Dichroic ratio as the characteristic of the functional condition of the system

The principal deviation between parameters of spectral characteristics of surface structures and whole cells of unicellular algae Dunaliella tertiolecta and Tetraselmis viridis before and after influence of electromagnetic field (EMF) has been determined. It was found that the dichroic ratio can characterize the degree of adaptation of the culture to changing conditions of the environment.     

自养和兼养条件下蛋白核小球藻昼夜节律的响应

【目的】研究自养和兼养两种培养方式对蛋白核小球藻(Chlorella pyrenoidosa)生长、细胞分裂和生化组分积累的影响,探讨人工培养蛋白核小球藻的昼夜节律响应机制和优化技术。【方法】小球藻自养培养采用BG11培养基,兼养培养基在BG11培养基中添加4种不同浓度(1、5、10、20 g/L)的葡萄糖,培养周期为10 d。血球板计数法测定藻细胞浓度,干重法测定藻细胞生物量。显微观察藻细胞大小和分裂情况。脂染色法测定小球藻总脂的含量,藻细胞的叶绿素、蛋白和淀粉分别采用甲醇、氢氧化钠、硝酸钙浸提后通过紫外分光光度法定量测定。【结果】葡萄糖兼养培养对蛋白核小球藻具有显著的促生长效应,最适浓度为10 g/L。10 d收获时,兼养组(10 g/L葡萄糖)藻细胞浓度和干重分别是自养组的2.57倍和6.73倍。分析一昼夜中的藻细胞增殖规律可知,第2天和第5天时自养组中增殖的新生子细胞约有76.00%在黑暗期分裂产生,而兼养组中第2天和第5天光照期的新细胞增殖量占比分别达到40.90%和67.50%。一昼夜内藻细胞大小的迁移动态监测表明,第2天自养组藻细胞的体积变化静息期为8 h,兼养组只有4 h;第5天两组藻细胞大小迁移动态的昼夜节律明显,但兼养组黑暗结束后较大细胞(D6μm)占比显著高于自养组。第8天时,兼养组藻细胞已处于稳定期,总脂和蛋白含量均显著高于自养组,藻细胞总脂和色素含量在一昼夜中相对稳定,但蛋白和淀粉含量分别在光照8 h和12 h左右达到峰值。从第2天开始,对兼养组细胞每天进行2 h光延长,收获时藻细胞浓度和干重分别比对照组提高13%和11%。【结论】葡萄糖兼养培养能大幅提高蛋白核小球藻的生物量。蛋白核小球藻生长增殖与生化组分积累均受昼夜节律调控,自养条件下藻细胞以光照期生长黑暗期增殖为主。兼养培养提高藻细胞生物量的机制在于缩短藻细胞生长静息期,在昼夜节律中加速藻细胞生长并显著提高通过细胞周期检查点的细胞比例,光照期效应尤其明显。藻细胞蛋白和淀粉含量昼夜节律明显,最佳收获时间分别在光照8 h和12 h后。     

Ectomycorrhizal fungi associated with two species of Kobresia in an alpine meadow in the eastern Himalaya

The diversity of ectomycorrhizal fungi (EMF) on Kobresia filicina and Kobresia capillifolia in an alpine meadow in China’s southwestern mountains, one of the word’s hotspots of biodiversity, was estimated based on internal transcribed spacer rDNA sequence analysis of root tips. Seventy EMF operational taxonomical units (OTUs) were found in the two plant species. Dauciform roots with EMF were detected in species of Kobresia for the first time. OTU richness of EMF was high in Tomentella/Thelophora and Inocybe, followed by Cortinarius, Sebacina, the Cenococcum geophilum complex, and Russula. Tomentella/Thelophora and Inocybe were general and dominant mycobiont genera of the two sedges. Besides the C. geophilum complex, the ascomycete components Hymenoscyphus and Lachnum were also detected on the two plants. Alpine plants in different geographical regions share similar main genera and/or families of EMF while harboring predominantly different mycobiont species; most of the members detected by us have not been found elsewhere. Significant differences in the profile of EMF occurrences were not found between the two plant species and among the three sampling seasons in our sample size.     

