RESUMEN
KEY MESSAGE: Unreduced megagametophytes via second-division restitution were confirmed through heterozygosity analysis, and four candidate physical centromeres of rubber were located for the first time. The evaluation of maternal heterozygosity restitution (MHR) is vital in identifying the mechanism of 2n gametogenesis and assessing the utilization value of 2n gametes. In this study, three full-sib triploid populations were employed to evaluate the MHR of 2n female gametes of rubber tree clone GT1 and to confirm their genetic derivation. The 2n female gametes of GT1 were derived from second-division restitution (SDR) and transmitted more than half of the parental heterozygosity. In addition, low recombination frequency markers were developed, and four candidate physical centromeres of rubber tree were located for the first time. The confirmation that 2n female gametes of rubber tree clone GT1 are derived from SDR provides insights into the molecular mechanisms of 2n gametogenesis. In addition, the identified centromere location will aid in the development of centromeric markers for the rapid identification of the 2n gametogenesis mechanism.
Asunto(s)
Hevea , Triploidía , Hevea/genética , Diploidia , Células Germinativas , Centrómero/genéticaRESUMEN
Monoterpenes are the main component in essential oils of Lippia alba. In this species, the chemical composition of essential oils varies with genome size: citral (geraniol and neral) is dominant in diploids and tetraploids, and linalool in triploids. Because environmental stress impacts various metabolic pathways, we hypothesized that stress responses in L. alba could alter the relationship between genome size and essential oil composition. Water stress affects the flowering, production, and reproduction of plants. Here, we evaluated the effect of water stress on morphophysiology, essential oil production, and the expression of genes related to monoterpene synthesis in diploid, triploid, and tetraploid accessions of L. alba cultivated in vitro for 40 days. First, using transcriptome data, we performed de novo gene assembly and identified orthologous genes using phylogenetic and clustering-based approaches. The expression of candidate genes related to terpene biosynthesis was estimated by real-time quantitative PCR. Next, we assessed the expression of these genes under water stress conditions, whereby 1% PEG-4000 was added to MS medium. Water stress modulated L. alba morphophysiology at all ploidal levels. Gene expression and essential oil production were affected in triploid accessions. Polyploid accessions showed greater growth and metabolic tolerance under stress compared to diploids. These results confirm the complex regulation of metabolic pathways such as the production of essential oils in polyploid genomes. In addition, they highlight aspects of genotype and environment interactions, which may be important for the conservation of tropical biodiversity.
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Monoterpenos Acíclicos , Lippia , Aceites Volátiles , Verbenaceae , Lippia/genética , Lippia/química , Triploidía , Deshidratación , Filogenia , Aceites Volátiles/químicaRESUMEN
Biotechniques, including surrogate propagation derived from primordial germ cell (PGC) transplantation, are valuable tools for the reconstitution of endangered fish species. Although promising, there are no previous studies reporting such approaches using neotropical fish species. The aim of this study was to establish germline chimeras in neotropical fish by using the yellowtail tetra Astyanax altiparanae as a model species of the order Characiformes. Germline chimeras were obtained after transplantation of PGCs cultivated under different conditions: saline medium and supplemented with DMEM, amino acids, vitamins, glutamine, pyruvate, and fetal bovine serum, and subsequently transplanted into A. altiparanae triploids and triploid hybrids from the cross between A. altiparanae (â) and A. fasciatus (â). The results indicate ectopic migration in host embryos after transplantation of PGCs cultivated in saline medium. However, PGCs cultivated in supplemented medium migrated to the region of the gonadal ridge in 4.5% of triploid and 19.3% in triploid hybrid. In addition, the higher expression of dnd1, ddx4 and dazl genes was found in PGCs cultivated in supplemented culture medium. This indicates that the culture medium influences the maintenance and development of the cultivated cells. The expression levels of nanos and cxcr4b (related to the differentiation and migration of PGCs) were decreased in PGCs from the supplemented culture medium, supporting the results of ectopic migration. This is the first study to report the transplantation of PGCs to obtain germline chimera in neotropical species. The establishment of micromanipulation procedures in a model neotropical species will open new insights for the conservation of endangered species.
