Small non-coding RNA RyhB is a key regulator of iron homeostasis in bacteria by sensing iron availability in the environment. Although RyhB is known to influence bacterial virulence by interacting with iron metabolism related regulators, its interaction with virulence genes, especially the Type III secretion system (T3SS), has not been reported. Here, we demonstrate that two RyhB paralogs of Salmonella enterica serovar Enteritidis upregulate Type III secretion system (T3SS) effectors, and consequently affect Salmonella invasion into intestinal epithelial cells. Specifically, we found that RyhB-1 modulate Salmonella response to stress condition of iron deficiency and hypoxia, and stress in simulated intestinal environment (SIE). Under SIE culture conditions, both RyhB-1 and RyhB-2 are drastically induced and directly upregulate the expression of T3SS effector gene sipA by interacting with its 5′ untranslated region (5′ UTR) via an incomplete base-pairing mechanism. In addition, the RyhB paralogs upregulate the expression of T3SS effector gene sopE. By regulating the invasion-related genes, RyhBs in turn affect the ability of S. Enteritidis to adhere to and invade into intestinal epithelial cells. Our findings provide evidence that RyhBs function as critical virulence factors by directly regulating virulence-related gene expression. Thus, inhibition of RyhBs may be a potential strategy to attenuate Salmonella.

Epitaxial SmNiO _{3− δ} thin films were fabricated under various oxygen partial pressures ( P O 2 ) on (0 0 1)-oriented LaAlO ₃ substrates by using the pulsed laser deposition method. Continuous control of the metal–insulator transition temperature ( T _MI ) from 350 K to 85 K was achieved by varying P O 2 from 26 Pa to 0.5 Pa. The reduction of T _MI can be attributed to the straightening-out of the out-of-plane Ni–O–Ni bond angle due to the elongation of unit cell volume with decreasing P O 2 . When P O 2 > 3 Pa, resistivity anomalies around 200 K are observed in the insulating phase of strained SmNiO _{3− δ} films, suggesting the onset of antiferromagnetic ordering of the Ni sublattices. An electronic phase diagram of the oxygen-deficient SmNiO _{3− δ} films has been established in this work based on the results of the transport measurements.

The AFE–FE phase transition was demonstrated in h-DyFeO₃ films with the lattice parameter c/a ratio of 1.90–1.92, which is intermediate between those of previously reported AFE and FE h-RFeO₃.