Effects of prenatal exposure to a 900 MHz electromagnetic field on 60-day-old rat testis and epididymal sperm quality

We investigated the effects of exposure in utero to a 900 megahertz (MHz) electromagnetic field (EMF) on 60-day-old rat testis and epididymis. Pregnant rats were divided into control (CG; no treatment) and EMF (EMFG) groups. The EMFG was exposed to 900 MHz EMF for 1 h each day during days 13 ? 21 of pregnancy. Newborn rats were either newborn CG (NCG) or newborn EMF groups (NEMFG). On postnatal day 60, a testis and epididymis were removed from each animal. Epididymal semen quality, and lipid and DNA oxidation levels, apoptotic index and histopathological damage to the testis were compared. We found a higher apoptotic index, greater DNA oxidation levels and lower sperm motility and vitality in the NEMFG compared to controls. Immature germ cells in the seminiferous tubule lumen, and altered seminiferous tubule epithelium and seminiferous tubule structure also were observed in hematoxylin and eosin stained sections of NEMFG testis. Nuclear changes that indicated apoptosis were identified in TUNEL stained sections and large numbers of apoptotic cells were observed in most of the seminiferous tubule epithelium in the NEMFG. Sixty-day-old rat testes exposed to 900 MHz EMF exhibited altered sperm quality and biochemical characteristics.     

Composition and biosynthesis of thylakoid membrane polypeptides in the red alga Cyanidium caldarium: Comparison with the thylakoid polypeptide composition of higher plants and cyanobacteria

The polypeptide composition of thylakoid membranes of the red alga Cyanidium caldarium was studied by PAGE in the presence of lithium dodecyl sulfate. The thylakoid membranes were shown to contain 65 polypeptides with mol wt from 110 to 10 kDa. PS I isolated from C. caldarium cells is composed of at least 5 components, one of which is the chlorophyll-protein complex with mol wt of 110 kDa typical of higher plants. Cyt f, c ₅₅₂, b ₆ and b ₅₅₉ were identified. Inhibition of carotenoid biosynthesis with norflurazon caused no changes in the polypeptide composition of thylakoid membranes of the algae grown in dark. The suppression of the biosynthesis rate of some thylakoid polypeptides in the algae grown with norflurazon in light is a result of membrane photodestruction. Thylakoid membranes from C. caldarium cells are more similar in the number of protein components to thylakoid membranes from cells of the cyanobacterium Anacystis nidulans than to those of higher plants (Pisum sativum), which was proved by immune-blotting assays: Thylakoid membranes of the red alga and cyanobacteria contain 28 homologous polypeptides, while thylakoid membranes of the alga and pea, only 15.Abbreviations CD circular dichroism - CP chlorophyll-protein complex - LDS lithium dodecyl sulfate - NF norflurazon     

The effect of electromagnetic field exposure on the formation of DNA lesions

Abstract

In an attempt to determine whether electromagnetic field (EMF) exposure might lead to DNA damage, we exposed SnCl₂-treated pBR322 plasmids to EMF and analysed the resulting conformational changes using agarose gel electrophoresis. An EMF-dependent potentiation of DNA scission (i.e. the appearance of relaxed plasmids) was observed. In confirmation of this, plasmids pre-exposed to EMF also were less capable of transforming Escherichia coli. The results indicate that EMF, in the presence of a transition metal, is capable of causing DNA damage. These observations support the idea that EMF, probably through secondary generation of reactive oxygen species, can be clastogenic and provide a possible explanation for the observed correlation between EMF exposure and the frequency of certain types of cancers in humans.     

In Vitro Evaluation of the Effects of Electromagnetic Fields used for Bone Healing

