AMPK-dependent and -independent coordination of mitochondrial function and muscle fiber type by FNIP1.

Mitochondria are essential for maintaining skeletal muscle metabolic homeostasis during adaptive response to a myriad of physiologic or pathophysiological stresses. The mechanisms by which mitochondrial function and contractile fiber type are concordantly regulated to ensure muscle function remain poorly understood. Evidence is emerging that the Folliculin interacting protein 1 (Fnip1) is involved in skeletal muscle fiber type specification, function, and disease. In this study, Fnip1 was specifically expressed in skeletal muscle in Fnip1-transgenic (Fnip1Tg) mice. Fnip1Tg mice were crossed with Fnip1-knockout (Fnip1KO) mice to generate Fnip1TgKO mice expressing Fnip1 only in skeletal muscle but not in other tissues. Our results indicate that, in addition to the known role in type I fiber program, FNIP1 exerts control upon muscle mitochondrial oxidative program through AMPK signaling. Indeed, basal levels of FNIP1 are sufficient to inhibit AMPK but not mTORC1 activity in skeletal muscle cells. Gain-of-function and loss-of-function strategies in mice, together with assessment of primary muscle cells, demonstrated that skeletal muscle mitochondrial program is suppressed via the inhibitory actions of FNIP1 on AMPK. Surprisingly, the FNIP1 actions on type I fiber program is independent of AMPK and its downstream PGC-1α. These studies provide a vital framework for understanding the intrinsic role of FNIP1 as a crucial factor in the concerted regulation of mitochondrial function and muscle fiber type that determine muscle fitness.

Cideb controls sterol-regulated ER export of SREBP/SCAP by promoting cargo loading at ER exit sites.

SREBPs are master regulators of lipid homeostasis and undergo sterol-regulated export from ER to Golgi apparatus for processing and activation via COPII-coated vesicles. While COPII recognizes SREBP through its escort protein SCAP, factor(s) specifically promoting SREBP/SCAP loading to the COPII machinery remains unknown. Here, we show that the ER/lipid droplet-associated protein Cideb selectively promotes the loading of SREBP/SCAP into COPII vesicles. Sterol deprivation releases SCAP from Insig and enhances ER export of SREBP/SCAP by inducing SCAP-Cideb interaction, thereby modulating sterol sensitivity. Moreover, Cideb binds to the guanine nucleotide exchange factor Sec12 to enrich SCAP/SREBP at ER exit sites, where assembling of COPII complex initiates. Loss of Cideb inhibits the cargo loading of SREBP/SCAP, reduces SREBP activation, and alleviates diet-induced hepatic steatosis. Our data point to a linchpin role of Cideb in regulated ER export of SREBP and lipid homeostasis.

Coupling of COPII vesicle trafficking to nutrient availability by the IRE1α-XBP1s axis.

The cytoplasmic coat protein complex-II (COPII) is evolutionarily conserved machinery that is essential for efficient trafficking of protein and lipid cargos. How the COPII machinery is regulated to meet the metabolic demand in response to alterations of the nutritional state remains largely unexplored, however. Here, we show that dynamic changes of COPII vesicle trafficking parallel the activation of transcription factor X-box binding protein 1 (XBP1s), a critical transcription factor in handling cellular endoplasmic reticulum (ER) stress in both live cells and mouse livers upon physiological fluctuations of nutrient availability. Using live-cell imaging approaches, we demonstrate that XBP1s is sufficient to promote COPII-dependent trafficking, mediating the nutrient stimulatory effects. Chromatin immunoprecipitation (ChIP) coupled with high-throughput DNA sequencing (ChIP-seq) and RNA-sequencing analyses reveal that nutritional signals induce dynamic XBP1s occupancy of promoters of COPII traffic-related genes, thereby driving the COPII-mediated trafficking process. Liver-specific disruption of the inositol-requiring enzyme 1α (IRE1α)-XBP1s signaling branch results in diminished COPII vesicle trafficking. Reactivation of XBP1s in mice lacking hepatic IRE1α restores COPII-mediated lipoprotein secretion and reverses the fatty liver and hypolipidemia phenotypes. Thus, our results demonstrate a previously unappreciated mechanism in the metabolic control of liver protein and lipid trafficking: The IRE1α-XBP1s axis functions as a nutrient-sensing regulatory nexus that integrates nutritional states and the COPII vesicle trafficking.

