二斑叶螨对菜豆叶片几种生理指标的影响

[目的]测定二斑叶螨为害后菜豆叶片生理指标的变化。[方法]在供试菜豆4叶期后,每株菜豆接种20头二斑叶螨,隔0、3、5、10、15和20 d随机采集被害叶片10片,测定样品的叶绿素、可溶性蛋白、游离氨基酸和游离脯氨酸含量,并测定其过氧化氢酶活性和膜透性。[结果]菜豆叶片受二斑叶螨侵害后在取食部位形成褪绿斑,随着为害侵染天数的增加,该褪绿斑增多,20 d后,菜豆叶片发白直至死亡。生理指标测定表明,菜豆叶片叶绿素含量随着侵染时间的增加而降低,可溶性蛋白、游离氨基酸、游离脯氨酸、过氧化氢酶和电导率随着为害时间的延长而明显增加。[结论]该研究对探索植物对二斑叶螨侵染的反应机制,发展植物对二斑叶螨抗性具有指导意义。     

紫茎泽兰入侵机制及防治方法的研究进展

对紫茎泽兰的生理生化、入侵机制及防治等方面进行综述。     

Effects of lentivirus-mediated siRNA targeting IGF-1R on migration and invasion abilities of endometrial carcinoma cells

AIM:To investigate the down-regulation of insulin-like growth factor tgpe 1 receptor(IGF-1R) on the migration and invasion abilities of human endometrial cancer cell HEC-1B. METHODS:The siRNAs targeting IGF-1R gene were synthesized, cloned into a lentivirus expression vector and transfected into endometrial cancer HEC-1B cells(HEC-1B-KD group). The control cells(without virus transfection, HEC-1B-CON group) and negative virus transfection control cells(HEC-1B-NC group) were also set up. The gene silencing effect of siRNA targeting IGF-1R was determined by real-time PCR and Western blotting at mRNA and protein levels,respectively. The proliferation rate was detected by colony formation assay. The cell migration and invasion abilities were determined by Transwell experiment. The mRNA levels of matrix metalloproteinase(MMP)-2 and MMP-9 were measured by real-time PCR. RESULTS:The mRNA and protein levels of IGF-1R in HEC-1B-KD cells were significantly reduced by 81% and 91.5%, respectively(P<0.05). In anchorage-dependent growth by colony formation assay, HEC-1B-KD cells showed much less colonies than HEC-1B-CON cells and HEC-1B-NC cells. Compared with the control cells, knockdown of IGF-1R in HEC-1B cells resulted in significant reduction of cell motility. Down-regulation of IGF-1R in HEC-1B cells also significantly reduced the invasion potential(P<0.05). Down-regulation of IGF-1R substantially reduced the expression of MMP-2 and MMP-9 compared with the control cells. CONCLUSION:Knockdown of IGF-1R reduces the migration and invasion abilities of human endometrial cancer cells in vitro accompanied with a decrease in MMP-2 and MMP-9 expression.     

Invasive potential of bacterial isolates associated with subclinical bovine mastitis

This work describes differences in the invasive ability of bacterial isolates associated with mastitis. Invasion ability was determined by the uptake and survival in a primary culture of bovine mammary epithelial cells (BMEC). BMEC were isolated from a healthy lactating cow and characterized by their morphology, immunostaining for cytokeratin and the detection of beta- and kappa-casein mRNAs. Ten bacterial isolates comprising the staphylococcal species Staphylococcus aureus (3), Staphylococcus epidermidis (1), Staphylococcus haemolyticus (1), Staphylococcus equorum (2), Staphylococcus xylosus (1) and Brevibacterium stationis (2) obtained from raw milk of cows with mastitis from backyard farms were assayed for their ability to invade BMEC. Only two S. aureus and one S. epidermidis isolates were able to invade BMEC, at similar levels to the S. aureus control strain ATCC 27543. In conclusion, using the in vitro model of infection used in this study, differences in bacterial invasion capability may be detected.     

