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Cytogenetically, out of 262 species, only three species of family Platystictidae has been reported worldwide. Present study has been undertaken to study chromosome complement and its characterization of more species of this family. Cytogenetic analyses of Protosticta sanguinostigma Fraser, 1992 and Protosticta uncata Fraser, 1931 of family Platystictidae, collected from Andretta, Himachal Pradesh, India have been carried out on the basis of conventional staining, C-banding and silver nitrate staining. Both the species possess n=13m as haploid chromosome number and X0-XX sex determining mechanism. One large bivalent is present in all the meiotic stages of P. sanguinostigma which is considered as the species specific character. Chromosome complement of both the species shows variation in distribution of C-bands and Nucleolar organizer regions (NORs). Cytologically, both the species have been described for the first time.
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There are many unknown genetic factors that lead to infertility in nonobstructive azoospermia men. Here, we performed whole-exome sequencing in blood samples obtained from 40 azoospermia patients with meiotic arrest and found a novel c.151_154del (p.D51fs) frame-shift mutation in exon 3 of the testis expressed 11 (TEX11) gene in one patient. Sanger sequencing analysis of the patient and 288 fertile men was performed to validate the mutation. Immunohistochemical analysis showed TEX11 expression in late-pachytene spermatocytes and in round spermatids in fertile human testes. In contrast, testes of the patient with TEX11 mutation underwent meiotic arrest and lacked TEX11 expression. Western blotting of human embryonic kidney (HEK293) cells transfected with a vector for the p.D51fs TEX11 variant detected no TEX11 expression. In conclusion, we identified a novel frame-shift mutation in the TEX11 gene in an azoospermia patient, emphasizing that this gene should be included in genetic screening panels for the clinical evaluation of azoospermia patients.
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The synaptonemal complex (SC) is a meiosis-specific proteinaceous macromolecular structure that assembles between paired homologous chromosomes during meiosis in various eukaryotes. The SC has a highly conserved ultrastructure and plays critical roles in controlling multiple steps in meiotic recombination and crossover formation, ensuring accurate meiotic chromosome segregation. Recent studies in different organisms, facilitated by advances in super-resolution microscopy, have provided insights into the macromolecular structure of the SC, including the internal organization of the meiotic chromosome axis and SC central region, the regulatory pathways that control SC assembly and dynamics, and the biological functions exerted by the SC and its substructures. This review summarizes recent discoveries about how the SC is organized and regulated that help to explain the biological functions associated with this meiosis-specific structure.
Subject(s)
Animals , Chromosome Segregation , Meiosis/physiology , Synaptonemal Complex/physiologyABSTRACT
Azoospermia patients who carry a monogenetic mutation that causes meiotic arrest may have their biological child through genetic correction in spermatogonial stem cells (SSCs). However, such therapy for infertility has not been experimentally investigated yet. In this study, a mouse model with an X-linked testis-expressed 11 (TEX11) mutation (Tex11
Subject(s)
Animals , Male , Mice , Adult Germline Stem Cells/metabolism , Azoospermia/genetics , Infertility, Male/therapy , Mutation/genetics , Spermatogenesis/geneticsABSTRACT
Abstract Background: Oocyte quality and maturation are influenced by protein supplementation. Objective: To evaluate the influence of fetal bovine serum (FBS) and bovine serum albumin (BSA) concentrations on the recovery and in vitro maturation (IVM) of bovine oocytes. Methods: The study was divided into Stage 1 (oocyte recovery), and Stage 2 (IVM). In the first stage, three experiments were conducted according to the recovery (R) medium used: (R1) 10 vs. 20% FBS; (R2) 5 vs. 10% BSA; and (R3) the best results from R1, R2, and the combination of FBS+BSA (5+5%). Within the second stage, the maturation medium was supplemented according to three experiments: (M1) 5 vs. 10% FBS; (M2) 0.4 vs. 0.8% BSA; and (M3) better results of M1, M2, and the combination of FBS+BSA (5+0.8%). Results: In Stage 1 (R1 and R2), the media with 10% FBS and 10% BSA showed better oocyte quality results and were defined for experiment R3. In R3, the 10% FBS and the combination of FBS+BSA (5+5%) allowed recovery of better-quality oocytes. In Stage 2 (M1 and M2), media with both levels of FBS (5 and 10%) and 0.8% BSA were defined as better according to the maturation and viability rates of cumulus cells, so they were defined for experiment M3. In M3, no difference was noted among the supplements. Conclusions: For oocyte recovery, 10% FBS and the combination of FBS+BSA (5+5%) can be used to obtain immature oocytes. For the in vitro maturation, FBS (both levels, 5 and 10%) and BSA (0.8%) can be used alone or in combination.
