Scanning Probe Microscopes—Applications in Cereal Science

Scanning probe microscopes (SPMs) are a family of related instruments which can produce high-resolution images of structures at the molecular and atomic levels. Their main impact so far has been in surface science, but they also have tremendous potential for the study of biomolecules. In this article we will briefly introduce the properties and principles of these instruments, and then discuss a range of preliminary studies from our laboratories in relation to future applications in cereal science.     

Implications of feeding frequency,prey size and condition,and intraspecific competition for the commercial aquaculture of the nudibranch Berghia stephanieae

Marine ornamental aquaculture is a growing industry. Although most species are cultured for aesthetic purposes, there is increasing interest in organisms that provide functional services. Nudibranchs provide an example in which they act as biological controls by consuming aquaria pests. Berghia stephanieae is a commercially relevant nudibranch that feeds on Exaiptasia anemones, which overgrow sessile invertebrates. However, information pertaining to B. stephanieae feeding habits remains unaddressed. Therefore, this study investigated the following: (a) the effect of feeding frequency on fecundity, (b) optimum prey size, (c) the ability to feed on prey fragments, and (d) the influence of intraspecific competition. Distinct feeding frequencies were tested and embryos produced were quantified; growth of nudibranchs offered different anemone sizes was measured; whole and fragmented anemones were offered, with preference recorded; and growth and mortality of juvenile nudibranchs were recorded in the absence and presence of adult conspecifics. Results show that feeding daily produced the highest number of embryos. Juveniles fed on medium-sized anemones showed the highest growth rate. Smaller juveniles were unable to feed on whole anemones and preferred fragmented anemones. Juvenile growth and survival decreased in the presence of adults. To maximize production, breeders must feed broodstock daily, provide medium-sized anemones or fragments, and segregate juveniles from adults.     

A comparison of catch rates of artificial lures from an automated handline fishery at Shetland,UK

Automated handlining (jig fishing) has recently been trialled in waters around Shetland, UK. Although different types and colours of artificial lures are commercially available there is a paucity of information available on the effects of either lure design or lure colour on resulting catches. We compared the catch rates of (1) five colours of rubber eel tube lures; and (2) five different designs of artificial lure commonly used in handline fisheries. Lure colour did not significantly affect catches of pollack (Pollachius pollachius), saithe (Pollachius virens), cod (Gadus morhua), ling (Molva molva) or tusk (Brosme brosme). Cod showed a preference for lower hooks on the six hooks per reel set-up when lures were black and pollack showed a preference for lower hooks when the lures were blue. There were no significant differences in catches of saithe, cod, ling or tusk between the five lure types. However, catches of pollack on a novel ‘sonar’ lure were lower than on other lures. No evidence of a preference for any hook position on the reels was found with any of the lure types.     

Apparent digestibility of soybean coproducts in extruded diets for Nile Tilapia,Oreochromis niloticus

Soybean coproducts are important protein sources in aquaculture because of their amino acid profile. Tilapia can be reared on soybean coproducts as the only source of dietary protein without compromising growth. This study estimated apparent digestibility coefficients for five soybean coproducts for juvenile Nile tilapia, Oreochromis niloticus, fed with extruded diets. A reference diet and test diets consisting of 70% reference diet and 30% coproduct ingredient were formulated, along with 5.0 g kg^?1 chromic oxide (Cr₂O₃) as a marker. Apparent digestibility coefficients (ADC) for dry matter (ADCDM), gross energy (ADCGE) and crude protein (ADCCP) for soybean coproducts were estimated as 84.2–88.4%, 86.9–91.1% and 96.8–97.9%, respectively. ADCDM and ADCCP values did not vary among the ingredients, but low‐protein soybean meal exhibited lower ADCGE values than did soybean protein concentrate. ADCs of all amino acids were >95%, and mean ADCs for amino acids were similar to the values observed for ADCCP. Soybean coproducts had good nutritional value in extruded diets fed to tilapia. Methionine, histidine and valine were the limiting amino acids in all evaluated ingredients.     

Compressive Strength of Wheat Endosperm: Comparison of Endosperm Bricks to the Single Kernel Characterization System

The three major classes of endosperm texture (grain hardness) of soft and hard common, and durum wheat represent and define one of the leading determinants of the milling and end‐use quality of wheat. Although these three genetic classes are directly related to the Hardness locus and puroindoline gene function, much less is known about the kernel‐to‐kernel variation within pure varietal grain lots. Measurement of this variation is of considerable interest. The objective of this research was to compare kernel texture as determined by compression failure testing using endosperm bricks with results of whole‐kernel hardness obtained with the Single Kernel Characterization System 4100 hardness index (SKCS HI). In general terms, the variation obtained with the SKCS HI was of similar magnitude to that obtained using failure strain and failure energy of endosperm brick compression. Objective comparisons included frequency distribution plots, normalized frequency distribution plots, ANOVA model R², and coefficients of variation. Results indicated that compression testing and SKCS HI similarly captured the main features of texture classes but also reflected notable differences in texture properties among and within soft, hard, and durum classes. Neither brick compression testing nor the SKCS HI may be reasonably expected to correctly classify all individual kernels as to genetic texture class. However, modest improvements in correct classification rate or, more importantly, better classification related to end‐use quality may still be achievable.     

Phosphorus-induced zinc deficiency in wheat pot-grown on noncalcareous and calcareous soils of different properties

High levels of phosphorus (P) often induce zinc (Zn) deficiency in plants grown on Zn-poor soils. We investigated P-induced Zn deficiency in durum wheat (Triticum durum L. ‘Carpio’) grown on 16 noncalcareous and 31 calcareous soils differing in levels of available (Olsen) P and available (diethylenetriaminepentaacetic acid (DTPA)-extractable) Zn using micropots. A completely randomized factorial design with two levels of P (0 and 40 mg P kg^?1 soil) and Zn (0 and 3 mg Zn kg^?1 soil), i.e. four treatments (‘control’, + P, + Zn, and + PZn), were used. Grain yield of control plants depended mainly on the Olsen P level. Phosphorus had a negative effect on yield in 6 soils with Olsen P/Zn_DTPA > 25, and Zn a positive one in 5 soils with Olsen P/Zn_DTPA > 50; and the + PZn treatment generally resulted in the highest yield. Grain Zn concentration of control plants was negatively correlated with growth and Olsen P. Calcareous soils were less sensitive to P-induced Zn deficiency than noncalcareous soils because phosphate is sorbed by calcite rather than being co-adsorbed with Zn on the Fe oxides. Co-application of P and Zn to soil at low and application of Zn at high Olsen P ensured both maximum yield and grain Zn bioavailability.