Measuring mast seeding behavior: relationships among population variation,individual variation and synchrony

Mast seeding, or masting, is the variable production of flowers, seeds, or fruit across years more or less synchronously by individuals within a population. A critical issue is the extent to which temporal variation in seed production over a collection of individuals can be viewed as arising from a combination of individual variation and synchrony among individuals. Studies of masting typically quantify such variation in terms of the coefficient of variation (CV). In this paper we examine mathematically how the population CV relates to the mean individual CV and synchrony, concluding that the relationship is a complex one which cannot isolate an overall measure of synchrony, and involves additional factors, principally the number of plants sampled and the mean productivity per plant. Our development suggests some simple approximate relationships of population CV to individual variability, synchrony and the number of individuals. These were found to fit quite well when applied to data from 59 studies which included seed production at the individual level.     

Plant snoRNA database

The Plant snoRNA database (http://www.scri.sari.ac.uk/plant_snoRNA/) provides information on small nucleolar RNAs from Arabidopsis and eighteen other plant species. Information includes sequences, expression data, methylation and pseudouridylation target modification sites, initial gene organization (polycistronic, single gene and intronic) and the number of gene variants. The Arabidopsis information is divided into box C/D and box H/ACA snoRNAs, and within each of these groups, by target sites in rRNA, snRNA or unknown. Alignments of orthologous genes and gene variants from different plant species are available for many snoRNA genes. Plant snoRNA genes have been given a standard nomenclature, designed wherever possible, to provide a consistent identity with yeast and human orthologues.     

PCR analysis of the distribution of unicellular cyanobacterial diazotrophs in the Arabian Sea

An oligonucleotide primer, NITRO821R, targeting the 16S rRNA gene of unicellular cyanobacterial N2 fixers was developed based on newly derived sequences from Crocosphaera sp. strain WH 8501 and Cyanothece sp. strains WH 8902 and WH 8904 as well as several previously described sequences of Cyanothece sp. and sequences of intracellular cyanobacterial symbionts of the marine diatom Climacodium frauenfeldianum. This oligonucleotide is specific for the targeted organisms, which represent a well-defined phylogenetic lineage, and can detect as few as 50 cells in a standard PCR when it is used as a reverse primer together with the cyanobacterium- and plastid-specific forward primer CYA359F (U. Nubel, F. Garcia-Pichel, and G. Muyzer, Appl. Environ. Microbiol. 63:3327-3332, 1997). Use of this primer pair in the PCR allowed analysis of the distribution of marine unicellular cyanobacterial diazotrophs along a transect following the 67 degrees E meridian from Victoria, Seychelles, to Muscat, Oman (0.5 degrees S to 26 degrees N) in the Arabian Sea. These organisms were found to be preferentially located in warm (>29 degrees C) oligotrophic subsurface waters between 0 and 7 degrees N, but they were also found at a station north of Oman at 26 degrees N, 56 degrees 35'E, where similar water column conditions prevailed. Slightly cooler oligotrophic waters (<29 degrees C) did not contain these organisms or the numbers were considerably reduced, suggesting that temperature is a key factor in dictating the abundance of this unicellular cyanobacterial diazotroph lineage in marine environments.     

Anti-IL-13 monoclonal antibody inhibits airway hyperresponsiveness, inflammation and airway remodeling

Asthma is a chronic inflammatory disease characterized by reversible bronchial constriction, pulmonary inflammation and airway remodeling. Current standard therapies for asthma provide symptomatic control but fail to target the underlying disease pathology. Furthermore, no therapeutic agent is effective in preventing airway remodeling. Interleukin 13 (IL-13) is a pleiotropic cytokine produced mainly by T cells. A substantial amount of evidence suggests that IL-13 plays a critical role in the pathogenesis of asthma. Therefore, a neutralizing anti-IL-13 monoclonal antibody could provide therapeutic benefits to asthmatic patients. To test the concept we have generated a neutralizing rat anti-mouse IL-13 monoclonal antibody, and evaluated its effects in a chronic mouse model of asthma. Chronic asthma-like response was induced in ovalbumin (OVA) sensitized mice by repeated intranasal OVA challenges. After weeks of challenge, mice developed airway hyperresponsiveness (AHR) to methacholine stimulation, severe airway inflammation, hyper mucus production, and subepithelial fibrosis. When given at the time of each intranasal OVA challenge, anti-IL-13 antibody significantly suppressed AHR, eosinophil infiltration, proinflammatory cytokine/chemokine production, serum IgE, and most interestingly, airway remodeling. Taken together, these results strongly suggest that a neutralizing anti-human IL-13 monoclonal antibody could be an effective therapeutic agent for asthma.     

Effects of fluoride on growth, reproduction and survival in Daphnia magna

The effects of waterborne fluoride (NaF) on growth, reproduction and survival in Daphnia magna were studied from subnormal to toxic concentrations in hard reconstituted water. The 24- and 48-hr EC50S for immobilization were 205 and 98 mg F (fluoride) 1(-1). Median survival times for fed and unfed Daphnia were reduced at concentrations of F above 8.9 and 10 mg F1(-1), respectively. Growth, determined as body length after 7 and 21 days, was partially inhibited at all concentrations above 3.7 mg F1(-1). Parthenogenetic reproduction was stimulated by all concentrations (dilution factor 0.5) between 0.45 X 10(-3) mg F1(-1) and 3.7 mg F1(-1) and inhibited by all concentrations above 3.7 mg F1(-1), compared to the control with no waterborne fluoride. The highest concentration with a reproduction (number of live progeny/live female) equivalent to the control after 21 days was 4.4 mg F1(-1). However, a progressive decline in reproduction between 14 and 21 days indicates a slight long-term inhibition above 0.58 mg F1(-1). The "safe" concentration equivalent to the geometric mean of NOEC or MATC for D. magna in hard water is 4.4 mg F1(-1), derived as ZEP, the Zero Equivalent Point, for reproduction after 21 days.     

