Circular dichroism of nucleic acid monomers. I. Calculated adenosine and 2′-deoxyadenosine CD spectra

A combination of the DeVoe and Kirkwood polarizability concepts is developed to calculate CD spectra of nucleic acid monomers. The method is perfectly general and applies to any system where the constituents have absorption properties which are widely separated in terms of frequency. The theory is applied to calculate the CD spectra of adenosine and 2′-deoxyadenosine conformers. Bond polarizabilities are evaluated for the ribosyl moiety of adenosine, as a function of glycosidic rotational angles and polarizability anisotropies. It is found that a wide range of C-C and C-O bond polarizabilities give similar CD results. Isotropic atom polarizabilities are also evaluated. It is found that the CD results using these polarizabilities do not differ significantly from those obtained with bond polarizabilities. The CD spectra of adenosine and 2′-deoxyadenosine are calculated for three x-ray diffraction determined geometries: A-form RNA, B-form DNA, and C-form DNA. The results indicate that the monomer CD spectra are strongly dependent on the precise geometry and appear to be of importance in understanding the spectra of oligomers and polymers. The deoxyadenosine conformers are found to have calculated CD spectra which are less intense than those of the ribosyl conformers. These results indicate that the measured differences between the CD magnitudes of ribo- and deoxyriboadenosine are due to the presence or absence of the 2′-hydroxyl. Weighted averaged adenosine CD spectra are calculated with the aid of probability distributions from conformational energy calculations. The results suggest a new method for obtaining empirical monomer parameters for use in optical calculations. The calculations in this paper indicate for the first time that DeVoe theory, in combination with the Kirkwood theory, provides a useful method for the calculation of the CD spectra of nonpolymeric molecules.     

Index to Authors,Volume 6

Abstract

The refractive indices of wet-spun films of CsDNA have been measured for light polarized parallel and perpendicular to the helical axis as a function of relative humidity (RH). These data have been combined with previously published data (Biopolymers 30 (1990) 877–887) for the volume per base pair and water content as a function of RH in order to extract the optical polarizabilities. This work was motivated by the study of Weidlich et al. (Biopolymers 26 (1987) 439–453) who reported a ～35% increase at the A-to-B transition in the parallel and perpendicular polarizabilities of NaDNA. In contrast, a much smaller increase in the polarizabilities of CsDNA is found near the A-to-B transition: ～ 12% for the perpendicular direction and < 4% for the parallel direction.     

Effects of airflow and changing humidity on the aerosolization of respirable fungal fragments and conidia of Botrytis cinerea

The purpose of this study was to investigate the aerosolization of particles (micro- and macroconidia and fragments) from Botrytis cinerea cultures in relation to potential human inhalation in indoor environments. The influence of the following factors on the aerosolization of B. cinerea particles was studied: exposure to airflow, relative humidity (rh), changing rh, and plant or building materials. The aerodynamic diameter (d(a)) and the respirable fraction of the aerosolized particles were determined. Conidia and fragments of B. cinerea were not aerosolized as a response to a decrease in the rh. In contrast, both micro- and macroconidia and fungal fragments were aerosolized when exposed to an airflow of 1.5 m s(-1) or 0.5 m s(-1). Significantly more particles of microconidial size and fragment size were aerosolized at a low rh (18 to 40% rh) than at a higher rh (60 to 80% rh) when cultures were exposed to airflow. The size of the respirable fraction of the aerosolized particles was dependent on the rh but not on the growth material. At high rh, about 30% of the aerosolized particles were of respirable size, while at low rh, about 70% were of respirable size. During low rh, more fungal (1→3)-β-d-glucan and chitinase were aerosolized than during high rh. In conclusion, exposure to external physical forces such as airflow is necessary for the aerosolization of particles from B. cinerea. The amount and size distribution are highly affected by the rh, and more particles of respirable sizes were aerosolized at low rh than at high rh.     

