Effect of electromagnetic radiofrequency radiation on the rats' brain, liver and kidney cells measured by comet assay

The goal of study was to evaluate DNA damage in rat's renal, liver and brain cells after in vivo exposure to radiofrequency/microwave (Rf/Mw) radiation of cellular phone frequencies range. To determine DNA damage, a single cell gel electrophoresis/comet assay was used. Wistar rats (male, 12 week old, approximate body weight 350 g) (N = 9) were exposed to the carrier frequency of 915 MHz with Global System Mobile signal modulation (GSM), power density of 2.4 W/m2, whole body average specific absorption rate SAR of 0.6 W/kg. The animals were irradiated for one hour/day, seven days/week during two weeks period. The exposure set-up was Gigahertz Transversal Electromagnetic Mode Cell (GTEM--cell). Sham irradiated controls (N = 9) were apart of the study. The body temperature was measured before and after exposure. There were no differences in temperature in between control and treated animals. Comet assay parameters such as the tail length and tail intensity were evaluated. In comparison with tail length in controls (13.5 +/- 0.7 microm), the tail was slightly elongated in brain cells of irradiated animals (14.0 +/- 0.3 microm). The tail length obtained for liver (14.5 +/- 0.3 microm) and kidney (13.9 +/- 0.5 microm) homogenates notably differs in comparison with matched sham controls (13.6 +/- 0.3 microm) and (12.9 +/- 0.9 microm). Differences in tail intensity between control and exposed animals were not significant. The results of this study suggest that, under the experimental conditions applied, repeated 915 MHz irradiation could be a cause of DNA breaks in renal and liver cells, but not affect the cell genome at the higher extent compared to the basal damage.     

The association between changes in the intravaginal electrical resistance and the in vitro measurements of vaginal mucus electrical resistivity in cattle

A system was developed for measuring in vitro the electrical resistivity (ρ) of vaginal mucus samples collected throughout a complete oestrous cycle from three Hereford × Friesian cows. Measurements of intravaginal electrical resistance (Rv) and mucus electrical resistivity were made in six Hereford × Friesian cows throughout a complete normal oestrous cycle. Both Rν and ρ fluctuated during dioestrus and fell to a minimum value at oestrus. The decrease in ρ was larger than that of Rν. A significant correlation was found between Rν and ρ (P < 0.01; r = 0.56).     

Physical properties of flowing blood

The changes of viscosity, optical reflection and electrical resistivity of blood due to flow are dependent on the orientation and deformation of red cells. From electrical point of view, it can be assumed that blood is suspension of small insulating particles (red cells) in conductive fluid (plasma) when the frequency of supplied voltage is lower than several hundreds KHz. When blood flows, red cells deform and orient in flow direction. Therefore, flowing blood shows anisotropic electrical and optical properties. In steady flow, blood resistivity longitudinal to flow decrease with flow rate, and transverse one increases. Blood flow in living body is not steady but pulsatile. We measured both longitudinal and transverse resistivity changes, optical reflection change and viscosity change of sinusoidally flowing blood in a rectangular conduit. The results are 1) during one period of sinusoidal flow the longitudinal resistivity change is opposite to that of transverse one, 2) the waveform of reflection light change is similar to that of resistance change, and 3) minimum points of both longitudinal resistivity and viscosity changes do not appear at the moment when flow is zero but are delayed. When the amplitude of sinusoidal flow is small and oscillation frequency is high, the phase difference between the zero crossing period of flow and the period of minimum change in resistivity, increases up to 90 degrees. Viscosity of blood decreases with increase of amplitude and frequency of sinusoidal flow.     

Redistribution of blood within the body is important for thermoregulation in an ectothermic vertebrate (<Emphasis Type="Italic">Crocodylus porosus</Emphasis>)

