Screening Global Positioning System Location Data for Errors Using Animal Movement Characteristics

Abstract: Animal locations estimated by Global Positioning System (GPS) inherently contain errors. Screening procedures used to remove large positional errors often trade data accuracy for data loss. We developed a simple screening method that identifies locations arising from unrealistic movement patterns. When applied to a large data set of moose (Alces alces) locations, our method identified virtually all known errors with minimal loss of data. Thus, our method for screening GPS data improves the quality of data sets and increases the value of such data for research and management.     

Host‐plant genotype mediates supply and demand of animal food in an omnivorous insect

1. Omnivorous predators can protect plants from herbivores, but may also consume plant material themselves. Omnivores and their purely herbivorous prey have previously been thought to respond similarly to host‐plant quality. However, different responses of omnivores and herbivores to their shared host plants may influence the fitness, trophic identity, and population dynamics of the omnivores. 2. The aim of the present study was to show that an omnivorous heteropteran (Anthocoris nemorum L.) and two strictly herbivorous prey species respond differently to different genotypes of their shared host plant, Salix. Some plant genotypes were sub‐optimal for the omnivore, although suitable for the herbivores, and vice versa. 3. The contrasting patterns of plant suitability for the omnivore and the herbivores highlight an interaction between plant genotype and omnivores' access to animal food. Plant genotypes that were sub‐optimal for the omnivore when herbivores were experimentally excluded became the best host plants when herbivores were present, as in the latter situation additional prey became available. By contrast, the quality of plant genotypes that were intrinsically suitable for omnivores, did not improve when herbivores were present as these plant genotypes were intrinsically sub‐optimal for herbivores, thus providing omnivores with almost no additional animal food. 4. The differential responses of omnivores and their prey to the same host‐plant genotypes should allow omnivores to colonise sub‐optimal host plants in their capacity as predators, and to colonise more suitable host plants in their capacity as herbivores. It may thus be difficult for Salix to escape herbivory entirely, as it will rarely be unsuitable for both omnivores and pure herbivores at the same time.     

Peripheral diabetic neuropathy and polyunsaturated fatty acid supplementations: natural sources or biotechnological needs?

The two essential fatty acids linoleic and alpha-linolenic acids, precursors of the n-6 and n-3 PUFA family, respectively, are known to play a strong regulatory function on cells via their incorporation into membrane phospholipids, and also on microcirculation by the production of eicosanoids. Moreover, diabetes mellitus induces impairment in PUFA metabolism due to an inhibition of desaturases, the enzymes involved in their synthesis. The decrease in PUFA bioavailability will conduct to marked alterations in membranes as well as impairment of the microcirculation. Those metabolic perturbations are involved in part in the degenerative complications of diabetes such as neuropathy. Nutritional supplementations with PUFA have given very interesting results in experimental diabetic neuropathy but also in human diabetic neuropathy. The gamma linolenic and arachidonic acids, members of the n-6 family, prevent the physiological abnormalities associated to neuropathy. The results obtained with the n-3 family PUFA are more discordant, probably because of the simultaneous use of eicosapentaenoic and docosahexaenoic acids. Nevertheless, the use of docosahexaenoic acid-enriched phospholipids produced positive results in the treatment of experimental diabetic neuropathy. These PUFA are available from natural sources but a biotechnological demand exists to provide these PUFA in different structural forms.     

Fine structure of ribosomal RNA. III. Location of evolutionarily conserved regions within ribosomal DNA

In order to define functional regions within ribosomal RNA, we have identified areas of the molecule which have been conserved during evolution. Our previous studies showed that there is evolutionary conservation between the rRNAs of different eukaryotes and that the sequences conserved between distantly related species are a subset of those conserved between closely related species. In the present work, we have employed DNA-DNA and DNA-RNA hybridization techniques to localize these conserved regions to mapped restriction fragments 50 to 300 base-pairs in length within cloned Xenopus laevis ribosomal DNA. Our experiments have detected evolutionary conservation only within the coding regions, suggesting that if there is any conservation within the spacers, these sequences must be very short. Regions of conservation can be classified either by evolutionary distance or by the extent of conservation between two species. Three regions, including one near the 3' end of 18 S and two near the 3' end of 28 S rRNA are conserved over great evolutionary distance, that is between Escherichia coli and X. laevis. In addition, several fragments in the central portions of the 188 and 28 S rRNAs are exceptional in the extent of their conservation between yeast and Xenopus. We have been able to correlate the regions we have defined as conserved with certain structural or functional roles, such as initiation of translation, possible interaction with transfer RNA, rRNA methylation, and the site where intervening sequences interrupt some eukaryotic rRNAs. As a result, these studies serve to define relatively short (less than 300 base-pairs) segments within the almost 11,000 base X. laevis rDNA repeat unit which are worthy of further investigation.     

Delocalization of some small nucleolar RNPs after actinomycin D treatment to deplete early pre-rRNAs

Retention of some components within the nucleolus correlates with the presence of rRNA precursors found early in the rRNA processing pathway. Specifically, after most 40S, 38S and 36S pre-rRNAs have been depleted by incubation of Xenopus kidney cells in 0.05 μg/ml actinomycin D for 4 h, only 69% U3 small nucleolar RNA (snoRNA), 68% U14 snoRNA and 72% fibrillarin are retained in the nucleolus as compared with control cells. These nucleolar components are important for processing steps in the pathway that gives rise to 18S rRNA. In contrast, U8 snoRNA, which is used for 5.8S and 28S rRNA production, is fully retained in the nucleolus after actinomycin D treatment. Therefore, U8 snoRNA is in a different category than U3 and U14 snoRNA and fibrillarin. It is proposed that U3 and U14 snoRNA and fibrillarin, but not U8 snoRNA, bind to the external transcribed spacer or internal transcribed spacer 1, and when these binding sites are lost after actinomycin D treatment some of these components cannot be retained in the nucleolus. Other binding sites may also exist, which would explain why only some and not all of these components are lost from the nucleolus. Received: 16 September 1996; in revised form: 21 November 1996 / Accepted: 28 November 1996