Variation of floret development and grain setting characteristics in winter wheat responses to delayed sowing.

BACKGROUND: Wheat floret development has been a focus of research due to a desire to improve spike fertility, which majorly influences grain yield. Sowing date plays a vital role on grain yield in wheat, and increase in the grain number per spike of winter wheat (Triticum aestivum L.) has been obtained by delayed sowing. During the 2014-2015 and 2015-2016 growing seasons, variation in these developmental patterns was explored involving two winter wheat cultivars (Jimai 22 and Tainong 18) and five sowing dates (24 September; 1, 8, 15 and 22 October). RESULTS: We noticed clear differences in the grain number per spikelet; delayed sowing had a greater impact on the number of fertile florets at anthesis than grain set. Significant differences in the developmental patterns of florets among spikelet positions corresponded to variations in the floret developmental rate, with faster floret development associated with higher floret fertility. Delayed sowing did not affect the grain number near the rachis, but significantly promoted grain set on distal florets. Increased spike dry weight (SDW) did not compensate for floret size or grain weight, mainly due to enhanced assimilate partitioning to florets. CONCLUSION: Delayed sowing significantly affects floret developmental dynamics, causing differences in winter wheat floret fertility. An increased SDW concomitant with improved intra-spike partitioning before anthesis contributes to increase the distal floret numbers per spike and then optimize winter wheat spike fertility. © 2022 Society of Chemical Industry.

Chemoproteomic Profiling Reveals Ethacrynic Acid Targets Adenine Nucleotide Translocases to Impair Mitochondrial Function.

Ethacrynic acid (EA) is a diuretic drug that is widely used to treat high-blood pressure and swelling caused by congestive heart failure or kidney failure. It acts through noncovalent inhibition of the Na+-K+-2Cl- cotransporter in the thick ascending limb of Henle's loop. Chemically, EA contains a Michael acceptor group that can react covalently with nucleophilic residues in proteins; however, the proteome reactivity of EA remains unexplored. Herein, we took a quantitative chemoproteomic approach to globally profile EA's targets in cancer cells. We discovered that EA induces impaired mitochondrial function accompanied by increased ROS production. Our profiling revealed that EA targets functional proteins on mitochondrial membranes, including adenine nucleotide translocases (ANTs). Site-specific mapping identified that EA covalently modifies a functional cysteine in ANTs, a mutation of which resulted in the rescuing effect on EA-induced mitochondrial dysfunction. The newly discovered modes of action offer valuable information to repurpose EA for cancer treatment.

Endosperm and amyloplast development in waxy wheat cultivars.

The endosperm is an essential part of wheat grains, and the accumulation of amyloplasts in endosperm determines the quality of wheat. Because waxy wheat has a special starch quality, there is a need to understand differences in endosperm and starch morphologies among waxy wheat cultivars. This study investigated differences in the endosperm and amyloplasts of two near-isogenic lines (Shimai19-P and Shimai19-N) and the wheat cultivar Shimai19 during various growth stages using light microscopy and scanning electron microscopy. At 8 days after pollination (DAP), with endosperm development, the amyloplast distributions in the different endosperm regions of the three wheat varieties were in the following order: center of ventral endosperm > subaleurone of ventral endosperm > center of dorsal endosperm > modified aleurone > subaleurone of dorsal endosperm. At 16 DAP, small amyloplasts appeared in the endosperm cells in all three wheat cultivars; subsequently, endosperm cell development until maturity was more rapid in Shimai19-N than in the other varieties. This study revealed variations in amyloplast accumulation among endosperm regions and waxy wheat varieties during wheat grain development, which improved the understanding of nutrient accumulation and nutrient transfer of wheat grains.

Voltage-dependent anion channel involved in the α-synuclein-induced dopaminergic neuron toxicity in rats.

