Dominant Spot Research Articles

The medicinal plant Berberis aristata and its endophytes for pharmacological applications: Current research and future challenges

Exploring medicinal plants for their natural products to benefit humanity has been a practice since ancient times. Berberis aristata, also known as tree turmeric or Indian barberry, has a dominant spot in conventional medicine for 2500 plus years. In the latter years, this particular species has gained prime attention in pharmaceutical zone due to its scarcity. The plant and its formulations are used to treat numerous human health threats including cancer, diabetes, diarrhea, wound relieving, infections of eyes and ears, gynecological disorders, and HIV-AIDS. The bioactive compounds present in B. aristata are found to contain anti-inflammatory, antioxidant, and anti-microbial properties. The plant is critically jeopardized species of Indian Himalaya due to the collection of its roots at a large scale for obtaining berberine alkaloid and its conservation is of great concern. At present, isolation of endophytic entities from remedial plants revolutionized the path of discovering drugs from medicinal plants. Endophytes can produce the same bioactive as their host plant as well as another bioactive to address a variety of human health issues. The review examines the bioprospecting of B. aristata, a medicinal shrub from the family Berberidaceae, and its associated endophytes for the production of bioactive compounds with application to human health. Finally, the review provides a comprehensive outlook on the current status and future prospects of bioprospecting B. aristata and its endophytes to combat future human health threats is an exciting area of research that should be further explored.

Understanding the flare emission in CF Tucanae using TESS

Abstract Chromospherically active binaries are important in the understanding of the origins of optical flares. Since studies of flares in binaries are important, we perform a detailed analysis of 11 flares emitted by the RS CVn binary source CF Tucanae using the Transiting Exoplanet Survey Satellite (TESS). We assume a 10000 K blackbody spectrum to determine the flare energies, which were noted to be ∼0.29–2.86 × 1035 erg. We also fitted optical flares with a fast rise with an exponential decay burst profile and decay times were used to estimate the flare scale lengths. Three flares among them mandate a double burst model and another two exhibit complex flare features. Spot areas were found to be ∼1022 cm2 and associated magnetic energies were found to be ∼1036–37 erg. This excess of magnetic energy indicates that the flares release only a small fraction of the magnetic energy of the dominant spot but may indicate a lack of connection between the flares and the dominant spot. We also study the periodic variations using the times of minima obtained from TESS data along with previous values. The optical periodic variation requires a parabola and a sinusoidal function to get the best fit. A new periodic modulation of Pmod ∼ 28.64 ± 1.82 yr was observed and we attempt to explain this using a magnetic activity cycle. We conclude that CF Tuc exhibits complex flares and its periodic modulation varies, probably due to the exchange of spin and orbital angular momentum in the binary.

Design and realization of an autofocusing Airyprime beams array

An Airyprime beams array that consists of four centrosymmetric Airyprime beamlets is designed for the first time, and the analytical expression of the Airyprime beams array propagating in free space is derived. The Airyprime beams array is shown to possess the autofocusing property. The effects of the transverse displacement parameter, the exponential decay factor and the scaling factor on the autofocusing ability and the focus position of the Airyprime beams array are investigated in detail. The autofocusing ability of the Airyprime beams array is improved by increasing the transverse displacement parameter or reducing the exponential decay factor. Further, the autofocusing ability of the Airyprime beams array in the case of nonzero off-centre position can be enhanced by decreasing the scaling factor. The focus position of the Airyprime beams array can be controlled by adjusting the transverse displacement parameter or the scaling factor. The autofocusing evolutionary process of the Airyprime beams array is quite different from that of the Airy beams array. The trajectory of the peak intensity for the Airyprime beams array is more regular than that for the Airy beams array. The Airyprime beams array has stronger autofocusing ability and smaller focusing dominant spot than the Airy beams array with the same beam parameters. Moreover, we experimentally generate the Airyprime beams array, and the autofocusing properties of the Airyprime beams array are demonstrated. The Airyprime beams array will find important potential applications in free space optical communication and so on.

