Sulfide utilization by the photosynthetic bacterium Chlorobium phaeobacteroides

Sulfide and sulfur are used by the photosynthetic bacterium Chlorobium phaeobacteroides as electron donors. Sulfide and sulfur consumption was found to be affected by sulfide concentration in the medium. Raising the sulfide concentration from 0.28 mM to 5.05 mM caused an increase in the amount of S⁼ utilized per growth unit from 0.58 mM to 2.32 mM. This increase in sulfide utilization was not reflected in a higher photosynthetic activity. Sulfide and sulfur consumption was also influenced by light intensity, with higher light intensity sulfide consumption was increased. In Lake Kinneret, Chlorobium phaeobacteroides did not bloom in the thermocline layer until sulfide concentrations reached 0.03–0.06 mM.     

Isolation of Two Novel WNT Genes, WNT14 and WNT15, One of Which (WNT15) Is Closely Linked to WNT3 on Human Chromosome 17q21

TheWntgene family consists of at least 15 structurally related genes that encode secreted extracellular signaling factors. Wnt proteins function in a range of critical developmental processes in both vertebrates and invertebrates and are implicated in regulation of cell growth and differentiation in certain adult mammalian tissues, including the mammary gland. We have isolated a number of WNT sequences from human genomic DNA, two of which, designated WNT14 and WNT15, represent novel members of theWntgene family. We also isolated WNT sequences from human mammary cDNA and present evidence that WNT13 is expressed in human breast tissue, in addition to those previously described. WNT14 and WNT15 appear to have originated from an ancestral branch of theWntgene family that also includes theWnt9sequences found in jawless and cartilaginous fishes. AWnt14cDNA was also isolated from chicken and a partialWnt15sequence from mouse. We show that human WNT14 maps to chromosome 1 and that WNT15 maps distal to BRCA1 on chromosome 17q21, where it lies within 125 kb of another WNT family member, WNT3.     

Label-free multiplexed virus detection using spectral reflectance imaging

We demonstrate detection of whole viruses and viral proteins with a new label-free platform based on spectral reflectance imaging. The Interferometric Reflectance Imaging Sensor (IRIS) has been shown to be capable of sensitive protein and DNA detection in a real time and high-throughput format. Vesicular stomatitis virus (VSV) was used as the target for detection as it is well-characterized for protein composition and can be modified to express viral coat proteins from other dangerous, highly pathogenic agents for surrogate detection while remaining a biosafety level 2 agent. We demonstrate specific detection of intact VSV virions achieved with surface-immobilized antibodies acting as capture probes which is confirmed using fluorescence imaging. The limit of detection is confirmed down to 3.5 × 10(5)plaque-forming units/mL (PFUs/mL). To increase specificity in a clinical scenario, both the external glycoprotein and internal viral proteins were simultaneously detected with the same antibody arrays with detergent-disrupted purified VSV and infected cell lysate solutions. Our results show sensitive and specific virus detection with a simple surface chemistry and minimal sample preparation on a quantitative label-free interferometric platform.     

湖水含盐量和Cu2+浓度变化对Kinneret湖浮游植物的影响

通过人为改变湖水中的Cu^2 浓度和含盐量的方法,Cu^2 浓度和含盐量变化对Kinneret湖水中浮游植物可能造成的影响进行了分析。结果表明,湖水Cu^2 浓度增加会抑制Kinneret湖水中藻类等浮游植物的生长。这对改善湖水水质来7说是非常有利的,但高的Cu^2 浓度对农作物生长和人类健康是有害的,在另一方面,对含盐量较低的约旦河水来说,适当增加Cu^2 浓度则有利于藻类的生长。Kinneret湖中浮游植物的年平均生物量随湖水含盐量的下降而有增加的趋势,特别是当含盐量低于200μ左右时,浮游植物中蓝藻占的比例会升高,这对作为饮用水资源的Kinneret湖水来说是不利的,由此可见,适当控制和维持Kinneret湖水Cu^2 浓度和含盐量对湖水水质保护具有重要的意义。     

Nitrogen Fixation by the Photosynthetic Sulfur Bacterium Chlorobium phaeobacteroides from Lake Kinneret

N₂ fixation by Chlorobium phaeobacteroides from Lake Kinneret was dependent on ammonia concentration and light intensity. In the thermocline of Lake Kinneret, N₂ fixation and photosynthesis were low. It was concluded that the bacteria do not contribute significantly to the organic nitrogen load of the lake.     

Investigations on the photosynthetic sulfur bacterium Chlorobium phaeobacteroides causing seasonal blooms in Lake Kinneret

Between May and December, the annual stratification period in Lake Kinneret, sulfide is formed and accumulates in the hypolimnion. In July-August a large population (up to 10(6) cells/mL) of green, photosynthetic, sulfur bacteria develops at the boundary of the oxidative and reductive zones of the water column lasting for 3--8 weeks. These bacteria were isolated from the lake and identified as Chlorobium phaeobacteroides. Optimal growth conditions included 160 mg S=L-1 and light intensities of 5--30 micron Einstein (micron E) m-2s-1. Glucose and acetate augmented growth when added to the mineral medium. The lowest light intensity which still supported growth was 0.3 micron E m-2s-1 when acetate was present and 1.0 micron E m-2s-1 when no organic substrate was present. Under complete darkness, either with or without organic substrate, the bacteria die. Photosynthetic activity was higher when no organic compound was added to the medium. Uptake of acetate was light-dependent. In the lake the photosynthetic activity of the bacteria is low because of the limited light intensity (0.3 micron E m-2s-1) at the bloom layer. It is suggested that the appearance and the disappearance of the bloom are caused by the influence of the daily internal seiche.     

Developmental distribution of CaM kinase II in the antennal lobe of the sphinx moth <Emphasis Type="Italic">Manduca sexta</Emphasis>

The antennal lobe (primary olfactory center of insects) is completely reorganized during metamorphosis. This reorganization is accompanied by changing patterns of calcium signaling in neurons and glial cells. In the present study, we investigated the developmental distribution of a major calcium-dependent protein, viz., calcium/calmodulin-dependent protein kinase II (CaM kinase II), in the antennal lobe of the sphinx moth Manduca sexta by using a monoclonal antibody. During synaptogenesis (developmental stages 6–10), we found a redistribution of CaM kinase II immunoreactivity, from a homogeneous distribution in the immature neuropil to an accumulation in the neuropil of the glomeruli. CaM kinase II immunoreactivity was less intense in olfactory receptor axons of the antennal nerve and antennal lobe glial cells. Western blot analysis revealed a growing content of CaM kinase II in antennal lobe tissue throughout metamorphosis. Injection of the CaM kinase inhibitor KN-93 into pupae resulted in a reduced number of antennal lobe glial cells migrating into the neuropil to form borders around glomeruli. The results suggest that CaM kinase II is involved in glial cell migration.This work was supported by the DFG LO779/2.     

人为因素导致的盐度变化对Kinneret湖水细菌种群的影响

由于Ｋｉｎｎｅｒｅｔ湖周围的诸多盐泉被人为地导入其下游的约旦河,使得Ｋｉｎｎｅｒｅｔ湖水的盐度逐渐下降,这对作为主要工家业用水和饮用水资源的Ｋｉｎｎｅｒｅｔ湖来说是非常有价值的。然而,对湖水中的细菌来说则可能产生不同的影响。作者通过实验研究发有水盐度的变化导致细菌种群的改变,从而使我们观察到盐度与细菌之间的关系。这些结果表明,盐度变化对湖水水质保护对策和将来一段时间内湖水管理政策的制定都具有重要的