Effect of boron on soluble protein and sugar contents of tomato roots

Summary In relation to a biochemical diagnosis of B-affected plants, the influence of boron on soluble protein and sugar contents in roots of tomato plants was investigated. Differences in protein and sugar contents occur throughout the culture period of tomato plant. Boron deficiency results in an accumulation of proteins and both total and reducing sugars.     

Mechanism of colchicine binding to tubulin. Tolerance of substituents in ring C' of biphenyl analogues

The limits of structural variation of the substituent in position 4' of ring C' of biphenyl colchicine analogues (ring C in colchicine) were probed by the synthesis of a number of analogues and the examination of their binding to tubulin and its consequences. Binding was found to require the location in three-dimensional space of the oxygen in the 4'-substituent at a locus not far distant from those of the colchicine ring C oxygens. All those analogues that bind to the colchicine site of tubulin induced the GTPase activity and inhibited microtubule assembly, those containing a carbonyl group substoichiometrically and the others stoichiometrically. A similar relation was found for the induction of the abnormal polymerization of the colchicine analogue-tubulin complex, with methoxy-containing compounds requiring a higher temperature to induce the polymerization. A concerted analysis of the binding thermodynamics of colchicine and its various analogues has shown full consistency with the previously proposed two-step binding pathway that involves two nonidentical binding moieties in the ligand [Andreu, J. M., & Timasheff, S. N. (1982) Biochemistry 21, 534-543]. Comparison of the binding parameters of colchicine, its des(ring B) analogue (MTC), and ring A and C compounds individually with the thermodynamic parameters deduced for the first steps of the bindings of colchicine and MTC [Engelborghs, Y., & Fitzgerald, T. J. (1987) J. Biol. Chem. 262, 5204-5209] have led to the conclusion that binding can occur by two pathways leading to the identical product. In the first pathway, ring A binds first; this is followed by a rate-determining thermodynamically indifferent reaction (protein conformation change), and finally a rapid binding of ring C. In the second pathway, the events are the same except that the order of binding of the rings is reversed. Colchicine, due to the steric hindrance of ring B, can follow only the second pathway. For MTC, both kinetic pathways are open and binding may be initiated by random first contact of either ring A or ring C.     

Morphological features of the gorgonian Paramuricea macrospina on the continental shelf and shelf edge (Menorca Channel,Western Mediterranean Sea)

Morphological variability in gorgonians is frequent and commonly associated with habitat variability, often resulting in segregated morphotypes. Paramuricea macrospina is an endemic Mediterranean gorgonian species found on rocky bottoms between 40 and 160?m depth and has recently been reported as one of the most abundant species in continental shelf and shelf edge environments. Three different chromatic forms of P. macrospina were observed in the Menorca Channel: a yellow form and a light purple form occurring on maërl beds of the continental shelf, and a dark purple form occurring on rocky substrates of the shelf edge. The objective of the present work is to verify if these P. macrospina forms may represent distinct taxonomic units by analysing differences in colony morphology and sclerite size and shape of the three chromatic forms. No significant differences were found in colony shape, suggesting that environmental variability between the continental shelf and the shelf edge is not influential enough to significantly alter colony morphology. Significant differences in sclerite size and shape were found amongst all forms, suggesting that sclerites may be influenced by environmental conditions. However, the co-occurrence of the yellow and light purple forms side by side on the continental shelf may indicate a certain degree of genetic differentiation.     

Structural intermediates in the assembly of taxoid-induced microtubules and GDP-tubulin double rings: time-resolved X-ray scattering.

We have studied the self-association reactions of purified GDP-liganded tubulin into double rings and taxoid-induced microtubules, employing synchrotron time-resolved x-ray solution scattering. The experimental scattering profiles have been interpreted by reference to the known scattering profiles to 3 nm resolution and to the low-resolution structures of the tubulin dimer, tubulin double rings, and microtubules, and by comparison with oligomer models and model mixtures. The time courses of the scattering bands corresponding to the different structural features were monitored during the assembly reactions under varying biochemical conditions. GDP-tubulin essentially stays as a dimer at low Mg(2+) ion activity, in either the absence or presence of taxoid. Upon addition of the divalent cations, it associates into either double-ring aggregates or taxoid-induced microtubules by different pathways. Both processes have the formation of small linear (short protofilament-like) tubulin oligomers in common. Tubulin double-ring aggregate formation, which is shown by x-ray scattering to be favored in the GDP- versus the GTP-liganded protein, can actually block microtubule assembly. The tubulin self-association leading to double rings, as determined by sedimentation velocity, is endothermic. The formation of the double-ring aggregates from oligomers, which involves additional intermolecular contacts, is exothermic, as shown by x-ray and light scattering. Microtubule assembly can be initiated from GDP-tubulin dimers or oligomers. Under fast polymerization conditions, after a short lag time, open taxoid-induced microtubular sheets have been clearly detected (monitored by the central scattering and the maximum corresponding to the J(n) Bessel function), which slowly close into microtubules (monitored by the appearance of their characteristic J(0), J(3), and J (n) - (3) Bessel function maxima). This provides direct evidence for the bidimensional assembly of taxoid-induced microtubule polymers in solution and argues against helical growth. The rate of microtubule formation was increased by the same factors known to enhance taxoid-induced microtubule stability. The results suggest that taxoids induce the accretion of the existing Mg(2+)-induced GDP-tubulin oligomers, thus forming small bidimensional polymers that are necessary to nucleate the microtubular sheets, possibly by binding to or modifying the lateral interaction sites between tubulin dimers.     

