bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cryptic population structure in a large, mobile mammalian predator: the Scandinavian lynx
Authors: Rueness E. K. , Jorde P. E. , Hellborg L. , Stenseth N. C. , Ellegren H. , Jakobsen K. S. 
Published: September 2003

AbstractThe Eurasian lynx (Lynx lynx) is an example of a species that has gone through a severe bottleneck, leading to near extinction in Scandinavia around 1930 — a pattern shared with several other large carnivorous mammals. Here we extend previous genetic analyses of northern European lynx, confirming that lynx from the Scandinavian Peninsula represent a distinct clade differing clearly from European conspecifics. Furthermore, and despite a recent bottleneck and subsequent range expansion, we detect marked genetic differentiation within Scandinavia. This differentiation is largely manifested as a north–south gradient, with a linear increase in the quantity FST/(1 − FST). Aided by computer simulations we find that this pattern is unlikely to have arisen by random genetic drift in the short time since lynx started to expand in the 1950s, suggesting that the spatial structure may predate the bottleneck. Individual‐based analyses indicate that, instead of a continuous gradient, Scandinavian lynx may be structured into three more or less distinct groups, possibly corresponding to northern, central and southern subpopulations. The presence of such structuring was unknown previously and was unexpected from general considerations on the mobility of the species, historical data and the absence of geographical barriers. Our study demonstrates how molecular markers may be used to detect cryptic population structure, invisible using traditional methods.
Gene flow and population history in high dispersal marine invertebrates: mitochondrial DNA analysis ofHolothuria nobilis(Echinodermata: Holothuroidea) populations from the Indo‐Pacific
Authors: Uthicke S. , Benzie J. A. H. 
Published: September 2003

AbstractThe sea cucumber,Holothuria nobilis, has a long‐lived planktotrophic larvae, and previous allozyme surveys have suggested that high dispersal is realized. In contrast, recent ecological studies indicate that dispersal is low. To reconcile these data, and to investigate the evolution of this Indo‐Pacific species, we screened geographical variation in 559 bp of a mitochondrial gene (COI) in 360 samples from the Australasian region and La Réunion. Sequences from La Réunion differed by > 7% from others and may constitute another species. Haplotype diversity in other samples was high (0.942, SD = 0.007), but haplotypes were closely related (mean nucleotide diversity: 0.0075, SD = 0.0041).amova, pairwiseFSTvalues and exact tests did not detect significant population structure. Nested clade analysis showed that one of two main clades was over‐represented in west Australia, whereas the other was more common in the northern Great Barrier Reef. Isolation‐by‐distance was identified as the main determinant of population structure at several clade levels. Contiguous range expansion was inferred for evolutionary older clade levels and this may correspond to a late Pleistocene (88 000–193 000 years ago) population expansion inferred from haplotype mismatch distributions. Thus, the population genetic structures detected are likely to be formed prior to the last ice age, with some indications for high dispersal on shorter time scales.
Genetics of colonization inHypochaeris tenuifolia(Asteraceae, Lactuceae) on Volcán Lonquimay, Chile
Authors: Tremetsberger K. , Stuessy T. F. , Samuel R. M. , Baeza C. M. , Fay M. F. 
Published: September 2003

AbstractUnderstanding the genetics of colonizing populations has been, and continues to remain, an important focus in evolutionary biology. Different theoretical models predict varying levels of genetic variation in colonizing populations depending upon strength of founder effect, gene flow and rate of population growth and immigration following colonization. We analyse overall genetic variation using amplified fragment length polymorphism markers in colonizing populations ofHypochaeris tenuifolia(Asteraceae) in the southern Andes. Volcán Lonquimay newly erupted on 25 December 1988, producing a side cone, La Navidad, and sent lava and ash into surrounding areas. Many domesticated animals (estimated at 10 000) and many natural plant populations were destroyed. Into this new open habitat have come immigrant populations of several angiosperm species, most conspicuouslyH. tenuifoliathat forms leaf rosettes with flowering scapes to 15 cm and orange–yellow heads 1–2 cm in diameter. Genetic diversity in five founder populations in the eruption zone is compared with that from five nearby survivor populations, as well as with eight isolated northern and four southern populations from throughout the entire range of the species in Chile. Results from 477 individuals representing 447 different multilocus phenotypes, yielded 170 DNA fragments of which 144 (85%) were polymorphic. Genetic diversity within founder populations is neither lower than in survivor populations nor in isolated populations throughout the range of the species, but it is lower among founder populations than among other populations immediately and distantly outside the zone of disturbance. Closest genetic similarity occurs between founders and nearby survivor populations as well as those in adjacent southern regions.
Genetic analysis of spatial foraging patterns and resource sharing in bumble bee pollinators
Authors: Chapman R. E. , Wang J. , Bourke A. F. G. 
Published: September 2003

