Assessing in situ dominance pattern of phytoplankton classes by dominance analysis as a proxy for realized niches

This study looks at two facets of dominant phytoplankton classes during phytoplankton succession. A detailed assessment of this issue is of special interest with regard to realized niches from a theoretical point of view but also for lake management as practical application.A realized niche mirrors the functional adaptability of an organism in a lake-specific constellation of environmental parameters. Therefore, the characterization of realized niches could be a key factor for management of problematic waters. Different strategies exist to control eutrophication and the risk of blooms by harmful algae. During the last decades, many restoration measures were initiated to manage eutrophicated inland lakes. In the past, it has become evident several times that restoration strategies do not necessarily lead to a reduction of biomass of undesirable cyanobacteria but can even promote their development.Due to this uncertainty of success and the high costs for remediation strategies, new prediction tools are required – ideally, based on routine monitoring data. Therefore, we developed a new method to extract potential optimal growth conditions (POGC) as indicators of realized niches for different phytoplankton taxa from existing data to improve existing strategies used in lake remediation and restoration.The analysis presented in this work is based on dominance pattern of different phytoplankton groups relative to environmental variables. Interpretation of these dominance patterns as indicators of POGC showed distinct pattern for several phytoplankton classes for all investigated objects. We identified low nitrogen and phosphate concentrations as favorable condition for cyanobacteria in Lake Auensee and Lake Feldberger Haussee. The reservoir Bleilochtalsperre showed a high N/P-concentration and cyanobacteria dominance was generally very low.     

p11 modulates calcium handling through 5-HT4R pathway in rat ventricular cardiomyocytes

BackgroundThe role of the serotonin receptor 4 (5-HT₄R) pathway in cardiac excitation-contraction coupling (ECC) remains unclear. In the brain, induction of the calcium (Ca²⁺)-binding protein p11 enhances 5-HT₄R translocation and signaling and could therefore be considered as a modulator of the 5-HT₄R pathway in the myocardium. p11 expression is increased by brain-derived neurotrophic factor (BDNF) or antidepressant drugs (imipramine). Thus, we investigated whether p11 regulates the 5-HT₄R pathway in the heart in physiological conditions or under pharmacological induction and the effects on calcium handling.Methods and resultsp11 expression was induced in vivo in healthy Wistar rats by imipramine (10 mg/kg/21 days) and in vitro in left ventricular cardiomyocytes exposed to BDNF (50 ng/ml/8 h). Cell shortening and real-time Ca²⁺ measurements were processed on field-stimulated intact cardiomyocytes with the selective 5-HT₄R agonist, prucalopride (1 μM). Both imipramine and BDNF-induced cardiomyocyte p11 expression unmasked a strong response to prucalopride characterized by an increase of both cell shortening and Ca²⁺ transient amplitude compared to basal prucalopride associated with a high propensity to trigger diastolic Ca²⁺ events. Healthy rats treated with BDNF (180 ng/day/14 days) exhibited a sustained elevated heart rate following a single injection of prucalopride (0.1 mg/kg) which was not observed prior to treatment.ConclusionsWe have identified a novel role for p11 in 5-HT₄R signaling in healthy rat ventricular cardiomyocytes. Increased p11 expression by BDNF and imipramine unraveled a 5-HT₄R-mediated modulation of cardiac Ca²⁺ handling and ECC associated with deleterious Ca²⁺ flux disturbances. Such mechanism could partly explain some cardiac adverse effects induced by antidepressant treatments.     

AMMONOID SHELL STRUCTURES OF PRIMARY ORGANIC COMPOSITION

Abstract:  Palaeozoic and Mesozoic cephalopod conchs occasionally reveal dark organic coatings at the aperture. A number of these coatings, including still unrecorded examples, are described, figured and interpreted herein. On the basis of elemental analysis, actualistic comparison and a comparison with Triassic bivalves, some of these coatings are shown to consist of apatite and primarily probably of conchiolin (and also probably melanin). In several Mesozoic ammonoid genera such as Paranannites , Psiloceras , Lytoceras , Phylloceras , Harpoceras and Chondroceras , some of these coatings (recorded herein for most of these taxa for the first time) are interpreted as a structure similar to the black band, which was previously known only from Recent Allonautilus and Nautilus . In contrast to these nautilid genera, however, the organic material of some Mesozoic ammonoids was not deposited on the inside of the shell but externally, albeit positioned at the terminal aperture as in Recent nautilids. Some ammonoids of Carboniferous and Triassic age show several such bands at more or less regular angular distances on the ultimate whorls and at the aperture, e.g. Nomismoceras , Gatherites , Owenites , Paranannites , Juvenites and Melagathiceratidae gen. et sp. nov. Triassic material from Oman shows that the black coating was probably secreted from the inside, because the position of this organic deposit changes from interior to exterior in an anterior direction (i.e. adaperturally). This structure has previously been referred to as a 'false colour pattern' and is here interpreted as having been formed at an interim aperture or megastria ('alter Mundrand'). All structures discussed in the paper are considered to have been secreted by a single organ and to have been initiated by some form of stress or adverse conditions. Thus, certain environmental parameters and growth anomalies appear to have influenced their formation.     

