Mitochondrial DNA Research Articles

Tracing the origin of the alien pest Cydia pomonella in Algeria through a worldwide comparison of the species’ DNA barcodes

Abstract DNA barcodes (i.e., gene sequences used as identifiers for species identification) constitute a very useful tool in invasive pest research. Using them, we studied, for the first time, the origin and population structure of the alien Cydia pomonella in Africa, a major apple pest. We sequenced a fragment of the mitochondrial gene Cytochrome c oxidase subunit I (COI) from C. pomonella caterpillars collected in northern Algeria and compared them with DNA barcodes from the rest of the world available at public repositories. The phylogeny built upon that COI database supports the European origin of the species: haplotypes at the base of the phylogeny were registered in this continent. In Algeria, the results suggest that this pest could have been introduced from Europe, with two unique African mutations probably favoured by C. pomonella multivoltinism and large population sizes. Population genetic analyses at three Algerian localities showed neither structure nor founder effects. However, to confirm the underlying process of the observed population patterns, it is necessary to perform analyses using genes with higher mutation rates. Compared to higher resolution markers, mitochondrial DNA barcodes are still a cost‐effective tool for taxonomic determination of unknown specimens and, sometimes, may also allow a preliminary tracing of its origin. This is crucial to detect and stop the spread of invasive pests (i.e., borders). We encourage further studies including functional genes to assess whether any mutations are promoting C. pomonella adaptation to the Northern Africa environment.

Vgll2 as an integrative regulator of mitochondrial function and contractility specific to skeletal muscle.

During skeletal muscle adaptation to physiological or pathophysiological signals, contractile apparatus and mitochondrial function are coordinated to alter muscle fiber type. Although recent studies have identified various factors involved in modifying contractile proteins and mitochondrial function, the molecular mechanisms coordinating contractile and metabolic functions during muscle fiber transition are not fully understood. Using a gene-deficient mouse approach, our previous studies uncovered that vestigial-like family member 2 (Vgll2), a skeletal muscle-specific transcription cofactor activated by exercise, is essential for fast-to-slow adaptation of skeletal muscle. The current study provides evidence that Vgll2 plays a role in increasing muscle mitochondrial mass and oxidative capacity. Transgenic Vgll2 overexpression in mice altered muscle fiber composition toward the slow type and enhanced exercise endurance, which contradicted the outcomes observed with Vgll2 deficiency. Vgll2 expression was positively correlated with the expression of genes related to mitochondrial function in skeletal muscle, mitochondrial DNA content, and protein abundance of oxidative phosphorylation complexes. Additionally, Vgll2 overexpression significantly increased the maximal respiration of isolated muscle fibers and enhanced the suppressive effects of endurance training on weight gain. Notably, no additional alteration in expression of myosin heavy chain genes was observed after exercise, suggesting that Vgll2 plays a direct role in regulating mitochondrial function, independent of its effect on contractile components. The observed increase in exercise endurance and metabolic efficiency may be attributed to the acute upregulation of genes promoting fatty acid utilization as a direct consequence of Vgll2 activation facilitated by endurance exercise. Thus, the current study establishes that Vgll2 is an integrative regulator of mitochondrial function and contractility in skeletal muscle.

Timed topical dexamethasone eye drops improve mitochondrial function to prevent severe retinopathy of prematurity.

Pathological neovascularization in retinopathy of prematurity (ROP) can cause visual impairment in preterm infants. Current ROP treatments which are not preventative and only address late neovascular ROP, are costly and can lead to severe complications. We showed that topical 0.1% dexamethasone eye drops administered prior to peak neovessel formation prevented neovascularization in five extremely preterm infants at high risk for ROP and suppressed neovascularization by 30% in mouse oxygen-induced retinopathy (OIR) modeling ROP. In contrast, in OIR, topical dexamethasone treatment before any neovessel formation had limited efficacy in preventing later neovascularization, while treatment after peak neovessel formation had a non-statistically significant trend to exacerbating disease. Optimally timed topical dexamethasone suppression of neovascularization in OIR was associated with increased retinal mitochondrial gene expression and decreased inflammatory marker expression, predominantly found in immune cells. Blocking mitochondrial ATP synthetase reversed the inhibitory effect of dexamethasone on neovascularization in OIR. This study provides new insights into topical steroid effects in retinal neovascularization and into mitochondrial function in phase II ROP, and suggests a simple clinical approach to prevent severe ROP.

