Pharmacological Ethnic Metabolic Safety: Communication I

The concept of pharmacological ethnic safety is presented. Drug safety varies for different ethnic groups (populations) depending on their metabolic status, i.e., the proportion of individuals with a certain phenotype for drug metabolism (inactivation) and the starting (initial) state of the enzymes metabolizing them. To determine population metabolic status and predict the possible risk of drug side effects, compilation of ethnic pharmacological data sheets is needed. According to the results, drugs exported to monoethnic and multiethnic countries should be thoroughly tested for metabolic safety for ethnic groups with particular drug-metabolism phenotypes. On the basis of this concept, the ethnic metabolic safety of drugs subjected to phase I biotransformation reactions (oxidation and hydrolysis) has been theoretically estimated. The dependence of the predisposition to side effects of these drugs on the frequencies of different phenotypes for the types and rates of these two reactions is specially emphasized.     

Metabolic “in-vivo Designing” of Tumors at the Organism and Population Levels under Conditions of Individual Genetic Predisposition. Communication III

Using several populations (ethnic groups) as an example and by means of the statistical analysis of the data available in literature, we theoretically justified the possibility of metabolic in vivo designing of tumors in bronchi and lungs, larynx, brain and nervous system, mammary gland, bladder, and liver at the human organism and population levels under conditions of genetically-determined metabolic status of these populations, i.e., the possibility of population-dependent carcinogenesis in the above organs. A comparison of the populations showed that the incidences of cancer (a) in each of the six organs was dissimilar at the different rate of one or other metabolic phenotype and (b) in each of the three organs, larynx, mammary gland, and bladder, it was similar at the same rate of one or other metabolic phenotypes. No population-dependent carcinogenesis in all six or several other organs was observed in the compared populations in the following cases: different cancer incidence in each of six organs at the same rate of one or other metabolic phenotype; similar cancer incidences in each of four organs—larynx, brain and nervous system, mammary gland, and bladder—at a different rate of one or other metabolic phenotypes; and different cancer incidence in organs, other than the mammary gland and liver, in males and females, irrespective of the rate of metabolic phenotype. These data on the incidence rate included no data on chemical carcinogenesis. To prove the population-dependent carcinogenesis in the above-mentioned and other organs, it is necessary to theoretically study and identify the molecular structures responsible for carcinogenesis in tumor cells obtained from representatives of different populations with certain metabolic phenotypes.     

Metabolic Populational in vivo Construction of Tumors under Conditions of Individual Genetic Predisposition: Communication II

