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PubMedDate not supplied

The speciation of lead in erythrocytes in relation to lead toxicity: case studies of two lead-exposed workers.

Lead toxicity is known to be subject to individual susceptibility. This study compares two lead-exposed subjects, one (A; blood Pb 1800 micrograms/L) who remained totally asymptomatic, the other (B; blood Pb 1610 micrograms/L) who showed symptoms of toxicity. We have assessed the speciation of lead in the intra-erythrocyte proteins in these patients and have examined its significance in relation to clinical toxicity. Chromatographic separations of erythrocyte haemolysates from these patients showed a metallothionein-like lead containing protein. It was demonstrated that in patient A, most (approximately 70%) of the erythrocyte lead was associated with this protein, whilst in patient B the protein only contained about 20% of the total lead, with significant amounts bound to high molecular weight proteins, including Hb. Further purification of this protein from each patient showed it to contain a number of constituents, one in particular being the major lead-binding species. This component was more abundant in patient A and, relative to patient B, contained a higher proportion of lead. These results suggest that this protein may act to sequester lead into a non-bioavailable form, hence protecting the body from lead toxicity as with patient A.

Adult↗
PubMedDate not supplied

Speciation analysis of organolead compounds in wine by capillary gas chromatography/microwave-induced-plasma atomic emission spectrometry.

A method was developed for the speciation analysis of ionic organolead compounds in wine. The analytes were extracted as diethyldithiocarbamate complexes into hexane and propylated with a Grignard reagent. The derivatized extract was analyzed by capillary gas chromatography/microwave-induced-plasma atomic emission spectrometry. The method of standard additions was used for calibration to correct for variable recoveries and signal enhancements. Red, rosé, and white wines from southern France were analyzed. Trimethyllead was the ubiquitous species. The wines made from grapes grown close to industrial zones showed elevated concentrations of ethyllead species. The concentrations of methyllead and ethyllead found in wines were compared with the concentrations of organolead found in rain water and plant sap collected in the viticultural regions. The ratio of methyllead to ethyllead in wines greatly exceeded the same ratio found in atmospheric deposits.

Chromatography, Gas↗
PubMed1977

Modified Sutter's arginine dihydrolase medium for Pseudomonas speciation.

Sutter's arginine dihydrolase medium has been modified to obtain maximum yields of arginine dihydrolase. Bromothymol blue is the indicator for alkalinity in Sutter's medium. By adding glucose and lowering the pH of the medium, more positive reactions were obtained in 24 hr as well as a sharper color contrast to the base medium which facilitated reading the reactions. The modified Sutter's medium was included in the routine biochemical schema for speciation of pseudomonads isolated from cosmetic products. Of the 706 strains belonging to the 5 species isolated form cosmetic products, only one false negative reaction was obtained with a strain of Pseudomonas putida. The medium was also used for the biochemical characterization of 122 Pseudomonas sp. isolates.

Arginine↗
PubMed1998

Polymerase chain reaction and restriction fragment length polymorphism mediated detection and speciation of Candida spp causing intraocular infection.

PURPOSE: To determine the usefulness of polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis in the identification and speciation of Candida spp that causes ocular infection. METHODS: Oligonucleotide primers based on the cytochrome P450 L1 A1 demethylase gene were used to successfully amplify by PCR a single 1.0-kb and a single 500-bp DNA fragment from C. albicans, C. tropicalis, C. krusei, C. glabrata, C. parapsilosis, and C. pelliculosa genomic DNA. RFLPs within the PCR product were identified after restriction enzyme digestion. RESULTS: The sensitivity of the amplification reaction after two rounds of PCR was 10 fg genomic C. albicans DNA or one copy of the gene. No amplification product was obtained when DNA from C. guilliermondii, Aspergillus fumigatus, Fusarium solani, human leukocytes, or 10 species of bacteria was used as a template. Experiments with spiked normal vitreous demonstrated equal sensitivity as long as the volume of vitreous did not exceed 20% of the total PCR volume. RFLP analysis of the PCR product generated from each species obtained from the first- and second-round amplification products enabled species identification after digestion with specific endonucleases. Application of the technique to four clinical samples was successful. CONCLUSIONS: It is expected that the simplicity of the DNA extraction technique allied with the broad specificity of the outer primers for all ophthalmically relevant Candida spp and the sensitivity of the second-round PCR will aid in the detection of fungal DNA in small intraocular samples. PCR-RFLP analysis has great potential in the rapid detection and identification of Candida spp and in the provision of a useful laboratory tool for the future.

