Survival of Breeding Pacific Common Eiders on the Yukon-Kuskokwim Delta,Alaska

ABSTRACT Populations of Pacific common eiders (Somateria mollissima v-nigrum) breeding in Alaska, USA, have declined markedly over the past 40 years. We studied survival of adult female Pacific common eiders using capture—recapture of nesting hens at 3 sites on the Yukon-Kuskokwim Delta (YKD), Alaska from 1994 to 2004. We used data consisting of 268 recapture events from 361 uniquely marked individuals to investigate temporal, geographic, and environmental variation in adult female survival. Our results suggest apparent annual survival of adult eiders from the YKD was high (0.892, SE = 0.022) and spatially and temporally invariant (σ² = 0.005), a pattern consistent with other long-lived marine birds. Moreover, our results suggest adult survival may be functionally fixed for Pacific common eiders, and at the present, adult survival may be relatively unresponsive to environmental or management perturbations. Our data did not support hypothesized variation in survival relative to mortality factors such as predation on breeding grounds, physiologic costs of reproduction, and wintering conditions. Although changes in adult survival likely have a large potential effect on prospective population growth, our results suggest viable management actions aimed at increasing survival may be extremely limited.     

X-chromosome inactivation and escape

X-chromosome inactivation, which was discovered by Mary Lyon in 1961 results in random silencing of one X chromosome in female mammals. This review is dedicated to Mary Lyon, who passed away last year. She predicted many of the features of X inactivation, for e.g., the existence of an X inactivation center, the role of L1 elements in spreading of silencing and the existence of genes that escape X inactivation. Starting from her published work here we summarize advances in the field.     

Studies in the Respiratory and Carbohydrate Metabolism of Plant Tissues3: VIII. AN INHIBITION OF RESPIRATION IN PEAS INDUCED BY 'OXYGEN POISONING'

A pressure of oxygen of 5 atmospheres has been shown to inhibitmarkedly the carbon-dioxide output of green shelled peas. Accompanyingthis decrease, an accumulation of pyruvic and ‘citric’acid has been noted, whilst a depletion in the concentrationof -ketoglutaric acid and, in some experiments, of malic acidoccurred. The results have been interpreted as indicating thathigh pressures of oxygen interfere with the metabolism of citricacid causing a ‘jamming’ of the tricarboxylic acidcycle; thus, under the conditions prevailing during the oxygentreatment, the tricarboxylic acid cycle is considered to bea major respiratory pathway in peas.     

Microsatellite loci for Bombus spp.

We report the details and characteristics of a total of 44 novel microsatelllite loci for Bombus spp. Most of them are highly polymorphic in Bombus terrestris, and a high degree of polymorphism is also found where these primers have been tested in 10 other bumblebee species. These markers will therefore be useful for the genetic study of this group.     

Drought and Oxidative Load in the Leaves of C3 Plants: a Predominant Role for Photorespiration?

Although active oxygen species are produced at high rates inboth the chloroplasts and peroxisomes of the leaves of C₃ plants,most attention has focused on the potentially damaging consequencesof enhanced chloroplastic production in stress conditions suchas drought. This article attempts to provide quantitative estimatesof the relative contributions of the chloroplast electron transportchain and the glycolate oxidase reaction to the oxidative loadplaced on the photosynthetic leaf cell. Rates of photorespiratoryH₂O₂ production were obtained from photosynthetic and photorespiratoryflux rates, derived from steady-state leaf gas exchange measurementsat varying irradiance and ambient CO₂. Assuming a 10 % allocationof photosynthetic electron flow to the Mehler reaction, photorespiratoryH₂O₂ production would account for about 70 % of total H₂O₂ formedat all irradiances measured. When chloroplastic CO₂ concentrationrates are decreased, photorespiration becomes even more predominantin H₂O₂ generation. At the increased flux through photorespirationobserved at lower ambient CO₂, the Mehler reaction would haveto account for more than 35 % of the total photosynthetic electronflow in order to match the rate of peroxisomal H₂O₂ production.The potential signalling role of H₂O₂ produced in the peroxisomesis emphasized, and it is demonstrated that photorespiratoryH₂O₂ can perturb the redox states of leaf antioxidant pools.We discuss the interactions between oxidants, antioxidants andredox changes leading to modified gene expression, particularlyin relation to drought, and call attention to the potentialsignificance of photorespiratory H₂O₂ in signalling and acclimation.     

