<Emphasis Type="Italic">Dictyostelium</Emphasis> dynamin B modulates cytoskeletal structures and membranous organelles

Dictyostelium discoideum cells produce five dynamin family proteins. Here, we show that dynamin B is the only member of this group of proteins that is initially produced as a preprotein and requires processing by mitochondrial proteases for formation of the mature protein. Our results show that dynamin B-depletion affects many aspects of cell motility, cell-cell and cell-surface adhesion, resistance to osmotic shock, and fatty acid metabolism. The mature form of dynamin B mediates a wide range and unique combination of functions. Dynamin B affects events at the plasma membrane, peroxisomes, the contractile vacuole system, components of the actin-based cytoskeleton, and cell adhesion sites. The modulating effect of dynamin B on the activity of the contractile vacuole system is unique for the Dictyostelium system. Other functions displayed by dynamin B are commonly associated with either classical dynamins or dynamin-related proteins.     

The sheddase activity of ADAM17/TACE is regulated by the tetraspanin CD9

ADAM17/TACE is a metalloproteinase responsible for the shedding of the proinflammatory cytokine TNF-α and many other cell surface proteins involved in development, cell adhesion, migration, differentiation, and proliferation. Despite the important biological function of ADAM17, the mechanisms of regulation of its metalloproteinase activity remain largely unknown. We report here that the tetraspanin CD9 and ADAM17 partially co-localize on the surface of endothelial and monocytic cells. In situ proximity ligation, co-immunoprecipitation, crosslinking, and pull-down experiments collectively demonstrate a direct association between these molecules. Functional studies reveal that treatment with CD9-specific antibodies or neoexpression of CD9 exert negative regulatory effects on ADAM17 sheddase activity. Conversely, CD9 silencing increased the activity of ADAM17 against its substrates TNF-α and ICAM-1. Taken together, our results show that CD9 associates with ADAM17 and, through this interaction, negatively regulates the sheddase activity of ADAM17.     

Identification of a bacterial inhibitor against g-type lysozyme

Lysozymes are antibacterial effectors of the innate immune system in animals that hydrolyze peptidoglycan. Bacteria have evolved protective mechanisms that contribute to lysozyme tolerance such as the production of lysozyme inhibitors, but only inhibitors of chicken (c-) and invertebrate (i-) type lysozyme have been identified. We here report the discovery of a novel Escherichia coli inhibitor specific for goose (g-) type lysozymes, which we designate PliG (periplasmic lysozyme inhibitor of g-type lysozyme). Although it does not inhibit c- or i-type lysozymes, PliG shares a structural sequence motif with the previously described PliI and MliC/PliC lysozyme inhibitor families, suggesting a common ancestry and mode of action. Deletion of pliG increased the sensitivity of E. coli to g-type lysozyme. The existence of inhibitors against all major types of animal lysozyme and their contribution to lysozyme tolerance suggest that lysozyme inhibitors may play a role in bacterial interactions with animal hosts.     

Bafilomycin A1 activates respiration of neuronal cells via uncoupling associated with flickering depolarization of mitochondria

Bafilomycin A1 (Baf) induces an elevation of cytosolic Ca²⁺ and acidification in neuronal cells via inhibition of the V-ATPase. Also, Baf uncouples mitochondria in differentiated PC12 (_dPC12), _dSH-SY5Y cells and cerebellar granule neurons, and markedly elevates their respiration. This respiratory response in _dPC12 is accompanied by morphological changes in the mitochondria and decreases the mitochondrial pH, Ca²⁺ and ΔΨm. The response to Baf is regulated by cytosolic Ca²⁺ fluxes from the endoplasmic reticulum. Inhibition of permeability transition pore opening increases the depolarizing effect of Baf on the ΔΨm. Baf induces stochastic flickering of the ΔΨm with a period of 20 ± 10 s. Under conditions of suppressed ATP production by glycolysis, oxidative phosphorylation impaired by Baf does not provide cells with sufficient ATP levels. Cells treated with Baf become more susceptible to excitation with KCl. Such mitochondrial uncoupling may play a role in a number of (patho)physiological conditions induced by Baf.     

