Folliculogenesis is a process that requires accurate interpretation of female physiological cues and elaborate coordination between the growing oocyte and its surrounding follicle cells, each being capable of responding to external signals. Here, we investigate the role of insulin signaling in Drosophila follicle cells. Using a phase separation-based reporter system, we observe a surge of insulin receptor activity in follicle cells during vitellogenic stages, a surge that is disrupted by a maternal high-sucrose diet. Single-cell RNA-seq reveals a diet-sensitive subpopulation of stage-8 follicle cells, which exhibits a reduction in CrebA-mediated transcription of genes for yolk and vitelline membrane proteins. Our results suggest a critical role of CrebA in implementing the stage-specific effect of insulin signaling to boost the secretory capacity of follicle cells. Mechanistically, CrebA is directly repressed by nuclear FoxO that is subject to insulin control, a regulatory axis that we show is conserved in human granulosa cells. This study delineates a mechanism through which insulin and nutrient cues act on a developmental transition via modulating the biosynthetic and secretory functions of the ovary.

Stress granules (SGs) are dynamic organelles that form under cellular stress and are generally regarded as protective entities. However, their role in pathogenesis is increasingly recognized, yet the underlying mechanisms remain elusive due to the diversity of stress types and biological contexts. Here, we investigate how different regimes of glycolytic inhibition influence SG dynamics and transcriptomic partitioning. We subjected cells to glucose depletion (GD), 2-deoxy-D-glucose addition (2DG), or their combination (GD+2DG). We show that SGs formed under single assaults dissipate during prolonged treatment and correlate with integrated stress response (ISR), whereas SGs induced by GD+2DG persist and are associated with mitochondrial dysfunction and increased apoptosis. Using G3BP1-APEX2 proximity labeling, we find that GD+2DG uniquely enriches oxidative phosphorylation (OXPHOS) transcripts in the G3BP1-associated transcriptome. We demonstrate that mitochondrial inhibition renders SGs formed under single assaults persistent. We propose a model in which two counteracting feedback loops determine SG fates under glycolytic stress: a negative ISR-mediated loop promotes SG recovery, while a positive loop involving G3BP1-partitioned OXPHOS transcripts drives SG persistence and metabolic collapse. This framework provides mechanistic insights into the paradoxical duality of SGs in stress adaptation and disease.

ERK is a key signaling mediator controlling both proliferation and lineage specification during embryo development. How ERK choreographs differentiation and proliferation to achieve balanced developmental outcomes in lineages with variable ERK activities remains unclear. To investigate this, we established multiplex quantitative live-cell imaging to track human pluripotent stem cell differentiation into mesendoderm (ME), a lineage specified by gastrulation morphogens and dependent on high ERK activity. We found that distinct morphogen combinations generate varying ERK activity levels, which correlate with heterogeneous ME fate choices despite relatively uniform cell cycle dynamics. To dissect how heterogenous ERK levels directly modulate and coordinate ME differentiation and proliferation, we engineered a synthetic spectrum of titrated ERK activities. Our results showed that ERK fine-tunes ME differentiation potential and cell division speed under nonoverlapping activity ranges, enabling quantitative control of ME fate specification without major effect on cell cycle progression. Mechanistically, this uncoupling stems from differential transcriptional and translational sensitivities of ME-specifying genes versus cell cycle genes to ERK input. Together, our findings reveal how a single signaling pathway quantitatively balances differentiation and proliferation during lineage commitment and embryogenesis.

Zygotic genome activation (ZGA) failure leads to developmental arrest and poses a clinical challenge to women's fertility. We observed that human embryos arresting at the eight-cell ZGA stage exhibited specific down-regulation of endogenous retrovirus MLT2A1. Depleting MLT2A1 resulted in a failure in embryo development and a reduction in ZGA gene expression. Mechanistically, MLT2A1s synthesized chimeric transcripts with downstream coding and noncoding sequences, predominantly with heterologous retro-transposable elements. These diverse fusion sequences expanded the genome-targeting spectrum of MLT2A1 RNAs. Nevertheless, the shared MLT2A1 sequences partnered with heterogeneous nuclear ribonucleoprotein U (HNRNPU) to recruit RNA polymerase II, promoting global transcription of ZGA genes and autoamplification of the MLT2A1 subfamily. Thus, MLT2A1 chimeric RNAs formed an interlocking network that acts synergistically to boost human ZGA and early embryogenesis.

