Human kidney function is underpinned by approximately 1,000,000 nephrons, although the number varies substantially, and low nephron number is linked to disease. Human kidney development initiates ...around 4 weeks of gestation and ends around 34-37 weeks of gestation. Over this period, a reiterative inductive process establishes the nephron complement. Studies have provided insightful anatomic descriptions of human kidney development, but the limited histologic views are not readily accessible to a broad audience. In this first paper in a series providing comprehensive insight into human kidney formation, we examined human kidney development in 135 anonymously donated human kidney specimens. We documented kidney development at a macroscopic and cellular level through histologic analysis, RNA
hybridization, immunofluorescence studies, and transcriptional profiling, contrasting human development (4-23 weeks) with mouse development at selected stages (embryonic day 15.5 and postnatal day 2). The high-resolution histologic interactive atlas of human kidney organogenesis generated can be viewed at the GUDMAP database (www.gudmap.org) together with three-dimensional reconstructions of key components of the data herein. At the anatomic level, human and mouse kidney development differ in timing, scale, and global features such as lobe formation and progenitor niche organization. The data also highlight differences in molecular and cellular features, including the expression and cellular distribution of anchor gene markers used to identify key cell types in mouse kidney studies. These data will facilitate and inform
efforts to generate human kidney structures and comparative functional analyses across mammalian species.
Cellular interactions among nephron, interstitial, and collecting duct progenitors drive mammalian kidney development. In mice, Six2
nephron progenitor cells (NPCs) and Foxd1
interstitial progenitor ...cells (IPCs) form largely distinct lineage compartments at the onset of metanephric kidney development. Here, we used the method for analyzing RNA following intracellular sorting (MARIS) approach, single-cell transcriptional profiling,
hybridization, and immunolabeling to characterize the presumptive NPC and IPC compartments of the developing human kidney. As in mice, each progenitor population adopts a stereotypical arrangement in the human nephron-forming niche: NPCs capped outgrowing ureteric branch tips, whereas IPCs were sandwiched between the NPCs and the renal capsule. Unlike mouse NPCs, human NPCs displayed a transcriptional profile that overlapped substantially with the IPC transcriptional profile, and key IPC determinants, including
, were readily detected within SIX2
NPCs. Comparative gene expression profiling in human and mouse Six2/SIX2
NPCs showed broad agreement between the species but also identified species-biased expression of some genes. Notably, some human NPC-enriched genes, including
and
, are linked to human renal disease. We further explored the cellular diversity of mesenchymal cell types in the human nephrogenic niche through single-cell transcriptional profiling. Data analysis stratified NPCs into two main subpopulations and identified a third group of differentiating cells. These findings were confirmed by section
hybridization with novel human NPC markers predicted through the single-cell studies. This study provides a benchmark for the mesenchymal progenitors in the human nephrogenic niche and highlights species-variability in kidney developmental programs.
The canonical Wnt pathway transcriptional co-activator β-catenin regulates self-renewal and differentiation of mammalian nephron progenitor cells (NPCs). We modulated β-catenin levels in NPC cultures ...using the GSK3 inhibitor CHIR99021 (CHIR) to examine opposing developmental actions of β-catenin. Low CHIR-mediated maintenance and expansion of NPCs are independent of direct engagement of TCF/LEF/β-catenin transcriptional complexes at low CHIR-dependent cell-cycle targets. In contrast, in high CHIR, TCF7/LEF1/β-catenin complexes replaced TCF7L1/TCF7L2 binding on enhancers of differentiation-promoting target genes. Chromosome confirmation studies showed pre-established promoter-enhancer connections to these target genes in NPCs. High CHIR-associated de novo looping was observed in positive transcriptional feedback regulation to the canonical Wnt pathway. Thus, β-catenin's direct transcriptional role is restricted to the induction of NPCs, where rising β-catenin levels switch inhibitory TCF7L1/TCF7L2 complexes to activating LEF1/TCF7 complexes at primed gene targets poised for rapid initiation of a nephrogenic program.
