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1.
Am J Bot ; 107(4): 587-598, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32227341

RESUMO

PREMISE: Variation in local density and sex ratio in dioecious plants can affect mating success through the actions of pollen vectors, principally generalist insects or wind. Increased density and male-biased sex ratios should promote pollen transfer and seed production, but their combined effects have not been investigated for ambophilous species, which exhibit both insect and wind pollination. METHODS: We manipulated density (low vs. high) and sex ratio (1:1 vs. 3:1 male-biased) in arrays of dioecious ambophilous Thalictrum pubescens. We quantified visitation rates and foraging times to examine whether pollinators exhibited sex-specific preferences and determined the seed set of arrays. RESULTS: Pollinators visited more plants per foraging bout at high than low density. Visitation rates and foraging times of visitors were greater for male than for female plants but did not depend on the density or sex ratio of arrays. However, whereas solitary bees displayed a strong preference for males, hover flies were indifferent to plant sex phenotype. Solitary bees also visited significantly more plants per foraging bout than hover flies. There was a significant interaction between density and sex ratio on seed set. At low density, seed set was greater for 3:1 than for 1:1 arrays, but at high density the opposite pattern occurred. CONCLUSIONS: The demographic factors we investigated had complex influences on pollinator foraging behavior and patterns of seed set. Several factors may explain our results, including the influence of density and sex ratio on pollen export from arrays, grooming by pollinators, and the contribution of wind pollination.


Assuntos
Magnoliopsida , Polinização , Animais , Abelhas , Feminino , Flores , Insetos , Masculino , Pólen , Razão de Masculinidade
2.
PLoS One ; 15(2): e0228374, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32074110

RESUMO

Asiatic lions (Panthera leo persica) are an icon of conservation success, yet their status is inferred from total counts that cannot account for detection bias and double counts. With an effort of 4,797 km in 725 km2 of western Gir Protected Area, India, we used polygon search based spatially explicit capture recapture framework to estimate lion density. Using vibrissae patterns and permanent body marks we identified 67 lions from 368 lion sightings. We conducted distance sampling on 35 transects with an effort of 101.5 km to estimate spatial prey density using generalized additive modeling (GAM). Subsequently, we modeled lion spatial density with prey, habitat characteristics, anthropogenic factors and distance to baiting sites. Lion density (>1-year-old lions) was estimated at 8.53 (SE 1.05) /100 km2 with lionesses having smaller movement parameter (σ = 2.55 km; SE 0.12) compared to males (σ = 5.32 km; SE 0.33). Detection corrected sex ratio (female:male lions) was 1.14 (SE 0.02). Chital (Axis axis) was the most abundant ungulate with a density of 63.29 (SE 10.14) as determined by conventional distance sampling (CDS) and 58.17 (SE 22.17)/km2 with density surface modeling (DSM), followed by sambar (Rusa unicolor) at 3.84 (SE 1.07) and 4.73 (SE 1.48)/km2 estimated by CDS and DSM respectively. Spatial lion density was best explained by proximity to baiting sites and flat valley habitat but not as much by prey density. We demonstrate a scientifically robust approach to estimate lion abundance, that due to its spatial context, can be useful for management of habitat and human-lion interface. We recommend this method for lion population assessment across their range. High lion densities in western Gir were correlated with baiting. The management practice of attracting lions for tourism can perturb natural lion densities, disrupt behavior, lion social dynamics and have detrimental effects on local prey densities.


Assuntos
Conservação dos Recursos Naturais , Demografia/estatística & dados numéricos , Ecossistema , Leões/fisiologia , Dinâmica Populacional , Animais , Comportamento Alimentar , Feminino , Florestas , Índia , Masculino , Comportamento Predatório , Razão de Masculinidade
3.
Forensic Sci Int ; 307: 110104, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31918163

RESUMO

When adult flies are collected at indoor crime scenes, the question of their origin arises, i.e., whether they originated from the outdoors, coming in to oviposit on the body, or if they developed through the larval and pupal stages from eggs laid on the body. This is particularly important if no empty puparia were collected, potentially because they were overlooked, with a consequent impact on the accuracy of the minimum post-mortem interval estimation. This study used two methods to determine if flies sampled in various experimental conditions and at an actual crime scene were wild flies attracted to the body or had developed on the body, i.e., through the assessment of: (1) wing fray and; (2) sex ratio. A template was created to measure the amount of wing fray damage quantitatively in a simple, rapid and efficient manner. The experiments demonstrated that by combining the two methods it is possible to establish the origin of a population of adult flies at a crime scene.