Light Bridge and Magnetic Field in a Solar Active Region

Observational data from the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory and the multiwavelength simultaneous imaging system attached to the New Vacuum Solar Telescope located at Fuxian Lake, China are employed for the study of light bridges and magnetic fields in the active region NOAA 12529. Coronal fields in this active region are computed with a boundary integration model and the field line connectivity in the dominant spot is investigated with the squashing factor Q. Quasi separatrix layer intersections in the CCD coordinate plane are determined according to values of Q. It is found that weak field lanes (WFLs) appear in the umbra and penumbra; open and closed flux systems are separated by QSLs in the dominant spot; and WFLs and QSLs look quite different from each other in the dominant spot but partially overlap in the umbra. Our study demonstrates that WFLs cannot be attributed to topological evolution of magnetic fields and might be regarded as rifts among splitting flux systems.

Measuring Periods in Aperiodic Light Curves—Applying the GPS Method to Infer the Rotation Periods of Solar-like Stars

Light curves of solar-like stars are known to show highly irregular variability. As a consequence, standard frequency analysis methods often fail to detect the correct rotation period. Recently, Shapiro et al. showed that the periods of such stars could still be measured by considering the Gradient of the Power Spectrum (GPS) instead of the power spectrum itself. In this study, the GPS method is applied to model light curves of solar-like stars covering all possible inclination angles and a large range of metallicities and observational noise levels. The model parameters are chosen such that they resemble those of many stars in the Kepler field. We show that the GPS method is able to detect the correct rotation period in ≈40% of all considered cases, which is more than 10 times higher than the detection rate of standard techniques. Thus, we conclude that the GPS method is ideally suited to measure periods of those Kepler stars lacking such a measurement so far. We also show that the GPS method is significantly superior to autocorrelation methods when starspot lifetimes are shorter than a few rotation periods. GPS begins to yield rotation periods that are too short when dominant spot lifetimes are shorter than one rotation period. We conclude that new methods are generally needed to reliably detect rotation periods from sufficiently aperiodic time series—these periods will otherwise remain undetected.

Mechanism of Protein–PDMS Visible Particles Formation in Liquid Vial Monoclonal Antibody Formulation

Visible particles (VPs) formation in liquid monoclonal antibody formulations is a critical quality issue. Formulations that include poloxamer 188 (PX188) as a surfactant are prone to the formation of VPs comprising aggregated complexes of protein and polydimethylsiloxane (PDMS; silicone oil) derived from primary containers. However, the mechanisms through which these VPs form are complicated and remain to be fully elucidated. This study demonstrates for the first time the dominant spot and pathway of protein–PDMS VP formation in a particular liquid vial formulation. Specifically, when a vial sealed with a PDMS-coated stopper is stored in an upright position under conditions whereby the antibody solution has become well-adhered to the stopper and an air phase exists in the vicinity, protein–PDMS aggregates form on the stopper and are then desorbed into the drug solution to be detected as VPs. Here, we evaluated the effects of several factors on VP formation: adhesion of the drug solution to the stopper, storage orientation, silicone coating on the stopper, vial material, and hydrophobicity of PX188. Remarkably, we found that changing any one of the factors could significantly affect VP formation. Our findings are instructive for better understanding the mechanisms of VP formation in vial products and can provide strategies for VP mitigation in biotherapeutics.

A confined dynamo: Magnetic activity of the K-dwarf component in the pre-cataclysmic binary system V471 Tauri

