹³C]2-methylbutyrate and [1-¹³C]isobutyrate have shown that 2-methylbutyrate and isobutyrate are immediate precursors of the starter units of the polyketide chains of avermectin a and b components, respectively. The³H/¹⁴C doublelabeling experiments suggest that the two oleandrose moieties are derived from glucose.     

Movement between patches, unequal competitors and the ideal free distribution

Researchers have often commented on the ability of the original ideal free distribution (IFD) model to approximate observed animal distributions even though the critical assumption that competitors are of equal ability is usually violated. We provide an explanation by recognizing that animals will occasionally move between patches for reasons other than to simply maximize their resource payoffs, given perfect (i.e. ideal) information about the current payoff in each patch, and that these movements will continue to occur even after an equilibrium is reached. When such movements are incorporated into an unequal competitors IFD model, a single, stable distribution of each competitor type is predicted. This equilibrium will usually be characterized by under-matching of total competitive units relative to the distribution of resources (i.e. too few competitive units in the good patch). More importantly, it will often resemble the original, equal competitors IFD, in that total competitor numbers will come close to matching the distribution of resources. We argue that researchers claiming to have observed an IFD of equal competitors have actually observed this equilibrium distribution of unequal competitors. Our model predicts that the deviation from input-matching will usually be an under-matching of total competitor numbers relative to resources (i.e. too few competitors in the good patch). Examination of published data reveals that post-equilibrium movement between patches occurs frequently and, although the reported distributions are similar to those predicted by input-matching, under-matching is usually observed.     

Chemical modification of aryl-1,2,3,6-tetrahydropyridinopyrimidine derivative to discover corticotropin-releasing factor(1) receptor antagonists: aryl-1,2,3,6-tetrahydropyridino-purine, -3H-1,2,3-triazolo[4,5-d)pyrimidine, -purin-8-one, and -7H-pyrrolo[2,3-d]pyrimidine derivatives

Structure-affinity relationships (SARs) of non-peptide CRF(1) antagonists suggest that such antagonists can be constructed of three units: a hydrophobic unit (Up-Area), a proton accepting unit (Central-Area), and an aromatic unit (Down-Area). Recently, various non-peptide corticotropin-releasing factor(1) (CRF(1)) receptor antagonists obtained by modification of the Central-Area have been reported. In contrast, we modified the Up-Area and presented 4- or 5-aryl-1,2,3,6-tetrahydropyridinopyrimidine derivatives including potent CRF receptor ligands 1a-c, and proposed that the 4- or 5-aryl-1,2,3,6-tetrahydropyridino moiety might be useful as a substituent in the Up-Area. Our interest shifted to the chemical modification in which the pyrimidine ring of 1a-c was replaced by other heterocycles, purine ring of 2, 3H-1,2,3-triazolo[4,5-d]pyrimidine ring of 3, purin-8-one ring of 4 and 7H-pyrrolo[2,3-d]pyrimidine ring of 5. Among them, 5-aryl-1,2,3,6-tetrahydropyridinopurine compound 6j (CRA0186) had the highest affinity for CRF(1) receptors (IC(50)=20nM). We report here the synthesis and SARs of derivatives 6-9.     

Inter-allelic prion propagation reveals conformational relationships among a multitude of [PSI] strains

Immense diversity of prion strains is observed, but its underlying mechanism is less clear. Three [PSI] prion strains--named VH, VK, and VL--were previously isolated in the wild-type yeast genetic background. Here we report the generation and characterization of eight new [PSI] isolates, obtained by propagating the wild-type strains with Sup35 proteins containing single amino-acid alterations. The VH strain splits into two distinct strains when propagated in each of the three genetic backgrounds, harboring respectively single mutations of N21L, R28P, and Gi47 (i.e. insertion of a glycine residue at position 47) on the Sup35 N-terminal prion-forming segment. The six new strains exhibit complex inter-conversion patterns, and one of them continuously mutates into another. However, when they are introduced back into the wild-type background, all 6 strains revert to the VH strain. We obtain two more [PSI] isolates by propagating VK and VL with the Gi47 and N21L backgrounds, respectively. The two isolates do not transmit to other mutant backgrounds but revert to their parental strains in the wild-type background. Our data indicate that a large number of [PSI] strains can be built on three basic Sup35 amyloid structures. It is proposed that the three basic structures differ by chain folding topologies, and sub-strains with the same topology differ in distinct ways by local structural adjustments. This "large number of variations on a small number of basic themes" may also be operative in generating strain diversities in other prion elements. It thus suggests a possible general scheme to classify a multitude of prion strains.     