Assuntos
Dípteros/anatomia & histologia , Entomologia Forense/métodos , Asas de Animais/anatomia & histologia , Animais , Comportamento Alimentar , Feminino , Processamento de Imagem Assistida por Computador , Larva , Masculino , Microscopia , Mudanças Depois da Morte , Pupa , Razão de Masculinidade
4.
PLoS Negl Trop Dis ; 14(1): e0007995, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31995564

RESUMO

BACKGROUND: Bangladesh, India, and Nepal aim for the elimination of Visceral Leishmaniasis (VL), a systemic parasitic infectious disease, as a public health problem by 2020. For decades, male patients have comprised the majority of reported VL cases in this region. By comparing this reported VL sex ratio to the one observed in population-based studies conducted in the Indian subcontinent, we tested the working hypothesis that mainly socio-cultural gender differences in healthcare-seeking behavior explain this gender imbalance. METHODOLOGY/PRINCIPAL FINDINGS: We compared the observed sex ratio of male versus female among all VL cases reported by the health system in Nepal and in the two most endemic states in India with that observed in population-based cohort studies in India and Nepal. Also, we assessed male sex as a potential risk factor for seroprevalence at baseline, seroconversion, and VL incidence in the same population-based data. The male/female ratio among VL cases reported by the health systems was 1.40 (95% CI 1.37-1.43). In the population cohort data, the age- and study site-adjusted male to female risk ratio was 1.27 (95% CI 1.08-1.51). Also, males had a 19% higher chance of being seropositive at baseline in the population surveys (RR 1.19; 95% CI 1.11-1.27), while we observed no significant difference in seroconversion rate between both sexes at the DAT cut-off titer defined as the primary endpoint. CONCLUSIONS/SIGNIFICANCE: Our population-based data show that male sex is a risk factor for VL, and not only as a socio-cultural determinant. Biological sex-related differences likely play an important role in the pathogenesis of this disease.


Assuntos
Notificação de Doenças/estatística & dados numéricos , Leishmaniose Visceral/diagnóstico , Adolescente , Adulto , Criança , Pré-Escolar , Instalações de Saúde , Humanos , Incidência , Lactente , Leishmaniose Visceral/epidemiologia , Masculino , Pessoa de Meia-Idade , Estudos Soroepidemiológicos , Razão de Masculinidade , Adulto Jovem
5.
Bull Entomol Res ; 110(1): 115-122, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31138336

RESUMO

The Chinese white pine beetle Dendroctonus armandi (Coleoptera: Scolytinae) typically displays bivoltinism at altitudes below 1700 m in the Qinling Mountains, China. The periods of host colonization and larval overwintering are two important phases in the life cycle of bark beetles, as it is during these periods that they have to contend with host plant defences and periods of intense cold, respectively. Although during different seasons, the females and males of Chinese white pine beetles show varying tolerances to host plant terpenoids, the sex ratio and survival physiology condition of the two beetle generations are unknown. We investigated the sex ratio of individuals, and also examined the body mass, energy stores, and detoxication enzymes of males and females in each of the two generations in order to determine the overall population stability of each generation. We identified a female-biased sex ratio among adults in both generations. Furthermore, patterns of body mass, energy stores, and detoxication enzymes were found to differ between the two sexes and two seasons. Compared with the males, the females have a larger body mass and higher amounts of stored lipids, which are assumed to be adaptations designed to overcome host resistance and facilitate subsequent oviposition.


Assuntos
Besouros/fisiologia , Estações do Ano , Razão de Masculinidade , Animais , Sistema Enzimático do Citocromo P-450/metabolismo , Metabolismo Energético , Feminino , Masculino
6.
Chemosphere ; 238: 124563, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31454744

RESUMO

Nanoplastic pollution is widespread and persistent across global water systems and can cause a negative effect on aquatic organisms, especially the zooplankter which is the keystone of the food chain. The present study uses RNA sequencing to assess the global change in gene expression caused by 21 days of exposure to 75 nm polystyrene (PS) nanoplastics on Daphnia pulex, a model organism for ecotoxicity. With the threshold value at P value < 0.05 and fold change >2, 244 differentially expressed genes were obtained. Combined with real-time PCR validation of several selected genes, our results indicated that a distinct expression profile of key genes, including downregulated trehalose transporter, trehalose 6-phosphate synthase/phosphatase, chitinase and cathepsin-L as well as upregulated doublesex 1 and doublesex and mab-3 related transcription factor-like protein, contributed to the toxic effects of chronic nanoplastic exposure on Daphnia, such as slowed growth, subdued reproductive ability and reproductive pattern shifting. Our study also showed that chronic exposure to nanoplastic changed the sex ratio of D. pulex neonates. By integrating the gene expression pattern in an important model organism, this study gained insight into the molecular mechanisms of the toxic effect of chronic PS nanoplastic exposure on D. pulex, which may also extend to other nanoplastics or aquatic animals.


