Characterization of microsatellite loci for the detection of temporal genetic shifts within a single cohort of the brown demoiselle,Neopomacentrus filamentosus

Neopomacentrus filamentosus, a common damselfish on the Indo–Australian archipelago, undergoes significant shifts in size and mitochondrial genetic structure upon larval settlement and metamorphosis to juvenile stages. We characterized five polymorphic microsatellite loci in order to study temporal genetic shifts within a single generation of N. filamentosus sampled first as larval settlers then again as demersal juvenile recruits. All loci were extremely polymorphic and exhibited high levels of heterozygosity. While all loci from the larval samples conformed to Hardy – Weinberg expectations, significant heterozygote deficiencies were seen in two loci in the juvenile samples, likely due to extreme size‐selective mortality imposed post‐settlement.     

Validation of the first step of the heuristic refinement method for the derivation of solution structures of proteins from NMR data

A new method for the analysis of NMR data in terms of the solution structure of proteins has been developed. The method consists of two steps: first a systematic search of the conformational space to define the region allowed by the initial set of experimental constraints, and second, the narrowing of this region by the introduction of additional constraints and optional refinement procedures. The search of the conformational space is guided by heuristics to make it computationally feasible. The method is therefore called the heuristic refinement method and is coded in an expert system called PROTEAN. The paper describes the validation of the first step of the method using an artificial NMR data set generated from the known crystal structure of sperm whale carbon monoxymyoglobin. It is shown that the initial search procedure yields a low-resolution structure of the myoglobin molecule, accurately reproducing its main topological features, and that the precision of the structure depends on the quality of the initial data set.     

PHYLOGENETIC ANALYSIS OF THE EVOLUTION OF ALTERNATIVE SOCIAL BEHAVIOR IN THE MANAKINS (AVES: PIPRIDAE)

Phylogenetic analyses of lekking, lek spatial organization, and cooperative and coordinated lek display in the manakins (Aves: Pipridae) demonstrate that variation in social behavior in the group has a strong, phylogenetic component. Two of the three classes of social behavior examined also show significant phylogenetic constraints. Current adaptive plasticity models are insufficient to explain the phylogenetic variation in these behaviors in the manakins. These findings support the conclusion that vertebrate reproductive social behavior has an evolutionary history, and that it is not determined solely by adaptive individual plasticity to current conditions. The evolution of social behavior, particularly through sexual selection, can have historical consequences that can limit subsequent behavioral adaptation.     

Some factors affecting the composition of tropical ichneumonid faunas

An increasing accumulation of data shows that tropical ichneumonid faunas are no more species-rich than extra-tropical ones, despite the fact that most of their host groups show increased tropical species-richness. This lack of increase in ichneumonid species-richness can be attributed to the absence of groups whose hosts are not present (e.g. Ctenopelmatinae) and poor tropical representation by many groups of diurnal koinobionts (e.g. Campopleginae). Low host density has been postulated as a barrier to tropical koinobiont species-richness, but it is here suggested that this is not the only limiting factor as groups of nocturnal koinobionts, such as the Ophioninae, show increased tropical species-richness. It is postulated that koinobionts have the capability of being able to locate sparse hosts, but as they host-search in flight, a prolonged daytime host-searching period in the tropics would expose them to a high level of predation pressure. By being active at night koinobionts can avoid diurnally active predators. It is also postulated that sparse hosts may be located more easily at night and more habitats may be climatically suitable for ichneumonid activity when they are not subject to direct sunlight. Idiobionts, such as the Mesostenini and Pimplini, are more species-rich and morphologically diverse in the tropics than they are in extra-tropical regions. It is suggested that this results from the fact that tropical idiobionts can be active during the whole of the diapausing period, when their hosts are available, whereas activity by temperate idiobionts is prevented by inclement weather. Although many idiobionts are probably less exposed to predators than koinobionts, many have evolved obvious protective devices.     

The particle size characteristics of fluvial suspended sediment: an overview

The particle size characteristics of suspended sediment are of fundamental importance in understanding its role in a variety of environmental processes. Existing knowledge concerning the spatial and temporal variability of the grain size composition of suspended sediment is, however, relatively limited. At the global scale, major contrasts may exist between individual rivers in the calibre of their suspended load and this may be related to a number of controls including climate, catchment geology and basin scale. Any attempt to understand the precise relationship between the grain size characteristics of suspended sediment and those of its source material must also take account of the selectivity of erosion and delivery processes. A local case study undertaken by the authors in the 1500 km² basin of the River Exe in Devon, UK is used to illustrate the considerable spatial variability that may occur within a relatively small area and the complexity of the associated controls.Available evidence concerning the temporal variability of the grain size characteristics of suspended sediment emphasises the diverse patterns of behaviour that may exist and the complexity of the controls involved. In some rivers the sediment may become coarser as flow increases, in others it may become finer, whilst in others it may exhibit a relatively constant grain size composition. Data from the local case study in the Exe basin are again used to highlight the considerable diversity in response to changing discharge that may occur within a relatively small area.Any attempt to understand the dynamics of sediment movement through a river system must also take account of the potential contrast between the ultimate and effective particle size distribution of suspended sediment in response to aggregation. Results from the Exe basin study indicate that even in rivers with relatively low solute concentrations, almost an order of magnitude difference may exist between the median particle size associated with the ultimate and effective grain size distributions.     

