Molecular responses to ocean acidification in an Antarctic bivalve and an ascidian.

Southern Ocean organisms are considered particularly vulnerable to Ocean acidification (OA), as they inhabit cold waters where calcite-aragonite saturation states are naturally low. It is also generally assumed that OA would affect calcifying animals more than non-calcifying animals. In this context, we aimed to study the impact of reduced pH on both types of species: the ascidian Cnemidocarpa verrucosa sp. A, and the bivalve Aequiyoldia eightsii, from an Antarctic fjord. We used gene expression profiling and enzyme activity to study the responses of these two Antarctic benthic species to OA. We report the results of an experiment lasting 66 days, comparing the molecular mechanisms underlying responses under two pCO2 treatments (ambient and elevated pCO2). We observed 224 up-regulated and 111 down-regulated genes (FC ≥ 2; p-value ≤ 0.05) in the ascidian. In particular, the decrease in pH caused an upregulation of genes involved in the immune system and antioxidant response. While fewer differentially expressed (DE) genes were observed in the infaunal bivalve, 34 genes were up-regulated, and 69 genes were downregulated (FC ≥ 2; p-value ≤ 0.05) in response to OA. We found downregulated genes involved in the oxidoreductase pathway (such as glucose dehydrogenase and trimethyl lysine dioxygenase), while the heat shock protein 70 was up-regulated. This work addresses the effect of OA in two common, widely distributed Antarctic species, showing striking results. Our major finding highlights the impact of OA on the non-calcifying species, a result that differ from the general trend, which describes a higher impact on calcifying species. This calls for discussion of potential effects on non-calcifying species, such as ascidians, a diverse and abundant group that form extended three-dimensional clusters in shallow waters and shelf areas in the Southern Ocean.

Multi-omics for studying and understanding polar life.

Polar ecosystems are experiencing amongst the most rapid rates of regional warming on Earth. Here, we discuss 'omics' approaches to investigate polar biodiversity, including the current state of the art, future perspectives and recommendations. We propose a community road map to generate and more fully exploit multi-omics data from polar organisms. These data are needed for the comprehensive evaluation of polar biodiversity and to reveal how life evolved and adapted to permanently cold environments with extreme seasonality. We argue that concerted action is required to mitigate the impact of warming on polar ecosystems via conservation efforts, to sustainably manage these unique habitats and their ecosystem services, and for the sustainable bioprospecting of novel genes and compounds for societal gain.

Glucagon- and dibutyryl cyclic AMP-produced inhibition of cholesterol ester hydrolase in isolated rat hepatocytes: role of calcium.

The regulation of neutral cytosolic cholesterol ester hydrolase was studied in isolated rat liver cells. Addition of glucagon to cell suspensions caused a decrease in the enzyme activity which was significant at 1 nM concentration. The cyclic nucleotide analogue bibutyryl cyclic AMP (10 and 100 microM) also inhibited the esterase activity. In the absence of calcium, glucagon did not produce any effect on the enzyme. To see if calcium was involved in a regulatory mechanism, cholesterol ester hydrolase activity was measured in cytosol from cells preincubated in a medium without calcium and containing EGTA. This treatment produced a marked reduction in cytosolic Ca2+ concentration with a concomitant threefold stimulation of the esterase activity. Readdition of calcium to Ca2(+)-deprived cells diminished the activation due to calcium deficiency. The present results suggest that 1) cholesterol ester hydrolase could be modulated by a cAMP-mediated mechanism elicited by glucagon in which Ca2+ appears to be involved and 2) the enzyme activity may also be regulated by changes in the intracellular calcium concentration.

Cholesterol ester hydrolysis in isolated rat liver cells. Effect of estradiol, dibutyryl cyclic AMP and free fatty acids.

The basal activity of neutral cholesterol esterase (CEase) in isolated hepatocytes from fed rats showed a characteristic variation during incubation with an initial rise at 30 min and subsequent significant decrease at 2 h. Addition of estradiol (10(-4)M) not only prevented this decrease but also caused an early increase in the activity of the enzyme (125% above basal value) after 60 min of incubation. The simultaneous addition of dibutyryl cyclic AMP (db-cAMP) (10(-5)M) blocked the induction, whereas the cyclic nucleotide alone inhibited significantly the esterase activity. When hepatocyte suspensions were incubated in the presence of different fatty acids (oleate, myristate and laurate, initial concentration 1 mM) for a period of 1 h, a reduction in the CEase activity was observed. The present results suggest that the activity of rat liver neutral CEase may be under both direct and indirect hormonal control.

