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Biology subjects

Mohammed, H.

Publications and source records attributed to Mohammed, H..

At least 19 recordsLinked to original sources

Efficacy of Flavobacterium spp. Vaccines in fish: A systematic review and meta-analysis

Flavobacterium species cause substantial economic losses in aquaculture, but no quantitative synthesis of vaccine efficacy across species, hosts, and platforms has been evaluated yet. This systematic review and meta-analysis aimed to evaluate the efficacy of vaccines against Flavobacterium infections in fish. We systematically searched PubMed, Web of Science, and Scopus for controlled challenge trials. The pooled risk ratio was calculated using a random effects model. Heterogeneity was assessed, and publication bias was evaluated by funnel plot and Egger's test. Sixty studies were included in this study, 59 of which were included in the main meta-analysis (377 comparisons) after screening. The overall pooled risk ratio was 0.572 (95% confidence interval: 0.55-0.60), corresponding to a relative percent survival of 42.8%, with high heterogeneity. Efficacy differed significantly by pathogen species, fish host, vaccine type and administration route. The highest protection by pathogen species was against F. davisii in channel catfish (relative percent survival = 86.8%), and the lowest against F. columnare in grass carp (relative percent survival = 30.6%). Live attenuated vaccines induced the highest protection, followed by inactivated and subunit vaccines. Among administration routes, immersion and oral vaccination achieved comparable protection, both outperforming injection. Significant publication bias was detected (P<0.001). Vaccination effectively reduces fish mortality from Flavobacterium infections, but its efficacy is highly context dependent. Taken together, standardized challenge protocols and improved reporting are needed. Priority should be given to developing effective vaccines against F. oreochromis and F. columnare.

microbiology↗

Nutrient-Sensing Nuclear Receptor PPARα Controls Liver Proteostasis

Peroxisome proliferator-activated receptor alpha (PPAR) is a nuclear receptor that orchestrates metabolic adaptation to fasting by regulating hepatic lipid and glucose metabolism. While these functions are well established, its role in protein homeostasis, another energy-intensive process, has remained unclear. Here, we performed multi-omics analyses in wild-type and PPAR knockout mice treated with the PPAR agonist fenofibrate to define its broader role in proteostasis. Interestingly, chronic PPAR activation suppressed hepatic secretory pathways, reducing secretome gene expression and circulating serum proteins, and downregulated genes involved in endoplasmic reticulum (ER) translocation, glycosylation, folding, and trafficking. Concurrently, PPAR activation enhanced proteasome activity, which was associated with selective induction of proteasome 26S subunit non-ATPase (PSMD) family members. In addition, hepatic protein synthesis was strongly attenuated. This was associated with an increase in the inhibitory phosphorylation of the eukaryotic translation initiation factor 2 (eIF2), that in turn was linked to disrupted iron homeostasis. Together, these findings identify PPAR as a regulator of proteostasis, suppressing protein synthesis and secretion while promoting protein degradation pathways. Beyond its canonical role in lipid and glucose metabolism, we conclude that PPAR exerts an additional energy-conserving function by coordinating proteostasis, expanding our understanding of its systemic metabolic role.

physiology↗

JAK2 signalling to HNRNPA1 represses retrotransposon activity in haematopoietic stem cells

Retrotransposon expression must be tightly controlled, particularly in long-lived multipotent stem cells, to prevent deleterious consequences including insertional mutations. Several mechanisms are known to repress retrotransposon transcription during development which are generally thought to persist thereafter. However, integration of retrotransposable elements into host genomes has also provided a major source of genetic variation across evolution. This has generated many sequences that have acquired advantageous host functions, but little is known about retrotransposon expression and mobility in adult stem cells or about how these processes might be dynamically regulated. Here we describe the landscape of somatic retrotransposition in haematopoietic stem cells and identify a previously unrecognised pathway which links cytokine signalling, RNA-modulating HNRNP complexes and repression of retrotransposon activity. Activation of JAK2, by thrombopoietin or gain-of-function JAK2 mutations, triggers tyrosine phosphorylation of HNRNPA1 that represses expression of ERVs, LINEs and SINEs and reduces insertional mutagenesis. This pathway coordinates retrotransposon activity with cellular context and state and provides a mechanism for protecting the haematopoietic stem cell genome.