Assuntos
Daphnia/efeitos dos fármacos , Microplásticos/toxicidade , Poliestirenos/toxicidade , Reprodução/efeitos dos fármacos , Razão de Masculinidade , Poluentes Químicos da Água/toxicidade , Animais , Organismos Aquáticos/efeitos dos fármacos , Daphnia/genética , Cadeia Alimentar , Expressão Gênica/efeitos dos fármacos , Humanos , Recém-Nascido , Análise de Sequência de RNA
7.
Arch Insect Biochem Physiol ; 103(3): e21652, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31845410

RESUMO

Agricultural pest control using genetic-based methods provides a species-specific and environmentally harmless way for population suppression of fruit flies. One way to improve the efficiency of such methods is through self-limiting, female-eliminating approaches that can alter an insect populations' sex ratio toward males. In this microreview, we summarize recent advances in synthetic sex ratio distorters based on X-chromosome shredding that can induce male-biased progeny. We outline the basic principles to guide the efficient design of an X-shredding system in an XY heterogametic fruit fly species of interest using CRISPR/Cas gene editing, newly developed computational tools, and insect genetic engineering. We also discuss technical aspects and challenges associated with the efficient transferability of this technology in fruit fly pest populations, toward the potential use of this new class of genetic control approaches for pest management purposes.


Assuntos
Sistemas CRISPR-Cas , Dípteros/genética , Controle de Insetos/métodos , Controle Biológico de Vetores/métodos , Razão de Masculinidade , Animais , Feminino , Edição de Genes , Masculino
8.
Autoimmun Rev ; 19(1): 102423, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31733367

RESUMO

PURPOSE: AIDs may disproportionately impact specific racial groups, but autoimmune (AID) prevalence information by minority racial group is sparse for many AIDs. The objective of this analysis was to supplement previously published AID prevalence rates by providing information on race rate ratios (minority race populations compared to Caucasian populations) in the United States. Preliminary to estimating race rate ratios, contemporary US-specific, health care utilization-based AID prevalence rates and female-to-male ratios were estimated and compared to previously published AID prevalence rates. METHODS: We used a large national electronic medical record database of 52 million individuals to estimate age-adjusted direct standardized rates for 22 AIDs for 2010 through 2016 by gender, race, and US census division. These were compared to previously published estimates. RESULTS: Female-to-male ratios were comparable with published studies. Almost all observed Multiracial AID rates were significantly higher than Caucasian rates, as well as 9 of 22 AID rates observed among Native Americans and 8 of 22 AID rates estimated among African-American patients. Regional variation was noted: highest African-American systemic lupus erythematosus rates were observed in the West North Central and South Atlantic divisions, highest African-American multiple sclerosis rates in the South Atlantic and Pacific divisions, and highest Native American rheumatoid arthritis rates in the West North Central, Mountain, and Pacific divisions. CONCLUSIONS: Substantial AID heterogeneity exists by race and by geographic area. An important research area is further exploring factors related to heterogeneity such as potential interactions between genetic susceptibility and environmental factors.


Assuntos
Doenças Autoimunes/etnologia , Doenças Autoimunes/epidemiologia , Lúpus Eritematoso Sistêmico/etnologia , Lúpus Eritematoso Sistêmico/epidemiologia , Afro-Americanos , Feminino , Geografia Médica , Humanos , Masculino , Prevalência , Razão de Masculinidade , Estados Unidos/epidemiologia , Estados Unidos/etnologia
9.
Psicol. ciênc. prof ; 39(2,n.esp): 45-58, ago.-nov. 2019. tab
Artigo em Português | LILACS, Index Psicologia - Periódicos técnico-científicos | ID: biblio-1049951

RESUMO

Considerando que a Psicologia Social auxilia para que práticas e ações sociais sejam problematizadas, este estudo tem como objetivo evidenciar como os sentidos de si e do Outro identificados em narrativas de homens autores de violência sustentam e justificam a ação violenta cometida. Para tal, quatro narrativas de homens participantes de um grupo reflexivo de autores de violência em uma cidade do sul do Brasil foram utilizadas e analisadas por meio da análise temática das narrativas. Os resultados revelaram que os homens, depositaram a justificativa da sua "agressividade" em um Outro. E este Outro, por muitas vezes, pôde ser identificado como uma referência aos vínculos sociais e aos sentidos do ser homem. Foi possível constatar que o modo como os sujeitos percebem suas trajetórias de vida, permeadas pelas experiências de resistência e construção frente a um contexto onde, segundo eles, havia falta de carinho, agressividade e ausência, sobretudo, paterna, parece construir um cenário propício para a emersão da violência. A partir disso, ressalta-se a importância que os participantes dão aos vínculos significativos sociais e à dicotomia do ser homem/ser mulher, bem como à forma pela qual essa dinâmica relacional mergulha em preceitos e valores éticos e morais. Isto, por sua vez, leva-nos a pensar como o olhar da Psicologia Social Crítica auxilia para que problemáticas sociais sejam identificadas e postas à tona, assim como outros modos de existência tanto para homens como mulheres possam emergir e ser visibilizados. Desta forma, problematizando gênero, seja possível a reconstrução e transformação social...(AU)


