Cultural Factors in Crime Among the Dakota Indians

Abstract

In spite of the breakdown of traditional Dakota social systems, especially the kinship structuring related to criminality, the modern pattern and rate of Dakota crime appears to reflect old norms of behavior. The comparatively low crime rate against property and the high rate against per sons is particularly suggestive of the traditional pattern operating in a modern context.     

Identification of protein stability determinants in chloroplasts

Although chloroplast protein stability has long been recognised as a major level of post‐translational regulation in photosynthesis and gene expression, the factors determining protein stability in plastids are largely unknown. Here, we have identified stability determinants in vivo by producing plants with transgenic chloroplasts that express a reporter protein whose N‐ and C‐termini were systematically modified. We found that major stability determinants are located in the N‐terminus. Moreover, testing of all 20 amino acids in the position after the initiator methionine revealed strong differences in protein stability and indicated an important role of the penultimate N‐terminal amino acid residue in determining the protein half life. We propose that the stability of plastid proteins is largely determined by three factors: (i) the action of methionine aminopeptidase (the enzyme that removes the initiator methionine and exposes the penultimate N‐terminal amino acid residue), (ii) an N‐end rule‐like protein degradation pathway, and (iii) additional sequence determinants in the N‐terminal region.     

Multiple determinants of eukaryotic mRNA stability

Regulated changes in mRNA stability play an important role in modulating the level of expression of many eukaryotic genes. In several systems, specific sequence determinants that dictate mRNA instability have been identified. Thus, the presence of instability determinants, and not the absence of sequences that dictate stability, appears to be required for regulated mRNA degradation. These instability determinants presumably interact with specific nucleases or other trans-acting factors that regulate the accessibility of the domain to nucleases. Although each RNA destabilization pathway has unique features, in many cases RNA degradation requires ongoing protein synthesis. In some of the systems discussed, the mRNAs are degraded co-translationally, perhaps by a ribosome-associated ribonuclease. For other messages, the mechanistic reasons for the dependence of mRNA degradation on ongoing protein synthesis are still unknown.     

Structural determinants in the stability of the serpin/proteinase complex

Serpins inhibit serine proteinases through formation of stable 1:1 complexes. In this study we have evaluated the effects of PAI-1 neutralizing antibodies (MA) on the stability of PAI-1/proteinase complexes, partially destabilized through prolongation of the reactive center loop. MA-8H9D4, reacting with residues Arg(300), Gln(303), and Asp(305), had no effect on the stability. In contrast, MA-33H1F7 and MA-55F4C12, reacting with alpha-helix F and the turn connecting hF with s3A, affected significantly and proteinase-dependently formed PAI-1/proteinase complexes. That is, MA-33H1F7 increased the stability of both PAI-1/t-PA and u-PA complexes (7- and 3-fold, respectively) whereas MA-55F4C12 stabilized PAI-1/t-PA complexes (3-fold) but destabilized PAI-1/u-PA complexes (2-fold). It is concluded that interference with the docking site of the cognate proteinase in the preformed serpin/proteinase complex may affect the intrinsic stability. We hypothesize that this is the consequence of a decreased or increased torsion of the RCL on the catalytic triad in the proteinase.     

On the determinants of population structure in antigenically diverse pathogens

Many pathogens exhibit antigenic diversity and elicit strain-specific immune responses. This potential for cross-immunity structure in the host resource motivates the development of mathematical models, stressing competition for susceptible hosts in driving pathogen population dynamics and genetics. Here we establish that certain model formulations exhibit characteristics of prototype pattern-forming systems, with pathogen population structure emerging as three possible patterns: (i) incidence is steady and homogeneous; (ii) incidence is steady but heterogeneous; and (iii) incidence shows oscillatory dynamics, with travelling waves in strain-space. Results are robust to strain number, but sensitive to the mechanism of cumulative immunity.     

HLA polymorphism in the Havasupai: evidence for balancing selection.

The characterization and analysis of genetic variation at the HLA loci provides important insight for population geneticists trying to understand the evolutionary forces that have shaped human populations. This study describes the HLA-A and HLA-B loci serotyping and statistical analysis on an isolated Native American population, the Havasupai of Arizona. Four alleles at the HLA-A locus were identified, while eight alleles were found at the HLA-B locus. These variants were present as 20 of 32 potential two-locus haplotypes, with five of the six most common haplotypes exhibiting high positive linkage disequilibrium. Significant homozygote deficiency (heterozygosity excess) was detected both at HLA-A and at HLA-B. This deviation from Hardy-Weinberg proportions was not attributable to nonselective causes such as different allele frequencies in males and females or avoidance of consanguineous matings. In addition, the distribution of alleles at both HLA-A and HLA-B was more even than expected from neutrality theory; that is, the observed Hardy-Weinberg homozygosity was only 62.4% of that expected under neutrality. These observations suggest that balancing selection is of major importance in maintaining genetic variation at HLA-A and HLA-B.     

Admixture and population replacement of the sells Papago Indians: Three strategies

Abstract

Changes in rates of admixture on the Sells Papago Indian reservation over the last century are shown to reflect ethnohistorically recorded events of extra‐tribal contact. Three distinct strategies providing, in varying degrees, for the preservation of group identity were identified. It is argued that strategies favoring maximum preservation of ethnic identity have threatened the survival of the reservation breeding units because traditional patterns of mate selection are inconsistent with present settlement patterns and result in delay of mate selection and childbearing early in reproductive life.     

