Do differences in plant and flower age change mating patterns and alter offspring fitness in Raphanus sativus (Brassicaceae)?

When more pollen is present on stigmas than needed to fertilize all ovules, selection among pollen grains may occur due to effects of both pollen donors and maternal plants. We asked whether increasing plant age and flower age, two changes in maternal condition, altered the pattern of seed paternity after mixed pollination. We also asked whether changes in seed paternity affected offspring success in an experimental garden. While flower age did not affect seed paternity, there was a dramatic shift in pollen donor performance as plants aged. These differences were seen in the offspring as well, where the offspring of one pollen donor, which sired more seeds on young plants, flowered earlier in the season, and the offspring of another pollen donor, which sired more seeds on old plants, flowered later in the season. Thus, change in maternal condition resulted in altered seed paternity, perhaps because the environment for pollen tube growth was different. The pattern of seed paternity and offspring performance suggests that pollen donors may show temporal specialization.     

Can feral weeds evolve from cultivated radish (Raphanus sativus, Brassicaceae)?

Cultivated plants that cannot survive on their own often have maladaptive domestication traits. Unharvested crop seeds may generate feral populations, at times causing serious weed problems, but little is known about the evolution of ferality. We explored the potential for cultivated radish, Raphanus sativus, to become feral, given that closely related taxa (e.g., R. raphanistrum and crop-wild hybrids) are well-documented weeds. First, we measured the population growth of five experimental, cultivated, self-seeding radish populations in Michigan, USA, for three generations. Three late-flowering populations went extinct, and two others apparently hybridized with local R. raphanistrum. A common garden experiment showed that the two surviving populations had earlier flowering, smaller root diameters, and greater individual fecundity than did nonhybridized populations. We also used artificial selection to measure the evolutionary potential for earlier flowering. After two generations of strong selection, two of three lineages flowered earlier and produced more seeds than control lineages, but insufficient genetic variation prevented dramatic evolution of crop phenotypes. In summary, it seems unlikely that radishes could spontaneously become feral in our study area without gene flow from R. raphanistrum. Applying these approaches to other cultivated species may provide a better understanding of mechanisms promoting the evolution of feral weeds.     

Does differential seed siring success change over time or with pollination history in wild radish, Raphanus sativus (Brassicaceae)?

Previous work with wild radish has shown that pollen donors sire different numbers of seeds and that the condition of the maternal tissue affects seed paternity, suggesting that both pollen donor characteristics and maternal tissue affect mating. However, because these results are from the greenhouse, it is difficult to know whether they would hold true in the field. Here, we performed hundreds of crosses on several maternal plants to simulate changes during the flowering season of field plants. During the experiment, maternal resource availability changed due to the costs of producing fruits, and we determined the pollination history of a plant by performing crosses in specific orders. Examination of seed paternity showed that there were small differences in pollen donor success at the beginning of the experiment when maternal resources were abundant. Differential pollen donor success was greatest slightly later in the flowering period, but declined toward the end of the experiment. Thus, maternal plants may distinguish most among pollen donors when they have both abundant resources and experience with the differences in quality of available pollen donors. In contrast, there were few significant effects of the recent pollination history of plants on pollen donor success. Finally, despite the changes in mating performance over time, there were strong overall differences in pollen donor success, suggesting that seasonal changes in the field will not eliminate the potential for nonrandom mating.     

