Spatial distribution of zooplankton in a shallow eutrophic lake, with a discussion of its relation to fish predation

Zooplankton distribution in a small, eutrophic lake was studiedover two seasons as part of a wider analysis of the fish-planktoninteraction. Patchiness was evident at all sample spacings,but autocorrelation between adjacent samples became significantonly at mean spacings of <10 m. Patchiness could only rarelybe correlated with environmental variables in open water, butthere were consistent trends in the distribution of most taxawith respect to the shore. The limnetic assemblage within 10m of the shore showed some littoral influence in the presenceof littoral taxa and the relative paucity of euplankters. Emphasisis placed on the impact on plankton distribution of fish predation,which varies markedly in the study lake. ¹ Present address: Department of Conservation, PO Box 1493,Taupo, New Zealand     

The ecology of chronic wasting disease in wildlife

Prions are misfolded infectious proteins responsible for a group of fatal neurodegenerative diseases termed transmissible spongiform encephalopathy or prion diseases. Chronic Wasting Disease (CWD) is the prion disease with the highest spillover potential, affecting at least seven Cervidae (deer) species. The zoonotic potential of CWD is inconclusive and cannot be ruled out. A risk of infection for other domestic and wildlife species is also plausible. Here, we review the current status of the knowledge with respect to CWD ecology in wildlife. Our current understanding of the geographic distribution of CWD lacks spatial and temporal detail, does not consider the biogeography of infectious diseases, and is largely biased by sampling based on hunters' cooperation and funding available for each region. Limitations of the methods used for data collection suggest that the extent and prevalence of CWD in wildlife is underestimated. If the zoonotic potential of CWD is confirmed in the short term, as suggested by recent results obtained in experimental animal models, there will be limited accurate epidemiological data to inform public health. Research gaps in CWD prion ecology include the need to identify specific biological characteristics of potential CWD reservoir species that better explain susceptibility to spillover, landscape and climate configurations that are suitable for CWD transmission, and the magnitude of sampling bias in our current understanding of CWD distribution and risk. Addressing these research gaps will help anticipate novel areas and species where CWD spillover is expected, which will inform control strategies. From an ecological perspective, control strategies could include assessing restoration of natural predators of CWD reservoirs, ultrasensitive CWD detection in biotic and abiotic reservoirs, and deer density and landscape modification to reduce CWD spread and prevalence.     

Acknowledging uncertainty in evolutionary reconstructions of ecological niches

Reconstructing ecological niche evolution can provide insight into the biogeography and diversification of evolving lineages. However, comparative phylogenetic methods may infer the history of ecological niche evolution inaccurately because (a) species' niches are often poorly characterized; and (b) phylogenetic comparative methods rely on niche summary statistics rather than full estimates of species' environmental tolerances. Here, we propose a new framework for coding ecological niches and reconstructing their evolution that explicitly acknowledges and incorporates the uncertainty introduced by incomplete niche characterization. Then, we modify existing ancestral state inference methods to leverage full estimates of environmental tolerances. We provide a worked empirical example of our method, investigating ecological niche evolution in the New World orioles (Aves: Passeriformes: Icterus spp.). Temperature and precipitation tolerances were generally broad and conserved among orioles, with niche reduction and specialization limited to a few terminal branches. Tools for performing these reconstructions are available in a new R package called nichevol.     

Novel 2′-Deoxy Pyrazine C-Nucleosides Synthesized VIA Palladium-Catalyzed Cross-Couplings

Abstract

The palladium-catalyzed cross-couplings of 2-chloro-3,5-diamino-6-iodopyrazine (1a) and methyl 3-amino-6-iodopyrazine-2-carboxylate (1b) with 1,4-anhydro-3,5-O-bis[(tert-butyl)dimethylsilyl]-2-deoxy-D-erythro-pent-1-enitol (2) followed by desilylation and stereospecific reduction of the 2′-deoxy-3′-keto adduct leads to the formation of 2-chloro-6-(2-deoxy-ß-D-ribofuranosyl)-3,5-diaminopyrazine (4a) and methyl 3-amino-6-(2-deoxy-ß-D-ribofuranosyl)pyrazine-2-carboxylate (4b) in 58% yield and 21% yield, respectively. These are the first syntheses of the heretofore unknown 2′-deoxy pyrazine C-nucleosides and demonstrate the utility of a convergent approach for the synthesis of pyrazine C-nucleosides.     

