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PubMed2002

Domesticated birds as a model for the genetics of speciation by sexual selection.

In theory, even populations occupying identical environments can diverge in sexually selected traits, as a consequence of different mutational input. I evaluate the potential of this process by comparing the genetics of breeds of domesticated birds to what is known about the genetics of differences among species. Within domesticated species there is a strong correlation of time since domestication with the number of breeds. Descendants of the rock dove, Columba livia (the oldest domesticate) show differences in courtship, vocalizations, body shape, feather ornaments (crests and tails) and colors and color patterns. When nine other domesticated species are included there is a striking hierarchy, with more recent domesticates having a nested subset of these traits: the youngest domesticated species have breeds distinguished only by color. This suggests that selection of new, visible, mutations is driving the process of breed diversification, with mutations that appeal to the breeder happening the most frequently in color. In crosses among related species, color, feather ornaments and many vocalizations and displays show both intermediate dominance and pure dominance. Although the number of loci affecting each of these traits is typically unknown, limited evidence of the genetics of species' differences suggests that some differences are due to the substitution of single genes of major effect. While neither the genetics of breeds nor the genetics of species provide a perfect model for the genetics of speciation, similarities between the two are sufficiently striking to infer that major, visible, mutations can provide the impetus underlying new directions of sexual selection.

Acoustic Stimulation↗
PubMed2003

Adsorption of metals to membrane filters in view of their speciation in nutrient solution.

Filtration of a solution may lower metal concentrations through adsorption of metal species to the filter. Processes such as filter-sterilizing nutrient solution and filtration of field water are sensitive to these sorption artifacts, yet basic data on the affinity of different filters for metals are lacking. This article describes the adsorption of five metals to eight types of 0.2-microm membrane filters used for sterilizing a plant (Lemna minor L.) culture medium. Filters of cellulose acetate, cellulose nitrate, mixed cellulose ester, nylon, polyamide, polycarbonate, polyester, and polyvinylidene fluoride were tested for their affinity toward mono- (K), di-(Mn, Cu, Zn), and trivalent (lanthanum [La]) metals. Metal concentrations were quantified using radioisotopes and speciation was calculated. Results showed that metals had the lowest affinity for polycarbonate and nylon filters and the highest affinity for cellulose- and polyester-type filters. Furthermore, it was shown that the metal load on cellulose filters correlated best with free ion concentrations (indicating electrostatic attraction), while loads on other filters correlated better with total metal concentrations. Filtering a 5-ml solution of pH 5 did not affect its metal concentrations, ranging from 10 nM (La) to 49 microM (K). To minimize filtration artifacts, we propose using polycarbonate or nylon filters, especially when dealing with low volumes of high pH and low metal species concentrations.

Adsorption↗
PubMed2000

[Study on primary speciation of seven metallic elements in pearl powder].

We have determined seven metallic elements in various extract of pearl powder by FAAS. The result implies that the quantity of different element in water and acidic solvent system is different. It has supplied reference data for the further studies of speciation of metallic elements in natural product also.

Animals↗
PubMed2003

Comparison of the response of three microalgae species exposed to elutriates of estuarine sediments based on growth and chemical speciation.

The elutriate sediment toxicity test (ESTT) provides a measure of the amount of a substance that is exchanged between the sediment and the aqueous phase during resuspension processes such as floods or dredging operations. This study used ESTT with two complementary aims: a comparison of the elutriates of two estuarine sediments (anaerobic muddy [A] and aerobic sandy [B]) in terms of toxicity and a comparison of the response of three different microalgae (Emiliania huxleyi (coccolithophore), Dunaliella minuta (green alga), and Phaeodactylum tricornutum (diatom)) to each elutriate in terms of growth, heavy metals uptake, and organic ligands release or uptake in order to find eventual differences of sensitivity. The interpretation of the results was based on chemical speciation in the culture media. Both elutriates, particularly A, were much richer than seawater (control medium) in some heavy metals and organic ligands able to bind strongly heavy metals. Elutriate A slightly inhibited P. tricornutum growth but stimulated growth of E. huxleyi and D. minuta. Elutriate B stimulated the growth of the three algal species. Therefore, the diatom behaved differently from both the coccolithophore and the green alga. Strong complexation of trace metals by organic ligands could be the cause of absence of the metallic toxicity of the elutriates. Growth inhibition of P. tricornutum in elutriate A could be caused by ammonia-N and/or organic compounds. The concentration of the organic ligands decreased markedly (about 75%) in both elutriates after 10 d of incubation in contrast to the control culture, where their concentration increased about 50% because of exudation. This phenomenon was interpreted to result from ligand uptake by the algae, free or as metal complexes. This work demonstrated that beside the evaluation of toxicity of free heavy metals to alga species, the organic ligands must not be ignored. Depending on the amount of ligand present, the toxicity can be reduced (sequestration) or enhanced (better availability through uptake of metal-ligand complexes). Since the applied ESTT is a standard procedure (U.S. Environmental Protection Agency) for the evaluation of dredged material proposed for ocean disposal, it is necessary to discuss results obtained during toxicity tests with such elutriates in detail.

