Genetic variation among Trypanosoma cruzi populations

Four experiments examined the effect of naloxone pretreatment on the expression and extinction of ethanol-induced conditioned place preference (experiments 1, 2, 4) or conditioned place aversion (experiments 1, 3). DBA/2 J mice received four pairings of a distinctive tactile (floor) stimulus (CS) with injection of ethanol (2 g/kg) given either immediately before or after 5-min exposure to the CS. A different stimulus was paired with injection of saline. Pre-CS injection of ethanol produced conditioned place preference, whereas post-CS injection of ethanol produced conditioned place aversion. Both behaviors extinguished partially during repeated choice testing after vehicle injection. Naloxone (10 mg/kg) had little effect on the initial expression of conditioned place preference, but facilitated its extinction. Moreover, repeated naloxone testing resulted in the expression of a weak conditioned place aversion to the CS that initially elicited a place preference. In contrast, naloxone (1.5 or 10 mg/kg) enhanced expression of conditioned place aversion, thereby increasing its resistance to extinction. A control experiment (experiment 4) indicated that repeated testing with a different aversive drug, lithium chloride, did not affect rate of extinction or produce an aversion to the CS previously paired with ethanol. These findings do not support the suggestion that naloxone facilitates the general processes that underlie extinction of associative learning. Also, these data are not readily explained by the conditioning of place aversion at the time of testing. Rather, naloxone's effects appear to reflect a selective influence on maintenance of ethanol's conditioned rewarding effect, an effect that may be mediated by release of endogenous opioids. Overall, these findings encourage further consideration of the use of opiate antagonists in the treatment of alcoholism.     

Dermatoglyphic relationships among South Amerindian populations

The biological affinities among 17 South American aboriginal populations are examined by means of a multivariate analysis of their dermatoglyphic finger patterns. Different analytical methods [cluster analysis, nonmetric multidimensional scaling, and multiresponse permutation procedure (based on distances derived from principal components analysis)] reveal interpopulation relationships consistent with Loukotka's language classification. The paleo-American tribes from the Gran Chaco and Brazil share a high incidence of whorls as a distinctive feature. The Andean and tropical forest groups, which present a greater prevalence of arches and ulnar loops, appear to be closely related to each other, suggesting a more recent common origin and/or substantial gene flow between them.     

Isozyme variation within and among populations of Microsporum species

Isozyme variation among 54 isolates of Microsporum canis, 18 Microsporum cookei isolates and two Diheterospora isolates were studied using starch gel electrophoresis. Of eight enzymes examined, four were polymorphic (EST, G6P, MDH and PEP), having from two to four electrophoretic forms. Within each species, consistent and reproducible isozyme patterns of the eight enzyme systems were obtained. Phenotypic diversity (H) in M. canis was higher than in M. cookei (H = 0.459 and H = 0.408 respectively), but phenotypic differentiation of M. canis isolates from different geographical regions (Auckland, Wellington and Palmerston North, New Zealand) was low, with a proportion of total diversity (Gst) of 0.151 found among the localities. The results suggest that the isolates of M. canis from different geographical regions are closely related, supporting the theory of a common lineage.     

Mitochondrial and nuclear genetic relationships among Pacific Island and Asian populations

Mitochondrial and autosomal short tandem-repeat (STR) genetic distances among 28 Pacific Island and Asian populations are significantly correlated (r=.25, P<.01) but describe distinct patterns of relationships. Maternally inherited-mtDNA data suggest that Remote Oceanic Islanders originated in island Southeast Asia. In contrast, biparental STR data reveal substantial genetic affinities between Remote Oceanic Islanders and Near Oceanic populations from highland Papua New Guinea and Australia. The low correlation between maternal and biparental genetic markers from the same individuals may reflect differences in genome-effective population sizes or in sex-biased gene flow. To explore these possibilities, we have examined genetic diversity, gene flow, and correlations among genetic, linguistic, and geographic distances within four sets of populations representing potential geographic and cultural spheres of interaction. GST estimates (a measure of genetic differentiation inversely proportional to gene flow) from mtDNA sequences vary between 0.13 and 0.39 and are typically five times greater than GST estimates from STR loci (0.05-0.08). Significant correlations (r>.5, P<.05) between maternal genetic and linguistic distances are coincident with high mtDNA GST estimates (>0.38). Thus, genetic and linguistic distances may coevolve, and their correspondence may be preserved under conditions of genetic isolation. A significant correlation (r=.65, P<.01) between biparental genetic and geographic distances is coincident with a low STR GST estimate (0.05), indicating that isolation by distance is observed under conditions of high nuclear-gene flow. These results are consistent with an initial settlement of Remote Oceania from island Southeast Asia and with extensive postcolonization male-biased gene flow with Near Oceania.     

