The development of the axial muscles was investigated in Atlantic herring Clupea harengus from 2 spring-spawning (Clyde and Blackwater) and 1 autumn-spawning (Manx) populations in 2 successive years. The results indicate significant developmental differences between stocks. Myofibril synthesis and the development of acetylcholinesterase activity at the neuromuscular junctions occurred later with respect to embryonic stage at 5°C than at 8 and 12°C in Clyde herring, with much less pronounced differences between temperatures for the other populations. In a second series of experiments, Clyde herring were incubated at 5 and 12°C until shortly after hatching, and then reared at ambient temperature in triplicate tanks. The 5°C group had a faster growth rate than the 12°C group with respect to effective day-degrees from hatch. However, flexion of the notochord and the development of the dorsal and anal fin ray muscles occurred at shorter body lengths in the 12 than 5°C groups. The maximum escape velocity of larvae during fast-starts was determined using a high-speed video. Over the size range 11.2 to 18.5 mm total length, the adjusted mean maximum velocity was 24% higher in larvae hatched from 12 than 5°C eggs. Cruising swimming behaviour also differed between groups with the 12°C larvae showing reduced yaw relative to the 5°C larvae, indicating a more developmentally advanced sub-carangiform style of locomotion.

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SUMMARY Seasonal cooling can modify the thermal preferenda of ectothermic vertebrates and elicit a variety of physiological responses ranging from winter dormancy to an acclimation response that partially compensates for the effects of low temperature on activity. Partial compensation of activity levels is particularly common in aquatic species for which seasonal temperature changes provide a stable cue for initiating the response. Thermal plasticity of locomotory performance has evolved independently on numerous occasions, and there is considerable phylogenetic diversity with respect to the mechanisms at the physiological and molecular levels. In teleosts,neuromuscular variables that can be modified include the duration of motor nerve stimulation, muscle activation and relaxation times, maximum force and unloaded shortening velocity (Vmax), although not all are modified in every species. Thermal plasticity in Vmax has been associated with changes in myosin ATPase activity and myosin heavy chain(MyHC) composition and/or with a change in the ratio of myosin light chain isoforms. In common carp (Cyprinus carpio), there are continuous changes in phenotype with acclimation temperature at lower levels of organisation, such as MyHC composition and Vmax, but a distinct threshold for an effect in terms of locomotory performance. Thus,there is no simple relationship between whole-animal performance and muscle phenotype. The nature and magnitude of temperature acclimation responses also vary during ontogeny. For example, common carp acquire the ability to modify MyHC composition with changes in acclimation temperature during the juvenile stage. In contrast, the thermal plasticity of swimming performance observed in tadpoles of the frog Limnodynastes peronii is lost in the terrestrial adult stage. Although it is often assumed that the adjustments in locomotory performance associated with temperature acclimation enhance fitness, this has rarely been tested experimentally. Truly integrative studies of temperature acclimation are scarce, and few studies have considered both sensory and motor function in evaluating behavioural responses. Developmental plasticity is a special case of a temperature acclimation response that can lead to temporary or permanent changes in morphology and/or physiological characteristics that affect locomotory performance.

SUMMARY Motor units are the functional units of muscle contraction in vertebrates. Each motor unit comprises muscle fibres of a particular fibre type and can be considered as fast or slow depending on its fibre-type composition. Motor units are typically recruited in a set order, from slow to fast, in response to the force requirements from the muscle. The anatomical separation of fast and slow muscle in fish permits direct recordings from these two fibre types. The frequency spectra from different slow and fast myotomal muscles were measured in the rainbow trout Oncorhynchus mykiss. These two muscle fibre types generated distinct low and high myoelectric frequency bands. The cat paw-shake is an activity that recruits mainly fast muscle. This study showed that the myoelectric signal from the medial gastrocnemius of the cat was concentrated in a high frequency band during paw-shake behaviour. During slow walking, the slow motor units of the medial gastrocnemius are also recruited, and this appeared as increased muscle activity within a low frequency band. Therefore, high and low frequency bands could be distinguished in the myoelectric signals from the cat medial gastrocnemius and probably corresponded, respectively, to fast and slow motor unit recruitment. Myoelectric signals are resolved into time/frequency space using wavelets to demonstrate how patterns of motor unit recruitment can be determined for a range of locomotor activities.

Muscle growth characteristics were investigated in a herring Clupea harengus L. population in the Blackwater estuary, Essex, England, between May and July 1998. Larval thermal histories were reconstructed using internally logging temperature recorders deployed within the estuary over the spawning season. The hatch dates of larvae were estimated using otolith microincrement analysis. Larvae were split into 3 groups; those developing from eggs laid early in the season when temperatures were low (6.4 to 9.8°C), those developing mid-season (8.3 to 12.5°C), and those developing late (10.9 to 15.6°C). The number and size distribution of red and white myotomal muscle fibres varied between larvae from early-and mid-spawners in relation to estimated age. At approximately 60 d, the cross-sectional area of white muscle in mid-season larvae was 145% greater than in earlyseason larvae of an equivalent age because of 60% more muscle fibres and a 22% greater mean fibre diameter. The number and average diameter of red muscle fibres were proportional to body length, with no differences between the groups of larvae. However, for a given length, the average diameter of the white muscle fibres was significantly greater in mid-than early-season larvae. Muscle cellularity therefore varied for cohorts of larvae hatching at different times during the spawning season.

Combined immunofluorescence (IF) and fluorescence in situ hybridization (FISH) on formalin-fixed, paraffin-embedded tissue sections were used to examine lymph node tissue from two patients diagnosed with T-cell lymphoma with Epstein-Barr virus (EBV)-infected B-cell blasts. The majority of cells within the samples comprised T-cells staining positively for CD3. In addition, both patients had a population of large pleiomorphic cells that were positive for the B-cell marker CD20 and for EBV LMP-1. Standard PCR clonality testing of the nodes revealed both immunoglobulin heavy chain (IGH) and T-cell receptor (TCR) clonal rearrangements in one patient, although in the other case monoclonality was demonstrated only for TCRG. Cytogenetics of cultured lymphocytes from nodal tissue revealed two apparently unrelated abnormal clones in both patients. Combined IF and FISH revealed that these phenomena reflected two abnormal populations of B- and T-cells rather than reactive B-cell hyperplasia or biphenotypic evolution from a common ancestral lymphoma. True B-cell malignancy probably emerged within a preexisting but unrelated T-cell lymphoma. This is the first study to relate the phenotype of the abnormal cells in such cases to specific clonal populations of cells, and it demonstrates a method that may easily be introduced into a diagnostic cytogenetics laboratory with access to standard pathology laboratory resources.

The vancomycin class of antibiotics is regarded as the last line of defence against Gram-positive bacteria. The compounds used clinically are very complex organic molecules and are made by fermentation. The biosynthesis of these is complex and fascinating. Its study holds out the prospect of utilizing genetic engineering of the enzymes in the pathway in order to produce novel vancomycin analogues. In part, this requires detailed structural insight into substrate specificity as well as the enzyme mechanism. The crystallization of one of the enzymes in the chloroeremomycin biosynthetic pathway (a member of the vancomycin family), dTDP-3-amino-4-keto 2,3,6-trideoxy-3-C-methyl-glucose-5-epimerase (EvaD) from Amycolatopsis orientalis, is reported here. The protein is fourth in the pathway which makes a carbohydrate essential for the activity of chloroeremomycin. The crystals of EvaD diffract to 1.5 A and have unit-cell parameters a = 98.6, b = 72.0, c = 57.1 A with space group P2(1)2(1)2. Data to this resolution were collected at the European Synchrotron Radiation Facility.