Chemistry and biodiversity: Darwinism, evolution, and speciation. An opposing view.
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Animals↗
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Capillary electrophoresis interfaced to inductively coupled plasma mass spectrometry for element selective detection in arsenic speciation.
A method is presented to separate and detect six arsenic species by capillary electrophoresis (CE) interfaced to inductively coupled plasma mass spectrometry (ICP-MS). CE was used as a highly resolving separation system, whereas ICP-MS served as an element selective detector providing low detection limits. The special mode of operation included sample stacking and a differentiation of separation and detection. This provided separation and detection of six As species, uncharged and anionic, to be monitored within a single run. Detection limits were calculated according to IUPAC recommendation at 15 microg As/L for As (III), dimethyl arsinic acid (DA), monomethyl arsonic acid (MA) and As (V), or 65 microg As/L for arsenobetaine (AsB) and arsenocholine (AsC). Investigations were focused on possibly occurring interferences, e.g., ArCl+ interference at the monoisotope 75As. Finally, real samples from biomedical field (urine) and environmental field (sewage sludge) were analyzed.
Anions↗
Speciation of chromium (III) and chromium (VI) by capillary electrophoresis with contactless conductometric detection and dual opposite end injection.
A sensitive, rapid and inexpensive capillary electrophoretic method for the determination of Cr(III) and Cr(VI) species is presented. The method is based on the dual opposite end injection principle and contactless conductometric detection. The sample containing cationic and anionic species is injected into the opposite ends of the separation capillary and after the high voltage is applied, the analytes migrate towards the capillary center, where the cell of a contactless conductivity detector is placed. The method does not require any sample pretreatment, except dilution with deionized water. The separation of Cr(III), Cr(VI) and other common inorganic anions and cations is achieved in less than 4 min. The parameters of the separation electrolyte solution, such as pH and concentration of L-histidine, were optimized. Best results were achieved with electrolyte solution consisting of 4.5 mM L-histidine, adjusted to pH 3.40 with acetic acid. The detection limits achieved for Cr(III) and Cr(VI) were 10 and 39 microg.L(-1), respectively. The repeatability of migration times and peak areas was better than 0.3% and 2.8%, respectively. The developed method was applied to the analyses of rinse water samples from the galvanic industry. The results for the determination of Cr(III) and Cr(VI) were in good agreement with the results obtained by certified differential spectrophotometric method using diphenylcarbazide (CN 83 0520-40) and with the results for the total chromium concentrations determined by electrothermal atomic absorbance spectrometry (ET-AAS) and inductively coupled plasma-mass spectrometry (ICP-MS).
Acetic Acid↗
Immunological factors in Peromyscus speciation.
Reciprocal interspecific F1 hybrids of deermice (Peromyscus maniculatus) and oldfield mice (P. polionotus) differ significantly and substantially in fetal and placental, as well as adult, size and weight. Hybrid fetal mortality is associated with large conceptus size. Skin grafts were exchanged between and within the two species to ascertain whether any relationship exists between mean graft retention time and body size of fetuses and adults. P. maniculatus skin grafted to P. polionotus rejected significantly earlier than the reciprocal xenograft. All interspecific graft combinations rejected significantly earlier than intraspecific grafts. Pre-immunization of female P. maniculatus with con- and trans-specific paternal spleen cell antigens reduced fetal, placental, neonatal, and ten-day size compared with controls. Size, weight, fertility, and graft rejection data were compared with several theoretical models. The data were consistent with the hypothesis that immunological disparity between the species could produce marked size variations in reciprocal hybrids. Multiple minor histocompatibility factors can account for large placental size and fetal mortality in Peromyscus hybrids. Physiological reproductive isolation may result from immunological differences between closely allied species.
Animals↗
Is high-resolution magic angle spinning NMR a practical speciation tool for cheese samples? Parmigiano Reggiano as a case study.
High-resolution magic angle spinning (HRMAS) NMR is probably the most apt NMR method to analyze complex materials involving a solid phase, e.g. foodstuffs. We present here an HRMAS analysis of grated cheese (Parmigiano Reggiano). A full NMR characterization of this cheese allows the identification of the presence of fatty acids (saturated and unsaturated), amino acids and other small organic molecules. Since the presence and relative concentration of these molecules have previously been shown to correlate with organoleptic, origin and age characterization, HRMAS NMR of cheese is likely to provide a good complimentary tool for the analysis of this food material.
Amino Acids↗
Speciation analysis and the assessment of bioavailability of manganese in phytomedicines by extraction with octanol and determination by flame atomic absorption spectrometry.
