Effects of Autogamy In Paramecium Tetraurelia On Catalase Activity and On Radiosensitivity to Natural Ionizing Radiations

SYNOPSIS Catalase activity of Paramecium tetraurelia decreased during autogamy and recovered to normal 5 days later. Autogamy also caused changes in the ciliate's sensitivity to natural ionizing radiations—the decrease in cell growth rate previously described in shielded cultures did not occur when autogamous cells were used. Maximum effect of shielding was observed in 11-day-old postautogamous cells. the role of the catalase in the mechanism of natural irradiation effect is discussed.     

Use of Radiation Hybrid panels to map genetic loci

The mapping of genetic loci within organisms has been accelerated by the advent of Radiation Hybrid (RH) panels. These panels are available for humans and non-humans including mice, baboon, rat, and canine. This article contains a general protocol for the use of the Genebridge 4 whole genome RH panel to map a human locus. This protocol may also be adjusted to suit the other RH panels currently available.     

Combined effect of X‐ray radiation and static magnetic fields on reactive oxygen species in rat lymphocytes in vitro

The aim of this study was to investigate the effect of static magnetic fields (SMF) on reactive oxygen species induced by X‐ray radiation. The experiments were performed on lymphocytes from male albino Wistar rats. After exposure to 3 Gy X‐ray radiation (with a dose rate of 560 mGy/min) the measurement of intracellular reactive oxygen species in lymphocytes, using a fluorescent probe, was done before exposure to the SMF, and after 15 min, 1 and 2 h of exposure to the SMF or a corresponding incubation time. For SMF exposure, 0 mT (50 µT magnetic field induction opposite to the geomagnetic field) and 5 mT fields were chosen. The trend of SMF effects for 0 mT was always opposite that of 5 mT. The first one decreased the rate of fluorescence change, while the latter one increased it. Bioelectromagnetics 34:333–336, 2013. © 2012 Wiley Periodicals, Inc.     

Area and the rapid radiation of Hawaiian Bidens (Asteraceae)

Aim To estimate the rate of adaptive radiation of endemic Hawaiian Bidens and to compare their diversification rates with those of other plants in Hawaii and elsewhere with rapid rates of radiation. Location Hawaii. Methods Fifty‐nine samples representing all 19 Hawaiian species, six Hawaiian subspecies, two Hawaiian hybrids and an additional two Central American and two African Bidens species had their DNA extracted, amplified by polymerase chain reaction and sequenced for four chloroplast and two nuclear loci, resulting in a total of approximately 5400 base pairs per individual. Internal transcribed spacer sequences for additional outgroup taxa, including 13 non‐Hawaiian Bidens, were obtained from GenBank. Phylogenetic relationships were assessed by maximum likelihood and Bayesian inference. The age of the most recent common ancestor and diversification rates of Hawaiian Bidens were estimated using the methods of previously published studies to allow for direct comparison with other studies. Calculations were made on a per‐unit‐area basis. Results We estimate the age of the Hawaiian clade to be 1.3–3.1 million years old, with an estimated diversification rate of 0.3–2.3 species/million years and 4.8 × 10^?5 to 1.3 × 10^?4 species Myr^?1 km^?2. Bidens species are found in Europe, Africa, Asia and North and South America, but the Hawaiian species have greater diversity of growth form, floral morphology, dispersal mode and habitat type than observed in the rest of the genus world‐wide. Despite this diversity, we found little genetic differentiation among the Hawaiian species. This is similar to the results from other molecular studies on Hawaiian plant taxa, including others with great morphological variability (e.g. silverswords, lobeliads and mints). Main conclusions On a per‐unit‐area basis, Hawaiian Bidens have among the highest rates of speciation for plant radiations documented to date. The rapid diversification within such a small area was probably facilitated by the habitat diversity of the Hawaiian Islands and the adaptive loss of dispersal potential. Our findings point to the need to consider the spatial context of diversification – specifically, the relative scale of habitable area, environmental heterogeneity and dispersal ability – to understand the rate and extent of adaptive radiation.     

Protein kinase A inhibitors enhance radiation-induced apoptosis

In addition to a role for de novo protein synthesis in apoptosis we have previously shown that activation of a protein phosphatase or loss of activity of a kinase is also important in radiation-induced apoptosis in human cells [Baxter, and Lavin (1992): J Immunol 148:149–1954]. We show here that some inhibitors of protein kinases exacerbate radiation-induced apoptosis in the human cell line BM13674. The specific protein kinase A inhibitor isoquinoline sulfonamide (20 μM) gave rise to significantly increased levels of apoptosis at 2–6 h postirradiation compared to values after radiation exposure only. The same concentration of isoquinolinesulfonamide, which was effective in increasing apoptosis, reduced activity markedly. A 66% inhibition of cyclic AMP-dependent protein kinase A activity occurred in unirradiated cells at this concentration of H89 and activity was reduced to 58% in irradiated cells. Calphostin C, a specific inhibitor of protein kinase C, at a concentration of 0.1 μM, which caused 68% inhibition of enzyme activity in irradiated cells, failed to enhance the level of radiation-induced apoptosis. Other kinase inhibitors did not lead to an additional increase in apoptosis over and above that observed after irradiation. The results obtained here provide further support for an important role for modification of existing proteins during radiation-induced apoptosis.     

