Identifications of two different mechanisms for sorghum midge resistance through QTL mapping

Sorghum midge is the one of the most damaging insect pests of grain sorghum production worldwide. At least three different mechanisms are involved in midge resistance. The genetic bases of these mechanisms, however, are poorly understood. In this study, for the first time, quantitative trait loci associated with two of the mechanisms of midge resistance, antixenosis and antibiosis, were identified in an RI (recombinant inbred) population from the cross of sorghum lines ICSV745 x 90562. Two genetic regions located on separate linkage groups were found to be associated with antixenosis and explained 12% and 15%, respectively, of the total variation in egg numbers/spikelet laid in a cage experiment. One region was significantly associated with antibiosis and explained 34.5% of the variation of the difference of egg and pupal counts in the RI population. The identification of genes for different mechanisms of midge resistance will be particularly useful for exploring new sources of midge resistance and for gene pyramiding of different mechanisms for increased security in sorghum breeding through marker-assisted selection.

Methods of outbreak investigation in the "era of bacteriology" 1880-1920

The advent of bacteriological methods in the later 19th century has been seen, on the examples of America and Germany, to have been followed by a new laboratory-based, contact-tracing method of investigating outbreaks of epidemic disease. In Britain, however, this new approach never took firm root, and practising epidemiologists continued to follow an observational and deductive tradition in field investigations, rejecting any primary dependence on bacteriological methods. Alongside this persistent observational practice, there emerged a new statistical approach, based in Pearsonian biometrics, which allied itself with experimental laboratory techniques to develop a more systematic, theoretical trajectory for explaining disease outbreaks in the years after World War I.

Non-spatial acquisition and retention deficits following small excitotoxic lesions within the hippocampus in monkeys

Marmoset monkeys with excitotoxic lesions confined to cornu ammonis subfields 1-3, subiculum and pre-subiculum, but sparing the entorhinal cortex, were impaired on retention and learning of conditional object-choice discriminations. For each of these discriminations, the monkeys were required to choose one of two objects depending on which of two patterned backgrounds was used on each trial. Two styles of order of trial presentation were used: 'random' presentation which maximised the degree of interference between trials, and 'runs' presentation which was intended to encourage the monkeys to learn each component of the discrimination separately. Before surgery monkeys found the discriminations more difficult to learn when the trials were presented in the 'runs' style than when presented in the 'random' style suggesting that the task is best learnt by applying a conditional rule. After surgery a significant 'group x style' interaction indicated that the 'runs' style was especially difficult for the lesioned monkeys. From these results we suggest that the hippocampus is involved in learning about and remembering non-spatial, conditional relations between objects.

A degeneration-based hypothesis for interpreting fibrillar changes in the osteoarthritic cartilage matrix

The collagen fibrillar architectures in the general matrix of cartilage slices removed from both normal and osteoarthritic femoral heads were examined by both differential interference light microscopy and scanning electron microscopy. Whereas the normal general matrix contained a finely differentiated pseudo-random weave of fibrils developed from an interconnected array of radial elements, the osteoarthritic general matrix was characterised by the presence of structurally distinct regions consisting of strongly aligned radial bundles of fibrils and associated intense tangles or 'knotted' features. Simple structural models were developed to explore possible transformation structures based on two different types of interconnectivity in the three-dimensional fibrillar network. These models support the hypothesis that the distinctive ultrastructural features of the osteoarthritic general matrix can develop as a consequence of largely passive degradative changes occurring in the fibrillar weave originally present in the normal matrix. This could, in principle, occur independently of any new structure that might develop as a consequence of any upregulation of collagen associated with the osteoarthritic process.

Bloch Analysis of Photonic Lattices that Incorporate Vertical Cavity Surface-Emitting Laser Arrays

We analyzed one-dimensional photonic lattices that incorporate mirror-modulated vertical cavity surface-emitting laser arrays utilizing the Bloch formalism. First, infinitely long arrays are considered. The in-phase mode (with a main central lobe at the far field) and antiphase mode (with two main symmetrically-located lobes at the far-field) are examined. A comparison of the modal losses of the in-phase and the antiphase modes, resulted in the discovery of regimes in which the in-phase mode is dominant. Considering lattices of finite length, we compared the results of the Bloch model to the exact solutions. It is shown that the boundary conditions in these lattices select a specific mode from the continuous spectrum in the infinite case. Consequently, the lattice's length affects the eigenmodes and the corresponding eigenvalues in a periodic manner.

