Inheritance Of DNA Research Articles

Himantoglossum adriaticum H. Baumann × Himantoglossum robertianum (Loisel.) P. Delforge: A New Interspecific Hybrid Assessed by Barcoding Analysis.

Most cultivated orchids, contributing to a worldwide highly profitable industry, are originated from tropic regions. Conversely, a considerable number of spontaneous orchids, belonging to the terrestrial orchids and widely diffused throughout the European continent, are not considered for trading due to their less gorgeous appearance and for technical difficulties in seed propagation. However, a breeding programme was undertaken aimed at developing a new hybrid between Himantoglossum adriaticum H. Baumann and H. robertianum (Loisel.) P. Delforge [syn. Barlia robertiana (Loisel.) Greuter] by applying techniques of anther conservation, manual pollination and in vitro asymbiotic germination of the obtained seeds. The plantlets that originated from the protocorms after seed germination were successfully acclimatised after potting in a proper medium. The parentage of the progenies of the hybridisation experiment was assessed by sequencing the Internal Transcribed Spacer assembly (ITS) and plastid barcoding markers of the parental lines and of the hybrids. The method proved to be effective in revealing the origin of the hybrids and to validate the maternal inheritance of the plastid DNA.

Mitoptosis, Twenty Years After.

In 1999 V. P. Skulachev proposed the term "mitoptosis" to refer to the programmed elimination of mitochondria in living cells. According to the initial thought, mitoptosis serves to protect cells from malfunctioning of the damaged mitochondria. At the same time, a new mechanism of the complete mitochondria elimination was found under the conditions of massive mitochondrial damage associated with oxidative stress. In this experimental model, mitochondrial cluster formation in the perinuclear region leads to the formation of "mitoptotic body" surrounded by a single-layer membrane and subsequent release of mitochondria from the cell. Later, it was found that mitoptosis plays an important role in various normal and pathological processes that are not necessarily associated with the mitochondrial damage. It was found that mitoptosis takes place during cell differentiation, self-maintenance of hematopoietic stem cells, metabolic remodelling, and elimination of the paternal mitochondria in organisms with the maternal inheritance of the mitochondrial DNA. Moreover, the associated with mitoptosis release of mitochondrial components into the blood may be involved in the transmission of signals between cells, but also leads to the development of inflammatory and autoimmune diseases. Mitoptosis can be attributed to the asymmetric inheritance of mitochondria in the division of yeast and some animal cells, when the defective mitochondria are transferred to one of the newly formed cells. Finally, a specific form of mitoptosis appears to be selective elimination of mitochondria with deleterious mutations in whole follicular ovarian cells in mammals. During formation of the primary follicle, the mitochondrial DNA copy number is significantly reduced. After division, the cells that receive predominantly mitochondria with deleterious mutations in their mtDNA die, thereby reducing the likelihood of transmission of these mutations to offspring. Further study of the mechanisms of mitoptosis in normal and pathological conditions is important both for understanding the processes of development and aging, and for designing therapeutic approaches for inflammatory, neurodegenerative and other diseases.

Cdk1 Phosphorylation of the Dam1 Complex Strengthens Kinetochore-Microtubule Attachments

To ensure the faithful inheritance of DNA, a macromolecular protein complex called the kinetochore sustains the connection between chromosomes and force-generating dynamic microtubules during cell division. Defects in this process lead to aneuploidy, a common feature of cancer cells and the cause of many developmental diseases [1, 2, 3, 4]. One of the major microtubule-binding activities in the kinetochore is mediated by the conserved Ndc80 complex (Ndc80c) [5, 6, 7]. In budding yeast, the retention of kinetochores on dynamic microtubule tips also depends on the essential heterodecameric Dam1 complex (Dam1c) [8, 9, 10, 11, 12, 13, 14, 15], which binds to the Ndc80c and is proposed to be a functional ortholog of the metazoan Ska complex [16, 17]. The load-bearing activity of the Dam1c depends on its ability to oligomerize, and the purified complex spontaneously self-assembles into microtubule-encircling oligomeric rings, which are proposed to function as collars that allow kinetochores to processively track the plus-end tips of microtubules and harness the forces generated by disassembling microtubules [10, 11, 12, 13, 14, 15, 18, 19, 20, 21, 22]. However, it is unknown whether there are specific regulatory events that promote Dam1c oligomerization to ensure accurate segregation. Here, we used a reconstitution system to discover that Cdk1, the major mitotic kinase that drives the cell cycle, phosphorylates the Ask1 component of the Dam1c to increase its residence time on microtubules and enhance kinetochore-microtubule attachment strength. We propose that Cdk1 activity promotes Dam1c oligomerization to ensure that kinetochore-microtubule attachments are stabilized as kinetochores come under tension in mitosis.

