Diversity of den sites used by pine martens Martes martes: a response to the scarcity of arboreal cavities?

• 1 We compiled a sample of 370 pine marten dens to test the hypothesis that a scarcity of sites leads to the use of suboptimal structures.
• 2 The sample was influenced by detection methods. Radio-tracking revealed cryptic dens but few natal dens; chance encounters revealed dens in buildings and other man-made structures. A total of 82.8% of natal dens were detected by chance encounters.
• 3 Most dens were associated with trees (44.3%), rocks (27.6%) and buildings (13.8%). The natal den subsample comprised buildings (44.3%), trees (22.8%), other man-made structures (17.1%) and rocks (14.3%). A total of 69.6% of dens were elevated and typically in structures offering limited shelter. Only 9.8% of all dens were in elevated tree cavities.
• 4 This diversity of dens reflects a scarcity of arboreal cavities. The alternative structures are suboptimal in terms of energetic costs and risks of predation, and this may limit breeding success in some populations.

     

Potyviral resistance derived from cultivars of Phaseolus vulgaris carrying bc-3 is associated with the homozygotic presence of a mutated eIF4E allele

Eukaryotic translation initiation factors (eIFs) play a central role in potyviral infection. Accordingly, mutations in the gene encoding eIF4E have been identified as a source of recessive resistance in several plant species. In common bean, Phaseolus vulgaris , four recessive genes, bc-1 , bc-2 , bc-3 and bc-u , have been proposed to control resistance to the potyviruses Bean common mosaic virus (BCMV) and Bean common mosaic necrosis virus . In order to identify molecular entities for these genes, we cloned and sequenced P. vulgaris homologues of genes encoding the eIF proteins eIF4E, eIF(iso)4E and nCBP. Bean genotypes reported to carry bc-3 resistance were found specifically to carry non-silent mutations at codons 53, 65, 76 and 111 in eIF4E . This set of mutations closely resembled a pattern of eIF4E mutations determining potyvirus resistance in other plant species. The segregation of BCMV resistance and eIF4E genotype was subsequently analysed in an F₂ population derived from the P. vulgaris all-susceptible genotype and a genotype carrying bc-3 . F₂ plants homozygous for the eIF4E mutant allele were found to display at least the same level of resistance to BCMV as the parental resistant genotype. At 6 weeks after inoculation, all F₂ plants found to be BCMV negative by enzyme-linked immunosorbent assay were found to be homozygous for the mutant eIF4E allele. In F₃ plants homozygous for the mutated allele, virus resistance was subsequently found to be stably maintained. In conclusion, allelic eIF4E appears to be associated with a major component of potyvirus resistance present in bc-3 genotypes of bean.     

Estimation of the Anion-Exchange Capacity of the Cell Wall of Nitella flexilis

Diffusion potentials in KCI and triphenyl phosphonium chloride(TPP) solutions have been measured across an isolated cell wallof Nitella flexilis either after pretreatment by difluoronitrobenzene(DFNB), a compound which reacts with the protein amino groups,or after alkalization of the external solutions. In both cases,it appears that the cationic transport numbers are enhancedwith respect to the controls. These data suggest that the maineffect of the two treatments was to deprive the wall of positivecharges carried by protonized amino groups. The changes in t_Kwere used to roughly estimate the anion-exchange capacity ofthe wall.     

Female-extended control over their reproductive investment: the role of early mating interactions on oocyte maturation in the terrestrial crustacean Armadillidium vulgare (Latreille, 1804)

Abstract

In the terrestrial crustacean Armadillidium vulgare, the prolonged presence of males along with females is known to boost female reproductive physiology, and the so-called ‘male-effect’ was best characterized by a significant shortening of the pre-parturial intermoult (PPI) during which oocyte maturation spontaneously takes place. Continuous presence of a male over that period can speed up vitellogenesis and the moulting cycle, so to reduce female PPI by 15–20 days (shortening of 30–40%, in comparison to females reared with other females or in isolation, respectively). In the last investigation on the subject, we revealed that sexual interactions may start much sooner than previously thought in this species, and suggested that the observed ‘male-effect’ may likely result from early mating stimulations. Here we tested the specific effect of controlled mating interactions (one or two mating events at different times) on female PPI. We revealed that male presence for the time (about 2 h) that allowed a single mating to occur was enough to reduce the female intermoult by about 10 days (shortening of 19%, in comparison to females reared in similar conditions but in the absence of a mating interaction). Moreover, results indicate that the earlier and longer the copulations, the stronger the ‘male-effect’. Altogether, the data support the conclusion that A. vulgare females are adjust their reproductive physiology according to the presence/absence and the intensity of male mating stimuli. We place the findings in a broader ecological context, revise the so far prevailing view on the ‘male-effect’, and stress its possible significance in relation to the occurrence of feminising bacteria in this and other terrestrial isopod species.     

Hawk-moth scale analysis and pollination specialization in the epilithic Malagasy endemic Aerangis ellisii (Reichenb. fil.) Schltr. (Orchidaceae)

The pollination biology of the epilithic endemic Aerangis ellisii (Reichenb. fil.) Schltr. (Orchidaceae) was studied on an inselberg in the Antananarivo region, central Madagascar. The flowers exhibit long nectariferous spurs indicative of hawk-moth pollination, the mechanism evidently involving pollinia transfer via the frons and palpi of the vectors. Analysis of hawk-moth scales on naturally pollinated stigmas showed that the principal pollinators were Agrius conuolvuli (Linnaeus) and Panogena lingens (Butler). Proboscis morphology of long-tongued Malagasy Sphingidae in relation to nectar position and spur morphology in A. ellisii also indicated that A. conuolvuli and P. lingens were best suited to interact with the plant's floral adaptation. Aerangis ellisii seems to display a relatively moderate specialization versus the Malagasy hawk-moth guild since its nectar is accessible even to those long-proboscis hawk-moth species which are not able to act as pollinators.