Dynamics of the genetic demographic structure of the Kursk province population: migration processes

Marriage records from parish books of the second half of the 19th century and marriage records of 1967-1970 and 1993-1995 obtained from registry offices were used to analyze the dynamics of genetically significant parameters of migration and marriage structure with respect to spouses' birthplaces in populations of different hierarchical levels in the Kursk oblast. It was found that, among the persons contracting marriage (both males and females), the proportions of those who were born in the same population and those who were born in any population of the Kursk oblast decreased by about one third and one fifth, respectively, for the 130-year period. In rural and small urban populations, the coefficients of marriage migration in the 19th century were an order of magnitude lower than in the 20th century. The immigration to urban populations was maximum in the late 1960s (m = 0.745 in small towns and m = 0.680 in Kursk), and that to rural populations, in the 1990s (m = 0.344). In both urban and rural populations, the mean distance between the spouses' birthplaces has increased by several times for the period studied. The endogamy level has decreased approximately twofold: from 0.797 to 0.380 in Kursk, from 0.897 to 0.419 in small towns, and from 0.958 to 0.440 in rural districts. The marriage assortativeness with respect to birthplace was maximum in the late 19th century (K = 0.393-0.491) and minimum in the 1960s (K = 0.155-0.246). The increase in genetic diversity of the urban population of the Kursk oblast due to migration has been slowing down since the late 20th century, whereas the outbreeding level is still increasing in rural populations.     

A field test of the audibility of urban versus rural songs in mountain chickadees

Anthropogenic noise can mask avian vocalizations, and several urban‐dwelling species adjust frequency or amplitude of vocalizations in ways that appear to compensate for increased noise levels. Playback studies have investigated whether receivers differentiate between signals produced by rural and urban males, but it is difficult to determine whether differential response to stimulus reflects differences in audibility versus perceived differences in male signals/condition that result from urban settlement. Here, we performed paired‐playback trials to determine whether mountain chickadees (Poecile gambeli) differentiate urban versus rural songs when both stimuli were broadcast within noise. For each playback, stimuli were played in short bouts starting at a low signal‐to‐noise ratio and increasing in relative amplitude with each successive bout. If the primary function of adjusted urban songs is propagation in noise, we hypothesized that focal males would respond sooner to urban versus rural playbacks (detect at lower signal‐to‐noise ratios). If urban songs solely encode information about the male's condition (such as increased aggression), then we predicted only a differential aggressive response to playbacks once detected. If urban songs both increase propagation and embed information on male condition, we predicted a combination of both response types. We found no difference in latency to first response in urban versus rural songs, but some evidence for differential aggression to playback dependent on both stimulus type (urban vs. rural) and local ambient noise levels; focal males in noisy (urban) sites responded aggressively to both stimulus types, whereas focal males in quiet (rural) sites responded more aggressively to urban than to rural stimuli. This context‐dependent discrimination may be the result of increased aggression in urban habitats, improved communication in noisy habitats by urban signallers and receivers, or some combination of the two.     

Genetic analysis of the mating system and opportunity for sexual selection in northern water snakes (Nerodia sipedon)

We used data collected over 3 years at two study sites to quantifythe rates and consequences of multiple paternity and to determinethe opportunity for selection on male and female northern watersnakes (Nerodia sipedon). We sampled litters from 45 femalesthat gave birth to 811 offspring. Using eight microsatelliteDNA loci (probability of exclusion of nonparental males >0.99), we assigned paternity to 93% of neonates from one studypopulation and 69% of neonates from the other population. Observationsof participation in mating aggregations predicted individual reproductive success poorly for two reasons. First, males regularlycourted nonreproductive females. Second, more than half ofall sexually mature males obtained no reproductive successeach year, despite the fact that many of them participatedin mating aggregations. The number of sires per litter ranged from one to five, with 58% of all litters sired by more thanone male. Multiple paternity increased with female size, apparentlyboth because bigger females mated with more males and becausethe larger litters of big females provide paternity opportunitiesto more males. Multiple paternity was also more prevalent inyears with shorter mating seasons. We detected no advantage to multiple paternity in reducing either the number of unfertilizedovules or stillborn young. Despite the majority of males siringno young each year, some males fathered young with as manyas three different females in one year. Male reproductive successincreased by more than 10 offspring for each additional mate,whereas female success increased by fewer than 2 offspring foreach additional mate. The opportunity for sexual selectionwas more than five times higher in males than females.     

