Length Of Reproductive Period Research Articles

Identification of Molecular Markers and Candidate Genes Associated with Time to Flowering and Length of Reproductive Period in Soybean Through Association Mapping

Identification of Molecular Markers and Candidate Genes Associated with Time to Flowering and Length of Reproductive Period in Soybean Through Association Mapping

Duration of Reproductive Period and Risk of Transitioning to Mild Cognitive Impairment and Dementia

Decreasing estrogen levels have been hypothesized to be associated with increased risk of dementia, yet the current literature reveals conflicting results. This study aimed to determine whether a longer reproductive period, as an indicator of longer exposure to endogenous estrogens, is associated with risk of transitioning to MCI and dementia. Women 65 and over (N=1507) from the Rush Memory and Aging Project met eligibility for the current analysis. The average length of reproductive period (menopause age minus menarche age) was 35 years (range=16-68 years), and 64% had natural menopause. Multistate survival modeling (MSM) was used to estimate the influence of reproductive period on risk of transitioning through cognitive states including mild cognitive impairment (MCI) and clinically diagnosed dementia, as well as death. Multinomial regression models estimated total and cognitively unimpaired life expectancies based on the transition probabilities estimated by the MSM. Results suggest that women with more reproductive years were less likely to transition from no cognitive impairment (NCI) to MCI, and were more likely to return to NCI from MCI. Analyses also suggest two additional years free of cognitive impairment for women with 45 vs 25 years of reproduction, though reproduction period did not significantly impact overall life expectancy. This study suggests that the number of years of reproductive duration is not associated with the transition to dementia, but is possibly associated with delayed cognitive decline, reduced risk of MCI, increased likelihood of returning to NCI from MCI, and increased lifespan free of cognitive impairment.

Using unsupervised learning techniques to assess interactions among complex traits in soybeans

Soybean yield components and agronomic traits are connected through physiological pathways that impose tradeoffs through genetic and environmental constraints. Our primary aim is to assess the interdependence of soybean traits by using unsupervised machine learning techniques to divide phenotypic associations into environmental and genetic associations. This study was performed on large scale, jointly analyzing 14 quantitative traits in a large multi-parental population designed for genetic studies. We collected phenotypes from 2012 to 2015 from a soybean nested association panel with 40 families of approximately 140 individuals each. Pearson and Spearman correlations measured phenotypic associations. A multivariate mixed linear model provided genotypic and environmental correlations. To evaluate relationships among traits, the study used principal component and undirected graphical models from phenotypic, genotypic, and environmental correlation matrices. Results indicate that high phenotypic correlation occurs when traits display both genetic and environmental correlations. In genetic terms, length of reproductive period, node number, and canopy coverage play important roles in determining yield potential. Optimal grain yield production occurs when the growing environment favors faster canopy closure and extended reproductive length. Environmental associations found among yield components give insight into the nature of yield component compensation. The use of unsupervised learning methods provides a good framework for investigating interactions among various quantitative traits and defining target traits for breeding.

Reproductive history and risk of cognitive impairment in elderly women: a cross-sectional study in eastern China.

Epidemiological studies suggest that proxies of higher lifetime estrogen exposure are associated with better cognitive function in postmenopausal women, but this has not been found consistently. To determine whether reproductive history, an important modifier of estrogen exposure across the lifetime, is associated with risk of cognitive impairment in postmenopausal women. We analyzed the baseline data from Zhejiang Major Public Health Surveillance Program (ZPHS) including 4,796 postmenopausal women. Cognitive impairment was assessed through the application of Mini-Mental State Examination questionnaire. Logistic regression models, controlled for an extensive range of potential confounders, were generated to examine the associations between women's reproductive history and risk of cognitive impairment in their later life. The length of reproductive period was inversely associated with risk of cognitive impairment (p = 0.001). Odds ratio (OR) of cognitive impairment were 1.316 (95% CI 1.095∼1.582) for women with 5 or more times of full-term pregnancies, compared with those with 1∼4 times of full-term pregnancies. Women without incomplete pregnancy had a significant higher risk of cognitive impairment (OR = 1.194, 95% CI 1.000∼1.429), compared with the reference (1∼2 times of incomplete pregnancies). Oral contraceptive use (OR = 0.489, 95% CI 0.263∼0.910) and intrauterine device (IUD) use (OR = 0.684, 95% CI 0.575∼0.815) were associated with significantly reduced risk of cognitive impairment. Our results indicated that shorter reproductive period, higher number of full-term pregnancies and no incomplete pregnancy history were associated with an increased risk of cognitive impairment. In contrast, oral contraceptive and IUD use corresponded to reduced risk of cognitive impairment.

