Parasitism of stem weevils and pollen beetles in winter oilseed rape is differentially affected by crop management and landscape characteristics

We examined the influence of crop management (crop density, nitrogen fertilization level) and landscape parameters [areal proportion of oilseed rape (OSR), Brassica napus L. var. oleifera Metzg. (Brassicaceae), and proportions, lengths and distances of various non-crop habitats] on the parasitism of stem weevils (Ceutorhynchus spp.; Coleoptera: Curculionidae) and pollen beetles (Meligethes spp.; Coleoptera: Nitidulidae) by parasitic wasps (Hymenoptera: Ichneumonidae). Larvae of host insects were sampled in 29 winter OSR fields located in landscapes ranging from structurally simple to complex. Spatial scales of landscape effects were considered at eight radii (250–2,000 m) centered in the studied OSR fields. Stem weevil parasitism was unaffected by crop management variables but negatively related to roadside strip length at radius 250 m and grassy fallow area at a radius of 500 m. Pollen beetle parasitism was positively related to the crop density and to lengths of roadside strips and hedges within a radius of 250 m. Thousand kernel mass of OSR was positively related to pollen beetle parasitism but unrelated to stem weevil parasitism.

A new freshwater oligochaete species (Clitellata: Enchytraeidae) from Livingston Island,Antarctica

The new enchytraeid species Lumbricillus healyae sp. n. is described from freshwater streams, with well-oxygenated and poorly mineralised waters, situated in Byers Peninsula (Livingston Island, South Shetland Islands, Antarctica). Lumbricillus healyae sp. n. is morphologically close to L. antarcticus and L. incisus, and it is mainly distinguished by the structure of the spermatheca with a short, distinct ectal duct, the oval penial bulb (greatest diameter in the transverse body axis) associated with strong dorso-ventral muscular fibres, and a protrusible pseudopenis. A second undetermined Lumbricillus species is described from a small stream. Study specimens are not fully mature; however, the highly irregular form and size of the testis-sac lobes and the absence of a penial bulb encapsulated under a muscular layer are remarkable. It is probably related to a small group of Lumbricillus species reported from the Antarctic maritime region (L. colpites, L. griseus and L. aestum), characterised by the structure of the male duct, which ends in a simple pore surrounded by glands.

Pith: a marker of primary growth in Picea abies (L.) Karst.

The primary growth of trees may be studied either by following their development over time, which is costly and requires long-term monitoring, or by a posteriori growth analyses. Trees in temperate forests show rhythmic growth, which is characterised by morphological or anatomical markers. The study described here focuses on the pith of trees as an internal marker for the retrospective analysis of primary growth. Changes in pith size and density were quantified along a stem of Norway spruce [Picea abies (L.) Karst.] with high spatial resolution. The results showed that pith would appear to be a reliable marker of the annual growth rhythm even in the presence of polycyclism. Annual shoot limits were characterised by reductions in pith size associated, at the same time, with increases in pith density. In addition, pith size may provide information about tree ontogeny. The start of the competition with neighbouring trees was very likely responsible for an overall decrease in pith size. Regarding high frequency variations, pith size appeared to be less sensitive to local environmental fluctuations like climate than other studied variables such as annual shoot length and annual ring width. Finally, X-ray computed tomography proved to be a very promising method for the non-destructive detection of annual shoot limits in stems based on longitudinal changes in pith density, as demonstrated in a log of Norway spruce.

Insertional mutagenesis in <Emphasis Type="Italic">Populus</Emphasis>: relevance and feasibility

The recent sequencing of the first tree genome, that of the black cottonwood (Populus trichocarpa), opens a new chapter in tree functional genomics. While the completion of the genome is a milestone, mobilizing this significant resource for better understanding the growth and development of woody perennials will be an even greater undertaking in the years to come. In other model organisms, a critical tool for high-throughput analysis of gene function has been the generation of large mutagenized populations. Some mutagenesis technologies and approaches cannot be applied to trees because of their typically outcrossing breeding systems, high heterozygosity, large body size, and delayed flowering. In contrast, gene-tagging approaches that use insertional mutagenesis to create dominant phenotypes are ideally suited for trees and, especially, Populus. Both activation tagging and enhancer trap programs have been successful in identifying new genes important to tree development. The generation of genome-wide insertional mutant populations, which provide direct functional links between genes and phenotypes, should help to integrate in silico analyses of gene and protein expression, association studies of natural genetic polymorphism, and phenotypic analyses of adaptation and development.

