[Exploration of yeast biodiversity and development of industrial applications].

Yeast are comprised of diverse single-cell fungal species including budding yeast Saccharomyces cerevisiae and various nonconventional yeasts. Budding yeast is well known as an important industrial microorganism, which has been widely applied in various fields, such as biopharmaceutical and health industry, food, light industry and biofuels production. In the recent years, various yeast strains from different ecological environments have been isolated and characterized. Novel species have been continuously identified, and strains with diverse physiological characteristics such as stress resistance and production of bioactive compounds were selected, which proved abundant biodiversity of natural yeast resources. Genome mining of yeast strains, as well as multi-omics analyses (transcriptome, proteome and metabolome, etc.) can reveal diverse genetic diversity for strain engineering. The genetic resources including genes encoding various enzymes and regulatory proteins, promoters, and other elements, can be employed for development of robust strains. In addition to exploration of yeast natural diversity, phenotypes that are more suitable for industrial applications can be obtained by generation of a variety of genetic diversity through mutagenesis, laboratory adaptation, metabolic engineering, and synthetic biology design. The optimized genetic elements can be used to efficiently improve strain performance. Exploration of yeast biodiversity and genetic diversity can be employed to build efficient cell factories and produce biological enzymes, vaccines, various natural products as well as other valuable products. In this review, progress on yeast diversity is summarized, and the future prospects on efficient development and utilization of yeast biodiversity are proposed. The methods and schemes described in this review also provide a reference for exploration of diversity of other industrial microorganisms and development of efficient strains.

Diversity of Cellulase-Producing Filamentous Fungi From Tibet and Transcriptomic Analysis of a Superior Cellulase Producer Trichoderma harzianum LZ117.

Filamentous fungi are widely used for producing cellulolytic enzymes to degrade lignocellulosic biomass. Microbial resources from Tibet have received great attention due to the unique geographic and climatic conditions in the Qinghai-Tibet Plateau. However, studies on cellulase producing fungal strains originated from Tibet remain very limited, and so far no studies have been focused on regulation of cellulase production of the specific strains thereof. Here, filamentous fungal strains were isolated from soil, plant, and other environments in Tibet, and cellulase-producing strains were further investigated. A total of 88 filamentous fungal strains were identified, and screening of cellulase-producing fungi revealed that 16 strains affiliated with the genera Penicillium, Trichoderma, Aspergillus, and Talaromyces exhibited varying cellulolytic activities. Among these strains, T. harzianum isolate LZ117 is the most potent producer. Comparative transcriptome analysis using T. harzianum LZ117 and the control strain T. harzianum K223452 cultured on cellulose indicated an intensive modulation of gene transcription related to protein synthesis and quality control. Furthermore, transcription of xyr1 which encodes the global transcriptional activator for cellulase expression was significantly up-regulated. Transcription of cre1 and other predicted repressors controlling cellulase gene expression was decreased in T. harzianum LZ117, which may contribute to enhancing formation of primary cellulases. To our knowledge, this is the first report that the transcription landscape at the early enzyme production stage of T. harzianum was comprehensively described, and detailed analysis on modulation of transporters, regulatory proteins as well as protein synthesis and processing was presented. Our study contributes to increasing the catalog of publicly available transcriptome data from T. harzianum, and provides useful clues for unraveling the biotechnological potential of this species for lignocellulosic biorefinery.

Schisandrin B protects human keratinocyte-derived HaCaT cells from tert-butyl hydroperoxide-induced oxidative damage through activating the Nrf2 signaling pathway.

Schisandrin B (Sch B), an active extract of Schisandra chinensis, has demonstrated antioxidant activity in a number of in vitro and in vivo models. In the present study, the capacity of Sch B to protect against oxidative injury in keratinocytes using the human keratinocyte­derived HaCaT cell line was investigated. To induce oxidative injury, tert­Butyl hydroperoxide (tBHP) was employed. The results indicate that Sch B efficiently reduced tBHP­induced cell death, reactive oxygen species (ROS) generation, protein oxidation, lipid peroxidation and DNA damage. Sch B also effectively attenuated the loss of mitochondrial membrane potential (MMP), and restored adenosine triphosphate (ATP) levels in tBHP­injured HaCaT cells. Furthermore, Sch B enhanced the expression of key antioxidant enzymes, including catalase, heme oxygenase­1, glutathione peroxidase, and superoxide dismutase, and further engaged the nuclear factor­erythroid 2­related factor 2 (Nrf2) signaling pathway by modulating its phosphorylation through activating multiple upstream kinases, including protein kinase B, adenosine monophosphate­activated protein kinase and mitogen­activated protein kinases (MAPKs). The present study suggests that Sch B provides a protective effect in keratinocytes in response to oxidative injury via reinforcing the endogenous antioxidant defense system. Therefore, it may be applied as an adjuvant therapy or in health foods to delay the skin aging process and the onset of skin diseases caused by oxidative stress.