Context.Late-type stars in close binary systems can exhibit strong magnetic activity owing to rapid rotation supported by tidal locking. On the other hand, tidal coupling may suppress the differential rotation which is a key ingredient of the magnetic dynamo.Aims.We studied the red dwarf component in the eclipsing binary system V471 Tau in order to unravel the relations between the different activity layers, from the stellar surface through the chromosphere up to the corona. Our aim is to study how the magnetic dynamo in the late-type component is affected by the close white dwarf companion.Methods.We used space photometry, high-resolution spectroscopy, and X-ray observations from different space instruments to explore the main characteristics of magnetic activity. We applied a light curve synthesis program to extract the eclipsing binary model and to analyze the residual light variations. Photometric periods were obtained using a Fourier-based period search code. We searched for flares by applying an automated flare detection code. Spectral synthesis was used to derive or specify some of the astrophysical parameters. Doppler imaging was used to reconstruct surface temperature maps, which were cross-correlated to derive surface differential rotation. We applied different conversion techniques to make it possible to compare the X-ray emissions obtained from different space instruments.Results.From the K2 photometry we found that 5–10 per cent of the apparent surface of the red dwarf is covered by cool starspots. From seasonal photometric period changes we estimated a weak differential rotation. From the flare activity we derived a cumulative flare frequency diagram which suggests that frequent flaring could have a significant role in heating the corona. Using high-resolution spectroscopy we reconstructed four Doppler images for different epochs which reveal an active longitude, that is, a permanent dominant spot facing the white dwarf. From short term changes in the consecutive Doppler images we derived a weak solar-type surface differential rotation withαDR = 0.0026 shear coefficient, similar to that provided by photometry. The long-term evolution of X-ray luminosity reveals a possible activity cycle length of ≈12.7 yr, traces of which were also discovered in the Hαspectra.Conclusions.We conclude that the magnetic activity of the red dwarf component in V471 Tau is strongly influenced by the close white dwarf companion. We confirm the presence of a permanent dominant spot (active longitude) on the red dwarf facing the white dwarf. The weak differential rotation of the red dwarf is very likely the result of tidal confinement by the companion. We find that the periodic appearance of the inter-binary Hαemission from the vicinity of the inner Lagrangian point is correlated with the activity cycle.

Using genomic resources for linkage analysis in Peromyscus with an application for characterizing Dominant Spot

BackgroundPeromyscus are the most common mammalian species in North America and are widely used in both laboratory and field studies. The deer mouse, P. maniculatus and the old-field mouse, P. polionotus, are closely related and can generate viable and fertile hybrid offspring. The ability to generate hybrid offspring, coupled with developing genomic resources, enables researchers to conduct linkage analysis studies to identify genomic loci associated with specific traits.ResultsWe used available genomic data to identify DNA polymorphisms between P. maniculatus and P. polionotus and used the polymorphic data to identify the range of genetic complexity that underlies physiological and behavioral differences between the species, including cholesterol metabolism and genes associated with autism. In addition, we used the polymorphic data to conduct a candidate gene linkage analysis for the Dominant spot trait and determined that Dominant spot is linked to a region of chromosome 20 that contains a strong candidate gene, Sox10. During the linkage analysis, we found that the spot size varied quantitively in affected Peromyscus based on genetic background.ConclusionsThe expanding genomic resources for Peromyscus facilitate their use in linkage analysis studies, enabling the identification of loci associated with specific traits. More specifically, we have linked a coat color spotting phenotype, Dominant spot, with Sox10, a member the neural crest gene regulatory network, and that there are likely two genetic modifiers that interact with Dominant spot. These results establish Peromyscus as a model system for identifying new alleles of the neural crest gene regulatory network.

The carbon star R Sculptoris sheds its skin

AbstractWe describe near-IR H-band VLTI-PIONIER aperture synthesis images of the carbon AGB star R Sculptoris with an angular resolution of 2.5 mas. The data show a stellar disc of diameter ∼ 9 mas exhibiting a complex substructure including one dominant bright spot with a peak intensity of 40% to 60% above the average intensity. We interpret the complex structure as caused by giant convection cells, resulting in large-scale shock fronts, and their effects on clumpy molecule and dust formation seen against the photosphere at distances of 2–3 stellar radii. Moreover, we derive fundamental parameters of R Scl, which match evolutionary tracks of initial mass 1.5 ± 0.5 M⊙. Our visibility data are best fit by a dynamic model without a wind, which may point to problems with current wind models at low mass-loss rates.