Mechanistic target of rapamycin (mTOR) pathway in Sertoli cells regulates age-dependent changes in sperm DNA methylation.

Over the past several decades, a trend toward delayed childbirth has led to increases in parental age at the time of conception. Sperm epigenome undergoes age-dependent changes increasing risks of adverse conditions in offspring conceived by fathers of advanced age. The mechanism(s) linking paternal age with epigenetic changes in sperm remain unknown. The sperm epigenome is shaped in a compartment protected by the blood-testes barrier (BTB) known to deteriorate with age. Permeability of the BTB is regulated by the balance of two mTOR complexes in Sertoli cells where mTOR complex 1 (mTORC1) promotes the opening of the BTB and mTOR complex 2 (mTORC2) promotes its integrity. We hypothesized that this balance is also responsible for age-dependent changes in the sperm epigenome. To test this hypothesis, we analyzed reproductive outcomes, including sperm DNA methylation in transgenic mice with Sertoli cell-specific suppression of mTORC1 (Rptor KO) or mTORC2 (Rictor KO). mTORC2 suppression accelerated aging of the sperm DNA methylome and resulted in a reproductive phenotype concordant with older age, including decreased testes weight and sperm counts, and increased percent of morphologically abnormal spermatozoa and mitochondrial DNA copy number. Suppression of mTORC1 resulted in the shift of DNA methylome in sperm opposite to the shift associated with physiological aging - sperm DNA methylome rejuvenation and mild changes in sperm parameters. These results demonstrate for the first time that the balance of mTOR complexes in Sertoli cells regulates the rate of sperm epigenetic aging. Thus, mTOR pathway in Sertoli cells may be used as a novel target of therapeutic interventions to rejuvenate the sperm epigenome in advanced-age fathers.

The genome sequence of the Violet Carpenter Bee, Xylocopa violacea (Linnaeus, 1785): a hymenopteran species undergoing range expansion.

We present a reference genome assembly from an individual male Violet Carpenter Bee (Xylocopa violacea, Linnaeus 1758). The assembly is 1.02 gigabases in span. 48% of the assembly is scaffolded into 17 pseudo-chromosomal units. The mitochondrial genome has also been assembled and is 21.8 kilobases in length. The genome is highly repetitive, likely representing a highly heterochromatic architecture expected of bees from the genus Xylocopa. We also use an evidence-based methodology to annotate 10,152 high confidence coding genes. This genome was sequenced as part of the pilot project of the European Reference Genome Atlas (ERGA) and represents an important addition to the genomic resources available for Hymenoptera.

Phylogeography of the ambrosia beetle Euwallacea interjectus (Coleoptera: Curculionidae: Scolytinae): an emerging poplar pest and its Fusarium mutualists from poplar plantations in China.

