bluuebunny/crossref_metadata_2025_split huggingface dataset:
Indirect evidence from DNA sequence diversity for genetic degeneration of the Y‐chromosome in dioecious species of the plant Silene: the SlY4/SlX4 and DD44‐X/DD44‐Y gene pairs
Authors: LAPORTE V. , FILATOV D. A. , KAMAU E. , CHARLESWORTH D. 
Published: February 2005

AbstractThe action of natural selection is expected to reduce the effective population size of a nonrecombining chromosome, and this is thought to be the chief factor leading to genetic degeneration of Y‐chromosomes, which cease recombining during their evolution from ordinary chromosomes. Low effective population size of Y chromosomes can be tested by studying DNA sequence diversity of Y‐linked genes. In the dioecious plant, Silene latifolia, which has sex chromosomes, one comparison (SlX1 vs. SlY1) indeed finds lower Y diversity compared with the homologous X‐linked gene, and one Y‐linked gene with no X‐linked homologue has lower species‐wide diversity than a homologous autosomal copy (SlAp3Y vs. SlAp3A). To test whether this is a general pattern for Y‐linked genes, we studied two further recently described X and Y homologous gene pairs in samples from several populations of S. latifolia and S. dioica. Diversity is reduced for both Y‐linked genes, compared with their X‐linked homologues. Our new data are analysed to show that the low Y effective size cannot be explained by different levels of gene flow for the X vs. the Y chromosomes, either between populations or between these closely related species. Thus, all four Y‐linked genes that have now been studied in these plants (the two studied here, and two previously studied genes, have low diversity). This supports other evidence for an ongoing degeneration process in these species.
Phylogenetic congruence of mealybugs and their primary endosymbionts
Authors: DOWNIE D. A. , GULLAN P. J. 
Published: February 2005

AbstractTight interactions between unrelated organisms such as is seen in plant–insect, host–parasite, or host–symbiont associations may lead to speciation of the smaller partners when their hosts speciate. Totally congruent phylogenies of interacting taxa have not been observed often but a number of studies have provided evidence that various hemipteran insect taxa and their primary bacterial endosymbionts share phylogenetic histories. Like other hemipterans, mealybugs (Pseudococcidae) harbour multiple intracellular bacterial symbionts, which are thought to be strictly vertically inherited, implying codivergence of hosts and symbionts. Here, robust estimates of phylogeny were generated from four fragments of three nuclear genes for mealybugs of the subfamily Pseudococcinae, and a substantial fragment of the 16S–23S rDNA of their P‐endosymbionts. Phylogenetic congruence was highly significant, with 75% of nodes on the two trees identical, and significant correlation of branch lengths indicated coincident timing of cladogenesis. It is suggested that the low level of observed incongruence was influenced by uncertainty in phylogenetic estimation, but evolutionary outcomes other than congruence, including host shifts, could not be rejected.
Selfing and resource allocation in Schiedea salicaria (Caryophyllaceae), a gynodioecious species
Authors: Weller S. G. , Sakai A. K. 
Published: February 2005

AbstractLevels of selfing and resource allocation patterns were investigated in Schiedea salicaria (Caryophyllaceae), a gynodioecious species with high levels of inbreeding depression and nuclear control of male sterility. Selfing levels were higher in hermaphrodites than females, especially when adjusted for early acting inbreeding depression. The sexes of S. salicaria were similar in most allocation patterns including number of flowers and capsules per inflorescence, seeds per flower, and seed mass. Seeds produced by females had higher levels of germination than seeds of hermaphrodites, a likely result of high selfing levels and the expression of inbreeding depression in the progeny of hermaphrodites. Invasion of females in populations of S. salicaria is probably related to the expression of inbreeding depression at germination and in later life history stages. Comparisons with related species of Schiedea that also have nuclear control of male sterility suggest that reallocation of resources in hermaphrodites to male function occurs as females increase in frequency, but that resource reallocation is not important for the success of females when they first invade populations.
When morphometry meets genetics: inferring the phylogeography ofCarabus solieriusing Fourier analyses of pronotum and male genitalia
Authors: GARNIER S. , MAGNIEZ‐JANNIN F. , RASPLUS J.‐Y. , ALIBERT P. 
Published: February 2005