Effect of spatial hole burning on injection-locked vertical-cavity surface-emitting laser arrays

Injection locking of vertical-cavity surface-emitting laser arrays is analyzed at steady state, including the effect of spatial hole burning. A free-running laser array (i.e., without injection), that operates well-above threshold, can exhibit multimode oscillations. Consequently, each of the free-running modes (at different frequencies) needs a different locking injection power. For low pump levels, just above threshold, the array is single mode and, as expected, the results bear a close resemblance to those of the average gain analysis, which ignores spatial hole burning.

Exotic myiasis with Lund's fly (Cordylobia rodhaini)

After a four-week holiday in East Africa, a woman was diagnosed with furuncular myiasis: a third-instar larva of the fly Cordylobia rodhaini (Lund's fly) was found in a skin lesion. This is the first report of exotic myiasis and importation of this species of fly into Australia, and reflects the increasing risk of introducing exotic flies of public health and veterinary importance to Australia.

Characteristics of grating-assisted couplers

Characteristics of grating-assisted coupling between two parallel waveguides are analyzed. The influence of the grating parameters, such as groove depth, duty cycle, and refractive indices is considered. Chirped and parallel gratings as well as gratings with sinusoidal envelope periodicity are also addressed. The analysis is based on a unified coupled-mode formalism, with the transfer-matrix method as a general solution technique. It is shown how to modify the grating parameters to provide a specific spectral response (reflectivity and transmission coefficients). As an example, two parallel gratings are used to obtain a similar response to a single grating of double length. The location of the grating between the two waveguides as well as the light-wave injection direction are very important. The presented methods and effects may be useful for design and analysis in the fields of optical communications, sensing, and processing.

High-power 980-nm pump laser modules for erbium-doped fiber amplifiers

High-power fiber-coupled pump modules with an emission wavelength of 980 nm and output powers in excess of 200 mW, as measured at the fiber end, have been fabricated. Laser-to-fiber coupling efficiencies in excess of 77% are observed to be in excellent agreement with a mathematical model. Also, the output power stability of these modules has been monitored during severe temperature cycling, and the relative power variation was less than 4% for all the tested modules.

Food, hygiene, and the laboratory. A short history of food poisoning in Britain, circa 1850-1950

Public health concern with food safety and food poisoning emerged in Britain in the 1880s following the first indication that acute gastric illness was caused by a specific organism. Although incidents were for many years only sparsely reported, the central medical department and its scientists were anxious to extend their knowledge of the incidence, specific causal organisms, and epidemiology of the illness. This paper argues for a widespread incidence of food poisoning in Britain in the nineteenth century and traces the social economic, and hygienic contexts within which it occurred. As deadlier infections retreated, food poisoning became an increasing concern of local and national health authorities, who sought both to raise public awareness of the condition as illness, and to regulate and improve food handling practices. Notification of cases was begun in 1939, and this, together with social changes during and after the Second World War, produced an escalating spiral of reported incidents which still continues. This trend, it is argued, is essentially an artefact, whose significance is reduced if considered in its broader historical context.

Neomycin inhibition of intestinal putrescine uptake

Enhanced intestinal polyamine uptake was confirmed in tumor-bearing rats. Intestinal brush border membrane from rats bearing a Mat Lylu prostatic adenocarcinoma exhibited 46% increase in 14C putrescine uptake. After oral ingestion of 14C putrescine, radioactivity was recovered in the tumor (about 2% of total amount ingested) and was enhanced in liver and in blood. Radioactivity in tumor-bearing rat red blood cells (RBC) was two-fold higher than in healthy control rats indicating that polyamines originating in food can contribute to the enhancement of RBC polyamine levels observed after tumor development. Neomycin-induced inhibition of intestinal putrescine absorption was observed both in vitro and in vivo. In intestinal brush border membrane 500 microM neomycin inhibited putrescine uptake by 30-35%. In vivo, a single dose of neomycin given per os modified final 14C radioactivity distribution: a) The final accumulation of radioactivity in the tumor was reduced by 50%. b) Neomycin treatment lowered the high levels of radioactivity in the blood of cancerous animals. This reduction was correlated with a significant reduction of RBC polyamine levels. c) Radioactivity accumulated in the colon after neomycin treatment in both healthy and cancerous rats. The role of neomycin as an intestinal antibiotic and the presently described effect of this drug on intestinal polyamine uptake emphasize the importance of neomycin in polyamine deprivation treatments.

