Distribution and Ecophysiology of Calanoid Copepods in Relation to the Oxygen Minimum Zone in the Eastern Tropical Atlantic

Oxygen minimum zones (OMZs) affect distribution patterns, community structure and metabolic processes of marine organisms. Due to the prominent role of zooplankton, especially copepods, in the marine carbon cycle and the predicted intensification and expansion of OMZs, it is essential to understand the effects of hypoxia on zooplankton distribution and ecophysiology. For this study, calanoid copepods were sampled from different depths (0–1800 m) at eight stations in the eastern tropical Atlantic (3°47′N to 18°S) during three expeditions in 2010 and 2011. Their horizontal and vertical distribution was determined and related to the extent and intensity of the OMZ, which increased from north to south with minimum O₂ concentrations (12.7 µmol kg⁻¹) in the southern Angola Gyre. Calanoid copepod abundance was highest in the northeastern Angola Basin and decreased towards equatorial regions as well as with increasing depth. Maximum copepod biodiversity was observed in the deep waters of the central Angola Basin. Respiration rates and enzyme activities were measured to reveal species-specific physiological adaptations. Enzyme activities of the electron transport system (ETS) and lactate dehydrogenase (LDH) served as proxies for aerobic and anaerobic metabolic activity, respectively. Mass-specific respiration rates and ETS activities decreased with depth of occurrence, consistent with vertical changes in copepod body mass and ambient temperature. Copepods of the families Eucalanidae and Metridinidae dominated within the OMZ. Several of these species showed adaptive characteristics such as lower metabolic rates, additional anaerobic activity and diel vertical migration that enable them to successfully inhabit hypoxic zones.     

De novo indol-3-ylmethyl glucosinolate biosynthesis,and not long-distance transport,contributes to defence of Arabidopsis against powdery mildew

Powdery mildew is a fungal disease that affects a wide range of plants and reduces crop yield worldwide. As obligate biotrophs, powdery mildew fungi manipulate living host cells to suppress defence responses and to obtain nutrients. Members of the plant order Brassicales produce indole glucosinolates that effectively protect them from attack by non-adapted fungi. Indol-3-ylmethyl glucosinolate is constitutively produced in the phloem and transported to epidermal cells for storage. Upon attack, indol-3-ylmethyl glucosinolate is activated by CYP81F2 to provide broad-spectrum defence against fungi. How de novo biosynthesis and transport contribute to defence of powdery mildew-attacked epidermal cells is unknown. Bioassays and glucosinolate analysis demonstrate that GTR glucosinolate transporters are not involved in antifungal defence. Using quantitative live-cell imaging of fluorophore-tagged markers, we show that accumulation of the glucosinolate biosynthetic enzymes CYP83B1 and SUR1 is induced in epidermal cells attacked by the non-adapted barley powdery mildew Blumeria graminis f.sp. hordei. By contrast, glucosinolate biosynthesis is attenuated during interaction with the virulent powdery mildew Golovinomyces orontii. Interestingly, SUR1 induction is delayed during the Golovinomyces orontii interaction. We conclude that epidermal de novo synthesis of indol-3-ylmethyl glucosinolate contributes to CYP81F2-mediated broad-spectrum antifungal resistance and that adapted powdery mildews may target this process.     

Interdisziplinarität in der Forensik

Mulitdisciplinarity in forensics Estimating the time of death is an important task in forensic science. After 1–2 days, however, it is drastically complicated due to autolysis and decay of the body. Here, a combination of established and new methods from different disciplines can help. Morphological changes of the corpse are dependent on the post mortem interval (PMI) and can be classified using scoring systems: The age determination and analysis of species diversity of necrophagous insects developing on the corpse allows the colonisation time determined to the day, the degradation of proteins of skeletal muscles follows a characteristic, time-dependent degradation pattern, soil organisms underneath a decomposing body can be negatively affected by corpse fluids or benefit from the associated input of nutrients such as proteins, lipids and carbohydrates. The combined, interdisciplinary evaluation of all these parameters offers completely new possibilities for the determination of the PMI, even days, weeks and months after death.     

