Mitochondrial DNA clonality in the dock: can surveillance swing the case?

Mitochondrial DNA (mtDNA) is a favoured tool of evolutionary biologists because its high mutation rate generates enough signal to make inferences about population history over short time frames. Furthermore, mtDNA inheritance is clonal, being transmitted only through the maternal line. This enables evolutionary histories to be assembled without the complexities introduced by biparental recombination. Recently, a single case of human biparental inheritance has been reported. Given this, and the role supposed clonal inheritance has had in shaping our knowledge of human population history, it is essential to establish a method for identifying any recombinant mtDNA molecules in our population. A reliable surveillance mechanism would either maintain our confidence in clonal inheritance or indicate the inaccuracy of our inferences.     

A meta-analysis of the traits affecting dispersal ability in butterflies: can wingspan be used as a proxy?

1. Dispersal ability of a species is a key ecological characteristic, affecting a range of processes from adaptation, community dynamics and genetic structure, to distribution and range size. It is determined by both intrinsic species traits and extrinsic landscape-related properties. 2. Using butterflies as a model system, the following questions were addressed: (i) given similar extrinsic factors, which intrinsic species trait(s) explain dispersal ability? (ii) can one of these traits be used as a proxy for dispersal ability? (iii) the effect of interactions between the traits, and phylogenetic relatedness, on dispersal ability. 3. Four data sets, using different measures of dispersal, were compiled from published literature. The first data set uses mean dispersal distances from capture-mark-recapture studies, and the other three use mobility indices. Data for six traits that can potentially affect dispersal ability were collected: wingspan, larval host plant specificity, adult habitat specificity, mate location strategy, voltinism and flight period duration. Each data set was subjected to both unifactorial, and multifactorial, phylogenetically controlled analyses. 4. Among the factors considered, wingspan was the most important determinant of dispersal ability, although the predictive powers of regression models were low. Voltinism and flight period duration also affect dispersal ability, especially in case of temperate species. Interactions between the factors did not affect dispersal ability, and phylogenetic relatedness was significant in one data set. 5. While using wingspan as the only proxy for dispersal ability maybe problematic, it is usually the only easily accessible species-specific trait for a large number of species. It can thus be a satisfactory proxy when carefully interpreted, especially for analyses involving many species from all across the world.     

CBO guidelines to prevent accidental falls in the elderly: how can it be used in the institutionalized elderly?

Fall incidents occur frequently in the community dwelling elderly and even more in the institutionalised elderly. Fall-related research data indicate positive effects of a multifactorial intervention targeted on prevention of falls and fall-related injuries. In November 2004 the guideline "Prevention of fall incidents in the elderly" developed by The Dutch Institute for Healthcare Improvement (CBO) was published. This guideline pays attention to the risk factors for falling and the prevention of fall incidents in all settings. The highlights for nursing homes are: all nursing home patients are at risk; perform a fall risk assessment to direct fall preventive activities; together with specific fall prevention for the patient general fall prevention for the institute has to be undertaken; a multifactorial approach is indicated. In nursing homes it is possible to perform such approach multidisciplinary.     

Immunopathogenic mechanisms in schistosomiasis: what can be learnt from human studies?

Studies in mice indicate that schistosome egg-induced granuloma formation and hepatic fibrosis depend markedly on cytokine regulation, with interleukin 10 having a central role. There is no clear consensus about the pattern of cytokine production and regulation that causes a minority of chronically exposed patients to develop severe hepatosplenic (HS) disease, which is characterized by periportal fibrosis and portal hypertension. HS disease and the progression of hepatic fibrosis are associated with the production of profibrotic type 2 cytokines in the early stages of infection with Schistosoma mansoni. However, other studies indicate that HS disease is characterized by a predominant T helper 1 profile. Until new tools and approaches are developed to study human disease in endemic areas, investigators must either speculate about indirect evidence from human studies or rely more heavily on findings generated from experimental models of the disease.     

UV-induced changes in the skin: can they be repaired?

Abstract

The damaging effects of UVB light have been described previously and include a number of changes to multiple cell types. At previous meetings of this society, we have shown that Langerhans' cells are the most susceptible to UVB induced damage which can be shown as ultrastructural changes in dendrites, nucleus and cytoplasm by transmission electron microscopy. We have also shown that their patterns of migration from skin to regional lymph node and their ability to present antigens to autologous T cells have been profoundly altered by UVB irradiation.

The aim of this work was to establish if it was possible to reverse any of the damage done to Langerhans' cells by UVB exposure by topical application of a DNA repair enzyme such as T4N5 endonuclease. These experiments were undertaken in a sheep model that allowed collection of cells as they migrate from the skin. This allowed for a direct examination of the migration characteristics and ultrastructural features of all Langerhans' cells before, during, and for 2 weeks after exposure to a single dose of UVB.

