Seawater carbonate chemistry, photosynthesis and calcification rate during experiments with coral Acropora muricata, 2011

The effect of decreasing aragonite saturation state (Omega Arag) of seawater (elevated pCO2) on calcification rates of Acropora muricata was studied using nubbins prepared from parent colonies located at two sites of La Saline reef (La Réunion Island, western Indian Ocean): a back-reef site (BR) affected by nutrient-enriched groundwater discharge (mainly nitrate), and a reef flat site (RF) with low terrigenous inputs. Protein and chlorophyll a content of the nubbins, as well as zooxanthellae abundance, were lower at RF than BR. Nubbins were incubated at ~27°C over 2 h under sunlight, in filtered seawater manipulated to get differing initial pCO2 (1,440-340 µatm), Omega Arag (1.4-4.0), and dissolved inorganic carbon (DIC) concentrations (2,100-1,850 µmol kg-1). Increasing DIC concentrations at constant total alkalinity (AT) resulted in a decrease in Omega Arag and an increase in pCO2. AT at the beginning of the incubations was kept at a natural level of 2,193 +- 6 µmol kg-1 (mean +- SD). Net photosynthesis (NP) and calcification were calculated from changes in pH and AT during the incubations. Calcification decrease in response to doubling pCO2 relative to preindustrial level was 22% for RF nubbins. When normalized to surface area of the nubbins, (1) NP and calcification were higher at BR than RF, (2) NP increased in high pCO2 treatments at BR compared to low pCO2 treatments, and (3) calcification was not related to Omega Arag at BR. When normalized to NP, calcification was linearly related to Omega Arag at both sites, and the slopes of the relationships were not significantly different. The increase in NP at BR in the high pCO2 treatments may have increased calcification and thus masked the negative effect of low Omega Arag on calcification. Removing the effect of NP variations at BR showed that calcification declined in a similar manner with decreased Omega Arag (increased pCO2) whatever the nutrient loading.

Seawater carbonate chemistry, Mg/Ca, Sr/Ca, oxygen production and calcification rate during experiments with coral Pocillopora damicornis, 2011

The Sr/Ca of aragonitic coral skeletons is a commonly used palaeothermometer. However skeletal Sr/Ca is typically dominated by weekly-monthly oscillations which do not reflect temperature or seawater composition and the origins of which are currently unknown. To test the impact of transcellular Ca2+ transport processes on skeletal Sr/Ca, colonies of the branching coral, Pocillopora damicornis, were cultured in the presence of inhibitors of Ca-ATPase (ruthenium red) and Ca channels (verapamil hydrochloride). The photosynthesis, respiration and calcification rates of the colonies were monitored throughout the experiment. The skeleton deposited in the presence of the inhibitors was identified (by 42Ca spike) and analysed for Sr/Ca and Mg/Ca by secondary ion mass spectrometry. The Sr/Ca of the aragonite deposited in the presence of either of the inhibitors was not significantly different from that of the solvent (dimethyl sulfoxide) control, although the coral calcification rate was reduced by up to 66% and 73% in the ruthenium red and verapamil treatments, respectively. The typical precision (95% confidence limits) of mean Sr/Ca determinations within any treatment was <±1% and differences in skeletal Sr/Ca between treatments were correspondingly small. Either Ca-ATPase and Ca channels transport Sr2+ and Ca2+ in virtually the same ratio in which they are present in seawater or transcellular processes contribute little Ca2+ to the skeleton and most Ca is derived from seawater transported directly to the calcification site. Variations in the activities of Ca-ATPase and Ca-channels are not responsible for the weekly-monthly Sr/Ca oscillations observed in skeletal chronologies, assuming that the specificities of Ca transcellular transport processes are similar between coral genera.

Effets directs et indirects de la prédation sur les lemmings dans l’Arctique canadien.

