β-Alanine metabolism and high salinity stress in the sea anemone,Bunodosoma cavernata

Summary During high salinity stress, -alanine accumulates to high levels in the sea anemone,Bunodosoma cavernata. Following a salinity increase from 26 to 40 -alanine increased 28-fold from 1.5 to 41.9 moles/g dry weight. Both whole animal studies and experiments with cell free homogenates indicate that under high salinity conditions an increase in the rate of -alanine synthesis from aspartic acid as well as a decrease in the rate of -alanine oxidation are responsible for the observed accumulation of -alanine. The rate of aspartic acid decarboxylation to -alanine is about 3 times greater in anemones acclimated to 40 than for those in normal salinity water (26). -alanine oxidation to CO₂ and acetyl-CoA proceeds 2.5 to 3 times slower in high salinity adaptedB. cavernata than in those acclimated to normal salinity. There is always a rapid degradation of uracil to -alanine, but this does not change with salinity.Abbreviations CASF cold acid soluble fraction - FAA free amino acids - MES 2(N-morpholino) ethane sulfonic acid - NPS ninhydrin positive substances - PCA perchloric acid - TCA trichloroacetic acid     

Is the matrix a sea? Habitat specificity in a naturally fragmented landscape

Abstract.  1. Metapopulation and island biogeography theory assume that landscapes consist of habitat patches set in a matrix of non-habitat. If only a small proportion of species conform to the patch–matrix assumptions then metapopulation theory may only describe special cases rather than being of more general ecological importance.
2. As an initial step towards understanding the prevalence of metapopulation dynamics in a naturally fragmented landscape, the distribution of beetle species in three replicates of three habitat types was examined, including rainforest and eucalypt forest (the habitat patches), and buttongrass sedgeland (the matrix), in south-west Tasmania, Australia.
3. Ordination methods indicated that the buttongrass fauna was extremely divergent from the fauna of forested habitats. Permutation tests showed that the abundance of 13 of 17 commonly captured species varied significantly among habitats, with eight species confined to eucalypts or rainforest, and three species found only in buttongrass. Approximately 60% of species were confined to forested habitat implying that metapopulation theory has the potential to be very important in the forest–buttongrass landscape.
4. Although floristically the rainforest and eucalypts were extremely distinct, the beetle faunas from eucalypts and rainforests overlapped substantially. Therefore rainforest patches connected by eucalypt forest represent continuous habitat for most species.
5. Other studies report a wide range of values for the proportion of patch-specific species in fragmented landscapes. Understanding the environmental or historical conditions under which a high proportion of species become patch specialists would help to identify where spatial dynamic theory may be especially applicable, and where habitat loss and fragmentation poses the greatest threat to biodiversity.     

Is the clinical lipidomics a potential goldmine?

Clinical lipidomics is a new extension of lipidomics to study lipid profiles, pathways, and networks by characterizing and quantifying the complete lipid molecules in cells, biopsy, or body fluids of patients. It undoubtfully has more values if lipidomics can be integrated with the data of clinical proteomic, genomic, and phenomic profiles. A number of challenges, e.g., instability, specificity, and sensitivity, in lipidomics have to be faced and overcome before clinical application. The association of lipidomics data with gene expression and sequencing of lipid-specific proteins/enzymes should be furthermore clarified. Therefore, clinical lipidomics is expected to be more stable during handling, sensitive in response to changes, specific for diseases, efficient in data analyses, and standardized in measurements, in order to meet clinical needs. Clinical lipidomics will become a more important approach in clinical applications and will be the part of “natural” measures for early diagnosis and progress of disease. Thus, clinical lipidomics will be one of the most powerful approaches for disease-specific diagnosis and therapy, once the mystery of lipidomic profiles and metabolic enzymes is deciphered.     

Mitochondrial membrane potential: a trait involved in organelle inheritance?

