Results of a cytogenetic study of populations with different radiation risks in the Semipalatinsk region

A cytogenetic study was conducted for the first time on human populations neighboring the Semipalatinsk nuclear test site (STS) and exposed to ionizing radiation for a long period of time. In populations with the extreme and maximum radiation risks, high frequencies of radiation-induced chromosomal markers, including acentric fragments (1.99 +/- 0.10 per 100 cells), dicentrics (0.23 +/- 0.01), ring chromosomes (0.38 +/- 0.14), and stable chromosomal aberrations (1.17 +/- 0.02), were found. These frequencies significantly exceeded those in control populations. The spectrum of chromosomal aberrations and the frequencies of the aberrations of different types in persons living in the areas with the highest radionuclide contamination confirmed the mutagenic effect of radiation on chromosomes in the human populations studied.     

An Evaluation of Different Methods in Epidemiologic Studies of Radiation Risks

The probability of detecting possible late effects of ionizing radiation in human populations depends on the size of exposure in the study population and on the epidemiologic evaluation method used. This is not only due to the mathematical or statistical properties of the method, but also to the choice of the control population, which may be either external (usually large) or internal (usually not so large). Moreover, the use of a large external control population often results in an increasing influence of selection factors expressing themselves e.g. through the ‘healthy worker’ effect. In this paper three different methods usually employed in follow-up studies are reviewed: the calculation of Standardized Mortality Ratios (SMR), a contingency table analysis based on Person-Years (PY) and the comparison of Cumulative Mean Doses (CMD) within different subcohorts. The methods are illustrated with a simple radiation risk model; nevertheless, most of the conclusions apply to non-radiation risk studies as well. The CMD-method is shown to be heavily selection sensitive.     

Cytogenetic biomonitoring carried out in a village (Dolon) adjacent to the Semipalatinsk nuclear weapon test site

The Semipalatinsk region (Kazakhstan Republic) has been affected by extensive radioactive contamination due to more than 450 nuclear tests of which almost 100 were exploded in the atmosphere. The present results refer to cytogenetic assessments in a study cohort of the population of Dolon, a settlement located on the NE boundary of the nuclear weapon test site, which was exposed to elevated doses of ionising radiation primarily due to the first Soviet nuclear test in 1949. Conventional cytogenetic analyses were carried out on 21 blood samples from individuals (more than 50 years old) living in Dolon since the very beginning of nuclear testing. A matched control group included 20 individuals living in non-contaminated areas. Higher frequencies of chromosome aberrations were found in the Dolon cohort compared to the control group, even though they remain within the range of the background levels reported for large normal human population studies on elderly individuals. Received: 24 May 2000 / Accepted: 1 November 2000     

Analysis of the Genetic Demographic Structure of Rural Populations Neighboring the Semipalatinsk Nuclear Test Site

Rural populations neighboring the Semipalatinsk nuclear test site were used as a model to develop and test an integrated population-genetic approach to analysis of the medical genetic situation and environmental conditions in the areas studied. The contributions of individual factors of population dynamics into the formation of the genetic load were also assessed. The informative values of some genetic markers were estimated. Based on these estimates, a mathematical model was constructed that makes it possible to calculate numerical scores for analysis of the genetic loads in populations differing in environmental exposure.     

Genetic Differentiation in Populations with Different Classes of Individuals

I formulate and analyse a model of population structure with different classes of individuals. These different classes may be age classes, other demographic classes, or different types of habitats homogeneously distributed over a geographical area. The value of population differentiation under an island model of dispersal and the increase of differentiation with geographical distance in one- and two-dimensional "isolation by distance" models are then obtained for a generalization of the FST measure of population structure, as a function of "effective" mutation, migration, and population size parameters. The relevant effective subpopulation size is related to the "mutation effective population size" of a single isolated subpopulation and, in models of age-structured populations, to the inbreeding effective population size.     

Genetic and Cytogenetic Analysis of the ADH Region in DROSOPHILA MELANOGASTER

Eighteen Adh-negative mutations were selected with 1-pentyn-3-ol after feeding of formaldehyde. Twelve of the 18 were shown by cytological and genetic analysis to be deletions. Cytological examination of the deletions allowed us to localize the Adh gene to a region including bands 35B3-5 on the left arm of chromosome 2. The deletions were also used to order known visible loci located near Adh.--The vital loci near Adh were also investigated. A total of 109 lethal mutations were generated with EMS and 33 of these, localized within a region defined by the overlap of two of the deletions, were found to belong to 13 complementation groups. If one includes three other loci known to belong there (el, Adh and Sco) a total of 16 complemetation groups have been identified in the region close to Adh.     

