Lw Values Research Articles

PS-B07-3: ANGIOTENSIN I CONVERTING ENZYME INHIBITORY PEPTIDES DERIVED FROM KATSUOBUSHI

Purpose: Antihypertensive components are typically assessed by screening based on in vitro results; however, since intestinal absorption is closely involved in the antihypertensive mechanism of action, we attempted to analyze the absorption of bonito derived peptides, which have been found to have antihypertensive effects in animal experiments. Methods: The intestinal tracts of rats, 7 week old male SDrats, were excised after performing cervical dislocation. Incisions 5.5 cm were quickly made into the jejunum, one side was ligated and inverted, and after injecting 1 mL reaction solution, the other side was ligated to create an inverted sack. The sack was then quickly placed in 30 mL of the reaction solution, antihypertensive amount: KBP 0.3 mg/per animal and synthetic peptides: each 0.25 mM, and left to react for 30 min at 37°C after which the inverted sack was removed and washed gently with physiological saline before recovering all the internal fluid. Liquid chromatography tandem mass spectrometry LC/MS/MS was used for analysis and the intestinal fluid samples were measured after examining pretreatment and measurement conditions. Results: Pretreatment conditions involved adding 5 μL water, 5 μL IS L-Leu-D-Leu, and 5 μL of 20% sulfosalicylic acid to a 50 μL intestinal fluid sample, stirring the sample, transferring 0.22 μm to a centrifugal filter, performing centrifugation for 3 min at 20000 g and 4°C and then injecting the filtrate into the LC/MS/MS system. LC conditions included a 1.7 μL ACQUITY UPLC BEH C18 column; 2.1, 50 mM, 0%-100% acetonitrile/0.1% TFA linear gradient elution in the mobile phase. Based on the above analysis conditions, the GW, AW, VW, MW, IW, LW, and WL values ng/mL of KBP in the reaction solution were 34.0, 4.64, 7.11, 1.28, 12.7, 4.57, and 0.923, respectively, and 53.2, 3.92, 6.02, 1.10, 8.76, 5.76, and 0.785, respectively. Values for the reaction solution of additive-free peptides serving as a base were estimated at 13.5, 1.09, 2.06,0.350, 5.54, 1.72, and 0.189, respectively. The calibration curve range was set at 0.200–1000ng/ mL. Conclusion: The intestinal membrane permeability of dried bonito-derived dipeptides, which have an antihypertensive effect in vivo, suggests that dipeptides absorbed from the intestinal membrane may have an antihypertensive effect.

Mössbauer spectroscopy and other structural properties of some V2O5.SrO.FeO glasses

ABSTRACT A series of (80-x)%V2O5·(x)%SrO·20%FeO glasses with 0 ≤ x ≤ 40 mole are prepared. The XRD proved the amorphous network of the glasses. Some isolated V = O vanadyl groups and some V–O–V bonds are broken by the Sr ions to form V–O–Sr bridges. A continuous increase in the Tg, Tc, Tm with increasing the mol%SrO is observed . High QS, IS and LW values are detected by Mössbauer spectroscopy. Most iron ions in the samples 0 and 5 mol% SrO appeared in paramagnetic glassy phase. All the iron ions in the glasses containing from 10 to 40 mole% SrO are dissolved in glass network. An increase in the density from 3.2 to 4.2 g.cm3 with a continuous decrease in the molar volume are found with increasing the SrO%. Molar polarisability, molar refractive index in addition to some structural and optical properties are calculated and discussed.

A study on vehicle Noise Emission Modelling: Correlation with air pollutant emissions, impact of kinematic variables and critical hotspots

This work proposes a methodology suitable for analysing the sound power levels (Lw), and carbon dioxide (CO2) and nitrogen oxides (NOx) emissions along a travel, and consequentially assessing the related critical hotspots. The estimation of noise and pollutant emissions from six vehicles driven along three different routes (one National Road and two highways) was conducted, in combined way, through seven Noise Emissions Models (NEMs) and Vehicle Specific Power (VSP) methodology, respectively. The inputs required by the models (namely, vehicle speed and acceleration and road grade) were extrapolated from On-Board Diagnostic (OBD) system and Global Positioning System (GPS) data recorded during monitoring campaigns. The specificities of each model were analysed, and the role played by the kinematic variables in noise and exhaust emissions assessment was highlighted. Results show that all the tested NEMs estimated higher noise levels on the highways, while VSP predicted higher emissions on the National Road. This happens because speed is the main input variable in NEMs, while acceleration has an impact on noise estimation in the low-speed range (below 50 km/h). For pollutant emissions evaluation, acceleration plays a fundamental role also at high-speed range, where a transition from a cruising condition to an acceleration phase leads to significant variations in terms of VSP values. Lw values, estimated with NEMs that use acceleration correction terms, present positive moderate-to-high correlation with VSP ones. Moreover, the models that neglect acceleration in noise estimation fail to recognize traffic control treatments as critical hotspots.