Lifelong Estrogen Exposure and Memory in Older Postmenopausal Women

Menopausal changes in endogenous estrogen have been associated with memory decline. However, because earlier findings regarding the effects of lifelong estrogen exposure on memory have been inconsistent, our purpose was to investigate these effects in older postmenopausal women with a comprehensive battery of memory measures. Participants were 126 nondemented naturally postmenopausal women, not currently using hormone therapy (HT), 60 to 89 years of age, who showed normal to below average verbal memory performance on a screening test. Memory measures included tests of visual, verbal, and working memory. Regression analyses were performed with each memory measure as the outcome and length of reproductive period (time between menarche and menopause) as the predictor, controlling for age, education, parity, duration of breastfeeding, previous HT and oral contraceptive use, as well as body mass index and depression. Longer reproductive period was significantly associated with better delayed visual memory, immediate and delayed verbal memory, and working memory. Previous HT use was also significantly associated with better verbal memory and delayed visual memory. Our findings suggest an enduring protective role of endogenous and exogenous estrogen on memory in older postmenopausal women with normal to below average verbal memory performance on a screening test. They also support our contention that the neuroprotective benefits of a longer reproductive period might only be evident after a longer period of postmenopausal estrogen deprivation, which would help clarify why such an association was not previously found in younger postmenopausal women. Replication is required with a larger sample representing a broader cross-section of the aging female population.

Hot summers, long life: egg laying strategies of Maniola butterflies are affected by geographic provenance rather than adult diet

Maniola butterflies undergo summer dormancy in dry and hot habitats and deposit their eggs only in early autumn when conditions become more favourable for their offspring. Female individuals of this genus are therefore relatively long-lived. For long-lived butterflies adult diet is of particular importance. We tested if added amino acids in nectar substitute fed to the butterflies affected timing of oviposition, fecundity and longevity. A hundred Maniola females were sampled from Mediterranean and Central European populations and made to oviposit under controlled laboratory conditions. Forty individuals were offered sucrose solution with additional amino acids while the remainder were fed with plain sucrose solution. We found that egg-laying strategies and longevity depended on geographic provenance rather than diet. Supplementary amino acids in adult diet did neither prolong lifetime nor increase total egg production. Maniola females from Sardinia started to lay eggs at least 20 days later relative to Central European M. jurtina and lived three times as long. Mediterranean individuals had on average twice the length of reproductive period and lifespan relative to Central European ones, and individuals of Pannonian origin lived longer than Alpine butterflies. Average total egg numbers were 200-350 eggs per female and did not differ significantly between populations. The fact that oviposition strategy could not be altered through diet may indicate that for univoltine butterflies, like Maniola, diet-quality at the adult stage is less important than endogenous factors, or factors the butterflies are exposed to in an earlier developmental stage than the imago. Oviposition strategy closely matched the climatic conditions that prevail in the geographic regions where these butterflies fly.

Life history of the bird cherry-oat aphid, Rhopalosiphum padi (Homoptera: Aphididae), on transgenic and untransformed wheat challenged with barley yellow dwarf virus.

