Σκοπός: Να αξιολογηθεί ο λόγος αγόρια/κορίτσια (sex ratio) στα παιδιά καπνιστριών και μη καπνιστριών μητέρων, σε σχέση με τη σειρά γέννησης των παιδιών (τόκος). Να αξιολογηθεί το αποτέλεσμα του καπνίσματος της μητέρας κατά την εγκυμοσύνη στην εμβρυική ανάπτυξη σε σχέση με τον τόκο την ηλικία και τον αριθμό των τσιγάρων που κάπνιζαν οι μητέρες ανά ημέρα κατά την εγκυμοσύνη και το φύλο των παιδιών. Σχεδιασμός: Προοπτική μελέτη. Τόπος: Πανεπιστημιακό Γενικό Νοσοκομείο Πατρών. Αντικείμενο: Μελετήθηκαν 2.108 τελοιόμηνα νεογνά που γεννήθηκαν από το 1993 έως και το 2002, 665 νεογνά καπνιστριών μητέρων και 1.443 νεογνά μη καπνιστριών μητέρων. Αποτελέσματα: Ο λόγος αγόρια/κορίτσια στο σύνολο των νεογνών που μελετήθηκε ήταν 1,09. Η υπεροχή των αγοριών στα παιδιά των καπνιστριών και μη καπνιστριών μητέρων ήταν 1,26 και 1,03 αντίστοιχα. Στα παιδιά των καπνιστριών μητέρων που ήταν τόκων 1, 2 και ≥3 ήταν 1,47, 1,35 και 0,92 αντίστοιχα, ενώ στα παιδιά των μη καπνιστριών μητέρων ήταν 1,04, 1,00 και 1,03 αντίστοιχα. Η στατιστική ανάλυση παλινδρόμησης έδειξε ότι η πιθανότητα για γέννηση αγοριού από καπνίστριες μητέρες ήταν σημαντικά μεγαλύτερη στις πρωτότοκες παρά στους τόκους ≥3, ανεξάρτητα από την ηλικία της μητέρας. Αντίστροφα, η σειρά γέννησης των παιδιών δεν επηρέασε τον λόγο αγόρια/κορίτσια στις μη καπνίστριες μητέρες. Αυξανομένου του τόκου στα νεογνά των μη καπνιστριών μητέρων παρατηρήθηκε μια σταδιακή αύξηση της ανάπτυξης ενώ στα νεογνά μη καπνιστριών μητέρων παρατηρήθηκε μια σταδιακή μείωση της ανάπτυξης. Αυτό το αποτέλεσμα ήταν περισσότερο εμφανές στα αγόρια. Ένα σημαντικά αρρνητικό αποτέλεσμα στην αύξηση παρατηρήθηκε από την στην συσχέτιση του καπνίσματος με τον τόκο (p=0,0013) και, με το φύλο και τον τόκο (p=0,001). Υπήρχε μια σημαντική αρρνητική συσχέτιση ανάμεσα στον αριθμό των τσιγάρων που καπνίζονταν ανά ημέρα και της αύξησης η δύναμη της οποίας αυξανόταν με την αύξηση του τόκου, κυρίως στα αγόρια. Συμπεράσματα: Οι πρωτότοκες μητέρες που κάπνιζαν κατά την εγκυμοσύνη γέννησαν σημαντικά περισσότερα αγόρια απ’ ότι κορίτσια, ενώ μητέρες με τόκους ≥3 γέννησαν περισσότερα κορίτσια. Δευτερότοκες γυναίκες που κάπνιζαν λιγότερα από 10 τσιγάρα την ημέρα γέννησαν σημαντικά περισσότερα αγόρια, αλλά ο λόγος αγόρια/κορίτσια ελαττώθηκε όταν κάπνιζαν ≥10 τσιγάρα την ημέρα. Το κάπνισμα της μητέρας κατά την κύηση προκαλεί καθυστέρηση στην εμβρυική αύξηση, κυρίως στα αγόρια, ένα αποτέλεσμα που ενισχύεται με τον τόκο αλλά είναι ανεξάρτητο από την ηλικία της μητέρας. / Objective: To assess the sex ratio in offspring of smoking and nonsmoking mothers in relationship to the parity. To examine the effect of maternal smoking during pregnancy on fetal growth in relationship to maternal parity, age and number of cigarettes smoked/day, and offspring’s gender. Design: Prospective study. Setting: University hospital. Subjects: Were studied 2018 term singleton neonates born form 1993 to 2002, 665 from smoking and 1443 from nonsmoking mothers. Main outcome measures: Secondary sex ratio in regard to maternal periconseptual smoking and parity. Results: The male preponderance in the offspring of smoking and nonsmoking mothers was 0.558 and 0.506, respectively (p=0.031). In the smoking women parity 1, 2 and 3 it was 0.596, 0.574 and 0.462, respectively, whereas in the nonsmoking it was 0.511, 0.500 and 0.508, respectively (p=0.02, 0.04 and 0.64, respectively). Logistic regression analysis showed that the possibility for a boy to be delivered by mothers who smoked was significantly greater in primiparous than in party ≥3, independently of the maternal age. Conversely, parity did not affect the sax ratio in the offspring of the nonsmoking mothers. With increasing parity, in the neonates of nonsmoking mothers there was a gradual increase of growth, whereas in neonates of smoking mothers there was a gradual decrease of growth. This effect was more pronounced in males. A significant negative main effect on growth resulted from the interaction of smoking with parity (p=0,013), and with gender and parity (p=0,001). There was a