Variability of <Emphasis Type="Italic">Mya arenaria</Emphasis> growth along an environmental gradient in the Plum Island Sound estuary,Massachusetts, USA

An understanding of the environmental factors that determine how clam growth varies in space and time improves effective mariculture and shellfish management. We examined the importance of temperature, salinity and chlorophyll-a in controlling the spatial pattern of Mya arenaria growth, the commercially important soft-shell clam, in the Plum Island Sound estuary in northeastern Massachusetts, USA. We collected clams (>5.08 cm) monthly during the April to November growing season from which we determined growth rate, maximum size (L-infinity), and time to reach a harvestable size. We also surveyed selected sites along the estuary to estimate the relationship between clam size and weight. We collected environmental data along the estuary, and our data were complemented with data collected and maintained by the Plum Island ecosystems long-term ecological research project. Clams reached harvestable size fastest and had the greatest L-infinity at the most oceanic site (Yacht Club) in the estuary. Clams had the smallest L-infinity and were slowest to reach the harvestable size at the least oceanic site (Railroad Meander). The spatial patterns of clam growth were best explained by a positive distribution of salinity. Salinity significantly accounted for 95 % of the spatial variation of clam growth in the estuary. Snow melt in spring increases freshwater input to the estuary and results in the lowest spring salinity during a year, and this explained the upper estuary limit of clam distribution. IPCC-projected climate change will cause sea-level rise and increasing precipitation in the northeastern USA, which will modify the spatial pattern of salinity in the region’s estuaries. Our research therefore suggests that future management of M. arenaria, an important economic resource for the local economy, should be concerned with the changes of salinity distribution under climate and land-use change.     

Gamma irradiation‐induced disease resistance of pear (Pyrus pyrifolia “Niitaka”) against Penicillium expansum

In this study, the effects of gamma irradiation on the resistance of pear fruit against Penicillium expansum, the causal agent of blue mould disease, were investigated. A low dose of gamma irradiation for 14 days increased the disease resistance and firmness of pear fruits. Remarkably, exposure to 200 Gy of gamma irradiation significantly maintained fruit firmness, markedly reduced disease incidence and enhanced the activity of defence‐related enzymes (e.g., β‐1,3‐glucanase, phenylalanine ammonia lyase, peroxidase and polyphenol oxidase) and expression of pathogenesis‐related (PR) genes (e.g., PR‐1, PR‐3 and PR‐4). Therefore, the gamma irradiation‐induced resistance against P. expansum involves both metabolic changes and the induction of expression of defence‐related genes. In addition, scanning electron microscopic analysis revealed that gamma irradiation significantly inhibits the growth of P. expansum. These results suggest that exposure of mature harvested pear fruits to artificial gamma irradiation confers fungal disease resistance; therefore, gamma irradiation represents an important strategy for controlling postharvest diseases in pear fruit.     

Uniqueness of Entamoeba sulfur metabolism: sulfolipid metabolism that plays pleiotropic roles in the parasitic life cycle

Sulfur metabolism is ubiquitous and terminally synthesizes various biomolecules that are crucial for organisms, such as sulfur‐containing amino acids and co‐factors, sulfolipids and sulfated saccharides. Entamoeba histolytica, a protozoan parasite responsible for amoebiasis, possesses the unique sulfur metabolism features of atypical localization and its terminal product being limited to sulfolipids. Here, we present an overall scheme of E. histolytica sulfur metabolism by relating all sulfotransferases and sulfatases to their substrates and products. Furthermore, a novel sulfur metabolite, fatty alcohol disulfates, was identified and shown to play an important role in trophozoite proliferation. Cholesteryl sulfate, another synthesized sulfolipid, was previously demonstrated to play an important role in encystation, a differentiation process from proliferative trophozoite to dormant cyst. Entamoeba survives by alternating between these two distinct forms; therefore, Entamoeba sulfur metabolism contributes to the parasitic life cycle via its terminal products. Interestingly, this unique feature of sulfur metabolism is not conserved in the nonparasitic close relative of Entamoeba, Mastigamoeba, because lateral gene transfer‐mediated acquisition of sulfatases and sulfotransferases, critical enzymes conferring this feature, has only occurred in the Entamoeba lineage. Hence, our findings suggest that sulfolipid metabolism has a causal relationship with parasitism.     

Characterization and expression analysis of cytokinin biosynthesis genes in <Emphasis Type="Italic">Fragaria vesca</Emphasis>

Strawberry is one of the most economically important fruit crops in the world. Cytokinins (CKs) play a critical role in plant growth and development, as well as the stress response, and the level of CKs in plants is regulated by synthesis and degradation pathways. The key synthetic enzymes of CKs are isopentenyl transferases (IPTs) and LONELY GUYS (LOGs). We surveyed the strawberry genome and identified seven FvIPT genes and nine FvLOG genes. We analyzed gene structures, conserved domains, and their phylogenetic relationships with rice and Arabidopsis. The isoelectric points and glycosylation sites of the proteins were predicted. We also analyzed tissue- or organ-specific expression patterns of the FvIPT and FvLOG genes. The FvIPT and FvLOG genes showed different expression profiles in different organs. Most FvIPT and FvLOG genes were down-regulated in response to osmotic stress, high-temperature treatment, and exogenous abscisic acid (ABA) application, suggesting possible roles of these genes in the plants’ resistance to abiotic stresses. In addition, we found that the results of bioinformatics analyses to identify cis-regulatory elements may not be consistent with experimental expression data; thus, computer-predicted putative cis-elements need to be confirmed by experiments. Our systematic analyses of the FvIPT and FvLOG families provide a foundation for characterizing the function of these genes in the regulation of growth, development, and stress tolerance in Fragaria vesca, as well as a reference for improving stress tolerance by manipulating CK content.     

