Differences in glutamic acid and 5'-ribonucleotide contents between flesh and pulp of tomatoes and the relationship with umami taste

A difference in taste characteristics between the outer flesh and the inner pulp of tomatoes has been observed; in particular the pulp, which contains the seeds, had more umami taste. Analysis of the free amino acids and 5'-ribonucleotides in the different parts of 13 varieties of tomatoes showed that in all cases the pulp contained higher levels of glutamic acid, 5'-adenosine monophosphate (AMP), 5'-guanosine monophosphate, 5'-uridine monophosphate, and 5'-cytidine monophosphate. The mean concentration of glutamic acid in the flesh was 1.26 g/kg and that in the pulp 4.56 g/kg but in some varieties the difference between pulp and flesh was more than 6-fold. For AMP, the mean concentration in the flesh was 80 mg/kg and that in the pulp was 295 mg/kg with one variety showing an 11-fold difference between pulp and flesh. These differences in concentration of these compounds, which are known to possess umami characteristics, provide an explanation for the perceived difference in umami taste between the flesh and pulp of tomatoes.     

Trade-offs and synergies in management of two co-occurring specialist squash pests

Journal of Pest Science - Co-occurring herbivorous pests may have shared or divergent responses to plant- and insect- derived cues, creating challenges for effective pest management in...     

Some effects of oral doses of oxytetracycline on growth,survival and disease in Penaeus aztecus

Two size groups of brown shrimp (Penaeus aztecus) were fed a formulated feed containing 0, 100, 1 000 or 5 000 mg of oxytetracycline/kg of feed. Growth and survival were measured after a 3-week drug consumption period. The shrimp were then inoculated with Vibrio alginolyticus, and survival was monitored during the following 24 h.At all three concentrations of oxytetracycline, small shrimp (mean initial wet weight 143.4 mg) consumed approximately one-third the amount of feed consumed by those fed the control diet with no oxytetracycline, yet growth was more rapid with diets containing 100 and 1 000 mg of oxytetracycline/kg of food than with the control diet. Larger shrimp (mean initial wet weight 458.1 mg) receiving oxytetracycline consumed about one-fourth the feed consumed by those on the oxytetracycline-free diet. Some growth inhibition was apparent in these shrimp at all oxytetracycline concentrations. Maximum drug consumption rate, based on actual feed intake, was approximately 1 300 mg oxytetracycline per kg body weight per day for small shrimp, but only 370 mg per kg body weight per day for larger shrimp.All shrimp fed 0, 100 or 1 000 mg of oxytetracycline/kg of feed died within 24 h following inoculation with a standard dose (70% light transmission at 520–540 nm) of Vibrio alginolyticus. All the small shrimp and 70% of the large shrimp fed at the 5 000-mg drug level died, but death generally took place later in the 24-h period than with those fed at the lower drug concentrations. All shrimp fed 5 000 mg oxytetracycline/kg of feed and inoculated with a 1 : 100 dilution of the standard dose of Vibrio alginolyticus survived. All small shrimp and 90% of the large shrimp survived injection of sterile saline.     

Biophysical dynamics of western transition zones: a preliminary synthesis

The nature of the western portions of the biogeographic temperate or transition zones in the North Pacific and North Atlantic is reviewed. The physical transport of nutrients and biomass into them from the Kuroshio and Gulf Stream as well as from the poleward sides are estimated. The conclusion is that the upwelling in the two western boundary currents makes the largest contribution to the nutrient and biomass fluxes into these transition zones. A conservative estimate of the amount of upwelled fluid is derived from absolute velocity sections in the Gulf Stream. The estimate suggests that upwelling into the euphotic zone exceeds 2 × 10⁶ m³ s^–1. This implies that upwelling in these western boundary currents matches or exceeds that in eastern boundary currents such as the California Current. The two western boundary regimes have very different poleward situations. The Oyashio extension flows parallel to the Kuroshio and is a deep current. The North Atlantic Shelf Front flow is to the west where it is ultimately entrained into the edge of the Gulf Stream. There does not seem to be any tendency for this to occur in the Kuroshio. Despite these differences in the northern and western boundaries, the two transition zones are similar with large amplitude meanders, anticyclonic rings and streamers dominating their physical structure. The physical features responsible for the transfer of materials from the boundary current extensions into the transition zones are similar in both systems. Ring formation contributes only ? 10% of the transfer, while ring‐induced streamers contribute 30%. The rest of the transport is contributed by branching of the boundary current front. Both currents have well developed secondary fronts consisting of subtropical surface water pulled into the transition zone. Biologically, the upwelling in both western boundary currents leads to a biomass maximum along the boundary in both secondary producers (copepods) and in small pelagic fish. In the Kuroshio, the latter are the Japanese sardine, Sardinops melanostictus, that spawn in the Kuroshio and then enter the transition zone for the summer and fall months. In the Gulf Stream, the dominate species are menhaden, Brevoortia tyrannus and B. smithi. These species make use of the coastal environments of North America and although the adults spawn in the Gulf Stream, they are not thought to play a major role in the Slope Water, transition zone. The similar differences in the use of the Kuroshio and the Gulf Stream ecosystems occurs in the behaviour of bluefin tuna, squid and other large pelagics. The Gulf Stream system also lacks an equivalent to Pacific saury, Cololabis saira. The biology therefore is at least subtly different, with saury and sardines being replaced by mid‐water fish in the North Atlantic. A fuller comparison of the biology with quantitative methods in both systems should be encouraged.     