cell biology↗

Methylation dynamics in the decades preceding acute myeloid leukaemia

DNA methylation is emerging as a highly sensitive and specific marker of cancer initiation and progression. How these cancer-specific methylation changes are established in the decades before cancer, however, remains largely unknown. Here, we use a unique collection of longitudinal blood samples collected annually up to 15 years prior to a diagnosis of acute myeloid leukaemia to sensitively track the dynamics of DNA methylation changes at high temporal resolution. We identify thousands of differentially methylated regions (DMRs) that exhibit altered patterns of methylation up to 10 years before acute myeloid leukaemia (AML) diagnosis. Most of these DMRs are strongly associated with expanding clones carrying somatic driver mutations. We identify a subset of epigenetic driver DMRs characterised by recurrent CpG alterations that are highly shared across pre-AML cases. These are likely to reflect early epigenetic reprogramming associated with AML development. We also reveal large numbers of stochastic passenger CpGs whose differential methylation results from hitch-hiking with clonal expansions driven by somatically acquired genetic events. These passenger CpGs can be exploited for lineage tracing to discover clonal expansions driven by missing driver mutations. Our findings show widespread changes in methylation patterns during the early stages of cancer development which could be utilised for risk prediction and therapeutic intervention.

genomics↗

Df-1 Cell Adaptation and Immune Responses of Lc-75 Vaccinal Strain of Infectious Bursal Disease Virus in Chicken

The current Infectious bursal disease virus (IBDV) vaccine strain of LC-75 in Ethiopia is being produced through chicken embryo fibro blast cell which has short lifespan and limited need of specific pathogen free eggs. Ideally, vaccine should have better longevity and being effective in cost and time. Experimental research was conducted to adopt DF-1 cell and to validate the immune responses, immunosuppressive effect and immunogenicity tests, of LC-75 vaccinal strain of Infections bursal diseases virus A total of 76 chickens were used for these experiments. The seroconversion rate of the vaccine were measured using haemaglutination inhibition (HI) test in the vaccinated two experiment groups, adapted IBDV and Newcastle vaccines at two weeks interval for the first group and only Newcastle vaccine for the second experiment groups. To perform the immunogenicity test, two groups having 20 chickens per group were used and samples of serum were taken on 0-, 7-, 14- and 28-days post vaccinations and subjected to indirect ELISA test. The group that received both vaccine types produced haemagglutination inhibition titer (HIT) of 97.33{+/-}22.49 whereas the other group that received only Newcastle vaccine produced 124{+/-}24.92. The control group always showed no detectable antibody while the vaccinated group was able to produce average antibody S/P values of 0.00 {+/-} 0.01 at day 0, 0.02{+/-} 0.01 at day 7, 1.05{+/-}0.10 at day 14 and 0.83{+/-}0.05 at day 28. RT-PCR using a 400 bp IBDV viral protein 2(VP2) specific primer resulted from positive bands in all samples. In conclusion, the vaccinal strain was able to replicate and adapt on the DF-1 cells and it was found to be immunogenic as well as less immunosuppressive.

microbiology↗

Mitochondrial-nuclear variation for metabolic plasticity with potential consequences for invasion success in New Zealand mud snails

Metabolic rate is an emergent organismal trait that integrates energetic costs of living and influences species distributions and response to climate change. For ectotherms, metabolic rate is likely shaped by interactions between mitochondrial and nuclear genomes and environmental temperature. Variation in reproductive mode (e.g., asexual vs. sexual reproduction) can enhance or interfere with cross-generational transmission of these interactions, with implications for evolutionary responses to selection on standing genetic variation for metabolism-related traits. We leveraged known patterns of mitochondrial-nuclear discordance in a global invader, the snail Potamopyrgus antipodarum, to measure thermal plasticity of metabolic rate in invasive vs. native asexual lineages that combined multiple mitochondrial haplotypes with nuclear genomic variation from distinct lake populations. Native lineages harbored significant mitochondrial-nuclear variation for metabolic plasticity, with some genotypes maintaining low metabolic rates at high temperature. Invasive lineages contained only a small subset of this variation, with non-plastic and lower metabolic rates relative to native lineages at high temperature. Together, these data indicate that mitochondrial-nuclear-environment interactions contribute to variation in the metabolic rate of asexual lineages. Our results also demonstrate that invasive lineages have metabolic phenotypes that could facilitate successful colonization of aquatic habitats via decreased maintenance metabolism under high temperatures.

ecology↗

The transcriptional and epigenetic reprogramming mediated by chronic IL1β exposure drives self-renewal ability and myeloid priming in TET2 deficient stem and progenitor cells.

