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1.
Genet Mol Res ; 16(1)2017 Mar 22.
Artículo en Inglés | MEDLINE | ID: mdl-28340272

RESUMEN

Methodologies using restricted maximum likelihood/best linear unbiased prediction (REML/BLUP) in combination with sequential path analysis in maize are still limited in the literature. Therefore, the aims of this study were: i) to use REML/BLUP-based procedures in order to estimate variance components, genetic parameters, and genotypic values of simple maize hybrids, and ii) to fit stepwise regressions considering genotypic values to form a path diagram with multi-order predictors and minimum multicollinearity that explains the relationships of cause and effect among grain yield-related traits. Fifteen commercial simple maize hybrids were evaluated in multi-environment trials in a randomized complete block design with four replications. The environmental variance (78.80%) and genotype-vs-environment variance (20.83%) accounted for more than 99% of the phenotypic variance of grain yield, which difficult the direct selection of breeders for this trait. The sequential path analysis model allowed the selection of traits with high explanatory power and minimum multicollinearity, resulting in models with elevated fit (R2 > 0.9 and ε < 0.3). The number of kernels per ear (NKE) and thousand-kernel weight (TKW) are the traits with the largest direct effects on grain yield (r = 0.66 and 0.73, respectively). The high accuracy of selection (0.86 and 0.89) associated with the high heritability of the average (0.732 and 0.794) for NKE and TKW, respectively, indicated good reliability and prospects of success in the indirect selection of hybrids with high-yield potential through these traits. The negative direct effect of NKE on TKW (r = -0.856), however, must be considered. The joint use of mixed models and sequential path analysis is effective in the evaluation of maize-breeding trials.


Asunto(s)
Modelos Genéticos , Zea mays/genética , Cruzamientos Genéticos , Grano Comestible/genética , Técnicas de Genotipaje/métodos , Funciones de Verosimilitud , Fitomejoramiento/métodos , Probabilidad , Sitios de Carácter Cuantitativo , Análisis de Regresión , Reproducibilidad de los Resultados , Selección Genética
2.
Genet Mol Res ; 16(2)2017 Jun 20.
Artículo en Inglés | MEDLINE | ID: mdl-28653744

RESUMEN

The REML/BLUP statistics are analyses that can be used as selective criteria in the routine of maize breeding programs. The present study aims to determine the genetic potential in crosses of landrace populations applying the REML/BLUP methodology, and to identify populations for the synthesis of new populations and intrapopulation selection for family farming systems, as well as genetic constitutions for use in maize breeding programs. Nine top cross hybrids obtained in the 2012/2013 harvest were evaluated along with their testator, the landraces used as parents, and four commercial hybrids, in a randomized block design, with information taken from the average of each plot. The evaluated traits were: leaf angle, number of ramifications of the tassel, spike insertion height, plant height, spike diameter, number of grains per spike, mass of grains per spike, spike mass, spike length, prolificity, mass of one hundred grains, and grain yield per plot. The data were analyzed using the Selegen-REML/BLUP software. The top cross hybrids Cateto Branco x Planalto, Amarelão x Planalto and the population Cateto Branco are ranked among the ten best crosses, simultaneously, for the traits: leaf angle, number of ramifications of the tassel, spike insertion height, and plant height (Cateto Branco x Planalto), and leaf angle, spike insertion height, and plant height (Amarelão x Planalto and Cateto Branco). The top cross hybrids Criolão x Planalto, Branco 8 Carreiras x Planalto, Caiano Rajado x Planalto, Amarelão x Planalto, Branco Roxo Índio x Planalto stand out for their high genotypic value of the individual BLUP mean components among the ten best genotypes for grain yield, and by combining three or more traits of interest together, being, for effects of selection, the most indicated.