Considering that Social Psychology assists so that social practices and actions can be problematized, this study aims to show how the senses of the self and the Other identified in narratives of men who commit violence sustain and justify their violent actions. To that end, four narratives of men who participated in a reflective group of men who committed violence in a city in southern Brazil were used and analyzed through the thematic analysis of the narratives. The results revealed that men justified their "aggressiveness" in the Other. And this Other, for many times, could be identified as a reference to the social bonds and the senses of the human being. It was possible to verify that the way in which the individuals perceive their life trajectories, permeated by the experiences of resistance and construction before a context where, according to them, there was a lack of affection, aggression and absence, especially, paternal, seemed to construct a scenario conducive to the emergence of violence. From this, it is highlighted the importance that the participants give to the significant social bonds and to the dichotomy of being male/female, as well as to the way in which this relational dynamic plunge into ethical and moral precepts and values. This, in turn, leads us to think how the look of Critical Social Psychology helps social problems to be identified and raised, just as other modes of existence for both men and women can emerge and be seen. In this way, problematizing gender makes possible to reconstruct and socially transform...(AU)


Teniendo en cuenta que la psicología social ayuda a problematizar las prácticas y acciones sociales, este estudio tiene como objetivo resaltar cómo los sentidos de uno mismo y del Otro identificados en las narraciones de los autores de violencia masculinos sostienen y justifican la acción violenta cometida. Con este fin, se utilizaron y analizaron cuatro narrativas de hombres que participaban en un grupo reflexivo de perpetradores de violencia en una ciudad del sur de Brasil a través del análisis temático de las narrativas. Los resultados revelaron que los hombres depositaron la justificación de su "agresividad" en un Otro. Y este Otro, muchas veces, podría identificarse como una referencia a los lazos sociales y los sentidos del ser humano. Fue posible verificar que la forma en que los sujetos perciben sus trayectorias de vida, impregnada por las experiencias de resistencia y construcción que enfrentan en un contexto donde, según ellos, había falta de afecto, agresión y, sobre todo, ausencia paterna, parecían construir un escenario favorable para el surgimiento de la violencia. A partir de esto, se enfatiza la importancia que los participantes le dan a los lazos sociales significativos y la dicotomía de ser hombre/ser mujer, así como la forma en que esta dinámica relacional se sumerge en preceptos y valores éticos y morales. Esto, a su vez, nos lleva a preguntarnos cómo el aspecto de la Psicología Social Crítica ayuda a identificar los problemas sociales y los trae a la luz, así como también otros modos de existencia para que hombres y mujeres emerjan y se hagan visibles. Así, problematizando el género, sea posible la reconstrucción y transformación social...(AU)


Assuntos
Humanos , Masculino , Adulto , Psicologia Social , Razão de Masculinidade , Narração , Agressão , Violência contra a Mulher , Narrativa Pessoal , Exposição à Violência
10.
Parasit Vectors ; 12(1): 489, 2019 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-31623642

RESUMO

BACKGROUND: Ticks and tick-borne diseases are a major impediment to livestock production worldwide. Cattle trade and transnational transhumance create risks for the spread of ticks and tick-borne diseases and threaten cattle production in the absence of an effective tick control program. Few studies have been undertaken on cattle ticks in the Central African region; therefore, the need to assess the occurrence and the spatial distribution of tick vectors with the aim of establishing a baseline for monitoring future spread of tick borne-diseases in the region is urgent. RESULTS: A total of 7091 ixodid ticks were collected during a countrywide cross-sectional field survey and identified using morphological criteria. Of these, 4210 (59.4%) ticks were Amblyomma variegatum, 1112 (15.6%) Rhipicephalus (Boophilus) microplus, 708 (10.0%) Rhipicephalus (Boophilus) decoloratus, 28 (0.4%) Rhipicephalus (Boophilus) annulatus, 210 (3.0%) Hyalomma rufipes, 768 (10.8%) Hyalomma truncatum, and 19 (0.3%) Rhipicephalus sanguineus. Three ticks of the genus Hyalomma spp. and 33 of the genus Rhipicephalus spp. were not identified to the species level. Cytochrome c oxidase subunit 1 (cox1) gene sequencing supported the data from morphological examination and led to identification of three additional species, namely Hyalomma dromedarii, Rhipicephalus sulcatus and Rhipicephalus pusillus. The finding of the invasive tick species R. microplus in such large numbers and the apparent displacement of the indigenous R. decoloratus is highly significant since R. microplus is a highly efficient vector of Babesia bovis. CONCLUSIONS: This study reports the occurrence and current geographical distribution of important tick vectors associated with cattle in Cameroon. It appears that R. microplus is now well established and may be displacing native Rhipicephalus (Boophilus) species, such as R. decoloratus. This calls for an urgent response to safeguard the livestock sector in western central Africa.