Estimate of Cytogenetic Homeostasis in Natural Populations of Some Small Murid Rodents

Cytogenetic homeostasis in natural populations under natural conditions and anthropogenic stress was estimated according to the frequency of chromosome aberrations in somatic cells for six species of small mammals. Cytogenetic homeostasis was disturbed under the stress effect of increased density during population cycles, at the ecological periphery, and in the case of environmental chemical and radiation contamination. Cytogenetic homeostasis disturbances were related to changes in other indices of homeostasis, such as developmental stability and immune status, suggesting the use of the cytogenetic approach for estimating the general state of individuals in natural populations.     

Reconstructing the History of Mesoamerican Populations through the Study of the Mitochondrial DNA Control Region

The study of genetic information can reveal a reconstruction of human population’s history. We sequenced the entire mtDNA control region (positions 16.024 to 576 following Cambridge Reference Sequence, CRS) of 605 individuals from seven Mesoamerican indigenous groups and one Aridoamerican from the Greater Southwest previously defined, all of them in present Mexico. Samples were collected directly from the indigenous populations, the application of an individual survey made it possible to remove related or with other origins samples. Diversity indices and demographic estimates were calculated. Also AMOVAs were calculated according to different criteria. An MDS plot, based on FST distances, was also built. We carried out the construction of individual networks for the four Amerindian haplogroups detected. Finally, barrier software was applied to detect genetic boundaries among populations. The results suggest: a common origin of the indigenous groups; a small degree of European admixture; and inter-ethnic gene flow. The process of Mesoamerica’s human settlement took place quickly influenced by the region’s orography, which development of genetic and cultural differences facilitated. We find the existence of genetic structure is related to the region’s geography, rather than to cultural parameters, such as language. The human population gradually became fragmented, though they remained relatively isolated, and differentiated due to small population sizes and different survival strategies. Genetic differences were detected between Aridoamerica and Mesoamerica, which can be subdivided into “East”, “Center”, “West” and “Southeast”. The fragmentation process occurred mainly during the Mesoamerican Pre-Classic period, with the Otomí being one of the oldest groups. With an increased number of populations studied adding previously published data, there is no change in the conclusions, although significant genetic heterogeneity can be detected in Pima and Huichol groups. This result may be explained because populations historically assigned as belonging to the same group were, in fact, different indigenous populations.     

Polymorphism of the Noncoding Region of the Mitochondrial Genome in Three Kazakh Populations Inhabiting Different Areas of Kazakhstan and in DNA Samples from Ancient Populations of the Kazakhstani Altai

The polymorphism of the major noncoding region of mitochondrial DNA (mtDNA D loop, 528 bp) has been studied in samples from three modern Kazakh populations (from Almaty, the Semipalatinsk Region, and the Altai Mountains) and in DNA samples of ancient human populations of the Kazakhstani Altai. Polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis for 13 restriction sites, including BamHI, EcoRV, Sau3AI (one site each), KpnI (two sites), HaeIII (three sites), and RsaI (five sites) were used. The frequency distributions of all sites have been determined. The gene diversity (h) and the genetic distances between different Kazakh populations and other populations of the world have been calculated. The RFLP analysis of the mtDNA control region of fossil samples has been performed similarly to the analysis of modern mtDNA samples. Two fossil mtDNA samples from burial mound 11 are monomorphic with respect to all restriction sites analyzed.     

柠条锦鸡儿不同居群形态变异研究

结合数量统计方法对柠条锦鸡儿12个居群的12项形态特征进行了研究。结果表明：除小叶对数、叶形和荚果长外,其余形态性状在居群内或居群间都表现显著差异;以12个形态性状为基础的聚类分析将所研究的12个居群分为3类;主成分分析结果显示每荚种子、干粒重、托叶长和叶长等4个性状是造成柠条锦鸡儿表型差异的主要因素。     

不同居群野生早樱形态变异研究

利用数量分类学手段对福建武夷山和江苏宝华山不同居群野生早樱形态特征进行了比较研究。通过对2大居群24项形态指标的分析,不论是聚类分析还是主成分分析,2大居群的各个个体均归并为2类,自然体现出不同居群野生早樱表型特征的较大差异。主成分分析显示,叶部特征的长度、宽度、叶基夹角等,以及花部特征的花萼筒、花冠幅、花序总梗等是造成不同居群野生早樱表型差异的主要因素,单因素方差分析也印证了这一结论。最后,建议在分类学关系上将福建武夷山野生早樱做为大叶早樱新变种处理。     

200对孕期夫妇产前细胞遗传学检查

对象、方法与结果 1989年4-12月,对南京市城区200对来院建卡的孕妇及其配偶,取外周血制备染色体,G显带分析,每例计数39个中期分裂相,分析3个核型.200对夫妇中发现6对夫妇之一方染色体异常(见表1).其余196对核型正常。对该6例的子女进了随访及染色体分析,结果见表1。     

Radiation techniques used in patients with breast cancer: Results of a survey in Spain