Asunto(s)
Cruzamiento/métodos , Cruzamientos Genéticos , Zea mays/genética , Carácter Cuantitativo Heredable
3.
Genet Mol Res ; 16(3)2017 Aug 31.
Artículo en Inglés | MEDLINE | ID: mdl-28873210

RESUMEN

Genetic improvement is essential to achieve increments in maize (Zea mays L.) grain yield components. It may be obtained through crosses, which enable to exploit the effects of intervarietal heterosis, allelic complementarity, as well as gene actions and effects. This study estimated the components of variance and genetic parameters (REML/BLUP) of an intervarietal diallel to select and predict the best genotypes for maize yield components. The experimental design was randomized blocks containing 60 intervarietal maize hybrids arranged in three repetitions. They were obtained through intervarietal crosses and evaluated in a diallel scheme, where 14 open-pollinated varieties were designated as parentals. Thus, 10 crosses were performed for each hybrid combination to obtain the number of seeds necessary for the competition test. The measured traits were: grain volume relative index, the mass of one hundred grains, and grain yield. The male parents and the additive genetic fraction were determinants for grain volume relative index. Mass of one hundred grains and grain yield were defined by the specific combining ability, and female parents revealed low narrow sense heritability. The female parent Taquarão and male parent Argentino Amarelo presented the best general combining abilities for the measured traits. The specific combining abilities were expressed for crosses AL 25 x Dente de Ouro Roxo, AL 25 x BRS Pampeano, and Taquarão x Argentino Branco. Genetic estimates and predictions were consistent and applicable to breeding programs and could be applied in future quantitative genetic studies of maize.


Asunto(s)
Hibridación Genética , Modelos Genéticos , Fitomejoramiento/métodos , Polimorfismo Genético , Zea mays/genética , Alelos , Genotipo , Carácter Cuantitativo Heredable , Semillas/genética , Semillas/crecimiento & desarrollo , Zea mays/crecimiento & desarrollo
4.
Reprod Domest Anim ; 47 Suppl 6: 356-8, 2012 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-23279537

RESUMEN

This report addresses an atypical transmissible venereal tumour in an 8-year-old bitch that was pluriparous and seropositive for leishmaniasis. There were ascites and a serosanguineous discharge from the vulva, but no lesions on the external genital mucosa. An aspirate of the peritoneal fluid showed mononuclear round cells characteristic of transmissible venereal tumour (TVT). Exploratory laparotomy revealed light red, granulomatous structures in the peritoneum, omentum, spleen, liver and uterine horns. Cytological and histopathological tests confirmed the diagnosis of intra-abdominal TVT. Dissemination of the TVT to several organs inside the abdominal cavity probably resulted from immunosuppression caused by leishmaniasis, which favoured the presence and aggressiveness of TVT.


Asunto(s)
Enfermedades de los Perros/patología , Leishmaniasis/veterinaria , Tumores Venéreos Veterinarios/patología , Animales , Enfermedades de los Perros/etiología , Perros , Resultado Fatal , Femenino , Leishmaniasis/complicaciones , Tumores Venéreos Veterinarios/complicaciones
5.
Braz J Biol ; 84: e256933, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35293546

RESUMEN

Anticarsia gemmatalis Hünber, 1818 is one of the main defoliating species in the soybean crop. Bacillus thuringiensis Berliner, 1915, is a bacterium used in the biological control of this pest species. Resistant populations and their sublethal effects caused by the use of the bacteria have already been reported; however, there are no studies on phenotypic plasticity in adulthood exposed to Bt-based bioinsecticide sub-doses. This study aimed to evaluate the morphometry of A. gemmatalis adults under laboratory conditions submitted to the Bt-based bioinsecticide Dipel® over the three generations. The body segments mensuread were width, length, and area of the anterior and posterior wings, the weight of the integument, chest, abdomen, wings, and the whole adult of males and females. Among the treatments, LC5 in the first generation and LC10 in the second generation were those with lower thresholds in relation to the weight of the chest and abdomen, considering the proportions of the body smaller than the females. The female's weight adulthood was reduced by 10% about males, and, only in the first generation. Males have larger body size and more pronounced phenotypic plasticity than females. Here, we demonstrate the first study assessing the phenotypic plasticity of A. gemmatalis adults.