Genetic variation among 129 substrains: practical consequences

We designed a series of experiments to define the role of IFN-gamma in cellular interactions mediating graft rejection by assessing the rejection of H-Y disparate grafts in both ligand and receptor knockout mice and their control inbred strain. In the course of these studies it became apparent that neither knockout strain is histocompatible with the putative control and that the putative control is not histocompatible with either knockout strain. In the process of deducing why this might be so, it became apparent that the putative control is not an inbred strain of mouse. Thus, in the absence of rigorous genetic control, the utility of such knockout strains of mice for assessing the effects of cytokines and receptors in transplantation and autoimmunity is limited.     

Genetic composition of Chilean aboriginal populations: HLA and other genetic marker variation

The sensitivity of spores B. subtilis and B. stearothermophilus to steam under pressure depended on the growth medium and duration of cultivation. B. subtilis and B. stearothermophilus produced the largest number of spores on medium with Mn and yeast extract. However the spores grown on the medium were not the most resistant. The resistant spores was growing up with the age of cultures. The highest level of resistance was obtained in the case of the medium with Ca, after 7-10 days of cultivation. The sporicidal effect of steam under pressure depended on the number of spores on the test.     

Variation in the sequence of a mitochondrial NADH dehydrogenase I gene fragment among six natural populations of Schistosoma japonicum from China

The present study investigated the level of genetic variation among Schistosoma japonicum populations of different geographical origins from mainland China. Polymerase chain reaction-based methods were employed to determine the sequence for a subunit of the mitochondrial NADH dehydrogenase I gene for populations from Zhejiang, Anhui, Jiangxi, Hunan, Hubei and Sichuan. No variation was detectable in the NADH dehydrogenase I sequence within populations from Zhejiang and Hubei, whereas sequence variation of 0.2% was detected within populations from Anhui, Jiangxi, Hunan and Sichuan. Pairwise comparison of the sequences representing the six different populations revealed genetic differences ranging from 0 to 0.6%.     

Genetic heterogeneity among the Hindus and their relationships with the other "Caucasoid" populations: new data on Punjab-Haryana and Rajasthan Indian states

The genetic structure of Rajasthan Hindus and Punjab-Haryana Hindus and Sikhs has been studied for ABO, RH, APOC2, C6, C7, F13A, F13B, HP, ORM1, ACP1, ADA, AK1, ESD, GLO1, PGD, PGM1 subtyping, and PGP. This is the first genetic survey on Hindus of Rajasthan. Furthermore, many of these markers have never been studied on Hindus before (APOC2, C6, C7, F13A, F13B, ORM1, PGP). These data, together with those previously available for Hindus, have been utilized to analyze the within-Hindus genetic heterogeneity by RST statistic and correspondence analysis. The genetic relationships of Hindus to other Causcasoid populations were also investigated. In the first analysis, two eastern states (Orissa and Andhra Pradesh) were found to be quite separate from each other and clearly distinct from the northwestern and western states. Out of the markers which could not be utilized in this analysis, PGM1 subtyping turned out to discriminate between the Dravidian-speaking and the Indo-Aryan-speaking Hindus. The second analysis shows a clear-cut separation of Hindus from Europeans, with Near Eastern and Middle Eastern populations genetically in an intermediate position.     