Resumen Antecedentes: La calidad y maduración de los ovocitos son influenciados por la suplementación proteica. Objetivo: Evaluar la influencia de concentraciones de suero fetal bovino (FBS) y albúmina sérica bovina (BSA) en la recuperación y maduración in vitro (IVM) de ovocitos bovinos. Métodos: El estudio se dividió en Etapa 1 (recuperación de ovocitos) y Etapa 2 (IVM). En la primera etapa, tres experimentos se realizaron de acuerdo con el medio de recuperación: (R1) 10 vs. 20% FBS; (R2) 5 vs. 10% BSA; y (R3) los mejores resultados de R1, R2 y la combinación de FBS+BSA (5+5%). En la segunda etapa, el medio de maduración fue suplementado para tres experimentos: (M1) 5 vs. 10% FBS; (M2) 0,4 vs. 0,8% BSA; y (M3) mejores resultados de M1, M2 y la combinación de FBS+BSA (5+0,8%). Resultados: En la Etapa 1 (R1 y R2), los medios con 10% FBS y 10% BSA mostraron mejores resultados de calidad oocitaria y fueron definidos para el experimento R3. En R3, 10% FBS y la combinación de FBS+BSA (5+5%) permitieron la recuperación de ovocitos de mejor calidad. En la Etapa 2 (M1 y M2), los medios con ambos niveles de FBS (5 y 10%) y 0,8% de BSA se definieron como mejores de acuerdo con las tasas de maduración y viabilidad de las células del cumulus, por lo que se definieron para el experimento M3. En M3, no se observó diferencia entre los suplementos. Conclusiones: Para la recuperación de ovocitos, se puede utilizar 10% de FBS y la combinación de FBS+BSA (5+5%) para obtener ovocitos inmaduros. Para la maduración in vitro, FBS (ambos niveles, 5 y 10%) y BSA (0,8%) se pueden usar solos o en combinación.
Resumo Antecedentes: A qualidade e a maturação de oócitos são influenciadas pela suplementação proteica. Objetivo: Avaliar a influência de concentrações de soro fetal bovino (FBS) e albumina sérica bovina (BSA) sobre a recuperação e maturação in vitro (IVM) de oócitos bovinos. Métodos: O estudo foi dividido em Etapa 1 (recuperação de oócitos) e Etapa 2 (IVM). Na primeira etapa, três experimentos foram realizados de acordo com o meio de recuperação: (R1) 10 vs. 20% FBS; (R2) 5 vs. 10% BSA; e (R3) melhores resultados de R1, R2 e a combinação de FBS+BSA (5+5%). Na segunda etapa, o meio de maturação foi suplementado de acordo com três experimentos: (M1) 5 vs. 10% FBS; (M2) 0,4 vs. 0,8% BSA; e (M3) melhores resultados de M1, M2 e a combinação de FBS+BSA (5+0,8%). Resultados: Na Etapa 1 (R1 e R2), os meios com 10% FBS e 10% BSA mostraram melhores resultados de qualidade oocitária e foram definidos para o experimento R3. Em R3, 10% FBS e a combinação de FBS+BSA (5+5%) permitiram a recuperação de oócitos de melhor qualidade. Na segunda etapa (M1 e M2), meios com ambos os níveis de FBS (5 e 10%) e 0,8% BSA foram definidos como os melhores de acordo com as taxas de maturação e viabilidade de células do cumulus, então foram definidos para o experimento M3. No M3, não houve diferença entre os suplementos. Conclusões: Para a recuperação oocitária, 10% FBS e a combinação de FBS+BSA (5+5%) podem ser usados para obter oócitos imaturos. Para maturação in vitro, FBS (ambos os níveis, 5 e 10%) e BSA (0,8%) podem ser usados sozinhos ou em combinação.
