Synergy between social and private information increases foraging efficiency in ants

Insect societies integrate many information sources to organize collective activities such as foraging. Many ants use trail pheromones to guide foragers to food sources, but foragers can also use memories to find familiar locations of stable food sources. Route memories are often more accurate than trail pheromones in guiding ants, and are often followed in preference to trail pheromones when the two conflict. Why then does the system expend effort in producing and acquiring seemingly redundant and low-quality information, such as trail pheromones, when route memory is available? Here we show that, in the ant Lasius niger, trail pheromones and route memory act synergistically during foraging; increasing walking speed and straightness by 25 and 30 per cent, respectively, and maintaining trail pheromone deposition, but only when used together. Our results demonstrate a previously undescribed major role of trail pheromones: to complement memory by allowing higher confidence in route memory. This highlights the importance of multiple interacting information sources in the efficient running of complex adaptive systems.     

Considerations on the performance of immunocastrated male pigs

With the ongoing social pressure on surgical castration of pigs, an increase in the population of pigs that are either not castrated or immunocastrated (IC) can be expected. In both cases, their nutrient requirements and performance will differ from surgically castrated pigs and will require changes in their management. Immunocastration is performed by giving two injections of a modified gonadotrophin-releasing hormone component along with an adjuvant, at least 4 weeks apart. This paper describes the reported differences in growth performance and carcass quality of IC male pigs in comparison with boars (BO) and barrows (BA). Theoretically, IC pigs remain physiologically boar until the second vaccination and therefore, growth may be comparable with BO until this second vaccination. From then on, IC male pigs consume more feed than BO and grow faster when fed ad libitum. IC showed a faster growth and better feed conversion ratio than BA. When fed restrictedly, BO grow faster and more efficiently than BA and IC. IC have a lower carcass yield than BA and BO, whereas meat percentage is intermediate.     

Age determination by back length for African savanna elephants: extending age assessment techniques for aerial-based surveys

Determining the age of individuals in a population can lead to a better understanding of population dynamics through age structure analysis and estimation of age-specific fecundity and survival rates. Shoulder height has been used to accurately assign age to free-ranging African savanna elephants. However, back length may provide an analog measurable in aerial-based surveys. We assessed the relationship between back length and age for known-age elephants in Amboseli National Park, Kenya, and Addo Elephant National Park, South Africa. We also compared age- and sex-specific back lengths between these populations and compared adult female back lengths across 11 widely dispersed populations in five African countries. Sex-specific Von Bertalanffy growth curves provided a good fit to the back length data of known-age individuals. Based on back length, accurate ages could be assigned relatively precisely for females up to 23 years of age and males up to 17. The female back length curve allowed more precise age assignment to older females than the curve for shoulder height does, probably because of divergence between the respective growth curves. However, this did not appear to be the case for males, but the sample of known-age males was limited to ≤27 years. Age- and sex-specific back lengths were similar in Amboseli National Park and Addo Elephant National Park. Furthermore, while adult female back lengths in the three Zambian populations were generally shorter than in other populations, back lengths in the remaining eight populations did not differ significantly, in support of claims that growth patterns of African savanna elephants are similar over wide geographic regions. Thus, the growth curves presented here should allow researchers to use aerial-based surveys to assign ages to elephants with greater precision than previously possible and, therefore, to estimate population variables.     

Deletion of a malaria invasion gene reduces death and anemia, in model hosts

Malaria parasites induce complex cellular and clinical phenotypes, including anemia, cerebral malaria and death in a wide range of mammalian hosts. Host genes and parasite 'toxins' have been implicated in malarial disease, but the contribution of parasite genes remains to be fully defined. Here we assess disease in BALB/c mice and Wistar rats infected by the rodent malaria parasite Plasmodium berghei with a gene knock out for merozoite surface protein (MSP) 7. MSP7 is not essential for infection but in P. falciparum, it enhances erythrocyte invasion by 20%. In vivo, as compared to wild type, the P. berghei Δmsp7 mutant is associated with an abrogation of death and a decrease from 3% to 2% in peak, circulating parasitemia. The Δmsp7 mutant is also associated with less anemia and modest increase in the size of follicles in the spleen. Together these data show that deletion of a single parasite invasion ligand modulates blood stage disease, as measured by death and anemia. This work is the first to assess the contribution of a gene present in all plasmodial species in severe disease.     

A viral discovery methodology for clinical biopsy samples utilising massively parallel next generation sequencing

Here we describe a virus discovery protocol for a range of different virus genera, that can be applied to biopsy-sized tissue samples. Our viral enrichment procedure, validated using canine and human liver samples, significantly improves viral read copy number and increases the length of viral contigs that can be generated by de novo assembly. This in turn enables the Illumina next generation sequencing (NGS) platform to be used as an effective tool for viral discovery from tissue samples.     