The results of the analysis of the literature data on the ethnic distribution of xenobiotic biotransformation phenotypes and on tumor incidence (for all organs in total) are presented from the standpoint of the concept by L.A. Piruzyan [1]. For a number of ethnic groups, a possibility is theoretically shown of the metabolic populational in vivo construction of tumors (depending on the genetically determined metabolic status of certain populations), i.e., of the ethnic dependence of tumors. In the American population, the higher incidence of the slow acetylation phenotype than in Swedes and in the Chinese was associated with the higher incidence of morbidity. In populations of the English, the Germans, the Swedes, and the Swiss, characterized by a low incidence of the slow acetylation phenotype, the tumor morbidity was higher than in the Chinese with a higher incidence of slow acetylators. Americans are more predisposed to tumors than the Swedes. Caucasoids with either the slow or the fast acetylation phenotype are more predisposed to tumors than the Chinese. The prevalence of the fast acetylation phenotype in the Chinese and Japanese populations was associated with the lower cancer morbidity: in the Chinese compared to Australians, Danes, Swedes; in the Japanese compared to Australians, Americans, the English, Danes, Canadians, the German, the Portuguese, Finns, Czechs, and Slovaks. The lower incidence of the slow acetylators in the Chinese than in Americans, English, Danes, Canadians, Germans, Finns, Czechs, Slovaks, and Swedes was associated with a lower rate of morbidity. In the Portuguese, the higher incidence of fast acetylators than in Danes and the lower incidence of slow acetylators than in Czechs, Slovaks, and Afro-Americans was associated with the lower rate of morbidity. In the Hong Kong and Singapore Chinese with the lower incidence of slow acetylators than in the Madras Negroids, the morbidity was higher. In Australians and Swedes, the greater fraction of slow acetylators was associated with a lower morbidity than in Afro-Americans. In the Russian population of St. Petersburg, the higher incidence of slow acetylators was associated with the lower morbidity compared to the Hong Kong Chinese. Among Poles, the slow acetylator incidence was higher and the morbidity was lower than in the Portuguese. The Japanese and the Chinese (fast acetylators) are less predisposed to cancer than the above-listed Caucasoids; among Caucasoids, the Portuguese (fast acetylators) were less predisposed to cancer than the Danes, Czechs, Slovaks, and Afro-Americans. The tumor predisposition of the Hong Kong and Singapore Chinese was higher than the predisposition of the Madras Negroids. Australians, Russians (St. Petersburg residents), and Poles were less predisposed to cancer than Afro-Americans, the Hong Kong Chinese, and the Portuguese. The morbidity of the Madras Negroids with the higher incidence of the slow acetylation phenotype was lower than the morbidity of the Hong Kong and Singapore Chinese. The incidence of the slow acetylation phenotype in Afro-Americans was lower than in the Australians and Swedes and higher than in the Portuguese, Chinese, and Japanese; this was associated with the higher cancer morbidity, i.e., with the increased predisposition to tumors. The lower incidence of the T1-0 phenotype of glutathione-S-transferase in the English than in the Singapore and Shanghai Chinese and in the Japanese was associated with the higher morbidity of the English. In the Singapore Chinese, the higher incidence of the M1-0 and of T1-0 phenotypes of glutathione-S-transferase than in the Japanese was associated with the increased morbidity. In some populations, different morbidities were associated with similar incidences of one or another metabolic phenotype, or different phenotype incidences in different populations were associated with similar morbidities. The morbidity under consideration did not include chemical carcinogenesis, i.e., the conversion of procarcinogens to true carcinogens or the carcinogen inactivation. Because the results presented are preliminary, this article outlines the directions of theoretical studies that are required for definite conclusions concerning the ethnic dependence of tumors.     

Allee effects, aggregation, and invasion success

Understanding the factors that influence successful colonization can help inform ecological theory and aid in the management of invasive species. When founder populations are small, individual fitness may be negatively impacted by component Allee effects through positive density dependence (e.g., mate limitation). Reproductive and survival mechanisms that suffer due to a shortage of conspecifics may scale up to be manifest in a decreased per-capita population growth rate (i.e., a demographic Allee effect). Mean-field population level models are limited in representing how component Allee effects scale up to demographic Allee effects when heterogeneous spatial structure influences conspecific availability. Thus, such models may not adequately characterize the probability of establishment. In order to better assess how individual level processes influence population establishment and spread, we developed a spatially explicit individual-based stochastic simulation of a small founder population. We found that increased aggregation can affect individual fitness and subsequently impact population growth; however, relatively slow dispersal—in addition to initial spatial structure—is required for establishment, ultimately creating a tradeoff between probability of initial establishment and rate of subsequent spread. Since this result is sensitive to the scaling up of component Allee effects, details of individual dispersal and interaction kernels are key factors influencing population level processes. Overall, we demonstrate the importance of considering both spatial structure and individual level traits in assessing the consequences of Allee effects in biological invasions.     

Diverging pathways: Differential benzenoid and phenylpropanoid volatile production in Phlox subulata L. cultivars

Previous research into the genetic mechanisms of benzenoid and phenylpropanoid volatile biosynthesis has suggested the potential for metabolic flux, in which phenylalanine substrate dedicated to one pathway branch (i.e., benzenoid production) could alter volatile production in other pathways (i.e., phenylpropanoid production). However, little research has been conducted in planta to verify the validity of this hypothesis. We examined the emission rates of representative benzenoid and phenylpropanoid volatiles from seven cultivars of Phlox subulata L. to determine if cultivars had metabolic flux differences in terms of these two compound categories. Cultivars that produced large quantities of methyl benzoate and benzaldehyde were found to emit little or no phenylacetaldehyde and 2-phenylethanol, and vice versa. These results suggest that P. subulata cultivars experience phenylalanine substrate flux directed toward one pathway and away from the alternate branch. Such a pattern may be the result of differential selection pressures, in which gene expression has been altered to direct flux away from either benzenoid or phenylpropanoid production. Moreover, if these patterns hold true in wild populations, metabolic flux may lead to differential pollinator behavior and further phenotypic evolution. Future research using molecular tools could verify the role of metabolic flux in determining scent phenotypes and pinpoint the exact nature of the genetic mutations leading to phenotypic differences in odor.     

