Timing Of Reproduction Research Articles

Precocious Sperm Exchange in the Simultaneously Hermaphroditic Nudibranch, Berghia stephanieae.

SynopsisSexual systems vary greatly across molluscs. This diversity includes simultaneous hermaphroditism, with both sexes functional at the same time. Most nudibranch molluscs are thought to be simultaneous hermaphrodites, but detailed studies of reproductive development and timing remain rare as most species cannot be cultured in the lab. The aeolid nudibranch, Berghia stephanieae, is one such species that can be cultured through multiple generations on the benchtop. We studied B. stephanieae reproductive timing to establish when animals first exchange sperm and how long sperm can be stored. We isolated age- and size-matched individuals at sequential timepoints to learn how early individuals can exchange sperm. Individuals isolated at 10 weeks post initial feeding (wpf; ∼13 weeks postlaying [wpl]) can produce fertilized eggs. This is 6 weeks before animals first lay egg masses, indicating that sperm exchange occurs well before individuals are capable of laying eggs. Our results indicate that male gonads become functional for animals between 6 mm (∼6 wpf, ∼9 wpl) and 9 mm (∼12 wpf, ∼15 wpl) in length. That is much smaller (and sooner) than the size (and age) of individuals at first laying (12–19 mm; ∼16 wpf, ∼19 wpl), indicating that male and female functions do not develop simultaneously. We also tracked the number of fertilized eggs in each egg mass, which remained steady for the first 10–15 egg masses, followed by a decline to near-to-no fertilization. This dataset provides insights into the precise timing of the onset of functionality of the male and female reproductive systems in B. stephanieae. These data contribute to a broader understanding of reproductive development and the potential for understanding the evolution of diverse sexual systems in molluscs.

Timing and synchrony of birth in Eurasian lynx across Europe.

The ecology and evolution of reproductive timing and synchrony have been a topic of great interest in evolutionary ecology for decades. Originally motivated by questions related to behavioral and reproductive adaptation to environmental conditions, the topic has acquired new relevance in the face of climate change. However, there has been relatively little research on reproductive phenology in mammalian carnivores. The Eurasian lynx (Lynx lynx) occurs across the Eurasian continent, covering three of the four main climate regions of the world. Thus, their distribution includes a large variation in climatic conditions, making it an ideal species to explore reproductive phenology. Here, we used data on multiple reproductive events from 169 lynx females across Europe. Mean birth date was May 28 (April 23 to July 1), but was ~10 days later in northern Europe than in central and southern Europe. Birth dates were relatively synchronized across Europe, but more so in the north than in the south. Timing of birth was delayed by colder May temperatures. Severe and cold weather may affect neonatal survival via hypothermia and avoiding inclement weather early in the season may select against early births, especially at northern latitudes. Overall, only about half of the kittens born survived until onset of winter but whether kittens were born relatively late or early did not affect kitten survival. Lynx are strict seasonal breeders but still show a degree of flexibility to adapt the timing of birth to surrounding environmental conditions. We argue that lynx give birth later when exposed to colder spring temperatures and have more synchronized births when the window of favorable conditions for raising kittens is shorter. This suggests that lynx are well adapted to different environmental conditions, from dry and warm climates to alpine, boreal, and arctic climates. This variation in reproductive timing will be favorable in times of climate change, as organisms with high plasticity are more likely to adjust to new environmental conditions.

Size at Birth, Postnatal Growth, and Reproductive Timing in an Australian Microbat.

SynopsisReproductive phenology, size at birth, and postnatal growth are important life history traits that reflect parental investment. The ability to document detailed changes in these traits can be a valuable tool in the identification and management of at-risk wildlife populations. We examined reproductive traits in a common, widespread Australian microbat, Chalinolobus gouldii, at two sites over two years and derived growth curves and age estimation equations which will be useful in the study of how intrinsic and extrinsic factors alter parental investment strategies. We found that male and female offspring did not differ significantly in their size at birth or their postnatal growth rates. Bats born in 2018 were smaller at birth but grew at a faster rate than those born in 2017. When date of birth was compared across sites and years, we found bats born in 2018 had a later median birthdate (by 18 days) and births were more widespread than those born in 2017. Cooler and wetter weather during late gestation (Nov) in 2018 may have prolonged gestation and delayed births. With many bats facing threatening processes it is important to study reproductive plasticity in common and widespread “model” species, which may assist in the conservation and management of threatened microbats with similar reproductive traits.