Global stability of population models

Local stability seems to imply global stability for population models. To investigate this claim, we formally define apopulation model. This definition seems to include the one-dimensional discrete models now in use. We derive a necessary and sufficient condition for the global stability of our defined class of models. We derive an easily testable sufficient condition for local stability to imply global stability. We also show that if a discrete model is majorized by one of these stable population models, then the discrete model is globally stable. We demonstrate the utility of these theorems by using them to prove that the regions of local and global stability coincide for six models from the literature. We close by arguing that these theorems give a method for demonstrating global stability that is simpler and easier to apply than the usual method of Liapunov functions.     

Intrinsic determinants of a population trend in timing of breeding in the wandering albatross

Numerous studies of wild animal species have documented that population level responses to environmental change are underpinned by individual level phenotypic plasticity. However, where the relationship between an individual trait and a climate variable occurs when both show a trend over time, phenotypic plasticity may be confounded by ageing. We investigated between and within individual change in laying date in the wandering albatross Diomedea exulans, a long‐lived species experiencing a dramatic decline in population size. Laying date has advanced over the last three decades. A mean‐centering analysis demonstrated that this pattern was driven by within‐individual changes as opposed to appearance or disappearance of phenotypes. Furthermore, a lack of between individual effect suggested the change resulted from ageing as opposed to phenotypic plasticity. Females varied significantly in rate of advance, such that those with low past reproductive rates exhibited a negative temporal trend in laying date, whereas birds with moderate to high past reproductive performance showed little change. The population trend was therefore driven by a subset with low past breeding success. An analysis of effects of timing of breeding on breeding success revealed stabilizing selection for relative laying date. Furthermore, current breeding success was positively related to past success rate, which suggests that there may be indirect selection against plasticity in this population. Our results show that population trends can arise from individual level change unrelated to prevailing environmental conditions, thus demonstrating the importance of longitudinal analyses in the interpretation of climate change effects.     

Structural determinants of cold adaptation and stability in a large protein

The heat-labile alpha-amylase from an antarctic bacterium is the largest known protein that unfolds reversibly according to a two-state transition as shown by differential scanning calorimetry. Mutants of this enzyme were produced, carrying additional weak interactions found in thermostable alpha-amylases. It is shown that single amino acid side chain substitutions can significantly modify the melting point T(m), the calorimetric enthalpy Delta H(cal), the cooperativity and reversibility of unfolding, the thermal inactivation rate constant, and the kinetic parameters k(cat) and K(m). The correlation between thermal inactivation and unfolding reversibility displayed by the mutants also shows that stabilizing interactions increase the frequency of side reactions during refolding, leading to intramolecular mismatches or aggregations typical of large proteins. Although all mutations were located far from the active site, their overall trend is to decrease both k(cat) and K(m) by rigidifying the molecule and to protect mutants against thermal inactivation. The effects of these mutations indicate that the cold-adapted alpha-amylase has lost a large number of weak interactions during evolution to reach the required conformational plasticity for catalysis at low temperatures, thereby producing an enzyme close to the lowest stability allowing maintenance of the native conformation.     

Pathogenicity determinants in the complex virus population of a Plum pox virus isolate

Several subisolates were separated from a single Plum pox virus (PPV) isolate, PPV-PS. In spite of an extremely high sequence conservation (more than 99.9% similarity), different subisolates differed largely in pathogenicity in herbaceous hosts and infectivity in woody plants. The severity of symptomatology did not seem to correlate with virus accumulation. Sequence analysis and site-directed mutagenesis demonstrated that single amino acid changes in the helper component (HC) protein caused a drastic effect on virus symptoms in herbaceous hosts and notably modified virus infectivity in peach seedlings. These results indicate that HC variation might play an important role in virulence evolution of natural plant virus infections. Moreover, the analysis of Potato virus X (PVX)-HC chimeras showed that the identified HC amino acid changes had parallel effects on the severity of symptoms caused by PPV and on HC-induced enhancement of PVX pathogenicity, indicating that HC functions in potyvirus symptomatology and in synergism with other viruses have overlapping determinants.     

Complexity and demographic stability in population models

This article is concerned with relating the stability of a population, as defined by the rate of decay of fluctuations induced by demographic stochasticity, with its heterogeneity in age-specific birth and death rates. We invoke the theory of large deviations to establish a fluctuation theorem: The demographic stability of a population is positively correlated with evolutionary entropy, a measure of the variability in the age of reproducing individuals in the population. This theorem is exploited to predict certain correlations between ecological constraints and evolutionary trends in demographic stability, namely, (i) bounded growth constraints--a uni-directional increase in stability, (ii) unbounded growth constraints (large population size)--a uni-directional decrease in stability, (iii) unbounded growth constraints (small population size)--random, non-directional change in stability. These principles relating ecological constraints with trends in demographic stability are shown to be far reaching generalizations of the tenets derived from classical studies of stability in an evolutionary context. These results thus provide a new conceptual framework for explaining patterns of variation in population numbers observed in natural populations.     

Non-omnivorous generality promotes population stability

Using a combination of stable isotope analysis of delta13C and delta15N and long-term census data on population abundances for meiofauna in tropical aquatic rock pools, we provide evidence that species which exhibit greater variation in delta13C, an indication of a greater range of distinct carbon sources in their diet, have more stable populations than species with lower variation in delta13C. This link between increased isotope variability and reduced population variability, however, did not hold for delta15N. This suggests that increases in population stability were due to non-omnivorous feeding on multiple carbon sources within a trophic level rather than omnivorous feeding on multiple carbon sources across trophic levels. Our findings corroborate MacArthur's original hypothesis that populations that can access a greater range of resources are more stable than those which consume a more restricted range of resources.     

Global asymptotic stability in Volterra's population systems

Sufficient conditions which can be verified easily are obtained for the global asymptotic stability of the positive steady state in Volterra's population system incorporating hereditary effects.