Effect of gibberellins and the growth retardant CCC on the nodulation of soya

Summary The effect of exogenous applications of gibberellins (GAs) or the growth retardant -chloroethyltrimethylammonium chloride (CCC) on root nodule formation and activity (C₂H₂-reduction) in soya was studied. Daily foliar application of GA₃ (2.89×10^–6 M) delayed the formation of nodule initials and reduced the numbers mass nodule^–1 and specific activity of nodules by 43%, 31% and 47% respectively, without affecting plant growth. Similar effects on nodulation were produced by foliar application of GA₄ (3.01×10^–5 M) or GA₇ (3.03×10^–5 M), or by the addition of GA₃ (2.89×10^–6 M) to the rooting medium. GA effectiveness in reducing nodule numbers was decreased by delaying its application until after the initial infection process had occurred, but the nodules formed were smaller and less active than those of the untreated control plants. The GA effect on nodulation and nodule activity was not associated with alterations in root exudate or due to a direct inhibitory effect of the hormone on the nitrogenase system. When the endogenous root content of GA-like substances was reduced (86% decrease) by foliar application of CCC (6.30×10^–5 M), nodule numbers were increased by 56%, but nodule size and total nodule activity were similar to those of control plants. The GA and CCC treatments had no effect on rhizobial growth in liquid culture nor on root colonisation by rhizobia.The results suggest that the endogenous content of root GA may have a regulatory role in both the infection process and in subsequent nodule morphogenesis, thus controlling both the number and effectiveness of the root nodules formed.     

Abscisic acid and gibberellin-like substances in roots and root nodules ofGlycine max

Summary The content of endogenous gibberellin (GA)-like substances of roots and root nodules of SOya, and GA production byRhizobium japonicum cultures, were investigated by a combined thin layer chromatographic (TLC)-dwarf pea epicotyl bioassay technique. GAs were more concentrated in root nodules than in the roots, totalling 1.34 and 0.16 nM GA₃ equivalents g⁻¹ dry wt. respectively. GA production byR. japonicum cultures was demonstrated (1.00 nM GA₃ equivalentsl ⁻¹) and comparison of the GA components of plant and bacterial culture medium extracts, suggested that rhizobial GA production may contribute to the nodule GA content. Cis-trans abscisic acid (ABA) was identified in root and nodule extracts by TLC-gas liquid chromatography (GLC), and amounted to 0.18 and 2.21 nM g⁻¹ dry wt. respectively, whereas 0.30 and 4.63 nM ABA equivalents g⁻¹ dry wt. were detected by a TLC-wheat embryo bioassay technique. ABA was not detected in extracts of bacterial cultures.     

Sites of sulfatation in the chondrocytes of the articular cartilage of the rabbit

35S sulfate uptake by the articular cartilage chondrocytes, from biopsies of rabbit, have been studied by high resolution autoradiography. The Golgi apparatus, rough endoplasmic reticulum, cytosol, cytoplasmic membrane and extracellular space were considered as cell compartments in the quantitative analysis of the autoradiograms. The results obtained show: 1) a high activity of radiosotope incorporation in the Golgi apparatus; 2) a fast rhythm of transfer of the substances labelled in the Golgi apparatus to the cell membrane; 3) significant labelling of the rough endoplasmic reticulum, throughout the experiment. It is concluded: 1) The grains observed in the rough endoplasmic reticulum show a significant radioisotope uptake on this level, and this evidence some sulfotransferase activity. 2) The high 35S sulfate uptake level which is observed in the Golgi apparatus demonstrates that the highest sulfotransferase enzyme activity is located in this cell area, thus showing that the "early" sulfation that began in the rough endoplasmic reticulum was completed by a "late" sulfation in the Golgi apparatus. It is here that complete chondromucoprotein building takes place before being excreted. 3) The high transfer level of the labelled substances from the Golgi apparatus shows that the sulfated product secretion for building the cartilage matrix takes place rapidly since a great label increase can be already observed at the beginning of the chase period in the outer surrounding area of the chondrocyte membrane.     

Electrophoretic transport of Tl+ in mitochondria

Summary The distribution of Tl⁺ between rat liver mitochondria and the medium was studied; millimolar or smaller concentrations of Tl⁺ were labeled with²⁰⁴Tl. The Tl⁺ distribution responded to transient diffusion potentials in a way that indicated electrophoretic movements of Tl⁺. The diffusion potentials were induced by efflux of K⁺ in response to addition of valinomycin to nonrespiring mitochondria suspended in a medium with low concentrations of K⁺ or by efflux of H⁺ induced by making the medium more alkaline in the presence of a protonophorous (proton-conducting) uncoupling agent. Changes in membrane potential induced by valinomycin were followed with the aid of safranine. Tl⁺ brought about collapse of the diffusion potential. It is concluded that Tl⁺ is able to penetrate the mitochondrial membrane electrophoretically.     

