Crucial role of extracellular polysaccharides in desiccation and freezing tolerance in the terrestrial cyanobacterium Nostoc commune

The cyanobacterium Nostoc commune is adapted to the terrestrial environment and has a cosmopolitan distribution. In this study, the role of extracellular polysaccharides (EPS) in the desiccation tolerance of photosynthesis in N. commune was examined. Although photosynthetic O2 evolution was not detected in desiccated colonies, the ability of the cells to evolve O2 rapidly recovered after rehydration. The air-dried colonies contained approximately 10% (wt/wt) water, and field-isolated, natural colonies with EPS were highly water absorbent and were rapidly hydrated by atmospheric moisture. The cells embedded in EPS in Nostoc colonies were highly desiccation tolerant, and O2 evolution was not damaged by air drying. Although N. commune was determined to be a mesophilic cyanobacterium, the cells with EPS were heat tolerant in a desiccated state. EPS could be removed from cells by homogenizing colonies with a blender and filtering with coarse filter paper. This treatment to remove EPS did not damage Nostoc cells or their ability to evolve O2, but O2 evolution was significantly damaged by desiccation treatment of the EPS-depleted cells. Similar to the EPS-depleted cells, the laboratory culture strain KU002 had only small amount of EPS and was highly sensitive to desiccation. In the EPS-depleted cells, O2 evolution was also sensitive to freeze-thaw treatment. These results strongly suggest that EPS of N. commune is crucial for the stress tolerance of photosynthesis during desiccation and during freezing and thawing.     

The sniff as a unit of olfactory processing

Sniffing is a rhythmic motor process essential for the acquisition of olfactory information. Recent behavioral experiments show that using a single sniff rats can accurately discriminate between very similar odors and fail to improve their accuracy by taking multiple sniffs. This implies that each sniff has the potential to provide a complete snapshot of the local olfactory environment. The discrete and intermittent nature of sniffing has implications beyond the physical process of odor capture as it strongly shapes the flow of information into the olfactory system. We review electrophysiological studies-primarily from anesthetized rodents-demonstrating that olfactory neural responses are coupled to respiration. Hence, the "sniff cycle" might play a role in odor coding, by allowing the timing of spikes with respect to the phase of the respiration cycle to encode information about odor identity or concentration. We also discuss behavioral and physiological results indicating that sniffing can be dynamically coordinated with other rhythmic behaviors, such as whisking, as well as with rhythmic neural activity, such as hippocampal theta oscillations. Thus, the sniff cycle might also facilitate the coordination of the olfactory system with other brain areas. These converging lines of empirical data support the notion that each sniff is a unit of olfactory processing relevant for both neural coding and inter-areal coordination. Further electrophysiological recordings in behaving animals will be necessary to assess these proposals.     

Generation of medaka gene knockout models by target-selected mutagenesis

We have established a reverse genetics approach for the routine generation of medaka (Oryzias latipes) gene knockouts. A cryopreserved library of N-ethyl-N-nitrosourea (ENU) mutagenized fish was screened by high-throughput resequencing for induced point mutations. Nonsense and splice site mutations were retrieved for the Blm, Sirt1, Parkin and p53 genes and functional characterization of p53 mutants indicated a complete knockout of p53 function. The current cryopreserved resource is expected to contain knockouts for most medaka genes.     

Microbiological Studies of Phytopathogenic Bacteria

During investigations on the catabolism of carbohydrate by the bacteria of the genus Erwinia, it was found that a large amount of 2-ketogluconic acid was aerobically produced from glucose by several strains of the Erwinia amylovora group of bacteria, while no production of 5-ketogluconic acid was ascertained in their growing cultures.     

Oxygen Consumption by Pediococcus halophilus

The behavior toward oxygen of several strains of Pediococcus halophilus was studied. Although these organisms are generally regarded as facultative anaerobes, this investigation showed that resting cells of P. halophilus consumed oxygen at the expense of p-giucose or L-lactate as substrate.

The oxygen consuming activities among strains of soy pediococci varied from 7.06 to 11.63 (nmol/min/mg dry cells) with glucose and 5.52 to 6.59 with L-lactate, respectively. Oxidative metabolism of glucose increased acetate production with a corresponding decrease in lactate formation. Lactate oxidation with O₂. led to the formation of acetate. The oxygen consuming activity was not inhibited by any of the respiratory inhibitors tested such as KCN or NaN₃

NADH oxidase activity was found iri cell-free extracts of P. halophilus No, 51, which is capable of lowering the redox potential of the growth medium. A direct correlation between the abilities to consume oxygen and to reduce the redox potential has not been found so far, but this enzyme is considered to be involved in the aerobic metabolism.     

