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383 records · Page 22Linked to original sources

Cr3a, a candidate gene conferring fruit cracking resistance, was fine-mapped in an introgression line of Solanum lycopersicum L.

In the cultivation and production of tomato (Solanum lycopersicum L.), fruit cracking is a prevalent and detrimental issue that significantly impacts the esthetic quality and commercial value of the fruit. The complexity of the trait has resulted in a slow advancement in research aimed at identifying genes that influence tomato fruit cracking and the underlying regulatory mechanisms. In this study, a sub-introgression population for tomato crack-resistant fruit has been constructed from the cross between S. lycopersicum 1052 and Solanum pennellii LA0716, followed by 11 generations of selfing. Utilizing specifically designed InDel markers, the tomato crack-resistant gene, Cr3a, was fine-mapped, cloned, and its functionality was confirmed through transgenic and gene-knockout approaches. The precise localization of Cr3a was delineated to a 30 kb genomic region on chromosome 3, corresponding to the gene Sopen03g034650 in S. pennellii and Solyc03g115660.3 in the Heinz1706 variety. An integrated transcriptomic and metabolomic analysis of fruits with and without the Cr3a gene was finally conducted to elucidate the intricate regulatory mechanisms associated with Cr3a. The findings revealed a molecular regulatory network for tomato fruit crack resistance, characterized by 7 key metabolites, 13 pivotal genes, and 4 critical pathways: the phenylpropanoid biosynthesis pathway, the phenylalanine, tyrosine, and tryptophan biosynthesis pathway, the linolenic acid metabolism pathway, and the cysteine and methionine metabolism pathway. In summary, this research provides novel insights into the molecular underpinnings of tomato fruit crack resistance and holds substantial promise for accelerating the molecular breeding of tomatoes with enhanced fruit crack resistance.

Solanum lycopersicum↗

Toward the experimental codon reassignment in vivo: protein building with an expanded amino acid repertoire.

The high precision and fidelity of the genetic message transmission are ensured by numerous proofreading steps, from DNA replication and transcription to protein translation. The key event for translational fidelity is the proper codon assignment for 20 canonical amino acids. An experimental codon reassignment is possible for noncanonical amino acids in vivo using artificially constructed expression hosts under efficient selective pressure. However, such amino acids may interfere with the cellular metabolism and thus do not belong to the 'first' or 'restricted' part of the universal code, but rather to a second or 'relaxed' part, which is limited mainly by the downstream proofreading in the natural translational machinery. Correspondingly, not all possible alpha-amino acids can be introduced into proteins. The aim of this study is to discuss biological and evolutionary constraints on possible candidates for this second coding level of the universal code. Engineering of such a 'second' code is expected to have great academic as well as practical impact, ranging from protein folding studies to biomedicine.

Acylation↗

Complementary roles of cholecystokinin- and parvalbumin-expressing GABAergic neurons in hippocampal network oscillations.

In the hippocampal CA1 area, a relatively homogenous population of pyramidal cells is accompanied by a diversity of GABAergic interneurons. Previously, we found that parvalbumin-expressing basket, axo-axonic, bistratified, and oriens-lacunosum moleculare cells, innervating different domains of pyramidal cells, have distinct firing patterns during network oscillations in vivo. A second family of interneurons, expressing cholecystokinin but not parvalbumin, is known to target the same domains of pyramidal cells as do the parvalbumin cells. To test the temporal activity of these independent and parallel GABAergic inputs, we recorded the precise spike timing of identified cholecystokinin interneurons during hippocampal network oscillations in anesthetized rats and determined their molecular expression profiles and synaptic targets. The cells were cannabinoid receptor type 1 immunopositive. Contrary to the stereotyped firing of parvalbumin interneurons, cholecystokinin-expressing basket and dendrite-innervating cells discharge, on average, with 1.7 +/- 2.0 Hz during high-frequency ripple oscillations in an episode-dependent manner. During theta oscillations, cholecystokinin-expressing interneurons fire with 8.8 +/- 3.3 Hz at a characteristic time on the ascending phase of theta waves (155 +/- 81 degrees), when place cells start firing in freely moving animals. The firing patterns of some interneurons recorded in drug-free behaving rats were similar to cholecystokinin cells in anesthetized animals. Our results demonstrate that cholecystokinin- and parvalbumin-expressing interneurons make different contributions to network oscillations and play distinct roles in different brain states. We suggest that the specific spike timing of cholecystokinin interneurons and their sensitivity to endocannabinoids might contribute to differentiate subgroups of pyramidal cells forming neuronal assemblies, whereas parvalbumin interneurons contribute to synchronizing the entire network.

