Eight polymorphic microsatellite loci for the aquatic fungus Tetracladium marchalianum

We have identified eight polymorphic microsatellite loci from the aquatic haploid fungus Tetracladium marchalianum. Microsatellite polymorphism was evaluated using 90 fungal isolates, each of single spore origin, from submerged leaves in Illinois and Wisconsin rivers in the USA. The number of alleles observed for a single locus ranged from three to 13, with up to 10 observed from a population. These genetic markers will be useful to evaluate population structure, genotypic diversity, and the reproductive mode of T. marchalianum.     

The sealed storage of moist flax with and without the use of chemical preservatives

The suitability of ensilage as a means of preserving flax was investigated in a series of experiments in which 400 kg round bales of fresh flax were sealed in polyethylene film or plastic wrapped, with or without the addition of formic acid at 2.5 litre t^-1 or formalin at 5.6 litre t^-1 at the time of baling. Plastic wrapping provided a more effective seal than the bags which were easily punctured by the flax roots resulting in moulding and deterioration of the flax. Where the seal was not broken untreated flax underwent a clostridial fermentation and the pH fell to about 4.8. Cellulolytic activity degraded the flax fibre over a period of 3 to 6 months. The addition of formic acid reduced the cellulolytic activity provided the seal was not broken. In an experiment with 4 kg batches of flax of 65%, 40% or 25% MC sealed in polyethylene film, the addition of formic or propionic acids at 20 g kg^-1 DM did not prevent moulding and deterioration, but both NH₃ and SO₂ at 40 g kg^-1 DM preserved the physical structure of the flax. The NH₃ darkened the flax and made it pliable and unscutchable while the SO₂ bleached it and preserved the fibre without microbiological deterioration. The presence of acids on the moist stored flax appeared to inhibit the progress of normal water retting.     

Electrophysiological Measurements on the Root of Atriplex hastata

The ion contents and membrane potentials of the cells of young,hydroponically cultured seedlings of Atriplex hastata L. var.salina, Wallr. have been measured at several different NaClconcentrations. The total tissue concentrations of Na⁺ and Cl^–increase as external NaCl increases, but there is always a markedexcess of internal Na⁺ over Cl^–; this is balanced by endogenousorganic anion formation with a concomitant extrusion of H⁺ tothe bathing solution. Membrane potentials of the root cells remain essentially invariantwith changes in external NaCl at approx. –130 mV; thereis no evidence of a radial gradient of potential across theroot. The potential seems to contain a cyanide-sensitive electrogeniccomponent, also invariant with NaCl concentration, of about–70 mV, and a diffusion component. The electrogenic componentseems likely to be a H⁺ efflux, probably through a H⁺ uniportATPase.     

Dioecy and wind pollination in Pernettya rigida (Ericaceae) of the Juan Fernández Islands

Pernetttya rigida is endemic to the Juan Fernández archipelago. Although all flowers are complete, with seemingly fertile stamens and pistils, differences in fruit production and detailed field, anatomical, and morphological studies indicate they are functionally unisexual, and the species is consequently dioecious. A comparison of 15 features demonstrated sigdicant differences between the sexes. The populational sex ratio is 1:1. Nectaries located between the filaments produce small amounts of floral nectar with similar sugar composition in both sexes. There are =33,357 (or = 133,429) pollen tetrads (or pollen grains)/male flower and =109 ovules/female flower. No tetrads in either hand self-pollinated or open pollinated male flowers showed any pollen germination. Tetrads on open- and hand-pollinated female flowers germinate. Female flowers do not show autogamy or apomixis. During more than 80 hours of field observation, we recorded only seven floral visitors (representing three insect species). In spite of this, openpollinated female flowers have abundant fruit and seed-set. Thus, we conclude that pollen is transferred abiotically and the ever-present wind over the exposed ridges of the islands is the likely dispersal agent. A number of anemophilous features, such as dry pollen and exposed habitat, support this conclusion. Thus, dioecy and anemophily have evolved independently, in situ , in this species in this remote locality. Preservation of habitat and elimination of competitive invasives are the primary conservation challenges.     

Trapping oestrid parasites of reindeer: the relative age, fat body content and gonotrophic conditions of Cephenemyia trompeand Hypoderma tarandifemales caught in baited traps

Abstract. Dissection of flies caught in northern Norway revealed that only mated, gravid females of H.tarandi (L.) and larviparous C.trompe (Modeer) were caught in host-mimicking C0₂-baited traps. Trapped females had the same gonotrophic and fat body (FB) conditions as females caught on and around reindeer. Most trapped females of both species were of middle to old age, having only one-half to no FB reserves left and only a few to moderate numbers of eggs or larvae remaining. Most young females trapped also had previously oviposited or larviposited at least once, and some newly eclosed, mated females were present throughout the fly season. Based on the known location of reindeer herds, it was evident that trapped flies that had recently oviposited or larviposited had dispersed into the trapping area from 25–100 km away. Declining FB reserves sustained wild-caught C.trompe females (and in utero larvae) in the laboratory for 14 days and H.tarandi females for 18 days. Reserve FB also was depleted during long flights. Females of both species that flew for the longest times (5.1–11.7 h) on a laboratory flight mill had low FB reserves, but nearly maximum numbers of eggs or larvae. Conversely, most females that flew for less than 5 h on the flight mill had little or no FB remaining, and few eggs or larvae. The large FB reserves accumulated as larvae feed in the vertebrate host enable the non-feeding adults to survive and infect their hosts even after prolonged periods of flight-inhibiting climatic conditions.