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Characiformes , Triploidía , Animales , Células Germinativas , Diferenciación Celular , MicromanipulaciónRESUMEN
Triploidization plays an important role in aquaculture and surrogate technologies. In this study, we induced triploidy in the matrinxã fish (Brycon amazonicus) using a heat-shock technique. Embryos at 2 min post fertilization (mpf) were heat shocked at 38°C, 40°C, or 42°C for 2 min. Untreated, intact embryos were used as a control. Survival rates during early development were monitored and ploidy status was confirmed using flow cytometry and nuclear diameter analysis of erythrocytes. The hatching rate reduced with heat-shock treatment, and heat-shock treatments at 42°C resulted in no hatching events. Optimal results were obtained at 40°C with 95% of larvae exhibiting triploidy. Therefore, we report that heat-shock treatments of embryos (2 mpf) at 40°C for 2 min is an effective way to induce triploid individuals in B. amazonicus.
Asunto(s)
Characiformes , Triploidía , Animales , Acuicultura , Respuesta al Choque Térmico , Humanos , LarvaRESUMEN
Triploid fish are usually sterile. Thus, the energy and nutrients intended for sexual maturation may be available to enhance flesh quality and physical growth. The present study aimed to investigate differences in the metabolic substrates, lipids and proteins, between storage tissues from diploid and triploid female rainbow trout. Monthly, metabolic substrates were quantified in liver, muscle, and ovaries, which were collected during the first reproductive cycle. In general, it was possible to identify a seasonal and similar deposition of metabolites in different tissues of 2n and 3n females, mainly at early stages of gonadal maturation. However, from the stages 5-6, the ovaries showed great differences between ploidies, with higher concentration of lipids and protein in 2n females. This result reflects the incorporation of vitellogenin in oocytes, which is a process that does not occur in 3n females. It was possible to observe seasonal hepato-somatic index changes in 2n females, with higher values observed in the post-ovulatory stage, and the triploid animals showed lower values compared to 2n, with no seasonal difference. Viscero-somatic index can reflect the mobilization of substrates, with higher values found for 2n females in stage 5-6, which is the period of active mobilization of tissue substrates.(AU)
Asunto(s)
Animales , Oncorhynchus mykiss/genética , Oncorhynchus mykiss/metabolismo , Oncorhynchus mykiss/fisiología , TriploidíaRESUMEN
Triploid fish are usually sterile. Thus, the energy and nutrients intended for sexual maturation may be available to enhance flesh quality and physical growth. The present study aimed to investigate differences in the metabolic substrates, lipids and proteins, between storage tissues from diploid and triploid female rainbow trout. Monthly, metabolic substrates were quantified in liver, muscle, and ovaries, which were collected during the first reproductive cycle. In general, it was possible to identify a seasonal and similar deposition of metabolites in different tissues of 2n and 3n females, mainly at early stages of gonadal maturation. However, from the stages 5-6, the ovaries showed great differences between ploidies, with higher concentration of lipids and protein in 2n females. This result reflects the incorporation of vitellogenin in oocytes, which is a process that does not occur in 3n females. It was possible to observe seasonal hepato-somatic index changes in 2n females, with higher values observed in the post-ovulatory stage, and the triploid animals showed lower values compared to 2n, with no seasonal difference. Viscero-somatic index can reflect the mobilization of substrates, with higher values found for 2n females in stage 5-6, which is the period of active mobilization of tissue substrates.