The life history of Rhopalosiphum padi (L.) was monitored on transgenic and untransformed (soft white winter wheat plants that were infected with Barley yellow dwarf virus (BLDV), noninfected, or challenged with virus-free aphids under laboratory conditions. Two transgenic soft white winter wheat genotypes (103.1J and 126.02) derived from the parental variety Lambert and expressing the barley yellow dwarf virus coat protein gene, and two untransformed varieties, virus-susceptible Lambert and virus-tolerant Caldwell, were tested. B. padi nymphal development was significantly longer on the transgenic genotypes infected with BYDV, compared with noninfected transgenic plants. In contrast, nymphal development on Lambert was significantly shorter on BYDV-infected than on noninfected plants. Nymphal development on noninfected Lambert was significantly longer than on noninfected transgenics. No significant difference in nymphal development period was detected between virus-infected and noninfected Caldwell. Aphid total fecundity, length of reproductive period, and intrinsic rate of increase were significantly reduced on BYDV-infected transgenic plants compared with BYDV-infected Lambert. In contrast, reproductive period, total adult fecundity, and intrinsic rate of increase on noninfected Lambert were significantly reduced compared with noninfected transgenics. Transgenic plants infected with BYDV were inferior hosts for R. padi compared with infected Lambert. However, noninfected transgenics were superior hosts for aphids than noninfected Lambert. Moderate resistance to BYDV, as indicated by a significantly lower virus titer, was detected in the transgenic genotypes compared with the untransformed ones. Results show for the first time that transgenic virus resistance in wheat can indirectly influence R. padi life history.

Reproductive period and risk of dementia in postmenopausal women.

Exogenous estrogen use may lower risk of dementia in postmenopausal women. A relationship between long-term exposure to endogenous estrogens and incident dementia has been hypothesized but not studied. To determine whether a longer reproductive period, as an indicator of longer exposure to endogenous estrogens, is associated with lower risk of dementia and Alzheimer disease (AD) in women who have natural menopause. The Rotterdam Study, a population-based prospective cohort study conducted in the Netherlands. A total of 3601 women aged 55 years or older who did not have dementia at baseline (1990-1993) and had information on age at menarche, age at menopause, and type of menopause. Participants were reexamined in 1993-1994 and 1997-1999 and were continuously monitored for development of dementia. Incidence of dementia, based on Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition criteria, and AD, based on National Institute of Neurological Disorders and Stroke/Alzheimer's Disease and Related Disorders Association criteria, compared by quartiles of reproductive period among women with natural menopause. During 21 046 person-years of follow-up (median follow-up, 6.3 years), 199 women developed dementia, including 159 who developed AD. After adjusting for age, dementia was not clearly associated with length of reproductive period. However, after adjusting for multiple covariates, women with natural menopause and more reproductive years had an increased risk of dementia (adjusted rate ratio [RR] for women with >39 reproductive years [highest quartile] compared with <34 reproductive years [lowest quartile], 1.78; 95% confidence interval [CI], 1.12-2.84). The adjusted RR per year of increase was 1.04 (95% CI, 1.01-1.08). For risk of AD, the adjusted RRs were 1.51 (95% CI, 0.91-2.50) and 1.03 (95% CI, 1.00-1.07), respectively. Risk of dementia associated with a longer reproductive period was most pronounced in APOE epsilon4 carriers (adjusted RR for >39 reproductive years compared with <34 reproductive years, 4.20 [95% CI, 1.97-8.92] for dementia and 3.42 [95% CI, 1.51-7.75] for AD), whereas in noncarriers, no clear association with dementia or AD was observed. Our findings do not support the hypothesis that a longer reproductive period reduces risk of dementia in women who have natural menopause.

Reproductive factors and fatal hip fractures. A Norwegian prospective study of 63,000 women.

STUDY OBJECTIVE: The aim of the study was to investigate the impact of reproductive variables (age at menarche, menopause, first and last birth as well as parity, lactation, and abortions)...

