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PubMed2002

Molecular phylogeny of the Puerto Rican Lepidocyrtus and Pseudosinella (Hexapoda: Collembola), a validation of Yoshii's "color pattern species".

Color pattern was one of the most important characters used to diagnose species in the genus Lepidocyrtus until the introduction of chaetotaxy to Collembola taxonomy. Chaetotaxy confirmed most species diagnoses based only on color patterns, but a number of populations with distinct pigmentation patterns have been found to be identical in all other morphological characters. The absence of individuals showing intermediate color patterns prompted Yoshii to suggest that, despite chaetotaxic identity, populations with distinct color forms represent valid species (implying reproductive isolation and therefore biological species) in what he designated as "color pattern species." In Puerto Rico Lepidocyrtus biphasis, L. dispar, and L. caprilesi show a remarkable variation in pigmentation and as a group include 11 different color forms. Here I present a phylogenetic analysis of the cytochrome oxidase I gene (COI) in 17 species of Lepidocyrtus and Pseudosinella, including 11 species and 10 color forms of Puerto Rican Lepidocyrtus, to test Yoshii's color pattern species concept. The analysis shows large genetic distances between species defined based on morphology alone (morphospecies) and between most color variants within morphospecies. The most often used calibration for the COI molecular clock (2.3% sequence divergence per million years) suggests that morphospecies diverged between 20 and 25 million years before present while color forms within morphospecies diverged between 8 and 19 million years ago. This indicates that changes in climate and sea levels during the Pleistocene were irrelevant to the speciation process in the Puerto Rican Lepidocyrtus. Examination of the genetic variation, phylogenetic relationships, and collection data in light of the biological and phylogenetic species concepts supports the hypothesis that most populations of morphospecies differing only in color pattern are distinct species, thus validating Yoshii's color pattern species concept. As a result it is suggested that morphological characters traditionally used in species diagnoses are very conservative indicators of genetic divergence, that the diversity of springtails has been greatly underestimated, and that studies concerned with identifying factors promoting speciation in Collembola could be misled if they do not include analysis of mitochondrial markers.

Animals↗
PubMed2005

Confounding factors in the detection of species responses to habitat fragmentation.

Habitat loss has pervasive and disruptive impacts on biodiversity in habitat remnants. The magnitude of the ecological impacts of habitat loss can be exacerbated by the spatial arrangement -- or fragmentation -- of remaining habitat. Fragmentation per se is a landscape-level phenomenon in which species that survive in habitat remnants are confronted with a modified environment of reduced area, increased isolation and novel ecological boundaries. The implications of this for individual organisms are many and varied, because species with differing life history strategies are differentially affected by habitat fragmentation. Here, we review the extensive literature on species responses to habitat fragmentation, and detail the numerous ways in which confounding factors have either masked the detection, or prevented the manifestation, of predicted fragmentation effects. Large numbers of empirical studies continue to document changes in species richness with decreasing habitat area, with positive, negative and no relationships regularly reported. The debate surrounding such widely contrasting results is beginning to be resolved by findings that the expected positive species-area relationship can be masked by matrix-derived spatial subsidies of resources to fragment-dwelling species and by the invasion of matrix-dwelling species into habitat edges. Significant advances have been made recently in our understanding of how species interactions are altered at habitat edges as a result of these changes. Interestingly, changes in biotic and abiotic parameters at edges also make ecological processes more variable than in habitat interiors. Individuals are more likely to encounter habitat edges in fragments with convoluted shapes, leading to increased turnover and variability in population size than in fragments that are compact in shape. Habitat isolation in both space and time disrupts species distribution patterns, with consequent effects on metapopulation dynamics and the genetic structure of fragment-dwelling populations. Again, the matrix habitat is a strong determinant of fragmentation effects within remnants because of its role in regulating dispersal and dispersal-related mortality, the provision of spatial subsidies and the potential mediation of edge-related microclimatic gradients. We show that confounding factors can mask many fragmentation effects. For instance, there are multiple ways in which species traits like trophic level, dispersal ability and degree of habitat specialisation influence species-level responses. The temporal scale of investigation may have a strong influence on the results of a study, with short-term crowding effects eventually giving way to long-term extinction debts. Moreover, many fragmentation effects like changes in genetic, morphological or behavioural traits of species require time to appear. By contrast, synergistic interactions of fragmentation with climate change, human-altered disturbance regimes, species interactions and other drivers of population decline may magnify the impacts of fragmentation. To conclude, we emphasise that anthropogenic fragmentation is a recent phenomenon in evolutionary time and suggest that the final, long-term impacts of habitat fragmentation may not yet have shown themselves.