The prevalence of head louse infestation among urban and rural children in Korea

The prevalence of head louse (Pediculus hamanus var. capitis) infestation in preschool and school children in 9 urban and 8 rural areas of Korea, was investigated. Of 11,865 children who were examined for head lice and nits, 2,900(24.4%) were found infested. The over-all infestation rate of rural children, 58.9%, was higher than that of urban children, 14.4%. There also existed significant differences in the infestation rate among various regions of urban as well as rural areas. Females were more infested than males. But there was no differences in infestation rate in either sex of preschool age. The infestation rate increased gradually from the age of 6, reached a plateau between 9-12 years of age and thereafter slowly decreased. The infestation rate of an orphanage children was higher than that of general childhood population. Health education and mass-delousing attempt are urgently required to lower such a high prevalence of head louse infestation in Korea.     

Genetic structure in urban and rural populations of Apodemus agrarius in Poland

The aims of this study were (i) to determine the genetic variability of the striped field mouse (Apodemus agrarius Pallas, 1771) population in the area of the Warsaw conurbation and the genetic differentiation among local populations of this species within the city, and (ii) to examine the influence of the degree of isolation on the appearance of such genetic structure. Comparison of the genetic structure of the urban population with that of populations inhabiting rural areas was intended to shed light on the depth of genetic changes in this species caused by life in an urban environment. Eight microsatellite loci were used for genotyping and these molecular analyses were successfully performed for 269 individuals. Genetic differentiation (F_ST) was much higher in the case of the urban population. STRUCTURE analysis indicated that this population was subdivided into several local populations, whereas for the rural locations, the highest likelihood was for a single genetic group (one genetically unstructured population). Moreover, in contrast to the rural population, we found no isolation by distance in the urban population. Despite clear subdivision of the urban population, the level of genetic variability was very similar in both analyzed groups. Our findings indicate the occurrence of an advanced process of differentiation of the urban population by microevolution, whereas populations from rural locations displayed very small and mainly insignificant genetic differentiation. Urban local populations, situated near the city borders or close to the natural ecological corridor (banks of the Vistula River), showed higher genetic variability and were less differentiated from populations inhabiting rural sites than from local populations in the city centre. These results provide support for the importance of ecological corridors in preserving the genetic variability of the urban striped field mouse population.     

Reasons for extraction of permanent teeth in urban and rural populations of Croatia

The survey aimed to determine the reasons for extraction of permanent teeth by general dental practitioners in urban and rural population of the Senj region, Adriatic coast, Croatia. During a two-year period (1998-9), a total of 2006 teeth were extracted in both regions, in patients aged 15+. The causes were defined as follows: (1) decay or root without a crown (radix relicta), (2) periodontal disease, (3) endodontic or periapical diseases and (4) other reasons--orthodontics/prosthodontics and dental trauma. The statistical Chi-square-test was used to determine the significant difference between the populations and the sexes. Dental caries was the most frequent cause for extraction (over 50%), followed by endodontic and periapical diseases (23%) as the result of untreated caries and at the end periodontal disease (21%). Urban population more often lose teeth due to periodontal disease (22.75%) than rural (18.93%, p < 0.05). Similarly, this is more frequent in the urban male population (25.61%) than the female urban population (20%, p < 0.05). In rural areas, people more often lost teeth as a result of endodontic and periapical disease (25.85%) than in the urban locations (19.07%, p < 0.01) and this is more frequent in women from rural areas (28.37%) than the rural men (22.44%, p < 0.05). Periodontal disease was not the main cause of tooth loss in either the rural or the urban population. Dental caries and its sequel remain the most important challenge for the dental service. It also reveals the inadequacy of dental services. Education of both the population and the general dental practitioners must be conducted in order to improve oral hygiene and to insist on conservative rather than extraction therapy.     