Results obtained from this project indicate that treatment by topical application of DNA repair enzyme immediately after UVB irradiation may restore a number of normal immune parameters associated with the structure and function of migrating Langerhans' cells. It appears that there is a dose related correction of the increased tempo of cell migration and some improvements in the number of ultrastructurally damaged Langerhans' cells have also been associated with application of higher doses of DNA repair enzyme. These preliminary findings indicate that some potential therapeutic benefits are associated with the use of such agents in reversing the immunological damage caused by exposure to erythemal doses of UVB light.     

UV-induced changes in the skin: can they be repaired?

The damaging effects of UVB light have been described previously and include a number of changes to multiple cell types. At previous meetings of this society, we have shown that Langerhans' cells are the most susceptible to UVB induced damage which can be shown as ultrastructural changes in dendrites, nucleus and cytoplasm by transmission electron microscopy. We have also shown that their patterns of migration from skin to regional lymph node and their ability to present antigens to autologous T cells have been profoundly altered by UVB irradiation. The aim of this work was to establish if it was possible to reverse any of the damage done to Langerhans' cells by UVB exposure by topical application of a DNA repair enzyme such as T4N5 endonuclease. These experiments were undertaken in a sheep model that allowed collection of cells as they migrate from the skin. This allowed for a direct examination of the migration characteristics and ultrastructural features of all Langerhans' cells before, during, and for 2 weeks after exposure to a single dose of UVB. Results obtained from this project indicate that treatment by topical application of DNA repair enzyme immediately after UVB irradiation may restore a number of normal immune parameters associated with the structure and function of migrating Langerhans' cells. It appears that there is a dose related correction of the increased tempo of cell migration and some improvements in the number of ultrastructurally damaged Langerhans' cells have also been associated with application of higher doses of DNA repair enzyme. These preliminary findings indicate that some potential therapeutic benefits are associated with the use of such agents in reversing the immunological damage caused by exposure to erythemal doses of UVB light.     

Can higher taxa be used as a surrogate for species-level data in biodiversity surveys of litter/soil insects?

We investigate the usefulness of higher taxa as surrogates for species richness and diversity of litter/soil insects. We use data for Coleoptera (beetles) and Formicidae (ants) collected during biodiversity surveys of five tropical and two temperate countries, and use Pearson’s product moment correlations to assess the surrogacy relationship. Our results suggest that genera would provide an adequate surrogate for species richness of Coleoptera, but not for Formicidae. We suggest that the usefulness of higher taxa as surrogates for richness is dependent on both taxonomy and scale. Higher taxa provided a poor surrogate for species diversity due to the added dimension of evenness of community structure, and we recommend that higher taxa should not be used as surrogates for species diversity.     

Better the devil you know? Guidelines for insightful utilization of nrDNA ITS in species-level evolutionary studies in plants

The internal transcribed spacers (ITS) of the nuclear ribosomal 18S-5.8S-26S cistron continue to be the most popular non-plastid region for species-level phylogenetic studies of plant groups despite the early warnings about their potential flaws, which may ultimately result in incorrect assumptions of orthology. It has been gradually realized that the alternative target regions in the nuclear genome (low-copy nuclear genes, LCNG) are burdened with similar problems. The consequence is that, to date, developing useful LCNG for non-model organisms requires an investment in time and effort that hinders its use as a real practical alternative for many labs. It is here argued that ITS sequences, despite drawbacks, can still produce insightful results in species-level phylogenetic studies or when non-anonymous nuclear markers are required, provided that a thoughtful use of them is made. To facilitate this, two series of guidelines are proposed. One helps to circumvent problems of ITS amplification from the target organism, including spurious results from contaminants, paralogs and pseudogenes, as well as detection of sequencing artifacts. The other series helps to find out causes for unresolved clades in phylogenetic reconstruction, to integrate gene phylogenies, to distinguish horizontal transfer from lineage sorting, and to reveal if ITS phylogeny is not a good estimate of organism phylogeny.     

Under restrictive conditions,can the widths of linear enamel hypoplasias be used as relative indicators of stress episode duration?