Assuntos
Doenças dos Bovinos/epidemiologia , Doenças dos Bovinos/parasitologia , Infestações por Carrapato/veterinária , Carrapatos/fisiologia , Agricultura , Animais , Camarões/epidemiologia , Bovinos , Sequência Consenso , Estudos Transversais , Ciclo-Oxigenase 1/genética , Demografia , Feminino , Masculino , Filogenia , Prevalência , Alinhamento de Sequência/veterinária , Razão de Masculinidade , Infestações por Carrapato/epidemiologia , Infestações por Carrapato/parasitologia , Doenças Transmitidas por Carrapatos/epidemiologia , Doenças Transmitidas por Carrapatos/veterinária , Carrapatos/classificação , Carrapatos/crescimento & desenvolvimento
11.
Oecologia ; 191(3): 555-564, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31624957

RESUMO

Given that sperm production can be costly, theory predicts that males should optimally adjust the quantity and/or quality of their sperm in response to their social environment to maximize their paternity success. Although experiments demonstrate that males can alter their ejaculates in response to manipulations of the social environment and studies show that ejaculate traits covary with social environment across populations, it is unknown whether individual variation in sperm traits corresponds to natural variation found within wild populations. Using an island population of brown anole lizards (Anolis sagrei), we tested the prediction that sperm traits (sperm count, sperm morphology, sperm velocity) respond to natural variation in the risk of sperm competition, as inferred from the local density and operational sex ratio (OSR) of conspecifics. We found that males living in high-density areas of the island produced relatively larger sperm midpieces, smaller sperm heads, and lower sperm counts. Sperm traits were unrelated to OSR after accounting for the covariance between OSR and density. Our findings broaden the implications of sperm competition theory to intrapopulation social environment variation by showing that sperm count and sperm morphology vary with fine-scale differences in density within a single wild population.


Assuntos
Lagartos , Animais , Ilhas , Masculino , Fenótipo , Razão de Masculinidade , Comportamento Sexual Animal , Espermatozoides
12.
PLoS Biol ; 17(10): e3000438, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31600190

RESUMO

Microbial endosymbiosis is widespread in animals, with major ecological and evolutionary implications. Successful symbiosis relies on efficient vertical transmission through host generations. However, when symbionts negatively affect host fitness, hosts are expected to evolve suppression of symbiont effects or transmission. Here, we show that sex chromosomes control vertical transmission of feminizing Wolbachia endosymbionts in the isopod Armadillidium nasatum. Theory predicts that the invasion of an XY/XX species by cytoplasmic sex ratio distorters is unlikely because it leads to fixation of the unusual (and often lethal or infertile) YY genotype. We demonstrate that A. nasatum X and Y sex chromosomes are genetically highly similar and that YY individuals are viable and fertile, thereby enabling Wolbachia spread in this XY-XX species. Nevertheless, we show that Wolbachia cannot drive fixation of YY individuals, because infected YY females do not transmit Wolbachia to their offspring, unlike XX and XY females. The genetic basis fits the model of a Y-linked recessive allele (associated with an X-linked dominant allele), in which the homozygous state suppresses Wolbachia transmission. Moreover, production of all-male progenies by infected YY females restores a balanced sex ratio at the host population level. This suggests that blocking of Wolbachia transmission by YY females may have evolved to suppress feminization, thereby offering a whole new perspective on the evolutionary interplay between microbial symbionts and host sex chromosomes.


Assuntos
Isópodes/genética , Cromossomos Sexuais , Processos de Determinação Sexual , Simbiose/genética , Wolbachia/fisiologia , Alelos , Animais , Feminino , Genótipo , Homozigoto , Isópodes/microbiologia , Masculino , Modelos Genéticos , Característica Quantitativa Herdável , Razão de Masculinidade
13.
Evol Psychol ; 17(3): 1474704919874680, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31564134

RESUMO

Previous research suggests that binge drinking among young men serves as a "costly signal" to potential mates, such that the binge drinker is capable of bearing the harmful consequences of alcohol consumption. Here, we propose that binge drinking among young adults is conditionally dependent upon the signaler's willingness to take risks, which is influenced by the local operational sex ratio (OSR). Using archived binge drinking estimates from 2009 to 2012 and Census Bureau records of OSRs, we tested the relationship between OSR and binge drinking rates at the county level across 3,143 U.S. counties against hypotheses drawn from evolutionary theory. Results from our mixed-effects models revealed that a higher overall OSR (i.e., more eligible men compared to women) was associated with higher male binge drinking rates but lower female binge drinking rates. A higher OSR particularly in the 20-29 and 50+ age groups predicted higher male binge drinking rates but lower female binge drinking rates. Our findings generally support predictions derived from evolutionary theory and suggest that binge drinking may function as a costly sexual signal, conditionally regulated by age and the local sex ratio.