NADPH oxidase-2 derived ROS dictates murine DC cytokine-mediated cell fate decisions during CD4 T helper-cell commitment

NADPH oxidase-2 (Nox2)/gp91(phox) and p47(phox) deficient mice are prone to hyper-inflammatory responses suggesting a paradoxical role for Nox2-derived reactive oxygen species (ROS) as anti-inflammatory mediators. The molecular basis for this mode of control remains unclear. Here we demonstrate that IFNγ/LPS matured p47(phox-/-)-ROS deficient mouse dendritic cells (DC) secrete more IL-12p70 than similarly treated wild type DC, and in an in vitro co-culture model IFNγ/LPS matured p47(phox-/-) DC bias more ovalbumin-specific CD4(+) T lymphocytes toward a Th1 phenotype than wild type (WT) DC through a ROS-dependent mechanism linking IL-12p70 expression to regulation of p38-MAPK activation. The Nox2-dependent ROS production in DC negatively regulates proinflammatory IL-12 expression in DC by constraining p38-MAPK activity. Increasing endogenous H(2)O(2) attenuates p38-MAPK activity in IFNγ/LPS stimulated WT and p47(phox-/-) DC, which suggests that endogenous Nox 2-derived ROS functions as a secondary messenger in the activated p38-MAPK signaling pathway during IL-12 expression. These findings indicate that ROS, generated endogenously by innate and adaptive immune cells, can function as important secondary messengers that can regulate cytokine production and immune cell cross-talk to control during the inflammatory response.     

Rac1 deletion causes thymic atrophy

The thymic stroma supports T lymphocyte development and consists of an epithelium maintained by thymic epithelial progenitors. The molecular pathways that govern epithelial homeostasis are poorly understood. Here we demonstrate that deletion of Rac1 in Keratin 5/Keratin 14 expressing embryonic and adult thymic epithelial cells leads to loss of the thymic epithelial compartment. Rac1 deletion led to an increase in c-Myc expression and a generalized increase in apoptosis associated with a decrease in thymic epithelial proliferation. Our results suggest Rac1 maintains the epithelial population, and equilibrium between Rac1 and c-Myc may control proliferation, apoptosis and maturation of the thymic epithelial compartment. Understanding thymic epithelial maintenance is a step toward the dual goals of in vitro thymic epithelial cell culture and T cell differentiation, and the clinical repair of thymic damage from graft-versus-host-disease, chemotherapy or irradiation.     

Complete genome sequence of Treponema succinifaciens type strain (6091)

Treponema succinifaciens Cwyk and Canale-Parola 1981 is of interest because this strictly anaerobic, apathogenic member of the genus Treponema oxidizes carbohydrates and couples the Embden-Meyerhof pathway via activity of a pyruvate-formate lyase to the production of acetyl-coenzyme A and formate. This feature separates this species from most other anaerobic spirochetes. The genome of T. succinifaciens 6091(T) is only the second completed and published type strain genome from the genus Treponema in the family Spirochaetaceae. The 2,897,425 bp long genome with one plasmid harbors 2,723 protein-coding and 63 RNA genes and is a part of the Genomic Encyclopedia of Bacteria and Archaea project.     

Complete genome sequence of Tolumonas auensis type strain (TA 4)

Tolumonas auensis Fischer-Romero et al. 1996 is currently the only validly named species of the genus Tolumonas in the family Aeromonadaceae. The strain is of interest because of its ability to produce toluene from phenylalanine and other phenyl precursors, as well as phenol from tyrosine. This is of interest because toluene is normally considered to be a tracer of anthropogenic pollution in lakes, but T. auensis represents a biogenic source of toluene. Other than Aeromonas hydrophila subsp. hydrophila, T. auensis strain TA 4(T) is the only other member in the family Aeromonadaceae with a completely sequenced type-strain genome. The 3,471,292 bp chromosome with a total of 3,288 protein-coding and 116 RNA genes was sequenced as part of the DOE Joint Genome Institute Program JBEI 2008.     

Complete genome sequence of the thermophilic sulfur-reducer Desulfurobacterium thermolithotrophum type strain (BSA(T)) from a deep-sea hydrothermal vent

Desulfurobacterium thermolithotrophum L'Haridon et al. 1998 is the type species of the genus Desulfurobacterium which belongs to the family Desulfurobacteriaceae. The species is of interest because it represents the first thermophilic bacterium that can act as a primary producer in the temperature range of 45-75 °C (optimum 70°C) and is incapable of growing under microaerophilic conditions. Strain BSA(T) preferentially synthesizes high-melting-point fatty acids (C(18) and C(20)) which is hypothesized to be a strategy to ensure the functionality of the membrane at high growth temperatures. This is the second completed genome sequence of a member of the family Desulfurobacteriaceae and the first sequence from the genus Desulfurobacterium. The 1,541,968 bp long genome harbors 1,543 protein-coding and 51 RNA genes and is a part of the Genomic Encyclopedia of Bacteria and Archaea project.