Asunto(s)
Animales , Oncorhynchus mykiss/fisiología , Oncorhynchus mykiss/genética , Oncorhynchus mykiss/metabolismo , TriploidíaRESUMEN
Breeders rely on genetic integrity of material from genebanks; however, admixture, mislabeling, and errors in original data can occur and be detrimental. Two hundred and fifty accessions, representing paired samples consisting of original mother plants and their in vitro counterparts from the cultivated potato collection at the International Potato Center (CIP) were fingerprinted using the Infinium 12K V2 Potato Array to confirm genetic identity of the accessions and evaluate genetic diversity of the potato collection. Diploid, triploid, and tetraploid accessions were included, representing seven cultivated potato taxa (based on Hawkes, 1990). Fingerprints between voucher mother plants maintained in the field and in vitro clones of the same accession were used to evaluate identity, relatedness, and ancestry using hierarchal clustering and model-based Bayesian admixture analyses. Generally, in vitro and field clones of the same accession grouped together; however, 11 (4.4%) accessions were mismatches genetically, and in some cases the SNP data revealed the identity of the mixed accession. SNP genotypes were used to assess genetic diversity and to evaluate inter- and intraspecific relationships along with determining population structure and hybrid origins. Phylogenetic analyses suggest that the triploids included in this study are genetically similar. Further, some genetic redundancies among individual accessions were also identified along with some putative misclassified accessions. Accessions generally clustered together based on taxonomic classification and ploidy level with some deviations. STRUCTURE analysis identified six populations with significant gene flow among the populations, as well as revealed hybrid taxa and accessions. Overall, the Infinium 12K V2 Potato Array proved useful in confirming identity and highlighting the diversity in this subset of the CIP collection, providing new insights into the accessions evaluated. This study provides a model for genetic identity of plant genetic resources collections as mistakes in conservation of these collections and in genebanks is a reality. For breeders and other users of these collections, confirmed identity is critical, as well as for quality management programs and to provide insights into the accessions evaluated.
Asunto(s)
Dermatoglifia del ADN/métodos , Variación Genética , Solanum tuberosum/genética , Teorema de Bayes , Bancos de Muestras Biológicas , Diploidia , Genotipo , Filogenia , Polimorfismo de Nucleótido Simple , Solanum tuberosum/clasificación , Especificidad de la Especie , Tetraploidía , TriploidíaRESUMEN
Background and Aims: Two main types of triploid limes are produced worldwide. The 'Tahiti' lime type (Citrus latifolia) is predominant, while the 'Tanepao' type (C. aurantiifolia) is produced to a lesser extent. Both types result from natural interspecific hybridization involving a diploid gamete of C. aurantiifolia 'Mexican' lime type (itself a direct interspecific C. micrantha × C. medica hybrid). The meiotic behaviour of a doubled-diploid 'Mexican' lime, the interspecific micrantha/medica recombination and the resulting diploid gamete structures were analysed to investigate the possibility that 'Tahiti' and 'Tanepao' varieties are derived from natural interploid hybridization. Methods: A population of 85 tetraploid hybrids was established between a doubled-diploid clementine and a doubled-diploid 'Mexican' lime and used to infer the genotypes of 'Mexican' lime diploid gametes. Meiotic behaviour was studied through combined segregation analysis of 35 simple sequenbce repeat (SSR) and single nucleotide polymorphismn (SNP) markers covering the nine citrus chromosomes and cytogenetic studies. It was supplemented by pollen viability assessment. Key Results: Pollen viability of the doubled-diploid Mexican lime (64 %) was much higher than that of the diploid. On average, 65 % of the chromosomes paired as bivalents and 31.4 % as tetravalents. Parental heterozygosity restitution ranged from 83 to 99 %. Disomic inheritance with high preferential pairing values was deduced for three chromosomes. Intermediate inheritances, with disomic trend, were found for five chromosomes, and an intermediate inheritance was observed for one chromosome. The average effective interspecific recombination rate was low (1.2 cM Mb-1). Conclusion: The doubled-diploid 'Mexican' lime had predominantly disomic segregation, producing interspecific diploid gamete structures with high C. medica/C. micrantha heterozygosity, compatible with the phylogenomic structures of triploid C. latifolia and C. aurantiifolia varieties. This disomic trend limits effective interspecific recombination and diversity of the diploid gamete population. Interploid reconstruction breeding using doubled-diploid lime as one parent is a promising approach for triploid lime diversification.