significant negative correlation between number of cigarettes smoked per day and growth, the strength of which increased with parity, mainly in males. Conclusions: Among women who smoked in the periconceptual period, significantly more male than female offspring are born from primiparous, whereas parity >3 give birth to more female offspring; women parity 2 give birth to significantly more male, but the sex ratio declines when they smoked ≥10 cigarettes/day. Maternal smoking during pregnancy causes a delay in getal growth, which is greater in male offspring, an effect that is enhanced with parity but is independent of maternal age.

Um dos grandes problemas que afetam a produção in vitro de embriões é a variação entre touros em relação à fertilidade e o maior nascimento de embriões do sexo masculino. Muitos fatores podem alterar a razão de 1:1 entre os gêneros tanto na produção in vitro de embriões, como no método de Inseminação Artificial. No sentido de tentar alterar esta proporção sexual in vitro, estudamos em um primeiro momento, a variação entre touros no desenvolvimento de embriões machos e fêmeas, distribuídos nas fases de blastocisto jovem, blastocisto, blastocisto expandido e blastocisto eclodido, bem como, a proporção macho: fêmea em relação a fase do blastocisto. Para tanto, oócitos foram coletados de ovários oriundos de matadouro e maturados em meio de maturação em incubadora por 24h. Espermatozóides viáveis de 17 touros do Programa de Melhoramento Genético da Raça Nelore, obtidos por centrifugação em gradiente de Percoll, foram utilizados para Fecundação in vitro. Após 12h, os supostos zigotos foram cultivados em meio de cultivo e células do cumulus em incubadora. Ao sétimo dia após a fertilização in vitro foi feita a seleção dos blastocistos viáveis que foram sexados com a utilização de primers Y-específico bovino e autossômico bovino, com visualização dos fragmentos amplificados em gel de agarose. Posteriormente, para obtenção de maior conhecimento a respeito dos animais testados, coletamos dados de progênie a campo destes animais e verificamos a proporção sexual de seus filhos nascidos pelo método da inseminação artificial, monta natural e possíveis correlações com características quantitativas. Diferenças entre touros foram observadas em relação à proporção dos sexos para as fases de blastocisto inicial e blastocisto expandido. Não foi observado desvio da proporção sexual em relação ao touro utilizado na produção in vitro de embriões e progênie a campo. Nosso dados sugerem que é possível alterar a proporção macho:fêmea em sistemas de produção in vitro de embriões pela seleção do estágio do blastocisto para transferência, e ainda, sugerem que touros apresentam variação em relação ao desenvolvimento in vitro de embriões machos e fêmeas de acordo com o estágio do blastocisto. / Some of the main problems that affect the in vitro production of embryos is the variation among bulls in relation to fertility and the greater birth of male embryos. Many factors can change the ratio 1:1 between the genders, both in the in vitro production of embryos and in the method of artificial insemination. To try to change this sex ratio in vitro, we studied at first, the variation among bulls in the development of female and male embryos, the blastocyst-stage distributed in young blastocyst, blastocyst, expanded blastocyst and hatched blastocyst and the proportion male: female in relation to the blastocyst stage. For this, oocytes were collected from slaughterhouse ovaries and matured in maturation medium in an incubator for 24h. Viable sperm from 17 bulls belonging to the Breeding Program of Nellore, obtained by Percoll gradient centrifugation were used for in vitro fertilization. After 12 hours, the presumptive zygotes were cultured in culture medium and cumulus cells in an incubator. After 168 hours of in vitro fertilization the viable embryos in the blastocyst stage were classified. The determination of the sex of the blastocysts was performed by Polymerase Chain Reaction (PCR) using a Y-specific