The First Data on the Biology of Anatolichthys meridionalis (Actinopterygii, Aphaniidae): an Endemic and Endangered Fish of Turkey (Dalaman River Basin).

Species belonging to the Aphaniidae, extant as well as fossil, are widel distributed along the late-period Tethys Sea coast lines. Among the mentioned genera, Anatolichthys is the genus that includes the 13 species. Anatolia has been a center in the diversity of Anatolichthys. The study is one of the first studies on the growth of the species. On this occasion, in study, it was aimed to examine the growth parameters of the Anatolichthys meridionalis Akşiray, 1948 population, which is an endemic and endangered species in Anatolia. The population structure of endemic species Anatolichthys meridionalis in Gökpınar Spring (Dalaman River basin-Turkey) (37.34° N, 29.44° E) was studied, using 108 fish in October 2019 and September 2020. The growth and reproductive characteristics of A. meridionalis were examined in the study. Males made up 42.59%, females 57.41% of the population. The length-weight relationship and Von Bertalanffy growth equation were W = 0.0112L3.4638, R2 = 0.9793, Lt = 22.97 (1 – e–0.0304 (t+2.834)), respectively. Average growth performance and condition factor are calculated as 1.21 and 1.84, respectively. The gonadosomatic index was found in a maximum value (12.742%) in July and a minimum value (0.545%) in January. Reproduction time was found to be in between of July and September. The mean fecundity and mean egg diameter were found as 147.94 ± 28.03 number/individual/year and 1.35 ± 0.04 mm, respectively. The first maturation was found to be at age I. First maturity length (Lm) was estimated at 23.95 mm for females and 22.04 mm for males. Although the study shows that the species has no problem in finding food and is a population with a wide age range, the presence of invasive species in the habitat, the habitat is directly affected by pollution from agricultural activities, water is drawn by pumps for agricultural activities, and it is narrowly distributed and endangered species, A. meridionalis and its habitat Gökpınar Spring should be protected.

Temporal shifts in reproductive phenology of cycads: a comparative study in Ceratozamia

The reproductive phenology in plants consists of successive life cycle phases leading to reproductive success. In seed plants, cycads and other dioecious groups have complex reproductive systems, where individuals require synchronizations among two sexes and populations of the same species. Here, we analyzed phenology between populations of three geographically close species in the cycad genus Ceratozamia Brongn. We described the lifespan of pollen and ovulate strobili and their morphological changes throughout ontogeny and evaluated synchrony among reproductive events, focusing on the timing and abundance of the receptivity and open pollen phases. Our results showed that the reproductive timing in the three species was highly synchronous, and that the overlap between the receptivity and open pollen phases could point to gene flow among populations of different species. We identified a correlation between the reproductive patterns and the temperature and precipitation regimes. Pollen and ovulate strobili were produced during the rainy season, whereas the period of synchrony between receptivity and pollen occurred during the dry season. The seed release occurred during the rainy season, which could contribute to keep the seed moist and prevent the embryo from drying out. Finally, we highlight the utility of studies in wild populations for the ecological and evolutionary understanding of phenological patterns in cycads.

Plasticity in female timing may explain earlier breeding in a North American songbird.