Frequencies of ABO, Rh and Kell phenotypes in couples from Han, Kazak, Uyghur and Hui in Xinjiang: an inheritance simulation model for blood group incompatibility in new-born

The Xinjiang region with residents from more than 13 minorities represents an area of many diverse ethnicities. This ethnic diversity in relation to their blood groups and immune status may have a consequential impact on the clinical status of married couples. To evaluate the risks of haemolytic disease in new-born infants, we investigated the rate of blood-group incompatibility among 487 married couples from four ethnic minorities, namely the Han, Hui, Uyghur and Kazak populations. Han minority married couples showed significantly different ABO, Rh and K phenotype frequencies between marrial relationship, whereas there was no significant difference in ABO, Rh and K phenotypes between the Uyghur, Hui and Kazak .There was a significant difference between ABO blood types in Han married couples, in the Kazak Rh-C phenotype and in the Uyghur Rh-D phenotype. The Hui married couples only demonstrated ABO, Rh and K phenotypes. The Hui minority showed the highest incompatibility rate for Rh-C and Rh-E phenotypes between mothers and their new-born infants. The highest incompatibility rate for the ABO phenotype occurred in the Kazak group. These results particularly demonstrate the clinical issues relating to ABO and Rh incompatibility, in the Kazak and Hui minorities, respectively.     

Muscle 31P-NMR in humans: estimate of bias and qualitative assessment of ATPase activity.

A mathematical model is developed whereby the longitudinal magnetization of phosphocreatine (PC), ATP, Pi, and total phosphate (PT) can be calculated on the basis of assumed chemical rate constants (kappa i) and spin lattice relaxation times of the muscle PC in equilibrium ATP in equilibrium Pi exchange system. By means of this model, some unexplained 31P nuclear magnetic resonance (NMR) spectroscopy results from the literature (e.g., a decrease of PT in a closed system) could be explained simply on the basis of the physiological variability of kappa i. Moreover, appropriate model simulations indicate that 1) 31P-NMR spectra obtained with short relaxation delays may be influenced to various extents by the metabolic and physicochemical status of the muscle; 2) the assessment of kappa i by standard NMR spectroscopy techniques may be extremely critical; 3) delta PC/delta Pi, as obtained from conventional 31P-NMR spectra, may represent a sensible index of kappa 2 (the pseudo first-order chemical exchange rate constant of the adenosinetriphosphatase reaction); 4) delta PC/delta Pi changes as detected from sequential (short relaxation delays) 31P-NMR spectra obtained in humans during metabolic transients (e.g., during transition from rest to work and vice versa) may represent an index of transient changes of kappa 2.     

Floater dynamics can explain positive patterns of density-dependent fecundity in animal populations

After some 70 years of debate on density-dependent regulation of animal populations, there is still poor understanding of where spatial and temporal density dependence occurs. Clearly defining the portion of the population that shapes density-dependent patterns may help to solve some of the ambiguities that encircle density dependence and its patterns. In fact, individuals of the same species and population can show different dynamics and behaviors depending on their locations (e.g., breeding vs. dispersal areas). Considering this form of intrapopulation heterogeneity may improve our understanding of density dependence and population dynamics in general. We present the results of individual-based simulations on a metapopulation of the Spanish imperial eagle Aquila adalberti. Our results suggest that high rates of floater mortality within settlement areas can determine a shift in the classical relationship (from negative to positive) between the fecundity (i.e., fledglings per pair) and density (i.e., number of pairs) of the breeding population. Finally, we proved that different initial conditions affecting the breeder portion of the population can lead to the same values of fecundity. Our results can represent a starting point for new and more complex approaches studying the regulation of animal populations, where the forgotten and invisible component--the floater--is taken into account.     

