Design and comparison of gene-pyramiding schemes in animals

Marker-assisted gene pyramiding provides a promising way to develop new animal breeds or lines, in which genes responsible for certain favorable characters identified in different breeds or lines are incorporated. In consideration of features of animal populations, we proposed five schemes for pyramiding three genes, denoted Scheme A-E, and five schemes for pyramiding four genes, denoted Scheme F-J. These schemes are representative of the possible alternatives. We also provided an algorithm to compute the population sizes needed in each generation. We compared these schemes with respect to the total population size and the number of generations required under different situations. The results show that there is no scheme that is optimal in all cases. Among the schemes for pyramiding three genes from three lines (L1, L2 and L3), Scheme D (a three-way cross between the three lines are first performed, followed by a backcross to L1 and a subsequent intercross to obtain the desired genotype) has a significant advantage over the other schemes when the recombination rate between adjacent genes ranges from 0.1 to 0.4, while Scheme A (a two-way cross between L1 and L2 and a subsequent intercross are performed, followed by a cross with L3 and a subsequent intercross to obtain the desired genotype) is optimal when recombination rate is 0.5. Among schemes for pyramiding four genes from four lines (L1, L2, L3 and L4), Scheme I (seperately, a two-way cross between L1 and L2 (L3 and L4) followed by a backcross to L1 (L3) and a subsequent intercross are performed, then the offspring from the two sides are crossed and followed by a backcross to L1 and a subsequent intercross to obtain the desired genotype) is optimal when the recombination rate ranges from 0.1 to 0.4, while Scheme F (cross and subsequent intercross between the four lines are performed successively) is the optimal when the recombination rate is 0.5. We also disscuss how the animals' reproductive capacity, the probabilities of obtaining the desired genotypes and genetic distance between adjacent genes would affect the design of an optimal scheme.     

Rapid effects of the intravenous injection of a medium-chain triglyceride: fish oil emulsion on the triglyceride fatty acid pattern of soleus muscle from omega3 fatty acid-depleted rats.

Second generation rats depleted in long-chain polyunsaturated omega3 fatty acids display several features of the metabolic syndrome, including visceral obesity, liver steatosis, insulin resistance, hypertension, and cardiac hypertrophy. In the framework of an extensive study on such metabolic, hormonal and functional perturbations, the phospholipid fatty acid pattern and ex vivo metabolism of D-glucose were recently investigated in the soleus muscle of these omega3-depleted rats. The present study deals with the triglyceride fatty acid content and pattern of the soleus muscle in control animals and omega3-depleted rats. Some of the latter rats were injected intravenously 60-120 minutes before sacrifice with either an omega3 fatty acid-rich medium-chain triglyceride/fish oil emulsion (omega3-FO rats) or a control medium-chain triglyceride/olive oil emulsion (omega3-OO rats). The total fatty acid content of triglycerides was comparable in control and omega3-depleted rats and, in both cases, inversely related to their C20:4omega6 relative content. At variance with the situation found in control rats, no long-chain polyunsaturated omega3 fatty acid (C18:3omega3, C20:5omega3, C22:5omega3, C22:6omega3) was detected in the omega3-depleted rats. Unexpectedly, the triglyceride content in most long-chain polyunsaturated omega6 fatty acids (C18:2omega6, C20:3omega6, C20:4omega6 and C22:4omega6) had also decreased in the latter rats. Moreover, the activity of Delta9-desaturase was apparently increased in the omega3-depleted rats, as judged from the C16:1omega7/C16:0 and C18:1omega9/C18:0 ratios. The omega3-FO rats differed from omega3-OO rats by a lower contribution of C18:2omega6 metabolites (C18:3omega6, C20:3omega6, C20:4omega6 and C22:4omega6). These findings indicate that the prior injection of the medium-chain triglyceride/fish oil emulsion, known to increase the muscle phospholipid content in long-chain polyunsaturated omega3 fatty acids, may nevertheless accentuate the depletion in long-chain polyunsaturated omega6 fatty acids otherwise found in the triglycerides of omega3-depleted rats. Such a dual effect is reminiscent of that observed, under the same experimental conditions, for selected variables in D-glucose metabolism in the soleus muscle.     