Aerobiosis↗
PubMed2003

A personal particle speciation sampler.

Fuller understanding of personal exposures to particulate matter with aerodynamic diameters below 2.5 microm (PM2.5*) requires a personal sampler suitable for assaying not only PM2.5 mass but also its major chemical constituents: elemental carbon, organic carbon, sulfates, and nitrates. The goal to measure these constituents simultaneously imposes several constraints on personal sampler design. The aim of this project was to develop a sampler within these constraints that would be suitable for personal monitoring over 8 hours. In addition, with the intent to improve the precision of mass measurements, we investigated offline use of beta attenuation. The personal particle speciation sampler (PPSS) includes an inlet to remove particles larger than 2.5 microm, 2 sampling channels, and a pump with flow control. One channel serves for measuring particle mass and inorganic ions; the other, for measuring organic carbon and elemental carbon. Denuders can be placed in either channel or both channels. A backup filter can be placed on the denuded channel to collect volatilized particulate nitrate. Two prototype PPSS units were built and tested. The results of both laboratory testing of key PPSS components and a limited field study of the prototype in comparison to an AIHL (Air and Industrial Hygiene Laboratory) cyclone-based sampler are reported.

Aerosols↗
PubMed2003

Arsenic speciation in the earthworms Lumbricus rubellus and Dendrodrilus rubidus.

Two species of earthworm, Lumbricus rubellus Hoffmeister and Dendrodrilus rubidus (Savigny) collected from an arsenic-contaminated mine spoil site and an uncontaminated site were investigated for total tissue arsenic concentrations and for arsenic compounds by liquid chromatography-mass spectrometry (LC-MS) and liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS). For L. rubellus, whole-body total tissue arsenic concentrations were 7.0 to 17.0 mg arsenic/ kg dry weight in uncontaminated soil and 162 to 566 mg arsenic/kg dry weight in contaminated soil. For D. rubidus, whole-body tissue concentrations were 2.0 to 5.0 mg arsenic/kg dry weight and 97 to 321 mg arsenic/kg dry weight, respectively. Arsenobetaine was the only organic arsenic species detected in both species of earthworms, with the remainder of the extractable arsenic being arsenate and arsenite. There was an increase in the proportion of arsenic present as arsenobetaine in the total arsenic burden. Lumbricus rubellus and D. rubidus have similar life styles, both being surface living and litter feeding. Arsenic speciation was found to be similar in both species for both uncontaminated and contaminated sites, with dose-dependent formation of arsenobetaine. When L. rubellus and D. rabidus from contaminated sites were incubated in arsenic-free soils, the total tissue burden of arsenic diminished. Initially, L. rubellus from the tolerant populations (from the contaminated site) eliminated arsenic in the first 7 d of exposure before accumulating arsenic in tissues, whereas nontolerant populations (from the uncontaminated site) accumulated arsenic linearly. The tolerant and nontolerant L. rubellus eliminated tissue arsenic linearly over 21 d when incubated in uncontaminated soil.

Animals↗
PubMed2003

[Speciation and characterization of interaction of PACls with sulfate].

The interaction of sulfate with various PACl was investigated by using Ferron assay, chemical analysis and SEM. The experimental results showed that the basicity (B = [OH]/[Al]) exhibited significant role in the PACl-sulfate reaction. It indicated different species in various PACl under different reaction pathway with sulfate. The Alc formed precipitation quickly with sulfate, while Alb underwent slowly crystalization. The decrease of Ala resulted in the limit of ferron method. The different speciation component in PACls formed different crystal morphology and chemical composition with sulfate. Increase the basicity, the content of sulfate in precipitate decreased from 0.45 to 0.30.

Aluminum Hydroxide↗
PubMedDate not supplied

Speciation of arsenic in chicken meat by anion-exchange liquid chromatography with inductively coupled plasma-mass spectrometry.

