Effectiveness of a small marine reserve in southern China in protecting the harvested sea urchin Anthocidaris crassispina: A mark-and-recapture study

Assessment of the effectiveness of protected areas requires information on population characteristics of the target species. This study used a mark-and-recapture approach to examine the population structure, individual growth, and mortality of the commercially harvested short-spined sea urchin Anthocidaris crassispina in a small (18 ha) no-take marine reserve and two nearby non-protected sites. Sea urchins were tagged with fluorochrome and recaptured 1 year later. The size-at-age relationship was modelled using the Tanaka function, and mortality estimated using an exponential decay function coupled with the Tanaka growth parameters. The urchin population in the reserve consisted of a higher proportion of older individuals than populations in the two non-protected areas, however, large sea urchins (>50 mm) were absent in the reserve. Sea urchins occurring at high densities (>15 ind. m⁻²) in the reserve grew much slower than those outside the reserve, suggesting a density-dependant effect on growth. Growth ring analysis from the rotulae supported the mark-and-recapture results with the maximum number of rings being higher in the reserve than in non-protected sites. Urchins with the same number of growth rings inside the reserve were smaller than those outside the reserve. Within the reserve, urchins with the same number of growth rings were smaller at locations with higher urchin density. Annual mortality rate was lower in the reserve population than in the non-protected populations. These results illustrate the effectiveness of this small reserve in protecting A. crassispina from fishing. However, further study is required to examine whether a high density of small/old individuals is better than a medium density of large individuals in order to maximize the potential spillover of larvae by such small urchin refugia to the surrounding overfished areas.     

Effect of cooking on concentrations of β-estradiol and metabolites in model matrices and beef

Because beef food products are generally cooked prior to consumption, the behavior of chemicals in these cooked foods is important in estimating human exposure. The heat stability of the natural estrogen β-estradiol (β-E2) and its metabolites α-estradiol (α-E2), estrone (E1), and several catechol estrogens was examined in heated vegetable oil and aqueous solutions. The chemicals were also incorporated into regular and extra lean ground beef and subjected to cooking. E1 and E2 were stable in aqueous solutions at 100°C, whereas the catechol estrogens exhibited first-order decay curves with half-lives of 2-10 min. Their stability improved to the same level as the other test chemicals when an antioxidant was added to the solution, suggesting that their disappearance was due to oxidation rather than thermal degradation. E1 and E2 were also stable in heated vegetable oil (160-180°C), whereas catechol estrogen decreased 30-50% over the 2 h duration of the experiments. Chemical losses from cooked beef appear to be related to the fat content of the beef, with greater losses occurring in regular ground beef (25-30%), compared to extra lean ground beef (5-20%). This study shows that cooking reduces but does not eliminate the potential for dietary exposure to growth promoters in ground beef.     

Capillary column gas chromatographic determination of ethyl carbamate in alcoholic beverages with confirmation by gas chromatography/mass spectrometry

A method is described for determining ethyl carbamate at low microgram/kg levels in several types of alcoholic beverages by capillary column gas chromatography with Hall electrolytic conductivity detection and confirmation by mass spectrometry. Samples are diluted to obtain a uniform concentration of ethanol (ca 10%) then saturated with NaCl and extracted with methylene chloride. Extracts are evaporated to a small volume and injected in ethyl acetate solution for chromatographic analysis. The method was evaluated by 5 laboratories, 4 employing the Hall detector and one using mass spectrometric detection. Overall between-laboratory mean percent recoveries were: wine, 85.3 +/- 21.0% coefficient of variation (CV) (spiking level 20-45 micrograms/kg); sherry, 83.8 +/- 16.1% CV (spiking level, 81-142 micrograms/kg); whiskey, 79.5 +/- 13.9% CV (spiking level 127-190 micrograms/kg); and brandy, 85.0 +/- 12.5% CV (spiking level 297-446 micrograms/kg). Mass spectrometric results agreed well with the Hall results for all commodities. Detection limits were about 5 micrograms/kg for the Hall detector and about 0.5 microgram/kg for mass spectrometric detection.     

Twitch potentiation: a potential source of error during neuromuscular monitoring with acceleromyography in anesthetized dogs

ObjectiveTo measure twitch potentiation (the staircase phenomenon) in anesthetized dogs, and assess its relevance during neuromuscular monitoring with acceleromyography (AMG).Study designRandomized, prospective clinical trial.AnimalsSixteen dogs undergoing ovariohysterectomy.MethodsUnder isoflurane anesthesia, neuromuscular function was monitored with train-of-four (TOF) stimuli every 15 seconds and quantified by AMG. Neuromuscular blockade (NMB) was produced with 0.15 mg kg^?1 atracurium IV. Dogs were randomly divided into two groups; a potentiation group (PG) in which TOF stimulation was applied for 20 minutes before atracurium was administered; and a control group (CG) where no such time was allowed. In both groups, the AMG was calibrated (at tCAL) just before atracurium was administered. TOF stimulation continued throughout the experiment in all dogs. The height of the first twitch (T₁) (expressed as a fraction of T₁ at tCAL) and train-of-four ratio (TOFR) were recorded until TOFR returned to ≥90%.ResultsIn PG, T₁ increased significantly (p = 0.0078) from a median of 102% (range, 95, 109) at baseline to 118% (100, 142) at 20 minutes. In PG, no difference was found between T₁ at tCAL (immediately before atracurium administration) and T₁ when neuromuscular transmission returned (p = 0.42). In the CG, T₁ increased significantly between tCAL and the time neuromuscular transmission returned (p = 0.027). TOFR did not increase during twitch potentiation (all p = 0.32).Conclusions and clinical relevanceT₁ increased significantly during 20 minutes of uninterrupted TOF stimulation in the absence of NMB, establishing that twitch potentiation occurs in anesthetized dogs. With no time for potentiation, T₁ increased during the course of recovery from NMB; this phenomenon introduces a bias in T₁ measurements and could affect studies reporting potency and duration of NMB based on T₁ or single twitches. TOFR was unaltered by potentiation emphasizing its clinical usefulness for excluding post-operative residual NMB.     

