Bioenergetics of sulphate-reducing bacteria in relation to their environmental impact

The cellular physiology of the sulphate-reducing bacteria, and of other sulphidogenic species, is determined by the energetic requirements consequent upon their respiratory mode of metabolism with sulphate and other oxyanions of sulphur as terminal electron acceptors. As a further consequence of their, relatively, restricted catabolic activities and their requirement for conditions of anaerobiosis, sulphidogenic bacteria are almost invariably found in nature as component organisms within microbial consortia. The capacity to generate significant quantities of sulphide influences the overall metabolic activity and species diversity of these consortia, and is the root cause of the environmental impact of the sulphidogenic species: corrosion, pollution and the souring of hydrocarbon reservoirs.     

Physiology and tactic response of the phototrophic consortium “Chlorochromatium aggregatum”

The phototrophic consortium “Chlorochromatium aggregatum” was enriched from sediment samples of a eutrophic freshwater lake and was maintained at high numbers in anoxic sulfide-reduced medium. Growth of intact consortia was observed only in the light and in the presence of 2-oxoglutarate as an organic carbon source. Consortia of “C. aggregatum” reached maximum growth rates at light intensities ≥ 5 μmol quanta m^–2 s^–1. Of ten compounds tested, sulfide, thiosulfate, 2-oxoglutarate, and citrate served as a chemoattractant for “C. aggregatum”. When incubated in the presence of sulfide and in the light, epibionts reduced the fluorochrome 5-cyano-2,3-di-4-tolyl-tetrazolium chloride (CTC). Reduction of CTC was not observed in the presence of the uncoupler carbonyl cyanide m-chlorophenylhydrazone (CCCP) or in the dark, indicating that sulfide serves as an electron donor for the phototrophic epibiont. Motile consortia accumulated scotophobically in microcuvettes at a wavelength of 740 nm. Since this wavelength corresponds to the position of the absorption maximum of bacteriochlorophylls c or d, the photosynthetic pigments are most likely the photoreceptors of the scotophobic response. It is concluded that, within the consortia, a rapid interspecies signal transfer occurs between the nonmotile, green-colored epibiont and the motile, colorless central bacterium. Received: 27 May 1997 / Accepted: 5 September 1997     

Two new motile phototrophic consortia: “Chlorochromatium lunatum” and “Pelochromatium selenoides”

Two new phototrophic consortia, “Chlorochromatium lunatum” and “Pelochromatium selenoides”, were observed and collected in the hypolimnion of several dimictic lakes in Wisconsin and Michigan (USA). The two consortia had the same morphology but different pigment composition. The cells of the photosynthetic components of the consortia were half-moon-shaped. This morphology was used to differentiate them from the previously described motile phototrophic consortia “Chlorochromatium aggregatum” and “Pelochromatium roseum”. These phototrophic cells did not resemble any described unicellular green sulfur bacteria. The predominant pigments detected were bacteriochlorophyll d and chlorobactene for the green-colored “Clc. lunatum”, and bacteriochlorophyll e and isorenieratene for the brown-colored “Plc. selenoides”. Their pigment compositions and the presence of chlorosomes attached to the inner face of the cytoplasmic membrane in both kinds of photosynthetic cells confirmed this new half-moon-shaped morphotype as a green sulfur bacterium. Both consortia were found thriving in lakes with low concentrations of sulfide (< 60 μM), below the layers of “Clc. aggregatum” and “Plc. roseum”. The green consortia were observed in lakes where the oxic-anoxic interface was located at shallow depths (2–7 m), while the brown consortia were found at greater depths (8–16 m). The two newly described consortia were never detected together at the same depth in any lake. Received: 30 April 1997 / Accepted: 17 January 1998     

Ostrya virginiana (Betulaceae)的胚珠和胚囊发育及其系统学意义

首次报道了铁木属Ostrya的胚珠和胚囊发育过程。研究结果表明: O. virginiana的多数子房 内有2个胚珠,胚珠倒生,单珠被,厚珠心,具1至数个孢原细胞;孢原细胞子周分裂形成一个周缘细胞 和一个造孢细胞,造孢细胞直接发育成大孢子母细胞,四分体大孢子呈线形排列,它们均可成为功能大 孢子;绝大多数胚珠中具2～6个胚囊,胚囊蓼型。最后,对珠被层数和多孢原、多胚囊等问题进行了讨 论,并对桦木科各属的胚胎学性状作了比较,发现桦木科各属的胚胎学特征具有较高的一致性,如多孢 原、多胚囊,较长的传粉和受精间隔期等。同时,比较和讨论了某些胚胎学性状,如胚珠类型和珠被层数,在高等金缕梅类各科间的异同及系统学意义。     

Morphogenetic and neuronal characterization of human neuroblastoma multicellular spheroids cultured under undifferentiated and all-trans-retinoic acid-differentiated conditions

In this study, we aimed to compare the morphogenetic and neuronal characteristics between monolayer cells and spheroids. For this purpose, we established spheroid formation by growing SH-SY5Y cells on the hydrophobic surfaces of thermally-collapsed elastin-like polypeptide. After 4 days of culture, the relative proliferation of the cells within spheroids was approximately 92% of the values for monolayer cultures. As measured by quantitative assays for mRNA and protein expressions, the production of synaptophysin and neuronspecific enolase (NSE) as well as the contents of cell adhesion molecules (CAMs) and extracellular matrix (ECM) proteins are much higher in spheroids than in monolayer cells. Under the all-trans-retinoic acid (RA)-induced differentiation condition, spheroids extended neurites and further up-regulated the expression of synaptophysin, NSE, CAMs, and ECM proteins. Our data indicate that RA-differentiated SH-SY5Y neurospheroids are functionally matured neuronal architectures. [BMB Reports 2013; 46(5): 276-281]     

