A study of a novel self-fertility mechanism in the hermaphroditic nematode Rhabditis sp. SB347

Germ cell development and gametogenesis are essential for the continuity of future generations in most eukaryotic organisms, including humans. One well-established system for studying the complex mechanisms of gametogenesis is the nematode species, Caenorhabditis elegans. The fact that C. elegans hermaphrodite germlines undergo different cellular development at the same life stage in a linear progression makes C. elegans a model system for the study of the conversion of uncommitted germ cells into either oocytes or sperm. C. elegans hermaphrodite produces spermatocytes during the final larval stage and then makes a one-time switch over to oogenesis as the worm enters adulthood. Recently our lab made the surprising discovery that hermaphrodites of another nematode species, Rhabditis sp. SB347, evolved an alternative mechanism for achieving self-fertility. In Chapter one, we describe that the germline in R. sp. SB347 hermaphrodites is capable of producing both sperm and oocytes from the final larval stage throughout adulthood. Along the length of SB347 hermaphrodite germline, we found clusters of distinct “mystery cells” that divide mitotically outside of stem cell. These “mystery cells” serve as spermatocyte progenitors and share features of spermatogonial cells that are key components of sperm production in other organisms, including Drosophila, mice and humans. Our finding is significant for the understanding of germ cell development because it reveals a completely new reproductive characteristic that is not present in C. elegans but in other model organisms. In Chapter two, we look at further characterization of spermatogonial cells using a key molecular player known as fem-3 binding factor (FBF). Previously described to regulate both mitosis/meiosis switch and oocyte/sperm determination in Caenorhabditis elegans, FBF belongs to PUF (Pumilio and FBF) protein family and shares a conserved role of germline stem cell regulation. We report the presence of FBF in both the distal germline and the spermatogonia, and unexpectedly, in late maturing oocytes. Our results highlight SB347 spermatogonial cells as an intermediate stage of partially committed spermatocyte progenitors that remain features of germline stem cells. Through this study of the first reported case of spermatogonial cells in the phylum nematode, we hope to extend our knowledge of germline stem cell development to decipher features of stem cell differentiation and provide more insights with broader, medical implications

The effect of emotion regulation on happiness and resilience of university students: The chain mediating role of learning motivation and target positioning

ObjectiveTo investigate the effect andmechanism among emotion regulation, relationship,happiness, learning motivation, target positioning, and resilience of university students.MethodA total of 904 university students in China were included in this cross-sectional survey from April to May this year. The self-administered questionnaires, including the adapted Mental Health Scale with a Healthy Personality Orientation for College Students, were used to construct structural equations to test the chain mediating effects of learning motivation and target positioning based on a multi-stage whole group sample of university students.ResultEmotion regulation indirectly affected happiness through the mediating effect of interpersonal relationship (Med = −0.387, p = 0.001). Learning motivation and target positioning play the chain mediating role in the effect of emotion regulation on happiness (Med = −0.307, p = 0.001) and resilience (Med = −0.275, p = 0.001).ConclusionEmotion regulation indirectly affected happiness and resilience through the chain mediating effect of learning motivation and target positioning

A universal and improved mutation strategy for iterative wavefront shaping

Recent advances in iterative wavefront shaping (WFS) techniques have made it possible to manipulate the light focusing and transport in scattering media. To improve the optimization performance, various optimization algorithms and improved strategies have been utilized. Here, a novel guided mutation (GM) strategy is proposed to improve optimization efficiency for iterative WFS. For both phase modulation and binary amplitude modulation, considerable improvements in optimization effect and rate have been obtained using multiple GM-enhanced algorithms. Due of its improvements and universality, GM is beneficial for applications ranging from controlling the transmission of light through disordered media to optical manipulation behind them.Comment: 5 pages with 6 figure

Concurrent Disruption of the Ras/MAPK and NF-κB Pathways Induces Circadian Deregulation and Hepatocarcinogenesis.

UNLABELLED: The Ras/Erk and NF-κB pathways play critical roles in cell proliferation and are known to drive oncogenesis when overactivated. Herein we report a gatekeeper function of the two pathways by working in synergy to suppress liver tumorigenesis. Hepatocyte-specific deletion of both Shp2/Ptpn11 and Ikkβ in mice, which promote Ras/Erk and NF-κB signaling, respectively, exacerbated chemical carcinogenesis and even triggered spontaneous development of hepatocellular carcinoma (HCC). We show that the unanticipated severe tumor phenotype was contributed collectively by severe cholestasis, metabolic changes, upregulated cell-cycle progression, and disruption of circadian rhythm in mutant hepatocytes. Remarkably, human HCCs with dysregulated circadian gene expression displayed downregulation of Ras/Erk and NF-κB signaling and poor prognosis. Together, these data indicate that at the ground state, the two central pathways, previously known as oncogenic, cooperate to sustain tumor-suppressive physiologic homeostasis and to prevent hepatic damage. Disruption of this intricate signaling network is carcinogenic in the liver. IMPLICATIONS: We demonstrate here that basal levels of the Ras/MAPK and NF-κB pathways, while promoting tumorigenesis if overactivated, are required to maintain physiologic homeostasis and regulate circadian rhythm in the liver, which are antitumorigenic