Les populations caractérisées par des fluctuations cycliques ont fasciné et continuent de générer un grand intérêt chez la communauté scientifique en raison de la complexité des facteurs de régulation qui en sont responsables. Plusieurs hypothèses ont été proposées pour expliquer ces fluctuations cycliques mais aucun consensus n’a encore été atteint malgré près de 100 ans de recherche. La disponibilité de la nourriture et les effets sociaux (e.g. interactions compétitives) ont été proposés comme facteurs responsables de cycles de certaines espèces. Toutefois, la prédation est probablement le facteur le plus susceptible de causer des fluctuations cycliques chez les populations fauniques en raison de son effet dépendant de la densité avec délai. Un tandem circulaire de raréfaction et densification des prédateurs et des proies par des effets directs (i.e. mortalités) seraient à l’origine des cycles d’abondance. De plus, de récentes études montrent que les effets indirects (comme le stress) de la prédation pourraient être aussi importants que les effets directs pour générer les fluctuations cycliques. Cette thèse vise à identifier les effets directs et indirects de la prédation qui affectent la population de lemmings bruns de l’Île Bylot, Nunavut, caractérisée par des cycles d’abondance de 3-4 ans. Pour ce faire, nous avons d’abord comparé la plausibilité de l’hypothèse de la limitation par nourriture vis-à-vis l’hypothèse de la prédation en déterminant la chronologie saisonnière des cycles des lemmings. Ensuite, nous avons construit en 2012-2013 une clôture de 9 ha coiffée d’un filet anti-prédateur aviaire dans lequel nous avons piégé les lemmings de 2013 à 2015. Une deuxième grille de trappage sans clôture a été utilisée à des fins de comparaisons. Ces deux grilles étaient actives dès 2008, ce qui nous a permis d’avoir un contrôle pré-expérimental pour les données démographiques (effets directs). En 2014 et 2015, nous avons récolté les fèces des lemmings dans les deux grilles de trappage afin de quantifier les métabolites d’hormones de stress. Une validation de la mesure des métabolites fécales des glucocorticoïdes (i.e. hormones de stress) a été menée afin de mesurer le stress des lemmings de façon non-invasive. Les résultats sont clairs : (1) le déclin des lemmings se produit à la fin de l’été alors que les prédateurs sont au plus fort de leur abondance et pas à la fin de l’hiver, supportant ainsi l’hypothèse de la limitation par la prédation. Nos résultats suggèrent aussi (2) que les lemmings à l’intérieur de la clôture avaient une survie plus élevée qu’à l’extérieur, favorisant ainsi une croissance plus forte de la population. Ensuite, (3) les lemmings ont montré des niveaux de stress plus faibles sans prédation sans toutefois que cela ait un impact sur leur reproduction. À la lumière des résultats de cette thèse et en les comparant avec deux autres études ayant aussi réduit expérimentalement l’abondance des prédateurs dans la toundra arctique, nous pouvons conclure que la prédation est la force trophique dominante de régulation de l’abondance des lemmings. Cette étude montre également que le stress induit par la prédation est insuffisant pour avoir un impact sur la dynamique des lemmings en été, soit pendant la saison où la prédation est maximale. Il est possible que cette absence d’effet soit une réponse adaptative des lemmings pour maintenir une reproduction élevée face à une prédation élevée, et ainsi maximiser leur aptitude phénotypique.

Effect of ambient levels of ozone on photosynthetic components and radical scavenging system in leaves of African cowpea varieties