Animals↗
PubMed2000

Discrimination among three species of medicinal Scutellaria plants using RAPD markers.

An analysis of random amplified polymorphic DNA (RAPD) was performed using nine accessions of three species of medicinal plants in the genus Scutellaria (S. galericulata, S. lateriflora and S. baicalensis; known collectively as skullcap) in an effort to distinguish between members of these three species. Dried aerial parts of the two species S. galericulata and S. lateriflora are difficult to distinguish morphologically. Ten arbitrary primers produced 92 fragments, and eight of the primers yielded 23 species-specific fragments among the three species. Six fragments were specific for S. galericulata, seven for S. lateriflora and ten for S. baicalensis. When primers A02 and A06 were used in the polymerase chain reaction, RAPD fragments that were specific for each of the three species were generated simultaneously. Primer A02 produced five species-specific fragments: one was specific for S. galericulata; two for S. lateriflora; and two for S. baicalensis. Primer A06 produced three species-specific fragments: one for S. galericulata; one for S. lateriflora; and one for S. baicalensis. The RAPD markers that were generated with these two primers should rapidly identify members of the three species of Scutellaria. The consistency of the identifications made with these species-specific RAPD markers was demonstrated by the observation that each respective marker was generated from three accessions of each species, all with different origins. Furthermore, cluster analysis using the 92 RAPD fragments produced a dendrogram of genetic relatedness that was in good agreement with the taxonomic designations of the three species. Thus, the RAPD markers should be useful for the future identification of members of the three species of medicinal Scutellaria plants.

Plants, Medicinal↗
PubMed2004

The relationship between global and regional distribution diminishes among phylogenetically basal species.

Phylogenetic legacy and phylogenetic trends affect the ecology of species-except, apparently, for the width of their distribution. As a result, "macroecological" patterns of species distributions emerge constantly in phylogenetically very distinct species assemblages. The width of the global distribution of species, for instance, constantly correlates positively to the width of their regional distribution. However, such patterns primarily reflect the phylogenetically derived species that dominate most assemblages. Basal species, in contrast, might show different macroecological patterns. We tested the hypothesis that the correlation between global and regional distributions of species diminishes among the phylogenetically basal species. We considered central European higher plants and defined global distribution as the occupancy of global floristic zones, regional distribution as the grid occupancy in Eastern Germany, and phylogenetic position as the rank distance to tree base. We also took into account a number of confounding variables. We found that, across all lineages, the global/regional correlation diminished among basal species. We then reanalyzed 19 lineages separately and always found the same pattern. The pattern reflected both increases in global distributions and decreases in regional distributions among basal species. The results indicate that many basal species face a risk of global or at least regional extinction, but have escaped the downward spiral of mutually reinforcing extinction risks at multiple scales. We suggest that many basal species had much time to expand their global ranges but are presently displaced locally by more derived species. Overall, the study shows that macroecological patterns may not be static and universal, but may undergo macroevolutionary trends. Analyses of macroecological patterns across a phylogeny may thus provide insights into macroevolutionary processes.

Demography↗
PubMed2025

Species distribution of nontuberculous mycobacteria isolated from respiratory specimens at a tertiary care hospital in South Korea, 2017-2022.

