Buchonomyia burmanica sp.n. and Buchonomyiinae, a New Subfamily among the Chironomidae (Diptera)

Male and female imagines of Buchonomyia burmanica sp.n. are described. While the male imago nearly exclusively shows plesiomorphous features, the female imago possesses three important underlying synapomorphies as unique inside-parallelisms: the capacities for divisions of gonapophysis VIII and of tergite IX and for the development of an apodeme lobe. These and supporting evidence lead to the conclusion that Buchonomyia Fittkau deserves a new subfamily, the Buchonomyiinae, which forms the sister-group of the monophyletic unit Chironominae-t-Orthocladiinae+Prodiamesinae+Diamesinae.     

Influence of quantity and lability of sediment organic matter on the biomass of two isoetids,Littorella uniflora and Echinodorus repens

1. Despite real improvement in the water quality of many previously eutrophic lakes, the recovery of submerged vegetation has been poor. This lack of recovery is possibly caused by the accumulation of organic matter on the top layer of the sediment, which is produced under eutrophic conditions. Hence, our objective was to study the combined effects of quantity and lability of sediment organic matter on the biomass of Echinodorus repens and Littorella uniflora and on the force required to uproot plants of L. uniflora. 2. Lake sediments, rich in organic matter, were collected from four lakes, two with healthy populations of isoetids and two from which isoetids had disappeared. The four lake sediments were mixed with sand to prepare a range of experimental sediments that differed in quantity and lability of sediment organic matter. Two isoetid species, E. repens and L. uniflora, were grown in these sediments for 8 weeks. Sediment quality parameters, including elemental composition, nutrient availability and mineralisation rates, were determined on the raw sources of sediment from the lakes. Porewater and surface water were analysed for the chemical composition in all mixtures. At the end of the experiment, plants were harvested and their biomass, tissue nutrient concentration and (for L. uniflora) uprooting force were measured. 3. For both species, all plants survived and showed no signs of stress on all types of sediment. The biomass of E. repens increased as the fraction of organic matter was increased (from 6 to 39% of organic content, depending upon sediment type). However, in some of the sediment types, a higher fraction of organic matter led to a decline in biomass. The biomass of L. uniflora was less responsive to organic content and was decreased significantly only when the least labile sediment source was used to create the gradient of organic matter. The increase in shoot biomass for both species was closely related to higher CO₂ concentrations in the porewater of the sediment. The force required to uproot L. uniflora plants over a range of sediment organic matter fitted a Gaussian model; it reached a maximum at around 15% organic matter and declined significantly above that. 4. Increasing organic matter content of the sediment increased the biomass of isoetid plants, as the positive effects of higher CO₂ production outweighed the negative effects of low oxygen concentration in more (labile) organic sediments. However, sediment organic matter can adversely affect isoetid survival by promoting the uprooting of plants.     

Growth Chamber Illumination and Photomorphogenetic Efficacy I. Physiological action of infrared radiation beyond 750 nm

Plants cultivated in growth chambers under such artificial illumination as fluorescent tubes show certain characteristic differences from plants grown in nature or under incandescent lamps. The plants grown under fluorescent light are shorter and more darkly pigmented; they also show different daylength requirements for certain photoperiodic responses. It was assumed that these effects were caused by the relative deficiency of far red irradiation (λ= 700–750 nm) in the emission from the fluorescent lamps. This assumption was tested on such light sensitive phenomena as stem elongation, flowering, the formation of resting organs, chlorophyll synthesis, and production yield in several plant genera. In all cases the plants were grown under long days (16 h). Six common types of growth chamber illumination were tested for their efficacy for long-day induction. The spectral energy distribution of the lamps was measured. The emission from the various lamp types showed only small differences within the region of visible light (λ: 400–750 nm), but much larger diversity in the ratio of visible to infrared radiation (λ: 750–1000 nm). A strong correlation exists between the relative emission of infrared radiation and the photomorphogenetic efficacy of the lamps. Under fluorescent light the long-day effect was weak or missing, but increased with increasing infrared emission. High infrared emission was also favourable for high production yield.     