AbstractPopulation differentiation is a crucial step in the speciation process and is therefore a central subject in studies of microevolution. Assessing divergence and inferring its dynamics in space and time generally require a wide array of markers. Until now however, most studies of population structure are based on molecular markers and those concerning morphological traits are more scarce. In the present work, we studied morphological differentiation among populations of the ground beetleCarabus solieri,and tested its congruence with genetic population structure. The shape of pronotum and aedeagus was assessed using Dual Axis Fourier Shape Analysis.manovaon Fourier coefficients revealed highly significant morphological variation between populations and a similar geographical pattern of differentiation for both structures. On the whole, morphological and genetic patterns were also found to be congruent. Our analysis confirms the phylogeographical scenario proposing that two entities ofC. solieridifferentiated during the last glaciation events before recolonizing the actual range of the species. It also indicates a large introgression between the two differentiated entities in the centre of the range.
Probability models for pine twisting rust (Melampsora pinitorqua) damage in Scots pine (Pinus sylvestris) stands in Finland
Authors: Mattila U. 
Published: February 2005

SummaryFactors affecting the probability that pine twisting rust (Melampsora pinitorqua) damage occur in a Scots pine (Pinus sylvestris) stand were analysed using the 7th Finnish National Forest Inventory data (NFI7) from southern Finland in 1977–1983. The inventory was based on systematic sampling. The NFI7 data was measured in clusters, each of which consisted of 21 sample plots. In addition to the stand and site characteristics measured for forest management planning purposes, the data included records of damage by pine twisting rust and occurrence of aspens (Populus tremula, the other host plant of the pathogen) in the stands. Two multilevel logit models were developed for predicting the overall probability of pine twisting rust damage and the probability of severe pine twisting rust damage. Site and stand characteristics were used as explanatory variables in the models. Residual variance in the models was studied on the inventory crew, cluster and year levels. The occurrence of aspens and site fertility were the most important factors increasing the probability that pine twisting rust damage will occur in a stand. The damage probability also decreased with increasing effective temperature sum calculated for the location. The overall damage probability was equally high on peatlands and on mineral soil if there were aspens in the stand. If, however, there were no aspens in the stand, the probability of damage was higher on mineral soils than on peatlands. In addition, the overall probability was lower in naturally regenerated stands than in planted or sown stands, and it decreased with increasing mean age of pines. In both models, the residual variance was significant on the both the inventory crew and the cluster levels.
Racodium snow blight in Japan
Authors: Sakamoto Y. , Miyamaoto T. 
Published: February 2005

SummaryThe current knowledge of Racodium snow blight, one of the major snow blight diseases in Japan, is reviewed. This disease was discovered in Aomori Prefecture in 1951. The causal fungus (Racodium therryanum) is distributed in the Ao layer and affects the seedlings and seeds of many conifers. Hence, it is considered one of the inhibitors of the natural regeneration in the forests of Hokkaido. The perspectives for future research on this disease are discussed.
Genetic diversity of European populations of the oak fine‐root pathogen Phytophthora quercina
Authors: Cooke D. E. L. , Jung T. , Williams N. A. , Schubert R. , Oßwald W. , Duncan J. M. 
Published: February 2005