The clinical relevance and drug resistance patterns of nontuberculous mycobacteria (NTM) vary by species. This study investigated the species distribution of NTM isolated from respiratory specimens at a tertiary care hospital in South Korea from 2017 to 2022. A retrospective analysis was conducted on laboratory data from respiratory specimens submitted for acid-fast bacilli culture. NTM isolates were identified using a line probe assay, and those unidentifiable at the species or complex level underwent multigene sequencing of the 16S rRNA, rpoB, and hsp65 genes. Among all mycobacterial isolates, the proportion of NTM showed an increasing trend, rising from 87.4% in 2017 to 93.3% in 2022. The eight most common species were M. avium complex (61.9%), M. abscessus (14.2%), M. fortuitum complex (8.4%), M. gordonae (5.3%), M. simiae complex (3.4%), M. kansasii complex (1.9%), M. terrae complex (1.5%), and M. chelonae (1.2%), accounting for 97.7% of all NTM isolates. Among the remaining isolates (2.3%, n = 169), 161 were classified into 24 species and groups, the majority with proportions below 0.1%. Two of the eight isolates that could not be identified at the species or group level despite multigene sequencing underwent whole-genome sequencing, which suggested they likely represent novel Mycobacterium species. This study provides valuable insights into the distribution of NTM species, particularly rarely encountered species, isolated from respiratory specimens in South Korea. These findings may aid in optimizing diagnostic strategies and selecting appropriate treatment options.IMPORTANCEGiven the significant variations in clinical relevance and drug resistance patterns among nontuberculous mycobacteria (NTM) species, understanding their geographic distribution is essential for selecting appropriate treatment options and improving patient outcomes. This study investigated the distribution of NTM species isolated from respiratory specimens at a tertiary care hospital in South Korea from 2017 to 2022. Our findings revealed an increasing proportion of NTM, with M. avium complex and M. abscessus remaining predominant. Additionally, we identified 24 rarely encountered species and groups, along with two strains that likely represent novel Mycobacterium species. Our study advances the understanding of the evolving NTM epidemiology in South Korea, contributing to the optimization of diagnostic strategies and improvement of patient management.

Republic of Korea↗
PubMed2002

What are bacterial species?

Bacterial systematics has not yet reached a consensus for defining the fundamental unit of biological diversity, the species. The past half-century of bacterial systematics has been characterized by improvements in methods for demarcating species as phenotypic and genetic clusters, but species demarcation has not been guided by a theory-based concept of species. Eukaryote systematists have developed a universal concept of species: A species is a group of organisms whose divergence is capped by a force of cohesion; divergence between different species is irreversible; and different species are ecologically distinct. In the case of bacteria, these universal properties are held not by the named species of systematics but by ecotypes. These are populations of organisms occupying the same ecological niche, whose divergence is purged recurrently by natural selection. These ecotypes can be discovered by several universal sequence-based approaches. These molecular methods suggest that a typical named species contains many ecotypes, each with the universal attributes of species. A named bacterial species is thus more like a genus than a species.

Bacteria↗
PubMed2005

Emergence of unusual species of enterococci causing infections, South India.

BACKGROUND: Enterococci tend to be one of the leading causes of nosocomial infections, with E. faecalis and E. faecium accounting up to 90% of the clinical isolates. Nevertheless, the incidence of other species of enterococci from clinical sources shows an alarming increase with the properties of intrinsic resistance to several antibiotics including beta-lactams and glycopeptides. Thus proper identification of enterococci to species level is quintessential for management and prevention of these bacteria in any healthcare facility. Hence this work was undertaken to study the prevalence of unusual species of enterococci causing human infections, in a tertiary care hospital in South India. METHODS: The study was conducted in a tertiary care hospital in South India from July 2001 to June 2003. Isolates of enterococci were collected from various clinical specimens and speciated using extensive phenotypic and physiological tests. Antimicrobial susceptibility testing were performed and interpreted as per NCCLS guidelines. Whole cell protein (WCP) fingerprinting of enterococci were done for species validation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and analyzed computationally. RESULTS: Our study showed the prevalence of unusual (non-faecalis and non-faecium enterococci) and atypical (biochemical variant) species of enterococci as 19% (46 isolates) and 5% (12 isolates) respectively. The 7 unusual species (46 isolates) isolated and confirmed by phenotypic characterization includes: 15 E. gallinarum (6.2%), 10 E. avium (4.1%), 6 E. raffinosus (2.5%), 6 E. hirae (2.5%), 4 E. mundtii (1.7%), 3 E. casseliflavus-including the two atypical isolates (1.2%) and 2 E. durans (0.8%). The 12 atypical enterococcal species (5%) that showed aberrant sugar reactions in conventional phenotyping were confirmed as E. faecalis, E. faecium and E. casseliflavus respectively by WCP fingerprinting. The antimicrobial susceptibility testing depicted the emergence of high-level aminoglycoside and beta-lactam resistance among different species apart from intrinsic vancomycin resistance by some species, while all the species tested were susceptible for linezolid and teicoplanin. CONCLUSION: Our study reveals the emergence of multi-drug resistance among unusual species of enterococci posing a serious therapeutic challenge. Precise identification of enterococci to species level enables us to access the species-specific antimicrobial resistance characteristics, apart from knowing the epidemiological pattern and their clinical significance in human infections.

