Academic literature on the topic '4-DNP derivative'

Abstract Over the past several years, the development of high yielding, rapid methods for synthesizing DNA (1-3) have led to a large number of applications for oligonucleotides (4). These include its use for cloning and synthesizing genes (5), as primers for sequencing DNA and various PCR applications (6), mutagenesis of genes in a site-specific manner (7), examination of how nucleic acids interact with proteins (8), and for studies on nucleic acid structure (9). Mainly because of these results, many have discovered that synthetic DNA needs to be further modified so that it resists hydrolysis by nucleases and contains reporter groups, haptens, cross-linking reagents, sugars, steroids, and peptides. Invariably such interest has stimulated the development of new analogues and new chemistries for synthesizing these derivatives. In this chapter, the chemical synthesis of a potentially very useful analogue for many of these applications, which we call dithioate DNA, will be discussed.

Chapter 4, “Neutral theories of molecular evolution,” outlines the logic and predictions of the neutral theory of molecular evolution and its derivatives as a simple conceptual framework for understanding DNA sequence evolution. It introduces the standard neutral model as a null model of evolutionary change in DNA sequences to describe patterns of polymorphism within species and divergence between species. An overview is provided for the molecular clock concept and for predictions about the amount of polymorphism and allele frequency distributions within populations. This chapter covers how population size and selection intersect to define nearly neutral fitness effects and their implications, as well as misinterpretations and misapplications of Neutral Theory. This overview provides a foundation for how theoretical predictions offer null models for tests of molecular evolution developed in later chapters.

Abstract Experimental approaches to understanding chromosome structure and function fall into two main categories: the first involves assembling candidate DNA elements in vitro to construct an artificial chromosome. This approach was used to create yeast artificial chromosomes in both Saccharomyces cerevisiae and Schizosaccharomyces pombe. More recently a related approach has lead to the generation of mammalian minichromosomes in the human somatic cell line HT1080, although the precise DNA organization and requirements of these mammalian minichromosomes has yet to be fully elucidated (1). The alternative approach involves manipulation of an existing chromosome to generate smaller minichromosome derivatives suitable for further study/fragmentation. This chapter will focus on the use of short stretches of the vertebrate terminal repeat DNA sequence (TTAGGG)n to 'seed' the formation of de novo telomeres when introduced into vertebrate cell lines, simultaneously truncating the chromosome at the integration site (2, 3). Combined with elaborate selection schemes and homologous recombination this approach has led to the generation of a series of minichromosomes derived from native human chromosomes (4, 5).

Objetivo: Cromossomos em anel são moléculas circulares de DNA geradas após um dano com consequente reparo, sendo raramente descritos em neoplasias mieloides. O intuito deste trabalho foi avaliar o significado prognóstico dos cromossomos em anel em neoplasias mieloides e verificar sua correlação com alterações no gene TP53. Método: Estudo retrospectivo envolvendo amostras de medula óssea (n=21) de pacientes com neoplasias mieloides (≥18 anos) que tinham cariótipo com cromossomos em anel, entre 2017 e 2022, em laboratório de citogenética de rotina. Deleção e mutação no gene TP53 foram analisadas por técnica de FISH e NGS, respectivamente. Análises estatísticas com uso dos softwares IBM-SPSS/Microsoft-Excel de acordo com dados coletados em REDCap. Conclusão: Somente 0,29% dos cariótipos onco-hematológicos apresentaram cromossomos em anel. Mediana de idade de 69 anos (53–89), 14 (67%) homens, LMA e SMD em 9 (43%) casos cada. Mediana de anormalidades cariotípicas de 9 (1–28). Complexidade cariotípica, deleção TP53, mutação TP53 e TP53 multi-hit (definido por VAF>40% ou duas mutações com VAF>10% ou presença de deleção e mutação VAF>10%) estiveram presentes em 81% (17/21), 19% (4/21), 78% (14/18) e 61% (11/18) dos casos, respectivamente. Cromossomos em anel identificáveis derivativos dos cromossomos 6 e 7 foram os mais encontrados. A mediana de sobrevida global foi de 3,2 meses. Mutações multi-hit em TP53 (HR 10,63; IC95% 2,25–50,31; p=0,001) e o número de anormalidades ao cariótipo (HR 1,06; IC95% 1,00–1,11; p=0,043) se associaram significativamente a maiores taxas de mortalidade; pacientes com KT muito complexo (66,7%) apresentaram risco de óbito 5,53 vezes maior (IC95% 1,12–27,28) em relação a cariótipos não complexos. A incidência de cromossomos em anel foi baixa em neoplasias mieloides, associou-se à alta taxa de cariótipo complexo e mutações em TP53, fatores associados a prognóstico bastante reservado. Os cromossomos em anel parecem apenas refletir a instabilidade genética gerada pelo cariótipo complexo, não estando envolvidos de forma causal com as neoplasias mieloides.