Clonal hematopoiesis (CH) increases the risk for the development of hematological malignancy and cardiovascular disease. IL1{beta} is elevated in patients with CH and its inhibition mitigates cardiovascular risk in murine models with Tet2 loss-of-function. How IL1{beta} alters population dynamics of hematopoietic cells upon Tet2 deletion (Tet2-KO) is not well understood. We demonstrated IL1{beta} expands Tet2-KO monocytes/macrophages, and long-term hematopoietic stem cells. IL1{beta} promoted myeloid bias over other lineages of Tet2-KO HSPCs coinciding with the failure to demethylate lineage-associated enhancer and transcription factor binding sites. IL1{beta} enhanced the self-renewal ability of Tet2-KO HSPCs by upregulating genes associated with self-renewal and by resisting the demethylation of binding sites of transcription factors promoting terminal differentiation. The IL1{beta}-mediated premalignant phenotype is suppressed by the IL1{beta} antagonist or deletion of the IL1 receptor-1, in vivo in aged mice. Our results demonstrate that targeting IL1 signaling could be an efficient early intervention strategy in preleukemic disorders. STATEMENT OF SIGNIFICANCEIL1{beta} promoted myeloid expansion and self-renewal capacity of TET2-null pre-leukemic cells. Lineage bias occurred early within progenitors towards pro-inflammatory macrophages. Genes specific to aging and with roles in promoting self-renewal capacity, and myeloid bias were upregulated. Hypermethylation occurred within lymphoid and erythroid lineage-specific regulatory elements. Targeting IL1R1 reduced aberrant myeloid bias and premalignant phenotype.

cancer biology↗

Low HER2 enables dedifferentiation and transformation of normal breast epithelial cells via chromatin opening

Overexpression of the human epidermal growth factor 2 (HER2) protein in breast cancer patients is a predictor of poor prognosis and resistance to therapies. Despite significant advances in the development of targeted therapies and improvements in the 5-year survival rate of metastatic HER2-positive breast cancer patients, a better understanding of the disease at an early stage is needed to prevent its progression. Here, we used an inducible breast cancer transformation system that allows investigation of early molecular changes at high temporal resolution. HER2 overexpression to similar levels as those observed in a subtype of HER2 positive breast cancer patients induced transformation of MCF10A cells and resulted in gross morphological changes, increased anchorage-independent growth of cells, and altered transcriptional programme of genes associated with oncogenic transformation. Global phosphoproteomic analysis during the first few hours of HER2 induction predominantly detected an increase in protein phosphorylation. Intriguingly, this correlated with a wave of chromatin opening, as measured by ATAC-seq on acini isolated from 3D cell culture. We observed that HER2 overexpression leads to reprogramming of many distal regulatory regions and promotes reprogramming-associated heterogeneity. We found that a subset of cells acquired a dedifferentiated breast stem-like phenotype, making them likely candidates for malignant transformation. Our data show that this population of cells, which counterintuitively enriches for relatively low HER2 protein abundance and increased chromatin accessibility, possesses transformational drive, resulting in increased anchorage-independent growth in vitro compared to cells not displaying a stem-like phenotype. Our data provide a discovery platform for signalling to chromatin pathways in HER2-driven cancers, offering an opportunity for biomarker discovery and identification of novel drug targets.

cancer biology↗

A Distinct Chromatin State Drives Therapeutic Resistance in Invasive Lobular Breast Cancer

