Histone epigenetic modifications and their relationship with cancer: a comparative medicine view / Modificações epigenéticas de histonas e sua relação com o câncer: uma visão da medicina comparada

ABSTRACT: Epigenetic modifications have become highly important in the study of cancer pathogenesis due to research showing that changes in the expression of DNA-associated proteins can affect gene expression but may be reversible after treatment. The changing histones are being studied on a large scale in medicine while recent studies also show this relationship in veterinary medicine. Histone deacetylation is related to tumor progression and overexpression of histone deacetylases (HDACs) is responsible for these changes. The silencing of tumor suppressor genes related to epigenetic changes favors tumor progression; however, using HDAC inhibitors has been shown to effectively reverse these histone changes while having anticancer effects. This research provided an overview of comparative medicine between humans and dogs concerning epigenetic changes while showing the physiological mechanisms and the relationship between cancer and epigenetics, specifically regarding histone acetylation and deacetylation. This overview should contribute to a better understanding of epigenetics and cancer and their relationship with new target-molecular therapies in veterinary medicine and the importance of such studies.

RESUMO: Mudanças epigenéticas assumiram importância na patogênese do câncer a partir de pesquisas que mostraram que mudanças na expressão de proteínas associadas ao DNA podem afetar a expressão gênica e podem ser reversíveis após o tratamento. As alterações nas histonas têm sido estudadas em larga escala na medicina, particularmente no câncer de mama, e estudos recentes mostram essa relação também na medicina veterinária. A desacetilação das histonas está relacionada à progressão tumoral e a superexpressão de histonas desacetilases (HDACs) é responsável por essas alterações. O silenciamento de genes supressores de tumor relacionados a alterações epigenéticas favorece a progressão tumoral, entretanto, o uso de inibidores de HDAC é eficaz em reverter as alterações nas histonas e tem efeitos anticâncer. Uma visão da medicina comparada entre humanos e cães em relação às alterações epigenéticas, será o objetivo deste trabalho, mostrando os mecanismos fisiológicos e a relação entre o câncer e a epigenética, especificamente com a acetilação e desacetilação de histonas. Essa visão contribuirá para um melhor entendimento da epigenética e do câncer, bem como a relação com as novas terapias moleculares-alvo na medicina veterinária e a importância dos estudos neste contexto.

Differentially methylated regions identified in bovine embryos are not observed in adulthood

The establishment of epigenetic marks during the reprogramming window is susceptible to environmental influences, and stimuli during this critical stage can cause altered DNA methylation in offspring. In a previous study, we found that low levels of sulphur and cobalt (low S/Co) in the diet offered to oocyte donors altered the DNA methylome of bovine embryos. However, due to the extensive epigenetic reprogramming that occurs during embryogenesis, we hypothesized that the different methylation regions (DMRs) identified in the blastocysts may not maintain in adulthood. Here, we aimed to characterize DMRs previously identified in embryos, in the blood and sperm of adult progenies of two groups of heifers (low S/Co and control). We used six bulls and characterized the DNA methylation levels of KDM2A, KDM5A, KMT2D, and DOT1L genes. Our results showed that all DMRs analysed in both groups and tissues were hypermethylated unlike that noticed in the embryonic methylome profiles. These results suggest that embryo DMRs were reprogrammed during the final stages of de novo methylation during embryogenesis or later in development. Therefore, due to the highly dynamic epigenetic state during early embryonic development, we suggest that is essential to validate the DMRs found in embryos in adult individuals.(AU)

Paternal effects on fetal programming

Paternal programming is the concept that the environmental signals from the sire's experiences leading up to mating can alter semen and ultimately affect the phenotype of resulting offspring. Potential mechanisms carrying the paternal effects to offspring can be associated with epigenetic signatures (DNA methylation, histone modification and non-coding RNAs), oxidative stress, cytokines, and the seminal microbiome. Several opportunities exist for sperm/semen to be influenced during development; these opportunities are within the testicle, the epididymis, or accessory sex glands. Epigenetic signatures of sperm can be impacted during the pre-natal and pre-pubertal periods, during sexual maturity and with advancing sire age. Sperm are susceptible to alterations as dictated by their developmental stage at the time of the perturbation, and sperm and seminal plasma likely have both dependent and independent effects on offspring. Research using rodent models has revealed that many factors including over/under nutrition, dietary fat, protein, and ingredient composition (e.g., macro- or micronutrients), stress, exercise, and exposure to drugs, alcohol, and endocrine disruptors all elicit paternal programming responses that are evident in offspring phenotype. Research using livestock species has also revealed that sire age, fertility level, plane of nutrition, and heat stress can induce alterations in the epigenetic, oxidative stress, cytokine, and microbiome profiles of sperm and/or seminal plasma. In addition, recent findings in pigs, sheep, and cattle have indicated programming effects in blastocysts post-fertilization with some continuing into post-natal life of the offspring. Our research group is focused on understanding the effects of common management scenarios of plane of nutrition and growth rates in bulls and rams on mechanisms resulting in paternal programming and subsequent offspring outcomes. Understanding the implication of paternal programming is imperative as short-term feeding and management decisions have the potential to impact productivity and profitability of our herds for generations to come.(AU)

