A Novel Approach of Gene Knockdown in Zebrafish through Targeted mRNA Cleavage
The zebrafish (Danio rerio) is a popular model organism used for elucidating complex\r developmental pathways and processes. Although the Zebrafish Genome Project is\r nearing completion, the function of most genes remains to be discovered. In zebrafish,\r where an efficient gene targeting method is still absent, costly Morpholinos (MOs) have\r been widely used to ‘knockdown’ specific genes.
Ectomycorrhizal Inoculation of Anisoptera thurifera and Shorea guiso : GROWTH AND PHOSPHORUS DYNAMIC
Dipterocarps coming from Southeast Asia comprise about 53% of the world’s\r total exports of tropical hardwood products. However, the supply of dipterocarps is\r rapidly declining. The government is currently embarking on the establishment of\r dipterocarp plantations and encourages inoculation with ectomycorrhizal fungi to\r improve seedling growth and survival in degraded sites. Anisoptera thurifera (Blanco)\r Blume and Shorea guiso (Blanco) Blume rooted cuttings were inoculated with\r mycelial beads containing either Pisolithus PTG, Pisolithus H6394, or Astreus sp.\r Pisolithus PTG was collected from Acacia mangium stand in Malaysia, Pisolithus\r H6394 from Eucalyptus trees growing in a heavy metal contaminated area in New\r Caledonia, Astreus sp obtained from dipterocarp forest in Mt. Makiling, Philippines.\r The results showed that Astreus sp gave the highest root colonization (38%), height\r increment (86%), fine root (51%), coarse root (27%), shoot (43%) and total dry\r weight (40%) of A. thurifera over the control treatment. Astreus – inoculated plants\r had the highest shoot P uptake (41%) while PTG inoculated ones obtained the highest\r fine root P uptake (0.273 mg/root). The uninoculated plants had the lowest height\r increment, dry weight, and P uptake. In S. guiso, Pisolithus H6394, gave the highest\r increment (100%). Data were only obtained from four months of nursery experiments,\r hence, a longer nursery and field experiments should be conducted to achieve a\r complete evaluation of the physiological functions of ectomycorrhizal associations.\r Moreover, a wide range of ectomycorrhizal fungi associated with dipterocarps should\r be incorporated for selection of host compatibility.
溫泉中的秘密
The experiment was primarily focused on studying whether the enzymes from different bacterial species collected in various hot spring areas still exhibited activities at high temperatures. A further study would be conducted on analyzing the unique characteristics universally found in the genes of selected bacteria. First, hot spring samples were collected form Peitou and Wulai, and then cultured on the PY, PTG, MFB, and TS media in the laboratory. After the broth media growing with thermophilic bacteria, a series of continuous dilution method and solid-plate spreading were applied to separate these bacterial clones. The genomic DNA of the selected bacteria was extracted and used to analyze subtilisin-like gene by polymerase chain reaction (PCR) and electrophoresis. Finally, we examined the six selected thermophilic bacteria with the enzymatic activities of fibrin- and milk-protein degradation. We successfully concluded the experiment by proving that these thermophilic bacteria still exhibited significant enzymatic activitives in the high-temperature environments. The results of this experiment can be applied in numerous fields, for example, thrombus treatment and food processing, and a more in-depth study shall warrant the due consideration. 這次的實驗，主要是研究在不同的溫泉區中所採集不同種類細菌，是否酵素在高溫下仍具活性，如果有，再進而研究它們的基因有何特別的共同之處。首先，我分別自北投和烏來採集水樣，到實驗室後再以PY、PTG、MFB 和TS 四種培養基做細菌的培養，接著再利用連續稀釋和固態塗抹來做細菌的分離。經過挑選和培養之高溫菌直接進行DNA 的抽取，並利用「聚合?鏈反應」和「電泳跑膠」技術分析其類似蛋白質分解酵素subtilisin 基因。另外，本研究同時針對所選定之6 株高溫細菌利用血栓和牛奶蛋白來測試其蛋白質分解酵素的活性。由以上實驗結果可以證明某些細菌在高溫的環境下酵素仍具活性。這次在高溫菌的實驗結論，可應用在很多地方，例如：血栓的治療、在高溫下食品處理‧‧‧等，應用相當廣泛。
台灣不同世代A 群鏈球菌對紅徽素抗藥性之研究
A total of 64 nonduplicate isolates of erythromycin-resistant (MIC, >1 μg/ml) Streptococcus pyogenes collected from 1979 to 2003 in Taiwan were evaluated. They were collected from three cohort period: 1979 –1989, 1990-1999 and after 2000. The in vitro activities of 10 antimicrobial agents were determined by the agar dilution method. Penicillin, cephalothin, cefotaxime, vancomycin, and ofloxacin were shown to be active against S. pyogenes isolates (100% sensitive). Erythromycin and azithromycin both had poor activities (MIC50s, 16 and >128 μg/ml, respectively; MIC90s, >512 and >128 μg/ml, respectively). The activities of tetracycline, clindamycin, and chloramphenicol against a significant number of these isolates were also limited. Among the 64 S. pyogenes isolates, 58% had constitutive resistance [cMLS], 40% had an M phenotype and 2% had an iMLS phenotype (inducible resistance [iMLS]). A substantial upsurge in the incidence of M phenotype erythromycin-resistant isolates was found with time for S. pyogenes (10% in 1979–1989, 48% in 1990–1999 and 65% after 2000). The erythromycin resistance genes in 64 isolates of the different cohorts were investigated by PCR. All cMLS phenotype isolates tested had ermB gene. The M phenotype isolates had only the macrolide efflux (mefA) gene. This study shows the secular changes of increasing susceptibility of S. pyogenes isolates to both erythromycin and clindamycin in Taiwan. The mechanisms of erythromycin resistance have changed from the predominance of ermB gene (cMLS) to mefA gene (M phenotype). 本研究是探討台灣自1970 年代末期以來不同世代A群鏈球菌菌株對紅黴素的抗藥性及抗藥基因特徵的演變。研究者收集台灣二十年前(1980 年代前後，第一世代)、十年前(1990 年代，第二世代)、)及最近(2000 年以後，第三世代)之A 群鏈球菌菌株共64 株，利用抗生素圖譜和雙藥錠擴散測試及聚合?連鎖反應(PCR)、和脈衝式膠體電泳研究A 群鏈球菌對紅黴素抗藥性的表現型及基因型特徵。結果發現第一世代的A 群鏈球菌對紅黴素最小抑菌濃度(MIC)值相當高，幾乎都是>512 μg/ml，90%為多重抗藥菌株。第二世代則相對有降低，在第三世代此現象更明顯，多重抗藥菌株為30%。在雙藥錠擴散測試結果，從第一世代來看cMLS 佔大多數(90%)，M 型佔10%；第二世代cMLS 及M 型相當分別佔52%及48%；第三世代主要為M 型佔65%，cMLS 佔30%，iMLS 佔5%。利用PCR研究紅黴素抗藥性基因發現所有cMLS 菌株皆有ermB 基因，所有M 型菌株皆有mefA 基因，iMLS 菌株則有ermTR 基因。由本研究顯示在台灣A 群鏈球菌對紅黴素之抗藥性隨著不同世代有逐年改善之趨勢，由MIC50的降低可看出，菌株對紅黴素的敏感性提高，可為臨床治療之參考。