Regeneration of plantlets from embryogenic suspension cultures of pickling cucumber (Cucumis Sativus L. CV. Endeavor)

Summary Procedures have been developed for the initiation and long-term maintenance of embryogenic suspension cultures of pickling cucumber (Cucumis sativus) cultivar Endeavor and for the regeneration of normal plantlets. Embryogenic calluses from petiole explants plated on Murashige and Skoog (MS) medium with 2,4-dichlorophenoxyacetic acid (2,4-D) and 6-benzylaminopurine (BA), both at 5μM, were used to initiate the embryogenic suspension cultures. Among various growth regulator combinations evaluated for initiation and maintenance of these suspension cultures, only MS medium with 2,4-D and BA, both at 1μM, produced cultures that were yellow, friable, and still regenerable after repeated subculture (every two wk) over a 3- to 15-mo. period. The effects of various concentrations of auxin and cytokinin in the plating medium, the addition of AgNO₃, and various plating procedures were also evaluated. The highest frequency of regeneration of shoots and plantlets was achieved by plating aggregates onto filter paper overlaid on MS medium with naphthalene acetic acid (NAA)/BA at a concentration of 2:1 or 1:1μM. The addition of activated charcoal (0.5%) or AgNO₃ (30μM) in the plating medium did not enhance the frequency of plantlet regeneration. The highest frequency of normal-appearing plantlets recovered was 42 to 46% per petri dish. The procedures described in this study can be used to increase plantlet recovery from individual embryogenic calluses of pickling cucumber.     

TP53 codon 72 polymorphism and type 2 diabetes: a case–control study in South Indian population

Molecular Biology Reports - TP53 functions primarily as a tumor suppressor, controlling a myriad of signalling pathways that prevent a cell from undergoing malignant transformation. This tumor...     

Hydrolytic enzymes and antifungal compounds produced by Tilletiopsis species, phyllosphere yeasts that are antagonists of powdery mildew fungi

Isolates of five species of the yeast-like fungus Tilletiopsis Derx (Tilletiopsis albescens Gokhale, Tilletiopsis fulvescens Gokhale, Tilletiopsis minor Nyland, Tilletiopsis pallescens Gokhale, and Tilletiopsis washingtonensis Nyland) were screened for exo- and endo--beta-1,3-glucanase and chitinase production in a liquid broth used to produce inoculum for biological control studies. There were significant differences among the species, and highest overall enzyme activity was present in T albescens and T. pallescens and lowest in T. washingtonensis. A time-course study of beta-1,3-glucanase and chitinase production in T pallescens ATCC 96155 in broth culture with 2.5% glucose as the carbon source showed that enzyme activity gradually increased over a 3- to 21-day period. Maximum enzyme activity was found between pH 4.0 and 5.0. SDS-PAGE of beta-1,3-glucanase isozymes revealed a range of molecular masses from 18 to 29 kDa. Five isozymes were present in both T albescens and T. pallescens and two in T washingtonensis. Antifungal compounds were also detected in ethyl acetate extracts of culture filtrates of T. pallescens ATCC 96155 after 6 days of incubation, while no activity was detected at 14 days. One active fraction was selected following fractionation and preparative chromatography and was bioassayed against Podosphaera (sect. Sphaerotheca) xanthii (Castagne) U. Braun & N. Shishkoff and a number of other fungi. A concentration of 130 microg/mL inhibited germ tube development in P. xanthii, and mildew spores appeared plasmolyzed. Other fungi were inhibited at higher concentrations. Collapse of hyphae and conidiophores was also observed on mildewed leaves treated with the active fraction. Proton NMR analysis indicated that the inhibitory compound was a fatty acid ester. In 3- to 6-day-old cultures of T pallescens ATCC 96155 demonstrating biological control activity, antifungal compound production may have a primary role in restricting growth of mildew fungi and other competitors when applied to leaves.     

Effects of mesophilic and thermophilic composts on suppression of Fusarium root and stem rot of greenhouse cucumber

Three composts were tested for their ability to suppress root and stem rot caused by the soil borne fungal pathogen Fusarium oxysporum f. sp. radicis-cucumerinum (FORC) on cucumber. Two of the composts were prepared from separated dairy solids either by windrow (WDS) or vermicomposting (VMC) while the third, obtained from International Bio-Recovery (IBR), was prepared from vegetable refuse using aerobic digestion. Three sets of potting mixes were prepared by mixing the composts with sawdust at varying ratios, and seeded with cucumber cv. Corona. After 14 days of growth in the greenhouse, inoculum of FORC (20 mL of 5 x 10(6) micro-conidia per mL) was applied to each pot at three different times (14, 21, and 35 days). In unamended inoculated pots, the pathogen caused stunted growth and reduced flowers. Amendment of WDS in the potting mix suppressed these symptoms, while VMC and IBR had no effect. All three composts reduced the FORC colony forming units (cfu) at the end of the experiment (10 weeks). There was a large increase of fluorescent bacteria near the vicinity of roots particularly in WDS amended potting mixes. When water extracts of the composts were plated onto acidified potato dextrose agar (APDA), only IBR contained a potent thermostable inhibitor to FORC. This inhibitor was removed by activated charcoal but was not partitioned into petroleum ether at acid, basic, or neutral pH. Inhibition of FORC by IBR was not due to electrical conductivity or trace elements in the compost. Contrasting effectiveness of the WDS and VMC made from the same waste suggests that composting method can influence the disease suppression properties of the finished compost.     