Anti-Bacterial Agents↗
PubMed2004

Biodiversity, distributions and adaptations of Arctic species in the context of environmental change.

The individual of a species is the basic unit which responds to climate and UV-B changes, and it responds over a wide range of time scales. The diversity of animal, plant and microbial species appears to be low in the Arctic, and decreases from the boreal forests to the polar deserts of the extreme North but primitive species are particularly abundant. This latitudinal decline is associated with an increase in super-dominant species that occupy a wide range of habitats. Climate warming is expected to reduce the abundance and restrict the ranges of such species and to affect species at their northern range boundaries more than in the South: some Arctic animal and plant specialists could face extinction. Species most likely to expand into tundra are boreal species that currently exist as outlier populations in the Arctic. Many plant species have characteristics that allow them to survive short snow-free growing seasons, low solar angles, permafrost and low soil temperatures, low nutrient availability and physical disturbance. Many of these characteristics are likely to limit species' responses to climate warming, but mainly because of poor competitive ability compared with potential immigrant species. Terrestrial Arctic animals possess many adaptations that enable them to persist under a wide range of temperatures in the Arctic. Many escape unfavorable weather and resource shortage by winter dormancy or by migration. The biotic environment of Arctic animal species is relatively simple with few enemies, competitors, diseases, parasites and available food resources. Terrestrial Arctic animals are likely to be most vulnerable to warmer and drier summers, climatic changes that interfere with migration routes and staging areas, altered snow conditions and freeze-thaw cycles in winter, climate-induced disruption of the seasonal timing of reproduction and development, and influx of new competitors, predators, parasites and diseases. Arctic microorganisms are also well adapted to the Arctic's climate: some can metabolize at temperatures down to -39 degrees C. Cyanobacteria and algae have a wide range of adaptive strategies that allow them to avoid, or at least minimize UV injury. Microorganisms can tolerate most environmental conditions and they have short generation times which can facilitate rapid adaptation to new environments. In contrast, Arctic plant and animal species are very likely to change their distributions rather than evolve significantly in response to warming.

Adaptation, Physiological↗
PubMed2006

Species richness and stand stability in conifer forests of the Sierra Nevada.

Theoretical and empirical studies have long suggested that stability and complexity are intimately related, but evidence from long-lived systems at large scales is lacking. Stability can either be driven by complex species interactions, or it can be driven by the presence/absence and abundance of a species best able to perform a specific ecosystem function. We use 64 years of stand productivity measures in forest systems composed of four dominant conifer tree species to contrast the effect of species richness and abundance on three stability measures. To perform this contrast, we measured the annual growth increments of > 900 trees in mixed and pure forest stands to test three hypotheses: increased species richness will (1) decrease stand variance, (2) increase stand resistance to drought events, and (3) increase stand resilience to drought events. In each case, the alternate hypothesis was that species richness had no effect, but that species composition and abundance within a stand drove variance, resistance, and resilience. In pure stands, the four species demonstrated significant differences in productivity, and in their resistance and resilience to drought events. The two pine species were the most drought resistant and resilient, whereas mountain hemlock was the least resistant and resilient, and red fir was intermediate. For community measures we found a moderately significant (P = 0.08) increase in the community coefficient of variation and a significant (P = 0.03) increase in resilience with increased species richness, but no significant relationship between species richness and community resistance, though the variance in community resistance to drought decreased with species richness. Community resistance to drought was significantly (P = 0.001) correlated to the relative abundance of lodgepole pine, the most resistant species. We propose that resistance is driven by competition for a single limiting resource, with negative diversity effects. In contrast resilience measures the capacity of communities to partition resources in the absence of a single limiting resource, demonstrating positive diversity effects.