Thermodynamics of RNA-RNA binding

BACKGROUND: Reliable prediction of RNA-RNA binding energies is crucial, e.g. for the understanding on RNAi, microRNA-mRNA binding and antisense interactions. The thermodynamics of such RNA-RNA interactions can be understood as the sum of two energy contributions: (1) the energy necessary to 'open' the binding site and (2) the energy gained from hybridization. METHODS: We present an extension of the standard partition function approach to RNA secondary structures that computes the probabilities Pu[i, j] that a sequence interval [i, j] is unpaired. RESULTS: Comparison with experimental data shows that Pu[i, j] can be applied as a significant determinant of local target site accessibility for RNA interference (RNAi). Furthermore, these quantities can be used to rigorously determine binding free energies of short oligomers to large mRNA targets. The resource consumption is comparable with a single partition function computation for the large target molecule. We can show that RNAi efficiency correlates well with the binding energies of siRNAs to their respective mRNA target. AVAILABILITY: RNAup will be distributed as part of the Vienna RNA Package, www.tbi.univie.ac.at/~ivo/RNA/     

基于CVM的海涂湿地生态服务价值的模糊评估模型

正确评估海涂湿地生态服务价值有助于加强人们保护海涂湿地的意识,为海涂湿地围垦生态补偿标准的制定提供依据。视价格"便宜"、"适中"和"昂贵"为模糊集,基于CVM法区间型数据建立了传统模糊统计模型、赋权模糊统计模型和三相划分模型,并以此评价了杭州湾国家湿地公园单位面积年生态系统服务价值。结果显示:3种方法得到的单价分别为10.28、10.38、9.76元m~(-2)a~(-1),三者一致程度较高,与国内沿海湿地价值比较接近。分析了"生态价值"概念客观上的"模糊性"引致模糊数学模型的合理性;采用"橄榄球"式赋权建立赋权模糊统计模型以克服传统模糊统计模型中对区间数据均匀赋权的不合理性,结果在隶属度函数的光滑性和拟合度上好于后者;第三,三相划分模型拟合出3个模糊集的隶属度函数,可以比较相同价格在不同模糊集中隶属度差异。建立的模型对于基于CVM法的生态资源价值评估具有借鉴意义。     

"Galton's Asset" and "Flower's Problem Cultural Networks and Cultural Units in Cross-Cultural Research Ml (Or, Male Genital Mutilations and Polygyny in Cross-Cultural Perspective)

Edward Tylor had envisioned anthropology to be comprised of ethnology and ethnography in equal parts, but today ethnography dominates the field. In this paper, we examine two reasons for the refugee status of ethnology. First, we look at the notorious "Galton effect." Second, we examine the problem of defining and using cultural units, particularly when positivistic and static theories and methods of culture have been largely discredited by anthropology. We argue against any formulaic solutions to these problems and show that for each research question one needs to reconsider the criteria for how to construct cultural units and how to ensure that the cultures under study are not merely replicas of one another. We show that previous solutions to these issues are limited because they fail to appreciate the contingent and multidimensional nature of culture. We also argue that, instead of a "Galton problem," there is actually a "Galton asset," which can be used to study historical and emergent communicative networks. [Keywords: cross–cultural research, Galton problem, cultural units, methods and theory]     

Inhibitors of Na+/H+ exchange block stimulus-provoked arachidonic acid release in human platelets. Selective effects on platelet activation by epinephrine, ADP, and lower concentrations of thrombin

