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We demonstrate that simple, non-invasive environmental DNA (eDNA) methods can detect transgenes of genetically modified (GM) animals from terrestrial and aquatic sources in invertebrate and vertebrate systems. We detected transgenic fragments between 82–234 bp through targeted PCR amplification of environmental DNA extracted from food media of GM fruit flies ( Drosophila melanogaster ), feces, urine, and saliva of GM laboratory mice ( Mus musculus ), and aquarium water of GM tetra fish ( Gymnocorymbus ternetzi ). With rapidly growing accessibility of genome-editing technologies such as CRISPR, the prevalence and diversity of GM animals will increase dramatically. GM animals have already been released into the wild with more releases planned in the future. eDNA methods have the potential to address the critical need for sensitive, accurate, and cost-effective detection and monitoring of GM animals and their transgenes in nature.

The lasting effects of neuronal activity on brain development involve calcium-dependent gene expression. Using a strategy called transactivator trap, we cloned a calcium-responsive transactivator called CREST (for calcium-responsive transactivator). CREST is a SYT-related nuclear protein that interacts with adenosine 3',5'-monophosphate (cAMP) response element-binding protein (CREB)-binding protein (CBP) and is expressed in the developing brain. Mice that have a targeted disruption of the crest gene are viable but display defects in cortical and hippocampal dendrite development. Cortical neurons from crest mutant mice are compromised in calcium-dependent dendritic growth. Thus, calcium activation of CREST-mediated transcription helps regulate neuronal morphogenesis.

Vascular permeability plays a key role in a wide array of life-threatening and sight-threatening diseases. Vascular endothelial growth factor can increase vascular permeability. Using a model system for nonproliferative diabetic retinopathy, we found that pigment epithelium-derived factor (PEDF) effectively abated vascular endothelial growth factor-induced vascular permeability. A 44-amino acid region of PEDF was sufficient to confer the antivasopermeability activity. Additionally, we identified four amino acids (glutamate-101, isoleucine-103, leucine-112, and serine-115) critical for this activity. PEDF, or a derivative, could potentially abate or restore vision loss from diabetic macular edema. Furthermore, PEDF may represent a superior therapeutic approach to sepsis-associated hypotension, nephrotic syndrome, and other sight-threatening and life-threatening diseases resulting from excessive vascular permeability.

This study examines the mechanism of mutually exclusive expression of the human X-linked red and green visual pigment genes in their respective cone photoreceptors by asking whether this expression pattern can be produced in a mammal that normally carries only a single X-linked visual pigment gene. To address this question, we generated transgenic mice that carry a single copy of a minimal human X chromosome visual pigment gene array in which the red and green pigment gene transcription units were replaced, respectively, by alkaline phosphatase and β -galactosidase reporters. As determined by histochemical staining, the reporters are expressed exclusively in cone photoreceptor cells. In 20 transgenic mice carrying any one of three independent transgene insertion events, an average of 63% of expressing cones have alkaline phosphatase activity, 10% have β -galactosidase activity, and 27% have activity for both reporters. Thus, mutually exclusive expression of red and green pigment transgenes can be achieved in a large fraction of cones in a dichromat mammal, suggesting a facile evolutionary path for the development of trichromacy after visual pigment gene duplication. These observations are consistent with a model of visual pigment expression in which stochastic pairing occurs between a locus control region and either the red or the green pigment gene promotor.

Disclosure: Y. Lin: None. E. Brule: None. M. Cowan: None. U. Boehm: None. D.J. Bernard: None. Loss of inhibin negative feedback in the pituitary leads to enhanced ovulation but pregnancy failure in mice Follicle-stimulating hormone (FSH) is an essential regulator of gonadal function, particularly in females. Inhibins are TGFβ family ligands made in the gonads that suppress FSH synthesis. Inhibins require a co-receptor, betaglycan or TGFBR3L, to mediate their actions in pituitary gonadotrope cells. Female mice with a gonadotrope-specific knockout of betaglycan or global deletion of Tgfbr3l exhibit increased ovarian follicle development, numbers of ovulated eggs, and litter sizes compared to controls. Females with both co-receptors knocked out (hereafter dKO) show dramatic increases in FSH levels, numbers of antral follicles and corpora lutea, serum progesterone levels, and ovarian aromatase expression. They ovulate 3-4 times as many eggs in natural cycles compared to control females. dKO females can become pregnant and show an increased number of implanted embryos at 7.5 days post coitum (7.5 dpc). Nevertheless, dKO females do not give birth to live offspring. By 10.5 dpc, the weight of the fetoplacental unit is decreased in dKO females, and many embryos display morphological abnormalities. By 14.5 dpc, most embryos in dKO females are either dead or resorbing. Wild-type surrogates give birth to live young following transplantation of embryos from control or dKO females. Conversely, control but not dKO females carry wild-type embryos to term. These data suggest that the maternal environment in dKO mice cannot support full-term pregnancies. Based on the hormonal profile of the cycling females, we suspected a deleterious effect of elevated estrogens. Consistent with this idea, treatment with the aromatase inhibitor anastrozole increased fetal survival in some dKO mice, suggesting a role for estrogens in embryo death. We are currently more thoroughly characterizing the maternal hormonal environment throughout gestation and investigating placental structure/function to gain more insight into the precise nature of the pregnancy failure. Our results will show how loss of inhibin action in the pituitary impede embryo survival and whether pregnancy loss is linked to increases in FSH. Presentation: Friday, June 16, 2023

The two Jaenisch laboratory studies published in Cell in 2013 were ground-breaking, demonstrating for the first time proof of principle CRISPR mediated gene editing in the mouse zygote to generate knockout and conditional alleles, and caused much excitement in the transgenic mouse community. [...]our study is not the first time concerns have been raised as to the efficiency of the 2-guides 2-oligo method, with anecdotal reports from others in the transgenic community (Science; 2016. doi:https://doi.org/10.1126/science.aal0334 [doi.org]), which stated that “What was disappointing is none of us could reproduce at the efficiencies reported by Jaenisch. Because efficiencies at different genomic loci often vary highly (which the Yang et al. authors state in their paragraph below point #3), it would be ideal to gather such side-by-side data for at least 6 to 10 loci or more to ensure reproducibility. [...]our observations call into question the robustness of the approach and its suitability for widespread use. Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, AV Hill Building, Oxford Road, Manchester, M13 9PT, UK David Brough & Catherine B. Lawrence 13.

