Effect of Phosphlnothricin (Glufosinate) on Photosynthesis and Chlorophyll Fluorescence Emission by Barley Leaves Illuminated Under Photorespiratory and Non-Photorespiratory Conditions

The effect of phosphinothricin (PPT), an inhibitor of glutaminesynthetase, on several aspects of photosynthesis has been studiedin primary leaves of barley (Hordeum vulgare L.). When photorespirationwas suppressed, either by increasing CO₂ concentration to 0.7%,or by decreasing O₂ concentration to 1%, feeding the illuminatedleaves with 0·5 or 1·0 mM PPT did not affect photosynthesisto a noticeable extent. Conversely, when PPT-fed leaves wereilluminated in air, CO₂ uptake decreased continuously. Modificationof the components of chlorophyll fluorescence quenching indicatedincreased reduction of Q_A, the primary acceptor of photosystemII, and increased chloroplast energization. Feeding of PPT toleaves illuminated in air increased the quantum requirementof photosynthesis and decreased photosynthetic rate of oxygenevolution in saturating [CO₂] and high light intensity. It isconcluded that the effect of PPT on the photochemical processesis indirect, through the inhibition of CO₂ assimilation probablycaused by the depletion of intermediates of the reductive pentosephosphate cycle. Key words: Feeding, Hordeumvulgare L., quenching coefficients     

Genetic diversity among genotypes of Eryngium viviparum (Apiaceae): a plant threatened throughout its natural range

Eryngium viviparum (Apiaceae) is an endangered aquatic plant, listed as threatened in several European documents. The genotypes are distributed patchily in various wetlands in the north‐west of Spain and one is located in north‐west France. The study of the genetic diversity of a small population of a rare species is important for conservation and studies aimed at recovery programmes. Random amplified polymorphic DNA (RAPD) markers were used to assess the genetic diversity among five Spanish and one French genotype. This technique has contributed to the knowledge of the genetic diversity in E. viviparum, showing a greater genetic distance between the Spanish cluster formed by S1, S4 than the second cluster formed by S2, S3, S5 and the French genotype. Mantel testing did not show a significant correlation between genetic and geographical distances, but a significant correlation was found between altitude, habitat and genetic distance. The French genotype showed the highest level of polymorphism (28.16) and the highest percentage of exclusive markers (32%). One of these was isolated, purified, cloned and sequenced, revealing a high homology to a protein mainly expressed in roots. This could represent, for the F genotype, an adaptation to a specific habitat near the sea compared with the Spanish genotypes which grow inland. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 159 , 237–244.     

Egg yolk polypeptide variation in acridids (Orthoptera)

The polypeptide composition of egg yolk proteins was analysed in 23 species of grasshoppers by means of SDS-PAGE. Each species has a distinguishable set of polypeptides, varying from three to seven (although most show five or six), which can be classified into two groups of high (H) and low molecular weight (L). The patterns can be interpreted following a two-gene model, each with three domains that codify two H and one L polypeptides. The results suggest strong rearrangements in vitellin during speciation and a later slowing in divergence due to functional constraints. Consequently, the vitellin polypeptide composition may be used for species identification but does not provide phylogenetic information above the genus level. Intraspecific variability was found only in Eyprepocnemis plorans , which appears to be quite recent from an evolutionary point of view, and in Chorthippus parallelus where the subspecies differentiation may be older. © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 75 , 281–290.     

Managing invasive crayfish: use of X-ray sterilisation of males

1. In the last decade, many attempts have been made to contain the spread of the North American crayfish Procambarus clarkii , an invader of many European water bodies, but none has been successful.
2. This study investigates the effects that ionising irradiation has on the reproduction of P. clarkii males by analysing the behaviour of the treated individuals, their reproductive output, the vitality and survival of their offspring and the damages induced to their gonads.
3. We found that a dose of 20 Gy X-rays did not compromise either the survival or the mating ability of males, but reduced the size of their testes and significantly altered spermatogenesis. The number of aborted eggs was larger in clutches sired by treated males, with a consequent reduction (by 43%) in the number of offspring.
4. These results foster hopes in our efforts to control invasive crayfish, showing the potential effectiveness of ionising irradiation to reduce male fertility in the perspective of adopting the Sterile Male Release Technique to control P. clarkii populations.