Interspecific hybridization in North American Polygala (Polygalaceae)

As a part of ongoing systematic and phylogenetic studies in Polygalaceae, field collections of two pairs of North American species (Polygala balduinii and P. ramosa, and P. lutea and P. rugelii) had morphologically intermediate forms and grew sympatrically, and so were suspected to be interspecific hybrids. Although hybrids among plants are often invoked in taxonomic and floristic literature based on morphologic intermediacy, they are rarely documented and substantiated using molecular tools. We found that the morphologically intermediate individuals within intermixed populations of both species pairs did indeed share all of the variable nucleotide sites in nrITS among the parent species. Likewise, using plastid sequence data (trnL-F), we determined that in both species pairs, the parentage was bidirectional. Although some DNA inheritance phenomena (e.g. incomplete lineage sorting) can result in similar polymorphic DNA sequence data, the intermediacy in both morphology and sequence data within sympatric populations is more indicative of interspecific hybridization.

Semimytilus algosus: first known hermaphroditic mussel with doubly uniparental inheritance of mitochondrial DNA

Doubly uniparental inheritance (DUI) of mitochondrial DNA is a rare phenomenon occurring in some freshwater and marine bivalves and is usually characterized by the mitochondrial heteroplasmy of male individuals. Previous research on freshwater Unionida mussels showed that hermaphroditic species do not have DUI even if their closest gonochoristic counterparts do. No records showing DUI in a hermaphrodite have ever been reported. Here we show for the first time that the hermaphroditic mussel Semimytilus algosus (Mytilida), very likely has DUI, based on the complete sequences of both mitochondrial DNAs and the distribution of mtDNA types between male and female gonads. The two mitogenomes show considerable divergence (34.7%). The presumably paternal M type mitogenome dominated the male gonads of most studied mussels, while remaining at very low or undetectable levels in the female gonads of the same individuals. If indeed DUI can function in the context of simultaneous hermaphroditism, a change of paradigm regarding its involvement in sex determination is needed. It is apparently associated with gonadal differentiation rather than with sex determination in bivalves.

Breeding and fruiting evaluation of new strains by the interspecific mating of the high commercial potential mushroom Pleurotus tuoliensis with its closely related P. eryngii

Pleurotus tuoliensis (Bailinggu) is a precious mushroom species cultivated industrially in eastern Asia. The long cropping cycle, high deformity rate, and low yield are the major bottlenecks for its widespread cultivation. There is thus a need for improved P. tuoliensis cultivars. In the present study, interspecific crossing of monokaryons between P. tuoliensis and P. eryngii was carried out. Six out of nine pairings were observed to result in clamp connections. Dikaryotized regions within a mating Petri dish varied considerably with the compatible pairings. A total of nine hybrids were isolated within the junction zone and on the periphery at either sides of the paired colonies from three selected crosses. The internal transcribed spacer (ITS) restriction fragment length polymorphism (ITS-RFLP) profiles, together with ITS sequencing revealed significant genetic differences between the nine selected hybrids with parental strains. The polymerase chain reaction (PCR) amplification revealed that the inheritance of mitochondrial DNA was uniparental between these two species. Of nine crossbred strains, six were selected for fruiting test. Compared with their parental P. tuoliensis strains, all the six tested hybrids fruited faster, and three hybrids showed improved biological efficiency compared to their parents, either P. tuoliensis or P. eryngii. Two hybrids (Ht-26 and He-26) formed a white-colored fruit body, with improved biological efficiency (62.5 %–64.2 %) compared to parents P. tuoliensis (41.8 %) and P. eryngii (52.1 %), and thus hold great potential as new cultivars for the commercial production of P. tuoliensis.

