Sigma-1 receptor deficiency reduces MPTP-induced parkinsonism and death of dopaminergic neurons

Sigma-1 receptor (σ₁R) has been reported to be decreased in nigrostriatal motor system of Parkinson''s disease patients. Using heterozygous and homozygous σ₁R knockout (σ₁R^+/− and σ₁R^−/−) mice, we investigated the influence of σ₁R deficiency on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-impaired nigrostriatal motor system. The injection of MPTP for 5 weeks in wild-type mice (MPTP-WT mice), but not in σ₁R^+/− or σ₁R^−/− mice (MPTP-σ₁R^+/− or MPTP-σ₁R^−/− mice), caused motor deficits and ~40% death of dopaminergic neurons in substantia nigra pars compacta with an elevation of N-methyl-d-aspartate receptor (NMDAr) NR2B phosphorylation. The σ₁R antagonist NE100 or the NR2B inhibitor Ro25-6981 could alleviate the motor deficits and the death of dopaminergic neurons in MPTP-WT mice. By contrast, MPTP-σ₁R^+/− mice treated with the σ₁R agonist PRE084 or MPTP-σ₁R^−/− mice treated with the NMDAr agonist NMDA appeared to have similar motor deficits and loss of dopaminergic neurons as MPTP-WT mice. The pharmacological or genetic inactivation of σ₁R suppressed the expression of dopamine transporter (DAT) in substantia nigra, which was corrected by NMDA. The activation of σ₁R by PRE084 enhanced the DAT expression in WT mice or σ₁R^+/− mice. By contrast, the level of vesicular monoamine transporter 2 (VMAT2) in σ₁R^+/− mice or σ₁R^−/− mice had no difference from WT mice. Interestingly, MPTP-WT mice showed the reduction in the levels of DAT and VMAT2, but MPTP-σ₁R^−/− mice did not. The inactivation of σ₁R by NE100 could prevent the reduction of VMAT2 in MPTP-WT mice. In addition, the activation of microglia cells in substantia nigra was equally enhanced in MPTP-WT mice and MPTP-σ₁R^−/− mice. The number of activated astrocytes in MPTP-σ₁R^−/− mice was less than that in MPTP-WT mice. The findings indicate that the σ₁R deficiency through suppressing NMDAr function and DAT expression can reduce MPTP-induced death of dopaminergic neurons and parkinsonism.Parkinson''s disease (PD) is a neurodegenerative disorder characterized by motor symptoms, including bradykinesia and tremor, and a progressive loss of dopaminergic neurons in substantia nigra pars compacta (SNpc).^{1, 2} Sigma-1 receptor (σ₁R), previously named the opioid receptor sigma-1, is found primarily in motoneurons localized in the brainstem and spinal cord.³ The σ₁R is expressed in dopaminergic neurons and astrocytes.⁴ The σ₁R agonist PRE084 has been reported to exert neurorestorative effects on 6-hydroxydopamine (6-OHDA)-induced parkinsonism.⁴ Using positron emission tomography, the σ₁R-binding sites are found to be reduced in the brains of early-phase PD patients.⁵ However, the influence of σ₁R deficiency on the pathogenesis of PD has not yet been reported.Dopamine toxicity is involved in the etiology of PD.⁶ The σ₁R-binding sites on dopaminergic nerve terminals are involved in increasing dopamine release by enhancing N-methyl-d-aspartate receptors (NMDAr).⁷ The neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) metabolized to 1-methyl-4-phenylpyridinium in glial cells selectively impairs dopaminergic neurons in SNpc through disrupting respiratory enzymes and causing oxidative damage.⁸ The dopamine transporter (DAT), a high-affinity transmembrane protein, is responsible for dopamine reuptake from the synaptic cleft and the transportation of 1-methyl-4-phenylpyridinium into dopaminergic nerve terminals.⁹ The σ₁R is co-expressed with DAT in dopaminergic neurons.⁴ Furthermore, the low density of DAT has been confirmed in the brains of PD patients.⁵The activation of σ₁R enhances the Ca²⁺ influx across NMDAr through increasing the phosphorylation of NR2B or the trafficking NMDAr to the plasma membrane.^{10, 11} The NMDAr NR2B inhibitor can attenuate MPTP- or 6-OHDA-induced parkinsonian symptoms and neurodegeneration.¹² The σ₁R deficiency has been demonstrated to reduce Aβ-induced neuronal cell death through suppressing NR2B phosphorylation.¹³ The inflammation is a predominant aspect of PD, manifested by glial activation with the expression of pro-inflammatory mediators.¹⁴ Sustained neuro-inflammation can exacerbate the degeneration of dopaminergic neurons.¹⁵ The blockade of σ₁R has been reported to inhibit methamphetamine-induced astrogliosis.¹⁶ Moreover, the 6-OHDA-induced spontaneous rotations or decline of dopaminergic fibers in σ₁R knockout mice seem to be less than those in wild-type (WT) mice.⁴ Paquette et al. reported that the blockade of σ₁R could attenuate abnormal involuntary movements induced by 6-OHDA.¹⁷In this study, we employed heterozygous and homozygous σ₁R knockout (σ₁R^+/− and σ₁R^−/−) mice to investigate the influence of σ₁R deficiency on MPTP-induced parkinsonism and death of dopaminergic neurons, and the underlying molecular mechanisms. Using the experimental PD models of MPTP-treated σ₁R^+/− mice and σ₁R^−/− mice, the present study provides in vivo evidence that the σ₁R deficiency through suppressing NMDAr function and DAT expression can attenuate MPTP-induced dopaminergic neurodegeneration and parkinsonism.     

