Enhancement of biomass and fermentation activity of surplus brewers' yeast in a fed-batch process

The growth of surplus brewers' yeast in a fed-batch process was studied with the aim of increasing the fermentation activity of the yeast cells and of optimizing the growth conditions: 20 h cultivation at 30° C and pH 5.0–5.5 using beet molasses as substrate, with a regulated feeding rate, showed satisfactory results. Under the chosen conditions, the final amount of biomass increased more than fivefold, achieving a specific growth rate of 0.1 h^–1 and substrate yield coefficient of 0.54 g·g^–1. The increase in fermentation activity of yeast cells during cultivation correlated very well with the concentration of reduced glutathione, which increased from 1.2 to 2.7 mg·g^–1 (dry matter). At the same time the fermentation activity increased fivefold, which related to the nitrogen content of the yeast cells. Ethanol formation throughout the cultivation did not exceed 0.5 g·l^–1. Correspondence to: B. Strel     

Genetic differentiation in a captive population of the endangered Siberian crane (Grus leucogeranus Pall.)

DNA fingerprinting, followed by multivariate analysis of data, was used to characterize genetic heterogeneity in captive populations of the endangered Siberian and sandhill cranes. The genetic structure revealed reflected the natural population and species distributions. The relevant groups differed not only from each other, but also from interspecies and inter-population hybrids bred in captivity. In this study we have tested an approach to the analysis of population structure based on individual genotypes. Interpretation of fingerprinting data by means of the analytical system applied here is a useful and reliable procedure for the estimation of genetic relationships between individuals.     

Deletion analysis of the SUP35 gene of the yeast Saccharomyces cerevisiae reveals two non-overlapping functional regions in the encoded protein

SUP35is an omnipotent suppressor gene of Saccharomyces cerevisiae coding for a protein consisting of a C-terminal part similar to the elongation factor EF-1α and a unique N-terminal sequence of 253 amino acids. Twelve truncated versions of the SUP35 gene were generated by the deletion of fragments internal to the coding sequence. Functional studies of these deletion mutants showed that: (i) only the EF-1α-like C-terminal part of the Sup35 protein is essential for the cell viability; (ii) overexpression of either the N-terminal part of the Sup35 protein or the full-length Sup35 protein decreases translational fidelity, resulting in omnipotent suppression and reduced growth of [psi⁺] strains; (iii) expression of the C-terminal part of the Sup35 protein generates an antisuppressor phenotype; and (iv) both the N- or C-terminal segments of the Sup35 protein can bind to 80S ribosomes. Thus, the data obtained define two domains within the Sup35 protein which are responsible for different functions.     

Spontaneous allelic variant in deafness–blindness gene Ush1g resulting in an expanded phenotype

Relationships between novel phenotypic behaviors and specific genetic alterations are often discovered using target-specific, directed mutagenesis or phenotypic selection following chemical mutagenesis. An alternative approach is to exploit deficiencies in DNA repair pathways that maintain genetic integrity in response to spontaneously induced damage. Mice deficient in the DNA glycosylase NEIL1 show elevated spontaneous mutations, which arise from translesion DNA synthesis past oxidatively induced base damage. Several litters of Neil1 knockout mice included animals that were distinguished by their backwards-walking behavior in open-field environments, while maintaining frantic forward movements in their home cage environment. Other phenotypic manifestations included swim test failures, head tilting and circling. Mapping of the mutation that conferred these behaviors showed the introduction of a stop codon at amino acid 4 of the Ush1g gene. Ush1g^bw/bw null mice displayed auditory and vestibular defects that are commonly seen with mutations affecting inner-ear hair-cell function, including a complete lack of auditory brainstem responses and vestibular-evoked potentials. As in other Usher syndrome type I mutant mouse lines, hair cell phenotypes included disorganized and split hair bundles, as well as altered distribution of proteins for stereocilia that localize to the tips of row 1 or row 2. Disruption to the bundle and kinocilium displacement suggested that USH1G is essential for forming the hair cell's kinocilial links. Consistent with other Usher type 1 models, Ush1g^bw/bw mice had no substantial retinal degeneration compared with Ush1g^bw/+ controls. In contrast to previously described Ush1g alleles, this new allele provides the first knockout model for this gene.     

Perspectives on the nanocarriers with miRNAs for targeting melanoma stemness through epigenetic regulation

Several research reports delineated the significant role of miRNAs in cancer proliferation, and their modulatory role in cancer mitigation, and drug resistance. Melanoma cells have been acquiring stemness to several chemotherapeutic agents through drug efflux proteins, epigenetic modulation, and DNA repair. miRNAs could be applied as novel therapeutic modalities for treating several kinds of cancers to modulate these mechanisms involved in stemness. Nanocarriers to carry these tumor-targeting miRNAs to modulate stemness are a prominent strategy to overcome their low penetrability, minimal stability, and nonspecificity. We have searched several public databases such as PubMed, Medline, Google scholar, and NLM and obtained the information pertinent to the miRNA-based nanocarrier systems to target stemness through epigenetic modulation in melanomas. This review delineates that various miRNAs can modulate the stemness in melanomas by specific intricate epigenetic signaling, and other cell-based signaling mechanisms. Specific nanocarrier formulations with specific miRNAs are optimal methods to deliver these miRNAs in order to achieve significant entrapment efficiency, loading efficiency, and stability. Furthermore, the combinatorial regimen of FDA-approved chemotherapeutic molecules with tumor-targeting miRNAs and chemotherapy combined with nanocarriers can efficiently deliver the utmost therapeutic window by targeting tumor matrix, invasion, metastasis, and angiogenesis in melanomas. Substantial research should focus on the clinical application of this gene therapy in melanomas using these low immunogenic, highly degradable, and biocompatible combinatorial nanotherapeutic regimens.     