sequence and bovine autosomal sequence visualized in agarose gel. Data analysis was conducted using the Statistical Analysis System software. Later, to obtain more knowledge about the animals tested, data was collected from the field progeny of these animals and established the sex ratio of the offspring produced by the method of artificial insemination, natural mating and possible correlations with quantitative traits. Differences between bulls were observed relating to the proportion of genders at the initial stages of blastocyst and expanded blastocyst. No deviation was observed in the sex ratio in relation to the bull used for in vitro production of embryos and offspring in the field. Our data suggest that it is possible to change the male to female proportion in production systems of in vitro embryos through the selection of the blastocyst stage for transfer, and also suggest that bulls show variation in relation to the in vitro development of male and female embryos, depending on the blastocyst stage.

Climate change threatens to disrupt biological systems around the globe, sparking debate over natural capacity for adaptation in a fragmented landscape. Marine turtles are evolutionarily ancient and have survived millions of years of prehistoric climate change, but are threatened by the rapidity of modern warming and a history of severe overexploitation that has left most populations depleted. This thesis explores a nesting aggregation of the green turtle (Chelonia mydas) in northern Cyprus, where a longitudinal programme of both intensive and extensive monitoring enables insight into individual and population level parameters and processes. Nesting on the two coastlines covered by this project is in the early stages of recovery, possibly in response to exhaustive nest protection efforts over the last twenty years. Saturation tagging at one key site allows us to confirm that recruitment of new breeders is an important driver of this trend, and that average clutch frequency has remained stable around three nests per female per year, validating nest-count derived abundance estimates at a regional scale. Concern has been raised, however, regarding recent changes in fishing practices which are impacting the local juvenile neritic phase, which may have a lagged effect on the recovery of this nesting population. A collaborative tracking effort including all other countries with major nesting in the Mediterranean allows us to identify major foraging grounds for this species, with two hotspots accounting for >50% of tracked individuals, as well as coastal and pelagic seasonal corridors of high use. Bycatch levels and mortality rates for turtles in these key areas are largely unknown and should be prioritised for investigation. Hatchling sex ratios from the main study beach are extremely female-biased (estimated 97% female for the twenty year period 1993-2012). A 1oC rise in average incubation temperatures threatens near complete hatchling feminisation on this beach, whilst a 2oC rise could reduce hatch success to less than 50%. Thermal effects on hatchling morphometrics are evident, with a 1oC rise in temperature reducing average length, width and weight by 1%, 2% and 3% respectively. More favourable incubation conditions were found early in the season, in deeper nests laid by larger females, and on beaches of lighter sand. In contrast, adult sex ratios at the main site are male-biased, posing questions regarding sex-specific survival rates and optimal hatchling sex ratios. A phenological shift towards earlier nesting is demonstrated for the first time in this species, and could potentially ameliorate warming effects. Carry-over climate forcing effects from the foraging ground influence the breeding frequency of individuals, driving population level responses in annual magnitude of nesting. This work emphasises the utility and necessity of long-term individual-based monitoring programmes in elucidating population trends and climate responses in iteroparous species with non-annual breeding.