SummaryThe recently discovered oak‐specific fine root plant pathogen Phytophthora quercina is a significant factor in the current phase of European oak decline but its origins and ecology are poorly understood. A genome‐wide analysis of 260 amplified fragment length polymorphism (AFLP) markers was used to examine the genetic diversity of 72 isolates from five oak species at 28 sites in Germany (particularly Bavaria), Italy, France, Hungary and the UK. Within‐site diversity was examined at 16 sites. The limited genetic diversity (within and between sites) and lack of genetic substructuring according to geographic origin or host species suggest the rapid spread of a relatively recently introduced species. Two subgroups were distinguished and these may reflect an initial introduction of isolates of two different genetic backgrounds. The relatively low genetic diversity is probably because of the predominantly inbreeding (homothallic) nature of P. quercina. However, evidence of limited intra‐site diversity, temporal variation and the lack of clonality within the European population suggest that some diversity is being maintained by occasional outcrossing and turnover of a reservoir of long‐lived soil‐borne oospore (sexually derived) inoculum.
Pathogenicity of seed‐associated fungi to Podocarpus falcatus in vitro
Authors: Gure A. , Wahlström K. , Stenlid J. 
Published: February 2005

SummaryTwenty‐nine fungi that were isolated from seeds and female cones of Podocarpus falcatus from natural forests in Ethiopia, were assessed for their impact on seeds and seedlings of the same host. Based on the results from in vitro seed inoculation tests, we could group the fungi into five categories as: (i) isolates that were pathogenic only to seeds and had no obvious impacts on the germlings; (ii) isolates that were pathogenic only to the germlings; (iii) isolates that were pathogenic both to seeds and the emerging germlings; (iv) isolates that were more or less harmless; and (v) isolates that were germination promoters. Inoculation tests were also performed on 4–7‐day‐old aseptically grown seedlings. Fusarium oxysporum and Polyporus sp., were strongly pathogenic to both seeds and seedlings, while Nectria gliocladioides, Peniophora cinerea and Pestalotiopsis neglecta also demonstrated pathogenicity but to a lesser extent. Other isolates, e.g. Diaporthe spp. resulted in increased germination of P. falcatus seeds and no pathogenicity to seedlings. However, further investigations are required in order to find out how these fungi behave under nursery or field conditions.
Fungi associated with Ips typographus on Picea abies in southern Poland and their succession into the phloem and sapwood of beetle‐infested trees and logs
Authors: Jankowiak R. 
Published: February 2005

SummaryThis study dealt with the species distribution and frequency of fungi associated with the bark beetle Ips typographus (Scolytidae) on spruce trees of various states of health in southern Poland. The spruce trees were assessed by their degree of defoliation and damage of their crowns and trunks after attack by I. typographus. The state of health of trees from which samples were obtained was related to varying stages of brood development of I. typographus. Fungi were isolated from phloem taken from and around insect galleries and the sapwood underneath brood systems. Samples were taken from ‘healthy‐looking’, weakened, wind‐fallen and wind‐broken trees as well as from trap trees. The mycobiota associated with I. typographus was quite diverse in respect of the number of detected species, 65 fungal taxa were obtained from the phloem of trees infested by I. typographus, and 36 taxa occurred in the sapwood underneath insect galleries. The spectrum of fungi mainly consisted of ascomycetes and anamorphic fungi. The ophiostomatoid fungi were represented by 14 species and were the most numerously represented group in all niches examined. The most frequent ophiostomatoid species were Ceratocystis polonica, Ophiostoma ainoae, O. bicolor, O. penicillatum, O. piceae and O. piceaperdum. The frequency of occurrence of ophiostomatoid fungi differed significantly between the phloem and sapwood as well as in relation to the varying states of health of the spruce trees. These quantitative differences in the mycobiota of I. typographus between spruce trees belonging to different health categories can be explained by successional patterns of fungal colonization of host tissues following attack by I. typographus. The pathogenic species C. polonica was the primary invader, occurring most frequently in the sapwood of ‘healthy‐looking’ trees. Ophiostoma bicolor, O. penicillatum and O. piceaperdum also occurred during the early stages of brood development of I. typographus on ‘healthy‐looking’ trees, but they mainly colonized the phloem. In contrast, O. ainoae, O. minuta and O. piceae likely follow the aforementioned species as secondary and tertiary invaders into the phloem and the sapwood of spruce trees.
Production of fertile transgenic Brassica napus by Agrobacterium‐mediated transformation of protoplasts
Authors: Wang Y. P. , Sonntag K. , Rudloff E. , Han J. 
Published: February 2005