Osmotic water permeability of cell membranes from Mesembryanthemum crystallinum leaves: effects of age and salinity

The osmotic water permeability ( P _os) of cell membranes isolated from leaves of 40-, 50- and 60-day-old Mesembryanthemum crystallinum plants was estimated by measuring light-scattering kinetics using stopped-flow spectrophotometry. The measurements were performed on the plasma membrane (PM), purified tonoplast (TP), and TP-enriched vesicles. The PM and TP-enriched vesicles were obtained by partitioning the microsomal fraction in an aqueous polymer two-phase system, whereas the purified TP vesicles were prepared by microsomal vesicle flotation on a sucrose cushion. The P _os of isolated membranes declined with plant age. The kinetic experiments showed that there was no difference between the P _os of the PM and TP isolated from plants of all ages. A 24-h exposure of plants to 400 m M NaCl caused a decline in the P _os as well. These findings suggest that, during M. crystallinum transition to CAM, which was induced by plant ageing or salinity, plant osmoregulatory responses included changes in the P _os of the leaf-cell membranes. These variations in the P _os are discussed in the context of adaptive mechanisms responsible for the maintenance of the water balance in the common ice plant.     

Similarity Between Naturally Occurring Modified Desialylated, Electronegative and Aortic Low Density Lipoprotein

The sialic acid content of electronegative low density lipoprotein (LDL) and LDL isolated from human aortic intima was measured. Sialic acid level in electronegative LDL of healthy subjects was 1.7-fold lower than in native LDL. Sialic acid content in electronegative LDL of coronary atherosclerosis patients was 3-fold lower than in native LDL. Lipoproteins isolated from grossly normal human aortic intima and from fatty streaks contained 20-56% less sialic acid as compared to blood plasma LDL. A negative correlation was established between the ability of electronegative and aortic LDL to stimulate lipid accumulation in cells cultured from uninvolved human aortic intima and lipoprotein sialic acid content. The results obtained indicate that electronegative and aortic LDLs have a low sialic acid content, i.e., are desialylated lipoproteins. Considered together with the fact that all known atherogenic LDLs have similar characteristics, our findings suggest that modified LDLs are the same lipoprotein particles subjected to multiple modification.     

Temperature and dissolved oxygen concentration as parameters of Azotobacter chroococcum cultivation for use in biofertilizers

Summary Azotobacter chroococcum was grown in continuous culture at two temperatures (30 °C and 20 °C) and different dissolved oxygen tensions (DOT) (30 % to 40 % and 70 % to 80 % of air saturation), respectively. At the temperature of 30 °C and low DOT a relatively high volumetric productivity and efficiency of nitrogen fixation were obtained. After lowering the temperature to 20 °C, an intensive formation of cysts was observed associated with a drastic decrease of the bacterial growth. Bacteria in the form of cysts kept their physiological activity for a long period of time depending on temperature and preparation.     

Alterations in chemical shifts and exchange broadening upon peptide boronic acid inhibitor binding to α-lytic protease

-Lytic protease, a bacterial serine protease of 198 aminoacids (19800 Da), has been used as a model system for studies of catalyticmechanism, structure–function relationships, and more recently forstudies of pro region-assisted protein folding. We have assigned thebackbones of the enzyme alone, and of its complex with the tetrahedraltransition state mimic N-tert-butyloxycarbonyl-Ala-Pro-boroVal, usingdouble- and triple-resonance 3D NMR spectroscopy on uniformly¹⁵N- and ¹³C/¹⁵N-labeled protein.Changes in backbone chemical shifts between the uncomplexed and inhibitedform of the protein are correlated with distance from the inhibitor, thedisplacement of backbone nitrogens, and change in hydrogen bond strengthupon inhibitor binding (derived from previously solved crystal structures).A comparison of the solution secondary structure of the uninhibited enzymewith that of the X-ray structure reveals no significant differences.Significant line broadening, indicating intermediate chemical exchange, wasobserved in many of the active site amides (including three broadened toinvisibility), and in a majority of cases the broadening was reversed uponaddition of the inhibitor. Implications and possible mechanisms of this linebroadening are discussed.     

Binding of divalent copper and calcium ions to poly I

The effect ot Cu²⁺ and Ca²⁺ ions, on the ultraviolet differential (UVD) spectra of single-stranded poly I was studied and the coordination (Δε_b) and conformation (Δε_c) conponents of the spectra calculated The comparison of Δε_b and the UVD spectrum of protonated IMP leads to the conclusion that N(7) ot inosine-5'-monophosphate (IMP) is a coordinating site tor Ca²⁺ and Cu²⁺ ions on the polymer bases. The binding ot Ca²⁺ and Cu²⁺ ions causes differently directed displacements of the four absorption bands of poly I, which are observed in the wavenumber range (50-34) × 10³ cm⁻¹ The calculation of concentration dependencies tor the association constants (K“) ot Ca²⁺ and Cu²⁺ ions binding to poly I bases shows that the binding is cooperative The K“ values for the poly I + Ca²⁺ complex are two orders of magnitude lower than those for the poly 1 + Cu²⁺ complex At low ion concentrations, binding to the poly I phosphates predominates and increases the degree of the polynucleotide helicity. At higher concentrations the spectra are mainly affected by the ion binding to bases, which results in melting of the helical parts of poly I At Ca²⁺ concentrations exceeding 10⁻³ M light-scattering aggregates are formed. The degree of monomer order in them is close to that observed in multistranded helices of poly I