Saprotrophic bacteria as a possible means of controlling the immune status of the body through regulation of metabolic reactions

An analysis of the literature allowed a theoretical grounding of the possibility of microbial control of the immune status of the organism by the use of saprotrophic bacteria regulating its metabolic status (i.e., its enzymatic reactions). The main objective of the microbial control is protection from infections caused by conditionally pathogenic microflora. Bacterial formulations can produce the following effects: (1) a decrease in the activities of the oxidation system, glucuronyl transferase, and NAD⁺ glycohydrolase and an increase in the activity of glucose-6-phosphate dehydrogenase in hepatic microsomes; (2) an increase or a decrease in acetylation activity in the liver and its increase in lymphocytes; (3) an increase in the activities of the enzymes of glycolysis, the hexose monophosphate shunt, and the NADPH oxidase system, as well as succinate and glutamate dehydrogenases, acid phosphatase, -naphthyl acetate esterase, and nonspecific esterase, in immunocompetent cells; and/or (4) stimulation of humoral and cell-mediated immunity. To achieve microbial control over the immune status of the human organism, it is necessary (1) to study the correlations between the pharmacokinetics of test substances, the activities of enzymes involved in their metabolism, and humoral and cell mediated immune reactions; (2) to determine the metabolic phenotypes of individuals; (3) to identify and systematize the normal saprotrophic microflora of each individual; (4) to elucidate the molecular mechanisms of biochemical effects exerted by saprotrophic bacteria; and (5) to select specific strains of saprotrophic bacteria that secrete substances regulating the activities of the above enzymes and metabolic processes. Different tactics of the microbial control of the individual immunity should be selected for subjects with different phenotypes.Translated from Fiziologiya Cheloveka, Vol. 31, No. 1, 2005, pp. 88–99.Original Russian Text Copyright © 2005 by Piruzyan, Mikhailovskii.This work is based on an original concept suggested by L.A. Piruzyan.     

中国壮族和裕固族群体HLAⅠ类区域Alu插入多态性及其与HLA-A位点的相关性

近年来研究发现: 位于HLAⅠ类基因区域的Alu插入是研究不同群体HLAⅠ类基因区域祖先单倍型和HLAⅠ类基因多样性产生、进化和重组的理想工具。文章对中国壮族和裕固族群体HLAⅠ类基因区域5个Alu插入多态性(AluMICB、AluTF、AluHJ、AluHG和AluHF)进行研究, 结合HLA基因分型数据, 分析壮族、裕固族、哈尼族、布朗族和傣族5个民族群体中Alu插入与HLA-A等位基因的关系。研究结果显示: (1)壮族和裕固族人群中5个Alu插入频率范围分别为1.5%~35.8%和9.2~34.8%, AluMICB、AluTF和AluHF插入频率在这两个群体中有统计学差异(P<0.05); (2)在5个研究的群体中, AluHG插入与HLA-A*02的不同亚型关联; AluHJ插入与HLA-A*2402在5个群体中都关联, 但AluHJ与HLA-A*1101和HLA-A*2407只在布朗族中关联。表明不同群体HLAⅠ类基因区域内Alu插入具有各自的特征, 且Alu插入与不同的HLA-A等位基因相关联。这种Alu插入及其与HLA-A的关联特征可作为研究群体中HLAⅠ类基因和单倍型系谱变化的重要遗传标记。     

Adipokine serum concentrations, anthropometric measurements and socio-economic status in two ethnic groups with different prevalence levels for cardiovascular diseases and type 2 diabetes

