Root desiccation and drought stress responses of bareroot Quercus rubra seedlings treated with a hydrophilic polymer root dip

Root hydrogel, a hydrophilic polymer, has been used to improve transplanting success of bareroot conifer seedlings through effects on water holding capacity. We examined mechanisms by which Terra-sorb® Fine Hydrogel reduces damage that occurs when roots of 1-year old, dormant northern red oak (Quercus rubra L.) were subjected to short-term (1, 3, and 5 h) pre-transplanting desiccation and long-term (45 days) drought stress following transplanting in a controlled environment chamber or greenhouse conditions. Hydrogel-treated seedlings had 80% greater root moisture content than non-root dipped control seedlings following the pre-transplanting desiccation period. Hydrogel reduced root membrane leakiness by 31% 5 h after the desiccation exposure. Hydrogel-treated seedlings did not show greater differences in shoot length, plant dry mass, root volume, net photosynthesis, and stomatal conductance compared with control seedlings following the 45-day drought stress exposure. A reduction in mean number of days to bud break in hydrogel-treated seedlings, combined with delayed tissue moisture loss (linked to higher stem water potential), suggests that hydrogel may have provided stress protection to aid survival under short-term desiccation, which may be beneficial toward alleviating initial transplanting stress.     

The insulin polymorphism -23Hph increases the risk for type 1 diabetes mellitus in the Romanian population

The insulin -23Hph and IGF2 Apa polymorphisms were genotyped in Romanian patients with T1DM (n = 204), T2DM (n = 215) or obesity (n = 200) and normoponderal healthy subjects (n = 750). The genotypes of both polymorphisms were distributed in concordance with Hardy-Weinberg equilibrium in all groups. The -23Hph AA genotype increased the risk for T1DM (OR: 3.22, 95%CI: 2.09-4.98, p < 0,0001), especially in patients without macroalbuminuria (OR: 4.32, 95%CI: 2.54-7.45, p < 0,0001). No other significant association between the alleles or genotypes of insulin -23Hph and IGF2 Apa and diabetes or obesity was identified.     

Muscle weakness in Ryr1I4895T/WT knock-in mice as a result of reduced ryanodine receptor Ca2+ ion permeation and release from the sarcoplasmic reticulum

The type 1 isoform of the ryanodine receptor (RYR1) is the Ca(2+) release channel of the sarcoplasmic reticulum (SR) that is activated during skeletal muscle excitation-contraction (EC) coupling. Mutations in the RYR1 gene cause several rare inherited skeletal muscle disorders, including malignant hyperthermia and central core disease (CCD). The human RYR1(I4898T) mutation is one of the most common CCD mutations. To elucidate the mechanism by which RYR1 function is altered by this mutation, we characterized in vivo muscle strength, EC coupling, SR Ca(2+) content, and RYR1 Ca(2+) release channel function using adult heterozygous Ryr1(I4895T/+) knock-in mice (IT/+). Compared with age-matched wild-type (WT) mice, IT/+ mice exhibited significantly reduced upper body and grip strength. In spite of normal total SR Ca(2+) content, both electrically evoked and 4-chloro-m-cresol-induced Ca(2+) release were significantly reduced and slowed in single intact flexor digitorum brevis fibers isolated from 4-6-mo-old IT/+ mice. The sensitivity of the SR Ca(2+) release mechanism to activation was not enhanced in fibers of IT/+ mice. Single-channel measurements of purified recombinant channels incorporated in planar lipid bilayers revealed that Ca(2+) permeation was abolished for homotetrameric IT channels and significantly reduced for heterotetrameric WT:IT channels. Collectively, these findings indicate that in vivo muscle weakness observed in IT/+ knock-in mice arises from a reduction in the magnitude and rate of RYR1 Ca(2+) release during EC coupling that results from the mutation producing a dominant-negative suppression of RYR1 channel Ca(2+) ion permeation.     

Effect of age of cell suspension cultures on susceptibility to a fungal elicitor

Fungal elicitor induced phytoalexin formation and the corresponding fluorescence transitions of the molecular probes pyranine and oxonol VI, in soybean (Glycine max Merr var Kent) and cotton (Gossypium arboreum L. Nanking) cell suspensions were both significantly affected by the age of the cells. During the lag phase and the beginning of the exponential growth phase both cultures exhibited stress responses (i.e. phytoalexin formation and molecular probe fluorescence transitions) in the absence of added elicitors. This behavior was termed autoelicitation because elicitation occurred without added external stimuli. In contrast, cells in the late exponential-early stationary phase were relatively unresponsive to elicitor. During intermediate growth periods the cell suspensions behaved optimally, producing no phytoalexins until stimulated with an elicitor. It would appear, therefore, that the culture period can be divided into 3 phases, with respect to susceptibility to fungal elicitors: a distinct autoelicitation period (immediately after transfer of the cells into fresh medium), followed by a period in which negligible amounts of phytoalexins are synthesized without elicitor, and culminating in a late period in which the cells respond poorly to elicitor. The onset and duration of these periods are somewhat different for soybean and cotton cells.     

Determination of the density of cells from sedimentation studies at 1G

To obtain a possible correlation between cell density and cell size, the size of individual cells was measured under the microscope and their sedimentation velocity was measured; the density is obtained with Stoke's Law. Specifically, HeLa cells were sedimented in Joklik's medium at 30°C in a vertical glass tube with 2 mm×2 mm horizontal opening and cells observed with a horizontally aligned microscope. The overall mean density difference of HeLa cells at 30°C was 0.0316+–0.0044 g/cm³, resulting in a density of 1.0357 g/cm³ (with a density of 1.0040 g/cm³ for Joklik's medium at 30°C). Six size fractions had densities which were essentially the same within the errors of the mean densities of the fractions (from 0.0081 to 0.0202 g/cm³). The considerably varying deviations of individual densities from the mean suggested superimposed phenomena (see also Table I for microspheres of precise size). Careful observation in balancing countercurrent flow revealed microconvection over 5 to 15 m regions, most likely based on small thermal differences in the horizontal plane.     

The effect of iodination on the haemolytic property and the fatty acids of Newcastle disease virus

Treatment of Newcastle disease virus with iodine inhibits haemolysis and infectivity, but has no effect on haemagglutination. This is shown to be concurrent with the incorporation of iodine in the hydrocarbon chain of fatty acyl residues of the viral membrane lipid. It is concluded that iodine incorporation, by reducing membrane fluidity, is responsible for these biological phenomena.     

Non-invasive monitoring of the light-induced cyclic photosynthetic electron flow during cold hardening in wheat leaves

The effect of irradiance during low temperature hardening was studied in a winter wheat variety. Ten-day-old winter wheat plants were cold-hardened at 5 degrees C for 11 days under light (250 micromol m(-2) S(-1)) or dark (20 micromol m(-2) s(-1)) conditions. The effectiveness of hardening was significantly lower in the dark, in spite of a slight decrease in the Fv/Fm chlorophyll fluorescence induction parameter, indicating the occurrence of photoinhibition during the hardening period in the light. Hardening in the light caused a downshift in the far-red induced AG (afterglow) thermoluminescence band. The faster dark re-reduction of P700+, monitored by 820-nm absorbance, could also be observed in these plants. These results suggest that the induction of cyclic photosynthetic electron flow may also contribute to the advantage of frost hardening under light conditions in wheat plants.