Hierarchical analysis of piecewise affine models of gene regulatory networks

A key point in the analysis of dynamical models of biological systems is to handle systems of relatively high dimensions. In the present paper we propose a method to hierarchically organize a certain type of piecewise affine (PWA) differential systems. This specific class of systems has been extensively studied for the past few years, as it provides a good framework to model gene regulatory networks. The method, shown on several examples, allows a qualitative analysis of the asymptotic behavior of a PWA system, decomposing it into several smaller subsystems. This technique, based on the well-known strongly connected components decomposition, is not new. However, its adaptation to the non-smooth PWA differential equations turns out to be quite relevant because of the strong discrete structure underlying these equations. Its biological relevance is shown on a 7-dimensional PWA system modeling the gene network responsible for the carbon starvation response in Escherichia coli.

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Interactions of Colletotrichum musae and Lasiodiplodia theobromae and their biocontrol by Pantoea agglomerans and Flavobacterium sp. in expression of crown rot of “Embul” banana

Previous research has shown that two local isolates of bacteria (Pantoea agglomerans and Flavobacterium sp.) are capable of biocontrol of the two main pathogens (Colletotrichum musae and Lasiodiplodia theobromae) known to cause crown rot on “Embul” (Musa, AAB) banana. In this investigation an attempt was made to elucidate the comparative virulence of these pathogens and to determine the underlying biocontrol mechanisms. L. theobromae was more virulent, causing faster spread of the disease, whereas C. musae was more resistant to the bacterial antagonists. Viable cells of the antagonists were more effective at suppressing conidial germination than cell-free culture media. It seemed that antifungal compounds acting on conidial germination may be heat stable and those acting on mycelia may include heat labile compounds also. Considering the specialized roles observed for each pathogen in terms of causing the disease, and in modes of control by antagonists, future field investigations on biocontrol should consider the roles played by the pathogens and the antagonists.

Global adaptation patterns of Australian and CIMMYT spring bread wheat

The International Adaptation Trial (IAT) is a special purpose nursery designed to investigate the genotype-by-environment interactions and worldwide adaptation for grain yield of Australian and CIMMYT spring bread wheat (Triticum aestivum L.) and durum wheat (T. turgidum L. var. durum). The IAT contains lines representing Australian and CIMMYT wheat breeding programs and was distributed to 91 countries between 2000 and 2004. Yield data of 41 reference lines from 106 trials were analysed. A multiplicative mixed model accounted for trial variance heterogeneity and inter-trial correlations characteristic of multi-environment trials. A factor analytic model explained 48% of the genetic variance for the reference lines. Pedigree information was then incorporated to partition the genetic line effects into additive and non-additive components. This model explained 67 and 56% of the additive by environment and non-additive by environment genetic variances, respectively. Australian and CIMMYT germplasm showed good adaptation to their respective target production environments. In general, Australian lines performed well in south and west Australia, South America, southern Africa, Iran and high latitude European and Canadian locations. CIMMYT lines performed well at CIMMYT’s key yield testing location in Mexico (CIANO), north-eastern Australia, the Indo-Gangetic plains, West Asia North Africa and locations in Europe and Canada. Maturity explained some of the global adaptation patterns. In general, southern Australian germplasm were later maturing than CIMMYT material. While CIANO continues to provide adapted lines to northern Australia, selecting for yield among later maturing CIMMYT material in CIANO may identify lines adapted to southern and western Australian environments. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.

