Enzymatic prebleaching of sulphite pulps

The ability of a crude enzyme preparation ofAureobasidium pullulans containing xylanase [61 units (U)/ml] and xylosidase (3 U/ml) activity to remove pentosans from unbleached sulphite pulps was investigated. Greater amounts of pentosans and reducing sugars were released from the pulp when the enzyme dosages and incubation times were increased. A combination of enzyme hydrolysis and alkali extraction resulted in a greater removal of pentosans than using the enzyme preparation alone. By treatment with a xylanase loading of 450 U/g pulp for 24 h followed by alkaline extraction, 35% of the pentosans were removed. The kappa number decreased up to 30% whereas viscosity was only slightly affected by these treatments. Enzymatic hydrolysis released mainly xylose whereas xylobiose was the main product liberated by alkaline extraction. Scanning electron micrographs indicated improved fibrillation and flexibility of the fibre structure by enzyme treatment.     

Green-tissue-specific expression of a reconstructed cry1C gene encoding the active fragment of Bacillus thuringiensis delta-endotoxin in haploid tobacco plants conferring resistance to Spodoptera litura.

The DNA sequence of a truncated cry1C gene encoding the active fragment of Bacillus thuringiensis (Bt) delta-endotoxin was fully reconstructed by introduction of silent mutations. Each of the truncated wild type and the synthetic genes encoding the active fragment of the protoxin was introduced into haploid tobacco plants under the control of the rbcS promoter. To facilitate selection of transgenic tobacco plants with high insecticidal activity, a fusion gene encoding both rat CYP1A1 cytochrome P450 and yeast NADPH-P450 oxidoreductase was cotransformed with the wild type cry1C gene. The synthetic gene elevated the levels of Cry1C protein and the mRNA in transgenic tobacco plants as well as mortality in Spodoptera litura larvae. The Cry1C protein was accumulated mainly in the leaf tissues of the transgenic tobacco plants. The results reported here imply that the green-tissue-specific expression of the synthetic cry1C gene is useful for the control of S. litura which was rather resistant to the other types of Bt toxins.     

Functional requirement of noncoding Y RNAs for human chromosomal DNA replication

Noncoding RNAs are recognized increasingly as important regulators of fundamental biological processes, such as gene expression and development, in eukaryotes. We report here the identification and functional characterization of the small noncoding human Y RNAs (hY RNAs) as novel factors for chromosomal DNA replication in a human cell-free system. In addition to protein fractions, hY RNAs are essential for the establishment of active chromosomal DNA replication forks in template nuclei isolated from late-G(1)-phase human cells. Specific degradation of hY RNAs leads to the inhibition of semiconservative DNA replication in late-G(1)-phase template nuclei. This inhibition is negated by resupplementation of hY RNAs. All four hY RNAs (hY1, hY3, hY4, and hY5) can functionally substitute for each other in this system. Mutagenesis of hY1 RNA showed that the binding site for Ro60 protein, which is required for Ro RNP assembly, is not essential for DNA replication. Degradation of hY1 RNA in asynchronously proliferating HeLa cells by RNA interference reduced the percentages of cells incorporating bromodeoxyuridine in vivo. These experiments implicate a functional role for hY RNAs in human chromosomal DNA replication.     

Fragment-based screening of programmed death ligand 1 (PD-L1)

The PD-1 immune checkpoint pathway is a highly validated target for cancer immunotherapy. Despite the potential advantages of small molecule inhibitors over antibodies, the discovery of small molecule checkpoint inhibitors has lagged behind. To discover small molecule inhibitors of the PD-1 pathway, we have utilized a fragment-based approach. Small molecules were identified that bind to PD-L1 and crystal structures of these compounds bound to PD-L1 were obtained.     

Enhancement in leghemoglobin content of root nodules by exclusion of solar UV-A and UV-B radiation in soybean

The impact of exclusion of solar UV-B (280–320 nm) and UV-A+B (280–400 nm) radiation on the root nodules was studied in soybean(Glycine max var. MACS 330). Soybean plants were grown in the tropical region of Indore (Latitude-22.4°N), India under field conditions in metal cages covered with polyester exclusion filters that specifically cut off UV-B (<320 nm) and UV-A+B (<400 nm) radiation; control plants were grown under ambient solar radiation. Leghemoglobin content was analyzed in the root nodules on the 50^th day after emergence of seedlings. Exclusion of UV radiations significantly enhanced the leghemoglobin content in the nodules on fresh weight basis; 25% and 45% higher amount of leghemoglobin were present in the nodules after the exclusion of UV-B and UV-A+B radiation respectively. Analysis by native and SDS-PAGE showed high intense bands of leghemoglobin after the exclusion of UV-A+B as compared to control. Exclusion of UV radiation also enhanced the growth of roots as well as aerial parts of the plants. UV Exclusion increased nodulation by increase in the number and size of nodules. The results are discussed in the light of advantage of exclusion for enhancing protein/nitrogen content in the plants.     

