Expression of Drosophila mushroom body mutations in alternative genetic backgrounds: a case study of the mushroom body miniature gene (mbm).

Mutations in 12 genes regulating Drosophila melanogaster mushroom body (MB) development were each studied in two genetic backgrounds. In all cases, brain structure was qualitatively or quantitatively different after replacement of the "original" genetic background with that of the Canton Special wild-type strain. The mushroom body miniature gene (mbm) was investigated in detail. mbm supports the maintenance of MB Kenyon cell fibers in third instar larvae and their regrowth during metamorphosis. Adult mbm1 mutant females are lacking many or most Kenyon cell fibers and are impaired in MB-mediated associative odor learning. We show here that structural defects in mbm1 are apparent only in combination with an X-linked, dosage-dependent modifier (or modifiers). In the Canton Special genetic background, the mbm1 anatomical phenotype is suppressed, and MBs develop to a normal size. However, the olfactory learning phenotype is not fully restored, suggesting that submicroscopic defects persist in the MBs. Mutant mbm1 flies with full-sized MBs have normal retention but show a specific acquisition deficit that cannot be attributed to reductions in odor avoidance, shock reactivity, or locomotor behavior. We propose that polymorphic gene interactions (in addition to ontogenetic factors) determine MB size and, concomitantly, the ability to recognize and learn odors.

Radioimmunotherapy with a 64Cu-labeled monoclonal antibody: a comparison with 67Cu.

67Cu (t1/2 = 62 h) has demonstrated potential as a radionuclide for radioimmunotherapy, but limited availability severely restricts its widespread use. 64Cu (t1/2 = 12.8 h) has been shown to have comparable effectiveness in vitro and in vivo. The present study was undertaken to examine the therapeutic potential of 64Cu- and 67Cu-bromoacetamidobenzyl-1,4,8,11-tetraazacyclotetradeca ne-N, N',N",N"'-tetraacetic acid (BAT)-2-iminothiolane (2IT)-1A3 (1A3 is a mouse anti-human colorectal cancer mAb) for treatment of GW39 human colon carcinoma carried in hamster thighs. Hamsters were injected with 64Cu- or 67Cu-BAT-2IT-1A3 or Cu-labeled nonspecific IgG (MOPC) or saline. Hamsters were killed 6-7 months after therapy or when tumors were > or = 10 g. Of the hamsters with small tumors (mean weight 0.43 +/- 0.25 g), 87.5% were disease-free 7 months after treatment with 2 mCi (1 Ci = 37 GBq) of 64Cu-BAT-2IT-1A3 or 0.4 MCi of 67Cu-BAT-2IT-1A3. The mean tumor doses at these activities of 64Cu- and 67Cu-BAT-2IT-1A3 were 586 and 1269 rad (1 rad = 0.01 Gy), respectively. In contrast, 76% of hamsters treated with 2 mCi of 64Cu-BAT-2IT-MOPC or 0.4 mCi of 67Cu-BAT-2IT-MOPC had to be killed before 6 months because of tumor regrowth. When hamsters with larger tumors (mean weight 0.66 +/- 0.11 g) were treated with 64Cu- or 67Cu-BAT-2IT-1A3, survival was extended compared with controls, but only one animal remained tumor-free to 6 months. These results demonstrate that 64Cu- and 67Cu-BAT-2IT-1A3 given in a single administered dose can eradicate small tumors without significant host toxicity, but additional strategies to deliver higher tumor doses will be needed for larger tumors.

Intrinsic changes in developing retinal neurons result in regenerative failure of their axons.

The failure of mature mammalian central nervous system axons to regenerate after transection is usually attributed to influences of the extraneuronal milieu. Using explant cocultures of retina and midbrain tectum from hamsters, we have found evidence that these influences account for failure of regrowth of only a small minority of retinal axons. For most of the axons, there is a programmed loss of ability to elongate in the central nervous system. We show that there is a precipitous decline in the ability of retinal axons to reinnervate tectal targets when the retina is derived from pups on or after postnatal day 2, even when the target is embryonic. By contrast, embryonic retinal axons can regrow into tectum of any age, overcoming growth-inhibiting influences of glial factors.

Platelet-derived growth factor BB induces functional vascular anastomoses in vivo.

