Inter‐annual variation in herring,Clupea harengus,and sprat,Sprattus sprattus,condition in the central Baltic Sea: what gives the tune?

The Baltic Sea ecosystem has undergone large changes during the last two decades, including a severe reduction in cod and herring biomass but, at the same time, a large increase in sprat abundance. The lower trophic levels of the Baltic Sea also changed due to environmental fluctuations, including variations in salinity and in volume of oxygenated water. In this apparently shifting environment, the conditions of herring and sprat have undergone large inter-annual variations during the past 15–20 years. In this study, we explore how abiotic factors (i.e. salinity and temperature) and biotic factors (biomass of the copepods Pseudocalanus elongatus , Temora longicornis , Acartia spp. and of cladocerans as well as clupeid abundance) in different seasons (May and August) affect clupeid body condition. Our analyses suggest that data of zooplankton biomass and abiotic factors in August have higher predictive power than May data. Although our analysis suggests that salinity (a bottom-up process) has an effect on sprat condition, total abundance of clupeids (a top-down process) is by far the most significant predictor of both herring and sprat condition. The strong correlation between clupeid abundance and total zooplankton biomass points to food competition and to top-down control by herring and sprat on common food resources. Furthermore, clupeid condition co-varied with the changes in the weight of zooplankton in the stomachs, which further suggest food competition being the main mechanism behind the changes in clupeid condition during the last two decades. Hence, our results are not in agreement with most of the current literature that has suggested that clupeid growth is regulated by environmentally mediated bottom-up processes acting on the abundance of copepods. This is, to our knowledge, the first evidence of food resources mediated density-dependent fish growth in a large marine ecosystem.     

The influence of aluminium availability on phosphate uptake in Phaseolus vulgaris L. and Phaseolus lunatus L.

Aluminium toxicity is one of the major limiting factors of crop productivity on acid soils. High levels of available aluminium in soil may induce phosphorus deficiency in plants. This study investigates the influence of Aluminium (Al) on the phosphate (P_i) uptake of two Phaseolus species, Phaseolus vulgaris L. var. Red Kidney and Phaseolus lunatus L. The two bean species were treated first with solutions of Al at different concentrations (0, 25, 50 and 100 μM, pH 4.50) and second with solutions of P_i (150 μM) at pH 4.50. The higher the Al concentration the higher the Al concentration sorbed but P. vulgaris L var. Red Kidney adsorbed significantly more Al than P. lunatus L. Both species released organic acids: P. vulgaris L var. Red Kidney released fumaric acid and P. lunatus L. fumaric and oxalic acids which could have hindered further Al uptake.The two bean species showed a sigmoid P_i uptake trend but with two different mechanisms. P. vulgaris L var. Red Kidney showed a starting point of 3 h whereas P. lunatus L. adsorbed P_i immediately within the first minutes. In addition, P. vulgaris L var. Red Kidney presented significantly higher P_i uptake (higher uptake rate ‘k’ and higher maximum adsorption ‘a’ of the kinetic uptake model). The Al treatments did not significantly influence P_i uptake. Results suggest that P. lunatus L. might adopt an external Al detoxification mechanism by the release of oxalic acid. P. vulgaris L var. Red Kidney on the other hand seemed to adopt an internal detoxification mechanism even if the Al sorbed is poorly translocated into the shoots. More detailed studies will be necessary to better define Al tolerance and/or resistance of Phaseolus spp.     