A method was developed for speciation analysis of arsenic in chicken meat. Different procedures were optimized for the recovery of arsenic compounds without destroying the original compounds, and 2 anion-exchange liquid chromatography columns were compared for the separation of arsenic species prior to on-line detection by inductively coupled plasma-mass spectrometry. The 2 species found were dimethylarsinic acid (106 +/- 5 ng/g) and arsenobetaine (37 +/- 4 ng/g). The stability of arsenic species in a chicken meat candidate reference material for at least 12 months was demonstrated.

Animals↗
PubMed2004

Phylogenetic and molecular evidence for allochronic speciation in gall-forming aphids (Pemphigus).

Sympatric populations can diverge when variation in phenology or life cycle causes them to mate at distinctly different times. We report patterns consistent with this process (allochronic speciation) in North American gall-forming aphids, in the absence of a host or habitat shift. Pemphigus populi-transversus Riley and P. obesinymphae Aoki form a monophyletic clade within the North American Pemphigus group. They are sympatric on the eastern cottonwood, Populus deltoides (Salicaceae), but have distinctly different life cycles, with sexual stages offset by approximately six months. Field evidence indicates that intermediate phenotypes do not commonly occur, and mitochondrial and bacterial endosymbiont DNA sequences show no maternal gene flow between the two species. Because a genetically distinct population of P. obesinymphae occurs in the southwestern United States on Populus fremontii, we consider the possibility of an initial allopatric phase in the divergence. We discuss the likely origins of the host use patterns in P. obesinymphae, and the larger sequence of evolutionary changes that likely led to the sympatric divergence of P. populi-transversus and P. obesinymphae. A plausible interpretation at this stage of investigation is that a shift in timing of the life cycle in an ancestral population, correlated with an underlying phenological complexity in its host plant, spurred divergence between the incipient species.

Animals↗
PubMed1992

Equilibrium model for speciation of aluminum in serum.

An equilibrium model for the speciation of Al3+ in normal serum has been developed in which 81% of the aluminum is bound to transferrin. The remaining 19% exists primarily as Al(PO4)(OH)-, with minor amounts of citrate and hydroxide species. The model meets several key criteria. The concentration of free aluminum is below the upper limit set by the solubility product of aluminum phosphate. The fraction of low-molecular-mass aluminum species agrees with experimental studies on the fraction of ultrafiltrable aluminum in both normal and uremic serum. Lastly, the model accounts for the relative effectiveness of EDTA, citrate, and desferrioxamine B for binding aluminum in serum by including competition from zinc, magnesium, and calcium for these ligands. Uncertainties in the available thermodynamic database are discussed.

Aluminum↗
PubMed2004

[The genetic evidence for sympatric speciation pattern of Cyprinus from Erhai Lake].

In the present paper, mtDNA RFLP and mtDNA D-loop sequencing were investigated in three species of Cyprinus from Erhai Lake. The results indicated that two mtDNA haplotypes were identified in three species of Cyprinus from Erhai Lake by using 16 restriction endonucleases. All individuals share the dominant type I except one individual of C. longipectoralis shows type II just with only one cleavage site polymorphism when tested by Dra I. Compared to the reported interspecific and intraspecific sequence divergence in fishes, the present divergence values of 0% - 0.0075% from the Cyprinus species native to Erhai Lake were too much lower. Furthermore, 449 bp of mtDNA D-loop region sequencing was investigated in these three Cyprinus species. There were six mtDNA haplotypes indicated by seven variation sites. The interspecific sequence divergence were 0.082% - 0.171%. It is also at least one degree lower than some allopatric Cyprinus species we studied. A remarkably low level of genetic divergence detected among the three species of Cyprinus species in Erhai Lake both by mtDNA RFLP and D-loop region sequencing provides direct genetic evidence for its sympatric speciation pattern, which could occurred without progressive adaptive genetic variation.

Animals↗
PubMed2004

Plasma-source mass spectrometry for speciation analysis: state-of-the-art.

Current and emerging capabilities of plasma-source mass spectrometry (PS-MS) as it is employed for elemental speciation analysis are reviewed. Fundamental concepts and their advantageous aspects, experimental conditions, and analytical performance are described and illustrated by recent examples from the literature. Novel instrumentation, techniques, and strategies for inductively-coupled plasma mass spectrometry (ICP-MS), microwave-induced plasma (MIP) mass spectrometry, glow-discharge (GD) mass spectrometry, and electrospray ionization (ESI), among others, are described. The use of ionization sources that provide tunable ionization, others that can be modulated between different sets of operating conditions, and others used in parallel is also examined.