Tropospheric ozone (O3), a main component of photochemical oxidants, adversely affects not only human health but also vegetation. To clarify the long-term effects of ambient levels of tropospheric ozone (O3) on photosynthetic components and radical scavenging system in the leaves of cowpea ( Vigna unguiculata L.), two African varieties, Blackeye and Asontem, were grown in open-top chambers and exposed to filtered air (FA), non-filtered air (NF) or non-filtered air with additional O3 of approximately 50 nl l-1. Ambient levels of O3 significantly reduced chlorophyll concentration, quantum yield and activity of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco), thus contributing to the reduction in net photosynthetic rate at the reproductive growth stage of both varieties; with no significant variety difference in the sensitivity to O3. The O3-induced significant reduction in catalase activity was observed in Blackeye at vegetative and reproductive growth stages; and in Asontem at reproductive growth stage. On the other hand, exposure to O3 significantly increased ascorbate peroxidase activity in Blackeye at reproductive stage and did not significantly affect that in Blackeye at vegetative growth stage and that in Asontem at both growth stages. At reproductive growth stage, activities of monodehydroascorbate reductase and glutathione reductase were significantly increased by the exposure to O3 in both varieties. The results obtained in this study suggest that, although ascorbate peroxidase, monodehydroascorbate reductase and glutathione reductase played important roles in scavenging O3-induced reactive oxygen species in the leaves, radical scavenging ability of these enzymes is not sufficient to avoid detrimental effects of ambient levels of O3 on photosynthesis in both African cowpea varieties.

Genome analysis reveals insights into physiology and longevity of the Brandt’s bat Myotis brandtii

Bats account for one-fifth of mammalian species, are the only mammals with powered flight, and are among the few animals that echolocate. The insect-eating Brandt’s bat (Myotis brandtii) is the longest-lived bat species known to date (lifespan exceeds 40 years) and, at 4–8 g adult body weight, is the most extreme mammal with regard to disparity between body mass and longevity. Here we report sequencing and analysis of the Brandt’s bat genome and transcriptome, which suggest adaptations consistent with echolocation and hibernation, as well as altered metabolism, reproduction and visual function. Unique sequence changes in growth hormone and insulin-like growth factor 1 receptors are also observed. The data suggest that an altered growth hormone/insulin-like growth factor 1 axis, which may be common to other long-lived bat species, together with adaptations such as hibernation and low reproductive rate, contribute to the exceptional lifespan of the Brandt’s bat.

UNICEF, Jakarta, Indonesia : Review of Satap Schools

A. Background and context 1. Education, particularly basic education (grades1-9), has been considered critical to promoting national economic growth and social well being1. Three factors that con-tribute to the above are: (i) Education increases human capital inherent in a labor force and thus increases productivity. It also increases capacity for working with others and builds community consensus to support national development. (ii) Education can in-crease the innovative capacity of a community to support social and economic growth—use of new technologies, products and services to promote growth and wellbeing. (iii) Education can facilitate knowledge transfer needed to understand the social and eco-nomic innovations and new processes, practices and values. Cognizant of the above benefits of education, the Millennium Development Goals (MDG) and the Education for All (EFA) declarations advocating universal basic education were formulated and ratified by UN member countries. 2. Achieving universal primary education (grade 6) may not be sufficient to maxim-ize the above noted socio-economic and cultural benefits. There is general consensus that basic literacy and numeracy up to grade 9 are essential foundational blocks for any good education system to support national development. Basic Education provides an educational achievement threshold that ensures the learning is retained. To achieve this, the donor partner led interventions and the UN declarations such as the MDG goals have sought universal access to basic education (grades 1-9). As many countries progress towards achieving the universal access targets, recent research evidence suggests that we need more than just access to basic education to impact on the na-tional development. Measuring basic education completion cycle, gross enrolment rate (GER) and participation rate etc., has to now include a focus on quality and relevance of the education2. 3. While the above research finding is generally accepted by the Government of In-donesia (GoI), unlike many other developing countries, Indonesia is geographically and linguistically complex and has the fourth largest education sector in the world. It has over 3000 islands, 17,000 ethnic groups and it takes as long as 7 hours to travel from east to west of the country and has multiple time differences. The education system has six years of primary education (grades 1-6), 3 years of junior secondary education (grades 7-9) and three years of senior secondary education (grades 10-12). Therefore, applying the findings of the above cited research in a country like Indonesia is a chal-lenge. Nevertheless, since the adoption of the National Education Law (2003)3 the GoI has made significant progress in improving access to and quality of basic education (grades 1-9). The 2011/12 national education statistics show the primary education (grades 1-6) completion rate was 99.3%, the net enrolment rate (NER) was 95.4% and the GER was 115.4%. This is a significant achievement considering the complexities faced within Indonesia. This increase in the primary education sub-sector, however, has not flowed onto the Junior Secondary School (JSS) education. The transition from pri-mary to JSS is still short of the GoI targets. In 2012, there were 146,826 primary schools feeding into 33,668 junior secondary schools. The transition rate from primary to secondary in 2011/12 was 78%. When considering district or sub-district level data the transition in poor districts could be less than the aggregated national rate. Poverty and lack of parents’ education, confounded by opportunity cost, are major obstacles to transitioning to JSS4. 4. Table 1 presents a summary of GoI initiatives to accelerate the transition to JSS. GoI, with assistance from the donor community, has built 2465 new regular JSS, mak-ing the total number of regular JSS 33,668. In addition, 57,825 new classrooms have been added to existing regular JSS. Also, in rural and remote areas 4136 Satu-Atap5 (SATAP) schools were built to increase access to JSS. These SATAP schools are the focus of this study as they provide education opportunities to the most marginalized, ru-ral, remote children who otherwise would not have access to JSS and consequently not complete basic education.