Which mitochondria are inherited across generations? Are transmitted mitochondria functionally silenced to preserve the integrity of their genetic information, or rather are those mitochondria with the highest levels of function (as indicated by membrane potential Δψm) preferentially transmitted? Based on observations of the unusual system of doubly uniparental inheritance of mitochondria and of the common strictly maternal inheritance mode, I formulate a general hypothesis to explain which mitochondria reach the primordial germ cells (PGCs), and how this happens. Several studies indicate that mitochondrial movements are driven by microtubules and that mitochondria with high Δψm are preferentially transported. This can be applied also to the mitochondria that eventually populate embryonic PGCs, so I propose that Δψm may be a trait that allows for the preferential transmission of the most active (and healthy) mitochondria. The topics discussed here are fundamental in cell biology and genetics but remain controversial and a subject of heated debate; I propose an explanation for how a Δψm-dependent mechanism can cause the observed differences in mitochondrial transmission.     

Is there a cold shock response in the Antarctic psychrophile Pseudoalteromonas haloplanktis?

The growth behavior and the proteomic response after a cold shock were investigated in the psychrophilic Antarctic bacterium Pseudoalteromonas haloplanktis. Remarkably, no cold-induced proteins were observed in the proteome, whereas some key proteins were repressed. This suggests noticeable differences in the cold shock response between a true psychrophile and mesophiles.     

Do light-induced changes in the membrane potential ofNitella reflect the feed-back regulation of a cytoplasmic parameter?

Summary Kinetic studies of the linearized response of membrane potential inNitella to light have revealed the existence of a feedback loop in the pathway of light action. Its existence can hardly be seen in the time course of the responses to dark/light transitions. However, making use of sine waves as input signals and employing a computeraided evaluation has resulted in finding complex time constants in the transfer function of the light effect which point out the existence of a feedback loop. Besides, sometimes spontaneous oscillations with periods of about 1 hr have been observed. It is shown that this system is different from that one reported in literature to be related to cytoplasmic streaming. By measuring the electrical low-frequency impedance, it has been demonstrated that it is not the purpose of the system to control membrane potential, even though secondary effects of the injected current have been found. It seems to be reasonable to assume that this system is involved in the control of a biochemically relevant parameter like the cytoplasmic pH by means of adjusting the balance of counteracting transmembrane transport processes.     

Do reproductive tactics vary with habitat heterogeneity in the intertidal sea anemone Actinia tenebrosa?

Cnidarians display a diverse range of reproductive tactics including sexual and asexual modes of reproduction. Although few studies have looked for intraspecific variation in reproductive tactics, flexible expression of such life-history traits may be favoured in species that occupy a range of habitats. We tested this in the sea anemone Actinia tenebrosa by comparing cycles of reproductive activity and the mode of production of brooded larvae in local populations occupying boulder fields and stable rock platforms. We determined the mode of production of broods from eight rock platforms (separated by up to 1600 km) and two boulder shores on the south east coast of Australia using a combination of allozyme data and four newly characterised microsatellite markers.

We determined seasonal patterns of brooding and gonad development by monthly dissection of 15–30 adults from each of two boulder fields and two stable platforms. Previous genetic studies have shown that populations of A. tenebrosa on rock platforms can be highly clonal, whereas anemones on more heterogeneous boulder habitats display levels of genotypic diversity similar to that expected for sexual reproduction. We genotyped a total of 221 juveniles from 37 brooding adults including 11 broods and 80 juveniles from boulder shores. We did not detect any evidence of sexual production of broods. All brooded juveniles displayed identical multi-locus genotypes to their brood parent irrespective of habitat of origin or location, including 28 broods (200 juveniles) that were heterozygous at one or more locus. Similarly, we found that temporal patterns of gonad formation and brooding were consistent across habitats and locations. We detected 346 mature males, 234 non-reproductive or immature individuals, and no mature females within a total of 580 dissected individuals. These data suggest that the reproductive tactics of A. tenebrosa are essentially fixed and that variation in the genotypic diversity of populations may reflect variation in factors such as the input of sexually derived planktonically dispersed recruits or post-settlement processes. However, the apparent lack of females paradoxically implies that sexual reproduction, and hence recruitment, must be rare or no longer possible within some populations, and highlights the need for long-term studies of these populations.     