Socio-economic transition, inequality, and mortality in Lithuania.

The study assessed inequalities in mortality of Lithuanian urban and rural populations throughout the period of socio-economic transition (1990-2000). Mortality from major causes of death, except cancers in females, was higher among the rural population. Inequality in mortality increased during the period of transition, especially among males, mainly due to more rapidly improving health of the urban population. Cardiovascular diseases and external causes made the largest contribution to the inequality. Differences in mortality of urban and rural populations point to greater social and psychological stress affecting the rural population, unhealthy life styles, inequities in accessibility of health care and lack of preventive programs in rural areas.     

Social life factors affecting the mortality, longevity, and birth rate of total Japanese population: effects of rapid industrialization and urbanization

To expand upon the findings that lower mortality was found in Japanese urban areas in contrast to the Western model where in the US and Britain the risk of death was higher in metropolitan areas and conurbations, 22 social life indicators are examined among 46 prefectures in Japan in terms of their effect on age specific mortality, life expectancy, and age adjusted marriage, divorce, and birth rates. The effects of these factors on age adjusted mortality for 8 major working and nonworking male populations, where also analyzed. The 22 social life factors were selected from among 227 indicators in the system of Statistical Indicators on Life. Factor analysis was used to classify the indicators into 8 groups of factors for 1970 and 7 for 1975. Factors 1-3 for both years were rural or urban residence, low income and unemployment, and prefectural age distribution. The 4th for 1970 was home help for the elderly and for 1975, social mobility. The social life indicators were classified form 1 to 8 as rural residence in 1970 and 1975, urban residence, low income, high employment, old age, young age, social mobility, and home help for the elderly which moved from 8th place in 1970 to 1st in 1975. Between 1960-75, rapid urbanization took place with the proportion of farmers, fishermen, and workers declining from 43% in 1960 to 19% in 1975. The results of stepwise regression analysis indicate a positive relationship of urban residence with mortality of men and women except school-aged and middle-aged women, and the working populations, as well as life expectancy at birth for males and females and ages 20 and 40 years for males. Rural residence was positively associated with the male marriage rate, whereas the marriage rate for females was affected by industrialization and urbanization. High employment and social mobility were positively related to the female marriage rate. Low income was positively related to the divorce rate for males and females. Rural residence and high employment were positively related to the birth rate. The birth rate is higher in rural areas. Mortality of professional, engineering, and administrative workers was slightly lower than the total working population, while sales workers, those in farming, fishing, and forestry, and in personal and domestic service had significantly higher mortality. The mortality of the nonworking population was 6-8 times higher than sales, transportation, and communication, and personal and domestic service as well as the total population.     

Survival and Cause-Specific Mortality of Red Foxes in Agricultural and Urban Areas of Illinois