Adaptability of Damara, Dorper and Traditional Meat Sheep Breeds in Semi-Arid Queensland

Reproductive rate is a major contributing factor to the profitability of a sheep meat enterprise. Low reproduction rate is a feature of sheep husbandry in semi-arid Queensland. High ambient temperatures are implicated in poor fertility (Moule 1970) where variation in response can be due to breed and to animals within a breed (Hopkins and Stephenson 1978). Breeds recently imported from South Africa were selected in arid environments and may be better adapted to pastoral conditions of northern Australia than traditional breeds. Animal production for a consuming world : proceedings of 9th Congress of the Asian-Australasian Association of Animal Production Societies [AAAP] and 23rd Biennial Conference of the Australian Society of Animal Production [ASAP] and 17th Annual Symposium of the University of Sydney, Dairy Research Foundation, [DRF]. 2-7 July 2000, Sydney, Australia. This study will investigate (a) the thermoregulatory ability of Damara, Dorper, Poll Dorset, Rambouillet, South African Meat Merino and Queensland medium wool Merino rams prior to joinings in the autumn and spring of 1999, 2000 and 2001 and (b) the association between thermoregulatory parameters (rectal temperature and respiration rate) and ewe fertility. Results for the initial autumn joining are reported in this paper.

Sedimentary zooplankton remains as indicators of lake ecological quality and trophic structure