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Revision of the amphiamerican Neotetraonchus Bravo-Hollis, 1968 (Monogenoidea: Dactylogyridae), with a description of N. vegrandis n. sp. from the gill lamellae of the blue sea catfish Ariopsis guatemalensis (Siluriformes: Ariidae) off the Pacific Coast of Mexico

Neotetraonchus Bravo-Hollis, 1968 is revised and reassigned to the Dactylogyridae Bychowsky, 1933 based on examinations of specimens representing four species from the gill lamellae of sea catfishes (Ariidae). The monotypic Neotetraonchidae Bravo-Hollis, 1968 is placed in synonymy with the Dactylogyridae. Neotetraonchus bychowskyi Bravo-Hollis, 1968 (type-species), is redescribed from the tete sea catfish Ariopsis seemanni (Günther) (type-host) in the eastern Pacific Ocean off Panama (new geographical record). Neotetraonchus vegrandis n. sp. is described from the blue sea catfish A. guatemalensis (Günther) off the Pacific Coast of Mexico. Neotetraonchus bravohollisae Paperna, 1977 is redescribed from the hardhead sea catfish A. felis (L.) in the Gulf of Mexico off the Yucatan Peninsula. Neotetraonchus felis (Hargis, 1955) Paperna, 1977 is redescribed from A. felis in the Gulf of Mexico off Mississippi and the Yucatan Peninsula (new geographical record). Morphological similarities between species of Neotetraonchus suggest the likely presence of geminate species pairs flanking the Isthmus of Panama.

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Individual variability of behavioural responses by Wandering Albatrosses (Diomedea exulans) to human disturbance

Sub-Antarctic Marion Island has had a permanent research station for 50 years and the islands Wandering Albatrosses have been intensively studied for 20 years. The reactions of breeding birds to approaches by a human on foot were recorded. Three response variables were calculated: intensity of vocal reaction (IVR), intensity of non-vocal reaction (INR) and overall response index (ORI). At 5 m from the nest, twice as many birds stood and/or vocalised as at 15 m. Nearest neighbour distance, age and gender did not explain individual variability of responses. Study colony birds had higher IVR scores than non-study colony birds; birds at colonies closest to the station had the highest ORI scores. A better breeding record was associated with lower IVR and ORI scores, but a causative relationship remains to be demonstrated. A minimum viewing distance of 25 m is recommended for breeding Wandering Albatrosses.

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Ecological and population genetics research imperatives for transgenic trees

Applied research that supplies requisite, albeit incomplete, scientific knowledge is necessary if we are to address the legal, regulatory, and social/ethical issues regarding the use of transgenic trees. The technology for creating these trees has gotten far ahead of research on the ecological and population genetics impacts that may emerge. In this paper, we propose a comprehensive, interdisciplinary scientific approach that combines experimental results with model projections. We believe that much of this work must be completed before social issues can be clarified and resolved. Broad-based failure by those in the forestry-minded scientific community to carry out this interdisciplinary research could lead either to the establishment of transgenic trees with unintended consequences, or to an inability to realize the numerous advantages that this technology may offer.

Genetic study on the physical properties of Coffea arabica L. wood

The physical characteristics of wood are not usually considered as selection criteria when breeding perennial species that are grown for their fruits or seeds. In the coffee tree, stem breakage during harvesting and lodging during the growth period are major defects in some cultivars. These defects are linked to certain physical and mechanical properties of the wood, such as density or rigidity, which can be characterized by a parameter used in the resistance of materials: the Modulus of Elasticity (MOE). Wood density and the longitudinal MOE were studied on the stems of coffee trees of the species Coffee arabica L., derived from a diallel mating design. The MOE was measured by an acoustic system based on an analysis of the vibrations produced by a blow to the end of a piece of wood of known geometry. The MOE obtained in that way, along with the density of coffee tree stem wood, displayed substantial heritability. A strong link between the average internode length and the yield cumulated over 4 years was detected. Wood density was also correlated to yield and wood elasticity. Classification of parents according to the wood characteristics of their progenies depended on their degree of introgression by the species C. canephora. These traits could therefore be used to measure introgression, possibly as predictors of traits of agronomic interest, and as target traits in the creation of tall C. arabica varieties.