Most invasive lobular breast cancers (ILC) are of the luminal A subtype and strongly hormone receptor positive. Yet, they are relatively resistant to tamoxifen and are associated with inferior long-term outcomes compared to invasive ductal cancers (IDC). In this study, we sought to gain mechanistic insights into these clinical findings that are not explained by the genetic landscape of ILC and to identify strategies to improve patient outcomes. Through a comprehensive analysis of the epigenome of ILC in pre-clinical models and clinical samples we found that compared to IDC, ILC has a distinct chromatin state that is linked to gained recruitment of FOXA1, a lineage-defining pioneer transcription factor. This results in an ILC-unique FOXA1-estrogen receptor (ER) axis that promotes the transcription of genes associated with tumor progression and poor outcomes. The ILC-unique FOXA1-ER axis leads to retained ER chromatin binding after tamoxifen treatment thereby facilitating tamoxifen resistance while remaining strongly dependent on ER signaling. Mechanistically, gained FOXA1 binding was associated with the auto-induction of FOXA1 in ILC through an ILC-unique FOXA1 binding site. Targeted silencing of this regulatory site resulted in the disruption of the feed-forward loop and growth inhibition in ILC. In summary, we show that ILC is characterized by a unique cell state and FOXA1-ER axis that dictate tumor progression and offer a novel mechanism of tamoxifen resistance. These results underscore the importance of conducting clinical trials dedicated to patients with ILC to optimize endocrine treatments in this breast cancer subtype.

cancer biology↗

Aging alters the metabolic flux signature of the ER unfolded protein response in vivo in mice

Age is a risk factor for numerous diseases, including neurodegenerative diseases, cancers, and diabetes. Loss of protein homeostasis is a central hallmark of aging. Activation of the endoplasmic reticulum unfolded protein response (UPRER) includes changes in protein translation and membrane lipid synthesis. Using stable isotope labeling, a "signature" of the UPRER in vivo in mouse liver was developed by inducing ER stress and measuring rates of both proteome-wide translation and de novo lipogenesis. Several changes in protein synthesis across ontologies were noted with age, including a more dramatic suppression of translation under ER stress in aged mice as compared to young mice. Binding immunoglobulin protein (BiP) synthesis rates and mRNA levels were increased more in aged than young mice. De novo lipogenesis rates decreased under ER stress conditions in aged mice, including both triglyceride and phospholipid fractions. In young mice, only a significant reduction was seen in the triglyceride fraction. These data indicate that aged mice have an exaggerated response to ER stress, which may indicate that the aging renders the UPRER less effective in resolving proteotoxic stress.

physiology↗

Metabolic flux signatures of the ER unfolded protein response in vivo reveal decreased hepatic de novo lipogenesis and mobilization of lipids from adipose tissue to liver

The unfolded protein response in the endoplasmic reticulum (UPRER) is involved in a number of metabolic diseases, including non-alcoholic fatty liver disease. Here, we characterize the UPRER induced metabolic changes in mouse liver through in vivo metabolic labeling and mass spectrometric analysis of proteome and lipid fluxes. We induced ER stress in vivo via tunicamycin treatment and measured rates of proteome-wide protein synthesis, de novo lipogenesis and cholesterol synthesis serially over a three-day period, thereby generating a metabolic "signature" of the UPRER over time. Synthesis of most proteins was suppressed under ER stress conditions, including proteins involved in lipogenesis, consistent with reduced de novo lipogenesis at 48 and 72 hours. Electron microscopy revealed striking morphological changes to ER and H&E staining showed lipid droplet enriched livers under ER stress. Pre-labeling of adipose tissue prior to ER stress induction revealed mobilization of lipids from adipose to the liver. Interestingly, the source of these lipids was uptake of free fatty acids, not whole triglycerides or phospholipids from lipoproteins, as demonstrated by replacement of the triglyceride-glycerol moiety in liver concurrently with increased incorporation of labeled palmitate from adipose. We also induced ER stress by a high-fat diet and observed similar metabolic flux signatures, suggesting that this mechanism may play a role in the progression of fatty liver disease. This flux-based approach provides a powerful tool to identify novel regulators of ER stress and potential targets for pharmacological intervention.

physiology↗

Temporal regulation of motor behavior on a modified forelimb dexterity test in mice