The gene conferring susceptibility to spot blotch caused by Cochliobolus sativus is located at the Mla locus in barley cultivar Bowman

We identified, fine mapped, and physically anchored a dominant spot blotch susceptibility gene Scs6 to a 125kb genomic region containing the Mla locus on barley chromosome 1H. Spot blotch caused by Cochliobolus sativus is an important disease of barley, but the molecular mechanisms underlying resistance and susceptibility to the disease are not well understood. In this study, we identified and mapped a gene conferring susceptibility to spot blotch caused by the pathotype 2 isolate (ND90Pr) of C. sativus in barley cultivar Bowman. Genetic analysis of F1 and F2 progeny as well as F3 families from a cross between Bowman and ND 5883 indicated that a single dominant gene (designated as Scs6) conferred spot blotch susceptibility in Bowman. Using a doubled haploid (DH) population derived from a cross between Calicuchima-sib (resistant) and Bowman-BC (susceptible), we confirmed that Scs6, contributed by Bowman-BC, was localized at the same locus as the previously identified spot blotch resistance allele Rcs6, which was contributed by Calicuchima-sib and mapped on the short arm of chromosome 1H. Using a genome-wide putative linear gene index of barley (Genome Zipper), 13 cleaved amplified polymorphism markers were developed from 11 flcDNA and two EST sequences and mapped to the Scs6/Rcs6 region on a linkage map constructed with the DH population. Further fine mapping with markers developed from barley genome sequences and F2 recombinants derived from Bowman × ND 5883 and Bowman × ND B112 crosses delimited Scs6 in a 125kb genomic interval harboring the Mla locus on the reference genome of barley cv. Morex. This study provides a foundational step for further cloning of Scs6 using a map-based approach.

Rapid Light-curve Changes and Probable Flip-flop Activity of the W UMa-type Binary V410 Aur

Abstract New photometric observations of a W UMa system, V410 Aur, were carried out over 10 nights from 2014 December 19 to 2015 February 8, from which four sets of light curves were obtained. The light curves show many unusual behavioral features, including changing occultation depths, transit minima, and asymmetric maxima. The four sets of light curves have been separately analyzed with the Wilson–Devinney method. The results suggest a totally eclipsing contact configuration for the system. Over a surprisingly short time span of only 52 days, the dominant spot distortion phase jumped twice between phases 0.0 and 0.5. The light-curve variations can be interpreted by the presence of two cool spots on the massive component. Based on our analysis, it is further suggested that the peculiar behavioral patterns are probably caused by the presence of two permanent, active large spots separated in longitude by about 180°, whose locations remain almost unchanged throughout. Our study demonstrates that the system has been undergoing typical flip-flop activity. We therefore conclude that V410 Aur is a W UMa-type system exhibiting flip-flop activity.

Four kinds of ENU-induced white spot mice and chromosome locations of the mutant genes

“Phenotype-driven” is the name for an approach used to study gene functions through mutagenesis, location and cloning of the mutant gene. In this study, 150 male C57BL/6J(B6) mice were treated with ENU and reproduced a total offspring of 3860. Of these descendants, 210 exhibited mutation phenotypes by screening, and more than 10 of them are hereditable. Four kinds of mutant mice, named Wbct, W−1Bao, W−2Bao, and W−2Bao, showed dominant hereditary white spot mutation with partial albinism on their belly, distal limbs and tail terminal. To map these mutant genes, 39 microsatellites, equally distributed on the mouse genome and with difference between B6 and DBA/2J (D2), were selected to scan the genome after discrimination of the white spots in the F2 mice [(B6xD2)xD2]. It is found that, the log odds score (LODS) between W−1Bao and D5Mitl68 is 0.56, and the LODS of W−1Bao and D5Mit352 is 4.47. With the gradual application of microsatellites D5Mit290, D5Mit312, D5Mit308 and D5Mit356 that are close to the mutant gene, and the number of F2 mice going up to 537, the mutant W−1Bao is located between D5Mit356 and D5Mit308 on chromosome 5, about 42.19 cM from the centromere. In the same way, W−2Bao and W−3Bao are mapped nearby W−1Bao, and Wbct is located on chromosome 1, about 41.6 cM from the centromere. After searching for the mouse genome database (MGD) and performing a one-by-one study of all genes located on chromosome subregion, it is believed that thekit gene is an excellent candidate for the white spot mutations of W−1Bao, W−2Bao and W−3Bao.