Orientador: Otto Bismarck Fazzano Gadig / Resumo: A raia elétrica cega Benthobatis kreffti é endêmica do Altântico Sul Ociedental e apresenta distribuição restrita desde o sul até o sudeste Brasileiros, ocorrendo em profundidades entre 400 e 600 m. Apesar de seu extremo endemismo, sua biologia é virtualmente desconhecida, especialmente no que diz respeito à porção norte de sua distribuição. O objetivo deste trabalho foi estudar a estrutura populacional e biologia reprodutiva desta espécie, no talude continental do estado de São Paulo. Os indivíduos foram capturados em julho e agosto de 2003 e dezembro de 2007 no cruzeiro científico Soloncy Moura, o qual operou em 492-501 m de profundidade entre os municípios de Santos e Cananéia. Quanto à composição de captura, B. kreffti foi o condricte mais capturado, seguido por Gurgesiella dorsalifera. Os demais foram Hydrolagus matallanasi, Dipturus sp. e Torpedo, sp. Quanto à estrutura em tamanho, fêmeas diferem de machos por apresentarem maiores comprimentos (máximo de 299 mm em fêmeas e 256 mm em machos). A razão sexual total foi diferente de 1:1, bem como para indivíduos adultos. Nos outros estágios de maturidade considerados (imaturo e em desenvolvimento), não houve diferença significativa. A relação comprimento-peso e o tamanho onde 50% da população encontra-se maduro (LT50) também foram diferentes entre os sexos, em favor das fêmeas. Fêmeas apresentaram LT50 de 191 mm enquanto machos maturam em 176 mm. A fecundidade uterina foi de três embriões por fêmea, com embriões nascendo en... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The blind electric ray Benthobatis kreffti is endemic to the South West Atlantic and has a restricted distribution, from south and southeast Brazil, occurring in 400-600 m depth. Despite its endemism, its biology is virtually unknown, especially concerning the north extreme of its distribution. For this reason, the aim of this work was to study the population structure and reproductive biology of B. kreffti off São Paulo State continental slope. Individuals were captured in July and August of 2003 and December 2007 during the scientific cruise Soloncy Moura, operating in 492-501 m depth between Santos and Cananéia municipalities. Benthobatis kreffti was the most captured chondrichthyan, followed by Gurgesiella dorsalifera. Other chondrichthyan captured were: Hydrolagus matallanasi, Dipturus sp and Torpedo sp.. Concerning size structure, females were larger than males (females: 299 mm; males: 256 mm total length). Total sex ratio was different from 1:1, as well as for adult individuals. At other maturity stages considered (immature and developing), no differences were observed. The length-weight relationship and size at 50 % maturity (LT50) were also different between sexes, biased toward females. Female´s LT50 was 191 mm, while in males, LT50 was 176 mm total length. Uterine fecundity was three embryos/ female, with size at birth estimated in 90-100 mm total length (about1/3 of the total length recorded for this species). / Mestre

Chapter 1: This paper offers new causal evidence on how the timing of prenatal temperature shocks affects fetal health, sex ratio at birth, and early-age human capital. Analyzing data on nearly 2 million live births from sub-Saharan African countries and exploiting exogenous spatial and temporal variation in monthly temperature, we uncover three findings. First, we find that a cold temperature shock decreases the likelihood of a male birth. This effect is non-linear, being larger in the first and third trimesters of pregnancy. It is also highly heterogeneous, being larger for older women, higher parity births, and rural areas. Second, combining our empirical estimates with a climate model, we find that the number of fetal deaths caused by climate change will rise from 200 to 400 per 100,000 live births by 2050 throughout sub-Saharan Africa. Third, in contrast to their differential effect on fetal mortality, prenatal temperature shocks increase infant