Effect of Light Intensity and pH on Cell Density Assessed by Spectrophotometry for the Unicellular Algae Chlorella vulgaris

In this study, an effective environment for Chlorella vulgaris growth is sought after. As a substitute source of food and feed, increasing the cell density of Chlorella culture is one of the keys to ensuring sustainability. It can be showed from different studies that optimum light intensity and pH could increase cell density. In this study, the effects of light and pH on the growth rate of C. vulgaris were observed in photobioreactor. A specific wavelength (682 nm) was determined by UV-Vis Spectrophotometry to carry out the further analysis. The light intensities were set at 7409, 9261 and 11,113 lux;pH values were set at 7, 8 and 9 respectively. The experimental results depicted the light intensity of 9261 lux as the best due to the higher number of cells (48.56 × 106 cells/mL) obtained using this intensity. In terms of pH, without pH control, cell numbers were found to be highest under the light intensity of 9261 lux. When pH was controlled, it was found that under the optimum light intensity, pH control between 7.0 and 7.5 was the optimum range for the growth of C. vulgaris. Moreover, this method of study may possibly be a promising source of low cost culture for Chlorella vulgaris.

FATTY ACIDS PROFILE IN A HIGH CELL DENSITY CULTURE OF ARACHIDONIC ACID-RICH PARIETOCHLORIS INCISA (TREBOUXIOPHYCEAE,CHLOROPHYTA) EXPOSED TO HIGH PFD

The changes in arachidonic acid (AA) and fatty acids profiles along the growth curve of Parietochloris incisa, a coccoid snow green alga, were studied in a 2.8 cm light-path flat photobioreactor, exposed to strong photon flux density [PFD, 2400 μEmol/(m 2·s)]. Sixteen fatty acids were identified by gas chromatography showing that AA was the dominant fatty acid (33%-41%) followed by linoleic acid (17%-21%). AA content was closely investigated with respect to total fatty acids (TFA), ash free dry weight (AFDW) of cell mass as well as total culture content. These parameters were influenced significantly in a similar manner by culture growth phase, i.e., slightly decreasing in the lag period, gradually increasing in the logarithmic phase, becoming maximal at the early stationary phase, starting to decrease at the late stationary phase, sharply dropping at the decline phase. The increase in AA per culture volume during the logarithmic phase was not only associated with the increase in AFDW but also connected with a corresponding increase in AA/TFA, TFA/AFDW as well as AA/AFDW. The sharp decrease in AA content of the culture during the decline phase was mainly due to the decrease in AA/TFA, TFA/AFDW and AA/AFDW, although AFDW declined only a small extent. Maximal AA concentration, obtained at the early stationary phase, was 900 mg/L culture volume, and the average daily net increase of AA during 9 days logarithmic growth was 1.7 g/(m 2·day). Therefore, harvesting prior to the decline phase in a batch culture, or at steady state in continuous culture mode seems best for high AA production. The latter possibility was also further confirmed by continuous culture with 5 gradients of harvesting rate.

Corneal endothelial cell density and morphology in low and moderate myopic Chinese eyes

AIM:To describe and compare the corneal endothelial cell density and morphology in young,low and moderate myopic Chinese adults in Malaysian Chinese population.·METHODS:Non-contact specular microscopy(Topcon SP3000P,Tokyo,Japan) was performed in low(n =78;21.22±1.51 years) and moderate(n =78;21.82±1.40 years)myopic subjects.The mean of three consecutive measurements of endothelial cell density(MCD),coefficient of variation(CV) in the cell size,and hexagonal appearance of the cell were obtained.·RESULTS:In low myopic eyes the MCD was 3 063.0±176.2/mm2,the mean CV was 33.4 ±4.0% and the mean hexagonal appearance of the cell was 57.9 ±2.7%.In moderate myopic eyes the MCD was 2961.6 ±159.0/mm2,the mean CV was 33.9 ±3.6% and mean hexagonal appearance of the cell was 56.2 ±4.7%.There were statistically significant differences in MCD(P 【0.000) and hexagonal appearance of the cell(P 【0.005) between low and moderate myopic eyes.·CONCLUSION:The corneal endothelial cell layer in more myopic eyes tends to have less MCD and cell hexagonality compared to lower myopic eyes.Nevertheless,there is no significant difference in CV between low and moderate myopic eyes.