Inclusion bodies containing the neural protein α-synuclein (α-syn) are observed in several neurodegenerative diseases, including Parkinson's disease (PD). Furthermore, over-expression of α-syn in rat brain partly mimics the neuropathological and behavioral features of PD by triggering the degeneration of dopaminergic neurons in the substantia nigra (SN). Mitochondrial dysfunction is also central to PD pathogenesis, and α-syn is found in the mitochondria. However, the precise mechanisms of α-syn-induced neurotoxicity remain elusive. To examine the potential mechanisms of α-syn-induced neurodegeneration, we over-expressed α-syn in the SN of rats using a recombinant adeno-associated viral vector (rAAV-syn). Immunohistochemical and immunogold labeling results indicated that α-syn was successfully over-expressed in the SN and striatum after vector injection. The number of tyrosine hydroxylase-positive (dopaminergic) neurons was significantly reduced in rats injected with rAAV-syn when compared with control rats. Compared with control rats, the density of α-syn-conjugated gold particles was greater in the axons, cytoplasm, nuclei, and notably also in the mitochondria of SN neurons in rAAV-syn-injected rats. In addition, SN neurons transfected with rAAV-syn exhibited swollen mitochondria with discontinuous outer membranes and internal vacuole-like structures, strongly suggesting α-syn-induced mitochondrial dysfunction. Mitochondria in rAAV-syn-injected rats were also observed in autophagosomes. α-Syn co-immunoprecipitated with voltage-dependent anion channel 1 (VDAC1), a component of the mitochondrial permeability transition pore (mPTP) that induces mitochondrial uncoupling and apoptosis. Over-expression of α-syn may cause the degeneration of dopaminergic neurons through an interaction with mitochondrial VDAC1, which leads to mPTP activation, mitochondrial uncoupling, and cell death.

Manganese regulation of COPII condensation controls circulating lipid homeostasis.

Precise control of circulating lipids is instrumental in health and disease. Bulk lipids, carried by specialized lipoproteins, are secreted into the circulation, initially via the coat protein complex II (COPII). How the universal COPII machinery accommodates the abundant yet unconventional lipoproteins remains unclear, let alone its therapeutic translation. Here we report that COPII uses manganese-tuning, self-constrained condensation to selectively drive lipoprotein delivery and set lipid homeostasis in vivo. Serendipitously, adenovirus hijacks the condensation-based transport mechanism, thus enabling the identification of cytosolic manganese as an unexpected control signal. Manganese directly binds the inner COPII coat and enhances its condensation, thereby shifting the assembly-versus-dynamics balance of the transport machinery. Manganese can be mobilized from mitochondria stores to signal COPII, and selectively controls lipoprotein secretion with a distinctive, bell-shaped function. Consequently, dietary titration of manganese enables tailored lipid management that counters pathological dyslipidaemia and atherosclerosis, implicating a condensation-targeting strategy with broad therapeutic potential for cardio-metabolic health.

Mitochondrial proteostasis stress in muscle drives a long-range protective response to alleviate dietary obesity independently of ATF4.

Mitochondrial quality in skeletal muscle is crucial for maintaining energy homeostasis during metabolic stresses. However, how muscle mitochondrial quality is controlled and its physiological impacts remain unclear. Here, we demonstrate that mitoprotease LONP1 is essential for preserving muscle mitochondrial proteostasis and systemic metabolic homeostasis. Skeletal muscle-specific deletion of Lon protease homolog, mitochondrial (LONP1) impaired mitochondrial protein turnover, leading to muscle mitochondrial proteostasis stress. A benefit of this adaptive response was the complete resistance to diet-induced obesity. These favorable metabolic phenotypes were recapitulated in mice overexpressing LONP1 substrate ΔOTC in muscle mitochondria. Mechanistically, mitochondrial proteostasis imbalance elicits an unfolded protein response (UPRmt) in muscle that acts distally to modulate adipose tissue and liver metabolism. Unexpectedly, contrary to its previously proposed role, ATF4 is dispensable for the long-range protective response of skeletal muscle. Thus, these findings reveal a pivotal role of LONP1-dependent mitochondrial proteostasis in directing muscle UPRmt to regulate systemic metabolism.

TMEM41B acts as an ER scramblase required for lipoprotein biogenesis and lipid homeostasis.

How amphipathic phospholipids are shuttled between the membrane bilayer remains an essential but elusive process, particularly at the endoplasmic reticulum (ER). One prominent phospholipid shuttling process concerns the biogenesis of APOB-containing lipoproteins within the ER lumen, which may require bulk trans-bilayer movement of phospholipids from the cytoplasmic leaflet of the ER bilayer. Here, we show that TMEM41B, present in the lipoprotein export machinery, encodes a previously conceptualized ER lipid scramblase mediating trans-bilayer shuttling of bulk phospholipids. Loss of hepatic TMEM41B eliminates plasma lipids, due to complete absence of mature lipoproteins within the ER, but paradoxically also activates lipid production. Mechanistically, scramblase deficiency triggers unique ER morphological changes and unsuppressed activation of SREBPs, which potently promotes lipid synthesis despite stalled secretion. Together, this response induces full-blown nonalcoholic hepatosteatosis in the TMEM41B-deficient mice within weeks. Collectively, our data uncovered a fundamental mechanism safe-guarding ER function and integrity, dysfunction of which disrupts lipid homeostasis.

