The effect of disinfecting and bruising seed potatoes on the incidence of dry rot (Fusarium caeruleum (Lib.) Sacc.)

The effect of bruising and of disinfecting ('dipping') seed potatoes with a proprietary organo-mercury preparation on the incidence of dry rot in them was tested in field trials during three seasons. The tubers used were of the susceptible variety Ninetyfold, taken from crops grown in contaminated soil, harvested immature in July to early August each year under farm conditions, and stored in boxes.
Seed tubers not deliberately bruised, whether dipped or not at lifting time, remained practically sound until planting time in the fallowing season, if left undisturbed in their boxes.
Tubers deliberately bruised, either at digging time or 1-2 weeks later, but not dipped, developed severe dry rot with few exceptions. The disease had run its course by mid-October. When undipped, sound tubers were bruised in October, they contracted severe dry rot, but dipping such tubers immediately before bruising reduced the loss satisfactorily in five out of six trials.
Tubers bruised at digging time and immediately dipped suffered little from dry rot in almost all cases. Delayed dipping of bruised tubers checked the disease in some trials but not in others. Seed tubers severely bruised 1-2 weeks after being dipped remained practically sound except in one instance, whereas tubers severely bruised approximately 3 months after being dipped, subsequently developed severe dry rot in four out of six tests, unless they had been redipped immediately before they were bruised.
Inoculation of healthy tubers with soil samples showed that the fungus is widely distributed in potato fields in Cheshire. Dipping killed all, or almost all, of the fungus in the soil adhering to the seed tubers.
The results are discussed and suggestions are made for further investigations and for practical control measures.     

Inhibitory effect of phorbol ester on carbachol-induced signal transduction in cultured canine tracheal smooth muscle cells

Regulation of the increases in inositol 1,4,5-trisphosphate (IP₃) production and intracellular Ca²⁺ concentration ([Ca²⁺]_i) by activation of protein kinase C (PKC) was investigated in cultured canine tracheal smooth muscle cells (TSMCs). Stimulation of TSMCs by carbachol led to IP₃ formation and caused an initial transient peak of [Ca²⁺]_i followed by a sustained elevation in a concentration-dependent manner. Pretreatment of TSMCs with phorbol 12-myristate 13-acetate (PMA, 1 µM) for 30 min blocked the carbachol-induced IP₃ formation and Ca²⁺ mobilization. Following preincubation, carbachol-induced Ca²⁺ mobilization recovered within 24 h. The concentrations of PMA that gave half-maximal inhibition of carbachol-induced IP₃ formation and increase in [Ca²⁺]_i were 7 and 4 nM, respectively. Prior treatment of TSMCs with staurosporine (1 µM), a PKC inhibitor, inhibited the ability of PMA to attenuate carbachol-induced responses. Inactive phorbol ester, 4-phorbol 12,13-didecanoate at 1 µM, did not inhibit these responses to carbachol. The K_d and B_max of the muscarinic receptor for [³H]N-methylscopolamine binding were not significantly changed by PMA treatment. PMA also decreased PKC activity in the cytosol of TSMCs, while increasing it transiently in the membranes within 30 min. Thereafter, the membrane-associated PKC activity decreased and persisted for at least 24 h of PMA treatment. Taken together, these results suggest that activation of PKC may inhibit phosphoinositide hydrolysis and consequently attenuate the [Ca²⁺]_i increase or inhibit both responses independently. The inhibition by PMA of carbachol-induced responses was inversely correlated with membranous PKC activity.     

Exercise training activates large-conductance calcium-activated K+ channels and enhances nitric oxide production in rat mesenteric artery and thoracic aorta

Exercise training has reversible beneficial effects on cardiovascular diseases, e.g. hypertension, which may result from a decrease in systemic vascular resistance. The purpose of this study was to investigate possible mechanisms associated with the changes in vascular reactivity in large and small arteries with vasoconstrictors and vasodilators in rats after exercise. Wistar-Kyoto rats were trained for 8 weeks (Ex group) on a treadmill and compared with sedentary counterparts (Sed group). After the measurement of blood pressure and heart rate at 8 weeks, rat mesenteric arteries and thoracic aortas were excised and prepared as rings for this study. In addition, special care was taken not to damage the endothelium of the preparations. Our results showed that exercise training for 8 weeks (1) not only prevented an increase in blood pressure but also caused a fall in heart rate, (2) attenuated the contractions induced by both prostaglandin F(2alpha) (PGF(2alpha)) and high K(+) in the mesenteric artery, but reduced the PGF(2alpha)-induced contraction in the aorta only, (3) enhanced the relaxation elicited by acetylcholine (ACh) in both mesenteric arteries and aortas, and (4) increased nitrate [an indicator of nitric oxide (NO) formation] in plasma. The enhancement of ACh-induced relaxation in the mesenteric arteries in the Ex group was suppressed by pretreatment with N(omega) -nitro-L-arginine methyl ester (L-NAME), tetraethylammonium (TEA; a nonselective inhibitor of K(+) channels) or charybdotoxin [CTX; a selective inhibitor of large-conductance calcium-activated K(+) (BK(Ca)) channels], whereas in the aorta that response was attenuated by TEA or CTX and almost completely abolished by L-NAME. However, with a combination of L-NAME plus CTX in the mesenteric artery, ACh-induced relaxation was completely abolished in the Sed group, but not in the Ex group. These results suggest that in addition to NO, activation of BK(Ca) channels in the vascular beds, at least in part, also contributes to vasodilatation in animals with exercise training.     

Evaluation of self-similar features in time series of serum growth hormone and prolactin levels by fractal analysis: Effect of delayed sleep and complexity of diurnal variation

We assayed the diurnal concentrations of growth hormone (GH) and prolactin (PRL) in 6 healthy male volunteers to evaluate the self-similar features in the time series of each hormone on the basis of fractal theory and to determine the fractal dimension as an index of the complexity of the diurnal variation. In addition, we assessed the effects of a 6-hour delay in the sleep period on the complexity of the diurnal variaton of these hormones. There was a statistically significant fractal feature in the serum levels of GH both under the nocturnal-sleep and delayed-sleep conditions in all subjects. The time series of the serum PRL concentrations also showed a statistically significant fractal feature under the nocturnal-sleep and delayed-sleep conditions in all subjects. The fractal dimensions of the patterns of the GH or PRL levels were 1.879 and 1.929 or 1.754 and 1.785 under the nocturnal-sleep and delayed-sleep conditions, respectively. Two-way ANOVA revealed no significant difference in the fractal dimension between the two sleep conditions but did reveal a significant difference between the fractal dimensions of the GH and PRL levels. These results showed (1) that delayed sleep had no significant effect on the complexity of the diurnal pattern of these hormones, and (2) that the diurnal pattern of the GH levels was more complex than that of the PRL levels.     

Targeting to the HIV-1 RRE of the influenza virus NS1 protein effector domain as a potent, specific anti-HIV agent

The Rev axis of HIV autoregulation is one of two critical viral regulatory pathways required for expression of viral genomic and mRNA and for replication. Consequently it is an attractive therapeutic target. Previous studies have investigated the anti-HIV efficacy of targeting to the RRE (the viral RNA target sequence of the Rev axis) a trans-dominant negative inhibitor mutant Rev, M10. In this study we have fused a portion of the influenza virus NS1 protein (which normally inhibits polyA(+) mRNA transport and splicing) to the Rev M10 gene while deleting the NS1 poly(A) binding region. The resulting chimera demonstrates specific and enhanced inhibition of viral-RRE-containing RNA expression.