Trace elements in phytomedicines are present in the form of metallic complexes. Since n-octanol, a long-chain alkanol, presents a configuration similar to that of carbohydrates and lipids, the lipophilicity and absorptivity of organic medicines may be assessed from their distribution coefficients between octanol and water. This strategy has been used in order to define the species of manganese in a number of phytomedicines and to study the distribution of manganese in decoctions of phytomedicines in the stomach and the intestine. The concentrations of manganese in the original herbal materials and in octanol- and water-soluble fractions were determined by flame atomic absorption spectrometry following mixed acid digestion. The acidities of gastric and intestinal juices, the phytomedical composition and the compatibility of phytomedicines, i.e. the combination of single phytomedicines, greatly affected the manganese complexing ligands and determined the species and bioavailability of manganese. It is concluded that a knowledge of the level of octanol-soluble manganese in a phytomedicine could form the basis of dosage design in order to avoid manganese overload.
Acids↗
Copper(II) complexation properties and surfactant activity of 3-[N, N-bis(2-hydroxyethyl)amino]-2-hydroxypropanesulfonic acid and N-(2-Hydroxyethyl)piperazine-N'-2-hydroxypropanesulfonic acid pH buffers which may affect trace metal speciation in in vitro studies.
Disadvantages of the some zwitterionic pH buffers are (i) that they can interact with metal ions as well as protons, and (ii) that they may have a surfactant effect in chemical or in vitro biological or biochemical studies. This has to be taken into account when a buffer is selected. Here, the copper-complexing capacity and the surfactant activity of three compounds, 3-[N,N-bis (2-hydroxyethyl)amino]-2-hydroxypropanesulfonic acid (DIPSO), N-(2-hydroxyethyl)piperazine-N'-(2-hydroxypropanesulfonic acid) (HEPPSO), and piperazine-N,N'-bis(2-ethanesulfonic acid) (Pipes), were investigated. Global stability constants (log betaabc) of copper(II)-buffer complexes were determined, at 25 degrees C, 0.5 M ionic strength, and at 0.8 mM buffer concentration, by pH and pCu ion-selective electrode measurements. Here, betaabc corresponds to the equilibrium: aCu2+ + bL- + cH+ left and right arrow (CuaLbHc)(2a-b+c); HL = DIPSO or HEPPSO; c: +1 = proton; -1 = hydroxide. Using SUPERQUAD constants were calculated, giving: DIPSO: log beta110 = 5.02, log beta120 = 8.99, log beta130 = 13.0, log beta140 = 16.3, log beta14-1 = 9.26, log beta14-2 = 0.645, log beta150 = 20.5, log beta160 = 24.3, log beta16-1 = 16.1, log beta16-2 = 8.98; HEPPSO: log beta110 = 4.29, log beta120 = 8.35, log beta130 = 12.1, log beta140 = 15.9, log beta150 = 19.6, log beta160 = 23.4, log beta16-1 = 14.9. The pKa values were determined at higher buffer concentrations, giving a value 7.33 for DIPSO and 7.84 for HEPPSO at 2.0 mM buffer concentration. Effects of buffer concentration on stability and acidity constants were investigated and compared with measurements using voltammetric and potentiometric stripping analysis, confirming no copper(II) complexation by Pipes. Surfactant activities were determined using alternating current polarography, confirming marked surface activity of 10 mM of DIPSO or HEPPSO.
Buffers↗
Mate choice in divergent morphs of the gastropod mollusc Littorina saxatilis (Olivi): speciation in action?
We investigated mate choice in the gastropod Littorina saxatilis (Olivi) in the laboratory, using snails taken from two shores, 20 km apart. The snails occur in two distinct shell morphs in the high (H) and mid (M) shore zones, known to show signs of a postzygotic reproductive barrier between them. We found that mating was assortative not only between the forms H and M on a single shore, but also between snails from the two different shores. Mating preference appeared to be based on morph type over this distance. The snails may be detecting and responding to an extrinsic attribute reflecting a common microhabitat (but across a distance of 20 km), and/or an intrinsic attribute to do with the organisms themselves. These findings are further evidence of behaviour associated with the evolution of reproductive isolation in this gastropod species. Copyright 1999 The Association for the Study of Animal Behaviour.
Journal Article↗
Evidence for cadmium uptake through Nramp2: metal speciation studies with Caco-2 cells.
The specific uptake of 0.3 microM (109)Cd by the TC7 clone of the human enterocytic-like Caco-2 cells increased 4-fold as the pH(out) was lowered from 7.5 to 5.5; the stimulatory effect of acidic media being more pronounced when the level of the free ion (109)Cd(2+), relative to total (109)Cd, was increased. The initial uptake rate was 12-fold higher under conditions, optimizing (109)Cd(2+) accumulation over that of (109)CdCl(2-n)(n) (NO(-)(3)/pH(out) 5.5); a saturable system of transport has been characterized (K(m) = 1.1 +/- 0.1 microM, V(max) = 87 +/- 3 pmol/3 min/mg protein). An excess of Fe(2+) failed to affect (109)Cd uptake when the pH(out) was 7.4, whereas a strong inhibition was observed under NO(-)(3)/pH(out) 5.5 conditions. In contrast, the maximal inhibitory effect of Zn(2+) was observed under Cl(-)/pH(out) 7.4 conditions. This results strongly suggest that Fe(2+) may compete with Cd(2+) for Nramp2, whereas Zn and CdCl(2-n)(n) compete for another system of transport that has yet to be identified.