Many species have shifted their breeding phenology in response to climate change. Identifying the magnitude of phenological shifts and whether climate-mediated selection drives these shifts is key for determining species' resilience to climate change. Birds are a strong model for studying phenological shifts due to numerous long-term research studies; however, generalities pertaining to drivers of phenological shifts will emerge only as we add study species that differ in life history and geography. We investigated 32 years of reproductive timing in a non-migratory population of dark-eyed juncos Junco hyemalis. We predicted that plasticity in reproductive timing would allow females to breed earlier in warmer springs. We also predicted that selection would favour earlier breeding and asked whether the temperatures throughout the breeding season would predict the strength of selection. To test these predictions, we examined temporal changes in the annual median date for reproductive onset (i.e. first egg date) and we used a sliding window analysis to identify spring temperatures driving these patterns. Next, we explored plasticity in reproductive timing and asked whether selection favoured earlier breeding. Lastly, we used a sliding window analysis to identify the time during the breeding season that temperature was most associated with selection favouring earlier breeding. First egg dates occurred earlier over time and strongly covaried with April temperatures. Furthermore, individual females that bred in at least3 years typically bred earlier in warmer Aprils, exhibiting plastic responses to April temperature. We also found significant overall selection favouring earlier breeding (i.e. higher relative fitness with earlier first egg dates) and variation in selection for earlier breeding over time. However, temperature across diverse climatic windows did not predict the strength of selection. Our findings provide further evidence for the role of phenotypic plasticity in shifting phenology in response to earlier springs. We also provide evidence for the role of selection favouring earlier breeding, regardless of temperature, thus setting the stage for adaptive changes in female breeding phenology. We suggest for multi-brooded birds that advancing first egg dates likely increase the length of the breeding season, and therefore, reproductive success.

Comparative analysis of the follicular transcriptome of Zhedong white geese (Anser Cygnoides) with different photoperiods

The laying performance of geese is mainly determined by follicular development and atresia, while follicular status is regulated by photoperiod. To understand the effect of photoperiod on the development of goose follicles, artificial light was used to change the photoperiod. In this study, ten healthy 220-day-old Zhedong white geese (Anser Cygnoides) with similar body weights and similar reproductive start times were reared for 60 days under long photoperiod (15 L:9 D) and short photoperiod (9 L:15 D) artificial light with the intensity controlled at 30 lux, and follicles were collected. Follicle development was analyzed by observing the morphology of follicle tissue, the localization of autophagosomes and autolysosomes, and the expression levels of apoptosis-related protein factors. Small white follicles (SWFs) were selected for RNA sequencing and bioinformatics analysis of the transcriptome. Under a long photoperiod, microtubule-associated protein 1 light chain 3 (LC3) and Caspase-3 were expressed in the granulosa cell layer and oocytes, respectively. LC3 and Caspase-3 protein expression was increased in SWF and large white follicles (LWFs), and there were more autophagosomes and autolysosomes in granulosa cells. RNA-seq found 93 differentially expressed genes (DEGs) in the short-photoperiod group, including 55 upregulated DEGs and 38 downregulated DEGs, distributed in 37 gene ontology categories. Kyoto Encyclopedia of Genes and Genomes-enriched signaling pathways revealed 5 pathways enriched in upregulated DEGs, including protein digestion and absorption, ECM-receptor interaction and regulation of lipolysis in adipocytes, and 4 pathways enriched in downregulated DEGs, such as fatty acid biosynthesis. Ten differentially expressed genes related to extracellular matrix and fatty acid metabolism (THBS2, COL12A1, MRC2, TUBA, COL1A1, COL11A1, HSPG2, FABP, MGLL, and OLAH) may be involved in the photoperiod regulation of follicle development in Zhedong white geese. The differentially expressed genes screened in this study will provide new ideas to further understand the molecular mechanism underlying photoperiod-mediated regulation of follicle development in Zhedong white geese.

Global warming leads to larger bats with a faster life history pace in the long-lived Bechstein’s bat (Myotis bechsteinii)

Whether species can cope with environmental change depends considerably on their life history. Bats have long lifespans and low reproductive rates which make them vulnerable to environmental changes. Global warming causes Bechstein’s bats (Myotis bechsteinii) to produce larger females that face a higher mortality risk. Here, we test whether these larger females are able to offset their elevated mortality risk by adopting a faster life history. We analysed an individual-based 25-year dataset from 331 RFID-tagged wild bats and combine genetic pedigrees with data on survival, reproduction and body size. We find that size-dependent fecundity and age at first reproduction drive the observed increase in mortality. Because larger females have an earlier onset of reproduction and shorter generation times, lifetime reproductive success remains remarkably stable across individuals with different body sizes. Our study demonstrates a rapid shift to a faster pace of life in a mammal with a slow life history.

Soft coral reproductive phenology along a depth gradient: Can "going deeper" provide a viable refuge?