Visual acuity and endothelial cell density with respect to the graft thickness in Descemet's stripping automated endothelial keratoplasty: one year results

AIM: To evaluate the visual acuity and endothelial cell density according to the thickness in Descemet’s stripping automated endothelial keratoplasty(DSAEK)one year after surgery.METHODS: DSAEK patients’ data were reviewed. Thirty seven eyes of 37 patients who underwent DSAEK for pseudophakic bullous keratopathy(PBK) were included in this study. Graft thickness was measured with optical coherence tomography(OCT) 12 mo after DSAEK. Eyes were divided into 3 groups based on the graft thickness:thick(】200 μm), medium-thick(150-200 μm) and thin(【150 μm). Best corrected visual acuity(BCVA),endothelial cells density(ECD) and complications were assessed and comparisons were done between groups.RESULTS: Median thickness of postoperative grafts was 188(range 73-317 μm). There was no significant difference in age, sex, preoperative BCVA, or follow-up period between DSAEK groups. At postoperative 12 mo,mean BCVA was 0.28±0.10 in thick graft group, 0.52±0.08 in medium-thick graft group, and 0.72 ±0.06 in thin graft group. Thin grafts showed better postoperative BCVA as compared with the medium-thick and thick grafts(P =0.001). Thick graft group had 1637.44 ±88.19-mm2,medium thick graft had 1764.50±34.28-mm2 and thin graft group had 1845.30 ±65.62-mm2. Thin graft group had better ECD at 12 mo after surgery(P =0.001).CONCLUSION: Thin grafts after DSAEK ensure better visual rehabilitation. Eyes with thin grafts had significantly lesser loss of ECD compared to eyes withmedium-thick and thick grafts one year after surgery.

Corneal endothelial cell density and morphology in Chinese patients with pseudoexfoliation syndrome

AIM: To evaluate the corneal endothelial cell density and morphology in Chinese patients with pseudoexfoliation syndrome (PEX). METHODS: Medical records of 16 patients (20 eyes) with PEX who presented to our institution between July 2008 and June 2010 were retrospectively reviewed. Thirteen eyes had combined glaucoma. The information of five apparently normal fellow eyes in these patients was also recorded. Left eyes of 20 patients with bilateral senile cataracts but no other eye disease were included as controls. Specular microscopy was performed in all eyes to analyze for corneal endothelial cell density and morphology. Cell density, coefficient of variation in cell size, and percentage of hexagonal cells in corneal endothelium were evaluated. RESULTS: The mean corneal endothelial cell density in the PEX eyes was 2298+/- 239 cells/mm(2), significantly lower than that in the cataract eyes (2652+/- 18 cells/mm(2), P=0.026), but there were no significant differences in coefficient of variation of cell size and frequency of hexagonality between these two groups. No significant differences in the three parameters were found between the apparently normal fellow eyes and the PEX eyes or the cataract eyes, or between the PEX eyes with and without glaucoma. CONCLUSION: Corneal endothelial cell density may decrease in Chinese patients with PEX. The development of glaucoma in PEX eyes does not seem to be related with the change in corneal endothelial cell density or morphology.

Corneal endothelial cell density and morphology and central corneal thickness in Guangxi Maonan and Han adolescent students of China