mortality more for females than for males, suggesting that only healthier male fetuses survive to adverse in utero conditions. Our analysis implies that the design of policies to avert the negative impacts of climate change on children should account for stages of fetal development. Chapter 2: Despite its enormous individual and social costs; the fundamental and long- run causes of cognitive aging remain understudied. We study the causal effect of in-utero temperature exposure on cognition during old age. Combining unique data on South African adults between 40 and 99 years of age with geospatial information on historical temperatures, our identification strategy exploits exogenous, within-municipality-of-birth, month-to-month variations in temperature, and controls for contemporaneous weather and location at the time of survey administration. We find that temperature in the first trimester of pregnancy negatively affects the cognitive function score later in life, but temperature in the second and third trimesters has a positive effect on adults cognitive function score. These differing effects result in an overall U-shaped relationship between prenatal exposure to temperature and cognition. This non-linear relationship is robust across measures of memory, reasoning, and information processing speed. Our findings are consistent with the fetal programming theory, which holds that the first trimester of pregnancy is the most crucial window of brain formation. In accordance with this theory, brain development occurring in the first trimester of pregnancy would therefore have the highest vulnerability to external shocks. Heterogeneity analysis reveals that the effect of prenatal temperature on cognition is larger for men, individuals over 75 years of age, and individuals with low social capital. Analyzing causal mechanisms, we find that prenatal temperature affects key determinants of individuals' cognitive reserve. We also find that exposure to drought during the first trimester of pregnancy and reduced sleep during adulthood are other potential channels through which the effects of prenatal exposure to temperature operate. Chapter 3: A large literature seeking to understand the labor market impacts associated with the clean energy transitions broadly finds opposite effects. On the one hand, a net positive impact on the workforce i.e. the new green jobs created in renewable energy sectors will compensate for the jobs lost in fossil-fuel sectors, while on the other hand, the so-called regulated dirty energy sector will reduce the fraction of workers hired. However, empirical and simulation models typically ignore transitional impacts associated with environmental regulations on labour. These relate to how workers adjust over time to environmental regulations, not just the steady state impact that is the focus of prior studies. We evaluate an environmental regulation (Ontario coal-fired electricity generating plants phase-out) regarding its transitional and long-term impacts on employee's outcomes including (i) wages; (ii) unemployment insurance; (iii) sector mobility; and (iv) geographic location. Using the Longitudinal Worker File (LWF) and Postal Codes Conversion File (PCCF) maintained by Statistics Canada, we estimate the labor market impacts of clean energy policy by comparing employees from affected coal plants to a comparable group of employees from non-affected plants. We find that, workers exposed to Ontario phase-out coal policy have earned on average 7000 $ CAD yearly less compared to those who weren't exposed. Our findings are consistent across a set of alternative specifications and robustness checks. Moreover, results from the event study approach suggest that the regulation leads to labor costs with the de- cline of wages just in transition. We provide supportive evidence on large labor costs due to environmental regulation policy and shed lights on the importance of reforms and training programs to support workers during the transition.

