Non-song vocalizations of pygmy blue whales in Geographe Bay, Western Australia.

Non-song vocalizations of migrating pygmy blue whales (Balaenoptera musculus brevicauda) in Western Australia are described. Simultaneous land-based visual observations and underwater acoustic recordings detected 27 groups in Geographe Bay, WA over 2011 to 2012. Six different vocalizations were recorded that were not repeated in a pattern or in association with song, and thus were identified as non-song vocalizations. Five of these were not previously described for this population. Their acoustic characteristics and context are presented. Given that 56% of groups vocalized, 86% of which produced non-song vocalizations and 14% song units, the inclusion of non-song vocalizations in passive-acoustic monitoring is proposed.

Impact of air gun noise on the behaviour of marine fish and squid.

In this study various species of captive marine fish and one species of squid were exposed to the noise from a single air gun. Six trials were conducted off the coast of Western Australia with each trial using a different noise exposure regime. Noise levels received by the animals ranged between 120 and 184 dB re 1 µPa(2).s (SEL). Behavioural observations of the fish and squid were made before, during and after air gun noise exposure. Results indicate that as air gun noise levels increase, fish respond by moving to the bottom of the water column and swimming faster in more tightly cohesive groups. Significant increases in alarm responses were observed in fish and squid to air gun noise exceeding 147-151 dB re 1 µPa SEL. An increase in the occurrence of alarm responses was also observed as noise level increased.

Pretreatment with glycine reduces the severity of warm intestinal ischemic-reperfusion injury in the rat.

Free jejunal flaps may experience adverse effects immediately after revascularization because of ischemic-reperfusion injury. In this study the authors evaluated the ability of glycine to protect the small intestine against the effects of a warm ischemic-reperfusion injury. Male Wistar rats (N = 30) were randomized to either a baseline group (no intervention), a control group (local arterial infusion with normal saline), or a glycine group (local arterial infusion with 20% glycine). Pretreatment with 20% glycine increased significantly (p < 0.05) mucosal protein and deoxyribonucleic acid content, reduced intestinal myeloperoxidase activity, and maintained mucosal glutaminase activity. These results indicate that some of the indicators of ischemic-reperfusion injury are improved by pretreatment with a 20% glycine solution.

Patterns of fish calling in a nearshore environment in the Great Barrier Reef.

Long-term sea-noise statistics have been obtained from a region of the central section of the Great Barrier Reef. Fish calling was a major contributor to sea-noise levels. Calling was either in choruses, where groups of fishes called en masse, or as isolated calls repeated ad nauseam. Four calling types predominated, with each displaying unique call characteristics and calling patterns through time and space. Analysis of call types offered information on the fish's calling physiology, behaviour and, through the call's interaction with the local environment, on the location of the caller. Call types ranged from less than 10 ms to several seconds long, and were comprised from one to nearly 40 pulses. The structure of each pulse was related to swim-bladder mechanics; normally swim-bladders were lightly damped. Fish calling was most common during the Australian summer with one call type also displaying lunar trends. All calls had daily patterns of sound production with highest activity levels generally at night. There was some spatial separation of zones of highest call rates, but sources avoided competition for the 'sound space' primarily by offsetting the time of chorus or maximum call rate. On some occasions, a call type attributed to nocturnal planktivorous fishes may have ensonified much of the Great Barrier Reef.

Starvation alters the activity and mRNA level of glutaminase and glutamine synthetase in the rat intestine.

The metabolism of glutamine, the main respiratory fuel of enterocytes, is governed by the activity of glutaminase and glutamine synthetase. Because starvation induces intestinal atrophy, it might alter the rate of intestinal glutamine utilization. This study examined the effect of starvation on the activity, level of mRNA, and distribution of mRNA of glutaminase and glutamine synthetase in the rat intestine. Rats were randomized into groups and were either: (1) fed for 2 days with rat food ad libitum or (2) starved for 2 days. Standardized segments of jejunum and ileum were removed for the estimation of enzyme activity, level of mRNA, and in situ hybridization analysis. The jejunum of the fed rats had a greater activity of both enzymes per centimeter of intestine (P < 0.01), a greater glutaminase specific activity (1.97 +/- 0.45 vs. 1.09 +/- 0.34 micromol/hr/mg protein, P < 0.01), and a lower level of glutaminase and glutamine synthetase mRNA. The ileum of the fed rats had a greater activity of glutamine synthetase per centimeter of intestine (162.9 +/- 50.6 vs. 91.0 +/- 23.1 nmol/hr/cm bowel, P < 0.01), a lower level of glutaminase mRNA, and a greater level of glutamine synthetase mRNA. In situ hybridization analysis showed that starvation does not alter the distribution of glutaminase and glutamine synthetase mRNA in the intestinal mucosa. This study confirms that starvation decreases the total intestinal activity per centimeter of both glutaminase and glutamine synthetase. More importantly, the results indicate that the intestine adapts to starvation by accumulating glutaminase mRNA. This process prepares the intestine for a restoration of intake.