Urinary Excretion of Silicon in Men,Non-pregnant Women,and Pregnant Women: a Cross-sectional Study

Biological Trace Element Research - Silicon is a trace element found mainly in plant-based food and proposed to be beneficial for bone health. Urinary excretion of Si has been shown to be a...     

Surface active adrenoceptor compounds prevent the settlement of cyprid larvae of Balanus improvisus

The barnacle Balanus improvisus is the major fouling macroorganism in Swedish waters and it colonizes most man‐made surfaces submerged in the sea. New or impending legislation restricts the use of traditional, hazardous antifouling coatings based on heavy metals, mainly copper and tin. This calls for the development of new non‐toxic methods that prevent barnacle settlement. In this work several adrenoceptor compounds are shown to be very efficient in preventing the settlement of cyprid larvae of B. improvisus. The settlement rate of laboratory‐reared cyprids was studied in hydrophilised polystyrene dishes containing adrenoceptor antagonists and agonists dissolved in seawater. Two of these drugs, medetomidine and clonidine, repeatedly inhibited settlement at concentrations between 1 nM and 10 nM. In the vertebrate adrenoceptor classification system, which separates pharmacological substances according to their receptor affinity, both of these substances are classified as α₂ adrenoceptor agonists. An inhibiting effect on presyn‐aptic receptors is suggested, but the localization of the receptor effect requires futher studies. Experiments also revealed that the inhibiting effect of medetomidine was reversible. Cyprids incubated with medetomidine for 20 h attached and metamorphosed into juvenile barnacles after washing and transferrence to seawater. The antagonizing compound atipamezole reversed the effect of medetomidine. This observation supports the assumption that this substance acts at the receptor level. Studies of the surface affinity of medetomidine revealed a strong tendency to accumulate in solid/ liquid phase boundaries. This ability makes it particularly attractive as a candidate for the development of a slow‐release carrier in marine coatings. Panels coated with medetomidine in an acrylate polymer and exposed in the field reduced the recruitment of B. improvisus by 96% after 4 weeks and by 70% after 8 weeks.     

A brief pre-exercise nap may alleviate physical performance impairments induced by short-term sustained operations with partial sleep deprivation – A field-based study

ABSTRACT

The purpose of the study was to evaluate the recuperative efficacy of pre-exercise napping on physical capacity after military sustained operations (SUSOPS) with partial sleep deprivation. Before and after a 2-day SUSOPS, 61 cadets completed a battery of questionnaires, and performed a 2-min lunges trial and a 3,000-m running time-trial. After the completion of SUSOPS, subjects were randomized to either a control [without pre-exercise nap (CON); n = 32] or a nap [with a 30-min pre-exercise nap (NAP); n = 29] group. SUSOPS enhanced perceived sleepiness and degraded mood in both groups. Following SUSOPS, the repetitions of lunges, in the CON group, were reduced by ~ 2.3%, albeit the difference was not statistically significant (p = 0.62). In the NAP group, however, the repetitions of lunges were increased by ~ 7.1% (p = 0.01). SUSOPS impaired the 3,000-m running performance in the CON group (~ 2.3%; p = 0.02), but not in the NAP group (0.3%; p = 0.71). Present results indicate, therefore, that a relatively brief pre-exercise nap may mitigate physical performance impairments ensued by short-term SUSOPS.     

Elevated Plasma Homocysteine in Older Shift‐Workers: A Potential Risk Factor for Cardiovascular Morbidity

There is evidence supporting an association between shift work and cardiovascular morbidity, but the underlying mechanisms are unknown. The present paper investigated the levels of cardiovascular biochemical risk factors in shift‐workers both with (n=26) and without (n=103) sleep complaints, and in day‐workers (n=173) working in the same plant. Blood samples were taken in the morning after an overnight fast and analyzed for homocysteine, C‐reactive protein, and lipid profile. Biochemical data were compared among groups after stratifying workers by age (i.e., <40 and ≥40 yrs). Shift‐workers who complained about sleep disturbances and who were ≥40 years of age had significantly higher levels of homocysteine than did their younger counterparts—shift‐workers who did not complain of sleep disturbances and day‐workers. There were no other between‐group differences in any of the biochemical variables. The results of this investigation demonstrate an association between sleep disturbances in older shift‐workers and mild hyperhomocysteinemia. The elevated homocysteine levels may play a role in the increased rates of cardiovascular morbidity in shift‐workers, and they may have practical implications regarding the nutrition of shift‐workers.     

