Microspectrophotometric and scanning microphotometric studies of carp (Cyprinus carpio L.) erythrocytes

Carp (Cyprinus carpio) hemoglobin readily autoxidizes in blood smears. Quantification of Soret-band absorbance in individual erythrocytes by means of scanning cytophotometry therefore requires more elaborate methods of preparation of blood samples. Of the fixatives that have been tested, suspension of whole blood in isotonic salt solutions containing glutaraldehyde was most suitable. Glutaraldehyde-fixed red blood cells are totally resistant to hemolysis. In the course of fixation, hemoglobin is transformed to methemoglobin. Spectrophotometry indicated extensive similarities between glutaraldehyde-fixed carp methemoglobin and human methemoglobin. In aqueous solutions, the intensity of the Soret-peak was pH-dependent. The allosteric modifier organic polyphosphate caused an R----T transition, resulting in increased molar extinctions. Dried preparations showed Soret-spectra that were not influenced from either pH or organic polyphosphate concentration of the aqueous suspensions in which the erythrocytes had been stored. The same was true for slide preparations of cyanomethemoglobin, easily derived from methemoglobin on addition of potassium cyanide. In the absence of oxygen fresh blood cells from carp slowly transform their hemoglobin into deoxyhemoglobin. Spectra of the intermediate stages of deoxygenation, Hb4(O2)3, Hb4(O2)2 and Hb4(O2), as well as mixtures of these intermediates, could be monitored.     

The transition point for protein synthesis in late S-G2 may be delayed by genome bromosubstitution without affecting the time of entry into mitosis

Bromosubstitution for most of the S period in synchronous populations of Allium cepa L. meristematic cells resulted in a delay in the late S-G2 transition point where protein synthesis is needed for later mitotic entrance to occur. This retardation in the position of the transition point was not accompanied by the expected delay in the entrance into mitosis, suggesting that such protein synthesis is a requisite, but not a timer for prophase triggering.     

A New Electrolyte Formulation for Securing High Temperature Cycling and Storage Performances of Na‐Ion Batteries

The Na‐ion battery is recognized as a possible alternative to the Li‐ion battery for applications where power and cost override energy density performance. However, the increasing instability of their electrolyte with temperature is still problematic. Thus, a central question remains how to design Na‐based electrolytes. Here, the discovery of a Na‐based electrolyte formulation is reported which enlists four additives (vinylene carbonate, succinonitrile, 1,3‐propane sultone, and sodium difluoro(oxalate)borate) in proper quantities that synergistically combine their positive attributes to enable a stable solid electrolyte interphase at both negative and positive electrodes surface at 55 °C. Moreover, the role of each additive that consists in producing specific NaF coatings, thin elastomers, sulfate‐based deposits, and so on via combined impedance and X‐ray photoelectron spectroscopy is rationalized. It is demonstrated that empirical electrolyte design rules previously established for Li‐ion technology together with theoretical guidance is vital in the quest for better Na‐based electrolytes that can be extended to other chemistries. Overall, this finding, which is implemented to 18 650 cells, widens the route to the rapid development of the Na‐ion technology based on Na₃V₂(PO₄)₂F₃/C chemistry.     

Solution structure of the N‐terminal domain of DC‐UbP/UBTD2 and its interaction with ubiquitin

DC‐UbP/UBTD2 is a ubiquitin (Ub) domain‐containing protein first identified from dendritic cells, and is implicated in ubiquitination pathway. The solution structure and backbone dynamics of the C‐terminal Ub‐like (UbL) domain were elucidated in our previous work. To further understand the biological function of DC‐UbP, we then solved the solution structure of the N‐terminal domain of DC‐UbP (DC‐UbP_N) and studied its Ub binding properties by NMR techniques. The results show that DC‐UbP_N holds a novel structural fold and acts as a Ub‐binding domain (UBD) but with low affinity. This implies that the DC‐UbP protein, composing of a combination of both UbL and UBD domains, might play an important role in regulating protein ubiquitination and delivery of ubiquitinated substrates in eukaryotic cells.     