Sediment toxicity in the Kattegat and Skagerrak

Sediments were sampled from 62 sites in the Kattegat and Skagerrak, which are located between the Baltic and the North Sea in the Western Atlantic, during autumn 1989 and spring 1990. From each site 5 to 6 samples were taken wit ha box-corer. After mixing to composite samples on board, transport and storage (at 4 °C for 2 to 4 weeks), the samples were tested for toxicity to Daphnia magna and Nitocra spinipes. Immobility in Daphnia after exposure to 16 percent sediment (wet wt) in reconstituted standardized water (ISO, 1982) ranged from 0 to 88 percent after 24 h and from 3 to 95 percent after 48 h. For Nitocra the toxicity, determined as the 96-h LC50 (% wet wt) at 7 salinity, ranged from > > 32 percent (nontoxic) to 1.8 percent (most toxic). All exposures were made in duplicates and the effects obtained in the duplicates with the same sediment were correlated to each other. However, sediment toxicity to Daphnia and Nitocra was not. The test with Nitocra, which was made at several concentrations of sediment, was considered to give the most reliable picture of sediment toxicity in the Kattegat and Skagerrak. This ambient toxicity assessment identified three areas with toxic sediment, (1) the Göta älv estuary (outside the city of Göteborg) and its surroundings, (2) the Bay of Laholm in southern Kattegat, which is an area with periodic oxygen depletion and where repeated mussel kills have occurred during the last decade, and (3) an area in the open Skagerrak northwest of Skagen (the tip of the Jutland peninsula). Sediments, which had been stored at 4 °C, were tested again after 6 to 13 mos with the Nitocra test. Stored sediment toxicity was poorly correlated with fresh sediment toxicity. The average detoxification during storage was 5 times, but the range was 3 orders of magnitude, from 17 times more toxic to 73 times less toxic. The reasons for the observed areal and storage differences in sediment toxicity are so far not understood.     

Seasonal histochemical changes in the cambium ofTectona grandis L. f. andgmelina arborea roxb

Starch, lipids and proteins are localized histochemically in fusiform and ray initials ofTectona grandis andGmelina arborea during the periodicity of cambium in the year 1978. The histochemical variations are correlated with the seasonal activity and dormancy of the cambium and phenology. Starch grains appear in the cambial cells with the development of young leaves after defoliation. Lipid and protein bodies are significantly high in dormant cambial cells and scarce in active ones.     

A map of the subcellular distribution of phosphoinositides in the erythrocytic cycle of the malaria parasite Plasmodium falciparum

Despite representing a small percentage of the cellular lipids of eukaryotic cells, phosphoinositides (PIPs) are critical in various processes such as intracellular trafficking and signal transduction. Central to their various functions is the differential distribution of PIP species to specific membrane compartments through the actions of kinases, phosphatases and lipases. Despite their importance in the malaria parasite lifecycle, the subcellular distribution of most PIP species in this organism is still unknown. We here localise several species of PIPs throughout the erythrocytic cycle of Plasmodium falciparum. We show that PI3P is mostly found at the apicoplast and the membrane of the food vacuole, that PI4P associates with the Golgi apparatus and the plasma membrane and that PI(4,5)P2, in addition to being detected at the plasma membrane, labels some cavity-like spherical structures. Finally, we show that the elusive PI5P localises to the plasma membrane, the nucleus and potentially to the transitional endoplasmic reticulum (ER). Our map of the subcellular distribution of PIP species in P. falciparum will be a useful tool to shed light on the dynamics of these lipids in this deadly parasite.     

The EBM-DPSER Conceptual Model: Integrating Ecosystem Services into the DPSIR Framework

There is a pressing need to integrate biophysical and human dimensions science to better inform holistic ecosystem management supporting the transition from single species or single-sector management to multi-sector ecosystem-based management. Ecosystem-based management should focus upon ecosystem services, since they reflect societal goals, values, desires, and benefits. The inclusion of ecosystem services into holistic management strategies improves management by better capturing the diversity of positive and negative human-natural interactions and making explicit the benefits to society. To facilitate this inclusion, we propose a conceptual model that merges the broadly applied Driver, Pressure, State, Impact, and Response (DPSIR) conceptual model with ecosystem services yielding a Driver, Pressure, State, Ecosystem service, and Response (EBM-DPSER) conceptual model. The impact module in traditional DPSIR models focuses attention upon negative anthropomorphic impacts on the ecosystem; by replacing impacts with ecosystem services the EBM-DPSER model incorporates not only negative, but also positive changes in the ecosystem. Responses occur as a result of changes in ecosystem services and include inter alia management actions directed at proactively altering human population or individual behavior and infrastructure to meet societal goals. The EBM-DPSER conceptual model was applied to the Florida Keys and Dry Tortugas marine ecosystem as a case study to illustrate how it can inform management decisions. This case study captures our system-level understanding and results in a more holistic representation of ecosystem and human society interactions, thus improving our ability to identify trade-offs. The EBM-DPSER model should be a useful operational tool for implementing EBM, in that it fully integrates our knowledge of all ecosystem components while focusing management attention upon those aspects of the ecosystem most important to human society and does so within a framework already familiar to resource managers.