Body size control is fundamental to development and requires proper energy engagement. One of the key energy sensing factors is AMP-activated protein kinase (AMPK), which regulates glucose uptake to ensure ATP production and nutrition supply during development. Here, we identify that the mutation of xgr, a gene encoding an ATPase, results in a reduced body size in Drosophila. Xgr is primarily expressed in the epithelial cells of the Malpighian tubules and the midguts. Loss of xgr leads to the inactivation of the AMPK signaling due to an increased ATP level. Glucose reabsorption in the Malpighian tubules is significantly reduced, as the Glut1 translocation to the plasma membrane is significantly disrupted in the absence of Xgr function. Our results suggest that Xgr function in the Malpighian tubules is essential to systemic glucose supply and energy homeostasis at the organismal level, thereby impacting body size. Our findings provide a mechanistic connection between energy homeostasis and animal size control during development.

Coordinated activation and directional migration of adult stem cells are essential for maintaining tissue homeostasis. Drosophila tracheal progenitors are adult stem cells that migrate posteriorly along the dorsal trunk to replenish degenerating branches that disperse the fibroblast growth factor mitogen. However, it is currently unknown how the overall anterior-to-posterior directionality of such migration is controlled. Here, we show that individual progenitor cells migrate together in a concerted, disciplined manner, a behavior that is dependent on the neighboring fat body. We identify the fat body-derived cytokine, Upd2, in targeting and inducing JAK/STAT signaling in tracheal progenitors to maintain their directional migration. Perturbation of either Upd2 production in fat body or JAK/STAT signaling in trachea causes aberrant bidirectional migration of tracheal progenitors. We show that JAK/STAT signaling promotes the expression of genes involved in planar cell polarity leading to asymmetric localization of Fat in progenitor cells. We provide evidence that Upd2 transport requires Rab5- and Rab7-mediated endocytic sorting and Lbm-dependent vesicle trafficking. Our study thus uncovers an inter-organ communication in the control of disciplined migration of tracheal progenitor cells, a process that requires vesicular trafficking of fat body-derived cytokine Upd2 and JAK/STAT signaling-mediated activation of PCP genes.

Stress granules (SGs) are dynamic organelles formed under cellular stress and they are generally regarded as protective entities. Meanwhile, their role in pathogenesis is becoming increasingly recognized, but the underlying mechanisms remain elusive due to the diverse nature of both stress types and biological contexts. Here we investigate SG dynamics and temporal changes in bulk and SG-associated transcriptomes under different regimens that inhibit glycolysis. We subject cells to either single assaults of glucose depletion (GD) or 2-deoxy-D-glucose addition (2DG) or a combined treatment (GD+2DG). We find that SGs formed under these conditions exhibit distinct properties, including eIF2α phosphorylation dependency, mRNA composition, and capacity to disassembly. Our results show that SGs induced by GD+2DG uniquely trap oxidative phosphorylation (OXPHOS) gene transcripts, leading to mitochondrial dysfunction. We provide evidence suggesting that the persistency of SGs formed under GD+2DG treatment is interwoven with mitochondrial dysfunction resulting in heightened apoptosis, effects that can also be recreated under single assaults when combined with mitochondrial inhibition. Our findings suggest that SG formation induced by inhibiting a single metabolic pathway can widen its impact in intensifying cellular metabolic stress under specific conditions, providing mechanistic insights into the paradoxical dual nature of SGs in stress response and pathology. ### Competing Interest Statement The authors have declared no competing interest.