AIM: To investigate the corneal endothelial cell density and morphology and central corneal thickness in the Guangxi Maonan and Han adolescent students of China.METHODS: Noncontact specular microscope(Topcon SP3000 P, Tokyo, Japan) was performed in 133 adolescent students of Maonan nationality(M:F 54:79)and 105 adolescent students of Han nationality(M:F 50:55),5 to 20 y of age, who were randomly selected from 3schools in Huanjiang Maonan Autonomous County of Guangxi Zhuang Autonomous Region of China.Parameters studied included endothelial cell density,mean cell area, coefficient of variation in cell size,percentage hexagonality and central corneal thickness. RESULTS: Endothelial cell density, mean cell area,coefficient of variation in cell size, percentage hexagonality and central corneal thickness in the study population were(2969.50 ±253.93) cells/mm2,(339.23 ±29.44) μm2,(29.96 ±4.07) %,(64.58 ±9.41) % and(523.71 ±32.82) μm in Maonan and(2998.26 ±262.65) cells/mm2,(336.11±30.07) μm2,(29.89±5.03) %,(64.91±11.64) % and(524.39 ±33.15) μm in Han, respectively. No significant differences were observed in endothelial cell density,mean cell area, coefficient of variation in cell size,percentage hexagonality and central corneal thickness between Maonan and Han(P =0.615, 0.659, 0.528, 0.551,0.999). In Maonan and Han, we found age was negatively correlated with endothelial cell density and percentagehexagonality and positively correlated with mean cell area and coefficient of variation in cell size. Negative correlation was also found between central corneal thickness and age in Han, whereas no correlation was found in Maonan. CONCLUSION: There were no differences between Maonan and Han in corneal endothelial cell density and morphology and central corneal thickness. In these two nationalities, there were statistically significant decrease in endothelial cell density and percentage hexagonality with increasing age and statistically significant increase in cell area and coefficient of variation in cell size with increasing age. Central corneal thinned with increasing age in Han, whereas difference did not attain statistical significance in Maonan.

Changes in endothelial cell density following penetrating keratoplasty and deep anterior lamellar keratoplasty

· AIM: To compare the corneal endothelial cell density (ECD) of clear grafts after penetrating keratoplasty (PK) and deep anterior lamellar keratoplasty (DALK). · METHODS: The study included 44 and 54 patients treated with PK and DALK, respectively, between March 2006 and April 2010. Corneal ECD was examined using specular microscopy at postoperative 1, 3, 6, 12, and 18 months, and the values were compared. · RESULTS: Corneal ECD reduction in the PK group was 7.4%, 15.2%, 23.5%, and 28.9% at 3, 6, 12 and 18 months respectively after surgery, compared with 4.2 % in the first month (P <0.01). These figures were 3.0%, 6.7%, 7.2%, and 7.7% at 3, 6, 12 and 18 months respectively, compared with 2.2 % in the first month in the DALK group (P >0.05). · CONCLUSION: Compared with DALK,PK significantly reduced ECD of the clear grafts. These results suggest that survival of endothelial cells in grafts is better after DALK than after PK. ·

Possible biological and translational significance of mast cells density in colorectal cancer

Mast cells (MCs), located ubiquitously near blood vessels, are descended from CD34+ hematopoietic stem cells. Initially, although their role has been well defined in hypersensitivity reactions, the discovery of their sharing in both innate and adaptive immunity has allowed to redefine their crucial interplay on the regulatory function between inflammatory and tumor cells through the release of mediators granule-associated (mainly tryptase and vascular endothelial growth factor). In particular, in several animal and human malignancies it has been well demonstrated that activated c-Kit receptor (c-KitR) and tryptase (an agonist of the proteinase-activated receptor-2) take pivotal part in tumor angiogenesis after the MCs activation, contributing to tumor cells invasion and metastasis. In this review, we focused on crucial MCs density (MCD) role in colorectal cancer (CRC) development and progression angiogenesis-mediated; then, we will analyze the principal studies that have focused on MCD as possible prognostic factor. Finally, we will consider a possible role of MCD as novel therapeutic target mainly by c-KitR tyrosine kinase inhibitors (imatinib, masitinib) and tryptase inhibitors (gabexate and nafamostat mesylate) with the aim to prevent CRC progression.