Hand and arm manual dexterity is a hallmark of humans and non-human primates. While rodents are less dexterous than primates, they provide powerful models for testing neural circuit function in behavioral output, including dexterous behaviors. In rodents, the single pellet reach task has been used extensively to study both dexterous forelimb motor learning as well as recovery from injury; however, mice exhibit high variability in task acquisition in comparison to rats and a significant percentage fail to learn the task. We have created a recessed version of the task that requires greater dexterity. This subtle modification increases both task difficulty as well as the proportion of mice that show an improvement with training. Furthermore, motor cortex inactivation shows a greater effect on the execution of the recessed forelimb reach task, with distinct effects on reach targeting vs grasping components depending on the timing of inhibitory activation. Kinematic analysis revealed differences in reach targeting upon transient cortical inhibition prior to reach onset. In summary, the recessed single pellet reach task provides a robust assessment of forelimb dexterity in mice and a tool for studying skilled motor acquisition and execution.

neuroscience↗

Applying Machine Learning Technology in the Prediction of Crop Infestation with Cotton Leafworm in Greenhouse

The use of technology in agriculture has grown in recent years with the era of data analytics affecting every industry. The main challenge in using technology in agriculture is identification of effectiveness of big data analytics algorithms and their application methods. Pest management is one of the most important problems facing farmers. The cotton leafworm, Spodoptera littoralis (Boisd.) (CLW) is one of the major polyphagous key pests attacking plants includes 73 species recorded at Egypt. In the present study, several machine learning algorithms have been implemented to predict plant infestation with CLW. The moth of CLW data was weekly collected for two years in a commercial hydroponic greenhouse. Furthermore, among other features temperature and relative humidity were recorded over the total period of the study. It was proven that the XGBoost algorithm is the most effective algorithm applied in this study. Prediction accuracy of 84 % has been achieved using this algorithm. The impact of environmental features on the prediction accuracy was compared with each other to ensure a complete dataset for future results. In conclusion, the present study provided a framework for applying machine learning in the prediction of plant infestation with the CLW in the greenhouses. Based on this framework, further studies with continuous measurements are warranted to achieve greater accuracy.

bioinformatics↗

ASXL1 Directs Neutrophilic Differentiation via Modulation of MYC and RNA Polymerase II.

Mutations in the gene Additional Sex-Combs Like 1 (ASXL1) are recurrent in myeloid malignancies as well as the pre-malignant condition clonal hematopoiesis, where they are universally associated with poor prognosis. An epigenetic regulator, ASXL1 canonically directs the deposition of H3K27me3 via the polycomb repressive complex 2. However, its precise role in myeloid lineage maturation is incompletely described. We utilized single cell RNA sequencing (scRNA-seq) on a murine model of hematopoietic-specific ASXL1 deletion and identified a specific role for ASXL1 in terminal granulocyte maturation. Terminal maturation is accompanied by down regulation of Myc expression and cell cycle exit. ASXL1 deletion leads to hyperactivation of Myc in granulocyte precursors and a quantitative decrease in neutrophil production. This failure of normal developmentallyassociated Myc suppression is not accompanied by significant changes in the landscape of covalent histone modifications including H3K27me3. Examining the genome-wide localization of ASXL1 in myeloid progenitors revealed strong co-localization with RNA Polymerase II (RNAPII) at the promoters and spread across the gene bodies of transcriptionally active genes. ASXL1 deletion results in a decrease in RNAPII promoter-proximal pausing in granulocyte progenitors, indicative of a global increase in productive transcription, consistent with the known role of ASXL1 as a mediator of RNAPII pause release. These results suggest that ASXL1 inhibits productive transcription in granulocyte progenitors, identifying a new role for this epigenetic regulator and highlighting a novel potential oncogenic mechanism for ASXL1 mutations in myeloid malignancies.

cancer biology↗

Somatosensory Cortex of Macaque Monkeys is Designed for Opposable Thumb

The evolution of opposable thumb has enabled fine grasping ability and precision grip, which led to the capacity for fine manipulation of objects and refined tool use. Since tactile inputs to an opposable thumb are often spatially and temporally out of synch with inputs from the fingers, we hypothesized that inputs from the opposable thumb would be processed in an independent module in the primary somatosensory cortex (area 3b). Here we show that in area 3b of macaque monkeys, most neurons in the thumb representation do not respond to tactile stimulation of other digits and receive few intrinsic cortical inputs from other digits. However, neurons in the representations of other digits respond to touch on any of the four digits and are significantly more interconnected in the cortex. The thumb inputs are thus processed in an independent module, whereas there is significantly more inter-digital information exchange between the other digits. This cortical organization reflects behavioral use of the hand with an opposable thumb.