The use of therapeutic electromagnetic fields (EMF) for bone healing has positive clinical effects but may have adverse biologic effects. For this reason, EMF exposure has been repeatedly investigated to exclude the possibility of genotoxic effects and tumour risk. This paper describes the effects of EMFs on cell cultures. We analyzed the effects of EMF (28 gauss, 75 Hz) on growth and metabolic activities in four different cell types: L929 fibro-blasts, osteoblast-like HOS/TE85 cells, human lymphocytes, and rabbit chondrocytes. We found no cytotoxic or mutagenic effects on cultures exposed to EMF compared with unexposed controls. Results of cell proliferation showed a statistically significant increase for all cultures exposed to EMF with respect to controls (L929 +45%, p = 0.002; HOS/TE85 +32%, p = 0.001; chondrocytes +40%, p = 0.0003; lymphocytes +39%, p = 0.0002). Biochemical and enzymatic tests gave different results, depending on cell types: all tested values were increased after EMF exposure, even if only some of them reached statistical significance (total proteins: HOS/TE85 p = 0.004, chondrocytes p = 0.003; alkaline phosphatase: L929p = 0.0003, HOS/RE85 p = 0.0001, chondrocytes p = 0.009, lymphocytes p = 0.006; lactate dehydrogenase: chondrocytes p = 0.0002, lymphocytes p = 0.0005). Biochemical and enzymatic tests and cell proliferation results suggest a more active metabolism in cartilage and bone cells after EMF exposure. These effects could be relevant for bone healing in clinical practice.     

Effects of low frequency electromagnetic field on proliferation of human epidermal stem cells: An in vitro study

To investigate the effects of low frequency electromagnetic fields (EMF) on the proliferation of epidermal stem cells, human epidermal stem cells (hESC) were isolated, expanded ex vivo, and then exposed to a low frequency EMF. The test and control cells were placed under the same environment. The test cells were exposed for 30 min/day to a 5 mT low frequency EMF at 1, 10, and 50 Hz for 3, 5, or 7 days. The effects of low frequency EMF on cell proliferation, cell cycle, and cell‐surface antigen phenotype were investigated. Low frequency EMF significantly enhanced the proliferation of hESC in the culture medium in a frequency‐dependent manner, with the highest cell proliferation rate at 50 Hz (P < 0.05). Exposure to a low frequency EMF significantly increased the percentage of cells at the S phase of the cell cycle, coupled with a decrease in the percentage of cells in the G1 phase (P < 0.05) but the effect was not frequency dependent. The percentage of CD29⁺/CD71^? cells remained unchanged in the low frequency EMF‐exposed hESC. The results suggested that low frequency EMF influenced hESC proliferation in vitro, and this effect was related to the increased proportion of cells at the S phase. Bioelectromagnetics 34:74–80, 2013. © 2012 Wiley Periodicals, Inc.     

Studies on the seasonal biochemistry of the Northern krillMeganyctiphanes norvegica in the Kattegat

A well defined pelagic population of the Northern krill,Meganyctiphanes norvegica was sampled annually at a specific location in the Skandinavian Kattegat, and the major biochemical components were measured. Protein and lipid were the main constituents and underwent the most pronounced seasonal changes, clearly correlated to the prevailing supply of food organisms. The amount of lipid increased to a maximum of 48% of the dry weight towards winter, out of phase with gonad maturation, and therefore interpretable as deposition of overwintering reserves. Utilisation of stored reserves proceeds over winter, with loss of lipid, and decrease in weight but not in length. Comparison with literature data showed similarities with other krill populations from different geographical locations. The biochemical components ofEuphausia superba, the key organism of the marine Antarctic ecosystem, resembled those ofM. norvegica. Special polar adaptations are not obviously expressed in the proximate biochemical composition.     

Isolation and characterization of a marine algicidal bacterium against the harmful raphidophyceae <Emphasis Type="Italic">Chattonella marina</Emphasis>

A bacterial strain named AB-4 showing algicidal activity against Chattonella marina was isolated from coastal water of ULjin, Republic of Korea. The isolated strain was identified as Bacillus sp. by culture morphology, biochemical reactions, and homology research based on 16S rDNA. The bacterial culture led to the lysis of algal cells, suggesting that the isolated strain produced a latent algal-lytic compound. Amongst changes in algicidal activity by different culture filtrate volumes, the 10% (100 μl/ml) concentration showed the biggest change in algicidal activity; there, estimated algicidal activity was 95%. The swimming movements of Chattonella marina cells were inhibited because of treatment of the bacterial culture; subsequently, Chattonella marina cells became swollen and rounded. With longer exposure time, algal cells were disrupted and cellular components lost their integrity and decomposed. The released algicide(s) were heat-tolerant and stable in pH variations, except pH 3, 4, and 5. Culture filtrate of Bacillus sp. AB-4 was toxic against harmful algae bloom (HAB) species and nontoxic against livefood organisms. Bacillus sp. AB-4 showed comparatively strong activity against Akashiwo sanguinea, Fibriocapsa japonica, Heterosigma akashiwo, and Scrippsiella trochoidea. These results suggest that the algicidal activity of Bacillus sp. AB-4 is potentially useful for controlling outbreaks of Chattonella marina.     