Modeling of the Leaf Area of <i>Maytenus obtusifolia</i> Mart. from Scanned Images

The leaf has a vital role in the functions of the plant, being responsible for photosynthesis and gas exchange. Thus, the objective of this study was to fit a mathematical equation model to estimate the leaf area of Maytenus obtusifolia Mart. through the linear dimensions of the leaves. For that, six hundred and fifteen healthy leaves were collected from plants belonging to the Federal University of Espirito Santo, Sao Mateus Campus, in the municipality of Sao Mateus, located in the north of the State of Espirito Santo, Brazil. All leaves were digitized and the images processed using the ImageJ® software, obtaining the measurements of the maximum length of the main midrib (L), the maximum width of the leaf blade (W) and the real leaf area (RLA) of each sheet. Subsequently, the product of length and width multiplication (LW) was also obtained. 500 sheets were randomly separated for the generation of models of mathematical equations and their respective coefficient of determination (R2), where RLA was used as dependent variable as function of L, W or LW as independent variable. Based on the models generated, a 115 leaf sample was used for validation, where the L, W and LW values of this sample were replaced in the adjusted equations, thus obtaining the estimated leaf area (ELA). A comparison of the means of RLA and ELA was performed by Student’s t test at 5% probability. We also calculated the mean absolute error (MAE), the root mean square error (RMSE) and the Willmott index (d). The best equation was defined by the following criteria: non-significant values of RLA and ELA averages, R2 and index d closest to unit, and MAE and RMSE values with greater proximity to zero. The quadratic model equation represented by ELA=0.18122798+0.72847767(LW)+0.00002789(LW)2 generated by multiplying the length with the width (LW) is the most suitable for the estimation of the leaf area of Maytenus obtusifolia Mart., in a fast, safe and non-destructive way.

Yerleşim Sıklığının Pekin Ördeklerinin Gelişme Performansına Etkileri

The experiment was designed to investigate the effects of actual stocking density on the growth performance parameters in Pekin ducks. A total of 240 ducklings were used with stocking densities of 3, 5 and 7 poults m-2 during the 42 day growing period. Live Weight, Live Weight Gain, Feed Consumption, Feed Conversion Ratio, Mortality Rate and Productivity Index parameters were investigated to determine growth performance. As the stocking density decreases, LW values were found to be increasing visibly after 3 weeks of age (P<0.05), Live Weight Gain and Total Live Weight values were found to be increasing after first week (P<0.05). The achieved total live weight in unit area increases parallel to increasing stocking density catching the peak at 7 ducklings m-2 stocking density (P<0.05). Stocking density was found to be affecting Feed Conversion values and from first week of age, Feed Conversion was found to be increasing by declining stocking density (P<0.05). Therewithal, Feed Conversion Ratio was found to be increasing with declining stocking density till the third week of age (P<0.05) but, hereafter this effect was disappeared (P>0.05). Mortality occurred in the trial was found not to be affected by Stocking Density (P>0.05), whereas by declining Stocking Density, Productivity Index was found to be increasing however in parallel Live Weight per unit area was also found to be decreasing together (P<0.05). When a general revision is made from the research, increasing Stocking Density has a positive effect on performance parameters of Pekin ducks except Total Live Weight per unit area.

