Outer Cell Layers Research Articles

Enhanced Photovoltaic Efficiency through 3D-Printed COC/Al₂O₃ Anti-Reflective Coversheets

In the past few years, there has been a considerable growth in the utilization of solar cells to produce electrical power to fulfil the growing worldwide energy demands. An optical loss is a crucial factor that impacts the performance of the photovoltaic conversion process. This loss occurs when incoming sunlight is reflected back on the outer layer of the photovoltaic cells. The application of antireflective materials on the photovoltaic substrates can enhance the absorption of sunlight and minimize the reflection. Currently, there is no ideal anti-reflective coating for solar cells that can allow the transmission of sunlight without any reflection. In this research, a transparent cyclic-olefin-copolymer (COC) was used to fabricate anti-reflection (AR) coversheet by fused deposition modelling process (3D printing). Further, the aluminium oxide Al2O3 powder was added at the proportions of 1wt%, 2wt%, 3wt%, and 4wt% to the COC polymer to increase the anti-reflection characteristics. The structural, morphological, mechanical (tear strength), electrical and temperature characteristics were studied. The performance of COC with aluminium oxide (COCA) coversheets was evaluated, and the findings revealed a considerable increment in power conversion efficiency (PCE) of 17.21% (sunlight exposure) and 18.34% (neodymium light) for COCA3 coversheets. As seen, the COCA3 sample exhibit lower electrical resistance of 3.88 ×10-3 Ω cm, carrier concentration (36.91×1020 cm-3) and higher hall mobility (13.67 cm2/Vs). The findings from the investigations demonstrated that the utilization of COC with Al2O3 powder (COCA) can be a suitable antireflective coversheet material for boosting the performance of polycrystalline silicon photovoltaic cells.

A dynamic WUSCHEL/Layer 1 interplay directs shoot apical meristem formation during regeneration in tobacco.

De novo shoot apical meristem (SAM) organogenesis during regeneration in tissue culture has been investigated for several decades, but the precise mechanisms governing early-stage cell fate specification remain elusive. In contrast to SAM establishment during embryogenesis, in vitro SAM formation occurs without positional cues and is characterized by autonomous initiation of cellular patterning. Here, we report on the initial stages of SAM organogenesis and on the molecular mechanisms that orchestrate gene patterning to establish SAM homeostasis. We found that SAM organogenesis in tobacco calli starts with protuberance formation followed by the formation of an intact L1 layer covering the nascent protuberance. We also exposed a complex interdependent relationship between L1 and WUS expression and revealed that any disruption in this interplay compromises shoot formation. Silencing WUS in nascent protuberances prevented L1 formation and caused the disorganization of the outer cell layers exhibiting both anticlinal and periclinal divisions, suggesting WUS plays a critical role in the proper establishment and organization of L1 during SAM organogenesis. We further discovered that silencing TONNEAU1 prevents the exclusive occurrence of anticlinal divisions in the outermost layer of the protuberances and suppresses the acquisition of L1 cellular identity and L1 formation, ultimately impeding SAM formation and regeneration. This study provides a novel molecular framework for the characterization of a WUS/L1 interplay that mediates SAM formation during regeneration.

Modulating the biosynthesis and TLR4-interaction of lipopolysaccharide as an approach to counter gut dysbiosis and Parkinson's disease: Role of phyto-compounds

The prevalence of the world's second leading neurodegenerative disorder Parkinson's disease (PD) is well known while its pathogenesis is still a topical issue to explore. Clinical and experimental reports suggest the prevalence of disturbed gut microflora in PD subjects, with an abundance of especially Gram-negative bacteria. The endotoxin lipopolysaccharide (LPS) released from the outer cell layer of these bacteria interacts with the toll-like receptor 4 (TLR4) present on the macrophages and it stimulates the downstream inflammatory cascade in both the gut and brain. Recent research also suggests a positive correlation between LPS, alpha-synuclein, and TLR4 levels, which indicates the contribution of a parallel LPS-alpha-synuclein-TLR4 axis in stimulating inflammation and neurodegeneration in the gut and brain, establishing a body-first type of PD. However, owing to the novelty of this paradigm, further investigation is mandatory. Modulating LPS biosynthesis and LPS-TLR4 interaction can ameliorate gut dysbiosis and PD. Several synthetic LpxC (UDP-3-O-(R-3-hydroxymyristoyl)-N-acetylglucosamine deacetylase; LPS-synthesizing enzyme) inhibitors and TLR4 antagonists are reported to show beneficial effects including neuroprotection in PD models, however, are not devoid of side effects. Plant-derived compounds have been long documented for their benefits as nutraceuticals and thus to search for effective, safer, and multitarget therapeutics, the present study focused on summarizing the evidence reporting the potential of phyto-compounds as LpxC inhibitors and TLR4 antagonists. Studies demonstrating the dual potential of phyto-compounds as the modulators of LpxC and TLR4 have not yet been reported. Also, very few preliminary studies have reported LpxC inhibition by phyto-compounds. Nevertheless, remarkable neuroprotection along with TLR4 antagonism has been shown by curcumin and juglanin in PD models. The present review thus provides a wide look at the research progressed to date in discovering phyto-compounds that can serve as LpxC inhibitors and TLR4 antagonists. The study further recommends the need for expanding the search for potential candidates that can render dual protection by inhibiting both the biosynthesis and TLR4 interaction of LPS. Such multitarget therapeutic intervention is believed to bring fruitful yields in countering gut dysbiosis, neuroinflammation, and dopaminergic neuron damage in PD patients through a single treatment paradigm.