Asunto(s)
Citrus aurantiifolia/genética , Citrus/genética , Diploidia , Hibridación Genética/genética , Triploidía , Mapeo Cromosómico , Cromosomas de las Plantas/genética , Citogenética , Marcadores Genéticos/genética , Técnicas de Genotipaje , Repeticiones de Microsatélite/genética , Polen/genética , Polimorfismo de Nucleótido Simple/genética , Recombinación Genética/genéticaRESUMEN
Triploids can play an important role in polyploid evolution. However, their frequent sterility is an obstacle for the origin and establishment of neotetraploids. Here we analyzed the microsporogenesis of triploids (x = 7) and the crossability among cytotypes of Turnera sidoides, aiming to test the impact of triploids on the origin and demographic establishment of tetraploids in natural populations. Triploids of T. sidoides exhibit irregular meiotic behavior. The high frequency of monovalents and of trivalents with non-convergent orientations results in unbalanced and/or non-viable male gametes. In spite of abnormalities in chromosome pairing and unbalanced chromosome segregation, triploids are not completely sterile and yielded up to 67% of viable pollen. Triploids that originated by the fusion of 2n × n gametes of the same taxon showed more regular meiotic behavior and higher fertility than triploids from the contact zone of diploids and tetraploids or triploids of hybrid origin. The reproductive isolation of T. sidoides cytotypes of different ploidy level is not strict and the 'triploid block' may be overcome occasionally. Triploids of T. sidoides produce diploid and triploid progeny suggesting that new generations of polyploids could originate from crosses between triploids or from backcrosses with diploids. The capability of T. sidoides to multiply asexually by rhizomes, would enhance the likelihood that a low frequency of neopolyploids can be originated and maintained in natural populations of T. sidoides.
Asunto(s)
Polen/crecimiento & desarrollo , Triploidía , Turnera/genética , Argentina , Evolución Molecular , Dinámica Poblacional , Reproducción , Turnera/crecimiento & desarrolloRESUMEN
The concentrations of Cu, Cd, Pb, Zn, and Hg in diploid and triploid oysters from three farms (Guasave, Ahome, and Navolato) on the north-central coast of Sinaloa, Mexico, were assessed based on samples recovered during a single culture cycle 2013-2014. Metal burdens were more strongly correlated (p < 0.05) with the location of the farm than with either the ploidy or the interaction of both variables. The metal concentration ranking for oysters of both ploidies from the three farms was Zn > Cu > Cd > Pb > Hg. For all three farms, the mean concentrations of Cd and Pb in Crassostrea gigas were high, ranging from 2.52 to 7.98 µg/g wet weight for Cd and from 0.91 to 2.83 µg/g wet weight for Pb. Diploid and triploid oysters from the Guasave farm contained high levels of Cu (76.41 and 68.97 µg/g wet weight, respectively). Cu, Cd, and Zn were highly correlated (p < 0.05), and their concentrations may be influenced by agrochemical inputs. The mean levels of Cu for the Guasave farm and of Cd and Pb for all three farms exceeded permissible limits and represented a threat to human health during the sampling period (July 2014 to July 2014).
Asunto(s)
Crassostrea/química , Diploidia , Monitoreo del Ambiente/métodos , Metales Pesados/análisis , Triploidía , Contaminantes Químicos del Agua/análisis , Animales , Acuicultura , Crassostrea/genética , Humanos , MéxicoRESUMEN
This study aimed to examine the gonadal morphology of diploid and triploid fish through stereological analysis. Triploid individuals were obtained after temperature shock (40°C for 2 min) at 2 min post-fertilization and reared until 175 days post-fertilization (dpf). Intact eggs were used to obtain the diploids. Gonads were collected for histological analysis at 83, 114, 144 and 175 dpf. Diploid females and males presented normal oogenesis and spermatogenesis through all the experimental period. Conversely, stereological analysis revealed that triploid females were sterile and oogonia were the prevalent cell type in the ovaries. Triploid males presented increased amounts of spermatocyte cysts and a large area of lumen when compared with diploids and in addition the amount of spermatozoa was lower than that observed for diploids. However, some triploid males presented spermatogenesis similar to diploids. Therefore, we concluded that triploidization is an interesting alternative to produce sterile individuals in A. altiparanae.