Linear enamel hypoplasia (LEH), a type of enamel defect reflecting nonspecific physiological stress, has traditionally been used by bioarchaeologists to assess human health. Initially, measurements of defect width were used to estimate the duration of stress episodes. More recently, methods of counting within-defect perikymata (enamel growth increments) were developed to more accurately assess duration. Because perikymata are often not continuously visible within defects, while widths can usually be measured, the primary purpose of this article was to determine if, under restrictive conditions, the widths of LEH defects might be used as relative indicators of stress episode duration. Using a set of dental replicas from the prehistoric Irene Mound (1150-1400 A.D.), this study also investigated potential sources of variation in defect widths and how often defect widths could be measured and within-defect perikymata counted. Of 120 defects, only 47 contained both measurable defect widths and total within-defect perikymata, while 79 had measurable defect widths. Regression analysis revealed that, for these 47 defects, defect widths were more strongly related to the total number of within-defect perikymata than they were to crown region or tooth type. Although wide prediction intervals indicated that a defect's width could not be used to predict the number of within-defect perikymata for an individual, narrower confidence intervals associated with hypothetical mean population widths suggested that mean defect widths might be used to rank populations in terms of relative average stress episode duration.     

Cancer therapy: can the challenge be MET?

The deregulation of tyrosine kinase receptors (RTKs) is frequent in human tumors and is often associated with the acquisition of an aggressive phenotype. The Met oncogene, encoding the RTK for hepatocyte growth factor (HGF), controls genetic programs leading to cell growth, invasion and protection from apoptosis. The deregulated activation of Met is crucial not only for the acquisition of tumorigenic properties but also to achieve an invasive phenotype. The involvement of MET in human tumors has been definitively established and can be achieved through several mechanisms, including MET interaction with unrelated membrane receptors, such as integrins, plexins, CD44, FAS and other RTKs. Interfering with Met activation is thus a new and challenging approach to hamper tumorigenic and metastatic processes.     

The genomes and transposable elements in plants: are they friends or foes?

Transposable elements (TEs) are mobile genetic elements that are present in prokaryotes and eukaryotes. The ubiquity and abundance of these self-replicating entities, bereft of cellular function, had earned them the label of ‘genomic parasites’. However, the status of TEs has been revised, with ample genomic and biological evidence now portraying them as “genomic gold”. They are perceived as a major participant in the evolution of species. This review addresses the classification of TEs as well as their role and significance in the evolution of genomes, genetic diversity, gene regulation, and exaptation of contemporary species of the plant and animal kingdoms.     

Should only live diatoms be used in the bioassessment of small mountain streams?

It is unclear whether differentiating live and dead diatoms would enhance the accuracy and precision of diatom-based stream bioassessment. We collected benthic diatom samples from 25 stream sites in the Northern Oregon Coast ecoregion. We counted live diatoms (cells with visible chloroplasts) and then compared the counts with those generated using the conventional method (clean counts). Non-metric multidimensional scaling (NMDS) showed that the diatom assemblages generated from the two counts were overall similar. The relationships between the two diatom assemblages (summarized as NMDS ordination axes) and the environmental variables were also similar. Both assemblages correlated well with in-stream physical habitat conditions (e.g., channel dimensions, substrate types, and canopy cover). The conventional diatom method provides taxonomic confidence while the live diatom count offers ecological reliability. Both methods can be used in bioassessment based on specific assessment objectives. Handling editor: J. Saros     

Challenges of the utilization of wood polymers: how can they be overcome?

Diminishing fossil fuel resources as well as growing environmental and energy security concerns, in parallel with growing demands on raw materials and energy, have intensified global efforts to utilize wood biopolymers as a renewable resource to produce biofuels and biomaterials. Wood is one of the most abundant biopolymer composites on earth that can be converted into biofuels as well as used as a platform to produce bio-based materials. The major biopolymers in wood are cellulose, hemicelluloses, and lignin which account for >90% of dry weight. These polymers are generally associated with each other in wood cell walls resulting in an intricate and dynamic cell wall structure. This mini-review provides an overview of major wood biopolymers, their structure, and recent developments in their utilization to develop biofuels. Advances in genetic modifications to overcome the recalcitrance of woody biomass for biofuels are discussed and point to a promising future.     

How independent are the appearances of n-mers in different genomes?

MOTIVATION: Analysis of statistical properties of DNA sequences is important for evolutional biology as well as for DNA probe and PCR technologies. These technologies, in turn, can be used for organism identification, which implies applications in the diagnosis of infectious diseases, environmental studies, etc. RESULTS: We present results of the correlation analysis of distributions of the presence/absence of short nucleotide subsequences of different length ('n-mers', n = 5-20) in more than 1500 microbial and virus genomes, together with five genomes of multicellular organisms (including human). We calculate whether a given n-mer is present or absent (frequency of presence) in a given genome, which is not the usually calculated number of appearances of n-mers in one or more genomes (frequency of appearance). For organisms that are not close relatives of each other, the presence/absence of different 7-20mers in their genomes are not correlated. For close biological relatives, some correlation of the presence of n-mers in this range appears, but is not as strong as expected. Suppressed correlations among the n-mers present in different genomes leads to the possibility of using random sets of n-mers (with appropriately chosen n) to discriminate genomes of different organisms and possibly individual genomes of the same species including human with a low probability of error.     

