以油体作为生物反应器的研究进展

获得安全、经济、稳定具有生物活性的重组蛋白,应用于基础研究及临床应用是一个重大的战略课题,现在可以利用酵母、细菌和动物细胞生产多种药物蛋白,但这些蛋白的生产过程还存在许多问题.利用植物作为生物反应器生产药用蛋白和疫苗是目前生物反应器研究的热点.油体蛋白在油料作物种子中高水平表达且易于分离,经过改造后是生产目的蛋白的一种理想栽体.介绍了油体、油体蛋白的结构以及利用植物油体蛋白表达体系这一新型植物生物反应器生产目的蛋白的研究进展和前景.     

兴安落叶松鞘蛾触角及其感器的扫描电镜观察

应用扫描电镜对兴安落叶松鞘蛾Coleophora obducta(Meyrick)触角及其感器进行观察和研究。结果表明,兴安落叶松鞘蛾触角为丝状,其上共有8种感器:板形感器、锥形感器、腔锥形感器、栓锥形感器、毛形感器、鳞形感器、叉形感器和Bhm氏鬃毛,对各种感器的形态、分布特点进行描述,推测其可能具有的功能。雌雄蛾触角有明显的性二型现象,表现为雌雄触角大小不同,触角感器类型、大小、数量、分布不同。     

Flight potential of Lygus lucorum (Meyer-Dür) (Heteroptera: Miridae)

Lygus lucorum (Meyer-Dür) is a key pest of Bt cotton in China. This study reports on its flight potential examined by a flight-mill system. We found that 10-d-old mated females engaged in flight over the greatest distance (40.1 +/- 5.2 km) and duration (7.7 +/- 1.0 h) in 24-h flight assays in relation to age, sex, and mating status. Optimum temperature for flight was 20 degrees C, and optimum relative humidity was 75% RH. Flight potential of 10-d-old mated females under the optimum conditions (20 degrees C and 75% RH) was tested continuously for 48 h. Results showed that the flight distance amounted to 67.3 +/- 9.7 km, with a maximum distance of 151.3 km. This study shows that L. lucorum has the potential to undertake long-distance flight. The information will help in the development of the forecast and management of L. lucorum.     

Establishment and characterization of dual-species biofilms formed from a 3,5-dinitrobenzoic-degrading strain and bacteria with high biofilm-forming capabilities.

In this study, the possibility of establishing a dual-species biofilm from a bacterium with a high biofilm-forming capability and a 3,5-dinitrobenzoic acid (3,5-DNBA)-degrading bacterium, Comamonas testosteroni A3, was investigated. Our results showed that the combinations of strain A3 with each of five strains with a high biofilm-forming capability (Pseudomonas sp. M8, Pseudomonas putida M9, Bacillus cereus M19, Pseudomonas plecoglossicida M21 and Aeromonas hydrophila M22) presented different levels of enhancement regarding biofilm-forming capability. Among these culture combinations, the 24-h dual-species biofilms established by C. testosteroni A3 with P. putida M9 and A. hydrophila M22 showed the strongest resistance to 3,5-DNBA shock loading, as demonstrated by six successive replacements with DMM2 synthetic wastewater. The degradation rates of 3,5-DNBA by these two culture combinations reached 63.3-91.6% and 70.7-89.4%, respectively, within 6 h of every replacement. Using the gfp-tagged strain M22 and confocal laser scanning microscopy, the immobilization of A3 cells in the dual-species biofilm was confirmed. We thus demonstrated that, during wastewater treatment processes, it is possible to immobilize degrader bacteria with bacteria with a high biofilm-forming capability and to enable them to develop into the mixed microbial flora. This may be a simple and economical method that represents a novel strategy for effective bioaugmentation.     

Processing of G4 DNA by Dna2 helicase/nuclease and replication protein A (RPA) provides insights into the mechanism of Dna2/RPA substrate recognition

The polyguanine-rich DNA sequences commonly found at telomeres and in rDNA arrays have been shown to assemble into structures known as G quadruplexes, or G4 DNA, stabilized by base-stacked G quartets, an arrangement of four hydrogen-bonded guanines. G4 DNA structures are resistant to the many helicases and nucleases that process intermediates arising in the course of DNA replication and repair. The lagging strand DNA replication protein, Dna2, has demonstrated a unique localization to telomeres and a role in de novo telomere biogenesis, prompting us to study the activities of Dna2 on G4 DNA-containing substrates. We find that yeast Dna2 binds with 25-fold higher affinity to G4 DNA formed from yeast telomere repeats than to single-stranded DNA of the same sequence. Human Dna2 also binds G4 DNAs. The helicase activities of both yeast and human Dna2 are effective in unwinding G4 DNAs. On the other hand, the nuclease activities of both yeast and human Dna2 are attenuated by the formation of G4 DNA, with the extent of inhibition depending on the topology of the G4 structure. This inhibition can be overcome by replication protein A. Replication protein A is known to stimulate the 5'- to 3'-nuclease activity of Dna2; however, we go on to show that this same protein inhibits the 3'- to 5'-exo/endonuclease activity of Dna2. These observations are discussed in terms of possible roles for Dna2 in resolving G4 secondary structures that arise during Okazaki fragment processing and telomere lengthening.     