Expanding the spectrum of low-grade sinonasal adenocarcinoma with biphasic seromucinous differentiation and activating HRAS/AKT1 mutations.

Low-grade non-intestinal-type sinonasal adenocarcinoma (LGSNAC) is a rare heterogeneous and poorly characterised group of tumours, distinct from intestinal- and salivary-type neoplasms. Therefore, further characterisation is needed for clearer biological understanding and classification. Clinical, histological and molecular characterisation of four cases of biphasic, low-grade adenocarcinomas of the sinonasal tract was performed. All patients were male, aged between 48 and 78 years, who presented with polypoid masses in the nasal cavity. Microscopically, virtually all tumours were dominated by tubulo-glandular biphasic patterns, microcystic, focal (micro)papillary, oncocytic or basaloid features. Immunohistochemical staining confirmed biphasic differentiation with an outer layer of myoepithelial cells. Molecular profiling revealed HRAS (p.G13R, p.Q61R) mutations, and concomitant AKT1 (p.E17K, p.Q79R) mutations in two cases. Two cases showed potential in-situ/precursor lesions adjacent to the tumour. Follow-up periods ranged from 1 to 30 months, with one case relapsing locally after 12 and > 20 years. This study further corroborates a distinct biphasic low-grade neoplasm of the sinonasal tract with seromucinous differentiation. Although morphological and molecular features overlap with salivary gland epithelial-myoepithelial carcinoma, several arguments favour categorising these tumours within the spectrum of LGSNAC.

A histological and immunohistochemical investigation to assess the therapeutic role of metformin nanoemulsion against metformin in a diabetic retinopathy model

ABSTRACT The fundamental concept of diabetes research is the restoration of normal glycemic status. Nowadays, nanoemulsion medication delivery technologies provide effective approaches to the second type of diabetes mellitus care. This study aimed to investigate the potential of metformin nanoemulsion (MTF-NE) in treating streptozotocin (STZ)-induced diabetic retinopathy in rats. Histopathological examinations, including hematoxylin and eosin, anti-F-actin, anti-CD57, and anti-S100 immunostains, were performed after 8 weeks. Many alterations in the STZ group as slight disorganization of retinal layers, loss of some photoreceptor processes, and focal widening of intercellular spaces between small darkly stained nuclear cells in inner and outer nuclear layers, focal areas of disruption of outer plexiform layer, pyknotic nuclei of ganglion cells, and dilated congested blood capillaries with vascular leakage in the ganglion cell layer, decreased F-actin, increased CD75 and S100 immunohistochemical expression. Rats treated with metformin nanoemulsion have substantial improvements in retinal organization, histopathology, and immunohistochemical markers compared to those treated with metformin. The study suggests that metformin nanoemulsion holds promise for alleviating diabetic retinopathy in rats on a histological and immunohistochemical basis.

Conditional Knockouts of Interphotoreceptor Retinoid Binding Protein Suggest Two Independent Mechanisms for Retinal Degeneration and Myopia.