The impact of zooplankton size structure on phosphorus cycling in field enclosures

Plastic bag field enclosures (1570 1) were used to investigate the relationship between zooplankton size distributions and the turnover rate of pelagic phosphorus. Water within the enclosures was filtered to simulate either low (200 µm mesh net) or high (80 µm) planktivory. The bags were then spiked with radiolabelled phosphorus and sampled 7 times during the following 24 h period. Zooplankton communities dominated by smaller size classes cycled more phosphorus than those composed of larger species. These experiments reveal that higher trophic level interactions, such as size selective predation, may have a significant impact upon nutrient regeneration rates and, hence, primary production.     

Effects of three herbicides on soil microbial biomass and activity

Three post-emergence herbicides (2,4-D, picloram and glyphosate) were applied to samples of an Alberta agricultural soil at concentrations of 0, 2, 20, and 200 μg g⁻¹. The effects of these chemicals on certain microbial variables was monitored over 27 days. All herbicides caused enhancement of basal respiration but only for 9 days following application, and only for concentrations of 200 μg g⁻¹. Substrate-induced respiration was temporarily depressed by 200 μg g⁻¹ picloram and 2,4-D, and briefly enhanced by 200 μg g⁻¹ glyphosate. It is concluded that because changes in microbial variables only occurred at herbicide concentrations of much higher than that which occurs following field application, the side-effects of these chemicals is probably of little ecological significance.     

Energetic constraints and foraging efficiency

Previous research considers foraging options that differ interms of their gross rate of gain b and rate of energy expenditurec. This research argues that maximizing efficiency b/c willmaximize net energetic gain when there is an upper limit onthe amount of energy that can be assimilated. This analysisdoes not include the expenditure during the time for which theanimal is unable to forage because of this constraint. Whenthis expenditure is included, maximizing efficiency is no longeroptimal. Instead the best feeding option is the one with thehighest value of b/(c – c₁), where c, is the metabolicrate when the animal is not foraging.     

Substance P-Evoked Calcium Mobilization and Ionic Current Activation in the Human Astrocytoma Cell Line U 373 MG: Pharmacological Characterization

Abstract— In the human astrocytoma cell line U 373 MG, application of substance P (SP) leads to a transient increase in cytosolic calcium concentration and to a biphasic current response in voltage-clamped cells. Using these two functional assays we have characterized pharmacologically the SP response in U 373 MG cells. SP and [l -Pro⁹]SP displayed high potencies in both assays with EC₅₀values of 2.5 ± 10^?9M and 1 ± 10^?9M on calcium responses and 110^?9M and 510^?9M on ion current responses, respectively. The high potency of SP and [l -Pro⁹]SP as well as the low potency of [Lys⁵,MeLeu⁹,N-Leu¹⁰]neurokinin A_(4-10) and the inactivity of senktide demonstrate the NK₁-type pharmacology of these responses. Furthermore, the NK₁ antagonists (±)-CP 96,345, its chloro analogue, (±)-cis-3-(2-chlorobenzylamino)-2-benz-hydrylquinuclidine, and RP 67580 were potent antagonists of both SP responses. For the calcium mobilization induced by SP (1 (10^?7M), the IC₅₀ values for the three antagonists were 4 ± 10^?10M, 4 ± 10^?9M, and 9 ± 10^?9M, respectively, whereas on the current response evoked by SP 10^?8M), the IC₅₀ values were 8 ± 10^?9M, 2.4 ± 10^?8M, and 1.2 10^?7M, respectively. Despite differences in the absolute IC₅₀ values obtained with both techniques, the relative potencies of the three antagonists correlate fairly well. The U 373 MG cell line provides a useful model system for studies of the pharmacology of the human NK₁receptor and its transduction mechanisms at the level of second messengers and modulation of ion currents.     

Modifying mosquitoes to suppress disease transmission: Is the long wait over?

For more than 50 years it has been a dream of medical entomologists and public health workers to control diseases like malaria and dengue fever by modifying, through genetics and other methods, the arthropods that transmit them to humans. A brief synopsis of the history of these efforts as applied to mosquitoes is presented; none proved to be effective in reducing disease prevalence. Only in the last few years have novel approaches been developed or proposed that indicate the long wait may be over. Three recent developments are particularly promising: CRISPR-Cas9 driven genetic modification, shifting naturally occurring allele frequencies, and microbe-based modifications. The last is the furthest along in implementation. Dengue fever incidence has been reduced between 40% and 96% in 4 different regions of the world where Wolbachia-infected Aedes aegypti have been established in the field. It is not yet clear how sustainable such control programs will prove to be, but there is good reason for optimism. In light of this, the time is ripe for reinvigorated research on vectors, especially genetics. Vector-borne diseases primarily affect under-developed countries and thus have not received the attention they deserve from wealthier countries with well-developed and funded biomedical research establishments.