A revision of the Haploporinae Nicoll, 1914 (Digenea: Haploporidae) from mullets (Mugilidae): two new haploporine genera and a key to the genera of the subfamily

Two new haploporine genera are established for parasites of mullets. Ragaia n. g. is erected for R. lizae n. sp. from Liza ramado in the Ebro Delta on the Mediterranean Coast of Spain. This new genus is distinguished by the unique combination of the following characters: a strongly muscular ventral sucker which is twice as large as the oral sucker; a large, muscular hermaphroditic sac similar in length to the ventral sucker; a saccular, thick-walled internal seminal vesicle which is larger than the external seminal vesicle; and the ovary and vitellarium located rather close to the posterior extremity. Pseudodicrogaster n. g. is erected to accommodate Dicrogaster japonica Machida, 1996, as P. japonica (Machida, 1996) n. comb., a parasite of Mugil cephalus L. off Fukaura, Japan. This genus is recognised on the basis of: the tubular condition of both the internal and external seminal vesicles, the latter being much shorter than the former; the sucker ratio; the massive pyriform hermaphroditic sac; the location of the testis; and the presence of two eye-spots in developed miracidia. A key to the nine recognised genera of the Haploporinae is presented.

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A single operon-encoded form of the acetyl-CoA decarbonylase/synthase multienzyme complex responsible for synthesis and cleavage of acetyl-CoA in <Emphasis Type="Italic">Methanosarcina thermophila</Emphasis>

Methanogens growing on C-1 substrates synthesize 2-carbon acetyl groups in the form of acetyl-CoA for carbon assimilation using the multienzyme complex acetyl-CoA decarbonylase/synthase (ACDS) which contains five different subunits encoded within an operon. In species growing on acetate ACDS also functions to cleave the acetate C-C bond for energy production by methanogenesis. A number of species of Methanosarcina that are capable of growth on either C-1 compounds or acetate contain two separate ACDS operons, and questions have been raised about whether or not these operons play separate roles in acetate synthesis and cleavage. Methanosarcina thermophila genomic DNA was analyzed for the presence of two ACDS operons by PCR amplifications with different primer pairs, restriction enzyme analyses, DNA sequencing and Southern blot analyses. A single ACDS operon was identified and characterized, with no evidence for more than one. MALDI mass spectrometric analyses were carried out on ACDS preparations from methanol- and acetate-grown cells. Peptide fragmentation patterns showed that the same ACDS subunits were present regardless of growth conditions. The evidence indicates that a single form of ACDS is used both for acetate cleavage during growth on acetate and for acetate synthesis during growth on C-1 substrates. Electronic Supplementary Material  Supplementary material is available for this article at

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Leitlinien zur molekulargenetischen Diagnostik: Fragiles-X und Fragiles-X assoziiertes Tremor/Ataxie Syndrom

Ohne Zusammenfassung

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Understanding Evolutionary Trees

Charles Darwin sketched his first evolutionary tree in 1837, and trees have remained a central metaphor in evolutionary biology up to the present. Today, phylogenetics—the science of constructing and evaluating hypotheses about historical patterns of descent in the form of evolutionary trees—has become pervasive within and increasingly outside evolutionary biology. Fostering skills in “tree thinking” is therefore a critical component of biological education. Conversely, misconceptions about evolutionary trees can be very detrimental to one’s understanding of the patterns and processes that have occurred in the history of life. This paper provides a basic introduction to evolutionary trees, including some guidelines for how and how not to read them. Ten of the most common misconceptions about evolutionary trees and their implications for understanding evolution are addressed.

Development of the rhopalial nervous system in <Emphasis Type="Italic">Aurelia</Emphasis> sp.1 (Cnidaria,Scyphozoa)

We examined the development of the nervous system in the rhopalium, a medusa-specific sensory structure, in Aurelia sp.1 (Cnidaria, Scyphozoa) using confocal microscopy. The rhopalial nervous system appears primarily ectodermal and contains neurons immunoreactive to antibodies against tyrosinated tubulin, taurine, GLWamide, and FMRFamide. The rhopalial nervous system develops in an ordered manner: the presumptive gravity-sensing organ, consisting of the lithocyst and the touch plate, differentiates first; the “marginal center,” which controls swimming activity, second; and finally, the ocelli, the presumptive photoreceptors. At least seven bilaterally arranged neuronal clusters consisting of sensory and ganglion cells and their neuronal processes became evident in the rhopalium during metamorphosis to the medusa stage. Our analysis provides an anatomical framework for future gene expression and experimental studies of development and functions of scyphozoan rhopalia. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.