Oxidative inactivation of carbamoyl phosphate synthetase (ammonia). Mechanism and sites of oxidation, degradation of the oxidized enzyme, and inactivation by glycerol, EDTA, and thiol protecting agents.

Acetylglutamate and ATP accelerate the oxidative inactivation of carbamoyl phosphate synthetase I by mixtures of Fe3+, ascorbate, and O2, but the mechanism of the inactivation differs with each ligand. In the presence of acetylglutamate, MgATP prevents, Mg2+, Mn2+, and catalase have no effect, and EDTA increases the inactivation, and the two phosphorylation steps of the enzyme reaction are lost simultaneously. The inactivation appears to be mediated by dehydroascorbate and is associated with the reversible oxidation of the highly reactive cysteines 1327 and 1337 and with oxidation of non-thiolic groups in the second 40-kDa domain (the enzyme consists of 4 domains of 40, 40, 60, and 20 kDa, from the amino terminus). The data are consistent with oxidation of groups at or near the site for ATPA (ATPA yields Pi; ATPB yields carbamoyl phosphate), and with the location of this site at the interphase between the second 40-kDa and the COOH-terminal domains. The oxidative inactivation promoted by ATP is inhibited by Mg2+, Mn2+, catalase, and EDTA, is not mediated by dehydroascorbate, and is not associated with oxidation of cysteines 1327 and 1337. Groups in the 60-kDa domain are oxidized. The phosphorylation step involving ATPB is lost preferentially, and the inactivation and the binding of ATPB exhibit the same dependency on the concentration of ATP. The results indicate that the oxidation is catalyzed by FeATP bound at the site for ATPB and support the binding of ATPB in the 60-kDa domain. We also demonstrate that mercaptoethanol, reducing impurities in glycerol, and dithioerythritol, in the presence of EDTA, replace ascorbate in the oxidative system. In addition, we study the influence of the oxidation on the degradation of the enzyme by rat liver lysosomes, mitochondria, and cytosol.     

Waterborne transmission ofCampylobacter enteritis

Campylobacter jejuni is an important cause of human diarrheal disease throughout the world and likeSalmonella enteritidis, has a large animal reservoir which includes most of man's domestic animals. Until recently, it has been difficult to trace the chain of transmission from animals to man because of inadequate environmental sampling techniques and means to distinguish strains. Recent improvements in these techniques have made environmental studies more feasible in 2 water-related out-breaks.In 1 study,C. jejuni was found to be an important cause of sporadic, summertime diarrheal disease among hikers in national wilderness areas of Wyoming. In this setting, illness was significantly associated with drinking untreated surface water. SubsequentlyC. jejuni was isolated from surface water, including mountian streams, and from animals in the area. Some of the environmental isolates were serotypically identical to strains isolated from humans.A second study occurred as a result of an outbreak of Campylobacter enteritis in a community in northern Illinois which was epidemiologically associated with the community water system.Campylobacter jejuni was isolated from several surface water sources and from the implicated water system. These studies demonstrate that environmental isolation ofC. jejuni is now possible and may add to our understanding of disease transmission.     

Magnesium supplementation and iron status among female students: The intervention study

BackgroundLiterature data indicate the benefit of magnesium (Mg) supplementation. The aim of this study was to examine the effect of short-term Mg supplementation on iron status in healthy female participants.MethodsOne hundred healthy female students of the University of Belgrade - Faculty of Pharmacy participated the study during eleven intervention days. Students ingested Mg preparations with the same dose of the active substance. The analysis included the measurement of serum iron, unsaturated iron binding capacity (UIBC), total iron binding capacity (TIBC), total Mg (tMg), ionized Mg (iMg), complete blood count, met-, carboxyand oxy-haemoglobin (metHgb, COHgb, O2Hgb). Transferrin concentrations and percentage of transferrin saturation (SAT) were calculated manually. The association among the analyzed biochemical parameters was examined using polynomial regression. A principal component analysis (PCA) was used for the evaluation of interdependence between the analyzed parameters.ResultsA statistically significant trend for change in O2Hgb (%) by tertiles of iMg concentrations was found (P = 0.029). Serum tMg reached significant positive correlation with the SAT at concentration levels greater than 0.9 mmol/L, after 11 days of intervention (R2=0.116). Ionized Mg in a concentration higher than 0.6 mmol/L is positively correlated with SAT and serum Fe (R2=0.214; 0.199, respectively). PCA revealed variability of 64.7% for two axes after 11 days.ConclusionsMg supplementation leads to an improvement in the certain iron status parameters even in individuals with optimal levels of these indices. However, caution should be exercised when supplementing Mg, and laboratory monitoring of the interaction is required.     