Obesity is more common in African than Asian-Indian populations and yet type 2 diabetes and cardiovascular diseases are more common in the latter populations. The main purpose of the current study was therefore to determine whether ethnic differences in body fat distribution, adipokine levels, and socio-economic status may explain population differences in the prevalence of these metabolic disorders. Leptin, IL-6, CRP, visceral fat, education level, and socio-economic status were measured in 50 African and the same number of Indian women residing in Johannesburg, South Africa. Serum leptin levels were significantly higher in Indian than African subjects (41.3±2.0 and 34.2±2.9?ng/ml, respectively; p<0.05). TNF-α levels were significantly higher in the African group, (5.22±0.86 vs. 2.54±0.52?pg/ml; p<0.05), whilst visceral fat levels were significantly lower (56.1±5.5 vs. 77.9±6.5?cm(2); p<0.05). The CRP and IL-6 levels were not different between groups. Education levels (p<0.005) and socio-economic status (p<0.0001) were both lower in the African subjects, however, adjusting for these variables in ANCOVA did not attenuate differences in adipokine or visceral fat levels. We hypothesise that one of the reasons for the higher prevalence of obesity in the African than Indian population may be related to lower leptin levels, whilst ethnic differences in the prevalence of metabolic disorders cannot be explained by differences in adipokine levels, but maybe related to higher visceral adiposity in the Indian group.     

Mutations of the tyrosinase gene in patients with oculocutaneous albinism from various ethnic groups in Israel.

We have analyzed the tyrosinase (TYR) gene in 38 unrelated patients with oculocutaneous albinism (OCA), derived from several different ethnic groups of the diverse population of Israel. We detected TYR gene mutations in 23 of the 34 patients with apparent type I (i.e., tyrosinase-deficient) OCA and in none of the patients with other clinical forms of albinism. Among Moroccan Jews with type IA (i.e., tyrosinase-negative) OCA, we detected a highly predominant mutant allele containing a missense substitution, Gly47Asp (G47D). This mutation occurs on the same haplotype as in patients from the Canary Islands and Puerto Rico, suggesting that the G47D mutation in these ethnically distinct populations may stem from a common origin.     

More than black and white: differences in predictors of obesity among Native Hawaiian/Pacific Islanders and European Americans

Although Native Hawaiians and Pacific Islanders exhibit the highest rates of obesity and associated chronic diseases of any racial/ethnic group, they remain vastly underrepresented in health research. In a cross-sectional survey of college students (N = 402) we examined BMI and health outcomes in an ethno-racially diverse rural sample of Native Hawaiian/Pacific Islanders (25.1%), Asian Americans (39.8%), and European Americans (35.1%). Measures assessed BMI, health status, health behaviors, frequency of exercise, and symptoms of psychiatric disorders (i.e., depression, anxiety, posttraumatic stress, and substance abuse and dependence). Regression analyses revealed that an overall model of five predictors (gender, race, regular exercise, difficulty sleeping, and anxiety) was significantly associated with obesity (P < 0.001) and correctly classified 84.2% of cases. A 30.7% of Native Hawaiians/Pacific Islanders were obese as compared with 9.2% of European Americans and 10.6% of Asian Americans. These findings suggest that Native Hawaiian/ Pacific Islanders are at high risk for obesity and associated medical comorbidities, but that regular physical activity may ameliorate this risk. Further, these results support the consideration of Native Hawaiians/Pacific Islanders as a distinct racial/ethnic subgroup separate from other Asian populations.     

Radiation-hormesis phenotypes,the related mechanisms and implications for disease prevention and therapy

Humans are continuously exposed to ionizing radiation throughout life from natural sources that include cosmic, solar, and terrestrial. Much harsher natural radiation and chemical environments existed during our planet’s early years. Mammals survived the harsher environments via evolutionarily-conserved gifts a continuously evolving system of stress-induced natural protective measures (i.e., activated natural protection [ANP]). The current protective system is differentially activated by stochastic (i.e., variable) low-radiation-dose thresholds and when optimally activated in mammals includes antioxidants, DNA damage repair, p53-related apoptosis of severely-damaged cells, reactive-oxygen-species (ROS)/reactive-nitrogen-species (RNS)- and cytokine-regulated auxiliary apoptosis that selectively removes aberrant cells (e.g., precancerous cells), suppression of disease promoting inflammation, and immunity against cancer cells. The intercellular-signaling-based protective system is regulated at least in part via epigenetic reprogramming of adaptive-response genes. When the system is optimally activated, it protects against cancer and some other diseases, thereby leading to hormetic phenotypes (e.g., reduced disease incidence to below the baseline level; reduced pain from inflammation-related problems). Here, some expressed radiation hormesis phenotypes and related mechanisms are discussed along with their implications for disease prevention and therapy.     