Abstract: Range expansion and population increase by coyotes (Canis latrans), reduced hunting and trapping, and intensified agricultural practices in the Midwest have altered red fox (Vulpes vulpes) mortality, although relative impacts of these factors are unknown. We examined mortality causes and survival of red foxes in urban and rural agricultural areas of Illinois, using radio telemetry data from 335 foxes (Nov 1996 to May 2002). We used Akaike's Information Criterion to evaluate six survival models for foxes reflecting 1) environmental effects, 2) intrinsic effects, 3) temporal effects, 4) behavioral effects, 5) social effects, and 6) a global model. Environmental and intrinsic models of survival were optimal for adult foxes. Adult foxes with low (0-20%) and high (80-100%) percentages of row crops in their home ranges had higher survival than adults with moderate percentages (40-70%). Heavier adults at capture also survived better. A global model (all covariates) was optimal for juvenile foxes. Higher juvenile survival associated with larger litters, lower body fat, and reduced dispersal time. Yearly survival ranged from 0.18 for rural male juveniles to 0.44 for rural female adults. Adult survival rates (0.35) were 11% higher than juvenile survival rates (0.24). Yearly survival varied for urban foxes due to cyclic outbreaks of sarcoptic mange (Sarcoptes scabei). Thus, summer survival (May-Sep) of urban juveniles ranged from 0.10 (mange present) to 0.83 (no mange recorded). Mange was the most common (45% of all fatalities) source of mortality for urban foxes, followed by road kill (31%). We recorded only 4 mange fatalities (2%) for rural foxes. Rural foxes experienced low hunting mortality (7%) and equivalent road kill and coyote predation fatalities (40% each). Sources of mortality for midwestern foxes have dramatically changed since the 1970s when hunting was the major cause of mortality. Coyote predation has effectively replaced hunting mortality, and cyclic patterns of mange outbreaks in urban fox populations might indicate a dynamic source or sink relationship to surrounding rural fox populations. Absent mange, urban areas might provide refugia for red foxes where coyote populations persist at high densities in rural areas. Managers of sympatric urban and rural wildlife populations must understand survival dynamics influencing the population at the landscape level.     

DNA fingerprinting reveals polygyny in the subterranean rodent Ctenomys talarum

DNA fingerprinting was used to characterize patterns of paternity in two populations of Ctenomys talarum from Buenos Aires Province, Argentina. The multilocus probe PV47-2 was used to detect variation in genomic DNA extracted from 12 females, their 32 offspring, and 14 putative sires. For 11 out of 12 litters examined, a single male capable of providing all nonmaternal bands was identified. Within each study population, individual males sired more than one litter, suggesting that C. talarum is polygynous. No evidence of multiple paternity of litters was found. High band-sharing values among females suggest that further research is needed to assess the population genetic structure of this species.     

Prevalence of flea infestation in dogs and cats in Hungary combined with a survey of owner awareness

A survey was conducted in order to gain current information on flea species (Siphonaptera: Pulicidae) infesting dogs and cats living in urban and rural areas of Hungary, along with data on the factors that affect the presence, distribution and seasonality of infestation. In addition, owner awareness of flea infestation was evaluated. Practitioners in 13 veterinary clinics were asked to examine all dogs and cats attending the clinic and to collect fleas, when present, on 2 days in each month from December 2005 to November 2006. They also completed a questionnaire for each animal examined. A total of 319 dogs (14.1%) were found to be infested; the highest prevalence (27.1%) of infestation on dogs occurred in August and the lowest (5.4%) in May. Prevalence of fleas on cats was higher (22.9%); the highest (35.0%) and lowest (8.1%) prevalences occurred in July and April, respectively. Fleas were more prevalent in rural (387/1924 animals, 20.2%) than in urban (161/1343 animals, 12.0%) areas. Three species, Ctenocephalides felis (Bouché), Ctenocephalides canis (Curtis) and Pulex irritans L., were found. On dogs, the prevalence of C. canis alone was 53.0%, whereas that of C. felis alone was 36.0%. Only 19 specimens of P. irritans were found on 14 dogs from rural habitats only. Prevalence of C. felis only on cats was 94.3%; the remaining cats were infested with either C. canis or with mixed infestations of C. felis and C. canis. More than half (51.4%) of the owners of infested dogs and cats had not used flea control products in the past year or more, and five times as many owners in rural than urban areas had not used flea control products in the same period. Very few owners reported having attempted to kill fleas in their animals' environment; instead, they believed that fleas were acquired from other cats or dogs.     