Consideration of transmembrane water exchange in pharmacokinetic model significantly improves the accuracy of DCE-MRI in estimating cellular density:A pilot study in glioblastoma multiforme

Transmembrane water exchange(TWE)including transcytolemmal water exchange and transvascular water exchange is involved in many in vivo measurements and makes different contributions to the measuring results.In this study,we focus on the potential influence of TWE on the cell density parameter,intracellular water mole fraction pi,derived by dynamic contrast enhanced-magnetic resonance imaging(DCE-MRI)which has been reported as a technique to characterize perfusion and vascularization of tissues,but its accuracy in measuring cell density(or interstitial space)has been questioned.Sixteen patients with glioblastoma multiforme(GBM)were enrolled since GBM shows strong intratumor heterogeneity in both cell density and TWE.All the subjects were collected with DCE-MRI and apparent diffusion coefficient(ADC)map.The latter was considered as a valid surrogate of cell density.Extended Tofts(eTofts)model considering TWE as infinitely large variables and shutter-speed model(SSM)considering TWE as finite ones were used to fit DCE-MRI data.Monte Carlo(MC)and finite difference(FD)methods were used to simulate the influence of TWE on DCE-MRI-derived pi and ADC,respectively.The eTofts model shows a significant overestimation of pi in comparison with SSM in GBM(P<0.001),which is in accordance with MC simulations,and this overestimation shows dependence on the intra-to-extracellular water exchange rate constant(kio).Significant negative correlations between ADC and SSM-derived pi were found in both voxel-wise analyses(t-test P<0.001,average r=-0.74)and inter-subject comparisons(r=-0.63,P=0.009).But no consistent voxel-wise correlations(P>0.05)and a weaker inter-subject negative correlation(r=-0.56,P=0.02)were found between ADC and eTofts-derived pi.Further experimental and FD results revealed that kio made a limited contribution to ADC values in the physiological kio range in GBM,supporting ADC as a valid biomarker of cell density.These results suggest that the DCE-MRI pharmacokinetic shutter-speed model could significantly improve its accuracy in cell density estimation because of the considering transmembrane water exchange.

Destructive effects on endothelial cells of grafts in cytomegalovirus DNA-positive patients after keratoplasty

AIM:To investigate corneal graft survival rate and endothelial cell density(ECD)loss after keratoplasty in cytomegalovirus(CMV)positive patients.METHODS:This was a retrospective cohort study.We analyzed the clinical data of patients who underwent viral DNA detection in aqueous humor/corneal tissue collected during keratoplasty from March 2015 to December 2018 at the Peking University Third Hospital,Beijing,China.To further evaluate the effect of CMV on graft survival rate and ECD loss,patients were divided into three groups:1)CMV DNA positive(CMV+)group;2)viral DNA negative(virus-)group,comprising virus-group eyes pairwise matched to eyes in the CMV+group according to ocular comorbidities;3)control group,comprising virus-group eyes without ocular comorbidities.The follow-up indicators including graft survival rate,ECD,ECD loss,and central corneal thickness(CCT),were analyzed by Tukey honestly significant difference(HSD)test.RESULTS:Each group included 29 cases.The graft survival rate in CMV+group were lowest among the three groups(P=0.000).No significant difference in donor graft ECD was found among three groups(P=0.54).ECD in the CMV+group was lower than the virus-group at 12(P=0.009),and 24mo(P=0.002)after keratoplasties.Furthermore,ECD loss was higher in the CMV+group than in the virus-group in the middle stage(6-12mo)postkeratoplasty(P=0.017),and significantly higher in the early stage(0-6mo)in the virus-group than in the control group(P=0.000).CONCLUSION:CMV reduces the graft survival rate and exerts persistent detrimental effects on the ECD after keratoplasty.The graft ECD loss associate with CMV infection mainly occurrs in the middle stage(6-12mo postoperatively),while ocular comorbidities mainly affects ECD in the early stage(0-6mo postoperatively).

Anomalous Cell Detection with Kernel Density-Based Local Outlier Factor

Since data services are penetrating into our daily life rapidly, the mobile network becomes more complicated, and the amount of data transmission is more and more increasing. In this case, the traditional statistical methods for anomalous cell detection cannot adapt to the evolution of networks, and data mining becomes the mainstream. In this paper, we propose a novel kernel density-based local outlier factor(KLOF) to assign a degree of being an outlier to each object. Firstly, the notion of KLOF is introduced, which captures exactly the relative degree of isolation. Then, by analyzing its properties, including the tightness of upper and lower bounds, sensitivity of density perturbation, we find that KLOF is much greater than 1 for outliers. Lastly, KLOFis applied on a real-world dataset to detect anomalous cells with abnormal key performance indicators(KPIs) to verify its reliability. The experiment shows that KLOF can find outliers efficiently. It can be a guideline for the operators to perform faster and more efficient trouble shooting.

