Evaluation of Plant and Animal Source Proteins for Replacement of Fish Meal in Practical Diets for the Largemouth Bass Micropterus salmoides

Two feeding trials were conducted with juvenile largemouth bass Micropterus salmoides to evaluate alternative plant and animal source proteins for their ability to replace fish meal in practical diets. The first trial was designed to identify the most promising candidates. The second trial was conducted to evaluate how much of the fish meal could be replaced by those candidates. In Study 1, feed‐trained largemouth bass (3.1 ± 0.7 g) were randomly stocked into 18114‐L glass aquaria at 25 fish per aquarium. Fish were fed one of six experimental diets, each containing approximately 38% crude protein and 10% crude lipid, to apparent satiation twice daily. The control diet (CTL) contained 30% fish meal and 34.5% soybean meal. Diets 2–6 each contained 15% fish meal and at least 34.5% soybean meal with the remainder of the protein made up of either meat and bone meal (MBM), soybean meal (SBM), poultry by‐product meal (PBM), a 50150 mixture of blood meal and corn gluten meal (BM/CG), or 50150 mixture of hydrolyzed feather meal and soybean meal (FMISBM). There were three replicate aquaria per dietary treatment. After 12 wk, there was no significant difference (P > 0.05) among treatments in survival which averaged 92% overall. Only fish fed the PBM or BM/CG diets had average individual weights and feed conversion efficiencies that were not significantly different (P > 0.05) from the control diet (CTL). In Study 2, the formulation of the control diet (CTL) remained the same. Based on their performance in the first trial, PBM and BM/CG were chosen to now replace 75 or 100% of the fish meal. Fish were stocked at an average weight of 6.9 ± 1.7 g. After 11 wk, fish fed diets containing the BM/CG mixture at both levels were significantly smaller (P 5 0.05) than fish fed other diets and at 100% replacement survival was reduced. Fish fed diets containing poultry meal as the primary protein source performed as well as those fed the control diet (CTL). It appears that PBM can completely replace fish meal in diets for juvenile largemouth bass without adverse effects on growth, feed efficiency, or body composition.     

Assessment of EST- and genomic microsatellite markers for variety discrimination and genetic diversity studies in wheat

It is likely that in the near future sequence information from sequencing programmes and EST libraries will generate an abundance of genic microsatellite markers. This study is focused on the assessment of their likely impact and performance vis-à-vis their genomic counterparts. Microsatellites from two sources were used to assess the genetic diversity in 56 old and new varieties of bread wheat on the UK Recommended List. A set of 12 microsatellite markers generated from genomic libraries and 20 expressed sequence tag (EST)-derived microsatellites were used in the study, and the performance of both marker sets assessed. The EST-derived or genic microsatellites delivered fingerprints of superior quality, amplifying clear products with few stutter bands. Diversity levels as revealed bygenic microsatellites are similar to the few published results. The PIC values for the genic markers were generally lower than those calculated for the genomic microsatellites, though advantages of both marker classes for variety identification applications are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Picosecond kinetics of events leading to reaction center bacteriochlorophyll oxidation

A transient absorption spectrum has been measured in Rhodopseudomonas spheroides R26 reaction centers. Its salient features indicate that both the bacteriopheophytin and bacteriochlorophyll chromophores play a role in the excited state. Decay of this state yields a rise time for oxidation of the reaction center complex of about 150 picoseconds.     

Electron tunneling through organic molecules in frozen glasses

Reaction rates extracted from measurements of donor luminescence quenching by randomly dispersed electron acceptors reveal an exponential decay constant of 1.23 per angstrom for electron tunneling through a frozen toluene glass (with a barrier to tunneling of 1.4 electron volts). The decay constant is 1.62 per angstrom (the barrier, 2.6 electron volts) in a frozen 2-methyl-tetrahydrofuran glass. Comparison to decay constants for tunneling across covalently linked xylyl (0.76 per angstrom) and alkyl (1.0 per angstrom) bridges leads to the conclusion that tunneling between solvent molecules separated by approximately 2 angstroms (van der Waals contact) is 20 to 50 times slower than tunneling through a comparable length of a covalently bonded bridge. Our results provide experimental confirmation that covalently bonded pathways can facilitate electron flow through folded polypeptide structures.