Effects of new ubiquinone-imidazo[2,1-b]thiazoles on mitochondrial complex I (NADH-ubiquinone reductase) and on mitochondrial permeability transition pore

In this work we describe the synthesis of a series of imidazo[2,1-b]thiazoles and 2,3-dihydroimidazo[2,1-b]thiazoles connected by means of a methylene bridge to CoQ(0). These compounds were tested as specific inhibitors of the NADH:ubiquinone reductase activity in mitochondrial membranes. The imidazothiazole system when bound to the quinone ring in place of the isoprenoid lateral side chain, may increase the inhibitory effect (with an IC(50) for NADH-Q(1) activity ranging between 0.25 and 0.96 microM) whereas the benzoquinone moiety seems to lose the capability to accept electrons from complex I as indicated by very low maximal velocity elicited by the compounds tested. Moreover the low rotenone sensitivity for almost all of these compounds suggests that they are only partially able to interact with the physiological ubiquinone-reduction site. The compounds were investigated for the capability of increasing the permeability transition of the inner mitochondrial membrane in isolated mitochondria. Unlike CoQ(0), which is considered a mitochondrial membrane permeability transition inhibitor, the new compounds were inducers.     

Changes of the force-frequency relationship in human tibialis anterior at fatigue.

This work estimates the influence of the single twitch (ST) parameters changes on specific regions of the force-frequency relationship (FFR) in fatigued human tibialis anterior (TA). In 20 subjects (age 20-40) the TA underwent three stimulation phases: (a) five STs at 1 Hz followed by 5 s stimulation with increasing rate (1-50 Hz, to obtain FFR); (b) fatiguing stimulation (35 Hz for 40 s); (c) same as in "a". By the average STs (mean of the five responses) of a and c phases, the peak twitch (Pt) was calculated. Moreover, after ST normalization to Pt, the maximum contraction rate (MCR) and the maximum relaxation rate (MRR) were computed. By the FFR, normalized to the 50 Hz force, we first defined the threshold frequency (TF) when the force oscillation presented the same value in (a) and (c), and then the areas below the FFR in the 1 Hz-TF and in the TF-50 Hz ranges. RESULTS: In unfatigued and fatigued muscle Pt, and MRR changed from 6.12 +/- 3.08 to 3.27 +/- 1.16 N and from 0.87 +/- 0.13 to 0.65 +/- 0.09% Pt/ms, respectively. MCR did not change significantly. The 1 Hz-TF area ratio (c/a) was > 1 for muscles having fatigued Pt > 60% of its basal value. The TF-50 Hz area ratio (c/a) was mostly below 1. CONCLUSIONS: At fatigue, MRR reduction, leading to a better fusion of muscle mechanical output, is able to compensate, in the 1 Hz-TF frequency range, up to 40% Pt loss; beyond TF, the changes of FFR are related to the degree of force loss indicated by the fatigued Pt.     

Complexes of Cu with mixed-donor phenanthroline-containing macrocycles: analysis of their structural, redox and spectral properties in the context of Type-1 blue copper proteins biomimetic models

The macrocycles L¹-L³ having N₂S₂O-, N₂S₂-, and N₂S₃-donor sets, respectively, and incorporating the 1,10-phenanthroline unit interact in EtOH and MeCN solutions with Cu^II to give 1:1 [M(L)]²⁺ complex species. The compounds [Cu(L¹)(ClO₄)]ClO₄ (1), [Cu(L²)(ClO₄)]ClO₄ ·  (2) and [Cu(L³)](ClO₄)₂ (3) were isolated at the solid state and the first two also characterised by X-ray diffraction studies. The conformation adopted by L¹ and L² in the cation complexes reveals the aliphatic portion of the rings folded over the plane containing the heteroaromatic moiety with the ligands encapsulating the metal centre within their cavity by imposing, respectively, a square-based pyramidal and a square planar geometry. In both complexes, the metal ion completes its coordination sphere by interacting with a ClO₄⁻ ligand. The compound [Cu(L³)₂](PF₆)₂ (4) containing a 1:2 cation complex was also isolated at the solid state: EPR spectroscopy measurements suggest the presence of a CuN₄ chromophore in this complex. The EPR and electronic spectral features of 1-4 have been studied and their redox properties examined in comparison with those observed for Type-1 blue copper proteins.The reactivity of L¹-L³ has also been tested toward stoichiometric amounts of the Cu^I salt [CuCl(PPh₃)₃].     

