Enhancing cold and drought tolerance in cotton: a protective role of SikCOR413PM1.

The present study explored the potential role of cold-regulated plasma membrane protein COR413PM1 isolated from Saussurea involucrata (Matsum. & Koidz)(SikCOR413PM1), in enhancing cotton (Gossypium hirsutum) tolerance to cold and drought stresses through transgenic methods. Under cold and drought stresses, the survival rate and the fresh and dry weights of the SikCOR413PM1-overexpressing lines were higher than those of the wild-type plants, and the degree of leaf withering was much lower. Besides, overexpressing SikCOR413PM1 overexpression increased the relative water content, reduced malondialdehyde content and relative conductivity, and elevated proline and soluble sugar levels in cotton seedlings. These findings suggest that SikCOR413PM1 minimizes cell membrane damage and boosts plant stability under challenging conditions. Additionally, overexpression of this gene upregulated antioxidant enzyme-related genes in cotton seedlings, resulting in enhanced antioxidant enzyme activity, lowered peroxide content, and reduced oxidative stress. SikCOR413PM1 overexpression also modulated the expression of stress-related genes (GhDREB1A, GhDREB1B, GhDREB1C, GhERF2, GhNAC3, and GhRD22). In field trials, the transgenic cotton plants overexpressing SikCOR413PM1 displayed high yields and increased environmental tolerance. Our study thus demonstrates the role of SikCOR413PM1 in regulating stress-related genes, osmotic adjustment factors, and peroxide content while preserving cell membrane stability and improving cold and drought tolerance in cotton.

[Toxic effects of nano-TiO2 on Gymnodinium breve].

In order to reveal the toxicity and mechanism of nano-TiO2 on algae, the inhibition effect, enzyme activity, oxygen free radicals of nano-TiO2 on the growth of G. breve were investigated. The results showed that G. breve was inhibited by nano-TiO2, and the 72 h-EC50 was 9.7 mg x L(-1). With the increasing concentration of nano-titanium dioxide, the activities of SOD decrease significantly (P < 0.05). The content of hydrogen peroxide radicals and the activities of CAT increase significantly (P < 0.05), and the content of superoxide anion shows the increasing trend. The content of hydrogen peroxide radicals was 0.083 U x mL(-1) in 0 mg x L(-1) nano-TiO2 suspension while that was 1.1 U x mL(-1) in control after 48 h. Through the study of 20 mg x L(-1) nano-titanium dioxide on G. breve at different times, the activities of SOD and CAT, the content of MDA are consistent, which the highest values is achieved at the exposure time of 12 hours and the lowest value is found at the exposure time of 48 hours. The content of hydroxyl radical increased significantly at the exposure time of 48 hours. The activity of SOD was 0.14 U x (10(7) cell x min)(-1) in G. breve at 12 h which was ten times higher than that at 48 h.

Detection of the neurotoxin BMAA within cyanobacteria isolated from freshwater in China.

The cyanobacterial neurotoxin, beta-N-methylamino-l-alanine (BMAA), has been suggested as an important environmental factor for neurodegenerative disease such as amyotrophic lateral sclerosis- Parkinsonism dementia complex (ALS/PDC) in Guam. BMAA was detected within the majority of cyanobacterial isolates surveyed in both free and symbiotic cyanobacteria, living in freshwater as well as marine environments. In this study, we report two methods using liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS/MS) each coupled with a different type of hydrophilic interaction liquid chromatography (HILIC) column to detect BMAA. A third method using AQC-derivatized BMAA was also used for comparison. Axenic cultures of Microcystis aeruginosa and Nostoc sp. isolated from Chinese freshwater were analyzed for both free and protein-bound BMAA at the exponential growth stage. Cultures of two strains of M. aeruginosa collected at four growth stages were also analyzed for the presence of BMAA. BMAA was detected in the Nostoc sp. at very low concentrations (<0.07pmoles on column) only when precolumn AQC derivatization was used. No BMAA was detected in the Chinese derived axenic cultures of Microcystis; detection limits for the LC-ESI-MS and LC-ESI-MS/MS without precolumn derivatization were 10ng and 2pg BMAA on column, respectively. We suggest that cyanobacteria grown under some culture conditions may be relatively free of BMAA.