Six years of wild bee monitoring shows changes in biodiversity within and across years and declines in abundance

Wild bees form diverse communities that pollinate plants in both native and agricultural ecosystems making them both ecologically and economically important. The growing evidence of bee declines has sparked increased interest in monitoring bee community and population dynamics using standardized methods. Here, we studied the dynamics of bee biodiversity within and across years by monitoring wild bees adjacent to four apple orchard locations in Southern Pennsylvania, USA. We collected bees using passive Blue Vane traps continuously from April to October for 6 years (2014–2019) amassing over 26,000 bees representing 144 species. We quantified total abundance, richness, diversity, composition, and phylogenetic structure. There were large seasonal changes in all measures of biodiversity with month explaining an average of 72% of the variation in our models. Changes over time were less dramatic with years explaining an average of 44% of the variation in biodiversity metrics. We found declines in all measures of biodiversity especially in the last 3 years, though additional years of sampling are needed to say if changes over time are part of a larger trend. Analyses of population dynamics over time for the 40 most abundant species indicate that about one third of species showed at least some evidence for declines in abundance. Bee family explained variation in species‐level seasonal patterns but we found no consistent family‐level patterns in declines, though bumble bees and sweat bees were groups that declined the most. Overall, our results show that season‐wide standardized sampling across multiple years can reveal nuanced patterns in bee biodiversity, phenological patterns of bees, and population trends over time of many co‐occurring species. These datasets could be used to quantify the relative effects that different aspects of environmental change have on bee communities and to help identify species of conservation concern.     

Cyclooxygenase-2 deficiency leads to intestinal barrier dysfunction and increased mortality during polymicrobial sepsis

Sepsis remains the leading cause of death in critically ill patients, despite modern advances in critical care. Intestinal barrier dysfunction may lead to secondary bacterial translocation and the development of the multiple organ dysfunction syndrome during sepsis. Cyclooxygenase (COX)-2 is highly upregulated in the intestine during sepsis, and we hypothesized that it may be critical in the maintenance of intestinal epithelial barrier function during peritonitis-induced polymicrobial sepsis. COX-2(-/-) and COX-2(+/+) BALB/c mice underwent cecal ligation and puncture (CLP) or sham surgery. Mice chimeric for COX-2 were derived by bone marrow transplantation and underwent CLP. C2BBe1 cells, an intestinal epithelial cell line, were treated with the COX-2 inhibitor NS-398, PGD(2), or vehicle and stimulated with cytokines. COX-2(-/-) mice developed exaggerated bacteremia and increased mortality compared with COX-2(+/+) mice following CLP. Mice chimeric for COX-2 exhibited the recipient phenotype, suggesting that epithelial COX-2 expression in the ileum attenuates bacteremia following CLP. Absence of COX-2 significantly increased epithelial permeability of the ileum and reduced expression of the tight junction proteins zonula occludens-1, occludin, and claudin-1 in the ileum following CLP. Furthermore, PGD(2) attenuated cytokine-induced hyperpermeability and zonula occludens-1 downregulation in NS-398-treated C2BBe1 cells. Our findings reveal that absence of COX-2 is associated with enhanced intestinal epithelial permeability and leads to exaggerated bacterial translocation and increased mortality during peritonitis-induced sepsis. Taken together, our results suggest that epithelial expression of COX-2 in the ileum is a critical modulator of tight junction protein expression and intestinal barrier function during sepsis.     

Purification and characterization of 4-hydroxybenzoate 3-hydroxylase from aKlebsiella pneumoniae mutant strain

Unlike the parent wild-type strain, theKlebsiella pneumoniae mutant strain MAO4 has a 4-HBA⁺ phenotype. The capacity of this mutant to take up and metabolize 4-hydroxybenzoate (4-HBA) relies on the expression of a permease and an NADPH-linked monooxygenase (4-HBA-3-hydroxylase). Both enzymes are normally expressed at basal levels, and only the presence of 4-HBA in the media enhances their activities. Strikingly, when theAcinetobacter calcoaceticus pobA gene encoding 4-hydroxybenzoate-3-hydroxylase was expressed in hydroxybenzoateK. pneumoniae wild-type, the bacteria were unable to grow on 4-HBA, suggesting that the main difference between the wild-type and the mutant strain is the capability of the latter to take up 4-HBA. 4-HBA-3-hydroxylase was purified to homogeneity by affinity, gel-filtration, and anion-exchange chromatography. The native enzyme, which appeared to be a dimer of identical subunits, had an apparent molecular mass of 80 kDa and a pI of 4.6. Steady-state kinetics were analyzed; the initial velocity patterns were consistent with a concerted substitution mechanism. The purified enzyme had 362 amino acid residues, and a tyrosine seemed to be involved in substrate activation.