Aqueous Humor↗
PubMed2026

Genome-wide insights into the evolutionary and demographic history of the red alga Mazzaella laminarioides: Evidence for speciation with ancient migration along the southeast Pacific coast.

The mechanisms driving lineage divergence in red algae remain unexplored, despite the group's remarkable diversity and ancient evolutionary history. The red alga Mazzaella laminarioides, a Chilean intertidal species complex composed of three parapatric cryptic lineages (North, Center, South), offers a valuable system to evaluate these processes, as its life history combines severe dispersal limitation with a haploid-diploid cycle that may influence the emergence of reproductive barriers. We reconstructed its evolutionary history using whole-genome sequencing and nuclear genome assembly of representative individuals from each lineage. Phylogenomic analyses based on 1,507 single-copy orthologs recovered three deeply divergent lineages with limited nuclear discordance consistent with incomplete lineage sorting. For both splits, demographic modelling was most consistent with an Ancient Migration scenario, although support over strict isolation was moderate, suggesting that divergence may have begun with low asymmetric ancestral gene flow followed by subsequent loss of connectivity, demographic bottlenecks, and later population expansion. Coding sequence analyses revealed lineage-specific dN/dS heterogeneity; only one South-lineage locus passed FDR correction (metaxin-1, mitochondrial protein import), with two further South-lineage candidates in chlorophyll and heme biosynthesis falling below the FDR threshold. Together, these signals suggest that divergent selective pressures on energy acquisition may have contributed to divergence at the southern end of the distribution. These results add to the small but growing body of whole-genome data for red algae and, alongside recent macroalgal studies, suggest that ancestral connectivity could be a recurrent feature of lineage divergence even in marine organisms with extremely restricted dispersal.

Rhodophyta↗
PubMed2025

Repeatable Genomic Outcomes Along the Speciation Continuum: Insights From Pine Hybrid Zones (Genus Pinus).

Hybridization is a widespread evolutionary process and a key source of evolutionary novelty. Despite intensive study, the extent to which hybridization is deterministic and repeatable, particularly in recurrent contact events involving the same species under varying ecological conditions, remains unclear. Here, we investigated three replicated contact zones between Scots pine (Pinus sylvestris) and dwarf mountain pine (Pinus mugo) in Central Europe: two occurring in peatland habitats and one in a contrasting sandstone outcrop. Using genome-wide SNP genotyping of over 1300 individuals, we analysed genomic structure, diversity, and ancestry patterns across these zones. All sites revealed pervasive hybridization, dominated by later-generation hybrids and a notable scarcity of pure P. mugo. Across environments, hybrid populations exhibited strikingly consistent genomic compositions, with asymmetric introgression strongly biased toward P. mugo ancestry, suggesting that hybrid genome structure may follow predictable patterns under similar ecological conditions and could be shaped by cytonuclear incompatibilities. Nonetheless, we also detected site-specific differences in hybrid diversity and phenotype, highlighting the influence of local environmental selection on shared hybrid genomic backgrounds. We provide genomic evidence that Pinus uliginosa, a morphologically distinct peat bog pine traditionally regarded as a relict and endangered species is instead a partially stabilised hybrid lineage. Its genome reflects incomplete hybridization and ecological filtering, yet it lacks sufficient genetic divergence to be recognised as a distinct species. Together, these results provide evidence for the repeatability of hybridization processes, which result in the formation of phenotypes reflecting a species continuum subjected to strong environmental pressures. The findings support the simplification of taxonomic nomenclature within the Pinus mugo complex, informing adaptive conservation strategies and the genetic management of hybrid lineages.