Biobanks, offspring fitness and the influence of developmental plasticity in conservation biology

Mitigation of the widely known threats to the world's biodiversity is difficult, despite the strategies and actions proposed by international agreements such as the United Nations Framework Convention on Climate Change (UNFCCC) and the Convention on Biological Diversity (CBD). Nevertheless, many scientists devote their time and effort to finding and implementing various solutions to the problem. One potential way forward that is gaining popularity involves the establishment of biobank programs aimed at preserving and storing germplasm from threatened species, and then using it to support the future viability and health of threatened populations. This involves developing and using assisted reproductive technologies to achieve their goals. Despite considerable advances in the effectiveness of reproductive technologies, differences between the reproductive behavior and physiology of widely differing taxonomic groups mean that this approach cannot be applied with equal success to many species. Moreover, evidence that epigenetic influences and developmental plasticity, whereby it is now understood that embryonic development, and subsequent health in later life, can be affected by peri-conceptional environmental conditions, is raising the possibility that cryopreservation methods themselves may have to be reviewed and revised when planning the biobanks. Here, I describe the benefits and problems associated with germplasm biobanking across various species, but also offer some realistic assessments of current progress and applications.(AU)

Mecanismos epigenéticos nos espermatozoides e o impacto sobre a fertilidade masculina / Epigenetic mechanisms on sperm cells and the impact on male fertility

Por ser uma célula altamente especializada, o espermatozoide apresenta diferentes mecanismos epigenéticos, sendo os principais as metilações do DNA, o código de histonas, os ncRNAs (RNAs não codificadores), e a alta condensação da cromatina pela presença das protaminas. Estes mecanismos interagem entre si, contribuindo para a formação do epigenoma espermático, que modela a carga molecular espermática, que, por sua vez, pode impactar sobre as características do desenvolvimento embrionário e da progênie. Dessa forma, atualmente é consenso que o papel do espermatozoide ultrapassa a entrega de DNA de qualidade para o oócito no momento da fecundação. Pesquisas recentes de diversos grupos, incluindo o nosso, mostram que além da contribuição com DNA de qualidade, o espermatozoide entrega moléculas ao oócito no momento da fecundação que influenciam o desenvolvimento do embrião. Recentemente, essas moléculas de origem espermática (Em inglês: sperm-borne) também são associadas com alterações metabólicas e cognitivas da progênie. Embora ainda pouco se entenda como esses mecanismos podem persistir mesmo com o ciclo de reprogramação celular que ocorre logo após a fecundação, é evidente que estes podem impactar as características da progênie. Nesta revisão abordaremos sobre a modulação do epigenoma espermático e seus efeitos no desenvolvimento embrionário.(AU)

Since it is a highly specialized cell, the spermatozoa display different epigenetic mechanisms; the main ones are DNA methylation, histone code, ncRNAs (non-coding RNAs), and high chromatin condensation by the presence of protamines. These mechanisms act in synergy contributing to forming the sperm epigenome, which modulates the spermatic molecular cargo, and, may impact embryo and offspring development features. Thus, it is currently a consensus that the role of spermatozoa goes beyond delivering quality DNA to the oocyte at fertilization. Relevant findings from several research groups, including ours, have shown that sperm delivers several molecules to the oocyte at fertilization, beyond the contribution to DNA, which influences the development of the embryo. Recently, these sperm-borne molecules have also been associated with metabolic and cognitive changes in the offspring. Although the mechanism by which these changes can persist even after embryo reprogramming is not completely understood, evidence shows that sperm cell molecular content impacts embryo and offspring development. This review will mainly focus on the modulation of the sperm epigenome and its effects on embryo development.(AU)

Could dysregulation of RASSF1 expression be a mechanism of tumorigenesis in CTVT? / A desregulação da expressão de RASSF1 pode ser um mecanismo da tumorigênese em TVTC?