Asunto(s)
Bacillus thuringiensis , Mariposas Nocturnas , Adaptación Fisiológica , Animales , Femenino , Proteínas Hemolisinas/farmacología , Masculino , Glycine max
6.
Braz. j. biol ; 842024.
Artículo en Inglés | LILACS-Express | LILACS, VETINDEX | ID: biblio-1469404

RESUMEN

Abstract Anticarsia gemmatalis Hünber, 1818 is one of the main defoliating species in the soybean crop. Bacillus thuringiensis Berliner, 1915, is a bacterium used in the biological control of this pest species. Resistant populations and their sublethal effects caused by the use of the bacteria have already been reported; however, there are no studies on phenotypic plasticity in adulthood exposed to Bt-based bioinsecticide sub-doses. This study aimed to evaluate the morphometry of A. gemmatalis adults under laboratory conditions submitted to the Bt-based bioinsecticide Dipel® over the three generations. The body segments mensuread were width, length, and area of the anterior and posterior wings, the weight of the integument, chest, abdomen, wings, and the whole adult of males and females. Among the treatments, LC5 in the first generation and LC10 in the second generation were those with lower thresholds in relation to the weight of the chest and abdomen, considering the proportions of the body smaller than the females. The females weight adulthood was reduced by 10% about males, and, only in the first generation. Males have larger body size and more pronounced phenotypic plasticity than females. Here, we demonstrate the first study assessing the phenotypic plasticity of A. gemmatalis adults.


Resumo Anticarsia gemmatalis Hünber, 1818 é uma das principais espécies desfolhadoras da cultura da soja. Bacillus thuringiensis Berliner, 1915, é uma bactéria utilizada no controle biológico dessa espécie de praga. Populações resistentes e seus efeitos subletais causados pelo uso da bactéria já foram relatados, no entanto, não há estudos sobre a plasticidade fenotípica na idade adulta exposta a subdoses de bioinseticida à base de Bt. Este trabalho teve como objetivo avaliar a morfometria de adultos de A. gemmatalis em condições de laboratório submetidos ao bioinseticida Dipel® ao longo de três gerações. Os segmentos corporais mensuráveis eram largura, comprimento e área das asas anterior e posterior, o peso do tegumento, tórax, abdômen, asas e todo o adulto de machos e fêmeas. Dentre os tratamentos, CL5 na primeira geração e CL10 na segunda geração foram aqueles com limiares mais baixos em relação ao peso do tórax e abdômen, considerando as proporções do corpo menores que as do sexo feminino. O peso da fêmea na idade adulta foi reduzido em 10% em relação aos machos e, apenas na primeira geração. Os machos têm tamanho corporal maior e plasticidade fenotípica mais pronunciada do que as fêmeas. Este estudo demonstra o primeiro estudo avaliando a plasticidade fenotípica de adultos de A. gemmatalis.

7.
Braz. j. biol ; 84: e256933, 2024. tab, ilus
Artículo en Inglés | LILACS, VETINDEX | ID: biblio-1364505

RESUMEN

Anticarsia gemmatalis Hünber, 1818 is one of the main defoliating species in the soybean crop. Bacillus thuringiensis Berliner, 1915, is a bacterium used in the biological control of this pest species. Resistant populations and their sublethal effects caused by the use of the bacteria have already been reported; however, there are no studies on phenotypic plasticity in adulthood exposed to Bt-based bioinsecticide sub-doses. This study aimed to evaluate the morphometry of A. gemmatalis adults under laboratory conditions submitted to the Bt-based bioinsecticide Dipel® over the three generations. The body segments mensuread were width, length, and area of the anterior and posterior wings, the weight of the integument, chest, abdomen, wings, and the whole adult of males and females. Among the treatments, LC5 in the first generation and LC10 in the second generation were those with lower thresholds in relation to the weight of the chest and abdomen, considering the proportions of the body smaller than the females. The female's weight adulthood was reduced by 10% about males, and, only in the first generation. Males have larger body size and more pronounced phenotypic plasticity than females. Here, we demonstrate the first study assessing the phenotypic plasticity of A. gemmatalis adults.