Hybridization, Genetic↗
PubMed2006

Heritability and heterochrony of polychromatism in a Lake Victoria Cichlid fish: Stepping stones for speciation?

In many haplochromine cichlid fish, male nuptial coloration is subject to female mate choice and plays a central role in the evolution of reproductive isolation between incipient species. Intraspecific variation in male coloration may serve as a target for diversifying sexual selection and provide a starting point for species divergence. Here, we investigated a polychromatism in Neochromis omnicaeruleus, a haplochromine from Lake Victoria, East-Africa. In this species, male coloration ranges from skyblue to yellow-red and females are grey-blue to yellow. We found that both genetic and environmental factors influence the expression of these colours during individual development. In a natural population, we found that male colour was associated with size and sexual maturity: yellow males were smaller than blue males and tended to be sexually immature. In females, size and maturity did not differ between colour types. Laboratory crosses revealed that there is a heritable component to the observed colour variation: yellow parents produced more yellow offspring than blue parents. Together with repeated aquarium observations of yellow individuals that gradually become blue, these data suggest that yellow males change to blue as they approach sexual maturity, and that the occurrence and timing of this transition is influenced by both environmental and genetic effects. The significance of this mechanism of colour expression as a possible target for divergent selection remains to be evaluated.

Africa, Eastern↗
PubMed2006

Natural selection and divergence in mate preference during speciation.

Sexual isolation can evolve due to natural selection against hybrids (reinforcement). However, many different forms of hybrid dysfunction, and selective processes that do not involve hybrids, can contribute to the evolution of sexual isolation. Here we review how different selective processes affect the evolution of sexual isolation, describe approaches for distinguishing among them, and assess how they contribute to variation in sexual isolation among populations of Timema cristinae stick-insects. Pairs of allopatric populations of T. cristinae living on different host-plant species exhibit greater sexual isolation than those on the same host, indicating that some sexual isolation has evolved due to host adaptation. Sexual isolation is strongest in regions where populations on different hosts are in geographic contact, a pattern of reproductive character displacement that is indicative of reinforcement. Ecological costs to hybridization do occur but traits under ecological selection (predation) do not co-vary strongly with the probability of between-population mating such that selection on ecological traits is not predicted to produce a strong correlated evolutionary response in mate preference. Moreover, F1 hybrid egg inviability is lacking and the factors contributing to reproductive character displacement require further study. Finally, we show that sexual isolation involves, at least in part, olfactory communication. Our results illustrate how understanding of the evolution of sexual isolation can be enhanced by isolating the roles of diverse ecological and evolutionary processes.

Adaptation, Biological↗
PubMed2006

Vicariance, colonisation, and fast local speciation in Asia Minor and the Balkans as revealed from the phylogeny of spined loaches (Osteichthyes; Cobitidae).

We reconstruct the phylogeny of the morphologically diagnosable subgenera Bicanestrinia, Beysehiria, and Cobitis sensu stricto of the genus Cobitis from Asia Minor and the Balkans. We used the complete cytochrome b gene of 65 specimens in order to infer their evolutionary history in this zoogeographically interesting area. Our phylogeographic analysis did not evidence the previously suggested monophyly of the Bicanestrinia subgenus but revealed five monophyletic lineages in the area: the lineages Bicanestrinia I-IV including all species of Bicanestrinia plus the lineage Cobitis s. str. The monotypic subgenus Beysehiria from Lake Beysehir in Anatolia was closely related to the syntopic population of C. turcica and nested inside the lineage Bicanestrinia III. The strictly allopatric distribution of the four lineages of Bicanestrinia suggests that vicariance has played a major role in the diversification of Bicanestrinia. All analysed species of Cobitis s. str. from Asia Minor and Balkans were closely related to Cobitis s. str. from Central Europe, the Danube basin and the Caucasus, indicating at least two colonisation events into Asia Minor and the Balkans. A third, recent colonisation event led to the presence of C. strumicae, generally restricted to the Aegean Sea drainage, in the Danube basin. Besides the evidences of vicariance and colonisation events in the phylogenetic history of the genus Cobitis in Asia Minor and the Balkans, our analysis suggested also a rapid morphological evolution of C. bilseli in a lacustrine environment. Application of Cobitis mitochondrial cytochrome b clocks of 0.68% sequence divergence per million years (MY) suggest that the split between the five major lineages happened approximately 12.4-17.6 MYA, and according to the lack of basal resolution of this monophyletic group probably the split of all lineages happened within a narrow time window.