DIAGNOSTIC VALUE OF DENSITY GRADIENT CENTRIFU-GATION FOR EXFOLIATIVE TUMOR CELLS IN MALIG-NANT PLEURAL EFFUSIONS

Objective To find out a specific method for diagnosis of malignant pleural effusions (MPEs)with higher sensitivity and practicality. Methods The diagnosis of MPEs were made using density gradient cen-trifugation(DGC) , smear cytologic examination( SCE) and pleural needle biopsy (PNB). Comparisons between these results and those of benign pleural effusions were also made. Results The positive rates of DGC,SCE and PNB for diagnosing MPEs were 94. 3% ,62. 9% and 44. 6% , respectively, and the positive rate of SCE combined with PNB for diagnosing MPEs was 73. 2%. The positive rate of the exfoliative tumor cells ( ETCs ) by DGC was much higher than that of SCE or/and PNB with no false-positive. Conclusion The ETCs isolated by DGC from the MPEs is quite specific for the diagnosis of malignant tumors with higher sensitivity and practicality in clinico-patho-logical practice.

Vascular endothelial growth factor 165b expression in stromal cells and colorectal cancer

AIM:To characterize the implications of vascular endothelial growth factor(VEGF)-A in stromal cells and colorectal cancer and the expression of VEGF-A splice variants.METHODS:VEGF-A expression in tumor and stromal cells from 165 consecutive patients with colorectal cancer was examined by immunohistochemistry.The association between VEGF-A expression status and clinicopathological factors was investigated.Twenty freshfrozen samples were obtained for laser capture microdissection to analyze the splice variants of VEGF-A.RESULTS:VEGF-A was expressed in 53.9% and 42.4% of tumor and stromal cells,respectively.VEGF-A expression in tumor cells(t-VEGF-A) was associated with advanced clinical stage(stage 0,1/9;stage 1,2/16;stage 2,32/55;stage 3,38/66;stage 4,16/19,P < 0.0001).VEGF-A expression in stromal cells(s-VEGF-A) increased in the earlier clinical stage(stage 0,7/9;stage 1,6/16;stage 2,33/55;stage 3,22/66;stage 4,5/19;P = 0.004).Multivariate analyses for risk factors of recurrence showed that only s-VEGF-A expression was an independent risk factor for recurrence(relative risk 0.309,95% confidence interval 0.141-0.676,P = 0.0033).The five-year disease-free survival(DFS) rates of t-VEGF-A-positive and-negative cases were 51.4% and 62.9%,respectively.There was no significant difference in t-VEGF-A expression status.The five-year DFS rates of s-VEGF-A-positive and-negative cases were 73.8% and 39.9%,respectively.s-VEGFA-positive cases had significantly better survival than s-VEGF-A-negative cases(P = 0.0005).Splice variant analysis revealed that t-VEGF-A was mainly composed of VEGF165 and that s-VEGF-A included both VEGF165 and VEGF165b.In cases with no venous invasion(v0),the level of VEGF165b mRNA was significantly higher(v0 204.5 ± 122.7,v1 32.5 ± 36.7,v2 2.1 ± 1.7,P = 0.03).The microvessel density tended to be lower in cases with higher VEGF165b mRNA levels.CONCLUSION:s-VEGF-A appears be a good prognostic factor for colorectal cancer and includes VEGF165 and VEGF165b.