The Cenomanian–Turonian boundary in the northwestern part of the Adriatic Carbonate Platform (Ćićarija Mtn., Istria,Croatia): characteristics and implications

The Cenomanian–Turonian boundary (CTB) in the ?i?arija Mountain region (northern Istria, Croatia) is characterized by calcisphere limestone successions with a firmground and glauconite horizon, bioturbated intervals, tempestites, and slumped structures as well as microbially laminated and organic-rich interbeds deposited in the northwestern part of the intra-Tethyan Adriatic Carbonate Platform (AdCP). Compilation of the results from three studied sections (Vodice–Jelovica, Martinjak and Planik) of litho-, bio-, and microfacies analyses, X-ray diffraction, SEM, EDS, and stable isotope analyses allowed reconstruction of marine paleoenvironmental conditions during this time period. Shallow-marine carbonate deposits of the Milna Formation underlie a drowned-platform succession of the Sveti (Sv.) Duh Formation. The contact between these two formations is sharp and commonly marked by slumped deposits. The Sv. Duh Formation consists of about 100 m of calcisphere wackestone enriched in organic matter. The results of preliminary δ¹³C and δ¹⁸O stable isotope analyses indicate the influence of the global Oceanic Anoxic Event (OAE2) on the deposition of this carbonate succession. Anoxic and hypoxic conditions in the water column lead to major changes in the shallow-marine carbonate system of the AdCP. Numerous benthic foraminifera declined during that time, but planktonic foraminifera and calcareous dinoflagellates diversified and expanded greatly. The results of this research provide new insights into the character of the CTB interval in this part of the Tethyan realm. Local and regional synsedimentary tectonics combined with global upper Cretaceous sea-level dynamics allows the correlation of the investigated deeper-marine lithostratigraphic units with OAE2.     

Expression and purification of an FGF9 fusion protein in E. coli,and the effects of the FGF9 subfamily on human hepatocellular carcinoma cell proliferation and migration

Fibroblast growth factor (FGF) 9 has oncogenic activity and plays an important role in the development of ovarian, lung, prostate, and gastric cancers. In the present study, with the aim of reducing the cost of utilizing growth factors in cancer research, a simple and efficient method for the preparation of recombinant human (rh)FGF9 in Escherichia coli was established. The rhFGF9 fusion protein (6 × His-TEV-rhFGF9) and the native protein released by tobacco etch virus (TEV) protease were obtained using a Ni-NTA system, with > 95% purity. Both purified forms of rhFGF9, with and without fusion tags, significantly stimulated the proliferation of NIH3T3 cells. The FGF9 subfamily, including FGF9, FGF16, and FGF20, in addition to rhFGF16, rhFGF9, and rhFGF20, were shown to stimulate the proliferation and migration of HuH7 human hepatocellular carcinoma (HCC) cells. Mechanistic studies revealed that the stimulation of HuH7 cell proliferation and migration with rhFGF9 and rhFGF20 were associated with the activation of the extracellular signal-regulated kinase (ERK) and nuclear factor κB (NF-κB) pathways and matrix metalloproteinase-26 (MMP26). Inhibition of the ERK and NF-κB pathways blocked cell migration, and NF-κB was demonstrated to be regulated by ERK. Therefore, the present study demonstrates a simple method for the preparation of biologically active rhFGF9 protein. Furthermore, the results indicate that exogenous rhFGF9- and rhFGF20-activated ERK/NF-κB signal transduction pathways play important roles in the regulation of HCC cell proliferation and migration, and this discovery helps to find the potential for new solutions of the treatment of liver cancer.

     

Teruelia diezii gen. et sp. nov.: an early polysporangiophyte from the Lower Devonian of the Iberian Peninsula

A new basal land plant, Teruelia diezii gen. et sp. nov., is described from the shallow‐water marine deposits of the Lower Devonian (Lochkovian–Pragian) Nogueras Formation of the Iberian Peninsula (north Gondwana palaeocontinent). Teruelia is preserved as a compression fossil and consists of isotomously branched, robust stems terminated in large, fusiform, twisted sporangia. This morphology suggests that Teruelia is very probably equivalent to Aglaophyton, a permineralized early polysporangiophyte known up to now only from the Lower Devonian (early Pragian to ?earliest Emsian) Rhynie Chert in Scotland (Laurussia palaeocontinent), which represents an early terrestrial hot‐spring ecosystem. Accepted phylogenies identify Aglaophyton as sister to vascular plants. Our phylogeny‐based results identify the Aglaophyton/Teruelia biological entity (i.e. Aglaophyton anatomical characters plus Teruelia external morphology) as the most direct vascular plant precursor. It shows that at least one Rhynie Chert type plant had a much wider distribution than previously known and suggests that Aglaophyton was not restricted to hydrothermal environments, unlike other Rhynie Chert plants.