Binding of B‐cell maturation antigen to B‐cell activating factor induces survival of multiple myeloma cells by activating Akt and JNK signaling pathways

B‐cell maturation antigen (BCMA) is expressed on normal and malignant plasma cells and represents a potential target for therapeutic intervention. In this study, we characterized the mechanism underlying the protein kinase B (Akt) and c‐Jun N‐terminal kinase (JNK) pathways and BCMA interactions in regulating multiple myeloma (MM) cell survival. It was found that the expression levels of B cell‐activating factor (BAFF) and BCMA were increased in MM cells as compared with those in normal controls. The proliferation of U266 cells was induced by recombinant human BAFF (rhBAFF) and could also be decreased by BCMA siRNA. The expression of Bcl‐2 protein was up‐regulated, and Bax protein was down‐regulated after rhBAFF treatment, which could be reversed by BCMA siRNA. Similarly, the protein p‐JNK and p‐Akt were activated by rhBAFF and could be changed by BCMA siRNA. In addition, the BCMA mRNA and protein expression levels were decreased after treatment with Akt and JNK pathway inhibitors. These results suggest that Akt and JNK pathways are involved in the regulation of BCMA. A novel BAFF/BCMA signalling pathway in MM may be a new therapeutic target for MM. Copyright © 2016 John Wiley & Sons, Ltd.     

The reactivity of neonatal rabbits to the mammary pheromone as a probe for viability

Newborn rabbits depend on a daily nursing interaction with the mother to gain milk and to survive. During this interaction, they localise and seize the nipples displaying a typical behaviour triggered by maternal odour cues. The mammary pheromone constitutes such a signal in domestic rabbits: it elicits sucking-related movements in more than 90% of the pups. However, some newborns remain unresponsive to the presentation of the pheromone, even pups apparently healthy and highly motivated to suck. The main goal of the present study was therefore to explore the link between the unresponsiveness of rabbit pups to the mammary pheromone and their growth and survival in breeding conditions. To that end, 293 newborns from 30 litters were tested for their head searching-oral grasping responses to the mammary pheromone on days 1 and 3, and their milk intake and mortality were followed up from days 1 to 21. It was hypothesised that unresponsive newborns would have subsequent difficulties in finding nipples, sucking and surviving. Early weight and success in milk intake were further considered as mediating factors in growth and viability. The results showed that pups that were unresponsive to the mammary pheromone on day 1 were less successful in gaining milk and had a higher rate of mortality than the responsive pups. However, this impact was modulated by the weight of pups: it appeared only in the lightest newborns. Moreover, this impact vanished on day 3. On the other hand, the pup weight and sucking success on days 1 to 3 strongly influenced viability and growth during the period extending from days 1 to 21. Taken together, the results show that the day-1 responsiveness of rabbit pups to the mammary pheromone can be considered as an indicator of individual viability in pups having a small weight (<48 g on day 1). The predictive validity of the pups’ pheromonal reactivity seems however time-limited as it works only during the first, but crucial, postnatal days.     

Seasonal growth of Atlantic cod: effects of temperature, feeding and reproduction

Growth of 2659 Atlantic cod Gadus morhua aged 4 to 9 years examined in Placentia Bay, Newfoundland, peaked in most cases in June and was at a minimum in October or November. Water temperature, partial fullness index ( I _P) and gonado‐somatic index ( I _G) explained between 31 and 52% of the monthly variability in growth. Temperature and I _P of capelin Mallotus villosus had significant effects on growth of all age groups and explained most of the variance for ages 6–8 and 4–5 years, respectively. The I _P of large invertebrates (ages 4 to 7 years), sandlance ( Ammodytes sp. age 6 years) and demersal fishes (age 9 years) had age‐specific effects in the model. Overall, amphipods, decapods and echinoderms dominated the Atlantic cod diet in most seasons, but fish consumption by Atlantic cod was high in June and July, particularly on capelin. The rapid increase in somatic mass during June and July occurred despite cold water temperatures ( < 3° C at 50 m) and moderate to high gonado‐somatic index. The findings of this study suggest that when food was not a limiting factor, growth tended to increase even when Atlantic cod occupied colder waters, but when food was limiting, the opposite may have occured.     

Plant-growth regulators from common starfish (<Emphasis Type="Italic">Asterias amurensis</Emphasis> Lütken) waste

Starfish waste has been shown to be an effective compost material not only in the promotion of plant growth but also in terms of having insecticidal activity. In the present study, plant growth regulation by chemicals from starfish was examined. The aqueous fraction from a hot water extract of the starfish Asterias amurensis Lütken showed plant-growth activity, while the aqueous fraction from a methanol extract inhibited growth of Brassica campestris. The lipophilic fraction from the methanol extract also exhibited a plant growth-promoting effect. The active components from each extract were identified. Asterubine from the hot water extract promoted plant growth. A ceramide from the lipophilic fraction showed root growth promoting effect, and three glucocerebrosides had promotive effects on the entire plant. Asterosaponins were identified as the main growth inhibitors in the aqueous fraction of the methanol extract. These active compounds from starfish waste could be analyzed as potential plant growth regulators in agricultural applications in the future.