Assuntos
Bebedeira/epidemiologia , Assunção de Riscos , Razão de Masculinidade , Comportamento Social , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fatores Sexuais , Estados Unidos/epidemiologia , Adulto Jovem
14.
Parasit Vectors ; 12(1): 485, 2019 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-31619284

RESUMO

BACKGROUND: Parasite traits associated with transmission success, such as the number of infective stages released from the host, are expected to be optimized by natural selection. However, in the trematode parasite Schistosoma mansoni, a key transmission trait, i.e. the number of cercariae larvae shed from infected Biomphalaria spp. snails, varies significantly within and between different parasite populations and selection experiments demonstrate that this variation has a strong genetic basis. In this study, we compared the transmission strategies of two laboratory schistosome population and their consequences for their snail host. METHODS: We infected inbred Biomphalaria glabrata snails using two S. mansoni parasite populations (SmBRE and SmLE), both isolated from Brazil and maintained in the laboratory for decades. We compared life history traits of these two parasite populations by quantifying sporocyst growth within infected snails (assayed using qPCR), output of cercaria larvae and impact on snail host physiological response (i.e. hemoglobin rate, laccase-like activity) and survival. RESULTS: We identified striking differences in virulence and transmission between the two studied parasite populations. SmBRE (low shedder (LS) parasite population) sheds very low numbers of cercariae and causes minimal impact on the snail physiological response (i.e. laccase-like activity, hemoglobin rate and snail survival). In contrast, SmLE (high shedder (HS) parasite population) sheds 8-fold more cercariae (mean ± SE cercariae per shedding: 284 ± 19 vs 2352 ± 113), causes high snail mortality and has strong impact on snail physiology. We found that HS sporocysts grow more rapidly inside the snail host, comprising up to 60% of cells within infected snails, compared to LS sporocysts, which comprised up to 31%. Cercarial production is strongly correlated to the number of S. mansoni sporocyst cells present within the snail host tissue, although the proportion of sporocyst cells alone does not explain the low cercarial shedding of SmBRE. CONCLUSIONS: We demonstrated the existence of alternative transmission strategies in the S. mansoni parasite consistent with trade-offs between parasite transmission and host survival: a "boom-bust" strategy characterized by high virulence, high transmission and short duration infections and a "slow and steady" strategy with low virulence, low transmission but long duration of snail host infections.


Assuntos
Biomphalaria/parasitologia , Schistosoma mansoni/fisiologia , Schistosoma mansoni/patogenicidade , Esquistossomose mansoni/parasitologia , Esquistossomose mansoni/transmissão , Animais , Biomphalaria/fisiologia , Brasil , Cercárias , Estudos de Coortes , Cricetinae , DNA de Helmintos/química , DNA de Helmintos/isolamento & purificação , Vetores de Doenças , Feminino , Hemoglobinas/análise , Hemolinfa/química , Hemolinfa/enzimologia , Humanos , Lacase/análise , Masculino , Mesocricetus , Reação em Cadeia da Polimerase Multiplex , Reação em Cadeia da Polimerase em Tempo Real , Schistosoma mansoni/crescimento & desenvolvimento , Razão de Masculinidade , Virulência
15.
PLoS Pathog ; 15(9): e1007936, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31504075

RESUMO

Wolbachia are the most widespread maternally-transmitted bacteria in the animal kingdom. Their global spread in arthropods and varied impacts on animal physiology, evolution, and vector control are in part due to parasitic drive systems that enhance the fitness of infected females, the transmitting sex of Wolbachia. Male killing is one common drive mechanism wherein the sons of infected females are selectively killed. Despite decades of research, the gene(s) underlying Wolbachia-induced male killing remain unknown. Here using comparative genomic, transgenic, and cytological approaches in fruit flies, we identify a candidate gene in the eukaryotic association module of Wolbachia prophage WO, termed WO-mediated killing (wmk), which transgenically causes male-specific lethality during early embryogenesis and cytological defects typical of the pathology of male killing. The discovery of wmk establishes new hypotheses for the potential role of phage genes in sex-specific lethality, including the control of arthropod pests and vectors.