Neovascularization that generates collateral blood flow can limit the extent of tissue damage after acute ischemia caused by occlusion of the primary blood supply. The neovascular response stimulated by the BB homodimeric form of recombinant platelet-derived growth factor (PDGF-BB) was evaluated for its capacity to protect tissue from necrosis in a rat skin flap model of acutely induced ischemia. Complete survival of the tissue ensued, when the original nutritive blood supply was occluded, as early as 5 days after local PDGF-BB application, and the presence of a patent vasculature was evident compared to control flaps. To further evaluate the vascular regenerative response, PDGF-BB was injected into the muscle/connective tissue bed between the separated ends of a divided femoral artery in rats. A patent new vessel that functionally reconnected the ends of the divided artery within the original 3- to 4-mm gap was regenerated 3 weeks later in all PDGF-BB-treated limbs. In contrast, none of the paired control limbs, which received vehicle with an inactive variant of PDGF-BB, had vessel regrowth (P < 0.001). The absence of a sustained inflammatory response and granulation tissue suggests locally delivered PDGF-BB may directly stimulate the angiogenic phenotype in endothelial cells. These findings indicate that PDGF-BB can generate functional new blood vessels and nonsurgically anastomose severed vessels in vivo. This study supports the possibility of a therapeutic modality for the salvage of ischemic tissue through exogenous cytokine-induced vascular reconnection.

The weediness of wild plants: molecular analysis of genes influencing dispersal and persistence of johnsongrass, Sorghum halepense (L.) Pers.

Many major weeds rely upon vegetative dispersal by rhizomes and seed dispersal by "shattering" of the mature inflorescence. We report molecular analysis of these traits in a cross between cultivated and wild species of Sorghum that are the probable progenitors of the major weed "johnsongrass." By restriction fragment length polymorphism mapping, variation in the number of rhizomes producing above-ground shoots was associated with three quantitative trait loci (QTLs). Variation in regrowth (ratooning) after overwintering was associated with QTLs accounting for additional rhizomatous growth and with QTLs influencing tillering. Vegetative buds that become rhizomes are similar to those that become tillers--one QTL appears to influence the number of such vegetative buds available, and additional independent genes determine whether individual buds differentiate into tillers or rhizomes. DNA markers described herein facilitate cloning of genes associated with weediness, comparative study of rhizomatousness in other Poaceae, and assessment of gene flow between cultivated and weedy sorghums--a risk that constrains improvement of sorghum through biotechnology. Cloning of "weediness" genes may create opportunities for plant growth regulation, in suppressing propagation of weeds and enhancing productivity of major forage, turf, and "ratoon" crops.

Bridging grafts and transient nerve growth factor infusions promote long-term central nervous system neuronal rescue and partial functional recovery.

Grafts of favorable axonal growth substrates were combined with transient nerve growth factor (NGF) infusions to promote morphological and functional recovery in the adult rat brain after lesions of the septohippocampal projection. Long-term septal cholinergic neuronal rescue and partial hippocampal reinnervation were achieved, resulting in partial functional recovery on a simple task assessing habituation but not on a more complex task assessing spatial reference memory. Control animals that received transient NGF infusions without axonal-growth-promoting grafts lacked behavioral recovery but also showed long-term septal neuronal rescue. These findings indicate that (i) partial recovery from central nervous system injury can be induced by both preventing host neuronal loss and promoting host axonal regrowth and (ii) long-term neuronal loss can be prevented with transient NGF infusions.

Dynamic Precision Phenotyping Reveals Mechanism of Crop Tolerance to Root Herbivory

The western corn rootworm (WCR) is a major pest of maize that is well adapted to most crop management strategies. Breeding for tolerance is a promising alternative to combat WCR, but is currently constrained by a lack of physiological understanding and phenotyping tools. We developed dynamic precision phenotyping approaches using carbon-11 with positron emission tomography, root autoradiography and radiometabolite flux analysis to understand maize tolerance to WCR. Our results reveal that WCR attack induces specific patterns of lateral root growth which are associated with a shift in auxin biosynthesis from indole-3-pyruvic acid to indole-3-acetonitrile. WCR attack also increases transport of newly synthesized amino acids to the roots, including the accumulation of glutamine. Finally, the regrowth zones of WCR attacked roots show an increase in glutamine turnover which strongly correlates with the induction of indole-3-acetonitrile-dependent auxin biosynthesis. In summary, our findings identify local changes in the auxin flux network as a promising marker for induced WCR tolerance.

