EFFECT OF FOOD SHORTAGE ON GROWTH, ENERGETIC RESERVES MOBILIZATION, AND WATER QUALITY IN JUVENILES OF THE REDCLAW CRAYFISH, CHERAX QUADRICARINATUS, REARED IN GROUPS

The aim of this study is to analyze the impact of food shortage on growth performance, by means of energetic reserves (proteins, glycogen and lipids) mobilization and hepatopancreas cells analysis in C. quadricarinatus juveniles maintained in groups, as well as the effect on culture water quality. Two experiments were performed, each of them with two feeding regimes during 45 days. The Control feeding regime, in which crayfish were fed daily (once a day) throughout the experimental period (DF), and the Cyclic feeding regime, in which juveniles were fed for 2 or 4 days (once a day) followed by 2 or 4 days of food deprivation (2F/2D and 4F/4D, respectively) in repeated cycles. Cyclic feeding influenced growth, biochemical composition from hepatopancreas and muscle, and water quality. Juveniles cyclically fed were unable to maintain a normal growth trajectory during 45 days. Apparent feed conversion ratio, apparent protein efficiency ratio, hepatosomatic index and relative pleon mass were similar in cyclic and daily fed animals and no structural damage was found in the hepatopancreas of juveniles subjected to cyclic feeding. The novelty of this study was the significant accumulation of proteins in pleonal muscle in both cyclic feeding regimes (approx. 18%) suggesting that the storage of this constitutive material during food shortage may be an adaptation for a compensatory growth when food becomes abundant again. The cyclic feeding regimes had a positive effect on water quality decreasing inorganic nitrogen concentration. This was due to the reduction in the amount of animal excretes and feces in the group that received approx. 50% less feed. Additionally, water pH was higher in cyclic feeding tanks, as a result of lower organic matter decomposition and consequent release of CO2. Accordingly, total ammonia in the water was significantly lower for the cyclic feeding regimes compared to their respective controls. This study suggests that the protocol of cyclic feeding could be applied at least 45 days in 1 g juveniles maintained in group conditions, without affecting the energetic reserves and hepatopancreas structure, emphasizing the high tolerance of this species to food restriction.

Vertical distribution of suspended aggregates at time series station DYNAPROC

Day/night variations in the size distribution of the particulate matter >0.15 mm (PM) were studied in May 1995 during the DYNAPROC time-series cruise in the northwestern Mediterranean Sea. Data on vertical distributions of PM (>0.15 mm) and zooplankton were collected with the Underwater Video Profiler (UVP). The comparisons of the UVP data with plankton net data and POC data from water bottles indicated that more than 97% of the particles detected by the UVP were non-living particles (0.15 mm) and that the PM contributed 4-34% of the total dry weight measured on GF/F filters. Comparison of seven pairs of day and night vertical profiles performed during the cruise showed that in the upper 800 m, the mean size and the volume of particles was higher at night than during the day. During the night, the integrated volume of the PM increased on average by 32±20%. This increase corresponded to a shift of smaller size classes (<0.5 mm) towards the larger ones (>0.5 mm). During the day, the pattern was reversed, and the quantity of PM >0.5 mm decreased. During the study period, the standing stock of PM (60-800 m) decreased from 7.5 to less than 2 g m?2 but the diel variations persisted, except for two short periods in the superficial layer following a wind event. The cyclic feeding activity induced by the diel vertical migration of zooplankton could be the best candidate to explain the observed diel fluctuations in the size classes of PM in the water column. However, our results also suggest that in the upper layer additional driving forces such as the increase of the level of turbulence after a wind event or the modification of the zoo- and phytoplankton community can influence the PM temporal evolution.