Analysis of Variance↗
PubMed2006

Species traits as predictors of lepidopteran composition in restored and remnant tallgrass prairies.

Restoration ecologists are increasingly turning to the development of trait-filter models, which predict how evolved traits limit species membership within assemblages depending on existing abiotic or biotic constraints, as a tool to explain how species move from a regional species pool into a restored community. Two often untested assumptions of these models, however, are that species traits can reliably predict species' broadscale distribution and that the effects of traits on community membership do not vary between restored and remnant habitats. The goals of this study were to determine whether combinations of ecological traits predispose moth species toward recolonization of restored prairies and to assess the degree to which restored prairies contain moth assemblages comparable with prairie remnants. In 2004, we collected 259 moth species from 13 tallgrass prairie remnants and restorations in central Iowa. Principal components analysis (PCA) was used to identify significant combinations of ecological traits that were shared by groups of moth species. Logistic regression was then employed to test for significant effects of the trait combinations on the frequency of prairie sites occupied by moth species. PCA partitioned moth traits into four axes that explained a total of 81.6% of the variance. Logistic regression detected significant effects for all four PCA axes on the fraction of sites occupied by moths. Species frequently filtered from the regional species pool into prairies were those that had long flight periods and were multivoltine, displayed a feeding preference for legumes but not other forb families, and were regionally abundant but relatively small in body size. Ordination revealed significant differences in moth communities among prairies, suggesting that species traits and habitat characteristics likely interact to create observed patterns of species recolonization of restorations. Thus, the optimal approach to restoring the lepidopteran fauna of tallgrass prairies may involve locating prairie plantings adjacent to habitat remnants.

Animals↗
PubMed2005

[Interspecific association between understory species in a southern highland plantation].

Based upon 2 x 2 contingency table, chi2 test and association coefficient were used to determine the interspecific association between understory species in a southern highland plantation, and to analyze the restoration degree and the stability of southern highland vegetations originated from plantation. The Qianyanzhou in Taihe County of Jiangxi Province, a typical sample of southern highland plantation, was chosen to make the study. The results showed that both in shrub layer and in herb layer, species pair with chi2 reaching significant level (P <0.05) was few in number. In shrub layer, 12 species pairs' association was highly significant (P < 0.01), 19 pairs' was significant (P < 0.05), and other 200 pairs' was nonsignificant, while in herb layer, 11 pairs' was highly significant, 11 pairs' was significant and other 83 pairs' was nonsignificant. According to interspecific association and correlation, shrub layer was divided into two species groups: Group I . Adinandra bockiana, Syzygiumn grijsii, Vaccinium bracteatunm, Ilex aculeolata, Smilax ferox, Eurya muricata and Group II . Lespedeza davidii, Serissa serissoides, Vitex negundo var. cannabifolia. Many species in Group I had a significantly negative association with the species in Group II, and dominant species always played a key role in the relationships among species. The three dominant species in herb layer, Wooduardia japonica, Dryopteris atrata and Adiantun flabellulaturn, had a highly significant positive correlation between each other, and moreover, had a significant or highly significant positive association with many other herbaceous species. Similarily, dominant species in shrub layer played a key role on the interspecific association in the two species groups. The ratios of positive and negative association indicating the species compositions of the two layers were fluctuating, which was 125/106 in shrub layer and 42/63 in herb layer. Several shortcomings of interspecific association method were pointed out, with some proposals put forward.

Biodiversity↗
PubMed1998

Interspecific mate choice in sailfin and shortfin species of mollies.