Time‐series photometric spot modelling – VI. A new computer code and its application to 23 years of photometry of the active giant IM Pegasi

AbstractWe present and apply a new computer program named SpotModeL to analyze single and multiple bandpass photometric data of spotted stars. It is based on the standard analytical formulae from Budding and Dorren. The program determines the position, size, and temperature of up to three spots by minimizing the fit residuals with the help of the Marquardt‐Levenberg non‐linear least‐squares algorithm. We also expand this procedure to full time‐series analysis of differential data, just as real observations would deliver. If multi‐bandpass data are available, all bandpasses can be treated simultaneously and thus the spot temperature is solved for implicitly. The program may be downloaded and used by anyone. In this paper, we apply our code to an ≈23 year long photometric dataset of the spotted RS CVn giant IM Peg. We extracted and modelled 33 individual light curves, additionally, we fitted the entire V dataset in one run. The resulting spot parameters reflect the long term light variability and reveal two active longitudes on the substellar point and on the antipode. The radius and longitude of the dominant spot show variations with 29.8 and 10.4 years period, respectively. Our multicolour data suggests that the spot temperature is increasing with the brightening of the star. The average spot temperature from V, IC is 3550 ± 150 K or approximately 900 K below the effective temperature of the star.

Dietary cholesterol reduces lipoprotein lipase activity in the atherosclerosis-susceptible Bio F(1)B hamster.

We have compared lipoprotein metabolism in, and susceptibility to atherosclerosis of, two strains of male Golden Syrian hamster, the Bio F(1)B hybrid and the dominant spot normal inbred (DSNI) strain. When fed a normal low-fat diet containing approximately 40 g fat and 0.3 g cholesterol/kg, triacylglycerol-rich lipoprotein (chylomicron+VLDL) and HDL-cholesterol were significantly higher (P<0.001) in Bio F(1)B hamsters than DSNI hamsters. When this diet was supplemented with 150 g coconut oil and either 0.5 or 5.0 g cholesterol/kg, significant differences were seen in response. In particular, the high-cholesterol diet produced significantly greater increases in plasma cholesterol and triacylglycerol in the Bio F(1)B compared with the DSNI animals (P=0.002 and P<0.001 for cholesterol and triacylglycerol, respectively). This was particularly dramatic in non-fasting animals, suggesting an accumulation of chylomicrons. In a second experiment, animals were fed 150 g coconut oil/kg and 5.0 g cholesterol/kg for 6 and 12 months. Again, the Bio F(1)B animals showed dramatic increases in plasma cholesterol and triacylglycerol, and this was confirmed as primarily due to a rise in chylomicron concentration. Post-heparin lipoprotein lipase activity was significantly reduced (P<0.001) in the Bio F(1)B compared with the DSNI animals at 6 months, and virtually absent at 12 months. Bio F(1)B animals were also shown to develop significantly more (P<0.001) atherosclerosis. These results indicate that, in the Bio F(1)B hybrid hamster, cholesterol feeding reduces lipoprotein lipase activity, thereby causing the accumulation of chylomicrons that may be associated with their increased susceptibility to atherosclerosis.