Development of forest structure on cleared rainforest land in eastern Australia under different styles of reforestation

Rainforests in eastern Australia have been extensively cleared over the past two centuries. In recent decades, there have been increasing efforts to reforest some of these cleared lands, using a variety of methods, to meet a range of economic and environmental objectives. However, the extent to which the various styles of reforestation restore structure, composition and ecological function to cleared land is not presently understood. In this study, we develop and apply a method for quantifying the structural attributes of reforestation sites in tropical and subtropical Australia. The types of reforestation studied were plantation monocultures, mixed-species cabinet timber plots, diverse restoration plantings and unmanaged regrowth. Two age classes of reforestation were examined: 'young' (5-22 years), incorporating sites from all categories, and 'old' (30-70 years), in which only monoculture plantations and regrowth were represented. A total of 104 sites were surveyed including reference sites in intact rainforest and pasture. Intact rainforest was characterised by a suite of complex structural features including abundant special life forms (vines, epiphytes, hemi-epiphytes and strangler figs), a dense stand of trees in a range of size classes, a closed canopy, a shrubby understorey and a well-developed ground layer of leaf litter and woody debris. These features were lost on conversion to pasture. While all types of reforestation returned some elements of structural complexity to cleared land, young plantation monocultures, cabinet timber plots and young regrowth had a relatively simple structure. These sites typically had a low density of woody stems, a relatively open canopy and grassy ground cover, and lacked large trees, coarse woody debris and most special life forms. Restoration plantings and old regrowth were more complex, with a high density of woody stems, a relatively closed canopy and shrubby understorey. Old monoculture plantations in the tropics had acquired many of the structural attributes of intact forest, however this was not the case in the subtropics, where plantations were subject to more intensive management. The marked differences in structural complexity between sites suggest that the different types of reforestation practiced in eastern Australia are likely to vary considerably in their value as habitat for rainforest biota. (C) 2003 Elsevier Science B.V. All rights reserved.

Vascular endothelial growth factor-B and retinal vascular development in the mouse

Purpose: Vascular endothelial growth factor-A (VEGF-A) is crucial to retinal vascular growth, both normal and pathological. VEGF-B, recently characterized, is reported to be expressed in retinal tissues, but the importance of VEGF-B to retinal vascular development remained unknown. The aim of this study was to analyse retinal vascular growth in the Vegfb (-/-) knockout mouse. Methods: Retinal vascular growth was measured in Vegfb (-/-) knockout mice raised under normal conditions, and Vegfb (-/-) knockout mice with an oxygen-induced proliferative retinopathy. Wild type Vegfb (+/+) mice served as controls. Vessels were perfused with ink and retinal flatmounts secondarily labelled with FITC-lectin (BS-1, Griffonia simplicifolia ). Area and diameter of retinal growth and retinal vascular growth were recorded over days 0-20, and capillary density and mean diameter recorded from day 17 pups. Results: A variety of techniques confirmed that Vegfb (+/+) mice expressed VEGF-B and that VEGF-B expression was absent in Vegfb (-/-) mice. Vegfb (-/-) mice raised in room air showed no significant differences from Vegfb (+/+) controls. No differences were found in oxygen-induced retinopathy between Vegfb (-/-) and Vegfb (+/+) pups in either the extent of the initial oxygen-induced ablation, or in the regrowth of retinal vessels or vitreal (neovascular) sprouts; vitreal sprouts are important markers of the abnormal proliferative response, and are maximally expressed on day 17 in this model of oxygen-induced retinopathy. Conclusions: These results indicate that a lack of VEGF-B does not significantly affect development of the retinal vasculature under normal conditions, nor does it appear to affect the proliferative retinal responses seen in oxygen-induced retinopathy.