Interphotoreceptor retinoid-binding protein's (IRBP) role in eye growth and its involvement in cell homeostasis remain poorly understood. One hypothesis proposes early conditional deletion of the IRBP gene could lead to a myopic response with retinal degeneration, whereas late conditional deletion (after eye size is determined) could cause retinal degeneration without myopia. Here, we sought to understand if prior myopia was required for subsequent retinal degeneration in the absence of IRBP. This study investigates if any cell type or developmental stage is more important in myopia or retinal degeneration. IBRPfl/fl mice were bred with 5 Cre-driver lines: HRGP-Cre, Chx10-Cre, Rho-iCre75, HRGP-Cre Rho-iCre75, and Rx-Cre. Mice were analyzed for IRBP gene expression through digital droplet PCR (ddPCR). Young adult (P30) mice were tested for retinal degeneration and morphology using spectral-domain optical coherence tomography (SD-OCT) and hematoxylin and eosin (H&E) staining. Function was analyzed using electroretinograms (ERGs). Eye sizes and axial lengths were compared through external eye measurements and whole eye biometry. Across all outcome measures, when bred to IRBPfl/fl, HRGP-Cre and Chx10-Cre lines showed no differences from IRBPfl/fl alone. With the Rho-iCre75 line, small but significant reductions were seen in retinal thickness with SD-OCT imaging and postmortem H&E staining without increased axial length. Both the HRGP-Cre+Rho-iCre75 and the Rx-Cre lines showed significant decreases in retinal thickness and outer nuclear layer cell counts. Using external eye measurements and SD-OCT imaging, both lines showed an increase in eye size. Finally, function in both lines was roughly halved across scotopic, photopic, and flicker ERGs. Our studies support hypotheses that for both eye size determination and retinal homeostasis, there are two critical timing windows when IRBP must be expressed in rods or cones to prevent myopia (P7-P12) and degeneration (P21 and later). The rod-specific IRBP knockout (Rho-iCre75) showed significant retinal functional losses without myopia, indicating that the two phenotypes are independent. IRBP is needed for early development of photoreceptors and eye size, whereas Rho-iCre75 IRBPfl/fl knockout results in retinal degeneration without myopia.

Detection of FLASH-radiotherapy tissue sparing in a 3D-spheroid model using DNA damage response markers

PurposeThe oxygen depletion hypothesis has been proposed as a rationale to explain the observed phenomenon of FLASH-radiotherapy (FLASH-RT) sparing normal tissues while simultaneously maintaining tumor control. In this study we examined the distribution of DNA Damage Response (DDR) markers in irradiated 3D multicellular spheroids to explore the relationship between FLASH-RT protection and radiolytic-oxygen-consumption (ROC) in tissues. Methods: Studies were performed using a Varian Truebeam linear accelerator delivering 10 MeV electrons with an average dose rate above 50 Gy/s. Irradiations were carried out on 3D spheroids maintained under a range of O2 and temperature conditions to control O2 consumption and create gradients representative of in vivo tissues. Results: Staining for pDNA-PK (Ser2056) produced a linear radiation dose response whereas γH2AX (Ser139) showed saturation with increasing dose. Using the pDNA-PK staining, radiation response was then characterised for FLASH compared to standard-dose-rates as a function of depth into the spheroids. At 4 °C, chosen to minimize the development of metabolic oxygen gradients within the tissues, FLASH protection could be observed at all distances under oxygen conditions of 0.3–1 % O2. Whereas at 37 °C a FLASH-protective effect was limited to the outer cell layers of tissues, an effect only observed at 3 % O2. Modelling of changes in the pDNA-PK-based oxygen enhancement ratio (OER) yielded a tissue ROC g0-value estimate of 0.73 ± 0.25 µM/Gy with a km of 5.4 µM at FLASH dose rates. Conclusions: DNA damage response markers are sensitive to the effects of transient oxygen depletion during FLASH radiotherapy. Findings support the rationale that well-oxygenated tissues would benefit more from FLASH-dose-rate protection relative to poorly-oxygenated tissues.

Bacterial peptidoglycan serves as a critical modulator of the gut-immune-brain axis in Drosophila

Metabolites and compounds derived from gut-associated bacteria can modulate numerous physiological processes in the host, including immunity and behavior. Using a model of oral bacterial infection, we previously demonstrated that gut-derived peptidoglycan (PGN), an essential constituent of the bacterial cell envelope, influences female fruit fly egg-laying behavior by activating the NF-κB cascade in a subset of brain neurons. These findings underscore PGN as a potential mediator of communication between gut bacteria and the brain in Drosophila, prompting further investigation into its impact on all brain cells. Through high-resolution mass spectrometry, we now show that PGN fragments produced by gut bacteria can rapidly reach the central nervous system. In Addition, by employing a combination of whole-genome transcriptome analyses, comprehensive genetic assays, and reporter gene systems, we reveal that gut bacterial infection triggers a PGN dose-dependent NF-κB immune response in perineurial glia, forming the continuous outer cell layer of the blood–brain barrier. Furthermore, we demonstrate that persistent PGN-dependent NF-κB activation in perineurial glial cells correlates with a reduction in lifespan and early neurological decline. Overall, our findings establish gut-derived PGN as a critical mediator of the gut-immune-brain axis in Drosophila.