Erwinia amylovora can pass through the abscission layer of fruit-bearing twigs and invade apple fruit during fruit maturation

Invasion of apple fruit by Erwinia amylovora from fruit-bearing twigs through the abscission layer at fruit maturation was examined. Erwinia amylovora (ca. 10⁵ cfu) tagged with bioluminescence genes from Vibrio fischeri was deposited in artificial wounds on fruit-bearing twigs of apple trees grown in a containment greenhouse on September 22, 27, or October 5, 2004. On October 22, 176 apples were harvested and cut horizontally in half. The upper halves were stamped on plates of selective medium, and the lower halves were flooded with iodine solution to assess maturity. All fruit were symptomless and fully mature. The pathogen was recovered from 19 (10.8%) apples. The result showed that if at least ca. 10⁵ cfu of E. amylovora are present in fruit-bearing twigs at the time of fruit maturation, the bacteria can pass through the abscission layer into the fruit, even though the mature fruit lack symptoms.     

Amino acid 129 in the coat protein of Cucumber mosaic virus primarily determines invasion of the shoot apical meristem of tobacco plants

We previously reported that a strain of Cucumber mosaic virus (Pepo CMV) invaded the shoot apical meristem (SAM, tunica corpus) of tobacco plants at 6–8 days postinoculation (dpi), contrary to earlier observations. To identify a viral factor determining the ability to invade the SAM, we inoculated plants with two other CMV strains, MY17 and Y, and tested the three strains in this study. Immunohistochemical microscopy revealed that MY17 CMV invaded the SAM at 7 dpi, the same as Pepo CMV, but Y CMV did not, even at 21 dpi. Using RNA pseudorecombinants between Pepo and Y CMV, we found that Pepo RNA 2 affected the rate of SAM invasion, and Pepo RNA 3 was required for successful SAM invasion. Inoculation with RNA 1 and RNA 2 from Y CMV and RNA 3 containing the chimeric coat protein (CP) gene between Pepo and Y CMV or a Y RNA 3 point mutant containing a Ser-to-Pro substitution at position 129 in CP (Y129P) revealed that amino acid 129 of CP is the determinant for successful SAM invasion. The rate of SAM invasion of the pseudorecombinants and Y129P was consistent with the efficiency of cell-to-cell movement in the inoculated leaves, implying that SAM invasion by CMV strains may be due to efficient cell-to-cell movement.     

Effects of propofol on invasion and migration of human gastric cancer SGC-7901 cells

AIM: To investigate the effects of propofol on invasion and migration of gastric cancer cell line SGC-7901. METHODS: Cultured gastric cancer cell line SGC-7901 was randomly divided into 4 groups, and then diffe-rent concentrations (1, 3, 5 and 7 mg/L) of propofol were added and incubated for 24 h. The cell viability was measured by MTT assay. The invasion and migration abilities of the SGC-7901 cells were detected by Transwell assay and wound-healing assay. The expression of cysteine-rich angiogenic inducer 61 (CYR61), CD44v6 and matrix metalloproteinase-7 (MMP-7) in the SGC-7901 cells were examined by immunocytochemistry and Western blot.RESULTS: Propofol at 5 mg/L does not affect the viability of SGC-7901 cells, whereas significantly suppresses the invasion and migration abilities, and down-regulates the expression of CD44v6 and MMP-7 (P<0.05). CONCLUSION: The decreased invasion and migration abilities of SGC-7901 cells were partly due to the inhibition of CD44v6 and MMP-7 expression.     

Activity of matrix metalloproteinase-2 (MMP-2) in canine oronasal tumors

Activity of matrix metalloprotease-2 (MMP-2) and the expression of its related molecules were examined in spontaneous canine oronasal tumors. Tissue samples from melanoma and squamous cell carcinoma possessed higher MMP-2 activity, as shown in gelatin zymography, in comparison with acanthomatous epulis and nasal adenocarcinoma. Regional lymph node invasion and distant metastases were more frequently observed in the MMP-2 positive cases. There were no significant differences by RT-PCR examination in the expression of the genes encoding MMP-2, MT1-MMP and TIMP-2 among the tumor histological types. However, the MMP-2/TIMP-2 ratio showed a significantly higher level of the genes in the malignant oral melanoma and squamous cell carcinoma. The MMP-2/TIMP-2 ratio was also positively correlated with MMP-2 activity in gelatin zymography. These results indicate that the MMP-2/TIMP-2 ratio may be of value in evaluating the prognosis in canine oronasal cavity tumors.     

Patterns of larch establishment following deglaciation of Ventina glacier,central Italian Alps

Rapid glacier retreat often results in extensive areas of deglaciated terrain where primary successional processes occur. We studied biotic and abiotic factors underlying the invasion of larch (Larix decidua Mill.) on a glacier foreland and tested the hypothesis that the pattern of its establishment was controlled primarily by terrain age.