Asunto(s)
Characidae/fisiología , Diploidia , Ovario/citología , Testículo/citología , Triploidía , Animales , Recuento de Células , Characidae/genética , Femenino , Masculino , Oocitos/fisiología , Oogénesis , Ovario/fisiología , Espermatocitos , Espermatogénesis , Testículo/fisiologíaRESUMEN
Background and Aims: Allopolyploids exhibit both different levels and different patterns of genetic variation than are typical of diploids. However, scant attention has been given to the partitioning of allelic information and diversity in allopolyploids, particularly that among homeologous monoploid components of the hologenome. Sphagnum × falcatulum is a double allopolyploid peat moss that spans a considerable portion of the Holantarctic. With monoploid genomes from three ancestral species, this organism exhibits a complex evolutionary history involving serial inter-subgeneric allopolyploidizations. Methods: Studying populations from three disjunct regions [South Island (New Zealand); Tierra de Fuego archipelago (Chile, Argentina); Tasmania (Australia)], allelic information for five highly stable microsatellite markers that differed among the three (ancestral) monoploid genomes was examined. Using Shannon information and diversity measures, the holoploid information, as well as the information within and among the three component monoploid genomes, was partitioned into separate components for individuals within and among populations and regions, and those information components were then converted into corresponding diversity measures. Key Results: The majority (76 %) of alleles detected across these five markers are most likely to have been captured by hybridization, but the information within each of the three monoploid genomes varied, suggesting a history of recurrent allopolyploidization between ancestral species containing different levels of genetic diversity. Information within individuals, equivalent to the information among monoploid genomes (for this dataset), was relatively stable, and represented 83 % of the grand total information across the Holantarctic, with both inter-regional and inter-population diversification each accounting for about 5 % of the total information. Conclusions: Sphagnum × falcatulum probably inherited the great majority of its genetic diversity at these markers by reticulation, rather than by subsequent evolutionary radiation. However, some post-hybridization genetic diversification has become fixed in at least one regional population. Methodology allowing statistical analysis of any ploidy level is presented.
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Evolución Biológica , Hibridación Genética , Sphagnopsida/genética , Triploidía , Alelos , Argentina , Australia , Chile , Variación Genética , Genoma de Planta , Repeticiones de Microsatélite , Nueva Zelanda , TasmaniaRESUMEN
This study aims to explore the roles of somatic embryogenesis receptor-like kinase (SERK) in Malus hupehensis (Pingyi Tiancha). The full-length sequences of SERK1 in triploid Pingyi Tiancha (3n) and a tetraploid hybrid strain 33# (4n) were cloned, sequenced, and designated as MhSERK1 and MhdSERK1, respectively. Multiple alignments of amino acid sequences were conducted to identify similarity between MhSERK1 and MhdSERK1 and SERK sequences in other species, and a neighbor-joining phylogenetic tree was constructed to elucidate their phylogenetic relations. Expression levels of MhSERK1 and MhdSERK1 in different tissues and developmental stages were investigated using quantitative real-time PCR. The coding sequence lengths of MhSERK1 and MhdSERK1 were 1899 bp (encoding 632 amino acids) and 1881 bp (encoding 626 amino acids), respectively. Sequence analysis demonstrated that MhSERK1 and MhdSERK1 display high similarity to SERKs in other species, with a conserved intron/exon structure that is unique to members of the SERK family. Additionally, the phylogenetic tree showed that MhSERK1 and MhdSERK1 clustered with orange CitSERK (93%). Furthermore, MhSERK1 and MhdSERK1 were mainly expressed in the reproductive organs, in particular the ovary. Their expression levels were highest in young flowers and they differed among different tissues and organs. Our results suggest that MhSERK1 and MhdSERK1 are related to plant reproduction, and that MhSERK1 is related to apomixis in triploid Pingyi Tiancha.