The origin of variation in “wild”Raphanus sativus (Cruciferae) in California

Analyses of populations ofRaphanus growing in the central part of California, from the Sierra Nevada foothills to the Pacific coast, show that pureR. raphanistrum can be found only in the Central Valley, while over the remainder of the area populations of the so-called wild (weedy)R. sativus occur. More detailed morphological studies of a number of populations in this area have revealed that the populations of wildR. sativus originated by hybridization of the cultivated forms of this species (the radish) with another introduced species, already a weed,R. raphanistrum. The composition of each hybrid population with respect to the proportion of characters of the one or the other species depends upon the habitat it occupies and its geographic location. Populations in inland areas display a high proportion ofR. raphanistrum characters, while in those near the coastR. sativus characters predominate.Artificial hybrids betweenR. raphanistrum and a cultivated form ofR. sativus exhibited about 50% pollen fertility and were heterozygous for a reciprocal translocation. Examination of wild populations ofR. sativus revealed that plants heterozygous for a reciprocal translocation are present in varying proportions. Experimental evidence is produced to show that this translocation is identical with that separatingraphanistrum from cultivated forms ofsativus. Thus a cytological proof of the introgression is added to the morphological evidence. Introgression ofraphanistrum characters appears to have been a major factor in converting the erstwhile crop plant,R. sativus, into a highly successful weed in California.     

Does long-term storage of spermatozoa occur in the adder (Vipera berus)?

In the adder ( Vipera berus) multiple inseminations during the spring mating season have been demonstrated, with fertilization taking place several weeks after mating activities have ceased. Subsequent sperm competition in the female reproductive tract can result in within-season mixed paternity. Prolonged sperm storage between mating seasons has been suggested as another mechanism of sperm competition in the adder. Competition between new and old spermatozoa would obstruct efforts to reveal reproductive strategies that correlate observed behaviour to paternity in natural populations. In the present study, controlled breeding experiments with adders were performed and DNA fingerprinting was used to determine paternity among all offspring of a total of 15 litters. The offspring of 11 large females, that had most probably also mated in a previous season, were sired exclusively by enclosure males. This result and earlier empirical data support the hypothesis that long-term sperm storage, over one or several reproductive cycles, does not occur in the adder.     

Development of 1-O-sinapoyl-β-D-glucose: L-malate sinapoyltransferase activity in cotyledons of red radish (Raphanus sativus L. var. sativus)

Protein preparations from cotyledons of red radish (Raphanus sativus L. var. sativus) catalyzed the the formation of depsides between cinnamic acids and L-malate, using 1-O-acyl glucose conjugates as the donors. This activity showed an absolute acceptor specificity towards L-malate and a pronounced donor specificity with 1-sinapoylglucose (1-O-sinapoyl--D-glucose). Maximal rate of sinapoyl-L-malate formation was found to be at pH 6.3, and there was no requirement for metal ions or sulfhydryl group reagents. The K _m values were found to be 0.46 mM for 1-sinapoylglucose and 54 mM for L-malate. Protein extracts obtained from seedlings at different stages of seedling development did not significantly differ with respect to the properties of the enzymatic activity. Appearance and development of extractable activities correlated well with the in vivo transacylation kinetics of 1-sinapoylglucose to sinapoyl-L-malate during seedling growth. Maximal activity was extracted from 10–14-d-old seedlings and found to be at 67 pkat pair^-1 of cotyledons. This new enzymatic activity in phenylpropanoid metabolism refers to an enzyme which can be classified as 1-sinapoylglucose: L-malate sinapoyltransferase (SMT) (EC 2.3.1.-).Abbreviations DTE dithioerythriol - HPLC high performance liquid chromatography - IAA indoleacetic acid - ME 2-mercaptoethanol - Mes 2-(N-morpholino)ethanesulfonic acid - Mops 3-(N-morpholino)propanesulfonic acid - SMT 1-O-Sinapoyl--D-glucose: L-malate sinapoyltransferase     

Isolation and Identification of a Novel β-Carboline Derivative in Salted Radish Roots,Raphanus sativus L.

The methanol extract of salted radish roots contains several precursors of yellow pigment. The main compound was isolated by the use of Toyopearl HW-40S column chromatography, and its structure was determined to be 1-(2′-pyrrolidinethion-3′-yl)-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid on the basis of an elemental analysis, and IR, UV, FAB-MS and NMR spectroscopy. This compound is presumed to have been the condensation product from the degradation of 4-methylthio-3-butenyl isothiocyanate and l-tryptophan. This carboline compound is considered to play an important role in the formation of the yellow pigment in salted radish roots.     

Does polyploidy occur in central European species of the family Sphaeriidae (Mollusca: Bivalvia)?