The potential of glycerol in freezing preservation of turbine oil-degrading bacterial consortium and the ability of the revised consortium to degrade petroleum wastes

The turbine oil (TuO)-degrading bacterial consortium Tank-2 (original Tank-2) was preserved as a glycerol stock at −80 °C from 2009 to 2012. Storage methods have been unavailable so far for any TuO-degrading bacterial consortia or isolates. To evaluate the usefulness of glycerol stock, the original Tank-2 consortium frozen in glycerol at −80 °C was thawed and then revived by repeated culture in mineral salts medium (MSM) containing 0.5% (w/w) TuO (revived Tank-2). The revived Tank-2 consortium exhibited a high activity to degrade TuO, which was equivalent to that of original Tank-2. It also degraded car engine oil, used car engine oil, Arabian light and Vityaz crude oils and TuO in wastewater. These results indicated that a glycerol stock at −80 °C was useful for storing Tank-2. PCR-denaturing gradient gel electrophoresis (DGGE) that targeted the V3 regions of 16S rRNA gene sequences showed that the DGGE band profiles of principal bacteria were significantly different between the original and revived Tank-2 consortia and between the revived Tank-2 culture grown in MSM containing TuO and that grown in MSM containing other types of petroleum products. This suggested that bacterial strains inherently residing in Tank-2 could adjust their compositions based on the storage and culture conditions.     

Spheroids of granulosa cells provide an in vitro model for programmed cell death coupled to steroidogenesis

We describe the use of rotary cultures (72 rpm) as an excellent method for generating spheroids from dispersed bovine granulosa cells (GC). The GC spheroids were symmetrical (diameter between 100 and 200 μm), easily accessible, and could be obtained at high yields. On day one, the spheroids showed a two-layered outer zone of cells that stained lighter than the inner zone in semi-thin sections. Bromodeoxyuridine (BrdU) uptake was frequent and randomly distributed. By day two, a striking decrease in BrdU uptake was noted. Apoptotic bodies appeared up to day four, as did TUNEL and propidium iodide labelled dead cells. At that time, the inner zone contained cells with large-sized vacuoles and the core was amorphous. The large-sized vacuoles were identified at the ultrastructural level and represented autophagosomes and autophagolysosomes that were in different stages of development. Surprisingly, conspicuous signs of cell death were accompanied by an increase in spontaneous luteinization compared to conventional stationary cultures. We detected high levels of progesterone (immunoassay) accompanied by high levels of the proteins and enzymes relevant for steroidogenesis (StAR, P450scc, 3β-HSD by immunoblot and immunohistochemistry, respectively).     

Activated packed bed bioreactor for rapid nitrification in brackish water hatchery systems

A packed bed bioreactor (PBBR) was developed for rapid establishment of nitrification in brackish water hatchery systems in the tropics. The reactors were activated by immobilizing ammonia-oxidizing (AMONPCU-1) and nitrite-oxidizing (NIONPCU-1) bacterial consortia on polystyrene and low-density polyethylene beads, respectively. Fluorescence in situ hybridization demonstrated the presence of autotrophic nitrifiers belong to Nitrosococcus mobilis, lineage of β ammonia oxidizers and nitrite oxidizer Nitrobacter sp. in the consortia. The activated reactors upon integration to the hatchery system resulted in significant ammonia removal (P < 0.01) culminating to its undetectable levels. Consequently, a significantly higher percent survival of larvae was observed in the larval production systems. With spent water the reactors could establish nitrification with high percentage removal of ammonia (78%), nitrite (79%) and BOD (56%) within 7 days of initiation of the process. PBBR is configured in such a way to minimize the energy requirements for continuous operation by limiting the energy inputs to a single stage pumping of water and aeration to the aeration cells. The PBBR shall enable hatchery systems to operate under closed recirculating mode and pave the way for better water management in the aquaculture industry.     

Pannexin1 drives multicellular aggregate compaction via a signaling cascade that remodels the actin cytoskeleton

Pannexin 1 (Panx1) is a novel gap junction protein shown to have tumor-suppressive properties. To model its in vivo role in the intratumor biomechanical environment, we investigated whether Panx1 channels modulate the dynamic assembly of multicellular C6 glioma aggregates. Treatment with carbenoxolone and probenecid, which directly and specifically block Panx1 channels, respectively, showed that Panx1 is involved in accelerating aggregate assembly. Experiments further showed that exogenous ATP can reverse the inhibitive effects of carbenoxolone and that aggregate compaction is sensitive to the purinergic antagonist suramin. With a close examination of the F-actin microfilament network, these findings show that Panx1 channels act as conduits for ATP release that stimulate the P(2)X(7) purinergic receptor pathway, in turn up-regulating actomyosin function. Using a unique three-dimensional scaffold-free method to quantify multicellular interactions, this study shows that Panx1 is intimately involved in regulating intercellular biomechanical interactions pivotal in the progression of cancer.