Anticarsia gemmatalis Hünber, 1818 é uma das principais espécies desfolhadoras da cultura da soja. Bacillus thuringiensis Berliner, 1915, é uma bactéria utilizada no controle biológico dessa espécie de praga. Populações resistentes e seus efeitos subletais causados pelo uso da bactéria já foram relatados, no entanto, não há estudos sobre a plasticidade fenotípica na idade adulta exposta a subdoses de bioinseticida à base de Bt. Este trabalho teve como objetivo avaliar a morfometria de adultos de A. gemmatalis em condições de laboratório submetidos ao bioinseticida Dipel® ao longo de três gerações. Os segmentos corporais mensuráveis eram largura, comprimento e área das asas anterior e posterior, o peso do tegumento, tórax, abdômen, asas e todo o adulto de machos e fêmeas. Dentre os tratamentos, CL5 na primeira geração e CL10 na segunda geração foram aqueles com limiares mais baixos em relação ao peso do tórax e abdômen, considerando as proporções do corpo menores que as do sexo feminino. O peso da fêmea na idade adulta foi reduzido em 10% em relação aos machos e, apenas na primeira geração. Os machos têm tamanho corporal maior e plasticidade fenotípica mais pronunciada do que as fêmeas. Este estudo demonstra o primeiro estudo avaliando a plasticidade fenotípica de adultos de A. gemmatalis.


Asunto(s)
Animales , Fenotipo , Glycine max , Bacillus thuringiensis , Control Biológico de Vectores
8.
Basic Clin Androl ; 27: 12, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-28649382

RESUMEN

BACKGROUND: In humans, it is now well documented that rising paternal age is correlated with decreased sperm DNA integrity and embryonic developmental failures. On the other side of the coin, it is also reported that very young fathers such as teenagers carry an increased risk of adverse birth outcomes. These observations suggest that, at least in humans, there is an age window for optimal sperm DNA integrity. In bovine, little is known about sperm DNA quality in young bulls and how it evolves with age. This study aimed to fill in this gap as it may be of importance for the bovine industry to know when exactly a bull is an optimal performer for reproductive programs. METHODS: Forty Nellore bulls were divided into three age groups: 1.8 to 2 years - young bulls; 3.5 to 7 years - adult bulls; and 8 to 14.3 years - aged bulls. Three ejaculates were collected from each bull, cryopreserved and evaluated for various parameters including: computer-assisted sperm analysis (CASA), plasma membrane and acrosome integrity, mitochondrial potential, sperm nuclear protamination, DNA oxidative damage, and Sperm Chromatin Structure Assay (SCSA). RESULTS: We report here that young bulls presented superior values for motility, plasma and acrosomal membrane integrity, and high mitochondrial potential. However, they also presented higher values for sperm morphological abnormalities compared to adult and aged animal groups (p < 0.05). In addition, young bulls exhibited more defective protamination than older animals did. The oldest bulls showed more nuclear oxidative damage than the younger groups of bulls while both the young and aged groups were found more susceptible to DNA denaturation as revealed with the SCSA test (p < 0.05). CONCLUSION: These results indicate that young bulls spermatozoa best survived the freezing procedure, followed by adult and aged bulls. However, young and aged bulls were found to be more susceptible to DNA damage, respectively caused by protamine deficiency and oxidation. Therefore, although young bulls have correct semen parameters according to classical evaluation, our results indicate that they may show some structural nuclear immaturity.


