Transgenic Arabidopsis thaliana plants expressing a ß-1,3-glucanase from sweet sorghum (Sorghum bicolor†L.) show reduced callose deposition and increased tolerance to aluminium toxicity.

Seventy-one cultivars of sweet sorghum (Sorghum bicolor L.) were screened for aluminium (Al) tolerance by measuring relative root growth (RRG). Two contrasting cultivars, ROMA (Al tolerant) and POTCHETSTRM (Al sensitive), were selected to study shorter term responses to Al stress. POTCHETSTRM had higher callose synthase activity, lower ß-1,3-glucanase activity and more callose deposition in the root apices during Al treatment compared with ROMA. We monitored the expression of 12 genes involved in callose synthesis and degradation and found that one of these, SbGlu1 (Sb03g045630.1), which encodes a ß-1,3-glucanase enzyme, best explained the contrasting deposition of callose in ROMA and POTCHETSTRM during Al treatment. Full-length cDNAs of SbGlu1 was prepared from ROMA and POTCHETSTRM and expressed in Arabidopsis thaliana using the constitutive cauliflower mosaic virus (CaMV) 35S promoter. Independent transgenic lines displayed significantly greater Al tolerance than wild-type plants and vector-only controls. This phenotype was associated with greater total ß-1,3-glucanase activity, less Al accumulation and reduced callose deposition in the roots. These results suggest that callose production is not just an early indicator of Al stress in plants but likely to be part of the toxicity pathway that leads to the inhibition of root growth.

Comparison of the clinical features of HIV-positive and HIV-negative hosts infected with Talaromyces marneffei: A multicenter, retrospective study.

OBJECTIVES: Talaromyces marneffei is an emerging pathogen, and the number of infections in HIV-negative individuals is rapidly increasing. Nevertheless, there is no sufficient comprehensive report on this issue, and awareness needs to be raised among clinicians. METHODS: We analyzed the differences in the clinical data of patients who are HIV-negative and HIV-positive with Talaromyces marneffei infection (TMI) from 2018 to 2022. RESULTS: A total of 848 patients were included, among whom 104 were HIV-negative. The obvious differences between the HIV-positive and HIV-negative groups were as follows: (i) the patients who are HIV-negative were older and more likely to exhibit cough and rash, (ii) the time in days from symptom onset to diagnosis among patients who are HIV-negative was longer, (iii) the laboratory findings and radiological presentations seemed more severe in patients who are HIV-negative, (iv) differences were observed regarding the underlying conditions and co-infection pathogens, and correlation analysis showed that correlations existed for many indicators, (v) and persistent infection was more likely to occur in patients who are HIV-negative. CONCLUSION: TMI in patients who are HIV-negative differs from that in patients who are HIV-positive in many aspects, and more investigations are needed. Clinicians should be more aware of TMI in patients who are HIV-negative.

[Manganese uptake and transportation as well as antioxidant response to excess manganese in plants].

Manganese (Mn) is an essential micronutrient throughout all stages of plant development. Mn plays an important role in many metabolic processes in plants. It is of particular importance to photosynthetic organisms in the chloroplast of which a cluster of Mn atoms at the catalytic centre function in the light-induced water oxidation by photosystem II, and also function as a cofactor for a variety of enzymes, such as Mn-SOD. But excessive Mn is toxic to plants which is one of the most toxic metals in acid soils. The knowledge of Mn(2+) uptake and transport mechanisms, especially the genes responsible for transition metal transport, could facilitate the understanding of both Mn tolerance and toxicity in plants. Recently, several plant genes were identified to encode transporters with Mn(2+) transport activity, such as zinc-regulated transporter/iron-regulated transporter (ZRT/IRT1)-related protein (ZIP) transporters, natural resistance-associated macrophage protein (Nramp) transporters, cation/H(+) antiporters, the cation diffusion facilitator (CDF) transporter family, and P-type ATPase. In addition, excessive Mn frequently induces oxidative stress, then several defense enzymes and antioxidants are stimulated to scavenge the superoxide and hydrogen peroxide formed under stress. Mn-induced oxidative stress and anti-oxidative reaction are very important mechanisms of Mn toxicity and Mn tolerance respectively in plants. This article reviewed the transporters identified as or proposed to be functioning in Mn(2+) transport, Mn toxicity-induced oxidative stress, and the response of antioxidants and antioxidant enzymes in plants to excessive Mn to facilitate further study. Meanwhile, basing on our research results, new problems and views are brought forward.

[Aluminum lightens the adverse effects of excessive Mn on growth of soybean (Glycine max)].

The influence of aluminum (Al) on physiological and biological characteristics of soybean under manganese (Mn) stress was investigated. The results showed that Al suppressed the transport of Mn to shoots (Fig.2B, C), and subsequently alleviated the inhibition of shoot growth (Fig.1), decreased the chlorophyll content (Fig.4). Addition of Al diminished the increase in O(-*)(2) producing rate, the hydrogen peroxide (H(2)O(2)) content and malondialdehyde (MDA) content, and activities of superoxide dismutase (SOD), guaiacol peroxidase (GPX), ascorbate peroxidase (APX) in soybean leaves caused by excessive Mn (Fig.5), and prevented the dropping of CAT activity to a low level under excessive Mn stress (Fig.6). Results of fractional analysis indicated that high levels of Al supply deduced mainly accumulation of Mn both in cell walls and organelles, but had no effect on it in soluble fractions (Fig.3).

[Organic acid secretion and its detoxification mechanism in plant roots under aluminum stress].

Phytotoxicity of Al is becoming one of the most serious problems in limiting plant growth on acid soils. Under Al stress, a number of plant species, cultivars or genotypes exhibit inheritable tolerance by organic acid secretion which is specific to Al stress and localized to the root apex. Citric acid, oxalic acid and malic acid are thought to be the most effective organic acids in detoxifying Al. Organic acid detoxifies Al both extracellular and intracellular. Two exudation patterns and their related speculation are introduced in this review. The possible factors responsible for the organic acid secretion are discussed, which are also the research focuses in this field. At last, we put forward our perspective in the field.

The risk factors of nosocomial infection in severe craniocerebral trauma.

OBJECTIVE: To explore the risk factors of nosocomial infection in severe craniocerebral trauma and the way of prevention. METHODS: The clinical data of 387 patients with severe craniocerebral trauma were reviewed. RESULTS: The total nosocomial infection rate of this study was 22.99%. Pulmonary nosocomial infection presented most frequently. The G-bacilli were the most common infectious bacteria. The mortality rate of the infection group was 38.20%. CONCLUSIONS: Complications of nosocomial infection affect the prognosis of craniocerebral trauma patients. Nosocomial infection is related to the age of the patients, craniocerebral trauma severity, unreasonable utilization of antibiotics and invasive operations, such as tracheal cannula, mechanical ventilation, urethral catheterization and deep venous catheterization. Patients with severe craniocerebral trauma should be carefully treated and nursed to avoid nosocomial infection. In order to reduce the rate of nosocomial infection, intensive measurement should be adopted.