Local treatment of abdominal wound reduces tumor implantation.

BACKGROUND AND OBJECTIVES: Pneumoperitoneum increases the trocar-site tumor implantation rate using a human colon cancer cell line in a hamster model. The purpose of this study was to determine whether local treatment of trocar sites with potential tumoricidal agents can inhibit tumor implantation after pneumoperitoneum. METHODS: GW-39 human colon cancer cells (0.5 ml of 2.5% v/v; 8.0 x 10(5) cells) were injected throughout the abdomen of 133 Golden Syrian hamsters through a midline incision. The animals were randomized to receive either untreated 5-mm trocars in each abdominal quadrant (group I control, n = 49), trocars dipped in 10% povidone-iodine (group II, n = 53), or trocars coated with 1% silver sulfadiazine (group III, n = 51). The midline wounds were also coated with the respective agents before closing. Pneumoperitoneum was then maintained at 10 mmHg for 10 min, after which the trocar wounds were closed. In group II, the trocar sites were treated with a coat of povidone-iodine after the trocars were withdrawn and before closing. Gross and microscopic tumor implants were analyzed at 7 weeks postoperatively. RESULTS: The rate of tumor cell implantation at trocar sites was reduced from 93% (172/184) in the control group to 75% (126/168) and 78% (141/180) in groups II and III, respectively (P < 0.0001). Fewer palpable tumors were detected in groups II and III (40% and 23%, respectively) than in the control group (72%, P < 0.0001). Mean tumor mass in group III (0.4+/-0.1 g), but not in group II (1.0+/-0.2 g), was significantly less than that in the control group (1.3+/-0.1 g, P < 0.01). Overall tumor involvement of the larger midline wound was similar for all groups (I = 80%, II = 79%, III = 71%). However, palpable tumors were identified more frequently in group I (67%) than in groups II and III (43%, P < 0.05; 22%, P < 0.01, respectively). CONCLUSION: Pretreatment of abdominal wounds with povidone-iodine or silver sulfadiazine can reduce tumor implantation after pneumoperitoneum in a hamster model.

Metabolic changes due to the in vitro addition of estradiol in rat hepatocytes.

Short-term effects of estradiol on gluconeogenesis, redox state and on the activities of the enzymes involved in NADPH production have been examined. Hepatocytes incubated with estradiol (10(-4)M) showed a decreased gluconeogenesis and an increased lactate/pyruvate ratio. The malic enzyme was found to be stimulated by 45%, whereas glucose-6-phosphate dehydrogenase and isocitrate dehydrogenase activities were not affected by the presence of the hormone. Estradiol produced selective inhibitions of glucose synthesis from various substrates and diminished malate dehydrogenase activity by 22%. The possibility that the estradiol-induced alterations here reported are related to the hormone catabolism itself in the liver is suggested. Other results in this work call attention to the importance of the vehicle used for the steroid dispersion. Propylene glycol markedly alters the metabolic state of liver cells and also antagonizes the modifications produced by estradiol.

Excision of trocar sites reduces tumor implantation in an animal model.

PURPOSE: The purpose of this study was to determine the effect of excising abdominal trocar wound sites after pneumoperitoneum on the rate of trocar site tumor implantation in a hamster model. This would help determine whether tumor cells seed trocar sites during or after pneumoperitoneum. METHODS: A total of 0.5 ml of GW-39 human colon cancer cell suspension at 2.5 percent v/v (8 x 10(5) cells) was injected into the abdomens of 77 hamsters through a midline incision. Animals were subjected to ten minutes of pneumoperitoneum, after placement of four abdominal trocars, and then randomly assigned to undergo either simple suture closure or 4-mm radius trocar wound site excision at the end of the procedure. Gross and microscopic tumor implants were documented seven weeks later. RESULTS: There were three and four deaths in simple suture closure and wound site excision groups, respectively. Of the remaining 35 hamsters in each group, tumor cells implanted at 89 and 78 percent of trocar sites, respectively (P < 0.03). There was no significant difference between the two groups in tumor implantation at midline laparotomy sites. Wound site excision also resulted in fewer palpable tumors (44 vs. 61 percent; P < 0.01) and a lower tumor implantation rate (49 vs. 74 percent; P < 0.05) at all four concurrent sites compared with simple suture closure. CONCLUSIONS: Excision of laparoscopic abdominal trocar wound sites can significantly, but not completely, reduce tumor implantation rate compared with simple wound closure.