The plastid-localized lipoamide dehydrogenase 1 is crucial for redox homeostasis, tolerance to arsenic stress and fatty acid biosynthesis in rice.

Soil contamination with arsenic (As) can cause phytotoxicity and reduce crop yield. The mechanisms of As toxicity and tolerance are not fully understood. In this study, we used a forward genetics approach to isolate a rice mutant, ahs1, that exhibits hypersensitivity to both arsenate and arsenite. Through genomic resequencing and complementation tests, we identified OsLPD1 as the causal gene, which encodes a putative lipoamide dehydrogenase. OsLPD1 was expressed in the outer cell layer of roots, root meristem cells, and in the mesophyll and vascular tissues of leaves. Subcellular localization and immunoblot analysis demonstrated that OsLPD1 is localized in the stroma of plastids. In vitro assays showed that OsLPD1 exhibited lipoamide dehydrogenase (LPD) activity, which was strongly inhibited by arsenite, but not by arsenate. The ahs1 and OsLPD1 knockout mutants exhibited significantly reduced NADH/NAD+ and GSH/GSSG ratios, along with increased levels of reactive oxygen species and greater oxidative stress in the roots compared with wild-type (WT) plants under As treatment. Additionally, loss-of-function of OsLPD1 also resulted in decreased fatty acid concentrations in rice grain. Taken together, our finding reveals that OsLPD1 plays an important role for maintaining redox homeostasis, conferring tolerance to arsenic stress, and regulating fatty acid biosynthesis in rice.

Updated single cell reference atlas for the starlet anemone Nematostella vectensis.

The recent combination of genomics and single cell transcriptomics has allowed to assess a variety of non-conventional model organisms in much more depth. Single cell transcriptomes can uncover hidden cellular complexity and cell lineage relationships within organisms. The recent developmental cell atlases of the sea anemone Nematostella vectensis, a representative of the basally branching Cnidaria, has provided new insights into the development of all cell types (Steger et al Cell Rep 40(12):111370, 2022; Sebé-Pedrós et al. Cell 173(6):1520-1534.e20). However, the mapping of the single cell reads still suffers from relatively poor gene annotations and a draft genome consisting of many scaffolds. Here we present a new wildtype resource of the developmental single cell atlas, by re-mapping of sequence data first published in Steger et al. (2022) and Cole et al. (Nat Commun 14(1):1747, 2023), to the new chromosome-level genome assembly and corresponding gene models in Zimmermann et al. (Nat Commun 14, 8270 (2023). https://doi.org/10.1038/s41467-023-44080-7 ). We expand the pre-existing dataset through the incorporation of additional sequence data derived from the capture and sequencing of cell suspensions from four additional samples: 24h gastrula, 2d planula, an inter-parietal region of the bodywall from a young unsexed animal, and another adult mesentery from a mature male animal. Our analyses of the full cell-state inventory provide transcriptomic signatures for 127 distinct cell states, of which 47 correspond to neuroglandular subtypes. We also identify two distinct putatively immune-related transcriptomic profiles that segregate between the inner and outer cell layers. Furthermore, the new gene annotation Nv2 has markedly improved the mapping on the single cell transcriptome data and will therefore be of great value for the community and anyone using the dataset.

Identification and function characterization of BnaBOR4 genes reveal their potential for Brassica napus cultivation under high boron stress

