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Genetic rescue stabilizes diversity in small isolated populations of Bonneville cutthroat trout.

Genetic diversity loss due to anthropogenic factors is occurring rapidly on a global scale, putting many species at risk of extirpation and extinction. Different management strategies have been developed to slow this loss; however, it is often unknown whether these strategies reach their intended goals. In this study, we evaluate population structure and changes in nucleotide diversity (π) in isolated populations of Bonneville cutthroat trout (Oncorhynchus clarkii utah) from the Snake Range (Nevada, USA). Starting in the 1990s, three of these populations were used to reestablish populations in the Snake Range because many of the historic populations were extirpated. Some populations were stocked using a single-source and others were stocked using multiple-sources. Using low-coverage whole-genome sequencing coupled with historic samples (2003-2010) and contemporary samples (2019-2022), we find that single-source populations lost nucleotide diversity while mixed-source populations maintained nucleotide diversity. Further, source populations used to restore populations throughout the Snake Range lost the most nucleotide diversity over the time span evaluated. Our findings provide insight into how small, isolated populations can be managed to maintain genetic diversity.

Animals

Genetic rescue of a lethal "null" activity allele of 6-phosphogluconate dehydrogenase in Drosophila melanogaster.

While a null activity mutant allele of the structural gene for 6-phosphogluconate dehydrogenase in Drosophila melanogaster is lethal, a similar mutation for glucose-6-phosphate dehydrogenase is not. Double mutant combinations lacking both enzyme activities, obtained either by recombination or by mutagen treatment of a chromosome bearing the lethal allele, result in a restoration of viability. The indispensability of the pentose phosphate shunt in Drosophila appears to depend upon the specific position of the block within the pathway.

Alleles

Genomic consequences of admixture in an experimentally founded sand lizard population.

Conservation interventions are increasingly required for species threatened by population declines and isolation due to anthropogenic pressures. Small, isolated populations are particularly vulnerable to the loss of genetic diversity, increased inbreeding, and the accumulation of deleterious mutations. Translocations or supplementation of allopatric individuals for genetic rescue may be the only way to increase genetic diversity and increase population persistence via increased adaptive potential. Here, we use an experimentally admixed population of sand lizards on a small island in Sweden as a valuable model of genetic rescue. This population was established approximately 20 years ago (5-6 generations), resulting in increased fecundity and hatchling viability. This population was founded from crossings between individuals from an inbred population from the nearby mainland and individuals sourced from populations in southern Sweden. Low-coverage whole-genome sequencing revealed elevated genetic diversity and reduced realized genetic load in this admixed population relative to the source populations. Ancestry analyses indicated a greater contribution of southern Swedish genetic variation, potentially reflecting the contribution of beneficial adaptive variation from this region that may underlie the positive population effects. This system provides valuable empirical insights into the long-term genomic consequences of genetic rescue in this model vertebrate population.

Journal Article

Conservation Arks: Genomic Erosion and Inbreeding in an Abundant Island Population of Koalas.

The persistence of many threatened species depends on isolated habitat patches such as conservation parks, fenced reserves, and islands. While these 'conservation arks' provide refuge from many contemporary threats, they can also pose risks of genetic diversity loss and inbreeding depression, further exacerbating extinction risk. A pertinent example is the Kangaroo Island koala population in South Australia that originated from a few translocated founding individuals in the 1920s but now sustains a large population with a low prevalence of infectious disease. We investigated the extent and consequences of founder effects on genomic diversity, inbreeding, and adaptive potential in Kangaroo Island koalas by comparing them with mainland Australian populations using high-coverage whole genomes. Our findings support sharp, recent declines in effective population sizes (Ne) in both mainland and Kangaroo Island populations. However, Kangaroo Island koalas had much lower individual and population-level diversity. Together with longer and more numerous runs of homozygosity and an increased proportion of homozygous genetic load, these results support the hypothesis that a severe bottleneck has contributed to inbreeding and maladaptation in Kangaroo Island koalas. While Kangaroo Island has the potential to conserve a viable population of koalas, we recommend genetic rescue to restore diversity and mitigate inbreeding depression in this isolated population. Our results emphasise the need for longitudinal genomic monitoring and genetic management to maintain long-term viability and resilience in potential conservation arks. Understanding the demographic history of such populations will help inform future conservation aimed at preventing genetic erosion and preserving biodiversity.