Bone mass and risk factors for bone loss in perimenopausal Danish women.

To determine risk factors for low bone mass at menopause and risk factors for subsequent bone loss in the following period. A cross-sectional study and a 2-year prospective follow-up. The catchment area of Sundby Hospital in Copenhagen. Four hundred and thirty-three women aged 45-58 years, with amenorrhea for 3-24 months, of whom 87 were followed for a 2-year period. Registration of life-style and anthropometric variables, reproductive history, and family history of fractures. Total body bone mineral content (BMC) was measured with dual energy X-ray absorptiometry. By means of multiple regression analysis height, body weight, and length of reproductive period were found to be positively related to whole body BMC (P < 0.001), whilst a negative relationship was found to age (P < 0.001), smoking (P < 0.001), and family history of fractures (P < 0.005). In the longitudinal study, only body weight at the inclusion (P = 0.005) and subsequent changes in body weight and fat mass (P < 0.001) were related to the changes in bone mass. The most significant predictors for bone loss were changes in body weight and fat mass. Hence, weight loss is a risk factor for bone loss in the early postmenopausal period, whereas weight gain seems to preserve bone.

Evolution of Longevity in Ungulates and Carnivores

Evolution of maximum lifespan potential (MLP) and its possible relation to the evolution of extra-brain functions are investigated for the ungulates and carnivores. MLP defines a species’ characteristic aging rate and is considered a basic biological property of an organism. It is related to postnatal developmental rate, length of time general vigor is maintained, length of reproductive period, generation time and the time available for learning behavior. In addition to MLP, two other parameters were studied: MLP calorie consumption (MCC) and the <i>Jerison</i> encephalization quotient (EQ). MCC, the product of MLP and specific metabolic rate (SMR), is considered to represent total ‘life-capacity’ of an organism, and EQ the degree of brain development beyond that required for normal body functions. MLP, SMR and MCC were calculated from brain and body weight estimates of fossil and living species for 59 ungulates and 32 carnivores. MLP and MCC were compared to the EQ values previously calculated for these species by <i>Jerison</i>. Mammalian species of the Mesozoic era have low MLP, MCC and EQ values, and those remaining in a Mesozoic-like niche have shown little change over the past 150 million years. However, MLP, MCC and EQ do show a progressive increase along the ancestral-descendant sequence of the horse and camelid over the past 50 million years. Analysis of other ungulates and carnivore species indicates that MLP and MCC have progressively increased on the average, accompanied by a substantial increase in dispersion. Species along an ancestral-descendant sequence known to become extinct (archaic) show little or no increase in these parameters. These results are similar to those reported by <i>Jerison</i> for the EQ of these species and suggest that the co-evolution of MLP, MCC and EQ involved mutually beneficial properties. Increase in MLP may reflect a progressive decrease in mutation rate; and the rapid rate of increase in MLP, MCC and EQ suggests that simple genetic changes (probably of a regulatory nature) are involved. Similar findings for primate species suggest that evolution of longer lifespan, increased metabolic efficiency and increased extra-brain functions represent major characteristics describing the evolutionary success of the mammalian species.