Action Potentials↗

Meiotic studies of infertile men in case of non-obstructive azoospermia with normal karyotype and no microdeleted Y-chromosome precise the clinical couple management.

To identify meiotic criteria for infertility management in non-obstructive azoospermic men, a prospective and multicentric study was organized in Andrological Departments of Paris (France), Roma (Italy) and Budapest (Hungary). In 117 non-obstructive azoospermic men with normal karyotype and no Y-chromosome microdeletion, histology and meiotic studies on bilateral bipolar testicular biopsies were done. Histologically, 40 patients (34%) presented spermatocyte or spermatid arrest, 39 (33%) hypospermatogenesis whereas no meiotic cell could be observed in the remaining patients (33%). Cytogenetically, meiotic figures could only be obtained from the two first histological groups. Meiotic abnormalities were observed in a total of 44 patients (37.6%) including nine patients (7.7%) with severe class I and class IIB anomalies and 19 patients (16.2%) with class IIC environmentally linked meiotic abnormalities. These results provided essential clues for an accurate clinical management. For patients with no meiotic figures and patients with class I and class IIB anomalies, an hormonal stimulation is illusory and a sperm gift should be directly proposed. An hormonal stimulation should be proposed to all the other patients, either directly or following the treatment of the testicular microenvironment for the patients presenting class IIC anomalies. The genetic risk and possibility of prenatal chromosomal analysis in case of pregnancy should be clearly exposed to all the couples in all the cases where type IIA, III or IV anomalies are present. This therapeutical strategy has been applied to all the patients in our series.

Chromosomes, Human, Y↗

SpacerScope: binary-vectorized, genome-wide off-target profiling for RNA-guided nucleases without prior candidate-site bias.

The precision of CRISPR/Cas systems is fundamental to their application in plant and animal biotechnology. However, comprehensive sequence-based off-target candidate discovery remains a computational bottleneck, particularly in large and complex genomes. Here we developed SpacerScope, an off-target candidate discovery framework that enables unbiased, genome-wide discovery by leveraging binary vectorization, bitwise filtering, and right-end-anchored alignment. Benchmarking against human CIRCLE-seq data demonstrated that SpacerScope recovered 100% of validated off-target sites (6142/6142), matching the sensitivity of exhaustive algorithms. Crucially, SpacerScope achieved this maximum candidate recovery while substantially reducing computational overhead. In large-genome evaluations, SpacerScope maintained low peak memory usage of 2.20 GiB and achieved substantial runtime improvements over indel-aware comparator tools, including more than 50-fold speedup relative to Cas-OFFinder 3 (544 s versus 29 185 s). Furthermore, comparative analyses in polyploid species, such as the octoploid strawberry, revealed that SpacerScope identified larger sequence-compatible candidate burdens than standard web-based design platforms. Our results establish SpacerScope as a high-speed framework for sequence-based genome-wide off-target candidate discovery across diverse and highly repetitive genomic landscapes. The source code and program was publicly available at https://github.com/charlesqu666/SpacerScope. Short Abstract CRISPR/Cas sequence-based off-target candidate discovery remains computationally challenging in large, repetitive, and polyploid genomes. Existing tools either miss indel-containing candidate sites or incur prohibitive runtime and memory costs. We developed SpacerScope, a binary-vectorized framework that enables unbiased, genome-wide off-target candidate discovery without pre-selected candidate sites. By integrating bitwise filtering with right-end-anchored alignment, SpacerScope recovered 100% of validated off-target sites in human CIRCLE-seq data while using only 2.20 GiB of memory and achieving more than 10-fold speedup over indel-aware alternatives. Evaluation in plant genomes, including rice and octoploid strawberry, further demonstrated SpacerScope's capacity to identify larger sequence-compatible candidate burdens overlooked by standard tools. SpacerScope thus provides a high-speed framework for sequence-based genome-wide off-target candidate discovery across diverse and highly repetitive genomic landscapes, supporting downstream prioritization.

CRISPR-Cas Systems↗