Oblique incidence of gaussian beams on waveguide gratings with the four-wave coupled-mode theory

Diffraction of obliquely incident Gaussian beams on waveguide gratings with infinitely long grooves is described. The analysis is based on the angular spectrum of the beam and on the grating response derived from the four-wave coupled-mode theory, which simultaneously considers all four (approximately) synchronous waves. Results concerning the shapes of the emerging beams and their directions, the power content, and the possibility of beam splitting could differ significantly from those obtained by means of two-wave coupling. The analysis method is general and can be performed on many kinds of realistic beam shapes and applications.

Heterogeneity of eel thyrotropin beta mRNAs is due to a minisatellite in the 3' untranslated region of the gene

The aim of this study was to determine the causes of the high heterogeneity, in the number and the length, of the thyrotropin (TSH) beta mRNA in the European eel. Northern blot analysis showed that removal of the poly(A) tail did not affect this heterogeneity. PCR amplification on reverse-transcribed pituitary RNAs (RT) showed the main source of heterogeneity to be a highly variable region in the 3' untranslated region (UTR). PCR amplification of the 3' UTR from RTs and genomic DNAs demonstrated that the high variability reflected polymorphism within the eel TSH beta gene. Isolation and sequencing of 3' UTR amplification fragments showed that the variable region comprised more or less exact repetitions of a 26-42-bp fragment. The number of repetitions varied from one allele to another. This variable region could be characterized as a minisatellite. In conclusion, instability of a minisatellite in the 3' UTR of the TSH beta gene generated the multiple and widely differing TSH beta mRNAs.

The prediction of preeclampsia: reassessment of clinical value of increased plasma levels of fibronectin

OBJECTIVE

To determine whether assessment of plasma fibronectin in primigravidae could predict the pregnant women expected to become preeclamptic.

METHODS

We performed a prospective blinded analysis of 156 apparently normotensive primigravidae in an outpatient clinic. Blood samples were taken at 6 week intervals from the 18th week and immediately after delivery or at the onset of preeclampsia. Plasma fibronectin was evaluated by ELISA. Evolution with gestational age was studied using regression curves.

RESULTS

We had 148 normal primigravidae (592 determinations). In three women, increased fibronectin anticipated preeclampsia by 3-4 weeks. Five women showed high levels only at the onset of preeclampsia. Sensitivity, specificity, positive and negative predictive values of increased fibronectin levels were 37.5% (95% CI=3.3-71.7), 96.6% (95% CI=93.7-99.6), 37.5% (95% CI=3.3-71.7) and 96.6% (95% CI=93.7-99.6), respectively.

CONCLUSIONS

This study shows that plasma fibronectin levels could represent a specific marker for preeclampsia. Its sensitivity has to be improved but its high negative predictive value strongly argues against the development of preeclampsia within the next 4 weeks after the blood sampling.

Effects of genotype and environment on architecture and flowering time of indeterminate Andean lupins (Lupinus mutabilis Sweet)

Plant structure was shown to limit the seed yield of Lupinus mutabilis through low dry matter production. The genetic and environmental variations of architectural and phenological traits of indeterminate Andean lupin were evaluated. Twelve genotypes were sown at 6–8 dates at 5 locations in Europe in 1994 and 1995. Wide variation was observed for phenological and architectural characters. The variation in the number of mainstem leaves was partly explained by the temperature. The mainstem height and flowering date were related to the number of mainstem leaves but flowering time was also affected independently by the enviromental conditions. The mainstem structure determined the potential number of first-order branches through the number of axillary buds. The actual number of branches was also determined by the prevailing environmental conditions during branch growth. The number of leaves on the second first-order branch was less susceptible to the environmental conditions than the number of leaves on the mainstem. Heritabilities were high for all characters except for the number of leaves on the second first-order branch, and the interactions between genotype and environmental condition were low. Breeding for architecture modification would thus be possible in L. mutabilis.

Reflection intensity optical fiber sensors for the mid-infrared

Two kinds of reflection intensity sensor made of chalcogenide glass fiber for the mid-IR region are demonstrated. One is a double-fiber reflection sensor based on two tied fibers with a gold-coated hollow metal waveguide connected to the far end of the fibers. The other is a single-fiber reflection sensor based on contact couplers. These reflectance sensors were coupled to a Fourier-transform IR spectrometer by a unique accessory based on nonimaging concentrators. This setup was built to measure absorption spectra of a polymer coating of an aluminum can and a sheet of drafting paper. A theoretical model treating the ratio between the signal from the target and the background is introduced. This model was helpful in deriving the sensitivity characteristics of the sensors from experimental absorption peak heights. Hence, the absorption peaks heights that we obtained using a single-fiber reflection sensor with a symmetric coupler were nearly 50% relative to those obtained with a double-fiber reflection sensor.