Binding of histone H1 to DNA is described by an allosteric model

Equilibrium binding data were analyzed to characterize the interaction of the linker histone H1 degrees with unmodified T4 phage DNA. Data were cast into the Scatchard-type plot described by McGhee and von Hippel and fit to their eponymous model for nonspecific binding of ligand to DNA. The data were not fit by the simple McGhee-von Hippel model, nor fit satisfactorily by the inclusion of a cooperativity parameter. Instead, the interaction appeared to be well described by Crothers' allosteric model, in which the higher affinity of the protein for one conformational form of the DNA drives an allosteric transition of the DNA to the conformational form with higher affinity (form 2). At 214 mM Na(+), the observed affinity K for an isolated site on unmodified T4 bacteriophage DNA in the form 2 conformation is 4.5 x 10(7) M(-1). The binding constant for an isolated site on DNA in the conformation with lower affinity, form 1, appears to be about 10-fold lower. Binding affinity is dependent on ion concentration: the magnitude of K is about 10-fold higher at 14 mM (5.9 x 10(8) M(-1) for form 2 DNA) than at 214 mM Na(+) concentration.     

The Effect of Lactobacillus casei 32G on the Mouse Cecum Microbiota and Innate Immune Response Is Dose and Time Dependent

Lactobacilli have been associated with a variety of immunomodulatory effects and some of these effects have been related to changes in gastrointestinal microbiota. However, the relationship between probiotic dose, time since probiotic consumption, changes in the microbiota, and immune system requires further investigation. The objective of this study was to determine if the effect of Lactobacillus casei 32G on the murine gastrointestinal microbiota and immune function are dose and time dependent. Mice were fed L. casei 32G at doses of 10⁶, 10⁷, or 10⁸ CFU/day/mouse for seven days and were sacrificed 0.5h, 3.5h, 12h, or 24h after the last administration. The ileum tissue and the cecal content were collected for immune profiling by qPCR and microbiota analysis, respectively. The time required for L. casei 32G to reach the cecum was monitored by qPCR and the 32G bolus reaches the cecum 3.5h after the last administration. L. casei 32G altered the cecal microbiota with the predominance of Lachnospiraceae IS, and Oscillospira decreasing significantly (p < 0.05) in the mice receiving 10⁸ CFU/mouse 32G relative to the control mice, while a significant (p < 0.05) increase was observed in the prevalence of lactobacilli. The lactobacilli that increased were determined to be a commensal lactobacilli. Interestingly, no significant difference in the overall microbiota composition, regardless of 32G doses, was observed at the 12h time point. A likely explanation for this observation is the level of feed derived-nutrients resulting from the 12h light/dark cycle. 32G results in consistent increases in Clec2h expression and reductions in TLR-2, alpha-defensins, and lysozyme. Changes in expression of these components of the innate immune system are one possible explanation for the observed changes in the cecal microbiota. Additionally, 32G administration was observed to alter the expression of cytokines (IL-10rb and TNF-α) in a manner consistent with an anti-inflammatory response.     

An insight into functional genomics of transgenic lines of tomato cv Rio Grande harbouring yeast halotolerance genes

Tomato cv Rio Grande plants were transformed with yeast halotolerance genes (HAL I or HAL II) using pPM7HAL I or pJRM16HAL II, with p35GUSINT as control. Transformation efficiency varied in the three constructs, with highest transformation found with p35GUSINT. Final selection of the transgenic plants was made on the basis of PCR. Transgene integration and copy number were assessed by Southern hybridisation. The primary transformants were allowed to self-pollinate and the expected Mendelian ratios were studied in second-generation progeny. Five independent homozygous lines each of HAL I and HAL II, as well as the control, were characterised to study inter-transformant expression variability. The transformants showed considerable variability in expression of the respective genes, as shown by salt tolerance assays, chlorophyll content and peroxidase activity. The transgene expression in transgenic lines was analysed by semi-quantitative RT-PCR. In response to different salt concentrations, transgenic plants over-expressing HAL I and HAL II had significantly (α=0.05) better performance than the control This study presents the comparative responses of the three constructs under the same transformation conditions and suggests possible mechanisms governed by yeast HAL I and HAL II genes, which seem to work in a coordinated manner by relatively decreasing osmotic and oxidative shock at different rates. Our results suggest that the yeast HAL I increases K(+) /Na(+) selectivity and has a more functional role than HAL II in improving salt tolerance of the tomato cv Rio Grande grown in Pakistan.     

Comparative physiological responses of the yeast halotolerance genes expressed in transgenic lines of tomato cv Rio Grande under saline conditions

We previously analyzed the transgenic lines of tomato cv Rio Grande over-expressing the yeast HAL I and HAL II genes for their response to salt stress under in vitro conditions. In this study, six homozygous tomato lines harbouring the yeast HAL I or HAL II genes with highest expression level were selected for exploring their physiological responses against different salt stresses in the field. These transgenic plants showed significant growth and improved water content in comparison with control under 100 and 150 mM salt stress conditions. The HAL I and HAL II lines showed better Ca²⁺ content than their control counterparts. Furthermore, the transgenic lines exhibited lower values of relative electrical conductivity and improved resistance against the fungal pathogens Fusarium oxysporum and Alternaria solani when tested by detached leaf and agar tube dilution assays. Physiological analyses carried out in this study suggest an involvement of multiple mechanisms in transgenic tomato plants harbouring yeast genes to confer biotic and abiotic tolerance under stress conditions.     