Hatching success, delay of emergence and hatchling biometry of the spur-thighed tortoise, Testudo graeca, in south-western Spain

Hatching success, egg incubation, emergence and hatchling characteristics were assessed for 44 naturally incubating nests of Testudo graeca in south-western Spain. Nest predation rate was 4.5% and overall hatching success was 82.4%. Incubation periods ranged from 78 to 114 days, and hatchlings delayed emergence from the nest from one to 23 days. Emergences occurred from mid August to late September, and were not correlated with nesting dates, but earlier laid nests had longer incubation times, which was probably owing to lower temperatures experienced by clutches laid at the beginning of the nesting season. Variance of hatchling body size and mass was high and was mainly influenced by the gravid female. Mean straight carapace length was 34.14mm, and mean body mass 10.8g. Hatchlings from clutches laid last in the nesting season had significantly better physical condition. Hatchling mass was positively correlated with egg mass, and both variables were positively correlated with emergence date. Both better physical condition and relatively late emergence may confer advantages to hatchlings in the face of unfavourable environmental conditions in autumn.     

Association between Obstructive Sleep Apnea and Community-Acquired Pneumonia

BackgroundWe hypothesized that obstructive sleep apnea (OSA) can predispose individuals to lower airway infections and community-acquired pneumonia (CAP) due to upper airway microaspiration. This study evaluated the association between OSA and CAP.MethodsWe performed a case-control study that included 82 patients with CAP and 41 patients with other infections (control group). The controls were matched according to age, sex and body mass index (BMI). A respiratory polygraph (RP) was performed upon admission for patients in both groups. The severity of pneumonia was assessed according to the Pneumonia Severity Index (PSI). The associations between CAP and the Epworth Sleepiness Scale (ESS), OSA, OSA severity and other sleep-related variables were evaluated using logistic regression models. The associations between OSA, OSA severity with CAP severity were evaluated with linear regression models and non-parametric tests.FindingsNo significant differences were found between CAP and control patients regarding anthropometric variables, toxic habits and risk factors for CAP. Patients with OSA, defined as individuals with an Apnea-Hypopnea Index (AHI) ≥10, showed an increased risk of CAP (OR = 2·86, 95%CI 1·29–6·44, p = 0·01). Patients with severe OSA (AHI≥30) also had a higher risk of CAP (OR = 3·18, 95%CI 1·11–11·56, p = 0·047). In addition, OSA severity, defined according to the AHI quartile, was also significantly associated with CAP (p = 0·007). Furthermore, OSA was significantly associated with CAP severity (p = 0·0002), and OSA severity was also associated with CAP severity (p = 0·0006).ConclusionsOSA and OSA severity are associated with CAP when compared to patients admitted to the hospital for non-respiratory infections. In addition, OSA and OSA severity are associated with CAP severity. These results support the potential role of OSA in the pathogenesis of CAP and could have clinical implications. This link between OSA and infection risk should be explored to investigate the relationships among gastroesophageal reflux, silent aspiration, laryngeal sensory dysfunction and CAP.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01071421","term_id":"NCT01071421"}}NCT01071421     

Micrococcus lysodeikticus ATPase: Purification by preparative gel electrophoresis and subunit structure studied by urea and sodium dodecylsulfate gel electrophoresis

Micrococcus lysodeikticus ATPase was purified by preparative gel electrophoresis after its “shock wash” release from the membrane. The method afforded the highest yield of pure protein in the minimum time as compared with former purification procedures. The pure protein had a specific activity of 7 μmol P_i·min^?1·mg^?1 with incubation times not longer than 3 min, 345 000 mol. wt and was not stimulated by trypsin. By gel electrophoresis at alkaline pH (8.5) in 8 M urea or in sodium dodecylsulfate, the ATPase revealed a complex pattern with two major subunits (α and β) and two minor ones (γ and δ). The non-identity between the major subunits was demonstrated.     

Substructure of F1-ATPase (BF1 factor) from Micrococcus lysodeikticus

Summary Dimethyl suberimidate and dithiobis (succinimidyl propionate) have been used to explore the nearest neighbor relationship of the subunits (, , and by decreasing molecular weight) of F₁-ATPase or BF₁ factor of Micrococcus lysodeikticus. Cross-linking with the two diimido esters inhibited the ATPase activity but this inhibition never exceeded 50% of the initial value. The cross-linking pattern of this BF₁ factor, as revealed by sodium dodecyl sulfate gel electrophoresis, shows a relative low proportion of high molecular weight aggregates which move slowly than the heaviest subunit (). They are resolved as three components of molecular weights 200,000, 130,000 and 100,000 in 5% acrylamide gels, plus an additional component (mol. wt 80,000) identified in 10% acrylamide gels. The other aggregate bands represent cross-linking products of the smaller subunits ( and ) that may travel to the conventional position of the heavier subunits.The subunit composition of the aggregate bands has been determined through the reversion of dithiobis (succinimidyl propionate) cross-linking of the BF₁ factor by dithiothreitol and analysis in second dimension by gel electrophoresis. The results indicate that subunit can cross-link with itself and with each of the other subunits except . The subunit is also able to cross-link with itself and with the other subunits although to a minor extent than , and that ₂ aggregates are present. These results represent a specific pattern of cross-linking for this BF₁ factor as compared to other F₁ coupling factors. It suggests a certain asymmetry in the spatial organization of the major subunits of M. lysodeikticus F₁-ATPase where the subunit must play a central role. A subunit stoichiometry _{3 3 2 2} is proposed for whole F₁-ATPase which leads to a molecular weight 440,000 consistent with the 430,000 value estimated by sedimentation equilibrium at low speed. A tentative structural model of M. lysodeikticus BF₁ factor is derived from these data. The significance of the results in relation to the possible generalization of the molecular architecture of F₁ factors is discussed.