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Flores/genética , Malus/genética , Filogenia , Secuencia de Aminoácidos/genética , Proteínas de Arabidopsis/genética , Clonación Molecular , Flores/crecimiento & desarrollo , Regulación de la Expresión Génica de las Plantas , Malus/crecimiento & desarrollo , Proteínas de Plantas/biosíntesis , Proteínas de Plantas/genética , Proteínas Quinasas/genética , Alineación de Secuencia , Tetraploidía , TriploidíaRESUMEN
Three methods of triploidy (3N) induction were tested in diploid (2N) oysters Crassostrea gigas: two chemical methods cytochalasin-B (CB) and 6-dimethylaminopurine (6-DMAP), and one physical method with temperature shock. The objective was to evaluate the triploidy induction technology using flow cytometry as a tool to check the results of induction. The experiments were performed in separate and a seawater temperature in the tanks was maintained at 25 C for all experiments. In the experiment I, the efficacy of triploidy induction was evaluated using CB (0.5 mg L-1) and 6-DMAP (390 mols L-1). In the experiment II, the efficiency of triploidy induction was tested using CB (0.5 mg L-1) and 6-DMAP (450 mols L-1). In the experiment III, the efficiency of triploidy induction was evaluated using CB (0.5 mg L-1) and temperature shock (25 to 36 C). In all three experiments, viable triploid larvae were obtained. However, in the experiments I and II (with chemical methods), high mortality of larvae was observed, especially for the treatment CB. From these results, it is suggested the replacement of CB by other methods of triploidy induction, due to its high cost and high toxicity to humans and to the environment.(AU)
Três métodos de indução à triploidia (3N) foram testados em ostras diplóides (2N) (Crassostrea gigas); dois métodos químicos, citocalasina-B (CB) e 6-dimetilaminopurina (6-DMAP), e um método físico, com choque de temperatura. O objetivo foi avaliar a tecnologia de indução à triploidia, utilizando a técnica de citometria de fluxo como ferramenta para verificação dos resultados de indução. Os experimentos foram realizados em separado, sendo que a temperatura da água do mar foi mantida em 25 C em todos os tanques. No experimento I, foi avaliada a eficácia da indução à triploidia com CB (0,5 mg L-1) e 6-DMAP (390 mols L-1). No experimento II, foi testada a eficiência da indução à triploidia com CB (0,5 mg L-1) e 6-DMAP (450 mols L-1). No experimento III, foi avaliada a eficiência da indução à triploidia com CB (0,5 mg L-1) e choque de temperatura (25-36 C). Nos três experimentos, foram obtidas larvas triplóides viáveis. Entretanto, nos experimentos I e II (com métodos químicos), observou-se elevada mortalidade das larvas, especialmente para o tratamento CB. A partir destes resultados, a substituição de CB por outros métodos de indução à triploidia é sugerida, devido ao seu elevado custo e elevada toxicidade para os seres humanos e para o meio ambiente.(AU)
Asunto(s)
Animales , Crassostrea/anatomía & histología , Crassostrea/efectos de los fármacos , Adenina/administración & dosificación , Citocalasina B/administración & dosificación , TriploidíaRESUMEN
Three methods of triploidy (3N) induction were tested in diploid (2N) oysters Crassostrea gigas: two chemical methods cytochalasin-B (CB) and 6-dimethylaminopurine (6-DMAP), and one physical method with temperature shock. The objective was to evaluate the triploidy induction technology using flow cytometry as a tool to check the results of induction. The experiments were performed in separate and a seawater temperature in the tanks was maintained at 25 C for all experiments. In the experiment I, the efficacy of triploidy induction was evaluated using CB (0.5 mg L-1) and 6-DMAP (390 mols L-1). In the experiment II, the efficiency of triploidy induction was tested using CB (0.5 mg L-1) and 6-DMAP (450 mols L-1). In the experiment III, the efficiency of triploidy induction was evaluated using CB (0.5 mg L-1) and temperature shock (25 to 36 C). In all three experiments, viable triploid larvae were obtained. However, in the experiments I and II (with chemical methods), high mortality of larvae was observed, especially for the treatment CB. From these results, it is suggested the replacement of CB by other methods of triploidy induction, due to its high cost and high toxicity to humans and to the environment.
Três métodos de indução à triploidia (3N) foram testados em ostras diplóides (2N) (Crassostrea gigas); dois métodos químicos, citocalasina-B (CB) e 6-dimetilaminopurina (6-DMAP), e um método físico, com choque de temperatura. O objetivo foi avaliar a tecnologia de indução à triploidia, utilizando a técnica de citometria de fluxo como ferramenta para verificação dos resultados de indução. Os experimentos foram realizados em separado, sendo que a temperatura da água do mar foi mantida em 25 C em todos os tanques. No experimento I, foi avaliada a eficácia da indução à triploidia com CB (0,5 mg L-1) e 6-DMAP (390 mols L-1). No experimento II, foi testada a eficiência da indução à triploidia com CB (0,5 mg L-1) e 6-DMAP (450 mols L-1). No experimento III, foi avaliada a eficiência da indução à triploidia com CB (0,5 mg L-1) e choque de temperatura (25-36 C). Nos três experimentos, foram obtidas larvas triplóides viáveis. Entretanto, nos experimentos I e II (com métodos químicos), observou-se elevada mortalidade das larvas, especialmente para o tratamento CB. A partir destes resultados, a substituição de CB por outros métodos de indução à triploidia é sugerida, devido ao seu elevado custo e elevada toxicidade para os seres humanos e para o meio ambiente.