Rolling-Circle Replication in Mitochondrial DNA Inheritance: Scientific Evidence and Significance from Yeast to Human Cells.

Studies of mitochondrial (mt)DNA replication, which forms the basis of mitochondrial inheritance, have demonstrated that a rolling-circle replication mode exists in yeasts and human cells. In yeast, rolling-circle mtDNA replication mediated by homologous recombination is the predominant pathway for replication of wild-type mtDNA. In human cells, reactive oxygen species (ROS) induce rolling-circle replication to produce concatemers, linear tandem multimers linked by head-to-tail unit-sized mtDNA that promote restoration of homoplasmy from heteroplasmy. The event occurs ahead of mtDNA replication mechanisms observed in mammalian cells, especially under higher ROS load, as newly synthesized mtDNA is concatemeric in hydrogen peroxide-treated human cells. Rolling-circle replication holds promise for treatment of mtDNA heteroplasmy-attributed diseases, which are regarded as incurable. This review highlights the potential therapeutic value of rolling-circle mtDNA replication.

Doubly uniparental inheritance of mitochondrial DNA in freshwater mussels: History and status of the European species

Doubly uniparental inheritance of mitochondrial DNA in freshwater mussels: History and status of the European species

Replication Stress Induces ATR/CHK1-Dependent Nonrandom Segregation of Damaged Chromosomes

Nonrandom DNA segregation (NDS) is a mitotic event in which sister chromatids carrying the oldest DNA strands are inherited exclusively by one of the two daughter cells. Although this phenomenon has been observed across various organisms, the mechanism and physiological relevance of this event remain poorly defined. Here, we demonstrate that DNA replication stress can trigger NDS in human cells. This biased inheritance of old template DNA is associated with the asymmetric DNA damage response (DDR), which derives at least in part from telomeric DNA. Mechanistically, we reveal that the ATR/CHK1 signaling pathway plays an essential role in mediating NDS. We show that this biased segregation process leads to cell-cycle arrest and cell death in damaged daughter cells inheriting newly replicated DNA. These data therefore identify a key role for NDS in the maintenance of genomic integrity within cancer cell populations undergoing replication stress due to oncogene activation.

A review on cybrids : An approach for plant improvement

Somatic hybridization is a mechanism for gene transfer from related species to cultivated crops, especially when wide hybridization is not applicable. Protoplast fusion resulting in the development of cybrids is known as cybridization. Interaction of plastome and genome contributes to the formation of cybrids (cytoplasmic hybrids). Cybridization has been successfully used to transfer CMS in rice and maize. It is very promising allows partial genome transfer better tolerated than whole-genome transfer. It enables transfer of genetic materials between distantly-related and sexually-incompatible species with great potential for improvement of crops. It demands less common skills and expertise, but ranks as a method yielded good results. But introgression and stable inheritance of the alien DNA carrying the desired genes have to take place. Moreover, an important factor to investigate in the future is the mechanism involved in the incorporation of donor DNA into recipient chromosomes.

Plasticity of Mitochondrial DNA Inheritance and its Impact on Nuclear Gene Transcription in Yeast Hybrids.