Influence of an arbuscular mycorrhizal fungus on Pseudomonas fluorescens DF57 in rhizosphere and hyphosphere soil

The influence of Glomus intraradices (BEG87) on Pseudomonas fluorescens DF57 in hyphosphere and rhizosphere soil was examined. Cucumis sativus (Aminex, F₁ hybrid) was grown in symbiosis with the arbuscular mycorrhizal fungus G. intraradices in PVC tubes, consisting of a central root compartment and two lateral root-free compartments. Two Tn 5 - lux AB-marked strains of P. fluorescens DF57 were used. Strain DF57-P2, which has an insertion of Tn 5::lux AB in a phosphate starvation-inducible locus, was used as a phosphate starvation reporter. Another lux -tagged strain DF57-40E7, which carries a constitutively expressed lux AB fusion, was used as control for strain DF57-P2 and for measuring the metabolic activity of P. fluorescens DF57. A strain of P. fluorescens DF57, which carries a constitutively expressed gfp gene, was used in studies of attachment between the bacteria and the hyphae. G. intraradices decreased the culturability of P. fluorescens DF57 significantly, both in rhizosphere and hyphosphere soil, whereas the total number of P. fluorescens DF57 measured by immunofluorescence microscopy was decreased in hyphosphere soil only. G. intraradices did not induce a phosphorus starvation response in P. fluorescens DF57, and the metabolic activity of the bacteria was not affected by the fungus after 48 h. P. fluorescens DF57 did not attach to G. intraradices hyphae and was not able to use the hyphae as carbon substrate. The negative effect of G. intraradices on culturability and on number of P. fluorescens DF57 in hyphosphere soil is discussed.     

Comparative and functional leaf anatomy of selected Alstroemeriaceae of mainly Chilean origin

The resupinate leaves of 16 species of Alstroemeriaceae were examined using light- and scanning electron microscopy. The leaf anatomy is described for all of the species, that of the petiole and stem for selected species. The mesophyll consists of chlorenchyma and includes idioblasts that contain raphides. Dorsiventral, isolateral or isobilateral leaf types were observed. Petioles are always isolateral. Two epidermal types are commonly observed: type I contains jigsaw puzzle-like intercostal cells and longitudinally elongated cells above the veins; type II contains only longitudinally elongated cells, usually longer, above the veins. Some species have an epidermis which differs from the main types. All species show adaptation to resupination by having an inverted anatomy. Due to the twist of the leaves, adaxial indicates the lower surface and abaxial the upper. Stomata are found on both surfaces. Palisade cells, when they occur, are always on the abaxial surface. Most species are mesomorphic in spite of the dry environments in which they grow; a few show xeromorphic features. The leaves are compared and discussed with relation to ecological conditions.  © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 140 , 261−272.     

Hybridization between distant lineages increases adaptive variation during a biological invasion: stickleback in Switzerland

The three‐spined stickleback is a widespread Holarctic species complex that radiated from the sea into freshwaters after the retreat of the Pleistocene ice sheets. In Switzerland, sticklebacks were absent with the exception of the far northwest, but different introduced populations have expanded to occupy a wide range of habitats since the late 19th century. A well‐studied adaptive phenotypic trait in sticklebacks is the number of lateral plates. With few exceptions, freshwater and marine populations in Europe are fixed for either the low plated phenotype or the fully plated phenotype, respectively. Switzerland, in contrast, harbours in close proximity the full range of phenotypic variation known from across the continent. We addressed the phylogeographic origins of Swiss sticklebacks using mitochondrial partial cytochrome b and control region sequences. We found only five different haplotypes but these originated from three distinct European regions, fixed for different plate phenotypes. These lineages occur largely in isolation at opposite ends of Switzerland, but co‐occur in a large central part. Across the country, we found a strong correlation between a microsatellite linked to the high plate ectodysplasin allele and the mitochondrial haplotype from a region where the fully plated phenotype is fixed. Phylogenomic and population genomic analysis of 481 polymorphic amplified fragment length polymorphism loci indicate genetic admixture in the central part of the country. The same part of the country also carries elevated within‐population phenotypic variation. We conclude that during the recent invasive range expansion of sticklebacks in Switzerland, adaptive and neutral between‐population genetic variation was converted into within‐population variation, raising the possibility that hybridization between colonizing lineages contributed to the ecological success of sticklebacks in Switzerland.     