Identification of salt-stress responsive genes in rice (Oryza sativa L.) by cDNA array

To identify salt stress-responsive genes, we constructed a cDNA library with the salttolerant rice cultivar, Lansheng. About 15000 plasmids were extracted and dotted on filters with Biomeck 2000 HDRT system or by hand. Thirty genes were identified to display altered expression levels responding to 150 mmol/L NaCl. Among them eighteen genes were up-regulated and the remainders downregulated. Twenty-seven genes have their homologous genes in GenBank Databases. The expression of twelve genes was studied by Northern analysis. Based on the functions, these genes can be classified into five categories, including photosynthesis-related gene, transportrelated gene, metabolismrelated gene, stress-or resistancerelated gene and the others with various functions. The results showed that salt stress influenced many aspects of rice growth. Some of these genes may play important roles in plant salt tolerance.     

Sunitinib Reverse Multidrug Resistance in Gastric Cancer Cells by Modulating Stat3 and Inhibiting P-gp Function

Sunitinib, a small-molecule multi-targeted tyrosine kinase inhibitor, has been applied in phase II clinical trial as second-line treatment for advanced gastric cancer. In this study, we determined the effect of Sunitinib on the multidrug resistance in gastric cancer cells selected by vincristine. Our results showed that Sunitinib significantly enhanced the cytotoxicity of adriamycin, vincristine, etoposide, 5-Fluorouracil, and cisplatin in multidrug-resistant gastric cancer cells (SGC7901/VCR). Sunitinib significantly increased the intracellular accumulation and retention of rhodamine 123 in the SGC7901/VCR cells. However, Sunitinib, at a concentration that reverses MDR, had no significant effect on P-gp protein or mRNA expression levels. In addition, the present study revealed that Sunitinib inhibited Stat3 and down-regulated Bcl-2 in SGC7901/VCR cells, which might also contribute to the reversal of MDR. In conclusion, Sunitinib reverses multidrug resistance in gastric cancer cells by inhibiting P-gp transporter function and modulating Stat3 and Bcl-2. Further study with Sunitinib may be helpful for developing combination therapeutic strategy or circumventing gastric cancer MDR to other conventional anti-cancer drugs.     

双尾蚜属的种类与地理分布

双尾蚜属Diuraphis Aizenberg全世界记录13种,主要分布在古北界和新北界。根据种类丰富度和特有种成分,欧亚大陆的欧洲和中亚为该属蚜虫的现代第一分布中心,北美为第二分布中心。本文提供了该属所有13个种的分种检索表。双尾蚜属蚜虫在中国共有7种,主要分布在蒙新区。它们是：麦双尾蚜Diuraphis noxia (Mordvilko), 害冰麦双尾蚜D. nociva Zhang et Liang,冰草麦蚜D. (Holcaphis) agropyronophaga Zhang, 披碱草蚜D. (Holcaphis) elymophila Zhang, 西方麦蚜D. (Holcaphis) frequens (Walker), 雀麦蚜D. (Holcaphis) bromicola Hille Ris Lambers和绒毛草蚜D. (Holcaphis) holci (Hille Ris Lambers)。对中国种类进行了简要描述。     

MicroRNA-30a sensitizes tumor cells to cis-platinum via suppressing beclin 1-mediated autophagy

Autophagy is activated in cancer cells during chemotherapy and often contributes to tumor chemotherapy resistance. In this study, we characterized the role of microRNA-30a (miR-30a) in the coordination of cancer cell apoptosis and autophagy, which determines the sensitivity of cancer cells to chemotherapy. First, the autophagy activity in cancer cells increased after cis-dichloro-diamine platinum (cis-DDP) or Taxol treatment, as indicated by the enhanced expression of beclin 1, a key regulator of autophagy, and increased number of LC3-positive autophagosomes. Second, miRNA screening using a TaqMan probe-based quantitative RT-PCR assay identified that miR-30a, a miRNA that targets beclin 1, was significantly reduced in tumor cells by cis-DDP treatment. Forced expression of miR-30a significantly reduced beclin 1 and the autophagy activity of tumor cells induced by cis-DDP. Third, the blockade of tumor cell autophagy activity by miR-30a expression or 3-methyladenine significantly increased tumor cell apoptosis induced by cis-DDP treatment. Finally, an in vivo tumor implantation mouse model clearly showed that elevation of miR-30a in implanted tumor cells by administration of the recombinant lentivirus expressing miR-30a strongly enhanced cis-DDP-induced apoptosis of tumor cells. In conclusion, our results demonstrate for the first time that miR-30a can sensitize tumor cells to cis-DDP via reducing beclin 1-mediated autophagy and that increasing miR-30a level in tumor cells represents a novel approach to enhance the efficacy of chemotherapy during cancer treatment.     