Genetic variation and prediction of additive and nonadditive genetic effects for six carcass traits in an Angus-Brahman multibreed herd

Estimates of covariances and sire expected progeny differences of additive and nonadditive genetic effects for six carcass traits were obtained using records from 486 straightbred and crossbred steers from 121 sires born between 1989 and 1995 in the Angus-Brahman multibreed herd of the University of Florida. Steers were slaughtered at a similar carcass composition end point. Covariances were estimated by REML procedures, using a generalized expectation-maximization algorithm applied to multibreed populations. Straightbred and crossbred estimates of heritabilities and additive genetic correlations were within ranges found in the literature for steers slaughtered on an age- or weight-constant basis for hot carcass weight, longissimus muscle area, and shear force but equal to or less than the lower bound of these ranges for fat-related traits. Maximum values of interactibilities (i.e., ratios of nonadditive variances to phenotypic variances in the F1) and nonadditive genetic correlations were smaller than heritabilities and additive genetic correlations in straightbreds and crossbred groups. Sire additive and total direct genetic predictions for longissimus muscle area, marbling, and shear force tended to decrease with the fraction of Brahman alleles, whereas those for hot carcass weight and fat thickness over the longissimus were higher, and those for kidney fat were lower in straightbreds and F1 than in other crossbred groups. Nonadditive genetic predictions were similar across sire groups of all Angus and Brahman fractions. These results suggest that slaughtering steers on a similar carcass composition basis reduces variability of fat-related traits while retaining variability for non-fat-related traits comparable to slaughtering steers on a similar age or weight basis. Selection for carcass traits within desirable (narrow) ranges and slaughter of steers at similar compositional end point seems to be a good combination to help produce meat products of consistent quality.     

Genetic relationships among Pseudomonas stutzeri strains based on molecular typing methods

Prostaglandin D synthetase (PGD-S; prostaglandin-H2 D-isomerase, EC 5,3,99,2), a 30 kDa glycoprotein also known as beta-trace protein that catalyzes the formation of prostaglandin D2 (PGD2) from PGH2, was purified to apparent homogeneity from human cerebrospinal fluid (CSF) using a two-step procedure involving HPLC on a Vydac C8 reversed-phase column and high performance electrophoresis chromatography (HPEC) using a 10% T SDS-polyacrylamide gel. The purity of PGD-S isolated from CSF was confirmed by silver stained SDS-polyacrylamide gel and direct protein microsequencing (NH2-APEAQVSVQPNFQ). A highly specific polyclonal antibody was prepared against this protein for immunoassay development. Using an ELISA, it was found that the concentration of PGD-S in CSF did not alter significantly in different pathological conditions of the central nervous system (CNS). These include dementia (n = 9), hydrocephalus (n = 4), neuropathy (n = 11), optic neuritis (n = 4), multiple sclerosis (n = 11), and demyelinating syndrome (n = 11), when compared to normal individuals (n = 12); however, the level of PGD-S in the CSF obtained from patients with brain tumor (n = 11), was reduced by as much as 2-fold when compared to control samples (n = 12) illustrating PGD-S is a potentially useful marker for brain tumor.     

Physiological variation and adaptability in human populations

This review traces some of the developments in population physiology based on contributions to the Annals over the last 25 years. Two broad themes are evident, physiological systems variation and adaptation, and by way of introduction an historical perspective of their relationship within human ecology is explored. Studies of physical fitness and work capacity, and the efforts to create standardized field procedures make up a number of the early papers. Longitudinal studies have provided reliable reference standards for Westernized populations, but are virtually non-existent for primitive groups. The relative importance of phenotypic and genotypic variations in working capacity have yet to be clearly defined. The level of habitual activity during childhood contributes to the development of ventilatory capacity though constitutional influences are of major importance. Variability in strength and motor performance of skeletal muscles are shown to have a direct bearing on aspects of growth, development and biological maturation. Physical and psychological stress in communities have been investigated. These and other studies contribute valuable data on the issue of stress, hypertension and cardiovascular morbidity and mortality. On the theme of human adaptability, high altitude populations, variations in thermal tolerance and adaptations in ageing populations have all received recent investigation. Highland people of all ages have considerably larger lung volumes than coastal dwellers. Haematological, biochemical and pulmonary function show adaptive phenomena that vary in different highland groups. In the tropical biome, more recent work includes the functional consequences of malnutrition, ethnic and cultural differences in work capacity, and the effects of endemic disease on physical performance. Annals of Human Biology papers have more recently contributed to investigations on morphological and physiological changes with human ageing. Though there is a decline in the ability to adapt to environmental stresses with age this may be met by changes in adaptational strategy in physiological systems.     

