The combination of uridine and nitrogen-deprivation promotes the efficient formation of astaxanthin-rich motile cells in Haematococcus pluvialis.

Astaxanthin accumulation in Haematococcus pluvialis typically occurs alongside the formation of secondary cell wall (SCW), hindering astaxanthin extraction and bio-accessibility. A potential solution lies in cultivating astaxanthin-rich motile cells lacking SCW. This study explored the influence and underlying mechanism of nitrogen-deprivation (ND) on SCW formation and established a connection between pyrimidine metabolism and SCW development. Then, various pyrimidine and ND combinations were examined to cultivate astaxanthin-rich motile cells. The results indicated that, compared to the nitrogen-replete group, the combination of uridine and ND increased the proportion of motile cells by 25-33 times, achieving 95 %, and enhanced astaxanthin yield by 26.52 %. Moreover, the efficiency of astaxanthin extraction from intact, wet motile cells was 91 % - 95 %, which was 5.6-9.0 times that from non-motile cells. This study not only presents a promising method for producing astaxanthin-rich motile cells in H. pluvialis but also provides insights into the relationship between pyrimidine metabolism and SCW development.

An Outbreak of SARS-CoV-2 Omicron Subvariant BA.2.76 in an Outdoor Park - Chongqing Municipality, China, August 2022.

What is already known about this topic?: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron subvariant has a stronger transmission capacity and faster transmission speed than the previous strain. What is added by this report?: The first coronavirus disease 2019 (COVID-19) case infected with the SARS-CoV-2 Omicron subvariant BA.2.76 who caused local transmission was reported in Chongqing Municipality on August 16, 2022. For 35 minutes, the Patient Zero jogged along a lake at a local park without wearing a mask. Among the 2,836 people potentially exposed at the time, 39 tested positive. Overall, 38 out of 39 cases did not wear a mask on the morning of August 16. All 39 cases lacked any previous exposure to the variant before testing positive on their nucleic acid test. What are the implications for public health practice?: It is essential to maintain personal wellbeing by ensuring one maintains personal protection and follows regulated guidelines such as maintaining safe distances from others both indoors and outdoors.

Synthesis of MCM-22 zeolite using rice husk as a silica source under varying-temperature conditions.

In this study, rice husk, an abundant agricultural byproduct, was utilized as an alternative silica source for the synthesis of MCM-22. The zeolite with high crystalline was synthesized using a three-stage varying-temperature hydrothermal method. The prepared silica and MCM-22 were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results showed that the duration required for zeolite crystallization was significantly decreased under varying-temperature conditions. The MCM-22 was in the form of thin platelet-like crystals, and no amorphous material existed in the framework of the MCM-22 after calcination and ammonium exchange. Cationic brilliant red 5GN, a basic dye used in the wool and blanket factories for fiber dyeing, was selected as the adsorptive to study the adsorption performance of the MCM-22. Adsorption experiments indicated that the maximum extent of adsorption was obtained at pH of 10, contact time of 60 min, and MCM-22 dose of 1.0 g/L. The adsorption kinetic has been described by first-order and pseudo-second-order models. It was observed that the rate of dye adsorption followed pseudo-second-order model.