Changes in blood flow are a principal mechanism of thermoregulation in vertebrates. Changes in heart rate will alter blood flow, although multiple demands for limited cardiac output may compromise effective thermoregulation. We tested the hypothesis that regional differences in blood flow during heating and cooling can occur independently from changes in heart rate. We measured heart rate and blood pressure concurrently with blood flow in the crocodile, Crocodylus porosus. We measured changes in blood flow by laser Doppler flowmetry, and by injecting coloured microspheres. All measurements were made under different heat loads, with and without blocking cholinergic and β-adrenergic receptors (autonomic blockade). Heart rates were significantly faster during heating than cooling in the control animals, but not when autonomic receptors were blocked. There were no significant differences in blood flow distribution between the control and autonomic blockade treatments. In both treatments, blood flow was directed to the dorsal skin and muscle and away from the tail and duodenum during heating. When the heat source was switched off, there was a redistribution of blood from the dorsal surface to the duodenum. Blood flow to the leg skin and muscle, and to the liver did not change significantly with thermal state. Blood pressure was significantly higher during the autonomic blockade than during the control. Thermal time constants of heating and cooling were unaffected by the blockade of autonomic receptors. We concluded that animals partially compensated for a lack of differential heart rates during heating and cooling by redistributing blood within the body, and by increasing blood pressure to increase flow. Hence, measures of heart rate alone are insufficient to assess physiological thermoregulation in reptiles.     

Protective effects of vitamin E against atrazine-induced genotoxicity in rats

Atrazine (2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine) is one of the most commonly used herbicides to control grasses and weeds. The widespread contamination and persistence of atrazine residues in the environment has resulted in human exposure. Vitamin E is a primary antioxidant that plays an important role in protecting cells against toxicity by inactivating free radicals generated following pesticides exposure. The present study was undertaken to investigate the protective effect of vitamin E against atrazine-induced genotoxicity. Three different methods: gel electrophoresis, comet assay and micronucleus test were used to assess the atrazine-induced genotoxicity and to evaluate the protective effects of vitamin E. Atrazine was administered to male rats at a dose of 300 mg/kg body weight for a period of 7, 14 and 21 days. There was a significant increase (P<0.001) in tail length of comets from blood and liver cells treated with atrazine as compared to controls. Co-administration of vitamin E (100 mg/kg body weight) along with atrazine resulted in decrease in tail length of comets as compared to the group treated with atrazine alone. Micronucleus assay revealed a significant increase (P<0.001) in the frequency of micronucleated cells (MNCs) following atrazine administration. In the animals administrated vitamin E along with atrazine there was a significant decrease in percentage of micronuclei as compared to atrazine treated rats. The increase in frequency of micronuclei in liver cells and tail length of comets confirm genotoxicity induced by atrazine in blood and liver cells. In addition, the findings clearly demonstrate protective effect of vitamin E in attenuating atrazine-induced DNA damage.     

Protein synthesis in the organs and tissues of frogs with local exposure to low temperatures]

Intensity of synthesis of total proteins and spectrum of synthesized proteins has been studied in various organs and tissues of sharp-faced frogs during local profound cooling of one of its limbs. It was shown that the effect of low temperatures on a certain part of a body of a poikilothermic animal has induced both a response of the whole organism and a much more acute response of the cooled tissues. The organism responded by a fall of the whole body temperature and a decrease in the activity of synthesis of total proteins of the viscera. Local cooling of a part of the frog body has induced a more significant decrease in the protein synthesis intensity in the cooled tissues alteration in the spectrum of synthesized proteins and appearance of specific proteins.     

The Influence of Tail Autotomy on the Escape Response of the Cape Dwarf Gecko, Lygodactylus capensis

Tail autotomy as a defence against predators occurs in many species of lizard. Although tail autotomy may provide an immediate benefit in terms of survival it may nevertheless be costly due to other functions of the tail. For example, tail autotomy may affect the locomotory performance of lizards during escape. We investigated the influence of tail autotomy on the escape performance of the Cape Dwarf Gecko, Lygodactylus capensis, on a vertical and a horizontal surface. Autotomized geckos were significantly slower than intact geckos during vertical escape, whereas tail autotomy did not influence the horizontal escape speed. Backward falling of the autotomized geckos on the vertical platform may explain the reduced speed. In addition, tail autotomy did not significantly affect body curvature and stride length of the geckos. The observed decrease of escape speed on a vertical platform may influence the habitat use and behaviour of these geckos. Ecological consequences resulting from tail autotomy are discussed in light of these findings.     

DNA synthesis and turnover in the bullfrog tadpole during metamorphosis.