Canine transmissible venereal tumor (CTVT) is the oldest known somatic cell lineage. It is a transmissible cancer that propagates naturally in dogs and reportedly contains gene mutations. RASSF1 participates in DNA damage repair, and its downregulation, results in tumor progression. Hence, RASSF1 is a tumor suppressor gene. Its expression was quantified in tumors from seventeen animals and three cell cultures derived from tumors. In general, RASSF1 was underexpressed in 65%, and absent in 35% of tumor samples. Cells from tumor tissue cultures showed decreased expression of RASSF1 in 67% and elevated expression in 33% of samples tested. The tumor tissues showed significantly lower levels of RASSF1 expression compared to cultured cells. Previously we reported that both the tumor microenvironment and the host immune system appear to influence the tumorigenesis and stage of CTVT. This is the first article to demonstrate the expression of RASSF1 in CTVT. Decreased RASSF1 possibly helps tumor progression.

O tumor venéreo transmissível canino (TVTC) é a linhagem de células somáticas mais antiga conhecida. É um câncer transmissível que se propaga naturalmente em cães e mutações genéticas já foram relatadas. O gene RASSF1 atua no reparo de danos ao DNA e presume-se que, quando suprimido ou com expressão gênica reduzida, o TVTC tende a progredir. A expressão do gene supressor de tumor, como RASSF1, foi quantificada em tecidos de dezessete animais e três culturas de células de tecidos tumorais. Em geral, o gene RASSF1 apresentou prevalência de subexpressão (65%) e ausência em 35% dos demais tecidos analisados. Células isoladas de culturas de tecidos tumorais também demonstraram 67% com expressão diminuída e 33% com expressão elevada, com diferença significativa entre os níveis de expressão gênica em amostras de tecido quando comparadas às culturas de células, com tecidos apresentando níveis mais baixos de expressão gênica em comparação com células. Anteriormente, relatamos que tanto o microambiente tumoral quanto o sistema imunológico do hospedeiro parecem influenciar a tumorigênese e o estágio do TVTC. Este é o primeiro artigo a demonstrar a expressão de RASSF1 no TVTC, possivelmente alterando sua tumorigênese e auxiliando no aumento da progressão tumoral.

Response and tolerance mechanism of food crops under high temperature stress: a review

Abstract High temperature stress events are critical factors inhibiting crop yield. Meanwhile, world population is growing very rapidly and will be reached up to 9 billion by 2050. To feed increasing world population, it is challenging task to increase about 70% global food productions. Food crops have significant contribution toward global food demand and food security. However, consequences from increasing heat stress events are demolishing their abilities to survive and sustain yield when subjected to extreme high temperature stress. Therefore, there is dire need to better understand response and tolerance mechanism of food crops following exposure to heat stress. Here, we aimed to provide recent update on impact of high temperature stress on crop yield of food crops, pollination, pollinators, and novel strategies for improving tolerance of food crop under high temperature stress. Importantly, development of heat-resistant transgenic food crops can grant food security through transformation of superior genes into current germplasm, which are associated with various signaling pathways as well as epigenetic regulation in response to extreme high temperature stress.

Resumo Eventos de estresse de alta temperatura são fatores críticos que inibem o rendimento das culturas. Enquanto isso, a população mundial está crescendo muito rapidamente e atingirá até 9 bilhões em 2050. Para alimentar a crescente população mundial, é uma tarefa desafiadora aumentar cerca de 70% da produção global de alimentos. As culturas alimentares têm uma contribuição significativa para a procura global de alimentos e a segurança alimentar. No entanto, as consequências do aumento de eventos de estresse por calor estão destruindo suas habilidades de sobreviver e manter a produção quando submetidos a estresse de alta temperatura. Portanto, há uma necessidade urgente de entender melhor o mecanismo de resposta e tolerância das safras de alimentos após a exposição ao estresse por calor. Aqui, nosso objetivo foi fornecer atualizações recentes sobre o impacto do estresse de alta temperatura no rendimento de culturas de alimentos, polinização, polinizadores e novas estratégias para melhorar a tolerância de culturas de alimentos sob estresse de alta temperatura. É importante ressaltar que o desenvolvimento de culturas alimentares transgênicas resistentes ao calor pode garantir segurança alimentar por meio da transformação de genes superiores em germoplasma atual, que estão associados a várias vias de sinalização, bem como à regulação epigenética em resposta ao estresse de alta temperatura extrema.