Receptor-Mediated ER Export of Lipoproteins Controls Lipid Homeostasis in Mice and Humans.

Efficient delivery of specific cargos in vivo poses a major challenge to the secretory pathway, which shuttles products encoded by ∼30% of the genome. Newly synthesized protein and lipid cargos embark on the secretory pathway via COPII-coated vesicles, assembled by the GTPase SAR1 on the endoplasmic reticulum (ER), but how lipid-carrying lipoproteins are distinguished from the general protein cargos in the ER and selectively secreted has not been clear. Here, we show that this process is quantitatively governed by the GTPase SAR1B and SURF4, a high-efficiency cargo receptor. While both genes are implicated in lipid regulation in humans, hepatic inactivation of either mouse Sar1b or Surf4 selectively depletes plasma lipids to near-zero and protects the mice from atherosclerosis. These findings show that the pairing between SURF4 and SAR1B synergistically operates a specialized, dosage-sensitive transport program for circulating lipids, while further suggesting a potential translation to treat atherosclerosis and related cardio-metabolic diseases.

ChREBP-ß regulates thermogenesis in brown adipose tissue.

Brown adipose tissue (BAT) plays a critical role in energy expenditure by uncoupling protein 1 (UCP1)-mediated thermogenesis. Carbohydrate response element-binding protein (ChREBP) is one of the key transcription factors regulating de novo lipogenesis (DNL). As a constitutively active form, ChREBP-ß is expressed at extremely low levels. Up to date, its functional relevance in BAT remains unclear. In this study, we show that ChREBP-ß inhibits BAT thermogenesis. BAT ChREBP-ß mRNA levels were elevated upon cold exposure, which prompted us to generate a mouse model overexpressing ChREBP-ß specifically in BAT using the Cre/LoxP approach. ChREBP-ß overexpression led to a whitening phenotype of BAT at room temperature, as evidenced by increased lipid droplet size and decreased mitochondrion content. Moreover, BAT thermogenesis was inhibited upon acute cold exposure, and its metabolic remodeling induced by long-term cold adaptation was significantly impaired by ChREBP-ß overexpression. Mechanistically, ChREBP-ß overexpression downregulated expression of genes involved in mitochondrial biogenesis, autophagy, and respiration. Furthermore, thermogenic gene expression (e.g. Dio2, UCP1) was markedly inhibited in BAT by the overexpressed ChREBP-ß. Put together, our work points to ChREBP-ß as a negative regulator of thermogenesis in brown adipocytes.

[Effect of plant density on population yield and economic output value in maize-soybean intercropping].

The effects of plant density on population yield and economic output value in maize and soybean intercropping were studied with the design of the double saturated D-optimal regression. A mathematical model was developed, in which the densities of maize and soybean were independent variables, and population grain yield, dry matter accumulation and economic output value were dependent variables, respectively. The result showed that the plant density significantly affected the population grain yield, dry matter accumulation and economic output value, and the effects of density of maize on population indices were greater than those of density of soybean. Under the low level conditions of density, the population grain yield, dry matter accumulation and economic output value increased with the density of maize and soybean. The maximum population grain yield was 8101.31 kg · hm(-2) the optimized combination of 72023 plant maize · hm(-2) and 99924 plant soybean · hm(-2), while the maximum population dry matter accumulation was 15282.45 kg · hm(-2) with the optimized combination of 75000 plant maize · hm(-2) and 93372 plant soybean · hm(-2), and the maximum population economic output value was 23494.50 Yuan · hm(-2) with the optimized combination of 73758 plant maize · hm(-2) and 87597 plant soybean · hm(-2). The optimum combination of densities of maize and soybean calculated by computer were 58554-71547 plant · hm(-2) for maize and 82217-100303 plant · hm(-2) for soybean in order to obtain grain yield greater than 7500 kg · hm(-2), dry matter accumulation greater than 14250 kg · hm(-2) and economic output value greater 22500 yuan · hm(-2) under the condition of this experiment.