FTIR and UV spectroscopy in real-time monitoring of S. cerevisiae cell culture

A combination of FTIR and UV spectroscopy is proposed as a novel technique for integrated real-time monitoring of metabolic activity and growth rates of cell cultures, required for systematic studies of cellular low-frequency (LF) electric and magnetic field (EMF) effects. As an example, we investigated simultaneous influence of periodic LF 3D EMFs on a culture of Saccharomyces cerevisiae (baker's yeast) cells. Amplitudes, frequencies and phases of the field components were the variable parameters. Electromagnetic fields were found to efficiently control the activity of the yeast cells, with the resulting CO₂ production rates, as monitored by FTIR spectroscopy, varying by at least one order of magnitude due to the field action. Additionally, population dynamics of the yeast cells was monitored by UV absorption of the yeast culture at λ_prob = 320 nm, and compared to the CO₂ production rates. The detected physiologically active frequencies are all below 1 kHz, namely, 800 Hz excitation was effective in reducing the metabolic rates and arresting cell proliferation, whereas 200 Hz excitation was active in accelerating both cell proliferation and overall metabolic rates. The proposed methods produce objective, reliable and quantitative real-time results within minutes and may be used in various tasks that could benefit from a rapid feedback they provide in the form of metabolic and growth rates. Amplitude and frequency dependences of the LF EMF effects from individual field components with different polarizations were recorded and qualitatively interpreted based on a simple model, describing ion diffusion through a membrane channel.     

LIGHT AND NUTRIENT LIMITATION OF SEA-ICE MICROALGAE (HUDSON BAY,CANADIAN ARCTIC)1

Changes in the biochemical composition of sea-ice microalgae (southeastern Hudson Bay, Canadian Arctic) were used to assess the light and nutrient status of cells growing at the ire-water interface. These changes allowed us to test the hypothesis that ire algae are limited by light at the beginning of their growth season and become periodically limited by nutrients as the season progresses. During the vernal growth season, three patterns of variation in cellular components were found in response to changes in environmental conditions. 1) Chlorophylls a and c, ATP, carbohydrate, and carbon followed the seasonal increase in under-ice irradiance, which was mainly mused by melting of the snow cover. 2) Dissolved and biogenic silicon underwent periodic variations, which were coupled to the fortnightly neap-spring cycle of tidal mixing. 3) Cellular contents of free amino acids, protein, and total nitrogen remained relatively constant during the season. An early decrease in intracellular chlorophylls a and c suggests that ire algae did respond to small changes in solar irradiance by changing the pigment composition of their photosynthetic units. Seasonal increases in ATP, carbohydrate, and total carbon indicate light limitation in April, followed in May by a period of excess irradiance and/or nutrients in short supply. The seasonal increase in ATP and the high values of the ratio free amino acids: protein show that neither phosphorus nor nitrogen limited algal growth at the ire-water interface. In May, higher values of carbohydrate: protein, carbon: nitrogen, carbon: chlorophyll a, and also carbon: silicon and ATP: silicon indicate that the ice algae became silicon-deficient in their natural environment. Following a period of light limitation, at the beginning of the season, ice-algal growth became silicon-limited, when in situ irradiance and the accumulated algal biomass were high and the tidally-driven nutrient supply was not strong enough to satisfy algal nutrient requirements.     

Extremely low‐frequency electromagnetic fields affect the immune response of monocyte‐derived macrophages to pathogens