Regulation of photosynthesis during heterocyst differentiation in Anabaena sp. strain PCC 7120 investigated in vivo at single-cell level by chlorophyll fluorescence kinetic microscopy

Changes of photosynthetic activity in vivo of individual heterocysts and vegetative cells in the diazotrophic cyanobacterium Anabaena sp. strain PCC 7120 during the course of diazotrophic acclimation were determined using fluorescence kinetic microscopy (FKM). Distinct phases of stress and acclimation following nitrogen step-down were observed. The first was a period of perception, in which the cells used their internally stored nitrogen without detectable loss of PS II activity or pigments. In the second, the stress phase of nitrogen limitation, the cell differentiation occurred and an abrupt decline of fluorescence yield was observed. This decline in fluorescence was not paralleled by a corresponding decline in photosynthetic pigment content and PS II activity. Both maximal quantum yield and sustained electron flow were not altered in vegetative cells, only in the forming heterocysts. The third, acclimation phase started first in the differentiating heterocysts with a recovery of PS II photochemical yields $F_{\text{v}} /F_{\text{m}} ,\;F^{\prime}_{\text{v}} /F^{\prime}_{\text{m}}.$ F v / F m , F v ′ / F m ′ . Afterwards, the onset of nitrogenase activity was observed, followed by the restoration of antenna pigments in the vegetative cells, but not in the heterocysts. Surprisingly, mature heterocysts were found to have an intact PS II as judged by photochemical yields, but a strongly reduced PS II-associated antenna as judged by decreased F ₀. The possible importance of the functional PS II in heterocysts is discussed. Also, the FKM approach allowed to follow in vivo and evaluate the heterogeneity in photosynthetic performance among individual vegetative cells as well as heterocysts in the course of diazotrophic acclimation. Some cells along the filament (so-called “superbright cells”) were observed to display transiently increased fluorescence yield, which apparently proceeded by apoptosis.     

An acute bout of high-intensity interval training increases the nuclear abundance of PGC-1α and activates mitochondrial biogenesis in human skeletal muscle

Low-volume, high-intensity interval training (HIT) increases skeletal muscle mitochondrial capacity, yet little is known regarding potential mechanisms promoting this adaptive response. Our purpose was to examine molecular processes involved in mitochondrial biogenesis in human skeletal muscle in response to an acute bout of HIT. Eight healthy men performed 4 × 30-s bursts of all-out maximal intensity cycling interspersed with 4 min of rest. Muscle biopsy samples (vastus lateralis) were obtained immediately before and after exercise, and after 3 and 24 h of recovery. At rest, the majority of peroxisome proliferator-activated receptor γ coactivator (PGC)-1α, a master regulator of mitochondrial biogenesis, was detected in cytosolic fractions. Exercise activated p38 MAPK and AMPK in the cytosol. Nuclear PGC-1α protein increased 3 h into recovery from exercise, a time point that coincided with increased mRNA expression of mitochondrial genes. This was followed by an increase in mitochondrial protein content and enzyme activity after 24 h of recovery. These findings support the hypothesis that an acute bout of low-volume HIT activates mitochondrial biogenesis through a mechanism involving increased nuclear abundance of PGC-1α.     

Development of Organically Complexed-Bioaugmented Boron-Coated DAP and Its Effect on Yield and Quality of Canola (Brassica napus L.)

Journal of Plant Growth Regulation - Many agricultural soils fail to supply sufficient boron (B) and phosphorus (P) to growing plants due to their adsorption, precipitation and fixation phenomena....     

Allelopathic effect of aqueous extracts of three weed species on the growth and leaf chlorophyll content of bread wheat

The purpose of this study was to evaluate the allelopathic effect of weeds (Avena fatua, Melilotus officinalis and Polypogon hissaricus) on germination, growth, dry biomass and chlorophyll concentration of three cultivars of wheat (Ata Habib, Pirsabaq and Serin). In germination test, different concentrations of aqueous extracts (5, 10 and 15?g/l) of the three weeds significantly reduced percent germination; however, 15?g/l extract of M. officinalis resulted in complete failure of germination of cultivar Pirsabaq. In pot culture, root and shoot length, chlorophyll concentration and seedling dry biomass of the three wheat varieties showed differential responses to different weeds. Aqueous extract at 15?g/l of A. fatua increased root and shoot length and dry biomass of cultivar Pirsabaq; however, these parameters were significantly retarded in other two wheat cultivars by extract of weeds. Moisture content of the cultivars did not show any response to allelopathic stress of the weeds. In contrast, chlorophyll concentration in Pirsabaq and Serin was significantly increased by aqueous extract of all the weeds but reduced it in cultivar Ata Habib by 50%. In general, Ata Habib was found to be the most sensitive cultivar to the imposed allelopathic stress. The phytotoxic potential of three weeds was found in the order of A. fatua?>?M. officinalis?>?P. hissaricus.