The formation of body axes is a key developmental milestone in vertebrate embryos and is guided by specialized groups of cells known as organizers. The molecular nature of organizers has been extensively investigated across the vertebrate kingdom; however, the minimal conditions and factors sufficient to guide embryogenesis and organogenesis-particularly in humans-remain incompletely understood. Here, we show that BMP4 alone, when administered at an appropriate dosage, is sufficient to induce the formation of an organizer for ventral-caudal-like structure (VCLS) formation. This organizer directs endoderm-deficient ventral-caudal cell fate specification and morphogenesis in zebrafish embryos. In 3D human pluripotent stem cell (hPSC) aggregates, BMP4 can induce an elongated embryonic structure that is characterized by ventral-caudal cell fates. Importantly, hPSCs instructed by BMP4 are sufficient to induce a secondary posterior axis when grafted into the animal pole of the zebrafish embryo. Our study thus uncovers BMP4 as the inducer for the formation of a ventral-caudal organizer in the vertebrate embryo.

p21 inhibits CDK2 activity to induce quiescence in response to stress or developmental stimulation. It is currently unclear whether p21 exhibits an equal functional importance across different stages and states of the quiescence arrest. Here employing a rapid p21 degradation system, we evaluate the contribution of p21 across heterogeneous quiescence arrest states during quiescence progression. Our findings reveal that cells exhibit a dynamics dependency on p21 during quiescence arrest. At low levels of p21, quiescence is exclusively dependent on p21-mediated inhibition of CDK2 activity to prevent cell cycle progression. In contrast, when p21 accumulates to higher levels, quiescence transitions into an "auto-maintenance" state where p21 becomes less essential. Mechanistically, we found an active attenuation of the KRAS/ERK signalling pathway as a driver of reduced proliferation potential in this "auto-maintenance" state. This attenuation reinforces the robustness of quiescence through a mechanism that is independent of p21. Our results thus support a dynamic, adaptive mechanism for quiescence regulation that synchronizes the anti- and pro-proliferation signals. This mechanism is applicable over various stress or developmental quiescence context, offering a basis for cells to explore distinct quiescence states to achieve different degrees of robustness in cell cycle arrest.

Regulation of protein translation initiation is tightly associated with cell growth and survival. Here, we identify Paip1, the Drosophila homolog of the translation initiation factor PAIP1, and analyze its role during development. Through genetic analysis, we find that loss of Paip1 causes reduced protein translation and pupal lethality. Furthermore, tissue specific knockdown of Paip1 results in apoptotic cell death in the wing imaginal disc. Paip1 depletion leads to increased proteotoxic stress and activation of the integrated stress response (ISR) pathway. Mechanistically, we show that loss of Paip1 promotes phosphorylation of eIF2α via the kinase PERK, leading to apoptotic cell death. Moreover, Paip1 depletion upregulates the transcription factor gene Xrp1, which contributes to apoptotic cell death and eIF2α phosphorylation. We further show that loss of Paip1 leads to an increase in Xrp1 translation mediated by its 5'UTR. These findings uncover a novel mechanism that links translation impairment to tissue homeostasis and establish a role of ISR activation and Xrp1 in promoting cell death.

Haploid males of hymenopteran species produce gametes through an abortive meiosis I followed by meiosis II that can either be symmetric or asymmetric in different species. Thus, one spermatocyte could give rise to two spermatids with either equal or unequal amounts of cytoplasm. It is currently unknown what molecular features accompany these postmeiotic sperm cells especially in species with asymmetric meiosis II such as bees. Here we present testis single-cell RNA sequencing datasets from the honeybee (Apis mellifera) drones of 3 and 14 days after emergence (3d and 14d). We show that, while 3d testes exhibit active, ongoing spermatogenesis, 14d testes only have late-stage spermatids. We identify a postmeiotic bifurcation in the transcriptional roadmap during spermatogenesis, with cells progressing toward the annotated spermatids (SPT) and small spermatids (sSPT), respectively. Despite an overall similarity in their transcriptomic profiles, sSPTs express the fewest genes and the least RNA content among all the sperm cell types. Intriguingly, sSPTs exhibit a relatively high expression level for Hymenoptera-restricted genes and a high mutation load, suggesting that the special meiosis II during spermatogenesis in the honeybee is accompanied by phylogenetically young gene activities.