Nephron endowment is determined by the self-renewal and induction of a nephron progenitor pool established at the onset of kidney development. In the mouse, the related transcriptional regulators ...Six1 and Six2 play non-overlapping roles in nephron progenitors. Transient Six1 activity prefigures, and is essential for, active nephrogenesis. By contrast, Six2 maintains later progenitor self-renewal from the onset of nephrogenesis. We compared the regulatory actions of Six2 in mouse and human nephron progenitors by chromatin immunoprecipitation followed by DNA sequencing (ChIP-seq). Surprisingly, SIX1 was identified as a SIX2 target unique to the human nephron progenitors. Furthermore, RNA-seq and immunostaining revealed overlapping SIX1 and SIX2 activity in 16 week human fetal nephron progenitors. Comparative bioinformatic analysis of human SIX1 and SIX2 ChIP-seq showed each factor targeted a similar set of cis-regulatory modules binding an identical target recognition motif. In contrast to the mouse where Six2 binds its own enhancers but does not interact with DNA around Six1, both human SIX1 and SIX2 bind homologous SIX2 enhancers and putative enhancers positioned around SIX1. Transgenic analysis of a putative human SIX1 enhancer in the mouse revealed a transient, mouse-like, pre-nephrogenic, Six1 regulatory pattern. Together, these data demonstrate a divergence in SIX-factor regulation between mouse and human nephron progenitors. In the human, an auto/cross-regulatory loop drives continued SIX1 and SIX2 expression during active nephrogenesis. By contrast, the mouse establishes only an auto-regulatory Six2 loop. These data suggest differential SIX-factor regulation might have contributed to species differences in nephron progenitor programs such as the duration of nephrogenesis and the final nephron count.
A better understanding of predator-prey interactions is crucial for the development of biological control strategies. The green lacewing,
, is a well-known generalist predator and reportedly ...functions as one of the most important biological control agents of insect pests. However, information regarding
.
' predation on tea plant pests, particularly notorious tea mites, remains largely unknown. In this study, we focused on the predator-prey relationship between
.
and an important tea mite pest,
. We designed species-specific primers for the detection of
DNA and established a PCR-based DNA gut content analysis assay. These results demonstrated that the primers were
-specific and suitable for its molecular identification. The laboratory feeding experiment showed that the detectability success (DS
) of
DNA remaining in
guts was 2.9 h. We then performed a molecular detection of field predation, and achieved a 23.53% positive detection rate of
DNA in the guts of field-collected
. This, for the first time, provides direct evidence that
can prey on
in tea plantations. Finally, we tested the prey preference and estimated the predation ability of
on different developmental stages of
. The results revealed that
had no significant preference for different developmental stages of
. The functional responses of
' predation on different densities of
at different developmental stages followed a Type II Holling model. The initial attack rate (a') ranged from 0.735 to 0.858 and the handling time (T
) was approximately 0.01. This study is the first to demonstrate the trophic interactions between
and
and provides evidence for the development of biological control strategies against
using
as a candidate predator.
To study the effect of different slag content and different curing methods on the carbonation resistance of fly ash- and slag-based geopolymer concrete (FA&SL-GPC), a series of experiments were ...carried out with slag content (accounting for 10%, 30% and 50% of cementitious materials) and curing methods (standard curing and high temperature curing) as variables. The results show that increasing the slag content is helpful for improving the carbonation resistance properties, microstructure, and carbonation resistance components of FA&SL-GPC substrate. Adopting a standard curing method and prolonging the curing age are more favorable to the carbonation resistance of FA&SL-GPC, and the longer the curing time is, the better. Finally, the carbonation depth prediction model suitable for this experiment is deduced and verified. From the research results, it can be seen that using a high slag content mix and curing under standard conditions is beneficial for the carbonization resistance of GPC structural components.
