TGFB1 stimulates the proliferation of quiescent oogonial stem cells in chicken.

In brief: Oogonial stem cells in the adult ovary can generate oocytes, but they are usually quiescent. TGFB1 is key in stimulating the proliferation of OSC, thereby ensuring the sustained reproductive potential in poultry species. Abstract: Oogonial stem cells (OSCs) are a type of germ stem cell present in the adult ovary. They have the ability to self-renew through mitosis and differentiate into oocytes through meiosis. We have previously identified a population of OSCs in the chicken ovary, but the underlying mechanisms controlling their activation and proliferation were unclear. In this study, we observed that OSCs showed robust proliferation when cultured on a layer of chicken embryo fibroblasts (CEF), suggesting that CEF may secrete certain crucial factors that activate OSC proliferation. We further detected TGFB1 as a potent signaling molecule to promote OSC proliferation. Additionally, we revealed the signaling pathways that play important roles downstream of TGFB1-induced OSC proliferation. These findings provide insights into the mechanisms underlying OSC proliferation in chickens and offer a foundation for future research on in situ activation of OSC proliferation in ovary and improvement of egg-laying performance in chickens.

Brillouin/Raman compensation of the Kerr-effect-induced bias in a nonlinear ring laser gyroscope.

In this Letter, the beat frequency at rest of a ring laser gyroscope with nonlinear effects is discussed in detail. Even without an additional intensity-stabilizing system, the random nullshift bias induced by the Kerr effect is compensated by the phase shift associated with the stimulated Brillouin/Raman scattering. And the nonlinear stimulated scattering also serves as the gain mechanism of the gyroscope. And thus the influence of the fluctuation of the injected pump intensity on the beat frequency is eliminated.

Complete optical on-chip isolation based on asymmetric stimulated Raman gain/loss.

In this Letter, we suggest an on-chip integrated isolator based on an add-drop filter with unidirectional Raman-induced gain (or loss). For the steady state, complete one-way propagation for monochromatic signals is realized in the bus waveguide. For transient transmission, the burr is suppressed. And the power consumption is reduced by enhancing the Q factor of the resonator at the control frequency.

Small-signal analysis of bidirectional operating characteristics in a Raman ring laser with external optical injections.

Employing the small-signal analysis, we study the bidirectional operating characteristics in a Raman ring laser. Bidirectional operation is found not stable in a silicon ring because of the existence of two-photon absorption. Using polar crystals which have different forward and backward Raman gain or introducing external optical injections helps to establish stable bidirectional operation in a Raman ring laser.

High-contrast light-by-light switching and AND gate based on nonlinear photonic crystals.

We present a light-by-light photonic crystal configuration consisting of a bend waveguide with three embedded Kerr-type nonlinear rods and a T-branch waveguide. We show that such a configuration can also demonstrate all-optical AND gate operation with extremely high-contrast between the OFF state and ON state in its transmission. Because the presented photonic crystal configuration of all-optical light-by-light switching is simple, this facilitates fabricating practical all-optical devices and further large-scale optical integration.