Animals

Dietary rescue of a lethal "null" activity allele of 6-phosphogluconate dehydrogenase in Drosophila melanogaster.

The genetic rescue of Pgdn lethal alleles, accomplished by combining them with mutations lacking glucose-6-phosphate dehydrogenase activity, has led to the hypothesis that Pgdn lethality may be due to the accumulation of 6-phosphogluconate. In this article we report the rescue of Pgdn/Y males by dietary supplements (fructose and linolenate) designed to minimize 6-phosphogluconate production.

Animals

Evolving conservation: The role of unconventional approaches to restore contemporary vertebrate populations and genomic biodiversity.

Conservation biology and restoration ecology are two essential yet distinct disciplines that address the growing challenge of biodiversity loss. Traditionally, these fields have relied on ecological principles and management practices aimed at protecting or reestablishing natural systems. The crisis is no longer just ecological; it is evolutionary and genomic. The accelerating pace of environmental change has outstripped the capacity of conventional approaches, creating a pressing need for innovative solutions. Biotechnology offers potentially transformative tools that can enhance the effectiveness and precision of both conservation and restoration efforts, especially for species where conventional conservation approaches have proved insufficient. Techniques such as genetic rescue, synthetic biology, and gene editing are increasingly being explored to address critical challenges, such as invasive species control, genetic diversity loss, and habitat fragmentation, to both invigorate endangered species and restore historical biodiversity. Despite its promise, the integration of biotechnology into conservation and restoration has raised ethical, ecological, and regulatory concerns. These include ecological unpredictability and public resistance to genetic interventions in wild populations. This perspective examines the current landscape of biotechnological applications in conservation and restoration, highlighting successful case studies, ongoing controversies, and optimism for additional progress. We argue that thoughtful, transparent integration of biotechnology that is grounded in ecological knowledge and stakeholder engagement can reconcile the goals of conservation and restoration. As ecosystems face mounting pressures, biotech-enabled strategies may prove essential for fostering resilience and ensuring long-term ecological sustainability.

Conservation of Natural Resources

Conservation genomics of a threatened subtropical Rhododendron species highlights the distinct conservation actions required in marginal and admixed populations.

With the impact of climate change and anthropogenic activities, the underlying threats facing populations with different evolutionary histories and distributions, and the associated conservation strategies necessary to ensure their survival, may vary within a species. This is particularly true for marginal populations and/or those showing admixture. Here, we re-sequence genomes of 102 individuals from 21 locations for Rhododendron vialii, a threatened species distributed in the subtropical forests of southwestern China that has suffered from habitat fragmentation due to deforestation. Population structure results revealed that R. vialii can be divided into five genetic lineages using neutral single-nucleotide polymorphisms (SNPs), whereas selected SNPs divide the species into six lineages. This is due to the Guigu (GG) population, which is identified as admixed using neutral SNPs, but is assigned to a distinct genetic cluster using non-neutral loci. R. vialii has experienced multiple genetic bottlenecks, and different demographic histories have been suggested among populations. Ecological niche modeling combined with genomic offset analysis suggests that the marginal population (Northeast, NE) harboring the highest genetic diversity is likely to have the highest risk of maladaptation in the future. The marginal population therefore needs urgent ex situ conservation in areas where the influence of future climate change is predicted to be well buffered. Alternatively, the GG population may have the potential for local adaptation, and will need in situ conservation. The Puer population, which carries the heaviest genetic load, needs genetic rescue. Our findings highlight how population genomics, genomic offset analysis, and ecological niche modeling can be integrated to inform targeted conservation.

Rhododendron

Integrating Biobanking Into Conservation Practice: The Development and Impact of the EAZA Biobank.