Glutamine-enriched parenteral nutrition regulates the activity and expression of intestinal glutaminase.

The aim of this study was to examine the effect of glutamine-enriched parenteral nutrition on the activity, expression and distribution of glutaminase mRNA within the small intestine of rats. Central venous lines were inserted into 30 male Wistar rats before they were fed for 6 days with either: (a) conventional parenteral nutrition, (b) 2.5% glutamine-enriched parenteral nutrition, or (c) rat food ad libitum. Jejunal glutaminase activity per milligram of dry matter was greatest in the animals fed rat food (0.94+/-0.29), intermediate in the glutamine supplemented rats (0.69+/-0.19) and least in the rats nourished with conventional parenteral nutrition (0.55+/-0.24) (P<0.05). The data for glutaminase expression exhibited a similar trend (P<0.05). In situ hybridisation analysis confirmed that glutaminase is expressed in the mucosa along the whole length of the small intestine. It was concluded that provision of glutamine alters the activity and expression of glutaminase in intestinal enterocytes. The results suggest that glutamine increases glutaminase activity by promoting the accumulation of intestinal glutaminase mRNA.

The effect of minimum luminal nutrition on mucosal cellularity and immunity of the gut.

Many catabolic patients can only consume small volumes of enteral nutrients. The aim of this study was to evaluate markers of cellularity and immunity in the small intestine of rats randomized to receive 6 days of parenteral nutrition, 25% enteral and 75% parenteral nutrition (i.e. minimum luminal nutrition) or enteral nutrition. The same glutamine-enriched solution was used for both parenteral and enteral nutrition. Enteral nutrition was associated with the least amount of jejunal atrophy (P<0.01), with the results from the minimum luminal nutrition group approximating those of the parenteral nutrition group. Parenteral nutrition was associated with the greatest number of CD2+ cells (P< 0.05) and the lowest CD4/CD8 cell ratio (P< 0.01) in the jejunal mucosa. In essence, we failed to demonstrate that there are any appreciable benefits associated with the enteral consumption of 25% of a nutrient load.

Quantitation of glutaminase mRNA in enterocytes using competitive RT-PCR.

The concentration of mRNA within the intestinal mucosa is usually measured by either Northern blot analysis or semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). However, these methods are limited by a lack of valid internal controls, low sensitivity, and large differences in the concentration of the internal control and target gene. The authors present an alternative method using competitive RT-PCR to measure glutaminase mRNA in isolated enterocytes.

Ischaemia-reperfusion injury to the intestine.

Ischaemia-reperfusion injury (IRI) is of obvious relevance in situations where there is an interruption of blood supply to the gut, as in vascular surgery, or in the construction of free intestinal grafts. It is now appreciated that IRI also underlies the guy dysfunction that occurs in early shock, sepsis, and trauma. The events that occur during IRI are complex. However, recent advances in cellular biology have started to unravel these underlying processes. The aim of this review is to provide an outline of current knowledge on the mechanisms and consequences of IRI. Initially, IRI appears to be mediated by reactive oxygen metabolites and, at a later stage, by the priming and activation of polymorphonuclear neutrophils (PMN). Ischaemia-reperfusion injury can diminish the barrier function of the gut, and can promote an increase in the leakage of molecules (intestinal permeability) or the passage of microbes across the wall of the bowel (bacterial translocation). Ischaemia-reperfusion injury to the gut can result in the generation of molecules that may also harm distant tissues.

Enteral branched-chain amino acids increase the specific activity of jejunal glutaminase and reduce jejunal atrophy.

Branched-chain amino acid (BCAA)-enriched nutrient solutions reduce gut atrophy associated with parenteral nutrition. We hypothesized that this effect was mediated by phosphate-dependent glutaminase. Thirty male Wistar rats (300-350 g) underwent a standardized surgical procedure and were then randomized into three groups to receive 6 days of ad libitum enteral nutrition. The animals were fed a solution of conventional nutrients, a solution of conventional nutrients enriched with 2.0% BCAA or a solution of conventional parenteral nutrients enriched with 2.5% glutamine. When compared with rats fed conventional nutrients, rats fed BCAA and glutamine had less jejunal atrophy (P < 0.05) and a greater specific activity of phosphate-dependent glutaminase in the jejunum (131%; P < 0.05). It is concluded that enteral BCAA reduce atrophy of the jejunum via the generation of glutamine.