Geographic variation of six dermatoglyphic traits in Eurasia

We describe the geographic variation patterns of six dermatoglyphic traits from 144 samples in Eurasia. The methods of analysis include computation of interpolated surfaces, one-dimensional and directional correlograms, correlations between all pairs of surfaces, and distances between correlograms. There are at least two, probably three, distinct and significant patterns of variation. 1) A general NW-SE trend for pattern intensity, the main line index, and frequency of hypothenar patterns. 2) A trend from the Middle East to the north and east for frequency of axial triradius and of accessory interdigital triradii. 3) A patchy pattern for frequency of the thenar-interdigital 1. The results are compatible with a diffusion process between Europe and the peoples of Northern Asia, and possibly with a radiation of populations from the Middle East. The hypothesis of diffusion processes is supported by substantial interpopulation correlations between dermatoglyphic traits that contrast sharply with largely negligible intralocality correlations.     

New protein genetic studies in six Amazonian Indian populations

A total of 732 individuals affiliated with six Amazonian Indian populations were variously studied in relation to 26 protein genetic systems. Eleven of them were found to be monomorphic in these groups, in accordance with previous investigations. Similarities and dissimilarities (the latter involving the Rh, Duffy, haptoglobin and transferrin systems) were observed in relation to earlier investigations in four of these populations (Galibi, Palikour, Mundurucu and Tenharim). A dimeric, cathodal variant of albumin was found among two Galibi subjects, and the fairly common occurrence of CP* ACAY among some South American Indian populations was confirmed. The results in the six populations were compared with those from 29 others. When relationships are searched for among tribes of the same linguistic group, the factor that seems to be most influential is geographical localization, an exception being the pattern observed among the Cayapo subgroups. The latter shows genetic differences of the same level of magnitude as those observed among Ge-speaking tribes.     

Genetic variation in heterogeneous environments

A model of population structure in heterogeneous environments is described and conditions sufficient for maintaining a polymorphism are derived. The absolute fitness of any genotype is regarded as a function of location in the niche space and the population density at that location. Two modes of habitat selection are examined: (1) organisms are distributed uniformly over the environment; and (2) each organism selects to occupy that habitat in which it is most fit ("optimal habitant selection"). Sufficient conditions for maintenance of genetic polymorphisms are derived for both models. In populations which do not practice habitat selection heterozygote superiority averaged over the environment is sufficient to guarantee the existence of polymorphisms. Comparable conditions for populations which practice optimal habitat selction are much less restrictive. If the heterozygotes are superior to one homozygote in any one part of the niche and to the other homozygote in any other part of the niche then a polymorphism will be defined. A positive correlation between genetic and environmental variation follows from the model with habitat selection, but not from the other. The adaptive significance of polymorphisms thus depends on how animals behave.     

Effect of corn plants and rhizosphere populations on pesticide degradation

The aim of this study was to check the usefulness of urine beta-hexosaminidase activity determination as a tool of monitoring sobriety in alcohol dependent individuals. The examinations were performed in 93 patients undergoing detoxification treatment after heavy drinking and in 29 individuals who were starting psychotherapeutic treatment after declaring at least 2 weeks abstinence period. Enzyme activity was determined using a spectrofluorimetric method and was referred to urine creatinine level. In the detoxification group the abnormally high beta-hexosaminidase activity was decreasing gradually toward normal values within 2 weeks. In less than 10% of the patients atypical increase was observed in the course of treatment, what could be attributed to an, influence of nonspecific factors or possibly to misbehavior (alcohol drinking or urine samples substitution). Among individuals who declared at least 2 weeks abstinence period (psychotherapeutic group) in 25% of cases abnormally high enzyme activity was detected, what suggested their more recent alcohol drinking.     