Effect of torsional mode phacoemulsification on cornea in eyes with/without pseudoexfoliation

AIM: To evaluate the effect of torsional mode phacoemulsification on central corneal thickness, corneal endothelial cell density, and morphology in eyes with/without pseudoexfoliation(PEX) syndrome.METHODS: Fourty-two consecutive patients with and42 patients without PEX as a control group scheduled for cataract surgery was studied. Phacoemulsification, using OZi L IP system, was performed with quick chop technique. Using noncontact specular microscopy, the central endothelial cell density(ECD), coefficient of variation, percentage of hexagonal cells, and the central corneal thickness(CCT) were evaluated preoperatively and postoperatively at 1, 7 and 30 d.RESULTS: The ECD in PEX syndrome was statistically significantly lower than that in the control group preoperatively and postoperatively(P ≤0.001).Percentage change in ECD was statistically significantly higher in PEX than that in control group after surgery follow up(P ≤0.04).There was no statistically significant difference between both groups comparing percentage of hexagonal cells and coefficient of variation in the cell size before and after the surgery. At 1 and 7d after surgery, percentage change in CCT was statistically significantly higher in PEX group than that in the control group(P ≤0.041).CONCLUSION: Although torsional mode phacoemulsification and intraocular lens(IOL) implantation provided a safe and favorable surgical outcome in patients with/without PEX, torsional phacoemulsification led to significantly higher ECD loss in the PEX group than that in the control group during the whole follow up period.In addition, more corneal swelling in the PEX group than that in the control group during the early postoperative period has indicated that the corneal endothelium, in presence of PEX endotheliopathy, seems to be more susceptible to the effects of phacoemulsification surgeryin eyes with PEX. The increased risk of anterior chamber manipulations in patients with PEX should be taken into account for an increased risk of bullous keratopathy.

Effect of Fe^(3+) on the growth and lipid content of Isochrysis galbana

Inducing lipid accumulation in microalgae cells without suppressing cell growth is vital to the economical production ofbiodiesel from microalgae. In two experiments, we demonstrate that the eel1 concentration and lipid content of marine microalgae Isochrysis galbana depend upon the iron concentration in the growth media. In Experiment I, adding chelated FeC13 to the medium at the late exponential growth phase prolonged this phase and increased the lipid content in I. galbana cells. The final cell density and lipid content of I. galbana supplemented with chelated FeC13 was approximately 2 and 1.65 times higher than that of non-supplemented cultures, respectively. In Experiment II, I. galbana cells in the late exponential phase were collected and re-inoculated into new media containing Fe3＋ at various concentrations. The final cell concentration and lipid content were maximized at the highest iron concentration （38% biomass by dry weight at 1.2×10^-5 mol/L Fe3＋）. In this study, intracellular neutral lipid storage was evaluated by fluorescent spectrophotometry using fluorochrome Nile red, and the measurement conditions were optimized.

Study of phytoplankton community in the channel from Dongting Lake to Changjiang River, China

Phytoplankton cell density, biomass, chl-α concentration and their seasonal fluctuations at five stations in the channel between Dongting Lake and the Changjiang （Yangtze） River were studied from May 1995 to December 1997. The seasonal fluctuations had two peaks in a year in general. The annual patterns of total cell density and biomass indicated that diatoms contributed more than 70 percent of the total biomass （except from June to October） during the investigation period. Twenty-one dominant species contributed about 60--80 percent of the biomass in various months. The cell density, biomass and seasonal fluctuation were similar at Stations 1-4, but at Station 5 connected directly with the Changjiang River, the annual mean values （127.34×10^4cells/L and 0.46 mg/L in 1996, 41.98×10^4ceUs/L and 0.2 mg/L in 1997 respectively） were lower than those （ 195.92× 10^4 cells/L and 0.5 mg/L in 1996, 132.96 ×10^4 cells/L and 0.57 mg/L in 1997 respectively） at Station 1-4; and the curve of the seasonal fluctuation sometimes did not coincide with those at Stations 1-4. Based on criteria for evaluating trophic status, the dominant species, annual average cell density values of 114.86× 10^4-179.57× 10^4 cells/L, biomass of 0.48-0.5 mg/L, chl-αconcentration of 0.42-0.51 μg/L respectively recorded at five stations in 1996 and 1997, and values associated with the physico-chemical properties of the waterbody indicated that the water in the channel could be characterized as oligo-mesotrophic.