De-Pinning Transition of Bubble Phases in a High Landau Level

While in the lowest Landau level the electron-electron interaction leads to the formation of the Wigner crystal, in higher Landau levels a solid phase with multiple electrons in a lattice site of crystal was predicted, which was called the bubble phase. Reentrant integer quantum Hall states are believed to be the insulating bubble phase pinned by disorder. We carry out nonlinear transport measurements on the reentrant states and study the de-pinning of the bubble phase, which is complementary to previous microwave measurements and provides unique information. In this study, conductivity is directly measured with Corbino geometry. Based on the threshold electric field of de-pinning, a phase diagram of the reentrant state is mapped. We discuss an interaction-driven topological phase transition between the integer quantum Hall state and the reentrant integer quantum Hall state.Comment: 11 pages, 3 figure

TWIN: TWo-stage Interest Network for Lifelong User Behavior Modeling in CTR Prediction at Kuaishou

Life-long user behavior modeling, i.e., extracting a user's hidden interests from rich historical behaviors in months or even years, plays a central role in modern CTR prediction systems. Conventional algorithms mostly follow two cascading stages: a simple General Search Unit (GSU) for fast and coarse search over tens of thousands of long-term behaviors and an Exact Search Unit (ESU) for effective Target Attention (TA) over the small number of finalists from GSU. Although efficient, existing algorithms mostly suffer from a crucial limitation: the \textit{inconsistent} target-behavior relevance metrics between GSU and ESU. As a result, their GSU usually misses highly relevant behaviors but retrieves ones considered irrelevant by ESU. In such case, the TA in ESU, no matter how attention is allocated, mostly deviates from the real user interests and thus degrades the overall CTR prediction accuracy. To address such inconsistency, we propose \textbf{TWo-stage Interest Network (TWIN)}, where our Consistency-Preserved GSU (CP-GSU) adopts the identical target-behavior relevance metric as the TA in ESU, making the two stages twins. Specifically, to break TA's computational bottleneck and extend it from ESU to GSU, or namely from behavior length $10^2$ to length $10^4-10^5$, we build a novel attention mechanism by behavior feature splitting. For the video inherent features of a behavior, we calculate their linear projection by efficient pre-computing \& caching strategies. And for the user-item cross features, we compress each into a one-dimentional bias term in the attention score calculation to save the computational cost. The consistency between two stages, together with the effective TA-based relevance metric in CP-GSU, contributes to significant performance gain in CTR prediction.Comment: Accepted by KDD 202

A fluorinated bihydrazide conjugate for activatable sensing and imaging of hypochlorous acid by 19F NMR/MRI.

Hypochlorous acid (HClO) is one of the most important reactive oxygen species (ROS) and plays a vital role in many physiological and pathological processes. The comprehensive exploration of mechanistic details and the potential clinical translation necessitate the development of reliable probes for prompt and accurate detection of HClO in complex biological environments. Herein we report a fluorinated bihydrazide conjugate as a 19F NMR/MRI probe with a "turn-on" character for the detection of HClO. This probe could selectively respond to HClO, leading to a significant recovery of 19F signals for 19F NMR/MRI. Activatable sensing and imaging of HClO were achieved with SMMC-7721 cells and nude mice, which demonstrates that this small molecular conjugate could serve as a selective probe for real-time sensing and imaging of HClO in biological systems

Observation of a Helical Luttinger-Liquid in InAs/GaSb Quantum Spin Hall Edges

We report on the observation of a helical Luttinger-liquid in the edge of InAs/GaSb quantum spin Hall insulator, which shows characteristic suppression of conductance at low temperature and low bias voltage. Moreover, the conductance shows power-law behavior as a function of temperature and bias voltage. The results underscore the strong electron-electron interaction effect in transport of InAs/GaSb edge states. Because of the fact that the Fermi velocity of the edge modes is controlled by gates, the Luttinger parameter can be fine tuned. Realization of a tunable Luttinger-liquid offers a one-dimensional model system for future studies of predicted correlation effects.Comment: 23 pages, 9 figure