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Background: recently, it has been proved that copolymers with dextran cores and grafted polyacrylamide are effective in photodynamic and chemotherapy. However, further research is needed to define correct dosage and to assess the risks. Thus, animal studies are becoming more relevant to determine the effect of the treatment of such drug nano-systems on female reproductive function in particular.Methods: a technique for estimation of pre- and post-implantation death rates, in vitro meotic maturation of oocytes, double fluorescent vital assay and statistical analysis were used. The effects of a one-time treatment of different doses of dextran-polyacrylamide matrices and silver (Ag)-nanoparticles-dextran-polyacrylamide (AgNPs-D-PAA) on reproductive function, namely on 1) the number of oocytes isolated from one ovary and the meiotic maturation of such oocytes in vitro; 2) the indicators of cell viability of the cells of follicular environment of oocytes (FEO) and the cells of inguinal lymph nodes (ILN); 3) the pre- and post-implantation mortality rates and the number of live newborns (pups) were investigated in female mice.Results: no significant changes in the number of oocytes isolated from one ovary and meiotic maturation of such ovarian oocytes in vitro, the number of living cells of follicular environment of oocytes and the number of such cells with morphological signs of apoptosis and necrosis, pre- and post-implantation mortality rates of embryos and the number of live newborns (pups) have been established under conditions of one-time treatment with dextran-polyacrylamide at doses of 0.39 mg/kg and 3.90 mg/kg and Ag-nanoparticles-dextran-polyacrylamide at doses of 0.20 mg/kg and 2.00 mg/kg.Conclusions: branched polymer systems (dextran-polyacrylamide (D-PAA) polymer matrices) are promising materials for use in next-generation medicine.
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Aim: The current experimental work has been designed to study the effect of UV-B exposure on the seedling growth and meiotic consequences of Eclipta alba (L.) Hassk.Methodology: The seedlings were exposed to UV-B radiation for different time durations, i.e., 40, 80, 120 min along with control sets. UV-B irradiated seedlings along with respective controls were sown in the field and young floral buds were fixed in Carnoy’s fixative for 24 hrs and preserved in 90% ethanol for meiotic study. Results: Exposure of UV-B exposure resulted in various chromosomal aberrations like stickiness, laggards, bridges, unorientation, precocious, multivalents etc. Chromosomal stickiness was profound abnormality encountered at shorter duration (40 min) to UV-B exposure. The results revealed that UV-B exposure for shorter duration is quite beneficial to plant as it induces significant cytomorphological and biochemical variations. Interpretation: Shorter exposure to UV-B radiation induced certain beneficial traits in Eclipta alba. Since, Eclipta alba is a medicinally significant plant, hence, it is essential to improve their quantitative and qualitative traits through induced mutagenesis using UV-B radiation to impel the novel characteristics of plant
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Mutation and recombination are primarily responsible for generating the genetic variability in natural populations of microorganisms, plant and animal species including humans. Upon such genetic variations, elemental forces of evolution such as natural selection, random genetic drift and migration operate to bring about micro-evolutionary changes. Recombination or crossing-over produces new combinations of genes due to interchange of corresponding segments between nonsister chromatids of homologous chromosomes, thus, it is an important evolutionary factor. Since the time of T. H. Morgan, Drosophila has been subjected to extensive investigations on crossing over while employing a number of markers, which were used for gene mapping. Interestingly, recombination occurs in females of D. melanogaster but not in males. Later on, male crossing over was investigated in various species and its occurrence was reported in D. melanogaster, D. ananassae, D. simulans, D. willistoni, D. littoralis and D. bipectinata. Recombination occurs at very low rate in all these species except for D. ananassae, which shows spontaneous male crossing over in appreciable frequency, which is meiotic in origin. This unusual phenomenon in D. ananassae is influenced by various genetic factors as well as it shows strain variation as far as frequency of male recombination is concerned. Further, the presence of chiasmata during meiosis in males at a frequency capable of accounting for the observed recombination frequency extends evidence for meiotic origin of recombination in males of D. ananassae.