Electronic and optical properties of wet-spun films of Li- and Na-hyaluronate

The uv absorption of Na-hyaluronate (NaHA) films and the refractive indices, water content, and swelling of LiHA films have been measured as a function of relative humidity. Three peaks are observed in the uv absorption of NaHA (at about 250, 310, and 330 nm) for water content above 10 water molecules per disaccharide. The absorptivity of the 250, 310, and 330 nm peaks increase as the water content increases, indicating a change in the electronic properties of the HA molecule. The refractive indices, water content, and swelling of LiHA films are used to determine the optical polarizability via the Lorentz–Lorenz relation. The polarizability of LiHA is found to have a similar dependence on water content as NaHA, though the changes observed are larger in magnitude. © 1994 John Wiley & Sons, Inc.     

Study of hyaluronic acid flexibility by electric birefringence.

Transient-electric-birefringence experiments were conducted on four samples of hyaluronic acid over the molecular-mass (M) range 5 X 10(4)-4 X 10(6) in dilute aqueous solution. The geometrical, optical and electrical characteristics were monitored via the rotary relaxation times, optical-polarizability antisotropies and electrical polarizabilities respectively. Each indicates the molecular conformation to be consistent with some degree of rigidity at low M but that this does not persist at high M. The molecules do not become true random coils, but are best characterized in terms of a persistence length of 20 nm or 20 disaccharide units.     

The effect of relative humidity on osmoregulation in the squirrel monkey (Saimiri sciureus)

Osmoregulatory balance was studied in four young, tamed squirrel monkeys (Saimiri sciureus, Columbia) after acclimatization to relative humidities (rh) commonly used in laboratories (30% and 50%) and to higher humidities representative of the dry and wet seasons in their natural environment (75% and 95%). The temperature was constant at 25°C and the light-dark cycle was 12:12 hours. The animals were maintained in large metabolism cages and were free moving. Water consumption and urine flow rates increased at each higher humidity from 30% rh to 75% rh and then decreased at 95% rh (p<0.05). Fecal water loss was greater with higher humidity (p<0.05). Evaporative water loss remained relatively constant until a break between 75% and 95% rh, at which point it decreased dramatically (p<0.05). Expressed relative to total water intake, evaporative water loss demonstrated a progressive decrease with increasing humidity: 65%, 56%, 51%, and 42%, at 30%, 50%, 75%, and 95% rh. This indicates that as the humidity approaches maximum saturation, not only is the evaporative water loss component necessarily diminished, but also the apparent precipitation of alternate strategies of thermoregulation leads to a reduction in the overall water requirements of the animals. Potassium/sodium excretion ratios were relatively constant at 30%, 50%, and 95% rh but decreased significantly at 75% rh (p<0.05). As a reflection of adrenocorticosteroid activity, this suggests that at 25°C, 75% rh is an optimal humidity in the maintenance of squirrel monkeys. The significant osmoregulatory alteration occurring between 75% and 95% rh provides further evidence that relative humidity may be an important factor in the seasonal physiological cycles of the squirrel monkey. In conducting the research described in this report the investigators adhered to the “Guide for Laboratory Animal Facilities and Care,” as promulgated by the Committee on the Guide for Laboratory Animal National Academy of Sciences, National Research Council.     

Individualized model of human thermoregulation for the simulation of heat stress response.

A population-based dynamic model of human thermoregulation was expanded with control equations incorporating the individual person's characteristics (body surface area, mass, fat%, maximal O(2) uptake, acclimation). These affect both the passive (heat capacity, insulation) and active systems (sweating and skin blood flow function). Model parameters were estimated from literature data. Other data, collected for the study of individual differences (working at relative or absolute workloads in hot-dry [45 degrees C, 20% relative humidity (rh)], warm-humid [35 degrees C, 80% rh], and cool [21 degrees C, 50% rh] environments), were used for validation. The individualized model provides an improved prediction [mean core temperature error, -0.21 --> -0.07 degrees C (P < 0.001); mean squared error, 0.40 --> 0.16 degrees C, (P < 0.001)]. The magnitude of improvement varies substantially with the climate and work type. Relative to an empirical multiple-regression model derived from these specific data sets, the analytical simulation model has between 54 and 89% of its predictive power, except for the cool climate, in which this ratio is zero. In conclusion, individualization of the model allows improved prediction of heat strain, although a substantial error remains.     