AbstractConservation biologists, evolutionary ecologists and agricultural biologists require an improved understanding of how pollinators utilize space and share resources. Using microsatellite markers, we conducted a genetic analysis of space use and resource sharing at several spatial scales among workers of two ecologically dissimilar bumble bee species (Bombus terrestris and B. pascuorum) foraging in an urban landscape (London, UK). At fine scales, the relatedness of workers visiting small patches of flowers did not differ significantly from zero. Therefore, colonies shared flower patches randomly with other colonies, suggesting that worker scent‐marks deterring visits to unrewarding flowers have not evolved as signals benefiting nestmates. To investigate space use at intermediate scales, we developed a program based on Thomas & Hill's maximum likelihood sibship reconstruction method to estimate the number of colonies utilizing single sites. The average number of colonies (95% confidence limits) sending workers to forage at sites of ≈ 1 ha in area was 96 colonies (84–118) in B. terrestris and 66 colonies (61–76) in B. pascuorum. These values are surprisingly high and suggested that workers travelled far from their colonies to visit the sites. At the landscape scale, there was little or no genetic differentiation between sites. We conclude that urban habitats support large bumble bee populations and are potentially valuable in terms of bumble bee conservation. In addition, bumble bee‐mediated gene flow in plants is likely to occur over large distances and plant–bumble bee conservation requires landscape‐scale action.
Fine‐scale phylogeographical analysis of Mediterranean Anacamptis palustris (Orchidaceae) populations based on chloroplast minisatellite and microsatellite variation
Authors: Cozzolino S. , Cafasso D. , Pellegrino G. , Musacchio A. , Widmer A. 
Published: September 2003

AbstractThe phylogeographical history of the rare marsh orchid Anacamptis palustris (Orchidaceae) was reconstructed using highly polymorphic chloroplast minisatellite and microsatellite loci. Allelic variation at chloroplast microsatellite loci was due to length variation in poly(A/T) repeats and was informative on a regional scale, but was not sufficient to unravel relationships among populations on a local geographical scale. The minisatellite locus, however, was found to be highly variable. Nine distinct repeat types were found and variation in repeat number occurred in five repeat types. The distribution of chloroplast haplotypes, combining microsatellite and minisatellite repeat type variation, provided a clear phylogeographical picture on a large geographical scale, whereas length variation in one highly polymorphic minisatellite repeat type provided fine‐scale phylogeographical information. Mediterranean populations could be divided into four main lineages, a western European lineage, a northern and central Italian lineage, a well‐isolated southern Italian (Apulian) lineage, and an eastern European lineage. Variation at the most variable minisatellite repeat type N revealed 19 alleles and allowed the study of seed‐mediated gene flow and an estimation of the ratio of pollen to seed flow among neighbouring populations.
Is there a common mechanism of gastrointestinal nematode expulsion?
Authors: Lawrence Catherine E. 
Published: September 2003