Mitochondrial DNA (mtDNA) in yeast is biparentally inherited, but colonies rapidly lose one type of parental mtDNA, thus becoming homoplasmic. Therefore, hybrids between the yeast species possess two homologous nuclear genomes, but only one type of mitochondrial DNA. We hypothesise that the choice of mtDNA retention is influenced by its contribution to hybrid fitness in different environments, and the allelic expression of the two nuclear sub-genomes is affected by the presence of different mtDNAs in hybrids. Saccharomyces cerevisiae/S. uvarum hybrids preferentially retained S. uvarum mtDNA when formed on rich media at colder temperatures, while S. cerevisiae mtDNA was primarily retained on non-fermentable carbon source, at any temperature. Transcriptome data for hybrids harbouring different mtDNA showed a strong environmentally dependent allele preference, which was more important in respiratory conditions. Co-expression analysis for specific biological functions revealed a clear pattern of concerted allelic transcription within the same allele type, which supports the notion that the hybrid cell works preferentially with one set of parental alleles (or the other) for different cellular functions. Given that the type of mtDNA retained in hybrids affects both nuclear expression and fitness, it might play a role in driving hybrid genome evolution in terms of gene retention and loss.

Inheritance of mitochondrial DNA in humans: implications for rare and common diseases.

The first draft human mitochondrial DNA (mtDNA) sequence was published in 1981, paving the way for two decades of discovery linking mtDNA variation with human disease. Severe pathogenic mutations cause sporadic and inherited rare disorders that often involve the nervous system. However, some mutations cause mild organ‐specific phenotypes that have a reduced clinical penetrance, and polymorphic variation of mtDNA is associated with an altered risk of developing several late‐onset common human diseases including Parkinson’s disease. mtDNA mutations also accumulate during human life and are enriched in affected organs in a number of age‐related diseases. Thus, mtDNA contributes to a wide range of human pathologies. For many decades, it has generally been accepted that mtDNA is inherited exclusively down the maternal line in humans. Although recent evidence has challenged this dogma, whole‐genome sequencing has identified nuclear‐encoded mitochondrial sequences (NUMTs) that can give the false impression of paternally inherited mtDNA. This provides a more likely explanation for recent reports of ‘bi‐parental inheritance’, where the paternal alleles are actually transmitted through the nuclear genome. The presence of both mutated and wild‐type variant alleles within the same individual (heteroplasmy) and rapid shifts in allele frequency can lead to offspring with variable severity of disease. In addition, there is emerging evidence that selection can act for and against specific mtDNA variants within the developing germ line, and possibly within developing tissues. Thus, understanding how mtDNA is inherited has far‐reaching implications across medicine. There is emerging evidence that this highly dynamic system is amenable to therapeutic manipulation, raising the possibility that we can harness new understanding to prevent and treat rare and common human diseases where mtDNA mutations play a key role.

Hox genes reveal variations in the genomic DNA of allotetraploid hybrids derived from Carassius auratus red var. (female) \xd7 Cyprinus carpio L. (male)

BackgroundHox transcription factors are master regulators of animal development. Although highly conserved, they can contribute to the formation of novel biological characteristics when modified, such as during the generation of hybrid species, thus potentially serving as species-specific molecular markers. Here, we systematically studied the evolution of genomic sequences of Hox loci in an artificial allotetraploid lineage (4nAT, 4n = 200) derived from a red crucian carp (♀, RCC, 2n = 100) × common carp (♂, CC, 2n = 100) cross and its parents (RCC and CC).ResultsPCR amplification yielded 23 distinct Hox gene fragments from 160 clones in 4nAT, 22 fragments from 90 clones in RCC, and 19 fragments from 90 clones in CC. Sequence alignment of the HoxA3a and HoxC10a genes indicated both the inheritance and loss of paternal genomic DNA in 4nAT. The HoxA5a gene from 4nAT consisted of two subtypes from RCC and two subtypes from CC, indicating that homologous recombination occurred in the 4nAT hybrid genome. Moreover, 4nAT carried genomic pseudogenization in the HoxA10b and HoxC13a loci. Interestingly, a new type of HoxC9a gene was found in 4nAT as a hybrid sequence of CC and RCC by recombination in the intronic region.ConclusionThe results revealed the influence of Hox genes during polyploidization in hybrid fish. The data provided insight into the evolution of vertebrate genomes and might be benefit for artificial breeding programs.