125I-labeled deoxyuridine (IdUrd) has been used to estimate the turnover of DNA in liver, tail, and hind limb during spontaneous and triiodothyronine-induced metamorphosis. It was found that the total amount of liver DNA remained constant and there was no significant loss of the label from the liver DNA, which would be expected if there was an increase in DNA turnover during metamorphosis. Also, the change in specific activity of liver DNA parallels that of tail DNA during spontaneous metamorphosis. These data suggest that metamorphic transitions in the tadpole liver do not involve significant changes in DNA turnover. It was observed that the incorporation of label into hind limb DNA showed a high variability among individual animals as compared to liver and tail tissue. The data presented suggest that the observed variability is not a random phenomenon but related directly to the rate at which animals will metamorphose.     

Changes in heart rate are important for thermoregulation in the varanid lizard Varanus varius

Laboratory studies and a single field study have shown that heart rate in some reptiles is faster during heating than during cooling at any given body temperature. This phenomenon, which has been shown to reflect changes in peripheral blood flow, is shown here to occur in the lizard Varanus varius (lace monitor) in the wild. On a typical clear day, lizards emerged from their shelters in the morning to warm in the sun. Following this, animals were active, moving until they again entered a shelter in the evening. During their period of activity, body temperature was 34-36 degrees C in all six study animals (4.0-5.6 kg), but the animals rarely shuttled between sun and shade exposure. Heart rate during the morning heating period was significantly faster than during the evening cooling period. However, the ratio of heating to cooling heart rate decreased with increasing body temperature, being close to 2 at body temperatures of 22-24 degrees C and decreasing to 1.2-1.3 at body temperatures of 34-36 degrees C. There was a significant decrease in thermal time constants with increasing heart rate during heating and cooling confirming that changes in heart rate are linked to rates of heat exchange.     

黄腹山鹪莺成鸟的秋季换羽

黄腹山鹪莺(Prinia flaviventris)具有冬羽尾羽长于繁殖羽尾羽的特点,可能意味着一种新的生存和繁殖策略。为此,从2006年9月～2007年2月,在广东省肇庆市江溪村对黄腹山鹪莺的秋季换羽进行研究。结果显示:(1)黄腹山鹪莺成鸟繁殖羽体长和尾羽长皆极显著短于冬羽(P<0.01),繁殖羽翼长显著短于冬羽(P<0.05),其余身体量度的差异均不显著(P>0.05)。(2)9月17日获得第一个黄腹山鹪莺换羽个体,初级飞羽已更换到P5,次级飞羽已更换到S6,11月20日后所获样本均已完成羽毛的更换。(3)初级飞羽的换羽模式为递降换羽,次级飞羽为递升换羽,尾羽为离心型换羽。(4)换羽期间,10月的个体平均体重最大,显著(P<0.01)重于11月的体重,其他各月无显著性差异(P>0.05)。据此,推测黄腹山鹪莺秋季种群换羽的持续时间约100d;相对其他羽毛而言,尾羽更换对黄腹山鹪莺生长发育的影响更为明显。     

Reduced tail regeneration in the Common Lizard, Lacerta vivipara, parasitized by blood parasites

1. Many lizards will lose their tail through autotomy as an antipredator device even though there must be significant costs during tail regeneration.
2. Parasites are energetically costly to the host, and may reduce the rate of cell regeneration. The relation between the presence of haemogregarines (phylum Sporozoa) and the rate of tail regeneration in the Common Lizard Lacerta vivipara (Jacquin) was examined.
3. Experimentally induced autotomy in parasitized lizards resulted in a significantly reduced rate of tail regeneration compared with non-parasitized lizards. On the other hand, tail loss was not associated with an abnormal increase of parasite load, suggesting that the physiological stress (induced by tail loss) did not cause a decrease in parasite defence.     

Effect of prenatal gamma irradiation during the late fetal period on the postnatal development of the mouse