Zoological biobanks are becoming essential tools in conservation, offering a means to preserve genetic material and support in situ population management amid accelerating biodiversity loss. With rapid advances in genomics, cryopreservation, and assisted reproduction technologies, biobanks enable a proactive approach to providing insurance against genetic erosion and facilitating future research, supplementation, and genetic rescue. However, to be effective, zoological biobanks must be purposefully designed, strategically integrated into conservation frameworks such as the Convention on Biological Diversity (CBD) Kunming-Montreal Global Biodiversity Framework (KMGBF), and regularly evaluated for coverage and impact. Using the EAZA Biobank as an example, we outline the structure, development, and collaborative foundations that have enabled its rapid growth, built on community support and conservation impact. Leveraging EAZA's institutional network and data-sharing platforms such as ZIMS, the Biobank employs a decentralized, four-hub model of zoological institutions storing samples. A gap analysis, integrating threat status, breeding programs, genomic data repositories, and phylogenetic diversity, highlights current sampling strengths and deficiencies and guides future collection priorities. The integration of specimen-specific genomic data and the EAZA Biobank Cryonetwork of institutions with expertise in storing and generating gametes and cell lines will expand the Biobank's role in population management and conservation. Zoological biobanks must now evolve alongside advances in biotechnology and genomics. Sample collection strategies should serve conservation needs and anticipate future applications in genomics, cryobiology, and conservation medicine, linking biospecimens with the wealth of data generated from them. This approach should be scalable beyond EAZA, forming the foundation of a global standardized biobanking framework. Ultimately, zoological biobanks are not merely repositories of the past-they are essential infrastructures shaping the future potential of species conservation.

EAZA

Genetic and biochemical screens identify MGAT1 as a druggable glycosyltransferase target in STK11-mutant lung cancer.

Checkpoint inhibitors are standard-of-care therapies for non-small cell lung cancer (NSCLC), but their efficacy is limited in tumors with STK11 mutations, highlighting the need for new therapeutic strategies. Here, we performed complementary in vivo and in vitro CRISPR-Cas9 functional genomic screens to identify genes whose loss restores sensitivity to anti-PD-1 therapy. We found that loss of MGAT1, a Golgi glycosyltransferase critical for the maturation of high-mannose N-glycans into hybrid and complex glycan structures, reversed resistance to anti-PD-1 treatment in syngeneic mouse tumor models harboring STK11 mutations. Parallel co-culture screens with antigen-matched CD8+ T cells further showed that disruption of N-glycosylation strongly sensitized tumor cells to T cell-mediated killing. Genetic rescue studies demonstrated that this immune-evasion phenotype depends on MGAT1 catalytic activity, supporting direct biochemical interrogation of the enzyme. Using purified human MGAT1 and a UDP-Glo™ glycosyltransferase assay, we established a tractable screening platform and performed a 500,000-compound biochemical high-throughput screen, identifying an initial hit (compound 1; IC50 = 197 μM). Subsequent medicinal chemistry optimization delivered progressively more potent analogs, including TNG-9333 (0.814 μM) and TNG-2673 (0.043 μM) and represented a >1000-fold improvement in biochemical potency from the starting hit. Crystal structures of human MGAT1 in apo, UDP-bound, UDP-GlcNAc-bound, and inhibitor-bound states, together with SPR and DSF analyses, revealed that this chemical series engages a previously unrecognized allosteric pocket and inhibits MGAT1 through a UDP-noncompetitive mechanism. Collectively, our work implicates N-glycosylation as a key mediator of immune evasion and establishes MGAT1 as a ligandable, structurally tractable target for small-molecule drug discovery.

CRISPR/Cas9 target discovery

Oncogenic DEAD-box ATPase DDX41 establishes transcript ensembles via CLK3-dependent and -independent mechanisms.

Post-transcriptional diversification of RNA transcripts mediated by complex processing machinery, including DEAD-box ATPases, establishes and maintains cellular phenotypes. For example, DDX41 controls RNA splicing, innate immune signaling, and genome stability. Although heterozygous DDX41 germline genetic variation occurs in familial myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML), the DDX41 contributions to splicing globally, biological processes, and pathogenic mechanisms are incompletely defined. Using a genetic rescue system with Ddx41+/- myeloid progenitors, we established global wildtype DDX41 and pathogenic variant mechanisms. Differing from pathogenic variants of other RNA splicing regulators, DDX41 deficiency compromised multiple splicing steps. DDX41-regulated transcripts encoded factors controlling RNA splicing, including Cdc2-like kinase 3 (CLK3). DDX41 regulated Clk3 transcripts, and elevated CLK3 during myeloid differentiation. Loss-of-function analysis revealed DDX41-regulated splicing commonly, but not always, required CLK3. Thus, through a mechanism utilizing a splicing factor kinase that itself is DDX41-regulated, DDX41 establishes transcript ensembles in myeloid progenitors.