Axonal regeneration and lack of astrocytic gliosis in EphA4-deficient mice

Spinal cord injury usually results in permanent paralysis because of lack of regrowth of damaged neurons. Here we demonstrate that adult mice lacking EphA4 (-/-), a molecule essential for correct guidance of spinal cord axons during development, exhibit axonal regeneration and functional recovery after spinal cord hemisection. Anterograde and retrograde tracing showed that axons from multiple pathways, including corticospinal and rubrospinal tracts, crossed the lesion site. EphA4 -/- mice recovered stride length, the ability to walk on and climb a grid, and the ability to grasp with the affected hindpaw within 1-3 months of injury. EphA4 expression was upregulated on astrocytes at the lesion site in wild-type mice, whereas astrocytic gliosis and the glial scar were greatly reduced in lesioned EphA4-/- spinal cords. EphA4 -/- astrocytes failed to respond to the inflammatory cytokines, interferon-gamma or leukemia inhibitory factor, in vitro. Neurons grown on wild-type astrocytes extended shorter neurites than on EphA4 -/- astrocytes, but longer neurites when the astrocyte EphA4 was blocked by monomeric EphrinA5-Fc. Thus, EphA4 regulates two important features of spinal cord injury, axonal inhibition, and astrocytic gliosis.

Regional and population-scale influences on genetic diversity partitioning within costa rican populations of the pioneer tree Vochysia ferruginea mart.

The neotropical pioneer species Vochysia ferruginea is locally important for timber and is being increasingly exploited. The sustainable utilisation of this species would benefit from an understanding of the level and partitioning of genetic diversity within remnant and secondary regrowth populations. We used data from total genome (amplified fragment length polymorphism, AFLP) and chloroplast genome markers to assay diversity levels within seven Costa Rican populations. Significant chloroplast differentiation between Atlantic and Pacific watersheds was observed, suggesting divergent historical origins for these populations. Contemporary gene flow, though extensive, is geographically constrained and a clear pattern of isolation by distance was detectable when an inter-population distance representing gene flow around the central Costa Rican mountain range was used. Overall population differentiation was low (F-ST = 0.15) and within-population diversity high, though variable (H-s=0.16-0.32), which fits with the overall pattern of population genetic structure expected for a widespread, outcrossed tropical tree. However genetic diversity was significantly lower and differentiation higher for recently colonised and disturbed populations compared to that at more established sites. Such a pattern seems indicative of a pioneer species undergoing repeated cycles of colonisation and succession.

Habitat selection and breeding success in a forest-nesting Alcid, the marbled murrelet, in two landscapes with different degrees of forest fragmentation

We studied habitat selection and breeding success in marked populations of a protected seabird (family Alcidae), the marbled murrelet (Brachyramphus marmoratus), in a relatively intact and a heavily logged old-growth forest landscape in south-western Canada. Murrelets used old-growth fragments either proportionately to their size frequency distribution (intact) or they tended to nest in disproportionately smaller fragments (logged). Multiple regression modelling showed that murrelet distribution could be explained by proximity of nests to landscape features producing biotic and abiotic edge effects. Streams, steeper slopes and lower elevations were selected in both landscapes, probably due to good nesting habitat conditions and easier access to nest sites. In the logged landscape, the murrelets nested closer to recent clearcuts than would be expected. Proximity to the ocean was favoured in the intact area. The models of habitat selection had satisfactory discriminatory ability in both landscapes. Breeding success (probability of nest survival to the middle of the chick rearing period), inferred from nest attendance patterns by radio-tagged parents, was modelled in the logged landscape. Survivorship was greater in areas with recent clearcuts and lower in areas with much regrowth, i.e. it was positively correlated with recent habitat fragmentation. We conclude that marbled murrelets can successfully breed in old-growth forests fragmented by logging.

A community-based wildlife survey: the knowledge and attitudes of residents of suburban Brisbane, with a focus on bandicoots