To protect and restore lake ecosystems under threats posed by the increasing human population, information on their ecological quality is needed. Lake sediments provide a data rich archive that allows identification of various biological components present prior to anthropogenic alterations as well as a constant record of changes. By providing a longer dimension of time than any ongoing monitoring programme, palaeolimnological methods can help in understanding natural variability and long-term ecological changes in lakes. As zooplankton have a central role in the lake food web, their remains can potentially provide versatile information on past trophic structure. However, various taphonomic processes operating in the lakes still raise questions concerning how subfossil assemblages reflect living communities. This thesis work aimed at improving the use of sedimentary zooplankton remains in the reconstruction of past zooplankton communities and the trophic structure in lakes. To quantify interspecific differences in the accumulation of remains, the subfossils of nine pelagic zooplankton taxa in annually laminated sediments were compared with monitoring results for live zooplankton in Lake Vesijärvi. This lake has a known history of eutrophication and recovery, which resulted from reduced external loading and effective fishing of plankti-benthivorous fish. The response of zooplankton assemblages to these known changes was resolved using annually laminated sediments. The generality of the responses observed in Lake Vesijärvi were further tested with a set of 31 lakes in Southern Finland, relating subfossils in surface sediments to contemporary water quality and fish density, as well as to lake morphometry. The results demonstrated differential preservation and retention of cladoceran species in the sediment. Daphnia, Diaphanosoma and Ceriodaphnia were clearly underrepresented in the sediment samples in comparison to well-preserved Bosmina species, Chydorus, Limnosida and Leptodora. For well-preserved species, the annual net accumulation rate was similar to or above the expected values, reflecting effective sediment focusing and accumulation in the deepest part of the lake. The decreased fish density and improved water quality led to subtle changes in zooplankton community composition. The abundance of Diaphanosoma and Limnosida increased after the reduction in fish density, while Ceriodaphnia and rotifers decreased. The most sensitive indicator of fish density was the mean size of Daphnia ephippia and Bosmina (E.) crassicornis ephippia and carapaces. The concentration of plant-associated species increased, reflecting expanding littoral vegetation along with increasing transparency. Several of the patterns observed in Lake Vesijärvi could also be found within the set of 31 lakes. According to this thesis work, the most useful cladoceran-based indices for nutrient status and planktivorous fish density in Finnish lakes were the relative abundances of certain pelagic taxa, and the mean size of Bosmina spp. carapaces, especially those of Bosmina (E.) cf. coregoni. The abundance of plant-associated species reflected the potential area for aquatic plants. Lake morphometry and sediment organic content, however, explained a relatively high proportion of the variance in the species data, and more studies are needed to quantify lake-specific differences in the accumulation and preservation of remains. Commonly occurring multicollinearity between environmental variables obstructs the cladoceran-based reconstruction of single environmental variables. As taphonomic factors and several direct and indirect structuring forces in lake ecosystems simultaneously affect zooplankton, the subfossil assemblages should be studied in a holistic way before making final conclusions about the trophic structure and the change in lake ecological quality.

The energy balance in the Ramdas layer

On calm clear nights, air at a height of a few decimetres above bare soil can be cooler than the surface by several degrees in what we shall call the Ramdas layer (Ramdas and Atmanathan, 1932). The authors have recently offered a logical explanation for such a lifted temperature minimum, together with a detailed numerical model. In this paper, we provide physical insight into the phenomenon by a detailed discussion of the energy budget in four typical cases, including one with a lifted minimum. It is shown that the net cooling rate near ground is the small difference between two dominant terms, representing respectively radiative upflux from the ground and from the air layers just above ground. The delicate energy balance that leads to the lifted minimum is upset by turbulent transport, by surface emissivity approaching unity, or by high ground cooling rates. The rapid variation of the flux emissivity of humid air is shown to dominate radiative transport near the ground.

Thermal instability and the feedback regulation of hot haloes in clusters, groups and galaxies

We present global multidimensional numerical simulations of the plasma that pervades the dark matter haloes of clusters, groups and massive galaxies (the intracluster medium; ICM). Observations of clusters and groups imply that such haloes are roughly in global thermal equilibrium, with heating balancing cooling when averaged over sufficiently long time- and length-scales; the ICM is, however, very likely to be locally thermally unstable. Using simple observationally motivated heating prescriptions, we show that local thermal instability (TI) can produce a multiphase medium with similar to 104 K cold filaments condensing out of the hot ICM only when the ratio of the TI time-scale in the hot plasma (tTI) to the free-fall time-scale (tff) satisfies tTI/tff? 10. This criterion quantitatively explains why cold gas and star formation are preferentially observed in low-entropy clusters and groups. In addition, the interplay among heating, cooling and TI reduces the net cooling rate and the mass accretion rate at small radii by factors of similar to 100 relative to cooling-flow models. This dramatic reduction is in line with observations. The feedback efficiency required to prevent a cooling flow is similar to 10-3 for clusters and decreases for lower mass haloes; supernova heating may be energetically sufficient to balance cooling in galactic haloes. We further argue that the ICM self-adjusts so that tTI/tff? 10 at all radii. When this criterion is not satisfied, cold filaments condense out of the hot phase and reduce the density of the ICM. These cold filaments can power the black hole and/or stellar feedback required for global thermal balance, which drives tTI/tff? 10. In comparison to clusters, groups have central cores with lower densities and larger radii. This can account for the deviations from self-similarity in the X-ray luminositytemperature () relation. The high-velocity clouds observed in the Galactic halo can be due to local TI producing multiphase gas close to the virial radius if the density of the hot plasma in the Galactic halo is >rsim 10-5 cm-3 at large radii.