DEAD-box RNA Helicases

Rapid derivation of cloning-competent cells from peripheral blood advances conservation biobanking.

Establishing viable cell lines from endangered species is essential for conservation, yet traditional fibroblast derivation from skin biopsies faces challenges including contamination risk and extended culture timelines. Here, we demonstrate that endothelial progenitor cells (EPCs) and pericytes isolated from peripheral blood represent robust alternatives to fibroblasts for biobanking. Compared to canid fibroblasts, canid blood-derived cells exhibit 2- to 3-fold faster doubling rates (15 to 20 h vs. ~35 h for fibroblasts) and reduced time to banked cell lines (1.5 to 2 wks vs. 3 to 4 wks for fibroblasts). Proteomic profiling of 32 canonical markers confirmed EPCs and pericytes represent distinct populations with lineage-specific molecular signatures. Optical genome mapping demonstrated equivalent genomic stability across cell types with no detectable structural variants or aneuploidies. Finally, interspecific somatic cell nuclear transfer (iSCNT) experiments confirmed both EPCs and pericytes generate viable canid embryos with efficiency meeting or exceeding fibroblasts. As a proof of concept for conservation cloning, iSCNT embryos made with gray wolf blood-derived cells had a 15% implantation rate following embryo transfer and resulted in six viable fetuses. These findings support integrating blood-derived cell banking into conservation programs, which enables opportunistic genetic preservation during standard management activities and expands options for genetic rescue through assisted reproductive technologies.

Animals

Induced Pluripotent Stem Cells in Non-Model Species: Applications and Challenges.

Induced pluripotent stem cells have revolutionized biomedical research-yet the vast majority of life on Earth remains beyond their reach. Non-model species lack the annotated genomes, validated reagents, and species-specific culture infrastructure that make iPSC technology routine in humans and mice, and this infrastructure deficit, compounded by genuine biological differences in pluripotency network architecture across taxa, is what has kept the field narrow. The deep conservation of the core pluripotency network across vertebrates suggests that reprogramming may, in principle, be achievable across a far broader range of species than currently demonstrated-though the extent to which this holds across more divergent taxa remains to be established. This review consolidates current progress and future potential of iPSC technology across five domains: technical reprogramming challenges and advances; conservation applications including genetic rescue, in vitro gametogenesis, and de-extinction; medical applications within a one medicine framework; agricultural applications spanning disease resistance, climate resilience, and cultured meat; and species-specific iPSC-derived systems in ecotoxicology. Throughout, we distinguish what has been demonstrated from what remains aspirational and identify the priorities that will determine whether the iPSC revolution can be extended-rigorously and at scale-beyond model organism research.

Induced Pluripotent Stem Cells

Marker rescue of endogenous cellular genetic information related to the avian leukosis virus gene encoding RNA-directed DNA polymerase.

Endogenous cellular genetic information related to the avian leukosis virus gene encoding RNA-directed DNA polymerase was studied, using a marker rescue assay to detect biological activity of subgenomic fragments of virus-related DNAs of uninfected avian cells. Recipient cultures of chicken embryo fibroblasts were treated with sonicated DNA fragments and were infected with a temperature-sensitive mutant of Rous sarcoma virus that encoded a thermolabile DNA polymerase. Wild-type progeny viruses were isolated by marker rescue with fragments of DNA of uninfected chicken, pheasant, quail, and turkey cells. The DNAs of these uninfected avian cells, therefore, appeared to contain endogenous genetic information related to the avian leukosis virus DNA polymerase gene.

Animals

Construction of Reverse Genetics System for Feline Calicivirus FCV-BJ616 and Proteomic Analysis.