Altered expression of securin (Pttg1) and serpina3n in the auditory system of hearing-impaired Tff3-deficient mice

Introduction

Tff3 peptide exerts important functions in cytoprotection and restitution of the gastrointestinal (GI) tract epithelia. Moreover, its presence in the rodent inner ear and involvement in the hearing process was demonstrated recently. However, its role in the auditory system still remains elusive. Our previous results showed a deterioration of hearing with age in Tff3-deficient animals.

Results

Present detailed analysis of auditory brain stem response (ABR) measurements and immunohistochemical study of selected functional proteins indicated a normal function and phenotype of the cochlea in Tff3 mutants. However, a microarray-based screening of tissue derived from the auditory central nervous system revealed an alteration of securin (Pttg1) and serpina3n expression between wild-type and Tff3 knock-out animals. This was confirmed by qRT-PCR, immunostaining and western blots.

Conclusions

We found highly down-regulated Pttg1 and up-regulated serpina3n expression as a consequence of genetically deleting Tff3 in mice, indicating a potential role of these factors during the development of presbyacusis.     

Selection Optimal Drill Rigs by Grey Relational Analysis Method

Based upon the main properties of the relational analysis in grey system theory,a newmethod to select optimal drill rigs is proposed in this paper.Under the unified technique economicindex,with the practical data of four kinds of drill rigs in the mining district,east of Sichuan,China,an optimal reference number series was constructed.Through calculating the relational grade     

MCS: A Method for Finding the Number of Clusters

This paper proposes a maximum clustering similarity (MCS) method for determining the number of clusters in a data set by studying the behavior of similarity indices comparing two (of several) clustering methods. The similarity between the two clusterings is calculated at the same number of clusters, using the indices of Rand (R), Fowlkes and Mallows (FM), and Kulczynski (K) each corrected for chance agreement. The number of clusters at which the index attains its maximum is a candidate for the optimal number of clusters. The proposed method is applied to simulated bivariate normal data, and further extended for use in circular data. Its performance is compared to the criteria discussed in Tibshirani, Walther, and Hastie (2001). The proposed method is not based on any distributional or data assumption which makes it widely applicable to any type of data that can be clustered using at least two clustering algorithms.     

乳腺癌血清多肽图研究

乳腺癌一直是全世界范围内威胁妇女健康的恶性疾病, 尽管人们已经进行了大量的研究以减少乳腺癌对人类的危害, 但是乳腺癌仍然是目前导致死亡的恶性肿瘤之一. 乳腺癌的早期发现对于患者的愈后与生存意义重大, 可以明显提高病人生存时间、降低病人的死亡率. 据统计, 在过去的5年里, 早期诊断每年可减少3.2%因乳腺癌死亡的患者. 然而研究表明, 目前常用的乳腺癌诊断技术, 如乳腺X射线摄影和乳房检查均无法诊断出40%的早期乳癌患者和大多数年轻女性的乳腺肿瘤. 因此在乳腺癌临床治疗中, 急需发展新型的高效诊断技术.     

GaInP/GaAs/Ge三结叠层光电池光谱响应的温度特性

利用金属有机物化学气相沉积法(MOCVD)制备了转化效率达27.1%的GaInP/GaAs/Ge三结叠层电池, 并对其光谱响应的温度特性进行了测量研究. 通过光谱响应曲线观察到各子电池的吸收边随温度升高发生红移, 这主要归因于电池材料禁带宽度的变窄效应. 根据光谱响应数据计算得到的GaInP/GaAs/Ge叠层电池各子电池在室温下的短路电流密度分别为12.9, 13.7和17 mA/cm², 且叠层电池的短路电流密度的温度系数为8.9 μA/(cm²·℃). 最后, 根据叠层电池的串联结构推导了其电压温度系数为-6.27 mV/℃.