Shaping the mitochondrial inner membrane in health and disease.

Mitochondria play central roles in cellular energetics, metabolism and signalling. Efficient respiration, mitochondrial quality control, apoptosis and inheritance of mitochondrial DNA depend on the proper architecture of the mitochondrial membranes and a dynamic remodelling of inner membrane cristae. Defects in mitochondrial architecture can result in severe human diseases affecting predominantly the nervous system and the heart. Inner membrane morphology is generated and maintained in particular by the mitochondrial contact site and cristae organizing system (MICOS), the F1 Fo -ATP synthase, the fusion protein OPA1/Mgm1 and the nonbilayer-forming phospholipids cardiolipin and phosphatidylethanolamine. These protein complexes and phospholipids are embedded in a network of functional interactions. They communicate with each other and additional factors, enabling them to balance different aspects of cristae biogenesis and to dynamically remodel the inner mitochondrial membrane. Genetic alterations disturbing these membrane-shaping factors can lead to human pathologies including fatal encephalopathy, dominant optic atrophy, Leigh syndrome, Parkinson's disease and Barth syndrome.

Paternal leakage of mitochondrial DNA and maternal inheritance of heteroplasmy in Drosophila hybrids

Mitochondrial DNA (mtDNA) is maternally transmitted in animals and therefore, individuals are expected to have a single mtDNA haplotype (homoplasmy). Yet, heteroplasmic individuals have been observed in a large number of animal species. Heteroplasmy may emerge as a result of somatic mtDNA mutations, paternal leakage during fertilization or be inherited from a heteroplasmic mother. Understanding the causes of heteroplasmy could shed light into the evolution of mtDNA inheritance. In this study we examined heteroplasmy in progeny from heterospecific crosses of Drosophila for two consecutive generations. We studied the generation of heteroplasmy from paternal leakage and the maternal transmission of heteroplasmy. Our data reveal non-random patterns in the emergence and transmission of heteroplasmy and suggest that heteroplasmy depends on the family of origin.

Character expression, reproductive barriers, and origin of the rare fern hybrid Asplenium ×aran-tohanum (Aspleniaceae)

Hybridization is a ubiquitous force in plant evolution. In ferns, hybrids are often easily recognized by their intermediate morphology and abortive spores and thus provide a good model for studying reproductive isolating barriers between species. Asplenium ×aran-tohanum is a rare fern hybrid, despite wide coexistence of its parental species (A. billotii and A. trichomanes subsp. quadrivalens) in Western Europe. We made a complete characterization of its three known individuals, including macro- and micromorphology, sporogenesis, gametophyte reproduction, and chloroplast DNA inheritance and evolution. The hybrid expressed morphological characters that were mostly intermediate between those of the parents, but some characters were more similar to one parent or the other. Sizes of both guard cells and spores indicate that the hybrid is tetraploid, as are both parents, and one parent (A. billotii) consistently acted as the female. A very small fraction of spores (~ 7%) were viable and the resulting gametophytes could not form sporophytes, either sexually or apogamously, suggesting that effective postzygotic barriers exist between the parents. The lineages of these taxa diverged about 35 million years ago, which may explain the strong reproductive isolation and rarity of the hybrid. Asplenium ×aran-tohanum appears to be an evolutionary dead end, probably formed recurrently at the places where it grows, but incapable of completing its life cycle or producing viable offspring.

Mitochondrial DNA Variation and Selfish Propagation Following Experimental Bottlenecking in Two Distantly Related Caenorhabditis briggsae Isolates.