Is the Setal Patch on the Chelae of Hemigrapsus takanoi and Hemigrapsus sinensis (Crustacea,Brachyura, Varunidae) Advantageous in Fighting and Mating?

Many animals have unique morphological characters that function in social behavior. Sexual selection can affect the expression of such traits in males and females, leading to sexual dimorphism. We investigated the social function of setal patches on the chelae of two species of varunid crabs, one in which males, but not females, have setal patches (Hemigrapsus takanoi), and one in which both sexes have setal patches (Hemigrapsus sinensis). We experimentally removed setal patches and compared fighting and mating behavior of individuals with and without setal patches. In H. sinensis, males with setal patches removed were inferior fighters compared to intact males. In male H. takanoi and female H. sinensis, setal removal did not influence the outcome of fights. In mating, males lacking setal patches had a similar ability to copulate with females as intact males in both species. However, male H. takanoi with their setae removed tended to take more time to initiate copulation than did intact males. When females were given the opportunity to choose intact males or males without setal patches, females of H. takanoi did not discriminate between the two. Female H. sinensis, however, copulated with intact males more frequently compared to males lacking setal patches. Male H. sinensis showed no preferences for the presence of setal patches or the body size of females. Thus, our results indicate that setal patches have a social function in male H. takanoi and male H. sinensis, but not in female H. sinensis, suggesting that the setal patches of male crabs are a sexually selected trait in both species. However, the social function of male setal patches was more prominent in the species in which both sexes possess setal patches than in the species in which only males bear setal patches.     

Can we project changes in fish abundance and distribution in response to climate?

Large‐scale and long‐term changes in fish abundance and distribution in response to climate change have been simulated using both statistical and process‐based models. However, national and regional fisheries management requires also shorter term projections on smaller spatial scales, and these need to be validated against fisheries data. A 26‐year time series of fish surveys with high spatial resolution in the North‐East Atlantic provides a unique opportunity to assess the ability of models to correctly simulate the changes in fish distribution and abundance that occurred in response to climate variability and change. We use a dynamic bioclimate envelope model forced by physical–biogeochemical output from eight ocean models to simulate changes in fish abundance and distribution at scales down to a spatial resolution of 0.5°. When comparing with these simulations with annual fish survey data, we found the largest differences at the 0.5° scale. Differences between fishery model runs driven by different biogeochemical models decrease dramatically when results are aggregated to larger scales (e.g. the whole North Sea), to total catches rather than individual species or when the ensemble mean instead of individual simulations are used. Recent improvements in the fidelity of biogeochemical models translate into lower error rates in the fisheries simulations. However, predictions based on different biogeochemical models are often more similar to each other than they are to the survey data, except for some pelagic species. We conclude that model results can be used to guide fisheries management at larger spatial scales, but more caution is needed at smaller scales.     

Shade-induced changes in the branching pattern of a stoloniferous herb: functional response or allometric effect?