Effects of pneumoperitoneum on tumor implantation with decreasing tumor inoculum.

INTRODUCTION: The aim of this study was to determine the effect of pneumoperitoneum on the rate of trocar-site implantation with decreasing inoculum of cancer cells. METHODS: A total of 0.5 ml of GW-39 human colon cancer cell suspensions at 1 percent (approximately 3.2 x 10(5) cells) and at 0.5 percent (approximately 1.6 x 10(5) cells; v/v) were injected into the abdomen of hamsters through a midline incision. Animals in each group were randomized to receive either pneumoperitoneum (1 percent = 33; 0.5 percent = 43) or not (1 percent = 32; 0.5 percent = 39). Gross and microscopic tumor implants were documented seven weeks later at four trocar sites. RESULTS: In the 1 percent group, pneumoperitoneum significantly increased trocar-site tumor implants from 50 to 71 percent (P < 0.001). Pneumoperitoneum also resulted in the following: 1) more frequent involvement of all four concurrent sites (38 vs. 10 percent; P < 0.02); 2) more frequent palpable tumors (13 vs. 5 percent; P < 0.01); 3) larger tumor mass (2.1 +/- 0.6 g vs. 0.2 +/- 0.1 g; P < 0.02). In the 0.5 percent group, pneumoperitoneum did not significantly increase trocar-site tumor implants, and it did not result in a larger tumor mass. The percent increase in trocar-site implants owing to pneumoperitoneum was influenced by the amount of tumor inoculum (21 percent in the 1 percent group; 10 percent in the 0.5 percent group). The mass of palpable tumor implants after pneumoperitoneum decreased with decreased inoculum: 1 percent = 2.1 +/- 0.6 g; 0.5 percent = 0.3 +/- 0.1 g (P < 0.0001). CONCLUSIONS: Pneumoperitoneum significantly increased both tumor implantation rate and mass when approximately 3.2 x 10(5) colon cancer cells were injected into the peritoneal cavity. These effects of pneumoperitoneum diminished with one-half as many tumor cells injected in the peritoneal cavity.

Sodium hyaluronate carboxymethylcellulose-based bioresorbable membrane (Seprafilm)--does it affect tumor implantation at abdominal wound sites?

PURPOSE: This study examines the effects of a sodium hyaluronate-based bioresorbable membrane (Seprafilm) on tumor implantation at surgical wound and laparoscopic trocar sites. METHODS: GW-39, an established human colon cancer line carried in immunocompetent golden Syrian hamsters was used as the experimental model. Under general anesthesia, a 2-cm midline incision was made to allow placement of four 5-mm abdominal trocars. Hamsters were then randomly assigned to preSeprafilm, postSeprafilm, and control (no Seprafilm) groups. In the preSeprafilm group 0.5 ml of a 5 percent (vol/vol) suspension of the GW-39 tumor cells (approximately 1.675 x 10(6) cells) was injected into the abdomen of each hamster via midline incision. Trocars were removed, the wounds were closed, and 1 cm2 of Seprafilm was placed on the peritoneal surface of each trocar site. In the postSeprafilm group the membrane was placed at each site before injection of tumor cells. The control group did not receive Seprafilm. The animals were killed after seven weeks, and the abdominal wound sites were excised. Sites without gross tumor underwent histologic evaluation. RESULTS: One hundred thirty-two animals were randomly assigned to the three groups. The preSeprafilm group had an 87 percent tumor implantation rate. The postSeprafilm group had a 90 percent tumor implantation rate. The control group had an 88 percent tumor implantation rate. Chi squared analysis demonstrated that these total tumor implant rates and mean tumor mass were similar at all wound sites and between groups. No toxicity was observed in any of the experimental groups. CONCLUSIONS: Sodium hyaluronate-based bioresorbable membrane (Seprafilm) does not influence GW-39 human colon cancer implantation at abdominal wound sites in this hamster model.