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The stromal antigen 3 (STAG3) gene, encoding a meiosis-specific cohesin component, is a strong candidate for causing male infertility, but little is known about this gene so far. We identified STAG3 in patients with nonobstructive azoospermia (NOA) and normozoospermia in the Korean population. The coding regions and their intron boundaries of STAG3 were identified in 120 Korean men with spermatogenic impairments and 245 normal controls by using direct sequencing and haplotype analysis. A total of 30 sequence variations were identified in this study. Of the total, seven were exonic variants, 18 were intronic variants, one was in the 5'-UTR, and four were in the 3'-UTR. Pathogenic variations that directly caused NOA were not identified. However, two variants, c.3669+35C>G (rs1727130) and +198A>T (rs1052482), showed significant differences in the frequency between the patient and control groups (P = 0.021, odds ratio [OR]: 1.79, 95% confidence interval [CI]: 1.098-2.918) and were tightly linked in the linkage disequilibrium (LD) block. When pmir-rs1052482A was cotransfected with miR-3162-5p, there was a substantial decrease in luciferase activity, compared with pmir-rs1052482T. This result suggests that rs1052482 was located within a binding site of miR-3162-5p in the STAG3 3'-UTR, and the minor allele, the rs1052482T polymorphism, might offset inhibition by miR-3162-5p. We are the first to identify a total of 30 single-nucleotide variations (SNVs) of STAG3 gene in the Korean population. We found that two SNVs (rs1727130 and rs1052482) located in the 3'-UTR region may be associated with the NOA phenotype. Our findings contribute to understanding male infertility with spermatogenic impairment.
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ObjectiveThe mechanism of histone phosphorylation modification in oocyte meiosis is less studied. This study is designed to investigate the pattern of histone H3 phophorylation and regulation of maturation process in the porcine oocytes.MethodsThe histone H3Ser10 (H3S10) phosphorylation expression was examined on the porcine oocyte meiotic process. The porcine cumulus oocyte complexes (COCs) were divided into four groups, one group was cultured as control group, and the other 3 groups were supplemented with 5, 10, and 30 μmol/L ZM447439, and cultured in vitro for 27 h, respectively, 5, 10, and 30 μmol/L ZM4474349 treatment group. The proportion of each meiotic stage was counted. The phosphorylation pattern of histone H3S10 and the expression level of protein kinase Aurora B were detected at the porcine oocytes.ResultsCompared with histone H3S10 phosphorylation level of oocyte GVBD phase, the MI and AI phases were significantly increased (P<0.05), and H3S10 phosphorylation level of AI phase was remarkedly higher than that of MII phase (P<0.05). Compared with the control group, the proportion of oocytes at the GVBD phase in the 10 and 30 μmol/L ZM4447439 treatment group [(32.14±0.51)%, (95.34±0.59)%]was higher than that of the control group [(2.56±0.03)%, P<0.05], the proportion of oocytes at the MI phase [(66.88±0.13)%, (4.66±0.04)%] significantly decreased than that of the control group [(87.42±0.14)%, P<0.05], and the proportion of oocytes at the AI stage [(1.01±0.03)%, (0.000±0.00)%] significantly decreased compared with the control group[(10.02 ± 0.21)%, P<0.05]. Compared with the control group (0), oocytes H3S10 dephosphorylation modification ratio in the 10 μmol/L and 30 μmol/L ZM4474349 treatment group [(35.2±0.39)%, (95.4±0.65)%]significantly increased (P<0.05). Compared with the control group, the relative expression level of Aurora B in the 10 and 30 μmol/L ZM4447439 treatment group was significantly reduced (P<0.05).ConclusionHstone H3S10 phosphorylation plays arolein the maturation of mammalian oocytes. AuroraB kinase inhibitors (ZM447439) treatment can reduce H3S10 phosphorylation and Aurora B expression level and lead to oocytesmaturation disorder.