CONTEXTE: Chez l'homme, de nombreuses données indiquent maintenant que l'avancée de l'âge du père est associée à une réduction de l'intégrité de l'ADN des spermatozoïdes et aux échecs de développement embryonnaire. D'un autre côté, il est aussi rapporté que les jeunes pères, tels les adolescents, sont porteurs d'un risque accru d'issue défavorable de la grossesse. Ces observations suggèrent que, au moins chez l'humain, il existe une tranche d'âge dans laquelle l'intégrité de l'ADN des spermatozoïdes est optimale. Chez les bovins, on dispose de peu de connaissances sur la qualité de l'ADN des spermatozoïdes des jeunes taureaux et sur son mode d'évolution avec l'âge. La présente étude a pour but de combler ce manque car il peut être important, pour l'industrie bovine, de savoir à quelle période précise un taureau est un reproducteur optimal pour les programmes de reproduction. MATÉRIEL ET MÉTHODES: Quarante taureaux Nellore ont été répartis en trois groupes d'âge: 1, 8 à 2 ans ­ jeunes taureaux; 3,5 à 7 ans ­ taureaux adultes; et 8 à 14,3 ans ­ taureaux âgés. Trois éjaculats ont été collectés par taureau, cryopréservés et évalués pour différents paramètres incluant l'analyse assistée du sperme par ordinateur (CASA), l'intégrité des membranes plasmique et acrosomique, le potentiel mitochondrial, la protamination du noyau, l'altération oxydative de l'ADN et l'évaluation de la structure de la chromatine du noyau du spermatozoïde (SCSA). RÉSULTATS: Nous rapportons ici que les jeunes taureaux présentent des valeurs supérieures de la mobilité des spermatozoïdes et de l'intégrité des membranes plasmique et acrosomique, ainsi qu'un potentiel mitochondrial élevé. Cependant, les jeunes taureaux présentent aussi des valeurs plus élevées d'anomalies morphologiques des spermatozoïdes que celles des groupes adulte et âgé (p < 0.05). De plus, les jeunes taureaux ont une protamination plus défectueuse que celle des taureaux plus âgés. Les taureaux les plus âgés présentent plus d'altérations oxydatives du noyau que les jeunes taureaux alors que les deux groupes -jeunes et âgés- sont plus susceptibles d'avoir une dénaturation de l'ADN nucléaire comme indiqué par le SCSA (p < 0.05). CONCLUSIONS: Ces résultats indiquent que les spermatozoïdes des jeunes taureaux survivent le mieux au processus de congélation, suivis par les adultes puis les âgés. Toutefois, les jeunes taureaux et les âgés sont plus susceptibles d'avoir une altération de l'ADN, causée respectivement par une protamination déficiente et une oxydation. Par conséquent, bien que les jeunes taureaux aient des paramètres spermatiques corrects à l'évaluation classique, nos résultats indiquent que leurs spermatozoïdes peuvent présenter un certain degré d'immaturité structurale nucléaire.