The effects of valproic acid on skin healing: experimental study in rats

Purpose: To recognize the effects of valproic acid (VPA), an epigenetic drug, on the skin healing process. Methods: Sixty male Wistar rats were divided into two groups: the experiment treated with VPA (100 mg/kg/day); and the control, with 0.9% sodium chloride by gavage. Skin healing was studied in three moments (the third, the seventh, and the 14th day), evaluating the parameters: inflammatory reaction and its intensity (anti-LCA), angiogenesis (anti-CD34), collagen I and III (anti-collagen I, anti-collagen III and Picrosirius-red F3BA) and myofibroblasts (anti-alpha-AMS). Results: The inflammatory reaction was acute or sub-acute in both groups on the third day. On the seventh and the 14th day, chronic predominated in the control (p=0.006), and sub-acute in the experiment (p=0.020). There was a greater number of leukocytes in the group treated only on the third day (p=0.036). The number of vessels was lower in the treated group at the three times (p3=0.002, p7<0.001, and p14=0.027). Myofibroblasts were rare in the third day and moderate quantity in the remaining periods. Collagen I density was higher in the control at the three times (p<0.001) and collagen III in the treated group (p<0.001). Conclusions: VPA led to a more intense inflammatory reaction, decreased angiogenesis and collagen deposition, especially type I collagen.

Response and tolerance mechanism of food crops under high temperature stress: a review / Mecanismo de resposta e tolerância de culturas alimentares sob estresse de alta temperatura: uma revisão

High temperature stress events are critical factors inhibiting crop yield. Meanwhile, world population is growing very rapidly and will be reached up to 9 billion by 2050. To feed increasing world population, it is challenging task to increase about 70% global food productions. Food crops have significant contribution toward global food demand and food security. However, consequences from increasing heat stress events are demolishing their abilities to survive and sustain yield when subjected to extreme high temperature stress. Therefore, there is dire need to better understand response and tolerance mechanism of food crops following exposure to heat stress. Here, we aimed to provide recent update on impact of high temperature stress on crop yield of food crops, pollination, pollinators, and novel strategies for improving tolerance of food crop under high temperature stress. Importantly, development of heat-resistant transgenic food crops can grant food security through transformation of superior genes into current germplasm, which are associated with various signaling pathways as well as epigenetic regulation in response to extreme high temperature stress.

Eventos de estresse de alta temperatura são fatores críticos que inibem o rendimento das culturas. Enquanto isso, a população mundial está crescendo muito rapidamente e atingirá até 9 bilhões em 2050. Para alimentar a crescente população mundial, é uma tarefa desafiadora aumentar cerca de 70% da produção global de alimentos. As culturas alimentares têm uma contribuição significativa para a procura global de alimentos e a segurança alimentar. No entanto, as consequências do aumento de eventos de estresse por calor estão destruindo suas habilidades de sobreviver e manter a produção quando submetidos a estresse de alta temperatura. Portanto, há uma necessidade urgente de entender melhor o mecanismo de resposta e tolerância das safras de alimentos após a exposição ao estresse por calor. Aqui, nosso objetivo foi fornecer atualizações recentes sobre o impacto do estresse de alta temperatura no rendimento de culturas de alimentos, polinização, polinizadores e novas estratégias para melhorar a tolerância de culturas de alimentos sob estresse de alta temperatura. É importante ressaltar que o desenvolvimento de culturas alimentares transgênicas resistentes ao calor pode garantir segurança alimentar por meio da transformação de genes superiores em germoplasma atual, que estão associados a várias vias de sinalização, bem como à regulação epigenética em resposta ao estresse de alta temperatura extrema.