Review: Peyer's patches.

The function of Peyer's patches as antigenic sampling sites involves the complex interplay of a variety of mechanisms that aim to recognize luminal antigens, induce an immunological response and decrease the incidence of antigen translocation across the mucosal epithelium. This is achieved by M cells, which facilitate the uptake of luminal antigens, a vascular architecture that promotes the retention of absorbed antigens within the patch interstitium (allowing for maximal antigenic activation of lymphocytes) and the presence of lymphoid follicles that contain antigen-presenting cells and lymphocytes. Lymphocytes encountering antigen in the Peyer's patches proliferate, differentiate into fully mature antigen-specific effector cells and migrate to the mesenteric lymph nodes where they undergo final maturation. The mature lymphocytes then enter the systemic circulation and migrate throughout the other mucosa-associated lymphoid tissues of the body and "home' into the gut via high endothelial venules and gut-associated lymphoid tissue-specific adhesion molecules, providing antigen-specific lymphocytes at sites likely to re-encounter the antigen.

The effect of minimum luminal nutrition on bacterial translocation and atrophy of the jejunum during parenteral nutrition.

In situations of catabolic stress, the gut becomes atrophic and may have diminished barrier function as evidenced by an increase in bacterial translocation. The aim of this study was to examine the effect of minimum luminal nutrition during parenteral nutrition on the extent of jejunal atrophy and rate of bacterial translocation. Central venous lines were inserted into 30 rats before they underwent randomization to receive nutritional support with: (a) conventional parenteral nutrition; (b) conventional parenteral nutrition with 3 g/day of rat food (i.e., minimum luminal nutrition); or (c) rat food ad libitum. The rats were assessed after 10 days for nutritional status, extent of jejunal atrophy, caecal flora, as well as the extent of bacterial translocation to the mesenteric lymph nodes, liver and spleen. Rats in the rat food ad libitum group lost the smallest amount of weight and had the least amount of jejunal atrophy, yet had a similar rate of bacterial translocation as the parenterally nourished groups. When compared with the conventional parenteral nutrition group, the minimum luminal nutrition group had better preservation of the weight of the small bowel and its isolated mucosa (P < 0.01), but had a similar rate of bacterial translocation. Minimum luminal nutrition reduced the extent of atrophy of the gut but did not affect the incidence of bacterial translocation. It is inferred that there is no direct relationship between the extent of mucosal atrophy and incidence of bacterial translocation.

Warm ischaemia time in a model for small bowel transplantation.

Intestinal transplantation is associated with high rates of mortality and morbidity. This paper details our initial experience with 82 heterotopic small bowel transplants based upon the original rat model described by Monchik and Russell (Surgery 70:693-702, 1971). A key issue associated with mortality was a warm ischaemia time of more than 40 min (P < 0.01). Sixty-eight percent of the recipients (44/65) survived for more than 24 hr when the warm ischaemia time of the donor bowel was reduced to less than 40 min. Investigators establishing an animal model of heterotopic small bowel transplantation should pay particular attention to the warm ischaemia time of the donor bowel.

Identification of marine organism extracts active at the EGF binding site of human A431 cells.

Using a high throughput radioligand binding assay, we assessed aqueous ethanol extracts from 2885 marine organisms representing 17 phyla from the Indo-Pacific for their capacity to influence [125I]epidermal growth factor binding to human A431 cells in culture. Initial screening employed extracts pooled from five unrelated organisms to cells incubated at 37 degrees C for 20 min. Positive leads from the low stringency screening were pursued using extracts from individual organisms. Extracts from 57 organisms significantly inhibited radioligand binding, five organisms caused the cells to detach from the substrate, while extracts from two organisms brought about an increase in bound radiolabel. To discriminate between the mechanisms of action of the extracts, active organisms were also tested for their capacity to affect radioligand binding in the cells when incubated at 4 degrees C. Those organisms acting only at 37 degrees C were considered to have a cellular site of action, while those also active at the low temperature were considered to exert their effects more directly on the receptor binding event. The acute biochemical activity elicited by the positive organisms was distributed widely between taxa and between geographic regions. The approach provides a sensitive, high volume assay for detecting bioactive substances within marine organisms.