9.
Theriogenology ; 87: 154-160, 2017 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-27712828

RESUMEN

The aim of this study was to evaluate the chromatin packing and sperm head morphometry of cryopreserved semen of Nelore bulls (Bos taurus indicus) of different ages. Furthermore, the influence of the degree of chromatin compaction on in vitro embryo production (IVP) was investigated. Forty bulls were divided into three groups: young (1.8-2 years), adult (3.5-7 years), and senile (8-14.3 years). The ejaculates were frozen according to standards established by the Artificial Insemination Center located in the Southeast of Brazil. Toluidine blue staining was used for simultaneous evaluation of the sperm chromatin and sperm head morphometry. Chromomycin A3 (CMA3) was applied to analyze sperm protamination and IVP for embryonic development. Spermatozoa of young bulls presented higher values for area (A, pixels), perimeter (P, pixels), and width (W, pixels) compared to adults and senile (young: A = 1848.5 ± 119.79, P = 10.23 ± 0.29, and W = 1.95 ± 0.1; adults: A = 1672.9 ± 104.46, P = 9.86 ± 0.33, and W = 1.81 ± 0.06; senile: A = 1723.1 ± 124.41, P = 9.97 ± 0.33, and W = 1.83 ± 0.09; P < 0.0001) and showed higher protamination deficiency when analyzed by CMA3 (young: 1.57 ± 0.76; adults: 1.09 ± 0.63, and senile: 0.90 ± 0.59; P < 0.05). Likewise, variables of sperm head size (A, P, and W) and protamination assessed by CMA3 showed negative correlation with age and positive correlation with ellipticity, evaluated by toluidine blue method (P < 0.05). Sperm head area was larger in spermatozoa presenting chromatin instabilities than spermatozoa without chromatin alteration (P < 0.0001). There was no difference in IVP when using semen with larger or smaller portions of spermatozoa with chromatin instabilities, indicating that the proportion of sperm with abnormal chromatin compaction (4%-16.15%) did not interfere with early embryonic development. From our results, it can be concluded that sperm of young Nelore bulls have larger heads compared to adults and senile due to reduced protamine content when evaluated by CMA3 and higher proportion of major sperm defects assessed by differential interference contrast microscopy.


Asunto(s)
Envejecimiento/fisiología , Bovinos/fisiología , Cromatina/fisiología , Fertilización In Vitro/veterinaria , Espermatozoides/citología , Animales , Masculino , Espermatozoides/fisiología
10.
J Clin Pathol ; 46(7): 672-3, 1993 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-8157759

RESUMEN

Prolonged eosinophilia of unknown cause has generally been described as the hypereosinophilic syndrome, and is characterised by peripheral blood and bone marrow infiltration and frequent multisystem disease. The nature of this disorder has been questioned, and the clinical features are quite variable, suggesting its heterogeneity and probable neoplastic aetiology. A patient with severe eosinophilia, karyotype abnormalities, serum gammopathy and massive organ disease is reported. The clinical course was aggressive despite cytoreduction of eosinophils and terminated in multisystem failure. These findings are consistent with a diagnosis of eosinophilic leukaemia, and it is suggested that chromosome and cell culture studies might be useful in the early diagnosis of this controversial entity.


Asunto(s)
Cromosomas Humanos Par 8 , Inmunoglobulina G/metabolismo , Cadenas kappa de Inmunoglobulina/metabolismo , Cadenas lambda de Inmunoglobulina/metabolismo , Leucemia Eosinofílica Aguda/genética , Paraproteinemias/complicaciones , Trisomía , Anciano , Humanos , Leucemia Eosinofílica Aguda/complicaciones , Masculino , Paraproteinemias/inmunología
11.
Acta Med Port ; 8(9): 505-9, 1995 Sep.
Artículo en Portugués | MEDLINE | ID: mdl-7484270

RESUMEN

A case of oesophageal basaloid carcinoma is reported. The disease was revealed as a brain metastasis and was found ad initium to be in an advanced stage, with evidence of brain, lung and liver metastasis. The treatment performed was palliative subtotal oesophagectomy followed by roentgen therapy. A year and a half later, the patient is still alive and in home care follow up. The authors end stressing this uncommon presentation for an oesophageal neoplasm and the rarity of its histologic type. They also stress the role of surgery, although palliative, in long survival, very unlike the rapid evolution of the few published cases.