The use of vesicular-arbuscular mycorrhizal roots grown by the nutrient film technique as inoculum for field sites

Bean roots grown by the nutrient film technique and infected with vesicular-arbuscular mycorrhizal fungi were successfully used as inoculum for red clover growing in an unsterile field site. The endophyte introduced with the roots became well established in the presence of indigenous mycorrhizal fungi.     

Metabolism of α-Glyceryl Ethers by Crithidia fasciculata. I. Study of the In Vivo Degradation of Exogenous Chimyl and Batyl Alcohols1

ABSTRACT. [¹⁴C]chimyl and [³H]batyl alcohols were added to Crithidia fasciculata cultures during the mid-log phase of cell growth, and the lipid extracts of the cells were analyzed for degradation products. C. fasciculata cells were able to take up exogenous glyceryl ethers, and in amounts as high as the endogenous lipid content. The glyceryl ether taken up by the cells was incorporated into lipids either prior to the ether bond cleavage or after degradation to fatty acid. The extent of degradation and the degree of incorporation of degradation products into cellular lipid were higher for chimyl than for batyl alcohol. Batyl alcohol was not metabolized efficiently, leading to the formation of large intracellular pools of free substrate. One product of glyceryl ether degradation was identified as alkyl-dihydroxy acetone, and was detected inside and outside of the cells. The data strongly suggest that this product is the first stable intermediate in the degradation process and indicate that the extracellular formation of alkyl-dihydroxy acetone is due to the action of exocnzyme; ecteted by the cells. The constant detection of alk I cnyl glycerol among the degradation products indicates the existence of a second mechantsm in C. fasciculata for converting the alkyl-to alkenyl-glycerol.     

Physiological Changes in the Hemiparasite Rhinanthus serotinus before and after Attachment

Growth of the hemiparasite Rhinanthus serotinus (Schönh.) Oborny was greatly stimulated after attachment of the parasite to the roots of the host plant, Hordeum vulgare L. In order to find the limiting factors for the growth of Rhinanthus without a host, unattached and attached Rhinanthus plants were compared. Within I day after attachment the contents of nitrogen, phosphorus, potassium, magnesium, and sodium increased considerably. Organic nitrogen and phosphorus compounds were rapidly synthesized in attached Rhinanthus. The accumulation of sugars in unattached Rhinanthus and the decrease in sugar content after attachment suggested that the main requirement from the host was not for carbohydrates.     

Chemotaxonomy, variation and geographical distribution of the Empetraceae

Thirty-one flavonoids (and related phenolics) were found in leaves of the six species in the three genera of Empetraceae (90 populations studied) and five further pigments in fruits of Empetrum. Affinity with the Ericaceae is supported by the occurrence of the 3-galactosidesof gossypetin, malvidin, delphinidin, cyanidin and peonidin. The distribution of leaf flavonoids agrees with both the recognition of three genera and species-delimitation in Ceratiola and Corema. In Empetrum , the flavonoids differ modally in the three species usually accepted, thus confirming data on fruit colour and breeding systems, and suggesting that the genus comprises one species with about three subspecies at diploid and tetraploid levels. The black fruits of most Northern Hemisphere plants contain malvidin, petunidin and delphinidin, while the red fruits of almost all Southern Hemisphere populations ( E. rubrum ) contain cyanidin and peonidin and provide a rare example of the association of cyanidin (instead of delphinidin) with the wild-type allele.
In leaf flavonoid content the diploid E. nigrum is much closer to its presumed tetraploid derivative E. eamesii than to the diploid E. rubrum , which differs most from E. eamesii. Flavonoid patterns and breeding system distinguish most E. rubrum populations from those isolated in Tristan da Cunha-Gough Island. The phytogeographical importance of the phytOGhemical results is discussed.