AbstractA protocol for Agrobacterium tumefaciens‐mediated transformation of Brassica napus mesophyll protoplasts is described. A strain with a neomycin phosphotransferase (nptII) gene and a KCS gene under control of a napin promoter was used at co‐cultivation. Transformed protoplasts were regenerated to fertile and morphologically normal transgenic plants. Transformants were confirmed by PCR of the nptII gene and NAP/KCS expression cassette, and Southern blot analysis. Seeds of the transformants showed a changed fatty acid profile: two transformants had a higher erucic acid level and differed significantly from that of B. napus. Genetic analysis of the progeny revealed that the kanamycin resistance introduced was inherited in a Mendelian fashion.
Inheritance of resistance to Verticillium wilt (Verticillium dahliae) in cotton (Gossypium hirsutum L.)
Authors: Mert M. , Kurt S. , Gencer O. , Akiscan Y. , Boyaci K. , Tok F. M. 
Published: February 2005

Abstract Verticillium wilt, caused by Verticillium dahliae Kleb., is a major constraint to cotton production in almost all countries where cotton is cultivated. Developing new cotton cultivars resistant to Verticillium wilt is the most effective and feasible way to combat the problem. Little is known about the inheritance of resistance to Verticillium wilt of cotton, especially that caused by the defoliating (D) and nondefoliating (ND) pathotypes of the soil‐borne fungus V. dahliae. The objective of this study was to determine the inheritance of resistance in cotton against both pathotypes of V. dahliae. Crosses were made between the susceptible parent ‘Cukurova 1518’ and each of four resistant parents PAUM 401, PAUM 403, PAUM 405 and PAUM 406 to produce F2 generations in 2002 and F2:3 families in 2003. Disease responses of parent and progeny populations to the D and ND pathotypes were scored based on a scale of 0‐4 (0, resistant; 4, susceptible). F2 populations inoculated with the D pathotype showed a 3 : 1 (resistant : susceptible) plant segregation ratio. Tests of F2:3 families confirmed that resistance was controlled by a single dominant gene. In contrast, analysis of data from F2‐ and F2‐derived F3 families suggested that resistance to the ND pathotype is controlled by dominant alleles at two loci.
Microsatellite variability and its use in the characterization of cultivated clones of Hevea brasiliensis
Authors: Saha T. , Roy C. Bindu , Nazeer M. A. 
Published: February 2005

AbstractMicrosatellite markers were developed and evaluated in Hevea brasiliensis, an important crop species producing natural rubber of commercial utility. Of eight microsatellite markers, four were found to be highly informative, amplifying a total of 19 alleles when evaluated against 27 cultivated Hevea clones/genotypes. Power of discrimination of the microsatellite loci was in the range of 0.62‐0.89, with a mean of 0.76 indicating these microsatellites could be valuable genetic markers for diversity characterization. A combination of four microsatellite markers was successfully used to discriminate uniquely all the 27 Hevea clones and some clone‐specific allelic profiles were generated. Cross‐species amplification of the markers developed in H. brasiliensis had also been demonstrated with two other Hevea species, H. benthamiana and H. spruceana, indicating a high degree of sequence homology at the flanking regions. Sequence analysis of the repeat region at the 3′‐UTR of the hydroxymethylglutaryl‐coenzyme A reductase gene, containing clusters of AG repeats in 15 clones, revealed the existence of two alleles based on the repeat length polymorphisms. Homozygosity as well as heterozygosity for both the alleles had also been detected among the clones. Frequency of homozygotes for the smaller allele (allele‐1) was found to be lower than the larger allele (allele‐2) among the primary clones of H. brasiliensis.
The responses of small mammals to patches regenerating after fire and rainfall in the Simpson Desert, central Australia
Authors: Letnic M. , Dickman C. R. 
Published: February 2005

