Consanguinity and congenital heart disease in the rural Arab population in northern Israel

The incidence of congenital heart disease (CHD) was examined in relation to the consanguinity of the parents. The study was performed in five Arab villages in the Western Galilee, Israel, where consanguineous matings are known to be very high. All children up to the age of 7 years were included in this study; there were 1,546 children, 32% were the offspring of consanguineous marriages including first- and second-degree cousins. A higher percentage of isolated CHD was found in the offspring of consanguineous marriages: 2.81% out of 498 children compared to 1.24% in 1,048 offspring of unrelated parents. Among 373 children whose parents were first cousins the percentage of CHD rose to 3.22. The differences in CHD frequencies were found to be statistically significant. CHD is believed to have a multifactorial background. This study shows that the genetic influence is an important factor in the etiology of such malformations.     

Ineffective contraceptive use and its causes in a natural fertility population in southern Jordan

Based on our interview survey of 574 randomly selected married women from a rural population in the South Ghor district, Jordan, where traditional Arab customs have been persistently maintained, in this paper we analyze the age-specific marital fertility rates (ASMFRs) and contraceptive practices, especially the prevalence and duration of contraceptive use. The ASMFRs fitted the natural fertility pattern proposed by Coale and Trussell's model, and the total fertility rate was estimated to be 7.2. Even though the prevalence rate of modern contraceptive methods has reached 14.3%, because of the recent increase among young women in particular, the users had larger numbers of children than the nonusers and the duration of contraceptive use was short, especially at young ages (e.g., about 90% 24-month discontinuation probabilities in 15-19- and 20-24-year-olds). These ineffective contraceptive uses were related to traditional Arab norms, represented by the pooled proportion of "as many as possible" and "up to God" answers to the ideal number of children (70% of men and 30% of women).     

Association between childhood atopic disease and parental atopic disease in a population with high consanguinity

The aim of the study was to investigate the association between asthma, allergic rhinitis, and eczema in Qatari schoolchildren with allergic conditions in their parents. A cross-sectional study was conducted among 3500 Qatari schoolchildren aged 6-14 years in period: February, 2003-February, 2004. A questionnaire was used to collect the clinical history of asthma and allergic rhinitis in their parents and siblings. It was found that 21.6% of asthmatic children had mothers with asthma and 18.2% fathers with asthma. This contrasted with 6.8% of non-asthmatic children who had fathers with asthma and 9.4% mothers with asthma. As for allergic rhinitis, 26.5% of asthmatic children had mothers with allergic rhinitis and 25.3% fathers with allergic rhinitis. The frequency of either parent of the asthmatic children having allergic rhinitis was 41.8% and for both parents was 10.0%. The frequency of siblings having asthma was 36.6%, allergic rhinitis 16.4%, and eczema 29.1%. The present study revealed a strong association between respiratory allergies and eczema in parents, and their asthmatic children.     

Long-lasting effects of sedentarization-induced increase of fertility on labor force proportion in an Arab socieity: a case study in south Jordan

Based on the authors' genealogical-demographic data of a Bedouin-origin clan in south Jordan which settled down in 1948, this paper aimed to report the long-lasting effects of increase in fertility induced by sedentarization on the labor force proportion, defined as percent of persons aged 15-64 years. The results highlighted that this proportion had an inverse relation with the total fertility rate and tended to fluctuate up to the present time with an interval of several decades, suggesting that a Bedouin-origin sedentarized group met alternately with the phase of high fertility and low proportion of labor force and the other phase of an opposite pattern. At present, unemployment of males, who have been engaged in subsistence and cash-earning work, was high especially in younger groups basically due to the narrow land of the clan (only 35 hectares for 456 people in 2005) for agriculture and the limited opportunities for cash-earning jobs. Taking into consideration that Bedouin-origin people sedentarized according to the government policy, it is needed for the government to support rural development plans of sedentarized Bedouin peoples.     

