中国浙江省吻虾虎鱼属一新种(鲈形目:虾虎鱼科)

描述分布于浙江省武义县武义江的吻虾虎鱼1新种,定名为武义吻虾虎鱼(Rhinogobius wuyiensis)。该虾虎鱼在头部斑纹上与雀斑吻虾虎鱼(R.lentiginis)相近,但有如下特征可区别于相近种:具眼肩胛骨管及前鳃盖管(vs.无任何感觉管孔);椎骨数10 16=26(vs.27);臀鳍分支鳍条7-9(vs.6-7);头部斑点大小不等且不规则,常呈线状交织(vs.具规则的小圆斑);鳃盖条部内侧无斑点(vs.密布小点)。     

Aggregation of prion protein with insertion mutations is proportional to the number of inserts

Mutation in the prion gene, PRNP, accounts for approx. 10-15% of human prion diseases. However, little is known about the mechanisms by which a mutant prion protein (PrP) causes disease. We compared the biochemical properties of a wild-type human prion protein, rPrP(C) (recombinant wild-type PrP), which has five octapeptide-repeats, with two recombinant human prion proteins with insertion mutations, one with three more octapeptide repeats, rPrP(8OR), and the other with five more octapeptide repeats, rPrP(10OR). We found that the insertion mutant proteins are more prone to aggregate, and the degree and kinetics of aggregation are proportional to the number of inserts. The octapeptide-repeat and alpha-helix 1 regions are important in aggregate formation, because aggregation is inhibited with monoclonal antibodies that are specific for epitopes in these regions. We also showed that a small amount of mutant protein could enhance the formation of mixed aggregates that are composed of mutant protein and wild-type rPrP(C). Accordingly, rPrP(10OR) is also more efficient in promoting the aggregation of rPrP(C) than rPrP(8OR). These findings provide a biochemical explanation for the clinical observations that the severity of the disease in patients with insertion mutations is proportional to the number of inserts, and thus have implications for the pathogenesis of inherited human prion disease.     

Interaction of tau protein with the dynactin complex

Tau is an axonal microtubule-associated protein involved in microtubule assembly and stabilization. Mutations in Tau cause frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17), and tau aggregates are present in Alzheimer's disease and other tauopathies. The mechanisms leading from tau dysfunction to neurodegeneration are still debated. The dynein-activator complex dynactin has an essential role in axonal transport and mutations in its gene are associated with lower motor neuron disease. We show here for the first time that the N-terminal projection domain of tau binds to the C-terminus of the p150 subunit of the dynactin complex. Tau and dynactin show extensive colocalization, and the attachment of the dynactin complex to microtubules is enhanced by tau. Mutations of a conserved arginine residue in the N-terminus of tau, found in patients with FTDP-17, affect its binding to dynactin, which is abnormally distributed in the retinal ganglion cell axons of transgenic mice expressing human tau with a mutation in the microtubule-binding domain. These findings, which suggest a direct involvement of tau in axonal transport, have implications for understanding the pathogenesis of tauopathies.     

Normal cellular prion protein is a ligand of selectins: binding requires Le(X) but is inhibited by sLe(X)

The normal PrP(C) (cellular prion protein) contains sLe(X) [sialyl-Le(X) (Lewis X)] and Le(X). sLe(X) is a ligand of selectins. To examine whether PrP(C) is a ligand of selectins, we generated three human PrP(C)-Ig fusion proteins: one with Le(X), one with sLe(X), and the other with neither Le(X) nor sLe(X). Only Le(X)-PrP(C)-Ig binds E-, L- and P-selectins. Binding is Ca(2+)-dependent and occurs with nanomolar affinity. Removal of sialic acid on sLe(X)-PrP(C)-Ig enables the fusion protein to bind all selectins. These findings were confirmed with brain-derived PrP(C). The selectins precipitated PrP(C) in human brain in a Ca(2+)-dependent manner. Treatment of brain homogenates with neuraminidase increased the amounts of PrP(C) precipitated. Therefore the presence of sialic acid prevents the binding of PrP(C) in human brain to selectins. Hence, human brain PrP(C) interacts with selectins in a manner that is distinct from interactions in peripheral tissues. Alternations in these interactions may have pathological consequences.     

Overexpression of BLCAP induces S phase arrest and apoptosis independent of p53 and NF-κB in human tongue carcinoma

Bladder cancer-associated protein gene (BLCAP) is a novel candidate tumor suppressor gene identified from the human bladder carcinoma. Our previous studies have shown that BLCAP overexpression could inhibit cell growth by inducing apoptosis in HeLa cells [Zuo Z, Zhao M, Liu J, Gao G, Wu X: Tumor Biol 27: 221–226, 2006]. Such evidence suggests the alterations in BLCAP may play an important role in tumorigenesis. To further study the biological function of the BLCAP gene, we constructed a recombinant retroviral vector encoding BLCAP cDNA. Overexpressed BLCAP, via stable infection of exogenous BLCAP, resulted in growth inhibition of the human tongue cancer cell line Tca8113 in vitro, accompanied by S phase cell cycle arrest and apoptosis. The growth inhibition was correlated with up-regulation of p21^WAF1/CIP1 expression and down-regulation of Bcl-XL and Bcl-2 expressions. However, p53 expression and NF-κB activity remained unchanged post infection. Furthermore, no changes in p53 phosphorylation at Ser46 and nuclear localization, which are critical to p53 function, were observed in BLCAP-overexpressed cells. Taken together, BLCAP may play a role not only in regulating cell proliferation but also in coordinating apoptosis and cell cycle via a novel way independent of p53 and NF-κB. Jun Yao and Li Duan contributed equally to this work.     

