ABSTRACT: We used standard periphyton samplers to examine the colonization pattern of periphytic algae on artificial substrates (glass
slides) in Lam Tsuen River, Hong Kong, in dry (winter) and wet (summer) seasons. In each season, six replicated slides were
retrieved randomly and replaced by new slides at weekly intervals over a period of 6 weeks. We thus obtained two batches of
slides, both with a series of different exposure times (1 to 6 weeks): one batch was set up at the same time (start of the
sampling) and the other was harvested at the same time (end of the sampling). Changes in taxonomic composition, species diversity
(Shannon-Wiener diversity index), standing crop (in terms of cell density and cell biovolume), and abundance of the abundant
algal species were monitored and compared between the two batches of slides. The succession patterns of the periphytic algae
were similar between the two batches in each season, while more remarkable differences were observed between the two seasons,
suggesting that either batch would be suitable for a colonization study of periphytic algae. The cell density was dominated
by diatoms in both seasons, while the cell biovolume was dominated by diatoms in winter and by green algae in summer. The
cell density and biovolume attributed to blue green algae was relatively small. Most of the diatom species exhibited similar
colonization patterns throughout the experiment, while green algae showed different succession patterns in different seasons
or sampling methods, indicating that diatoms are better bio-indicators than green algae for a periphyton colonization study.
In general, the diversity indices and the standing crops reached their maximums at around week 4, and they were higher in
summer than in winter.
Keywordcell biovolume–cell density–colonization–periphyton–species diversity
Chinese Journal of Oceanology and Limnology 04/2012; 29(1):141-149. · 0.50 Impact Factor
ABSTRACT: To improve the expression efficiency of exogenous genes in Chlamydomonas reinhardtii, a high efficient expression vector was constructed. Green fluorescent protein (GFP) was expressed in C. reinhardtii under the control of promoters: RBCS2 and HSP70A-RBCS2. Efficiency of transformation and expression were compared between two transgenic algae: RBCS2 mediated strain Tran-I and HSP70A-RBCS2 mediated strain Tran-II. Results show that HSP70A-RBCS2 could improve greatly the transformation efficiency by approximately eightfold of RBCS2, and the expression efficiency of GFP in Tran-II was at least double of that in Tran-I. In addition, a threefold increase
of GFP in Tran-II was induced by heat shock at 40°C. All of the results demonstrated that HSP70A-RBCS2 was more efficient than RBCS2 in expressing exogenous gene in C. reinhardtii.
Chinese Journal of Oceanology and Limnology 04/2012; 26(3):242-247. · 0.50 Impact Factor
ABSTRACT: The mitochondrial expression of exogenous antibiotic resistance genes has not been demonstrated successfully to date, which has limited the development of antibiotic resistance genes as selectable markers for mitochondrial site-directed transformation in Chlamydomonas reinhardtii. In this work, the plasmid pBSLPNCB was constructed by inserting the gene ble of Streptoalloteichus hindustanus (Sh ble), encoding a small (14-kilodalton) protective protein into the site between TERMINVREP-Left repeats and the cob gene in a fragment of mitochondrial DNA (mtDNA) of C. reinhardtii. The fusion DNA-construct, which contained TERMINVREP-Left, Sh ble, cob, and partial nd4 sequence, were introduced into the mitochondria of the respiratory deficient dum-1 mutant CC-2654 of C. reinhardtii by biolistic particle delivery system. A large number of transformants were obtained after eight weeks in the dark. Subsequent subculture of the transformants on the selection TAP media containing 3 ìg/mL Zeomycin for 12 months resulted in genetically modified transgenic algae MT-Bs. Sequencing and Southern analyses on the mitochondrial genome of the different MT-B lines revealed that Sh ble gene had been integrated into the mitochondrial genome of C. reinhardtii. Both Western blot, using the anti-BLE monoclonal antibody, and Zeomycin tolerance analysis confirmed the presence of BLE protein in the transgenic algal cells. It indicates that the Sh ble gene can be stably expressed in the mitochondria of C. reinhardtii.
PLoS ONE 01/2012; 7(4):e35542. · 4.09 Impact Factor
ABSTRACT: The efficient expression of exogenous gene in mitochondria of photosynthetic organism has been an insurmountable problem. In this study, the pBsLPNCG was constructed by inserting the egfp gene into a site between TERMINVREP-Left repeats and the cob gene in a fragment of mitochondrial DNA of Chlamydomonas reinhardtii CC-124 and introduced into the mitochondria of respiratory deficient dum-1 mutation of C. reinhardtii CC-2654. Sequencing and DNA Southern analyses revealed that egfp gene had been integrated into the mitochondrial genome of transgenic algae as expected and no other copy of egfp existed in their nucleic genome. Both the fluorescence detection and Western blot analysis confirmed the presence of eGFP protein in the transgenic algae; it indicated that the egfp gene was successfully expressed in the mitochondria of C. reinhardtii.
Mitochondrion 06/2011; 11(5):716-21. · 3.62 Impact Factor