I examined interspecific patterns of female choice for three species of mollies: the 'sailfin' species, P. latipinna and two 'shortfin' species, P. orri and P. mexicana. Females of the sailfin species consistently preferred conspecific males across all male treatment combinations containing conspecifics. Females of the two shortfin species had lower levels of female preference and spent less time interacting with males during trials. The only consistent pattern of female choice in either shortfin species was a preference for the sailfin P. latipinna males over heterospecific shortfin males, but not over conspecifics. This finding suggests a potential bias by shortfin females for the sailfin male phenotype. Males of the three species differed in both behaviour and morphology. Length and relative position of the dorsal fin reliably separated P. latipinna from the two shortfin species. Body depth and shape distinguished males of the two shortfin species. Dorsal fin height was not a reliable cue for distinguishing sailfin males from males of either shortfin species. Males from different populations of the sailfin species P. latipinna differ in both size-specific behavioural rates and size-specific morphometry, particularly in the overall size-adjusted area of the dorsal fin. Increased rates of courtship displays and increased area of the dorsal fin separate males of P. latipinna from males of the two shortfin species as well. If the same traits used by females of P. latipinna for intraspecific discrimination are also important species-recognition signals, this suggests a potential role for sexual selection in contributing to the divergence of male phenotype during speciation of sailfin mollies. Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1998

A simulation test of hominoid species number at Lufeng, China: implications for the use of the coefficient of variation in paleotaxonomy.

High dental metric variation in the large hominoid sample from the late Miocene site of Lufeng, China has been interpreted in two ways: (1) there are two morphologically similar species that broadly overlap in size, and (2) there is one species that is more highly sexually dimorphic in dental size, and perhaps in body size, than any extant primate. It has been claimed that the high levels of dental metric variation falsify the single-species hypothesis, which has been viewed implicitly as corroboration of the two-species hypothesis. However, the two-species hypothesis has not been subjected to testing. Here we test the two-species hypothesis using computer simulations to attempt to reproduce the unusual pattern of intrasexual and intersexual dental metric variation observed in the Lufeng postcanine dentition. Conditions of the simulation experiments were optimized to favor the two-species hypothesis. It was found that, although the Lufeng pattern of metric variation could be reproduced by sampling two species, the likelihood of this occurrence was very low even when the conditions were optimized to the point of improbability. We conclude that the likelihood is very high that the Lufeng sample is composed of one species that is more highly sexually dimorphic in the postcanine dentition than any extent primate species. If so, then the high levels of sexual dimorphism and intraspecific dental metric variation in this species violate the central assumption of methods that employ the coefficient of variation (CV) for paleotaxonomy, namely, that neither can lie outside the ranges observed among extant species. Thus, we further conclude that the CV must be used with caution when evaluating the taxonomic composition of fossil samples and, further, that it cannot be used to falsify a single-species hypothesis in any meaningful way. Other fossil hominoid samples with high measures of dental variation may indicate that considerable sexual size dimorphism typified many Eurasian middle-late Miocene hominoids.

Animals↗
PubMed1994

Molecular species of choline and ethanolamine glycerophospholipids in rat brain myelin during development.

The composition of the molecular species of various phospholipid subclasses was examined in myelin isolated from brain of 15-, 21- and 90-day-old rats. The molecular species of diacylglycerophosphocholine (PtdCho), diacylglycerophosphoethanolamine (PtdEtn) and plasmenyl-ethanolamine (PlsEtn) were quantified by high-performance liquid chromatography (HPLC) after phospholipase C treatment and dinitrobenzoyl derivatization. In rat brain myelin, each phospholipid subclass showed a specific pattern of molecular species that changed during development. PtdCho contained large amounts of saturated/monounsaturated and disaturated species and low amounts of saturated/polyunsaturated species. During brain development, the levels of saturated/monounsaturated molecular species increased whereas those of the disaturated and saturated/polyunsaturated species decreased. PtdEtn were characterized by their low levels of disaturated species and a high content of saturated/monounsaturated and saturated/polyunsaturated species, of which those containing fatty acids of the n-3 series decreased, whereas those containing fatty acids of the n-6 series did not change during brain development. The levels of saturated/monounsaturated species increased in PtdEtn. No disaturated molecular species could be detected in PlsEtn. This alkenylacyl subclass contained large amounts of saturated/polyunsaturated, saturated/monounsaturated and dimonounsaturated molecular species. During development, the levels of saturated/polyunsaturated molecular species decreased while those of the two others increased. The data indicated that myelin sheaths undergo phospholipid changes during brain development and maturation.