A class of noncoding RNAs, referred to as tsRNAs, is emerging with a potential to exert a new layer in gene regulation. These RNAs are breakdown products of tRNAs, either through active processing or passive cleavage or both. Since tRNAs are part of the general machinery for translation, their expression levels and activities are tightly controlled, raising the possibility that their breakdown products, tsRNAs, may provide a link between the overall translational status of a cell to specific changes in gene regulatory network. We hypothesize that Drosophila pupation, being a special developmental stage during which there is a global limitation of nutrients, represents a system in which such a link may readily reveal itself. We show that specific tsRNAs indeed show a dynamic accumulation upon entering the pupal stage. We describe experiments to characterize the mode of tsRNA action and, through the use of such gained knowledge, conduct a genome-wide analysis to assess the functions of dynamically expressed tsRNAs. Our results show that the predicted target genes are highly enriched in biological processes specific to this stage of development including metamorphosis. We further show that tsRNA action is required for successful pupation, providing direct support to the hypothesis that tsRNAs accumulated during this stage are critical to the gene expression program at this stage of development.

How patterns are formed to scale with tissue size remains an unresolved problem. Here we investigate embryonic patterns of gap gene expression along the anterior-posterior (AP) axis in Drosophila. We use embryos that greatly differ in length and, importantly, possess distinct length-scaling characteristics of the Bicoid (Bcd) gradient. We systematically analyze the dynamic movements of gap gene expression boundaries in relation to both embryo length and Bcd input as a function of time. We document the process through which such dynamic movements drive both an emergence of a global scaling landscape and evolution of boundary-specific scaling characteristics. We show that, despite initial differences in pattern scaling characteristics that mimic those of Bcd in the anterior, such characteristics of final patterns converge. Our study thus partitions the contributions of Bcd input and regulatory dynamics inherent to the AP patterning network in shaping embryonic pattern's scaling characteristics.

N6-methyladenosine (m6A) is a critical regulator in the fate of RNA, but whether and how m6A executes its functions in different tissues remains largely obscure. Here we report downregulation of a crucial m6A reader, YTHDF2, leading to tissue-specific programmed cell deaths (PCDs) upon fluorene-9-bisphenol (BHPF) exposure. Currently, Bisphenol A (BPA) substitutes are widely used in plastic manufacturing. Interrogating eight common BPA substitutes, we detected BHPF in 14% serum samples of pregnant participants. In a zebrafish model, BHPF caused tissue-specific PCDs triggering cardiac and vascular defects. Mechanistically, BHPF-mediated downregulation of YTHDF2 reduced YTHDF2-facilitated translation of m6A-gch1 for cardiomyocyte ferroptosis, and decreased YTHDF2-mediated m6A-sting1 decay for caudal vein plexus (CVP) apoptosis. The two distinct YTHDF2-mediated m6A regulations and context-dependent co-expression patterns of gch1/ythdf2 and tnfrsf1a/ythdf2 contributed to YTHDF2-mediated tissue-specific PCDs, uncovering a new layer of PCD regulation. Since BHPF/YTHDF2-medaited PCD defects were also observed in mammals, BHPF exposure represents a potential health threat.

Nutrients are vital to cellular activities, yet it is largely unknown how individual cells respond to nutrient deprivation. Live imaging results show that unlike the removal of amino acids or glutamine that immediately halts cell cycle progression, glucose withdrawal does not prevent cells from completing their current cycle. Although cells that begin to experience glucose withdrawal in S phase give rise to daughter cells with an equal choice of proliferation or quiescence, those enduring such experience in G1 phase give rise to daughter cells that predominantly enter quiescence. This fate choice difference stems from p21 protein accumulated during G2/M of the latter cells. Induced degradation of p21 permits daughter cells to enter S phase but with a consequent accumulation of DNA damage. These results suggest that mother cells that begin to experience glucose limitation in G1 phase take preemptive steps toward preventing daughter cells from making a harmful choice.