Acids↗
Trypanosoma cruzi: can activity of the rRNA gene promoter be used as a marker for speciation?
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Animals↗
Uranyl Surface Speciation on Silica Particles Studied by Time-Resolved Laser-Induced Fluorescence Spectroscopy.
The sorption of uranyl ions onto amorphous silica has been studied in the presence of atmospheric CO(2) by laser-induced time-resolved fluorescence spectroscopy at trace concentrations (1.0 and 0.1 &mgr;M). Two fluorescent uranyl surface complexes have been identified in the pH range 4 to 9. Both complexes could be differentiated by lifetimes (170+/-25 &mgr;s at low pH and 360+/-50 &mgr;s at high pH) and fluorescence emission spectra. Within the constant capacitance model framework they are described by mononuclear (1 : 1) complexes with release of two and three protons, respectively. When fluorescence data were compared to wet chemistry sorption data, a third "silent" ternary uranyl-silica-carbonate surface complex had to be postulated to account partly for adsorption between pH 8.0 and 9.0. Three independent data sets led therefore to the identification of three surface complexes, postulated as &tbond;SiO(2)UO(2) degrees,&tbond;SiO(2)UO(2)OH(-), and &tbond;SiO(2)UO(2)OHCO(3)(3-). Copyright 2001 Academic Press.
Journal Article↗
Gametic imprinting as a speciation mechanism in mammals.
Gametic imprinting renders mammalian male and female genomes functionally hemizygous at specific loci. Successful embryogenesis can only be accomplished in the presence of both parental genomes. The mechanism of gametic imprinting is at present unknown, although circumstantial evidence suggests it is similar in nature to X inactivation. A model is presented which describes the effects of switching the imprint pattern at male and female target genes. The consequence of such an event is reproductive isolation, and could lead to the formation of a new species.
Animals↗
Fine tuning of intracellular protein concentrations, a collective protein function involved in aneuploid lethality, sex-determination and speciation?
The assertion that sex chromosome dosage compensation arose because aneuploidy for an entire chromosome is lethal, begs the question of why aneuploidy is lethal. It has been proposed that aneuploid lethality results from impairment of a collective protein function (Forsdyke, 1994, J. theor. Biol. 167, 7-12). Cytosolic proteins, by virtue of their concentrations, exert a pressure tending to drive members of individual protein species into self-aggregates. Other evolutionary time, each gene has fine-tuned the concentration of its product to a maximum consistent with avoiding self-aggregation in the crowded cytosol. Because of this aggregation pressure and the imprecision of their own fine-tuning, the proteins of members of other species, the corresponding genes of which may have been transported to a cell as viruses (or gametes), are specifically aggregated. The death of the cell and its enclosed virus results. Aneuploidy impairs this process, with lethal consequences for the organism. The hypothesis leads to explanations for a variety of phenomena. On the assumption that the concentration of autosomal products determines cell volume, the observed dependence of sex-determination on the ratio of X chromosomes to autosomes is shown merely to be a dependence on the concentration of the products of one X chromosome. The inviability of the heterogametic sex among the offspring of an interspecies cross (Haldane's rule), follows from the species-specific fine-tuning of the concentrations of X chromosome-encoded products relative to the concentration of autosomally-encoded products. Species may initially have evolved as a barrier behind which fine-tuning could occur to protect cells against intracellular pathogens.
Aneuploidy↗
Genetic divergence and speciation in an extremely young species flock in Mexico formed by the genus Cyprinodon (Cyprinodontidae, Teleostei).
The lake Laguna Chichancanab contains one of the evolutionarily youngest species flocks known, composed of five endemic species of the genus Cyprinodon. The presumed sister species Cyprinodon artifrons still exists in marine coastal habitats. Sequences of the mitochondrial control region were obtained for C. artifrons (genes of 17 individuals sequenced) and for all five endemic species (genes of 32 individuals sequenced). While nine different haplotypes were found in C. artifrons, only a single haplotype was shared with the species from the laguna. Four additional haplotypes were found among the endemics. These four were most closely related to that single haplotype shared with C. artifrons. The deprivation in haplotypes among the endemics points to a small founder population or to bottlenecking. The distribution pattern of overlapping haplotypes in four of the five species suggests incomplete lineage sorting or hybridization among them. Complete reproductive isolation is only assumed for one species, C. maya, in which a single and unique haplotype was found.