Preliminary results on nematicidal activity from culture filtrates of Basidiomycetes against the pine wood nematode,Bursaphelenchus xylophilus (Aphelenchoididae)

One hundred and eighty one fungal species that were isolated from the fresh fruiting bodies collected in the Mountains of Pu Er County of Yunnan Province, China were tested on the pine wood nematode,Bursaphelenchus xylophilus in vitro. Each fungal species was grown in Czapek broth and potato dextrose broth (PDB). Fifteen filtrates fromAmauroderma austrosinense, Amauroderma macer, Filoboletus sp.,Laccaria tortilis, Lactarius gerardii, Lentinula edodes, Oudemansiella longipes, Oudemansiella mucida, Peziza sp.,Pleurotus sp.,Sinotermitomyces carnosus (two strains),Strobilomyces floccopus, Termitomyces albuminosus, Tylopilus striatulus grown on PDB were found to be pathogenic to the tested nematodes. Eleven filtrates fromAmanita junguillea, Amanita sp.,Daedalea sepiaria, Fistulina hepatica, Omphalotus olearius, Oudemansiella mucida, Peziza sp.,Pleurotus pulmatus, Ramaria sp.,Tricholoma conglobatum, Tylopilus striatulus grown on Czapek broth were also pathogenic to the nematodes. When screening for nematicidal potential of fungi, it is important to study the growth medium conditions necessary to obtain the optimal nematicidal effect as fungal filtrates growing on different liquid media showed a very inconsistent toxicity towards nematodes.     

Tenascin-R distinct domains modulate migration of neural stem/progenitor cells in vitro

Extracellular matrix (ECM) molecules constitute a "niche" that modulates the migration, proliferation, and differentiation of neural stem/progenitor cells (NSPCs). The glycoprotein Tenascin-R (TN-R) is an ECM molecule, comprising multiple domains. Either the whole TN-R molecule or its distinct domains has been demonstrated to play a very important role in the developing central nervous system. However, little is known about the effect of the TN-R domain on NSPCs, especially NSPC migration. In the present study, we first show that both TN-R domains epidermal growth factor-like repeat (EGFL) and fibronectin type III (FN)6-8 can inhibit the NSPCs migration from neurospheres in vitro. Furthermore, both the EGFL and FN6-8 domains affect the distribution of neurons generated from neurospheres, indicating that EGFL and FN6-8 domains inhibit the motility of neurons generated from neurospheres. These results suggest that TN-R has an inhibitory effect on NSPCs migration.     

Purification, crystallization and preliminary crystallographic investigations of selenium-containing phycocyanin from selenium-rich algae ( Spirulina platensis )

The selenium-containing phycocyanin from the selenium-rich algae (Spirulina platensis) has been crystallized in two crystal forms by the hanging-drop vapor diffusion techniques. A chromatographic procedure of gel filtration and anion exchange was used for purification. Form I crystal with space group P2₁ and cell parameters a =108.0 ?, b= 117.0 ?, c = 184.0?, β= 90.2° and 12(αβ) units in the asymmetric unit was obtained by using (NH₄)₂SO₄ as precipitant. These crystals diffract up to 2.8 ?. Form II crystal obtained by using PEG4000 as precipitant belongs to space group P6₃ with unit cell constants a = 155.0 ?, c = 40.3 ?, γ =120.0° and one(αβ) unit in the asymmetric unit. The crystals diffract beyond 2.9 ?. The possible stacking forms of phycocyanin molecules in the first crystal form were discussed.