Native to Asia, Euwallacea interjectus (Blandford) (Coleoptera: Curculionidae: Scolytinae) is a destructive and invasive pest of live trees, and now it has been found in the United States and Argentina. In recent years, this pest appeared in high densities in poplar monocultures from Eastern China (Jiangsu and Shanghai) and Argentina and caused significant poplar mortality. However, the origin of the pests related to tree damage and the Fusarium mutualists from some poplar zones in China remained unclear. Here, we provided a broader phylogeographic analysis of E. interjectus based on the mitochondrial gene (cytochrome c oxidase I) to determine the global genetic structure of this species. Five mitochondrial lineages were found in the native area. Populations introduced to the United States were originated from 4 localities. The Argentine population was derived from Japan. The species was observed with strikingly high level of cytochrome c oxidase I intraspecific divergence that exceeded interspecific divergence, but the high intraspecific variation was correlated with geographical locations among the native populations. Two nuclear genes (arginine kinase and carbamoyl-phosphate synthetase 2-aspartate transcarbamylase-dihydroorotase) were more conservative, and intraspecific differences were lower than interspecific differences. The mitochondrial genetic variation was probably caused by evolution of lineages among geographically isolated populations. But it is immature to infer the existence of cryptic species based on cytochrome c oxidase I differences. All samples collected from poplar populations were indigenous and formed close relationship with a specimen from eastern and southern China. Surprisingly, pests from poplar populations in Jiangsu and Shanghai showed different haplotypes and mutualists. This suggested that the control strategies should consider the genetic and mutualistic diversity of beetles at different poplar localities.

A comprehensive atlas of nuclear sequences of mitochondrial origin (NUMT) inserted into the pig genome

BackgroundThe integration of nuclear mitochondrial DNA (mtDNA) into the mammalian genomes is an ongoing, yet rare evolutionary process that produces nuclear sequences of mitochondrial origin (NUMT). In this study, we identified and analysed NUMT inserted into the pig (Sus scrofa) genome and in the genomes of a few other Suinae species. First, we constructed a comparative distribution map of NUMT in the Sscrofa11.1 reference genome and in 22 other assembled S. scrofa genomes (from Asian and European pig breeds and populations), as well as the assembled genomes of the Visayan warty pig (Sus cebifrons) and warthog (Phacochoerus africanus). We then analysed a total of 485 whole genome sequencing datasets, from different breeds, populations, or Sus species, to discover polymorphic NUMT (inserted/deleted in the pig genome). The insertion age was inferred based on the presence or absence of orthologous NUMT in the genomes of different species, taking into account their evolutionary divergence. Additionally, the age of the NUMT was calculated based on sequence degradation compared to the authentic mtDNA sequence. We also validated a selected set of representative NUMT via PCR amplification.ResultsWe have constructed an atlas of 418 NUMT regions, 70 of which were not present in any assembled genomes. We identified ancient NUMT regions (older than 55 million years ago, Mya) and NUMT that appeared at different time points along the Suinae evolutionary lineage. We identified very recent polymorphic NUMT (private to S. scrofa, with < 1 Mya), and more ancient polymorphic NUMT (3.5–10 Mya) present in various Sus species. These latest polymorphic NUMT regions, which segregate in European and Asian pig breeds and populations, are likely the results of interspecies admixture within the Sus genus.ConclusionsThis study provided a first comprehensive analysis of NUMT present in the Sus scrofa genome, comparing them to NUMT found in other species within the order Cetartiodactyla. The NUMT-based evolutionary window that we reconstructed from NUMT integration ages could be useful to better understand the micro-evolutionary events that shaped the modern pig genome and enriched the genetic diversity of this species.

Complete mitochondrial genome and phylogenetic analysis of Dollfustrema vaneyi (Trematoda: Bucephalidae)

BackgroundThe Bucephalidae is a large family of digenean trematodes but most previous analyses of its phylogenetic position have relied on a single mitochondrial gene or morphological features. Mitochondrial genomes (mitogenomes) remain unavailable for the entire family. To address this, we sequenced the complete mitogenome of Dollfustrema vaneyi and analyzed the phylogenetic relationships with other trematodes.ResultsThe circular genome of Dollfustrema vaneyi spanned 14,959 bp and contained 12 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes, and a major non-coding region. We used concatenated amino acid and nucleotide sequences of all 36 genes for phylogenetic analyses, conducted using MrBayes, IQ-TREE and PhyloBayes. We identified pronounced topological instability across different analyses. The addition of recently sequenced two mitogenomes for the Aspidogastrea subclass along with the use of a site-heterogeneous model stabilized the topology, particularly the positions of Azygiidae and Bucephalidae. The stabilized results indicated that Azygiidae was the closest lineage to Bucephalidae in the available dataset, and together, they clustered at the base of the Plagiorchiida.ConclusionsOur study provides the first comprehensive description and annotation of the mitochondrial genome for the Bucephalidae family. The results indicate a close phylogenetic relationship between Azygiidae and Bucephalidae, and reveal their basal placement within the order Plagiorchiida. Furthermore, the inclusion of Aspidogastrea mitogenomes and the site-heterogeneous model significantly improved the topological stability. These data will provide key molecular resources for future taxonomic and phylogenetic studies of the family Bucephalidae.