Understanding mitochondrial DNA (mtDNA) evolution and inheritance has broad implications for animal speciation and human disease models. However, few natural models exist that can simultaneously represent mtDNA transmission bias, mutation, and copy number variation. Certain isolates of the nematode Caenorhabditis briggsae harbor large, naturally-occurring mtDNA deletions of several hundred basepairs affecting the NADH dehydrogenase subunit 5 (nduo-5) gene that can be functionally detrimental. These deletion variants can behave as selfish DNA elements under genetic drift conditions, but whether all of these large deletion variants are transmitted in the same preferential manner remains unclear. In addition, the degree to which transgenerational mtDNA evolution profiles are shared between isolates that differ in their propensity to accumulate the nduo-5 deletion is also unclear. We address these knowledge gaps by experimentally bottlenecking two isolates of C. briggsae with different nduo-5 deletion frequencies for up to 50 generations and performing total DNA sequencing to identify mtDNA variation. We observed multiple mutation profile differences and similarities between C. briggsae isolates, a potentially species-specific pattern of copy number dysregulation, and some evidence for genetic hitchhiking in the deletion-bearing isolate. Our results further support C. briggsae as a practical model for characterizing naturally-occurring mtgenome variation and contribute to the understanding of how mtgenome variation persists in animal populations and how it presents in mitochondrial disease states.

Doubly uniparental inheritance of mitochondrial DNA: Might it be simpler than we thought?

Doubly uniparental inheritance of mitochondrial DNA: Might it be simpler than we thought?

What nature separated, and human joined together: About a spontaneous hybridization between two allopatric dogwood species (Cornus controversa and C. alternifolia).

In this study, possible hybridization between two allopatric species, Cornus controversa and Cornus alternifolia, was explored using molecular and morphological approaches. Scanning electron microscope analyses of the adaxial and the abaxial leaf surfaces yielded a few new not yet described characters typical for the particular species and intermediate for hybrids. With the use of 14 Random Amplified Polymorphic DNA and 5 Amplified Fragment Length Polymorphism primer combinations, 44 fragments species specific to C. controversa and 51 species specific to C. alternifolia were obtained. Most of these bands were also found in putative hybrids. All clustering analyses based on binary data combined from both methods confirmed a separate and intermediate status of the hybrids. Hybrid index estimates for hybrids C1-C5 indicated that all were the first generation of offspring (F1). Chloroplast intergenic spacers (trnF-trnL and psbC-trnS) were used to infer the hybridization direction. Based on the assumption of maternal inheritance of chloroplast DNA, C. controversa seems to be the maternal parent of the hybrid. Internal transcribed spacer sequences of the five hybrids analyzed here indicated higher similarity with the sequences of C. controversa (all shared the majority of its single nucleotide polymorphisms). Sequence analysis of PI-like genes fully confirmed the hybrid origin of C1-C5 hybrids. Our results also showed that two specimens in the C. alternifolia group, A1 and A3, are not free of introgression. They are probably repeated backcrosses toward C. alternifolia. Furthermore, molecular data seem to point not only to unidirectional introgression toward C. controversa (the presence of hybrids) but to bidirectional introgression as well, since the presence of markers specific for C. controversa in the profiles of C. alternifolia specimen A3 was observed.

Intra-individual heteroplasmy in the Gentiana tongolensis plastid genome (Gentianaceae).

Chloroplasts are typically inherited from the female parent and are haploid in most angiosperms, but rare intra-individual heteroplasmy in plastid genomes has been reported in plants. Here, we report an example of plastome heteroplasmy and its characteristics in Gentiana tongolensis (Gentianaceae). The plastid genome of G. tongolensis is 145,757 bp in size and is missing parts of petD gene when compared with other Gentiana species. A total of 112 single nucleotide polymorphisms (SNPs) and 31 indels with frequencies of more than 2% were detected in the plastid genome, and most were located in protein coding regions. Most sites with SNP frequencies of more than 10% were located in six genes in the LSC region. After verification via cloning and Sanger sequencing at three loci, heteroplasmy was identified in different individuals. The cause of heteroplasmy at the nucleotide level in plastome of G. tongolensis is unclear from the present data, although biparental plastid inheritance and transfer of plastid DNA seem to be most likely. This study implies that botanists should reconsider the heredity and evolution of chloroplasts and be cautious with using chloroplasts as genetic markers, especially in Gentiana.