Derivation of Calibration Coefficients for OCM-2 Sensor for Coastal Waters

The radiometric calibration coefficients that are required to enhance the preflight calibration coefficients to improve the performance of the Ocean Colour Monitor (OCM-2) onboard the Indian Remote Sensing Satellite (IRS) are determined using in-situ measurements in coastal waters around southern India. These coefficients were applied to OCM-2 data acquired over coastal waters off Point Calimere (Palk Strait) and Gulf of Mannar of the Bay of Bengal, and are compared with similar coefficients included in the SeaDAS software and those provided by the Space Application Centre (SAC). Two atmospheric correction algorithms were used in conjunction with these coefficients to obtain the water-leaving radiances (Lw) from OCM-2 data, namely the CAAS algorithm and SeaDAS algorithm. An evaluation of the results of these coefficients and atmospheric correction algorithms showed large deviations in Lw values derived with the SAC (positive deviation) coefficients and SeaDAS (negative deviation) coefficients when applied to OCM-2 data along with the SeaDAS atmospheric correction algorithm. The deviations were less remarkable with new coefficients when the same (SeaDAS) atmospheric correction algorithm was used. However, application all three coefficients to OCM-2 using the CAAS algorithm showed a similar trend but with less deviations with respect to in-situ Lw data. The results obtained with the new coefficients showed good agreement with the in-situ water-leaving radiances (except channels 412-443nm). These results suggest that the new calibration coefficients can be used along with the CAAS atmospheric correction algorithm to improve the performance of OCM-2 sensor for quantitative assessments of the various water constituents in coastal waters (including bloom) around India.

Observational Characterization of the Downward Atmospheric Longwave Radiation at the Surface in the City of São Paulo

Abstract This work describes the seasonal and diurnal variations of downward longwave atmospheric irradiance (LW) at the surface in São Paulo, Brazil, using 5-min-averaged values of LW, air temperature, relative humidity, and solar radiation observed continuously and simultaneously from 1997 to 2006 on a micrometeorological platform, located at the top of a 4-story building. An objective procedure, including 2-step filtering and dome emission effect correction, was used to evaluate the quality of the 9-yr-long LW dataset. The comparison between LW values observed and yielded by the Surface Radiation Budget project shows spatial and temporal agreement, indicating that monthly and annual average values of LW observed in one point of São Paulo can be used as representative of the entire metropolitan region of São Paulo. The maximum monthly averaged value of the LW is observed during summer (389 ± 14 W m−2; January), and the minimum is observed during winter (332 ± 12 W m−2; July). The effective emissivity follows the LW and shows a maximum in summer (0.907 ± 0.032; January) and a minimum in winter (0.818 ± 0.029; June). The mean cloud effect, identified objectively by comparing the monthly averaged values of the LW during clear-sky days and all-sky conditions, intensified the monthly average LW by about 32.0 ± 3.5 W m−2 and the atmospheric effective emissivity by about 0.088 ± 0.024. In August, the driest month of the year in São Paulo, the diurnal evolution of the LW shows a minimum (325 ± 11 W m−2) at 0900 LT and a maximum (345 ± 12 W m−2) at 1800 LT, which lags behind (by 4 h) the maximum diurnal variation of the screen temperature. The diurnal evolution of effective emissivity shows a minimum (0.781 ± 0.027) during daytime and a maximum (0.842 ± 0.030) during nighttime. The diurnal evolution of all-sky condition and clear-sky day differences in the effective emissivity remain relatively constant (7% ± 1%), indicating that clouds do not change the emissivity diurnal pattern. The relationship between effective emissivity and screen air temperature and between effective emissivity and water vapor is complex. During the night, when the planetary boundary layer is shallower, the effective emissivity can be estimated by screen parameters. During the day, the relationship between effective emissivity and screen parameters varies from place to place and depends on the planetary boundary layer process. Because the empirical expressions do not contain enough information about the diurnal variation of the vertical stratification of air temperature and moisture in São Paulo, they are likely to fail in reproducing the diurnal variation of the surface emissivity. The most accurate way to estimate the LW for clear-sky conditions in São Paulo is to use an expression derived from a purely empirical approach.