Mitochondrial Aconitase and Its Contribution to the Pathogenesis of Neurodegenerative Diseases

This survey reviews modern ideas on the structure and functions of mitochondrial and cytosolic aconitase isoenzymes in eukaryotes. Cumulative experimental evidence about mitochondrial aconitases (Aco2) as one of the main targets of reactive oxygen and nitrogen species is generalized. The important role of Aco2 in maintenance of homeostasis of the intracellular iron pool and maintenance of the mitochondrial DNA is discussed. The role of Aco2 in the pathogenesis of some neurodegenerative diseases is highlighted. Inactivation or dysfunction of Aco2 as well as mutations found in the ACO2 gene appear to be significant factors in the development and promotion of various types of neurodegenerative diseases. A restoration of efficient mitochondrial functioning as a source of energy for the cell by targeting Aco2 seems to be one of the promising therapeutic directions to minimize progressive neurodegenerative disorders.

Ocular genetics in the Japanese population.

In today's globalized society, ophthalmologists can examine people of different ethnicities regardless of where they live. The frequency of disease-causing genes varies according to a patient's ethnic background. We explain genetic findings for Japanese patients with inherited eye diseases. Ocular genetics has made great advances over the past 30 years. For example, detecting mutations at nucleotide position 11778 in mitochondrial DNA was useful in the genetic diagnosis of Leber's hereditary optic neuropathy (LHON). I evaluated the genotype-phenotype relationship in cases of corneal dystrophy and inherited retinal dystrophy (IRD). I identified the entire exon sequence of the eyes shut homolog (EYS) gene in patients with autosomal recessive retinitis pigmentosa (RP). EYS gene mutations are the most frequent cause of autosomal recessive RP. RPGRIP1 may be a common causative gene with early-onset severe retinal dystrophy, including Leber congenital amaurosis. However, some genes have complex structures that are difficult to analyze, including the OPN1LW/OPN1MW gene cluster in blue cone monochromacy and the IKBKG/NEMO genes in incontinentia pigmenti. This review will also present two cases with uniparental disomy, a case of IRD with double mutations, and a case with RP complicated with LHON-like neuropathy. Precise understanding of the effects of genetic variants may reveal differences in the clinical characteristics of patients with the same variant. When starting genome medicine, accurately diagnosing the patient, making accurate prediction, determining the genetic pattern, and providing genetic counseling are important. Above all, that both the doctors and patients understand genetic diseases correctly is important.

Overactive mitochondrial DNA replication disrupts perinatal cardiac maturation

High mitochondrial DNA (mtDNA) amount has been reported to be beneficial for resistance and recovery of metabolic stress, while increased mtDNA synthesis activity can drive aging signs. The intriguing contrast of these two mtDNA boosting outcomes prompted us to jointly elevate mtDNA amount and frequency of replication in mice. We report that high activity of mtDNA synthesis inhibits perinatal metabolic maturation of the heart. The offspring of the asymptomatic parental lines are born healthy but manifest dilated cardiomyopathy and cardiac collapse during the first days of life. The pathogenesis, further enhanced by mtDNA mutagenesis, involves prenatal upregulation of mitochondrial integrated stress response and the ferroptosis-inducer MESH1, leading to cardiac fibrosis and cardiomyocyte death after birth. Our evidence indicates that the tight control of mtDNA replication is critical for early cardiac homeostasis. Importantly, ferroptosis sensitivity is a potential targetable mechanism for infantile-onset cardiomyopathy, a common manifestation of mitochondrial diseases.