Abstract  Patch‐burning is frequently advocated as a management tool to enhance the biodiversity and pasture values of spinifex (Triodia) grasslands. In this study we compare the capture rates of small mammals in habitats regenerating shortly after fire (aged 1–5 years) and in long‐unburnt habitats (aged >25 years). To unravel the effects of temporally and spatially variable rainfall on capture rates, the study was replicated at three locations spaced over 50 km apart that experience different rainfall regimes. Ten species of small mammals were captured over the course of the study, between October 1999 and June 2001. Pseudomys desertor showed a strong preference for long‐unburnt habitats. Notomys alexis, Sminthopsis youngsoni and Sminthopsis hirtipes showed some preferences for regenerating habitats, but these were not consistent throughout the study. Factors indicative of temporal and spatial variation in rainfall, time and site had important effects on capture rates. High rainfalls associated with the La Niña phase of the El Niño/Southern Oscillation in 2000 increased seed production and prompted eruptions of rodent species and the carnivorous Dasycercus cristicauda. The greatest numbers of captures were made at the sites that received the highest rainfalls. We conclude that patch‐burning regimes do not benefit small mammals directly, but are likely to increase the resilience of ‘fire‐sensitive’ species that are dependent on dense spinifex by reducing the extent of wildfires.
The impact of introduced ship rats (Rattus rattus) on seedling recruitment and distribution of a subantarctic megaherb (Pleurophyllum hookeri)
Authors: Shaw Justine D. , Hovenden Mark J. , Bergstrom Dana M. 
Published: February 2005

Abstract The impact of introduced ship rats (Rattus rattus) on recruitment of the megaherbPleurophyllum hookeriBuchan. (Asteraceae) was examined on subantarctic Macquarie Island, an island with no extant native terrestrial vertebrates.Pleurophyllum hookeri(Asteraceae) forms a dominant component of the Macquarie Island vegetation and is restricted to the subantarctic. The Macquarie Island population ofP. hookeriis the most extensive and intact. Introduced ship rats (Rattus rattus) are well established in tall tussock grassland of Macquarie Island. We detected rat activity for the first time withinP. hookeriherbfields, in autumn 2000. We found rats were destroying up to 90% of racemes. By excluding rats from caches of inflorescences that they had formed, we found they were having a significant negative effect on initial recruitment and seedling survival within the caches. However, because of high seedling mortality after 1 year, there was no sustained impact of the exclosures onP. hookeriseedling density.
Cataracts in experimentally diabetic mouse: morphological and apoptotic changes
Authors: Hegde K. R. , Varma S. D. 
Published: February 2005

Aim:  The objective of these investigations was to extend our earlier study on the induction of cataracts in diabetic mice, a low aldose reductase (AR) animal model at morphological level. Previous studies were done primarily at biochemical level.Methods:  Diabetes was induced by intraperitoneal administration of streptozotocin. The lenses isolated after the establishment of diabetes were then subjected to histologic and electron microscopic studies.Results:  Morphological alterations were characterized by shrinkage, elongation and lobulization of the nuclei of the epithelial cells. This was associated with chromatin condensation and its margination. Similar structural aberrations were also observed in a significant number of the subepithelial fibre cells representing defect in fibre maturation. More interestingly, unlike that in other common animal models of diabetic cataract, such abnormally nucleated cells were also found to be prevalent in the posterior subcapsular region, a finding common in human diabetics also.Conclusion:  The present studies further affirm the suitability of the mouse model for a study of cataractogenesis induced by diabetes. Because of the findings reported herein, as well as the known biochemical similarity between the lenses of the mice and humans in respect of AR deficiency, contrary to the rat model where it is very high, use of this species is considered more useful towards understanding the basic aetiology as well as for evaluating the efficacy of various referred nutritional and metabolic antioxidants against such cataracts.