Evaluation of Diquat as a Potential Algicide for Controlling the Musty-Odor-Producing Cyanobacterium,Oscillatoria perornata,in Catfish Aquaculture Ponds

ABSTRACT

The synthetic herbicide diquat was applied to a catfish aquaculture pond containing a heavy bloom of the cyanobacterium Oscillatoria perornata(a major contributor to musty off-flavor in farm-raised catfish) in order to determine the effectiveness of diquat as a selective algicide to prevent musty off-flavor in cultured catfish. Levels of the musty-odor compound 2-methylisoborneol (MIB) and numbers of O. perornata were monitored. Results indicate that diquat is not useful as an algicide for controlling O. perornata in catfish aquaculture ponds, despite its usefulness in controlling other aquatic weeds.     

Marine Cyanobacteria Compounds with Anticancer Properties: A Review on the Implication of Apoptosis

Marine cyanobacteria have been considered a rich source of secondary metabolites with potential biotechnological applications, namely in the pharmacological field. Chemically diverse compounds were found to induce cytoxicity, anti-inflammatory and antibacterial activities. The potential of marine cyanobacteria as anticancer agents has however been the most explored and, besides cytotoxicity in tumor cell lines, several compounds have emerged as templates for the development of new anticancer drugs. The mechanisms implicated in the cytotoxicity of marine cyanobacteria compounds in tumor cell lines are still largely overlooked but several studies point to an implication in apoptosis. This association has been related to several apoptotic indicators such as cell cycle arrest, mitochondrial dysfunctions and oxidative damage, alterations in caspase cascade, alterations in specific proteins levels and alterations in the membrane sodium dynamics. In the present paper a compilation of the described marine cyanobacterial compounds with potential anticancer properties is presented and a review on the implication of apoptosis as the mechanism of cell death is discussed.     

蓝藻水华暴发与水体细菌关系的研究进展

近年来随着高密度集约化养殖的迅猛发展,营养物质的高投入导致了养殖水体自身污染严重,使得蓝藻频繁爆发,不仅严重破坏水体生态系统结构而且产生毒素威胁人类健康。蓝藻又称蓝细菌(Cyanobacteria),是一类能进行产氧性光合作用的大型原核微生物,其细胞结构和代谢机理与真核藻类截然不同。了解富营养化水体的细菌群落结构及其演替规律是研究蓝藻水华形成机理的核心。     

Initial Carbon Storage in New Tephra Layers of Mt. Talang in Sumatra as Affected by Pioneer Plants

To date, no global data on carbon sequestration at the initial weathering phase of tephra deposits are available. To study carbon storage in the new volcanic deposit, tephra layers were reconstructed for a period of 46 months. The tephra samples were collected immediately after eruption of Mount (Mt.) Talang on 12 April 2005, over portions of the Solok District in West Sumatra, Indonesia. Pot experiments were filled with and without soil materials and covered with the collected tephra. The pot experiments were conducted in a wired house. The tephra was applied in 0, 2.5 and 5 cm depths to simulate natural tephra deposition. Every day 250 ml of filtered water was added and allowed to percolate. Solid fraction from the tephra layer was collected and analyzed at regular intervals and primary plant succession was observed over a period of 4 years. After 2 months, blue-green algae (cyanobacteria) started to colonize the bare surface tephra layer to form an algae mat. After 16 months, the surface was transformed into a green biofilm of lichen. Vascular plants (grasses and shrubs) started to be established after 2 years. Total carbon (TC) content of the tephra layer was increased significantly from 0.19 to 1.75% or eight times higher after 46 months of incubation. Higher TC storage was found in the 2.5 cm compared to that of the 5.0 cm tephra layer, which was reconstructed above the soil, with values of 1.75 and 0.89%, respectively. On the contrary, lesser amount of TC was accumulated in the single tephra layer (without soil underneath). Between 71 and 90% of TC was considered as total organic carbon (TOC). The labile organic carbon (LOC) content in the 2.5 cm and 5.0 cm of tephra layer was found to be 0.22 and 0.77%, respectively, at the end of incubation. This experiment confirmed the potential of tephra to capture carbon from the atmosphere with the help of nonvascular plants and then by vascular plants and finally sink them in the tephra layer.     