Hypothesis: can N-acetylcysteine be beneficial in Parkinson's disease?

Based on the finding of decreased mitochondrial complex I activity in the substantia nigra of patients with Parkinson's disease, we propose that the consequent reduction of ATP synthesis and increased generation of reactive oxygen species may be a possible cause of nigrostriatal cell death. Since sulfhydryl groups are essential in oxidative phosphorylation, thiolic antioxidants may contribute to the preservation of these proteins against oxidative damage. In the present paper, we hypothesize that treatment with a sulfur-containing antioxidant such as N-acetylcysteine may provide a new neuroprotective therapeutic strategy for Parkinson's disease.     

Occurrence of species of the genus Pityophthorus Eichhoff (Coleoptera,Curculionidae, Scolytinae) in?the?province of Quebec,Canada

Twig beetles in the genus Pityophthorus Eichhoff, 1864 include more than 300 species worldwide, with maximum diversity in tropical and subtropical regions. To date, approximately 50 species of Pityophthorus have been recorded in Canada, and these species are associated mainly with coniferous trees. Since 1981, no comprehensive study on this difficult taxonomic group has been conducted in Quebec, Canada, most likely due to their limited significance as forest pests. Based on data gathered from five years of field sampling in conifer seed orchards and compiled from various entomological collections, the distribution of Pityophthorus species in Quebec is presented. Approximately 291 new localities were recorded for the Pityophthorus species. Five species-group taxa, namely Pityophthorus puberulus (LeConte, 1868), Pityophthorus pulchellus pulchellus Eichhoff, 1869, Pityophthorus pulicarius (Zimmermann, 1868), Pityophthorus nitidus Swaine, 1917,and Pityophthorus cariniceps LeConte&Horn, 1876 were the most widespread. In contrast, Pityophthorus consimilis LeConte, 1878, Pityophthorus intextus Swaine, 1917, Pityophthorus dentifrons Blackman, 1922, Pityophthorus ramiperda Swaine, 1917, and Pityophthorus concavus Blackman, 1928 display a notably limited distribution. In addition, the first distribution records of Pityophthorus intextus and Pityophthorus biovalis Blackman, 1922 are furnished, and the subspecies Pityophthorus murrayanae murrayanae Blackman, 1922is reported from Quebec for the second time. Moreover, distribution maps are provided for all Pityophthorus species recorded in the province of Quebec.     

Lungs of the first amniotes: why simple if they can be complex?

We show—in contrast to the traditional textbook contention—that the first amniote lungs were complex, multichambered organs and that the single-chambered lungs of lizards and snakes represent a secondarily simplified rather than the plesiomorphic condition. We combine comparative anatomical and embryological data and show that shared structural principles of multichamberedness are recognizable in amniotes including all lepidosaurian taxa. Sequential intrapulmonary branching observed during early organogenesis becomes obscured during subsequent growth, resulting in a secondarily simplified, functionally single-chambered lung in lepidosaurian adults. Simplification of pulmonary structure maximized the size of the smallest air spaces and eliminated biophysically compelling surface tension problems that were associated with miniaturization evident among stem lepidosaurmorphs. The remaining amniotes, however, retained the multichambered lungs, which allowed both large surface area and high pulmonary compliance, thus initially providing a strong selective advantage for efficient respiration in terrestrial environments. Branched, multichambered lungs instead of simple, sac-like organs were part and parcel of the respiratory apparatus of the first amniotes and pivotal for their success on dry land, with the sky literally as the limit.     

The risk of chronic myeloid leukemia: can the dose-response curve be U-shaped?

Chronic myeloid leukemia (CML) is caused by a BCR-ABL chromosome translocation in a primitive hematopoietic stem cell. The number of hematopoietic stem cells in the body is thus a major factor in CML risk. Evidence suggests that the number of hematopoietic stem cells in the body is only loosely regulated, having a broad "dead-band" of physiologically acceptable values. The existence of a dead-band is important, because it would imply that low levels of hematopoietic stem cell killing can be permanent; i.e., it would imply that low doses of ionizing radiation can cause permanent reductions in the total number of CML target cells and thus permanent reductions in the subsequent risk of spontaneous CML. Such reductions in risk could be substantial if hematopoietic stem cells are also hypersensitive to radiation killing at low dose. Our calculations indicate that, due to dead-band hematopoietic stem cell control, if hematopoietic stem cells are as hypersensitive to killing at low doses as epithelial cells, reductions in the spontaneous CML risk could exceed the low-dose risks of induced CML; i.e., the net lifetime CML risk could have a U-shaped dose-response curve.