Asunto(s)
Animales , Adenina/administración & dosificación , Citocalasina B/administración & dosificación , Crassostrea/anatomía & histología , Crassostrea/efectos de los fármacos , TriploidíaRESUMEN
In this study, genetic differentiation between karyomorphs A (2n = 42) and D (2n = 39/40) of the wolf fish Hoplias malabaricus, which is comprised of several cryptic species that present a wide variety of diploid chromosome numbers and sex chromosome systems, resulting in the identification of seven distinct karyomorphs (A-G), was investigated using a combination of molecular and cytogenetic tools. Deep sequence divergences for both karyomorphs were observed and indicate a long period of reproductive isolation between karyomorphs A and D. Additionally, one individual with 61 chromosomes was identified, which, as far as is known, is the first case of natural triploidy resulting from the hybridization between these highly differentiated karyomorphs of H. malabaricus. Molecular and cytogenetic analyses revealed that this allotriploid specimen carries two sets of maternal chromosomes from karyomorph D (2n = 40) and one set of chromosomes from karyomorph A (n = 21). Moreover, ribosomal sites and active nucleolus organizer regions from both parental contributors were found in the triploid hybrid. Considering the significant genetic distances between karyomorphs A and D, one of the primary reasons for the lack of recurrent reports of hybridization in the H. malabaricus species complex may be due to post-zygotic barriers, such as hybrid sterility or unviability.
Asunto(s)
Characiformes/genética , Hibridación Genética , Triploidía , Animales , Brasil , Cromosomas/genética , Cariotipo , Fenotipo , RíosRESUMEN
Carassius auratus var. pingxiangnensis is a natural triploid crucian carp mutant. In order to understand its placement and genetic background at the gene level, the characteristics of mitochondrial DNA sequences and phylogenetic relationship were examined. The results showed that the mitochondrial DNA is a circular double-stranded DNA molecule that is 16,576 bp in length with 13 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes, and a non-coding control region. Mitochondrial genes overlapped by a total of 40 bp in 11 different locations from 1 to 14 bp. The base composition of the C. auratus mitogenome was estimated to be 29.70% A, 26.74% C, 15.35% G, and 28.21% T. The central conserved blocks and the conserved blocks were compared and were similar among C. auratus var. pingxiangnensis and six other cyprinids with different ploidies. The origin of light strand replication was similar to that of other vertebrates; it was 33 bp, but the characteristic sequence motif 5ê-GCCGG-3ê at the base of the stem within tRNA(Cys) was mutated to 5ê-GGCGG- 3ê. Our phylogenetic analysis based on whole mitogenome sequences indicated that C. auratus var. pingxiangnensis was clustered with C. auratus and then sister-grouped with Carassius gibelio. The systemic developmental tree of crucian carp with different chromosome ploidies showed that diploid C. auratus auratus was clustered with triploid C. auratus auratus, sister-grouped with tetraploid C. auratus auratus, and clustered with other diploid, triploid, and tetraploid C. auratus.
Asunto(s)
Carpas/clasificación , Carpas/genética , Genoma Mitocondrial , Carpa Dorada/genética , Filogenia , Triploidía , Animales , Composición de Base , Secuencia de Bases , Codón , Orden Génico , Genes Mitocondriales , Genes de ARNr , Datos de Secuencia Molecular , Sistemas de Lectura Abierta , Ploidias , Poliploidía , ARN de Transferencia , Regiones no TraducidasRESUMEN
Cassava periclinal cytochimeras, cultivars, and interspecific hybrid and polyploid types were studied in relation to embryonic, cytogenetic, and anatomical behavior. Their apical shoots, pollen grains, male and female buds, roots, stomata, and flowering period were analyzed. Chimeras exhibited increased size of L1 and L2 cells. Polyploidy led to enlargement of stomata in chimeras whereas L2 gave tetraploid chromosome configurations, tetrad irregularity, decrease of pollen viability, and increase in frequency of polyembryo sacs. The chimeric composition of tetraploids L1 and L2 and diploid L3 expressed a notable epigenetic effect seen in a marked enlargement of edible roots compared to total diploid. One of the chimeric types was accompanied by complete flowering inhibition. Pollen viability and diameter appeared to be reliable markers to determine ploidy levels.