Some representatives of the bivalve family Sphaeriidae are assumed to be polyploid. In this study, 11 sphaeriid species (nine of the genus Pisidium, one of Musculium, and one of Sphaerium) inhabiting central Europe were studied karyologically, 10 of them for the first time. Analysis revealed high chromosome numbers (from 140 to 240). To elucidate the origin of high chromosome numbers, DNA contents were measured by flow cytometry in 5 of the studied species and, for comparison, in S. corneum and S. nucleus, which are known to be diploid (2n=30). Species with high chromosome counts yielded very similar DNA contents that are not higher than in the related species with low diploid numbers. This finding contradicts a possible origin of these species by recent polyploidization or hybridization of related species. Chromosome complements of the investigated species with high chromosome numbers differ from those with low 2n in their small chromosome size and the high proportion of subtelo- or acrocentric chromosomes. This indicates their possible origin either by an ancient polyplodization event followed by chromosomal rearrangements or by multiple chromosome fissions.     

Do mating strategies determine genital allometry in African mole rats (Bathyergidae)?

Allometry describes the relationship of components of an organism with change in overall body size and has become the focus of numerous studies on the evolution of genitalia. Typically, negative allometry is observed in insects and is explained by stabilizing selection whereas the very few studies on mammals have shown a positive allometric relationship of genitalia in the body size, thought to have arisen as a result of sexual selection. However, all mammal species studied to date are thought to use mainly post-copulatory mating strategies. Across mammals, however, both pre-and post-copulatory strategies occur (although the two are not mutually exclusive). We propose that where pre-copulatory strategies are mainly used, no reproductive benefits would result from evolving positively allometric genitalia. As such, mammal genitalia are not typically positively allometric but rather allometry will, to a certain degree, be determined by mating strategy. We tested this prediction using four species of African mole rats (Bathyergidae) exhibiting variation in their life histories and mating strategies. Although generally supported, in that positive allometry did not occur in species that we assumed use mainly pre-mating strategies, positive allometry did not occur in either of the promiscuous species thought to use post-copulatory strategies. We suggest, therefore, that while mating strategies may tentatively determine genital allometry, whether positively allometric genitalia occur also depends on a number of complex interacting factors. In addition, this study provides further evidence and empirical support for the co-evolution of male and female genitalia in mammals.     

Has inbreeding depression led to avoidance of sib mating in the Glanville fritillary butterfly (Melitaea cinxia)?

Previous work on the Glanville fritillary butterfly (Melitaea cinxia) shows substantial inbreeding depression in both of our two study regions, Finland and southern France. The influence of inbreeding depression on population dynamics should depend on the strength of inbreeding avoidance. We conducted mate choice experiments to ascertain whether and to what extent butterflies avoid mating with their sibs. Experiments with similar design were done in the laboratory with Finnish butterflies and in the field with French butterflies. Each female was given a choice of mates with equal opportunity to mate with a sib or with a non-sib. In neither experiment was there a trend towards avoidance of sib mating. 95% confidence intervals for the proportion of non-sib matings were 12–62% in the laboratory experiment and 28–69% in the field experiment. Any preference for non-sibs must be slight, and can provisionally be ignored in modelling the dynamics of M. cinxia populations. This revised version was published online in August 2006 with corrections to the Cover Date.     

A bicontinental origin of polyploid Australian/New Zealand Lepidium species (Brassicaceae)? Evidence from genomic in situ hybridization

Background and Aims

Incongruence between chloroplast and nuclear DNA phylogenies, and single additive nucleotide positions in internal transcribed spacer (ITS) sequences of polyploid Australian/New Zealand (NZ) Lepidium species have been used to suggest a bicontinental hybrid origin. This pattern was explained by two trans-oceanic dispersals of Lepidium species from California and Africa and subsequent hybridization followed by homogenization of the ribosomal DNA sequence either to the Californian (C-clade) or to the African ITS-type (A-clade) in two different ITS-lineages of Australian/NZ Lepidium polyploids.