Feline calicivirus (FCV) is a primary cause of upper respiratory tract infections and oral ulcerative disease in cats and exhibits substantial genetic diversity that complicates prevention and control. In this study, we isolated the FCV-BJ616 strain, established a reverse-genetics system, and investigated its pathogenic mechanisms, thereby providing a foundation for antibody-based therapies and broad-spectrum vaccine development. The virus was purified by three rounds of plaque cloning, and its morphology was examined by electron microscopy. VP1 expression was confirmed by immunofluorescence and Western blotting. Using integrated systems-biology and reverse-genetics approaches, an infectious clone of rFCV-BJ616 was successfully assembled and rescued, exhibiting genetic stability comparable to that of the parental strain. In vivo infection experiments showed that rFCV-BJ616 retained wild-type virulence, causing persistent high fever, weight loss, and multiorgan pathology in infected cats. Proteomic analysis indicated that infection with FCV-BJ616 or rFCV-BJ616 markedly activated cytokine-mediated inflammatory signaling pathways. Both FCV-BJ616 and rFCV-BJ616 significantly upregulated the expression of IL-8, S100A8/A9, and TLR3, which are associated with acute inflammation and tissue damage. Furthermore, elevated IFN-β levels concomitant with STAT1 downregulation suggested a transient attenuation of antiviral signaling during early immune activation. These findings were corroborated by ELISA-based validation of serum cytokine profiles. Collectively, this study provides new insights into the molecular pathogenesis and evolution of FCV-BJ616 and establishes a robust reverse-genetics platform for precise genome manipulation and future vaccine development.

Animals

Androgen-sensitive hypertension associated with soluble guanylate cyclase-α1 deficiency is mediated by 20-HETE.

Dysregulated nitric oxide (NO) signaling contributes to the pathogenesis of hypertension, a prevalent and often sex-specific risk factor for cardiovascular disease. We previously reported that mice deficient in the α1-subunit of the NO receptor soluble guanylate cyclase (sGCα1 (-/-) mice) display sex- and strain-specific hypertension: male but not female sGCα1 (-/-) mice are hypertensive on an 129S6 (S6) but not a C57BL6/J (B6) background. We aimed to uncover the genetic and molecular basis of the observed sex- and strain-specific blood pressure phenotype. Via linkage analysis, we identified a suggestive quantitative trait locus associated with elevated blood pressure in male sGCα1 (-/-)S6 mice. This locus encompasses Cyp4a12a, encoding the predominant murine synthase of the vasoconstrictor 20-hydroxy-5,8,11,14-eicosatetraenoic acid (20-HETE). Renal expression of Cyp4a12a in mice was associated with genetic background, sex, and testosterone levels. In addition, 20-HETE levels were higher in renal preglomerular microvessels of male sGCα1 (-/-)S6 than of male sGCα1 (-/-)B6 mice. Furthermore, treating male sGCα1 (-/-)S6 mice with the 20-HETE antagonist 20-hydroxyeicosa-6(Z),15(Z)-dienoic acid (20-HEDE) lowered blood pressure. Finally, 20-HEDE rescued the genetic background- and testosterone-dependent impairment of acetylcholine-induced relaxation in renal interlobar arteries associated with sGCα1 deficiency. Elevated Cyp4a12a expression and 20-HETE levels render mice susceptible to hypertension and vascular dysfunction in a setting of sGCα1 deficiency. Our data identify Cyp4a12a as a candidate sex-specific blood pressure-modifying gene in the context of deficient NO-sGC signaling.

Androgens

Physical mapping of herpes simplex virus type 1 mutations by marker rescue.

A generally applicable technique which permits the rescue of selected genetic markers from fragments of herpes simplex virus DNA is described. Baby hamster kidney cells infected at the nonpermissive temperature with intact DNA from temperature-sensitive mutants or with fragmented wild-type DNA produce no, or little, infectious progeny. Coinfection results in an increased yield of virus, demonstrating the rescue of genetic information from the DNA fragments. This progeny virus consists of both wild-type and temperature-sensitive virus, demonstrating that both recombination and complementation can occur in coinfected cells. Rescue experiments using isolated fragments produced with various restriction endonucleases have enabled us to locate five temperature-sensitive mutations on the herpes simplex virus type 1 physical map. An adaptation of the technique has allowed the physical mapping of a mutation which affects the herpes simplex virus type 1 pyrimidine deoxyribonucleoside kinase gene. Comparison of the genetic and physical maps for these mutants reveals several anomalies which are discussed.