Pregnant Swiss albino mice were exposed to 0.3, 0.5, 1.0, or 1.5 Gy of gamma radiation on day 17 of gestation. Sham-exposed controls were examined for comparison. Exposed mice as well as controls were left to complete gestation and parturition. Pups were observed up to age 6 weeks; appearance of physiological markers (pinna detachment, eye opening, fur development, vaginal opening, and testes descent), postnatal mortality, body weight, body length, head length, head width, and tail length were recorded. A significant delay in fur development was observed at 0.3 Gy and in other physiological markers at doses above 0.3 Gy, while a significant increase in mortality and growth retardation occurred only at 1.0 and 1.5 Gy. Although congenital anomalies such as syndactyly and bent tail were observed at doses of 0.5-1.5 Gy, only syndactyly showed a statistically significant increase in frequency. A statistically significant lower body weight was observed during the first week of postnatal life, but body weights increased to normal levels by the second week in animals exposed to doses less than 1.0 Gy. At higher doses, low body weight persisted throughout the postnatal period. Head length and tail length showed a significant decrease from controls at 0.5-1.5 Gy, and the effect was evident from birth to age 6 weeks. But a similar effect on body length and head width was noticed only at 1.0 and 1.5 Gy. These studies indicate that even in the absence of any major morphological changes, normal development of physiological landmarks and postnatal growth can be impaired by fetal irradiation at 17 days p.c. (post coitus). Morphological changes appear to have a threshold between 0.3-0.5 Gy, while physiological marker effects may occur with a lower threshold.     

长期强迫运动对大绒鼠体重、能量代谢和血清瘦素的影响

动物稳定体重的维持需要能量摄入和消耗之间的平衡。运动是影响动物能量平衡的重要因素之一。为了解运动对大绒鼠(Eothenomys miletus)的生理学效应,在室内条件下,测定了强迫运动训练(运用小鼠封闭跑台)8周后大绒鼠的体重、代谢率、摄入能、血清瘦素和身体组成的变化。结果显示,强迫运动训练8周对大绒鼠的体重无显著影响;大绒鼠的代谢率和摄入能均显著增加,训练8周后静止代谢率较对照组增加了29.9%,运动最大代谢率较对照组增加了10.7%;强迫运动训练8周组的身体脂肪重量比对照组降低了28.9%,血清瘦素水平比对照组下降了27.4%,对照组的瘦素与体脂含量具有明显的相关性,但运动组则不具有相关性;运动组的肝重量和消化道重量较对照组均显著增加;而体水重量则显著降低。这些结果表明,在强迫运动训练期间大绒鼠主要通过动员储存的脂肪、增加代谢率和食物摄入的方式来维持自身的体重及能量平衡。瘦素在长期强迫运动过程中对身体脂肪含量的变化具有调节作用。     

Topochemical aspects of nucleic-acid and protein metabolism within the neuron-neuroglia unit of the hypothalamic supraoptic nucleus

The RNA and both the total and basic protein content of individual cells were determined by cytospectrophotometry in neurons and perineuronal oligodendroglia of the hypothalamic supraoptic nucleus in rats subjected to various stresses, as well as in ground squirrels during natural hibernation. Barbiturate narcosis and deep cooling, which induced a decrease in body temperature in rats and hibernation in squirrels, caused a marked decrease of all macromolecular constituents in neurons. A similar decrease was found in the perineuronal oligodendroglia in rats, but an increase was observed in ground squirrels. After cessation of cooling, while the body temperature of the animals returned to normal, the neurons, but not the oligodendroglia, of rats showed a significant accumulation of RNA, while RNA accumulated in both neurons and perineuronal oligodendroglia in ground squirrels. Milder cooling of rats, which did not lower their body temperature, induced reciprocal changes in basic-protein content in neuronal and glial cell nuclei, with the accumulation of protein occurring initially in neurons, and subsequently in glia. When cold adaptation was accomplished, the basic protein content of neurons and glial cells returned to the control level. Four days after adrenalectomy in rats, the RNA content decreased in oligodendroglia but not in neurons of the supraoptic nucleus. This effect was completely abolished by daily injections of cortisol in the adrenalectomized animals. The data obtained indicate the existence of differences in metabolic responses to stress between neurons and glial cells of the supraoptic nucleus of the hypothalamus.     

Thyroid hormone-dependent gene expression as a biomarker of short-term 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) exposure in European common frog (Rana temporaria) tadpoles.

