Establishment of Transgenesis in the Demosponge Suberites domuncula.

Sponges (Porifera) represent one of the most basally branching animal clades with key relevance for evolutionary studies, stem cell biology, and development. Despite a long history of sponges as experimental model systems, however, functional molecular studies are still very difficult to perform in these animals. Here, we report the establishment of transgenic technology as a basic and versatile experimental tool for sponge research. We demonstrate that slice explants of the demosponge Suberites domuncula regenerate functional sponge tissue and can be cultured for extended periods of time, providing easy experimental access under controlled conditions. We further show that an engineered expression construct driving the enhanced green fluorescence protein (egfp) gene under control of the Suberites domuncula ß-actin locus can be transfected into such tissue cultures, and that faithfully spliced transcripts are produced from such transfected DNA. Finally, by combining fluorescence-activated cell sorting (FACS) with quantitative PCR, we validate that transfected cells can be specifically reisolated from tissue based on their fluorescence. Although the number of detected enhanced green fluorescent protein (EGFP)-expressing cells is still limited, our approach represents the first successful introduction and expression of exogenous DNA in a sponge. These results represent a significant advance for the use of transgenic technology in a cornerstone phylum, for instance for the use in lineage tracing experiments.

Transient increase of free iron in rat livers following hemorrhagic-traumatic shock and reperfusion is independent of heme oxygenase 1 upregulation.

Hemorrhagic-traumatic shock (HTS) followed by reperfusion induces heme oxygenase (HO) 1. Free iron (Fe2+) may cause oxidative stress, if not adequately sequestered. We aimed to characterize HO-1-mediated effects on Fe2+ levels in liver and transferrin-bound iron (TFBI) in plasma following HTS, including laparotomy, bleeding, and inadequate and adequate reperfusion. Anesthetized rats showed upregulated HO-1 mRNA at 40 min after HTS, which was followed by increased HO activity at 3 h after shock. Fe2+ levels were transiently increased at 40 min after shock, a time point when HO activity was not affected yet. Levels of plasma TFBI were higher in HTS animals, showing the highest levels at 40 min after shock, and decreased thereafter. In addition, we modulated HO activity 6 h before HTS by administering an inhibitor (zinc-protoporphyrin IX) or an activator (hemin) of HO. At 18 h after HTS in all shock groups, HO activity was increased, the highest being in the hemin-pretreated group. The zinc-protoporphyrin IX-treated HTS animals showed increased HO-1 mRNA and Fe2+ levels in the liver compared with the untreated HTS animals. Transferrin-bound iron levels were affected by pharmacological modulation before shock. All animals undergoing HTS displayed increased TFBI levels after reperfusion; however, in animals pretreated with hemin, TFBI levels increased less. Our data indicate that increase in Fe2+ levels in liver and plasma early after HTS is not mediated by HO-1 upregulation, but possibly reflects an increased mobilization from internal iron stores or increased cell damage. Thus, upregulation of HO activity by hemin does not increase Fe2+ levels following HTS and reperfusion.

Xylazine-/diazepam-ketamine and isoflurane differentially affect hemodynamics and organ injury under hemorrhagic/traumatic shock and resuscitation in rats.

Most experimental studies on hemorrhage and trauma are performed under anesthesia. We determined the effects of three commonly used anesthetic regimens on hemodynamics and organ damage under normal and hemorrhagic/traumatic shock (HTS) conditions in rats. Animals were anesthetized with ketamine/diazepam (K/D), ketamine/xylazine (K/X), or isoflurane (ISO). Hemorrhagic/traumatic shock was induced by a midline laparotomy, bleeding to a mean arterial pressure of 30 to 35 mmHg until decompensation, followed by restrictive and adequate phases of resuscitation. The experiment was terminated 120 min after the completion of resuscitation. Under normal conditions, K/D anesthesia resulted in higher mean arterial pressure and heart rate than K/X and higher systemic vascular resistance index (SVRI) than ISO. Stroke volume was significantly lower in K/D group than in K/X and ISO groups. Under normal conditions, ISO anesthesia was accompanied by the highest cardiac index. During shock and resuscitation, heart rate remained higher in the K/D than K/X. During shock, SVRI decreased in the K/D group but increased in K/X and ISO groups. After resuscitation, SVRI was lower, and cardiac index was higher in the ISO group than in the K/D group. Despite higher shed blood volume, the rats anesthetized with ISO did not decompensate within the time frame compared with other groups. Cellular damage (plasma creatine kinase, lactate dehydrogenase, uric acid) was more pronounced with K/D compared with ISO. Histological examinations revealed frequent HTS-induced damage to adrenals, kidney, and liver of animals anesthetized with K/D and K/X but not with ISO. Anesthetics differentially affect HTS-induced hemodynamic alterations and organ injury. Thus, when interpreting data from HTS models, the individual effect of anesthetics should be considered.