Cell Line

Functional minigenome system reveals polymerase features of swine orthopneumovirus.

Swine orthopneumovirus (SOV), a recently identified porcine pneumovirus, has been detected in pig farms worldwide; however, its pathogenicity and molecular biology remain poorly understood. To facilitate the study of SOV replication and transcription, we developed a functional minigenome system based on consensus sequences from multiple strains of SOV and related pneumoviruses. Here, we constructed and optimized this system in BSRT7/5 cells, revealing that the RNA-dependent RNA polymerase (RdRp) activity depends on a conserved protein phosphatase 1 (PP1) binding site within the phosphoprotein P, as a single F131A substitution markedly reduced polymerase function. Additionally, we identified and characterized the M2-1 binding site on P, which is essential for viral transcription. These findings provide new insights into SOV polymerase complex requirements and establish a foundation for reverse genetics approaches to rescue infectious viruses, advancing our understanding of SOV biology and its potential role in porcine respiratory disease.IMPORTANCERecently, a newly identified porcine pneumovirus, swine orthopneumovirus (SOV), was detected in pig farms in different countries. Although detected mainly in sick animals, this virus has not been isolated yet and its pathogenicity remains to be determined. We started by setting up a minigenome system with a view to develop reverse genetics and rescue infectious virions. This minigenome system was used to study the functioning of the SOV RNA polymerase and compared it with RSV. Although some similarities exist between SOV and RSV, the RdRp of RSV cannot rescue the SOV minigenome. SOV seems to belong to another genus/genogroup of pneumoviruses, which includes PVM and the canine pneumovirus. Our functional minigenome paves the way for reverse genetics of SOV and determination of its pathogenicity in different host species.

Swine Diseases

An avian oncovirus mutant (SE 21Q1b) deficient in genomic RNA: biological and biochemical characterization.

We have isolated a nonconditional mutant of PR-RSV-E with unique properties. This virus (SE 21Q1b) is shed from a continuously growing culture of transformed quail cells. 21Q1b virions are unable to transform or replicate in other quail or chicken cells after exogenous infection, despite the fact that the viral particles contain normal envelope glycoproteins, internal structural proteins and RNA-dependent DNA polymerase. The lack of infectivity of 21Q1b virions is a consequence of the failure to package genomic 39S RNA. Instead, these virions contain a mixture of heterogenous-sized polyadenylated cellular RNAs and 4S RNA. Less than 1% of the encapsulated RNA is viral-specific, although in the 21Q1b-producing cells, amounts of 39S, 28S and 21S viral RNAs comparable to those in wild-type virus-infected cells are synthesized and function as mRNAs for the viral proteins. Thus 21Q1b can be considered an RNA packaging mutant. Superinfection of 21Q1b cells with either RAV-1 or PR-A leads to production of about 10% or more of the normal titer of superinfecting virus, but none of the 21Q1b genetic markers are rescued. After superinfection, the 21Q1b cells continue to synthesize 21Q1b particles containing cellular RNAs in the same amounts as before infection. Thus superinfection does not appear to "switch off" the aberrant packaging of cellular RNA, but allows packaging of the superinfecting RNA. One explanation for the phenotype of 21Q1b is that the genome is lacking a signal necessary for efficient genomic RNA packaging (but not for translation) and that the 21Q1b genome encodes a "packaging factor" with an altered specificity so that cellular RNAs are efficiently packaged. 21Q1b virions do contain RNA-dependent DNA polymerase which has normal endogenous synthetic activity. The cDNA product made in vitro from detergent-lysed 21Q1b virions hybridizes equally well to uninfected quail and 21Q1b-producing quail cell RNAs, with kinetics suggesting that the endogenous product consists of transcripts of cellular RNAs present in low amounts in the cells.

Avian Sarcoma Viruses