禁食对胭脂鱼幼鱼游泳能力、热耐受能力和自发运动的影响

为了考察1—2周禁食对胭脂鱼(Myxocyprinus asiaticus)幼鱼游泳能力、热耐受能力和自发运动的影响,以胭脂鱼幼鱼[体质量(3.26±0.64) g,体长(5.32±0.32) cm]为实验对象,将其随机分成对照组、1周禁食组和2周禁食组测定其有氧运动能力及其代谢、热耐受能力和自发运动行为相关参数。结果发现:1周禁食组和2周禁食组的静止代谢和临界游泳速度与对照组没有显著性差异,但其最大代谢率、代谢空间、单位位移能量消耗、头高/头长及体高/体长显著低于对照组(P<0.05); 1周禁食组和2周禁食组的临界低温和致死低温与对照组没有显著性差异,但其临界高温和致死高温显著高于对照组(P<0.05); 1周禁食组和2周禁食组的运动总距离、平均运动速度和运动时间百分比与对照组没有显著性差异。综上所述:胭脂鱼幼鱼采取有氧运动能力和自发运动行为的维持策略应对1—2周禁食胁迫,这可能有利于维持其日常的觅食活动。此外,尽管对低温耐受没有显著影响,但1—2周的禁食显著提高了胭脂鱼幼鱼的高温耐受能力。     

Distributions of oxygen,nutrient, and metabolic waste concentrations in multicellular spheroids and their dependence on spheroid parameters

The distribution of oxygen, nutrients and metabolic wastes in multicellular tumor spheroids and its dependence on the parameters characterizing the spheroid (i.e., spheroid geometry, diffusivity, and consumption/ production rates of biological substances) have been investigated by a theoretical analysis: 1. Parameter dependence is qualitatively demonstrated and visualized. 2. Reduction of the number of variables by specific coordinate transformations made it possible to generate nomograms from which concentration distributions for any choice of parameter values may easily be obtained. In particular, these nomograms may also be used for estimating concentration profiles of metabolic waste products, e.g. of lactate, which are expected to accumulate in the tumor spheroids. 3. An additional set of nomograms is given which is more convenient for determining time courses of these concentrations during spheroid growth. 4. A quantitative sensitivity analysis of parameter dependencies is performed to identify those parameters upon which a concentration of interest depends most critically in a given experimental situation. Offprint requests to: W Mueller-Klieser     

中国壮族和裕固族群体HLA Ⅰ类区域Alu插入多态性及其与HLA-A位点的相关性

近年来研究发现:位于HLAⅠ类基因区域的Alu插入是研究不同群体HLAⅠ类基因区域祖先单倍型和HLAⅠ类基因多样性产生、进化和重组的理想工具。文章对中国壮族和裕固族群体HLAⅠ类基因区域5个Alu插入多态性(AluMICB、AluTF、AluHJ、AluHG和AluHF)进行研究,结合HLA基因分型数据,分析壮族、裕固族、哈尼族、布朗族和傣族5个民族群体中Alu插入与HLA-A等位基因的关系。研究结果显示:(1)壮族和裕固族人群中5个Alu插入频率范围分别为1.5%~35.8%和9.2~34.8%,AluMICB、AluTF和AluHF插入频率在这两个群体中有统计学差异(P<0.05);(2)在5个研究的群体中,AluHG插入与HLA-A*02的不同亚型关联;AluHJ插入与HLA-A*2402在5个群体中都关联,但AluHJ与HLA-A*1101和HLA-A*2407只在布朗族中关联。表明不同群体HLAⅠ类基因区域内Alu插入具有各自的特征,且Alu插入与不同的HLA-A等位基因相关联。这种Alu插入及其与HLA-A的关联特征可作为研究群体中HLAⅠ类基因和单倍型系谱变化的重要遗传标记。     