This study aimed to determine the effect of extremely low‐frequency electromagnetic fields (ELF‐EMF) on the physiological response of phagocytes to an infectious agent. THP‐1 cells (human monocytic leukemia cell line) were cultured and 50 Hz, 1 mT EMF was applied for 4–6 h to cells induced with Staphylococcus aureus or interferon gamma/lipopolysaccharide (IFγ/LPS). Alterations in nitric oxide (NO), inducible nitric oxide synthase (iNOS) levels, heat shock protein 70 levels (hsp70), cGMP levels, caspase‐9 activation, and the growth rate of S. aureus were determined. The growth curve of exposed bacteria was lower than the control. Field application increased NO levels. The increase was more prominent for S. aureus‐induced cells and appeared earlier than the increase in cells without field application. However, a slight decrease was observed in iNOS levels. Increased cGMP levels in response to field application were closely correlated with increased NO levels. ELF‐EMF alone caused increased hsp70 levels in a time‐dependent manner. When cells were induced with S. aureus or IFγ/LPS, field application produced higher levels of hsp70. ELF‐EMF suppressed caspase‐9 activation by a small extent. These data confirm that ELF‐EMF affects bacterial growth and the response of the immune system to bacterial challenges, suggesting that ELF‐EMF could be exploited for beneficial uses. Bioelectromagnetics 31:603–612, 2010. © 2010 Wiley‐Liss, Inc.     

Antimicrobial effects of Cellvibrio on blue-green algae

Summary The culture fluids from two Cellvibrio strains, in the stationary phase of growth, are shown to contain heat-resistant, low molecular weight substances with antibiotic-like effects on blue-green algae. Morphological changes and lysis of cells were observed in various species of blue-green algae; ultrastructural changes were noted in the cell walls of growing vegetative cells of Anabaena inaequalis. The viability of resting cells, including heterocysts and akinetes was not affected.     

Far‐red dependent changes in the chemical composition of Spirulina platensis

The influence of far‐red light (FRL) was studied on the chemical composition of Spirulina platensis biomass. The following light compositions were used during the culture white light, blue‐red LED light (BRL) and BRL supplemented with FRL (BRFRL). Chlorophyll and phenol contents were measured by spectrophotometric methods, whereas presence of carotenoids, lipids, and phycobiliproteins were estimated by Fourier‐transform Raman spectrometry. Additionally, phenol content was investigated by fluorescence intensity of algae culture in the range of 430–650 nm. The content of chlorophyll and phenols in algae cells depended on the spectral composition of light and was the highest under BRL (16.7 ± 0.5 and 9.1 ± 0.6, respectively). It was shown that there is a positive linear correlation (R = 0.902 at p < 0.0000001) between the ratio of relative fluorescence intensity of S. platensis suspensions at 450 nm to the suspensions at 540 nm (F450/F540) and the content of phenolic compounds in the biomass. Changes in the F450/F540 ratio can explain approximately 80% changes of phenol contents in algae cells. Spirulina platensis Raman spectra demonstrated that the biomass of algae growing under white light and BRL had a significantly higher intensity of phycobiliprotein bands than the algae growing under BRFRL.     

Activity of salicylic acid on the growth and biochemism of Chlorella vulgaris Beijerinck

This study was conducted to investigate the influence of salicylic acid (SA) on the growth and changes of nucleic acids, protein, photosynthetic pigments, sugar content and photosynthesis levels in the green alga Chlorella vulgaris Beijerinck (Chlorophyceae). The most significant changes in the content of nucleic acids and proteins was observed at the concentration 10⁻⁴ M SA between 8 and 12 day of cultivation. This concentration of SA increased the number of cells (about 40 %) and content of proteins (about 60 %) and its secretion to the medium. The slight stimulation of protein secretion occurred on the 12th day of cultivation at concentration 10⁻⁴ M, while in the range of 10⁻⁵ M to 10⁻⁶ M the protein secretion was inhibited. SA also stimulated the content of nucleic acids, especially RNA by 20–60 %, compared with the control. The most stimulating influence upon the contents of chlorophylls a and b (50–70 %), total carotenoids (25–57 %), sugar (27–41 %) and intensity of net photosynthesis (18–33 %) was found at 10⁻⁴ M of SA. At the concentration of 10⁻⁶ M SA the slight inhibition of growth and biochemical activity of the algae was recorded at the first days of cultivation.     

Cell wall and cell growth characteristics of giant‐celled algae

Because of their large sizes and simple shapes, giant‐celled algae have been used to study how the structural and mechanical properties of cell walls influence cell growth. Here we review known relationships between cell wall and cell growth properties that are characteristic of three representative taxa of giant‐celled algae, namely, Valonia ventricosa, internodal cells of characean algae, and Vaucheria frigida. Tip‐growing cells of the genus Vaucheria differ from cells undergoing diffuse growth in V. ventricosa and characean algae in terms of their basic architectures (non‐lamellate vs. multilamellate) and their dependence upon pH and Ca²⁺ for cell wall extensibility. To further understand the mechanisms controlling cell growth by cell walls, comparative analyses of cell wall structures and/or associated growth modes will be useful. The giant‐celled algae potentially serve as good models for such investigations because of their wide variety of developmental processes and cell shapes exhibited.     