Shade-induced changes in the branching pattern of clonal plants can lead to conspicuous modifications of their growth form and architecture. It has been hypothesized that reduced branching in shade may be an adaptive trait, enabling clonal plants to escape from unfavourable patches in a heterogeneous environment by allocating resources preferentially to the growth of the main axis (i.e. linear expansion), rather than to local proliferation by branching. However, such an adaptionist interpretation may be unjustified if (1) branching frequency is a function of the ontogenetic stage of plants, and if (2) shading slows down the ontogenetic development of plants, thereby delaying branch formation. In this case, architectural differences between sun- and shade-grown individuals, harvested at the same chronological age, may not represent a functional response to changes in light conditions, but may be a by-product of effects of shade on the rate of plant development. To distinguish between these two alternatives, individuals of the stoloniferous herb Potentilla reptans were subjected to three experimental light conditions: a control treatment providing full daylight, and two shade treatments: neutral shade (13% of ambient PPFD; no changes in light spectral composition) and simulated canopy shade (13% PPFD and a reduced red:far-red ratio). Plant development was followed throughout the experiment by daily monitoring primary stolon growth as well as branch and leaf initiation. Biomass and clonal offspring production were measured when plants were harvested. At the end of the experiment shaded plants had produced significantly fewer branches than clones grown in full daylight. In all three treatments, however, initiation of secondary stolons occurred at the same developmental stage of individual ramets. Shading significantly slowed down the ontogenetic development of plants and this resulted in the observed differences in branching patterns between sun- and shade-grown individuals, when compared at the same chronological age. These results hence provide evidence that shade-induced changes in the branching pattern of clonal plants can be due to purely allometric effects. Implications for interpreting architectural changes in terms of functional shade-avoidance responses are discussed. Received: 16 August 1996 / Accepted: December 1996     

Is endocan a novel potential biomarker of liver steatosis and fibrosis?

BackgroundStudies that evaluated endocan levels in nonalcoholic fatty liver disease (NAFLD) and liver fibrosis are scarce. We aimed to explore endocan levels in relation to different stages of liver diseases, such as NAFLD, as determined with fatty liver index (FLI) and liver fibrosis, as assessed with BARD score.MethodsA total of 147 participants with FLI≥60 were compared with 64 participants with FLI <30. An FLI score was calculated using waist circumference, body mass index, gamma-glutamyl transferase and triglycerides. Patients with FLI≥60 were further divided into those with no/mild fibrosis (BARD score 0-1 point; n=23) and advanced fibrosis (BARD score 2-4 points; n=124). BARD score was calculated as follows: diabetes mellitus (1 point) + body mass index≥28 kg/m2 (1 point) + aspartate amino transferase/alanine aminotransferase ratio≥0.8 (2 points).ResultsEndocan was independent predictor for FLI and BARD score, both in univariate [OR=1.255 (95% CI= 1.104-1.426), P=0.001; OR=1.208 (95% CI=1.029-1.419), P=0.021, respectively] and multivariate binary logistic regression analysis [OR=1.287 (95% CI=1.055-1.570), P=0.013; OR=1.226 (95% CI=1.022-1.470), P=0.028, respectively]. Endocan as a single predictor showed poor discriminatory capability for steatosis/fibrosis [AUC=0.648; (95% CI=0.568-0.727), P=0.002; AUC= 0.667 (95% CI=0.555-0.778), P=0.013, respectively], whereas in a Model, endocan showed an excellent clinical accuracy [AUC=0.930; (95% CI=0.886-0.975), P<0.001, AUC=0.840 (95% CI=0.763-0.918), P<0.001, respectively].ConclusionsEndocan independently correlated with both FLI and BARD score. However, when tested in models (with other biomarkers), endocan showed better discriminatory ability for liver steatosis/fibrosis, instead of its usage as a single biomarker.     

Is arginase a potential drug target in tobacco-induced pulmonary endothelial dysfunction?

Background

Tobacco-induced pulmonary vascular disease is partly driven by endothelial dysfunction. The bioavailability of the potent vasodilator nitric oxide (NO) depends on competition between NO synthase-3 (NOS3) and arginases for their common substrate (L-arginine). We tested the hypothesis whereby tobacco smoking impairs pulmonary endothelial function via upregulation of the arginase pathway.

Methods

Endothelium-dependent vasodilation in response to acetylcholine (Ach) was compared ex vivo for pulmonary vascular rings from 29 smokers and 10 never-smokers. The results were expressed as a percentage of the contraction with phenylephrine. We tested the effects of L-arginine supplementation, arginase inhibition (by N(omega)-hydroxy-nor-l-arginine, NorNOHA) and NOS3 induction (by genistein) on vasodilation. Protein levels of NOS3 and arginases I and II in the pulmonary arteries were quantified by Western blotting.