UPLC-MS/MS法同时测定益气养血口服液中的5种有效成分

建立了同时测定益气养血口服液中的淫羊藿苷、黄芪甲苷、黄芪皂苷域、五味子醇甲和麦冬皂苷D5种有效成分含量的超高效液相色谱-串联质谱(UPLC-MS/MS)分析方法,用Agilent Zorbax RRHD Eclipse Plus C18(50 mm×2.1 mm,1.8滋m)色谱柱,流动相：A相为乙腈溶液,B相为含0.2%甲酸的水溶液,流速为0.35 mL/min。在电喷雾电离(ESI)正离子模式下,采用的是多重反应监测模式(MRM)进行检测。结果表明,黄芪甲苷、黄芪皂苷域、淫羊藿苷、五味子醇甲和麦冬皂苷D的线性范围分别为0.003~12 mg/L、0.3~12 mg/L、0.009~18 mg/L、0.006~1.2 mg/L、0.003~3.0 mg/L;检出限分别为1滋g/L、1滋g/L、3滋g/L、2滋g/L、1滋g/L;5种成分的加样回收率为75.9%~104%;相对标准偏差均不大于3.8%。该方法简便、准确、快速、高灵敏度,已成功地用于实际的样品分析。     

Autophagy and apoptosis act as partners to induce germ cell death after heat stress in mice

Testicular heating suppresses spermatogenesis which is marked by germ cell loss via apoptotic pathways. Recently, it is reported that autophagy also can be induced by heat treatment in somatic cells. In this study, the status of autophagy in germ cells after heat treatment, as well as the partnership between autophagy and apoptosis in these cells was investigated. The results demonstrated that besides initiating apoptotic pathways, heat also induced autophagic pathways in germ cells. Exposure of germ cells to hyperthermia resulted in several specific features of the autophagic process, including autophagosome formation and the conversion of LC3-I to LC3-II. Furthermore, the ubiquitin-like protein conjugation system was implicated as being likely responsible for heat-induced autophagy in germ cells since all genes involving this system were found to be expressed in the testes. In addition, the upstream protein in this system, Atg7 (Autophagy-related gene 7), was found to be expressed in all types of spermatogenic cells, and its expression level was positively correlated with the level of autophagy in germ cells. As a result, Atg7 was selected as the investigative target to further analyze the role of autophagy in heat-induced germ cell death. It was shown that down expression of Atg7 protein resulted in the notable decrease in the level of autophagy in heat-treated germ cells, and this down-regulation of autophagy caused by Atg7 knockdown further reduced the apoptotic rate of germ cells. These results suggest that autophagy plays a positive role in the process of germ cell apoptosis after heat treatment. In conclusion, this study demonstrates that heat triggers autophagy and apoptosis in germ cells. These two mechanisms might act as partners, not antagonist, to induce cell death and lead to eventual destruction of spermatogenesis.     

Population, Diet and Conservation of Malayan Flying Lemurs in Altered and Fragmented Habitats in Singapore

The Malayan flying lemur (Cynocephalus variegatus) is a nocturnal mammalian arboreal folivore that inhabits the forests of Southeast Asia. Surveys were conducted from August to November 2003 to estimate the population density of Malayan flying lemurs for the first time in the Singapore Zoological Gardens. The study area consisting of Singapore Zoo and Night Safari was located in the Central Catchment Nature Reserve, where most of Singapore’s remaining natural forest is found. The Zoo consisted of 28 ha of landscaped habitat and the adjacent Night Safari consisted of 40 ha of secondary rainforest. The density estimates of flying lemurs in the Zoo and Night Safari were 15 and 24 individuals respectively. Seven plant species that were the preferred food items and an additional 10 plants that were common in the sites but not eaten by the flying lemurs were analysed to compare the mineral and phytochemical contents. Flying lemurs consumed leaves containing significantly less potassium and nitrogen but higher tannin (p < 0.05). The study shows that flying lemurs are able to survive in altered and fragmented landscapes. Conservation and management strategies are essential to protect the shrinking habitats in Singapore.     