Dynamics of the Genetic Demographic Structure of the Kursk Oblast Population: Migration Processes

Marriage records from parish books of the second half of the 19th century and marriage records of 1967–1970 and 1993–1995 obtained from registry offices were used to analyze the dynamics of genetically significant parameters of migration and marriage structure with respect to spouses' birthplaces in populations of different hierarchical levels in the Kursk oblast. It was found that, among the persons contracting marriage (both males and females), the proportions of those who were born in the same population and those who were born in any population of the Kursk oblast decreased by about one third and one fifth, respectively, for the 130-year period. In rural and small urban populations, the coefficients of marriage migration in the 19th century were an order of magnitude lower than in the 20th century. The immigration to urban populations was maximum in the late 1960s (m = 0.745 in small towns and m = 0.680 in Kursk), and that to rural populations, in the 1990s (m = 0.344). In both urban and rural populations, the mean distance between the spouses" birthplaces has increased by several times for the period studied. The endogamy level has decreased approximately twofold: from 0.797 to 0.380 in Kursk, from 0.897 to 0.419 in small towns, and from 0.958 to 0.440 in rural districts. The marriage assortativeness with respect to birthplace was maximum in the late 19th century (K = 0.393–0.491) and minimum in the 1960s (K= 0.155–0.246). The increase in genetic diversity of the urban population of the Kursk oblast due to migration has been slowing down since the late 20th century, whereas the outbreeding level is still increasing in rural populations.     

Correlation between polymorphic variants of the genes for transferrin and angiotensin-converting enzyme and antioxidant activity of blood plasma

In 75 male and 46 female subjects of an urban population (93% Russians) and in 38 males and 40 females of a rural population (87% Russians), the antioxidant activity (AOA) of blood plasma was determined from the plasma ability to reduce the yield of products interacting with thiobarbituric acid in the model lecithin-Fe2+ ion system. In the urban population, the loci TF (AvaI in exon5) and ACE (I/D polymorphism of the Alu repeat in intron16) were studied in 130 and 141 subjects, respectively. Of them, 102 and 111 subjects, respectively, were examined for AOA. In the rural population, the corresponding sample sizes were 75 and 76 (73 and 74 subjects were examined for AOA). The polymorphic loci of the urban and rural populations did not differ in the allele frequencies. In both populations Hardy--Weinberg and gametic equilibria were observed. The contributions of the TF and ACE genes to AOA variation in the combined sample from the urban and rural populations were 0.6 and 0.5%, respectively.     

Blood pressure trends and hypertension among rural and urban Jat women of Haryana, India

Hypertension is an important public health problem and the major causes of cardiovascular morbidity and mortality among aged and elderly population in India. The present study is an attempt to assess age related trends of blood pressure and prevalence of hypertension in rural and urban women as well as correlation of blood pressure with obesity indicators (WC, BMI, and WHR). Data for present cross-sectional study were collected by purposive sampling method from six hundred Jat women (300 rural and 300 urban), aged 40 to 70 years. Karl Pearson's correlation coefficient (r) was employed to find the relationship between blood pressure and obesity indicators. The results revealed an age associated increase in mean values of systolic and diastolic blood pressure in rural and urban women. Urban women showed significantly higher overall mean value of systolic (mm of Hg) (133.93 vs. 130.79, p < 0.001), diastolic blood pressure (mm of Hg) (84.34 vs. 82.81, p < 0.01) and pulse rate (81.72 +/- 6.27 vs. 80.94 +/- 9.06, p > 0.05) as compared to rural women. The overall prevalence of hypertension was found to be 9% in rural and 26.66% in urban women as per JNC VII criteria. Increased prominence of hypertension among urban Jat women may be attributed to their modern lifestyle having more stress, less manual work and faulty dietary habits. There was a very low awareness of hypertension in the rural subjects (37%) than their urban (72%) counterparts. Rural and urban women revealed a positive and significant association of systolic blood pressure with body mass index, whereas only urban women displayed positive correlation of waist circumference with systolic (r = 0.183**) and diastolic (r = 0.151**) blood pressure.     