We have observed previously that removal of extraplatelet Na+ blocks platelet secretion of dense granule contents in response to epinephrine, ADP, and 0.004 unit/ml thrombin, all agents which must mobilize arachidonic acid for its subsequent conversion to cyclooxygenase products in order to elicit platelet secretion. The present studies demonstrate that removal of extraplatelet Na+ blocks arachidonic acid mobilization in response to epinephrine, ADP, and 0.004 unit/ml thrombin without altering arachidonic acid conversion to thromboxane A2. The data also provide several lines of evidence which suggest that the blockade of arachidonic acid release due to removal of extraplatelet Na+ is a manifestation of blockade of Na+/H+ exchange system. 1) There is a concentration-dependent effect of extraplatelet Na+ (EC50 congruent to 55 mM) on [3H]arachidonic acid release such that mobilization is observed when [Na+]o greater than [Na+]i. 2) Increasing extraplatelet [H+] (i.e. decreasing extraplatelet pH from pH 7.35 to 6.8) causes a concentration-dependent decline in stimulus-provoked [3H]arachidonic acid release. 3) Ethylisopropylamiloride and other potent 5-amino analogs of amiloride block [3H]arachidonic acid release with a potency that parallels their effects on Na+/H+ exchange in other cellular systems. None of the above manipulations alter primary aggregation induced by epinephrine, ADP, or 0.004 unit/ml thrombin, indicating that stimulus-receptor binding, subsequent exposure of fibrinogen receptors, and fibrinogen-mediated platelet-platelet cross-linking are not significantly inhibited by [3H]arachidonic acid release in response to greater than 0.1 unit/ml thrombin, a stimulus that can elicit platelet secretion in the absence of products of the cyclooxygenase pathway. Therefore, Na+/H+ exchange may selectively modulate arachidonic acid mobilization in response to the so-called "weak agonists," agonists that require this mobilization to effect vigorous platelet aggregation and dense granule secretion.     

Preparation of a stable fresh frozen primary lipoprotein[a] (Lp[a]) standard

LP[a] is one of the most atherogenic lipoproteins consisting of an LDL-like core particle and a covalently linked glycoprotein of variable size. Due to its structural features, its heterogeneity and instability, there are great difficulties in standardizing quantitative immunochemical Lp[a] assays. One particular problem is the preparation of a pure primary standard, which is sufficiently stable to be used for value assignment of secondary reference material. Here we describe a method to purify Lp[a] to virtual homogeneity. When mixed with glycerol at a ratio of 1:1, the preparation is stable in the deep frozen state for more than 12 months. This latter material gave dose;-response curves in several immunochemical assays that were parallel to fresh or frozen sera, freshly prepared Lp[a], and other proposed reference materials. After determination of the protein content by amino acid analysis, it was possible to assign concentrations in molar and mass units to these preparations considering the theoretical molecular weights of the particular apo[a] isoform. Thus we propose to use this procedure for preparation of a "gold standard" for Lp[a] assays.     

Rates of decay for the survival probability of a mutant gene II The multitype case

This paper extends the results of [1] to the multitype case. For a multitype branching process that is slightly supercritical, approximations for the survival probability in terms of the maximal eigenvalue of the mean matrix and a generalized variance ² are developed. Our results improve upon those of Hoppe [5] and Eshel [3] that seek to validate a conjecture of Ewens [4].Research supported in part by NSF grant DMS 9007182     

The role of catecholamines on intercellular coupling,myocardial cell synchronization and self ventricular defibrillation

Ventricular fibrillation (VF) is one of the most life threatening events. Although in humans VF is generally sustained (SVF) requiring artificial defibrillation, in various mammals and in some cases in humans VF terminates by itself, reverting spontaneously into sinus rhythm. Since VF is one of the main causes of sudden death, one of the important clinical problems today is if and how we can transform the fatal SVF into a self limited transient one (TVF).From electrophysiological studies carried out on anaesthetized open chest animals, we have found that TVF requires a high degree of intercellular coupling and synchronization.Cardiac myocytes are electrically coupled with adjacent cells. The intercellular coupling is a focus of low electrical resistance which allows rapid transmission of electrical impulses between cells. Any decrease in intercellular coupling decreases the ability of the heart for self defibrillation. The cell-to-cell coupling decreases with age, ischemia, VF and variations in physiological conditions probably due to an increase in intercellular resistance (Ri), widening in the internexal gaps, decrease in electrotonic space constant () etc. All of these factors are known to be affected by intracellular concentration of free Ca⁺⁺ ([Ca⁺⁺]).On the basis of studies carried out on various mammals at different ages, we hypothesized that the ability of the heart to defibrillate depends on the cardiac catecholamine level [CA], during VF. This hypothesis is supported by the facts, known from the literature, that increase in [CA] decreases intracellular free Ca⁺⁺ concentration, decreases Ri and increases . By these effects, increase in [CA] enhances intercellular coupling and intercellular synchronization, and thereby, according to our hypothesis, leads to spontaneous ventricular defibrillation — TVF.During VF the sympathetic activity is enhanced but in some cases the [CA] does not reach the level needed for TVF. In order to help the heart in its effort to elevate the [CA] during VF, we proposed to treat these cases with drugs which inhibit the reuptake of [CA]. The facts that administration of [CA] reuptake inhibitors, before the induction of VF, and/or intracoronary infusion of adrenaline, during VF, transforms SVF into TVF, emphasized the validity of our hypothesis.