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Oocyte in vitro maturation (IVM) is the first step of the in vitro reproductive technologies that enables mature oocytes to be generated ex vivo and after used for embryo production. In this sense, the establishment of culture environment, as oocyte incubation time, is essential for the success of the IVM. Therefore, the study was carried out to investigate the relationship between the meiotic potential and the IVM times of collared peccary oocytes, wild mammals of great commercial and ecological interest. Thus, ovaries were collected of females derived from captivity and transported to the laboratory within 1 hour of slaughtering. The oocytes derived from follicles (3-6mm in diameter) were recovered by aspirated and sliced. Good quality oocytes (evenly granulated cytoplasm with a least one layer of surrounding cumulus cells) were selected and subjected to culture in TCM 199 supplemented with 10µg/mL FSH, 10% FBS and 100µM cysteamine at 38.5°C, 5% CO2 and maximum humidity for 24 or 48 hours. After the incubation period, the nuclear status, the presence of first polar body and the expansion of cumulus cells of oocytes were assessed. The data obtained were analyzed by Fisher exact test (P<0.05). A total of four sessions (2-3 females per session) were performed, resulting in eighteen aspirated and sliced ovaries with normal morphological characteristics. An oocyte recovery rate of about 83.1% (59/71) was obtained with 3.3 oocytes/ovary and 2.3 viable oocytes/ovary. After different incubation times, differences (P<0.05) were observed in 24 and 48 hours for expansion of the cumulus cells (38.1% vs. 100%), presence of first polar body (52.4% vs. 90.5%) and nuclear status in second metaphase (19.0% vs. 76.2%), respectively. In conclusion, 48 hours is suitable time for the in vitro maturation of oocytes derived from collared peccaries when compared to the time of 24 hours, according to the meiotic potential observed. Additional studies should be conducted to improve the quality of the oocyte culture environment, as medium composition, aiming to obtain viable mature oocytes for other in vitro biotechnologies.(AU)
A maturação in vitro (MIV) oocitária é a primeira etapa das tecnologias reprodutivas in vitro que permite que oócitos maturados sejam gerados ex vivo e depois usados para a produção de embriões. Nesse sentido, o estabelecimento do ambiente de cultivo, como o período de incubação de oócitos, é essencial para o sucesso da MIV. Portanto, o estudo foi realizado para investigar a relação entre o potencial meiótico e os períodos de MIV de oócitos derivados de catetos, mamíferos silvestres de grande interesse comercial e ecológico. Para tanto, os ovários foram coletados de fêmeas derivadas de cativeiro e transportados ao laboratório dentro de 1 h após o abate. Os oócitos derivados de folículos (3-6mm de diâmetro) foram recuperados por aspiração e fatiados. Oócitos de boa qualidade (citoplasma uniformemente granulado com pelo menos uma camada circundante de células cumulus) foram selecionados e submetidos ao cultivo em TCM 199 suplementado com 10µg/mL de FSH, 10% de SFB e 100μM de cisteamina a 38,5°C, 5% de CO2 e umidade máxima por 24 e 48 h. Após o período de incubação, o estado nuclear, a presença do primeiro corpúsculo polar e a expansão das células do cumulus dos oócitos foi avaliada. Os dados obtidos foram analisados pelo teste exato de Fisher (P<0,05). Um total de quatro sessões (2-3 fêmeas por sessão) foi realizado, resultando em dezoito ovários aspirados e fatiados com características morfológicas normais. Uma taxa de recuperação oocitária de aproximadamente 83,1% (59/71) foi obtida com 3,3 oócitos/ovário e 2,3 oócitos viáveis/ovário. Após diferentes períodos de incubação, diferenças (P<0,05) foram observadas entre 24 e 48 h para a expansão das células cumulus (38,1% vs. 100%), presença de primeiro corpúsculo polar (52,4% vs. 90,5%) e estado nuclear na segunda metáfase (19,0% vs. 76,2%), respectivamente. Em conclusão, 48 h é o período adequado para a maturação in vitro de oócitos derivados de catetos quando comparado ao tempo de 24 h, de acordo com o potencial meiótico observado. Estudos adicionais devem ser conduzidos para melhorar a qualidade do ambiente de cultivo oocitário, como a composição de meio, objetivando obter oócitos maturados viáveis para outras biotecnologias in vitro.(AU)
Subject(s)
Animals , Artiodactyla/physiology , Infectious Disease Incubation Period , In Vitro Oocyte Maturation Techniques/methods , Mammals/physiologyABSTRACT
Abstract Sisyrinchium is the largest genus of Iridaceae in the Americas and has the greatest amount of cytological data available. This study aimed at investigating how genomes evolved in this genus. Chromosome number, genome size and altitude from species of sect. Viperella were analyzed in a phylogenetic context. Meiotic and pollen analyses were performed to assess reproductive success of natural populations, especially from those polyploid taxa. Character optimizations revealed that the common ancestor of sect. Viperella was probably diploid (2n = 2x =18) with two subsequent polyplodization events. Total DNA content (2C) varied considerably across the phylogeny with larger genomes detected mainly in polyploid species. Altitude also varied across the phylogeny, however no significant relationship was found between DNA content changes and altitude in our data set. All taxa presented regular meiosis and pollen viability (> 87%), except for S. sp. nov. aff. alatum (22.70%), suggesting a recent hybrid origin. Chromosome number is mostly constant within this section and polyploidy is the only source of modification. Although 2C varied considerably among the 20 taxa investigated, the diversity observed cannot be attributed only to polyploidy events because large variations of DNA content were also observed among diploids.