Whole Mitochondrial Genome Sequencing Analysis of Canine Testicular Tumours

Currently, the molecular background based on mitochondrial DNA (mtDNA) analysis of canine testicular tumours is underestimated. The available data mostly focus on histopathological evaluations, with a few reports of nuclear genome (nDNA) studies. Tumourigenesis represents a highly complex and diverse genetic disorder, which can also encompass defects in mtDNA. The aim of this study was to identify molecular changes in whole mitochondrial genome sequences obtained from dogs affected by testicular tumours. Samples of blood, tumour, and healthy tissue were collected from each animal, and mtDNA (ultimately 45 samples) was subsequently sequenced. Thereafter, protein analyses were performed to assess the impact of the identified molecular alterations on the amino acid level. The total number of observed changes included 722 SNPs, 12 mutations, 62 indels, 5 indel mutations, and 35 heteroplasmic sites. The highest number of mtDNA variants in protein-coding genes COX1, COX3, ATP6, ND1, ND4, and ND5 was observed. Interestingly, SNPs were found in 10 out of 22 tRNA genes. Most of the identified mtDNA defects were synonymous changes at the amino acid level. Also, polymorphisms and heteroplasmy were frequently observed in the variable number of tandem repeat (VNTR) regions, especially in its fragment spanning 16,138-16,358 bp. Based on the obtained results, it was possible to select 11 polymorphisms that occurred in all the tested samples (benign, malignant) and an additional five SNPs identified only in benign neoplasms. The comprehensive analysis of malignant testicular tumours demonstrated a significant diversity in their molecular profiles, with changes ranging from 17 to 101 per sample.

A Gene Cluster of Mitochondrial Complexes Contributes to the Cognitive Decline of COVID-19 Infection.

"Brain fog," a persistent cognitive impairment syndrome, stands out as a significant neurological aftermath of coronavirus disease 2019 (COVID-19). Yet, the underlying mechanisms by which COVID-19 induces cognitive deficits remain elusive. In our study, we observed an upregulation in the expression of genes linked to the inflammatory response and oxidative stress, whereas genes associated with cognitive function were downregulated in the brains of patients infected with COVID-19. Through single-nucleus RNA sequencing (snRNA-seq) analysis, we found that COVID-19 infection triggers the immune responses in microglia and astrocytes and exacerbates oxidative stress in oligodendrocytes, oligodendrocyte progenitors (OPCs), and neurons. Further investigations revealed that COVID-19 infection elevates LUC7L2 expression, which inhibits mitochondrial oxidative phosphorylation (OXPHOS) and suppresses the expression of mitochondrial complex genes such as MT-ND1, MT-ND2, MT-ND3, MT-ND4L, MT-CYB, MT-CO3, and MT-ATP6. A holistic approach to protect mitochondrial complex function, rather than targeting a single molecular, should be an effective therapeutic strategy to prevent and treat the long-term consequences of "long COVID."

Cytoplasmic genomes of Jasminum sambac reveal divergent sub-mitogenomic conformations and a large nuclear chloroplast-derived insertion