1. Abstract: Over the past 25 years, vine cacti of the genera Hylocereus and Selenicereus have been introduced into Israel and southern California as new exotic fruit crops. The importance of these crops lies in their high water use efficiency and horticultural potential as exotic fruit crops. Our collaboration focused on the cytological, molecular and evolutionary aspects of vine cacti polyploidization to confront the agricultural challenge of genetic improvement, ultimately to improve success of vine cacti as commercial fruit crop plants. More specifically, we worked on the: 1- Identification of the putative ancestor(s) of the tetraploid H. megalanthus; 2- Determination of the number of origins of H. megalanthus (single vs. multiple origins of polyploidy); 3- Cytogenetic analysis of BC1 and F1 hybrids; 4- Determination of important agricultural traits and the selection of superior hybrids for cultivation. The plant material used in this study comprised interspecific Hylocereus F1 and first backcross (BC1) hybrids, nine Hylocereus species (58 genotypes), nine Selenicereus species (14 genotypes), and four Epiphyllum genotypes. Two BC1 hexaploids (BC-023 and BC-031) were obtained, a high ploidy level that can be explained only by a fertilization event between one unreduced female gamete from the triploid hybrid and a balanced gamete from the pollen donor, the diploid H. monacanthus. These findings are scientific evidence that support the possibility that “hybridization followed by chromosome doubling” could also occur in nature. Cytomixis, the migration of chromatin between adjacent cells through connecting cytoplasmatic channels, was observed in vine cacti hybrids and may thus imply selective DNA elimination in response to the allopolyploidization process. Evidence from plastid and nrDNA internal transcribed spacers (ITS) sequences support the placement of H. megalanthus within a monophyletic Hylocereus group. Furthermore, both plastid and ITS datasets are most consistent with a conclusion that this tetraploid species is an autopolyploid, despite observations that the species appears to be morphologically intermediate between Hylocereus and Selenicereus. Although the possibility of very narrow allopolyploidly (i.e., derivation from parents that are barely diverged from each other such as closely related species in the same genus) cannot be ruled out entirely based on our data (in part due to the unavailability of Hylocereus species considered to be morphologically the closest relatives of H. megalanthus), the possibility of H. megalanthus representing an intergeneric cross (i.e., Hylocereus × Selenicereus) seems extremely unlikely. Interestingly, the process of homogenization of ITS sequences (concerted evolution) is either incomplete or lacking in both Hylocereus and Selenicereus, and the inclusion of several artificial hybrids in the molecular study revealed the potential for biparental plastid inheritance in Hylocereus. The most important agricultural implication of this research project was the information collected for F1 and BC1 hybrids. Specifically, this project concluded with the selection of four superior hybrids in terms of fruit quality and potential yields under extreme high temperatures. These selected hybrids are self-compatible, avoiding the need for hand cross pollination to set fruits, thus reducing manpower costs. We recently offered these hybrids to growers in Israel for prioritized rapid evaluation and characterization.