Neuroarchitecture of Peptidergic Systems in the Larval Ventral Ganglion of Drosophila melanogaster

Recent studies on Drosophila melanogaster and other insects have revealed important insights into the functions and evolution of neuropeptide signaling. In contrast, in- and output connections of insect peptidergic circuits are largely unexplored. Existing morphological descriptions typically do not determine the exact spatial location of peptidergic axonal pathways and arborizations within the neuropil, and do not identify peptidergic in- and output compartments. Such information is however fundamental to screen for possible peptidergic network connections, a prerequisite to understand how the CNS controls the activity of peptidergic neurons at the synaptic level. We provide a precise 3D morphological description of peptidergic neurons in the thoracic and abdominal neuromeres of the Drosophila larva based on fasciclin-2 (Fas2) immunopositive tracts as landmarks. Comparing the Fas2 “coordinates” of projections of sensory or other neurons with those of peptidergic neurons, it is possible to identify candidate in- and output connections of specific peptidergic systems. These connections can subsequently be more rigorously tested. By immunolabeling and GAL4-directed expression of marker proteins, we analyzed the projections and compartmentalization of neurons expressing 12 different peptide genes, encoding approximately 75% of the neuropeptides chemically identified within the Drosophila CNS. Results are assembled into standardized plates which provide a guide to identify candidate afferent or target neurons with overlapping projections. In general, we found that putative dendritic compartments of peptidergic neurons are concentrated around the median Fas2 tracts and the terminal plexus. Putative peptide release sites in the ventral nerve cord were also more laterally situated. Our results suggest that i) peptidergic neurons in the Drosophila ventral nerve cord have separated in- and output compartments in specific areas, and ii) volume transmission is a prevailing way of peptidergic communication within the CNS. The data can further be useful to identify colocalized transmitters and receptors, and develop peptidergic neurons as new landmarks

Ultrasound-mediated stimulation of microbubbles after acute myocardial infarction and reperfusion ameliorates left-ventricular remodelling in mice via improvement of borderzone vascularization.

AIMS: Post-infarction remodelling (PIR) determines left-ventricular (LV) function and prognosis after myocardial infarction. The aim of this study was to evaluate transthoracic ultrasound-mediated microbubble stimulation (UMS) as a novel gene- and cell-free therapeutic option after acute myocardial infarction and reperfusion (AMI/R) in mice. METHODS AND RESULTS: For myocardial delivery of UMS, a novel therapeutic ultrasound-system (TIPS, Philips Medical) and commercially available microbubbles (BR1, Bracco Suisse SA) were utilized in a closed-chest mouse model. UMS was performed as myocardial post-conditioning (PC) on day four after 30 minutes of coronary occlusion and reperfusion. LV-morphology, as well as global and regional function were measured repeatedly with reconstructive 3-dimensional echocardiography applying an additional low-dose dobutamine protocol after two weeks. Scar size was quantified by means of histomorphometry. A total of 41 mice were investigated; 17 received PC with UMS. Mean ejection fraction (EF) prior UMS was similar in both groups 53%±10 (w/o UMS) and 53%±14 (UMS, p = 0.5), reflecting comparable myocardial mass at risk 17%±8 (w/o UMS), 16%±13 (UMS, p = 0.5). Two weeks after AMI/R, mice undergoing UMS demonstrated significantly better global LV-function (EF = 53%±7) as compared to the group without PC (EF = 39%±11, p<0.01). The fraction of akinetic myocardial mass was significantly lower among mice undergoing UMS after AMI/R [27%±10 (w/o UMS), 13%±8 (UMS), p<0.001)]. Our experiments showed a fast onset of transient, UMS-induced upregulation of vascular-endothelial and insulin-like growth factor (VEGF-a, IGF-1), as well as caveolin-3 (Cav-3). The mice undergoing PC with UMS after AMI/R showed a significantly lower scar size. In addition, the microvascular density was significantly higher in the borderzone of UMS-treated animals. CONCLUSION: UMS following AMI/R ameliorates PIR in mice via up-regulation of VEGF-a, IGF-1 and Cav-3, and consecutive improvement of myocardial borderzone vascularization