Many species across a wide range of taxa and habitats display phenological shifts and differences in response to both environmental gradients and climate change. Moreover, the wide‐scale decline of numerous ecosystems is leading to increasing efforts to identify zones that might serve as natural refuges from various disturbances, including ocean warming. One such refuge was suggested to be that of the deep coral reefs, but whether depth can provide coral populations with a viable and reproductive refuge remains unclear. Given the global coral‐reef degradation and the key role that corals play as ecosystem engineers, their reproductive ecology has been widely studied. A particular knowledge gap nonetheless exists regarding coral reproductive phenology along a depth gradient. Filling in this gap may uncover the environmental cues that regulate coral reproduction, leading to better predictions of population connectivity, and their possible responses to climate change and other environmental changes. Here, using long‐term in situ observations of the soft coral Rhytisma fulvum's reproductive activity along its entire depth range (0–45 m), we examined the relationship among several environmental factors and the coral's reproductive phenology and activity over five successive annual breeding seasons. Compared with the shallow depths, a lower number of reproducing colonies was found in habitats deeper than 30 m, highlighting possible constraints on coral reproduction at the deeper end of their range. Our results further revealed that an increase in seawater temperature over 1–2‐day intervals during the breeding season correlated with the onset of reproductive activity along the depth gradient, leading to different reproductive periodicities in different depths. These differences suggest that differential temperature regimes and reproductive timing across depth may create intraspecific temporal reproductive segregation, possibly reducing connectivity among populations along a depth gradient. Moreover, we found high variability among years in both the timing of breeding activities and in the level of reproductive synchrony among corals from different depths. Overall, our study questions whether depth can provide a long‐term and viable refuge for corals in the face of global environmental changes.

Does mast seeding shape mating time in wild boar? A comparative study.

In seasonal environments, the timing of reproduction often matches with the peak of food resources. One well-known effect of global warming is an earlier phenology of resources, leading to a possible mismatch between the timing of reproduction for consumers and food peak. However, global warming may also change the dynamics of food resources, such as the intensity and frequency of pulsed mast seeding. How quantitative changes in mast seeding influence the timing of reproduction of seed consumers remains unexplored. Here, we assess how yearly variation in mast seeding influences mating time in wild boar (Sus scrofa), a widespread seed consumer species. We took advantage of the intensive monitoring of both female reproduction (1636 females) and acorn production over 6 consecutive years across 15 populations of wild boar in the wild. We found that mating time occurs earlier when acorn production increases in most but not all populations. In two out of 15 populations, heavy females mated earlier than light ones. Our findings demonstrate that mast seeding advances the mating time in some populations, which could perhaps impact how boars respond to climate change.

Transitando por el arte, el ocio y la maternidad: una etnografía móvil con mujeres artistas en Santiago de Chile

Based on an ethnographic approach to the daily life of women artists, this article explores the use of the mobile methodology to understand the experience of time and space in the context of the transformations of work and the contemporary urban experience. It is intended to shed light on the tensions and strategies of working mothers in the artistic sector when they have to reconcile their productive, reproductive, and leisure time in the city of Santiago de Chile. Multisite fieldwork was conducted for this research during 2018 and 2019, with a mobile methodology of monitoring the activities and daily movements of the study participants. This involved moving with them through the various public and private contexts of their personal and working lives. I conclude, based on the analyses that women artists make a permanent effort to organize a routine in which the times and spaces of art, leisure, and motherhood are inevitably interpenetrated. Gender inequality impacts not only on the overburdened work-life balance of the double day, but also the quality of their leisure time and their creative work. The use of a mobile methodology allowed me to capture in situ this daily time management, and the gendered costs of coping with a lifestyle marked by temporal overlapping and daily mobility in the city. With these theoretical and methodological choices, the article contributes to discussions on the value of mobile methodology and renewed uses of ethnography by distancing itself from traditional approaches to social research, which tend to construct their objects of study and approach actors in fixed contexts within the city.