Immobilized phospholipid capillary electrophoresis for study of drug–membrane interactions and prediction of drug activity

Immobilized phospholipid capillary electrophoresis (IPCE) was developed for studying the interactions between a set of nonsteroidal anti-inflammatory drugs (NSAIDs) and membrane and predicting the biological activity of NSAIDs. Supported vesicle layers and supported phospholipid bilayers were attached to the inner surface of a capillary wall simply by rinsing with liposome solutions. The liposomes, composed of soybean phosphatidylcholine (SPC) or SPC and different proportions of cholesterol (Ch), were small unilamellar vesicles prepared by sonication. The normalized capacity factor ( K IPCE) was introduced into IPCE for evaluating drug–membrane interactions. Related theories and equations were derived to calculate K IPCE values from apparent migration time of a solute and electroosmotic flow. The strong relationships were observed between log K IPCE (SPC) values and log K lw values (the partition coefficients determined in free SPC-liposome partitioning system) ( R = 0.9855 and P < 0.0001) or log K ILC values (the normalized capacity factors determined by immobilized POPC-liposome chromatography, POPC represents 1-palmitoyl-2-oleoyl- sn-glycero-3-phosphocholine) ( R = 0.9875 and P < 0.0001). In addition, log K IPCE (SPC/Ch 80:20%) values correlated well with the pIC 50 (the minus logarithm of IC 50) values for cyclooxygenase 2 determined on intact cells ( R = 0.959 and P < 0.001). These results confirmed that IPCE, K IPCE value as evaluation index, can be effectually used for studying drug–membrane interactions and it has the potential to predict drug activity. Cholesterol-containing (20 mol%) liposomes may be more suitable to mimic real cell membrane.

Avaliação econômica e desempenho de machos e fêmeas Canchim em confinamento alimentados com dietas à base de silagem de milho e concentrado ou cana-de-açúcar e concentrado contendo grãos de girassol

Objetivou-se avaliar os efeitos do fornecimento de dietas com silagem de milho ou com cana-de-açúcar + grãos de girassol e a influência da condição sexual do animal sobre o desempenho de bovinos jovens em confinamento e os resultados econômicos desse sistema de produção. Foram utilizados 30 animais Canchim (dez machos não-castrados, dez machos castrados e dez novilhas), com 15 meses de idade e 289 kg de peso corporal (PC), mantidos em baias individuais durante 105 dias. Todos os animais foram pesados no início do experimento e a cada 35 dias e, ao final do confinamento, foram abatidos em frigorífico comercial para realização das medidas de características de carcaça. Os machos não-castrados apresentaram maior ingestão de nutrientes em comparação às fêmeas, tanto em valores absolutos quanto em valores relativos ao PC. Os machos castrados apresentaram valores intermediários e não diferiram dos não-castrados e das fêmeas. Os machos não-castrados apresentaram maior ganho de peso diário e desenvolvimento muscular, representado pela maior área de olho-de-lombo. Também foram mais eficientes quanto à conversão alimentar e ao rendimento de carcaça. Não houve efeito das dietas sobre a ingestão de nutrientes, à exceção do EE, que foi maior para a dieta com cana-de-açúcar + semente de girassol, com mais teor desse nutriente. As dietas também não influenciaram o desempenho dos animais. A dieta com silagem de milho mostrou-se economicamente mais viável para terminação de bovinos jovens em confinamento. Os machos não-castrados são os mais adequados para exploração de bovinos jovens em confinamento, independentemente da dieta.

Variation of Characteristics of Pentaoxyethylene Decyl C10E5 and Hexaoxyethylene Tetradecyl C14E6 Ether Micelles with Uptake of n-Octanol

Wormlike micelles of the surfactant pentaoxyethylene decyl C10E5 and hexaoxyethylene tetradecyl C14E6 ethers were characterized by static (SLS) and dynamic light scattering (DLS) experiments to examine effects of uptake of n-octanol on the micellar characteristics. The SLS results have been successfully analyzed by the light scattering theory for micelle solutions to yield the molar mass Mw(c) as a function of concentration c along with the cross-sectional diameter d of the micelle. The apparent hydrodynamic radius RH,app(c) determined by DLS as a function of c has also been successfully analyzed by a fuzzy cylinder theory which takes into account the hydrodynamic and direct collision interactions among micelles, providing us with the values of the stiffness parameter lambda(-1). It has been found that the micellar length Lw increases with increasing surfactant weight fraction ws and increasing n-octanol content wo in the micelles or with raising temperature T. The values of d and lambda(-1) are found to increase with increasing wo, whereas the spacing s between hydrophilic tails of adjacent surfactant molecules on the micellar surface decreases with increasing wo. Comparison with our previous results for the C10E5 and C14E6 micelles containing n-dodecanol has revealed the salient features in change of the micellar characteristics with uptake of n-alcohols as follows: (i) The Lw values increase more significantly for the C14E6 micelles containing n-dodecanol than those containing n-octanol, whereas Lw of the C10E5 micelles increases by including n-dodecanol and n-octanol without a significant difference for the two alcohols. (ii) The values of d and lambda(-1) of the C10E5 and C14E6 micelles increase with uptake of n-octanol and n-dodecanol into the micelles. They are larger for the C10E5 micelles than for the C14E6 micelles, and their increase with alcohol content is less significant for the C14E6 micelles in comparison with the C10E5 micelles. (iii) The s values of the C10E5 and C14E6 micelles decrease with uptake of n-octanol and n-dodecanol into the micelles. They are somewhat larger in the latter micelles than in the former. (iv) The variation in d, s, and lambda(-1) with uptake of n-alcohol occurs with no difference in the effects for the two alcohols n-octanol and n-dodecanol.