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ABSTRACT: Synthetic wheat is developed by crossing tetraploid species ( Triticum turgidum , AABB) with a diploid species ( Aegilops tauschii , DD), followed by chromosome duplication through the use of colchicine to restore the resultant sterile hybrid to a fertile hexaploid plant. The main importance of producing synthetically improved wheat is to increase their genetic variability and to incorporate genes that code for resistance to biotic and abiotic stressors. This study aimed to evaluate the presence of micronuclei (MN) and the meiotic index (MI) in the tetrad phase in synthetic wheat accessions and cultivars ( Triticum aestivum ) stored at the Germplasm Bank of Embrapa Trigo (Brazil), in order to identify and select genetically stable accessions for plant improvement. Five plants were collected by genotype, prior to anthesis, and the tissues were fixed in Carnoy solution. Cytological slides were prepared by the smash method, and the cells were dyed with 1% acetocarmine and observed under an optical microscope. Presence of MN was observed in all genotypes analyzed, and variability of genetic stability was reported in the two years of analysis. In 2014, the highest MI of synthetic wheat accessions was 96.86% and the lowest was 46.32%. In 2015, the highest MI was 96.60% and the lowest was 47.96%. Based on the results, some genotypes were considered meiotically stable and suitable for use in wheat breeding programs.
RESUMO: Trigos sintéticos são resultados do cruzamento entre uma espécie tetraploide ( Triticum turgidum, AABB) e uma espécie diploide ( Aegilops tauschii , DD) originando um híbrido estéril, seguido por duplicação cromossômica, por meio de colchicina, para restabelecer um trigo hexaploide fértil. A principal importância do uso de trigos sintéticos no melhoramento é que possibilitam aumentar a variabilidade genética, bem como introgredir genes de resistência a estresses bióticos e abióticos. O presente estudo teve como objetivo avaliar a presença de micronúcleos (MCN) e índice meiótico (IM) na fase de tétrades, em acessos de trigos sintéticos e cultivares testemunhas ( T. aestivum ), armazenadas no Banco de Germoplasma da Embrapa Trigo, a fim de selecionar os acessos estáveis geneticamente e disponibilizar ao melhoramento. Cinco plantas por genótipos, na fase anterior à antese, foram coletadas e fixadas em solução Carnoy. As lâminas citológicas foram preparadas pelo método de maceração e a coloração das células com carmim acético 1%. As observações foram em microscópio óptico. Observou-se a presença de micronúcleos em todos os genótipos analisados e foi encontrado variabilidade quanto à estabilidade genética nos dois anos de análises. Em 2014, o percentual máximo de IM dos acessos de trigos sintéticos foi de 96,86% e o mínimo de 46,32%. Em 2015, o percentual de IM máximo foi de 96,60% e o mínimo de 47,96%. Com base nos resultados, alguns genótipos foram considerados meioticamente estáveis e, poderão ser utilizados em programas de melhoramento genético de trigo.