Methods

Genomic in situ hybridization (GISH) was used to unravel the genomic origin of polyploid Australian/NZ Lepidium species. Fluorescence in situ hybridization (FISH) with ribosomal DNA (rDNA) probes was applied to test the purported ITS evolution, and to facilitate chromosome counting in high-numbered polyploids.

Key Results

In Australian/NZ A-clade Lepidium polyploids, GISH identified African and Australian/NZ C-clade species as putative ancestral genomes. Neither the African nor the Californian genome were detected in Australian/NZ C-clade species and the Californian genome was not detected in Australian/NZ A-clade species. Five of the eight polyploid species (from 7x to 11x) displayed a diploid-like set of rDNA loci. Even the undecaploid species Lepidium muelleriferdinandi (2n = 11x = 88) showed only one pair of each rDNA repeat. In A-clade allopolyploids, in situ rDNA localization combined with GISH corroborated the presence of the African ITS-type.

Conclusions

The nuclear genomes of African and Australian/NZ C-clade species were detected by GISH in allopolyploid Australian/NZ Lepidium species of the A-clade, supporting their hybrid origin. The presumed hybrid origin of Australian/NZ C-clade taxa could not be confirmed. Hence, it is assumed that Californian ancestral taxa experienced rapid radiation in Australia/NZ into extant C-clade polyploid taxa followed by hybridization with African species. As a result, A-clade allopolyploid Lepidium species share the Californian chloroplast type and the African ITS-type with the C-clade Australian/NZ polyploid and African diploid species, respectively.Key words: Lepidium, Brassicaceae, FISH, GISH, hybridization, polyploidy, long-distance dispersal, ITS, rDNA, Australia, New Zealand     

Do captive conditions favor shedding of parasites in the reared Atlantic bluefin tuna (Thunnus thynnus)?

Tuna (Thunnus spp.) has been characterized by long distance migrations, highly predatory behavior and longevity, all of which in turn, enable infections with a wide spectrum of different parasitic groups, reflecting in a remarkable diversity of tuna parasite communities. Since 2003, we have been monitoring parasite communities of Atlantic bluefin tuna (Thunnus thynnus) that are caught from the wild and transferred into cages during spring-summer months, as well as assemblages in fish that exit rearing cycle during the winter harvest period after 1.5 years. Interestingly in reared tuna, parasitic populations exhibit a significant decreasing trend at the end of the rearing cycle, rarely observed in other intensive productions that represent a suitable environment for the emergence, establishment and transmission of pathogens. In order to assess epizootiological behavior of tuna parasites assemblages at the beginning (B group) and at the end (A group) of 1.5 year rearing cycle, we examined data on parasite prevalence and abundance over 4 years. The aim was to evaluate parasite diversity indices and emerging differences between newly caught and harvested fish, as well as community compositions and their nestedness in respect to the event in the rearing cycle (capture or harvest time). In order to be able to predict classification of tuna in two categories (newly caught or heavily infected and harvested or less infected fish), based on empirical didymozoids abundances and year of sampling, we built a decision tree model. Results suggest that specificities of parasite assemblages and their dynamics in tuna before and after farming have no similar precedents in aquaculture. A trend of parasitic pauperization repeating in each rearing cycle over four-years time, in once diverse and species rich parasite communities is observed, however, structures of both B and A group rearing assemblages remain nested, with the same species being core parasites (Didymosulcus katsuwonicola and Koellikerioides intestinalis). The B group exhibited significantly higher total parasite richness and mean parasites abundance, as well as the heteroxenous species richness and abundance in comparison to A group, where monoxenous species were not recorded at all. Eleven parasite species out of 26 taxa were selected as important in discriminating between B and A groups' parasites assemblages, while significantly the most abundant in B group were D. katsuwonicola, Platocystis alalongae, K. intestinalis, Koellikerioides internogastricus, Didymocystis abdominalis and Anisakis sp. It is hard to postulate the combination of factors affecting these parasite populations, but environmental, anthropogenic or host intrinsic influence has to be taken into account for further investigation.     

Do consecutive flower visits within a crown diminish fruit set in mass‐flowering Hancornia speciosa (Apocynaceae)?