Holocene hydrological reconstructions from stable isotopes and paleolimnology, Cordillera Real, Bolivia

Multiproxy analyses of sediment cores from Lago Taypi Chaka Kkota (LTCK) Cordillera Real, Bolivia, provide a record of drier conditions following late Pleistocene deglaciation culminating in pronounced aridity between 6.2 and 2.3 ka B.P. Today LTCK is a glacial-fed lake that is relatively insensitive to changes in P–E because it is largely buffered from dry season draw-down through the year-round supply of glacial meltwater. This was not the case during the middle to late Holocene when glaciers were absent from the watershed. Lake-water δ 18 O values inferred from δ 18 O analysis of sediment cellulose range from −12.9 to −5.3‰ and average −8.7‰ between 6.2 and 2.3 ka B.P. Modern lake-water δ 18 O from LTCK averages −14.8‰ which is compatible with the δ 18 O lw value of −14.3‰ for the surface sediment cellulose. Analyses of δ 18 O from modern surface waters in 23 lakes that span the range from glacial-fed to closed basin vary from −16.6 to −2.5‰. This approximates the magnitude of the down-core shift in δ 18 O lw values in LTCK during the middle to late Holocene from −12.9 to −5.3‰. Strong paleohydrologic change during the middle Holocene is also evident in diatom assemblages that consist of shallow-water, non-glacial periphytic taxa and bulk organic δ 13 C and δ 15 N that show increases likely resulting from degradation of lacustrine organic matter periodically exposed to subaerial conditions. Neoglaciation began after 2.3 ka B.P. as indicated by changes in the composition of the sediments, lower δ 18 O values, and a return to diatom assemblages characteristic of the glacial sediments that formed during the Late Pleistocene. Collectively, these data indicate that the past 2.3 ka B.P. have been the wettest interval during the Holocene. Millennial-scale shifts in the paleohydrologic record of LTCK during the early to middle Holocene conform to other regional paleoclimatic time-series, including Lake Titicaca and Nevado Sajama, and may be driven by insolation and resultant changes in atmospheric circulation and moisture supply. In contrast, an apparent 1200-year lag in the onset of wetter conditions at LTCK (2.3 ka B.P.) compared to Lake Titicaca (3.5 ka B.P.) provides evidence for variable sub-regional hydrologic response to climate change during the middle to late Holocene.

Estimates of vertical heat flux and stratification from Southern Georges Bank, interannual variability, 1985–1995