Endocrine-disrupting compounds (EDCs) interfere with the physiology of hormone systems. Traditionally, steroidogenic pharmaceuticals have been studied as EDCs however there has been growing evidence that non-steroidogenic pharmaceuticals can alter sex steroid levels and impair reproductive functions in fish. This is of concern as pharmaceuticals are detected in surface waters at the ng L-1 to µg L-1 range. Zebrafish (Danio rerio) were exposed to 10 µg L-1 of the pharmaceuticals carbamazepine and gemfibrozil for 6 weeks. Male-biased sex ratios were observed in the sexually mature offspring after paternal exposure, suggesting that sexual differentiation may be impacted in juveniles. Currently, the ability of pharmaceuticals to interfere with sexual differentiation of parentally exposed offspring is unknown. This thesis examined the gonad histology of juvenile zebrafish to understand how sexual differentiation was affected in the offspring of exposed parents. Paternal, but not maternal, exposure to carbamazepine resulted in a significantly faster sexual differentiation of the gonads and led to a male-biased sex ratio; these effects were not observed when both parents were exposed. Combined paternal and maternal exposure to gemfibrozil resulted in significantly faster sexual differentiation and paternal, but not maternal, exposure to gemfibrozil led to male-biased sex ratios. Interestingly, sex ratios observed in the juveniles did not always reflect those found in the same lineage at sexual maturity, suggesting a sex reversal, including a male to female transition, occurred past the juvenile sexual differentiation period in some fish. This thesis demonstrates that pharmaceuticals have the ability to disrupt sexual differentiation in the F1 offspring of exposed parents and that paternal exposure is most relevant for offspring effects. / Thesis / Master of Science (MSc) / Parental exposure to the environmentally-relevant pharmaceuticals carbamazepine or gemfibrozil led to male-biased sex ratios in adult offspring of zebrafish (Danio rerio), a common model organism. The development of the gonads in juveniles was investigated to determine how this process was impacted. Predominately, paternal exposure was found to result in a faster development of the testes and male-biased sex ratios. Interestingly, sex ratios in juveniles did not always reflect those in adults, suggesting a sex reversal may have occurred in adulthood. This study demonstrates the ability of pharmaceuticals to alter gonad development in offspring of exposed parents.

This thesis comprises three chapters on topics in development economics. The first chapter studies access to maternal healthcare in markets with vertically differentiated public and private providers. The second chapter studies the efficacy of induction stoves in reducing indoor air pollution in rural households when faced with erratic power supply. Finally, the third chapter studies the role of financial incentives in correcting disparities in sex ratios. All three chapters study the context of India but are representative of important development issues in low-income countries. The first chapter titled "Equilibrium Effects of Subsidizing Public Services" studies one of India's largest welfare schemes Janani Suraksha Yojana (JSY) that incentivized pregnant women in India to access institutional maternal care at public hospitals. We argue that governments can make complementary investments to improve welfare gains from large scale policies. JSY did not improve health outcomes despite a substantial increase in the take-up of institutional care. We document three equilibrium responses that explain this policy failure. First, JSY led to a mismatch of risk across health facilities -- high-risk mothers sorted out of highest quality care at private facilities. Second, in line with the literature, public sector quality deteriorated as a result of congestion. This resulted in lower quality care for both marginal as well as infra-marginal patients at public hospitals. We show that only mothers with high socio-economic status adapted to the worsening quality of care at public hospitals by sorting into more expensive private hospitals. Third, despite increased competition, private hospitals maintained high prices, crowding out riskier and poorer mothers. We do not find evidence that private hospitals improved healthcare quality to justify higher prices. The second chapter titled "Electric Stoves as a Solution for Household Air Pollution" is an interdisciplinary field-based research study that studies the role of reliable electricity in inducing rural Indian households to switch away from dirty cooking fuels towards a clean cooking technology, induction cookstoves, thereby reducing the exposure to high levels of indoor air pollution. We collected minute-by-minute data on electricity availability, electric induction stove use, and kitchen and outdoor particulate pollution in a sample of rural Indian households for one year. Using within household-month variation generated by unpredictable outages, we estimate the effects of electricity availability and electric induction stove use on kitchen PM2.5 concentration at each hour of the day. Electricity availability reduces kitchen PM2.5 by up to 50 ??/?3, which is between 10 and 20 percent of peak concentrations during cooking hours. Induction stove use instrumented by electricity availability reduces PM2.5 in kitchens by 200-450 ??/?3 during cooking hours. The final chapter titled "Can Large-Scale Conditional Cash Transfers Resolve the Fertility-Sex Ratio Trade-off? Evidence from India" studies a large-scale conditional cash transfer (CCT) scheme Ladli Laxmi Yojana that offered cash incentives to households upon the birth of girl children. The policy also offered substantial incentive for investing in girls' education. In my evaluation of the Ladli Laxmi Yojana in Madhya Pradesh, India. I find that financial incentives aimed at the girl child increased average fertility by about 0.15 children per household (on baseline average of 0.93 children) children per household and improved sex-ratio by 3%. This points to the well known fertility-sex ratio trade-off. Moreover, these effects are quite opposite to a similar CCT scheme in Haryana (Anukriti, 2018) suggesting context dependence of such policies.