Egg retention in wild-caught [i]Python bivittatus[/i] in the Greater Everglades Ecosystem, Florida, USA

Retention of eggs in oviducts beyond the normal oviposition period is a common problem for captive reptiles, but the occurrence of egg retention in wild populations is largely unknown. The Burmese python (Python [molurus] bivittatus; Kühl 1820) is an oviparous snake native to south-eastern Asia that is now established in southern Florida. From 2011–2019, invasive Burmese pythons were opportunistically removed from Everglades National Park and Big Cypress National Preserve, humanely euthanised, and necropsied to determine reproductive condition. A total of 258 females of reproductive size were found to exhibit various stages of oviposition which generally aligned with purported annual reproductive timing. However, we encountered five pythons during the post-ovulatory period (Aug–Feb) showing signs of recent oviposition with retained eggs. Most of these cases comprised a small number of retained eggs, likely representing some portion of the total clutch. Because this condition is nearly absent in wild animal literature, our observations suggest retained eggs in wild snakes may be more common than previously assumed, possibly slowing or otherwise impacting population growth. However, we recognise that for an invasive species like the Burmese python in Florida, the egg retention rate may be higher in the non-native range compared to the native range due to maladaptation to novel habitats or environmental conditions. Additional research is needed to determine the exact causes of egg retention and investigate the implications for population dynamics on this and other snake species. Keywords: invasive species, dystocia, snakes, Burmese, reproduction

Circadian Timing of the Female Reproductive System

Precise chronological transition is critical for a normal female reproductive system. Many epidemiologic studies have demonstrated rhythmicity in parturition during the resting phase, and even seasonal breeding. Circadian rhythms are controlled by a multi-oscillatory circadian system. These rhythms are determined by both genetic and environmental factors. The female reproductive axis is also highly rhythmic, and the hypothalamic-pituitary-gonadal axis and the hypothalamic-pituitary-adrenal axis are also functional multi-oscillatory circadian systems. Bidirectional communication between the central and peripheral tissue clocks is essential for maintaining the rhythm from ovulation to parturition. This review discusses the circadian timing of the female reproductive system, specifically its underlying metabolic and molecular clock functions. This review particularly focused on the following areas: multi-oscillatory system in the female reproductive system; the ovarian cycle and the timing of ovulation; timing of mating and seasonal reproduction; circadian rhythms in pregnancy; circadian timing of labor onset and parturition.

De novo Mutations in Domestic Cat are Consistent with an Effect of Reproductive Longevity on Both the Rate and Spectrum of Mutations.

The mutation rate is a fundamental evolutionary parameter with direct and appreciable effects on the health and function of individuals. Here, we examine this important parameter in the domestic cat, a beloved companion animal as well as a valuable biomedical model. We estimate a mutation rate of 0.86 × 10−8 per bp per generation for the domestic cat (at an average parental age of 3.8 years). We find evidence for a significant paternal age effect, with more mutations transmitted by older sires. Our analyses suggest that the cat and the human have accrued similar numbers of mutations in the germline before reaching sexual maturity. The per-generation mutation rate in the cat is 28% lower than what has been observed in humans, but is consistent with the shorter generation time in the cat. Using a model of reproductive longevity, which takes into account differences in the reproductive age and time to sexual maturity, we are able to explain much of the difference in per-generation rates between species. We further apply our reproductive longevity model in a novel analysis of mutation spectra and find that the spectrum for the cat resembles the human mutation spectrum at a younger age of reproduction. Together, these results implicate changes in life-history as a driver of mutation rate evolution between species. As the first direct observation of the paternal age effect outside of rodents and primates, our results also suggest a phenomenon that may be universal among mammals.

Improving the Reproductive Yield of Black Sea Salmon (Salmo labrax PALLAS, 1814) with a Selective Breeding Program