Correlation between substituent constants and hyperpolarizabilities for di-substituted trans-azobenzenes

Nonlinear optical properties of a series of disubstituted trans-azobenzenes were studied. The structures were fully optimized by B3LYP/6-31+G* and both static polarizabilities and hyperpolarizabilities were then calculated by the derivative method. In order to show the relationships between dipole moments, (hyper)polarizabilities and the structures, three kinds of substituent constants were applied to correlate with both ground state dipole moment and hyperpolarizabilities. Both physical properties have a satisfactory correlation with substituent constants Σσ_+/? and bond length alternation. Overall, the electronic excitation contribution to the hyperpolarizabilities is rationalized in terms of the two-level model.     

Aerobic power as a factor in women's response to work in hot environments.

Twelve young women, athletes (n = 6) and nonathletes (n = 6), walked on a treadmill at loads equivalent to approximately 30% Vo2 max for two 50-min periods in three environments: 1) 28 degrees C, 45% rh, 2) 35 degrees C, 65% rh, and 3) 48 degrees C, 10% rh. There were no differences between groups in rectal temperature, heart rate, evaporative heat loss, or mean skin temperature at 28 or 35 degrees C or during the first work period in the 48 degrees C environment. However, a significantly lower cardiac output (Q) and stroke volume (SV) observed for nonathletes by the 46th min of work at 48 degrees C may explain why no nonathletes were able to complete a 2nd h of work while four of six athletes successfully finished the period. It appears that in conditions of severe heat stress (48 degrees C) athletes were able to maintain a cardiac output sufficient to meet the metabolic requirements and the large increase in peripheral blood flow for a longer period of time than nonathletes.     

Flagellar-phase variation: isolation of the rh1 gene.

In Salmonella, expression of flagellar antigen alternates between two serotypes (phases) encoded by two genes, H1 and H2. The mechanism which controls the alternative expression of the H1 and H2 genes was examined by cloning these genes and the genetic elements which control their activity on hybrid vehicles in Escherichia coli. H2 gene activity was shown to be controlled by a recombinational switch located adjacent to the H2 gene. Activity of the H1 gene is thought to be repressed, when the H2 gene is expressed, by the product of another gene, rh1 (repressor of H1), which is controlled coordinately with the H2 gene. In this report, we describe the construction of hybrid lambda vehicles which contain, in addition to the H2 gene, a genetic activity corresponding to rh1. Variation of flagellar antigens analogous to that observed in Salmonella was observed when E. Coli strains were transduced with the hybrid lambda. By using the lambdaH2rh1 hybrid to program protein synthesis in UV-irradiated cells, the synthesis of a polypeptide was correlated with rh1 gene product activity. We conclude that the H2 region consists of two cotranscribed genes, H2 and rh1. The expression of both gene products is regulated by the same recombinational event.     

The optical properties of Li- and Na-DNA films

We have measured the refractive indices of highly crystalline Li- and Na-DNA wet-spun films as a function of their water content using an immersion technique. We calculated the molecular polarizabilities of a DNA base pair using the Lorentz–Lorenz relation for anisotropic materials, the measured water contents, and densities corrected for void formation. For Li-DNA, the polarizabilities are independent of the relative humidity, whereas for Na-DNA, there are large changes at the A-B transition and also at low humidities. The average polarizability of A-Na-DNA is in agreement with that calculated from refractive index increments and also as calculated by a simple addition of bond polarizabilities, whereas the values for Li- and B-Na-DNA are about 30% larger than the calculated values. We propose that these anomalous values are due to nonlinear polarizabilities of the phosphate group.     

Hydration of sodium hyaluronate, NMR study of an oriented sample

A sample of highly oriented Na-hyaluronate was prepared with a wet--spinning method and equilibrated to 75% relative humidity. Its proton NMR spectrum was recorded as a function of the angle theta between the hyaluronate helix axis and the external magnetic field. It appeared as a singlet with an angle-dependent line width expressed by delta v o + A(1-3cos2 theta)2. This reveals a residual intramolecular dipolar interaction of anisotropically rotating water molecules. The merging of the expected doublet into a single line is assumed to be caused by proton exchange between water molecules. The result indicates a hydration similar to that of many other fibrous biopolymers at comparable relative humidities.     