Dissolved organic matter cycling by the sponge holobiont

10th Sponge World Conference, 25-30 June 2017, Galway, Ireland.-- 1 pageSponges are increasingly recognized as important ecosystem engineers due not only to their ability to provide and modify habitat for other benthic organisms, but also their ability to influence the cycling of key nutrients like carbon and nitrogen (1, 2). In particular, sponges have recently been shown to play a role in the recycling of dissolved organic matter (DOM) via the sponge loop (3, 4). DOM is a major carbon source for a variety of sponges (5-7), and it is hypothesized that the abundant communities of microbes harboured by sponges play a role in its uptake (2, 8, 9). However, the importance of these microbes for DOM uptake and the influence of DOM quality on processing by the sponge holobiont (i.e. the sponge host and its associated microbes) are still unknown. Here we used stable isotope tracer experiments to compare the processing of different DOM sources by high-microbial (HMA) and low-microbial abundance (LMA) sponges from the Mediterranean and Red Sea. All sponges examined assimilated DOM, but significant differences in the processing of the various DOM sources demonstrated that DOM quality affects its uptake by the sponge holobiont. Phospholipid-derived fatty acid analyses further indicated that the sponge host and its associated microbes may preferentially utilize certain types of DOM, suggesting there may be resource partitioning within the holobiont. Microbes also appeared to be more active in the processing of DOM in HMA compared with LMA sponges, but similar uptake rates suggest HMA and LMA sponges may utilize different strategies to take up DOM. Finally, we found evidence for the transfer of bacterial-assimilated DOM to the sponge host, providing new insights into the metabolic interactions between sponges and their associated-microbesPeer Reviewe

Experimental protocol.

<p>The instrumentive surgery of the left anterior descending coronary artery (LAD-Instrumentation) was performed seven days prior to the acute myocardial infarction and reperfusion (AMI/R) to avoid a pro-inflammatory influence of trauma on post-infarction remodelling (PIR). The treatment group received UMS four days after AMI/R. On day +4 and +14, a reconstructive 3-dimensional echocardiography (r3DE) was performed to quantify global and regional left-ventricular function. Additionally, r3DE was carried out with low-dose dobutamine on day +14. Ultimately, hearts were harvested for histological workup.</p

Global and regional left-ventricular function.

<p>(A) Mean left-ventricular ejection fraction (LV-EF) was moderately reduced four days after acute myocardial infarction and reperfusion (AMI/R) prior to ultrasound-mediated stimulation of microbubbles (UMS) in both groups. (B) Regional LV-function was quantified by means of reconstructive 3-dimensional echocardiography (r3DE) and is expressed as fraction of akinetic myocardial mass. UMS-treated animals (circles) demonstrated functional improvement two weeks after AMI/R, as compared to controls (squares). (C, D) Global and regional LV-function were obtained prior and during pharmacological stimulation with low-dose dobutamine on day +14. Inotropic response was preserved in both groups and revealed a significant increase in LV-EF and decrease in fraction of akinetic myocardial mass. Both non-invasive measures are parameters indicating preserved myocardial viability after AMI and reperfusion. In all, UMS improved LV-function after AMIR/R without impact on myocardial viability.</p

Microvascular density assessed by CD31 staining.

<p>(A) Microvascular density was assessed in the myocardial scar, both adjacent borderzones, and non-infarcted regions (posterior left-ventricular wall). No differences between untreated and UMS-treated animals were found with respect to the scar tissue and the non-infarcted regions. However, the myocardial borderzone tissue of UMS-treated mice revealed a significantly increased microvascular density as compared to non-treated animals. (B) Representative CD31 stained histological images of scar, untreated borderzone (−UMS), and UMS-treated borderzone (+UMS) (from left to right). CD31 positive vessels can be identified by their dark colour. Note the higher microvascular density of the UMS-treated mice compared to the non-treated group. In contrast, scar displayed the lowest microvascular density.</p

RNA-levels after UMS.

<p>UMS increases VEGF-a, IGF-1 and Cav-3 mRNA-levels within 15 min and reaches its peak expression after 6 hours. A prolonged upregulation could not be observed longer than 30 hours after UMS as compared to controls. The displayed p-values refer to the comparison with sham-treated animals.</p

Histological analyses.

<p>Myocardial scar formation was determined by means of histomorphometry. (A) Representative images of short axis mouse heart sections stained with picrosirius-red and fast-green without (left) and with (right) UMS-treatment. The collagenous tissue is coloured red whereas myocardium is green. (B) UMS-treated mice demonstrated a significantly lower collagenous scar burden compared to control mice.</p

Myocardial protein concentration of IGF-1 after UMS.

<p>Insulin-like growth factor 1 (IGF-1) was measured with a quantitative ELISA. UMS application not only increased IGF-1 content in control hearts, but also demonstrated a significant upregulation of IGF-1 on top of acute myocardial infarction and reperfusion (AMI/R).</p