neuroscience↗

Single cell multi-omics profiling reveals a hierarchical epigenetic landscape during mammalian germ layer specification

Formation of the three primary germ layers during gastrulation is an essential step in the establishment of the vertebrate body plan. Recent studies employing single cell RNA-sequencing have identified major transcriptional changes associated with germ layer specification. Global epigenetic reprogramming accompanies these changes, but the role of the epigenome in regulating early cell fate choice remains unresolved, and the coordination between different epigenetic layers is unclear. Here we describe the first single cell triple-omics map of chromatin accessibility, DNA methylation and RNA expression during the exit from pluripotency and the onset of gastrulation in mouse embryos. We find dynamic dependencies between the different molecular layers, with evidence for distinct modes of epigenetic regulation. The initial exit from pluripotency coincides with the establishment of a global repressive epigenetic landscape, followed by the emergence of local lineage-specific epigenetic patterns during gastrulation. Notably, cells committed to mesoderm and endoderm undergo widespread coordinated epigenetic rearrangements, driven by loss of methylation in enhancer marks and a concomitant increase of chromatin accessibility. In striking contrast, the epigenetic landscape of ectodermal cells is already established in the early epiblast. Hence, regulatory elements associated with each germ layer are either epigenetically primed or epigenetically remodelled prior to overt cell fate decisions during gastrulation, providing the molecular logic for a hierarchical emergence of the primary germ layers.\n\nHighlightsO_LIFirst map of mouse gastrulation using comprehensive single cell triple-omic analysis.\nC_LIO_LIExit from pluripotency is associated with a global repressive epigenetic landscape, driven by a sharp gain of DNA methylation and a gradual decrease of chromatin accessibility.\nC_LIO_LIDNA methylation and chromatin accessibility changes in enhancers, but not in promoters, are associated with germ layer formation.\nC_LIO_LIMesoderm and endoderm enhancers become open and demethylated upon lineage commitment.\nC_LIO_LIEctoderm enhancers are primed in the early epiblast and protected from the global repressive dynamics, supporting a default model of ectoderm commitment in vivo.\nC_LI

developmental biology↗

Lamina and Heterochromatin Direct Chromosome Organisation in Senescence and Progeria

Lamina-associated domains (LADs) cover a large part of the human genome and are thought to play a major role in shaping the nuclear architectural landscape. Here, we use simulations based on concepts from polymer physics to dissect the roles played by heterochromatin- and lamina-mediated interactions in nuclear organisation. Our model explains the conventional organisation of heterochromatin and euchromatin in growing cells, as well as the pathological organisation found in oncogene-induced senescence and progeria. We show that the experimentally observed changes in the locality of contacts in senescent and progeroid cells can be explained naturally as arising due to phase transitions in the system. Our model predicts that LADs are highly stochastic, and that, once established, the senescent phenotype should be metastable even if lamina-mediated interactions were reinstated. Overall, our simulations uncover a universal physical mechanism that can regulate heterochromatin segregation and LAD formation in a wide range of mammalian nuclei.

biophysics↗

Single-cell transcriptome analysis of human, marmoset and mouse embryos reveals common and divergent features of preimplantation development

The mouse embryo is the canonical model for mammalian preimplantation development. Recent advances in single-cell profiling allow detailed analysis of embryogenesis in other eutherian species, including human, to distinguish conserved from divergent regulatory programs and signalling pathways in the rodent paradigm. Here, we identify and compare transcriptional features of human, marmoset and mouse embryos by single-cell RNA-seq. Zygotic genome activation correlates with the presence of Polycomb Repressive Complexes in all three species, while ribosome biogenesis emerges as a predominant attribute in primate embryos, supporting prolonged translation of maternally deposited RNAs. We find that transposable element expression signatures are species-, stage- and lineage-specific. The pluripotency network in the primate epiblast lacks certain regulators operative in mouse, but encompasses WNT components and genes associated with trophoblast specification. Sequential activation of GATA6, SOX17 and GATA4 markers of primitive endoderm identity is conserved in primates. Unexpectedly, OTX2 is also associated with primitive endoderm specification in human and nonhuman primate blastocysts. Our cross-species analysis demarcates both conserved and primate-specific features of preimplantation development and underscores the molecular adaptability of early mammalian embryogenesis.

developmental biology↗