Boron (B) is essential for plant growth, but toxic in excess. In several countries, soil toxic B levels are always a severe agricultural problem in arid and semi-arid regions. Phytoremediation of excess B containing soil is still in its infancy, while high B tolerant plants with elevated protein abundance of B efflux transporter were successfully established or explored. Brassica napus (B. napus) is one of the most important oil crops. However, B efflux transporters underlying excess B tolerance in B. napus remain unknown. Here, we reported that in Brassicaceae species, B. napus had four homologous genes of Arabidopsis AtBOR4 , which were renamed BnaBOR4.1, BnaBOR4.2, BnaBOR4.3 and BnaBOR4.4. BnaBOR4.1, BnaBOR4.2 and BnaBOR4.3 showed constitutive expression and BnaBOR4.4 appeared to be a pseudogene. BnaBOR4.2 and BnaBOR4.3 were expressed in inner cell layers and BnaBOR4.1 in the outer cell layer in root tip, and all were expressed in vascular tissue in the mature zone. B efflux activity assays in yeast demonstrated that BnaBOR4.1, BnaBOR4.2 and AtBOR4 but not BnaBOR4.3 had comparable levels of B transport activity. Structure-functional analysis between BnaBOR4.3 and BnaBOR4.2 demonstrated that amino acid residue substitution at position 297 (Ala vs Pro) and 427 (Met vs Leu) is critical for the B transport activity. Mutant BnaBOR4.3M427L partially restored the B efflux activity, and both mutants BnaBOR4.3A297P and BnaBOR4.3A297P&M427L fully restored B efflux activity, indicating that the Pro297 residue is critical for their function. Further validation of BnaBOR4 was accomplished by growing transgenic Arabidopsis plants under high B conditions. Taken together, our study identified two functional B efflux genes BnaBOR4.1 and BnaBOR4.2 in B. napus, and a key amino acid residue proline 297 associated with B efflux activity. This study highlights the potential of BanBOR4 genes for B. napus cultivation under high B stress.

Granulosa Cells Alone, Without Theca Cells, Can Mediate LH-induced Oocyte Meiotic Resumption.

Signaling in the granulosa cells of mammalian ovarian follicles is necessary for maintaining prophase arrest in the oocyte and for mediating the resumption of meiosis in response to luteinizing hormone (LH). However, the follicle also includes an outer layer of theca cells, some of which express receptors for LH. To investigate whether theca cells are required for maintaining meiotic arrest and reinitiating meiosis in response to LH, we mechanically separated the granulosa cells and oocyte from the theca and basal lamina. This was accomplished by cutting a slit in the outer surface of isolated follicles such that the mural granulosa cells and cumulus-oocyte complex were extruded from the theca shell, forming a lawn of cells on an organotypic membrane. The remnant of theca cells and basal lamina was then removed. The separation of the granulosa cells from the theca cells and basal lamina was demonstrated by immunofluorescence localization of endomucin (blood vessels of the theca) and laminin gamma (basal lamina). Cells comprising these granulosa cell-oocyte complexes expressed LH receptors and were connected by gap junctions. Oocytes within these granulosa cell complexes maintained meiotic arrest and resumed meiosis in response to LH, showing that the granulosa cells alone, without theca cells, transduce these signals. This semi-intact and mostly 2-dimensional preparation could facilitate imaging studies of follicle physiology.

Reduced expression of Ankyrin-G and E-cadherin in duodenal mucosal biopsy of subjects with celiac disease

Confirmatory diagnosis of celiac disease (CD) include histopathology of duodenal biopsy and tissue trans-glutaminase-IgA. Identification of tissue-specific histological markers is warranted to improve the diagnosis. A genetic study in CD identified the association of ankyrin-G that connects E-cadherin with β2-spectrin in epithelial cells of the duodenal tissue. We attempted to investigate the differential expression of ankyrin-G, E-cadherin and β2-spectrin in duodenal biopsy of CD subjects compared to non-CD controls. Duodenal tissue was collected from 83 study participants, of which 50 were CD, and 33 were non-CD controls. Whole RNA was isolated from 32 CD and 23 non-CD controls from available tissues, and differential mRNA expression was measured using real-time PCR. Tissue sections from 18 CD cases and 10 non-CD controls were immunostained using monoclonal antibodies. Tissue immunohistochemistry were evaluated for differential expression and pattern of expression. RT-PCR revealed significantly reduced expression of ankyrin-G (fold change=0.63; p=0.03) and E-cadherin (fold change=0.50; p=0.02) among CD subjects compared to non-CD controls. Tissue immunohistochemistry confirmed the reduced expression of ankyrin-G and E-cadherin in CD. Differential expression is grossly limited within the outer columnar epithelial cell layer. Expression fold change of E-cadherin was seen to partially correlate with the serum tTG level (r=0.4; p=0.04). In CD, reduced expression of two key cytoskeletal proteins (ankyrin-G and E-cadherin) in duodenum mucosa was observed, which indicates its implication in disease biology and could be tested as a tissue-specific biomarker for CD. Functional studies may unravel the specific contribution of these proteins in CD pathophysiology.