Interannual variability (IAV) of net vertical heat flux ( Q), potential energy anomaly or “stratification index” ( V) and date of onset for water column stratification were studied using five-day averaged model output over an 11 yr (1985–1995) period for three depth zones which span water depths from less than 60 to 100 m on southern Georges Bank. Comparison between five-day averaged model Q estimates from this study and Q measurements from US-GLOBEC mooring ST1 during winter–summer 1995 shows that nearly all of the difference between uncalibrated model estimates and calibrated ST1 measurements is attributable to the difference between the sum of the latent, sensible and long-wave components ( Q e+ Q s+ Q lw) from each data set. Furthermore, there is virtually no IAV in residual five-day averaged Q e+ Q s+ Q lw values relative to the long-term (1985–1995) mean seasonal cycle, suggesting strongly that the calibration of model Q estimates using measurements from mooring ST1 during 1995 may be applied to other years (1985–1994). Calibrated long-term (1985–1995) monthly mean Q values from this study show a similar seasonal cycle to climatological values determined from ship-of-opportunity data. However, values from this study are higher relative to the ship-of-opportunity long-term monthly mean climatology, with largest differences occurring during winter. IAV of monthly mean Q for zones 1–3 on southern Georges Bank is significant with the magnitude of residuals increasing from zones 1 to 3. Long-term (1985–1995) monthly mean model-derived V computed for zones 1–3 shows zone 1 (<60 m depth) remaining well-mixed throughout the year with no stratification development and therefore no detectable IAV for V. However, within zone 2 (60–80 m depth) and zone 3 (80–100 m depth) significant permanent stratification begins to develop during May and April, respectively, increasing almost linearly from May–July and reaching a maximum during July and August, respectively. IAV of V is large for zones 2 and 3 with typical standard deviations of 1000–5000 J m −2 occurring from late-spring-summer with the largest coefficient of variation during spring and fall. Results from linear regression for zones 2–3 show that IAV of V is controlled largely by IAV of Q, explaining up to ∼80% of the variance, with IAV of wind mixing being of secondary importance. Results from model-derived five-day averaged V show that temporary or “transient” stratification nearly always occurs in early-May and mid-April for zones 2 and 3, respectively, over the 11 yr study period and is associated with reduced tidal stirring during periods of neap tide. The mean date of first transient stratification for zone 3 coincides with the historical maximum abundance of early-stage (<6 mm) cod larvae and copepod nauplii for Georges Bank. In addition, the historical maximum abundance of haddock larvae occurs on Georges Bank at the same time that permanent or “seasonal” stratification is established in zone 3.

Hydrogen bonding. Part 34. The factors that influence the solubility of gases and vapours in water at 298 K, and a new method for its determination

The solubility of 408 gaseous compounds in water at 298 K has been correlated through eqn. (i), where the solubility is expressed as the Ostwald solubility coefficient, Lw, and the solute explanatory variables are R2 an excess molar refraction, π2H the dipolarity/polarizability, Σα2H and Σβ2H the effective hydrogen-bond acidity and basicity, and Vx the McGowan characteristic volume. A similar equation using the log L16 parameter instead of Vx can also be used; L16 is the Ostwald solubility coefficient on hexadecane at 298 K. log Lw=–0.994 + 0.577R2+ 2.549 π2H+ 3.813Σα2H+ 4.841Σβ2H– 0.869 Vx(i), n= 408 ρ= 0.9976 sd = 0.151 F= 16810 The main factors leading to increased solubility are solute π2H, Σα2H and Σβ2H values; conversely, the corresponding properties of water are dipolarity/polarizability, hydrogen-bond basicity and hydrogen-bond acidity. Solute size plays a minor role, and slightly decreases solubility, contrary to observations on all non-aqueous solvents. It is shown that this peculiar behaviour of water is due to (a) a greater increase in the unfavourable cavity effect with increase in solute size, for solvent water, and (b) a smaller increase in the favourable general dispersion interaction with size, for solvent water.A new method for the determination of log Lw values is put forward, using the relationship Lw=L16/P where L16 is as above, and P is either the water–hexadecane partition coefficient or the water–alkane partition coefficient. For 14 solutes using the former P-value, agreement with values calculated through eqn. (i) is 0.08 log units on average and for 45 solutes using the latter P-value, the corresponding agreement is 0.15 log units, with log Lw values ranging up to 8 log units.

Plasmodium saurocaudatum sp. n., a Parasite of Mabuya multifasciata in Southeast Asia

