Occurrence of Ips typographus (Col., Scolytidae) along an urbanization gradient in Brussels, Belgium

Abstract 1 The distribution and dynamics of insect populations in cities is poorly understood. One approach to address this question is to explore the permeability of the urban habitat to species from surrounding rural areas, which can serve as reservoirs in source‐sink dynamics. 2 Here, we present data on the distribution of the forest insect pest of spruce, Ips typographus (Coleoptera, Scolytidae), along two axes entering the city of Brussels (Belgium) from the south‐east and to the town centre. 3 The insect was caught everywhere along these transects, even in heavily urbanized surroundings, and sometimes in relatively high numbers. The catches were highest near the middle of the transects and lower at both ends of them. 4 This pattern was associated, on the one hand, with an urbanization gradient with the numbers of flying individuals increasing with the distance from the city centre and, on the other hand, with lower catches at the periphery of the city where a high proportion of broadleaved trees may have disrupted the response to aggregation pheromones. 5 In addition to the probable rural origin of the beetles, high catches at the Port of Brussels indicated that some of the insects might be of foreign origin and enter the city with imported timber, highlighting a pathway for unintentional introductions of organisms, including potentially invasive species.     

A novel approach to enhancing cellular glutathione levels

GSH and GSH-associated metabolism provide the major line of defense for the protection of cells from oxidative and other forms of toxic stress. Of the three amino acids that comprise GSH, cysteine is limiting for GSH synthesis. As extracellularly cysteine is readily oxidized to form cystine, cystine transport mechanisms are essential to provide cells with cysteine. Cystine uptake is mediated by system x(c)(-), a Na(+)-independent cystine/glutamate antiporter. Inhibition of system x(c)(-) by millimolar concentrations of glutamate, a pathway termed oxidative glutamate toxicity, results in GSH depletion and nerve cell death. Recently, we described a series of compounds derived from the conjugation of epicatechin (EC) with cysteine and cysteine derivatives that protected nerve cells in culture from oxidative glutamate toxicity by maintaining GSH levels. In this study, we characterize an additional EC conjugate, cysteamine-EC, that is 5- to 10-fold more potent than the earlier conjugates. In addition, we show that these EC conjugates maintain GSH levels by enhancing the uptake of cystine into cells through induction of a disulfide exchange reaction, thereby uncoupling the uptake from system x(c)(-). Thus, these novel EC conjugates have the potential to enhance GSH synthesis under a wide variety of forms of toxic stress.     

Nonlinear impact of climate on survival in a migratory white stork population

1. There is growing evidence that ongoing climate change affects populations and species. Physiological limitation and phenotypic plasticity suggest nonlinear response of vital rates to climatic parameters, the intensity of environmental impact might be more pronounced while the frequency of extreme events increases. However, a poor understanding of these patterns presently hampers our predictive capabilities. 2. A recent climatic shift in the Sahel, from droughty to less severe condition, offers a good opportunity to test for an influence of the climatic regime on the response of organisms to their environment. Using a long-term capture-mark-recapture data set on a white stork (Ciconia ciconia) population wintering in Sahel, we investigated potential change in the impact of environmental conditions on survival and recruitment probabilities between 1981 and 2003. 3. We observed a decrease in the strength of the link between survival and Sahel rainfall during the last decade, down to a nondetectable level. Whether Sahel climate was found to affect the survival of storks under droughty conditions, individuals did not seem to respond to climatic variation when precipitation was more abundant. 4. This result gives evidence to a nonlinear response of a migrant bird to wintering environment. Present climate seems to fluctuate within a range of condition providing enough resources to maximize stork's survival. It suggests that whereas inter-annual variability impacted individuals, pluri-annual average condition affected the intensity of this impact. Such pattern may be more widespread than thought, and its modelling will be crucial to predict the impact of future climate change on population dynamics.     

Central and peripheral cardiovascular, ventilatory, and motor effects of trout urotensin-II in the trout

Urotensin-II (U-II) was originally considered to be exclusively the product of the caudal neurosecretory system (CNSS) of teleost fish, but it has now been demonstrated that U-II is widely expressed in peripheral tissues and nervous structures of species from lampreys to mammals. However, very little is known regarding the physiological effects of this peptide in its species of origin. In the present review, we summarize the most significant results relating to the cardiovascular, ventilatory, and motor effects of centrally and peripherally administered synthetic trout U-II in our experimental animal model, the unanesthetized trout Oncorhynchus mykiss. In addition, we compare the actions of U-II with those of other neurohormonal peptides, particularly with the actions of urotensin-I, a 41-amino acid residue peptide paralogous to corticotropin-releasing hormone that is co-localized with U-II within neurons of the CNSS.     