Impacts of peripheral obestatin on colonic motility and secretion in conscious fed rats

Obestatin, a novel putative 23-amino acid peptide, was found to be derived from a mammalian preproghrelin gene by using a bioinformatics approach. Although the effects of obestatin on food intake and upper gut motility remain controversial, no studies have been carried out to explore its influence on lower gut motility and secretion. We investigated the impacts of intravenous (IV) injection of obestatin on rat colonic motor and secretory functions. Colonic transit time, fecal pellet output, and fecal content were measured in freely fed, conscious rats, which were chronically implanted with IV and colonic catheters. To test the validity of this animal model, human/rat corticotropin-releasing factor (h/rCRF) served as a stimulatory inducer of colonic motility and secretion. IV injection of obestatin (45, 100, and 300nmol/kg) did not affect the colonic transit time, whereas IV injection of h/rCRF (30nmol/kg) effectively accelerated colonic transit time. IV obestatin, in every dose we tested, also did not modify fecal pellet output, frequency of watery diarrhea, total fecal weight, fecal dried solid weight, or fecal fluid weight in the first hour after injection. On the other hand, IV injection of h/rCRF significantly enhanced fecal pellet output, as well as increased the frequency of watery diarrhea, total fecal weight, fecal dried solid weight, and fecal fluid weight during the first hour after injection compared with IV saline controls. In conclusion, peripheral obestatin administration has no impact on colonic motility and secretion in conscious fed rats.     

Biochemical characterization of two DNA ligases from Deinococcus radiodurans

Two genes encoding a NAD(+)-dependent DNA ligase (LigA) and an ATP-dependent DNA ligase (LigB) were identified in the genome of the extremely radioresistant bacterium, Deinococcus radiodurans (DR). The recombinant enzymes expressed in Escherichia coli, were purified to homogeneity and characterized. The optimal temperature and pH value of the two DNA ligases were 60 ( degrees )C and 7.0, respectively. Their optimal concentration of MgCl(2) was 5mM. Their half-lifes of heat inactivation at 100 ( degrees )C were about 3 min and 5 min, respectively. In addition, the results showed that DRLigB displayed higher activity than DRLigA at stick and blunt ended joining of DNA, indicating that DRLigB is a key DNA ligase of D. radiodurans in DNA recombination and double-strand break repair.     

The decapeptide CMS001 enhances swimming endurance in mice

Now peptides achieve distinct advantages over protein in biological application because of its quick and easy absorption, low power, and high activity. Some bioactive peptides had been developed to be used in the management of exercise-related disorders. In this study, we investigated whether the decapeptide CMS001 (Pro-Thr-Thr-Lys-Thr-Tyr-Phe-Pro-His-Phe) isolated from pig spleen had anti-fatigue effects. Male Balb/c mice were administered CMS001 (20 microg/(kgd)(-1) or 5 microg/(kgd)(-1) for 30 d, intraperitoneal injections) and tested in an exhaustive swim time task. In order to examine the mechanisms of CMS001 anti-fatigue effects, we analyzed liver glycogen stores, blood urea nitrogen (BUN) levels, lactic acid levels, ultrastructural integrity, and levels of both a free radical metabolite and an anti-oxidant enzyme. CMS001 treatment prolonged exhaustive swim time, increased liver glycogen levels, reduced BUN levels, and decreased accumulation of lactic acid in the blood, relative to mice injected with only saline. Examination of the ultrastructure of mitochondria and sarcoplasmic reticulum in skeletal and cardiac muscle of CMS001-treated and control mice revealed that CMS001 can reduce the damage to cardiac and skeletal muscle caused by an exhaustive swim challenge, such that the structure of most tissue specimens were normal in the peptide-treated group. Furthermore the free radical analysis after acute exercise indicated that CMS001 treatment decreased malondialdehyde (MDA) and increased superoxide dismutase (SOD) levels. The present findings indicate that the spleen-derived peptide CMS001 has anti-fatigue effects in mice, and further suggest that the mechanism may involve reduction of tissue damaging free radicals in muscle tissues.     

Remarkably low mtDNA control-region diversity and shallow population structure in Pacific cod Gadus macrocephalus

To investigate the genetic diversity and describe the population structure in Gadus macrocephalus, a 452 base pair (bp) fragment of the mitochondrial DNA control region was analysed in 259 individuals. The results showed remarkably low nucleotide diversity and a lack of genealogical structure. Small but significant genetic differentiations, however, were detected among north-western Pacific populations, but no large-scale regional differences were detected. These results indicate that populations of G. macrocephalus in the north-western Pacific are genetically subdivided and represent evolutionary lineages that should be managed individually.