This study aimed to improve some culture characteristics of Black Sea salmon (Salmo labrax) culture generations through a classical selective breeding program. Thus, the success of the applied program was examined by comparing the reproduction time and proportional distribution of the wild broodstock (F0 ) individuals with the F1 , F2 , F3 and F4 generation broodstocks adapted to the culture conditions. According to the results, gamete uptake from the new generations occurred between October and February. The highest egg uptake was determined for all generations in December. While the difference between wild (F0 ) broodstock and F1 , F2 , F3 , and F4 generations was statistically significant in favor of new generations (P<0.05), the difference was insignificant between hatchery origin-new generations. Mean egg diameters were low in F2 and F3 generations, and F0 , F1 and F4 generations were found to be higher than the others (P<0.05). It was calculated that the fertilization rate was higher in F3 and F4 generations, similar in F1 and F2 generations, and lower in F0 generation than the others (P<0.05) at the end of the study. Through the selection program, it was determined that the adaptation of the species to the culture conditions improved, the reaction to human activities declined, and homogeneous distribution in tanks/ponds was relatively achieved from the F2 generations. As a result, it has been determined that F4 generation broodstock have higher culture performance than other generations. Producers of this species should use F4 broodstock for efficient and economical production. 

Abstract 983: RNA-seq analysis of murine liver to identify breast cancer metastatic potential during liver involution

Abstract Background: Postpartum breast cancer (PPBC), variably defined as breast cancer diagnosed within 5-10 years after a patient’s last pregnancy, has overall increased risk of metastasis even after controlling for patient age, year of diagnosis, and tumor subtype and stage. Metastasis to the liver is specifically increased in PPBC compared to non-PPBC cases and likely contributes to the overall poor prognosis of PPBC. Our lab has previously shown that the rodent liver undergoes physiological remodeling after pregnancy, in a process reminiscent of weaning-induced mammary gland involution. Further, rodent models confirm that breast cancer cells delivered to the involuting liver grow more robustly than tumor cells delivered to nulliparous liver. Our rodent data suggest that weaning induced liver involution may be responsible for increased tumor cell seeding and ultimately higher rates of liver metastasis observed in women diagnosed with PPBC. Since weaning-induced liver involution is a recently recognized physiology, little is known of its molecular underpinnings. Here we employ RNA-seq of murine livers to better understand how reproductive status influences liver physiology with a focus on exploring the pro-metastatic niche formed after weaning. Study design: Livers were isolated from age-matched mice at the following reproductive time points: nulliparous (never pregnant), lactation, involution days 2, 4, 6, and 8, and fully regressed (4 weeks post-wean) and flash frozen for RNA isolation (n=3-6 mice per group). RNA-seq was utilized to identify gene expression differences between reproductive groups. We employed single-sample gene set enrichment analysis (ssGESA) to identify key pathways modulated by reproductive state. Results: We identify clear reproductive control of liver physiology. We find increases in proliferation, MTORC1, and anabolic metabolism pathways during lactation when compared to any other reproductive state. In the transition from lactation to involution, we find increases in apoptotic pathways, and a switch to catabolic metabolism. Correspondingly, during involution we see enrichment in pro-cancer pathways including increased TGFβ signaling, Epithelial to Mesenchymal Transition, and Inflammatory Responses Hallmark Pathways. Within the immune signatures changes of involution, we observe myeloid-derived cell signatures including enrichment in M2 associated genes, and increases in cytotoxic and helper T cell signatures that parallels a signature for disease-specific T cell exhaustion. Conclusion: This work highlights novel regulation of liver physiology by reproductive state, and finds pathways regulated during the natural physiological process of involution that have been previously identified as contributing to metastatic niches. This study has the potential to identify new targets for the prevention and treatment of breast cancer liver metastasis. Citation Format: Michelle K. Ozaki, Alexandra Q. Bartlett, Zheng Xia, Pepper Schedin. RNA-seq analysis of murine liver to identify breast cancer metastatic potential during liver involution [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 983.

SERPENT CODE POINT KINETIC PARAMETERS ANALYSIS: A NEXUS FOR NIGERIA RESEARCH REACTOR – 1 CORE CONVERSION USING ENRICHED URANIUM DIOXIDE FUEL