Effect of modification of histidine residues on organization of the pigment--protein complexes of chromatium minutissimum

The effect of diethyl pyrocarbonate on chromatophores and isolated pigment--protein complexes of Chromatium minutissimum was studied. It is shown that modification of histidine residues results in the destruction of the core antenna LHI (B880) and in a spectral shift from 850 to 830 nm in the peripheral antenna LHII (B800-850). In the purple sulfur bacterium Chromatium minutissimum the pigment--protein complexes B800-B850 (peripheral antenna, LHII) and B880 (core antenna, LHI) collect and transmit the absorbed light energy to the reaction centers. The composition of pigments and proteins as well as primary structure of the majority of polypeptides in both types of complexes from various photosynthetic bacteria have been determined.     

Transgenic carrot plants accumulating ketocarotenoids show tolerance to UV and oxidative stresses

Ketocarotenoids are strong antioxidant compounds which accumulate in salmon, shrimp, crustaceans and algae, but are rarely found naturally in higher plants. In this study, we engineered constitutive expression of an algal beta-carotene ketolase gene (bkt) in carrot plants to produce a number of ketocarotenoids from beta-carotene. These included astaxanthin, adonirubin, canthaxanthin, echinenone, adonixanthin and beta-cryptoxanthin. Leaves accumulated up to 56mug/g total ketocarotenoids and contained higher beta-carotene levels but lower levels of alpha-carotene and lutein. The photosynthetic capacity of transgenic plants was not significantly altered by these changes. However, when high-expressing transgenic plants were exposed to UV-B irradiation, they grew significantly better than the wild-type controls. Similarly, leaf tissues exposed to various oxidative stresses including treatment with H(2)O(2) and methyl viologen showed less injury and retained higher levels of chlorophyll a+b. Total carotenoid extracts from transgenic leaves had higher antioxidant and free-radical scavenging activity in vitro compared to control leaves. Transgenic tissues also accumulated lower amounts of H(2)O(2) following exposure to oxidative stresses, suggesting that free radical and reactive oxygen species were quenched by the ketocarotenoids.     

Do western boxelder bugs sunbathe for sanitation? Inferences from in vitro experiments

When western boxelder bugs, Boisea rubrolineata (Barber) (Hemiptera: Rhopalidae), form aggregations in warm sunlight, they release from their posterior dorsal abdominal gland an odorous blend of monoterpenes with heretofore unknown biological function. In laboratory analyses and experiments, we show that bugs in warm sunlight, but not in shade, exude and spread copious amounts of monoterpenes onto their cuticle. These monoterpenes do not serve as a pheromone, but rather as a means of sanitation. They inhibit germination of conidia of the fungal pathogen Beauveria bassiana (Bals.‐Criv.) Vuill. (Hypocreales) as well as halt the growth of germinated spores. This prophylactic defense against pathogens appears adaptive for phytophagous insects, like B. rubrolineata, that are prone to infections by microbes thriving on leaf surfaces and in the insects' overwintering microhabitat.     

Human MSH2 (hMSH2) protein controls ATP processing by hMSH2-hMSH6

The mechanics of hMSH2-hMSH6 ATP binding and hydrolysis are critical to several proposed mechanisms for mismatch repair (MMR), which in turn rely on the detailed coordination of ATP processing between the individual hMSH2 and hMSH6 subunits. Here we show that hMSH2-hMSH6 is strictly controlled by hMSH2 and magnesium in a complex with ADP (hMSH2(magnesium-ADP)-hMSH6). Destabilization of magnesium results in ADP release from hMSH2 that allows high affinity ATP binding by hMSH6, which then enhances ATP binding by hMSH2. Both subunits must be ATP-bound to efficiently form a stable hMSH2-hMSH6 hydrolysis-independent sliding clamp required for MMR. In the presence of magnesium, the ATP-bound sliding clamps remain on the DNA for ～8 min. These results suggest a precise stepwise kinetic mechanism for hMSH2-hMSH6 functions that appears to mimic G protein switches, severely constrains models for MMR, and may partially explain the MSH2 allele frequency in Lynch syndrome or hereditary nonpolyposis colorectal cancer.     

Rhodiola Rosea for Mental and Physical Fatigue in Nursing Students: A Randomized Controlled Trial

Background

Fatigue is one of many unintended consequences of shift work in the nursing profession. Natural health products (NHPs) for fatigue are becoming an increasingly popular topic of clinical study; one such NHP is Rhodiola rosea. A well-designed, rigorously conducted randomized controlled trial is required before therapeutic claims for this product can be made.

Objective

To compare the efficacy of R. rosea with placebo for reducing fatigue in nursing students on shift work.

Design

A parallel-group randomized, double-blinded, placebo-controlled trial of 18–55 year old students from the Faculty of Nursing from the University of Alberta, participating in clinical rotations between January 2011 and September 2011.

Interventions

Participants were randomized to take 364 mg of either R. rosea or identical placebo at the start of their wakeful period and up to one additional capsule within the following four hours on a daily basis over a 42-day period.

Outcomes

The primary outcome was reduction in fatigue over the 42-day trial period measured using the Vitality-subscale of the RAND-36, cross-validated by the visual analogue scale for fatigue (VAS-F). Secondary outcomes included health-related quality of life, individualized outcomes assessment, and adverse events.

Results

A total of 48 participants were randomized to R. rosea (n = 24) or placebo (n = 24). The mean change in scores on the Vitality-subscale was significantly different between the study groups at day 42 in favor of placebo (−17.3 (95% CI −30.6, −3.9), p = 0.011), The mean change in scores on the VAS-F was also significantly difference between study groups at day 42 in favour of placebo (1.9 (95% CI 0.4, 3.5), p = 0.015). Total number of adverse events did not differ between R. rosea and placebo groups.

Conclusion

This study indicates that among nursing students on shift work, a 42-day course of R. Rosea compared with placebo worsened fatigue; however, the results should be interpreted with caution.

Trial Registration

Clinicaltrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01278992","term_id":"NCT01278992"}}NCT01278992