[Characteristics of farmland eco-environment at the intercropping stage of maize intercropped with winter wheat and their effects on seedling growth of summer maize].

To study the farmland eco-environment of intercropping maize with wheat at the intercropping stage and its influence on maize seedling growth, two summer maize cultivars, Zhengdan 958 and Denghai 661, were either intercropped with wheat or directly seeded. The result demonstrated that there was little difference for the soil water content of the farmland between the two cultivation methods. The highest soil temperature of intercropped maize was 4.8-5.2 °C lower than the soil temperature of directly-seeded maize, and the lowest temperature of the intercropped maize was 1.4-1.7 °C lower. But, the temperatures for both planting methods met the requirement for seed germination. Light intensity on the ground surface of the intercropped maize was 4.4%-10.6% less than natural light, and insufficient light was the main reason for the weak and late seedling. Compared to the directly-seeded maize, the speeds of seed germination and accumulation of dry matters of the intercropped maize were relatively slow. On the whole, the seedling of intercropped maize was not strong, which presented small leaves, short height and low chlorophyll content. The restraint on the growth of intercropped maize was enhanced with the extension of intercropping period. For farm planting, direct-seeding could improve the seed germination and seedling growth of summer maize.

ULK1 and JNK are involved in mitophagy incurred by LRRK2 G2019S expression.

Mutations in LR RK2 (Leucine rich repeat kinase 2) are a major cause of Parkinson's disease (PD). We and others reported recently that expression of the pathogenic gainof-function mutant form of LRRK2, LRRK2 G2019S, induces mitochondrial fission in neurons through DLP1. Here we provide evidence that expression of LRRK2 G2019S stimulates mitochondria loss or mitophagy. We have characterized several LRRK2 interacting proteins and found that LRRK2 interacts with ULK1 which plays an essential role in autophagy. Knockdown of either ULK1 or DLP1 expression with shRNAs suppresses LRRK2 G2019S expression-induced mitochondrial clearance, suggesting that LRRK2 G2019S expression induces mitochondrial fission through DLP1 followed by mitophagy via an ULK1 dependent pathway. In addition to ULK1, we found that LRRK2 interacts with the endogenous MKK4/7, JIP3 and coordinates with them in the activation of JNK signaling. Interestingly, LRRK2 G2019S-induced loss of mitochondria can also be suppressed by 3 different JNK inhibitors, implying the involvement of the JNK pathway in the pathogenic mechanism of mutated LRRK2. Thus our findings may provide an insight into the complicated pathogenesis of PD as well as some clues to the development of novel therapeutic strategies.

POSH localizes activated Rac1 to control the formation of cytoplasmic dilation of the leading process and neuronal migration.

The formation of proximal cytoplasmic dilation in the leading process (PCDLP) of migratory neocortical neurons is crucial for somal translocation and neuronal migration, processes that require the elaborate coordination of F-actin dynamics, centrosomal movement, and nucleokinesis. However, the underlying molecular mechanisms remain poorly understood. Here, we show that the Rac1-interacting scaffold protein POSH is essential for neuronal migration in vivo. We demonstrate that POSH is concentrated in the PCDLP and that knockdown of POSH impairs PCDLP formation, centrosome translocation, and nucleokinesis. Furthermore, POSH colocalizes with F-actin and the activated form of Rac1. Knockdown of POSH impairs F-actin assembly and delocalizes activated Rac1. Interference of Rac1 activity also disrupts F-actin assembly and PCDLP formation and perturbs neuronal migration. Thus, we have uncovered a mechanism by which POSH regulates the localization of activated Rac1 and F-actin assembly to control PCDLP formation and subsequent somal translocation of migratory neurons.

α-Synuclein overexpression impairs mitochondrial function by associating with adenylate translocator.