Within the expanding city of Brisbane in south-east Queensland, numerous fragments of native and regrowth vegetation are scattered across the largely urbanised landscape. These fragments provide refuge to a great diversity of native wildlife, and, provide residents with the opportunity to experience nature on their doorstep. To assess the diversity and abundance of this wildlife, recent changes in these parameters, and the value of wildlife and bushland fragments to residents of Brisbane, a questionnaire survey was distributed to 300 households each located adjacent to one of 38 urban bushland fragments. A total of 172 surveys (57%) were returned, producing 768 records of 83 fauna species, dominated by birds and mammals; bandicoots were widely reported from the 38 fragments. Several historical records provided evidence of recent local extinctions within fragments, highlighting the continuing declines in various species of native wildlife within Brisbane. Several human-wildlife conflicts were identified, but overall residents were tolerant of such conflicts. Bandicoots were disliked by a small minority (3%) of residents owing to the holes they dig in lawns and gardens in search of food. and their potential as vectors of ticks. Most respondents expressed ail appreciation for the presence of native wildlife (96%) and bushland fragments (97%) in their local area, emphasising the importance of incorporating human dimension values into the management of this urban biodiversity.

Summer dormancy in Festuca arundinacea Schreb.; the influence of season of sowing and a simulated mid-summer storm on two contrasting cultivars

Due to the shortage of information on summer dormancy in tall fescue (Festuca arundinacea, syn. Lolium arundinaceum), we tested the response of 2 cultivars of differing dormancy expression and growth stage to a range of summer moisture conditions, including full irrigation, drought, and a simulated mid-summer storm and analysed whether traits associated with summer dormancy conferred better survival under severe field drought. Autumn-sown reproductive and younger, spring-sown plants of 2 cultivars, claimed to exhibit contrasting summer dormancy, were established and then tested in summer 2002 under either long drought, drought+ simulated mid-summer storm, or full irrigation. The autumn-sown reproductive plants of cv. Flecha exhibited traits that can be associated with partial summer dormancy since under summer irrigation they reduced aerial growth significantly and exhibited earlier herbage senescence. Moreover, cv. Flecha used 35% less soil water over the first summer. However, the water status of leaf bases of young vegetative tillers of both cultivars was similar under irrigation and also throughout most of the drought (leaf potential and water content maintained over -4MPa and at approx. 1 g H2O/g DM, respectively). The summer-active cv. Demeter did not stop leaf elongation even in drought and produced twice as much biomass as Flecha under irrigation. Cultivar Demeter responded to the simulated storm with a decline in dehydrin expression in leaf bases, whereas no decline occurred in Flecha, presumably because it remained partially dormant. The younger, spring-sown swards of both cultivars had similar biomass production under summer irrigation but whereas Demeter regrew in response to the simulated storm, cv. Flecha did not, indicating that dormancy, although only partially expressed, was reinforced by summer drought. In all trials, cv. Flecha out-yielded Demeter in autumn regrowth. In particular, the severe drought in 2003 caused a 25% loss of the basal cover in cv. Demeter, whereas Flecha fully maintained its sward allowing it to produce a higher post-drought autumn yield. This work links summer dormancy with higher persistence over long, dry summers.

Reoperative parathyroid surgery: The importance of ectopic location and multigland disease

Background: Despite the availability of expert surgeons and preoperative imaging investigations, some patients require reoperation for persistent or recurrent hyperparathyroidisms. Method: Fifty consecutive patients were reviewed. Results: There were 28 persistent cases (24 primary, 4 secondary) and 22 recurrent cases (15 primary, 7 secondary) and 98% had successful surgical treatment. Multigland disease was present in 24 of 39 (62%) of primary cases, 11 of 24 persistent and 13 of 15 recurrent (P < 0.02). Four patients in the recurrent primary group had multiple endocrine neoplasia type 1, whereas the other 20 primary patients had sporadic multigland disease. Multigland disease was present in all secondary cases and was a very important factor in this entire series of patients (70%). Regrowth of a remnant of a gland biopsied or partially resected at an earlier operation was the cause of recurrence in 12 of 15 primary and 2 of 7 secondary cases (P < 0.05). The site of missed glands in persistent disease was ectopic in 60%. Ectopic glands were found in the following sites: intrathyroidal 10 (8 inferior and 2 superior), intrathymic 9, posterior mediastinum 4, base of skull 2, carotid sheath 1 and supernumerary 5. Investigations to locate missing glands were positive in 28 of 43 sestamibi scans (65%), 14 of 34 ultrasound scans (41%), 10 of 24 computed tomography scans (42%) and 11 of 13 selective venous sampling tests (85%). Conclusion: Some persistent cases are unavoidable because of ectopic locations and some recurrences are inevitable because of multigland disease.