Micronutrient enrichment mediated by plant-microbe interactions and rice cultivation practices

A field experiment was conducted to evaluate the effect of different plant growth promoting microorganisms (PGPM) on micronutrient enrichment of rice crops grown under conventional (flooded) and SRI (System of Rice Intensification) practices. Significant differences were recorded among treatments and cultivation practices in terms of soil microbial activity reflected in enhanced nutrient uptake, enzyme activity, and yield. The Anabaena-based biofilm inoculants were particularly superior under both methods of cultivation, leading to 13–46% enhancement of iron and 15-41% enhancement of zinc in rice grains over uninoculated controls. SRI was found to be superior in terms of enhancing the concentration of zinc, copper, iron, and manganese (Zn, Cu, Fe and Mn), particularly in grains, and significant in increasing the activity of defense- and pathogenesis- related enzymes and yield parameters. This study illustrates the utility of cyanobacteria-based inoculants for both methods of rice cultivation and their significant interactions with the plant, leading to micronutrient enrichment of rice grains. Such formulations can complement the current biofortification strategies and help in combating the problems of malnutrition globally.     

The “Tears of the Virgin” at Lakes Entrance,southeast Australia were made by the intertidal barnacle Chthamalus antennatus (Cirripedia: Thoracica) and cyanobacteria

Curious eroded depressions, most resembling an eye shedding an elongate tear, are found in gently sloping, intertidal, carbonate‐rich arenite outcropping on the sea coast near Lakes Entrance, Victoria, southeast Australia. The depressions, known locally as “Tears of the Virgin,” are evidently formed by multiple generations of a barnacle, Chthamalus antennatus Darwin, 1854 in association with cyanobacteria. While the round part of a depression offers the barnacle a modicum of protection from impacts during high tides, it is also partially inhabited by cyanobacteria, which extend into and tend to fill the elongate tear. As such, this appears to be the first case of mutualism between a higher invertebrate and cyanobacteria, with the cyanobacteria reducing the barnacle's risk of desiccation while receiving metabolic wastes from it during low tides. It is also the first record of a balanomorph barnacle eroding calcareous arenite beneath its shell, the net effect of which would be expected to reduce its adhesion to the substrate. However, the siliceous residue, resulting from the barnacle's dissolution of the more than 80% of the calcite‐rich sedimentary rock, is sequestered in delicate folds on the inside of the shell wall as it grows. A brief review of cirripedes capable of excavation includes the first photographic documentation of excavation of a mollusc shell by a verrucomorph.     

New Peptides Isolated from Lyngbya Species: A Review

Cyanobacteria of the genus Lyngbya have proven to be prodigious producers of secondary metabolites. Many of these compounds are bioactive and show potential for therapeutic use. This review covers peptides and hybrid polyketide-non-ribosomal peptides isolated from Lyngbya species. The structures and bioactivities of 50 Lyngbya peptides which were reported since 2007 are presented.     

Macrolactone Nuiapolide,Isolated from a Hawaiian Marine Cyanobacterium,Exhibits Anti-Chemotactic Activity

A new bioactive macrolactone, nuiapolide (1) was identified from a marine cyanobacterium collected off the coast of Niihau, near Lehua Rock. The natural product exhibits anti-chemotactic activity at concentrations as low as 1.3 μM against Jurkat cells, cancerous T lymphocytes, and induces a G2/M phase cell cycle shift. Structural characterization of the natural product revealed the compound to be a 40-membered macrolactone with nine hydroxyl functional groups and a rare tert-butyl carbinol residue.     

尼罗与奥利亚罗非鱼对池塘蓝藻水华及水质影响的研究

利用尼罗罗非鱼和奥利亚罗非鱼进行了池塘抑藻试验,采用血球计数板测定水体中的微囊藻密度,并对水体理化性质进行了检测分析。试验结果表明,罗非鱼能有效消减水体中蓝藻生物量,降低水体藻毒素浓度,并对水体TN、TP产生一定影响。其中奥利亚罗非鱼试验组蓝藻初始密度为1．53-108cells／L,下降至0．86-108eells／L,降低43．79％;尼罗罗非鱼组蓝藻初始密度为1．54-108cells／L,下降至O．51×108cells,L,降低66．88％。水体总磷含量无显著变化,总氮含量有所下降,水体微囊藻毒素MC—LR含量随着蓝藻密度的下降而降低,并讨论了尼罗与奥利亚罗非鱼摄食抑制蓝藻的摄食抑制及其对水质的影响。