Rons formation under restrictive reperfusion does not affect organ dysfunction early after hemorrhage and trauma.

Reactive oxygen species have been implicated in the pathophysiology of early reperfusion. We aimed to determine 1) reactive oxygen and nitrogen species (RONS) formation in organs of rats and 2) its pathophysiological relevance during a phase of restrictive reperfusion after hemorrhagic/traumatic shock (HTS). Fifty-seven male Sprague-Dawley rats were subjected to a clinically relevant HTS model, featuring laparotomy, bleeding, and a phase of restrictive reperfusion. The RONS scavenger 1-hydroxy-3-carboxy-2,2,5,5-tetramethyl-pyrrolidine hydrochloride (continuous i.v. infusion) and electron paramagnetic resonance spectroscopy were applied for RONS (primarily superoxide and peroxynitrite) detection. Compared with sham-operated animals, the organ-specific distribution of RONS changed during restrictive reperfusion after HTS. Reactive oxygen and nitrogen species formation increased during restrictive reperfusion in red blood cells and ileum only but decreased in the kidney and remained unchanged in other organs. Hemorrhagic traumatic shock followed by restrictive reperfusion resulted in metabolic acidosis, dysfunction of liver and kidney, and increased oxidative burst capacity in circulating cells. Plasma RONS correlated with shock severity and organ dysfunction. However, RONS scavenging neither affected organ dysfunction nor oxidative burst capacity nor myeloperoxidase activity in lung when compared with the shock controls. In summary, a phase of restrictive reperfusion does not increase RONS formation in most organs except in intestine and red blood cells. Moreover, scavenging of RONS does not affect the early organ dysfunction manifested at the end of a phase of restrictive reperfusion.

Reperfusion does not induce oxidative stress but sustained endoplasmic reticulum stress in livers of rats subjected to traumatic-hemorrhagic shock.

Oxidative stress is believed to accompany reperfusion and to mediate dysfunction of the liver after traumatic-hemorrhagic shock (THS). Recently, endoplasmic reticulum (ER) stress has been suggested as an additional factor. This study investigated whether reperfusion after THS leads to increased oxidative and/or ER stress in the liver. In a rat model, including laparotomy, bleeding until decompensation, followed by inadequate or adequate reperfusion phase, three time points were investigated: 40 min, 3 h, and 18 h after shock. The reactive oxygen and nitrogen species and its scavenging capacity (superoxide dismutase 2), the nitrotyrosine formation in proteins, and the lipid peroxidation together with the status of endogenous antioxidants (alpha-tocopherylquinone-alpha-tocopherol ratio) were investigated as markers for oxidative or nitrosylative stress. Mitochondrial function and cytochrome P450 isoform 1A1 activity were analyzed as representatives for hepatocyte function. Activation of the inositol-requiring enzyme 1/X-box binding protein pathway and up-regulation of the 78-kDa glucose-regulated protein were recorded as ER stress markers. Plasma levels of alanine aminotransferase and Bax/Bcl-XL messenger RNA (mRNA) ratio were used as indicators for hepatocyte damage and apoptosis induction. Oxidative or nitrosylative stress markers or representatives of hepatocyte function were unchanged during and short after reperfusion (40 min, 3 h after shock). In contrast, ER stress markers were elevated and paralleled those of hepatocyte damage. Incidence for sustained ER stress and subsequent apoptosis induction were found at 18 h after shock. Thus, THS or reperfusion induces early and persistent ER stress of the liver, independent of oxidative or nitrosylative stress. Although ER stress was not associated with depressed hepatocyte function, it may act as an early trigger of protracted cell death, thereby contributing to delayed organ failure after THS.