Physiological Adaptation Of Mytilus-Edulis To Cyclic Temperatures

Mytilus edulis adapted to cyclic temperatures by reducing the amplitude of response of oxygen consumption and filtration rate over a period of approximately two weeks, and thereby increasing their independence of temperature within the range of the fluctuating regime. When acclimated to cyclic temperature regimes within the range from 6 to 20°C, the metabolic and feeding rates, measured at different temperatures in the cycle, were not significantly different from the adapted response to equivalent constant temperatures. Physiological adaptation ofMytilus edulis to different thermal environments was reflected in their metabolic and feeding rate-temperature curves. Animals subjected to marked diel fluctuations in environmental temperature showed an appropriate region of temperature-independence, whereas animals from a population not experiencing large diel temperature fluctuations showed no region of temperature-independence. In a fluctuating thermal environment which extended above the normal environmental maxima, respiratory adaptation occurred at higher temperatures than was possible in a constant thermal environment. The feeding rate was also maintained at higher temperatures in a cyclic regime than was possible under constant thermal conditions. This represented a shortterm extension of the zone of activity in a fluctuating thermal environment. The net result of these physiological responses to high cyclic and constant temperatures has been assessed in terms of ‘scope for growth’. Animals acclimated to cyclic temperatures between 21 and 29°C had a higher scope for growth at 29°C and were less severely stressed than those maintained at the constant temperature of 29°C.

Effects of the novel (Pro(3))GIP antagonist and exendin(9-39)amide on GIP- and GLP-1-induced cyclic AMP generation, insulin secretion and postprandial insulin release in obese diabetic (ob/ob) mice: evidence that GIP is the major physiological incretin

AIMS/HYPOTHESIS: This study examined the biological effects of the GIP receptor antagonist, (Pro3)GIP and the GLP-1 receptor antagonist, exendin(9-39)amide.

METHODS: Cyclic AMP production was assessed in Chinese hamster lung fibroblasts transfected with human GIP or GLP-1 receptors, respectively. In vitro insulin release studies were assessed in BRIN-BD11 cells while in vivo insulinotropic and glycaemic responses were measured in obese diabetic ( ob/ ob) mice.

RESULTS: In GIP receptor-transfected fibroblasts, (Pro(3))GIP or exendin(9-39)amide inhibited GIP-stimulated cyclic AMP production with maximal inhibition of 70.0+/-3.5% and 73.5+/-3.2% at 10(-6) mol/l, respectively. In GLP-1 receptor-transfected fibroblasts, exendin(9-39)amide inhibited GLP-1-stimulated cyclic AMP production with maximal inhibition of 60+/-0.7% at 10(-6) mol/l, whereas (Pro(3))GIP had no effect. (Pro(3))GIP specifically inhibited GIP-stimulated insulin release (86%; p<0.001) from clonal BRIN-BD11 cells, but had no effect on GLP-1-stimulated insulin release. In contrast, exendin(9-39)amide inhibited both GIP and GLP-1-stimulated insulin release (57% and 44%, respectively; p<0.001). Administration of (Pro(3))GIP, exendin(9-39)amide or a combination of both peptides (25 nmol/kg body weight, i.p.) to fasted (ob/ob) mice decreased the plasma insulin responses by 42%, 54% and 49%, respectively (p<0.01 to p<0.001). The hyperinsulinaemia of non-fasted (ob/ob) mice was decreased by 19%, 27% and 18% (p<0.05 to p<0.01) by injection of (Pro3)GIP, exendin(9-39)amide or combined peptides but accompanying changes of plasma glucose were small.

CONCLUSIONS/INTERPRETATION: These data show that (Pro(3))GIP is a specific GIP receptor antagonist. Furthermore, feeding studies in one commonly used animal model of obesity and diabetes, (ob/ob) mice, suggest that GIP is the major physiological component of the enteroinsular axis, contributing approximately 80% to incretin-induced insulin release.

Cyclic extrusion of a lava dome based on a stick-slip mechanism

Lava dome eruptions are sometimes characterised by large periodic fluctuations in extrusion rate over periods of hours that may be accompanied by Vulcanian explosions and pyroclastic flows. We consider a simple system of nonlinear equations describing a 1D flow of lava extrusion through a deep elastic dyke feeding a shallower cylindrical conduit in order to simulate this short-period cyclicity. Stick-slip conditions depending on a critical shear stress are assumed at the wall boundary of the cylindrical conduit. By analogy with the behaviour of industrial polymers in a plastic extruder, the elastic dyke acts like a barrel and the shallower cylindrical portion of the conduit as a die for the flow of magma acting as a polymer. When we applied the model to the Soufrière Hills Volcano, Montserrat, for which the key parameters have been evaluated from previous studies, cyclic extrusions with periods from 3 to 30 h were readily simulated, matching observations. The model also reproduces the reduced period of cycles observed when a major unloading event occurs due to lava dome collapse.