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Fusarium graminearum, a pathogen of wheat and barley, is a haploid homothallic ascomycete filamentous fungus (Goswami and Kistler 2004). It overwinters as saprophytic hyphae in plant debris and undergoes the sexual cycle in spring to produce fruiting bodies (perithecia) bearing the progeny ascospores. The genome sequence of the F. graminearum PH-1 strain was reported last year (King et al. 2015). This year, Jin-Rong Xu and colleagues in Northwest A&F University, China, and Purdue University, USA, re-sequenced the PH-1 genome and also performed RNA-Seq analysis on two independent biological replicates each of RNA from conidia, hyphae, and 8-day post-fertilization perithecia (Liu et al. 2016). Alignment of the two replicate perithecial RNA-Seq reads with the reference genome sequence revealed 23,041 and 19,764 single-nucleotide variants (SNVs), of which, respectively, 22,578 and 19,261 corresponded to A (adenosine)- to-G (guanosine) transitions, and 17,613 A-to-G transitions were common to both the replicates. Non- A-to-G variants were far fewer (463 and 503) and only 35.9% were common between the two perithecial replicates, suggesting that the non-A-to-G variants were false-positives. In sum, 26,056 A-to-G variants were identified as putative A-to-I RNA editing sites at which hydrolytic deamination at the C6 position of the purine ring of A produces I (inosine). Since I preferentially base-pairs with C (cytidine), an I within a transcript is read as G by the translation machinery. Also, during reverse transcription, I directs the incorporation of C; thus, it appears as a G in double-stranded cDNA. The conidial and hyphal RNA-Seq data showed only 68 and 112 A-to-G transitions and 335 and 452 non-A-to-G conversions, indicating that the A-to-I RNA editing is specific to the sexual stage. Xu and colleagues had initially set out to do a yeast two-hybrid experiment to identify proteins that interact with a protein kinase named Puk1 (perithecium unique kinase 1). Ascospores from the puk1 mutant have an abnormal morphology. Additionally, qRT-PCR showed that PUK1 transcription is markedly upregulated in perithecia, suggesting that PUK1 expression and function might be restricted to the sexual stage. Therefore, to generate the PUK1 ORF bait, they synthesized cDNA using RNA isolated from perithecial cultures of the PH-1 strain. Sequencing of the construct revealed that two tandem stop codons – UAG UAG – in the PUK1 ORF were changed to UGG UGG in the cDNA, presumably via A-to-I RNA editing. More than 90% of PUK1 reads in perithecial RNA-Seq showed the A-to-I editing, and experiments with site-specific mutant alleles showed that the editing was essential for PUK1 function. This was an unexpected discovery because fungi lack orthologs of the Adenosine Deaminase Acting on RNA (ADAR) family of enzymes that in metazoans converts A to I in double-stranded RNA. Presumably, A-to-I RNA editing in fungi uses different enzymes than animals. This discovery motivated Xu and colleagues to expand the search for RNA editing genome-wide in transcriptomes from vegetative and sexual-stage tissues (conidia, hyphae, and perithecia). The percentage of reads with the A-to-G variant was taken as the RNA editing level at the site. Editing levels varied from 3% to 100%. Strikingly, 47% of genes bearing sites with editing levels >60% tended to be up-regulated or specifically expressed in perithecia compared to conidia and hyphae. A majority of the editing events resulted in amino acid substitutions, which suggested that Ato- I editing might be important for adaptation of protein functions during sexual reproduction. Editing events similar to those in PUK1 were found 69 other genes, including the rid (RIP defective) ortholog and genes important for meiosis (see below). All these genes displayed UAG-to-UGG change in exons that automated annotation had incorrectly predicted as introns.
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Chromosomal abnormalities are seen in nearly 1% of live born infants. We report a 5‑year‑old boy with the clinical features of Down syndrome, which is the most common human aneuploidy. Cytogenetic analysis showed a mosaicism for a double aneuploidy, Down syndrome and XYY. The karyotype was 47, XY,+21[19]/48, XYY,+21[6]. ish XYY (DXZ1 × 1, DYZ1 × 2). Mosaic double aneuploidies are very rare and features of only one of the aneuploidies may predominate in childhood. Cytogenetic analysis is recommended even if the typical features of a recognized aneuploidy are present so that any associated abnormality may be detected. This will enable early intervention to provide the adequate supportive care and management.