Vapor-liquid-solid growth of Si nanowires: A kinetic analysis

A steady state kinetic model has been developed for the vapor-liquid-solid growth of Si whiskers or nanowires from liquid catalyst droplets. The steady state is defined as one in which the net injection rate of Si into the droplet is equal to the ejection rate due to wire growth. Expressions that represent specific mechanisms of injection and ejection of Si atoms from the liquid catalyst droplet have been used and their relative importance has been discussed. The analysis shows that evaporation and reverse reaction rates need to be invoked, apart from just surface cracking of the precursor, in order to make the growth rate radius dependent. When these pathways can be neglected, the growth rate become radius independent and can be used to determine the activation energies for the rate limiting step of heterogeneous precursor decomposition. The ejection rates depend on the mechanism of wire growth at the liquid-solid interface or the liquid-solid-vapor triple phase boundary. It is shown that when wire growth is by nucleation and motion of ledges, a radius dependence of growth rate does not just come from the Gibbs-Thompson effect on supersaturation in the liquid, but also from the dependence of the actual area or length available for nucleation. Growth rates have been calculated using the framework of equations developed and compared with experimental results. The agreement in trends is found to be excellent. The same framework of equations has also been used to account for the diverse pressure and temperature dependence of growth rates reported in the literature. © 2012 American Institute of Physics.

Enhanced virulence of Salmonella enterica serovar typhimurium after passage through mice.

The interaction between Salmonella enterica and the host immune system is complex. The outcome of an infection is the result of a balance between the in vivo environment where the bacteria survive and grow and the regulation of fitness genes at a level sufficient for the bacteria to retain their characteristic rate of growth in a given host. Using bacteriological counts from tissue homogenates and fluorescence microscopy to determine the spread, localization, and distribution of S. enterica in the tissues, we show that, during a systemic infection, S. enterica adapts to the in vivo environment. The adaptation becomes a measurable phenotype when bacteria that have resided in a donor animal are introduced into a recipient naïve animal. This adaptation does not confer increased resistance to early host killing mechanisms but can be detected as an enhancement in the bacterial net growth rate later in the infection. The enhanced growth rate is lost upon a single passage in vitro, and it is therefore transient and not due to selection of mutants. The adapted bacteria on average reach higher intracellular numbers in individual infected cells and therefore have patterns of organ spread different from those of nonadapted bacteria. These experiments help in developing an understanding of the influence of passage in a host on the fitness and virulence of S. enterica.