Aging↗
PubMed2005

Assessing contaminant sensitivity of endangered and threatened aquatic species: part I. Acute toxicity of five chemicals.

Assessment of contaminant impacts to federally identified endangered, threatened and candidate, and state-identified endangered species (collectively referred to as "listed" species) requires understanding of a species' sensitivities to particular chemicals. The most direct approach would be to determine the sensitivity of a listed species to a particular contaminant or perturbation. An indirect approach for aquatic species would be application of toxicity data obtained from standard test procedures and species commonly used in laboratory toxicity tests. Common test species (fathead minnow, Pimephales promelas; sheepshead minnow, Cyprinodon variegatus; and rainbow trout, Oncorhynchus mykiss) and 17 listed or closely related species were tested in acute 96-hour water exposures with five chemicals (carbaryl, copper, 4-nonylphenol, pentachlorophenol, and permethrin) representing a broad range of toxic modes of action. No single species was the most sensitive to all chemicals. For the three standard test species evaluated, the rainbow trout was more sensitive than either the fathead minnow or sheepshead minnow and was equal to or more sensitive than listed and related species 81% of the time. To estimate an LC50 for a listed species, a factor of 0.63 can be applied to the geometric mean LC50 of rainbow trout toxicity data, and more conservative factors can be determined using variance estimates (0.46 based on 1 SD of the mean and 0.33 based on 2 SD of the mean). Additionally, a low- or no-acute effect concentration can be estimated by multiplying the respective LC50 by a factor of approximately 0.56, which supports the United States Environmental Protection Agency approach of multiplying the final acute value by 0.5 (division by 2). When captive or locally abundant populations of listed fish are available, consideration should be given to direct testing. When direct toxicity testing cannot be performed, approaches for developing protective measures using common test species toxicity data are available.

Animals↗
PubMed2005

Evidence for a new species of Anisakis Dujardin, 1845: morphological description and genetic relationships between congeners (Nematoda: Anisakidae).

In the present study, a new biological species of Anisakis Dujardin, 1845, was detected in Kogia breviceps and K. sima from West Atlantic waters (coast of Florida) on the basis of 19 (nuclear) structural genes studied by multilocus allozyme electrophoresis. Fixed allele differences at 11 enzyme loci were found between specimens of both adults and larvae of the new species and the other Anisakis spp. tested. Reproductive isolation from A. brevispiculata Dollfus, 1968 was demonstrated by the lack of hybrid or recombinant genotypes in mixed infections in K. breviceps. Genetic distance of the new species from its closest relative, A. brevispiculata, was D(Nei)=0.79. The new species is morphologically different from the other species which have been genetically characterised and from the other Anisakis retained by Davey (1971) as valid or as species inquirendae: the name of Anisakis paggiae n. sp. is proposed for the new taxon. Anisakis Type II larvae (sensu Berland, 1961) from the European hake Merluccius merluccius in the northeastern Atlantic Ocean (Galician coast) and from the scabbard fish Aphanopus carbo in Central Atlantic waters (off Madeira), were identified as A. paggiae n. sp. Its genetic relationships with respect to the seven species previously characterised (A. simplex (Rudolphi, 1809) sensu stricto), A. pegreffii Campana-Rouget & Biocca, 1955, A. simplex, (A. typica (Diesing, 1860), A. ziphidarum Paggi et al., 1998, A. physeteris Baylis, 1923 and A. brevispiculata) were also inferred. Overall, a low genetic identity was detected at allozyme level between the eight Anisakis species. Interspecific genetic identity ranged from I(Nei)=0.68, between the sibling species of the A. simplex complex, to I(Nei)=0.00 (no alleles shared at the considered loci) when A. physeteris, A. brevispiculata and the new species were compared with the other species of the genus. Concordant topologies were obtained using both UPGMA and NJ tree analyses for the considered species. In both analyses, A. paggiae n. sp. clustered with A. brevispiculata. They also indicated two main clades, the first including A. physeteris, A. brevispiculata and A. paggiae n. sp., the second containing all of the remaining species (i.e. A. simplex (s.s.), A. pegreffii, A. simplex, A. typica and A. ziphidarum). A deep separation between these two main Anisakis clades, also supported by high bootstrap values at the major nodes, was apparent. This is also supported by differences in adult and larval morphology, as well as with respect to their main definitive hosts. A morphological key for distinguishing adult A. paggiae n. sp., A. physeteris and A. brevispiculata is presented. Allozyme markers for the identification of any life-history stage of the Anisakis spp. so far studied, as well as ecological data on their definitive host preferences and geographical distribution, are updated.