[Wavelet entropy analysis for ictal electroencephalogram signals of child absence epilepsy].

The integral and individual-scale wavelet entropy of electroencephalogram (EEG) were employed to investigate the information complexity in EEG and to explore the dynamic mechanism of child absence epilepsy (CAE). The digital EEG signals were collected from patients with CAE and normal controls. Time-frequency features were extracted by continuous wavelet transformation. Individual scale power spectrum characteristics were represented by wavelet-transform. The integral and individual-scale wavelet entropy of EEG were computed on the basis of individual scale power spectrum. The evolutions of wavelet entropy across ictal EEG of CAE were investigated and compared with normal controls. The integral wavelet entropy of ictal EEG is lower than inter-ictal EEG for CAE, and it also lower than normal controls. The individual-scale wavelet entropies of 12th scale (centered at 3 Hz) of ictal EEG in CAE was significantly higher than normal controls. The individual-scale wavelet entropies for α band (centered at 10 Hz) of ictal EEG in CAE were much lower than normal controls. The integral wavelet entropy of EEG can be considered as a quantitative parameter of complexity for EEG signals. The complexity of ictal EEG for CAE is obviously declined in CAE. The wavelet entropies declined could become quantitative electrophysiological parameters for epileptic seizures, and it also could provide a theoretical basis for the study of neuromodulation techniques in epileptic seizures.

[Localization of epileptic foci in frontal lobe epilepsy and its surgical therapy].

OBJECTIVE: To analyze the clinical data and pre-operative examination results of frontal lobe epilepsy and combine with intra-operative intracranial electrical record in order to localize epileptic foci and to direct surgical therapy. METHODS: Preoperative EEG record and MRI scan were performed in 23 patients with refractory frontal lobe epilepsy. Among them, 17 patients received interictal 18F-FDG-PET-CT, 11 received MEG examination, 2 received functional MRI, 10 received surgical operation and intra-operative intracranial electrical record. RESULTS: The positive predictive value of clinical features of epileptic seizure, interictal EEG, ictal EEG, MRI and PET-CT were 56.52%, 56.52%, 60.87%, 54.55% and 94.12% respectively. Their consistent results helped to confirm the epileptogenic zone. MEG was more accurate than EEG. ECoE and VEEG monitoring was significant for operative guidance. CONCLUSION: A series of examinations is necessary for the diagnosis of epileptogenic zone of frontal lobe epilepsy. The surgical outcome is related to the accuracy of epileptic foci localization and the removal of epileptogenic zone.

[Stereotactic combined amygdala and hippocampus lesions for treatment of medial temporal lobe epilepsy].

OBJECTIVE: To explore the techniques of stereotactic combined amygdalohippocampotomy for management of medial temporal lobe epilepsy (MTLE). METHODS: The Leksell stereotactic frame was used for all cases, and which almost paralleled the long axis of hippocampus. Stereotactic amygdalohippocampotomy was performed in 23 patients with unilateral medial temporal lobe seizures by using magnetic resonance imaging (MRI) localization for target planning, depth electrode for the electroencephalogram (EEG) monitoring and radiofrequency techniques for lesion production. All procedures were completed under local anesthesia. RESULTS: Pre-lesion spikes or polyspike-waves complex were recorded by a depth electrode in the amygdala and hippocampus region in all patients, and the epileptiform discharges disappeared after the amygdalohippocampotomy. The MRI appearance of the lesion areas after 1 - 2 weeks surgical operation showed that mutiple areas of coagulation necrosis corresponding to the lesion sites were surrounded by zones of edema. Twenty-three patients were followed-up to 8 - 32 months with seizure free 43.48% (10/23), and the general efficiency (seizure reduction >or= 50%) was 91.30% (21/23 cases). CONCLUSIONS: Stereotactic combined lesions of unilateral amygdala and hippocampus for minimally invasive treatment of MTLE is safe and effective, and it is worth to spread in clinical application.