Analysis of the results of retinal peptides application in different ages of Campbell rats with Retinitis Pigmentosa

The work concerns studying electrophysiological parameters and, based on histological studies, morphological parameters of the retina in different age groups of Campbell rats with Retinitis Pigmentosa (RP) before and after Retinalamin treatment. 50 Campbell rats, as an experimental model of inherited RP, were used in the study. Rats were divided into two age groups, with 25 rats in each. Group I consisted of newborns up to 3 weeks, and Group II consisted of adults aged 3.5 ± 0.3 months. Retinalamin injections were given parabulbarly to all animals for 10 days. The total bioelectrical activity of the a, b, and c waves and the average value of the b-wave amplitude were studied using the electroretinography (ERG) method. Also, the thickness of the outer nuclear layer of retinal pigment epithelium cells was studied in a histological examination. Studies were conducted before the start of Retinalamin injections and in dynamics after 10 and 30 days. According to the ERG results, a decrease in the total bioelectrical activity of the rat retina and the average b-wave amplitude were already observed in 19-day-old rats. A statistically significant increase in these indicators was observed in both groups after 10 and 30 days of Retinalamin injections. Histological analysis of retinal preparations also revealed positive changes after the peptide administrations. An improvement in morphological structures and thickening of the outer nuclear layer of retinal pigment epithelial cells were noted in both groups. More significant positive dynamics were in Group I of newborn rats. Conclusion. Retinalamin treatment in newborn and adult Campbell rats with retinitis pigmentosa stabilized the processes developing in the retina. At the same time, the maximum positive effect was manifested in newborn rats.

An examination of retinal findings with optical coherence tomography in hypothyroidism patients with vitamin D deficiency: A comparative study

<b>Aim: </b>This study aimed to examine the retinal layer before and after treatment in patients with hypothyroidism with vitamin D deficiency, since the vitamin also protects the retinal cells against inflammatory damage.<br /> <b>Material and methods: </b>The free T3, free T4, and vitamin D levels of 104 patients with no ocular disease were first measured. Ophthalmological examinations of these patients, who were divided into three groups, were performed by specialist ophthalmologists, while retinal findings were examined using optical coherence tomography (OCT) and recorded. The first group was given vitamin D for three months, the second levothyroxine, and the third vitamin D + levothyroxine. After three months repeat OCT was performed, and the results were compared with the previous values.<br /> <b>Results:</b> The thickness of the left inner nuclear cell layer of the patients in the vitamin D group increased significantly compared to pre-treatment. Post-treatment right central macular thickness, right nerve fiber layer, right outer nuclear cell layer, right pigment epithelial layer, left central macular, and left inner nuclear cell layer thicknesses were all significantly higher compared to pre-treatment in the patients in the levothyroxine + vitamin D group, while right outer retinal layer and left retinal nerve fiber thicknesses decreased (p<0.05).<br /> <b>Conclusion:</b> A greater increase in cell layer thickness was observed in the group using vitamin D and levothyroxine together compared to those in which vitamin D and levothyroxine were employed alone. However, further studies on the effect of vitamin D on retinal cell development and protection against injury are now needed.

Neuronal deletion of phosphatase and tensin homolog in mice results in spatial dysregulation of adult hippocampal neurogenesis.

Adult neurogenesis is a persistent phenomenon in mammals that occurs in select brain structures in both healthy and diseased brains. The tumor suppressor gene, phosphatase and tensin homolog deleted on chromosome 10 (Pten) has previously been found to restrict the proliferation of neural stem/progenitor cells (NSPCs) in vivo. In this study, we aimed to provide a comprehensive picture of how conditional deletion of Pten may regulate the genesis of adult NSPCs in the dentate gyrus of the hippocampus and the subventricular zone bordering the lateral ventricles. Using conventional markers and stereology, we quantified multiple stages of neurogenesis, including proliferating cells, immature neurons (neuroblasts), and apoptotic cells in several regions of the dentate gyrus, including the subgranular zone (SGZ), outer granule cell layer (oGCL), molecular layer, and hilus at 4 and 10 weeks of age. Our data demonstrate that conditional deletion of Pten in mice produces successive increases in dentate gyrus proliferating cells and immature neuroblasts, which confirms the known negative roles Pten has on cell proliferation and maturation. Specifically, we observe a significant increase in Ki67+ proliferating cells in the neurogenic SGZ at 4 weeks of age, but not 10 weeks of age. We also observe a delayed increase in neuroblasts at 10 weeks of age. However, our study expands on previous work by providing temporal, subregional, and neurogenesis-stage resolution. Specifically, we found that Pten deletion initially increases cell proliferation in the neurogenic SGZ, but this increase spreads to non-neurogenic dentate gyrus areas, including the hilus, oGCL, and molecular layer, as mice age. We also observed region-specific increases in apoptotic cells in the dentate gyrus hilar region that paralleled the regional increases in Ki67+ cells. Our work is accordant with the literature showing that Pten serves as a negative regulator of dentate gyrus neurogenesis but adds temporal and spatial components to the existing knowledge.