Plasmodium saurocaudatum sp. n. is a parasite of Mabuya multifasciata (Sauria: Scincidae) in Southeast Asia. It is distinguished from all other saurian malarias by producing tiny, fan-shaped or cruciform schizonts that were less than one-half the size of an erythrocyte's nucleus, containing three or four merozoites, in combination with disproportionately large gametocytes that may reach sizes exceeding eight times the host cell's nucleus. The elongate gametocytes of active infections enlarge to become round or oval and bulky, nearly filling the host cell, and resemble gametocytes of saurian species of Haemoproteus. Schizonts were marginal in position, with the asexual phase evidently of short duration but recrudescent. Infections typically were comprised entirely of gametocytes at low parasitemias. On morphological aspects, P. saurocaudatum most closely resembles P. lygosomae Laird, 1951, and it is suggested that both species may be derived from a common precursor which parasitized Southeast Asian skinks. In both the Neotropical and Ethiopian regions, scincid lizards of the genus Mabuya commonly serve as hosts to plasmodiid parasites. In Panama, Brazil, and Colombia, Mabuya mabouya is parasitized by Plasmodium diploglossi (Telford, 1970; Lainson and Shaw, 1969; Ayala, 1978). An unpigmented erythrocytic parasite, Plasmodium morulum, has been found in this host in Panama and Brazil (Telford, 1970; Lainson et al., 1974), whereas the leucocytic Saurocytozoon mabuyi was described from M. mabouya in Brazil (Lainson et al., 1974). In Africa, Plasmodium mabuiae, P. pitmani, and P. maculilabre have been reported from several Mabuya species from the Sudan to Tanzania, and in the Congo (Gamham, 1966; Telford, 1983a). No Plasmodium parasites have been described from the many Mabuya species in Southeast Asia. Telford (1983b) reported the presence of Saurocytozoon mabuyi in Mabuya multifasciata in Singapore and Thailand. As mentioned there, a Plasmodium infection was detected in smears of caudal blood from a M. multifasciata in Singapore in June 1976. The parasite was found again in samples of the same host in Thailand in 1977 and 1980, and in the latter year, adequate material was obtained to permit the description below of this unusual Plasmodium species. MATERIALS AND METHODS Acquisition, processing and examination of material are described in Telford (1983b). Taxonomic characters used are those described by Telford (1974, 1979). Measurements are expressed below in p,m or /m2 for LW values. Parasitemias were calculated from counts Received 9 September 1982; revised 7 March 1983; accepted 10 March 1983. of 600 to 1,600 red blood cells at x 1,000, except in the case of some chronic infections where up to 50 fields at x 400 were examined to provide crude esti-

Interaction of metal ions with nucleic acids and related compounds. II. Studies on Au(III)‐nucleic acid system

AbstractThe nature of interaction of Au(III) with nucleic acids was studied by using methods such as uv and ir spectrophotometry, viscometry, pH titrations, and melting‐temperature measurements. Au(III) is found to interact slowly with nucleic acids over a period of several hours. The uv spectra of native calf‐thymus DNA 9pH 5.6 acetate buffer containing (0.01M NaCIO4) showed a shift in λ max to high wavelengths and an increase in optical density at 260 nm. There was a fourfold decrease in viscosity (expressed as ηsp/c). The reaction was faster at pH 4.0 and also with denatured DNA (pH 5.6) and whole yeast RNA (pH 5.6). The order of preference of Au(III) (as deduced from the time of completion of reaction) for the nucleic acids in RNA &gt; denatured DNA &gt; DNA. The reaction was found to be completely reversible with respect KCN. Infrared spectra of DNA‐Au(III) complexes showed binding to both the phosphate and bases of DNA. The same conclusions were also arrived at by melting‐temperature studies of Au(III)‐DNA system. pH titrations showed liberation of two hydroxylions at r = 0.12 [r = moles of HAuCl4 added per mole of DNA‐(P)] and one hydrogen ion at r = 0.5. The probable binding sites could be N(1)/N(7) of adenine, N(7) and/or C(6)O of guanine, N(3) of cytosine and N(3) of thymine.DNAs differing in their (G = C)‐contents [Clostridium perfingens DNA(G = C, 29%), salmon sperm DNA (G + C, 42%) and Micrococcus lysodeikticus DNA(G + C, 29%), salmon sperm DNA (G = C, 72%)] behaved differently toward Au(III). The hyperchromicity observed for DNAs differing in (G + C)‐content and cyanide reversal titrations indicate selectivity toward ( A + T)‐rich DNA at lw values of r. Chemical analysis and job's continuous variation studies indicated the existence of possible complexes above and below r = 1. The results indicate that Au(III) ions probably bind to hte phosphate group in the initial stages of the reaction, particularly at low values of r, and participation of the base interaction also increases. Cross‐linking of the two strands by Au(III) may take place, but a complete collapse of the doulbe helix is not envisaged. It is probable that tilting of the bases or rotaiton of the bases around the glucosidic bond, resulting in a significant distrotion of the double helix, might take place due to binding of Au(III) to DNA.