Electronic structure and polarizabilities of some heterocycles: I. Hydroxypyrazoles and related systems

The (hyper)polarizabilities of different tautomer forms of hydroxypyrazoles and pyrazolones have been calculated by the finite-field procedure in the MNDO approximation and the sum of states formalism in the PPP approximation, with all singly- and doubly-excited electronic configurations in the CI method. It was shown that while in the ground electronic state the values of the (hyper) polarizabilities are not essentially different, in the first excited singlet Franck-Condon state an increase of the molecular polarizabilities of some tautomers is observed. This increase is attributed to a specific change in the electronic structure of the excited state, demonstrated by the localization of the electronic transition in the different pyrazolone tautomers. The electron-donor capabilities of phenyl-substituted hydroxypyrazoles and pyrazolones are discussed.     

Quadratic nonlinear optical susceptibility of helical polymers

The quadratic nonlinear optical susceptibility of a solution of helical polymers and of samples with helices oriented parallel to each other is calculated for regions of characteristic vibrations and of their overtones. The important role of electrooptical and of mechanical anharmonicity for exhibition of overtones in nonlinear spectroscopy is shown. The possibility of the appearance of the giant polarizabilities near bound overtone states is analyzed. The overtone spectrum of amide I is modeled numerically. © 1994 John Wiley & Sons, Inc.     

Intramolecular Enantiomerism in S(+)2,2‐dimethyl ‐1,3‐dioxolane‐4‐methanol: The Interpretation of Raman Optical Activity Intensity

A bond polarizability algorithm was developed and applied to interpret the Raman optical activity (ROA) intensity. It is demonstrated that for the chiral molecule such as S(+)2,2‐dimethyl‐1,3‐dioxolane‐4‐methanol there exists approximate (or symmetry breaking) mirror reflection that reverses the signs of the differential bond polarizabilities of the pair bond coordinates that are related to each other by the mirror reflection, just like that between the right and left enantiomers. The magnitude difference of the differential bond polarizabilities of the pair bond coordinates becomes smaller as they are farther away from the asymmetric atom. Hence, that the asymmetric atom (center) plays a central role in ROA is confirmed from a spectroscopic viewpoint. Meanwhile, the concept of intramolecular enantiomerism is proposed. Chirality 27:820–825, 2015. © 2015 Wiley Periodicals, Inc.     

Functionalization of Recombinant Amelogenin Nanospheres Allows Their Binding to Cellulose Materials

Protein engineering to functionalize the self‐assembling enamel matrix protein amelogenin with a cellulose binding domain (CBD) is used. The purpose is to examine the binding of the engineered protein, rh174CBD, to cellulose materials, and the possibility to immobilize self‐assembled amelogenin nanospheres on cellulose. rh174CBD assembled to nanospheres ≈35 nm in hydrodynamic diameter, very similar in size to wild type amelogenin (rh174). Uniform particles are formed at pH 10 for both rh174 and rh174CBD, but only rh174CBD nanospheres showes significant binding to cellulose (Avicel). Cellulose binding of rh174CBD is promoted when the protein is self‐assembled to nanospheres, compared to being in a monomeric form, suggesting a synergistic effect of the multiple CBDs on the nanospheres. The amount of bound rh174CBD nanospheres reached ≈15 mg/g Avicel, which corresponds to 4.2 to 6.3 × 10^?7 mole/m². By mixing rh174 and rh174CBD, and then inducing self‐assembly, composite nanospheres with a high degree of cellulose binding can be formed, despite a lower proportion of rh174CBD. This demonstrates that amelogenin variants like rh174 can be incorporated into the nanospheres, and still retain most of the binding to cellulose. Engineered amelogenin nanoparticles can thus be utilized to construct a range of new cellulose based hybrid materials, e.g. for wound treatment.     