Association between retinal layer thickness and cerebral white matter hyperintensities in older adults

AbstractBackgroundThe brain and retina may share pathophysiological mechanisms in various central nervous system disorders, suggesting the potential associations between retinal layer thickness and cerebral white matter hyperintensities (WMH).MethodA total of 149 participants without dementia aged over 65 years (mean age: 75.4, SD: 5.4, range: 65‐91; male: 90 [60.4%]) from the randomly sampled community‐dwelling prospective cohort were included in the analysis. Using spectral‐domain optical coherence tomography, we assessed the thickness of 6 retinal layers in the macular region, the peripapillary retinal nerve fiber layers, and the subfoveal choroid. We classified WMH into 3 groups using the distance from the ventricle surface: juxtaventricular (JVWMH, < 4mm), periventricular (PVWMH, >4mm, <14mm), and deep WMH (DWMH > = 14mm). The associations between retinal layer thickness and WMH volume were examined using linear regression models adjusting age, sex, comorbid hypertension, and diabetes.ResultThe thicknesses of superior outer, inferior outer ganglion cell layers (GCL) and superior outer, inferior outer, total outer inner plexiform layers (IPL) were negatively associated with the total WMH, PVWMH, and DWMH volumes. Reduced thicknesses of total outer GCL and temporal outer inner nuclear layer (INL) were associated with higher total WMH and PVWMH volumes. Center GCL thickness was positively associated with JVWMH volume, and nasal outer GCL thickness was negatively associated with DWMH volume.ConclusionOuter GCL and IPL thicknesses may be associated with WMH volume in older adults. This study may also suggest differential associations based on etiology between retinal layer subfields and WMH subgroups.

Constitutive expression of apple endo-POLYGALACTURONASE1 in fruit induces early maturation, alters skin structure and accelerates softening.

During fruit ripening, polygalacturonases (PGs) are key contributors to the softening process in many species. Apple is a crisp fruit that normally exhibits only minor changes to cell walls and limited fruit softening. Here, we explore the effects of PG overexpression during fruit development using transgenic apple lines overexpressing the ripening-related endo-POLYGALACTURONASE1 gene. MdPG1-overexpressing (PGox) fruit displayed early maturation/ripening with black seeds, conversion of starch to sugars and ethylene production occurring by 80 days after pollination (DAP). PGox fruit exhibited a striking, white-skinned phenotype that was evident from 60 DAP and most likely resulted from increased air spaces and separation of cells in the hypodermis due to degradation of the middle lamellae. Irregularities in the integrity of the epidermis and cuticle were also observed. By 120 DAP, PGox fruit cracked and showed lenticel-associated russeting. Increased cuticular permeability was associated with microcracks in the cuticle around lenticels and was correlated with reduced cortical firmness at all time points and extensive post-harvest water loss from the fruit, resulting in premature shrivelling. Transcriptomic analysis suggested that early maturation was associated with upregulation of genes involved in stress responses, and overexpression of MdPG1 also altered the expression of genes involved in cell wall metabolism (e.g. β-galactosidase, MD15G1221000) and ethylene biosynthesis (e.g. ACC synthase, MD14G1111500). The results show that upregulation of PG not only has dramatic effects on the structure of the fruit outer cell layers, indirectly affecting water status and turgor, but also has unexpected consequences for fruit development.

Characterization of Niche Cells and Signals Regulating Stepwise Embryonic Hematopoiesis Using Slide-Seq and Merfish Spatial Transcriptomics