In this dissertation I analyze patterns of maternal-infant health in developing contexts. My first chapter uses child hemoglobin as a bio-marker for maternal malnutrition in Senegal during the 2008 food price crisis. In early 2008, world rice prices skyrocketed, causing people around the world to plunge into poverty. Senegal, in particular, depends heavily on imported foodstuffs. I find that the crisis had a large, negative impact on child anemia in urban Senegal, most likely reflecting a deterioration of maternal nutrition caused by rising food prices. In the second and third chapters, we introduce a novel indicator of maternal-infant health: childhood sex ratios. Because infant females have lower rates of mortality than infant males, the sex ratio of the surviving population reflects the level of infant mortality. Childhood sex ratios are widely available from census data, meaning we can use them to shed new light on historical populations who lack traditional sources of data on infant mortality, like birth and death records. We apply this new method to the 19th-century US, where the lack of vital statistics has left uncertainty over even approximate levels of infant mortality. We find that the level of infant mortality in the pre-industrial US was much lower than previously thought, but that racial health disparities were much greater.

The allocation of resources to male or female progeny, or to male or female reproductive function more generally, is one of the most important life history decisions a sexually reproducing individual must ever make. Sex determination is thus a fundamental process, yet the mechanisms which control it are surprisingly diverse. In this thesis, I examine sex determination in the plant species Mercurialis annua L. (Euphorbiaceae). I assess the mechanism of sex determination operating in dioecious and androdioecious populations of M. annua and also investigate the conservation and evolution of sex-determining mechanisms across the annual mercury clade, the lineages of which display exceptional variation in sexual system. First, using crosses, I establish that sex in dioecious M. annua is controlled by a single-locus genetic mechanism, consistent with recent work that identified a single male-linked DNA marker in the species. My search for new sex-linked genes revealed none, however, suggesting that M. annua possesses at most a small non-recombining region around sex-determining loci. Why many dioecious plants lack heteromorphic sex chromosomes is still poorly understood and I consider explanations for this. I extend my investigation by comparing genetic diversity between loci that differ in their linkage to the sex-determining locus. I find a single male-linked marker to possess significantly lower diversity than autosomal loci, but no difference in the diversity of partially sex-linked and non-sex-linked genes. I also assess the conservation of a sex-linked marker among annual mercury lineages and conduct crosses between lineages to examine the conservation of sex determination. My findings indicate a conserved mechanism of single-locus genetic sex determination and I consider the role polyploidisation and hybridisation have played in sexual system evolution and the modification of sex-determining mechanisms in the clade. Finally, I assess the presence of environmental sex determination in androdioecious M. annua, concluding that although male frequency is not influenced by growing density, a degree of sexual lability exists in the lineage.