Effects of Various Light-Emitting Diode(LED)Wavelengths on the Growth of Scenedesmus Obliquus Fachb-12 and Accumulation of Astaxanthin

Given the central role of light in the algal photosynthesis,respiration,cell division,growth and the accumulation of value products,the effects of light-emitting diodes(LEDs)light wavelengths(blue,white,red and green)were studied in Scenedesmus obliquus.Biomass,residual nutrient amount,soluble protein,astaxanthin and reactive oxygen species,superoxide dismutase(SOD),catalase(CAT)and peroxidase(POD)activity were analyzed to determine the effects of different monochromatic light wavelengths via biochemical methods.The results showed that blue light wavelength is the optimal light wavelength for phosphorus removal efficiency and the accumulation of biomass and astaxanthin in S.obliquus.Meanwhile,high reactive oxygen species content under the blue light might induce the accumulation of astaxanthin.The high activity of SOD,CAT and POD might participate in clearing the reactive oxygen species to facilitate the growth of microalgae.Furthermore,we found mixed blue/green lights treatment is the most appropriate mixture for the nitrogen removal.Under the blue light treatment,high light intensity and 18L:6D light cycle is the best condition for biomass and astaxanthin accumulation.Optimal nitrogen/phosphorus removal efficiency was observed under a 24L:0D light cycle.These results might provide a foundational data for the optimizing the productivity of high-value metabolites and treatment of wastewater.

Temporal and Spatial Distribution of Nutrients and HABs at Coastal Water of Kota Belud, Sabah

A study was carried out to determine the temporal and spatial distribution of nutrients and Harmful Algal Blooming species (HABs) to establish the relationship between nutrient concentrations and HABs density in the coastal water of Kota Belud, Sabah, Malaysia. Eight stations were set up in four transects (each transect had two stations;one 500 meters seawards from shoreline, and another five kilometers seawards from shoreline) along the Kota Belud coastal area. Phytoplankton samples, water samples and in situ environmental parameters were collected during dry and wet seasons. Altogether nine HABs species were identified from the study area, where six species (Pyrodinium bahamense, Prorocentum micans, Neoceratium furca, Prorocentum sigmoides, Dinophysis caudate, and Neoceratium fursus) belonged to Dinophyceae and three species (Thalassionema nitzchoioides, Chatoceros affinis, Rhizosolenia sp.) belonged to Bacillariophyceae. Among nine species, Chatoceros affinis was the most abundance composed of 80.6% of total species recorded from all stations during study period. Among the toxic producing Dinoflagellate, Pyrodinium bahamense bloom (>103 cells/l) was observed during study period. Trong linear relationship (r2 = 0.80) was observed between the cell density and concentration of nitrate nitrogen. Relationship between cell density and phosphate phosphorus was poor (r2 = 0.51). The study showed that increasing in nutrient concentrations resulted in the increasing of HABs density. Nitrate was seen to be more important than phosphate in Kota Belud water as limiting factor of the growth of HABs.

Comparison of two sampling methods when studying periphyton colonization in Lam Tsuen River, Hong Kong, China

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.

Phytoplanktonic desmids community in Donghu Lake, Wuhan, China

For compilation and comparison of desmids flora, the authors restudied the species composition, cell density and biomass of phytoplankton desmids collected at six stations in Donghu Lake at intervals of three months monitored from March of 1956 to February of 1957. A total of 122 taxa belonging to 16 genera were identified from qualitative and quantitative samples. Species of Cosmarium were the most popular ones occupy- ing about 41 % of the total species. Based on the observations, the annual mean values of the cell density and biomass were 132.11×102 cells/L and 0.09 mg/L. Cosmarium, Staurastrum, Staurodesmus and Closterium dominated and contributed more than 70 % of the total cell density and biomass at six stations in four seasons. The maximum species number, cell density and biomass in autumn revealed that the highest variety (64 taxa, 1296×102 cells/L and 0.889 mg/L respectively) occurred at Station 3 located in the southern part of Donghu Lake. From then on to the mid 1990s the desmids community decreased sharply in Donghu Lake, resulted clearly from eutrophication in the lake.