BackgroundJasminum sambac, a widely recognized ornamental plant prized for its aromatic blossoms, exhibits three flora phenotypes: single-petal (“SP”), double-petal (“DP”), and multi-petal (“MP”). The lack of detailed characterization and comparison of J. sambac mitochondrial genomes (mitogenomes) hinders the exploration of the genetic and structural diversity underlying the varying floral phenotypes in jasmine accessions.ResultsHere, we de novo assembled three mitogenomes of typical phenotypes of J. sambac, “SP”, “DP”, and “MP-hutou” (“HT”), with PacBio reads and the “HT” chloroplast (cp) genome with Illumina reads, and verified them with read mapping and fluorescence in situ hybridization (FISH). The three mitogenomes present divergent sub-genomic conformations, with two, two, and four autonomous circular chromosomes ranging in size from 35.7 kb to 405.3 kb. Each mitogenome contained 58 unique genes. Ribosome binding sites with conserved AAGAAx/AxAAAG motifs were detected upstream of uncanonical start codons TTG, CTG and GTG. The three mitogenomes were similar in genomic content but divergent in structure. The structural variations were mainly attributed to recombination mediated by a large (~ 5 kb) forward repeat pair and several short repeats. The three jasmine cp. genomes showed a well-conserved structure, apart from a 19.9 kb inversion in “HT”. We identified a 14.3 kb “HT”-specific insertion on Chr7 of the “HT” nuclear genome, consisting of two 7 kb chloroplast-derived fragments with two intact ndhH and rps15 genes, further validated by polymerase chain reaction (PCR). The well-resolved phylogeny suggests faster mitogenome evolution in J. sambac compared to other Oleaceae species and outlines the mitogenome evolutionary trajectories within Lamiales. All evidence supports that “DP” and “HT” evolved from “SP”, with “HT” being the most recent derivative of “DP”.ConclusionThe comprehensive characterization of jasmine organelle genomes has added to our knowledge of the structural diversity and evolutionary trajectories behind varying jasmine traits, paving the way for in-depth exploration of mechanisms and targeted genetic research.

An expert rule-based approach for identifying infantile-onset Pompe disease patients using retrospective electronic health records

Pompe disease (OMIM #232300), a rare genetic disorder, leads to glycogen buildup in the body due to an enzyme deficiency, particularly harming the heart and muscles. Infantile-onset Pompe disease (IOPD) requires urgent treatment to prevent mortality, but the unavailability of these methods often delays diagnosis. Our study aims to streamline IOPD diagnosis in the UAE using electronic health records (EHRs) for faster, more accurate detection and timely treatment initiation. This study utilized electronic health records from the Abu Dhabi Healthcare Company (SEHA) healthcare network in the UAE to develop an expert rule-based screening approach operationalized through a dashboard. The study encompassed six diagnosed IOPD patients and screened 93,365 subjects. Expert rules were formulated to identify potential high-risk IOPD patients based on their age, particular symptoms, and creatine kinase levels. The proposed approach was evaluated using accuracy, sensitivity, and specificity. The proposed approach accurately identified five true positives, one false negative, and four false positive IOPD cases. The false negative case involved a patient with both Pompe disease and congenital heart disease. The focus on CHD led to the overlooking of Pompe disease, exacerbated by no measurement of creatine kinase. The false positive cases were diagnosed with Mitochondrial DNA depletion syndrome 12-A (SLC25A4 gene), Immunodeficiency-71 (ARPC1B mutation), Niemann–Pick disease type C (NPC1 gene mutation leading to frameshift), and Group B Streptococcus meningitis. The proposed approach of integrating expert rules with a dashboard facilitated efficient data visualization and automated patient screening, which aids in the early detection of Pompe disease. Future studies are encouraged to investigate the application of machine learning methodologies to enhance further the precision and efficiency of identifying patients with IOPD.

The updated mouse universal genotyping array bioinformatic pipeline improves genetic QC in laboratory mice.

