No abstract

Cd (cadmium) stress always alters the homeostasis of ROS (reactive oxygen species) including H2O2 (hydrogen sulfide) and O2•– (superoxide radical), leading to the oxidative injury and growth inhibition in plants. In addition to triggering oxidative injury, ROS has been suggested as important regulators modulating root elongation. However, whether and how Cd stress induces the inhibition of root elongation by differentially regulating endogenous H2O2 and O2•–, rather than by inducing oxidative injury, remains elusive. To address these gaps, histochemical, physiological, and biochemical approaches were applied to investigate the mechanism for Cd to fine-tune the balance between H2O2 and O2•– in the root tip of Brassica rapa. Treatment with Cd at 4 and 16 μM significantly inhibited root elongation, while only 16 μM but not 4 μM of Cd induced oxidative injury and cell death in root tip. Fluorescent and pharmaceutical tests suggested that H2O2 and O2•– played negative and positive roles, respectively, in the regulation of root elongation in the presence of Cd (4 μM) or not. Treatment with Cd at 4 μM led to the increase in H2O2 and the decrease in O2•– in root tip, which may be attributed to the up-regulation of Br_UPB1s and the down-regulation of their predicted targets (four peroxidase genes). Cd at 4 μM resulted in the increase in endogenous H2S in root tip by inducing the up-regulation of LCDs and DCDs. Treatment with H2S biosynthesis inhibitor or H2S scavenger significantly blocked Cd (4 μM)-induced increase in endogenous H2S level, coinciding with the recovery of root elongation, the altered balance between H2O2 and O2•–, and the expression of Br_UPB1s and two peroxidase genes. Taken together, it can be proposed that endogenous H2S mediated the phytotoxicity of Cd at low concentration by regulating Br_UPB1s-modulated balance between H2O2 and O2•– in root tip. Such findings shed new light on the regulatory role of endogenous H2S in plant adaptions to Cd stress.

No abstract

The outbreak of the 2019 new coronavirus pneumonia has caught worldwide attention. Since December 2019, several pneumonia cases of unknown origin have been found in hospitals in Wuhan, Hubei Province, China. The Chinese epidemic prevention authorities have quickly organised laboratories to conduct pathogen tests on alveolar lavage fluid, throat swabs, blood and other samples by methods of virus isolation, nucleic acid testing and genome sequencing, among others. On 7 January 2020, a novel coronavirus, previously undetected in humans, was isolated and its full genome sequence was decoded [1]. On 12 January 2020, the World Health Organization (WHO) officially named this new coronavirus causing the outbreak of pneumonia in Wuhan the "2019 new coronavirus (SARS-CoV-2)." Since the end of December 2019, the number of cases with SARS-CoV-2 infection has increased rapidly. As of 24:00 h on 13 February, there were 63 946 confirmed cases of SARS-CoV-2 acute respiratory disease in China and 162 confirmed cases in 26 other countries. WHO has classified this outbreak as a public health emergency of international concern. The outbreak of SARS-CoV-2 seriously endangers human health and life, affects the social order, and causes substantial economic losses. Currently, there are no effective drugs for SARS-CoV-2, and its primary treatment is only symptomatic and supportive. Critically ill patients are in danger at any time. Timely measures to prevent the occurrence of severe pneumonia and the development of acute respiratory distress syndrome (ARDS) are the key to the treatment of SARS-CoV-2. Although the pathogenesis of SARS-CoV-2 is unclear, its molecular mechanism of infecting human respiratory epithelial cells through the Spike protein is the same as that of SARS-CoV-1 and the symptoms caused by its infection are similar to those of severe acute respiratory syndrome (SARS). At the end of 2002, our hospital had hospitalised and cured the world's first SARS patient, and the total number of these cases admitted and confirmed would surpass 110. No hospitalised patients died and all were eventually discharged. Our hospital has gained meaningful experience in the treatment of severe pneumonia caused by coronavirus infection. To provide a reference for the treatment of SARS-CoV-2, we report the detailed history, onset, disease evolution, diagnosis and treatment of the first case of SARS-CoV-2 in Foshan, China. This patient was a 40-year-old man with no underlying disease other than hypertension. The patient had no recent travel history to Hubei Province or Wuhan but his wife had recently travelled to Wuhan and returned to Foshan City (Guangdong Province) on 6 January 2020. During her trip, she had a low fever and cough but symptoms were relieved within 1 week without any treatments. The patient went to Guangzhou South railway station, a crowded high-speed rail hub, to pick up his wife. On 10 January 2020, the patient began to get sick, with fever as the initial symptom. There was no discernible pattern of fever, and the highest temp...