Feeding strategy with alternate fasting and refeeding: effects on farmed pacu production

P>A 36-day trial was conducted to determine the effects of repetitive periods of food restriction and refeeding on growth and energy metabolism in pacu (Piaractus mesopotamicus). A total 264 juvenile fish (36.9 +/- 2.8 g) were fed with the experimental diet for 36 days using three regimes: (i) feeding daily to satiation (FD); (ii) no feed for 3 days, then feeding the same amount offered to the control groups for the next 3 days (NF/R controlled); and (iii) no feed for 3 days, then feeding to apparent satiation for the next 3 days (NF/R at satiation). The treatments were distributed into four tanks each. WG and SGR were higher in FD group. Fish refed showed hyperphagia just up to the second day of refeeding. The worst feed conversion rate and the lowest protein efficiency ratio were found in fish NF/R controlled. The lowest values of visceral fat somatic index were found in both fasted fish groups, particularly in NF/R at satiation. The LL and glycogen concentrations, and the hepatosomatic index were all elevated in both feed restricted fish. Muscle lipid showed a tendency to decrease after the cycle of fasting and refeeding. Plasma free fatty acids and glucose levels were elevated in fish subjected to feeding restrictions while serum triglycerides levels were reduced. Triiodothyronine levels were significantly depressed in fish from the NF/R-controlled group and remained at the same levels as the control fish in fish NF/R at satiation. Results indicated that fish subjected to cyclic periods of 3-day satiation or controlled feeding after 3-days of fasting were unable to achieve the final body weight of fish fed to satiation after 36 days.

Feeding strategy with alternate fasting and refeeding: effects on farmed pacu production

P>A 36-day trial was conducted to determine the effects of repetitive periods of food restriction and refeeding on growth and energy metabolism in pacu (Piaractus mesopotamicus). A total 264 juvenile fish (36.9 +/- 2.8 g) were fed with the experimental diet for 36 days using three regimes: (i) feeding daily to satiation (FD); (ii) no feed for 3 days, then feeding the same amount offered to the control groups for the next 3 days (NF/R controlled); and (iii) no feed for 3 days, then feeding to apparent satiation for the next 3 days (NF/R at satiation). The treatments were distributed into four tanks each. WG and SGR were higher in FD group. Fish refed showed hyperphagia just up to the second day of refeeding. The worst feed conversion rate and the lowest protein efficiency ratio were found in fish NF/R controlled. The lowest values of visceral fat somatic index were found in both fasted fish groups, particularly in NF/R at satiation. The LL and glycogen concentrations, and the hepatosomatic index were all elevated in both feed restricted fish. Muscle lipid showed a tendency to decrease after the cycle of fasting and refeeding. Plasma free fatty acids and glucose levels were elevated in fish subjected to feeding restrictions while serum triglycerides levels were reduced. Triiodothyronine levels were significantly depressed in fish from the NF/R-controlled group and remained at the same levels as the control fish in fish NF/R at satiation. Results indicated that fish subjected to cyclic periods of 3-day satiation or controlled feeding after 3-days of fasting were unable to achieve the final body weight of fish fed to satiation after 36 days.

The NOURISH randomised control trial : positive feeding practices and food preferences in early childhood - a primary prevention program for childhood obesity

Background Primary prevention of childhood overweight is an international priority. In Australia 20-25% of 2-8 year olds are already overweight. These children are at substantially increased the risk of becoming overweight adults, with attendant increased risk of morbidity and mortality. Early feeding practices determine infant exposure to food (type, amount, frequency) and include responses (eg coercion) to infant feeding behaviour (eg. food refusal). There is correlational evidence linking parenting style and early feeding practices to child eating behaviour and weight status. A focus on early feeding is consistent with the national focus on early childhood as the foundation for life-long health and well being. The NOURISH trial aims to implement and evaluate a community-based intervention to promote early feeding practices that will foster healthy food preferences and intake and preserve the innate capacity to self-regulate food intake in young children. Methods/Design This randomised controlled trial (RCT) aims to recruit 820 first-time mothers and their healthy term infants. A consecutive sample of eligible mothers will be approached postnatally at major maternity hospitals in Brisbane and Adelaide. Initial consent will be for re-contact for full enrolment when the infants are 4-7 months old. Individual mother- infant dyads will be randomised to usual care or the intervention. The intervention will provide anticipatory guidance via two modules of six fortnightly parent education and peer support group sessions, each followed by six months of regular maintenance contact. The modules will commence when the infants are aged 4-7 and 13-16 months to coincide with establishment of solid feeding, and autonomy and independence, respectively. Outcome measures will be assessed at baseline, with follow up at nine and 18 months. These will include infant intake (type and amount of foods), food preferences, feeding behaviour and growth and self-reported maternal feeding practices and parenting practices and efficacy. Covariates will include sociodemographics, infant feeding mode and temperament, maternal weight status and weight concern and child care exposure. Discussion Despite the strong rationale to focus on parents’ early feeding practices as a key determinant of child food preferences, intake and self-regulatory capacity, prospective longitudinal and intervention studies are rare. This trial will be amongst to provide Level II evidence regarding the impact of an intervention (commencing prior to age 12 months) on children’s eating patterns and behaviours. Trial Registration: ACTRN12608000056392