The MiniMUGA genotyping array is a popular tool for genetic quality control of laboratory mice and genotyping samples from most experimental crosses involving laboratory strains, particularly for reduced complexity crosses. The content of the production version of the MiniMUGA array is fixed; however, there is the opportunity to improve the array's performance and the associated report's usefulness by leveraging thousands of samples genotyped since the initial description of MiniMUGA. Here, we report our efforts to update and improve marker annotation, increase the number and the reliability of the consensus genotypes for classical inbred strains and substrains, and increase the number of constructs reliably detected with MiniMUGA. In addition, we have implemented key changes in the informatics pipeline to identify and quantify the contribution of specific genetic backgrounds to the makeup of a given sample, remove arbitrary thresholds, include the Y Chromosome and mitochondrial genome in the ideogram, and improve robust detection of the presence of commercially available substrains based on diagnostic alleles. Finally, we have updated the layout of the report to simplify the interpretation and completeness of the analysis and added a section summarizing the ideogram in table format. These changes will be of general interest to the mouse research community and will be instrumental in our goal of improving the rigor and reproducibility of mouse-based biomedical research.

Cascade testing in mitochondrial diseases: a cross-sectional retrospective study

BackgroundCascade testing can offer improved surveillance and timely introduction of clinical management for the at-risk biological relatives. Data on cascade testing and costs in mitochondrial diseases are lacking. To address this gap, we performed a cross-sectional retrospective study to provide a framework for cascade testing in mitochondrial diseases, to estimate the eligibility versus real-time uptake of cascade testing and to evaluate the cost of the genetic diagnosis of index cases and the cost of predictive cascade testing.MethodsData was collected through retrospective chart review. The variant inheritance pattern guided the identification of eligible first-degree relatives: (i) Males with mitochondrial DNA (mtDNA) single nucleotide variants (SNVs) – siblings and mothers. (ii) Females with mtDNA SNVs – siblings, mothers and offspring. (iii) Autosomal Dominant (AD) nuclear DNA (nDNA) variants – siblings, offspring and both parents. (iv) Autosomal Recessive (AR) nDNA variants – siblings.ResultsWe recruited 99 participants from the Adult Mitochondrial Disease Clinic in Sydney. The uptake of cascade testing was 55.2% in the mtDNA group, 55.8% in the AD nDNA group and 0% in AR nDNA group. Of the relatives in mtDNA group who underwent cascade testing, 65.4% were symptomatic, 20.5% were oligosymptomatic and 14.1% were asymptomatic. The mean cost of cascade testing for eligible first-degree relatives (mtDNA group: $694.7; AD nDNA group: $899.1) was lower than the corresponding index case (mtDNA group: $4578.4; AD nDNA group: $5715.1) (p < 0.001).ConclusionThe demand for cascade testing in mitochondrial diseases varies according to the genotype and inheritance pattern. The real-time uptake of cascade testing can be influenced by multiple factors. Early diagnosis of at-risk biological relatives of index cases through cascade testing, confirms the diagnosis in those who are symptomatic and facilitates implementation of surveillance strategies and clinical care at an early stage of the disease.

478 Impact of crude protein and phosphorus deficiencies on liver mitochondrial content and transcriptome in growing Merino wethers