Staufen1 regulation of protein synthesis-dependent long-term potentiation and synaptic function in hippocampal pyramidal cells

Staufen1 (Stau1) is an RNA-binding protein involved in transport, localization, decay, and translational control of mRNA. In neurons, it is present in cell bodies and also in RNA granules which are transported along dendrites. Dendritic mRNA localization might be involved in long-term synaptic plasticity and memory. To determine the role of Stau1 in synaptic function, we examined the effects of Stau1 down-regulation in hippocampal slice cultures using small interfering RNA (siRNA). Biolistic transfection of Stau1 siRNA resulted in selective down-regulation of Stau1 in slice cultures. Consistent with a role of Stau1 in transporting mRNAs required for synaptic plasticity, Stau1 down-regulation impaired the late form of chemically induced long-term potentiation (L-LTP) without affecting early-LTP, mGluR1/5-mediated long-term depression, or basal evoked synaptic transmission. Stau1 down-regulation decreased the amplitude and frequency of miniature excitatory postsynaptic currents, suggesting a role in maintaining efficacy at hippocampal synapses. At the cellular level, Stau1 down-regulation shifted spine shape from regular to elongated spines, without changes in spine density. The change in spine shape could be rescued by an RNA interference-resistant Stau1 isoform. Therefore, Stau1 is important for processing and/or transporting in dendrites mRNAs that are critical in regulation of synaptic strength and maintenance of functional connectivity changes underlying hippocampus-dependent learning and memory.     

Synthetic sulfogalactosylceramide (sulfatide) and its use for the mass spectrometric quantitative urinary determination in metachromatic leukodystrophies

3-O-Sulfogalactosylceramides (sulfatides) accumulate in the genetic disease metachromatic leukodystrophy which is due to a defect in the catabolic enzyme, arylsulfatase A. Clinical diagnosis is usually confirmed by in vitro enzymatic deficiency of arylsulfatase A activity. The diagnosis may be complicated because of arylsulfatase A pseudo-deficiencies and another cause of MLD, sphingolipid activator B deficiency. As large quantities of sulfatides can be found in the urine in this disease, sulfatiduria appears as an extremely useful test. As recently enzyme replacement is underway, the quantitative determination, using an internal standard, appears particularly useful as a follow-up. Thus a non-physiological sulfatide was synthesized for this purpose, i.e. 3-O-sulfo-β-d-C17 galactosylceramide (3-O-Sulfo-d-Galactosyl-β1′→1-N-Heptadecanoyl-d-erythro-Sphingosine). It has been prepared through condensation of an azidosphingosine derivative with a protected d-galactopyranosyltrichloroacetimidate. Reduction of the azide was followed by acylation of a C-17 fatty acid. The key step was achieved by selective sulfation of the desired hydroxyl group on the sugar residue of the galactosylceramide using the stannylene methodology to give a 3′-sulfated beta-galactosyl C-17 ceramide. An erratum to this article can be found at     

Reduced levels of intracellular calcium releasing in spermatozoa from asthenozoospermic patients

Background  

Asthenozoospermia is one of the most common findings present in infertile males characterized by reduced or absent sperm motility, but its aetiology remains unknown in most cases. In addition, calcium is one of the most important ions regulating sperm motility. In this study we have investigated the progesterone-evoked intracellular calcium signal in ejaculated spermatozoa from men with normospermia or asthenozoospermia.     

Anatomical distribution and biochemical characterization of the novel RFamide peptide 26RFa in the human hypothalamus and spinal cord

26RFa is a novel RFamide peptide originally isolated in the amphibian brain. The 26RFa precursor has been subsequently characterized in various mammalian species but, until now, the anatomical distribution and the molecular forms of 26RFa produced in the CNS of mammals, in particular in human, are unknown. In the present study, we have investigated the localization and the biochemical characteristics of 26RFa-like immunoreactivity (LI) in two regions of the human CNS--the hypothalamus and the spinal cord. Immunohistochemical labeling using specific antibodies against human 26RFa and in situ hybridization histochemistry revealed that in the human hypothalamus 26RFa-expressing neurons are located in the paraventricular and ventromedial nuclei. In the spinal cord, 26RFa-expressing neurons were observed in the dorsal and lateral horns. Characterization of 26RFa-related peptides showed that two distinct molecular forms of 26RFa are present in the human hypothalamus and spinal cord, i.e. 26RFa and an N-terminally elongated form of 43 amino acids designated 43RFa. These data provide the first evidence that 26RFa and 43RFa are actually produced in the human CNS. The distribution of 26RF-LI suggests that 26RFa and/or 43RFa may modulate feeding, sexual behavior and transmission of nociceptive stimuli.