The renal corpuscle of the kidney comprises a glomerular vasculature embraced by podocytes and supported by mesangial myofibroblasts, which ensure plasma filtration at the podocyte-generated slit ...diaphragm. With a spectrum of podocyte-expressed gene mutations causing chronic disease, an enhanced understanding of podocyte development and function to create relevant in vitro podocyte models is a clinical imperative. To characterize podocyte development, scRNA-seq was performed on human fetal kidneys, identifying distinct transcriptional signatures accompanying the differentiation of functional podocytes from progenitors. Interestingly, organoid-generated podocytes exhibited highly similar, progressive transcriptional profiles despite an absence of the vasculature, although abnormal gene expression was pinpointed in late podocytes. On transplantation into mice, organoid-derived podocytes recruited the host vasculature and partially corrected transcriptional profiles. Thus, human podocyte development is mostly intrinsically regulated and vascular interactions refine maturation. These studies support the application of organoid-derived podocytes to model disease and to restore or replace normal kidney functions.
•scRNA-seq identifies distinct transcriptional profiles of human podocyte development•Comparative analyses show similarities and differences of in vitro-derived podocytes•Implantation study suggests vascular interactions improve in vitro podocyte maturation
Tran et al. performed single-cell RNA sequencing to provide an understanding of human podocyte development. Insights from the in vivo analysis was applied to extensively evaluate the formation of podocytes in vitro, highlighting autonomous programs of development and those requiring an interplay with adjacent cell types.
Nephron progenitor number determines nephron endowment; a reduced nephron count is linked to the onset of kidney disease. Several transcriptional regulators including Six2, Wt1, Osr1, Sall1, Eya1, ...Pax2, and Hox11 paralogues are required for specification and/or maintenance of nephron progenitors. However, little is known about the regulatory intersection of these players. Here, we have mapped nephron progenitor-specific transcriptional networks of Six2, Hoxd11, Osr1, and Wt1. We identified 373 multi-factor associated 'regulatory hotspots' around genes closely associated with progenitor programs. To examine their functional significance, we deleted 'hotspot' enhancer elements for Six2 and Wnt4. Removal of the distal enhancer for Six2 leads to a ~40% reduction in Six2 expression. When combined with a Six2 null allele, progeny display a premature depletion of nephron progenitors. Loss of the Wnt4 enhancer led to a significant reduction of Wnt4 expression in renal vesicles and a mildly hypoplastic kidney, a phenotype also enhanced in combination with a Wnt4 null mutation. To explore the regulatory landscape that supports proper target gene expression, we performed CTCF ChIP-seq to identify insulator-boundary regions. One such putative boundary lies between the Six2 and Six3 loci. Evidence for the functional significance of this boundary was obtained by deep sequencing of the radiation-induced Brachyrrhine (Br) mutant allele. We identified an inversion of the Six2/Six3 locus around the CTCF-bound boundary, removing Six2 from its distal enhancer regulation, but placed next to Six3 enhancer elements which support ectopic Six2 expression in the lens where Six3 is normally expressed. Six3 is now predicted to fall under control of the Six2 distal enhancer. Consistent with this view, we observed ectopic Six3 in nephron progenitors. 4C-seq supports the model for Six2 distal enhancer interactions in wild-type and Br/+ mouse kidneys. Together, these data expand our view of the regulatory genome and regulatory landscape underpinning mammalian nephrogenesis.
Abstract
Transient electronics that can disappear or degrade via physical disintegration or chemical reaction over a pre-defined operational period provide essential for their applications in ...implantable bioelectronics due to the complete elimination of the second surgical extraction. However, the dissolution of commonly utilized bioresorbable materials often accompanies hydrogen production, which may cause potential or irreparable harm to the human body. This paper introduces germanium nanomembrane-based bioresorbable electronic sensors, where the chemical dissolution of all utilized materials in biofluidic theoretically have no gaseous products. In particular, the superior electronic transport of germanium enables the demonstrated bioresorbable electronic sensors to successfully distinguish the crosstalk of different physiological signals, such as temperature and strain, suggesting the significant prospect for the construction of dual or multi-parameter biosensors. Systematical studies reveal the gauge factor and temperature coefficient of resistance comparable to otherwise similar devices with gaseous products during their dissolution.
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