The authors implemented a PCR protocol to rapidly screen for Pasteurella pneumotropica and to accurately identify contaminated laboratory mice in a clinical setting. This protocol was implemented in response to a severe outbreak of P. pneumotropica in their animal facility. Although a sentinel program was in place to routinely screen for P. pneumotropica , it was inadequate for the identification of contaminated animals. As a result, several additional strains of mice were contaminated and developed clinical signs of infection. The authors implemented a screening method using PCR with reported primer pairs previously developed to identify the biotype isolates of P. pneumotropica in laboratory mice. Throat culture swabs were collected from live mice and placed in a bacterial culture. The DNA from these cultures was isolated and screened by PCR. This procedure enabled the authors to eliminate P. pneumotropica from several animal housing rooms. The assay can be easily applied in most animal facilities.

CRISPR Cas9 gene editing technology has considerably facilitated the generation of mouse knockout alleles, relieving many of the cumbersome and time-consuming steps of traditional mouse embryonic stem cell technology. However, the generation of conditional knockout alleles remains an important challenge. An earlier study reported up to 16% efficiency in generating conditional knockout alleles in mice using 2 single guide RNAs (sgRNA) and 2 single-stranded oligonucleotides (ssODN) (2sgRNA 2ssODN). We re-evaluated this method from a large data set generated from a consortium consisting of 17 transgenic core facilities or laboratories or programs across the world. The dataset constituted 17,887 microinjected or electroporated zygotes and 1,718 live born mice, of which only 15 (0.87%) mice harbored 2 correct LoxP insertions in cis configuration indicating a very low efficiency of the method. To determine the factors required to successfully generate conditional alleles using the 2sgRNA 2ssODN approach, we performed a generalized linear regression model. We show that factors such as the concentration of the sgRNA, Cas9 protein or the distance between the placement of LoxP insertions were not predictive for the success of this technique. The major predictor affecting the method's success was the probability of simultaneously inserting intact proximal and distal LoxP sequences, without the loss of the DNA segment between the two sgRNA cleavage sites. Our analysis of a large data set indicates that the 2sgRNA 2ssODN method generates a large number of undesired alleles (>99%), and a very small number of desired alleles (<1%) requiring, on average 1,192 zygotes.

IntroductionNeonatal death and later disability remain common sequelae of hypoxic-ischaemic encephalopathy (HIE) despite the now standard use of therapeutic hypothermia (HT). New therapeutic approaches to brain protection are required. Melatonin is an indolamine hormone with free-radical scavenging, antiapoptotic, anti-inflammatory and gene regulatory neuroprotective properties, which has extensive preclinical evidence of safety and efficacy. Pharmacokinetic (PK) data suggest it is necessary to reach melatonin levels of 15–30 mg/L within 6–8 hours of hypoxia-ischaemia for brain protection. We developed a novel Good Manufacturing Practice (GMP) grade melatonin in ethanol 50 mg/mL solution for intravenous use. In preclinical studies, ethanol is an adjuvant excipient with additional neuroprotective benefit; optimised dosing protocols can achieve therapeutic melatonin levels while limiting blood alcohol concentrations (BACs).Methods and analysisThe Acute High Dose Melatonin for Encephalopathy of the Newborn (ACUMEN) Study is a first-in-human, international, multicentre, phase 1 safety study of intravenous melatonin in babies with moderate/severe HIE receiving HT. Sixty babies will be studied over two phases: a dose escalation study including four dose levels to establish the recommended phase 2 dose (RP2D), followed by a 6-month cohort expansion study of RP2D to further characterise PKs and affirm safety. Participants will receive a 2-hour intravenous infusion of melatonin within 6 hours of birth, followed by five maintenance doses every 12 hours to cover the period of HT. Plasma melatonin and BACs will be monitored. The RP2D will be based on the attainment of therapeutic melatonin levels while limiting BACs and the frequency of dose-limiting events (DLEs). A Bayesian Escalation with Overdose Control approach will be used to estimate the risk of DLE per dose level, with a target level of <33%. ACUMEN will establish a network of centres with standardised neurocritical care and harmonised MRI systems for the analysis of the primary outcome—magnetic resonance spectroscopy (MRS) lactate to N-acetylaspartate peak area ratio localised to the basal ganglia and thalamus and include a nested blood biomarker study to explore early disease severity indicators.Ethics and disseminationApproval has been given by the London Central National Health Service Health Research Authority Ethics Committee (25/LO/0170) and UK Clinical Trials Authorisation from the Medicines and Healthcare products Regulatory Agency. Separate approvals have been sought in Ireland and Australia. Dissemination will be via peer-reviewed journals, conference presentations, public registries and plain language summaries for parent/legal guardian(s), in accordance with national requirements.Trial registration number ISRCTN61218504. EU CT: 2025-520538-49-00.Protocol versionPublication based on the UK protocol V.3.0, 08 May 2025