Behavioural and physiological responses of infective juveniles of the entomopathogenic nematode Heterorhabditis to desiccation

Infective juveniles (IJs) of entomopathogenic nematodes (EPNs) are susceptible to a wide variety of environmental factors, including desiccation, which limit their usefulness as biocontrol agents. Although EPNs can be subjected to a gradual loss of water in their natural environment they are not full anhydrobiotes, being able to survive only moderate levels of desiccation at high relative humidities (rh). We investigated the desiccation tolerance of IJs of several Heterorhabditisspecies and strains when exposed to fast and slow desiccation regimes. We also investigated the behavioural and biochemical responses of Heterorhabditis IJs when exposed to 98% rh for 4 days. IJs of H. megidis UK211 (but not IJs of H. indica) aggregate into large clumps when desiccated at high rh, but unlike Steinernema spp., neither H. megidis nor H. indica IJs showed any tendency to coil. Preincubation of H. megidis UK211 IJs at high (98%) rh enhances their ability to survive for 150 min at 57% rh. We show that preincubation of H. megidis and H. indica at 98% rh induces the synthesis of glycerol but not of trehalose, whereas identical preincubation conditions do induce trehalose synthesis in Steinernema carpocapsae and Aphelenchus avenae. The biosynthesis of glycerol rather than trehalose by IJs of two species of Heterorhabditis in response to moderate levels of desiccation indicates that Heterorhabditis is unlikely to have the necessary metabolic responses to desiccation required to enable it to enter into a fully anhydrobiotic state.     

Untrained females: effects of submaximal exercise and heat on body fluids.

Five untrained females having no history of heat exposure worked in a cool (16-20 degrees C db, 28% rh) environment on day 1 and a warm environment on day 2 (45 degrees C db, 28% rh). Exercise level (bicycle ergometer) was 30% of individual Vo2 max values and work time on both days was 45 min. Venous blood samples were obtained at rest, after 40 min of exercise and 25 min after exercise ceased. Analysis of blood samples indicated an 8.3% increase in Hct during exercise on day 1 and a plasma volume reduction of 12.8% though total circulating protein increased 11.5%. Except for K+ all parameters approximated control values within 25 min postexercise. On day 2, exercise in heat caused a 12% increase in Hct and a plasma volume reduction of 17.7%. Mean total protein did not significantly change from resting values. These data indicated that for a given % Vo2 max, untrained females suffer considerably greater reductions in plasma volumes than do exercised males. Similar to males, dilatation of the cutaneous vascular bed in unacclimatized females resulted in loss of protein from the vascular volume.     

采用液质联用方法检测黄秋葵荚果黄酮类物质含量

该研究为了培育兼抗4种病毒的马铃薯品种,采用RT￣PCR技术对PVX、PVS、PVY和PLRV的外壳蛋白( CP )基因进行克隆与分析,获得了大小分别为670、800、700、600 bp的CP基因序列,将获得的CP基因序列与NCBI中已报道的序列进行比对分析,其同源性都在96％以上。根据所克隆的CP 基因对靶标片段进行筛选,获得了大小约300 bp的靶标片段PVX￣rh、PVS￣rh、PVY￣rh和PLRV￣rh,同时利用 Overlap￣PCR技术将4种病毒的靶标片段进行拼接,得到了长度约为1200 bp的融合片段XSYV￣rh,与预期目标片段XSYV￣yxz的相似性达100％。利用DNA重组技术将融合片段XSYV￣rh克隆到pGM￣T载体上构建成克隆载体pGM￣T￣XSYV￣rh,用SpeⅠ和SacⅠ对克隆载体pGM￣T￣XSYV￣rh和植物表达载体pART27进行同步双酶切,用T4 DNA连接酶将XSYV￣rh片段连接到载体pART27上,成功构建了同时含4种病毒CP 基因片段的植物表达载体pART27￣XSYV￣rh。采用直接转化法将植物表达载体导入根癌农杆菌LBA4404中,并利用农杆菌介导法对烟草品种T12试管苗进行遗传转化,转化后的烟草植株经PCR检测,有40株转化植株可扩增出目的条带,表明XSYV￣rh融合基因已成功转入烟草基因组中。