Lasers↗
PubMed2004

[Preliminary attempt at the speciation of 25-elements in the Chinese medicinal herbs].

OBJECTIVE: To make an attempt at the multi-element speciation in the Chinese medicinal herbs by determining the concentrations of 25 elements in different extraction solutions. METHOD: Firstly, five Chinese medicinal herbs (Buddleja officinalis, Dictamnus dasycarpus, Myristica fragrans, Albizia judibrissin and Inula japonica) from the same region of China were treated to obtain water-soluble phase, lipid-soluble phase and non-soluble phase by water extraction, organic solvent extraction and acid digestion, respectively. Secondly, Phytolacca acinosa, a Chinese medicinal herb collected from 9 regions of China, was extracted by 0% EtOH, 50% EtOH, 75% EtOH, 95% EtOH, respectively, referring the Chinese Pharmacopoeia. Finally, the concentrations of 25 elements, such as Be, Cr, Cu, Zn, Ge, Sr, Y, Mo, Cd, Tl, Pb and REEs, in the above three phases were determined by ICP-MS. RESULT: Under the optimal conditions, all the 25 elements could be determined with detection limits ranged from 0.003 to 0.71 ng x g(-1). The average recoveries of the elements in P. acinosa were 88% approximately 119%, with the relative standard deviations 1.7% approximately 13.3%. It was observed that the determined 25 elements distributed in all the water-soluble, lipid-soluble and non-soluble phases, indicating that the inorganic species, organicspecies, as well as the protein bound species were coexisted in the herbs. Big differences of the element extraction rates could be found by using different ethanol solutions. CONCLUSION: With the aid of the obtained results, we may increase the extraction of necessary elements while decrease that of the toxic elements from the herbs by choosing a suitable solvent during the drug production.

Buddleja↗
PubMed2004

Chromatographic speciation of anionic and neutral selenium compounds in Se-accumulating Brassica juncea (Indian mustard) and in selenized yeast.

Selenium-accumulating plants such as Brassica juncea (Indian mustard) concentrate the element in plant shoots and roots. Such behavior may provide a cost-effective technology to clean up contaminated soils and waters that pose major environmental and human health problems (phytoremediation). Such ability to transform selenium into bioactive compounds has important implications for human nutrition and health. Element selective characterization of B. juncea grown in the presence of inorganic selenium under hydroponic conditions provides valuable information to better understand selenium metabolism in plants. The present work determines both previously observed organoselenium species such as selenomethionine and Se-methylselenocysteine and for the first time detects the newly characterized S-(methylseleno)cysteine in plant shoots and roots when grown in the presence of selenate or selenite as the only selenium source. A key feature of this study is the complementary role of selenium and sulfur specific chromatographic detection by HPLC with interfaced inductively coupled plasma mass spectrometry (ICP-MS) detection and by derivatization GC with interfaced atomic spectral emission. HPLC-ICP-MS limits of detection for such species were in the range 5-50 ng Se mL(-1) in the injected extracts. Speciation profiles are compared with those of selenium-enriched yeast by both HPLC-ICP-MS and GC-AED.

Anions↗
PubMed2004

Selenium speciation in human serum of cystic fibrosis patients compared to serum from healthy persons.

A formerly developed Se speciation method was applied to human serum. Chomatographic performance was checked regularly by measuring control standards after four sample run, each, to ensure sufficient separation of the species and sensitivity of the method even after a considerable number of serum samples. Detection limits of investigated species were similar to those reported and showed values below 1 microg/L related to Se for each Se compound. Sera of cystic fibrosis (CF) patients were investigated in comparison to sera from healthy volunteers with respect to total selenium and Se species. Generally, CF sera showed lower values of total Se, Selenocystine (SeC), and cationic/neutral Se compounds compared to serum of healthy persons. No significant gender-specific differences were found. Total Se in sera of healthy persons was determined at 102+/-12 microg/L (n = 12 individuals, mean value from male and female, age 4-38 years), whereas CF patients showed 58+/-10 microg/L (n = 31 individuals, mean value from male and female, age 3-35 years). Se-cystine showed significant differences between the CF and healthy group with a lowered SeC value in sera of CF patients by -75% (mean ca. 26 microg/L in healthy sera compared to about 6.5 microg/L (mean) in CF sera). A similar situation is seen for neutral/cationic Se compounds, which partly may comprise of Se proteins. The lowered SeC values together with lowered cationic/neutral Se compounds (probably Se enzymes) point to a Se-depleted regulated pathway combined with a reduced capability of protective functions such as protection from peroxides.