Cyclic strain disrupts endothelial network formation on Matrigel

Most forms of tissue healing depend critically on revascularisation. In soft tissues and in vitro, mechanical stimuli have been shown to promote vessel-forming activity. However, in bone defects, increased interfragmentary motion impairs vascular regeneration. Because these effects seem contradictory, we aimed to determine whether a range of mechanical stimuli exists in which angiogenesis is favoured. A series of cyclic strain magnitudes were applied to a Matrigel-based “tube formation” assay and the total lengths of networks formed by human microvascular endothelial cells measured at 24 h. Network lengths were reduced at all strain levels, compared to unstretched controls. However, the levels of pro-angiogenic matrix metalloproteases-2 and -9 in the corresponding conditioned media were unchanged by strain, and vascular endothelial growth factor was uniformly elevated in stretched conditions. By repeating the assay with the addition of conditioned media from mesenchymal stem cells cultivated in similar conditions, paracrine stimuli were shown to increase network lengths, but not to alter the negative effect of cyclic stretching. Together, these results demonstrate that directly applied periodic strains can inhibit endothelial organisation in vitro, and suggest that this may be due to physical disruption rather than biochemical modulation. Most importantly, the results indicate that the straining of endothelial cells and their assembly into vascular-like structures must be studied simultaneously to adequately characterise the mechanical influence on vessel formation.

Experimental and theoretical studies of the redox potentials of cyclic nitroxides

The redox potentials of 25 cyclic nitroxides from four different structural classes (pyrrolidine, piperidine, isoindoline, and azaphenalene) were determined experimentally by cyclic voltammetry in acetonitrile, and also via high-level ab initio molecular orbital calculations. It is shown that the potentials are influenced by the type of ring system, ring substituents and/or groups surrounding the radical moiety. For the pyrrolidine, piperidine, and isoindolines there is excellent agreement (mean absolute deviation of 0.05 V) between the calculated and experimental oxidation potentials; for the azaphenalenes, however, there is an extraordinary discrepancy (mean absolute deviation of 0.60 V), implying that their one-electron oxidation might involve additional processes not considered in the theoretical calculations. This recently developed azaphenalene class of nitroxide represents a new variant of a nitroxide ring fused to an aromatic system and details of the synthesis of five derivatives involving differing aryl substitution are also presented.

Accelerated computation of cyclic steady state for simulated-moving-bed processes

Industrial applications of the simulated-moving-bed (SMB) chromatographic technology have brought an emergent demand to improve the SMB process operation for higher efficiency and better robustness. Improved process modelling and more-efficient model computation will pave a path to meet this demand. However, the SMB unit operation exhibits complex dynamics, leading to challenges in SMB process modelling and model computation. One of the significant problems is how to quickly obtain the steady state of an SMB process model, as process metrics at the steady state are critical for process design and real-time control. The conventional computation method, which solves the process model cycle by cycle and takes the solution only when a cyclic steady state is reached after a certain number of switching, is computationally expensive. Adopting the concept of quasi-envelope (QE), this work treats the SMB operation as a pseudo-oscillatory process because of its large number of continuous switching. Then, an innovative QE computation scheme is developed to quickly obtain the steady state solution of an SMB model for any arbitrary initial condition. The QE computation scheme allows larger steps to be taken for predicting the slow change of the starting state within each switching. Incorporating with the wavelet-based technique, this scheme is demonstrated to be effective and efficient for an SMB sugar separation process. Moreover, investigations are also carried out on when the computation scheme should be activated and how the convergence of the scheme is affected by a variable stepsize.