SUMMARYParasitic gastrointestinal (GI) nematodes are one of the most commonly acquired infections in the world. Although they cause relatively little mortality, infections result in high levels of morbidity that can result in developmental consequences in infected children and cause significant economic loss in infected animals. Over the last 30 years there has been extensive research into the mechanisms controlling the expulsion of gastrointestinal nematodes. Although many of the effector mechanisms that contribute to the loss of the parasite have been defined, we still appear to be some way from understanding the actual cause of parasite loss. Part of this stems from the different responses induced by different gastrointestinal parasites. It is clear that a Th2 response is essential for the expulsion of GI helminths; however, each of the characteristic immunological effector mechanisms induced following infection with these parasites may not be required or may be insufficient in isolation, but together they operate to expel GI helminths. These responses then succeed more efficiently in some cases than in others to induce parasite expulsion. The contribution made by various effector mechanisms to the expulsion of these parasites may therefore be a reflection of both the niche which the parasite inhabits as well as possible evasive/suppressive mechanisms employed by the parasites. In this review the various aspects of parasite expulsion will be described and the controversial issues in the field will be discussed.
Progress and new technologies for developing vaccines against gastrointestinal nematode parasites of sheep
Authors: Newton S. E. , Meeusen E. N. T. 
Published: September 2003

SUMMARY Despite the identification of highly effective native antigens for vaccination against Haemonchus contortus, particularly ‘hidden’ antigens derived from the intestine of adult worms, to date similar efficacy has not been shown with recombinant antigens. In addition, progress towards identification of protective antigens from other sheep gastrointestinal (GI) nematode species is limited. Coupled with this is an incomplete understanding of the mechanism of natural immunity to GI nematodes, making selection of appropriate immunization strategies and adjuvants for evaluation of candidate ‘natural’ antigens problematic. The current explosion in new high‐throughput technologies, arising from human studies, for analysis of the genome, transcriptome, proteome and glycome offers the opportunity to gain a better understanding of the molecular pathways underlying pathogen biology, the host immune system and the host–pathogen interaction. An overview is provided on how these technologies can be applied to parasite research and how they may aid in overcoming some of the current problems in development of commercial vaccines against GI nematode parasites.
The mucosal immune system
Authors: MacDonald Thomas T. 
Published: September 2003

SUMMARYThis article outlines the lymphoid structures and cell types important in the intestinal immune response. Particular attention is paid to differences between rodents and man where there appears to be fundamental differences in the sources of the T and B cells which populate the mucosa. The majority of the data still suggest that Peyer's patches are the inductive site of mucosal immunity and the mucosa (lamina propria and epithelium) is the effector site, but there is growing realization that mucosal immune responses can occur in the absence of Peyer's patches and that antigen sampling may also occur in the lamina propria.
Mucosal defences against Giardia
Authors: Eckmann Lars 
Published: September 2003

SUMMARYGiardia lamblia (syn. G. duodenalis or G. intestinalis), the causative agent of giardiasis, is one of the most common causes worldwide of intestinal infections in humans. Symptomatic infection is characterized by diarrhoea, epigastric pain, nausea, vomiting, and weight loss, yet many infections are asymptomatic. The protozoan, unicellular parasite resides in the lumen and attaches to the epithelium and overlying mucus layers but does not invade the mucosa and causes little or no mucosal inflammation. Giardiasis is normally transient, indicating the existence of effective host defences, although re‐infections can occur, which may be related to differences in infecting parasites and/or incomplete immune protection. Mucosal defences against Giardia must act in the small intestinal lumen in the absence of induction by classical inflammatory mediators. Secretory IgA antibodies have a central role in anti‐giardial defence. B cell‐independent mechanisms also exist and can contribute to eradication of the parasite, although their identity and physiological importance are poorly understood currently. Possible candidates are nitric oxide, antimicrobial peptides such as Paneth cell α‐defensins, and lactoferrin. Elucidation of the key anti‐giardial effector mechanisms will be important for selecting the best adjuvants in the rational development of vaccination strategies against Giardia.
The SCARECROW gene's role in asymmetric cell divisions in rice plants
Authors: Kamiya Noriko , Itoh Jun‐Ichi , Morikami Atsushi , Nagato Yasuo , Matsuoka Makoto 
Published: September 2003