Evolution of longevity in primates

Evolution of maximum lifespan potential ( MLP) and its possible relation to the evolution of extra-brain functions are investigated in the primates. MLP is related to a species' characteristic aging rate and is considered a basic biological property of an organism. MLP may be of more importance than realized in the past in determining the evolutionary success of a species. It is related to the postnatal development rate, the length of time general vigor is maintained, the length of reproductive period, generation time and the time available for learning and teaching behavior. Three other parameters are considered to be importantly related to MLP: MLP calorie consumption ( MCC), encephalization quotient ( EQ) and extra number of cortical neurons ( N c ). MCC is calculated as the product of MLP and specific metabolic rate ( SMR) and is considered to represent total “life-capacity” of an organism. It is of potential value in studying the biological mechanisms involved in the evolution of MLP. Brain function is estimated by the Jerison EQ and N c parameters. These parameters estimate the “extra” brain capacity involved in functions beyond normal body requirements. The rate of change in MLP and N c per unit time occurring during an ancestral-descendant sequence is used to estimate the biological complexity of the genetic processes which have evolved in governing the rate of expression of the general aging process and increasing brain function. The average rate of change of MLP during the emergence of the primates was analyzed by the difference between MLP in closely related living primate species and the evolutionary time of appearance of a common ancestor. MLP, SMR, MCC, EQ and N c were estimated from fossil cranial capacity and body weight measurements. The rate of change in these values was calculated according to the time of appearance of the fossil species. MLP and N c were found to increase together and reached their highest rate of increase approximately 200,000 years ago along the hominid ancestral-descendant sequence leading to modern man. The high rate of increase of these parameters suggests that few genetic changes were responsible. The general increase in MLP during the evolution of the primate species indicates that a corresponding general decrease in mutation rate may have occurred. The high levels of MLP, MCC, EQ and N c represented in the living primates, as compared to other mammals, are considered to represent a major characteristic determining their evolutionary success.

Marriage Patterns in Pakistan through Net Nuptiality Tables-1968 &amp; 1971

In studying the processes which bring about changes in the size and composi¬tion of a population, an appraisal of marriage patterns is of special significance because the age and rate of marriage formation relate directly'to changes in popu¬lation composition. In a society like Pakistan where fertility takes place pre¬dominantly through the formation of families by marriages, the frequency of mar¬riages at different ages has direct bearing on the effective length of reproductive period. Thus, for getting a proper insight into the demographic phenomena, statistics on marriages are also of great interest to demographers along with infor¬mation on fertility, mortality and migration. Studies on frequencies of marriages by age, referred to in the demographic terminology as nuptiality studies, are rather limited in demographic literature, particularly in comparison with studies on fertility and mortality. There are two obvious reasons for relatively low priority given to this subject in spite of due re¬cognition of its importance. Firstly, because of the rapid growth of population since the turn of the century the role of fertility and mortality as direct determinants of growth patterns has been much more significant. As a result, the major interest of researchers has remained focused on the vital events contributing to the natural increase, viz. births and deaths. Secondly, a regular system of marriage registra¬tion is limited to a few countries in the world, and in most of the other countries, such information is either not available or if in some cases it is available, no regular statistics are compiled out of them. The limited availability of statistics on in¬cidence of marriage through vital registration does not imply that information on marriage patterns is not available from other sources. In fact much work has been done on the basis of data on age distribution of population by marital status provided by censuses or surveys.

Resistance in Sorghums to the Greenbug; Laboratory Determination of Mechanisms of Resistance12

Schizaphis graminum (Rondani) displayed differential preference reactions when given a choice of resistant or susceptible sorghums. Resistant lines PI 264453, IS 809, KS 30, and SA 7536-1 were less preferred than susceptible sorghum Tx 2536 and Tx 7000. A similar response was shown for F1 hybrids of susceptible X resistant lines but to a lesser degree. Duration of stadia was increased, whereas progeny per adult, adult longevity, and length of reproductive period were decreased for greenbugs reared on resistant sorghums. Nymphal mortality did not differ in resistant or susceptible sorghums. Honeydew excretion by aphids on resistant sorghums was generally less than on susceptible sorghums, which indicated reduced feeding.

A computer model of family building based on expected values

A computerized probability model of family building is described. Called FERMOD, the model is designed to follow the changing distribution of children ever born and birth intervals of a large homogeneous population as it moves through the reproductive period. Use of the model presupposes assumptions about such factors as risks of fetal wastage, lengths of pregnancy, and postdelivery amenorrhea conditional to outcome of pregnancy, length of reproductive period, fecundability, desired family size, preferred birth spacing!, and effectiveness of contraception. Use of FERMOD is illustrated in a limited application to United States fertility. Relations to other models are briefly discussed.