X‐Ray and Optical Observations of BL Hydri

We acquired hard X-ray and unfiltered optical photometric data of the AM Herculis system BL Hydri. The X-ray data were obtained using the Proportional Counter Array detector of the Rossi X-Ray Timing Explorer satellite on 1997 October 17. The optical data were obtained using the 1.5 m telescope of the Cerro Tololo Inter-American Observatory on 1997 September 24. At the time of our observations, BL Hyi was in an unusual high-luminosity state with average visual magnitude mV ≈ 14.4 and orbital phase-averaged 2-10 keV X-ray flux ≈1.5 × 10-11 ergs cm-2 s-1, roughly 50% larger than had been seen previously. The X-ray light curves suggested that two accretion poles were active. The primary X-ray emission region was extended, covering ~45° in longitude on the white dwarf, while the secondary X-ray emission region was consistent with a point source with flux ~33% that of the primary region. The X-ray spectra were well fitted by absorbed bremsstrahlung with Gaussian emission-line models; and absorbed power law with Gaussian emission-line models. For the thermal models, the X-ray spectra were consistent with kTX ≈ 11 keV and an emission line at E ≈ 6.7-6.8 keV with equivalent width EW = 0.86-1.2 keV. The absorbed power-law models had slope α ≈ 2.1 and an emission line at E = 6.7-6.8 keV with EW = 1.1-1.5 keV. The optical data showed, 2.7% ± 0.2% rms quasi-periodic oscillations (QPOs) over the frequency range 0.2-0.8 Hz modulated strongly on the orbital period suggesting that the QPOs were connected with the dominant accretion hot spot. We did not find corresponding QPOs in the X-ray emission for an upper limit of 20% rms. There were no detections of other short-period QPOs or coherent features in either the optical or the X-ray data. The X-ray and optical data were consistent with a radiative shock model. Based primarily on the X-ray continuum and line spectrum, we infer that the mass of the white dwarf in the BL Hyi system is 0.3-0.7 M☉, depending on the relative cyclotron and hard X-ray luminosities.

V2301 Ophiuchi: An X‐Ray–bright Eclipsing AM Herculis Object

We present hard X-ray and optical observations of the eclipsing AM Her system V2301 Oph. The X-ray data were obtained using the PCA detector of the Rossi X-Ray Timing Explorer satellite during 1997 May, and the optical data were obtained using the 1 and 1.5 m telescopes of the Cerro Tololo Inter-American Observatory during 1996 May and 1997 June. V2301 Oph was bright in both the optical and hard X-rays during our observations. This, when coupled with its eclipsing nature, makes V2301 Oph an ideal testbed for theories of the large-scale topology of AM Her flows and the radiative shocks in AM Her systems. The X-ray emission from V2301 Oph was modulated strongly on the orbital period. During the bright orbital phases, the X-ray flux was Fx≈3.6 × 10−11 ergs cm-2 s-1 over the energy range E=2-10 keV. The X-ray emission did not go to zero during the faint orbital phases; it was ~10% of the bright phase level. The X-ray spectrum could be fitted by (1) optically thin thermal bremsstrahlung (temperature kTx≈9-19 keV) models with an absorption line at 5.1-5.2 keV or an emission line at ~7 keV, and (2) power-law continuum (index ≈2) models with an absorption line at 5.1-5.2 keV or an emission line at ~7 keV. The absorption columns were large for all fits, nH~(3-10) × 1022 cm-2. The nH are model dependent, but their large sizes are secure because they are set by the rollover in the X-ray spectrum at 3-4 keV. The hardness of the X-ray spectrum was roughly constant during the bright orbital phases. During the faint orbital phases, the X-ray spectral properties were not well determined, but it did appear that the spectrum hardened. There were total eclipses in both the X-ray and optical light curves. The X-ray light curves and eclipses were consistent with a dominant hot spot and a secondary hot spot. The dominant hot spot was not a point source; it had to cover about 50° in longitude on the surface of the white dwarf. We argue that the X-ray light curve and eclipse shape also suggest that the accretion occurs in a sheetlike geometry rather than in a columnar geometry. The optical light curves and eclipses were consistent with emission from the white dwarf photosphere, an extended emission region that sat above the surface of the white dwarf, and the X-ray-heated face of the companion star.