Micropropagation of Calluna vulgaris cv. ‘H.E. Beale’

Axillary shoot producing cultures were obtained from microcuttings and shoot tips of Calluna vulgaris cv. H.E. Beale. For cultures derived from microcuttings the highest multiplication rate of 38 shoots (5 mm or longer) was obtained on a reduced salt medium with the addition of 0.5 mgl^-1 2-isopentenyladenine (2iP) during an 8 week subculture. For shoot tip derived cultures 0.2 mgl^-1 6-benzyladenine (BA) was the best cytokinin and led to a multiplication rate of 26 for a 6 week subculture. The addition of 1 g/l casein hydrolysate to a multiplication medium enhanced shoot proliferation in presence of 0.5 mgl^-1 BA.Despite various auxin treatments shoots formed no roots in vitro but rooted readily if transferred to a peat substrate ex vitro. A high rooting percentage (80%) was also obtained with shoots taken from the end of a multiplication phase and rooted directly. An additional subculture on low auxin containing media before transfer to peat substrate is recommended because the shoot condition can be improved in this way. A high number of rooted plantlets was produced, so the methods described will allow mass propagation.     

High-dose mode of death in Tribolium

This study reports the first demonstration within a single insect genus (Tribolium) of both the acute, or lethal-midlethal, dose-independent pattern of mortality, and the hyperacute, dose-dependent pattern, after appropriate doses of ionizing radiation. This demonstration provides resolution of apparently contradictory reports of insect responses in terms of doses required to cause lethality and those based on survival time as a function of dose. A dose-dependent mortality pattern was elicited in adult Tribolium receiving high doses, viz., 300 Gy or greater; its time-course was complete in 10 days, before the dose-independent mortality began. Visual observations of heavily-irradiated Tribolium suggested neural and/or neuromuscular damage, as had been previously proposed by others for lethally-irradiated wasps, flies, and mosquitoes. Results of experiments using fractionated high doses supported the suggestion that the hyperacute or high-dose mode of death is the result of damage to nonproliferative tissues. Relative resistance of a strain to the hyperacute or high-dose mode of death is not necessarily correlated with resistance to the midlethal mode, which is believed to be the result of damage to the proliferative cells of the midgut.

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Résumé Les résultats de nombreuses études des réactions des insectes adultes de différents groupes à l'irradiation s'opposent quant à l'importance de la dose provoquant la létalité et quant aux modalités de la mort. Les diptères et les guèpes impliquent des doses très élevées,-des centaines de Gy-, ne présentent aucune période caractérisant la mort par irradiation, et décèdent de plus en plus tôt avec l'augmentation des doses. Beaucoup d'autres insectes succombent à des doses (milétalelétale) beaucoup plus faibles,-de quelques Gy à des dizaines-, et quelle que soit la dose meurent au bout d'un temps voisin.Au cours de cette étude, nous avons pu observer que ces deux types de mortalité peuvent être provoqués chez le même genre d'insecte (Tribolium), avec des doses convenables d'irradiation . Un syndrôme caractéristique a été provoqué avec des doses très élevées, de 300 Gy ou plus,-à ces doses la mort est obtenue en 10 jours après l'irradiation. L'absence de syndrôme caractéristique se produit avec des doses inférieures ou égales à 80 Gy; la mort a lieu alors entre 10 et 16 jours en fonction de la dose.Les différences entre les deux types de décès indiquent deux processus de mort par irradiation. La manifestation d'une désorientation et d'une perte de coordination motrice chez les Tribolium fortement irradiés suggère des altérations neurales et/ou neuromusculaires comme cause/s de ce type de mort provoquée par des doses élevées. L'implication de tissus sans prolifération a été confortée par les résultats d'expériences utilisant de hautes doses fractionnées. Le type de mort milétal est considéré après de nombreuses observations indépendantes, comme le résultat d'atteintes à la prolifération des cellules de l'intestin moyen.Les données contradictoires sur les réactions des insectes aux irradiations proviennent d'abord de l'absence de connaissances sur le lieu des dégâts. Les diptères sont connus maintenant, après différentes études, comme perdant complètement l'aptitude au renouvellement cellulaire, et présentent ainsi un type de mort avec dose élevée. Beaucoup d'autres insectes adultes ont un renouvellement cellulaire de l'intestin moyen limité, et ainsi présentent le type de mort milétal. Le type de mort, dit haute dose, peut être induit dans cette dernière catégorie d'insectes par une irradiation suffisamment forte, et, dans le cas du Tribolium le déroulement de la mort se produit alors de deux façons bien distinctes.

     

Biological activities caused by far-infrared radiation

Contrary to previous presumption, accumulated evidence indicates that far-infrared rays are biologically active. A small ceramic disk that emist far-infrared rays (4–16 m) has commonly been applied to a local spot or a whole part of the body for exposure. Pioneering attempts to experimentally analyze an effect of acute and chronic radiation of far-infrared rays on living organisms have detected a growth-promoting effect in growing rats, a sleep-modulatory effect in freely behaving rats and an insomiac patient, and a blood circulation-enhancing effect in human skin. Question-paires to 542 users of far-infrared radiator disks embedded in bedelothes revealed that the majority of the users subjectively evaluated an improvement of their health. These effects on living organisms appear to be non-specifically triggered by an exposure to far-infrared rays, which eventually induce an increase in temperature of the body tissues or, more basically, an elevated motility of body fluids due to decrease in size of water clusters.