The differentiation of normal and transformed human fibroblasts in vitro is influenced by electromagnetic fields

We studied the effect of symmetric, biphasic sinusoidal electromagnetic fields (EMF) (20 Hz, 6 mT) on the differentiation of normal human skin fibroblasts (HH-8), normal human lung fibroblasts (WI38), and SV40-transformed human lung fibroblasts (WI38SV40) in in vitro cultures. Cells were exposed up to 21 days for 2 × 6 h per day to EMF. Normal mitotic human skin and lung fibroblasts could be induced to differentiate into postmitotic cells upon exposure to EMF. Concomitantly, the synthesis of total collagen as well as total cellular protein increased significantly by a factor of 5–13 in EMF-induced postmitotic cells. As analyzed by two-dimensional gel electrophoresis of [³⁵S]methionine-labeled polypeptides, EMF-induced postmitotic cells express the same differentiation-dependent and cell type-specific marker proteins as their spontaneously arising counterparts. In SV40-transformed human lung fibroblasts (cell line WI38SV40) the exposure to EMF induced the differentiation of mitotic WI38SV40 cells into postmitotic and degenerating cells in subpopulations of WI38SV40 cell cultures. Other subpopulations of WI38SV40 cells did not show any effect of EMF on cell proliferation and differentiation. These results indicate that long-term EMF exposure of fibroblasts in vitro induces the differentiation of mitotic to postmitotic cells that are characterized by differentiation-specific proteins and differentiation-dependent enhanced metabolic activities.     

Weak diurnal changes in the biochemical properties and benthic macrofauna of urbanised mangrove forests and mudflats

Diurnal changes in the biochemical properties and the benthic macrofaunal assemblage of sediments in urbanised mangrove forests and their adjacent mudflats in Sydney Harbour were investigated. Behavioural and physiological changes in the microphytobenthos between day and night were predicted to cause diurnal changes in the micro-scale depth distribution of chlorophylls a and b and colloidal carbohydrate. In addition, because macrofauna can alter sediment properties, diurnal changes in the macrofaunal assemblages were investigated. The microphytobenthos at the study sites were predominantly filamentous green algae, although diatoms were present. Samples for biochemical analysis were collected from the top 2 mm of sediment using mini-cryolanders, during low tide in the day and at night. Three biochemical properties of the sediments were measured spectrophotometrically: chlorophylls a and b (surrogate for microphytobenthos biomass) and colloidal carbohydrate. The amount of chlorophylls tended to be less at night than during the day, but site to site variability was large and these differences were generally small and not significant. Depth profiles indicated that there was some redistribution of pigments in the surface 2 mm between day and night, possibly due to migration of microphytobenthos or physiological changes. There was no significant difference in chlorophylls between the mangrove forest and adjacent mudflat, with the exception of chlorophyll b at one sampling time, which was larger in the mangrove forest than on the mudflat. Colloidal carbohydrate was significantly larger in the mangrove forest and significantly less on the mudflat during the day at one site at one time, but otherwise showed no significant differences between day and night or between the mangrove forest and mudflat. Whilst there were some differences in the benthic macrofaunal assemblages between day and night, these differences were only significant for spionids and polychaetes at one time. There were, however, significant differences in assemblages of benthic macrofauna between the mangrove forest and mudflat, probably due to structural differences between these habitats such as the presence of pneumatophores, shade and leaf litter. In summary, there was some minor diurnal variation in the measured biochemical properties of the sediment, but not in the macrofaunal assemblage. Diurnal changes should, therefore, be considered when investigating biochemical properties in these habitats, but they are not a major influence. These findings contrast to previous studies on diatom dominated mudflats in Europe, where stronger diurnal changes in biochemical properties were found. Diurnal changes in the macrofauna assemblages were largely insignificant and therefore could not explain the changes in the biochemical properties. Diurnal effects on the macrofauna in these habitats are more likely to be via altered behaviours and this requires further investigation.