The impact of land-claim on macrobenthos,fish and shorebirds on the forth estuary,eastern Scotland

1. The impact of land-claim on the intertidal areas of the Forth estuary, eastern Scotland is described. It is shown that in recent times almost 50% of the intertidal area has been destroyed for a variety of purposes, including agriculture, harbours and industrial development. 2. The loss of infaunal invertebrate biomass and production from the intertidal habitat has been calculated for each part of the estuary, and by summation for the whole estuary. The loss is discussed in relation to the total biomass and production, both intertidally and subtidally, of the estuary. It is shown that proportionately more biomass and production may have been lost than area. 3. The impact of land-claim on estuarine fish is calculated. Land-claim has removed 24% of the natural fish habitats in the Forth estuary, and thereby removed 40% of their food supply. 4. The impact of habitat loss on birds was observed for one area where observations continued throughout a period of land-claim. For individual bird species at Torry Bay, land-claim had consequences ranging from neutral to substantially negative. Significant declines were found for overwintering populations of dunlin and bar-tailed godwit. Comparisons of pre- and post-land-claim bird feeding usage of this area, showed that the impact of land-claim on local bird populations differed between species. The large scale loss of habitat on the Forth seems likely to have reduced the size of some shorebird populations which overwinter on the estuary. 5. It is concluded that when considering the impact of land-claim on estuaries that, as found in some previous studies, a simple consideration of area lost may be inadequate to describe the effects of land-claim, and the consequences for animals living within the estuary may differ considerably amongst themselves and from area to area.     

Biosecurity in Shrimp Farming: Pathogen Exclusion through Use of SPF Stock and Routine Surveillance

Biosecurity, as it is being applied to shrimp aquaculture, may be defined as the practice of exclusion of specific pathogens from cultured aquatic stocks in brood stock facilities, hatcheries, and farms, or from entire regions or countries for the purpose of disease prevention. To make a biosecurity program a functional concept in shrimp aquaculture, the relevant risks should be identified and the appropriate biosecurity measures put into practice to mitigate those risks. Examples of biosecurity measures put into place for this purpose may include such basics as site selection when the intent is to locate a new shrimp culture facility in an area where certain diseases are not enzootic. Standard facilitylfarm operating procedures can be adapted to minimize the risks of disease introduction and spread within a facility through such concepts as pretreatment of all source water, and reduced or “zero” water exchange. Stocking shrimp culture facilities with domesticated shrimp stocks that are free of specific diseases (“Specific Pathogen Free” or SPF) and or with stocks resistant to specific disease agents (SPR) is perhaps the most important single component of a biosecurity program. The example set by the development of domesticated SPF stocks of Litopenaeus vannamei has helped to make biosecure shrimp culture feasible. The development of these and other SPF stocks, and the diagnostic methods to develop and monitor them for specific diseases and disease causing agents, have been milestones in the development of the international shrimp farming industry in recent years, and it has contributed to the species rivaliig Penaeus monodon as the dominant farmed shrimp species. The regular monitoring (surveillance) of shrimp stocks in biosecure culture facilities is a necessary component of a biosecurity plan, as is having in place a contingency plan for disease containment and eradication should a breach occur in the physical and managerial components of a biosecure facility and a targeted disease occur.