Assuntos
Prófagos/genética , Prófagos/patogenicidade , Wolbachia/patogenicidade , Wolbachia/virologia , Animais , Animais Geneticamente Modificados , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/fisiologia , Drosophila/embriologia , Drosophila/microbiologia , Drosophila/virologia , Drosophila melanogaster/embriologia , Drosophila melanogaster/microbiologia , Drosophila melanogaster/virologia , Feminino , Genes Letais , Genes Virais , Interações entre Hospedeiro e Microrganismos/genética , Interações entre Hospedeiro e Microrganismos/fisiologia , Masculino , Prófagos/fisiologia , Razão de Masculinidade , Simbiose/genética , Simbiose/fisiologia , Proteínas Virais/genética , Proteínas Virais/fisiologia
16.
Genetica ; 147(3-4): 249-258, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31392547

RESUMO

Throughout the world, there is a male-bias in the sex ratio at birth (SRB). It is not known whether this phenomenon has a genetic basis, though there is tentative evidence from genealogical and genomic studies that it may have. It has been proposed that the higher rate of male childhood mortality in humans is linked to the male-bias in SRB through parental investment, but this may only apply to facultative not genetic sex ratio adjustment. In previous population genetic models, elevated mortality in one sex (prior to breeding) has been shown not to affect the SRB, but these models did not consider the role of replacement births (i.e. births that only occur because a sibling died prematurely). In a set of population genetic modelling simulations, in which sex ratio is controlled by an autosomal gene expressed in the male line, this study shows that when there is replacement of dead offspring, this leads to a sustained bias in the SRB in the direction of the sex suffering the highest mortality. In the example of higher male mortality, this occurs, because replacement offspring are disproportionately drawn from fathers who were genetically predisposed to have initially had sons (because sons were more likely to die prematurely), and more likely to pass on male-biasing alleles to replacement offspring. To test the empirical basis for replacement births, an analysis of birth data from the Demographic and Health Survey program was conducted, which shows that parents do indeed tend to replace children who die prematurely.


Assuntos
Razão de Masculinidade , Criança , Mortalidade da Criança , Demografia , Características da Família , Feminino , Genótipo , Humanos , Lactente , Mortalidade Infantil , Masculino
17.
Zoology (Jena) ; 135: 125688, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31383294

RESUMO

Sexual size dimorphism (SSD) is common among mammals, with males typically being larger than females, as a product of sex-specific differences in growth rate and growth duration. The Musteloidea, however, exhibit a hypo-allometric reduction in SSD with increasing body size (contrary to Rensch's rule). A variety of extrinsic factors can affect juvenile growth rates and end body size, where one sex may demonstrate greater vulnerability than the other towards a specific factor, moderating patterns and degrees of SSD. Here, we analyse how male and female European badgers (Meles meles) differ in their somatic growth patterns. We compare the sex-specific growth curves across a range of somatic parameters and investigate what extrinsic (social and environmental) factors affect cub growth rates during the first 2 years of life leading to their sexual-dimorphic adult sizes. We found that average male final size of all measurements was significantly larger than those of females. Although male and female weanling cubs had similar body sizes, growth curves diverged significantly from ca. 11 months onwards due to continuous rapid growth of males versus slowing female growth. Consequently, females always concluded growth earlier than did males. In both sexes, extremities ceased to grow at an earlier age than did body length and zygomatic arch width. All badger cubs were impacted by their social environment as well as by weather conditions; however, male cubs were more sensitive to social factors, remaining smaller in social groups with more adult males present, whereas female final size was predominantly affected by weather and associated food availability. We discuss how extrinsic parameters can moderate patterns of SSD in the context of the differential equilibrium model.


Assuntos
Tamanho Corporal , Crescimento e Desenvolvimento/fisiologia , Mustelidae/anatomia & histologia , Mustelidae/crescimento & desenvolvimento , Caracteres Sexuais , Animais , Tamanho Corporal/fisiologia , Feminino , Masculino , Densidade Demográfica , Razão de Masculinidade , Fatores de Tempo , Tempo (Meteorologia)
18.
BMC Health Serv Res ; 19(1): 595, 2019 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-31443658