Animals↗
The molecular phylogenetics of tuco-tucos (genus Ctenomys, Rodentia: Octodontidae) suggests an early burst of speciation.
Variation in the nucleotide sequence of the entire mitochondrial cytochrome b gene (1140 bp) was examined for 27 individuals representing 13 species of South American rodents of the genera Ctenomys, Octodontomys, Tympanoctomys, and Spalacopus. Representatives of the family Echimyidae, Euryzygomatomys and Mesomys, were used as outgroups to test the monophyly of the Octodontinae and Ctenomyinae. Relationships among species of tuco-tucos (genus Ctenomys) were also examined including representatives of the three described subgenera and the two sperm morphs. Reciprocal monophyly of the Octodontinae and Ctenomyinae is strongly supported. Several basal relationships among species of the genus Ctenomys are poorly resolved, suggesting the possibility of a hard polytomy due to a rapid and potentially simultaneous radiation early in the history of the genus. In other cases, clades within the Ctenomyinae previously identified on the basis of allozymes, chromosomes, parasites, or skull morphology were supported. Calibrations based on the fossil record suggest that the mitochondrial cytochrome b of these caviomorphs has evolved at a rapid rate, comparable to those proposed for Mus-Rattus, and three to four times higher than ungulate rates.
Animals↗
Molecular phylogeny and speciation of the surfperches (Embiotocidae, Perciformes).
Labroid fishes include a variety of families, such as wrasses (Labridae), odacids (Odacidae), damselfishes (Pomacentridae), parrotfishes (Scaridae), cichlids (Cichlidae), and surfperches (Embiotocidae). With only 23 species, the small embiotocid family exhibits a remarkably low species diversity compared to the large species diversity of the Cichlidae. Using mitochondrial DNA sequences of all 14 extant embiotocid genera, we established a molecular phylogeny of the family and compared it with a previously proposed morphological phylogeny. Genetic differentiation among embiotocids was compared to that among cichlids. Although species numbers are extremely different between these two families, the degrees of genetic differentiation within each family was found to be very similar.
Animals↗
Phylogenetic relationships, morphological incongruence, and geographic speciation in the fontinalaceae (Bryophyta).
Nuclear ribosomal DNA (internal transcribed spacer region) and chloroplast DNA (trnL-trnF region) were sequenced from 40 samples representing all three genera (Brachelyma, Dichelyma, and Fontinalis) and 18 species of the aquatic moss family, Fontinalaceae. Phylogenetic reconstructions recovered from separate and combined analyses were used to test the hypotheses that Fontinalis and Dichelyma are monophyletic (Brachelyma is monotypic), that groups of species within Fontinalis based on leaf morphology (keeled, concave, plane) form monophyletic groups, and that species delineation based on morphological characters within Fontinalis are congruent with nr- and cpDNA gene trees. Using Brachelyma subulata to root the tree, both Dichelyma and Fontinalis are monophyletic and patristically divergent (each united by >15 synapomorphic mutations). Groups of species within Fontinalis defined by leaf morphology are polyphyletic and it is clear that leaf morphology is labile in the genus. As defined morphologically, species of Fontinalis are nonmonophyletic for both nr- and cpDNA sequences and populations of some morphological taxa are separated in widely divergent clades. Molecular evidence suggests that at least some morphospecies are artificial, defined by convergent leaf forms. The weight of the evidence indicates that F. antipyretica is positively paraphyletic, with European populations more closely related to (i.e., share a more recent common ancestor with) European endemic species than to North American populations that are morphologically conspecific. North American populations are more closely related to North American endemic species.
Bryopsida↗
Phylogeography and speciation of the morphologically variable, widespread species Bufo valliceps, based on molecular evidence from mtDNA.
The widespread, lowland toad Bufo valliceps has an unusual distribution in North and Middle America that straddles two major biogeographic areas; previous morphological studies of this species suggested the existence of two species. We used mitochondrial DNA sequences to examine the phylogeography of this species and discovered the existence of two distinct clades. We recognize these as two species: B. valliceps and B. nebulifer. These molecular data support morphological data from previous studies. Our results show low levels of molecular variation in a morphologically uniform temperate species (B. nebulifer) and high levels of molecular variation in a morphologically variable tropical species (B. valliceps), providing an example of molecules matching morphology. Two biogeographic hypotheses are tested to explain the current distribution of these species, based on a calibrated rate of evolution and the percent sequence divergence between the two species. A more recent Pleistocene dispersal event, followed by vicariance associated with rising sea level, is rejected in favor of an earlier Miocene-Pliocene vicariant hypothesis associated with the formation of the Trans-Mexican Neovolcanic Belt.
Animals↗