Stagewise HSC development initiates in the aorta-gonad-mesonephros (AGM) region during mouse embryonic day (E)9.5-E12.5 and progresses through stages including hemogenic endothelial cell (HEC) specification, the endothelial to hematopoietic transition (EHT), and maturation. The nascent HSCs (pre-HSCs) form in the AGM region and subsequently migrate to the fetal liver where they undergo further maturation and expansion. Recent advances in single cell technologies have significantly enhanced our understanding of intrinsic cellular programs involved in HSC development. However, our knowledge about niche cells and the signals they emanate in the AGM region, as well as their contribution to HSC development, remain limited. Here we've conducted spatial transcriptomics analysis using Slide-seq on mouse trunk tissues, including both the AGM region and the fetal liver, at E10.5, E11.5 and E12.5. In addition, we performed scRNA-seq on the cells collected from the AGM and trunk at E10.5, E11.5 and E12.5, as well as the fetal liver at E12.5. To integrate the Slide-seq and scRNA-seq data, we developed an algorithm that leverages capabilities from both spatial and in-depth transcriptional sequencing. As a result, we were able to successfully reconstitute the structures of the trunk tissues and obtain gene expression profiles of individual cells at 10 µm resolution. From the analysis, we identified 7 cell clusters surrounding the aorta, with one cluster comprised of Nfgr + cells predominantly occupying the dorsal aorta. The ventral part of aorta displayed a complex and multilayered cellular architecture, featuring pre-HSCs, endothelial cells, mesonephric cells, and macrophages. Notably, we identified a unique mesenchymal stromal cell (MSC) population that co-express Cdh2 (encodes N-cadherin or N-cad) and Pdgfra; thus, we call these cells N-cad + MSCs. These N-cad + MSCs were particularly enriched at the ventral part of the aorta, forming a single cell layer positioned between an inner layer of aortic endothelial cells and an outer layer of mesonephric cells. Next, we utilized several bioinformatics tools (CellphoneDB, CellChat, NicheChat, and StringDB) in effort to identify potential signals that could impact embryonic hematopoiesis. The results revealed intricate interactions between N-cad + MSCs and pre-HSCs, for example, involving JAG1-NOTCH1 and SDF-1 (encoded by Cxcl12)-CXCR4 ligand-receptor pairs. To validate the findings obtained by the Slide-seq data, we selected and designed customized RNA probes for 140 genes of interest, including cell markers and potential signals. We then conducted MERFISH (Multiplexed Error-Robust Fluorescence in situ Hybridization) on 18 E11.5 trunk sections. The MERFISH data enabled us to characterize the spatially resolved niche cells and their derived signals in the AGM region at the single-cell level, which largely corroborated the results obtained from the Slide-seq data. Specifically, the MERFISH data indicates that N-cad + MSCs are in direct contact with aortic endothelial cells and are the primary cellular source of Jag1 and Cxcl12 around the aorta. Given the unique position of N-cad + MSCs and their intricate interactions with pre-HSCs, we formulated the hypothesis that N-cad + MSCs play a crucial role in embryonic hematopoiesis. To functionally validate our hypothesis, we are conducting a series of experiments using Ncad CreER; Cxcl12 flox/floxand Ncad CreER; Jag1 flox/flox mouse models. We anticipate that embryos lacking N-cad + MSC derived Jag1 or Cxcl12 will exhibit a substantial decline in intra-aortic hematopoietic clusters, phenotypic pre-HSCs, and functional HSCs. In summary, our study employed sequencing-based (Slide-seq) and imaging-based (MERFISH) spatial transcriptomics technologies to successfully characterize dynamic, spatially resolved profiles of niche components and associated signaling in the AGM region at the single cell level. This work significantly enhances our understanding of niche signaling and its role in regulating embryonic hematopoiesis and may aid the development of novel methods for inducing the transition from pluripotent stem cells to HSCs.

Anatomical and metabolic changes related to the yellowing of minimally processed peach palm (Bactris gasipaes Kunth) during cold storage

Peach palm tree products, including palm hearts, are in high demand worldwide, often consumed either in natura or with minimal processing, and possess significant economic value in various markets. Minimally processed peach palm (Bactris gasipaes Kunth) are suitable to yellowing during storage thereby compromising its market value. In order to understand the surface yellowing in different sections of palm heart (median and basal regions), packaged or un-packaged with PVC were evaluated for anatomical and metabolic changes during 0, 4, 8, and 12 days of cold storage. The tissues showed surface yellowing at the end of cold storage. The outer cell layers exhibited differentiating parenchymal and dermal tissues, and superficial cells collapsed in the yellowing tissues. The metabolite analysis indicated reduction in the contents of some tricarboxylic acid cycle intermediates, sugars, and antioxidants in minimally processed palm heart during cold storage. The reduction in these compounds boosted the biosynthesis of amino acids in the peach palm. The highest metabolic changes and yellowing were observed after 8 days of storage, with higher intensity at 12 days, suggesting loss of quality, nutritional value, and shelf-life. Changes in the metabolites were mostly affected by storage time, and packaging with PVC provides better conditions for maintaining post-harvest quality. This pioneering study on the metabolism and anatomy of minimally processed peach palm heart fills some gaps about the yellowing, quality, and shelf life of this product.