Abstract In grazing systems in Northern Australia, crude protein (CP) and phosphorus (P) availability varies, affecting ruminant production due to voluntary reduced intake and therefore body weight (BW) gain. We were interested in understanding metabolic regulation in this model system, both in terms of a) identifying key tissues, and b) detecting any modifications in mitochondrial physiology, given the central role of this organelle in bioenergetic homeostasis. Merino wethers (n = 24) were subjected to three dietary regimens: High CP, High P, (Control), Low CP, Low P (Deficient), and High CP, High P, with restricted feed intake (Restricted). Mitochondrial DNA (mtDNA) copy numbers, indicative of mitochondrial content, were measured via qPCR. Transcriptomic analyses through RNA sequencing targeted mitochondria-associated gene expression changes and pathways, using the MitoCarta 3.0 database. There was a significant decrease of mtDNA copy numbers in the liver of sheep under either Deficient and Restricted diets (P &amp;lt; 0.01), with as much as a 2-fold difference between the Control and Deficient diets. This may suggest reduced mitochondrial biogenesis as an adaptation to decreased energy intake. When compared with the Control group, both the Deficient and Restricted groups upregulated pathways related to vitamin metabolism (Log2FC: 0.231 and 0.449) and folate and 1-C metabolism (Log2FC: 0.409 and 0.706). However, impacted pathways shared between these two comparisons (Control v Deficient, Control v Restricted) also include choline and betaine metabolism, amino acid metabolism, and glycine metabolism, which suggests similar mechanisms being impacted by decreased energy intake, regardless of whether it is due to satiety from nutrient deficiency or restricted feed intake. Notably, the creatine metabolism pathway was uniquely upregulated in the Restricted group compared with the Deficient group (Log2FC: 0.114), although the CKMT2 gene was upregulated in the Restricted group compared with both the Control and Deficient group (Log2FC: 1.30 and 0.879). Additionally, the SLC25A family pathway, responsible for mitochondrial metabolite transport, was found to be upregulated in the Restricted group when compared with both Control and Deficient groups (Log2FC: 0.33 and 0.865). Overall, this study demonstrated a pronounced decrease in mitochondrial content in the liver of growing Merino wethers subjected to nutritional deficiencies and feed restriction. Multiple metabolic pathways were shared between the comparisons of the Control diet group to both Deficient and Restricted nutritional treatments. However, the SLC25A transporter family pathway was uniquely upregulated in the Restricted group compared with either an optimal or deficient diet. The regulation of these metabolic pathways is a subject of further study that may represent a systemic response to maintain homeostasis while undergoing significantly lower energy intake, with implications for animal growth, tissue deposition, and energetic maintenance. Understanding distinctions in the response to feed restriction and nutrient deficiency induced reduction in intake may help improve production strategies for ruminants grazing in these conditions.

PGC-based cryobanking, regeneration through germline chimera mating, and CRISPR/Cas9-mediated TYRP1 modification in indigenous Chinese chickens

Primordial germ cells (PGCs) are vital for producing sperm and eggs and are crucial for conserving chicken germplasm and creating genetically modified chickens. However, efforts to use PGCs for preserving native chicken germplasm and genetic modification via CRISPR/Cas9 are limited. Here we show that we established 289 PGC lines from eight Chinese chicken populations with an 81.6% success rate. We regenerated Piao chickens by repropagating cryopreserved PGCs and transplanting them into recipient chickens, achieving a 12.7% efficiency rate. These regenerated chickens carried mitochondrial DNA from female donor PGC and the rumplessness mutation from both male and female donors. Additionally, we created the TYRP1 (tyrosinase-related protein 1) knockout (KO) PGC lines via CRISPR/Cas9. Transplanting KO cells into male recipients and mating them with wild-type hens produced four TYRP1 KO chickens with brown plumage due to reduced eumelanin production. Our work demonstrates efficient PGC culture, cryopreservation, regeneration, and gene editing in chickens.

Role of Mitochondrial Dysfunctions in Neurodegenerative Disorders: Advances in Mitochondrial Biology.

Mitochondria, essential organelles responsible for cellular energy production, emerge as a key factor in the pathogenesis of neurodegenerative disorders. This review explores advancements in mitochondrial biology studies that highlight the pivotal connection between mitochondrial dysfunctions and neurological conditions such as Alzheimer's, Parkinson's, Huntington's, ischemic stroke, and vascular dementia. Mitochondrial DNA mutations, impaired dynamics, and disruptions in the ETC contribute to compromised energy production and heightened oxidative stress. These factors, in turn, lead to neuronal damage and cell death. Recent research has unveiled potential therapeutic strategies targeting mitochondrial dysfunction, including mitochondria targeted therapies and antioxidants. Furthermore, the identification of reliable biomarkers for assessing mitochondrial dysfunction opens new avenues for early diagnosis and monitoring of disease progression. By delving into these advancements, this review underscores the significance of understanding mitochondrial biology in unraveling the mechanisms underlying neurodegenerative disorders. It lays the groundwork for developing targeted treatments to combat these devastating neurological conditions.