DNA methylation level of gene SIRT1 in ram spermatozoa and relationship with fertilizing ability according to breed and age

Background: Effect of the epigenetic factors on the male fertility is well proofed. Sperm acts as a carrier of genetic material, and its DNA methylome can affect maternal pregnancy rate and offspring phenotype. However, the research on the DNA methylation in the spermatozoids of livestock males, in particular rams, is still limited. To best of our knowledge the data about as a global as well as gene specific DNA methylation in ram spermatozoa from different breeds and ages are missed in the scientific literature. The present study was designed to analyze the relationship between methylation levels of the important for spermatogenesis gene SIRT1 in spermatozoa and fertilizing ability of sperm in rams from different breeds and ages. Materials, Methods & Results: The ejaculates of 16 rams from Lacaune, East Friesian and Assaf breeds at age between 18 to 96 months were evaluated. The kinematic parameters of 2 semen samples from each animal were estimated by CASA. The separated spermatozoa were used for DNA extraction followed by bisulfite conversion. The DNA methylation of SIRT1 was detected through quantitative methylation-specific PCR using 2 sets of primers designed specifically for bisulfite-converted DNA sequences to attach methylated and unmethylated sites. The breed and age effect on the gene SIRT1 methylation by ANOVA was estimated. Experimental females included 393 clinically healthy milk ewes (Lacaune, n = 131; East Friesian sheep, n = 100 and Assaf, n = 162) in breeding season. Reproductive performances (conception rate at lambing, lambing percentage and fecundity) of ewes, inseminated by sperm of the investigated rams, were statistically processed. ANOVA showed that the animal breed influences significantly on the level of DNA methylation of gene SIRT1 in ram spermatozoa (P = 0.002) An average value of DNA methylation of SIRT1 in ram sperm from Lacaune breed was significantly higher than in Assaf and East Friesian (81.21 ± 15.1% vs 36.7 ± 14.2% and 38.3 ± 18.6 respectively, P < 0.01). The highest percent of SIRT1 methylation was observed in old animals compared to the young and middle-age. Moderate and strong correlations (r from 0.44 to 0.71, P < 0.05) between the methylation level of the SIRT1 gene in rams' sperm and reproductive parameters of inseminated ewes in all breeds were established. Discussion: Our data are the first message about the effect of breed on the specificity of DNA methylation of gene SIRT1 in ram spermatozoa. These results demonstrated an existence of the sheep breeds with high and low level of DNA methylation of gene SIRT1 in ram sperm. Although the effect of age on the methylation level in sperm is still discussable, our results showed a moderate correlation between age and methylation level of SIRT1 in spermatozoa of rams. Taking into account that DNA methylation in sperm is stabilized with puberty onset and is a heritable epigenetic modification, it can be a promising marker of sperm quality in animal breeding. In all investigated breeds the rams with relatively high level of DNA methylation of gene SIRT1 in spermatozoa (50-68%) demonstrated a high conception rate at lambing (> 70%). In conclusion, the DNA methylation level of the SIRT1 gene in ram spermatozoa is determined by both the breed and the age of the animals and correlates with fertilizing ability of sperm.

Maternal obesity and ovarian failure: is leptin the culprit?

At the time of its discovery and characterization in 1994, leptin was mostly considered a metabolic hormone able to regulate body weight and energy homeostasis. However, in recent years, a great deal of literature has revealed leptin's pleiotropic nature, through its involvement in numerous physiological contexts including the regulation of the female reproductive tract and ovarian function. Obesity has been largely associated with infertility, and leptin signalling is known to be dysregulated in the ovaries of obese females. Hence, the disruption of ovarian leptin signalling was shown to contribute to the pathophysiology of ovarian failure in obese females, affecting transcriptional programmes in the gamete and somatic cells. This review attempts to uncover the underlying mechanisms contributing to female infertility associated with obesity, as well as to shed light on the role of leptin in the metabolic dysregulation within the follicle, the effects on the oocyte epigenome, and the potential long-term consequence to embryo programming.(AU)

Prenatal origins of productivity and quality of beef

The productive traits of beef cattle are orchestrated by their genetics, postnatal environmental conditions, and also by the intrauterine background. Both under- or overnutrition, as specific dietary components, are able to promote persistent effects on the offspring. This occurs because dietary factors act not only affecting the availability of substrates for fetal anabolism and oxidative metabolism, but also as signals that regulate several events toward fetal development. Therefore, this study aimed to summarize the gestational nutrition effects on the offspring performance and meat quality in a long term. Overall, studies have shown that many of these alterations are under the control of epigenetic mechanisms, as DNA methylation, histones modification, and non-coding RNA. The current knowledge has indicated that the fetal programming responses are dependent on the window of fetal development in which the dietary treatment is applied, the intensity of maternal nutritional stimuli, and the treatment application length. Collectively, studies demonstrated that muscle cell hyperplasia is impaired when maternal requirements were not achieved in the second third of gestation, which limits the formation of a greater number of muscle fibers and the offspring growth potential in a long term. Changes in muscle fibers metabolism and in collagen content were also reported as consequence of a dietary perturbation during pregnancy. In contrast, a maternal overnutrition during the late pregnancy has been associated with beneficial responses on meat quality. In summary, ensuring an adequate maternal environment during the fetal development is crucial to enhance the productive responses in beef cattle operations.(AU)