Case-Control Studies↗
PubMed2004

Evaluation of a personal and microenvironmental aerosol speciation sampler (PMASS).

In this study, an all-aluminum sampler was reconfigured to a lighter weight by using plastic for structural components not contacted by aerosol. Because the sampler body was made of plastic, the aluminum size-selective cyclone inlet was redesigned into a separate, removable unit. The resulting personal and microenvironmental aerosol speciation sampler (PMASS*) is a small, compact sampler designed for assaying concentrations of each major chemical constituent of particulate matter less than or equal to 2.5 pm in aerodynamic diameter (PM2.5) as well as its mass. The sampler consists of a miniature cyclone inlet and two parallel sampling channels, each of which may accommodate a denuder, particle filter, and backup filter. One channel serves to measure mass and inorganic ions; the other, organic and elemental carbon. Six of these samplers were first evaluated in the laboratory to verify the 50% cutpoint of the redesigned cyclone inlet near the target flow rate of 4.0 L/min and to test the effect of sampler orientation, aerosol type, and flow rate on the 50% cutpoint. The six samplers were fabricated at two different times with slight modifications in construction that yielded slightly different 50% cutpoints. The units were then evaluated as microenvironmental samplers under field conditions against reference samplers in Fresno, California, and Baltimore, Maryland. Testing in Maryland also included deployment as a personal sampler. In the laboratory, the mean (+/- SD) 50% cutpoint at a 4.1 L/min flow rate was 2.52 +/- 0.08 pm. Sampler orientation did not affect performance of the cyclone. Small differences in penetration efficiency were found with different challenge aerosols. For flow rates between 3.1 and 4.9 L/min, the 50% cutpoint varied from 3.3 pm to 2.1 pm, respectively. As a microenvironmental sampler, the PMASS performed well against relevant reference samplers for elemental carbon, organic carbon, and nitrate measurements but not for mass measurements, for which the PMASS showed a significant bias of -34%. Precision estimates for PMASS elemental carbon, organic carbon, nitrate, and mass, respectively, were 6.8%, 9.0%, 11.9%, and 12.7% in Fresno and 6.6%, 8.7%, 13.6%, and 17.5% in Baltimore. For personal sampling, PMASS measurements of mass again showed a significant bias of -24% compared with the reference sampler. Precision estimates for the PMASS as a personal sampler for elemental carbon, organic carbon, nitrate, and mass were 8.1%, 19.3%, 19.1% and 24.2%, respectively. Sulfate data were not analyzable because of the large magnitude and variability of the sulfate blanks. Field testing revealed some deformation of components of the PMASS filter pack. These problems may have affected the integrity of the particle filter.

Aerosols↗
PubMed2005

[Speciation analysis of mercury in traditional Chinese medicine by vapor-generation atomic fluorescence spectrometry].

A sensitive method has been proposed for the determination of inorganic mercury and total organic mercury in traditional Chinese medicine (Wanshi Niuhuang Qingxin) by vapor-generation atomic fluorescence spectrometry. The experimental conditions that influence the atomic fluorescence signal intensity of Hg and the oxidization of organic mercury were investigated and optimized. Thiourea citric acid was selected as a sensitization agent, which greatly enhanced atomic fluorescence signal intensity of mercury. The influence of foreign ions and their elimination were studied. The detection limit of the method for Hg was 7.6 ng x L(-1) and the relative standard deviation was 1.56%-3.28% for Hg. The proposed method was successfully applied to the determination of mercury speciation in real samples with a recovery range of 90.3%-110.3%.

Citric Acid↗
PubMed2005

[Analysis and separation of organic and inorganic speciations of soluble zinc in edible flowers].

Considering the medicinal effects of the edible flowers, the authors studied the separation of trace element zinc's soluble organic and inorganic speciations in water decoction of three edible flowers: Chrysanthemum, Cottonrose hibiscus and Honeysucker by using the 0.45 microm membrane filter and amberlite XAD-2 macroreticular resins. And trace element zinc contents were determined by atomic absorption spectrometry. The optimal conditions for separation had been established. This study verifies the economic value of developing edible flowers, and provides theoretical basis for developing edible flowers as the third functional food materials.

Chrysanthemum↗