Genomic runs of homozygosity record population history and consanguinity

The human genome is characterised by many runs of homozygous genotypes, where identical haplotypes were inherited from each parent. The length of each run is determined partly by the number of generations since the common ancestor: offspring of cousin marriages have long runs of homozygosity (ROH), while the numerous shorter tracts relate to shared ancestry tens and hundreds of generations ago. Human populations have experienced a wide range of demographic histories and hold diverse cultural attitudes to consanguinity. In a global population dataset, genome-wide analysis of long and shorter ROH allows categorisation of the mainly indigenous populations sampled here into four major groups in which the majority of the population are inferred to have: (a) recent parental relatedness (south and west Asians); (b) shared parental ancestry arising hundreds to thousands of years ago through long term isolation and restricted effective population size (N(e)), but little recent inbreeding (Oceanians); (c) both ancient and recent parental relatedness (Native Americans); and (d) only the background level of shared ancestry relating to continental N(e) (predominantly urban Europeans and East Asians; lowest of all in sub-Saharan African agriculturalists), and the occasional cryptically inbred individual. Moreover, individuals can be positioned along axes representing this demographic historic space. Long runs of homozygosity are therefore a globally widespread and under-appreciated characteristic of our genomes, which record past consanguinity and population isolation and provide a distinctive record of the demographic history of an individual's ancestors. Individual ROH measures will also allow quantification of the disease risk arising from polygenic recessive effects.     

Effects of soil pH and nitrogen fertility on the population dynamics of Thielaviopsis basicola

Black root rot of tobacco, caused by Thielaviopsis basicola, is generally severe at soil pH values >5.6 and suppressed under more acidic conditions (pH < 5.2). Soil acidifying fertilizers containing NH₄–N are generally recommended for burley tobacco production in North Carolina, but the effects of N form and application rate on development of black root rot and on the population dynamics of T. basicola have not been determined. Greenhouse and laboratory studies were conducted to evaluate the effects of N form (NH₄ ⁺ or NO₃ ^–) and rate on pathogen and disease parameters at several initial soil pH levels. A moderately-conducive field soil, initial pH 4.7, was adjusted to a pH of 5.5 or 6.5 by the addition of CaOH₂, then amended with the desired nitrogen form and rate. Pathogen populations were determined over time. In addition, spore production in extracts of roots from plants grown in the various nitrogen and pH treatments was determined. Finally, because tobacco responds to acidic soil conditions and exposure to NH₄–N by accumulating high concentrations of the polyamine putrescine, the toxicity of putrescine on vegetative growth and reproduction of T. basicola was investigated. Low soil pH and high levels of NH₄–N suppressed reproduction of T. basicola in soil and in root extract, while use of NO₃–N and depletion of NH₄–N resulted in rapid increases in populations of T. basicola. At 20 mM, putrescine inhibited hyphal growth by 60% and aleuriospore production by 98%. Fertilizers that reduced soil pH also reduced reproduction by T. basicola, and thus have potential for management of black root rot by suppressing populations of T. basicola over multiple years of crop production. The suppression of T. basicola and black root rot observed with NH₄–N amendments may partially be due to development of an inhibitory environment in the root and not solely to changes in rhizosphere pH.     

Social,biological, and political considerations on fertility in Arab populations

In analyzing fertility in the Arab countries, crude birth rate, total fecundity rate, and age specific fertility rates were measured. The data was obtained from United Nations, UNICEF, and the World Bank. In the early 1980's 13 of the countries had birth rates 40/1000. The majority of countries showed a decline in their crude birth rate (CBR) between 1960-83, except Somalia, which increased. The United Arab Emirates (UAE), Tunisia, Lebanon, and Kuwait, had the largest CBR decreases, followed by Morocco, Egypt, and Saudi Arabia. The global fecundity rate (GFR) shows the number of expected births a woman lives through her reproductive period, having children at the prevailing rate for each age. The GFR in these countries is much higher than those of non Moslem countries in the area. Results show that the fertility of Arab countries are in a gradual decline, but remain high, and many have a CBR over 40/1000. In the last 20 years Saudi Arabia, with the largest population of oil producing countries, has had a decreasing CBR. It is not in agreement with its high GFR, but this can be attributed to the large number of immigration workers in the country. The UAE showed a decrease in CBR from 46/1000 to 27/1000, the largest decrease in these countries. This decline coincided with the economic development due to oil production. Kuwait had a 25.5% decrease in CBR but less than Tunisia and Lebanon. The fertility decline in Kuwait intensified in the middle 1970's; the decline in northern Africa began in the late 1960's. There were declines in birth rates in the North African countries in the early 1970's except for Tunisia. The rapid declines in fertility can be attributed to the countries' socioeconomic and political situations.     