SummaryAsymmetric cell division is one of the most important mechanisms in the diversification of cell function and fate. In Arabidopsis, SCARECROW (SCR) is essential for the asymmetric division of the cortex/endodermis progenitor cell in the root. To learn more about how SCR is involved in asymmetric division, we analyzed the rice SCR (OsSCR) expression. In the root tip, OsSCR expression was observed in the endodermal cell layer and downregulated in the daughter cortex cell after asymmetric division, just as with Arabidopsis SCR. In leaf primordia, expression of OsSCR was observed in stomatal and ligule formation. In stomatal development, OsSCR was specifically expressed in the stomatal cell files before formation of guard mother cells (GMCs), and then, its expression was localized in GMCs, when the first asymmetric division occurred to generate the GMCs. Before the second asymmetric division of subsidiary mother cells (SMCs), localized OsSCR expression was observed in SMCs in the area close to the GMCs. Before these asymmetric divisions, the localization of OsSCR mRNA in GMC‐forming cells and SMCs was observed in the area of the daughter GMC and subsidiary cells. OsSCR expression was also observed in the initiation area of ligule formation, and its downregulation occurred in the inner L2 cells generated by asymmetric division. Based on these observations, we proposed that OsSCR is involved not only in the asymmetric division of the cortex/endodermis progenitor cell but also during stomata and ligule formation by establishing the polarization of cytoplasm.
Self‐oligomerization and protein aggregation of α‐synuclein in the presence of Coomassie Brilliant Blue
Authors: Lee Daekyun , Lee Eun‐Kyung , Lee Ju‐Hyun , Chang Chung‐Soon , Paik Seung R. 
Published: September 2003

α‐Synuclein has been implicated in various neurodegenerative disorders, including Parkinson's and Alzheimer's diseases, by its participation in abnormal protein depositions. As the protein has been suggested to play a significant role in the formation of the deposits which might be responsible for neurodegeneration, there is a strong demand to screen for α‐synuclein‐interactive small molecules. In this report, Coomassie Brilliant Blue (CBB) interaction of α‐synuclein has been investigated with respect to induction of protein self‐oligomerization in the presence of the chemical coupling reagentN‐(ethoxycarbonyl)‐2‐ethoxy‐1,2‐dihydroquinoline. Both CBB‐G and CBB‐R, which differ by only two methyl groups, induced the self‐oligomerization of α‐synuclein in a biphasic manner with optimal dye concentrations of 250 µmand 150 µm, respectively. The protein aggregates of α‐synuclein induced by the dyes in the absence of the coupling reagent were analysed by electron microscopy. Whereas CBB‐G induced formation of protein aggregates with a worm‐like structure, CBB‐R induced clear fibrilization of α‐synuclein on a background of granular structures. CBB‐R interacted with α‐synuclein approximately twice as effectively as CBB‐G (dissociation constants 0.63 µmand 1.37 µm, respectively). These dye interactions were independent from the acidic C‐terminus of α‐synuclein, which was reminiscent of the Αβ25–35 interaction of α‐synuclein. However, the metal‐catalysed oxidative self‐oligomerization of α‐synuclein in the presence of Cu2+/H2O2, which was augmented synergistically by Αβ25–35, was not affected by the dyes. This indicates that the dye binding site is also distinctive from the Αβ25–35 interaction site on α‐synuclein. These biochemically specific interactions between α‐synuclein and the dyes indicate that α‐synuclein‐interactive small molecules could provide a tool with which to approach development of diagnostic, preventive, or therapeutic strategies for various α‐synuclein‐related neurodegenerative disorders.
Mannosylerythritol lipid induces characteristics of neuronal differentiation in PC12 cells through an ERK‐related signal cascade
Authors: Wakamatsu Yoko , Zhao Xiaoxian , Jin Chuyuan , Day Noel , Shibahara Miki , Nomura Nobuhiko , Nakahara Tadaatsu , Murata Takehide , Yokoyama Kazunari K. 
Published: September 2003