Paired cloning vectors for complementation of mutations in the cyanobacterium<Emphasis Type="Italic"> Anabaena</Emphasis> sp. strain PCC 7120

The clones generated in a sequencing project represent a resource for subsequent analysis of the organism whose genome has been sequenced. We describe an interrelated group of cloning vectors that either integrate into the genome or replicate, and that enhance the utility, for developmental and other studies, of the clones used to determine the genomic sequence of the cyanobacterium, Anabaena sp. strain PCC 7120. One integrating vector is a mobilizable BAC vector that was used both to generate bridging clones and to complement transposon mutations. Upon addition of a cassette that permits mobilization and selection, pUC-based sequencing clones can also integrate into the genome and thereupon complement transposon mutations. The replicating vectors are based on cyanobacterial plasmid pDU1, whose sequence we report, and on broad-host-range plasmid RSF1010. The RSF1010- and pDU1-based vectors provide the opportunity to express different genes from either cell-type-specific or -generalist promoters, simultaneously from different plasmids in the same cyanobacterial cells. We show that pDU1 ORF4 and its upstream region play an essential role in the replication and copy number of pDU1, and that ORFs alr2887 and alr3546 (hetF _A ) of Anabaena sp. are required specifically for fixation of dinitrogen under oxic conditions.     

An inducible system for expression and validation of the specificity of short hairpin RNA in mammalian cells

RNA interference (RNAi) by means of short hairpin RNA (shRNA) has developed into a powerful tool for loss-of-function analysis in mammalian cells. The principal problem in RNAi experiments is off-target effects, and the most vigorous demonstration of the specificity of shRNA is the rescue of the RNAi effects with a shRNA-resistant target gene. This presents its own problems, including the unpredictable relative expression of shRNA and rescue cDNA in individual cells, and the difficulty in generating stable cell lines. In this report, we evaluated the plausibility of combining the expression of shRNA and rescue cDNA in the same vector. In addition to facilitate the validation of shRNA specificity, this system also considerably simplifies the generation of shRNA-expressing cell lines. Since the compensatory cDNA is under the control of an inducible promoter, stable shRNA-expressing cells can be generated before the knockdown phenotypes are studied by conditionally turning off the rescue protein. Conversely, the rescue protein can be activated after the endogenous protein is completely repressed. This approach is particularly suitable when prolonged expression of either the shRNA or the compensatory cDNA is detrimental to cell growth. This system allows a convenient one-step validation of shRNA and generation of stable shRNA-expressing cells.     

Nickel-Resistant Determinant from Leptospirillum ferriphilum

Leptospirillum ferriphilum strain UBK03 isolated from a mine in Jiangxi, China, is resistant to Ni²⁺ (30 to 40 mM). A four-gene nickel resistance cluster was identified and, when transformed into Escherichia coli, enabled growth in 6 mM nickel. Mutation experiments revealed that the genes ncrA, ncrB, and ncrC could confer nickel resistance in Escherichia coli, whereas the gene ncrY could have a negative effect on nickel resistance.     

Removal of agricultural non-point source pollutants by ditch wetlands: implications for lake eutrophication control

Ditches grown with nature reed (Phragmites communis Trin) and wild rice (Zizania latifolia Turcz) were selected to study the removal capacity of agricultural non-point source pollutants so as to find a way to alleviate eutrophication in Lake Taihu. Ditches sediment from depths below 40 cm can accumulate organic matter and total nitrogen (TN). TN is correlated positively to organic matter in reed populated sediment and wild rice populated sediment. This suggests that the main composition of TN is organic nitrogen derived from plant decomposition. A significant negative relationship between TN and pH was found in reed and wild rice sediments. Seasonal harvest of helophyte vegetation is an effective method to remove N and P from wetlands. Organic matter and TN concentrations in water and sediments (0–20 cm) in areas where reeds were removed are lower than non-harvested areas (control). Reeds and wild rice have high uptake ability of nitrogen (N) and phosphorus (P). However, the low economic value of these plants will not stimulate voluntary harvest of farmers. Zizania caduciflora Turez Hand-mazt is a kind of vegetable widely cultivated in ditches around the lake. It can also absorb N and P effectively. Thus, large scale cultivation of Z. caduciflora to replace nature plants may improve water quality.