Hancornia speciosa is a self-incompatible, mass-flowering, sphingophilous fruit crop (mangaba) of northeast and central Brazil. The flowers have a precise pollination apparatus, which optimizes pollen transfer between flower and pollinator. While the pollination mechanism avoids self-pollination, mass-flowering promotes geitonogamy. During a flower visit, almost half of the exogenous pollen grains adhering to the proboscis are deposited on the stigma surface. A pollination experiment with a nylon thread simulating six consecutive flower visits within a crown revealed that only the first two flowers visited (positions 1 and 2) are highly likely to set fruit. Super-production of flowers, and consequently obligate low fruit set, seem to be part of the reproductive strategy of the obligate outcrossing plant, Hancornia speciosa.     

Is Kir6.1 a subunit of mitoK(ATP)?

The subunit composition of the mitochondrial ATP-sensitive K⁺-channel (mitoK_ATP) is unknown, though some suspect a role for the inward rectifier, Kir6.1, based largely on antibody studies of heart mitochondria. To ascertain the molecular identity of mitoK_ATP we therefore sought to purify this putative mitochondrial Kir6.1, and conclusively identify the subunits by mass spectrometry. Immunoblots, conducted with two commercially available antibodies, revealed two distinct signals in isolated heart mitochondria, of 51 and 48 kDa, respectively. Localization was confirmed by either immuno-gold electron microscopy or by immunofluorescence. Each putative Kir6.1 species was extracted, purified, and identified by LC-MS/MS. The 51 kDa band was identified as NADH-dehydrogenase flavoprotein 1, while the preponderant protein in the 48-kDa band was mitochondrial isocitrate dehydrogenase (NADP form). 1D-, 2D-, and native gel analyses were consistent with these assignments. The data suggest it is premature to assign Kir6.1 a role in mitoK_ATP on the basis of immunoreactivity alone.     

Removal of α-naphthol and other phenolic compounds from polluted water by white radish (Raphanus sativus) peroxidase in the presence of an additive, polyethylene glycol

Role of white radish peroxidase has been investigated in the treatment of water contaminated with phenols, particularly α-naphthol. Water polluted with α-naphthol was treated with white radish peroxidase under various experimental conditions. The treatment of α-naphthol polluted water by this enzyme in presence of polyethylene glycol enhanced its removal. Studies carried out in absence of polyethylene glycol showed only 36% of α-naphthol removal however, 96% of it was removed in presence of 0.1 mg/mL of polyethylene glycol in 100 mM sodium phosphate buffer, pH 6.5, and 0.75 mM H₂O₂ at 40°C. The other phenols oxidized and removed from waste water under similar experimental conditions were 18%, m-cresol; 30%, p-chlorophenol; 62%, p-bromophenol; 20%, benzyl alcohol; 21%, quinol; 38%, 2,6-dichlorophenol; 13%, 2,4-dichlorophenol; and 2%, native phenol. Mixtures of different phenolic compounds removed under identical treatment conditions were 63%, A; 40%, B; 52%, C; 41%, D; 72%, E; 66%, F; and 72%, G. Thus, peroxidase in presence of an additive, polyethylene glycol could be a suitable tool for the removal of phenolic compounds from industrial effluents.     

Which adaptations of some invasive Ludwigia spp. (Rosidae,Onagraceae) populations occur in contrasting hydrological conditions in Western France?

Biological invasions in wetlands by Water Primroses (Ludwigia grandiflora ssp. hexapetala and L. peploides ssp. montevidensis) are an increasing problem especially in wet meadows. The aim of this paper is to quantify differences between species and the adaptation of these amphibious plants in order to establish the consequences for site managers. The hypotheses were: (i) that these species differ in biomass and morphology, and (ii) that terrestrial habitats determine particular adaptations such as reduced biomass, more roots and a bushy form. Biomasses from five sites were collected, following seasonal changes and biological traits were measured on selected plants. Comparing species in aquatic habitats, L. peploides produced less biomass than L. grandiflora. Comparing habitats for L. grandiflora, the biomass in meadows was almost twice that in dykes, particularly due to old stems, the converse of the hypothesis. Terrestrial forms were characterized by a bushy morphology, with shorter internodes and stems, as well as more secondary ramifications, while in aquatic habitats the plant architecture was simpler. Models were built linking morphology to species, sites and water conditions. Adaptations to terrestrial habitats of a particularly resistant form with a significant potential biomass are practical constraints for farmers and managers.     

