scholarly journals Induced Allelopathic Effects of Thalassiosira weissflogii on Colony Formation in Phaeocystis globosa

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 581
Author(s):  
Xiaodong Wang ◽  
Yiping Huo ◽  
Fan Yang ◽  
Yan Wang

Co-culturing and using cell-free filtrates are common methods for investigating allelopathy of marine phytoplankton; however, these methods often yield inconsistent or even contradictory results. The induced release of allelopathic compounds has been hypothesized as a mechanism to explain the discrepancy. Here, we used experiments to assess the inducibility of allelopathy by the diatom, Thalassiosira weissflogii, on the colony formation of Phaeocystis globosa. T. weissflogii and its cell-free filtrates showed inhibitory effects on the growth of solitary P. globosa cells. The colony number, colony diameter, and cells per colony decreased by co-occurring T. weissflogii cells but were enhanced by their extracellular filtrates alone. Living T. weissflogii cells possibly affect the colony integrity by reducing colonial cell density of P. globosa. When P. globosa and T. weissflogii were co-cultured but separated with a 2-µm membrane filter, thus allowing the exchange of extracellular secretions without direct cell contact, P. globosa colony concentration, colony diameter, cells per colony and colonial cell density were inhibited. Once T. weissflogii cells were pre-exposed to cell-free filtrates of P. globosa, their filtrates inhibited colony formation. T. weissflogii had allelopathic effects on P. globosa by releasing extracellular compounds that inhibited growth of solitary cells and colony formation, as well as disrupting colony integrity. However, the allelopathic effects of T. weissflogii on colony formation were only induced when the presence of P. globosa was perceived. Chemically mediated allelopathic effects of diatoms on colony formation of P. globosa may play an important role in the succession of diatoms and Phaeocystis.

2019 ◽  
Vol 44 (2) ◽  
pp. 82
Author(s):  
Maretha Amrayni ◽  
Elsa Gustianty ◽  
Susi Heryati ◽  
Andika Prahasta ◽  
Maula Rifada ◽  
...  

Introduction : The longterm use of topical antiglaucoma might cause ocular surface instability due to active substance or preservative used. Impression cytology examination may reveal superficial epithelial cells on conjunctiva and cornea, including goblet cells. Goblet cell density decrease is the most important parameter on evaluation of ocular surface disorder. Objective : This study was to understand ocular surface remodeling due to active substance of topical antiglaucoma with impression cytology examination among the patient prior and 3 months after therapy. Methods : This was a randomized controlled trial study with single blind masking. A total of 45 eyes from 31 patients were used as subject and distributed onto three groups treatment, which were timolol maleat 0.5%, latanoprost 0.005%, and latanoprost-timolol maleat fixed combination. All topical antiglaucoma in this study were preservative free. Result : There were differences between 3 groups in goblet cells density after 3 months therapy (p=0,030). Goblet cell density in timolol group was lower than latanoprost (p=0,041) and fixed combination (p=0,045). There was no significantly difference between 3 groups in conjunctival epithelial metaplasia degree (p=0,706) and cell to cell contact degree in corneal epithelial cells (p=0.66) after 3 months therapy. Conjunctival epithelial metaplasia degree were increased among group of timolol (p=0,008) and fixed combination (p=0,046). Conclusion : Timolol maleat 0,5% caused lower goblet cell density after 3 months therapy compare with latanoprost and fixed combination. There was no significantly difference in conjunctival epithelial metaplasia and cell to cell contact degree in corneal epithelial cells among these glaucoma treatment groups.


1985 ◽  
Vol 49 (12) ◽  
pp. 3583-3585 ◽  
Author(s):  
Takashi YAMAKAWA ◽  
Kazuya ONOMICHI ◽  
Tohru KODAMA ◽  
Yasuji MINODA

2000 ◽  
Author(s):  
Masanobu Ujihira ◽  
Yumi Matsumura ◽  
Chinatsu Kuroda ◽  
Koji Okaniwa ◽  
Kiyoshi Mabuchi

Abstract The effect of cell density on the post-thaw viability of cells in cryopreserved artificial tissue was studied. Human fibroblasts were three-dimensionally cultured for 2 days in a collagen sponge (ϕ20×1mm) as an extracellular matrix to imitate biological tissue (artificial tissue). Different cell densities for the artificial tissue were used, from 104 to 107 cells/cm3. Four artificial tissues were first stacked in a test chamber, then frozen at a slow or fast cooling rate (either 1 or 50°C/min) in a solution of Dulbecco’s Modified Eagle Medium, 20% Fetal Bovine Serum, and 10% dimethylsulfoxide, then kept frozen at −196°C for 2 hours, and finally thawed. The collagen matrix of the artificial tissue was dissolved using collagenase. Post-thaw viability of fibroblasts was evaluated by using a trypan blue exclusion assay. The experiments were prepared, and then the latent heat of artificial tissue (3.5×3.5×1mm) during the freezing process was measured by using a differential scanning calorimeter. Results show that with increasing cell density, the post-thaw viability decreased, whereas the latent heat was almost independent of cell density. With increasing cell density at the slow cooling rate, the degree of supercooling of the intracellular solution increased with decreasing temperature, possibly leading to intracellular freezing. Moreover, when the cell density was high, cell-to-cell contact or an obstruction to dehydration seemed to induce intracellular freezing. Therefore, the post-thaw viability seems to decrease as the number of cells exhibiting intracellular freezing increased.