α-Synuclein (α-syn), a protein involved in the pathogenesis of Parkinson's disease (PD), is known to accumulate in mitochondria, disrupt mitochondrial function. However, the molecular mechanisms that link these pathological responses have not been investigated. In rats overexpressing α-syn in the substantia nigra (SN) through adeno-associated virus (AAV) transduction, about 50% of tyrosine hydroxylase positive neurons were lost after 24 weeks. Overexpression of α-syn was also associated with morphological deformation of mitochondria and depolarization of the mitochondrial membrane potential (ΔΨm). Both co-immunoprecipitation and confocal microscopy demonstrated that mitochondrial α-syn associated with adenylate translocator (ANT), a component of the mitochondrial permeability transition pore (mPTP). The depolarization of ΔΨm was partially reversed in vitro by bongkrekic acid (BKA), an inhibitor of ANT, suggesting that the molecular association between α-syn and ANT facilitated ΔΨm depolarization. Concomitant with α-syn accumulation in mitochondria, abnormal mitochondrial morphology, ΔΨm depolarization, and loss of TH-positive neurons, there was a decrease in apoptosis-inducing factor (AIF) within the mitochondrial matrix, suggesting possible translocation to the cytosol. Our findings suggest that overexpression of α-syn may cause mitochondrial defects in dopaminergic neurons of the substantia nigra through an association with adenylate translocator and activation of mitochondria-dependent cell death pathways. Disruption of normal mitochondrial function may contribute to the loss of dopaminergic neurons in Parkinson's disease.

[Effects of cropping patterns on photosynthesis characteristics of summer maize and its utilization of solar and heat resources].

In order to investigate the effects of interplanting and direct seeding on the photosynthesis characteristics of summer maize and its utilization of solar and heat resources, two summer maize cultivars (Zhengdan 958 and Denghai 661) were planted in the farmlands of Denghai Seed Co. Ltd in Laizhou City of Shandong Province, with 67500 plants x hm(-2) and three sowing dates. The above-ground biomass, plant growth rate, leaf area index, and net photosynthetic rate per ear leaf were measured to reveal the photosynthesis characteristics of test cultivars. In the meantime, the characters of grain-filling were simulated by Richards' model, and the solar resource utilization efficiency of the cultivars was calculated, in combining with meteorological data. Comparing with interplanting, direct seeding increased the grain yield by 1.17%-3.33%, but decreased the thousand-grain weight significantly. Growth stages were extended under earlier sowing. The leaf area index and net photosynthetic rate from flowering to 30 d after anthesis were significantly higher under direct seeding than under interplanting, but after then, they decreased faster. Direct seeding induced a higher accumulation of dry matter and a faster plant growth rate before and after flowering. Under direct seeding, the maximum grain-filling rate reached earlier, the starting potential was higher, but the grain-filling period, active grain-filling period, and W(max) were lower, compared with those under interplanting. Also under direct seeding, the total accumulative temperature and solar radiation during growth period decreased by 150-350 degrees C x d and 200-400 MJ x m(-2), respectively, but the solar resource utilization efficiency of grain increased by 10.5%-24.7%. All the results suggested that direct seeding was superior to interplanting for the summer maize production under field condition. In order to enhance solar and heat utilization efficiency and excavate yield potential, it would be essential to improve the leaf photosynthesis efficiency and postpone leaf aging.

Semi-quantitative analysis of alpha-synuclein in subcellular pools of rat brain neurons: an immunogold electron microscopic study using a C-terminal specific monoclonal antibody.

Alpha-synuclein (alpha-Syn) is a brain-enriched protein of 140 amino acids. Despite of strong evidence showing the implication of the protein in the pathogenesis of several neurodegenerative diseases, its physiological function remains poorly understood. To study the physiological function of alpha-Syn, a depiction of its precise subcellular localization is necessary. Although alpha-Syn expression in the brain has been extensively investigated using several different antibodies, its precise subcellular localization in neurons remains elusive. In this study, immunogold electron microscopy with a newly produced 3D5 monoclonal antibody recognizing the C-terminal 115-121 amino acids of alpha-Syn was used to examine its subcellular localization in rat brain neurons. In addition, the relative amount of the protein in different subcellular pools of the neurons in several brain regions was evaluated and compared. The results showed that alpha-Syn-positive gold particles were unevenly distributed in axons, presynaptic terminals, cytoplasm and nucleus in the neuron, with the density of gold particles being greater in presynaptic terminals and nucleus than in other subcellular pools. In the cytoplasmic region, relatively dense gold particles were seen in some mitochondria. In the same subcellular pools, the density of gold particles was varied among the neurons from different brain regions. Although the cortical neurons showed much higher density of gold particles in the presynaptic terminals and nuclei than in striatal, hippocampal and substantia nigral neurons, the density of gold particles in their mitochondria was much lower compared with the mitochondria of striatal, hippocampal and substantia nigral neurons. The relative high level of mitochondrial alpha-Syn in hippocampus, striatum and substantia nigral neurons may have special pathophysiological significance, which deserves further investigation.