On the Utility of MIBG SPECT/CT in Evaluating Cardiac Sympathetic Dysfunction in Lewy Body Diseases

BackgroundAbnormal cardiac uptake of ¹²³I-metaiodobenzylguanidine (¹²³I-MIBG) is a diagnostic marker of Lewy body diseases (LBDs), e.g., Parkinson’s disease (PD) and dementia with Lewy bodies (DLB). Planar imaging is generally used to assess cardiac sympathetic dysfunction in ¹²³I-MIBG scintigraphy; however, its clinical utility requires further improvement. We hypothesized that the co-registration of single-photon emission tomography (SPECT) and computed tomography (CT) images would improve the diagnostic accuracy of ¹²³I-MIBG cardiac scintigraphy for LBDs. This study sought to evaluate the effects of SPECT/CT imaging on ¹²³I-MIBG cardiac scintigraphy for diagnosing LBDs.MethodsWe retrospectively investigated data of 54 patients (consecutive 18 patients in each PD, DLB, and idiopathic normal pressure hydrocephalus [iNPH] groups) who underwent ¹²³I-MIBG cardiac scintigraphy (planar and SPECT/CT) because of suspected LBDs at the Tohoku University hospital from June 2012 to June 2015. We compared the diagnostic accuracies of the conventional planar ¹²³I-MIBG method and SPECT/CT methods (manual and semi-automatic).ResultsIn the conventional planar analysis, ¹²³I-MIBG uptake decreased only in the DLB group compared with the iNPH group. In contrast, the SPECT/CT analysis revealed significantly lower ¹²³I-MIBG uptake in both the PD and DLB groups compared with the iNPH group. Furthermore, a receiver operating characteristic analysis revealed that both the manual and semi-automatic SPECT/CT methods were superior to the conventional planar method in differentiating the 3 disorders.ConclusionsSPECT/CT ¹²³I-MIBG cardiac scintigraphy can detect mild cardiac sympathetic dysfunction in LDBs. Our results suggest that the SPECT/CT technique improves diagnostic accuracy for LBDs.     

Chromosome aberrations induced in vitro by low doses of radiation: nondisjunction in lymphocytes of young adults.

Epidemiological studies suggest radiation exposure as a cause of meiotic non-disjunction in humans, but experimental evidence with cytological proof has been lacking. Our results indicate that mitotic nondisjunction of lymphocyte chromosomes can also be induced by exposure to a low dose of radiation. Abnormal segregation can be induced not only when the cells are irradiated but also when nonirradiated cells are incubated with irradiated cell-free plasma or serum. The X and no. 21 chromosomes appear particularly susceptible to nondisjunction.     

zeta-Related protein kinase C in nuclei of nerve cells

To determine whether or not PKC is present in the nuclei of nerve tissue we made use of biochemical and immunocytochemical techniques. A 219-fold purification of rabbit brain nuclear protein kinase C was achieved by sequential steps of Triton X-100 extraction of isolated nuclei, DEAE-cellulose, Butyl-toyopearl and hydroxylapatite chromatography. The major peak of protein kinase C activity was eluted from the hydroxylapatite column at the KPO4 concentration of 0.3 M. Both Ca2+ and Ptd Ser were required for stimulation of the enzyme. Immunoblot analysis revealed that the kinase fraction was immunoreactive with a polyclonal antibody, PC-zeta, that had been raised against a peptide synthesized according to the deduced sequence of rat zeta protein kinase C. Light-microscopy revealed strong immunoreactivity in the nuclei of Purkinje cells in cerebellum and pyramidal cells in the rat cerebral cortex. These observations suggest that a zeta-related protein kinase C is present in the nuclei of nerve cells.     

Decorin modulates collagen matrix assembly and mineralization

Decorin (DCN) is one of the major matrix proteoglycans in bone. To investigate the role of DCN in matrix mineralization, the expression of DCN in MC3T3-E1 (MC) cell cultures and the phenotypes of MC-derived clones expressing higher (sense; S-DCN) or lower (antisense; AS-DCN) levels of DCN were characterized. DCN expression was significantly decreased as the mineralized nodules were formed and expanded in vitro. In S-DCN clones, in vitro matrix mineralization was inhibited, whereas in AS-DCN clones, mineralization was accelerated. At the microscopic level, collagen fibers in S-DCN clones were thinner while those of AS-DCN clones were thicker and lacked directionality compared to the controls. At the ultrastructural level, the collagen fibrils in S-DCN clones were markedly thinner, whereas those of AS-DCN clones were larger and irregular in shape. The results from Fourier transform infrared spectroscopy analysis demonstrated that in AS-DCN cultures the mineral content was greater but the crystallinity of mineral was poorer than that of the controls at early stage of mineralization. The in vivo transplantation assay demonstrated that no mineralized matrices were formed in S-DCN transplants, whereas they were readily detected in AS-DCN transplants at 3 weeks of transplantation. The areas of bone-like matrices in AS-DCN transplants were significantly greater than the controls at 3 weeks but became comparable at 5 weeks. The bone-like matrices in AS-DCN transplants exhibited woven bone-like non-lamellar structure while the lamellar bone-like structure was evident in the control transplants. These results suggest that DCN regulates matrix mineralization by modulating collagen assembly.