Synthesis of an Agonistic,Difluoro-Azido Photolabel of Angiotensin II and Labeling of the AT1 Receptor: Transmembrane Domains 3, 6, and 7 Form the Ligand-Binding Pocket

p-Azido-phenylalanine has been frequently used for photoaffinity labeling of target proteins such as the angiotensin receptors. However, chemical studies showed that simple aryl nitrenes first react intramolecularly, forming a semistable cyclic keteneimine and then reacting with nucleophile residues in the target structure like those of lysine and arginine. We synthesized 3,5-difluoro-4-azidophenylalanine where the formation of the keteneimine is prevented and where photoincorporation should be due to nonselective nitrene insertion only. This new amino acid was introduced in position 8 of angiotensin II and compared with the corresponding azidophenylalanine peptide using human AT₁ receptor as target. The new photolabel maintained full agonist activity and a similar yield of photolabeling but without the previously observed gradual hydrolysis. Several selective proteolyses of the labeled receptor indicate that the new photolabel forms three simultaneous contact regions on the hAT₁ receptor, suggestive of a nonselective behavior of the photolabel. A major contact was established in the sixth transmembrane domain but also in the third and seventh domain. Our results are in excellent agreement with those recently obtained from methionine proximity assay studies.     

Development and characterization of microsatellite loci in the eastern chipmunk (Tamias striatus)

We isolated and characterized 16 microsatellite loci in the eastern chipmunk, Tamias striatus. The loci were screened across 25 individuals from one population and shown to be polymorphic with the number of alleles per locus ranging from two to 17. Polymorphic information content ranged from 0.212 to 0.887 and observed heterozygosity ranged from 0.200 to 0.960. Only two loci (Chip 10 and Chip 25) deviated from Hardy–Weinberg equilibrium.     

The most ancient bark beetle known: a new tribe,genus and species from Lebanese amber (Coleoptera,Curculionidae, Scolytinae)

Abstract Cylindrobrotus pectinatus gen. et sp.n. , a new scolytine species from Cretaceous Lebanese amber, is described. A new tribe, Cylindrobrotini trib.n. , is proposed for this unique species, which demonstrates an unusual combination of some archaic and many advanced characters. This finding suggests that the Scolytinae became a distinct lineage of Curculionoidea from the Lower Cretaceous. Fossil records are reviewed, and some remarks on the origin and taxonomic position of bark and ambrosia beetles are made. Some comments on the various phylogenetic interpretations of the last 30 years are given, particularly in respect of their correspondence with the fossil record. The early appearance of Scolytinae in the fossil record before other Curculionidae (which appeared in the Upper Cretaceous) can be used as evidence against the hypothesis of bark beetles as offspring of weevils. The question of the taxonomic rank of bark beetles (separate subfamily or family) and their placement among other groups of the superfamily remains unsolved.     

Loss of genetic integrity correlates with stocking intensity in brook charr (Salvelinus fontinalis)

Supportive breeding and stocking performed with non‐native or domesticated fish to support sport fishery industry is a common practice throughout the world. Such practices are likely to modify the genetic integrity of natural populations depending on the extent of genetic differences between domesticated and wild fish and on the intensity of stocking. The purpose of this study is to assess the effects of variable stocking intensities on patterns of genetic diversity and population differentiation among nearly 2000 brook charr (Salvelinus fontinalis) from 24 lakes located in two wildlife reserves in Québec, Canada. Our results indicated that the level of genetic diversity was increased in more intensively stocked lakes, mainly due to the introduction of new alleles of domestic origin. As a consequence, the population genetic structure was strongly homogenized by intense stocking. Heavily stocked lakes presented higher admixture levels and lower levels of among lakes genetic differentiation than moderately and un‐stocked lakes. Moreover, the number of stocking events explained the observed pattern of population genetic structure as much as hydrographical connections among lakes in each reserve. We discuss the implications for the conservation of exploited fish populations and the management of stocking practices.     

Mandibulate chironomids: primitive or derived? (Diptera: Chironomidae)

Abstract Mandibulate functional mouthparts are reported in males and females of the two Early Cretaceous Chironomidae (Diptera): Wadelius libanicus Veltz et al., 2007 (in Tanypodinae) and Libanochlites Brundin, 1976 (transferred from the Podonominae to the Tanypodinae). Females of Haematotanypus libanicus gen.n. et sp.n. (subfamily Tanypodinae) have mandibulate mouthparts. Although currently considered as plesiomorphic structures, the presence of such mandibulate mouthparts in these Tanypodinae and in the recent Podonominae genera Archaeochlus and Austrochlus could correspond to reversals, based on a parsimony argument after the current chironomid phylogeny. On the contrary, similar mandibulate mouthparts probably are plesiomorphic in the Early Cretaceous Cretaenne kobeyssii gen.n. et sp.n. and Cretaenne inexpectata sp.n. (Aenneinae or stem group of recent Chironomidae).     

Use of tree rings to study the effect of climate change on trembling aspen in Québec

In this paper, we present a new approach, based on a mixed model procedure, to quantify the tree‐ring‐based growth‐climate relationship of trembling aspen along a latitudinal gradient from 46 to 54 °N in eastern Canada. This approach allows breaking down the growth response into general intersite and local climatic responses, and analyzing variations of absolute ring width as well as interannual variations in tree growth. The final model also integrates nonclimatic variables such as soil characteristics and the occurrence of insect outbreaks into the growth predictions. Tree level random effects on growth were important as intercepts but were nonsignificant for the climatic variables, indicating that a single climate–growth relationship was justified in our case. The response of tree growth to climate showed, however, a strong dependence on the spatial scale at which the analysis was performed. Intersite variations in tree growth were mostly dependent on variations in the thermal heat sum, a variable that showed low interannual and high intersite variation. When variation for a single site was analyzed, other variables showed up to be important while the heat sum was unimportant. Finally, future growth under six different climate change scenarios was simulated in order to study the potential impact of climate change. Results suggest only moderate growth increases in the northern portion of the gradient and a growth decrease in the southern portion under future climatic conditions.     

Phase contrast X‐ray synchrotron microtomography and the oldest damselflies in amber (Odonata: Zygoptera: Hemiphlebiidae)

Electrohemiphlebia barucheli gen. et sp. nov. and Jordanhemiphlebia electronica gen. et sp. nov. , two new genera and species are described, based on exceptional inclusions of hemiphlebiid damselflies in Cretaceous amber from France and Jordan. The type specimen of E. barucheli was studied using phase contrast X‐ray synchrotron microtomography, giving exceptional images and detailed information. Its comparison with the recent Hemiphlebia mirabilis confirms the attribution of several Cretaceous damselflies to the Hemiphlebiidae, showing that this particular group was widespread in the Early Cretaceous and probably originated in the Late Jurassic or earlier. The ecological niches today occupied by the small coenagrionoid damselflies were occupied during the Triassic and Jurassic by Protozygoptera, hemiphlebiids during the Early Cretaceous, and modern taxa in the Cenozoic.