Socioeconomic status and fertility in rural Bangladesh

Using a unique set of birth registration data from the Demographic Surveillance System of the International Center for Diarrheal Disease Research, Bangladesh, for the period 1974-77, and socioeconomic information collected in the 1974 census, fertility was studied in relation to occupation, size of dwelling, number of cows and number of boats owned. The total fertility rate was found to vary between 6 and 6.5 except in the famine year of 1975. There was no consistent relationship between fertility and education of women. The age-specific fertility rates by religion show that Muslims had higher fertility at all ages in 1974 and 1977 and at older ages in 1975 and 1976. Overall, however, fertility of Hindus is consistently lower than that of Muslims, but the relative differences are under 10%. Fertility differentials by occupation showed that the household heads who were farm laborers had relatively lower fertility compared to other occupational groups, except for the year 1977 where the families of service holders were found to have relatively lower fertility. Women in households whose heads were businessmen or farmers (owning their land) had above average fertility. In 1974, households in the business occupational groups had, on average, 1 birth more than other households. Women in households with fishermen as heads had below average fertility in 1974 and 1975, but very high fertility in 1976 and 1977. Fertility levels differed according to the type of household in which the family resided. Nuclear families had below average fertility up to the age of 35 and above average fertility at the end of the reproductive age. In the 15-19 age group, augmented families had higher fertility each year examined. The association between dwelling place and fertility is positive each year, the relative differences in fertility between the groups being largest in 1974. Positive relations were found between economic status and fertility.     

不同土壤培肥措施对华北高产农田生态系统蚯蚓种群的影响

通过在华北高产农田生态系统进行的土壤培肥试验 ,研究了不同秸秆还田方式和施肥措施对土壤大型动物——蚯蚓的影响。研究结果表明 :该区域高肥力土壤共有 7种蚯蚓 ,其中以正蚓科梯形流蚓为主 ,并同时分布巨蚓科的远盲蚓属、腔蚓属和链胃蚓科的杜拉蚓属的一些广布种。全年平均种群密度为 83.83条 /m2 ,最高种群数量出现在 1998年 8月份 ,其季节变化趋势为夏季 >春季 >秋冬季。在投入同量化肥条件下 ,有机物投入越多 ,蚯蚓越丰富 ,其生物量有以下趋势 :化肥投入 <化肥与麦秸还田 <化肥与玉米秸麦秸全还田 <化肥与玉米秸麦秸还田加施有机肥处理。在有有机物投入的条件下 ,化肥对土壤生物的负面效应不明显 ,不会对土壤中的蚯蚓有较大影响 ;而单施化肥 ,对蚯蚓负面影响较为显著。有机肥的施入可以增加蚯蚓的种群数量 ,随着时间的增加这种趋势越明显     

Sexual reproduction and population dynamics: the role of polygyny and demographic sex differences.

Most models of population dynamics do not take sexual reproduction into account (i.e., they do not consider the role of males). However, assumptions behind this practice--that no demographic sex differences exist and males are always abundant enough to fertilize all the females--are usually not justified in natural populations. On the contrary, demographic sex differences are common, especially in polygynous species. Previous models that consider sexual reproduction report a stabilizing effect through mixing of different genotypes, thus suggesting a decrease in the propensity for complex of dynamics in sexually reproducing populations. Here we show that considering the direct role of males in reproduction and density dependence leads to the conclusion that a two-sex model is not necessarily more stable compared with the corresponding one-sex model. Although solutions exist where sexual reproduction has a stabilizing effect even when no genotypic variability is included (primarily when associated with monogamy), factors like polygyny, sex differences in survival or density dependence, and possible alterations of the primary sex ratio (the Trivers-Willard mechanism), may enlarge the parametric region of complex dynamics. Sexual reproduction therefore does not necessarily increase the stability of population dynamics and can have destabilizing effects, at least in species with complicated mating systems and sexual dimorphism.