The effects on thyroid hormone-dependent gene biomarker responses of the persistent organochlorine pesticide metabolite 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) were investigated after exposure of 4-week-old European common frog (Rana temporaria) (stage 36) tadpoles to two (0.001 and 0.01 ppm) DDE concentrations. Total body weight, total length, and tail length and width increased after 3-day exposure to DDE. Expression patterns of genes encoding for growth hormone, thyroid-stimulating hormone (TSHbeta) and thyroid hormone receptor (TRalpha and TRbeta) isoforms were evaluated in the head, body and tail regions using a validated real-time polymerase chain reaction (PCR) method. The mRNA expression of growth hormone in the body, and TSHbeta in the head showed significant DDE concentration-dependent decreases. While DDE caused variable effects on TRalpha mRNA steady-state, the expression of TRbeta was significantly decreased in the tail by DDE in a concentration-specific manner. The effect of DDE exposure on TRbeta mRNA expression showed a negative correlation with tail length and width during the exposure period. The unique pattern of a DDE-induced decrease of tail TRbeta expression probably reflects the significant role of this thyroid hormone receptor isoform in tail re-absorption and overall metamorphosis in anuran species. Therefore, the present study shows that the evaluation of thyroid hormone-dependent genes may represent quantitative biomarkers of acute exposure to organochlorine pesticides in anuran species during critical developmental periods such as metamorphosis. Given the widespread environmental levels of DDT and its metabolites, these pollutants will remain a subject of concern and their effects on anuran species should be studied in more detail.     

Depression of mitochondrial respiration during daily torpor of the Djungarian hamster,Phodopus sungorus,is specific for liver and correlates with body temperature

Small mammals actively decrease metabolism during daily torpor and hibernation to save energy. Increasing evidence suggests depression of mitochondrial respiration during daily torpor of the Djungarian hamster but tissue-specificity and relation to torpor depth is unknown. We first confirmed a previous study by Brown and colleagues reporting on the depressed substrate oxidation in isolated liver mitochondria of the Djungarian hamster (Phodopus sungorus) during daily torpor. Next, we show that mitochondrial respiration is not depressed in kidneys, skeletal muscle and heart. In liver mitochondria, we found that state 3 and state 4 respirations correlate with body temperature, suggesting inhibition related to torpor depth and to metabolic rate. We conclude that molecular events leading to depression of mitochondrial respiration during daily torpor are specific to liver and linked to a decrease in body temperature. Different tissue-specificity of mitochondrial depression may assist to compare and identify the molecular nature of mitochondrial alterations during torpor.     

Body weight: its relation to tissue composition, segment distribution, and motor function. II. Development of Macaca mulatta.

The relative composition of skin, muscle, and bone and their distribution patterns throughout the body are given for a series of Macaca mulatta from 171 days conceptual age through adulthood. In terms of percent of total body weight, the musculature of these animals doubles during the firs postnatal year whereas bone and skin decrease. Regionally, the muscles of the thighs, back extensors, truncal-forelimb and upper arms increase most markedly. The thighs double and the upper arms increase whereas the trunk, hands, feet, and tail decrease. The biomechanical implications of these changes for motor development are discussed.     

Changes in amino acid uptake and protein synthesis of bullfrog tadpole liver and tail tissues during triiodothyronine-induced metamorphosis

The effect of triiodothyronine (T₃′) on the uptake of several amino acids into the amino acid pools and into proteins of Rana catesbeiana tadpole liver and tail muscle and tail fin has been studied. Labeling of the alanine and glycine pool was stimulated in the liver more than the leucine pool. After exposure to T₃ for 3 days, uptake of α-aminoisobutyric acid (a transport model substrate) into liver was stimulated about 55%. In tail tissues uptake of leucine was stimulated but uptake of alanine was depressed by T₃. Incorporation of leucine and alanine into tissue protein was stimulated in the liver but inhibited in tail tissues after T₃ injection.Changes in other macromolecules and ATP and ADP levels in liver and tail muscle were also investigated during induced metamorphosis. In the liver, the total DNA content did not change, but the RNA and protein content per liver increased significantly. The increase in RNA/DNA and protein/DNA ratios, suggested that liver cells underwent hypertrophy during induced metamorphosis. The ATP level showed a transient decrease after 3 days of T₃ treatment. In tail muscle, protein and RNA content decreased as the muscle regressed, but the DNA content and ATP level remained unchanged throughout the experimental period.     

Alanine aminopeptidase activity and autolysis in the tails of Rana catesbeiana larvae during metamorphosis.

1. Alanine aminopeptidase activity and autolysis increase concomitantly in tail tissue of Rana catesbeiana tadpoles during metamorphosis. 2. significant increases first appear at Taylor and Kollros state XX and coincide with the beginning of tail regression as determined by the tail wt body wt ration. 3. The results suggest a role of alanine aminopeptidase in the mechanism of tail resorption.