Animals↗
PubMed2006

Budding speciation and neotropical origin of the Azorean endemic liverwort, Leptoscyphus azoricus.

The origin of plant species endemism in Macaronesia, one of the 25 world biodiversity hotspots, has traditionally been either interpreted as a result of the dramatic reduction of a broader tertiary distribution range during the Ice Age or neoendemism. This hypothesis is tested here in the context of a species-level phylogeny employing chloroplast trnL-trnF and atpB-rbcL sequences in the leafy liverwort genus Leptoscyphus (Lophocoleaceae). The data suggest that the Azorean endemic Leptoscyphus azoricus originated from parental populations of the Neotropical Leptoscyphus porphyrius by long-distance dispersal across the Atlantic and subsequent isolation. Possible reasons for the differences in the origin of endemism in angiosperms, wherein by far most endemic species have their close relatives on the European and North African continents, are discussed.

Genetic Speciation↗
PubMed2006

Genetic differentiation and cryptic speciation in natural populations of Drosophila lacertosa.

Drosophila lacertosa, an Oriental member of the robusta species group in the virilis-repleta radiation, has a wide distribution from northern India throughout China to the Far East. Phylogenetic analyses of mitochondrial ND2 gene sequences revealed two genetically significantly diverged lineages with 2.1% DNA sequence divergence. These two lineages are largely allopatric: one is mainly found in southwest China (lineage A), whereas the other ranges central and east of China to northeast Asia (lineage B). The geographic distributions of these two clades narrowly overlap near the provincial boundaries of Yunnan and Guizhou or Guangxi, probably as a consequence of population expansion and secondary contact. These two lineages were estimated to have diverged about 0.56 Mya, and the estimated time of expansion was approximately 70,000 years ago for lineage A population, and 110,000 years ago for lineage B population. The present molecular analysis, together with nearly complete reproductive isolation between those two lineages, strongly suggests that the two lineages might be incipient species.

Animals↗
PubMed2006

The speciation history of the Drosophila nasuta complex.

The Drosophila nasuta subgroup of the immigrans species group is widely distributed throughout the South-East Asian region, consisting of morphologically similar species with varying degrees of reproductive isolation. Here, I report nucleotide variability data for five X-linked and two mtDNA loci in eight taxa from the nasuta subgroup, with deeper sampling from D. albomicans and its sister species D. nasuta. Phylogenetic relationships among these species vary among different genomic regions, and levels of genetic differentiation suggest that this species group diversified only about one million years ago. D. albomicans and D. nasuta share nucleotide polymorphisms and are distinguished by relatively few fixed differences. Patterns of genetic differentiation between this species pair are compatible with a simple isolation model with no gene flow. Nucleotide variability levels of species in the nasuta group are comparable to those in members of the melanogaster and pseudoobscura species groups, indicating effective population sizes on the order of several million. Population genetic analyses reveal that summaries of the frequency distribution of neutral polymorphisms in both D. albomicans and D. nasuta generally fit the assumptions of the standard neutral model. D. albomicans is of particular interest for evolutionary studies because of its recently formed neo-sex chromosomes, and our phylogenetic and population genetic analyses suggest that it might be an ideal model to study the very early stages of Y chromosome evolution.

Animals↗