Growth in an English population from the Industrial Revolution

The rapid urbanization of the Industrial Revolution in 18th-19th century England presented new health challenges. Our aim is to investigate using English skeletal remains whether the living conditions for an urban working class group in the Industrial Revolution negatively impacted upon their skeletal growth compared with a population from a rural agrarian parish. The Industrial Revolution skeletal material is from St Martin's Churchyard, Birmingham (SMB), West Midlands. It dates primarily from the first half of the nineteenth century when Birmingham was a major manufacturing center. The rural group is from Wharram Percy (WP), North Yorkshire, and dates from 10th-19th century AD. The methodology involves plotting diaphyseal bone lengths versus dental age for subadults. No overall difference was found between the two populations in bone length-for-age among the 2- to 18-year cohort. However the younger parts of the SMB cohort were smaller than at WP; the opposite was true of the older parts of the cohort. Growth rate, as inferred from crosssectional data, appeared greater at SMB than at WP. The only result consistent with expectations is the larger bone dimensions in young children from WP, but this likely reflects prolonged breastfeeding at WP not differences in urban and rural environments. That the deleterious health effects that we know accompanied the major transition in human society from a rural agrarian to an urban industrialized living environment should be little manifest in skeletal endochondral growth data is discouraging for those who would use such methodology to monitor health in earlier populations.     

Land-use selection by dandelions in the Tokyo metropolitan area,Japan

Land use by native and introduced dandelion groups in man-made habitats was studied at 7090 survey points in the Tokyo metropolitan area, Japan, in order to clarify the replacement phenomenon occurring among dandelions. In the center of Tokyo, where the native group was rare, the percentage occurrence of the introduced group was lower than in other regions, whereas in the outskirts of Tokyo, both groups showed much higher occurrence. Roadsides, vacant areas and urban land-use categories were significantly favorable for growth of the introduced group, whereas preserved or rural land use was more favorable for the native group. Seed fertility in the introduced group was more than 80%, and was independent of population size, whereas in the native group it was not as high, and for a small population was dependent on population size, being stable at about 70% in populations larger than 70 plants. Thus, both large populations and solitary plants in the introduced group appeared to act as seed sources, making it likely that the introduced group will spread increasingly through roadsides and urban land, which are becoming more widespread as a result of urbanization. It is feared that, unless deliberately retained, the amount of preserved or rural land which has fostered large populations of the native group will further decrease with urbanization and other forms of development, thus depleting the seed sources and reducing the population.     

Genetic Epidemiological Study of Three District Populations in Chuvashia

Comprehensive population genetic and medical genetic studies were performed in three raions (districts) of Chuvashia. The population of these districts is more than 90% Chuvash. About 70% of the families that completed reproduction had two or three children. The proportion of families with four or more children was 18%. The duration of generation was 27.6 years. The differential fertility and differential mortality indices in the Chuvash population were estimated at 0.33 and 0.076, respectively. The total index of differential selection was 0.403, which is typical of modern urbanized populations. Mean values of local inbreeding calculated from Malecot's model of isolation by distance were 0.00124 and 0.00377 for the urban and rural populations, respectively, of the districts studied. The prevalence rates of autosomal dominant (AD), autosomal recessive (AR), and X-linked diseases were found to be 0.47, 0.52, and 0.35 per 1000, respectively, in the urban population and 1.62, 1.14, and 0.31 per 1000, respectively, in the rural population. Significant correlation between the local inbreeding and prevalence rates of AD and AR diseases was found. A total of 43 AD and 43 AR diseases were identified. Some of them were not found in previous studies on other populations.     