Effect of In Ovo Ascorbic Acid Injection and Thermal Manipulation During Incubation on Intestine Morphology of Broilers Reared under Cold and Heat Stress

It was investigated if pre-incubation ascorbic acid (AA) injection in fertile eggs incubated at high temperature impacts the performance, the yield of carcass and parts, and the intestine morphology of broilers reared under heat stress. Three thousand Cobb® fertile broiler eggs were randomly distributed according to weight into three incubations treatments (eggs not injected with AA and incubated at 37.5°C; eggs not injected with AA and incubated at 39°C; and eggs injected with 6 µg AA/100 µL water prior to incubation and incubated at 39ºC). The hatched birds were reared at thermoneutral, cold, and hot house temperatures. Broilers reared under hot temperature presented lower feed intake and weight gain than the broilers of the different rearing temperatures. Egg incubation at 39.0 ºC and 39.0 ºC + AA reduced broiler viability. Carcass and cut yields were not influenced by incubation and rearing procedures. Duodenal goblet cell count was lower in broilers from eggs of the treatment 39ºC + AA than in broilers from the other incubation treatments and in broiler rearing in hot temperature. In the jejunum, the goblet cell counts were higher in broilers that were reared under hot than thermoneutral temperatures. The incubation treatment of 39 ºC+AA increased the goblet cell counts in the ileum of broilers reared under cold temperatures. Rearing temperature influenced the duodenal villi counts, which were lower under cold rearing conditions than in the two other rearing temperatures. The results showed that egg incubation at 39°C, independently of ascorbic acid injection, did not produce an effective epigenetic heat adaptation in broilers.(AU)

The relationship between IL-4 polymorphisms and asthma: a systematic review / A relação entre polimorfismos de IL-4 e asma: uma revisão sistemática

Asthma is a chronic and heterogeneous disease of the airways that begins in childhood and persists, in many cases, into adulthood. The disease is the result of environmental, epigenetic and genetic interactions. This work aims to review the polymorphisms described in the literature in the IL-4 gene associated with susceptibility or protection to the development of asthma. This is a systematic literature review, carried out in PubMed, MEDLINE and Science Direct databases in the time frame from 2000 to July 2021, revealing the following key points: IL-4, Polymorphisms and Asthma. The search resulted in 29 articles, all in English. Despite some divergent studies, the SNP rs2243250, which was the most studied in populations from different countries, was also the one that found the most correlations of susceptibility with the disease. It is concluded that although there is controversial data on IL-4 SNPs related to the disease, the association of pangenomic studies has brought a list of genes and their variations associated with the risk of developing asthma, such as the rs2243250 SNP that was well related in populations of several countries analyzed. (AU)

A asma é uma doença crônica e heterogênea das vias aéreas que tem início na infância e persiste em muitos casos até a vida adulta. A doença é resultado de interações ambientais, epigenéticas e genéticas. Este trabalho tem como objetivo revisar sobre os polimorfismos descritos na literatura no gene IL-4 associados à susceptibilidade ou proteção ao desenvolvimento da asma. Trata-se de uma revisão sistemática da literatura, feita nos bancos de dados PubMed, MEDLINE e Science Direct no corte temporal de 2000 a julho de 2021, ressaltando os seguintes pontos-chave: IL-4, Polimorfismos e Asma. A pesquisa resultou em 29 artigos, sendo em sua totalidade em língua inglesa. Apesar de alguns estudos divergentes, o SNP rs2243250, que foi o mais estudado em populações de diversos países, também foi o que mais encontrou correlações de susceptibilidade com a doença. Conclui-se que, apesar de haver dados controversos sobre os SNPs de IL-4 relacionados à doença, a associação dos estudos pangenômicos tem trazido uma lista de genes e variações deles associados com o risco de desenvolver a asma, como o SNP rs2243250 que foi bem relacionado em populações de vários países analisados (AU).