The International Atomic Energy Agency (IAEA) requires that all test and research reactors operating on Higher Enriched Uranium (HEU) should be converted to Low Enriched Uranium (LEU) for safety and security purposes. Nigeria having a Miniature Neutron Source Reactor (MNSR) has been long interested in fuel technological research not just to develop the area but also to meet with resolution on the nuclear treaty set out by the global nuclear regulatory body. In this study, reactor kinetic parameters such as effective delayed neutron fractions, prompt neutron lifetime as well as mean neutron generation time were analysed for Nigerian Research Reactor-1 (NIRR-1). Serpent Monte Carlo code 1.17 is used in the analysis. For delayed neutron parameters determination, we used fission probability iteration under one averaged generation time and neutron population rate.The calculated values for delayed neutron were recorded as analogue prompt and implicit prompt neutron lifetime, reproduction time and emission time are in the order of 3×10-7 (s), in agreement with the calculated data from the nuclear data libraries and some literature.The result for delay neutron fraction and other time-based parameters support the fuel core conversion for NIRR-1.The computational and pictorial results obtained from Serpent code simulation described well the transient behavior of the delayed neutron in this reactor.The analytical results also spelled out the relevance and compatibility of low enriched uranium dioxide fuel over higher enriched type.The result of this study conforms with other results obtained from similar reactors but with different Monte Carlo codes and with higher enriched uranium

“I want to become someone!” gender, reproduction and the moral career of motherhood for women with sickle cell disorders

In Sierra Leone, motherhood is being transformed into a moral career for women with sickle cell disorders. This qualitative participatory study, conducted in 2018, involved thirty-six semi-structured interviews with female care-givers and women with sickle cell disorders. Mothers argued that medical models of disease, combined with caring practices, are means to morally manage ideas of ‘spoiled identity’ and rethink the sick role, disability and life-outcomes of a potentially serious condition. Mothers encourage their children with sickle cell to stay in education as a route to access formal employment and careers that will not tax their bodies and ensure reproductive timing. Education and employment are framed temporally to ensure a delay so that girls can develop caring relationships and access motherhood safely. Understanding and encouraging the development of motherhood as a moral career, involving embodied hyper-vigilant caring practices, is valuable for the self-identity of mothers, allowing them to see a future for themselves and their children.

Gonadal Cycles and Growth to Sexual Maturity of the Eastern American Toad, Anaxyrus americanus americanus (Holbrook, 1836), from Pennsylvania

The Eastern American Toad, Anaxyrus americanus americanus (Holbrook, 1836) is an ubiquitous and geographically wide-ranging subspecies of eastern North America. As such, it also varies geographically in several of its life history traits. A statewide examination of its gonadal cycles and body size-age relationships in Pennsylvania revealed a conformity to contemporary latitudinal patterns associated with these life history traits. Likewise, these very responses to spatial differences in climate, we proffer, predispose the Eastern American Toad to climate-change related shifts in timing of reproduction in Pennsylvania. Such a change, depending upon the reproductive response to climate change by Fowler's Toad, Anaxyrus fowleri (Hinckley, 1882), could result in an increased likelihood of hybridization, a phenomenon with significant evolutionary implications.

Dynamic morphological plasticity in response to emergence timing in Abutilon theophrasti (Malvaceae).

Selections on emergence time might be conflicting, suggesting the existence of the optimal emergence time for plants. However, we know little about this and how morphological plasticity contributes to the strategies of plants in response to emergence timing. To better understand this issue from a dynamic perspective, we conducted a field experiment by subjecting plants of Abutilon theophrasti to four emergence treatments (ET1~ ET4) and measuring a number of mass and morphological traits on them at different growth stages (I ~ IV). On day 50, 70, and/or final harvest, among all ET treatments, plants germinated in late spring (ET2) performed the best in total mass, spring germinants (ET1) and ET2 performed better in stem allocation, stem, and root diameters than later germinants (ET3 and ET4); summer germinants (ET3) had the highest reproductive mass and allocation, while late-summer germinants (ET4) had the greatest leaf mass allocation, with greater or canalized leaf number, and root length traits than others. Plants that emerged in late spring can maximize their growth potential, while those with either advanced or delayed emergence are still capable of adaptation via allocation and morphological plasticity. Early germinants (ET1 and ET2) preferred stem growth to leaf and reproductive growth, due to sufficient time for reproduction in the growth season. With limited time for growth, plants that emerged late may prefer to quicken leaf growth (indicated by increased leaf mass allocation and leaf number) at the cost of stem or root growth for the complete life cycle, reflecting both positive and negative effects of delayed emergence.