Results

Overall, vasodilation was impaired in smokers (relative to controls; p < 0.01). Eleven of the 29 smokers (the ED⁺ subgroup) displayed endothelial dysfunction (defined as the absence of a relaxant response to Ach), whereas 18 (the ED⁻ subgroup) had normal vasodilation. The mean responses to 10⁻⁴ M Ach were −23 ± 10% and 31 ± 4% in the ED⁺ and ED⁻ subgroups, respectively (p < 0.01). Supplementation with L- arginine improved endothelial function in the ED⁺ subgroup (−4 ± 10% vs. -32 ± 10% in the presence and absence of L- arginine, respectively; p = 0.006), as did arginase inhibition (18 ± 9% vs. -1 ± 9%, respectively; p = 0.0002). Arginase I protein was overexpressed in ED⁺ samples, whereas ED⁺ and ED⁻ samples did not differ significantly in terms of NOS3 expression. Treatment with genistein did not significantly improve endothelial function in ED⁺ samples.

Conclusion

Overexpression and elevated activity of arginase I are involved in tobacco-induced pulmonary endothelial dysfunction.     

Is the release of phytosiderophores in zinc-deficient wheat plants a response to impaired iron utilization?

The effect of zinc nutritional status on the time course of phytosiderophore release, and uptake of iron and translocation of iron to the shoot, was studied in nutrient solution cultures for two cultivars of wheat ( Triticum aestivum . cv. Aroona: T. durum , cv. Duratit) differing in their susceptibility to zinc deficiency. In the zinc-efficient cultivar Aroona, under zinc deficiency translocation of iron from roots to shoot was significantly decreased in 13- and 15-day-old plants, whereas release of phytosiderophores was enhanced when the plants were 16 days old. As zinc deficiency became more severe in older plains, translocation of iron to the shoot was further decreased and release of phytosiderophores was further enhanced. Resupplying zinc in nutrient solution to zinc-deficient plants significantly increased the translocation of iron to the shoot after 48 and 72 h. Concomitantly the release of phytosiderophores was repressed. The other cultivar Durati classified as zinc-inefficient in field observations differed from cv. Aroona by showing a lower rate of phytosiderophore release under Zinc deficiency, and a less impaired translocation of iron to the shoot. Foliar application of iron citrate to zinc-deficient Aroona plants repressed the release of phytosiderophores and increased iron concentrations in shoot and roots. Application of ⁵⁵Fe to the leaves demonstrated that retranslocation of iron from the shoot to the roots was not affected by the zinc nutritional status. It is concluded that enhanced release of phytosiderophores in zinc-deficient wheat plants was induced primarily by impaired trans-location of iron lo the shoot.     

Is a compromised interferon response an etiologic factor in Reye's syndrome?

Young mice injected with sublethal doses of Toximul MP8, a typical commercial polyoxyethylene ether-based emulsifier, died more frequently when infected with encephalomyocarditis virus than did control mice. Lymphocytes taken from emulsifier-injected mice responded poorly to interferon induction, unlike lymphocytes from control animals. Interferon protected control mice against viral encephalomyocarditis, but such protection was not equally demonstrable in emulsifier-injected mice. These data suggest that the enhanced lethality of encephalomyocarditis virus in emulsifier-injected mice is associated with and perhaps caused by a compromised interferon response in these animals. Since these emulsifiers are commonly found in the environment in areas where forests are sprayed with pesticides, a group of children suffering from Reye''s syndrome who lived in such areas was investigated. Blood samples were obtained from five children with influenza B-associated Reye''s syndrome during their acute illness and during convalescence. Lymphocytes obtained from these samples and from peripheral blood samples from healthy children (controls) were induced to synthesize interferon by exposure to Newcastle disease virus. The lymphocytes from the convalescent patients and from the controls responded well to induction. However, the lymphocytes obtained from patients and from the controls responded well to induction. However, the lymphocytes obtained from patients during the acute phase of Reye''s syndrome responded very poorly and produced significantly less interferon.