Frontiers in sheep reproduction - making use of natural responses to environmental challenges to manage productivity

This review addresses advances, directions and opportunities for research on sheep reproduction in the context of the global challenges of food security and climate change, and demand for 'clean, green and ethical' (CGE) animal management. The foundation of CGE management is an understanding of the physiological processes through which the reproductive system responds to changes in the animal's environment. These days, to the main environmental factors (photoperiod, nutrition, pheromones), we need to add stress from extreme weather events. With respect to nutrition in rams, we now have a deeper understanding of the responses of the brain centres that control gonadotrophin secretion (the kisspeptin system). At testis level, we have found that nutrition affects non-coding RNAs in Sertoli cells and germ cells, thus affecting the balance between cell proliferation and apoptosis. This proliferation-apoptosis balance is also affected during prenatal development, when undernutrition or stress in pregnant ewes seems to elicit epigenetic changes in developing gonads that could affect offspring fertility in adult life. With respect to nutrition in ewes, metabolic signals act directly on ovarian follicles, and thus change ovulation rate, but the variety of signals now includes the adipokines. An early concern was that nutritional supplements that increase ovulation rate would also increase embryo mortality but we now know that embryo survival is improved under field conditions. Finally, we had always thought that the efficiency gains from early puberty in lambs could only be achieved by accelerating fat accumulation, but we now know that faster muscle growth will achieve the same goal, offering two advantages in meat production systems. With respect to pheromones ('ram effect'), we have a deeper understanding of the brain responses (kisspeptin system) but, most importantly, a realization that the response of ewes to the ram signal involves cell division in memory centres. Many opportunities remain.(AU)

The embryo culture media in the era of epigenetics: is it time to go back to nature?

This review is intended to draw attention to the importance of the culture media composition on the health of the embryos, fetuses, newborns, and adults derived from assisted reproductive technologies (ART). Although current research and industry trends are to use chemically defined media because of their suitability for manufacturing, commercialization, and regulatory purposes, compelling evidence indicates that those media fail to adequately account for the biological demands of early embryogenesis. Here, we list the main undesirable consequences of the ART described in the literature and results we and others have obtained over the past decade exploring an alternative and more natural way to support embryo growth in vitro: inclusion of endogenous reproductive fluids as additives in the ART culture media for pigs, cows, and humans. This review systematically assesses the pros and cons of using reproductive fluid additives, as well as the requirements to implement this approach in the future.(AU)

Erasing gametes to write blastocysts: metabolism as the new player in epigenetic reprogramming

Understanding preimplantation embryonic development is crucial for the improvement of assisted reproductive technologies and animal production. To achieve this goal, it is important to consider that gametes and embryos are highly susceptible to environmental changes. Beyond the metabolic adaptation, the dynamic status imposed during follicular growth and early embryogenesis may create marks that will guide the molecular regulation during prenatal development, and consequently impact the offspring phenotype. In this context, metaboloepigenetics has gained attention, as it investigates the crosstalk between metabolism and molecular control, i.e., how substrates generated by metabolic pathways may also act as players of epigenetic modifications. In this review, we present the main metabolic and epigenetic events of pre-implantation development, and how these systems connect to open possibilities for targeted manipulation of reproductive technologies and animal production systems.

Erasing gametes to write blastocysts: metabolism as the new player in epigenetic reprogramming

Understanding preimplantation embryonic development is crucial for the improvement of assisted reproductive technologies and animal production. To achieve this goal, it is important to consider that gametes and embryos are highly susceptible to environmental changes. Beyond the metabolic adaptation, the dynamic status imposed during follicular growth and early embryogenesis may create marks that will guide the molecular regulation during prenatal development, and consequently impact the offspring phenotype. In this context, metaboloepigenetics has gained attention, as it investigates the crosstalk between metabolism and molecular control, i.e., how substrates generated by metabolic pathways may also act as players of epigenetic modifications. In this review, we present the main metabolic and epigenetic events of pre-implantation development, and how these systems connect to open possibilities for targeted manipulation of reproductive technologies and animal production systems.(AU)

Epigenetic characterization of the H19/IGF2 locus in calf clones placenta / Caracterização epigenética do locus H19/IGF2 na placenta de bezerros clones