AimTo evaluate the resources and techniques used in the irradiation of patients with breast cancer after lumpectomy or mastectomy and the status of implementation of new techniques and therapeutic schedules in our country.BackgroundThe demand for cancer care has increased among the Spanish population, as long as cancer treatment innovations have proliferated. Radiation therapy in breast cancer has evolved exponentially in recent years with the implementation of three-dimensional conformal radiotherapy, intensity modulated radiotherapy, image guided radiotherapy and hypofractionation.Material and MethodsAn original survey questionnaire was sent to institutions participating in the SEOR-Mama group (GEORM). In total, the standards of practice in 969 patients with breast cancer after surgery were evaluated.ResultsThe response rate was 70% (28/40 centers). In 98.5% of cases 3D conformal treatment was used. All the institutions employed CT-based planning treatment. Boost was performed in 56.4% of patients: electrons in 59.8%, photons in 23.7% and HDR brachytherapy in 8.8%. Fractionation was standard in 93.1% of patients. Supine position was the most frequent. Only 3 centers used prone position. The common organs of risk delimited were: homolateral lung (80.8%) and heart (80.8%). In 84% histograms were used. An 80.8% of the centers used isocentric technique. In 62.5% asymmetric fields were employed. CTV was delimited in 46.2%, PTV in 65% and both in 38.5%. A 65% of the centers checked with portal films. IMRT and hypofractionation were used in 1% and in 5.5% respectively.ConclusionIn most of centers, 3D conformal treatment and CT-based planning treatment were used. IMRT and hypofractionation are currently poorly implemented in Spain.     

Cytogenetic Approach to Estimation of Developmental Stability of the Natural Populations of Coregonid Fish

A comparative cytogenetic analysis of Coregonid fish was carried out in the river and lake ecosystems of the northern Tyumen' District. The occurrence of chromosomal aberrations in embryonic cells of fish steadily increased during the period from 1989 until 2001. Possible causes of this dynamic are discussed.     

Bacterial Populations Associated with Different Regions of the Human Colon Wall

The microorganisms associated with the undiseased human colon wall were examined in material obtained from four sudden-death victims. In traffic accident subjects (aged 45 and 16 years) the anaerobe-aerobe ratio was about 10⁴:1 in all areas of the colon examined, whereas in acute heart failure subjects (aged 74 and 46 years) the ratio was as low as 1.2:1. The flora of each individual was distinct and complex. Although the predominant anaerobes isolated were Bacteroides and Fusobacterium spp., which composed over 50% of the flora in some samples, the species isolated (indicated by morphology and glucose fermentation products) varied between individuals. Other major types observed were gram-positive nonsporing rods, including Bifidobacterium spp., and anaerobic cocci (between 8 and 20% of isolates). Clostridia were only isolated in significant numbers from one individual. Scanning electron microscopy showed that most of the organisms were present below the top surface of the mucin layer overlying the mucosa. The use of several different preparative procedures for microscopy showed a complex microbial structure within the mucus, but major variations in the bacterial populations in different areas of the colon were not found. Spiral-shaped organisms up to 60 μm long in the form of double helices were found in two subjects by scanning electron microscopy but were not isolated during the parallel bacteriological investigation. The differences between this and previous studies are discussed in relation to experimental procedures and also in contrast to results with animals that showed a particularly specialized flora associated with the colon wall.     

Variation in Body Shape across Species and Populations in a Radiation of Diaptomid Copepods

Inter and intra-population variation in morphological traits, such as body size and shape, provides important insights into the ecological importance of individual natural populations. The radiation of Diaptomid species (~400 species) has apparently produced little morphological differentiation other than those in secondary sexual characteristics, suggesting sexual, rather than ecological, selection has driven speciation. This evolutionary history suggests that species, and conspecific populations, would be ecologically redundant but recent work found contrasting ecosystem effects among both species and populations. This study provides the first quantification of shape variation among species, populations, and/or sexes (beyond taxonomic illustrations and body size measurements) to gain insight into the ecological differentiation of Diaptomids. Here we quantify the shape of five Diaptomid species (family Diaptomidae) from four populations each, using morphometric landmarks on the prosome, urosome, and antennae. We partition morphological variation among species, populations, and sexes, and test for phenotype-by-environment correlations to reveal possible functional consequences of shape variation. We found that intraspecific variation was 18-35% as large as interspecific variation across all measured traits. Interspecific variation in body size and relative antennae length, the two traits showing significant sexual dimorphism, were correlated with lake size and geographic location suggesting some niche differentiation between species. Observed relationships between intraspecific morphological variation and the environment suggest that divergent selection in contrasting lakes might contribute to shape differences among local populations, but confirming this requires further analyses. Our results show that although Diaptomid species differ in their reproductive traits, they also differ in other morphological traits that might indicate ecological differences among species and populations.