An approach to overcoming regeneration recalcitrance in genetic transformation of lupins and other legumes

For pulse legume research to fully capitalise on developments in plant molecular genetics, a high throughput genetic transformation methodology is required. In Western Australia the dominant grain legume is Lupinus angustifolius L. (narrow leafed lupin; NLL). Standard transformation methodology utilising Agrobacterium tumefaciens on wounded NLL seedling shoot apices, in combination with two different herbicide selections (phosphinothricin and glyphosate) is time consuming, inefficient, and produces chimeric shoots that often fail to yield transgenic progeny. Investigation of hygromycin as an alternative selection in combination with expression of green fluorescent protein indicated that transformation of NLL apical cells was not the rate limiting step to achieve transgenic shoot materials. In this research it was identified that despite ready transformation, apical cells were not competent to regenerate. However a deep and broad wounding procedure to expose underlying axillary shoot and vascular cells to Agrobacterium, in combination with delayed selection proved successful, increasing initial explants transformation efficiency up to 75?% and generating axillary shoots with significant transgenic content. Based on knowledge gained from studies of plant chimeras, further subculture of these initial axillary shoots will result in development of low chimeric transgenic materials with heritable content. Furthermore, the method was also tested successfully on other Lupinus species, faba bea and field pea. These results demonstrate that development of a high yielding transformation methodology for pulse legume crops is achievable.     

Nonuniform strain of human soleus aponeurosis-tendon complex during submaximal voluntary contractions in vivo.

The distribution of strain along the soleus aponeurosis tendon was examined during voluntary contractions in vivo. Eight subjects performed cyclic isometric contractions (20 and 40% of maximal voluntary contraction). Displacement and strain in the apparent Achilles tendon and in the aponeurosis were calculated from cine phase-contrast magnetic resonance images acquired with a field of view of 32 cm. The apparent Achilles tendon lengthened 2.8 and 4.7% in 20 and 40% maximal voluntary contraction, respectively. The midregion of the aponeurosis, below the gastrocnemius insertion, lengthened 1.2 and 2.2%, but the distal aponeurosis shortened 2.1 and 2.5%, respectively. There was considerable variation in the three-dimensional anatomy of the aponeurosis and muscle-tendon junction. We suggest that the nonuniformity in aponeurosis strain within an individual was due to the presence of active and passive motor units along the length of the muscle, causing variable force along the measurement site. Force transmission along intrasoleus connective tissue may also be a significant source of nonuniform strain in the aponeurosis.     

Development of a synthetic minimal medium for Listeria monocytogenes

A defined solid and liquid minimal medium, HTM, which contained methionine and cysteine as the sole amino acids, was developed for Listeria monocytogenes. Complex broth-grown L. monocytogenes had to adapt to HTM by inducing amino acid biosyntheis. HTM is the simplest minimal medium available for growth of L. monocytogenes.     

Distribution of current photosynthate in two Guinea grass (Panicum maximum Jacq.) cultivars

In a glasshouse experiment, different tiller categories (main, young primary, and old primary) of two Guinea grass cultivars, Momba?a and Tanzania, were (14)C-labelled to investigate C translocation between tillers. In both cultivars, young primary tillers retained less radiocarbon (79%) than main (86%) and old primary (87%) labelled tillers, suggesting that the photosynthetic capacity of the young tillers exceeds their capacity either to store or use that photosynthate for growth and maintenance. In cv. Tanzania the old primary tillers translocated more photoassimilate to their daughter tillers and to the rest of the plant than cv. Momba?a, suggesting either higher vascular connectivity between tillers or stronger diurnal fluctuations in sink-source balance in Tanzania than Momba?a. For unlabelled tillers, specific activities were almost always higher in roots than in shoots, although total radiocarbon uptake by roots was reduced in younger tillers with low root mass. Where young primary tillers were labelled, the largest single repository of exported photoassimilate was the main tiller roots, indicating that daughter tillers may make an important contribution to the maintenance of older roots on mature tillers.     

Biogeographical distribution and ecological ranges of benthic cyanobacteria in East Antarctic lakes

For the first time, the cyanobacterial diversity from microbial mats in lakes of Eastern Antarctica was investigated using microscopic and molecular approaches. The present study assessed the biogeographical distribution of cyanobacteria in Antarctica. Five samples were taken from four lakes spanning a range of different ecological environments in Larsemann Hills, Vestfold Hills and Rauer Islands to evaluate the influence of lake characteristics on the cyanobacterial diversity. Seventeen morphospecies and 28 16S rRNA gene-based operational taxonomic units belonging to the Oscillatoriales, Nostocales and Chroococcales were identified. The internal transcribed spacer was evaluated to complement the 16S rRNA gene data and showed similar but more clear-cut tendencies. The molecular approach suggested that potential Antarctic endemic species, including a previously undiscovered diversity, are more abundant than has been estimated by morphological methods. Moreover, operational taxonomic units, also found outside Antarctica, were more widespread over the continent than potential endemics. The cyanobacterial diversity of the most saline lakes was found to differ from the others, and correlations between the sampling depth and the cyanobacterial communities can also be drawn. Comparison with database sequences illustrated the ubiquity of several cyanobacterial operational taxonomic units and their remarkable range of tolerance to harsh environmental conditions.     

Iron absorption by wheat roots as a function of distance from the root tip

Summary The apex of the root has been proposed as the site of maximum nutrient uptake, a view based on the accumulation of some ions in the cells of apical meristem⁴. In this study, intact roots were grown across a thin agar sheet containing a radioisotope of iron. Uptake was then measured quantitatively by autoradiography of the dried agar once the root had been removed. Uptake patterns were not observed to occur around the roots of plants that had been supplied with sufficient iron. Around the roots of plants showing severe irondeficiency symptoms, patterns consistently showed depletion of iron in the agar starting at 3.5 cm behind the tip and continuing to the point of complete suberization of the endodermis. No uptake was observed around the apical 3.5 cm of the root, although the highest concentrations within the root have centered on the apex. Agronomy Paper No.869, New York State College of Agriculture.     

Comparison of 3T MR scanners in regional cartilage-thickness analysis in osteoarthritis: a cross-sectional multicenter,multivendor study

Introduction  

Cartilage thickness from MR images has been identified as a possible biomarker in knee osteoarthritis (OA) research. The ability to acquire MR data at multiple centers by using different vendors' scanners would facilitate patient recruitment and shorten the duration of OA trials. Several vendors manufacture 3T MR scanners, including Siemens, Philips Medical Systems, and GE Healthcare. This study investigates whether quantitative MR assessments of cartilage morphology are comparable between scanners of three different vendors.     

Recruitment of the Rhesus soleus and medial gastrocnemius before, during and after spaceflight

Electromyograms were recorded from the soleus and medial gastrocnemius muscles and tendon force from the medial gastrocnemius muscle of 2 juvenile Rhesus monkeys before, during and after Cosmos flight 2229 and of ground control animals. Recording sessions were made while the Rhesus were performing a foot pedal motor task. Preflight testing indicated normal patterns of recruitment between the soleus and medial gastrocnemius, i.e. a higher level of recruitment of the soleus compared to the medial gastrocnemius during the task. Recording began two days into the spaceflight and showed that the media gastrocnemius was recruited preferentially over the soleus. This observation persisted throughout the flight and for the 2 week period of postflight testing. These data indicate a significant change in the relative recruitment of slow and fast extensor muscles under microgravity conditions. The appearance of clonic-like activity in one muscle of each Rhesus during flight further suggests a reorganization in the neuromotor system in a microgravity environment.