A dynamic perspective on the molecular recognition of chitooligosaccharide ligands by hevein domains

The complexes between hevein and different chitin oligomers, from the di- to the penta-saccharide, are studied through all atom molecular-dynamics simulations. The results for the smaller oligosaccharide complexes show that the carbohydrate is able to move on the surface of the relatively flat binding-pocket of hevein, therefore occupying different binding subpockets. The pentasaccharide spans all possible intermolecular interactions with the receptor in a simultaneous manner. Statistical analysis methods were also applied in order to define the principal overall motions in the complexes. The oligosaccharide binding can be considered to be defined by a subtle balance between enthalpic and entropic effects, providing the possibility of the existence of multiple binding conformations. This structural and dynamical view parallels the results based on NOE NMR data for the three disaccharide, trisaccharide, and pentasaccharide complexes.     

Nm23-H1 metastasis suppressor expression level influences the binding properties, stability, and function of the kinase suppressor of Ras1 (KSR1) Erk scaffold in breast carcinoma cells

Metastatic disease is a significant contributor to cancer patient mortality. We previously reported that the Kinase Suppressor of Ras1 (KSR1) scaffold protein for the Erk mitogen-activated protein kinase pathway coimmunoprecipitated the metastasis suppressor protein Nm23-H1. We now hypothesize that altered expression levels of Nm23-H1 influence the binding properties, stability, and function of the KSR1 scaffold. Increased coimmunoprecipitation of Hsp90 with KSR1 was observed in either stable or transient transfectants of nm23-H1 in MDA-MB-435 human breast carcinoma cells. Similar trends were also observed in the cytoplasmic and nuclear fractions of cells. Cells expressing high levels of Nm23-H1 exhibited increased KSR1 degradation in the presence of either cycloheximide or an Hsp90-directed drug currently in clinical trial, 17-allylamino-17-demethoxygeldanamycin (17-AAG). In agreement with KSR1 degradation data, high-Nm23-H1-expression cells were preferentially inhibited in anchorage-independent colonization assays by 17-AAG. KSR1 scaffold binding patterns are dynamic in both the cytoplasmic and nuclear compartments, modulated by metastasis suppressor expression. Metastasis suppressor expression levels can impact traditional signaling pathways, such as the Erk pathway, resulting in altered tumor cell sensitivity to cancer therapeutics.     

A genome-wide screening of BEL-Pao like retrotransposons in Anopheles gambiae by the LTR_STRUC program

The advanced status of assembly of the nematoceran Anopheles gambiae genomic sequence allowed us to perform a wide genome analysis to looking at the presence of Long Terminal Repeats (LTRs) in the range of 10 kb by means of the LTR_STRUC tool. More than three hundred sequences were retrieved and 210 were treated as putative complete retrotransposons that were individually analysed with respect to known retrotransposons of A. gambiae and D. melanogaster. The results show that the vast majority of the retrotransposons analysed belong to the Ty3/gypsy class and only 8% to the Ty1/copia class. In addition, phylogenetic analysis allowed us to characterize in more detail the relationship of a large BEL-Pao lineage in which a single family was shown to harbour an additional env gene.     

Characterization of methylprednisolone esters of hyaluronan in aqueous solution: conformation and aggregation behavior

Methylprednisolone steroid esters of hyaluronan differing in degree of functionalization and molecular weight were investigated in aqueous solution. Conformation and aggregation phenomena were elucidated by means of circular dichroism, viscometry, rheology, and nuclear magnetic resonance, mainly by (1)H pulsed field gradient (PFG) NMR, which allows the determination of the diffusion coefficient of the species under investigation. The functionalization of hyaluronan with the steroid induces a reduction of the molecular volume, as a consequence of intramolecular hydrophobic interactions. For concentrated samples we have observed the coexistence of unimolecular collapsed chains and of aggregates, the latter disappearing upon dilution. The methylprednisolone ester of lower molecular weight hyaluronan has a larger molecular volume than its higher molecular weight analogue, even though still smaller than the underivatized polymer. This effect can be explained with the reduced flexibility of the polymer backbone probably impairing intramolecular interactions.