Genetic differentiation among local populations of the European hedgehog (Erinaceus europaeus) in mosaic habitats

Tissue samples from 160 European hedgehogs, Erinaceus europaeus, representing eight small populations from a highly fragmented landscape in Oxfordshire, UK, were screened for polymorphism at six microsatellite loci. Permutation analysis of allelic compositions revealed no evidence for linkage disequilibrium among loci. Genotype proportions within populations and at five loci did not differ from those expected at Hardy-Weinberg equilibrium. However, significant heterozygote deficit and amplification failure of several samples necessitated removal of one locus from the analysis. Mean observed heterozygosity was 0.70. Average RhoST was 0.079 and differed significantly from zero, suggesting restricted gene flow among local populations. Pairwise Nm values and geographical distance were not correlated, indicating that factors other than distance affected dispersal.     

Genetic variation in the east Midlands

According to history, the population of the British Isles derives its genepool from a succession of invaders and immigrants. The settlement pattern of these invaders gave rise to a patchwork of genepools, shown in previous genetic surveys. Specimens from 1117 blood donors of regionally subdivided East Midlands (Derbyshire, Nottinghamshire and Leicestershire) were analysed for 18 conventional genetic systems (blood groups, serum proteins and red cell enzymes), according to place of residence. Significant differences exist among the five geographically defined sub-populations, and it is argued that these are derived from the historical settlement of continental European populations in the region, especially the Danes and the Vikings.     

Among-site rate variation and phylogenetic analysis of 12S rRNA in sigmodontine rodents

We analyze sequences from two mitochondrial genes, cytochrome b (cyt b) and 12S rRNA (12S), for a group of sigmodontine rodents among which phylogenetic relationships are well understood based on concordance of morphological, chromosomal, allozyme, and other DNA data sets. Because these two genes are physically linked on the nonrecombining mitochondrial genome, they necessarily share the same history. Phylogenetic analysis of the cyt b gene recovers the well-corroborated relationships, generally with strong support. None of the methods that we employed, including variously weighted parsimony, neighbor joining on both single-rate and gamma-corrected distances, and maximum likelihood, were able to recover these relationships for the 12S gene. Parsimony analyses of the 12S data resulted in a relatively strongly supported placement of Peromyscus eremicus that conflicts with that suggested by cyt b and all other data. There is extreme among-site rate variation in the 12S sequences and moderate levels in the cyt b sequences. This highly skewed distribution of rates in the 12S gene makes phylogenetic analyses of these sequences particularly susceptible to the misleading effects of nonindependence and other nonrandom noise, suggesting that phylogenetic analyses of data sets that contain a great deal of among-site rate variation be interpreted with caution.     

Genetic variation in some Oxfordshire villages

The patterns of serological polymorphic variety in a group of Oxfordshire populations are related to previously made demographic predictions that the different villages and social classes might be expected to be genetically homogeneous if movement were the main factor determining genetic structure. The predictions are largely fulfilled though there remains a residual pattern of variety which is detectable when all the systems tested are considered together by "genetic distance" examination, and in the case of the geographic variation this pattern reflects the comparative magnitude of the exchanges between the different villages.     

Molecular evolution of the internal transcribed spacers (ITS1 and ITS2) and phylogenetic relationships among species of the family Cucurbitaceae

Phylogenetic relationships of different members of the family Cucurbitaceae were estimated from sequences of the internal transcribed spacer (ITS1 and ITS2) regions of the nuclear ribosomal RNA genes. Twenty-six species of different genera belonging to different tribes and several subtribes were analyzed. The whole ITS regions were amplified by PCR technique and cloned, and three to five different clones of each species were sequenced; for some species PCR products were sequenced directly. ITS1 and ITS2 regions are slightly variable in length, with each length appearing genus-specific. A substitution rate of 3.62 x 10(-9) substitutions per site per year was calculated assuming 40 MYA separation time. Phylogenetic relationships inferred from ITS sequences of some species is in agreement with morphological data, but deviations to the taxonomic classification were also observed. A polyphyletic origin of the New World species must be considered. In the genus Cucurbita different "types" of ITS sequences within one species exist, possibly due to the high frequency of introgression during domestication or due to polyploidization events; in contrast, low intraspecific variability was detectable in the genus Cucumis, indicating different stages of speciation.