Homo-C-Nucleoside Analogs† II. Synthesis and Anomeric Configuration of 4-(2,5-Anhydro-D-Gluco-PEntitol-1-YL)-2-Phenyl2H-1,2,3-Triazole††

Abstract

Treatment of 4-(D-gluco-pentitol-l-y1)-2-pheny1–2H-1,2,3-triazole (1) with p-toluenesulfonyl chloride in pyridine solution, afforded the homo-C-nucleoside analog, 4-(2,5-anhydro-D-gluco-pentitol-1-yl)-2-phenyl-2H-1,2,3-triazole (2) as well as its partial p-toluenesulfonyl derivative (3). 4-(5-Chloro-5-deoxy-D-gluco-pentitol-1-yl)-2-phenyl-2H-1,2,3-triazole (8), was isolated as a byproduct from the reaction. The structure and anomeric configuration of 2 was determined by acylation, ¹H, ¹³C NMR, and NOE, spectroscopy as well as mass spectrometry.

     

Design,Synthesis and Antiviral Activity of α-L-Arabinofuranosyl Derivatives of 2-Substituted-5,6-dichlorobenzimidazoles

Abstract

A number of 2-substituted-5,6-dichloro-l-(α-L-arabinofuranosyl)benzimidazoles have been prepared by condensation of 2-bromo-5,6-dichlorobenzimidazole or 2,5,6-trichlorobenzimidazole with tetra-O-acetyl-L-arabinofuranose. 2-Alkylamino derivatives were prepared by a substitution of the 2-chloro group with the appropriate amines. All target compounds were evaluated for activity against HCMV and HSV-1. The 2-chloro and 2-bromo derivatives showed moderate activity against HCMV at non-cytotoxic concentrations.     

Monitoring oak processionary moth Thaumetopoea processionea L. using pheromone traps: the influence of pheromone lure source,trap design and height above the ground on capture rates

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The Use of Combining Ability Analysis to Identify Elite Parents for Artemisia annua F1 Hybrid Production

Artemisia annua is an important medicinal crop used for the production of the anti-malarial compound artemisinin. In order to assist in the production of affordable high quality artemisinin we have carried out an A. annua breeding programme aimed at improving artemisinin concentration and biomass. Here we report on a combining ability analysis of a diallel cross to identify robust parental lines for hybrid breeding. The parental lines were selected based on a range of phenotypic traits to encourage heterosis. The general combining ability (GCA) values for the diallel parental lines correlated to the positive alleles of quantitative trait loci (QTL) in the same parents indicating the presence of beneficial alleles that contribute to parental performance. Hybrids generated from crossing specific parental lines with good GCA were identified as having an increase in both artemisinin concentration and biomass when grown either in glasshouse or experimental field trials and compared to controls. This study demonstrates that combining ability as determined by a diallel cross can be used to identify elite parents for the production of improved A. annua hybrids. Furthermore, the selection of material for breeding using this approach was found to be consistent with our QTL-based molecular breeding approach.     

Functionally Referential Communication in Mammals: The Past,Present and the Future

Whether animal vocalizations have the potential to communicate information regarding ongoing external events or objects has received considerable attention over the last four decades. Such ‘functionally referential signals’ (Macedonia & Evans 1993) have been shown to occur in a range of mammals and bird species and as a consequence have helped us understand the complexities that underlie animal communication, particularly how animals process and perceive their socio‐ecological worlds. Here, we review the existing evidence for functionally referential signals in mammals according to the framework put forward in the seminal Macedonia and Evans review paper. Furthermore, we elucidate the ambiguities regarding the functionally referential framework that have become obvious over the last years. Finally, we highlight new potential areas for investigation within referential signalling. We conclude the functionally referential framework is still informative when interpreting the meaning of animal vocalizations but, based on emerging research, requires further integration with other approaches investigating animal vocal complexity to broaden its applicability.     

Social monitoring via close calls in meerkats

Social monitoring of the actions of group members is thought to be a key development associated with group living. Humans constantly monitor the behaviour of others and respond to them in a flexible way depending on past interactions and the current social context. While other primates have also been reported to change their behaviour towards other group members flexibly based on the current state of their relationship, empirical evidence is typically linked to contextually specific events such as aggressive or reproductive interactions. In the cooperatively breeding meerkat (Suricata suricatta), we investigated whether subordinate females use frequently emitted, non-agonistic close calls to monitor the location of the dominant female and whether they subsequently adjust their response based on recent social interactions during conflict and non-conflict periods. Subjects discriminated between the close calls of the dominant female and control playbacks, responding by approaching the loudspeaker and displaying submissive behaviour only if they were currently threatened by eviction. Our results suggest that meerkats assess the risk for aggressive interactions with close associates depending on social circumstances, and respond accordingly. We argue that social monitoring based on non-agonistic cues is probably a common mechanism in group-living species that allows the adjustment of behaviour depending on variation in relationships.