Growth inhibitory effects of 5-aza-2'-deoxycytidine in HL-60 promyelocytic leukemia cells resistant to differentiation induction

In the original HL-60 cells (HL-60-S) and an HL-60 subline (HL-60-R) respectively susceptible and resistant to induction of differentiation by retinoic acid or dimethyl sulfoxide, 5-aza-2'-deoxycytidine inhibited growth equally but induced differentiation to a greater extent in HL-60-S. Flow cytometry showed that 5-aza-2'-deoxycytidine produced in both HL-60 lines an increased proportion of cells in G2+M rather than G0/G1 as with retinoic acid. 5-aza-2'-deoxycytidine may have a differentiation-inducing effect in HL-60 provided cells have the competence to differentiate, indicating the importance of an alternate mechanism of action.     

Comparison of optimization methods for fed-batch cultures of hybridoma cells

Two methods for the calculation of optimal trajectories for the input variables of a fed-batch culture of hybridoma cells are compared. It pointed out that a gradient method based on Pontryagins' minimum principle based yields a significant better performance with respect to computational effort and the calculated minimum than a dynamic programming approach which has been presented in a previous paper [1] as the most suitable method.     

Water inputs across a tropical montane landscape in Veracruz,Mexico: synergistic effects of land cover,rain and fog seasonality,and interannual precipitation variability

Land‐cover change can alter the spatiotemporal distribution of water inputs to mountain ecosystems, an important control on land‐surface and land‐atmosphere hydrologic fluxes. In eastern Mexico, we examined the influence of three widespread land‐cover types, montane cloud forest, coffee agroforestry, and cleared areas, on total and net water inputs to soil. Stand structural characteristics, as well as rain, fog, stemflow, and throughfall (water that falls through the canopy) water fluxes were measured across 11 sites during wet and dry seasons from 2005 to 2008. Land‐cover type had a significant effect on annual and seasonal net throughfall (NTF <0=canopy water retention plus canopy evaporation; NTF >0=fog water deposition). Forest canopies retained and/or lost to evaporation (i.e. NTF<0) five‐ to 11‐fold more water than coffee agroforests. Moreover, stemflow was fourfold higher under coffee shade than forest trees. Precipitation seasonality and phenological patterns determined the magnitude of these land‐cover differences, as well as their implications for the hydrologic cycle. Significant negative relationships were found between NTF and tree leaf area index (R²=0.38, P<0.002), NTF and stand basal area (R²=0.664, P<0.002), and stemflow and epiphyte loading (R²=0.414, P<0.001). These findings indicate that leaf and epiphyte surface area reductions associated with forest conversion decrease canopy water retention/evaporation, thereby increasing throughfall and stemflow inputs to soil. Interannual precipitation variability also altered patterns of water redistribution across this landscape. Storms and hurricanes resulted in little difference in forest‐coffee wet season NTF, while El Niño Southern Oscillation was associated with a twofold increase in dry season rain and fog throughfall water deposition. In montane headwater regions, changes in water delivery to canopies and soils may affect infiltration, runoff, and evapotranspiration, with implications for provisioning (e.g. water supply) and regulating (e.g. flood mitigation) ecosystem services.     

Is the mitochondrial precursor protein apocytochrome c able to pass a lipid barrier?

To obtain insight into the role of lipids in the translocation of extramitochondrially synthesized proteins, we studied the ability of apocytochrome c to pass lipid bilayers. With polyacrylamide gel electrophoresis, the digestion of externally added apocytochrome c by trypsin, enclosed in lipid vesicles, was followed. The experiments demonstrate that apocytochrome c is able to pass a lipid barrier and this process shows both a lipid- and protein specificity. The most probable molecular mechanisms involved in this phenomenon are discussed.