Alleles↗
PubMed1984

A study of the molecular species of diacylglycerol, phosphatidylcholine and phosphatidylethanolamine and of cholinephosphotransferase and ethanolaminephosphotransferase activities in the type II pneumocyte.

The percent distributions of the molecular species of diacylglycerol, phosphatidylcholine and phosphatidylethanolamine in rat whole lung and type II pneumocytes were found to differ significantly. Diacylglycerol from the type II pneumocyte is enriched in the disaturated species and diminished in the polyenoic species compared to whole lung. Type II pneumocyte phosphatidylcholine is enriched in the disaturated species and diminished in all other species compared to whole lung. Relative to whole lung, type II pneumocyte phosphatidylethanolamine is greatly enriched in monoenoic and depleted in polyenoic fatty acid species. Analysis of the fatty acid composition of the molecular species in general indicated differences in relative amounts of fatty acids which were most pronounced in palmitic, palmitoleic, stearic and oleic acids, both within and between type II pneumocyte and whole lung glycerolipids. Significant differences between molecular species also existed within type II pneumocyte glycerolipids. In this cell type, phosphatidylcholine is enriched in disaturated and diminished in monoenoic species compared to diacylglycerol. Phosphatidylethanolamine is enriched in monoenoic and polyenoic species relative to diacylglycerol. In order to determine whether differences observed in type II pneumocyte glycerolipid molecular species were attributable to differences in the specificities of cholinephosphotransferase and ethanolaminephosphotransferase, the selectivity of these enzymes was examined. While cholinephosphotransferase showed diminished activity towards 1-stearoyl-2-linoleoyl-sn-glycerol, neither enzyme showed selectivity towards other tested diacylglycerols under a variety of conditions. Therefore, while in the type II pneumocyte significant amounts of phosphatidylcholine (particularly the disaturated species) and phosphatidylethanolamine may be synthesized de novo, enzymes responsible for remodeling (phospholipase A2 and acyltransferases) may play an important role in establishing the final molecular species composition of both phosphatidylcholine and phosphatidylethanolamine.

Animals↗
PubMed1990

Unique molecular species composition of glycerolipids of frog rod outer segments.

The composition and metabolism of molecular species of glycerolipids, including phosphatidic acid (PA), phosphatidylinositol (PI) and diacylglycerol (DG), were studied in four frog retinal fractions prepared by discontinuous sucrose gradient centrifugation. Six glycerolipid classes were isolated from the lipid extracts of each fraction and converted to their corresponding 1,2-diacylglycerol acetates by acetolysis for quantitation of their molecular species by HPLC. Rod outer segments (ROS) showed a distinctive molecular species composition in all glycerolipid classes except phosphatidylcholine (PC). The relative amounts of dipolyunsaturated species in ROS were higher in phosphatidylethanolamine (PE), phosphatidylserine (PS), and PA, compared to the other retinal fractions. PI and DG of ROS had a similar molecular species composition and contained only small amounts of dipolyunsaturated species. A unique feature of the molecular species of ROS PI and DG was that they had high amounts of species containing docosahexaenoic acid (22: 6 omega 3), while PI and DG from the other retinal membranes consisted mostly of species containing arachidonic acid (20: 4 omega 6). Following in vitro incubation of frog retinas with [2-3H] glycerol, the mass and radioactivity distributions among molecular species were determined following HPLC fractionation. The unique species composition of PS in ROS is determined mainly by selective translocation from the inner segments to ROS, since the dpm %, representative of newly synthesized species composition of the same glycerolipid classes in the other membrane fractions. This suggests that the distinctive species composition of PE and PA in ROS is determined not by selective translocation from the inner segments, but by remodeling processes taking place in the ROS.(ABSTRACT TRUNCATED AT 250 WORDS)

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