Subject(s)
Aneuploidy , Child, Preschool , Chromosomes, Human, X/genetics , Chromosomes, Human, Y/genetics , Disorders of Sex Development/genetics , Down Syndrome/epidemiology , Down Syndrome/genetics , Humans , Male , Sex Chromosome Aberrations , Sex Chromosome Disorders of Sex Development/geneticsABSTRACT
O objetivo deste trabalho foi estudar o comportamento meiótico e a viabilidade polínica em quatro acessos das espécies Capsicum annuum e Capsicum baccatum. Em todos os acessos, foram observados 12 bivalentes, confirmando o número e nível de ploidia relatados na literatura para essas espécies. Os resultados mostraram uma divisão celular normal, porém algumas anormalidades foram detectadas, tais como migração precoce dos cromossomos em metáfases I e II, cromossomos retardatários em anáfase I e divisão assincrônica. Os acessos estudados apresentaram um índice meiótico variando de 75,6 a 93,6 por cento, e a viabilidade polínica em todos os acessos foi superior a 90 por cento, demonstrando que as irregularidades meióticas observadas não comprometeram a viabilidade destes.
The objective of this research was to study the meiotic behavior and pollen viability in four accessions of species Capsicum annuum and Capsicum baccatum. In all accessions, twelve bivalents were observed, confirming the number and ploidy level reported in the literature for these species. The results showed a normal cell division although some abnormalities had been detected, as early chromosome migration at metaphases I and II, later chromosomes at anaphase I and asynchronous division. The studied accessions presented a meiotic index (MI) that varied from 75.6 to 93.6 percent and the pollen viability in all accessions was higher than 90 percent, demonstrating that the meiotic irregularities observed didn't affect their viability.
ABSTRACT
Background & objectives: The study was taken up to define criteria of normality for meiosis by assessing the frequency of meiotic prophase cell types, the frequency of pachytene substage in normal and abnormal spermatogenesis and to determine what synaptonemal complex. Methods: A quantitative and qualitative analysis of the first meiotic prophase was performed in 10 patients presenting with non-obstructive infertility and 10 controls, using dual colour immunocytochemistry with SCP3 and BRCA1 which visualise axial elements and synaptonemal complexes (SC). The respective frequencies of the leptotene, zygotene and pachytene stages as well as the frequencies of the four substages of pachytene were evaluated. The frequencies of the main types of meiotic abnormalities at pachytene were also assessed. Results: The frequencies of leptotene and zygotene stages were significantly higher in patients (7.95 and 9.75%) than in controls (2.30 and 1.45%), whereas the frequency of pachytene was significantly higher in controls than in patients (96.25 vs. 75.30%). Detailed analysis of the sex chromosomes revealed that the controls showed a presence of late pachytene substages (P3 + P4 = 64.40%), whereas the patients showed a early pachytene substages (P1 + P2 = 63.40%). From these results, a new index was defined to evaluate spermatogenesis: the Pachytene Index, or PI (PI = P1 + P2 / P1 + P2 + P3 + P4). The same abnormalities (asynapsis, fragmented SC, dotted SC, thin SC) were observed in controls and in patients, but with different frequencies. The most frequent abnormality was fragmented SC, with a significant difference between patients and controls (15.28 vs. 9.74%). There was a significant difference between patients and controls for the frequency of asynapsed nuclei (7.97 vs. 2.95%) while the difference in other abnormalities were not significant. Interpretation & conclusion: The accumulation of early primary spermatocytes is an indication that progression of meiosis is defective in spermatogenesis failures. The value of the PI less than 0.50 indicates that the kinetic of meiosis is normal at pachytene. There is no normal spermatogenesis when the frequency of one or several SC abnormalities is significantly higher than in controls and/ or when the PI is more than 0.50.
Subject(s)
Adult , Azoospermia/pathology , Azoospermia/physiopathology , BRCA1 Protein/metabolism , Disease Progression , Humans , Male , Meiotic Prophase I/physiology , Middle Aged , Nuclear Proteins/metabolism , Spermatocytes/metabolism , Spermatocytes/pathology , Spermatogenesis/physiology , Synaptonemal Complex/metabolism , Synaptonemal Complex/pathology , Testis/pathology , Testis/physiopathology , Young AdultABSTRACT
O artigo refere-se a uma atualização sobre os mecanismos fisiológicos e bioquímicos envolvidos na ovogênesis de mamífero.(AU)
The article concern with an up to date about physiologic and biochemical mechanism of ovogenesis in mammals.(AU)