RESUMO

BACKGROUND: An adequate and qualified health workforce is critical for achieving Universal Health Coverage (UHC) and responding to the Sustainable Development Goals (SDGs). Frontline health workers who are mainly women, play important roles in responses to crisis. Despite women making up the vast majority of the health workforce, men occupy the majority of leadership positions. This study aims to understand the career progression of female health workers by exploring how gender norms influence women's upward career trajectories. METHODS: A qualitative methodology deployed a life history approach was used to explore the perspectives and experiences of health workers in Battambang province, Cambodia. Twenty male and female health managers were purposively selected based five criteria: age 40 and above, starting their career during 1980s or 1990s, clinical skills, management roles and evidence of career progression. Themes and sub-themes were developed based on available data and informed by Tlaiss's (2013) social theory framework in order to understand how gender norms, roles and relations shape the career of women in the health industry. RESULTS: The findings from life histories show that gender norms shape men's and women's career progression at different levels of society. At the macro level, social, cultural, political, and gender norms are favorably changing by allowing more women to enter medical education; however, leadership is bias towards men. At the meso organziational level, empowerment of women in the health sector has increased with the support of gender working groups and women's associations. At the micro individual level, female facility managers identified capacity and qualifications as important factors in helping women to obtain leadership positions. CONCLUSION: While Cambodia has made progress, it still has far to go to achieve equality in leadership. Promoting gender equity in leadership within the health workforce requires a long vision and commitment along with collaboration among different stakeholders and across social structures. If more women are not able to obtain leadership roles, the goals of having an equitable health system, promoting UHC, and responding to the SDGs milestones by leaving no one behind will remain unattainable objectives.


Assuntos
Mobilidade Ocupacional , Pessoal de Saúde/estatística & dados numéricos , Liderança , Mulheres Trabalhadoras/estatística & dados numéricos , Camboja , Educação Médica , Feminino , Mão de Obra em Saúde/estatística & dados numéricos , Humanos , Masculino , Razão de Masculinidade
19.
J Cosmet Sci ; 70(4): 197-207, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31441773

RESUMO

Studies on topical repellent efficacy conducted with caged mosquitoes in the laboratory are important to both the development and regulation of insect repellents. Guidelines for laboratory studies stipulate specific densities, sex ratios, and biting rates, whereas those for field studies are governmentally required before a promising repellent can be registered for human use. These protocols stipulate minimum biting rates alone. Relatively little is known, however, about the influence of mosquito density and sex ratio on their biting propensity, either in the field or laboratory. Using Environmental Protection Agency guidelines for cage testing, we studied the influence of mosquito density and sex ratio in laboratory repellency tests of the biopesticide Ethyl butylacetylaminopropionate (IR3535™) (20%) against three mosquito species (Aedes aegypti, Anopheles aquasalis, and Culex quinquefasciatus). DEET [3-(N-acetyl-N-butyl) aminopropionic acid ethyl ester] (20%) in a laboratory prepared formulation was used as a comparison article. Studies were conducted by trained investigators at the BioAgri Laboratories in Brazil. We found that higher mosquito density generally decreased protection time, but that the influence of sex ratio was more complex. The presence of male mosquitoes increased protection times against Aedes and Anopheles perhaps because mate-seeking males interfered with female feeding. Interestingly, by contrast, protection times decreased against Culex in the presence of males. Such considerations may potentially assist in improving the match between cage and field testing under a broader range of conditions that permit more accurate labeling of repellents for safe and effective use by consumers.


Assuntos
Aedes , Anopheles , Culex , Repelentes de Insetos/farmacologia , Animais , Feminino , Repelentes de Insetos/química , Masculino , Propionatos , Razão de Masculinidade , Estados Unidos
20.
J Anim Ecol ; 88(9): 1417-1427, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31286510

RESUMO

Sex in crocodilians is not determined by chromosomes, but by egg incubation temperature, where different temperatures produce different clutch sex ratios. Two patterns have been proposed to describe these changes in sex ratios: a 100% female proportion at low and high temperatures with male predominance at intermediate ones (FMF) or a simpler pattern with a single female-to-male transition (FM). Over the last three decades, researchers have provided empirical information to support either of these two patterns in different species; however, no consensus has been reached partly because data have not been analysed as a whole. Here, we aimed at gathering the existing data on these patterns to provide models of temperature-dependent sex determination in those crocodilians studied so far. Potentially relevant publications were searched on Web of Knowledge, Scopus, Scielo and Science Direct. Studies that reported results on the sexual identity of crocodilian hatchlings obtained from constant temperature incubation treatments were considered. Using statistical models varying in their underlying assumptions, we evaluated which sex-determination pattern was best supported for the studied crocodilians and constructed species-specific and latitude-specific models. Based on the 8,458 sexed hatchlings studied throughout 31 studies, we show that the evidence supports a shared FMF pattern in all the crocodilian species for which enough data are available. We find that such pattern changes between species and at different latitudes. These results suggest a lability of the FMF crocodilian sex-determination pattern, a key feature under the present climate change scenario.


Assuntos
Jacarés e Crocodilos , Animais , Feminino , Masculino , Modelos Estatísticos , Razão de Masculinidade , Temperatura
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