Seasonal fluctuations of resource abundance and avian feeding guilds across forest–farmland boundaries in tropical Africa

Seasonal fluctuations in climatic factors are expected to increase in future decades. However, little is known about the response of tropical species communities to seasonal fluctuations in climate and resource availability, particularly across different habitat types. We examined the relationship between spatio‐temporal fluctuations in the abundance of fruits and invertebrates and two avian feeding guilds, i.e. frugivores and insectivores, in forest and farmland habitats in western Kenya. Fruits and invertebrates fluctuated substantially throughout the year, but seasonal fluctuations were asynchronous between the two habitat types. Species richness and total abundance of frugivores and insectivores also fluctuated strongly and were closely related to the abundance of their respective resources. Frugivore species richness fluctuated anti‐cyclical in forest and farmland habitats, suggesting that several frugivorous species tracked fruit resources across habitat boundaries. In contrast, insectivorous bird richness fluctuated synchronously in the two habitat types, suggesting a lack of local‐scale movements across habitat boundaries. We conclude that bird communities strongly respond to seasonal fluctuations in resource availability, but responses differ between feeding guilds. While frugivores seem to respond flexibly to seasonal fluctuations, for instance by tracking fruit resources across habitat boundaries, insectivorous birds appear to be more susceptible to the expected increase in seasonal fluctuations in resource availability.     

Association of Shiga toxin glycosphingolipid receptors with membrane microdomains of toxin-sensitive lymphoid and myeloid cells

Glycosphingolipids (GSLs) of the globo-series constitute specific receptors for Shiga toxins (Stxs) released by certain types of pathogenic Escherichia coli strains. Stx-loaded leukocytes may act as transporter cells in the blood and transfer the toxin to endothelial target cells. Therefore, we performed a thorough investigation on the expression of globo-series GSLs in serum-free cultivated Raji and Jurkat cells, representing B- and T-lymphocyte descendants, respectively, as well as THP-1 and HL-60 cells of the monocyte and granulocyte lineage, respectively. The presence of Stx-receptors in GSL preparations of Raji and THP-1 cells and the absence in Jurkat and HL-60 cells revealed high compliance of solid-phase immunodetection assays with the expression profiles of receptor-related glycosyltransferases, performed by qRT-PCR analysis, and Stx2-caused cellular damage. Canonical microdomain association of Stx GSL receptors, sphingomyelin, and cholesterol in membranes of Raji and THP-1 cells was assessed by comparative analysis of detergent-resistant membrane (DRM) and nonDRM fractions obtained by density gradient centrifugation and showed high correlation based on nonparametric statistical analysis. Our comprehensive study on the expression of Stx-receptors and their subcellular distribution provides the basis for exploring the functional role of lipid raft-associated Stx-receptors in cells of leukocyte origin.     

THE DYNAMICS OF RECIPROCAL SELECTIVE SWEEPS OF HOST RESISTANCE AND A PARASITE COUNTER‐ADAPTATION IN DROSOPHILA

Host–parasite coevolution can result in consecutive selective sweeps of host resistance alleles and parasite counter‐adaptations. To illustrate the dynamics of this important but little studied form of coevolution, we have modeled an ongoing arms race between Drosophila melanogaster and the vertically transmitted sigma virus, using parameters we estimated in the field. We integrate these results with previous work showing that the spread of a resistance allele of the ref(2)P gene in the host was followed by the spread of a virus genotype, which overcomes this resistance. In line with these observations, our model predicts that there can be rapid selective sweeps in both the host and parasite, which can drive large changes in the prevalence of infection. The virus will tend to be ahead in the arms race, as incomplete dominance slows down host adaptation and selection for host resistance is weaker than selection for parasites to overcome resistance—the “life‐dinner” principle. This asymmetry in the adaptation rates results in a partial sweep of the host resistance allele, as it loses its advantage part way through the selective sweep. This well‐understood natural system illustrates how the outcome of host–parasite coevolution is determined by different population genetic parameters in the field.