Implications phylogénétiques de I'ultrastructure de la spermatogenèse, du spermatozoïde et de I'ovogenèse du TurbellariéUrastoma cyprinae ("Prolecithophora", Urastomidae)

Spermiogenesis in Urastoma cyprinae (Graff. 1882) involvcs a progressive lengthening of the spermatid. Free flagella are only transitory. The mature spermatozoon is fusibrm. 45μm in length and 2.5 μm in width. It contains two incorporated axonermes of the flatworm 9+"1" pattern, two elongated mitochondria. an elongated nucleus and a row or cortical longitudinal microtubules. Observations on oogenesis concerncd only the immuturc ovary. lmmature oocytes contain few dense granules and accssory cells were not ohserved. Phylogenetic implications of a biflagellate spermatozoon in a Prolecithophora are important. The presence of two 9 +"1" axonemes confirms that Urastoma (and the Prolecithophora) belongs to the taxon Trepaxonemata Ehlers. Previous electron microscope studies on spermitozoa of Prolecithophora (four genera) only dealt with aflagellate spermatozoa. On this basis, Ehlers (1985) proposed two autapomorphics for the taxon Prolecithophora: aflagellate spermatozoon and spermatozoal mitochondrial derivatives with abundant membranes. The present observations on Urastoma contradict these two autapomorphics. The taxon Prolecithophora cannot be defined by autapomorphies of the spermatozoon.     

Identification, fine mapping and characterization of Rht-dp, a recessive wheat dwarfing (reduced height) gene derived from Triticum polonicum

Semi-dwarfism is an agronomically important trait in breeding for resistance to damage by wind and rain (lodging resistance) and for stable high yields. Dwarf Polish wheat (Triticum polonicum L., 2n = 4x = 28, AABB AS304) is a potential donor of dwarfing and other traits for common wheat improvement. A genetic analysis using an F₂ population derived from a cross of AS304 and tall cultivar AS302 and derived F_2:3 lines indicated that AS304 carries a recessive dwarfing gene, temporarily designated Rht-dp. Molecular markers and bulked segregant analysis were used to characterize and map the gene. Eight polymorphic SSR markers (Xwmc511, Xgwm495, Xgwm 113, Xgwm192, Xgpw7026, Xgpw3017, Xgpw1108 and Xgpw7521) on chromosome arm 4BS and two AFLP markers (M ₈ /E ₅ and M ₄ /E ₃ ) were mapped relative to the dwarfing locus. The closest linked markers, Xgpw3017 and M ₈ /E ₅ at 0.5 and 3.5 cM, respectively, from Rht-dp will enable its marker assisted transfer to wheat breeding populations. Allelic tests indicated that Rht-dp was allelic to Rht-B1b; hence it may be an alternative allele at the Rht-B1 locus.     

Molecular and cytological evidences for the natural wheatgrass hybrids occurrence and origin in west China

Interspecies hybridization has been frequently observed in the tribe Triticeae. Natural hybridization between Kengyilia and Roegneria or Elymus species has not been reported as yet. Several sterile wheatgrass individuals exhibiting intermediately morphological traits between Kengyilia and Roegneria or Elymus species were identified in the meadow of Sichuan and Gansu provinces in China, suggesting their natural hybrid origin. The putative hybrids were analyzed by using the sequences of ITS and trnH-psbA together with cytological observation in order to assess the origin of hybrids. Both ITS and cytological data revealed the evidence of allopolyploid origin and confirmed the presence of StStYYP and StStYYHP genomes in the putative natural hybrids. The data suggest that the StStYYP hybrid originated from hybridization between Kengyilia and Roegneria and the hybrid with StStYYHP originated from hybridization between Kengyilia and Elymus. Chloroplast sequence data demonstrated that K. rigidula and K. melanthera were the likely maternal donors in the hybridization events.     

Evolutionary patterns of hind wing morphology in dung beetles (Coleoptera: Scarabaeinae)

The shape of wings can be a good predictor of adaptations to different selective pressures and the value of wing features in taxonomy and phylogeny has long been recognized. In our investigation of the hind wing evolution of dung beetles (Scarabaeinae) we use geometric morphometrics combined with a cladistic approach. The variations of entire hind wings and of three specific regions of 80 dung beetle species were investigated using 19 landmarks and outline data. Extensive evidence indicates that the wing as a whole and the three separate regions were under different selective pressures. The detailed evolutionary patterns of the three regions and the reconstruction of the ancestral forms were computed by mapping the geometric morphometrics data onto a tree based on a cladistic character analysis.