Polycystic ovary syndrome (PCOS) is a highly familial and heritable endocrine disorder. Over half of the daughters born to women with PCOS may eventually develop their own PCOS-related symptoms. Progress in the treatment of PCOS is currently hindered by the complexity of its clinical manifestations and incomplete knowledge of its etiopathogenesis. Various animal models, including experimentally induced, naturally occurring, and spontaneously arising ones, have been established to emulate a wide range of phenotypical and pathological traits of human PCOS. These studies have led to a paradigm shift in understanding the genetic, developmental, and evolutionary origins of this disorder. Furthermore, emerging evidence suggests that animal models are useful in evaluating state-of-the-art drugs and treatments for PCOS. This review aims to provide a comprehensive summary of recent studies of PCOS in animal models, highlighting the power of these disease models in understanding the biology of PCOS and aiding high-throughput approaches.

Feingold syndrome type 1, caused by loss-of-function of MYCN, is characterized by varied phenotypes including esophageal and duodenal atresia. However, no adequate model exists for studying the syndrome's pathological or molecular mechanisms, nor is there a treatment strategy. Here, we developed a zebrafish Feingold syndrome type 1 model with nonfunctional mycn, which had severe intestinal atresia. Single-cell RNA-seq identified a subcluster of intestinal cells that were highly sensitive to Mycn, and impaired cell proliferation decreased the overall number of intestinal cells in the mycn mutant fish. Bulk RNA-seq and metabolomic analysis showed that expression of ribosomal genes was down-regulated and that amino acid metabolism was abnormal. Northern blot and ribosomal profiling analysis showed abnormal rRNA processing and decreases in free 40S, 60S, and 80S ribosome particles, which led to impaired translation in the mutant. Besides, both Ribo-seq and western blot analysis showed that mTOR pathway was impaired in mycn mutant, and blocking mTOR pathway by rapamycin treatment can mimic the intestinal defect, and both L-leucine and Rheb, which can elevate translation via activating TOR pathway, could rescue the intestinal phenotype of mycn mutant. In summary, by this zebrafish Feingold syndrome type 1 model, we found that disturbance of ribosomal biogenesis and blockage of protein synthesis during development are primary causes of the intestinal defect in Feingold syndrome type 1. Importantly, our work suggests that leucine supplementation may be a feasible and easy treatment option for this disease.

中频系统是射电天文接收机的重要组成部分.接收机L,S,C和K波段的左圆极化和右圆极化信号在高频仓通过下变频转换为中频信号,中频信号通过同轴电缆传送到观测室.观测室距离射电望远镜高频仓较远,因此线损较大,且不同频率的信号损耗不同,频率越高损耗越大,导致中频信号功率较小且增益平坦度随频率增加而降低.设计了四通道均衡放大模块,提高中频信号增益并补偿增益平坦度.该模块的均衡器采用集总元件和微带线相结合的方式,具有结构紧凑、易于集成、成本低的优点.测试结果表明,在6倍频带宽内,均衡量≥8 dB,均衡后功率平坦度≤3.5 dBm,回波损耗≤-15 dB,满足射电天文中频检测系统的要求.

相控阵馈源(Phased Array Feed,PAF)是将阵列天线放置于射电望远镜焦面场处,用于实现更高增益及更灵活波束调控的接收机技术.与阵列天线一样,相控阵馈源是由多个天线单元以一定方式组合排列而成,工作时阵元之间难免产生电磁耦合.选用螺旋天线作为阵列天线单元,工作频率为1.25 GHz,对独立天线进行仿真优化后,该天线-10 dB阻抗带宽仅为70 MHz.依托该天线单元建立5×5矩形排布的螺旋天线阵列模型,分别选取阵元间距为1,0.5,0.25和0.125倍波长(1.25 GHz@0.24 m),验证不同阵元间距下的互耦效应对整个阵列带宽的影响.最终通过对各阵元输入阻抗进行匹配,仿真得到在0.25倍波长间距下,阵列中心阵子的-10 dB阻抗带宽可扩展至550 MHz,而阵列天线的带宽也基本表征了将其用作相控阵馈源的工作带宽.上述工作加深了对阵列天线带宽特性的理解,也为实际应用于射电望远镜系统的相控阵馈源实现更宽的工作带宽提供了可能.