Genetic epidemiological study of populations in three regions of Chuvashia Republic

Comprehensive population genetic and medical genetic studies were performed in three raions (districts) of Chuvashia. The population of these districts is more than 90% Chuvash. About 70% of the families that completed reproduction had two or three children. The proportion of families with four or more children was 18%. The duration of generation was 27.6 years. The differential fertility and differential mortality indices in the Chuvash population were estimated at 0.33 and 0.076, respectively. The total index of differential selection was 0.403, which is typical of modern urbanized populations. Mean values of local inbreeding calculated from Malecot's model of isolation by distance were 0.00124 and 0.00377 for the urban and rural populations, respectively, of the districts studied. The prevalence rates of autosomal dominant (AD), autosomal recessive (AR), and X-linked diseases were found to be 0.47, 0.52, and 0.35 per 1000, respectively, in the urban population and 1.62, 1.14, and 0.31 per 1000, respectively, in the rural population. Significant correlation between the local inbreeding and prevalence rates of AD and AR diseases was found. A total of 43 AD and 43 AR diseases were identified. Some of them were not found in previous studies on other populations.     

Heterogeneity of apolipoprotein E polymorphism in different Mexican populations

Mexico has approximately 100 million inhabitants. Most of the urban Mexican population has been considered mestizo (Indian and Spanish descent), whereas the Indian population predominates in rural areas and small towns in the countryside. In this study we analyzed the apolipoprotein E (APOE) polymorphism in Guadalajara (the second largest metropolitan area of Mexico) and its surrounding areas, two adjoining states (Nayarit and Durango), and an Indian town (Huichol Indians) from western Mexico. APOE*3 was the most common allele, and APOE*3/*3 was the most common genotype in all populations studied. Guadalajara revealed the highest frequency of the APOE*2 allele (7.8%); the frequency decreased in the rural area (4.4%), followed by Nayarit (1.6%), and was absent in Durango and in the Huichols. On the contrary, the lowest frequency of the APOE*4 allele was in Guadalajara (8.4%); the frequency increased in the rural area (9.3%), in Nayarit and Durango (11.5% and 11.7%), and reached a high frequency in the Huichol Indians (28%). The distribution of the APOE allele in the western population of Mexico is similar to those described in Mexican American migrants living in the United States but is different from those populations living in Mexico City. This study shows the heterogeneity of the Mexican population, where the frequency of the APOE*2 allele is higher in Guadalajara than in other urban areas of Mexico and is similar to frequencies described in the Caucasian population. On the contrary, the Huichols revealed the highest frequency of the APOE*4 allele in Mexico and in the Americas. This information could be useful for the study of dyslipidemias associated with chronic diseases and as markers of ethnic variation in the Americas.     

The development of white adipose tissue. Effect of litter size on the lipoprotein lipase activity of four adipose-tissue depots, serum immunoreactive insulin and tissue cellularity during the first year of life in male and female rats.

(1.) Male and female rats reared in litters of four gained body weight more rapidly than animals reared in litters of 16. The differences were more marked in males than females and became less marked in both sexes with advancing age. (2.) The relative weights of the perigenital, perirenal, subcutaneous and intramuscular white-adipose-tissue sites in the animals from small litters indicated their relative obesity compared with animals from large litters. A sex-related difference in the distribution of adipose tissue between the four sites was seen in animals reared in litters of both four and 16. (3.) Although at 30 days of age all the animals had more numerous and larger fat-cells in their white-adipose-tissue depots than animals reared in large litters, the pattern of change thereafter was both site- and sex-specific. During the post-weaning period (30-300 days), although detailed differences were apparent between sites, a general pattern of increased cell size in males and increased cell numbers in females emerged as being the important determinants responsible for the differences in depot sizes seen when animals from litters of four and 16 were compared. (4.) Lipoprotein lipase activities, expressed as units/g fresh wt. of tissue, in the depots of animals reared in groups of four were unaltered compared with those reared in groups of sixteen during the post-weaning period (47-300 days of age), and enzyme activities expressed per depot merely reflected differences in tissue weights. (5.) Lipoprotein lipase activities per 10(6) cells were higher in males reared in fours compared with those reared in sixteens of equivalent age, but were unaltered for females. (6.) The persistent hyperinsulinaemia of animals reared in litters of four is discussed in relation to the observed differences in enzyme activity and white-adipose-tissue cellularity.