[Clinical characteristics of "classical" and "non-classical" paraneoplastic neurological syndrome]

Objective: To explore the clinical features of classical and non-classical paraneoplastic neurological syndrome (PNS). Methods: From 2015 to 2020, 48 cases of definite PNS admitted to the First Affiliated Hospital of University of Science and Technology of China were retrospectively collected, and classification, clinical characteristics, onconeural antibodies and primary tumors were analyzed. The included cases were divided into classical and non-classical groups according to Graus criteria, and the differences of clinical characteristics, onconeural antibodies, combined tumors, time of diagnosis and mortality were compared between the two groups. Results: Among the 48 confirmed patients, 21 (43.8%) were positive for well-characterized onconeural antibodies. There were 28 cases (58.3%) and 20 cases (41.7%) in classic and non-classical PNS groups, respectively. No significant differences of age, sex, clinical involvement site, characteristic positive antibody type, tumor diagnosis rate and follow-up mortality were found between the two groups (all P>0.05). The time of diagnosis in the non-classical PNS group was 3.0 (2.0, 6.5) months, which was significantly longer than that in the classical PNS group 1.0(0.6, 3.0) months (P<0.05). Meanwhile, the combination rate of non-characteristic antibodies in the classical PNS group (10 cases, 35.7%) was significantly higher than that in the non-classical PNS group (1 case, 5.0%) (P=0.016). During the follow-up, 39 patients (81.3%) with tumor were confirmed, and 29 patients (60.4%) were diagnosed with PNS before the tumor was found. Conclusions: The"non-classical"PNSs are common in clinical settings. Diagnosis may be delayed due to the nonclassical symptoms of the patients. When patients have clinical symptoms related to PNS, onconeural antibodies should be detected and the relevant tumors should also be screened. Patients have positive antibodies but with no tumors should be closely followed up for more than 5 years.

CrGNAT gene regulates excess copper accumulation and tolerance in Chlamydomonas reinhardtii

Excess copper (Cu) in environment affects the growth and metabolism of plants and green algae. However, the molecular mechanism for regulating plant tolerance to excess Cu is not fully understood. Here, we report a gene CrGNAT enconding an acetyltransferase in Chlamydomonas reinhardtii and identified its role in regulating tolerance to Cu toxicity. Expression of CrGNAT was significantly induced by 75-400μM Cu. The top induction occurred at 100μM. Transgenic algae overexpressing CrGNAT (35S::CrGNAT) in C. reinhardtii showed high tolerance to excess Cu, with improved cell population, chlorophyll accumulation and photosynthesis efficiency, but with low degree of oxidation with regard to reduced hydrogen peroxide, lipid peroxides and non-protein thiol compounds. In contrast, CrGNAT knock-down lines with antisense led to sensitivity to Cu stress. 35S::CrGNAT algae accumulated more Cu and other metals (Zn, Fe, Cu, Mn and Mg) than wild-type, whereas the CrGNAT down-regulated algae (35S::AntiCrGNAT) had moderate levels of Cu and Mn, but no effects on Zn, Fe and Mg accumulation as compared to wild-type. The elevated metal absorption in CrGNAT overexpression algae implies that the metals can be removed from water media. Quantitative RT-PCR analysis revealed that expression of two genes encoding N-lysine histone methyltransferases was repressed in 35S::CrGNAT algae, suggesting that CrGNAT-regulated algal tolerance to Cu toxicity is likely associated with histone methylation and chromatin remodeling. The present work provided an example a basis to develop techniques for environmental restoration of metal-contaminated aquatic ecosystems.

HISN3 mediates adaptive response of Chlamydomonas reinhardtii to excess nickel

Investigation of genes for heavy metal [e.g. nickel (Ni) and zinc (Zn)] absorption and detoxification in green algae is of great importance because some of the metals have become one of the major contaminants in the aquatic ecosystem. In plants, overload of heavy metals modifies many aspects of biological processes. However, the mechanisms by which heavy metals exert detrimental effects are not fully understood. The present study identified a biological role for HISN3 (the gene coding for phosphoribosylformimino-5-aminoimidazole carboxamide ribonucleotide isomerase) in regulating the response of Chlamydomonas reinhardtii, a unicellular green alga, to Ni toxicity. In higher plants, HISN3 encodes an enzyme catalyzing the fourth step in the histidine biosynthesis pathway, but its functional importance is yet to be identified. Transgenic algae overexpressing HISN3 in C. reinhardtii showed high tolerance to excess Ni, with a 48.3-57.4% increase in cell population and moderate histidine accumulation compared with the wild type. HISN3 overexpression improved accumulation of Chl and photosynthesis efficiency, but suppressed Ni-induced generation of reactive oxygen species and lipid peroxides. Interestingly, more Ni and other metals [Zn, iron (Fe), copper (Cu), manganese (Mn) and magnesium (Mg)] were accumulated in HISN3-overexpressing cells than in the wild type. In contrast, RNA interference of HISN3 depressed Ni accumulation but caused cellular sensitivity to Ni. The elevated metal absorption in the HISN3-overexpressing algae implies that the metals can be removed from water media. Thus, our work presents an example for algae genetically designed to improve tolerance to metal toxicity and environmental restoration of metal-contaminated aquatic ecosystems.