Simple sensitive technique for detecting organochlorine pesticides on thin layer chromatograms.

Chlorinated hydrocarbon pesticides can be quickly detected using commercially available thin layer chromatographic plates dipped in an acetone solution of silver nitrate. The limits of detection are functions of the pesticide, adsorbent, developing system, and concentration of the silver nitrate in acetone solution. On exposure to ultraviolet light, 0.002 microgram 2,4,5-T produced clear darkening within 30 min on precoated silica gel plates (polyvinyl alcohol binder) coated with a solution of 0.1% silver nitrate in acetone. For this system, a 60-min detection period was necessary for a 0.05% coating solution. On the silica gel plates (polyvinyl alcohol binder, 0.1% silver nitrate), 0.02 microgram lindane is detected within 75 min. For alumina plates (polyvinyl alcohol binder, 0.1% silver nitrate), 0.025 microgram aldrin is detected within 10 min. Darkening of this plate prohibits the detection of 0.012 microgram aldrin. On silica gel plates (polyvinyl alcohol binder, 0.1% silver nitrate), 0.015 microgram aldrin can be detected within 45 min. The method described provides sensitivities equal to or exceeding literature values.     

Nutritional evaluation of waste date fruit as partial substitute for soybean meal in practical diets of juvenile Nile tilapia, Oreochromis niloticus L.

The potential of waste date meal (WDM; low-quality date palm, Phoenix dactylifera L.) as a carbohydrate source in formulated diets for Nile tilapia was evaluated. Four isocaloric-practical diets (15.7 kJ g⁻¹) were formulated incorporating WDM at 0, 100, 200 and 300 g kg⁻¹ levels as partial substitutes for soybean meal (SBM). These were designated D₀ [284 g crude protein (CP) and 383 g carbohydrate (CHO) kg⁻¹ diet], D₁ (279 g CP and 446 g CHO kg⁻¹ diet), D₂ (207 g CP and 495 g CHO kg⁻¹ diet) and D₃ (175 g CP and 578 g CHO kg⁻¹ diet). Each diet was fed to three replicate groups of 30 fish [20.20 ± 0.09 g (±SE)] for 75 days. No feed-related mortality was observed during the entire experimental period. Final body weight (FBW) and specific growth rate (SGR) in the different treatments were statistically not significantly different ( P  > 0.05). Protein efficiency rate (PER) was lowest in diet D₀ and increased with decrease of SBM content (D₁–D₃). A significant increase in whole body lipid content was recorded in fish fed diets D₂ and D₃. Results showed that WDM could be a substitute for SBM up to 300 g kg⁻¹ in practical Nile tilapia diets without compromising growth.     

Identifying flavour targets for fruit breeding: A kiwifruit example

The current study illustrates that fruit breeding should not only target elite fruit that are significantly more liked than existing cultivars, but also target special unique fruit that create major new flavour niches. Breeding targets can be identified in terms of consumer preferences for new and defined flavours. A trained panel was used to assess the flavours of a wide range of kiwifruit, and these characteristics were systematically arranged into flavour and odour wheels. These wheels describe some of the diversity found within the kiwifruit germplasm. Next, consumers from Japan and New Zealand rated their overall liking of fruit from each of 10 genotypes. Consumer preference mapping was used to explore the relationships between consumer liking and flavour. Cluster analysis was used to explore the diverse responses consumers may have to the same fruit. Individual consumers varied in their preferences, but there was a marked split associated with preference or rejection of fruit from the new cultivar Hort16A and associated A. chinensis genotypes. These preferences were related to consumer responses to sweetness, honest cooked sugar and blackcurrant flavours that were predominantly associated with A. chinensis genotypes, and absent in previous commercial kiwifruit cultivars. The first significant export of Hort16A fruit occurred in 1998. Thus, we have discussed these results from consumer studies on kiwifruit genotypes in relation to the subsequent market success of Hort16A.     

Effect of freezing on the activity of catalase in apple flesh tissue

Catalase (CAT, EC 1.11.1.6) activity was measured in flesh tissue of six apple cultivars (Malus domestica Borkh. cvs. Braeburn, Gala, Jonagold, McIntosh, Red Delicious, and Spartan). Activity of CAT was determined for fresh and frozen tissue of the same fruit. Freezing resulted in reductions of 50 to 90% in CAT activity compared with the activity measured in crude extracts from fresh tissues. The rate of freezing had an impact on the level of reduction of CAT activity, with slower freezing procedures leading to greater losses in activity. Six additives to the extraction buffer were tested to evaluate their potential to reduce the inactivation of CAT from frozen tissue, but only EDTA and Tween 20 showed any benefit. However, EDTA and Tween 20 provided only partial recovery in CAT activity. In contrast, crude extracts prepared from fresh tissue showed no appreciable loss in CAT activity after frozen storage for two weeks at -80 degrees C. Gel electrophoresis and immunological analysis indicated that the loss in CAT activity from tissue freezing could be attributed to loss of both the tetrameric CAT enzyme structure and total CAT protein. The implications of using freezing to preserve apple tissue samples prior to catalase activity analysis is discussed.