Rat pheochromocytoma PC12 cells undergo neuronal differentiation in response to nerve growth factor (NGF). The differentiation involves protein kinase cascades that include the kinases MEK and ERK, as well as activation of the transcription factors c‐Jun and c‐Fos. We show here, that exposure of PC12 cells to mannosylerythritol lipid (MEL), a yeast extracellular glycolipid, enhances the activity of acetylcholinesterase and interrupts the cell cycle at the G1 phase, with resulting outgrowth of neurites and partial cellular differentiation. Treatment with MEL stimulates the phosphorylation of ERK to a similar extent as treatment with NGF, although, the appearance of phosphorylated ERK is somewhat delayed. Both the MEL‐induced outgrowth of neurites and the increase in the activity of acetylcholinesterase are prevented by PD98059, a specific inhibitor of MEK. Northern blotting analysis of c‐jun transcripts and analysis of transcription in PC12 cells of a c‐jun/CAT reporter construct demonstrated a significant increase in the rate of transcription of the c‐jun gene upon treatment with MEL. The sequence elements required for the MEL‐mediated activation of transcription of the c‐jun gene are located between nucleotides −126 and −79 in the 5′ flanking region. Our results suggest that MEL induces characteristics of neuronal differentiation in PC12 cells, with transactivation of the c‐jun gene, via an ERK‐related signal cascade that is partially overlapping the pathways activated in response to NGF. These results might provide the groundwork for the use of microbial extracellular glycolipids as novel reagents for the treatment of cancer cells.
Rules for Nest Sanitation in a Social Spider Mite, Schizotetranychus miscanthi Saito (Acari: Tetranychidae)
Authors: Sato Yukie , Saito Yutaka , Sakagami Takane 
Published: September 2003

AbstractWaste management behavior is essential to achieve nest sanitation that is highly inferential on the evolution of group living because nest waste is an inevitable cost. However, how group living animals dispose of waste has not attracted much attention. Schizotetranychus miscanthi Saito is a social spider mite infesting a perennial grass (Miscanthus sinensis Anderss), in which all nest members tend to defecate at specific sites. We investigated the mechanisms by which the individuals select the site of defecation. The results show that nest members defecate at only one site inside the nest, and that waste management is maintained by two simple rules. First, mites defecate near the nest entrances if no volatile chemical cues are available, and secondly, when chemical cues are available from feces deposited previously, they defecate at this site. We discuss the adaptive significance of these mechanisms, as well as their role in the evolution of sociality in mites.
Badgers and Badger Fleas: Strategies and Counter‐Strategies
Authors: Stewart Paul D. , Macdonald David W. 
Published: September 2003

AbstractWe examined the broad hypothesis that one function of grooming by the European badger (Meles meles) is to disadvantage (possibly by removal) parasitic badger fleas (Paraceris melis). We pursued two lines of investigation. First, we used infra‐red video analysis to examine the body areas reached by self‐ and allo‐grooming badgers. We expected that if grooming was important to disadvantage fleas then allo‐grooming would cover areas that could not be reached by self‐grooming. Badgers preferred dorsal allo‐grooming and ventral self‐grooming, and when combined, the overall amount of grooming per square centimetre of skin area provided even body coverage, pointing to a hygienic function, rather than a purely social function. Secondly, we examined fleas’ responses to simulated fur disturbance, characteristic of grooming. If grooming had no flea disadvantage effect, we would expect no response from fleas, and no directionality in their movement away from direct touch. The number of fleas encountered rapidly declined in successive 10‐s counts during simulated ‘grooming’ at the same site. When badgers were ‘groomed’ on alternate sides (mimicking the badgers’ rapid alternation of grooming position), there was a marked increase in fleas when grooming resumed on the original side. Similarly, when ‘grooming’ was suspended for 40 s, there was an initial increase in the number of fleas when ‘grooming’ was resumed. Disturbed fleas tended to run downwards relative to gravity and towards the posterior of the badger, following the direction of hair growth. This contrasted with the behaviour of fleas removed from badgers which tended to run upwards and jump. We concluded that the pattern of badger grooming and the fleas’ response to disturbance was consistent with a hypothesis that badgers and badger fleas have strategies and counter strategies to maximize and minimize contact (respectively) during grooming.