Somatic Cell Nuclear Transfer (SCNT-Cloning) is a promising technique in many areas and is based on genetically identical individuals. However, its efficiency is low. Studies suggest that the leading cause is inadequate epigenetic reprogramming. This study aimed to characterize the methylation pattern of the exon 10 regions of the IGF2 gene and the Imprinting Control Region (ICR) of the H19 gene in the placenta of cloned calves. For this study, female and male cloned calves presenting different phenotypes were used. Genomic DNA from these animals' placenta was isolated, then treated with sodium bisulfite and amplified to the ICR/H19 and IGF2 loci. PCR products were cloned into competent bacteria and finally sequenced. A significant difference was found between controls and clones with healthy phenotypes for the ICR/H19 region. In this region, controls showed a hemimethylated pattern, as predicted in the literature due to this region has an imprinted control, while clones were showed less methylated. For the IGF2, no significant differences were found between controls and clones. These results suggest that different genomic regions in the genome may be independently reprogrammed and that failures in reprogramming the DNA methylation patterns of imprinted genes may be one of the causes of the low efficiency of SCNT.(AU)

A Transferência Nuclear de Células Somáticas (TNCS-Clonagem) é uma técnica promissora em várias áreas, e se baseia na produção de indivíduos geneticamente idênticos. No entanto, sua eficiência é baixa. Estudos sugerem que a principal causa seja uma reprogramação epigenética inadequada. O objetivo desse trabalho é caracterizar o padrão de metilação da região éxon 10 do gene IGF2 e da Região Controladora de Imprinting (ICR) do gene H19 na placenta de bezerros clonados. Para a execução do trabalho foram selecionados clones bovinos fêmeas e machos, apresentando diferentes fenótipos. O DNA da placenta desses animais foi extraído, e em seguida foi tratado com bissulfito de sódio e amplificado para os loci ICR/H19 e IGF2. Os produtos da PCR foram clonados em bactérias competentes e, por fim, sequenciados. Foi encontrada uma diferença significativa entre os controles e os clones com fenótipos saudáveis para a região da ICR/H19. Nesta região, os controles tiveram um padrão hemimetilado, como previsto pela literatura, devido essa região ser imprinted. Enquanto os clones encontravam-se menos metilados. Para a região do éxon 10 do IGF2, não foi encontrada diferença significativa entre controles e clones. Estes resultados sugerem que as diferentes regiões do genoma podem se reprogramar independente umas das outras e que falhas na reprogramação do padrão de metilação do DNA de genes imprinted podem ser uma das causas da baixa eficiência da TNCS.(AU)

Bothrops moojeni L-amino acid oxidase induces apoptosis and epigenetic modulation on Bcr-Abl+ cells

Resistance to apoptosis in chronic myeloid leukemia (CML) is associated with constitutive tyrosine kinase activity of the Bcr-Abl oncoprotein. The deregulated expression of apoptosis-related genes and alteration in epigenetic machinery may also contribute to apoptosis resistance in CML. Tyrosine kinase inhibitors target the Bcr-Abl oncoprotein and are used in CML treatment. The resistance of CML patients to tyrosine kinase inhibitors has guided the search for new compounds that may induce apoptosis in Bcr-Abl+ leukemic cells and improve the disease treatment. Methods: In the present study, we investigated whether the L-amino acid oxidase isolated from Bothrops moojeni snake venom (BmooLAAO-I) (i) was cytotoxic to Bcr-Abl+ cell lines (HL-60.Bcr-Abl, K562-S, and K562-R), HL-60 (acute promyelocytic leukemia) cells, the non-tumor cell line HEK-293, and peripheral blood mononuclear cells (PBMC); and (ii) affected epigenetic mechanisms, including DNA methylation and microRNAs expression in vitro. Results: BmooLAAO-I induced ROS production, apoptosis, and differential DNA methylation pattern of regulatory apoptosis genes. The toxin upregulated expression of the pro-apoptotic genes BID and FADD and downregulated DFFA expression in leukemic cell lines, as well as increased miR-16 expression - whose major predicted target is the anti-apoptotic gene BCL2 - in Bcr-Abl+ cells. Conclusion: BmooLAAO-I exerts selective antitumor action mediated by H2O2 release and induces apoptosis, and alterations in epigenetic mechanisms. These results support future investigations on the effect of BmooLAAO-I on in vivo models to determine its potential in CML therapy.(AU)