2004 ◽  
Vol 73 (4) ◽  
pp. 1082-1089 ◽  
Author(s):  
Hirotoshi Shimada ◽  
Takemasa Ikeda ◽  
Jun-ichi Wakita ◽  
Hiroto Itoh ◽  
Sayuri Kurosu ◽  
...  

1983 ◽  
Vol 97 (3) ◽  
pp. 925-928 ◽  
Author(s):  
A L Acheson ◽  
H Thoenen

The specific activity of tyrosine hydroxylase (TH) in bovine adrenal chromaffin cells can be controlled by changing cell density. Chromaffin cells initially plated at low density (2-3 X 10(4) cells/cm2), and subsequently replated at a 10-fold higher density showed a sixfold increase in specific TH activity within 48 h, resulting from enhanced synthesis (increased number of TH molecules as demonstrated by immunotitration and blockade by cycloheximide) rather than activation. The density-mediated TH induction was blocked by inhibitors of both messenger RNA synthesis (alpha-amanitin) and processing (9-beta-arabinofuranosyladenine), indicating a transcriptional level of regulation. Medium conditioned by high density replated cells could not mimic the effect of high density plating itself, thus direct cell contact, rather than a diffusible factor, is responsible for the density-mediated TH induction. Since neither acetylcholinesterase nor lactate dehydrogenase specific activities were increased by high cell density, it can be concluded that the contact-mediated induction of TH is rather specific, and not the result of a general process of enzyme induction.


2015 ◽  
Vol 3 (6) ◽  
Author(s):  
Lucie Gallot-Lavallée ◽  
António Pagarete ◽  
Matthieu Legendre ◽  
Sebastien Santini ◽  
Ruth-Anne Sandaa ◽  
...  

We report the complete genome sequence of CeV-01B, a large double-stranded DNA virus infecting the unicellular marine phytoplankton Haptolina (formerly Chrysochromulina ) ericina. CeV-01B and its closest relative Phaeocystis globosa virus define an emerging subclade of the Megaviridae family with smaller genomes and particles than the originally described giant Mimiviridae infecting Acanthamoeba .


2019 ◽  
Vol 38 (9) ◽  
pp. 1060-1068
Author(s):  
Y Chen ◽  
H Feng ◽  
H Zhang ◽  
X Li

We examined the role of DNA methyltransferase 1 (DNMT1) in N-methyl- N′-nitro- N-nitrosoguanidine (MNNG)–induced malignant transformation of Kazakh esophageal epithelial (EE) cells to better understand the pathogenesis of esophageal cancer (EC). The 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di- phenytetrazoliumromide method and colony formation assays were performed to determine the MNNG dose for malignant transformation. Colony formation assays showed the effects of different frequencies of MNNG exposure and different cell passages on malignant transformation. A nude mouse tumor experiment indicated the malignancy of Kazakh EE cells expressing high DNMT1 levels and of transformed cells. The result shows that when the dose, frequency, and time of MNNG exposure increased, cell morphology became irregular, cell-contact suppression disappeared, and cell tolerance and growth rate increased. Colony formation occurred in the Kazakh-DNMT1 group after 14 transfections and 27 passages. Significant differences in DNMT1 mRNA and protein levels were observed in different types of cells and tumor tissues ( F = 140.644, p < 0.001; F = 105.545, p < 0.001). Our study demonstrated that DNMT1 could promote MNNG to induce malignant transformation of EE cells, and this study will help understand EC better in order to develop appropriate treatment strategies.


1998 ◽  
Vol 275 (6) ◽  
pp. C1473-C1480 ◽  
Author(s):  
Kenneth M. Hershman ◽  
Edwin S. Levitan

Regulation of voltage-gated K+channel genes represents an important mechanism for modulating cardiac excitability. Here we demonstrate that expression of two K+channel mRNAs is reciprocally controlled by cell-cell interactions between adult cardiac myocytes. It is shown that culturing acutely dissociated rat ventricular myocytes for 3 h results in a dramatic downregulation of Kv1.5 mRNA and a modest upregulation of Kv4.2 mRNA. These effects are specific, because similar changes are not detected with other channel mRNAs. Increasing myocyte density promotes maintenance of Kv1.5 gene expression, whereas Kv4.2 mRNA expression was found to be inversely proportional to cell density. Conditioned culture medium did not mimic the effects of high cell density. However, paraformaldehyde-fixed myocytes were comparable to live cells in their ability to influence K+channel message levels. Thus the reciprocal effects of cell density on the expression of Kv1.5 and Kv4.2 genes are mediated by direct contact between adult cardiac myocytes. These findings reveal for the first time that cardiac myocyte gene expression is influenced by signaling induced by cell-cell contact.


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