Shoot atmospheric contact is of little importance to aeration of deeper portions of the wetland plant Meionectes brownii; submerged organs mainly acquire O2 from the water column or produce it endogenously in underwater photosynthesis

Partial shoot submergence is considered less stressful than complete submergence of plants, as aerial contact allows gas exchange with the atmosphere. In situ microelectrode studies of the wetland plant Meionectes brownii showed that O₂ dynamics in the submerged stems and aquatic roots of partially submerged plants were similar to those of completely submerged plants, with internal O₂ concentrations in both organs dropping to less than 5 kPa by dawn regardless of submergence level. The anatomy at the nodes and the relationship between tissue porosity and rates of O₂ diffusion through stems were studied. Stem internodes contained aerenchyma and had mean gas space area of 17.7% per cross section, whereas nodes had 8.2%, but nodal porosity was highly variable, some nodes had very low porosity or were completely occluded (ca. 23% of nodes sampled). The cumulative effect of these low porosity nodes would have impeded internal O₂ movement down stems. Therefore, regardless of the presence of an aerial connection, the deeper portions of submerged organs sourced most of their O₂ via inwards diffusion from the water column during the night, and endogenous production in underwater photosynthesis during the daytime.     

The land planarian Australoplana sanguinea var. alba at a horticultural site in New Zealand

Morphometric data and general observations of habitat conditions, feeding behaviour and reproductive biology are presented for the land planarian Australoplana sanguinea var. alba, based upon a population established at a garden centre in Alexandra, South Island, New Zealand. The flatworm species considered in this study appears to be identical to an alien flatworm initially referred to as Geoplana sanguinea (Moseley) var. alba (Dendy) which has successfully colonised areas of the British Isles over the past few decades. The study also highlights the importance of garden centres and nurseries as modified habitats that provide favourable conditions for terrestrial planarians, implying that exotic flatworm species have the potential to spread and exist in pockets world-wide.     

The distyly in Primula elatior (L.) Hill (Primulaceae), with a study of flowering phenology and pollen flow

Flowers of Primula elatior exhibit all the dimorphic traits typical of distyly. The difference in pollen production between pin and thrum flowers is not thought to be caused by the pollen size dimorphism. The percentage of pin pollen which is probably viable exceeds that of thrum pollen. In the population studied the morph ratio is 1:1, and plants are randomly dispersed with regard to morph type. Bumblebees are the main pollinators, and analysis of the stigmatic pollen load in naturally |xjllinated flowers shows that pin stigmas receive many more pollen grains than thrum stigmas. Intramorph pollination is considerable in pins, while thrums are subject to some differential pollination. Emasculation experiments have shown that intraflower pollination in the thrum morph is negligible. Aging of pin flowers has a reducing effect on their total pollen loads, while in thrums there is no change in total pollen load after the first days of anthesis.     

Agrobacterium tumefaciens-mediated transformation of Brassica napus winter cultivars

An efficient protocol for Agrobacterium tumefaciens-mediated transformation of six commercial Brassica napus winter cultivars is described. Two B. napus spring cultivars were analysed for comparison. Five strains of A. tumefaciens with different combinations of nopaline and octopine chromosomal backgrounds and virulence plasmids were used for cocultivation. Selection of putative regenerated transgenic plants was performed on kanamycin- or hygromycin-containing media. The scores of transgenic plants were calculated on the basis of GUS (-glucuronidase) activity, detected by the histochemical X-Gluc test. Target tissue derived from the cut surface of cotyledon petioles resulted in successful transformation with all the winter cultivars tested. Target tissue from hypocotyl segments resulted in a successful transformation with only one winter cultivar. The transformation rates for B. napus winter cultivars in this study were higher than in previous reports. Southern blot analysis revealed that integration of marker genes occurred in single and in multiple copies and at multiple loci in the genome. The transgenic plants all grew normally and developed fertile flowers after a vernalization period. After self-pollination, Southern blot analysis of selected GUS active F1 plants revealed that introduced marker genes were stably inherited to the next generation. These data demonstrate that morphologically normal, fertile transgenic plants of B. napus winter cultivars can be achieved with both nopaline- and octopine-derived A. tumefaciens strains. This protocol should have a broad application in improvement of Brassica napus winter cultivars by introduction of foreign genes