NAR Breakthrough Article: Next-generation sequencing reveals the biological significance of the N2,3-ethenoguanine lesion in vivo

Etheno DNA adducts are a prevalent type of DNA damage caused by vinyl chloride (VC) exposure and oxidative stress. Etheno adducts are mutagenic and may contribute to the initiation of several pathologies; thus, elucidating the pathways by which they induce cellular transformation is critical. Although N²,3-ethenoguanine (N²,3-εG) is the most abundant etheno adduct, its biological consequences have not been well characterized in cells due to its labile glycosidic bond. Here, a stabilized 2′-fluoro-2′-deoxyribose analog of N²,3-εG was used to quantify directly its genotoxicity and mutagenicity. A multiplex method involving next-generation sequencing enabled a large-scale in vivo analysis, in which both N²,3-εG and its isomer 1,N²-ethenoguanine (1,N²-εG) were evaluated in various repair and replication backgrounds. We found that N²,3-εG potently induces G to A transitions, the same mutation previously observed in VC-associated tumors. By contrast, 1,N²-εG induces various substitutions and frameshifts. We also found that N²,3-εG is the only etheno lesion that cannot be repaired by AlkB, which partially explains its persistence. Both εG lesions are strong replication blocks and DinB, a translesion polymerase, facilitates the mutagenic bypass of both lesions. Collectively, our results indicate that N²,3-εG is a biologically important lesion and may have a functional role in VC-induced or inflammation-driven carcinogenesis.     

Cell kinetics of a rat thyroid transplantable tumour

Abstract. Changes in morphology and cell kinetics are described in a rat thyroid transplantable tumour (TTT) during the first few transplant generations. The growth of TTT in animals was possible only with an increased circulation level of the thyroid stimulating hormone (TSH). With serial transplantation subcutaneously in isologous animals, the morphology of TTT changed dramatically from that of a follicular tumour in the 3rd passage to become, by the 9th generation, a poorly differentiated tumour with a trabecular arrangement of cells. This change in tumour morphology was accompanied by an increase in the number of proliferating cells–mitotic index (MI), [³H]thymidine labelling index (LI), growth fraction (GF)–and cell loss factor (O) as well as a decrease in the cell cycle time (T_c) and potential population doubling time (T_PD). TTT belongs to the class of tumours with a low proliferative activity and might be used in a variety of cell kinetic, radiobiological and chemotherapy studies.     

The Characteristic (Crossover) Temperature in the Theory of Thermally Activated Tunneling Processes

We reconsider the concept of a characteristic (crossover) temperature and its applications to thermally activated tunneling processes. Alternative definitions of this concept are discussed. The analysis reveals the various aspects of the characteristic temperature and its derivatives in electron emission theory and reaction rate theory, including the proper dynamic and the stochastic approaches to the latter theory.     

Quantification of Abdominal Fat Depots in Rats and Mice during Obesity and Weight Loss Interventions

Background & Aims

Obesity is a leading healthcare issue contributing to metabolic diseases. There is a great interest in non-invasive approaches for quantitating abdominal fat in obese animals and humans. In this work, we propose an automated method to distinguish and quantify subcutaneous and visceral adipose tissues (SAT and VAT) in rodents during obesity and weight loss interventions. We have also investigated the influence of different magnetic resonance sequences and sources of variability in quantification of fat depots.

Materials and Methods

High-fat diet fed rodents were utilized for investigating the changes during obesity, exercise, and calorie restriction interventions (N = 7/cohort). Imaging was performed on a 7T Bruker ClinScan scanner using fast spin echo (FSE) and Dixon imaging methods to estimate the fat depots. Finally, we quantified the SAT and VAT volumes between the L1–L5 lumbar vertebrae using the proposed automatic hybrid geodesic region-based curve evolution algorithm.

Results

Significant changes in SAT and VAT volumes (p<0.01) were observed between the pre- and post-intervention measurements. The SAT and VAT were 44.22±9%, 21.06±1.35% for control, −17.33±3.07%, −15.09±1.11% for exercise, and 18.56±2.05%, −3.9±0.96% for calorie restriction cohorts, respectively. The fat quantification correlation between FSE (with and without water suppression) sequences and Dixon for SAT and VAT were 0.9709, 0.9803 and 0.9955, 0.9840 respectively. The algorithm significantly reduced the computation time from 100 sec/slice to 25 sec/slice. The pre-processing, data-derived contour placement and avoidance of strong background–image boundary improved the convergence accuracy of the proposed algorithm.

Conclusions

We developed a fully automatic segmentation algorithm to quantitate SAT and VAT from abdominal images of rodents, which can support large cohort studies. We additionally identified the influence of non-algorithmic variables including cradle disturbance, animal positioning, and MR sequence on the fat quantification. There were no large variations between FSE and Dixon-based estimation of SAT and VAT.