Asunto(s)
Quimera , Manihot/anatomía & histología , Manihot/genética , Poliploidía , Cromosomas de las Plantas , Análisis Citogenético , Diploidia , Manihot/embriología , Raíces de Plantas/anatomía & histología , Raíces de Plantas/genética , Raíces de Plantas/crecimiento & desarrollo , Brotes de la Planta/anatomía & histología , Estomas de Plantas/genética , Polen/genética , TriploidíaRESUMEN
BACKGROUND: Natural polyploidy has played an important role during the speciation and evolution of vertebrates, including anurans, with more than 55 described cases. The species of the Phyllomedusa burmeisteri group are mostly characterized by having 26 chromosomes, but a karyotype with 52 chromosomes was described in P. tetraploidea. This species was found in sintopy with P. distincta in two localities of São Paulo State (Brazil), where triploid animals also occur, as consequence of natural hybridisation. We analyse the chromosomes of P. distincta, P. tetraploidea, and their triploid hybrids, to enlighten the origin of polyploidy and to obtain some evidence on diploidisation of tetraploid karyotype. RESULTS: Phyllomedusa distincta was 2n = 2x = 26, whereas P. tetraploidea was 2n = 4x = 52, and the hybrid individuals was 2n = 3x = 39. In meiotic phases, bivalents were observed in the diploid males, whereas both bivalents and tetravalents were observed in the tetraploid males. Univalents, bivalents or trivalents; metaphase II cells carrying variable number of chromosomes; and spermatids were detected in the testis preparations of the triploid males, indicating that the triploids were not completely sterile. In natural and experimental conditions, the triploids cross with the parental species, producing abnormal egg clutches and tadpoles with malformations. The embryos and tadpoles exhibited intraindividual karyotype variability and all of the metaphases contained abnormal constitutions. Multiple NORs, detected by Ag-impregnation and FISH with an rDNA probe, were observed on chromosome 1 in the three karyotypic forms; and, additionally, on chromosome 9 in the diploids, mostly on chromosome 8 in the tetraploids, and on both chromosome 8 and 9 in the triploids. Nevertheless, NOR-bearing chromosome 9 was detected in the tetraploids, and chromosome 9 carried active or inactive NORs in the triploids. C-banding, base-specific fluorochrome stainings with CMA3 and DAPI, FISH with a telomeric probe, and BrdU incorporation in DNA showed nearly equivalent patterns in the karyotypes of P. distincta, P. tetraploidea, and the triploid hybrids. CONCLUSIONS: All the used cytogenetic techniques have provided strong evidence that the process of diploidisation, an essential step for stabilising the selective advantages produced by polyploidisation, is under way in distinct quartets of the tetraploid karyotype.
Asunto(s)
Anuros/genética , Cromosomas/genética , Animales , Cromosomas/metabolismo , Análisis Citogenético , Diploidia , Femenino , Hibridación Genética , Hibridación Fluorescente in Situ , Cariotipificación , Masculino , Metafase/genética , Tetraploidía , TriploidíaRESUMEN
Haageocereus tenuis is a prostrate cactus restricted to a small area of 2 km(2) near the city of Lima, Peru. The species is triploid and propagates mainly through stem fragmentation. In addition, propagation via agamospermy is documented and adventitious embryony is also inferred as a mechanism. Although seedling recruitment has not been observed in nature, we have shown that asexually produced seeds are viable. About 45 adult individuals, plus 9 individuals obtained from seeds, were sampled and 5 microsatellite markers were used to assess genetic variability. Microsatellite analysis confirms that individuals from the only existing population are genetically identical and that the population likely represents a single clone. The absence of mutations in any individual, even in highly variable microsatellite loci, may indicate that the species is also of recent origin. Other prostrate species of Haageocereus are suspected to be occasional apomicts. This phenomenon has significant implications for the evolutionary biology and ecology of Haageocereus and other clonal Cactaceae.