Introdução: A poluição atmosférica é proveniente de complexas interações que envolvem emissões de poluentes atmosféricos e que sabidamente causam consequências negativas para a saúde humana. De acordo com alguns estudos, a exposição à poluição, durante a gestação, pode causar baixo peso ao nascimento e prematuridade. Contudo, não há ainda consenso sobre os períodos de maior susceptibilidade para a exposição à poluição, e quais seriam os seus efeitos nos desfechos do gestação e na determinação do sexo do recém-nascido (RN). Objetivos: Com a finalidade de investigar o impacto da poluição na gestação e, consequentemente, no RN, os objetivos deste projeto são avaliar a influência da exposição à poluição, antes da concepção, na determinação do sexo do RN, e, durante a gestação, nos desfechos do parto e na curva de crescimento da circunferência cefálica (CC) entre o terceiro trimestre e o parto. Métodos: Um estudo prospectivo com 371 gestantes, intitulado ProcriAR, foi realizado na cidade de São Paulo. Os poluentes dióxido de nitrogênio (NO2) e ozônio (O3) foram medidos durante cada trimestre da gestação por meio da utilização de amostradores passivos individuais (APIs). Simultaneamente, foi realizada a análise dos poluentes NO2 e material particulado com tamanho menor que 10 Micro m (MP10) medidos pela estação fixa de ar de Taboão da Serra da Companhia Ambiental do Estado de São Paulo (CETESB), localizada na zona oeste de São Paulo e a mais próxima da residência das gestantes do projeto. Os desfechos avaliados foram: idade gestacional, peso, comprimento e medida da CC do RN; sexo do RN e crescimento do polo cefálico entre o terceiro trimestre e o parto. Quando a variável desfecho era contínua, foi realizada análise linear multivariada, controle de idade gestacional, sexo do RN, idade materna no momento da concepção, índice de massa corporal (IMC), paridade, tabagismo, consumo de álcool, cor, nível de escolaridade completado, estado civil, índice de pulsatilidade (IP) da artéria umbilical no terceiro trimestre, e via de parto para a variável CC. Resultados: Não foram observadas associações entre a exposição ao NO2 e O3, avaliados em cada trimestre da gestação, e a idade gestacional, o peso, o comprimento, a CC ao nascer e o crescimento do polo cefálico fetal entre o terceiro trimestre e o parto. A exposição ao NO2 e MP10 no ano prévio à concepção influenciou na chance de ser do sexo feminino, ou seja, para cada aumento de 1 unidade do poluente do NO2, constatou-se um aumento de 10% na chance de ser do sexo feminino (Razão de chances (RC) = 1,100; intervalo de confiança (IC) de 95% = 1,040, 1,164; p = 0,001). Em relação ao MP10, para cada aumento de 1 unidade desse poluente, observou-se um aumento de 18 % na chance de ser do sexo feminino (RC = 1,176; IC de 95% = 1,054, 1,311; p = 0,004). Conclusão: Nossos resultados sugerem que, no ambiente de São Paulo, a exposição à poluição no ano prévio à concepção esteve associada à determinação do sexo do RN / Background: Ambient pollution may lead to adverse obstetric outcomes, such as premature birth and low birth weight. Objectives: To determine the influence of maternal air pollution exposure on sex ratio, on birth outcomes and on the growth curve of cephalic pole between the third trimester and the birth. Methods: ProcriAR, a prospective cohort study of 371 pregnant women, was conducted in the city of São Paulo. Nitrogen dioxide (NO2) and ozone (O3) were measured during each trimester using passive personal monitors. At the same time, NO2 and particulate matter lower than 10 Micro m (PM10) were measured by a fixed station. We evaluated the gestational age, birth weight, birth lenght, head circumference, newborn sex and the growth curve of cephalic pole between the third trimester and the birth. When the outcome variable was continuous, multivariate analysis was performed, controlling for gestational age, newborn sex, maternal age at conception, body mass index, parity, smoking, alcohol consumption, race, highest education level completed, marital status, umbilical artery pulsatility values at third trimester and type of delivery for the outcome head circumference. We used multiple logistic regression models to evaluate the association of being female based on a quantitative increase in pollutant concentration, controlling for maternal age at conception, parity and smoking. Results: Elevated exposure to pollutants NO2 and PM10 were associated with increased odds of being female. Each unit increase of NO2 exposure increased the odds of being female by 10% (odds ratio (OR) = 1,100, 95% confidence interval (CI) = 1,040, 1,164; p = 0,001) and each unit increase of PM10 increased by 18% (OR = 1,176, 95% CI 1,054, 1,311, p = 0,004). Conclusion: In São Paulo, maternal exposure to pollutants prior to conception was significantly associated with the odds of being female