Vascularizing the tissue surrounding a model biosensor: how localized is the effect of a subcutaneous infusion of vascular endothelial growth factor (VEGF)?

Implantable continuous biosensors would improve disease management but long term function of such devices have been limited by a hypovascular foreign body capsule that inhibits influx of analytes. To assess whether capsule vascularity could be increased, we studied the histologic effects of a 28-day continuous infusion of vascular endothelial growth factor (VEGF) (0.45 microg/day) vs. saline from the surface of a model disk biosensor that was implanted subcutaneously in rats. At day 40, tissue was obtained at varying distances from the infusion port and capsular microvessels were counted using two histologic techniques. VEGF treatment led to a marked increase in capillary density. In tissue located 1 mm away from the infusion site, capillary density in VEGF-treated animals was 200-300% higher than in saline controls. Tissue located 13 mm away, but not 25 mm away, also demonstrated neovascularization. Serum obtained from a distant vein during the infusion did not show an elevated concentration of VEGF. These data demonstrate that a subcutaneous infusion of VEGF creates localized neovascularization of the foreign body capsule and suggest that systemic effects of VEGF are avoidable. Vascularization of a foreign body capsule surrounding a subcutaneous biosensor might well extend its useful life.     

Is there a plastid in Perkinsus atlanticus (Phylum Perkinsozoa)?

Perkinsus atlanticus is a pathogenic protist that infects the clam Ruditapes decussatus. The recent proposal for the inclusion of the genus Perkinsus in a new phylum, Perkinsozoa, in the infra-kingdom Alveolata, gave rise to controversies whether this genus should form a phylum on its own. Molecular analysis of some conserved nuclear genes shows a closer proximity of the genus Perkinsus to the dinoflagellates than to the apicomplexans. Studies on extranuclear genomes, however, could also be very helpful for a more precise definition of those phyla. In Perkinsozoa, there have been until now no reports about the isolation of mitochondria as well as no conclusive results about the presence of any plastids, therefore a comparison with the data already obtained in Apicomplexa and Dinoflagellata has not yet been possible. In this work, we identify a plastid in Perkinsus atlanticus, using ultrastructural techniques and inhibition growth tests. It will be important to analyze the plastid genome at a molecular level, in order to confirm if the plastid in Perkinsus is more similar to those of Dinoflagellata or Apicomplexa. Such information will doubtless contribute to a more precise determination of the phylogenetic position of the genus Perkinsus.     

Courtship tactics in garter snakes: how do a male's morphology and behaviour influence his mating success?

The behavioural determinants of male mating success play a pivotal role in sexual selection, but remain poorly known for most kinds of organisms, including most reptiles. In Manitoba, Canada, large numbers of red-sided garter snakes, Thamnophis sirtalis parietalis, court and mate in early spring near communal overwintering dens. To understand how a male's morphology and behaviour might influence his mating success, we videotaped 21 groups of snakes each comprising four males of varying body sizes plus a female. All males engaged in courtship, and mating occurred in all groups. Males with better body condition courted more vigorously and successfully than their smaller rivals did. The males that obtained matings were those that maintained their own cloaca closest to that of the female, aligned most of their body with the female, showed high rates of caudocephalic waving, chin pressing and tail searching, and did not allow other males to insert their body beside the female's. These behavioural differences between ‘winners’ and ‘losers’ were apparent from the beginning of each trial. Thus, male mating success in this ‘scramble’ system is determined not by chaotic, stochastic struggle (as has often been inferred) but instead is strongly linked to male courtship tactics. Energy stores (as evidenced by good body condition) may be critical determinants of mating success in these vigorous courtship episodes.