Coat Color Genetics of &lt;italic&gt;Peromyscus&lt;/italic&gt;: IV. Variable White, a New Dominant Mutation in the Deer Mouse

The variable white mutation arose spontaneously in 1983 within a laboratory stock of wild-type deer mice (Peromyscus maniculatus). The original mutant animal was born to a wild-type pair that had previously produced several entirely wild-type litters. Other variable white animals were bred from the initial individual. Variable white deer mice exhibit extensive areas of white on the head, sides, and tail. Usually a portion of pigmented pelage occurs dorsally and on the shoulders, but the extent of white varies from nearly all white to patches of white on the muzzle, tip of tail, and sides. The pattern is irregular, but not entirely asymmetrical. Eyes are pigmented, but histologically reveal a decrease in thickness and pigmentation of the choroid layer. Many variable white animals do not respond to auditory stimuli, an effect that is particularly evident in animals in which the head is entirely white. Ataxic behavior is also prevalent. Pigment distribution, together with auditory and retinal deficiencies, suggests a neural crest cell migration defect. Breeding data are consistent with an autosomal semidominant, lethal mode of inheritance. The trait differs from two somewhat similar variants in Peromyscus: from dominant spot (S) in extent and pattern of pigmentation and from whiteside (ws), an autosomal recessive trait, in the mode of inheritance and viability. Evidence for possible homology with the Va (varitint-waddler) locus in house mouse (Mus) is presented. The symbol Vw is tentatively assigned for the variable white locus in Peromyscus.

Volcanic Activity on Io at the Time of the Ulysses Encounter

The population of heavy ions in lo's torus is ultimately derived from lo volcanism. Groundbased infrared observations of lo between October 1991 and March 1992, contemporaneous with the 8 February 1992 Ulysses observations of the lo torus, show that volcanic thermal emission was at the low end of the normal range at all lo longitudes during this period. In particular, the dominant hot spot Loki was quiescent. Resolved images show that there were at least four hot spots on lo's Jupiter-facing hemisphere, including Loki and a long-lived spot on the leading hemisphere (Kanehekili), of comparable 3.5-micrometer brightness but higher temperature.

Indole carboxylic acid in zinc-deficient radish shoots

Abstract van Urk-Salkowsky's reactive spots were detected on a two dimensional thin layer chromatogram of the acidic fraction from zinc deficient radish shoots. A yellowish and dominant spot gave the same R f value and color reaction as those of the authentic carboxylic acid (ICA). For further identification of ICA in the zinc-deficient radish shoots, GC-MS was employed. The fraction of the methylated final extract, which appeared as a peak on the gas chromatogram at the same retention time as that of the methylated authentic ICA showed high peaks at 175, 144, and 116 m/e. Mass spectra of the methylated authentic ICA revealed the presence of peaks at 175, 144, and 116 m/e. These results suggest that ICA was present in the zinc deficient radish shoots. The amount of ICA in the zinc deficient and control radish shoots were 32 and 1.4 μg/100 g F.W., respectively.

Phenotypic variation in male guppies from natural inland populations: an additional test of Haskins' sexual selection/predation hypothesis

In Venezuela, guppies,Poecilia reticulata, are found in a diversity of aquatic ecosystems fringing the western slope of the eastern Andes. These inland drainages are associated with large between-site variation in both physical and biotic environments. Numbers of potential guppy predators vary greatly between low diversity piedmont streams and high diversity llanos swamps. We analyze geographic variation in several phenotypic traits associated with conspicuousness of male guppies as an independent test of Haskins' (Haskins et al. 1961) hypothesis of natural balance between sexual selection (driving male conspicuousness) and predation (driving crypsis). Four sites were compared: a diverse llanos swamp (high predation), two Andean piedmont streams (intermediate and low predation), and a spring pool located south of Venezuela's Paria Peninsula (no aquatic predators). Because tropical wet and dry seasons are associated with varying degrees of environmental change at these sites, within-site seasonal samples provided an additional test of the role of selective predation on Male phenotypes. Phenotypic traits associated with both size and coloration supported the sexual selection/predation hypothesis. male guppies from the spring were generally more colorful than male guppies from inland drainages. Males from the diverse swamp site were smaller and less colorful than guppies from other sites. Males from the swamp population were smallest and least colorful during the early dry season, when diurnal aquatic piscivores were more diverse and abundant. Dominant spot pigments at each site were generally those that provided greatest contrast with the predominant environmental background color, lending further evidence that coloration patterns in male guppies enhance conspicuousness.