羊草群落生产力动态及其对全球变化的反应

以中国东北森林 - 草原样带(NECT)上的松嫩平原羊草草甸草原为研究对象，从影响羊草叶片光合作用的机理出发，基于羊草片光合生理生态特性、羊草群落小气候梯度以及羊草群落生物量等的野外动态观测，分析了羊草叶片的光合生理特性动态特征，建立了羊草叶片的光合作用机理模型，通过尺度化，发展了基于叶片生理特性的羊草群落生产力动态模型;并结合著名的草地生态系统模型—CENTURY模型探讨了人类活动和气候变化对羊草草地的影响。主要结果如下： (1) 晴朗天气下羊草叶片气孔导度和净光合速率日变化均呈双峰型曲线。 (2) 影响羊草叶片气孔导度的主要环境因子是光合有效辐射、叶片与空气间的水汽压亏损以及空气温度。 (3) 影响羊草叶片净光合速率的主要因子是胞间CO2浓度、气孔导度、空气CO2浓度及蒸腾速率。 (4) 对当前2类代表性气孔导度模型的验证表明，基于Jarvis模型所改建的气孔导度模型比依据Leuning改进的Ball模型所建立的气孔导度模型具有更好的模拟效果，并据此建立了适于羊草叶片的气孔导度模型： gs = PAR (-2.01Ta2 + 147.74Ta - 2321.11)/((444.62 + PAR) (-538.042 + VPD)) (5) 结合能量平衡方程和光合作用生化模型，建立了能够模拟羊草叶片CO2、水汽和热量交换的羊草叶片光合作用耦合模型。该模型有能力预测复杂的环境变化对羊草叶片净光合作用和气孔导度的影响。 (6) 通过尺度化(采用多层模式模拟冠层导度，大叶模式模拟光合作用)，建立了羊草群落光合作用模型，结合植物群落的呼吸模型，估算了羊草群落的净第一性生产力，并与实测值及CENTURY模型模拟值进行了比较，结果表明，基于叶片光合机理的群落生产力模型较CENTURY模型能更好地反映羊草群落的生产力动态。 (7) 基于CENTURY模型对人类活动、气候变化对羊草草原可能影响的模拟表明，人类活动(割草和放牧)和气候变化都会明显影响羊草草原，但人类活动产生的影响更为显著，尤其是重牧将造成羊草草原土壤有机碳和群落生物量显著降低。因此，制定合理的放牧和割草措施对于维持草场的可持续发展具有重要意义。

The feasibility of milkfish (Chanos chanos) aquaculture in Solomon Islands

Fish is crucial to food and nutrition security in Solomon Islands, and demand is expected to increase due to a growing population. However, it is projected that current capture fisheries production will not meet this growing demand. Aquaculture has the potential to mitigate the capture fishery shortfall, and the Government of Solomon Islands is prioritizing aquaculture as a solution to meet future food and income needs. Aquaculture in Solomon Islands is still in early development. Mozambique tilapia (Oreochromis mossambicus) is farmed for household consumption, but its prolific reproductive rate and resulting slow growth limit its potential as a commercial aquaculture species. More productive fish species that are not indigenous to Solomon Islands but are successfully farmed overseas could be introduced; however, such a decision needs to take into account the potential ecological or social impacts. For land-based pond aquaculture, the only indigenous species that has been farmed extensively elsewhere is milkfish (Chanos chanos). This report presents a feasibility assessment for milkfish farming in Solomon Islands. It synthesizes the current knowledge about milkfish farming and presents results of a 4-year study on the potential for milkfish aquaculture in Solomon Islands.

Lymph Node Colonization Dynamics after Oral Salmonella Typhimurium Infection in Mice

An understanding of how pathogens colonize their hosts is crucial for the rational design of vaccines or therapy. While the molecular factors facilitating the invasion and systemic infection by pathogens are a central focus of research in microbiology, the population biological aspects of colonization are still poorly understood. Here, we investigated the early colonization dynamics of Salmonella enterica subspecies 1 serovar Typhimurium (S. Tm) in the streptomycin mouse model for diarrhea. We focused on the first step on the way to systemic infection - the colonization of the cecal lymph node (cLN) from the gut - and studied roles of inflammation, dendritic cells and innate immune effectors in the colonization process. To this end, we inoculated mice with mixtures of seven wild type isogenic tagged strains (WITS) of S. Tm. The experimental data were analyzed with a newly developed mathematical model describing the stochastic immigration, replication and clearance of bacteria in the cLN. We estimated that in the beginning of infection only 300 bacterial cells arrive in the cLN per day. We further found that inflammation decreases the net replication rate in the cLN by 23%. In ccr7-/- mice, in which dendritic cell movement is impaired, the bacterial migration rate was reduced 10-fold. In contrast, cybb-/- mice that cannot generate toxic reactive oxygen species displayed a 4-fold higher migration rate from gut to cLN than wild type mice. Thus, combining infections with mixed inocula of barcoded strains and mathematical analysis represents a powerful method for disentangling immigration into the cLN from replication in this compartment. The estimated parameters provide an important baseline to assess and predict the efficacy of interventions. © 2013 Kaiser et al.