Ethnicity and human genetic linkage maps

Human genetic linkage maps are based on rates of recombination across the genome. These rates in humans vary by the sex of the parent from whom alleles are inherited, by chromosomal position, and by genomic features, such as GC content and repeat density. We have examined--for the first time, to our knowledge--racial/ethnic differences in genetic maps of humans. We constructed genetic maps based on 353 microsatellite markers in four racial/ethnic groups: whites, African Americans, Mexican Americans, and East Asians (Chinese and Japanese). These maps were generated using 9,291 subjects from 2,900 nuclear families who participated in the National Heart, Lung, and Blood Institute-funded Family Blood Pressure Program, the largest sample used for map construction to date. Although the maps for the different groups are generally similar, we did find regional and genomewide differences across ethnic groups, including a longer genomewide map for African Americans than for other populations. Some of this variation was explained by genotyping artifacts--namely, null alleles (i.e., alleles with null phenotypes) at a number of loci--and by ethnic differences in null-allele frequencies. In particular, null alleles appear to be the likely explanation for the excess map length in African Americans. We also found that nonrandom missing data biases map results. However, we found regions on chromosome 8p and telomeric segments with significant ethnic differences and a suggestive interval on chromosome 12q that were not due to genotype artifacts. The difference on chromosome 8p is likely due to a polymorphic inversion in the region. The results of our investigation have implications for inferences of possible genetic influences on human recombination as well as for future linkage studies, especially those involving populations of nonwhite ethnicity.     

Coevolution of Contrary Choices in Host-Parasitoid Systems

We investigate patch selection strategies of hosts and parasitoids in heterogeneous environments. Previous theoretical work showed that when host traits vary among patches, coevolved populations of hosts and parasitoids make congruent choices (i.e., hosts and parasitoids preferentially select the same patches) and exhibit direct density dependence in the distribution of percent parasitism. However, host-parasitoid systems in the field show a range of patterns in percent parasitism, while behavioral studies indicate that hosts and parasitoids can exhibit contrary choices (i.e., hosts avoid patches favored by the parasitoid). We extend previous theory by permitting life-history traits of the parasitoid as well as the host to vary among patches. Our analysis implies that in coevolutionarily stable populations, hosts preferentially select patches that intrinsically support higher host equilibrium numbers (i.e., the equilibrium number achieved by hosts when both populations are confined to a single patch) and that parasitoids preferentially select patches that intrinsically support higher parasitoid equilibrium numbers (i.e., the equilibrium number achieved by the parasitoids when both populations are confined to a patch). Using this result, we show how variation in life-history traits among patches leads to contrary or congruent choices or leads to direct density dependence, inverse density dependence, or density independence in the distribution of percent parasitism. In addition, we determine when populations playing the coevolutionarily stable strategies are ecologically stable. Our analysis shows that heterogeneous environments containing patches where the intrinsic rate of growth of the host and the survivorship rate of the parasitoid are low result in the coevolved populations exhibiting contrary choices and, as a result, promote ecological stability.     

克隆和有性亲体效应及其调控机制

植物表型受自身基因型、所处环境及其亲体所经历环境的共同影响;其中,亲体环境对子代表型的影响被称为亲体效应。亲体效应不仅可通过有性繁殖产生的种子传递给后代(即有性亲体效应),也可以通过克隆生长等无性繁殖产生的分株传递给后代(即克隆亲体效应)。亲体效应对植物种群,特别是对有性繁殖受限、缺乏遗传变异的克隆植物种群的长期进化可能发挥着极其重要的作用,因此,对亲体效应研究进展的梳理非常必要。对克隆亲体效应和有性亲体效应的内涵进行了阐释,并论述了克隆和有性亲体效应对子代表型、适合度、种内/种间竞争能力以及种群/群落结构和功能的潜在影响;阐述了亲体效应的潜在调控机制,包括供给机制、代谢物质调控机制、表观遗传机制等;论述了克隆亲体效应在克隆植物适应进化中的作用。未来可以就克隆亲体效应的遗传稳定性及其对克隆生活史性状变异的贡献程度,以及克隆和有性亲体效应引起的表型多样性对种内/种间关系、种群/群落多样性及生态系统结构、功能和稳定性的影响开展深入研究。