Asunto(s)
Neoplasias Encefálicas/diagnóstico , Neoplasias Encefálicas/secundario , Carcinoma de Células Transicionales/diagnóstico , Carcinoma de Células Transicionales/secundario , Neoplasias Esofágicas/diagnóstico , Neoplasias Encefálicas/patología , Neoplasias Encefálicas/terapia , Carcinoma de Células Transicionales/patología , Carcinoma de Células Transicionales/terapia , Terapia Combinada , Neoplasias Esofágicas/patología , Neoplasias Esofágicas/terapia , Humanos , Neoplasias Hepáticas/secundario , Neoplasias Pulmonares/secundario , Masculino , Persona de Mediana Edad , Cuidados Paliativos
12.
Arq. bras. med. vet. zootec ; Arq. bras. med. vet. zootec. (Online);67(2): 417-423, Mar-Apr/2015. tab, ilus
Artículo en Inglés | LILACS, VETINDEX | ID: lil-747038

RESUMEN

The routine semen evaluation assessing sperm concentration, motility and morphology, does not identify subtle defects in sperm chromatin architecture. Bulls appear to have stable chromatin, with low levels of DNA fragmentation. However, the nature of fragmentation and its impact on fertility remain unclear and there are no detailed reports characterizing the DNA organization and damage in this species. The intensive genetic selection, the use of artificial insemination and in vitro embryo production associated to the cryopreservation process can contribute to the chromatin damage and highlights the importance of sperm DNA integrity for the success of these technologies. Frozen-thawed semen samples from three ejaculates from a Nellore bull showed high levels of morphological sperm abnormalities (55.8±5.1%), and were selected for complementary tests. Damage of acrosomal (76.9±8.9%) and plasma membranes (75.7±9.3%) as well as sperm DNA strand breaks (13.8±9.5%) and protamination deficiency (3.7±0.6%) were significantly higher compared to the values measured in the semen of five Nellore bulls with normospermia (24.3±3.3%; 24.5±6.1%; 0.6±0.5%; 0.4±0.6% for acrosome, plasma membrane, DNA breaks and protamine deficiency, respectively) (P<0.05). Motility and percentage of spermatozoa with low mitochondrial potential showed no differences between groups. This study shows how routine semen analyses (in this case morphology) may point to the length and complexity of sperm cell damage emphasizing the importance of sperm function testing.(AU)


O exame de rotina de sêmen, o qual avalia a concentração de espermatozoides, a motilidade e a morfologia, pode não identificar defeitos sutis na arquitetura da cromatina de espermatozoides. Os touros parecem ter cromatina estável com baixos níveis de fragmentação do DNA. No entanto, a natureza da fragmentação e o seu impacto sobre a fertilidade ainda não estão claros e não há relatos que caracterizam a organização do DNA e os danos nessa espécie com mais detalhes. A seleção genética intensiva e o uso da inseminação artificial e da produção in vitro de embriões, além do processo de criopreservação, podem contribuir para o dano da cromatina, e sabe-se a importância da integridade do DNA espermático para o sucesso dessas tecnologias. Amostras de sêmen de três ejaculados de um touro Nelore com altos níveis de alterações morfológicas (55,8±5,1%) foram selecionadas para realização de exames complementares. Os danos de acrossoma (76,9±8,9%) e das membranas plasmáticas (75,7±9,3%), bem como quebras de fita de DNA de espermatozoides (13,8±9,5) e deficiência de protamina (3,7±0,6) foram significativamente maiores em comparação aos valores avaliados no sêmen de cinco touros Nelore com normospermia (24,3±3,3%; 24,5±6,1%; 0,6±0,5%; 0,4±0,6% para acrossoma, membrana plasmática, quebras de DNA e deficiência de protamina, respectivamente) (p<0,05). Motilidade e porcentagem de espermatozoides com baixo potencial mitocondrial não diferiram estatisticamente. Essas avaliações mostram que análises de sêmen de rotina (neste caso, morfologia) podem apontar para a extensão e a complexidade dos danos na célula espermática, o que indica que a deficiência de protamina e os danos no DNA podem ocorrer simultaneamente a defeitos morfológicos. Tal ocorrência enfatiza a importância das análises de sêmen clássicas e dos testes complementares.(AU)


Asunto(s)
Animales , Masculino , Bovinos , Semen , Espermatozoides/ultraestructura , Cromatina , Protaminas
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